Working machine

Abstract

A working machine includes a traveling device to cause a machine body to travel and turn, a working device to attach thereto an attachment to perform work by contacting a target object, and change a posture of the attachment including a position in an up-down direction, a work manual operator to be operated to actuate the working device to change the posture, and a controller configured / programmed to control the working device. The controller is configured / programmed to cause a memory / storage to store actual control information relating to the posture at a time when a predetermined condition which, when satisfied, allows estimation that work is being performed by the attachment, is satisfied, and after the predetermined condition becomes not satisfied and the machine body turns, actuate the working device based on the actual control information to change the posture back to a work posture at the time when the predetermined condition is satisfied.

Description

BACKGROUND OF THE INVENTION1. Field of the Invention

[0001] The present invention relates to working machines such as skid-steer loaders and compact track loaders, and particularly relates to techniques to perform work using each of various types of attachments attached to a working device including arms and the like.2. Description of the Related Art

[0002] Working machines such as skid-steer loaders and compact track loaders each include a machine body, a traveling device to support the machine body to allow the machine body to travel, and a working device attached to the machine body (for example, Japanese Unexamined Patent Application Publication No. 2012-207531). This kind of working machine has one of the attachments which perform various types of work attached to the distal portion of the arms of the working device thereof, and is configured such that the posture, such as the position and orientation, of the attached attachment is changed by the working device and work corresponding to the attachment is performed.

[0003] Some attachments perform work while being moved by the working machine and being kept in the posture in contact with a target object such as a natural object (e.g., earth, soil, plants) or a structure. In the case where such an attachment is attached to the working device of the working machine, the user, for example, operates the working device to bring the attachment into the work posture in contact with the target object, and then manually operates the working machine to travel to perform work using the attachment. Upon the working machine reaching an edge of the worksite, the user manually operates the working machine to turn to change directions of travel of the working machine. In so doing, the user operates the working device to bring the attachment into a non-work posture away from the target object to prevent problems from occurring during the turn. Furthermore, the user, after turning the working machine to change directions, operates the working device to bring the attachment back into the work posture and then causes the working machine to travel and the attachment to resume work. However, it is difficult and tiring for the user to operate the working device to bring the attachment back into the work posture.SUMMARY OF THE INVENTION

[0004] Example embodiments of the present invention make it possible to reduce the burden on the user to operate the working machine and bring the attachment into the work position in a suitable manner.

[0005] A working machine according to an example embodiment of the present invention includes a machine body, a traveling device to cause the machine body to travel and turn, a working device to attach thereto an attachment which is one of a plurality of attachments to perform work by contacting a target object, and change a posture of the attachment attached thereto including a position of the attachment in an up-down direction, a work manual operator to be operated to actuate the working device to change the posture of the attachment, and a controller configured or programmed to control the working device, wherein the controller is configured or programmed to cause a memory and / or a storage to store actual control information relating to the posture of the attachment at a time when a predetermined condition is satisfied, the predetermined condition being a condition which, when satisfied, allows estimation that the work is being performed by the attachment attached to the working device, and after the predetermined condition becomes not satisfied and the machine body turns, actuate the working device based on the actual control information to change the posture of the attachment back to a previous work posture which is the posture of the attachment at the time when the predetermined condition is satisfied.

[0006] In an example embodiment of the present invention, the working machine may further include a detector to detect a posture of the working device that includes a position of the working device in an up-down direction. The controller may be configured or programmed to include, in the actual control information, device information relating to the posture of the working device at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body turns, actuate the working device based on the device information to change the posture of the working device back to the posture of the working device at the time when the predetermined condition is satisfied.

[0007] In an example embodiment of the present invention, the working device may include an arm connected to the machine body swingably in the up-down direction of the machine body, a hitch connected to a distal portion of the arm swingably in the up-down direction and operable to attach and detach the attachment thereto and therefrom, a first actuator to swing the arm, and a second actuator to swing the hitch. The work manual operator may be operable to be operated to actuate the first actuator and / or the second actuator to swing the arm and / or the hitch to change the posture of the attachment that includes the position and an orientation of the attachment. The controller may be configured or programmed to actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

[0008] In an example embodiment of the present invention, the working machine may further include a travel manual operator to be operated to cause the traveling device to cause the machine body to travel and turn. The controller may be configured or programmed to, after the predetermined condition is satisfied, when the travel manual operator is operated to cause the machine body to turn, actuate the first actuator and / or the second actuator to swing the arm and / or the hitch to move the attachment attached to the working device in a direction away from the target object, and when the travel manual operator has not been operated to cause the machine body to turn for a predetermined period or more, or when the travel manual operator is operated to cause the machine body to travel straight after the travel manual operator stops being operated to cause the machine body to turn, actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

[0009] In an example embodiment of the present invention, the controller may be configured or programmed to include, in the actual control information, device information relating to an actuated position of the first actuator and / or an actuated position of the second actuator at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body turns, change the actuated position of the first actuator and / or the actuated position of the second actuator each back to the actuated position indicated by the device information.

[0010] In an example embodiment of the present invention, the working machine may further include an input interface to receive input of information relating to the attachment attached to the working device. The controller may be configured or programmed to, in a case that the attachment corresponding to the information inputted via the input interface is a specific attachment, keep an orientation of the attachment by actuating the second actuator to swing the hitch when actuating the first actuator to swing the arm to raise or lower the attachment.

[0011] In an example embodiment of the present invention, the working machine may further include a first detector to detect a position of the arm, and a second detector to detect a position of the hitch. The controller may be configured or programmed to include, in the predetermined condition, a condition that an actuated position of the first actuator and / or an actuated position of the second actuator determined based on a detection result from the first detector and / or a detection result from the second detector each has / have been in a corresponding actuation range for a predetermined period.

[0012] In an example embodiment of the present invention, the working machine may further include an input interface to receive input of information relating to the attachment attached to the working device. The controller may be configured or programmed to define the actuation range corresponding to the first actuator and / or the second actuator based on the information inputted via the input interface.

[0013] In an example embodiment of the present invention, the controller may be configured or programmed to include, in the predetermined condition, a condition that the machine body is traveling straight.

[0014] In an example embodiment of the present invention, the working machine may further include a travel manual operator to be operated to cause the traveling device to cause the machine body to travel and turn. The controller may be configured or programmed to, when the predetermined condition becomes not satisfied because, while the machine body is traveling straight, the work manual operator is operated to swing the arm to move the attachment attached to the working device in a direction away from the target object, after the travel manual operator is operated to cause the machine body to turn, upon passage of a predetermined period or more since the travel manual operator stopped being operated to cause the machine body to turn, or upon operation of the travel manual operator to cause the machine body to travel straight after stoppage of operation of the travel manual operator to cause the machine body to turn, actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

[0015] In an example embodiment of the present invention, the working machine may further include a power output circuit to output power to an auxiliary actuator provided in or on the attachment to drive the attachment, and an input interface to receive input of information relating to the attachment attached to the working device. The controller may be configured or programmed to, in a case that the attachment corresponding to the information inputted via the input interface is a specific attachment including the auxiliary actuator, include, in the predetermined condition, a condition that the controller has been in a predetermined mode in which the controller keeps constant a state of power output to the auxiliary actuator for a predetermined period.

[0016] In an example embodiment of the present invention, the working machine may further include an input interface to receive input of information relating to the attachment attached to the working device. The working device may be operable to change an orientation of the attached attachment that is included in the posture of the attached attachment. The controller may be configured or programmed to define, based on the information inputted via the input interface, a turn posture of the attachment that includes the position and the orientation of the attachment when the machine body turns, and, when the machine body turns, actuate the working device to change the posture of the attachment to the turn posture.

[0017] The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A more complete appreciation of example embodiments of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings described below.

[0019] FIG. 1 illustrates an example of a work-related hydraulic circuit of a working machine.

[0020] FIG. 2 illustrates an example of a travel-related hydraulic circuit of a working machine.

[0021] FIG. 3 is a block diagram showing an example of an electrical configuration of a working machine.

[0022] FIG. 4 illustrates an example of a hydraulic circuit to actuate a latch cylinder.

[0023] FIG. 5 illustrates an example of attachment information and control information.

[0024] FIG. 6 illustrates an example of an input screen displaying icons of attachments.

[0025] FIG. 7 illustrates an example of actual control information.

[0026] FIG. 8A is a flowchart showing an example of operation of a working machine.

[0027] FIG. 8B is a flowchart continuing from FIG. 8A.

[0028] FIG. 9 shows an example of a work condition determining process in FIG. 8A.

[0029] FIG. 10 illustrates an example of a monitor screen.

[0030] FIG. 11 illustrates another example of a work-related hydraulic circuit of a working machine.

[0031] FIG. 12 is a side view of a working vehicle.

[0032] FIG. 13 is an elevational view of a quick hitch.DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0033] Example embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. The drawings are to be viewed in an orientation in which the reference numerals are viewed correctly.

[0034] Example embodiments of the present invention will now be described with reference to the accompanying drawings as necessary.

[0035] FIG. 12 is a side view of a working machine 1 of the present example embodiment. In the present example embodiment, a compact track loader is illustrated as an example of the working machine 1. However, the working machine according to an example embodiment of the present invention is not limited to a compact track loader, and may be, for example, some other construction machine, agricultural machine, or working machine such as a skid-steer loader, a backhoe, or a tractor. The left direction, right direction, the direction approaching the viewer of FIG. 12, and the direction away from the viewer of FIG. 12 are respectively forward, rearward, left and right directions of the working machine 1. The direction perpendicular to the front-back direction and the up-down direction of the working machine 1 is hereinafter referred to as a machine body width direction.

[0036] The working machine 1 includes a machine body 2, a cabin 3, a working device 4, traveling device(s) 5, and a prime mover 6. The cabin 3 is provided on the machine body 2. The cabin 3 includes a seat 8 therein. The prime mover 6 is provided at a rear portion of the machine body 2. The prime mover 6 is a power source of the working machine 1. In the present example embodiment, the prime mover 6 includes a diesel engine. However, the prime mover 6 may be another internal combustion engine (engine) such as a gasoline engine, and / or may be a motor such as an electric motor.

[0037] The traveling devices 5 are respectively provided on the left and right sides of the machine body 2, and support the machine body 2 such that the machine body 2 is allowed to travel. That is, a pair of the left and right traveling devices 5 are provided. The traveling devices 5 include crawler traveling devices. Note that the traveling devices 5 are not limited to crawler traveling devices, and may be wheeled traveling devices including front wheel(s) and rear wheel(s), or may be semi-crawler traveling devices in which the front wheels or the rear wheels are crawler wheels.

[0038] When the left-side traveling device (left traveling device) 5 and the right-side traveling device (right traveling device) 5 are both driven to rotate forward or both driven to rotate reversely, or when one of them is driven to rotate forward and the other is driven to rotate reversely or is stopped, the machine body 2 (working machine 1) travels forward, travels rearward, or turns left or right. That is, the traveling devices 5 are operable to cause the machine body 2 to travel and turn. Furthermore, as the speed of rotation of the left and right traveling devices 5 changes, the travel speed of the machine body 2 changes, whereas, as the left and right traveling devices 5 stop, the machine body 2 stops. In this way, the traveling devices 5 change the traveling state such as the direction of travel, the travel speed, and the stopping of the machine body 2.

[0039] The working device 4 is provided on the machine body 2. The working device 4 includes arms 10, first links 12, second links 13, lift cylinders 14, tilt cylinders 15, a hitch 16, and an attachment 11. Of these, the arms 10, the first links 12, the second links 13, the lift cylinders 14, and the tilt cylinders 15 are provided on the left and the right of the cabin 3. The left and right arms 10 are connected by a connector.

[0040] The arms 10 are connected to the machine body 2 swingably in the up-down direction relative to the machine body 2. Specifically, the first links 12 and the second links 13 support proximal portions (rear portions) of the arms 10 via shafts such that the arms 10 are swingable in the up-down direction. First ends of the lift cylinders 14 are rotatably connected to the arms 10 via shafts, and opposite second ends of the lift cylinders 14 are rotatably connected to a lower rear portion of the machine body 2 via shafts. The lift cylinders 14 are hydraulic actuators (first actuators) to cause the arms 10 to swing in the up-down direction by extending and retracting.

[0041] The hitch 16 is connected to distal portions of the arms 10 swingably in the up-down direction relative to the distal portion of the arms 10. Specifically, first ends of the tilt cylinders 15 and the distal portions of the arms 10 are respectively rotatably connected to a rear portion of the hitch 16 via shafts. Opposite second ends of the tilt cylinders 15 are rotatably connected to central curved portions of the arms 10 via shafts and brackets. The tilt cylinders 15 are hydraulic actuators (second actuators) to cause the hitch 16 to swing in the up-down direction by extending and retracting. The attachment 11 is attached to the front surface of the hitch 16. The hitch 16 is a linkage to attach and detach the attachment 11 thereto and therefrom.

[0042] FIG. 13 is an elevational view of the quick hitch 16. Specifically, FIG. 13 shows the hitch 16 as seen from the machine body 2 of the working machine 1 in FIG. 12. The hitch 16 includes brackets 30, latching mechanisms 31, a latch cylinder 17, and the like. A pair of the left and right brackets 30 and a pair of the left and right latching mechanisms 31 are provided. The left and right brackets 30 are connected by a beam 39. The distal portions of the left and right arms 10 and the first ends of the left and right tilt cylinders 15 are connected to the left and right brackets 30 via shafts (FIG. 12). The left and right latching mechanisms 31 are respectively provided on the left and right brackets 30.

[0043] Each latching mechanism 31 includes a latch lever 32, a latch pin 33 and the like. An upper portion of the latch lever 32 is rotatably connected to the corresponding bracket 30 via a shaft. The latch pin 33 is held swingably up and down by the bracket 30. A lower end portion of a coil spring 34 is connected to an upper end portion of the latch pin 33 via a shaft, and an upper end portion of the coil spring 34 is connected to a central portion of the latch lever 32 via a shaft.

[0044] The latch cylinder 17 is a hydraulic cylinder (hydraulic actuator) to actuate the latching mechanisms 31 between a latching state and an unlatching state. A first end (distal portion of the rod) of the latch cylinder 17 is rotatably connected to a lower end portion of one of the latch levers 32 via a shaft. An opposite second end (bottom portion of the cylinder case) of the latch cylinder 17 is rotatably connected to a lower end portion of the other the latch levers 32 via a shaft.

[0045] As represented by a solid line in FIG. 13, when the latch cylinder 17 extends with the front surfaces of the brackets 30 abutting a base plate 9 connected to the back surface of the attachment 11, the latch levers 32 rotate to descend, causing the latch pins 33 to be inserted into through-holes 9h in a lower end portion of the base plate 9. With this, the latching mechanisms 31 are brought into a latching state in which the attachment 11 is secured to the brackets 30 (attached to the hitch 16).

[0046] As represented by a dot-dot-dash line in FIG. 13, when the latch cylinder 17 retracts, the latch levers 32 rotate to ascend, allowing the latch pins 33 to be removed from the through-holes 9h of the base plate 9 by the elastic force of the coil springs 34. With this, the latching mechanisms 31 are brought into an unlatching state in which the attachment 11 is not secured to the brackets 30, allowing the attachment 11 to be detached from the hitch 16.

[0047] Since the above-described hitch 16 allows the attachment 11 to be easily replaced with another one, the hitch 16 is called a “quick hitch” or “quick changer”. Note that another actuator such as a hydraulic motor may be used instead of the latch cylinder 17, or an electric actuator such as an electric motor or an electric cylinder may be used instead of the latch cylinder 17.

[0048] When the arms 10 are caused to swing in the up-down direction by the lift cylinders 14 with the attachment 11 attached to the hitch 16 as described above, the attachment 11 is raised or lowered, and the position (height) of the attachment 11 in the up-down direction relative to the machine body 2 and to the target object and the position of the attachment 11 in the front-back direction are changed. When the hitch 16 is caused to swing in the up-down direction by the tilt cylinders 15, the attachment 11 also swings in the up-down direction, and the tilt angle of the attachment 11, i.e., the orientation (which includes the pitch angle relative to the front-rear direction) of the attachment 11 relative to the machine body 2 and the target object, is changed.

[0049] Thus, the working device 4 is a posture changing device to change the posture including the position and the orientation of the attachment 11. Furthermore, with regard to the working device 4, since the arms 10 and the hitch 16 are individually swingable, the working device 4 can, when at least one of the arms 10 or the hitch 16 swing(s) with the attachment 11 attached, change the posture including at least one of the height or the orientation of the attachment 11 relative to the machine body 2 and the target object. The attachment 11 is changed between a work posture in which the working device 4 can perform work on a target object and a non-work posture in which the working device 4 does not perform work. The working machine 1 includes a working unit 4U including the working device 4 and the attachment 11 attached to the working device 4.

[0050] The working device 4 (hitch 16) is operable to attach thereto and detach therefrom each of attachments 11 to perform various types of work, and a selected one of the attachments 11 is attached to the working device (hitch 16). The attachment 11 is a working tool to perform work. The working machine 1 performs work corresponding to the attachment 11 attached to the working device 4.

[0051] Examples of the attachment 11 attachable to the working device 4 include attachments 11 with no actuators and attachments 11 including an actuator. For example, buckets, pallet forks, and the like do not include actuators. For example, sweepers, snow blowers, snow blades, angle brooms, mowers, plows, skid cutters, breakers, earth augers, spreaders, and the like each include an actuator and are driven by power from the actuator. The actuator in or on the attachment 11 is actuated by power from the working machine 1.

[0052] For example, spreaders and the like are non-contact work attachments 11 which perform work such as spreading fertilizer or agricultural chemicals while being moved by the working machine 1 without contacting the target object such as earth or crops.

[0053] For example, buckets, sweepers, snow blowers, snow blades, angle brooms, hopper brooms, mowers, plows, skid cutters, and the like are contacting / moved work attachments 11 to perform work such as carrying, removing, adjusting, or destroying a target object such as earth, soil, or plants while being moved by the working machine 1 and being kept in contact with the target object. In the example shown in FIG. 12, a sweeper, which is a contacting / moved work attachment 11 including an auxiliary actuator 27, is attached to the working device 4 (hitch 16).

[0054] In the case where a contacting / moved work attachment 11 is attached to the working device 4 of the working machine 4, the user, for example, operates the working device 4 to bring the attachment 11 into a work posture in contact with the target object, and then manually operates the working machine 1 to travel to perform work using the attachment 11. Upon the working machine 1 reaching an edge of the worksite, the user manually operates the working device 4 to or causes the working device 4 to automatically bring the attachment 11 into a non-work posture away from the target object, and then manually operates the working machine 1 to turn to change the direction of travel of the working machine 1. Furthermore, the user, after turning the working machine 1 to change the direction of travel, manually operates the working device 4 to or causes the working device 4 to automatically bring the attachment 11 back into the work posture, and then manually operates the working machine 1 to travel and the attachment 11 to resume work.

[0055] In the present example embodiment, the actuator(s) provided in or on the drive attachment 11 is a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder. For example, an auxiliary actuator 27 provided in or on the sweeper (attachment) 11 shown in FIG. 12 is a hydraulic motor which drives the sweeper 11.

[0056] The auxiliary actuator 27 provided in or on the drive attachment 11 is actuated by hydraulic fluid supplied from the working machine 1. As shown in FIG. 12, the machine body 2 of the working machine 1 is provided with AUX port(s) (auxiliary port(s)) 25 at a front portion thereof. The AUX ports 25 allow hydraulic fluid to flow to and from the auxiliary actuator 27. The AUX ports 25 include a first AUX port 25a and a second AUX port 25b. The attachment 11 includes a first hydraulic port and a second hydraulic port. Each port includes a coupler.

[0057] For example, the user or the like connects an external fluid passage 26a including a hose or the like to the first AUX port 25a and to the first hydraulic port of the attachment 11, and connects an external fluid passage 26b to the second hydraulic port of the attachment 11 and to the second AUX port 25b. With this, hydraulic fluid is allowed to flow out (to be supplied) from the working machine 1 to the auxiliary actuator 27 of the attachment 11, and is allowed to flow from the auxiliary actuator 27 into (returns to) the working machine 1. This defines a hydraulic circuit between the working machine 1 and the auxiliary actuator 27, so that the auxiliary actuator 27 can be actuated by hydraulic fluid from the working machine 1 to cause the attachment 11 to perform work. In the example in FIG. 12, the above circuit allows a brush 11b, which is a driven portion of the sweeper, to be driven to rotate by power from the auxiliary actuator 27 and to perform work to remove a target object such as dust on a ground J.

[0058] As described above, the actuators 14, 15 and 27 provided in or on the working device 4 and the attachment 11 are actuated by hydraulic fluid to cause the working device 4 and the attachment 11 to perform work. Note that some attachments are electric-driven attachments including electric actuator(s) such as an electric motor and / or an electric cylinder. Such an electric-driven attachment performs work in the following manner. Electricity from a battery provided in or on the working machine 1 is inputted into an electric actuator via an electric connector and an electric cable in or on the machine body 2, so that the electric actuator is actuated and the attachment is driven by power from the actuator, making it possible to perform work.

[0059] FIG. 1 illustrates a work-related hydraulic circuit 4A included in the working machine 1. This hydraulic circuit 4A causes the working device 4 and the attachment 11 to operate. The working machine 1 includes a pilot pump P1 and a main pump P2. For example, the pilot pump P1 is a fixed displacement hydraulic pump, and the main pump P2 is a variable displacement hydraulic pump.

[0060] The pilot pump P1 is actuated by power from the prime mover 6 to deliver hydraulic fluid stored in a hydraulic fluid tank T to a fluid passage 40. The hydraulic fluid delivered by the pilot pump P1 is pilot fluid to control various hydraulic devices provided in the working machine 1. The pressure of pilot fluid is a pilot pressure.

[0061] The main pump P2 is actuated by power from the prime mover 6 to deliver hydraulic fluid stored in the hydraulic fluid tank T to a main fluid passage 45. The hydraulic fluid delivered by the main pump P2 is used to actuate the lift cylinders 14 and the tilt cylinders 15 of the working device 4, as well as hydraulic device(s) such as the auxiliary actuator 27 provided in or on the attachment 11.

[0062] The working machine 1 includes a plurality of control valves 60A, 60B and 60C. The plurality of control valves 60A, 60B and 60C include a lift control valve 60A, a tilt control valve 60B, and an auxiliary (AUX) control valve 60C. The plurality of control valves 60 are each connected to the main fluid passage 45. The lift control valve 60A controls the flow rate (output) and the supply direction of hydraulic fluid supplied from the main fluid passage 45 to the lift cylinders 14 to actuate the lift cylinders 14. The tilt control valve 60B controls the flow rate (output) and the supply direction of hydraulic fluid supplied from the main fluid passage 45 to the tilt cylinders 15 to actuate the tilt cylinders 15. The AUX control valve 60C controls the flow rate and the supply direction of the hydraulic fluid supplied from the main fluid passage 45 to the auxiliary actuator 27 via the AUX port(s) 25 to actuate the auxiliary actuator 27.

[0063] The lift control valve 60A is connected to the lift cylinders 14 via a plurality of fluid passages 64a and 64b. The lift control valve 60A is a pilot-operated, direct-acting spool three-position switching valve. The lift control valve 60A includes a plurality of work pressure receivers 61a and 61b, and switches between a third position (neutral position) 61c, a first position 61d different from the third position 61c, and a second position 61e different from the third position 61c and the first position 61d depending on the pilot pressure acting on the work pressure receiver(s) 61a and / or 61b. When the lift control valve 60A is in the third position 61c, hydraulic fluid is not supplied from the main fluid passage 45 to the lift cylinders 14.

[0064] When the lift control valve 60A switches to the first position 61d or the second position 61e, hydraulic fluid from the main fluid passage 45 is supplied to the lift cylinders 14 via the lift control valve 60A and the fluid passage 64a or 64b. When the opening of the lift control valve 60A changes according to the pilot pressure while the lift control valve 60A is in the first position 61d or the second position 61e, the flow rate of hydraulic fluid from the main fluid passage 45 to the lift cylinders 14 is changed. Thus, the lift control valve 60A controls the supply direction and the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the lift cylinders 14 according to the pilot pressure acting on the work pressure receiver(s) 61a and / or 61b to cause the lift cylinders 14 to extend or retract.

[0065] More specifically, when the lift control valve 60A switches to the first position 61d, hydraulic fluid from the main fluid passage 45 flows through the lift control valve 60A and the fluid passage 64a and is supplied to the rod-side chambers of the lift cylinders 14. With this, the lift cylinders 14 retract, the arms 10 swing downward, and the attachment 11 attached to the hitch 16 lowers. The hydraulic fluid pushed out of the cap-side chambers of the lift cylinders 14 flows through the fluid passage 64b and is drained from the lift control valve 60A.

[0066] When the lift control valve 60A switches to the second position 61e, hydraulic fluid from the main fluid passage 45 flows through the lift control valve 60A and the fluid passage 64b, and is supplied to the cap-side chambers of the lift cylinders 14. With this, the lift cylinders 14 extend, the arms 10 swing upward, and the attachment 11 attached to the hitch 16 is raised. The hydraulic fluid pushed out from the rod-side chambers of the lift cylinders 14 flows through the fluid passage 64a and is drained from the lift control valve 60A.

[0067] The tilt control valve 60B is connected to the tilt cylinders 15 by a plurality of fluid passages 65a and 65b. The tilt control valve 60B is a pilot-operated, direct-acting spool three-way switching valve. The tilt control valve 60B includes a plurality of work pressure receivers 62a and 62b, and switches between a third position (neutral position) 62c, a first position 62d different from the third position 62c, and a second position 62e different from the third position 62c and the first position 62d, depending on the pilot pressure acting on the work pressure receiver(s) 62a and / or 62b. When the tilt control valve 60B is in the third position 62c, hydraulic fluid is not supplied from the main fluid passage 45 to the tilt cylinders 15.

[0068] The tilt control valve 60B switches to the first position 62d or the second position 62e to allow hydraulic fluid from the main fluid passage 45 to be supplied to the tilt cylinders 15 via the tilt control valve 60B and the fluid passage 65a or 65b. When the opening of the tilt control valve 60B changes according to the pilot pressure while the tilt control valve 60B is in the first position 62d or the second position 62e, the flow rate of hydraulic fluid from the main fluid passage 45 to the tilt cylinders 15 is changed. Thus, the tilt control valve 60B controls the supply direction and the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the tilt cylinders 15 according to the pilot pressure acting on the work pressure receiver(s) 62a and / or 62b to cause the tilt cylinders 15 to extend or retract.

[0069] More specifically, when the tilt control valve 60B switches to the first position 62d, hydraulic fluid from the main fluid passage 45 flows through the tilt control valve 60B and the fluid passage 65b, and is supplied to the cap-side chambers of the tilt cylinders 15. With this, the tilt cylinders 15 extend, the hitch 16 swings downward, the tilt angle of the attachment 11 attached to the hitch 16 decreases, and the orientation is changed such that the front portion of the attachment 11 lowers. The hydraulic fluid pushed out of the rod-side chambers of the tilt cylinders 15 flows through the fluid passage 65b and is drained from the tilt control valve 60B.

[0070] When the tilt control valve 60B switches to the second position 62e, hydraulic fluid from the main fluid passage 45 flows through the tilt control valve 60B and the fluid passage 65a, and is supplied to the rod-side chambers of the tilt cylinders 15. With this, the tilt cylinders 15 retract, the hitch 16 swings upward, the tilt angle of the attachment 11 attached to the hitch 16 increases, and the orientation is changed such that the front portion of the attachment 11 is raised. The hydraulic fluid pushed out from the cap-side chambers of the tilt cylinders 15 flows through the fluid passage 65a and is drained from the tilt control valve 60B.

[0071] The AUX control valve 60C is connected to the AUX ports 25 via a plurality of AUX fluid passages (auxiliary fluid passages) 66a and 66b. Specifically, a first port of the AUX control valve 60C and the first AUX port 25a are connected via the AUX fluid passage 66a, and a second port of the AUX control valve 60C and the second AUX port 25b are connected via the AUX fluid passage 66b. The AUX control valve 60C is a pilot-operated, direct-acting spool three-position switching valve. The AUX control valve 60C includes a plurality of AUX pressure receivers 63a and 63b, and switches between a third position (neutral position) 63c, a first position 63d different from the third position 63c, and a second position 63e different from the third position 63c and the first position 63d, depending on the pilot pressure acting on the AUX pressure receiver(s) 63a and / or 63b.

[0072] When the AUX control valve 60C is in the third position 63c, hydraulic fluid is not supplied to the auxiliary actuator 27 from the main fluid passage 45 via the AUX fluid passage 66a or 66b and the AUX port(s) 25. When the AUX control valve 60C switches to the first position 63d or the second position 63e, hydraulic fluid from the main fluid passage 45 is supplied to the auxiliary actuator 27 via the AUX control valve 60C, the AUX fluid passage 66a or 66b, and the corresponding AUX port 25, and the supply direction of the hydraulic fluid changes.

[0073] More specifically, when the AUX control valve 60C switches to the first position 63d, hydraulic fluid from the main fluid passage 45 is supplied to the auxiliary actuator 27 via the AUX control valve 60C, the AUX fluid passage 66a and the first AUX port 25a, and return fluid from the auxiliary actuator 27 flows through the second AUX port 25b and the AUX fluid passage 66b and is drained from the AUX control valve 60C. When the AUX control valve 60C switches to the second position 63e, hydraulic fluid from the main fluid passage 45 is supplied to the auxiliary actuator 27 via the AUX control valve 60C, the AUX fluid passage 66b and the second AUX port 25b, and return fluid from the auxiliary actuator 27 flows through the first AUX port 25a and the AUX fluid passage 66a and is drained from the AUX control valve 60C.

[0074] When the opening of the AUX control valve 60C changes according to the pilot pressure while the AUX control valve 60C is in the first position 63d or the second position 63e, the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the auxiliary actuator 27 via the corresponding AUX port 25 is changed.

[0075] As described above, the AUX control valve 60C controls the supply direction and the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the auxiliary actuator 27 via the corresponding AUX fluid passage 66a or 66b and the corresponding AUX port 25 according to the pilot pressure acting on the AUX pressure receiver(s) 63a and / or 63b to actuate the auxiliary actuator 27. The AUX control valve 60C, the AUX fluid passages 66a and 66b, and the AUX ports 25 define an auxiliary hydraulic circuit (power output circuit) 4B to supply (output) hydraulic fluid (i.e., power) to the auxiliary actuator 27 of the attachment 11, and the auxiliary hydraulic circuit 4B is provided in the working machine 1.

[0076] The working machine 1 includes pressure detectors 70a and 70b. The pressure detectors 70a and 70b include pressure sensors. The pressure detector 70a is provided in the AUX fluid passage 66a to detect an AUX pressure (auxiliary pressure) which is the pressure of hydraulic fluid flowing from the AUX control valve 60C through the AUX fluid passage 66a and is supplied to the auxiliary actuator 27 of the attachment 11. The pressure detector 70b is provided in the AUX fluid passage 66b to detect an AUX pressure which is the pressure of hydraulic fluid flowing from the AUX control valve 60C through the AUX fluid passage 66b and is supplied to the auxiliary actuator 27. During work performed by the attachment 11 including the auxiliary actuator 27, the AUX pressure detected by the pressure detector(s) 70a and / or 70b can be regarded as a load on the attachment 11.

[0077] Note that the pressure detectors 70a and 70b also detect the pressure of hydraulic fluid (return fluid) flowing from the auxiliary actuator 27 through the corresponding AUX fluid passage 66a or 66b and returning to the AUX control valve 60C. However, since the pressure is equal to or substantially equal to the atmospheric pressure, the pressure is not regarded as auxiliary pressure by a controller 20.

[0078] The working machine 1 includes a plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b. The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b are proportional valves in each of which the solenoid is energized and the opening is changed according to a control signal (electric current signal) inputted thereto. The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b are each connected to fluid passages 40b and 40c branching from the fluid discharge passage 40, and a change in the opening thereof changes the pilot pressure of pilot fluid supplied from the fluid discharge passage 40. Specifically, as the electric current value of the control signal inputted increases, the opening of the plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b increases, allowing pilot fluid from the fluid discharge passage 40 to be outputted with an increased pilot pressure.

[0079] The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b include lift solenoid valves 76a and 76b, tilt solenoid valves 77a and 77b, and AUX solenoid valves 78a and 78b. The lift solenoid valves 76a and 76b are respectively connected to the work pressure receivers 61a and 61b of the lift control valve 60A via fluid passages. The tilt solenoid valves 77a and 77b are respectively connected to the work pressure receivers 62a and 62b of the tilt control valve 60B via fluid passages. The AUX solenoid valves 78a and 78b are respectively connected to the AUX pressure receivers 63a and 63b of the AUX control valve 60C via fluid passages.

[0080] When the opening of the lift solenoid valve 76a is greater than 0 (zero), pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 61a from the lift solenoid valve 76a. In so doing, a pilot pressure corresponding to the opening of the lift solenoid valve 76a acts on the work pressure receiver 61a. When the pilot pressure acting on the work pressure receiver 61a is equal to or higher than a predetermined value, the spool of the lift control valve 60A moves, and the lift control valve 60A switches to the first position 61d. With this, the lift cylinders 14 retract and the attachment 11 lowers, and therefore the lift solenoid valve 76a is a solenoid valve to lower the attachment.

[0081] Similarly, when the opening of the lift solenoid valve 76b increases, pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 61b from the lift solenoid valve 76b, and the lift control valve 60A switches to the second position 61e. With this, the lift cylinders 14 extend and the attachment 11 is raised, and therefore the lift solenoid valve 76b is a solenoid valve to raise the attachment.

[0082] Similarly, when the opening of the tilt solenoid valve 77a increases, pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 62a from the tilt solenoid valve 77a, and the tilt control valve 60B switches to the first position 62d. With this, the tilt cylinders 15 extend and the tilt angle of the attachment 11 decreases, and therefore the tilt solenoid valve 77a is a solenoid valve to lower the front portion of the attachment. When the opening of the tilt solenoid valve 77b increases, pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 62b from the tilt solenoid valve 77b, and the tilt control valve 60B switches to the second position 62e. With this, the tilt cylinders 15 retract and the tilt angle of the attachment 11 increases, and therefore the tilt solenoid valve 77b is a solenoid valve to raise the front portion of the attachment.

[0083] Similarly, when the opening of the AUX solenoid valve 78a increases, pilot fluid from the fluid discharge passage 40 acts on the AUX pressure receiver 63a via the AUX solenoid valve 78a, and the AUX control valve 60C switches to the first position 63d. With this, hydraulic fluid is supplied from the AUX control valve 60C to the auxiliary actuator 27 via the AUX fluid passage 66a and the first AUX port 25a. When the opening of the AUX solenoid valve 78b increases, pilot fluid from the fluid discharge passage 40 acts on the AUX pressure receiver 63b via the AUX solenoid valve 78b, and the AUX control valve 60C switches to the second position 63e. With this, hydraulic fluid is supplied from the AUX control valve 60C to the auxiliary actuator 27 via the AUX fluid passage 66b and the second AUX port 25b.

[0084] The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b change the pilot pressure to act on the corresponding pressure receivers 61a, 61b, 62a, 62b, 63a and 63b according to the control signals inputted thereto to change the flow rate of hydraulic fluid from the corresponding control valves 60A, 60B and 60C to the corresponding actuators 14, 15 and 27.

[0085] The working machine 1 includes a work manual operator (work manual operator unit) 67 and the controller 20. The work manual operator 67 is a manual operator to be operated to actuate the working device 4 to cause the working device 4 to freely change the posture of the attachment 11, and to control the swinging of the arms 10 and the hitch 16. The work manual operator 67 includes a digital joystick. The work manual operator 67 includes a work operating lever 67a and a sensor 67b. The work operating lever 67a is a manual operator (work manual operator) to be operated by the driver of the working machine, and is provided in the vicinity of the seat 8 inside the cabin 3. The work operating lever 67a can be operated not only forward and rearward from a neutral position, but also leftward and rightward from the neutral position.

[0086] The sensor 67b includes at least one of an angle sensor or an electric circuit, detects the operation direction and the operation angle (angle of pivoting) of the work operating lever 67a, and outputs a detection signal (electric signal) corresponding to the operation direction and the operation angle. The controller 20 determines the operation direction and the operation angle of the work operating lever 67a based on the detection signal outputted from the sensor 67b, and calculates the ratio of the operation angle to the maximum angle of pivoting of the work operating lever 67a as the operation amount of the work operating lever 67a.

[0087] The controller 20 then inputs a control signal into the lift solenoid valve 76a or 76b or the tilt solenoid valve 77a or 77b according to the operation direction and the operation amount of the work operating lever 67a to open the solenoid valve. With this, a corresponding one of the lift control valve 60A and the tilt control valve 60B switches to the first position 61d, 62d or the second position 61e, 62e, the lift cylinders 14 or the tilt cylinders 15 extend or retract, the arms 10 or the hitch 16 swing(s) in the corresponding direction, and the position including the height or the orientation (tilt angle) of the attachment 11 attached to the hitch 16 is changed.

[0088] Specifically, when the work operating lever 67a is pivoted forward, the controller 20 inputs a control signal into the lift solenoid valve 76a according to the operation amount of the work operating lever 67 to open the lift solenoid valve 76a. With this, the lift control valve 60A switches to the first position 61d, the lift cylinders 14 retract, the arms 10 swing downward, the attachment 11 lowers, and the height of the attachment 11 decreases. In so doing, the attachment 11 is positioned somewhat forward.

[0089] When the work operating lever 67a is pivoted rearward, the controller 20 inputs a control signal into the lift solenoid valve 76b according to the operation amount of the work operating lever 67a to open the lift solenoid valve 76b. With this, the lift control valve 60A switches to the second position 61e, the lift cylinders 14 extend, the arms 10 swing upward, the attachment 11 is raised, and the height of the attachment 11 increases. In so doing, the attachment 11 is positioned somewhat rearward.

[0090] When the work operating lever 67a is pivoted leftward, the controller 20 inputs a control signal into the tilt solenoid valve 77a according to the operation amount of the work operating lever 67a to open the tilt solenoid valve 77a. With this, the tilt control valve 60B switches to the first position 62d, the tilt cylinders 15 extend, and the hitch 16 swings downward, so that the orientation of the attachment 11 is changed such that the front portion of the attachment 11 lowers.

[0091] When the work operating lever 67a is pivoted rightward, the controller 20 inputs a control signal into the tilt solenoid valve 77b according to the operation amount of the work operating lever 67a to open the tilt solenoid valve 77b. With this, the tilt control valve 60B switches to the second position 62e, the tilt cylinders 15 retract, the hitch 16 swings upward, so that the orientation of the attachment 11 is changed such that the front portion of the attachment 11 is raised.

[0092] Note that when the controller 20 causes the arms 10 to swing, the controller 20 causes the hitch 16 to swing so that the orientation of the attachment 11 is not changed. That is, the controller 20, when causing the arms 10 to swing by inputting a control signal into one of the lift solenoid valves 76a and 76b, the controller 20 also inputs a control signal into a corresponding one of the tilt solenoid valves 77a and 77b that corresponds to the swinging direction of the arms 10 to cause the hitch 16 to swing, thus keeping the orientation of the attachment 11 constant. This eliminates or reduces the likelihood that, when the arms 10 swing, the attachment 11 will tilt and accidentally contact a target object or surrounding objects and be damaged. As described above, the controller 20 controls actuation of the working device 4 in response to manual operation of the work manual operator 67 (work operating lever 67a). The controller 20 also automatically controls actuation of the working device 4.

[0093] The working machine 1 includes an AUX output switch 73b. The AUX output switch 73b is an operating switch to be operated by the driver. The AUX output switch 73b is turned ON to start supplying hydraulic fluid to the corresponding AUX port 25, and is turned OFF to stop supplying the hydraulic fluid.

[0094] When the controller 20 is in an AUX mode in which the attachment 11 including the auxiliary actuator 27 is allowed to be used with the working machine 1, if the AUX output switch 73b is turned ON, the controller 20 inputs a control signal into one of the AUX solenoid valves 78a and 78b to open the solenoid valve. With this, the AUX control valve 60C switches to the first position 63d or the second position 63e, and hydraulic fluid is supplied from the AUX control valve 60C to the corresponding AUX port 25 via the AUX fluid passage 66a or the AUX fluid passage 66b. In so doing, if the AUX ports 25 and hydraulic ports of the attachment 11 are connected by the external fluid passages 26, hydraulic fluid is supplied from the corresponding AUX port 25 to the auxiliary actuator 27 of the attachment 11 via the corresponding external fluid passage 26 and the like, the auxiliary actuator 27 is actuated, and the attachment 11 is driven.

[0095] When the controller 20 is in the AUX mode, if the AUX output switch 73b is turned OFF, the controller 20 stops inputting the control signal into the AUX solenoid valve 78a or 78b to close the AUX solenoid valve 78a or 78b. With this, the AUX control valve 60C switches to the third position 63c, and the supply of hydraulic fluid from the AUX control valve 60C to the AUX port 25 is stopped. Thus, the supply of hydraulic fluid to the auxiliary actuator 27 of the attachment 11 is also stopped, the auxiliary actuator 27 stops, and the attachment 11 stops.

[0096] The controller 20 inputs a control signal into at least one of the lift solenoid valve 76b or 76b or the tilt solenoid valve 77a or 77b according to the AUX pressure detected by the pressure detectors 70a and 70b to adjust the opening of the solenoid valve(s). With this, the controller 20 switches at least one of the lift control valve 60A or the tilt control valve 60B to the first position or the second position to supply hydraulic fluid to at least one of the lift cylinders 14 or the tilt cylinders 15 to cause the cylinders to extend or retract to cause at least one of the arms 10 or the hitch 16 to swing, thus adjusting at least one of the position or the orientation of the attachment 11.

[0097] The working machine 1 includes a load sensing system (which may be hereinafter simply referred to as “LS system”) 80. The LS system 80 is a hydraulic system to control the flow rate of hydraulic fluid delivered by the variable displacement main pump P2 such that a differential pressure is constant. The differential pressure is obtained by subtracting, from the hydraulic fluid delivery pressure of the main pump P2 which is a variable displacement pump, the maximum of load pressures on the actuators 14, 15 and 27 actuated by hydraulic fluid delivered by the main pump P2.

[0098] The LS system 80 includes a swash plate changing cylinder 81, a flow rate compensation valve 82, and an opening changing cylinder 83. The swash plate changing cylinder 81 adjusts the angle of the swash plate of the main pump P2. The flow rate compensation valve 82 causes a hydraulic pressure to act on the swash plate changing cylinder 81 to actuate the swash plate changing cylinder 81. The opening changing cylinder 83 is actuated by the pilot pressure of pilot fluid from the pilot pump P1 to change the opening of the flow rate compensation valve 82.

[0099] A PLS fluid passage 84 and a PPS fluid passage 85 are connected to the flow rate compensation valve 82. The PLS fluid passage 84 is a fluid passage to transmit a PLS pressure which is the maximum of the load pressures on the actuators 14, 15 and 27 (actuator maximum load pressure). The PPS fluid passage 85 is used to transmit a PPS pressure which is the delivery pressure of the main pump P2. The flow rate compensation valve 82 actuates the swash plate changing cylinder 81 to adjust the angle of the swash plate of the main pump P2 such that the differential pressure, which is obtained by subtracting the PLS pressure from the PPS pressure, is constant. With this, the flow rate of hydraulic fluid delivered by the main pump P2 is controlled, and hydraulic power corresponding to the load applied to the working device 4 and the attachment 11 is outputted from the main pump P2.

[0100] In the present example embodiment, the swash plate of the main pump P2 is pressed by the self-pressure thereof in a direction that increases the flow rate of hydraulic delivered by the main pump P2. The swash plate changing cylinder 81 is operable to cause a force against the self-pressure of the main pump P2 to act on the swash plate. Furthermore, the flow rate compensation valve 82 is operable to control the delivery flow rate of the main pump P2 by adjusting the hydraulic pressure acting on the swash plate changing cylinder 81. Thus, when the hydraulic pressure acting on the swash plate changing cylinder 81 is removed (becomes zero), the angle of the swash plate of the main pump P2 becomes maximum, and the flow rate of hydraulic fluid delivered by the main pump P2 becomes maximum.

[0101] FIG. 2 illustrates a travel-related hydraulic circuit 5A included in the working machine 1. The hydraulic circuit 5A actuates the traveling devices 5 to cause the working machine 1 to travel. The working machine 1 includes travel pumps 50 and travel motors 51.

[0102] Each travel pump 50 is a hydraulic pump to be actuated by power from the prime mover 6. The travel pump 50 is a swash-plate variable displacement axial pump and includes pressure receivers 50a and 50b to receive pilot pressure. The pump pressure receivers 50a and 50b include a forward-travel pump pressure receiver 50a and a rearward-travel pump pressure receiver 50b. The angle of the swash plate of the travel pump 50 is changed according to the pilot pressure acting on the pump pressure receiver(s) 50a and / or 50b. When the angle of the swash plate of the travel pump 50 is changed, the flow rate and the supply direction of the hydraulic fluid delivered by the travel pump 50 change. The travel pumps 50 include a first travel pump 50L corresponding to the first traveling device 5, and a second travel pump 50R corresponding to the second traveling device 5.

[0103] Each travel motor 51 is a hydraulic motor to be actuated by hydraulic fluid delivered by the corresponding travel pump 50. The travel motors 51 include a first travel motor 51L corresponding to the first travel pump 50L, and a second travel motor 51R corresponding to the second travel pump 50R.

[0104] The first travel motor 51L is connected to the first travel pump 50L via a closed loop circuit fluid passage 53a. The first travel motor 51L is actuated by hydraulic fluid supplied from the first travel pump 50L. The first travel motor 51L includes an output shaft 51Lj, and changes the rotation speed of the output shaft 51Lj based on the flow rate of hydraulic fluid delivered by the first travel pump 50L. When the power from the first travel motor 51L is transmitted from the output shaft 51Lj to the drive shaft of the first traveling device 5 via a transmission mechanism, the first traveling device 5 is driven.

[0105] The first travel motor 51L includes a swash plate. When the angle of the swash plate of the first travel motor 51L is changed by a swash plate cylinder 52L, the first travel motor 51L changes the rotation speed stage of the output shaft 51Lj to a first speed stage (low speed stage) or a second speed stage (high speed stage) higher than the first speed stage. Specifically, when the swash plate cylinder 52L retracts, the rotation speed of the output shaft 51Lj of the first travel motor 51L is set to the first speed stage. When the swash plate cylinder 52L extends, the rotation speed of the output shaft 51Lj of the first travel motor 51L is set to the second speed stage.

[0106] The second travel motor 51R is connected to the second travel pump 50R via a closed loop circuit fluid passage 53b. The second travel motor 51R is actuated by hydraulic fluid delivered by the second travel pump 50R to drive the second traveling device 5 via an output shaft 51Rj and the like. When the angle of the swash plate of the second travel motor 51R is changed by a swash plate cylinder 52R, the second travel motor 51R changes the rotation speed stage of the output shaft 51Rj to the first speed stage or the second speed stage. Since the configurations of the second travel motor 51R, the second travel pump 50R, the second traveling device 5 and the swash plate cylinder 52R are respectively the same as the configurations of the first travel motor 51L, the first travel pump 50L, the first traveling device 5 and the swash plate cylinder 52L, detailed description therefor is omitted.

[0107] The working machine 1 includes a travel manual operator (travel manual operator unit) 57. The travel manual operator 57 is operated to control the travel pumps 50, the travel motors 51, and the traveling devices 5. The travel manual operator 57 is operable to be operated to cause the traveling devices 5 and the like to cause the machine body 2 to travel and turn. The travel manual operator 57 is operable to change the pilot pressure applied to the pump pressure receivers 50a, 50b of the travel pumps 50 to change the angle of swash plates of the travel pumps 50 to change the amount and direction of hydraulic fluid delivered by the travel pumps 50, the speed and direction of rotation of the output shafts 51Lj, 51Rj of the travel motors 51, and the speed and direction of operation of the traveling devices 5. The travel manual operator 57 includes a travel operating lever 57a and a plurality of operating valves 44.

[0108] The travel operating lever 57a is a manual operator (travel manual operator) to be operated by the driver, and is provided in the vicinity of the seat 8 inside the cabin 3. The travel operating lever 57a can be operated from the neutral position in a forward direction F, a rearward direction B, a leftward direction L, and a rightward direction R, as well as from the neutral position diagonally leftward and forward, diagonally rightward and forward, diagonally leftward and rearward, and diagonally rightward and rearward.

[0109] The operating valves 44 include operating valves 44a, 44b, 44c, and 44d. The operating valves 44a to 44d are connected to a fluid discharge passage 40, and are actuated by operation of the common travel operating lever 57a to change the pilot pressure of pilot fluid which is hydraulic fluid supplied from the fluid discharge passage 40.

[0110] Specifically, the first operating valve 44a is operable to, when the travel operating lever 57a is pivoted in the forward direction F, change the pilot pressure outputted therefrom according to the operation amount (angle of pivoting). The second operating valve 44b is operable to, when the travel operating lever 57a is pivoted in the rearward direction B, change the pilot pressure outputted therefrom according to the operation amount. The third operating valve 44c is operable to, when the travel operating lever 57a is pivoted in the leftward direction L, change the pilot pressure outputted therefrom according to the operation amount. The fourth operating valve 44d is operable to, when the travel operating lever 57a is pivoted in the rightward direction R, change the pilot pressure outputted therefrom according to the operation amount.

[0111] The operating valves 44 are connected to their corresponding travel pumps 50 by travel fluid passages 42. The travel fluid passages 42 include a first travel fluid passage 42a, a second travel fluid passage 42b, a third travel fluid passage 42c, a fourth travel fluid passage 42d, and a fifth travel fluid passage 42e. The first travel fluid passage 42a is connected to a forward-travel pump pressure receiver 50a of the first travel pump 50L. The second travel fluid passage 42b is connected to a rearward-travel pump pressure receiver 50b of the first travel pump 50L. The third travel fluid passage 42c is connected to a forward-travel pump pressure receiver 50a of the second travel pump 50R. The fourth travel fluid passage 42d is connected to a rearward-travel pump pressure receiver 50b of the second travel pump 50R.

[0112] The fifth travel fluid passage 42e is connected to the operating valves 44a to 44d and to the travel fluid passages 42a to 42d. Specifically, the fifth travel fluid passage 42e includes a bridge fluid passage 42e1 and a plurality of connector fluid passages 45e2. In the bridge fluid passage 42e1, a plurality of shuttle valves 43 and first ends of the connector fluid passages 45e2 are connected alternately. The second ends of the connector fluid passages 45e2 are connected to the respective operating valves 44. The shuttle valves 43 are connected to the respective travel fluid passages 42.

[0113] When the travel operating lever 57a is pivoted in the forward direction F, the first operating valve 44a is operated to allow pilot fluid to be supplied from the first operating valve 44a to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the first operating valve 44a is applied to the forward-travel pump pressure receiver 50a of the first travel pump 50L via the fifth travel fluid passage 42e and the first travel fluid passage 42a. The pilot pressure from the first operating valve 44a is applied to the forward-travel pump pressure receiver 50a of the second travel pump 50R via the fifth travel fluid passage 42e and the third travel fluid passage 42c.

[0114] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the first port 51a to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the third port 51c to the second travel motor 51R. Then, the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R rotate in the normal direction (rotate to achieve forward travel), the first traveling device 5 and the second traveling device 5 are driven to achieve forward travel, and the working machine 1 travels straight forward.

[0115] When the travel operating lever 57a is pivoted in the rearward direction B, the second operating valve 44b is operated to allow pilot fluid to be supplied from the second operating valve 44b to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the second operating valve 44b is applied to the rearward-travel pump pressure receiver 50b of the first travel pump 50L via the fifth travel fluid passage 42e and the second travel fluid passage 42b. The pilot pressure from the second operating valve 44b is applied to the rearward-travel pump pressure receiver 50b of the second travel pump 50R via the fifth travel fluid passage 42e and the fourth travel fluid passage 42d.

[0116] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the second port 51b to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the fourth port 51d to the second travel motor 51R. Then, the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R rotate in the reverse direction (rotate to achieve rearward travel), the first traveling device 5 and the second traveling device 5 are driven to achieve rearward travel, and the working machine 1 travels straight rearward.

[0117] When the travel operating lever 57a is pivoted in the leftward direction L, the third operating valve 44c is operated to allow pilot fluid to be supplied from the third operating valve 44c to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the third operating valve 44c is applied to the forward-travel pump pressure receiver 50a of the second travel pump 50R via the fifth travel fluid passage 42e and the third travel fluid passage 42c. The pilot pressure from the third operating valve 44c is applied to the rearward-travel pump pressure receiver 50b of the first travel pump 50L via the fifth travel fluid passage 42e and the second travel fluid passage 42b.

[0118] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the second port 51b to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the third port 51c to the second travel motor 51R. Then, the output shaft 51Lj of the first travel motor 51L rotates in the reverse direction, the first traveling device 5 is driven to achieve rearward travel, the output shaft 51Rj of the second travel motor 51R rotates in the normal direction, the second traveling device 5 is driven to achieve forward travel, and the working machine 1 turns left.

[0119] When the travel operating lever 57a is pivoted in the rightward direction R, the fourth operating valve 44d is operated to allow pilot fluid to be supplied from the fourth operating valve 44d to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the fourth operating valve 44d is applied to the forward-travel pump pressure receiver 50a of the first travel pump 50L via the fifth travel fluid passage 42e and the first travel fluid passage 42a. The pilot pressure from the fourth operating valve 44d is applied to the rearward-travel pump pressure receiver 50b of the second travel pump 50R via the fifth travel fluid passage 42e and the fourth travel fluid passage 42d.

[0120] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the first port 51a to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the fourth port 51d to the second travel motor 51R. Then, the output shaft 51Lj of the first travel motor 51L rotates in the normal direction, the first traveling device 5 is driven to achieve forward travel, the output shaft 51Rj of the second travel motor 51R rotates in the reverse direction, the second traveling device 5 is driven to achieve rearward travel, and the working machine 1 turns right.

[0121] When the travel operating lever 57a is pivoted diagonally, the difference between the pilot pressures applied to the forward-travel pump pressure receivers 50a and the rearward-travel pump pressure receivers 50b determines the directions and speeds of rotation of the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R, and the working machine 1 turns right or left while traveling forward or rearward.

[0122] Specifically, when the travel operating lever 57a is pivoted diagonally leftward and forward, the working machine 1 turns left while traveling forward at a speed corresponding to the operation amount of the travel operating lever 57a. When the travel operating lever 57a is pivoted diagonally rightward and forward, the working machine 1 turns right while traveling forward at a speed corresponding to the operation amount of the travel operating lever 57a. When the travel operating lever 57a is pivoted diagonally leftward and rearward, the working machine 1 turns left while traveling rearward at a speed corresponding to the operation amount of the travel operating lever 57a. When the travel operating lever 57a is pivoted diagonally rightward and rearward, the working machine 1 turns right while traveling rearward at a speed corresponding to the operation amount of the travel operating lever 57a.

[0123] The working machine 1 includes speed-change switching valves 58L and 58R, a speed-change solenoid valve 59, and a speed-change switch 75. The speed-change switching valves 58L and 58R are two-position switching valves. The speed-change switching valve 58L is connected to the swash plate cylinder 52L by a fluid passage, and the speed-change switching valve 58R is connected to the swash plate cylinder 52R by a fluid passage. The speed-change switching valves 58L and 58R are connected to the speed-change solenoid valve 59 via a fluid passage 41. The speed-change solenoid valve 59 is a two-position solenoid switching valve including two positions and a solenoid to be energized in response to a control signal inputted thereto to switch between the positions. The speed-change solenoid valve 59 is connected to the fluid discharge passage 40, and switches the positions of the switching valves 58L and 58R. The speed-change switch 75 is an operating switch to be operated by the driver to input an instruction to switch the speed stage of the rotation speed of the output shafts 51Lj and 51Rj of the travel motor 51 to a first speed stage (low speed stage) or a second speed stage (high speed) higher than the first speed stage.

[0124] Upon receipt of an instruction to switch the speed stage to the first speed stage from the speed-change switch 75, the controller 20 inputs a control signal into the speed-change solenoid valve 59 to switch the speed-change solenoid valve 59 to the first position to block pilot fluid. With this, the pilot fluid from the fluid discharge passage 40 does not act on the pressure receivers of the speed-change switching valves 58L and 58R via the speed-change solenoid valve 59, the speed-change switching valves 58L and 58R are in the first position to block hydraulic fluid, and hydraulic fluid is not supplied from the speed-change switching valves 58L and 58R to the swash plate cylinders 52L and 52R. Thus, the swash plate cylinders 52L and 52R are caused to retract by the elastic force of a spring, and the rotation speed of the output shafts 51Lj and 51Rj of the travel motors 51 is switched to the first speed stage.

[0125] Upon receipt of an instruction to switch the speed stage to the second speed stage from the speed-change switch 75, the controller 20 inputs a control signal into the speed-change solenoid valve 59 to switch the speed-change solenoid valve 59 to the second position to allow pilot fluid to pass therethrough. With this, pilot fluid from the fluid discharge passage 40 acts on the pressure receivers of the speed-change switching valves 58L and 58R via the speed-change solenoid valve 59, the speed-change switching valves 58L and 58R switch to the second position to allow hydraulic fluid to pass therethrough, and hydraulic fluid is supplied from the speed-change switching valves 58L and 58R to the swash plate cylinders 52L and 52R. Thus, the swash plate cylinders 52L and 52R are caused to extend by the hydraulic pressure, and the rotation speed of the output shafts 51Lj and 51Rj of the travel motors 51 is switched to the second speed stage.

[0126] Regardless of whether the speed-change switch 75 is operated or not, the controller 20 may switch the positions of the speed-change solenoid valve 59 to automatically change the second speed stage to the first speed stage (automatic speed reduction) or automatically change the first speed stage to the second speed stage speed (automatic speed increase). In the case where work is performed using a specific attachment 11, the controller 20 switches the speed stage to the first speed stage to perform a low-speed mode (creep mode) in which the travel speed of the working machine 1 is kept at a low speed.

[0127] FIG. 3 is a block diagram showing an electrical configuration of the working machine 1. The working machine 1 includes elements shown in FIG. 3. The controller 20 includes a processing circuit including one or more processors. The working machine 1 includes the controller 20 which is configured or programmed to perform various controls relating to the working machine 1. The controller 20 is connected to the other elements shown in FIG. 3 in a communicable manner via in-vehicle network(s) such as CAN, ISOBUS, LIN and / or FlexRay.

[0128] The controller 20 includes at least one of one or more internal memories, analog circuits, digital circuits, and the like. The analog circuits and the digital circuits include one or more processors. The processor(s) included in the controller 20 include, for example, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC) and / or the like.

[0129] The internal memory(memories) of the controller 20 is / are each a volatile or nonvolatile memory which stores software program(s) to be executed by one or more processors and various data. The controller 20 uses a predetermined storage area of the internal memory as a buffer to temporarily store information and data.

[0130] A storing device (memory and / or storage) 21 includes a nonvolatile memory and / or the like. The storing device 21 also stores software program(s) to be executed by one or more processors of the controller 20 and various data. The storing device 21 also stores control data corresponding to various attachments 11.

[0131] The one or more processors of the controller 20 read(s) software program(s) and control data from the internal memory and / or the storing device 21, and perform various processes based on the software program(s) and the control data. The one or more processors of the controller 20 may perform various processes based on a predetermined logic circuit.

[0132] Note that a plurality of physically separated processors of the controller 20 may operate together to perform various processes, and the configuration of the controller 20 is not limited to the above described configuration. In such a case, the plurality of processors are respectively provided in one or more computers which are physically separated from the working machine 1, and are connected in a communicable manner via a network such as a in-vehicle network, LAN, WAN, and / or the Internet.

[0133] The following configuration may be used: the above described software program(s) is / are stored in a storage medium (nonvolatile memory such as HDD, SSD, CD-ROM, DVD-ROM) connected in a communicable manner with the controller 20 and / or in external device(s) such as a server and / or the like connected via the above described network(s), and is / are installed from such storage medium(media) and / or the external device(s) into the internal memory or the storing device 21.

[0134] A user interface 22 is, for example, a terminal device (computer) in the form of a touchscreen or a tablet including a display. The user interface 22 is provided in the vicinity of the seat 8 inside the cabin 3 (FIG. 12). The controller 20 causes the user interface 22 to output (display) various information relating to the working machine 1 stored in the internal memory and / or the storing device 21 to the driver or the like (or to other user(s)).

[0135] The driver or the like of the working machine 1 inputs various information via the user interface 22. For example, information relating to the attachment 11 attached to the working device 4 can be inputted via the user interface 22. The controller 20 causes the internal memory and / or the storing device 21 to store the information inputted via the user interface 22. The user interface 22 functions as an input interface and an output interface. The user interface 22 may include input interface(s) such as at least one manual operator, e.g., a button, a switch, a dial, and / or a slider, and / or a microphone, and output device(s) such as a speaker.

[0136] A communicator 24 shown in FIG. 3 includes a communication circuit to wirelessly communicate with external device(s) such as a server, a terminal device and / or a portable device via the Internet, a wireless LAN and / or the like. The portable device is, for example, a smartphone or a tablet. The communicator 24 may include a receiver compliant with a satellite positioning system to receive radio waves from satellites. The communicator 24 also functions as an input interface and an output interface.

[0137] A beacon scanner 23 is a receiver to receive wireless signals compliant with a near field communication standard. Specifically, the beacon scanner 23 receives wireless signals (beacon signals) compliant with Bluetooth (registered trademark) Low Energy which is a near field communication standard. As shown in FIG. 12, the beacon scanner 23 is provided at a front portion of the machine body 2. In the case where a beacon transmitter 19 is provided on the attachment 11 attached to the hitch 16, the beacon scanner 23 receives wireless signals transmitted from the beacon transmitter 19. The beacon scanner 23 is an input interface.

[0138] In the case where the attachment 11 attached to the hitch 16 includes an electric circuit including a processor such as CPU, an electric harness connected to the electric circuit is connected to an AUX connector 28. The AUX connector 28 may communicate in a wired manner with the attachment 11, and functions as an input interface and an output interface.

[0139] An attaching switch 29a, a detaching switch 29b, an accelerator 7, the speed-change switch 75, the work manual operator 67, and an AUX manual operator 73 are provided in the vicinity of the seat 8 inside the cabin 3, and are operated by the driver of the working machine 1.

[0140] The attaching switch 29a is operated to attach the attachment 11 to the hitch 16. The detaching switch 29b is operated to allow the attachment 11 to be detached from the hitch 16. As another example, a single operating switch may be used as an attaching switch and a detaching switch.

[0141] A latch control valve 35 is a three-position solenoid switching valve including three positions and a solenoid to be energized in response to a control signal inputted thereto to switch between the positions, and controls the latch cylinder 17. As shown in FIG. 4, the latch control valve 35 is connected to the latch cylinder 17 by fluid passages and is also connected to the main fluid passage 45. The latch control valve 35 is switchable between (i) a neutral position 35c to block hydraulic fluid from the fluid passage 45, (ii) a first position 35a to allow hydraulic fluid to be supplied to the cap-side chamber of the latch cylinder 17 to cause the latch cylinder 17 to extend, and (iii) a second position 35b to allow hydraulic fluid to be supplied to the rod-side chamber of the latch cylinder 17 to cause the latch cylinder 17 to retract.

[0142] For example, the driver of the working machine 1 operates the work manual operator 67 (FIG. 1) to lower the arms 10 and the hitch 16, and operates the travel manual operator 57 (FIG. 2) to cause the machine body 2 to travel forward very slowly, thus causing the front surface of the bracket 30 of the hitch 16 to contact the base plate 9 (FIG. 13) of the attachment 11 placed on the ground J. Then, when the driver operates the attaching switch 29a, the controller 20 inputs a control signal into the latch control valve 35 to switch the latch control valve 35 from the neutral position 35c to the first position 35a. With this, the latch cylinder 17 extends, the latching mechanisms 31 switch to the latching state, and the attachment 11 is attached (fixed) to the hitch 16.

[0143] The driver, while the working machine 1 is in the stopped state, operates the work manual operator 67 to lower the arms 10 and the hitch 16 to cause the attachment 11 attached to the hitch 16 to contact the ground. Then, when the driver operates the detaching switch 29b, the controller 20 inputs a control signal into the latch control valve 35 to switch the latch control valve 35 from the neutral position 35c to the second position 35b. With this, the latch cylinder 17 retracts, the latching mechanisms 31 switch to the unlatching state, and the attachment 11 is allowed to be detached from the hitch 16. In this state, when the driver operates the travel manual operator 57 to cause the machine body 2 to travel rearward, the attachment 11 is detached from the hitch 16.

[0144] A speed detector 36 shown in FIG. 3 detects the travel speed of the working machine 1 (machine body 2). Specifically, the speed detector 36 includes, for example, rotation speed sensor(s) to detect the rotation speed of the travel motors 51L and 51R (FIG. 2) and a calculator, and the calculator calculates the travel speed based on a detection signal from the rotation speed sensor(s). Note that the calculator may not be provided in the speed detector 36, and the controller 20 may calculate the travel speed based on the detection signal from the rotation speed sensor. The controller 20 calculates the travel distance by multiplying the travel speed of the machine body 2 by the travel time.

[0145] As another example, the travel manual operator 57 may include a sensor to detect the direction and angle of operation (pivoting) of the travel operating lever 57a, and the speed detector 36 or the controller 20 may calculate the travel speed based on a detection signal (electric signal) outputted from the sensor. More specifically, for example, the speed detector 36 or the controller 20 determines the direction and angle of operation of the travel operating lever 57a based on a detection signal from the sensor of the travel manual operator 57, calculates, as the operation amount of the travel operating lever 57a, the ratio of the angle of operation of the travel operating lever 57a to the maximum angle of pivoting of the travel operating lever 57a, and calculates the travel speed of the working machine 1 based on the operation amount.

[0146] Alternatively, the speed detector 36 or the controller 20 may calculate the position of the machine body 2 at regular intervals based on signals received by the receiver of the communicator 24 from satellites of a satellite positioning system, and calculate the travel speed of the working machine 1 based on time-series position data of the machine body 2. The configuration to detect the travel speed of the working machine 1 is not limited to the above, and a speed detector to detect the travel speed by some other known method may be used.

[0147] An arm detector 37 and a hitch detector 38 detect the position of the working device 4 that includes the position in the up-down direction, and may each include a sensor(s) such as an inertial measurement unit (IMU) and / or a potentiometer, for example. The arm detector 37 (first detector) detects the angle of rotation (swinging) of the arms 10 as the position (swinging position) of the arms 10 at least in the swinging direction. The arm detector 37, if including an inertial measurement unit, detects the three-dimensional position of the arms 10 and the inertial motion (position in three orthogonal axes, translational motion, and rotational motion) of the arms 10 to determine the acceleration and angular velocity of the arms 10. The controller 20, based on the detection results from the arm detector 37, determines the posture of the arms 10 that includes the position and orientation of the arms 10, the positions of the distal portion of the arms 10 and the hitch 16 in the up-down direction and in the front-rear direction, and the actuated position (the degree of extension / retraction) of the lift cylinders 14.

[0148] The hitch detector 38 (second detector) detects the tilt angle (angle of rotation (swinging)) of the hitch 16 as the position (swinging position) of the hitch 16 at least in the swinging direction. The hitch detector 38, if including an inertial measurement unit, detects the three-dimensional position of the hitch 16 and the inertial motion (position in three orthogonal axes, translational motion, and rotational motion) of the hitch 16 to determine the acceleration and angular velocity of the hitch 16. The controller 20, based on the detection results from the hitch detector 38, determines the posture of the hitch 16 that includes the position and orientation of the hitch 16, the position of the hitch 16 in the up-down direction and the position and orientation in the front-rear direction, and the actuated position (the degree of extension / retraction) of the tilt cylinders 15.

[0149] Furthermore, the controller 20 determines the behavior of the attachment 11 attached to the hitch 16, the position of the attachment 11 in the up-down direction, and the position and orientation of the attachment 11 in the front-rear direction based on the detection results(s) from the arm detector 37 and / or the hitch detector 38. Specifically, the controller 20 determines the direction of movement of a work surface 11w (FIG. 12) of the attachment 11 attached to the hitch 16 (any of four directions including up, down, forward, and rearward directions) and the position of the work surface 11w based at least on the detection result from the arm detector 37, and determines the orientation of the work surface 11w based on the detection result from the hitch detector 38. The work surface 11w is an imaginary surface defined at the contact portion of the attachment 11 that makes contact with the target object during work, and is a reference surface for the posture of the attachment 11.

[0150] As described above, the controller 20 determines the postures (position and orientation) of the arms 10 and the hitch 16 of the working device 4 and the posture of the attachment 11 attached to the working device 4 based on the detection results from the arm detector 37 and the hitch detector 38. Furthermore, the controller 20, based on the detection results from the arm detector 37 and the hitch detector 38, controls the working device 4 and actuates the working device 4 to change the posture of the attachment 11.

[0151] In addition to the foregoing pressure detectors 70a and 70b, the working machine 1 includes pressure detectors 48a, 48b, 48c, 48d, 49a, 49b, 49c, 49d, 68a, 68b, 68c, and 68d as elements to detect the pressure of hydraulic fluid or pilot fluid. Each of the pressure detectors 48a to 48d, 49a to 49d and 68a to 68d includes a pressure sensor.

[0152] The pressure detectors 48a, 48, 48c, and 48d are provided in the respective travel fluid passages 42a, 42b, 42c, and 42d, as illustrated in FIG. 2. The pressure detector 48a detects, as a first travel pressure, the pilot pressure of pilot fluid applied to the first travel fluid passage 42a and the forward-travel pump pressure receiver 50a of the first travel motor 51L. The pressure detector 48b detects, as a second travel pressure, the pilot pressure of pilot fluid applied to the second travel fluid passage 42b and the rearward-travel pump pressure receiver 50b of the first travel motor 51L. The pressure detector 48c detects, as a third travel pressure, the pilot pressure of pilot fluid applied to the third travel fluid passage 42c and the forward-travel pump pressure receiver 50a of the second travel motor 51R. The pressure detector 48d detects, as a fourth travel pressure, the pilot pressure of pilot fluid applied to the fourth travel fluid passage 42d and the rearward-travel pump pressure receiver 50b of the second travel motor 51R.

[0153] The controller 20 may determine the operation direction and operation amount of the travel operating lever 57a and also determine whether or not the travel manual operator 57 is operated to cause the machine body 2 to travel straight or whether or not the travel manual operator 57 is operated to cause the machine body 2 to turn, based on the first to fourth travel pressures detected by the pressure detectors 48a to 48d. The controller 20 may determine the travel direction, travel speed, whether straight travel is performed, whether turn is performed, the direction of turn, and the type of turn regarding the machine body 2 (working machine 1) based on the first to fourth travel pressures.

[0154] The pressure detectors 49a, 49b, 49c and 49d are provided in the circuit fluid passages 53a and 53b. The pressure detector 49a detects the pressure of hydraulic fluid acting on a first port 51a of the first travel motor 51L as a first motor pressure. The pressure detector 49b detects the pressure of hydraulic fluid acting on a second port 51b of the first travel motor 51L as a second motor pressure. The pressure detector 49c detects the pressure of hydraulic fluid acting on a third port 51c of the second travel motor 51R as a third motor pressure. The pressure detector 49d detects the pressure of hydraulic fluid acting on a fourth port 51d of the second travel motor 51R as a fourth motor pressure.

[0155] The controller 20 determines the travel direction, the travel speed, whether straight travel is being performed, whether turning is being performed, the turn direction, and the type of turn relating to the working machine 1 based on the first to fourth motor pressures detected by the pressure detectors 49a to 49d. The controller 20 may determine the operation direction and operation amount of the travel operating lever 57a and also determine whether or not the travel manual operator 57 is operated to cause the machine body 2 to travel straight or whether or not the travel manual operator 57 is operated to cause the machine body 2 to turn, based on the first to fourth motor pressures.

[0156] As shown in FIG. 1, the pressure detectors 68a, 68b, 68c and 68d are respectively provided in the fluid passages 64a, 64b, 65a and 65b. The pressure detectors 68a and 68b detect the pressure of hydraulic fluid acting from the lift control valve 60A to the lift cylinders 14 as a lift pressure. The controller 20 refers to the lift pressure and, for example, adjusts the opening of the solenoid valves 76a and 76b. The pressure detectors 68c and 68d detect the pressure of hydraulic fluid acting from the tilt control valve 60B to the tilt cylinders 15 as a tilt pressure. The controller 20 refers to the tilt pressure and, for example, adjusts the opening of the tilt solenoid valves 77a and 77b. The controller 20 may determine whether or not the work manual operator 67 is operated to swing the arms 10 and the hitch 16 of the working device 4 and whether or not the work manual operator 67 is operated to change the posture of the attachment 11 based on the lift pressure and the tilt pressure.

[0157] The accelerator 7 is operable to define and change the rotation speed of the prime mover 6, and includes an acceleration operator and an acceleration sensor. The acceleration operator is, for example, an operation structure (manual operator) such as a lever, a pedal, a dial, or a slider. The acceleration sensor outputs a signal corresponding to the operation position of the acceleration operator. The controller 20 controls the driving of the prime mover 6 and defines and changes the rotation speed of the prime mover 6 based on an acceleration signal outputted from the acceleration sensor.

[0158] The configurations of the speed-change switch 75, the speed-change solenoid valve 59, the lift solenoid valves 76a and 76b, the tilt solenoid valves 77a and 77b, and the AUX solenoid valves 76a and 76b have been described already.

[0159] The AUX manual operator 73 is operable to control the supply of hydraulic fluid to the auxiliary actuator 27 of the attachment 11. The AUX manual operator 73 includes, in addition to the foregoing AUX output switch 73b, an AUX mode switch 73a, an AUX steady switch 73c, and an AUX volume switch 73d.

[0160] The AUX mode switch 73a is turned ON to start an AUX mode in which an attachment 11 including an auxiliary actuator 27 is allowed to be used with the working machine 1, and is turned OFF to end the AUX mode. When the AUX mode switch 73a is turned ON to start the AUX mode and then the AUX output switch 73b is turned ON, the controller 20 opens one of the AUX solenoid valves 77a and 77b to allow hydraulic fluid to be supplied from the AUX control valve 60C to the corresponding AUX port 25.

[0161] In so doing, if the first AUX port 25a and the first hydraulic port of the attachment 11 are connected by the external fluid passage 26a and the second hydraulic port of the attachment 11 and the second AUX port 25b are connected by the external fluid passage 26b, (i) hydraulic fluid from the AUX control valve 60C flows through the first AUX port 25a, the external fluid passage 26a, and the first hydraulic port of the attachment 11 and is supplied to the auxiliary actuator 27 of the attachment 11, and (ii) hydraulic fluid discharged from the auxiliary actuator 27 flows through the second hydraulic port of the attachment 11, the external fluid passage 26b, and the second AUX port 25b and returns to the AUX control valve 60C. In some cases, hydraulic fluid from the AUX control valve 60C flows through the second AUX port 25b, the external fluid passage 26b, and the second hydraulic port of the attachment 11 and is supplied to the auxiliary actuator 27, whereas hydraulic fluid from the auxiliary actuator 27 flows through the first hydraulic port of the attachment 11, the external fluid passage 26a, and the first AUX port 25a and returns to the AUX control valve 60C.

[0162] The controller 20 ends the AUX mode when the AUX mode switch 73a is turned OFF after the AUX output switch 73b is turned OFF, the AUX solenoid valves 77a and 77b are closed, and the supply of hydraulic fluid from the AUX control valve 60C to the corresponding AUX port 25 is stopped.

[0163] The AUX steady switch 73c is turned ON to start a steady output mode in which the current state of supply of hydraulic fluid to the auxiliary actuator 27 (fluid flow rate) is kept constant, and is turned OFF to stop the steady output mode. When the AUX steady switch 73c is turned ON while the AUX mode is being performed to supply hydraulic fluid to the auxiliary actuator 27, the controller 20 starts the steady output mode and to maintain the opening of the AUX control valve 60C to keep constant the fluid flow rate of hydraulic fluid supplied to the auxiliary actuator 27. After that, when the AUX steady switch 73c is turned OFF, the controller 20 ends the steady output mode, does not maintain the opening of the AUX control valve 60C anymore, and does not keep constant the fluid flow rate of hydraulic fluid supplied to the auxiliary actuator 27 anymore.

[0164] The AUX volume switch 73d is operated to change the supply amount of hydraulic fluid to the auxiliary actuator 27. The AUX volume switch 73d outputs an electric signal corresponding to the manual operation of a control knob such as a slider operating switch, a dial, or a push button. When the AUX volume switch 73d is operated and an electric signal corresponding to the operation is inputted into the controller 20 when the steady supply mode is not performed, the controller 20 detects the operation position of the AUX volume switch 73d based on the electric signal, and inputs a control signal with an electric current value corresponding to the operation position into the AUX solenoid valves 78a and 78b. With this, the openings of the AUX solenoid valves 78a and 78b are defined and / or changed, the pilot pressure acting on the AUX control valve 60C changes, the opening of the AUX control valve 60C is defined and / or changed, the supply amount of hydraulic fluid from the AUX control valve 60C to the auxiliary actuator 27 is defined and / or changed, and the AUX pressure is also defined and / or changed.

[0165] After the attachment 11 is attached to the hitch 16, the controller 20 identifies the attachment 11. For example, in the case where the attached attachment 11 includes a beacon transmitter 19, a wireless signal including information relating to the attachment 11 is transmitted at regular intervals from the beacon transmitter 19, and therefore the wireless signal is received by the beacon scanner 23. The controller 20 identifies the attached attachment 11 based on the information included in the wireless signal received by the beacon scanner 23. For example, the information transmitted by the beacon transmitter 19 includes identification information of the attachment 11 provided with the beacon transmitter 19. The storing device 21 stores pieces of attachment information indicating a plurality of attachments 11 attachable to the working device 4 and pieces of control information defined for the respective plurality of attachments 11, which are associated with each other.

[0166] FIG. 5 illustrates an example, in the form of a table, of pieces of attachment information of the plurality of attachments 11 attachable to the working device 4 and their corresponding pieces of control information. The pieces of information shown in FIG. 5 are stored in a predetermined storage area of the storing device 21.

[0167] The attachment information shown in FIG. 5 includes identification information (ID), name, icon data, model number, and specifications of a corresponding attachment 11. The specifications include information such as the size of the attachment 11, the position and orientation of the work surface 11w (FIG. 12) of the attachment 11 relative to the base plate 9 (FIG. 13), and whether the attachment 11 includes an auxiliary actuator 27. The specifications of the attachment information of the attachment 11 including an auxiliary actuator 27 may include specifications information such as the type and capacity of the auxiliary actuator 27.

[0168] The control information includes the default value of fluid flow rate, work information, and / or the like. The fluid flow rate is the amount of hydraulic fluid supplied per unit time to the auxiliary actuator 27 of the corresponding attachment 11.

[0169] Work information includes information relating to a work condition (predetermined condition) which, when satisfied, allows estimation that work is being performed by the attachment 11 attached to the working device 4. The information relating to the work condition includes a predetermined actuation range of the lift cylinders 14 and a predetermined actuation range of the tilt cylinders 15. Each of the predetermined actuation ranges of the lift cylinders 14 and the tilt cylinders 15 corresponds to the range of the work posture of the corresponding attachment 11 within which work can be performed by the attachment 11. In other words, this is a range of the posture (position and orientation) of the working device 4.

[0170] The controller 20 includes, into the work condition, a condition that the actuated positions of the lift cylinders 14 and the tilt cylinders 15 determined from the detection results from the arm detector 37 and the hitch detector 38 fall within the corresponding predetermined actuation ranges, and determines whether the work condition is satisfied. Additionally or alternatively, the controller 20 may include, in the work condition, a condition that the machine body 2 is traveling straight and / or a condition that the steady output mode has been performed for a predetermined period, and determine whether or not the work condition is satisfied. Such a work condition is an example, and the work condition may include some other condition(s).

[0171] The predetermined actuation range(s) of at least one of the lift cylinders 14 or the tilt cylinders 15 may be included in the work information (control information). The controller 20 may then include, in the work condition, a condition that the actuated position(s) of at least one of the lift cylinders 14 or the tilt cylinders 15 determined from the detection result(s) from at least one of the arm detector 37 or the hitch detector 38 is / are within the corresponding actuation range(s), and determine whether or not the work condition is satisfied.

[0172] In addition to or instead of the predetermined actuation ranges of the lift cylinders 14 and the tilt cylinders 15, a predetermined range of the work posture of the attachment 11 and / or a range of the work posture of the arms 10 and the hitch 16 that corresponds to the predetermined range may be included in the work information. The controller 20 may then include, in the work condition, a condition that at least one of the posture of the attachment 11 or the posture of the arms 10 and the hitch 16 determined from the detection results from the arm detector 37 and the hitch detector 38 is within a predetermined range, and determine whether or not the work condition is satisfied.

[0173] Note that, as the work posture of the attachment 11, for example, the position in the up-down direction (vertical direction) of the work surface 11w (height of the work surface 11w from the bottom of the traveling devices 5 in contact with the ground) and the orientation (tilt angle, or pitch angle) of the work surface 11w may be defined. As the posture of the arms 10, the swing position (angle of rotation) of the arms 10 detectable by the arm detector 37 and / or the position in the up-down direction of the arms 10 detectable by the arm detector 37 may be defined. As the posture of the hitch 16, the swing position (angle of rotation) of the hitch 16 detectable by the hitch detector 38 and / or the position in the up-down direction of the hitch 16 detectable by the hitch detector 38 may be defined.

[0174] For each of the plurality of attachments 11 attachable to the working device 4, related one or more of the default value of the fluid flow rate and the work information are defined, and such defined information is included in the control information. In the example in FIG. 5, the control information for contacting / moved work attachments 11 such as a sweeper and a rake includes the default value of fluid flow rate and work information. The control information for attachments 11 each including an auxiliary actuator 27 at least includes the default value of fluid flow rate. The work information for attachments 11 to condition the surface of the target object, such as a sweeper and a snow blower, defines a predetermined period for the foregoing steady output mode of zero seconds or longer. The control information for attachments 11 other than the contacting / moved work attachments, such as a spreader and a grapple, does not include work information.

[0175] As another example, the control information for attachments 11 other than contacting / moved work attachments 11 may also include work information, posture information, and / or the like. The attachment information may include at least one of the identification information (ID), name, icon, or model number of the attachment 11, and / or other information such as a nickname and / or the serial number of the attachment 11.

[0176] The controller 20 reads attachment information and control information corresponding to the information (identification information) about the attachment 11 received from the beacon transmitter 19 from the storing device 21. The controller 20 identifies the type of the attachment 11 and determines whether the attachment 11 includes an auxiliary actuator 27 based on the read attachment information.

[0177] In the case where an electric circuit including a controller such as a CPU is provided in the attachment 11, the controller 20 may, after an electric harness connected to the electric circuit is connected to the AUX connector 28, receive information relating to the attachment 11 transmitted from the controller via the electric harness and the AUX connector 28. The controller 20 may then read control information corresponding to the attachment 11 indicated by the received information from the storing device 21.

[0178] The information transmitted from an electronic device in or on the attachment 11, such as the beacon transmitter 19 or the controller of the attachment 11, may include the information relating to the attachment 11 and the control information corresponding to the attachment 11. In such a case, the controller 20, upon receipt of the information transmitted from the electronic device of the attachment 11 via the beacon scanner 23 or the AUX connector 28, reads (acquires) the information relating to the attachment 11 and the control information from the received information.

[0179] The control information transmitted from the electronic device of the attachment 11 as described above may include at least one of the default value of the fluid flow rate or the work information. The control information from the electronic device of the attachment 11 may include information indicating at least one of the predetermined actuation ranges of the lift cylinders 14 and the tilt cylinders 15, the predetermined range of the work posture of the arms 10 and the hitch 16, or the predetermined range of the work posture of the attachment 11. In such a case, the controller 20 acquires the information included in the control information transmitted from the electronic device of the attachment 11, via the beacon scanner 23 or the AUX connector 28.

[0180] In addition to or instead of the beacon transmitter 19 and the beacon scanner 23, a transmitter such as a Radio Frequency Identification (RFID) tag may be provided in or on the attachment 11 and a receiver to receive wireless signals issued by the transmitter may be provided in or on the working machine 1.

[0181] Additionally or alternatively, the controller 20 may read from the storing device 21 the data of a plurality of icons C1, C2, C3, C4, C5, C6, and so on indicating respective attachments 11 attachable and detachable to and from the working device 4 and cause the user interface 22 to display the plurality of icons C1, C2, C3, C4, C5, C6, and so on, on a predetermined input screen G2 as illustrated in FIG. 6. In the example of FIG. 6, the controller 20 causes the plurality of icons C1, C2, C3, C4, C5, C6, and so on and the pieces of identification information A1, A2, A3, A4, A5, A6, and so on of the attachments 11 corresponding to the plurality of icons C1, C2, C3, C4, C5, C6, and so on to be displayed on the input screen G2.

[0182] The controller 20 may be configured or programmed to, when the driver or the like performs an operation on the user interface 22 to select an icon that represents the attachment 11 attached to the working device 4 from the plurality of icons C1, C2, C3, C4, C5, C6, and so on displayed on the input screen G2, accept the selected icon (icon C3 in FIG. 6) as information indicating the attachment 11 and read the control information for the attachment 11 corresponding to the selected icon from the storing device 21.

[0183] Additionally or alternatively, the following configuration may be used: the driver or the like manually inputs information such as the name of the attachment 11 attached to the working device 4 into the input screen displayed on the user interface 22. The controller 20 may then receive the manually inputted information from the user interface 22, and read the control information corresponding to the information from the storing device 21.

[0184] Additionally or alternatively, the following configuration may be used: an input screen as indicated in FIG. 6 or an input screen for manual input is displayed on a display of an external device such as a smartphone, and information relating to the attachment 11 corresponding to the icon selected by the user via the input screen or manually inputted information relating to the attachment 11 is transmitted from the external device and received by (inputted into) the communicator 24. The controller 20 may then read, from the storing device 21, the control information corresponding to the information relating to the attachment 11 received by the communicator 24.

[0185] The controller 20 is configured or programmed to, in the case where the control information acquired from the storing device 21 or the like (such as the beacon scanner 23 or the AUX connector28) includes the default value of the fluid flow rate, control the AUX solenoid valves 78a and 78b and the AUX control valve 60C such that hydraulic fluid is supplied to the auxiliary actuator 27 at the default fluid flow rate when the AUX output switch 73b is operated, for example.

[0186] The controller 20 is configured or programmed to, if the acquired control information includes work information, define the work condition based on the work information, determine whether the work condition is satisfied or not, and, if the work condition is satisfied, determine (estimate) that the attachment 11 attached to the working device 4 is performing work. The controller 20 then cause the storing device 21 (or the internal memory) to store actual control information relating to the posture of the attachment 11 at the time when the work condition is satisfied.

[0187] FIG. 7 illustrates an example of actual control information. The controller 20 is configured or programmed to include, in actual control information, device information relating to the posture of the working device 4, such as the actuated positions of the lift cylinders 14 and the tilt cylinders 15 at the time when the work condition is satisfied, and cause the storing device 21 to store the actual control information. As another example, the controller 20 may include, in device information, only information indicating the actuated position of the lift cylinders 14 at the time when the work condition is satisfied. The controller 20 may include, in the device information, information indicating the posture (which may include only position) of at least the arms 10 (of the arms 10 and the hitch 16) at the time when the work condition is satisfied. The controller 20 may include, in the actual control information, information indicating the posture (which may include only position) of the attachment 11 at the time when the work condition is satisfied.

[0188] The controller 20 is configured or programmed to, after the work condition, which was satisfied, becomes not satisfied and then the machine body 2 turns, actuate the working device 4 based on the actual control information stored in the storing device 21 to change the posture of the attachment 11 back to the previous posture which is the posture at the time when the work condition was satisfied.

[0189] FIGS. 8A and 8B show a flowchart showing the operation of the working machine 1. The steps in FIGS. 8A and 8B are repeatedly performed by the controller 20 based on software program(s) stored in the internal memory and / or the storing device 21. The same applies to the steps of a flowchart in FIG. 9 (described later). For convenience, in each flowchart, “attachment” is indicated as “ATT”, and “actuator” is indicated as “ACT”.

[0190] In response to the operation of the attaching switch 29a, the controller 20 actuates the latch cylinder 17 to attach the attachment 11 to the hitch 16 (S1 in FIG. 8A), then acquires input information relating to the attachment 11 inputted thereto from one of the input interfaces 23, 28, 22 and 24, and acquires (reads) attachment information and control information corresponding to the attachment 11 indicated by the input information from the storing device 21 (S2). The controller 20 then identifies the attachment 11 based on the acquired attachment information (S3). In so doing, the controller 20 identifies the type of the attachment 11, whether the attachment 11 includes an auxiliary actuator 27, and / or the like.

[0191] The controller 20, if determining that the attachment 11 includes an auxiliary actuator 27 (YES at S4), after starting the AUX mode in response to turning ON of the AUX mode switch 73a, starts supply of hydraulic fluid to the corresponding AUX port 25 from the AUX control valve 60C in response to turning ON of the AUX output switch 73b (S5). With this, hydraulic fluid is supplied from the AUX port 25 to the auxiliary actuator 27 of the attachment 11 via the corresponding external fluid passage 26 and the like to actuate the auxiliary actuator 27, so that the attachment 11 is driven. In so doing, the controller 20 actuates the AUX solenoid valves 78a and 78b to define the opening of the AUX control valve 60C such that the fluid flow rate of hydraulic fluid toward the AUX port 25 is the default value indicated by the control information.

[0192] If determining that the attachment 11 does not include auxiliary actuators 27 based on the attachment information (NO at S4), the controller 20 does not supply hydraulic fluid from the AUX control valve 60C to the corresponding AUX port 25.

[0193] After the answer is NO at step S4 or after step S5, the controller 20 determines whether or not the attachment 11 attached to the hitch 16 is a specific attachment 11 based on the attachment information. The specific attachment 11 is an attachment 11 to be automatically brought into a work posture. For example, defined specific attachments 11 include attachments 11 to perform work while being kept in the work posture in contact with the target object. The defined specific attachments 11 may include attachments 11 to perform work while being moved by the working machine 1 and kept in the work posture in contact with the target object.

[0194] More specifically, for example, the defined specific attachments 11 include buckets, sweepers, snow blowers, snow blades, angle brooms, mowers, plows, skid cutters, and / or the like, but do not include spreaders, grapples, earth augers, and pallet forks. Information indicating specific attachments 11 is stored in the internal memory of the controller 20 or a predetermined storage area of the storing device 21. The controller 20 reads the stored information to identify specific attachment(s) 11, and determines whether the attachment 11 indicated by the attachment information, i.e., the attachment 11 attached to the hitch 16, is a specific attachment 11.

[0195] The controller 20 may be configured or programmed to, if the control information includes work information, determine that the attached attachment 11 is a specific attachment 11 (YES at S6), and if the control information does not include work information, determine that the attached attachment 11 is not a specific attachment 11 (NO at S6).

[0196] If determining that the attached attachment 11 is not a specific attachment 11 (NO at S6), the controller 20 ends the series of operation in FIGS. 8A and 8B. In such a case, the controller 20 does not change the posture of the attached attachment 11 automatically to the work posture.

[0197] In contrast, if the attached attachment 11 is a specific attachment 11 (YES at S6), the controller 20 performs a work condition determining process (S7). The work condition determining process is performed to select a work condition suitable for the attachment 11 and determine whether the work condition is satisfied or not.

[0198] FIG. 9 is a flowchart showing an example of the work condition determining process. First, the controller 20 reads work information included in the control information corresponding to the attachment 11 and, as information relating to the work condition indicated by the work information, defines a predetermined actuation range of the lift cylinders 14 and a predetermined actuation range of the tilt cylinders 15 (S31 in FIG. 8A). Next, the controller 20, based on the detection results from the arm detector 37 and the hitch detector 38, determines the current actuated position of the lift cylinders 14 and the current actuated position of the tilt cylinders 15, as actual control information relating to the current posture of the working device 4 and of the attachment 11 attached to the working device 4 (S32).

[0199] Next, the controller 20 determines whether or not the current actuated positions of the lift cylinders 14 and the tilt cylinders 15 are within the corresponding predetermined actuation ranges, and, if both the current actuated positions of the lift cylinders 14 and the tilt cylinders 15 are within the predetermined actuation ranges, counts the time for which such a situation has continued. The controller 20 then, if a predetermined period T1 has passed with the current actuated positions of the lift cylinders 14 and the tilt cylinders 15 within the respective corresponding actuation ranges (YES at S33), determines whether or not the machine body 2 is traveling straight.

[0200] As another example, the controller 20 may be configured or programmed to, instead of steps S31 to S33, without referring to the actuation range or the actuated position of the tilt cylinders 15, define a predetermined actuation range of the lift cylinders 14, determine the current actuated position of the lift cylinders 14, and determine whether or not a predetermined period has passed with the current actuated position within the predetermined actuation range.

[0201] The controller 20 may be configured or programmed to, instead of or in addition to steps S31 and S32, define a predetermined actuation range of at least the arms 10 (of the arms 10 and the hitch 16) from the control information corresponding to the attachment 11, and determine the current actuated position (swinging position) of at least the arms 10 (of the arms 10 and the hitch 16) based on the detection results from the arm detector 37 and the hitch detector 38. The controller 20 may then, instead of or in addition to step S33, determine whether or not a predetermined period T1 has passed with the determined current actuated position within the corresponding predetermined actuation range.

[0202] Additionally or alternatively, the controller 20 may be configured or programmed to define a predetermined range of the work posture of the attachment 11 (a range of at least the position (of the position and the orientation)) from the control information corresponding to the attachment 11, and determine the current posture (which includes at least the position (of the position and the orientation)) of the attachment 11 based on the detection results from the arm detector 37 and the hitch detector 38. The controller 20 may then determine whether or not a predetermined period T1 has passed with the current posture of the attachment 11 within the predetermined range of the work posture.

[0203] The controller 20 may be configured or programmed to determine whether or not the machine body 2 is traveling straight based on first to fourth travel pressures detected by the pressure detectors 48a to 48d. Specifically, for example, if the first travel pressure and the third travel pressure applied to the forward-travel pump pressure receivers 50a of the travel pumps 50L, 50R, of the first to fourth travel pressures detected by the pressure detectors 48a to 48d, are each equal to or greater than a first predetermined value and the absolute value of the difference between the first travel pressure and the third travel pressure is less than a second predetermined value, the controller 20 determines that the machine body 2 is traveling straight forward (YES at S34). Furthermore, if the second travel pressure and the fourth travel pressure applied to the rearward-travel pump pressure receivers 50b of the travel pumps 50L, 50R are each equal to or greater than the first predetermined value and the absolute value of the difference between the second travel pressure and the fourth travel pressure is less than the second predetermined value, the controller 20 determines that the machine body 2 is traveling straight rearward (YES at S34). If the first to fourth travel pressures do not satisfy either of the above, the controller 20 determines that the machine body 2 is not traveling straight (NO at S34).

[0204] The controller 20 may be configured or programmed to determine whether or not the machine body 2 is traveling straight based on first to fourth motor pressures detected by the pressure detectors 49a to 49d. Specifically, for example, if the first motor pressure applied to the first port 51a of the first travel motor 51L and the third motor pressure applied to the third port 51c of the second travel motor 51R, of the first to fourth motor pressures detected by the pressure detectors 49a to 49d, are each equal to or greater than a third predetermined value and the absolute value of the difference between the first motor pressure and the third motor pressure is less than a fourth predetermined value, the controller 20 determines that the machine body 2 is traveling straight forward (YES at S34). If the second motor pressure applied to the second port 51b of the first travel motor 51L and the fourth motor pressure applied to the fourth port 51d of the second travel motor 51R are each equal to or greater than the third predetermined value and the absolute value of the difference between the second motor pressure and the fourth motor pressure is less than the fourth predetermined value, the controller 20 determines that the machine body 2 is traveling straight rearward (YES at S34). If the first to fourth motor pressures do not satisfy either of the above, the controller 20 determines that the machine body 2 is not traveling straight (NO at S34).

[0205] Note that, if the attachment 11 which does not perform work during straight rearward travel of the machine body 2 is attached to the working device 4, the controller 20 need only determine whether or not the machine body 2 is traveling straight forward at step S34. As another example, the travel manual operator 57 may include a sensor to detect the operation direction and operation amount of the travel operating lever 57a, and the controller 20 may determine whether or not the machine body 2 is traveling straight based on the detection result from the sensor.

[0206] If determining that the machine body 2 is traveling straight (YES at S34), the controller 20 determines whether or not the attachment 11 identified at step S3 in FIG. 8A is an attachment 11 for which the steady output mode is recommended during work. If the identified attachment 11 is an attachment 11 for which the steady output mode is recommended (YES at S35), the controller 20 determines whether or not a predetermined period T2 has passed with the working machine 1 in the steady output mode.

[0207] The controller 20 then, if the predetermined period T2 has passed with the working machine 1 in the steady output mode (YES at S36), determines that the work condition is satisfied (S37), and ends the work condition determining process. That is, the controller 20 recognizes that the working machine 1 is performing work with the attachment 11 attached to the working device 4. If the identified attachment 11 is not an attachment 11 for which the steady output mode is recommended (NO at S35), the controller 20 does not perform the determination at step S36, determines that the work condition is satisfied (S37), and ends the work condition determining process.

[0208] If the answer is NO at step S33, S34, or S36 (NO at step S33, S34, S36), the controller 20 determines that the work condition is not satisfied (S38), and ends the work condition determining process. That is, the controller 20 recognizes that the working machine 1 is not performing work with the attachment 11 attached to the working device 4.

[0209] After ending the work condition determining process, the controller 20 determines whether or not the work condition has been satisfied continuously for a predetermined period T4 or more (S8 in FIG. 8A). If the work has been performed by the attachment 11 for the predetermined period T4 or more, the controller 20 determines that the work condition has been satisfied continuously for the predetermined period T4 or more (YES at S8 in FIG. 8A). The controller 20 then causes the storing device 21 to store actual control information relating to the posture of the attachment 11 at the time when the work condition is satisfied (S9). Specifically, the controller 20 includes, into the actual control information, device information indicating the actuated positions of the lift cylinders 14 and the tilt cylinders 15 relating to the posture of the working device 4 at the time when the work condition is satisfied (i.e., the actuated positions determined at step S32 in FIG. 9), and causes the storing device 21 to store the actual control information (see FIG. 7). Note that the controller 20 does not cause the storing device 21 to store the actual control information if the work condition has not been satisfied continuously for the predetermined period T4 or more (NO at S8 in FIG. 8A).

[0210] After the answer is NO at step S8 or after step S9 in FIG. 8A, the controller 20 determines whether or not the travel operating lever 57a of the travel manual operator 57 is operated to turn the machine body 2. In so doing, the controller 20 determines whether or not the operation to turn the machine body 2 is performed, based on the first to fourth travel pressures detected by the pressure detectors 48a to 48d.

[0211] Specifically, if, for example, (i) the absolute value of the difference between the first travel pressure and the third travel pressure applied to the forward-travel pump pressure receivers 50a of the travel pumps 50L, 50R, of the first to fourth travel pressures detected by the pressure detectors 48a to 48d or (ii) the absolute value of the difference between the second travel pressure and the fourth travel pressure applied to the rearward-travel pump pressure receivers 50b of the travel pumps 50L, 50R is equal to or greater than the second predetermined value, the controller 20 determines that the travel operating lever 57a is operated to turn the machine body 2 (YES at S10 in FIG. 8B). If the absolute value of the difference between the first travel pressure and the third travel pressure and the absolute value of the difference between the second travel pressure and the fourth travel pressure are each less than the second predetermined value, the controller 20 determines that the travel operating lever 57a is not operated to turn the machine body 2 (NO at S10).

[0212] The controller 20 may be configured or programmed to determine whether or not the travel operating lever 57a is operated to turn the machine body 2 based on the first to fourth motor pressures detected by the pressure detectors 49a to 49d. Specifically, for example, if (i) the absolute value of the difference between the first motor pressure applied to the first port 51a of the first travel motor 51L and the third motor pressure applied to the third port 51c of the second travel motor 51R, of the first to fourth motor pressures detected by the pressure detectors 49a to 49d, or (ii) the absolute value of the difference between the second motor pressure applied to the second port 51b of the first travel motor 51L and the fourth motor pressure applied to the fourth port 51d of the second travel motor 51R is equal to or greater than a fourth predetermined value, the controller 20 determines that the travel operating lever 57a is operated to turn the machine body 2 (YES at S10). If the absolute value of the difference between the first motor pressure and the third motor pressure and the absolute value of the difference between the second motor pressure and the fourth motor pressure are each less than the fourth predetermined value, the controller 20 determines that the travel operating lever 57a is not operated to turn the machine body 2 (NO at S10).

[0213] If the travel operating lever 57a is not operated to turn the machine body 2 (NO at S10), the controller 20 determines whether or not the work operating lever 67a of the work manual operator 67 is operated to actuate the working device 4 (operated to perform work). In so doing, when the driver operates the work operating lever 67a while the machine body 2 (working machine) is traveling straight or in the stopped state, the controller 20 determines that the work operating lever 67a is operated to perform work based on the detection result from the sensor 67b of the work manual operator 67 (YES at S11), and actuates the working device 4 according to the operation direction and operation amount of the work operating lever 67a to change the posture of the working device 4 and the attachment 11 (S12).

[0214] Specifically, the controller 20, according to the operation direction and operation amount of the work operating lever 67a determined based on the detection result from the sensor 67b, actuates the lift solenoid valve 76b, the tilt solenoid valve 77a, the lift control valve 60A, and the tilt control valve 60B to cause the lift cylinders 14 and the tilt cylinders 15 to extend or retract to swing the arms 10 and the hitch 16 to change the posture of the working device 4 and the attachment 11. The controller 20 then performs the work condition determining process again (S7 in FIG. 8A).

[0215] After the controller 20 performs the work condition determining process again, if the answer is YES at step S8, the controller 20 updates, at step S9, the actual control information such that the actual control information includes device information indicating the actuated positions of the lift cylinders 14 and the tilt cylinders 15 relating to the posture of the working device 4 at the time when the work condition is satisfied again (S37 in FIG. 9).

[0216] While the working machine 1 is traveling straight with the attachment 11 performing work, for example, when the working machine 1 reaches an edge of the worksite, the driver operates the travel operating lever 57a to turn the working machine 1 to change directions. If the travel operating lever 57a is operated to turn the machine body 2 (YES at S10), the controller 20 determines the current actuated position of the lift cylinders 14 (S13). If the current actuated position of the lift cylinders 14 is within a predetermined actuation range (YES at S14), the controller 20 actuates the lift cylinders 14 using the lift solenoid valve 76b and the lift control valve 60A to swing the arms 10, thus moving the attachment 11 attached to the working device 4 by a predetermined distance in a direction away from the target object (S15). In the example in FIG. 12, the controller 20 causes the lift cylinders 14 to extend using the lift solenoid valve 76b and the lift control valve 60A to swing the arms 10 upward, thus raising the attachment 11 by a predetermined distance.

[0217] If the identified attachment 11 is a specific attachment 11 for which the work surface 11w is to be held horizontally (held constant), the controller 20 actuates the tilt cylinders 15 using the tilt solenoid valve 77a and the tilt control valve 60B to swing the hitch 16 as the arms 10 swing, thus keeping the orientation of the attachment 11 horizontally relative to the target object. This also keeps a state in which the work surface 11w of the attachment 11 is horizontal to the bottom of the traveling devices 5.

[0218] The controller 20 may be configured or programmed to, at step S15, determine a turn posture which includes the position and orientation of the attachment 11 during the turn of the machine body 2, based on predetermined actuated positions of the lift cylinders 14 and the tilt cylinders 15 indicated by the control information (work information) corresponding to the attachment 11. The controller 20 may then, before the machine body 2 starts turning, actuate the lift cylinders 14 and the tilt cylinders 15 using the lift solenoid valve 76b, the lift control valve 60A, the tilt solenoid valve 77a, and the tilt control valve 60B to swing the arms 10 and the hitch 16 to change the posture of the attachment 11 to the turn posture. When step S15 is performed, the actuated position of the lift cylinders 14 does not fall within the predetermined actuation range anymore, and therefore the controller 20 determines that the work condition is not satisfied anymore (S16).

[0219] While the working machine 1 is traveling straight (while the machine body 2 is traveling straight) and located short of an edge of the worksite, if the driver operates the work operating lever 67a to prepare for turning the working machine 1 (YES at S11), the controller 20 swings the arms 10 according to the operation direction and operation amount of the work operating lever 67a to move the attachment 11 attached to the working device 4 away from the target object to change the posture of the working device 4 and the attachment 11 (S12). With this, the working machine 1 can stably turn (change directions) with the attachment 11 separated from the target object.

[0220] After that, if the controller 20, after performing steps S7 to S9 in FIG. 8A, determines that the travel operating lever 57a is operated to turn the machine body 2 (YES at S10 in FIG. 8B), the controller 20 determines that the current actuated position of the lift cylinders 14 is not within the predetermined actuation range (NO at S14), and determines that the work condition is not satisfied anymore and does not move the attachment 11 using the working device 4 (S16).

[0221] As long as the travel operating lever 57a is being operated to turn the machine body 2, the travel pumps 50L, 50R, the travel motors 51L, 51R, and the traveling devices 5 are actuated to turn the machine body 2 according to the operation direction and operation amount of the travel operating lever 57a. If the driver stops turning the working machine 1 at, for example, an end of the worksite, the driver, in order to resume work using the attachment 11, moves the travel operating lever 57a back to the neutral position and then operates the travel operating lever 57a forward to cause the machine body 2 to travel straight. In such a case, the controller 20, upon detecting that the travel operating lever 57a has not been operated to turn the machine body 2 for a predetermined period T5 (S17), determines that the turn of the machine body 2 has ended (S18). The controller 20 may be configured or programmed to determine that the turn of the machine body 2 has ended when the operation of the travel operating lever 57a to turn the machine body 2 is stopped and then the travel operating lever 57a is operated to cause the machine body 2 to travel straight, e.g., when the travel operating lever 57a is temporarily moved back to the neutral position and then operated forward.

[0222] The controller 20 then determines whether or not the storing device 21 stores actual control information and, if the storing device 21 stores no actual control information (NO at S19), the controller 20 repeats step S11 and subsequent steps. If the storing device 21 stores actual control information (YES at S19), the controller 20 actuates the working device 4 based on the actual control information to move the posture of the attachment 11 back to the previous work posture which is the posture at the time when the work condition was satisfied (S20).

[0223] Specifically, at step S20, the controller 20 reads the actuated positions of the lift cylinders 14 and the tilt cylinders 15 indicated by the device information included in the actual control information, and actuates the lift cylinders 14 and the tilt cylinders 15 using the lift solenoid valve 76b, the tilt solenoid valve 77a, the lift control valve 60A, and the tilt control valve 60B to swing the arms 10 and the hitch 16 such that the actual actuated positions of the lift cylinders 14 and the tilt cylinders 15 match the read actuated positions. That is, the controller 20 moves the actuated positions of the lift cylinders 14 and the tilt cylinders 15 back to the actuated positions at the time of the previous work indicated by the actual control information (device information) to move the posture of the attachment 11 back to the previous work posture.

[0224] Since the posture of the attachment 11 is automatically changed back to the previous work posture, it is possible to perform work using the attachment 11 under the same conditions as before the turn of the machine body 2. After step S20, if the work performed by the attachment 11 has not ended (NO at S21), the controller 20 performs the work condition determining process again (S7 in FIG. 8A) and repeats subsequent steps.

[0225] After that, for example, when the supply of hydraulic fluid to the corresponding AUX port 25 (i.e., to the auxiliary actuator 27 of the attachment 11) is stopped in response to turning OFF of the AUX output switch 73b, the controller 20 determines that the work performed by the attachment 11 has ended (YES at S21 in FIG. 8B). The controller 20 determines that the work performed by the attachment 11 has ended also when the power switch in or on the working machine 1 is turned OFF to stop the prime mover 6 and when the detaching switch 29b is turned ON to allow the attachment 11 to be detached from the hitch 16 (YES at S21). The controller 20 then ends a series of operation in FIGS. 8A and 8B.

[0226] When step S19 in FIG. 8B is performed, the arms 10 and the hitch 16 of the working device 4 are automatically actuated to change the posture of the attachment 11 automatically to the previous work posture. In this regard, for the driver of the working machine 1, etc., to know the start and end of the automatic change in posture, the controller 20 causes, during the automatic change in posture, the user interface 22 to output (display) information indicating that the posture is being automatically changed.

[0227] FIG. 10 illustrates an example of a monitor screen G1 displayed on the user interface 22. The controller 20 causes the user interface 22 to display the monitor screen G1 while the working machine 1 is in operation. The monitor screen G1 displays pieces of information V1 to V6 indicating the state of the working machine 1 detected by sensors in or on the working machine 1, the current date and time, and pieces of information U1 and U2 indicating the attachment 11 identified by the controller 20. The controller 20 is configured or programmed to, when the controller 20 is performing step S19 in FIG. 8B, cause the monitor screen G1 to display a piece of information U3 indicating that the attachment 11 is being changed to the work posture.

[0228] The controller 20 may cause the display of an external device such as a smartphone, instead of the user interface 22, to display (output) the monitor screen G1. In such a case, the controller 20 need only transmit display data of the monitor screen G1 and the foregoing piece of information U3 to the external device via the communicator 24, and cause the display of the external device to display the monitor screen G1 including the piece of information U3.

[0229] In the above-described example embodiments, the controller 20 reads control information corresponding to the attachment 11 attached to the working device 4 based on input information relating to the attachment 11 inputted via the input interface(s) 22, 23, 24, and / or 28, and includes, into the work condition, condition(s) in steps S33, S34, S36 in FIG. 9 based on the control information. Alternatively, for example, step S34 in FIG. 9 may be omitted. Other condition(s) may be included in the work condition.

[0230] The above description of the example embodiments discusses examples in which, with regard to attachments 11 other than contacting / moved attachments such as spreaders, the corresponding control information does not include work information (FIG. 5) and such attachments 11 are not controlled by the controller 20 to automatically change to the previous work posture. However, also with regard to attachments 11 other than contacting / moved work attachments and with regard to other attachments 11 to be changed to the non-work posture by the working device 4 while work is stopped, the corresponding control information may include work information and such attachments 11 may also be controlled by the controller 20 to automatically change to the work posture. Also when work is to be performed for the first time since an attachment 11 is attached to the working device 4, the controller 20 may control the working device 4 to change the posture of the attachment 11 automatically to the work posture included in the corresponding control information.

[0231] In the above described example embodiments, the work manual operator 67 includes a digital joystick. However, for example, as shown in FIG. 11, a pilot-operated hydraulic work manual operator 67 may be used instead.

[0232] The work manual operator 67 in a work-related hydraulic circuit 4A of another example embodiment shown in FIG. 11 includes a work operating lever 67a and a plurality of pilot valves 89a, 89b, 89c and 89d. The plurality of pilot valves 89a to 89d are connected to a fluid discharge passage 40 and are respectively connected to fluid passages 88a, 88b, 88c and 88d. The fluid passages 88a, 88b, 88c and 88d are respectively connected to corresponding work pressure receivers 61a, 61b, 62a, 62b of the lift control valve 60A and the tilt control valve 60B via high-pressure selection valves 91a, 91b, 91c and 91d. Note that, in FIG. 11, for convenience, a portion of the fluid passages 88a, 88b, 88c and 88d is omitted ((a), (b), (c), (d)).

[0233] The high-pressure selection valves 91a, 91b, 91c, 91d are each connected to the lift solenoid valve 76a, 76b or the tilt solenoid valve 77a, 77b via a fluid passage. Each of the high-pressure selection valves 91a, 91b, 91c, 91d allows a higher one of the hydraulic pressure from the connected pilot valve 89a, 89b, 89c, 89d and the hydraulic pressure from the connected solenoid valve 76a, 76b, 77a, 77b to act on the connected work pressure receiver 61a, 61b. The fluid passages 88a to 88d are provided with a solenoid switching valve 87. The solenoid switching valve 87 is a two-position solenoid switching valve, and switchable between a first position to allow passage of pilot fluid and a second position to block pilot fluid. Note that the solenoid switching valve 87 is normally in the first position.

[0234] When the work operating lever 67a is pivoted forward (direction F), the first pilot valve 89a is operated, and, after the pilot pressure of pilot fluid from the fluid discharge passage 40 is changed at the first pilot valve 89a, the pilot fluid passes through the first fluid passage 88a and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 61a of the lift control valve 60A. With this, the lift control valve 60A switches to the first position 61d, the lift cylinders 14 retract, and the arms 10 swing downward.

[0235] When the work operating lever 67a is pivoted rearward (direction B), the second pilot valve 89b is operated, and, after the pilot pressure of pilot fluid from the fluid discharge passage 40 is changed at the second pilot valve 89b, the pilot fluid passes through the second fluid passage 88b and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 61b of the lift control valve 60A. With this, the lift control valve 60A switches to the second position 61e, the lift cylinders 14 extend, and the arms 10 swing upward.

[0236] When the work operating lever 67a is pivoted leftward (direction L), the third pilot valve 89c is operated, and, after the pilot pressure of pilot fluid from the fluid discharge passage 40 is changed at the third pilot valve 89c, the pilot fluid passes through the third fluid passage 88c and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 62a of the tilt control valve 60B. With this, the tilt control valve 60B switches to the first position 62d, the tilt cylinders 15 extend, and the hitch 16 swings downward.

[0237] When the work operating lever 67a is pivoted rightward (direction R), the fourth pilot valve 89d is operated, and, after the pilot pressure of pilot fluid from the pilot fluid discharge passage 40 is changed at the fourth fluid passage 88d, the pilot fluid passes through the fourth fluid passage 88d and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 62b of the tilt control valve 60B. With this, the tilt control valve 60B switches to the second position62e, the tilt cylinders 15 retract, and the hitch 16 swings upward.

[0238] The fluid passages 88a, 88b, 88c and 88d are provided with respective pressure detectors 92a, 92b, 92c and 92d. The pressure detectors 92a, 92b, 92c and 92d detect the pilot pressure outputted from the pilot valves 89a, 89b, 89c and 89d. The controller 20 may determine whether or not the work operating lever 67a is operated, the operation direction and operation amount of the work operating lever 67a based on the pilot pressure detected by the pressure detectors 92a to 92d.

[0239] The controller 20 is configured or programmed such that, when actuating at least one of the lift solenoid valves 76a and 76b or the tilt solenoid valves 77a and 77b to switch the position of at least one of the lift control valve 60A or the tilt control valve 60B to cause at least one of the arms 10 or the hitch 16 to swing, the controller 20 inputs a control signal into the solenoid switching valve 87 to switch the solenoid switching valve 87 to the second position. With this, the pilot pressure from the pilot valves 89a to 89d is blocked at the solenoid switching valve 87 and does not act on any of the work pressure receivers 61a, 61b, 62a and 62b of the lift control valve 60A and the tilt control valve 60B.

[0240] In the foregoing example embodiments, a hydraulic, pilot-operated travel manual operator 57 is used. Note, however, that the travel manual operator57 may also include a digital joystick like the work manual operator 67 illustrated in FIG. 1, and may include some other electric manual operator capable of inputting, into the controller 20, an operation signal (electric signal) corresponding to the operation direction and operation amount of the travel operating lever 57a.

[0241] Working machines 1 of example embodiments described so far include features described in the following items and achieve the following effects.

[0242] (Item 1) A working machine 1 including a machine body 2, a traveling device 5 to cause the machine body 2 to travel and turn, a working device 4 to attach thereto an attachment 11 which is one of a plurality of attachments 11 to perform work by contacting a target object, and change a posture of the attachment 11 attached thereto including a position of the attachment 11 in an up-down direction, a work manual operator 67 to be operated to actuate the working device 4 to change the posture of the attachment 11, and a controller 20 configured or programmed to control the working device 4, wherein the controller 20 is configured or programmed to cause a memory and / or a storage 21 to store actual control information relating to the posture of the attachment 11 at a time when a predetermined condition (work condition) is satisfied, the predetermined condition being a condition which, when satisfied, allows estimation that the work is being performed by the attachment 11 attached to the working device 4, and after the predetermined condition becomes not satisfied and the machine body 2 turns, actuate the working device 4 based on the actual control information to change the posture of the attachment 11 back to a previous work posture which is the posture of the attachment 11 at the time when the predetermined condition is satisfied.

[0243] With the configuration according to item 1, for example, after the driver operates the work manual operator 67 to change the posture of the attachment 11 to an intended work posture, the driver can manually drive the working machine 1 and perform work using the attachment 11. Then, even if, upon the working machine 1 reaching an edge of the worksite, the driver operates the work manual operator 67 to bring the attachment 11 into a non-work posture away from the target object and temporarily stops the work so that the working machine 1 can stably make a turn, it is possible to automatically change the posture of the attachment 11 back to the posture before the turn, i.e., back to the work posture intended by the driver, after the working machine 1 (machine body 2) makes a turn. This makes it possible to reduce the burden on the driver to perform operations, to bring the attachment 11 properly into the work posture, and to resume the work in the same manner as before the turn. This also makes it possible to quickly resume the work using the attachment 11 and improve work performance.

[0244] (Item 2) The working machine 1 according to item 1, further including a detector 37, 38 (arm detector 37, hitch detector 38) to detect a posture of the working device 4 that includes a position of the working device 4 in an up-down direction, wherein the controller 20 is configured or programmed to include, in the actual control information, device information relating to the posture of the working device 4 at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body 2 turns, actuate the working device 4 based on the device information to change the posture of the working device 4 back to the posture of the working device 4 at the time when the predetermined condition is satisfied.

[0245] With the configuration according to item 2, the controller 20 determines the posture of the working device 4 based on the detection result from the detector(s) 37, 38 before and after the working machine 1 turns and, after the turn of the working machine 1, changes the posture of the working device 4 back to the posture before the turn of the working machine 1. This makes it possible to reliably change the posture of the attachment 11 back to the work posture before the turn automatically. Furthermore, since the controller 20 does not need to determine the posture of the attachment 11 based on the posture of the working device 4, it is possible to reduce the processing load on the controller 20.

[0246] (Item 3) The working machine 1 according to item 1 or 2, wherein the working device 4 includes an arm 10 connected to the machine body 2 swingably in the up-down direction, a hitch 16 connected to a distal portion of the arm 10 swingably in the up-down direction and operable to attach and detach the attachment 11 thereto and therefrom, a first actuator (lift cylinder) 14 to swing the arm 10, and a second actuator (tilt cylinders) 15 to swing the hitch 16, wherein the work manual operator 67 is operable to be operated to actuate the first actuator 14 and / or the second actuator 15 to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 that includes the position and an orientation of the attachment 11, and the controller 20 is configured or programmed to actuate the first actuator 14 and / or the second actuator 15 based on the actual control information to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 back to the previous work posture.

[0247] With the configuration according to item 3, the driver is able to operate the work manual operator 67 to swing the arm(s) 10 and the hitch 16 to bring the working device 4 into an intended posture and also bring the attachment 11 attached to the hitch 16 into an intended posture. Furthermore, by the driver operating the work manual operator 67 to cause the working device 4 to bring the attachment 11 into an intended non-work posture, it is possible to temporarily stop the work. Furthermore, after the working machine 1 turns, the driver does not need to operate the work manual operator 67 to bring the attachment 11 into the work posture (which is more difficult to achieve than the non-work posture), and the controller 20 actuates the first actuator(s) 14 and / or the second actuator(s) 15 to swing the arm(s) 10 and / or the hitch 16 to change the posture of the attachment 11 back to the work posture before the turn automatically, making it possible to reduce the burden on the driver to operate the arm(s) 10 and the hitch 16.

[0248] (Item 4) The working machine 1 according to item 3, further including a travel manual operator 57 to be operated to cause the traveling device 5 to cause the machine body 2 to travel and turn, wherein the controller 20 is configured or programmed to, after the predetermined condition is satisfied, when the travel manual operator 57 is operated to cause the machine body 2 to turn, actuate the first actuator 14 and / or the second actuator 15 to swing the arm 10 and / or the hitch 16 to move the attachment 11 attached to the working device 4 in a direction away from the target object, and when the travel manual operator 57 has not been operated to cause the machine body 2 to turn for a predetermined period or more, or when the travel manual operator 57 is operated to cause the machine body 2 to travel straight after the travel manual operator 57 stops being operated to cause the machine body 2 to turn, actuate the first actuator 14 and / or the second actuator 15 based on the actual control information to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 back to the previous work posture.

[0249] With the configuration according to item 4, by the driver temporarily stopping the work using the attachment 11 and operating the travel manual operator 57 to make a turn, without the need to operate the work manual operator 67, the working device 4 is actuated to bring the attachment 11 automatically into the non-work posture away from the target object, making it possible to further reduce the burden on the driver to perform operations. Furthermore, after the working machine 1 turns, by the driver stopping operating the travel manual operator 57 to make a turn, the posture of the attachment 11 is automatically changed back to the work posture before the turn. This makes it possible to further reduce the burden on the driver to perform operations.

[0250] (Item 5) The working machine 1 according to item 3 or 4, wherein the controller 20 is configured or programmed to include, in the actual control information, device information relating to an actuated position of the first actuator 14 and / or an actuated position of the second actuator 15 at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body 2 turns, change the actuated position of the first actuator 14 and / or the actuated position of the second actuator 15 each back to the actuated position indicated by the device information.

[0251] With the configuration according to item 5, the controller 20 determines the actuated position of the first actuator(s) 14 and / or the second actuator(s) 15 before and after the working machine 1 turns and, after the turn of the working machine 1, changes the actuated position of the first actuator(s) 14 and / or the second actuator(s) 15 back to the actuated position before the turn of the working machine 1. This makes it possible to reliably change the posture of the attachment 11 back to the work posture before the turn automatically. Furthermore, since the controller 20 does not need to determine the posture of the working device 4 and / or the attachment 11 based on the actuated position of the first actuator(s) 14 and / or the second actuator(s) 15, it is possible to reduce the processing load on the controller 20.

[0252] (Item 6) The working machine 1 according to any one of items 3 to 5, further including an input interface 22, 23, 24, 28 (user interface 22, beacon scanner 23, communicator 24, AUX connector 28) to receive input of information relating to the attachment 11 attached to the working device 4, wherein the controller 20 is configured or programmed to, in a case that the attachment 11 corresponding to the information inputted via the input interface 22, 23, 24, 28 is a specific attachment 11, keep an orientation of the attachment 11 constant by actuating the second actuator 15 to swing the hitch 16 when actuating the first actuator 14 to swing the arm 10 to raise or lower the attachment 11.

[0253] With the configuration according to item 6, when the driver operates the work manual operator 67 to swing the arm(s) 10 to raise or lower the specific attachment 11, the orientation and posture of the attachment 11 relative to the target object is kept constant without having to operate the work manual operator 67 to swing the hitch 16, making it possible to further reduce the burden on the driver to perform operations. Furthermore, both when the arm(s) 10 is / are manually swung and when the arm(s) 10 is / are automatically swung, it is possible to eliminate or reduce the likelihood that the orientation of the attachment 11 will change and the attachment 11 will accidentally hit the target object or surrounding objects. This eliminates the need for the driver to operate the work manual operator 67 to avoid hitting an object, making it possible to further reduce the burden on the driver to perform operations.

[0254] (Item 7) The working machine 1 according to any one of items 3 to 6, further including a first detector (arm detector) 37 to detect a position of the arm 10, and a second detector (hitch detector) 38 to detect a position of the hitch 16, wherein the controller 20 is configured or programmed to include, in the predetermined condition, a condition that an actuated position of the first actuator 14 and / or an actuated position of the second actuator 15 determined based on a detection result from the first detector 37 and / or a detection result from the second detector 38 each has / have been in a corresponding actuation range for a predetermined period.

[0255] With the configuration according to item 7, it is possible to appropriately and easily estimate that the work is being performed by the attachment 11 attached to the working device 4 on the working machine 1. Furthermore, by causing the memory and / or the storage 21 to store actual control information including the information indicating the actuated positions of the first actuator(s) 14 and the second actuator(s) 15 relating to the work posture of the attachment 11 before the turn of the working machine 1, and changing the actuated positions of the first actuator(s) 14 and the second actuator(s) 15 back to the corresponding actuated positions indicated by the actual control information after the turn of the working machine 1, it is possible to easily and reliably change the posture of the attachment 11 back to the work posture before the turn automatically.

[0256] (Item 8) The working machine 1 according to item 7, further including an input interface 22, 23, 24, 28 to receive input of information relating to the attachment 11 attached to the working device 4, wherein the controller 20 is configured or programmed to define the actuation range corresponding to the first actuator 14 and / or the second actuator 15 based on the information inputted via the input interface 22, 23, 24, 28.

[0257] With the configuration according to item 8, it is possible to define a predetermined condition and the actuation range(s) of the first actuator(s) 14 and / or the second actuator(s) 15 relating to the work posture corresponding to the attachment 11 attached to the working device 4, possible to more appropriately estimate that the work is being performed by the attachment 11, and possible to more appropriately change the posture of the attachment 11 back to the work posture before the turn automatically.

[0258] (Item 9) The working machine 1 according to item 7 or 8, wherein the controller 20 is configured or programmed to include, in the predetermined condition, a condition that the machine body 2 is traveling straight.

[0259] With the configuration according to item 9, in the case where an attachment 1 to be caused to perform work on a target object in contact therewith by being moved by the working machine 1 traveling straight is attached to the working device 4, it is possible to more appropriately estimate that the work is being performed by the attachment 11. This makes it possible to more appropriately change the posture of the attachment 11 back to the work posture before the turn automatically.

[0260] (Item 10) The working machine 1 according to item 9, further including a travel manual operator 57 to be operated to cause the traveling device 5 to cause the machine body 2 to travel and turn, wherein the controller 20 is configured or programmed to, when the predetermined condition becomes not satisfied because, while the machine body 2 is traveling straight, the work manual operator 67 is operated to swing the arm 10 to move the attachment 11 attached to the working device 4 in a direction away from the target object, after the travel manual operator 57 is operated to cause the machine body 2 to turn, upon passage of a predetermined period or more since the travel manual operator 57 stopped being operated to cause the machine body 2 to turn, or upon operation of the travel manual operator 57 to cause the machine body 2 to travel straight after stoppage of operation of the travel manual operator 57 to cause the machine body 2 to turn, actuate the first actuator 14 and / or the second actuator 15 based on the actual control information to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 back to the previous work posture.

[0261] With the configuration according to item 10, it is possible, at the time when the driver wishes to resume work after the working machine 1 makes a turn, to appropriately change the posture of the attachment 11 back to the work posture before the turn automatically, making it possible to eliminate or reduce the likelihood that the working device 4 will operate in an unintended manner to change the posture of the attachment 11.

[0262] (Item 11) The working machine 1 according to any one of items 1 to 10, further including a power output circuit (auxiliary hydraulic circuit) 4B to output power to an auxiliary actuator 27 provided in or on the attachment 11 to drive the attachment 11, and an input interface 22, 23, 24, 28 to receive input of information relating to the attachment 11 attached to the working device 4, wherein the controller 20 is configured or programmed to, in a case that the attachment 11 corresponding to the information inputted via the input interface 22, 23, 24, 28 is a specific attachment 11 including the auxiliary actuator 27, include, in the predetermined condition, a condition that the controller 20 has been in a predetermined mode in which the controller 20 keeps constant a state of power output to the auxiliary actuator 27 for a predetermined period.

[0263] With the configuration according to item 11, in the case where a specific attachment 11 including an auxiliary actuator 27 is attached to the working device 4, it is possible to more appropriately estimate that the work is being performed by the attachment 11. This makes it possible to more appropriately change the posture of the attachment 11 back to the work posture before the turn automatically.

[0264] (Item 12) The working machine 1 according to any one of items 1 to 11, further including an input interface 22, 23, 24, 28 to receive input of information relating to the attachment 11 attached to the working device 4, wherein the working device 4 is operable to change an orientation of the attached attachment 11 that is included in the posture of the attached attachment 11, and the controller 20 is configured or programmed to define, based on the information inputted via the input interface 22, 23, 24, 28, a turn posture of the attachment 11 that includes the position and the orientation of the attachment 11 when the machine body 2 turns, and, when the machine body 2 turns, actuate the working device 4 to change the posture of the attachment 11 to the turn posture.

[0265] With the configuration according to item 12, it is possible to change the posture of the attachment 11 attached to the working device 4 to the turn posture corresponding to the attachment 11 and cause the working machine 1 to turn more stably, and possible to further reduce the burden on the driver to perform operations.

[0266] While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.

Examples

Embodiment Construction

[0033]Example embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. The drawings are to be viewed in an orientation in which the reference numerals are viewed correctly.

[0034]Example embodiments of the present invention will now be described with reference to the accompanying drawings as necessary.

[0035]FIG. 12 is a side view of a working machine 1 of the present example embodiment. In the present example embodiment, a compact track loader is illustrated as an example of the working machine 1. However, the working machine according to an example embodiment of the present invention is not limited to a compact track loader, and may be, for example, some other construction machine, agricultural machine, or working machine such as a skid-steer loader, a backhoe, or a tractor. The left direction, right direction, the direction approaching the viewer of F...

BACKGROUND OF THE INVENTION1. Field of the Invention

[0001] The present invention relates to working machines such as skid-steer loaders and compact track loaders, and particularly relates to techniques to perform work using each of various types of attachments attached to a working device including arms and the like.2. Description of the Related Art

[0002] Working machines such as skid-steer loaders and compact track loaders each include a machine body, a traveling device to support the machine body to allow the machine body to travel, and a working device attached to the machine body (for example, Japanese Unexamined Patent Application Publication No. 2012-207531). This kind of working machine has one of the attachments which perform various types of work attached to the distal portion of the arms of the working device thereof, and is configured such that the posture, such as the position and orientation, of the attached attachment is changed by the working device and work corresponding to the attachment is performed.

[0003] Some attachments perform work while being moved by the working machine and being kept in the posture in contact with a target object such as a natural object (e.g., earth, soil, plants) or a structure. In the case where such an attachment is attached to the working device of the working machine, the user, for example, operates the working device to bring the attachment into the work posture in contact with the target object, and then manually operates the working machine to travel to perform work using the attachment. Upon the working machine reaching an edge of the worksite, the user manually operates the working machine to turn to change directions of travel of the working machine. In so doing, the user operates the working device to bring the attachment into a non-work posture away from the target object to prevent problems from occurring during the turn. Furthermore, the user, after turning the working machine to change directions, operates the working device to bring the attachment back into the work posture and then causes the working machine to travel and the attachment to resume work. However, it is difficult and tiring for the user to operate the working device to bring the attachment back into the work posture.SUMMARY OF THE INVENTION

[0004] Example embodiments of the present invention make it possible to reduce the burden on the user to operate the working machine and bring the attachment into the work position in a suitable manner.

[0005] A working machine according to an example embodiment of the present invention includes a machine body, a traveling device to cause the machine body to travel and turn, a working device to attach thereto an attachment which is one of a plurality of attachments to perform work by contacting a target object, and change a posture of the attachment attached thereto including a position of the attachment in an up-down direction, a work manual operator to be operated to actuate the working device to change the posture of the attachment, and a controller configured or programmed to control the working device, wherein the controller is configured or programmed to cause a memory and / or a storage to store actual control information relating to the posture of the attachment at a time when a predetermined condition is satisfied, the predetermined condition being a condition which, when satisfied, allows estimation that the work is being performed by the attachment attached to the working device, and after the predetermined condition becomes not satisfied and the machine body turns, actuate the working device based on the actual control information to change the posture of the attachment back to a previous work posture which is the posture of the attachment at the time when the predetermined condition is satisfied.

[0006] In an example embodiment of the present invention, the working machine may further include a detector to detect a posture of the working device that includes a position of the working device in an up-down direction. The controller may be configured or programmed to include, in the actual control information, device information relating to the posture of the working device at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body turns, actuate the working device based on the device information to change the posture of the working device back to the posture of the working device at the time when the predetermined condition is satisfied.

[0007] In an example embodiment of the present invention, the working device may include an arm connected to the machine body swingably in the up-down direction of the machine body, a hitch connected to a distal portion of the arm swingably in the up-down direction and operable to attach and detach the attachment thereto and therefrom, a first actuator to swing the arm, and a second actuator to swing the hitch. The work manual operator may be operable to be operated to actuate the first actuator and / or the second actuator to swing the arm and / or the hitch to change the posture of the attachment that includes the position and an orientation of the attachment. The controller may be configured or programmed to actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

[0008] In an example embodiment of the present invention, the working machine may further include a travel manual operator to be operated to cause the traveling device to cause the machine body to travel and turn. The controller may be configured or programmed to, after the predetermined condition is satisfied, when the travel manual operator is operated to cause the machine body to turn, actuate the first actuator and / or the second actuator to swing the arm and / or the hitch to move the attachment attached to the working device in a direction away from the target object, and when the travel manual operator has not been operated to cause the machine body to turn for a predetermined period or more, or when the travel manual operator is operated to cause the machine body to travel straight after the travel manual operator stops being operated to cause the machine body to turn, actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

[0009] In an example embodiment of the present invention, the controller may be configured or programmed to include, in the actual control information, device information relating to an actuated position of the first actuator and / or an actuated position of the second actuator at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body turns, change the actuated position of the first actuator and / or the actuated position of the second actuator each back to the actuated position indicated by the device information.

[0010] In an example embodiment of the present invention, the working machine may further include an input interface to receive input of information relating to the attachment attached to the working device. The controller may be configured or programmed to, in a case that the attachment corresponding to the information inputted via the input interface is a specific attachment, keep an orientation of the attachment by actuating the second actuator to swing the hitch when actuating the first actuator to swing the arm to raise or lower the attachment.

[0011] In an example embodiment of the present invention, the working machine may further include a first detector to detect a position of the arm, and a second detector to detect a position of the hitch. The controller may be configured or programmed to include, in the predetermined condition, a condition that an actuated position of the first actuator and / or an actuated position of the second actuator determined based on a detection result from the first detector and / or a detection result from the second detector each has / have been in a corresponding actuation range for a predetermined period.

[0012] In an example embodiment of the present invention, the working machine may further include an input interface to receive input of information relating to the attachment attached to the working device. The controller may be configured or programmed to define the actuation range corresponding to the first actuator and / or the second actuator based on the information inputted via the input interface.

[0013] In an example embodiment of the present invention, the controller may be configured or programmed to include, in the predetermined condition, a condition that the machine body is traveling straight.

[0014] In an example embodiment of the present invention, the working machine may further include a travel manual operator to be operated to cause the traveling device to cause the machine body to travel and turn. The controller may be configured or programmed to, when the predetermined condition becomes not satisfied because, while the machine body is traveling straight, the work manual operator is operated to swing the arm to move the attachment attached to the working device in a direction away from the target object, after the travel manual operator is operated to cause the machine body to turn, upon passage of a predetermined period or more since the travel manual operator stopped being operated to cause the machine body to turn, or upon operation of the travel manual operator to cause the machine body to travel straight after stoppage of operation of the travel manual operator to cause the machine body to turn, actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

[0015] In an example embodiment of the present invention, the working machine may further include a power output circuit to output power to an auxiliary actuator provided in or on the attachment to drive the attachment, and an input interface to receive input of information relating to the attachment attached to the working device. The controller may be configured or programmed to, in a case that the attachment corresponding to the information inputted via the input interface is a specific attachment including the auxiliary actuator, include, in the predetermined condition, a condition that the controller has been in a predetermined mode in which the controller keeps constant a state of power output to the auxiliary actuator for a predetermined period.

[0016] In an example embodiment of the present invention, the working machine may further include an input interface to receive input of information relating to the attachment attached to the working device. The working device may be operable to change an orientation of the attached attachment that is included in the posture of the attached attachment. The controller may be configured or programmed to define, based on the information inputted via the input interface, a turn posture of the attachment that includes the position and the orientation of the attachment when the machine body turns, and, when the machine body turns, actuate the working device to change the posture of the attachment to the turn posture.

[0017] The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A more complete appreciation of example embodiments of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings described below.

[0019] FIG. 1 illustrates an example of a work-related hydraulic circuit of a working machine.

[0020] FIG. 2 illustrates an example of a travel-related hydraulic circuit of a working machine.

[0021] FIG. 3 is a block diagram showing an example of an electrical configuration of a working machine.

[0022] FIG. 4 illustrates an example of a hydraulic circuit to actuate a latch cylinder.

[0023] FIG. 5 illustrates an example of attachment information and control information.

[0024] FIG. 6 illustrates an example of an input screen displaying icons of attachments.

[0025] FIG. 7 illustrates an example of actual control information.

[0026] FIG. 8A is a flowchart showing an example of operation of a working machine.

[0027] FIG. 8B is a flowchart continuing from FIG. 8A.

[0028] FIG. 9 shows an example of a work condition determining process in FIG. 8A.

[0029] FIG. 10 illustrates an example of a monitor screen.

[0030] FIG. 11 illustrates another example of a work-related hydraulic circuit of a working machine.

[0031] FIG. 12 is a side view of a working vehicle.

[0032] FIG. 13 is an elevational view of a quick hitch.DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0033] Example embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. The drawings are to be viewed in an orientation in which the reference numerals are viewed correctly.

[0034] Example embodiments of the present invention will now be described with reference to the accompanying drawings as necessary.

[0035] FIG. 12 is a side view of a working machine 1 of the present example embodiment. In the present example embodiment, a compact track loader is illustrated as an example of the working machine 1. However, the working machine according to an example embodiment of the present invention is not limited to a compact track loader, and may be, for example, some other construction machine, agricultural machine, or working machine such as a skid-steer loader, a backhoe, or a tractor. The left direction, right direction, the direction approaching the viewer of FIG. 12, and the direction away from the viewer of FIG. 12 are respectively forward, rearward, left and right directions of the working machine 1. The direction perpendicular to the front-back direction and the up-down direction of the working machine 1 is hereinafter referred to as a machine body width direction.

[0036] The working machine 1 includes a machine body 2, a cabin 3, a working device 4, traveling device(s) 5, and a prime mover 6. The cabin 3 is provided on the machine body 2. The cabin 3 includes a seat 8 therein. The prime mover 6 is provided at a rear portion of the machine body 2. The prime mover 6 is a power source of the working machine 1. In the present example embodiment, the prime mover 6 includes a diesel engine. However, the prime mover 6 may be another internal combustion engine (engine) such as a gasoline engine, and / or may be a motor such as an electric motor.

[0037] The traveling devices 5 are respectively provided on the left and right sides of the machine body 2, and support the machine body 2 such that the machine body 2 is allowed to travel. That is, a pair of the left and right traveling devices 5 are provided. The traveling devices 5 include crawler traveling devices. Note that the traveling devices 5 are not limited to crawler traveling devices, and may be wheeled traveling devices including front wheel(s) and rear wheel(s), or may be semi-crawler traveling devices in which the front wheels or the rear wheels are crawler wheels.

[0038] When the left-side traveling device (left traveling device) 5 and the right-side traveling device (right traveling device) 5 are both driven to rotate forward or both driven to rotate reversely, or when one of them is driven to rotate forward and the other is driven to rotate reversely or is stopped, the machine body 2 (working machine 1) travels forward, travels rearward, or turns left or right. That is, the traveling devices 5 are operable to cause the machine body 2 to travel and turn. Furthermore, as the speed of rotation of the left and right traveling devices 5 changes, the travel speed of the machine body 2 changes, whereas, as the left and right traveling devices 5 stop, the machine body 2 stops. In this way, the traveling devices 5 change the traveling state such as the direction of travel, the travel speed, and the stopping of the machine body 2.

[0039] The working device 4 is provided on the machine body 2. The working device 4 includes arms 10, first links 12, second links 13, lift cylinders 14, tilt cylinders 15, a hitch 16, and an attachment 11. Of these, the arms 10, the first links 12, the second links 13, the lift cylinders 14, and the tilt cylinders 15 are provided on the left and the right of the cabin 3. The left and right arms 10 are connected by a connector.

[0040] The arms 10 are connected to the machine body 2 swingably in the up-down direction relative to the machine body 2. Specifically, the first links 12 and the second links 13 support proximal portions (rear portions) of the arms 10 via shafts such that the arms 10 are swingable in the up-down direction. First ends of the lift cylinders 14 are rotatably connected to the arms 10 via shafts, and opposite second ends of the lift cylinders 14 are rotatably connected to a lower rear portion of the machine body 2 via shafts. The lift cylinders 14 are hydraulic actuators (first actuators) to cause the arms 10 to swing in the up-down direction by extending and retracting.

[0041] The hitch 16 is connected to distal portions of the arms 10 swingably in the up-down direction relative to the distal portion of the arms 10. Specifically, first ends of the tilt cylinders 15 and the distal portions of the arms 10 are respectively rotatably connected to a rear portion of the hitch 16 via shafts. Opposite second ends of the tilt cylinders 15 are rotatably connected to central curved portions of the arms 10 via shafts and brackets. The tilt cylinders 15 are hydraulic actuators (second actuators) to cause the hitch 16 to swing in the up-down direction by extending and retracting. The attachment 11 is attached to the front surface of the hitch 16. The hitch 16 is a linkage to attach and detach the attachment 11 thereto and therefrom.

[0042] FIG. 13 is an elevational view of the quick hitch 16. Specifically, FIG. 13 shows the hitch 16 as seen from the machine body 2 of the working machine 1 in FIG. 12. The hitch 16 includes brackets 30, latching mechanisms 31, a latch cylinder 17, and the like. A pair of the left and right brackets 30 and a pair of the left and right latching mechanisms 31 are provided. The left and right brackets 30 are connected by a beam 39. The distal portions of the left and right arms 10 and the first ends of the left and right tilt cylinders 15 are connected to the left and right brackets 30 via shafts (FIG. 12). The left and right latching mechanisms 31 are respectively provided on the left and right brackets 30.

[0043] Each latching mechanism 31 includes a latch lever 32, a latch pin 33 and the like. An upper portion of the latch lever 32 is rotatably connected to the corresponding bracket 30 via a shaft. The latch pin 33 is held swingably up and down by the bracket 30. A lower end portion of a coil spring 34 is connected to an upper end portion of the latch pin 33 via a shaft, and an upper end portion of the coil spring 34 is connected to a central portion of the latch lever 32 via a shaft.

[0044] The latch cylinder 17 is a hydraulic cylinder (hydraulic actuator) to actuate the latching mechanisms 31 between a latching state and an unlatching state. A first end (distal portion of the rod) of the latch cylinder 17 is rotatably connected to a lower end portion of one of the latch levers 32 via a shaft. An opposite second end (bottom portion of the cylinder case) of the latch cylinder 17 is rotatably connected to a lower end portion of the other the latch levers 32 via a shaft.

[0045] As represented by a solid line in FIG. 13, when the latch cylinder 17 extends with the front surfaces of the brackets 30 abutting a base plate 9 connected to the back surface of the attachment 11, the latch levers 32 rotate to descend, causing the latch pins 33 to be inserted into through-holes 9h in a lower end portion of the base plate 9. With this, the latching mechanisms 31 are brought into a latching state in which the attachment 11 is secured to the brackets 30 (attached to the hitch 16).

[0046] As represented by a dot-dot-dash line in FIG. 13, when the latch cylinder 17 retracts, the latch levers 32 rotate to ascend, allowing the latch pins 33 to be removed from the through-holes 9h of the base plate 9 by the elastic force of the coil springs 34. With this, the latching mechanisms 31 are brought into an unlatching state in which the attachment 11 is not secured to the brackets 30, allowing the attachment 11 to be detached from the hitch 16.

[0047] Since the above-described hitch 16 allows the attachment 11 to be easily replaced with another one, the hitch 16 is called a “quick hitch” or “quick changer”. Note that another actuator such as a hydraulic motor may be used instead of the latch cylinder 17, or an electric actuator such as an electric motor or an electric cylinder may be used instead of the latch cylinder 17.

[0048] When the arms 10 are caused to swing in the up-down direction by the lift cylinders 14 with the attachment 11 attached to the hitch 16 as described above, the attachment 11 is raised or lowered, and the position (height) of the attachment 11 in the up-down direction relative to the machine body 2 and to the target object and the position of the attachment 11 in the front-back direction are changed. When the hitch 16 is caused to swing in the up-down direction by the tilt cylinders 15, the attachment 11 also swings in the up-down direction, and the tilt angle of the attachment 11, i.e., the orientation (which includes the pitch angle relative to the front-rear direction) of the attachment 11 relative to the machine body 2 and the target object, is changed.

[0049] Thus, the working device 4 is a posture changing device to change the posture including the position and the orientation of the attachment 11. Furthermore, with regard to the working device 4, since the arms 10 and the hitch 16 are individually swingable, the working device 4 can, when at least one of the arms 10 or the hitch 16 swing(s) with the attachment 11 attached, change the posture including at least one of the height or the orientation of the attachment 11 relative to the machine body 2 and the target object. The attachment 11 is changed between a work posture in which the working device 4 can perform work on a target object and a non-work posture in which the working device 4 does not perform work. The working machine 1 includes a working unit 4U including the working device 4 and the attachment 11 attached to the working device 4.

[0050] The working device 4 (hitch 16) is operable to attach thereto and detach therefrom each of attachments 11 to perform various types of work, and a selected one of the attachments 11 is attached to the working device (hitch 16). The attachment 11 is a working tool to perform work. The working machine 1 performs work corresponding to the attachment 11 attached to the working device 4.

[0051] Examples of the attachment 11 attachable to the working device 4 include attachments 11 with no actuators and attachments 11 including an actuator. For example, buckets, pallet forks, and the like do not include actuators. For example, sweepers, snow blowers, snow blades, angle brooms, mowers, plows, skid cutters, breakers, earth augers, spreaders, and the like each include an actuator and are driven by power from the actuator. The actuator in or on the attachment 11 is actuated by power from the working machine 1.

[0052] For example, spreaders and the like are non-contact work attachments 11 which perform work such as spreading fertilizer or agricultural chemicals while being moved by the working machine 1 without contacting the target object such as earth or crops.

[0053] For example, buckets, sweepers, snow blowers, snow blades, angle brooms, hopper brooms, mowers, plows, skid cutters, and the like are contacting / moved work attachments 11 to perform work such as carrying, removing, adjusting, or destroying a target object such as earth, soil, or plants while being moved by the working machine 1 and being kept in contact with the target object. In the example shown in FIG. 12, a sweeper, which is a contacting / moved work attachment 11 including an auxiliary actuator 27, is attached to the working device 4 (hitch 16).

[0054] In the case where a contacting / moved work attachment 11 is attached to the working device 4 of the working machine 4, the user, for example, operates the working device 4 to bring the attachment 11 into a work posture in contact with the target object, and then manually operates the working machine 1 to travel to perform work using the attachment 11. Upon the working machine 1 reaching an edge of the worksite, the user manually operates the working device 4 to or causes the working device 4 to automatically bring the attachment 11 into a non-work posture away from the target object, and then manually operates the working machine 1 to turn to change the direction of travel of the working machine 1. Furthermore, the user, after turning the working machine 1 to change the direction of travel, manually operates the working device 4 to or causes the working device 4 to automatically bring the attachment 11 back into the work posture, and then manually operates the working machine 1 to travel and the attachment 11 to resume work.

[0055] In the present example embodiment, the actuator(s) provided in or on the drive attachment 11 is a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder. For example, an auxiliary actuator 27 provided in or on the sweeper (attachment) 11 shown in FIG. 12 is a hydraulic motor which drives the sweeper 11.

[0056] The auxiliary actuator 27 provided in or on the drive attachment 11 is actuated by hydraulic fluid supplied from the working machine 1. As shown in FIG. 12, the machine body 2 of the working machine 1 is provided with AUX port(s) (auxiliary port(s)) 25 at a front portion thereof. The AUX ports 25 allow hydraulic fluid to flow to and from the auxiliary actuator 27. The AUX ports 25 include a first AUX port 25a and a second AUX port 25b. The attachment 11 includes a first hydraulic port and a second hydraulic port. Each port includes a coupler.

[0057] For example, the user or the like connects an external fluid passage 26a including a hose or the like to the first AUX port 25a and to the first hydraulic port of the attachment 11, and connects an external fluid passage 26b to the second hydraulic port of the attachment 11 and to the second AUX port 25b. With this, hydraulic fluid is allowed to flow out (to be supplied) from the working machine 1 to the auxiliary actuator 27 of the attachment 11, and is allowed to flow from the auxiliary actuator 27 into (returns to) the working machine 1. This defines a hydraulic circuit between the working machine 1 and the auxiliary actuator 27, so that the auxiliary actuator 27 can be actuated by hydraulic fluid from the working machine 1 to cause the attachment 11 to perform work. In the example in FIG. 12, the above circuit allows a brush 11b, which is a driven portion of the sweeper, to be driven to rotate by power from the auxiliary actuator 27 and to perform work to remove a target object such as dust on a ground J.

[0058] As described above, the actuators 14, 15 and 27 provided in or on the working device 4 and the attachment 11 are actuated by hydraulic fluid to cause the working device 4 and the attachment 11 to perform work. Note that some attachments are electric-driven attachments including electric actuator(s) such as an electric motor and / or an electric cylinder. Such an electric-driven attachment performs work in the following manner. Electricity from a battery provided in or on the working machine 1 is inputted into an electric actuator via an electric connector and an electric cable in or on the machine body 2, so that the electric actuator is actuated and the attachment is driven by power from the actuator, making it possible to perform work.

[0059] FIG. 1 illustrates a work-related hydraulic circuit 4A included in the working machine 1. This hydraulic circuit 4A causes the working device 4 and the attachment 11 to operate. The working machine 1 includes a pilot pump P1 and a main pump P2. For example, the pilot pump P1 is a fixed displacement hydraulic pump, and the main pump P2 is a variable displacement hydraulic pump.

[0060] The pilot pump P1 is actuated by power from the prime mover 6 to deliver hydraulic fluid stored in a hydraulic fluid tank T to a fluid passage 40. The hydraulic fluid delivered by the pilot pump P1 is pilot fluid to control various hydraulic devices provided in the working machine 1. The pressure of pilot fluid is a pilot pressure.

[0061] The main pump P2 is actuated by power from the prime mover 6 to deliver hydraulic fluid stored in the hydraulic fluid tank T to a main fluid passage 45. The hydraulic fluid delivered by the main pump P2 is used to actuate the lift cylinders 14 and the tilt cylinders 15 of the working device 4, as well as hydraulic device(s) such as the auxiliary actuator 27 provided in or on the attachment 11.

[0062] The working machine 1 includes a plurality of control valves 60A, 60B and 60C. The plurality of control valves 60A, 60B and 60C include a lift control valve 60A, a tilt control valve 60B, and an auxiliary (AUX) control valve 60C. The plurality of control valves 60 are each connected to the main fluid passage 45. The lift control valve 60A controls the flow rate (output) and the supply direction of hydraulic fluid supplied from the main fluid passage 45 to the lift cylinders 14 to actuate the lift cylinders 14. The tilt control valve 60B controls the flow rate (output) and the supply direction of hydraulic fluid supplied from the main fluid passage 45 to the tilt cylinders 15 to actuate the tilt cylinders 15. The AUX control valve 60C controls the flow rate and the supply direction of the hydraulic fluid supplied from the main fluid passage 45 to the auxiliary actuator 27 via the AUX port(s) 25 to actuate the auxiliary actuator 27.

[0063] The lift control valve 60A is connected to the lift cylinders 14 via a plurality of fluid passages 64a and 64b. The lift control valve 60A is a pilot-operated, direct-acting spool three-position switching valve. The lift control valve 60A includes a plurality of work pressure receivers 61a and 61b, and switches between a third position (neutral position) 61c, a first position 61d different from the third position 61c, and a second position 61e different from the third position 61c and the first position 61d depending on the pilot pressure acting on the work pressure receiver(s) 61a and / or 61b. When the lift control valve 60A is in the third position 61c, hydraulic fluid is not supplied from the main fluid passage 45 to the lift cylinders 14.

[0064] When the lift control valve 60A switches to the first position 61d or the second position 61e, hydraulic fluid from the main fluid passage 45 is supplied to the lift cylinders 14 via the lift control valve 60A and the fluid passage 64a or 64b. When the opening of the lift control valve 60A changes according to the pilot pressure while the lift control valve 60A is in the first position 61d or the second position 61e, the flow rate of hydraulic fluid from the main fluid passage 45 to the lift cylinders 14 is changed. Thus, the lift control valve 60A controls the supply direction and the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the lift cylinders 14 according to the pilot pressure acting on the work pressure receiver(s) 61a and / or 61b to cause the lift cylinders 14 to extend or retract.

[0065] More specifically, when the lift control valve 60A switches to the first position 61d, hydraulic fluid from the main fluid passage 45 flows through the lift control valve 60A and the fluid passage 64a and is supplied to the rod-side chambers of the lift cylinders 14. With this, the lift cylinders 14 retract, the arms 10 swing downward, and the attachment 11 attached to the hitch 16 lowers. The hydraulic fluid pushed out of the cap-side chambers of the lift cylinders 14 flows through the fluid passage 64b and is drained from the lift control valve 60A.

[0066] When the lift control valve 60A switches to the second position 61e, hydraulic fluid from the main fluid passage 45 flows through the lift control valve 60A and the fluid passage 64b, and is supplied to the cap-side chambers of the lift cylinders 14. With this, the lift cylinders 14 extend, the arms 10 swing upward, and the attachment 11 attached to the hitch 16 is raised. The hydraulic fluid pushed out from the rod-side chambers of the lift cylinders 14 flows through the fluid passage 64a and is drained from the lift control valve 60A.

[0067] The tilt control valve 60B is connected to the tilt cylinders 15 by a plurality of fluid passages 65a and 65b. The tilt control valve 60B is a pilot-operated, direct-acting spool three-way switching valve. The tilt control valve 60B includes a plurality of work pressure receivers 62a and 62b, and switches between a third position (neutral position) 62c, a first position 62d different from the third position 62c, and a second position 62e different from the third position 62c and the first position 62d, depending on the pilot pressure acting on the work pressure receiver(s) 62a and / or 62b. When the tilt control valve 60B is in the third position 62c, hydraulic fluid is not supplied from the main fluid passage 45 to the tilt cylinders 15.

[0068] The tilt control valve 60B switches to the first position 62d or the second position 62e to allow hydraulic fluid from the main fluid passage 45 to be supplied to the tilt cylinders 15 via the tilt control valve 60B and the fluid passage 65a or 65b. When the opening of the tilt control valve 60B changes according to the pilot pressure while the tilt control valve 60B is in the first position 62d or the second position 62e, the flow rate of hydraulic fluid from the main fluid passage 45 to the tilt cylinders 15 is changed. Thus, the tilt control valve 60B controls the supply direction and the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the tilt cylinders 15 according to the pilot pressure acting on the work pressure receiver(s) 62a and / or 62b to cause the tilt cylinders 15 to extend or retract.

[0069] More specifically, when the tilt control valve 60B switches to the first position 62d, hydraulic fluid from the main fluid passage 45 flows through the tilt control valve 60B and the fluid passage 65b, and is supplied to the cap-side chambers of the tilt cylinders 15. With this, the tilt cylinders 15 extend, the hitch 16 swings downward, the tilt angle of the attachment 11 attached to the hitch 16 decreases, and the orientation is changed such that the front portion of the attachment 11 lowers. The hydraulic fluid pushed out of the rod-side chambers of the tilt cylinders 15 flows through the fluid passage 65b and is drained from the tilt control valve 60B.

[0070] When the tilt control valve 60B switches to the second position 62e, hydraulic fluid from the main fluid passage 45 flows through the tilt control valve 60B and the fluid passage 65a, and is supplied to the rod-side chambers of the tilt cylinders 15. With this, the tilt cylinders 15 retract, the hitch 16 swings upward, the tilt angle of the attachment 11 attached to the hitch 16 increases, and the orientation is changed such that the front portion of the attachment 11 is raised. The hydraulic fluid pushed out from the cap-side chambers of the tilt cylinders 15 flows through the fluid passage 65a and is drained from the tilt control valve 60B.

[0071] The AUX control valve 60C is connected to the AUX ports 25 via a plurality of AUX fluid passages (auxiliary fluid passages) 66a and 66b. Specifically, a first port of the AUX control valve 60C and the first AUX port 25a are connected via the AUX fluid passage 66a, and a second port of the AUX control valve 60C and the second AUX port 25b are connected via the AUX fluid passage 66b. The AUX control valve 60C is a pilot-operated, direct-acting spool three-position switching valve. The AUX control valve 60C includes a plurality of AUX pressure receivers 63a and 63b, and switches between a third position (neutral position) 63c, a first position 63d different from the third position 63c, and a second position 63e different from the third position 63c and the first position 63d, depending on the pilot pressure acting on the AUX pressure receiver(s) 63a and / or 63b.

[0072] When the AUX control valve 60C is in the third position 63c, hydraulic fluid is not supplied to the auxiliary actuator 27 from the main fluid passage 45 via the AUX fluid passage 66a or 66b and the AUX port(s) 25. When the AUX control valve 60C switches to the first position 63d or the second position 63e, hydraulic fluid from the main fluid passage 45 is supplied to the auxiliary actuator 27 via the AUX control valve 60C, the AUX fluid passage 66a or 66b, and the corresponding AUX port 25, and the supply direction of the hydraulic fluid changes.

[0073] More specifically, when the AUX control valve 60C switches to the first position 63d, hydraulic fluid from the main fluid passage 45 is supplied to the auxiliary actuator 27 via the AUX control valve 60C, the AUX fluid passage 66a and the first AUX port 25a, and return fluid from the auxiliary actuator 27 flows through the second AUX port 25b and the AUX fluid passage 66b and is drained from the AUX control valve 60C. When the AUX control valve 60C switches to the second position 63e, hydraulic fluid from the main fluid passage 45 is supplied to the auxiliary actuator 27 via the AUX control valve 60C, the AUX fluid passage 66b and the second AUX port 25b, and return fluid from the auxiliary actuator 27 flows through the first AUX port 25a and the AUX fluid passage 66a and is drained from the AUX control valve 60C.

[0074] When the opening of the AUX control valve 60C changes according to the pilot pressure while the AUX control valve 60C is in the first position 63d or the second position 63e, the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the auxiliary actuator 27 via the corresponding AUX port 25 is changed.

[0075] As described above, the AUX control valve 60C controls the supply direction and the flow rate of hydraulic fluid supplied from the main fluid passage 45 to the auxiliary actuator 27 via the corresponding AUX fluid passage 66a or 66b and the corresponding AUX port 25 according to the pilot pressure acting on the AUX pressure receiver(s) 63a and / or 63b to actuate the auxiliary actuator 27. The AUX control valve 60C, the AUX fluid passages 66a and 66b, and the AUX ports 25 define an auxiliary hydraulic circuit (power output circuit) 4B to supply (output) hydraulic fluid (i.e., power) to the auxiliary actuator 27 of the attachment 11, and the auxiliary hydraulic circuit 4B is provided in the working machine 1.

[0076] The working machine 1 includes pressure detectors 70a and 70b. The pressure detectors 70a and 70b include pressure sensors. The pressure detector 70a is provided in the AUX fluid passage 66a to detect an AUX pressure (auxiliary pressure) which is the pressure of hydraulic fluid flowing from the AUX control valve 60C through the AUX fluid passage 66a and is supplied to the auxiliary actuator 27 of the attachment 11. The pressure detector 70b is provided in the AUX fluid passage 66b to detect an AUX pressure which is the pressure of hydraulic fluid flowing from the AUX control valve 60C through the AUX fluid passage 66b and is supplied to the auxiliary actuator 27. During work performed by the attachment 11 including the auxiliary actuator 27, the AUX pressure detected by the pressure detector(s) 70a and / or 70b can be regarded as a load on the attachment 11.

[0077] Note that the pressure detectors 70a and 70b also detect the pressure of hydraulic fluid (return fluid) flowing from the auxiliary actuator 27 through the corresponding AUX fluid passage 66a or 66b and returning to the AUX control valve 60C. However, since the pressure is equal to or substantially equal to the atmospheric pressure, the pressure is not regarded as auxiliary pressure by a controller 20.

[0078] The working machine 1 includes a plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b. The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b are proportional valves in each of which the solenoid is energized and the opening is changed according to a control signal (electric current signal) inputted thereto. The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b are each connected to fluid passages 40b and 40c branching from the fluid discharge passage 40, and a change in the opening thereof changes the pilot pressure of pilot fluid supplied from the fluid discharge passage 40. Specifically, as the electric current value of the control signal inputted increases, the opening of the plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b increases, allowing pilot fluid from the fluid discharge passage 40 to be outputted with an increased pilot pressure.

[0079] The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b include lift solenoid valves 76a and 76b, tilt solenoid valves 77a and 77b, and AUX solenoid valves 78a and 78b. The lift solenoid valves 76a and 76b are respectively connected to the work pressure receivers 61a and 61b of the lift control valve 60A via fluid passages. The tilt solenoid valves 77a and 77b are respectively connected to the work pressure receivers 62a and 62b of the tilt control valve 60B via fluid passages. The AUX solenoid valves 78a and 78b are respectively connected to the AUX pressure receivers 63a and 63b of the AUX control valve 60C via fluid passages.

[0080] When the opening of the lift solenoid valve 76a is greater than 0 (zero), pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 61a from the lift solenoid valve 76a. In so doing, a pilot pressure corresponding to the opening of the lift solenoid valve 76a acts on the work pressure receiver 61a. When the pilot pressure acting on the work pressure receiver 61a is equal to or higher than a predetermined value, the spool of the lift control valve 60A moves, and the lift control valve 60A switches to the first position 61d. With this, the lift cylinders 14 retract and the attachment 11 lowers, and therefore the lift solenoid valve 76a is a solenoid valve to lower the attachment.

[0081] Similarly, when the opening of the lift solenoid valve 76b increases, pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 61b from the lift solenoid valve 76b, and the lift control valve 60A switches to the second position 61e. With this, the lift cylinders 14 extend and the attachment 11 is raised, and therefore the lift solenoid valve 76b is a solenoid valve to raise the attachment.

[0082] Similarly, when the opening of the tilt solenoid valve 77a increases, pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 62a from the tilt solenoid valve 77a, and the tilt control valve 60B switches to the first position 62d. With this, the tilt cylinders 15 extend and the tilt angle of the attachment 11 decreases, and therefore the tilt solenoid valve 77a is a solenoid valve to lower the front portion of the attachment. When the opening of the tilt solenoid valve 77b increases, pilot fluid from the fluid discharge passage 40 acts on the work pressure receiver 62b from the tilt solenoid valve 77b, and the tilt control valve 60B switches to the second position 62e. With this, the tilt cylinders 15 retract and the tilt angle of the attachment 11 increases, and therefore the tilt solenoid valve 77b is a solenoid valve to raise the front portion of the attachment.

[0083] Similarly, when the opening of the AUX solenoid valve 78a increases, pilot fluid from the fluid discharge passage 40 acts on the AUX pressure receiver 63a via the AUX solenoid valve 78a, and the AUX control valve 60C switches to the first position 63d. With this, hydraulic fluid is supplied from the AUX control valve 60C to the auxiliary actuator 27 via the AUX fluid passage 66a and the first AUX port 25a. When the opening of the AUX solenoid valve 78b increases, pilot fluid from the fluid discharge passage 40 acts on the AUX pressure receiver 63b via the AUX solenoid valve 78b, and the AUX control valve 60C switches to the second position 63e. With this, hydraulic fluid is supplied from the AUX control valve 60C to the auxiliary actuator 27 via the AUX fluid passage 66b and the second AUX port 25b.

[0084] The plurality of solenoid valves 76a, 76b, 77a, 77b, 78a and 78b change the pilot pressure to act on the corresponding pressure receivers 61a, 61b, 62a, 62b, 63a and 63b according to the control signals inputted thereto to change the flow rate of hydraulic fluid from the corresponding control valves 60A, 60B and 60C to the corresponding actuators 14, 15 and 27.

[0085] The working machine 1 includes a work manual operator (work manual operator unit) 67 and the controller 20. The work manual operator 67 is a manual operator to be operated to actuate the working device 4 to cause the working device 4 to freely change the posture of the attachment 11, and to control the swinging of the arms 10 and the hitch 16. The work manual operator 67 includes a digital joystick. The work manual operator 67 includes a work operating lever 67a and a sensor 67b. The work operating lever 67a is a manual operator (work manual operator) to be operated by the driver of the working machine, and is provided in the vicinity of the seat 8 inside the cabin 3. The work operating lever 67a can be operated not only forward and rearward from a neutral position, but also leftward and rightward from the neutral position.

[0086] The sensor 67b includes at least one of an angle sensor or an electric circuit, detects the operation direction and the operation angle (angle of pivoting) of the work operating lever 67a, and outputs a detection signal (electric signal) corresponding to the operation direction and the operation angle. The controller 20 determines the operation direction and the operation angle of the work operating lever 67a based on the detection signal outputted from the sensor 67b, and calculates the ratio of the operation angle to the maximum angle of pivoting of the work operating lever 67a as the operation amount of the work operating lever 67a.

[0087] The controller 20 then inputs a control signal into the lift solenoid valve 76a or 76b or the tilt solenoid valve 77a or 77b according to the operation direction and the operation amount of the work operating lever 67a to open the solenoid valve. With this, a corresponding one of the lift control valve 60A and the tilt control valve 60B switches to the first position 61d, 62d or the second position 61e, 62e, the lift cylinders 14 or the tilt cylinders 15 extend or retract, the arms 10 or the hitch 16 swing(s) in the corresponding direction, and the position including the height or the orientation (tilt angle) of the attachment 11 attached to the hitch 16 is changed.

[0088] Specifically, when the work operating lever 67a is pivoted forward, the controller 20 inputs a control signal into the lift solenoid valve 76a according to the operation amount of the work operating lever 67 to open the lift solenoid valve 76a. With this, the lift control valve 60A switches to the first position 61d, the lift cylinders 14 retract, the arms 10 swing downward, the attachment 11 lowers, and the height of the attachment 11 decreases. In so doing, the attachment 11 is positioned somewhat forward.

[0089] When the work operating lever 67a is pivoted rearward, the controller 20 inputs a control signal into the lift solenoid valve 76b according to the operation amount of the work operating lever 67a to open the lift solenoid valve 76b. With this, the lift control valve 60A switches to the second position 61e, the lift cylinders 14 extend, the arms 10 swing upward, the attachment 11 is raised, and the height of the attachment 11 increases. In so doing, the attachment 11 is positioned somewhat rearward.

[0090] When the work operating lever 67a is pivoted leftward, the controller 20 inputs a control signal into the tilt solenoid valve 77a according to the operation amount of the work operating lever 67a to open the tilt solenoid valve 77a. With this, the tilt control valve 60B switches to the first position 62d, the tilt cylinders 15 extend, and the hitch 16 swings downward, so that the orientation of the attachment 11 is changed such that the front portion of the attachment 11 lowers.

[0091] When the work operating lever 67a is pivoted rightward, the controller 20 inputs a control signal into the tilt solenoid valve 77b according to the operation amount of the work operating lever 67a to open the tilt solenoid valve 77b. With this, the tilt control valve 60B switches to the second position 62e, the tilt cylinders 15 retract, the hitch 16 swings upward, so that the orientation of the attachment 11 is changed such that the front portion of the attachment 11 is raised.

[0092] Note that when the controller 20 causes the arms 10 to swing, the controller 20 causes the hitch 16 to swing so that the orientation of the attachment 11 is not changed. That is, the controller 20, when causing the arms 10 to swing by inputting a control signal into one of the lift solenoid valves 76a and 76b, the controller 20 also inputs a control signal into a corresponding one of the tilt solenoid valves 77a and 77b that corresponds to the swinging direction of the arms 10 to cause the hitch 16 to swing, thus keeping the orientation of the attachment 11 constant. This eliminates or reduces the likelihood that, when the arms 10 swing, the attachment 11 will tilt and accidentally contact a target object or surrounding objects and be damaged. As described above, the controller 20 controls actuation of the working device 4 in response to manual operation of the work manual operator 67 (work operating lever 67a). The controller 20 also automatically controls actuation of the working device 4.

[0093] The working machine 1 includes an AUX output switch 73b. The AUX output switch 73b is an operating switch to be operated by the driver. The AUX output switch 73b is turned ON to start supplying hydraulic fluid to the corresponding AUX port 25, and is turned OFF to stop supplying the hydraulic fluid.

[0094] When the controller 20 is in an AUX mode in which the attachment 11 including the auxiliary actuator 27 is allowed to be used with the working machine 1, if the AUX output switch 73b is turned ON, the controller 20 inputs a control signal into one of the AUX solenoid valves 78a and 78b to open the solenoid valve. With this, the AUX control valve 60C switches to the first position 63d or the second position 63e, and hydraulic fluid is supplied from the AUX control valve 60C to the corresponding AUX port 25 via the AUX fluid passage 66a or the AUX fluid passage 66b. In so doing, if the AUX ports 25 and hydraulic ports of the attachment 11 are connected by the external fluid passages 26, hydraulic fluid is supplied from the corresponding AUX port 25 to the auxiliary actuator 27 of the attachment 11 via the corresponding external fluid passage 26 and the like, the auxiliary actuator 27 is actuated, and the attachment 11 is driven.

[0095] When the controller 20 is in the AUX mode, if the AUX output switch 73b is turned OFF, the controller 20 stops inputting the control signal into the AUX solenoid valve 78a or 78b to close the AUX solenoid valve 78a or 78b. With this, the AUX control valve 60C switches to the third position 63c, and the supply of hydraulic fluid from the AUX control valve 60C to the AUX port 25 is stopped. Thus, the supply of hydraulic fluid to the auxiliary actuator 27 of the attachment 11 is also stopped, the auxiliary actuator 27 stops, and the attachment 11 stops.

[0096] The controller 20 inputs a control signal into at least one of the lift solenoid valve 76b or 76b or the tilt solenoid valve 77a or 77b according to the AUX pressure detected by the pressure detectors 70a and 70b to adjust the opening of the solenoid valve(s). With this, the controller 20 switches at least one of the lift control valve 60A or the tilt control valve 60B to the first position or the second position to supply hydraulic fluid to at least one of the lift cylinders 14 or the tilt cylinders 15 to cause the cylinders to extend or retract to cause at least one of the arms 10 or the hitch 16 to swing, thus adjusting at least one of the position or the orientation of the attachment 11.

[0097] The working machine 1 includes a load sensing system (which may be hereinafter simply referred to as “LS system”) 80. The LS system 80 is a hydraulic system to control the flow rate of hydraulic fluid delivered by the variable displacement main pump P2 such that a differential pressure is constant. The differential pressure is obtained by subtracting, from the hydraulic fluid delivery pressure of the main pump P2 which is a variable displacement pump, the maximum of load pressures on the actuators 14, 15 and 27 actuated by hydraulic fluid delivered by the main pump P2.

[0098] The LS system 80 includes a swash plate changing cylinder 81, a flow rate compensation valve 82, and an opening changing cylinder 83. The swash plate changing cylinder 81 adjusts the angle of the swash plate of the main pump P2. The flow rate compensation valve 82 causes a hydraulic pressure to act on the swash plate changing cylinder 81 to actuate the swash plate changing cylinder 81. The opening changing cylinder 83 is actuated by the pilot pressure of pilot fluid from the pilot pump P1 to change the opening of the flow rate compensation valve 82.

[0099] A PLS fluid passage 84 and a PPS fluid passage 85 are connected to the flow rate compensation valve 82. The PLS fluid passage 84 is a fluid passage to transmit a PLS pressure which is the maximum of the load pressures on the actuators 14, 15 and 27 (actuator maximum load pressure). The PPS fluid passage 85 is used to transmit a PPS pressure which is the delivery pressure of the main pump P2. The flow rate compensation valve 82 actuates the swash plate changing cylinder 81 to adjust the angle of the swash plate of the main pump P2 such that the differential pressure, which is obtained by subtracting the PLS pressure from the PPS pressure, is constant. With this, the flow rate of hydraulic fluid delivered by the main pump P2 is controlled, and hydraulic power corresponding to the load applied to the working device 4 and the attachment 11 is outputted from the main pump P2.

[0100] In the present example embodiment, the swash plate of the main pump P2 is pressed by the self-pressure thereof in a direction that increases the flow rate of hydraulic delivered by the main pump P2. The swash plate changing cylinder 81 is operable to cause a force against the self-pressure of the main pump P2 to act on the swash plate. Furthermore, the flow rate compensation valve 82 is operable to control the delivery flow rate of the main pump P2 by adjusting the hydraulic pressure acting on the swash plate changing cylinder 81. Thus, when the hydraulic pressure acting on the swash plate changing cylinder 81 is removed (becomes zero), the angle of the swash plate of the main pump P2 becomes maximum, and the flow rate of hydraulic fluid delivered by the main pump P2 becomes maximum.

[0101] FIG. 2 illustrates a travel-related hydraulic circuit 5A included in the working machine 1. The hydraulic circuit 5A actuates the traveling devices 5 to cause the working machine 1 to travel. The working machine 1 includes travel pumps 50 and travel motors 51.

[0102] Each travel pump 50 is a hydraulic pump to be actuated by power from the prime mover 6. The travel pump 50 is a swash-plate variable displacement axial pump and includes pressure receivers 50a and 50b to receive pilot pressure. The pump pressure receivers 50a and 50b include a forward-travel pump pressure receiver 50a and a rearward-travel pump pressure receiver 50b. The angle of the swash plate of the travel pump 50 is changed according to the pilot pressure acting on the pump pressure receiver(s) 50a and / or 50b. When the angle of the swash plate of the travel pump 50 is changed, the flow rate and the supply direction of the hydraulic fluid delivered by the travel pump 50 change. The travel pumps 50 include a first travel pump 50L corresponding to the first traveling device 5, and a second travel pump 50R corresponding to the second traveling device 5.

[0103] Each travel motor 51 is a hydraulic motor to be actuated by hydraulic fluid delivered by the corresponding travel pump 50. The travel motors 51 include a first travel motor 51L corresponding to the first travel pump 50L, and a second travel motor 51R corresponding to the second travel pump 50R.

[0104] The first travel motor 51L is connected to the first travel pump 50L via a closed loop circuit fluid passage 53a. The first travel motor 51L is actuated by hydraulic fluid supplied from the first travel pump 50L. The first travel motor 51L includes an output shaft 51Lj, and changes the rotation speed of the output shaft 51Lj based on the flow rate of hydraulic fluid delivered by the first travel pump 50L. When the power from the first travel motor 51L is transmitted from the output shaft 51Lj to the drive shaft of the first traveling device 5 via a transmission mechanism, the first traveling device 5 is driven.

[0105] The first travel motor 51L includes a swash plate. When the angle of the swash plate of the first travel motor 51L is changed by a swash plate cylinder 52L, the first travel motor 51L changes the rotation speed stage of the output shaft 51Lj to a first speed stage (low speed stage) or a second speed stage (high speed stage) higher than the first speed stage. Specifically, when the swash plate cylinder 52L retracts, the rotation speed of the output shaft 51Lj of the first travel motor 51L is set to the first speed stage. When the swash plate cylinder 52L extends, the rotation speed of the output shaft 51Lj of the first travel motor 51L is set to the second speed stage.

[0106] The second travel motor 51R is connected to the second travel pump 50R via a closed loop circuit fluid passage 53b. The second travel motor 51R is actuated by hydraulic fluid delivered by the second travel pump 50R to drive the second traveling device 5 via an output shaft 51Rj and the like. When the angle of the swash plate of the second travel motor 51R is changed by a swash plate cylinder 52R, the second travel motor 51R changes the rotation speed stage of the output shaft 51Rj to the first speed stage or the second speed stage. Since the configurations of the second travel motor 51R, the second travel pump 50R, the second traveling device 5 and the swash plate cylinder 52R are respectively the same as the configurations of the first travel motor 51L, the first travel pump 50L, the first traveling device 5 and the swash plate cylinder 52L, detailed description therefor is omitted.

[0107] The working machine 1 includes a travel manual operator (travel manual operator unit) 57. The travel manual operator 57 is operated to control the travel pumps 50, the travel motors 51, and the traveling devices 5. The travel manual operator 57 is operable to be operated to cause the traveling devices 5 and the like to cause the machine body 2 to travel and turn. The travel manual operator 57 is operable to change the pilot pressure applied to the pump pressure receivers 50a, 50b of the travel pumps 50 to change the angle of swash plates of the travel pumps 50 to change the amount and direction of hydraulic fluid delivered by the travel pumps 50, the speed and direction of rotation of the output shafts 51Lj, 51Rj of the travel motors 51, and the speed and direction of operation of the traveling devices 5. The travel manual operator 57 includes a travel operating lever 57a and a plurality of operating valves 44.

[0108] The travel operating lever 57a is a manual operator (travel manual operator) to be operated by the driver, and is provided in the vicinity of the seat 8 inside the cabin 3. The travel operating lever 57a can be operated from the neutral position in a forward direction F, a rearward direction B, a leftward direction L, and a rightward direction R, as well as from the neutral position diagonally leftward and forward, diagonally rightward and forward, diagonally leftward and rearward, and diagonally rightward and rearward.

[0109] The operating valves 44 include operating valves 44a, 44b, 44c, and 44d. The operating valves 44a to 44d are connected to a fluid discharge passage 40, and are actuated by operation of the common travel operating lever 57a to change the pilot pressure of pilot fluid which is hydraulic fluid supplied from the fluid discharge passage 40.

[0110] Specifically, the first operating valve 44a is operable to, when the travel operating lever 57a is pivoted in the forward direction F, change the pilot pressure outputted therefrom according to the operation amount (angle of pivoting). The second operating valve 44b is operable to, when the travel operating lever 57a is pivoted in the rearward direction B, change the pilot pressure outputted therefrom according to the operation amount. The third operating valve 44c is operable to, when the travel operating lever 57a is pivoted in the leftward direction L, change the pilot pressure outputted therefrom according to the operation amount. The fourth operating valve 44d is operable to, when the travel operating lever 57a is pivoted in the rightward direction R, change the pilot pressure outputted therefrom according to the operation amount.

[0111] The operating valves 44 are connected to their corresponding travel pumps 50 by travel fluid passages 42. The travel fluid passages 42 include a first travel fluid passage 42a, a second travel fluid passage 42b, a third travel fluid passage 42c, a fourth travel fluid passage 42d, and a fifth travel fluid passage 42e. The first travel fluid passage 42a is connected to a forward-travel pump pressure receiver 50a of the first travel pump 50L. The second travel fluid passage 42b is connected to a rearward-travel pump pressure receiver 50b of the first travel pump 50L. The third travel fluid passage 42c is connected to a forward-travel pump pressure receiver 50a of the second travel pump 50R. The fourth travel fluid passage 42d is connected to a rearward-travel pump pressure receiver 50b of the second travel pump 50R.

[0112] The fifth travel fluid passage 42e is connected to the operating valves 44a to 44d and to the travel fluid passages 42a to 42d. Specifically, the fifth travel fluid passage 42e includes a bridge fluid passage 42e1 and a plurality of connector fluid passages 45e2. In the bridge fluid passage 42e1, a plurality of shuttle valves 43 and first ends of the connector fluid passages 45e2 are connected alternately. The second ends of the connector fluid passages 45e2 are connected to the respective operating valves 44. The shuttle valves 43 are connected to the respective travel fluid passages 42.

[0113] When the travel operating lever 57a is pivoted in the forward direction F, the first operating valve 44a is operated to allow pilot fluid to be supplied from the first operating valve 44a to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the first operating valve 44a is applied to the forward-travel pump pressure receiver 50a of the first travel pump 50L via the fifth travel fluid passage 42e and the first travel fluid passage 42a. The pilot pressure from the first operating valve 44a is applied to the forward-travel pump pressure receiver 50a of the second travel pump 50R via the fifth travel fluid passage 42e and the third travel fluid passage 42c.

[0114] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the first port 51a to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the third port 51c to the second travel motor 51R. Then, the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R rotate in the normal direction (rotate to achieve forward travel), the first traveling device 5 and the second traveling device 5 are driven to achieve forward travel, and the working machine 1 travels straight forward.

[0115] When the travel operating lever 57a is pivoted in the rearward direction B, the second operating valve 44b is operated to allow pilot fluid to be supplied from the second operating valve 44b to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the second operating valve 44b is applied to the rearward-travel pump pressure receiver 50b of the first travel pump 50L via the fifth travel fluid passage 42e and the second travel fluid passage 42b. The pilot pressure from the second operating valve 44b is applied to the rearward-travel pump pressure receiver 50b of the second travel pump 50R via the fifth travel fluid passage 42e and the fourth travel fluid passage 42d.

[0116] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the second port 51b to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the fourth port 51d to the second travel motor 51R. Then, the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R rotate in the reverse direction (rotate to achieve rearward travel), the first traveling device 5 and the second traveling device 5 are driven to achieve rearward travel, and the working machine 1 travels straight rearward.

[0117] When the travel operating lever 57a is pivoted in the leftward direction L, the third operating valve 44c is operated to allow pilot fluid to be supplied from the third operating valve 44c to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the third operating valve 44c is applied to the forward-travel pump pressure receiver 50a of the second travel pump 50R via the fifth travel fluid passage 42e and the third travel fluid passage 42c. The pilot pressure from the third operating valve 44c is applied to the rearward-travel pump pressure receiver 50b of the first travel pump 50L via the fifth travel fluid passage 42e and the second travel fluid passage 42b.

[0118] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the second port 51b to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the third port 51c to the second travel motor 51R. Then, the output shaft 51Lj of the first travel motor 51L rotates in the reverse direction, the first traveling device 5 is driven to achieve rearward travel, the output shaft 51Rj of the second travel motor 51R rotates in the normal direction, the second traveling device 5 is driven to achieve forward travel, and the working machine 1 turns left.

[0119] When the travel operating lever 57a is pivoted in the rightward direction R, the fourth operating valve 44d is operated to allow pilot fluid to be supplied from the fourth operating valve 44d to the fifth travel fluid passage 42e. The pilot pressure of pilot fluid supplied from the fourth operating valve 44d is applied to the forward-travel pump pressure receiver 50a of the first travel pump 50L via the fifth travel fluid passage 42e and the first travel fluid passage 42a. The pilot pressure from the fourth operating valve 44d is applied to the rearward-travel pump pressure receiver 50b of the second travel pump 50R via the fifth travel fluid passage 42e and the fourth travel fluid passage 42d.

[0120] With this, the angle of the swash plates of the first travel pump 50L and the second travel pump 50R is changed, hydraulic fluid delivered by the first travel pump 50L flows through the circuit fluid passage 53a and is supplied through the first port 51a to the first travel motor 51L, and hydraulic fluid delivered by the second travel pump 50R flows through the circuit fluid passage 53b and is supplied through the fourth port 51d to the second travel motor 51R. Then, the output shaft 51Lj of the first travel motor 51L rotates in the normal direction, the first traveling device 5 is driven to achieve forward travel, the output shaft 51Rj of the second travel motor 51R rotates in the reverse direction, the second traveling device 5 is driven to achieve rearward travel, and the working machine 1 turns right.

[0121] When the travel operating lever 57a is pivoted diagonally, the difference between the pilot pressures applied to the forward-travel pump pressure receivers 50a and the rearward-travel pump pressure receivers 50b determines the directions and speeds of rotation of the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R, and the working machine 1 turns right or left while traveling forward or rearward.

[0122] Specifically, when the travel operating lever 57a is pivoted diagonally leftward and forward, the working machine 1 turns left while traveling forward at a speed corresponding to the operation amount of the travel operating lever 57a. When the travel operating lever 57a is pivoted diagonally rightward and forward, the working machine 1 turns right while traveling forward at a speed corresponding to the operation amount of the travel operating lever 57a. When the travel operating lever 57a is pivoted diagonally leftward and rearward, the working machine 1 turns left while traveling rearward at a speed corresponding to the operation amount of the travel operating lever 57a. When the travel operating lever 57a is pivoted diagonally rightward and rearward, the working machine 1 turns right while traveling rearward at a speed corresponding to the operation amount of the travel operating lever 57a.

[0123] The working machine 1 includes speed-change switching valves 58L and 58R, a speed-change solenoid valve 59, and a speed-change switch 75. The speed-change switching valves 58L and 58R are two-position switching valves. The speed-change switching valve 58L is connected to the swash plate cylinder 52L by a fluid passage, and the speed-change switching valve 58R is connected to the swash plate cylinder 52R by a fluid passage. The speed-change switching valves 58L and 58R are connected to the speed-change solenoid valve 59 via a fluid passage 41. The speed-change solenoid valve 59 is a two-position solenoid switching valve including two positions and a solenoid to be energized in response to a control signal inputted thereto to switch between the positions. The speed-change solenoid valve 59 is connected to the fluid discharge passage 40, and switches the positions of the switching valves 58L and 58R. The speed-change switch 75 is an operating switch to be operated by the driver to input an instruction to switch the speed stage of the rotation speed of the output shafts 51Lj and 51Rj of the travel motor 51 to a first speed stage (low speed stage) or a second speed stage (high speed) higher than the first speed stage.

[0124] Upon receipt of an instruction to switch the speed stage to the first speed stage from the speed-change switch 75, the controller 20 inputs a control signal into the speed-change solenoid valve 59 to switch the speed-change solenoid valve 59 to the first position to block pilot fluid. With this, the pilot fluid from the fluid discharge passage 40 does not act on the pressure receivers of the speed-change switching valves 58L and 58R via the speed-change solenoid valve 59, the speed-change switching valves 58L and 58R are in the first position to block hydraulic fluid, and hydraulic fluid is not supplied from the speed-change switching valves 58L and 58R to the swash plate cylinders 52L and 52R. Thus, the swash plate cylinders 52L and 52R are caused to retract by the elastic force of a spring, and the rotation speed of the output shafts 51Lj and 51Rj of the travel motors 51 is switched to the first speed stage.

[0125] Upon receipt of an instruction to switch the speed stage to the second speed stage from the speed-change switch 75, the controller 20 inputs a control signal into the speed-change solenoid valve 59 to switch the speed-change solenoid valve 59 to the second position to allow pilot fluid to pass therethrough. With this, pilot fluid from the fluid discharge passage 40 acts on the pressure receivers of the speed-change switching valves 58L and 58R via the speed-change solenoid valve 59, the speed-change switching valves 58L and 58R switch to the second position to allow hydraulic fluid to pass therethrough, and hydraulic fluid is supplied from the speed-change switching valves 58L and 58R to the swash plate cylinders 52L and 52R. Thus, the swash plate cylinders 52L and 52R are caused to extend by the hydraulic pressure, and the rotation speed of the output shafts 51Lj and 51Rj of the travel motors 51 is switched to the second speed stage.

[0126] Regardless of whether the speed-change switch 75 is operated or not, the controller 20 may switch the positions of the speed-change solenoid valve 59 to automatically change the second speed stage to the first speed stage (automatic speed reduction) or automatically change the first speed stage to the second speed stage speed (automatic speed increase). In the case where work is performed using a specific attachment 11, the controller 20 switches the speed stage to the first speed stage to perform a low-speed mode (creep mode) in which the travel speed of the working machine 1 is kept at a low speed.

[0127] FIG. 3 is a block diagram showing an electrical configuration of the working machine 1. The working machine 1 includes elements shown in FIG. 3. The controller 20 includes a processing circuit including one or more processors. The working machine 1 includes the controller 20 which is configured or programmed to perform various controls relating to the working machine 1. The controller 20 is connected to the other elements shown in FIG. 3 in a communicable manner via in-vehicle network(s) such as CAN, ISOBUS, LIN and / or FlexRay.

[0128] The controller 20 includes at least one of one or more internal memories, analog circuits, digital circuits, and the like. The analog circuits and the digital circuits include one or more processors. The processor(s) included in the controller 20 include, for example, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC) and / or the like.

[0129] The internal memory(memories) of the controller 20 is / are each a volatile or nonvolatile memory which stores software program(s) to be executed by one or more processors and various data. The controller 20 uses a predetermined storage area of the internal memory as a buffer to temporarily store information and data.

[0130] A storing device (memory and / or storage) 21 includes a nonvolatile memory and / or the like. The storing device 21 also stores software program(s) to be executed by one or more processors of the controller 20 and various data. The storing device 21 also stores control data corresponding to various attachments 11.

[0131] The one or more processors of the controller 20 read(s) software program(s) and control data from the internal memory and / or the storing device 21, and perform various processes based on the software program(s) and the control data. The one or more processors of the controller 20 may perform various processes based on a predetermined logic circuit.

[0132] Note that a plurality of physically separated processors of the controller 20 may operate together to perform various processes, and the configuration of the controller 20 is not limited to the above described configuration. In such a case, the plurality of processors are respectively provided in one or more computers which are physically separated from the working machine 1, and are connected in a communicable manner via a network such as a in-vehicle network, LAN, WAN, and / or the Internet.

[0133] The following configuration may be used: the above described software program(s) is / are stored in a storage medium (nonvolatile memory such as HDD, SSD, CD-ROM, DVD-ROM) connected in a communicable manner with the controller 20 and / or in external device(s) such as a server and / or the like connected via the above described network(s), and is / are installed from such storage medium(media) and / or the external device(s) into the internal memory or the storing device 21.

[0134] A user interface 22 is, for example, a terminal device (computer) in the form of a touchscreen or a tablet including a display. The user interface 22 is provided in the vicinity of the seat 8 inside the cabin 3 (FIG. 12). The controller 20 causes the user interface 22 to output (display) various information relating to the working machine 1 stored in the internal memory and / or the storing device 21 to the driver or the like (or to other user(s)).

[0135] The driver or the like of the working machine 1 inputs various information via the user interface 22. For example, information relating to the attachment 11 attached to the working device 4 can be inputted via the user interface 22. The controller 20 causes the internal memory and / or the storing device 21 to store the information inputted via the user interface 22. The user interface 22 functions as an input interface and an output interface. The user interface 22 may include input interface(s) such as at least one manual operator, e.g., a button, a switch, a dial, and / or a slider, and / or a microphone, and output device(s) such as a speaker.

[0136] A communicator 24 shown in FIG. 3 includes a communication circuit to wirelessly communicate with external device(s) such as a server, a terminal device and / or a portable device via the Internet, a wireless LAN and / or the like. The portable device is, for example, a smartphone or a tablet. The communicator 24 may include a receiver compliant with a satellite positioning system to receive radio waves from satellites. The communicator 24 also functions as an input interface and an output interface.

[0137] A beacon scanner 23 is a receiver to receive wireless signals compliant with a near field communication standard. Specifically, the beacon scanner 23 receives wireless signals (beacon signals) compliant with Bluetooth (registered trademark) Low Energy which is a near field communication standard. As shown in FIG. 12, the beacon scanner 23 is provided at a front portion of the machine body 2. In the case where a beacon transmitter 19 is provided on the attachment 11 attached to the hitch 16, the beacon scanner 23 receives wireless signals transmitted from the beacon transmitter 19. The beacon scanner 23 is an input interface.

[0138] In the case where the attachment 11 attached to the hitch 16 includes an electric circuit including a processor such as CPU, an electric harness connected to the electric circuit is connected to an AUX connector 28. The AUX connector 28 may communicate in a wired manner with the attachment 11, and functions as an input interface and an output interface.

[0139] An attaching switch 29a, a detaching switch 29b, an accelerator 7, the speed-change switch 75, the work manual operator 67, and an AUX manual operator 73 are provided in the vicinity of the seat 8 inside the cabin 3, and are operated by the driver of the working machine 1.

[0140] The attaching switch 29a is operated to attach the attachment 11 to the hitch 16. The detaching switch 29b is operated to allow the attachment 11 to be detached from the hitch 16. As another example, a single operating switch may be used as an attaching switch and a detaching switch.

[0141] A latch control valve 35 is a three-position solenoid switching valve including three positions and a solenoid to be energized in response to a control signal inputted thereto to switch between the positions, and controls the latch cylinder 17. As shown in FIG. 4, the latch control valve 35 is connected to the latch cylinder 17 by fluid passages and is also connected to the main fluid passage 45. The latch control valve 35 is switchable between (i) a neutral position 35c to block hydraulic fluid from the fluid passage 45, (ii) a first position 35a to allow hydraulic fluid to be supplied to the cap-side chamber of the latch cylinder 17 to cause the latch cylinder 17 to extend, and (iii) a second position 35b to allow hydraulic fluid to be supplied to the rod-side chamber of the latch cylinder 17 to cause the latch cylinder 17 to retract.

[0142] For example, the driver of the working machine 1 operates the work manual operator 67 (FIG. 1) to lower the arms 10 and the hitch 16, and operates the travel manual operator 57 (FIG. 2) to cause the machine body 2 to travel forward very slowly, thus causing the front surface of the bracket 30 of the hitch 16 to contact the base plate 9 (FIG. 13) of the attachment 11 placed on the ground J. Then, when the driver operates the attaching switch 29a, the controller 20 inputs a control signal into the latch control valve 35 to switch the latch control valve 35 from the neutral position 35c to the first position 35a. With this, the latch cylinder 17 extends, the latching mechanisms 31 switch to the latching state, and the attachment 11 is attached (fixed) to the hitch 16.

[0143] The driver, while the working machine 1 is in the stopped state, operates the work manual operator 67 to lower the arms 10 and the hitch 16 to cause the attachment 11 attached to the hitch 16 to contact the ground. Then, when the driver operates the detaching switch 29b, the controller 20 inputs a control signal into the latch control valve 35 to switch the latch control valve 35 from the neutral position 35c to the second position 35b. With this, the latch cylinder 17 retracts, the latching mechanisms 31 switch to the unlatching state, and the attachment 11 is allowed to be detached from the hitch 16. In this state, when the driver operates the travel manual operator 57 to cause the machine body 2 to travel rearward, the attachment 11 is detached from the hitch 16.

[0144] A speed detector 36 shown in FIG. 3 detects the travel speed of the working machine 1 (machine body 2). Specifically, the speed detector 36 includes, for example, rotation speed sensor(s) to detect the rotation speed of the travel motors 51L and 51R (FIG. 2) and a calculator, and the calculator calculates the travel speed based on a detection signal from the rotation speed sensor(s). Note that the calculator may not be provided in the speed detector 36, and the controller 20 may calculate the travel speed based on the detection signal from the rotation speed sensor. The controller 20 calculates the travel distance by multiplying the travel speed of the machine body 2 by the travel time.

[0145] As another example, the travel manual operator 57 may include a sensor to detect the direction and angle of operation (pivoting) of the travel operating lever 57a, and the speed detector 36 or the controller 20 may calculate the travel speed based on a detection signal (electric signal) outputted from the sensor. More specifically, for example, the speed detector 36 or the controller 20 determines the direction and angle of operation of the travel operating lever 57a based on a detection signal from the sensor of the travel manual operator 57, calculates, as the operation amount of the travel operating lever 57a, the ratio of the angle of operation of the travel operating lever 57a to the maximum angle of pivoting of the travel operating lever 57a, and calculates the travel speed of the working machine 1 based on the operation amount.

[0146] Alternatively, the speed detector 36 or the controller 20 may calculate the position of the machine body 2 at regular intervals based on signals received by the receiver of the communicator 24 from satellites of a satellite positioning system, and calculate the travel speed of the working machine 1 based on time-series position data of the machine body 2. The configuration to detect the travel speed of the working machine 1 is not limited to the above, and a speed detector to detect the travel speed by some other known method may be used.

[0147] An arm detector 37 and a hitch detector 38 detect the position of the working device 4 that includes the position in the up-down direction, and may each include a sensor(s) such as an inertial measurement unit (IMU) and / or a potentiometer, for example. The arm detector 37 (first detector) detects the angle of rotation (swinging) of the arms 10 as the position (swinging position) of the arms 10 at least in the swinging direction. The arm detector 37, if including an inertial measurement unit, detects the three-dimensional position of the arms 10 and the inertial motion (position in three orthogonal axes, translational motion, and rotational motion) of the arms 10 to determine the acceleration and angular velocity of the arms 10. The controller 20, based on the detection results from the arm detector 37, determines the posture of the arms 10 that includes the position and orientation of the arms 10, the positions of the distal portion of the arms 10 and the hitch 16 in the up-down direction and in the front-rear direction, and the actuated position (the degree of extension / retraction) of the lift cylinders 14.

[0148] The hitch detector 38 (second detector) detects the tilt angle (angle of rotation (swinging)) of the hitch 16 as the position (swinging position) of the hitch 16 at least in the swinging direction. The hitch detector 38, if including an inertial measurement unit, detects the three-dimensional position of the hitch 16 and the inertial motion (position in three orthogonal axes, translational motion, and rotational motion) of the hitch 16 to determine the acceleration and angular velocity of the hitch 16. The controller 20, based on the detection results from the hitch detector 38, determines the posture of the hitch 16 that includes the position and orientation of the hitch 16, the position of the hitch 16 in the up-down direction and the position and orientation in the front-rear direction, and the actuated position (the degree of extension / retraction) of the tilt cylinders 15.

[0149] Furthermore, the controller 20 determines the behavior of the attachment 11 attached to the hitch 16, the position of the attachment 11 in the up-down direction, and the position and orientation of the attachment 11 in the front-rear direction based on the detection results(s) from the arm detector 37 and / or the hitch detector 38. Specifically, the controller 20 determines the direction of movement of a work surface 11w (FIG. 12) of the attachment 11 attached to the hitch 16 (any of four directions including up, down, forward, and rearward directions) and the position of the work surface 11w based at least on the detection result from the arm detector 37, and determines the orientation of the work surface 11w based on the detection result from the hitch detector 38. The work surface 11w is an imaginary surface defined at the contact portion of the attachment 11 that makes contact with the target object during work, and is a reference surface for the posture of the attachment 11.

[0150] As described above, the controller 20 determines the postures (position and orientation) of the arms 10 and the hitch 16 of the working device 4 and the posture of the attachment 11 attached to the working device 4 based on the detection results from the arm detector 37 and the hitch detector 38. Furthermore, the controller 20, based on the detection results from the arm detector 37 and the hitch detector 38, controls the working device 4 and actuates the working device 4 to change the posture of the attachment 11.

[0151] In addition to the foregoing pressure detectors 70a and 70b, the working machine 1 includes pressure detectors 48a, 48b, 48c, 48d, 49a, 49b, 49c, 49d, 68a, 68b, 68c, and 68d as elements to detect the pressure of hydraulic fluid or pilot fluid. Each of the pressure detectors 48a to 48d, 49a to 49d and 68a to 68d includes a pressure sensor.

[0152] The pressure detectors 48a, 48, 48c, and 48d are provided in the respective travel fluid passages 42a, 42b, 42c, and 42d, as illustrated in FIG. 2. The pressure detector 48a detects, as a first travel pressure, the pilot pressure of pilot fluid applied to the first travel fluid passage 42a and the forward-travel pump pressure receiver 50a of the first travel motor 51L. The pressure detector 48b detects, as a second travel pressure, the pilot pressure of pilot fluid applied to the second travel fluid passage 42b and the rearward-travel pump pressure receiver 50b of the first travel motor 51L. The pressure detector 48c detects, as a third travel pressure, the pilot pressure of pilot fluid applied to the third travel fluid passage 42c and the forward-travel pump pressure receiver 50a of the second travel motor 51R. The pressure detector 48d detects, as a fourth travel pressure, the pilot pressure of pilot fluid applied to the fourth travel fluid passage 42d and the rearward-travel pump pressure receiver 50b of the second travel motor 51R.

[0153] The controller 20 may determine the operation direction and operation amount of the travel operating lever 57a and also determine whether or not the travel manual operator 57 is operated to cause the machine body 2 to travel straight or whether or not the travel manual operator 57 is operated to cause the machine body 2 to turn, based on the first to fourth travel pressures detected by the pressure detectors 48a to 48d. The controller 20 may determine the travel direction, travel speed, whether straight travel is performed, whether turn is performed, the direction of turn, and the type of turn regarding the machine body 2 (working machine 1) based on the first to fourth travel pressures.

[0154] The pressure detectors 49a, 49b, 49c and 49d are provided in the circuit fluid passages 53a and 53b. The pressure detector 49a detects the pressure of hydraulic fluid acting on a first port 51a of the first travel motor 51L as a first motor pressure. The pressure detector 49b detects the pressure of hydraulic fluid acting on a second port 51b of the first travel motor 51L as a second motor pressure. The pressure detector 49c detects the pressure of hydraulic fluid acting on a third port 51c of the second travel motor 51R as a third motor pressure. The pressure detector 49d detects the pressure of hydraulic fluid acting on a fourth port 51d of the second travel motor 51R as a fourth motor pressure.

[0155] The controller 20 determines the travel direction, the travel speed, whether straight travel is being performed, whether turning is being performed, the turn direction, and the type of turn relating to the working machine 1 based on the first to fourth motor pressures detected by the pressure detectors 49a to 49d. The controller 20 may determine the operation direction and operation amount of the travel operating lever 57a and also determine whether or not the travel manual operator 57 is operated to cause the machine body 2 to travel straight or whether or not the travel manual operator 57 is operated to cause the machine body 2 to turn, based on the first to fourth motor pressures.

[0156] As shown in FIG. 1, the pressure detectors 68a, 68b, 68c and 68d are respectively provided in the fluid passages 64a, 64b, 65a and 65b. The pressure detectors 68a and 68b detect the pressure of hydraulic fluid acting from the lift control valve 60A to the lift cylinders 14 as a lift pressure. The controller 20 refers to the lift pressure and, for example, adjusts the opening of the solenoid valves 76a and 76b. The pressure detectors 68c and 68d detect the pressure of hydraulic fluid acting from the tilt control valve 60B to the tilt cylinders 15 as a tilt pressure. The controller 20 refers to the tilt pressure and, for example, adjusts the opening of the tilt solenoid valves 77a and 77b. The controller 20 may determine whether or not the work manual operator 67 is operated to swing the arms 10 and the hitch 16 of the working device 4 and whether or not the work manual operator 67 is operated to change the posture of the attachment 11 based on the lift pressure and the tilt pressure.

[0157] The accelerator 7 is operable to define and change the rotation speed of the prime mover 6, and includes an acceleration operator and an acceleration sensor. The acceleration operator is, for example, an operation structure (manual operator) such as a lever, a pedal, a dial, or a slider. The acceleration sensor outputs a signal corresponding to the operation position of the acceleration operator. The controller 20 controls the driving of the prime mover 6 and defines and changes the rotation speed of the prime mover 6 based on an acceleration signal outputted from the acceleration sensor.

[0158] The configurations of the speed-change switch 75, the speed-change solenoid valve 59, the lift solenoid valves 76a and 76b, the tilt solenoid valves 77a and 77b, and the AUX solenoid valves 76a and 76b have been described already.

[0159] The AUX manual operator 73 is operable to control the supply of hydraulic fluid to the auxiliary actuator 27 of the attachment 11. The AUX manual operator 73 includes, in addition to the foregoing AUX output switch 73b, an AUX mode switch 73a, an AUX steady switch 73c, and an AUX volume switch 73d.

[0160] The AUX mode switch 73a is turned ON to start an AUX mode in which an attachment 11 including an auxiliary actuator 27 is allowed to be used with the working machine 1, and is turned OFF to end the AUX mode. When the AUX mode switch 73a is turned ON to start the AUX mode and then the AUX output switch 73b is turned ON, the controller 20 opens one of the AUX solenoid valves 77a and 77b to allow hydraulic fluid to be supplied from the AUX control valve 60C to the corresponding AUX port 25.

[0161] In so doing, if the first AUX port 25a and the first hydraulic port of the attachment 11 are connected by the external fluid passage 26a and the second hydraulic port of the attachment 11 and the second AUX port 25b are connected by the external fluid passage 26b, (i) hydraulic fluid from the AUX control valve 60C flows through the first AUX port 25a, the external fluid passage 26a, and the first hydraulic port of the attachment 11 and is supplied to the auxiliary actuator 27 of the attachment 11, and (ii) hydraulic fluid discharged from the auxiliary actuator 27 flows through the second hydraulic port of the attachment 11, the external fluid passage 26b, and the second AUX port 25b and returns to the AUX control valve 60C. In some cases, hydraulic fluid from the AUX control valve 60C flows through the second AUX port 25b, the external fluid passage 26b, and the second hydraulic port of the attachment 11 and is supplied to the auxiliary actuator 27, whereas hydraulic fluid from the auxiliary actuator 27 flows through the first hydraulic port of the attachment 11, the external fluid passage 26a, and the first AUX port 25a and returns to the AUX control valve 60C.

[0162] The controller 20 ends the AUX mode when the AUX mode switch 73a is turned OFF after the AUX output switch 73b is turned OFF, the AUX solenoid valves 77a and 77b are closed, and the supply of hydraulic fluid from the AUX control valve 60C to the corresponding AUX port 25 is stopped.

[0163] The AUX steady switch 73c is turned ON to start a steady output mode in which the current state of supply of hydraulic fluid to the auxiliary actuator 27 (fluid flow rate) is kept constant, and is turned OFF to stop the steady output mode. When the AUX steady switch 73c is turned ON while the AUX mode is being performed to supply hydraulic fluid to the auxiliary actuator 27, the controller 20 starts the steady output mode and to maintain the opening of the AUX control valve 60C to keep constant the fluid flow rate of hydraulic fluid supplied to the auxiliary actuator 27. After that, when the AUX steady switch 73c is turned OFF, the controller 20 ends the steady output mode, does not maintain the opening of the AUX control valve 60C anymore, and does not keep constant the fluid flow rate of hydraulic fluid supplied to the auxiliary actuator 27 anymore.

[0164] The AUX volume switch 73d is operated to change the supply amount of hydraulic fluid to the auxiliary actuator 27. The AUX volume switch 73d outputs an electric signal corresponding to the manual operation of a control knob such as a slider operating switch, a dial, or a push button. When the AUX volume switch 73d is operated and an electric signal corresponding to the operation is inputted into the controller 20 when the steady supply mode is not performed, the controller 20 detects the operation position of the AUX volume switch 73d based on the electric signal, and inputs a control signal with an electric current value corresponding to the operation position into the AUX solenoid valves 78a and 78b. With this, the openings of the AUX solenoid valves 78a and 78b are defined and / or changed, the pilot pressure acting on the AUX control valve 60C changes, the opening of the AUX control valve 60C is defined and / or changed, the supply amount of hydraulic fluid from the AUX control valve 60C to the auxiliary actuator 27 is defined and / or changed, and the AUX pressure is also defined and / or changed.

[0165] After the attachment 11 is attached to the hitch 16, the controller 20 identifies the attachment 11. For example, in the case where the attached attachment 11 includes a beacon transmitter 19, a wireless signal including information relating to the attachment 11 is transmitted at regular intervals from the beacon transmitter 19, and therefore the wireless signal is received by the beacon scanner 23. The controller 20 identifies the attached attachment 11 based on the information included in the wireless signal received by the beacon scanner 23. For example, the information transmitted by the beacon transmitter 19 includes identification information of the attachment 11 provided with the beacon transmitter 19. The storing device 21 stores pieces of attachment information indicating a plurality of attachments 11 attachable to the working device 4 and pieces of control information defined for the respective plurality of attachments 11, which are associated with each other.

[0166] FIG. 5 illustrates an example, in the form of a table, of pieces of attachment information of the plurality of attachments 11 attachable to the working device 4 and their corresponding pieces of control information. The pieces of information shown in FIG. 5 are stored in a predetermined storage area of the storing device 21.

[0167] The attachment information shown in FIG. 5 includes identification information (ID), name, icon data, model number, and specifications of a corresponding attachment 11. The specifications include information such as the size of the attachment 11, the position and orientation of the work surface 11w (FIG. 12) of the attachment 11 relative to the base plate 9 (FIG. 13), and whether the attachment 11 includes an auxiliary actuator 27. The specifications of the attachment information of the attachment 11 including an auxiliary actuator 27 may include specifications information such as the type and capacity of the auxiliary actuator 27.

[0168] The control information includes the default value of fluid flow rate, work information, and / or the like. The fluid flow rate is the amount of hydraulic fluid supplied per unit time to the auxiliary actuator 27 of the corresponding attachment 11.

[0169] Work information includes information relating to a work condition (predetermined condition) which, when satisfied, allows estimation that work is being performed by the attachment 11 attached to the working device 4. The information relating to the work condition includes a predetermined actuation range of the lift cylinders 14 and a predetermined actuation range of the tilt cylinders 15. Each of the predetermined actuation ranges of the lift cylinders 14 and the tilt cylinders 15 corresponds to the range of the work posture of the corresponding attachment 11 within which work can be performed by the attachment 11. In other words, this is a range of the posture (position and orientation) of the working device 4.

[0170] The controller 20 includes, into the work condition, a condition that the actuated positions of the lift cylinders 14 and the tilt cylinders 15 determined from the detection results from the arm detector 37 and the hitch detector 38 fall within the corresponding predetermined actuation ranges, and determines whether the work condition is satisfied. Additionally or alternatively, the controller 20 may include, in the work condition, a condition that the machine body 2 is traveling straight and / or a condition that the steady output mode has been performed for a predetermined period, and determine whether or not the work condition is satisfied. Such a work condition is an example, and the work condition may include some other condition(s).

[0171] The predetermined actuation range(s) of at least one of the lift cylinders 14 or the tilt cylinders 15 may be included in the work information (control information). The controller 20 may then include, in the work condition, a condition that the actuated position(s) of at least one of the lift cylinders 14 or the tilt cylinders 15 determined from the detection result(s) from at least one of the arm detector 37 or the hitch detector 38 is / are within the corresponding actuation range(s), and determine whether or not the work condition is satisfied.

[0172] In addition to or instead of the predetermined actuation ranges of the lift cylinders 14 and the tilt cylinders 15, a predetermined range of the work posture of the attachment 11 and / or a range of the work posture of the arms 10 and the hitch 16 that corresponds to the predetermined range may be included in the work information. The controller 20 may then include, in the work condition, a condition that at least one of the posture of the attachment 11 or the posture of the arms 10 and the hitch 16 determined from the detection results from the arm detector 37 and the hitch detector 38 is within a predetermined range, and determine whether or not the work condition is satisfied.

[0173] Note that, as the work posture of the attachment 11, for example, the position in the up-down direction (vertical direction) of the work surface 11w (height of the work surface 11w from the bottom of the traveling devices 5 in contact with the ground) and the orientation (tilt angle, or pitch angle) of the work surface 11w may be defined. As the posture of the arms 10, the swing position (angle of rotation) of the arms 10 detectable by the arm detector 37 and / or the position in the up-down direction of the arms 10 detectable by the arm detector 37 may be defined. As the posture of the hitch 16, the swing position (angle of rotation) of the hitch 16 detectable by the hitch detector 38 and / or the position in the up-down direction of the hitch 16 detectable by the hitch detector 38 may be defined.

[0174] For each of the plurality of attachments 11 attachable to the working device 4, related one or more of the default value of the fluid flow rate and the work information are defined, and such defined information is included in the control information. In the example in FIG. 5, the control information for contacting / moved work attachments 11 such as a sweeper and a rake includes the default value of fluid flow rate and work information. The control information for attachments 11 each including an auxiliary actuator 27 at least includes the default value of fluid flow rate. The work information for attachments 11 to condition the surface of the target object, such as a sweeper and a snow blower, defines a predetermined period for the foregoing steady output mode of zero seconds or longer. The control information for attachments 11 other than the contacting / moved work attachments, such as a spreader and a grapple, does not include work information.

[0175] As another example, the control information for attachments 11 other than contacting / moved work attachments 11 may also include work information, posture information, and / or the like. The attachment information may include at least one of the identification information (ID), name, icon, or model number of the attachment 11, and / or other information such as a nickname and / or the serial number of the attachment 11.

[0176] The controller 20 reads attachment information and control information corresponding to the information (identification information) about the attachment 11 received from the beacon transmitter 19 from the storing device 21. The controller 20 identifies the type of the attachment 11 and determines whether the attachment 11 includes an auxiliary actuator 27 based on the read attachment information.

[0177] In the case where an electric circuit including a controller such as a CPU is provided in the attachment 11, the controller 20 may, after an electric harness connected to the electric circuit is connected to the AUX connector 28, receive information relating to the attachment 11 transmitted from the controller via the electric harness and the AUX connector 28. The controller 20 may then read control information corresponding to the attachment 11 indicated by the received information from the storing device 21.

[0178] The information transmitted from an electronic device in or on the attachment 11, such as the beacon transmitter 19 or the controller of the attachment 11, may include the information relating to the attachment 11 and the control information corresponding to the attachment 11. In such a case, the controller 20, upon receipt of the information transmitted from the electronic device of the attachment 11 via the beacon scanner 23 or the AUX connector 28, reads (acquires) the information relating to the attachment 11 and the control information from the received information.

[0179] The control information transmitted from the electronic device of the attachment 11 as described above may include at least one of the default value of the fluid flow rate or the work information. The control information from the electronic device of the attachment 11 may include information indicating at least one of the predetermined actuation ranges of the lift cylinders 14 and the tilt cylinders 15, the predetermined range of the work posture of the arms 10 and the hitch 16, or the predetermined range of the work posture of the attachment 11. In such a case, the controller 20 acquires the information included in the control information transmitted from the electronic device of the attachment 11, via the beacon scanner 23 or the AUX connector 28.

[0180] In addition to or instead of the beacon transmitter 19 and the beacon scanner 23, a transmitter such as a Radio Frequency Identification (RFID) tag may be provided in or on the attachment 11 and a receiver to receive wireless signals issued by the transmitter may be provided in or on the working machine 1.

[0181] Additionally or alternatively, the controller 20 may read from the storing device 21 the data of a plurality of icons C1, C2, C3, C4, C5, C6, and so on indicating respective attachments 11 attachable and detachable to and from the working device 4 and cause the user interface 22 to display the plurality of icons C1, C2, C3, C4, C5, C6, and so on, on a predetermined input screen G2 as illustrated in FIG. 6. In the example of FIG. 6, the controller 20 causes the plurality of icons C1, C2, C3, C4, C5, C6, and so on and the pieces of identification information A1, A2, A3, A4, A5, A6, and so on of the attachments 11 corresponding to the plurality of icons C1, C2, C3, C4, C5, C6, and so on to be displayed on the input screen G2.

[0182] The controller 20 may be configured or programmed to, when the driver or the like performs an operation on the user interface 22 to select an icon that represents the attachment 11 attached to the working device 4 from the plurality of icons C1, C2, C3, C4, C5, C6, and so on displayed on the input screen G2, accept the selected icon (icon C3 in FIG. 6) as information indicating the attachment 11 and read the control information for the attachment 11 corresponding to the selected icon from the storing device 21.

[0183] Additionally or alternatively, the following configuration may be used: the driver or the like manually inputs information such as the name of the attachment 11 attached to the working device 4 into the input screen displayed on the user interface 22. The controller 20 may then receive the manually inputted information from the user interface 22, and read the control information corresponding to the information from the storing device 21.

[0184] Additionally or alternatively, the following configuration may be used: an input screen as indicated in FIG. 6 or an input screen for manual input is displayed on a display of an external device such as a smartphone, and information relating to the attachment 11 corresponding to the icon selected by the user via the input screen or manually inputted information relating to the attachment 11 is transmitted from the external device and received by (inputted into) the communicator 24. The controller 20 may then read, from the storing device 21, the control information corresponding to the information relating to the attachment 11 received by the communicator 24.

[0185] The controller 20 is configured or programmed to, in the case where the control information acquired from the storing device 21 or the like (such as the beacon scanner 23 or the AUX connector28) includes the default value of the fluid flow rate, control the AUX solenoid valves 78a and 78b and the AUX control valve 60C such that hydraulic fluid is supplied to the auxiliary actuator 27 at the default fluid flow rate when the AUX output switch 73b is operated, for example.

[0186] The controller 20 is configured or programmed to, if the acquired control information includes work information, define the work condition based on the work information, determine whether the work condition is satisfied or not, and, if the work condition is satisfied, determine (estimate) that the attachment 11 attached to the working device 4 is performing work. The controller 20 then cause the storing device 21 (or the internal memory) to store actual control information relating to the posture of the attachment 11 at the time when the work condition is satisfied.

[0187] FIG. 7 illustrates an example of actual control information. The controller 20 is configured or programmed to include, in actual control information, device information relating to the posture of the working device 4, such as the actuated positions of the lift cylinders 14 and the tilt cylinders 15 at the time when the work condition is satisfied, and cause the storing device 21 to store the actual control information. As another example, the controller 20 may include, in device information, only information indicating the actuated position of the lift cylinders 14 at the time when the work condition is satisfied. The controller 20 may include, in the device information, information indicating the posture (which may include only position) of at least the arms 10 (of the arms 10 and the hitch 16) at the time when the work condition is satisfied. The controller 20 may include, in the actual control information, information indicating the posture (which may include only position) of the attachment 11 at the time when the work condition is satisfied.

[0188] The controller 20 is configured or programmed to, after the work condition, which was satisfied, becomes not satisfied and then the machine body 2 turns, actuate the working device 4 based on the actual control information stored in the storing device 21 to change the posture of the attachment 11 back to the previous posture which is the posture at the time when the work condition was satisfied.

[0189] FIGS. 8A and 8B show a flowchart showing the operation of the working machine 1. The steps in FIGS. 8A and 8B are repeatedly performed by the controller 20 based on software program(s) stored in the internal memory and / or the storing device 21. The same applies to the steps of a flowchart in FIG. 9 (described later). For convenience, in each flowchart, “attachment” is indicated as “ATT”, and “actuator” is indicated as “ACT”.

[0190] In response to the operation of the attaching switch 29a, the controller 20 actuates the latch cylinder 17 to attach the attachment 11 to the hitch 16 (S1 in FIG. 8A), then acquires input information relating to the attachment 11 inputted thereto from one of the input interfaces 23, 28, 22 and 24, and acquires (reads) attachment information and control information corresponding to the attachment 11 indicated by the input information from the storing device 21 (S2). The controller 20 then identifies the attachment 11 based on the acquired attachment information (S3). In so doing, the controller 20 identifies the type of the attachment 11, whether the attachment 11 includes an auxiliary actuator 27, and / or the like.

[0191] The controller 20, if determining that the attachment 11 includes an auxiliary actuator 27 (YES at S4), after starting the AUX mode in response to turning ON of the AUX mode switch 73a, starts supply of hydraulic fluid to the corresponding AUX port 25 from the AUX control valve 60C in response to turning ON of the AUX output switch 73b (S5). With this, hydraulic fluid is supplied from the AUX port 25 to the auxiliary actuator 27 of the attachment 11 via the corresponding external fluid passage 26 and the like to actuate the auxiliary actuator 27, so that the attachment 11 is driven. In so doing, the controller 20 actuates the AUX solenoid valves 78a and 78b to define the opening of the AUX control valve 60C such that the fluid flow rate of hydraulic fluid toward the AUX port 25 is the default value indicated by the control information.

[0192] If determining that the attachment 11 does not include auxiliary actuators 27 based on the attachment information (NO at S4), the controller 20 does not supply hydraulic fluid from the AUX control valve 60C to the corresponding AUX port 25.

[0193] After the answer is NO at step S4 or after step S5, the controller 20 determines whether or not the attachment 11 attached to the hitch 16 is a specific attachment 11 based on the attachment information. The specific attachment 11 is an attachment 11 to be automatically brought into a work posture. For example, defined specific attachments 11 include attachments 11 to perform work while being kept in the work posture in contact with the target object. The defined specific attachments 11 may include attachments 11 to perform work while being moved by the working machine 1 and kept in the work posture in contact with the target object.

[0194] More specifically, for example, the defined specific attachments 11 include buckets, sweepers, snow blowers, snow blades, angle brooms, mowers, plows, skid cutters, and / or the like, but do not include spreaders, grapples, earth augers, and pallet forks. Information indicating specific attachments 11 is stored in the internal memory of the controller 20 or a predetermined storage area of the storing device 21. The controller 20 reads the stored information to identify specific attachment(s) 11, and determines whether the attachment 11 indicated by the attachment information, i.e., the attachment 11 attached to the hitch 16, is a specific attachment 11.

[0195] The controller 20 may be configured or programmed to, if the control information includes work information, determine that the attached attachment 11 is a specific attachment 11 (YES at S6), and if the control information does not include work information, determine that the attached attachment 11 is not a specific attachment 11 (NO at S6).

[0196] If determining that the attached attachment 11 is not a specific attachment 11 (NO at S6), the controller 20 ends the series of operation in FIGS. 8A and 8B. In such a case, the controller 20 does not change the posture of the attached attachment 11 automatically to the work posture.

[0197] In contrast, if the attached attachment 11 is a specific attachment 11 (YES at S6), the controller 20 performs a work condition determining process (S7). The work condition determining process is performed to select a work condition suitable for the attachment 11 and determine whether the work condition is satisfied or not.

[0198] FIG. 9 is a flowchart showing an example of the work condition determining process. First, the controller 20 reads work information included in the control information corresponding to the attachment 11 and, as information relating to the work condition indicated by the work information, defines a predetermined actuation range of the lift cylinders 14 and a predetermined actuation range of the tilt cylinders 15 (S31 in FIG. 8A). Next, the controller 20, based on the detection results from the arm detector 37 and the hitch detector 38, determines the current actuated position of the lift cylinders 14 and the current actuated position of the tilt cylinders 15, as actual control information relating to the current posture of the working device 4 and of the attachment 11 attached to the working device 4 (S32).

[0199] Next, the controller 20 determines whether or not the current actuated positions of the lift cylinders 14 and the tilt cylinders 15 are within the corresponding predetermined actuation ranges, and, if both the current actuated positions of the lift cylinders 14 and the tilt cylinders 15 are within the predetermined actuation ranges, counts the time for which such a situation has continued. The controller 20 then, if a predetermined period T1 has passed with the current actuated positions of the lift cylinders 14 and the tilt cylinders 15 within the respective corresponding actuation ranges (YES at S33), determines whether or not the machine body 2 is traveling straight.

[0200] As another example, the controller 20 may be configured or programmed to, instead of steps S31 to S33, without referring to the actuation range or the actuated position of the tilt cylinders 15, define a predetermined actuation range of the lift cylinders 14, determine the current actuated position of the lift cylinders 14, and determine whether or not a predetermined period has passed with the current actuated position within the predetermined actuation range.

[0201] The controller 20 may be configured or programmed to, instead of or in addition to steps S31 and S32, define a predetermined actuation range of at least the arms 10 (of the arms 10 and the hitch 16) from the control information corresponding to the attachment 11, and determine the current actuated position (swinging position) of at least the arms 10 (of the arms 10 and the hitch 16) based on the detection results from the arm detector 37 and the hitch detector 38. The controller 20 may then, instead of or in addition to step S33, determine whether or not a predetermined period T1 has passed with the determined current actuated position within the corresponding predetermined actuation range.

[0202] Additionally or alternatively, the controller 20 may be configured or programmed to define a predetermined range of the work posture of the attachment 11 (a range of at least the position (of the position and the orientation)) from the control information corresponding to the attachment 11, and determine the current posture (which includes at least the position (of the position and the orientation)) of the attachment 11 based on the detection results from the arm detector 37 and the hitch detector 38. The controller 20 may then determine whether or not a predetermined period T1 has passed with the current posture of the attachment 11 within the predetermined range of the work posture.

[0203] The controller 20 may be configured or programmed to determine whether or not the machine body 2 is traveling straight based on first to fourth travel pressures detected by the pressure detectors 48a to 48d. Specifically, for example, if the first travel pressure and the third travel pressure applied to the forward-travel pump pressure receivers 50a of the travel pumps 50L, 50R, of the first to fourth travel pressures detected by the pressure detectors 48a to 48d, are each equal to or greater than a first predetermined value and the absolute value of the difference between the first travel pressure and the third travel pressure is less than a second predetermined value, the controller 20 determines that the machine body 2 is traveling straight forward (YES at S34). Furthermore, if the second travel pressure and the fourth travel pressure applied to the rearward-travel pump pressure receivers 50b of the travel pumps 50L, 50R are each equal to or greater than the first predetermined value and the absolute value of the difference between the second travel pressure and the fourth travel pressure is less than the second predetermined value, the controller 20 determines that the machine body 2 is traveling straight rearward (YES at S34). If the first to fourth travel pressures do not satisfy either of the above, the controller 20 determines that the machine body 2 is not traveling straight (NO at S34).

[0204] The controller 20 may be configured or programmed to determine whether or not the machine body 2 is traveling straight based on first to fourth motor pressures detected by the pressure detectors 49a to 49d. Specifically, for example, if the first motor pressure applied to the first port 51a of the first travel motor 51L and the third motor pressure applied to the third port 51c of the second travel motor 51R, of the first to fourth motor pressures detected by the pressure detectors 49a to 49d, are each equal to or greater than a third predetermined value and the absolute value of the difference between the first motor pressure and the third motor pressure is less than a fourth predetermined value, the controller 20 determines that the machine body 2 is traveling straight forward (YES at S34). If the second motor pressure applied to the second port 51b of the first travel motor 51L and the fourth motor pressure applied to the fourth port 51d of the second travel motor 51R are each equal to or greater than the third predetermined value and the absolute value of the difference between the second motor pressure and the fourth motor pressure is less than the fourth predetermined value, the controller 20 determines that the machine body 2 is traveling straight rearward (YES at S34). If the first to fourth motor pressures do not satisfy either of the above, the controller 20 determines that the machine body 2 is not traveling straight (NO at S34).

[0205] Note that, if the attachment 11 which does not perform work during straight rearward travel of the machine body 2 is attached to the working device 4, the controller 20 need only determine whether or not the machine body 2 is traveling straight forward at step S34. As another example, the travel manual operator 57 may include a sensor to detect the operation direction and operation amount of the travel operating lever 57a, and the controller 20 may determine whether or not the machine body 2 is traveling straight based on the detection result from the sensor.

[0206] If determining that the machine body 2 is traveling straight (YES at S34), the controller 20 determines whether or not the attachment 11 identified at step S3 in FIG. 8A is an attachment 11 for which the steady output mode is recommended during work. If the identified attachment 11 is an attachment 11 for which the steady output mode is recommended (YES at S35), the controller 20 determines whether or not a predetermined period T2 has passed with the working machine 1 in the steady output mode.

[0207] The controller 20 then, if the predetermined period T2 has passed with the working machine 1 in the steady output mode (YES at S36), determines that the work condition is satisfied (S37), and ends the work condition determining process. That is, the controller 20 recognizes that the working machine 1 is performing work with the attachment 11 attached to the working device 4. If the identified attachment 11 is not an attachment 11 for which the steady output mode is recommended (NO at S35), the controller 20 does not perform the determination at step S36, determines that the work condition is satisfied (S37), and ends the work condition determining process.

[0208] If the answer is NO at step S33, S34, or S36 (NO at step S33, S34, S36), the controller 20 determines that the work condition is not satisfied (S38), and ends the work condition determining process. That is, the controller 20 recognizes that the working machine 1 is not performing work with the attachment 11 attached to the working device 4.

[0209] After ending the work condition determining process, the controller 20 determines whether or not the work condition has been satisfied continuously for a predetermined period T4 or more (S8 in FIG. 8A). If the work has been performed by the attachment 11 for the predetermined period T4 or more, the controller 20 determines that the work condition has been satisfied continuously for the predetermined period T4 or more (YES at S8 in FIG. 8A). The controller 20 then causes the storing device 21 to store actual control information relating to the posture of the attachment 11 at the time when the work condition is satisfied (S9). Specifically, the controller 20 includes, into the actual control information, device information indicating the actuated positions of the lift cylinders 14 and the tilt cylinders 15 relating to the posture of the working device 4 at the time when the work condition is satisfied (i.e., the actuated positions determined at step S32 in FIG. 9), and causes the storing device 21 to store the actual control information (see FIG. 7). Note that the controller 20 does not cause the storing device 21 to store the actual control information if the work condition has not been satisfied continuously for the predetermined period T4 or more (NO at S8 in FIG. 8A).

[0210] After the answer is NO at step S8 or after step S9 in FIG. 8A, the controller 20 determines whether or not the travel operating lever 57a of the travel manual operator 57 is operated to turn the machine body 2. In so doing, the controller 20 determines whether or not the operation to turn the machine body 2 is performed, based on the first to fourth travel pressures detected by the pressure detectors 48a to 48d.

[0211] Specifically, if, for example, (i) the absolute value of the difference between the first travel pressure and the third travel pressure applied to the forward-travel pump pressure receivers 50a of the travel pumps 50L, 50R, of the first to fourth travel pressures detected by the pressure detectors 48a to 48d or (ii) the absolute value of the difference between the second travel pressure and the fourth travel pressure applied to the rearward-travel pump pressure receivers 50b of the travel pumps 50L, 50R is equal to or greater than the second predetermined value, the controller 20 determines that the travel operating lever 57a is operated to turn the machine body 2 (YES at S10 in FIG. 8B). If the absolute value of the difference between the first travel pressure and the third travel pressure and the absolute value of the difference between the second travel pressure and the fourth travel pressure are each less than the second predetermined value, the controller 20 determines that the travel operating lever 57a is not operated to turn the machine body 2 (NO at S10).

[0212] The controller 20 may be configured or programmed to determine whether or not the travel operating lever 57a is operated to turn the machine body 2 based on the first to fourth motor pressures detected by the pressure detectors 49a to 49d. Specifically, for example, if (i) the absolute value of the difference between the first motor pressure applied to the first port 51a of the first travel motor 51L and the third motor pressure applied to the third port 51c of the second travel motor 51R, of the first to fourth motor pressures detected by the pressure detectors 49a to 49d, or (ii) the absolute value of the difference between the second motor pressure applied to the second port 51b of the first travel motor 51L and the fourth motor pressure applied to the fourth port 51d of the second travel motor 51R is equal to or greater than a fourth predetermined value, the controller 20 determines that the travel operating lever 57a is operated to turn the machine body 2 (YES at S10). If the absolute value of the difference between the first motor pressure and the third motor pressure and the absolute value of the difference between the second motor pressure and the fourth motor pressure are each less than the fourth predetermined value, the controller 20 determines that the travel operating lever 57a is not operated to turn the machine body 2 (NO at S10).

[0213] If the travel operating lever 57a is not operated to turn the machine body 2 (NO at S10), the controller 20 determines whether or not the work operating lever 67a of the work manual operator 67 is operated to actuate the working device 4 (operated to perform work). In so doing, when the driver operates the work operating lever 67a while the machine body 2 (working machine) is traveling straight or in the stopped state, the controller 20 determines that the work operating lever 67a is operated to perform work based on the detection result from the sensor 67b of the work manual operator 67 (YES at S11), and actuates the working device 4 according to the operation direction and operation amount of the work operating lever 67a to change the posture of the working device 4 and the attachment 11 (S12).

[0214] Specifically, the controller 20, according to the operation direction and operation amount of the work operating lever 67a determined based on the detection result from the sensor 67b, actuates the lift solenoid valve 76b, the tilt solenoid valve 77a, the lift control valve 60A, and the tilt control valve 60B to cause the lift cylinders 14 and the tilt cylinders 15 to extend or retract to swing the arms 10 and the hitch 16 to change the posture of the working device 4 and the attachment 11. The controller 20 then performs the work condition determining process again (S7 in FIG. 8A).

[0215] After the controller 20 performs the work condition determining process again, if the answer is YES at step S8, the controller 20 updates, at step S9, the actual control information such that the actual control information includes device information indicating the actuated positions of the lift cylinders 14 and the tilt cylinders 15 relating to the posture of the working device 4 at the time when the work condition is satisfied again (S37 in FIG. 9).

[0216] While the working machine 1 is traveling straight with the attachment 11 performing work, for example, when the working machine 1 reaches an edge of the worksite, the driver operates the travel operating lever 57a to turn the working machine 1 to change directions. If the travel operating lever 57a is operated to turn the machine body 2 (YES at S10), the controller 20 determines the current actuated position of the lift cylinders 14 (S13). If the current actuated position of the lift cylinders 14 is within a predetermined actuation range (YES at S14), the controller 20 actuates the lift cylinders 14 using the lift solenoid valve 76b and the lift control valve 60A to swing the arms 10, thus moving the attachment 11 attached to the working device 4 by a predetermined distance in a direction away from the target object (S15). In the example in FIG. 12, the controller 20 causes the lift cylinders 14 to extend using the lift solenoid valve 76b and the lift control valve 60A to swing the arms 10 upward, thus raising the attachment 11 by a predetermined distance.

[0217] If the identified attachment 11 is a specific attachment 11 for which the work surface 11w is to be held horizontally (held constant), the controller 20 actuates the tilt cylinders 15 using the tilt solenoid valve 77a and the tilt control valve 60B to swing the hitch 16 as the arms 10 swing, thus keeping the orientation of the attachment 11 horizontally relative to the target object. This also keeps a state in which the work surface 11w of the attachment 11 is horizontal to the bottom of the traveling devices 5.

[0218] The controller 20 may be configured or programmed to, at step S15, determine a turn posture which includes the position and orientation of the attachment 11 during the turn of the machine body 2, based on predetermined actuated positions of the lift cylinders 14 and the tilt cylinders 15 indicated by the control information (work information) corresponding to the attachment 11. The controller 20 may then, before the machine body 2 starts turning, actuate the lift cylinders 14 and the tilt cylinders 15 using the lift solenoid valve 76b, the lift control valve 60A, the tilt solenoid valve 77a, and the tilt control valve 60B to swing the arms 10 and the hitch 16 to change the posture of the attachment 11 to the turn posture. When step S15 is performed, the actuated position of the lift cylinders 14 does not fall within the predetermined actuation range anymore, and therefore the controller 20 determines that the work condition is not satisfied anymore (S16).

[0219] While the working machine 1 is traveling straight (while the machine body 2 is traveling straight) and located short of an edge of the worksite, if the driver operates the work operating lever 67a to prepare for turning the working machine 1 (YES at S11), the controller 20 swings the arms 10 according to the operation direction and operation amount of the work operating lever 67a to move the attachment 11 attached to the working device 4 away from the target object to change the posture of the working device 4 and the attachment 11 (S12). With this, the working machine 1 can stably turn (change directions) with the attachment 11 separated from the target object.

[0220] After that, if the controller 20, after performing steps S7 to S9 in FIG. 8A, determines that the travel operating lever 57a is operated to turn the machine body 2 (YES at S10 in FIG. 8B), the controller 20 determines that the current actuated position of the lift cylinders 14 is not within the predetermined actuation range (NO at S14), and determines that the work condition is not satisfied anymore and does not move the attachment 11 using the working device 4 (S16).

[0221] As long as the travel operating lever 57a is being operated to turn the machine body 2, the travel pumps 50L, 50R, the travel motors 51L, 51R, and the traveling devices 5 are actuated to turn the machine body 2 according to the operation direction and operation amount of the travel operating lever 57a. If the driver stops turning the working machine 1 at, for example, an end of the worksite, the driver, in order to resume work using the attachment 11, moves the travel operating lever 57a back to the neutral position and then operates the travel operating lever 57a forward to cause the machine body 2 to travel straight. In such a case, the controller 20, upon detecting that the travel operating lever 57a has not been operated to turn the machine body 2 for a predetermined period T5 (S17), determines that the turn of the machine body 2 has ended (S18). The controller 20 may be configured or programmed to determine that the turn of the machine body 2 has ended when the operation of the travel operating lever 57a to turn the machine body 2 is stopped and then the travel operating lever 57a is operated to cause the machine body 2 to travel straight, e.g., when the travel operating lever 57a is temporarily moved back to the neutral position and then operated forward.

[0222] The controller 20 then determines whether or not the storing device 21 stores actual control information and, if the storing device 21 stores no actual control information (NO at S19), the controller 20 repeats step S11 and subsequent steps. If the storing device 21 stores actual control information (YES at S19), the controller 20 actuates the working device 4 based on the actual control information to move the posture of the attachment 11 back to the previous work posture which is the posture at the time when the work condition was satisfied (S20).

[0223] Specifically, at step S20, the controller 20 reads the actuated positions of the lift cylinders 14 and the tilt cylinders 15 indicated by the device information included in the actual control information, and actuates the lift cylinders 14 and the tilt cylinders 15 using the lift solenoid valve 76b, the tilt solenoid valve 77a, the lift control valve 60A, and the tilt control valve 60B to swing the arms 10 and the hitch 16 such that the actual actuated positions of the lift cylinders 14 and the tilt cylinders 15 match the read actuated positions. That is, the controller 20 moves the actuated positions of the lift cylinders 14 and the tilt cylinders 15 back to the actuated positions at the time of the previous work indicated by the actual control information (device information) to move the posture of the attachment 11 back to the previous work posture.

[0224] Since the posture of the attachment 11 is automatically changed back to the previous work posture, it is possible to perform work using the attachment 11 under the same conditions as before the turn of the machine body 2. After step S20, if the work performed by the attachment 11 has not ended (NO at S21), the controller 20 performs the work condition determining process again (S7 in FIG. 8A) and repeats subsequent steps.

[0225] After that, for example, when the supply of hydraulic fluid to the corresponding AUX port 25 (i.e., to the auxiliary actuator 27 of the attachment 11) is stopped in response to turning OFF of the AUX output switch 73b, the controller 20 determines that the work performed by the attachment 11 has ended (YES at S21 in FIG. 8B). The controller 20 determines that the work performed by the attachment 11 has ended also when the power switch in or on the working machine 1 is turned OFF to stop the prime mover 6 and when the detaching switch 29b is turned ON to allow the attachment 11 to be detached from the hitch 16 (YES at S21). The controller 20 then ends a series of operation in FIGS. 8A and 8B.

[0226] When step S19 in FIG. 8B is performed, the arms 10 and the hitch 16 of the working device 4 are automatically actuated to change the posture of the attachment 11 automatically to the previous work posture. In this regard, for the driver of the working machine 1, etc., to know the start and end of the automatic change in posture, the controller 20 causes, during the automatic change in posture, the user interface 22 to output (display) information indicating that the posture is being automatically changed.

[0227] FIG. 10 illustrates an example of a monitor screen G1 displayed on the user interface 22. The controller 20 causes the user interface 22 to display the monitor screen G1 while the working machine 1 is in operation. The monitor screen G1 displays pieces of information V1 to V6 indicating the state of the working machine 1 detected by sensors in or on the working machine 1, the current date and time, and pieces of information U1 and U2 indicating the attachment 11 identified by the controller 20. The controller 20 is configured or programmed to, when the controller 20 is performing step S19 in FIG. 8B, cause the monitor screen G1 to display a piece of information U3 indicating that the attachment 11 is being changed to the work posture.

[0228] The controller 20 may cause the display of an external device such as a smartphone, instead of the user interface 22, to display (output) the monitor screen G1. In such a case, the controller 20 need only transmit display data of the monitor screen G1 and the foregoing piece of information U3 to the external device via the communicator 24, and cause the display of the external device to display the monitor screen G1 including the piece of information U3.

[0229] In the above-described example embodiments, the controller 20 reads control information corresponding to the attachment 11 attached to the working device 4 based on input information relating to the attachment 11 inputted via the input interface(s) 22, 23, 24, and / or 28, and includes, into the work condition, condition(s) in steps S33, S34, S36 in FIG. 9 based on the control information. Alternatively, for example, step S34 in FIG. 9 may be omitted. Other condition(s) may be included in the work condition.

[0230] The above description of the example embodiments discusses examples in which, with regard to attachments 11 other than contacting / moved attachments such as spreaders, the corresponding control information does not include work information (FIG. 5) and such attachments 11 are not controlled by the controller 20 to automatically change to the previous work posture. However, also with regard to attachments 11 other than contacting / moved work attachments and with regard to other attachments 11 to be changed to the non-work posture by the working device 4 while work is stopped, the corresponding control information may include work information and such attachments 11 may also be controlled by the controller 20 to automatically change to the work posture. Also when work is to be performed for the first time since an attachment 11 is attached to the working device 4, the controller 20 may control the working device 4 to change the posture of the attachment 11 automatically to the work posture included in the corresponding control information.

[0231] In the above described example embodiments, the work manual operator 67 includes a digital joystick. However, for example, as shown in FIG. 11, a pilot-operated hydraulic work manual operator 67 may be used instead.

[0232] The work manual operator 67 in a work-related hydraulic circuit 4A of another example embodiment shown in FIG. 11 includes a work operating lever 67a and a plurality of pilot valves 89a, 89b, 89c and 89d. The plurality of pilot valves 89a to 89d are connected to a fluid discharge passage 40 and are respectively connected to fluid passages 88a, 88b, 88c and 88d. The fluid passages 88a, 88b, 88c and 88d are respectively connected to corresponding work pressure receivers 61a, 61b, 62a, 62b of the lift control valve 60A and the tilt control valve 60B via high-pressure selection valves 91a, 91b, 91c and 91d. Note that, in FIG. 11, for convenience, a portion of the fluid passages 88a, 88b, 88c and 88d is omitted ((a), (b), (c), (d)).

[0233] The high-pressure selection valves 91a, 91b, 91c, 91d are each connected to the lift solenoid valve 76a, 76b or the tilt solenoid valve 77a, 77b via a fluid passage. Each of the high-pressure selection valves 91a, 91b, 91c, 91d allows a higher one of the hydraulic pressure from the connected pilot valve 89a, 89b, 89c, 89d and the hydraulic pressure from the connected solenoid valve 76a, 76b, 77a, 77b to act on the connected work pressure receiver 61a, 61b. The fluid passages 88a to 88d are provided with a solenoid switching valve 87. The solenoid switching valve 87 is a two-position solenoid switching valve, and switchable between a first position to allow passage of pilot fluid and a second position to block pilot fluid. Note that the solenoid switching valve 87 is normally in the first position.

[0234] When the work operating lever 67a is pivoted forward (direction F), the first pilot valve 89a is operated, and, after the pilot pressure of pilot fluid from the fluid discharge passage 40 is changed at the first pilot valve 89a, the pilot fluid passes through the first fluid passage 88a and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 61a of the lift control valve 60A. With this, the lift control valve 60A switches to the first position 61d, the lift cylinders 14 retract, and the arms 10 swing downward.

[0235] When the work operating lever 67a is pivoted rearward (direction B), the second pilot valve 89b is operated, and, after the pilot pressure of pilot fluid from the fluid discharge passage 40 is changed at the second pilot valve 89b, the pilot fluid passes through the second fluid passage 88b and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 61b of the lift control valve 60A. With this, the lift control valve 60A switches to the second position 61e, the lift cylinders 14 extend, and the arms 10 swing upward.

[0236] When the work operating lever 67a is pivoted leftward (direction L), the third pilot valve 89c is operated, and, after the pilot pressure of pilot fluid from the fluid discharge passage 40 is changed at the third pilot valve 89c, the pilot fluid passes through the third fluid passage 88c and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 62a of the tilt control valve 60B. With this, the tilt control valve 60B switches to the first position 62d, the tilt cylinders 15 extend, and the hitch 16 swings downward.

[0237] When the work operating lever 67a is pivoted rightward (direction R), the fourth pilot valve 89d is operated, and, after the pilot pressure of pilot fluid from the pilot fluid discharge passage 40 is changed at the fourth fluid passage 88d, the pilot fluid passes through the fourth fluid passage 88d and the solenoid switching valve 87 and the pilot pressure acts on the work pressure receiver 62b of the tilt control valve 60B. With this, the tilt control valve 60B switches to the second position62e, the tilt cylinders 15 retract, and the hitch 16 swings upward.

[0238] The fluid passages 88a, 88b, 88c and 88d are provided with respective pressure detectors 92a, 92b, 92c and 92d. The pressure detectors 92a, 92b, 92c and 92d detect the pilot pressure outputted from the pilot valves 89a, 89b, 89c and 89d. The controller 20 may determine whether or not the work operating lever 67a is operated, the operation direction and operation amount of the work operating lever 67a based on the pilot pressure detected by the pressure detectors 92a to 92d.

[0239] The controller 20 is configured or programmed such that, when actuating at least one of the lift solenoid valves 76a and 76b or the tilt solenoid valves 77a and 77b to switch the position of at least one of the lift control valve 60A or the tilt control valve 60B to cause at least one of the arms 10 or the hitch 16 to swing, the controller 20 inputs a control signal into the solenoid switching valve 87 to switch the solenoid switching valve 87 to the second position. With this, the pilot pressure from the pilot valves 89a to 89d is blocked at the solenoid switching valve 87 and does not act on any of the work pressure receivers 61a, 61b, 62a and 62b of the lift control valve 60A and the tilt control valve 60B.

[0240] In the foregoing example embodiments, a hydraulic, pilot-operated travel manual operator 57 is used. Note, however, that the travel manual operator57 may also include a digital joystick like the work manual operator 67 illustrated in FIG. 1, and may include some other electric manual operator capable of inputting, into the controller 20, an operation signal (electric signal) corresponding to the operation direction and operation amount of the travel operating lever 57a.

[0241] Working machines 1 of example embodiments described so far include features described in the following items and achieve the following effects.

[0242] (Item 1) A working machine 1 including a machine body 2, a traveling device 5 to cause the machine body 2 to travel and turn, a working device 4 to attach thereto an attachment 11 which is one of a plurality of attachments 11 to perform work by contacting a target object, and change a posture of the attachment 11 attached thereto including a position of the attachment 11 in an up-down direction, a work manual operator 67 to be operated to actuate the working device 4 to change the posture of the attachment 11, and a controller 20 configured or programmed to control the working device 4, wherein the controller 20 is configured or programmed to cause a memory and / or a storage 21 to store actual control information relating to the posture of the attachment 11 at a time when a predetermined condition (work condition) is satisfied, the predetermined condition being a condition which, when satisfied, allows estimation that the work is being performed by the attachment 11 attached to the working device 4, and after the predetermined condition becomes not satisfied and the machine body 2 turns, actuate the working device 4 based on the actual control information to change the posture of the attachment 11 back to a previous work posture which is the posture of the attachment 11 at the time when the predetermined condition is satisfied.

[0243] With the configuration according to item 1, for example, after the driver operates the work manual operator 67 to change the posture of the attachment 11 to an intended work posture, the driver can manually drive the working machine 1 and perform work using the attachment 11. Then, even if, upon the working machine 1 reaching an edge of the worksite, the driver operates the work manual operator 67 to bring the attachment 11 into a non-work posture away from the target object and temporarily stops the work so that the working machine 1 can stably make a turn, it is possible to automatically change the posture of the attachment 11 back to the posture before the turn, i.e., back to the work posture intended by the driver, after the working machine 1 (machine body 2) makes a turn. This makes it possible to reduce the burden on the driver to perform operations, to bring the attachment 11 properly into the work posture, and to resume the work in the same manner as before the turn. This also makes it possible to quickly resume the work using the attachment 11 and improve work performance.

[0244] (Item 2) The working machine 1 according to item 1, further including a detector 37, 38 (arm detector 37, hitch detector 38) to detect a posture of the working device 4 that includes a position of the working device 4 in an up-down direction, wherein the controller 20 is configured or programmed to include, in the actual control information, device information relating to the posture of the working device 4 at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body 2 turns, actuate the working device 4 based on the device information to change the posture of the working device 4 back to the posture of the working device 4 at the time when the predetermined condition is satisfied.

[0245] With the configuration according to item 2, the controller 20 determines the posture of the working device 4 based on the detection result from the detector(s) 37, 38 before and after the working machine 1 turns and, after the turn of the working machine 1, changes the posture of the working device 4 back to the posture before the turn of the working machine 1. This makes it possible to reliably change the posture of the attachment 11 back to the work posture before the turn automatically. Furthermore, since the controller 20 does not need to determine the posture of the attachment 11 based on the posture of the working device 4, it is possible to reduce the processing load on the controller 20.

[0246] (Item 3) The working machine 1 according to item 1 or 2, wherein the working device 4 includes an arm 10 connected to the machine body 2 swingably in the up-down direction, a hitch 16 connected to a distal portion of the arm 10 swingably in the up-down direction and operable to attach and detach the attachment 11 thereto and therefrom, a first actuator (lift cylinder) 14 to swing the arm 10, and a second actuator (tilt cylinders) 15 to swing the hitch 16, wherein the work manual operator 67 is operable to be operated to actuate the first actuator 14 and / or the second actuator 15 to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 that includes the position and an orientation of the attachment 11, and the controller 20 is configured or programmed to actuate the first actuator 14 and / or the second actuator 15 based on the actual control information to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 back to the previous work posture.

[0247] With the configuration according to item 3, the driver is able to operate the work manual operator 67 to swing the arm(s) 10 and the hitch 16 to bring the working device 4 into an intended posture and also bring the attachment 11 attached to the hitch 16 into an intended posture. Furthermore, by the driver operating the work manual operator 67 to cause the working device 4 to bring the attachment 11 into an intended non-work posture, it is possible to temporarily stop the work. Furthermore, after the working machine 1 turns, the driver does not need to operate the work manual operator 67 to bring the attachment 11 into the work posture (which is more difficult to achieve than the non-work posture), and the controller 20 actuates the first actuator(s) 14 and / or the second actuator(s) 15 to swing the arm(s) 10 and / or the hitch 16 to change the posture of the attachment 11 back to the work posture before the turn automatically, making it possible to reduce the burden on the driver to operate the arm(s) 10 and the hitch 16.

[0248] (Item 4) The working machine 1 according to item 3, further including a travel manual operator 57 to be operated to cause the traveling device 5 to cause the machine body 2 to travel and turn, wherein the controller 20 is configured or programmed to, after the predetermined condition is satisfied, when the travel manual operator 57 is operated to cause the machine body 2 to turn, actuate the first actuator 14 and / or the second actuator 15 to swing the arm 10 and / or the hitch 16 to move the attachment 11 attached to the working device 4 in a direction away from the target object, and when the travel manual operator 57 has not been operated to cause the machine body 2 to turn for a predetermined period or more, or when the travel manual operator 57 is operated to cause the machine body 2 to travel straight after the travel manual operator 57 stops being operated to cause the machine body 2 to turn, actuate the first actuator 14 and / or the second actuator 15 based on the actual control information to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 back to the previous work posture.

[0249] With the configuration according to item 4, by the driver temporarily stopping the work using the attachment 11 and operating the travel manual operator 57 to make a turn, without the need to operate the work manual operator 67, the working device 4 is actuated to bring the attachment 11 automatically into the non-work posture away from the target object, making it possible to further reduce the burden on the driver to perform operations. Furthermore, after the working machine 1 turns, by the driver stopping operating the travel manual operator 57 to make a turn, the posture of the attachment 11 is automatically changed back to the work posture before the turn. This makes it possible to further reduce the burden on the driver to perform operations.

[0250] (Item 5) The working machine 1 according to item 3 or 4, wherein the controller 20 is configured or programmed to include, in the actual control information, device information relating to an actuated position of the first actuator 14 and / or an actuated position of the second actuator 15 at the time when the predetermined condition is satisfied, and after the predetermined condition becomes not satisfied and the machine body 2 turns, change the actuated position of the first actuator 14 and / or the actuated position of the second actuator 15 each back to the actuated position indicated by the device information.

[0251] With the configuration according to item 5, the controller 20 determines the actuated position of the first actuator(s) 14 and / or the second actuator(s) 15 before and after the working machine 1 turns and, after the turn of the working machine 1, changes the actuated position of the first actuator(s) 14 and / or the second actuator(s) 15 back to the actuated position before the turn of the working machine 1. This makes it possible to reliably change the posture of the attachment 11 back to the work posture before the turn automatically. Furthermore, since the controller 20 does not need to determine the posture of the working device 4 and / or the attachment 11 based on the actuated position of the first actuator(s) 14 and / or the second actuator(s) 15, it is possible to reduce the processing load on the controller 20.

[0252] (Item 6) The working machine 1 according to any one of items 3 to 5, further including an input interface 22, 23, 24, 28 (user interface 22, beacon scanner 23, communicator 24, AUX connector 28) to receive input of information relating to the attachment 11 attached to the working device 4, wherein the controller 20 is configured or programmed to, in a case that the attachment 11 corresponding to the information inputted via the input interface 22, 23, 24, 28 is a specific attachment 11, keep an orientation of the attachment 11 constant by actuating the second actuator 15 to swing the hitch 16 when actuating the first actuator 14 to swing the arm 10 to raise or lower the attachment 11.

[0253] With the configuration according to item 6, when the driver operates the work manual operator 67 to swing the arm(s) 10 to raise or lower the specific attachment 11, the orientation and posture of the attachment 11 relative to the target object is kept constant without having to operate the work manual operator 67 to swing the hitch 16, making it possible to further reduce the burden on the driver to perform operations. Furthermore, both when the arm(s) 10 is / are manually swung and when the arm(s) 10 is / are automatically swung, it is possible to eliminate or reduce the likelihood that the orientation of the attachment 11 will change and the attachment 11 will accidentally hit the target object or surrounding objects. This eliminates the need for the driver to operate the work manual operator 67 to avoid hitting an object, making it possible to further reduce the burden on the driver to perform operations.

[0254] (Item 7) The working machine 1 according to any one of items 3 to 6, further including a first detector (arm detector) 37 to detect a position of the arm 10, and a second detector (hitch detector) 38 to detect a position of the hitch 16, wherein the controller 20 is configured or programmed to include, in the predetermined condition, a condition that an actuated position of the first actuator 14 and / or an actuated position of the second actuator 15 determined based on a detection result from the first detector 37 and / or a detection result from the second detector 38 each has / have been in a corresponding actuation range for a predetermined period.

[0255] With the configuration according to item 7, it is possible to appropriately and easily estimate that the work is being performed by the attachment 11 attached to the working device 4 on the working machine 1. Furthermore, by causing the memory and / or the storage 21 to store actual control information including the information indicating the actuated positions of the first actuator(s) 14 and the second actuator(s) 15 relating to the work posture of the attachment 11 before the turn of the working machine 1, and changing the actuated positions of the first actuator(s) 14 and the second actuator(s) 15 back to the corresponding actuated positions indicated by the actual control information after the turn of the working machine 1, it is possible to easily and reliably change the posture of the attachment 11 back to the work posture before the turn automatically.

[0256] (Item 8) The working machine 1 according to item 7, further including an input interface 22, 23, 24, 28 to receive input of information relating to the attachment 11 attached to the working device 4, wherein the controller 20 is configured or programmed to define the actuation range corresponding to the first actuator 14 and / or the second actuator 15 based on the information inputted via the input interface 22, 23, 24, 28.

[0257] With the configuration according to item 8, it is possible to define a predetermined condition and the actuation range(s) of the first actuator(s) 14 and / or the second actuator(s) 15 relating to the work posture corresponding to the attachment 11 attached to the working device 4, possible to more appropriately estimate that the work is being performed by the attachment 11, and possible to more appropriately change the posture of the attachment 11 back to the work posture before the turn automatically.

[0258] (Item 9) The working machine 1 according to item 7 or 8, wherein the controller 20 is configured or programmed to include, in the predetermined condition, a condition that the machine body 2 is traveling straight.

[0259] With the configuration according to item 9, in the case where an attachment 1 to be caused to perform work on a target object in contact therewith by being moved by the working machine 1 traveling straight is attached to the working device 4, it is possible to more appropriately estimate that the work is being performed by the attachment 11. This makes it possible to more appropriately change the posture of the attachment 11 back to the work posture before the turn automatically.

[0260] (Item 10) The working machine 1 according to item 9, further including a travel manual operator 57 to be operated to cause the traveling device 5 to cause the machine body 2 to travel and turn, wherein the controller 20 is configured or programmed to, when the predetermined condition becomes not satisfied because, while the machine body 2 is traveling straight, the work manual operator 67 is operated to swing the arm 10 to move the attachment 11 attached to the working device 4 in a direction away from the target object, after the travel manual operator 57 is operated to cause the machine body 2 to turn, upon passage of a predetermined period or more since the travel manual operator 57 stopped being operated to cause the machine body 2 to turn, or upon operation of the travel manual operator 57 to cause the machine body 2 to travel straight after stoppage of operation of the travel manual operator 57 to cause the machine body 2 to turn, actuate the first actuator 14 and / or the second actuator 15 based on the actual control information to swing the arm 10 and / or the hitch 16 to change the posture of the attachment 11 back to the previous work posture.

[0261] With the configuration according to item 10, it is possible, at the time when the driver wishes to resume work after the working machine 1 makes a turn, to appropriately change the posture of the attachment 11 back to the work posture before the turn automatically, making it possible to eliminate or reduce the likelihood that the working device 4 will operate in an unintended manner to change the posture of the attachment 11.

[0262] (Item 11) The working machine 1 according to any one of items 1 to 10, further including a power output circuit (auxiliary hydraulic circuit) 4B to output power to an auxiliary actuator 27 provided in or on the attachment 11 to drive the attachment 11, and an input interface 22, 23, 24, 28 to receive input of information relating to the attachment 11 attached to the working device 4, wherein the controller 20 is configured or programmed to, in a case that the attachment 11 corresponding to the information inputted via the input interface 22, 23, 24, 28 is a specific attachment 11 including the auxiliary actuator 27, include, in the predetermined condition, a condition that the controller 20 has been in a predetermined mode in which the controller 20 keeps constant a state of power output to the auxiliary actuator 27 for a predetermined period.

[0263] With the configuration according to item 11, in the case where a specific attachment 11 including an auxiliary actuator 27 is attached to the working device 4, it is possible to more appropriately estimate that the work is being performed by the attachment 11. This makes it possible to more appropriately change the posture of the attachment 11 back to the work posture before the turn automatically.

[0264] (Item 12) The working machine 1 according to any one of items 1 to 11, further including an input interface 22, 23, 24, 28 to receive input of information relating to the attachment 11 attached to the working device 4, wherein the working device 4 is operable to change an orientation of the attached attachment 11 that is included in the posture of the attached attachment 11, and the controller 20 is configured or programmed to define, based on the information inputted via the input interface 22, 23, 24, 28, a turn posture of the attachment 11 that includes the position and the orientation of the attachment 11 when the machine body 2 turns, and, when the machine body 2 turns, actuate the working device 4 to change the posture of the attachment 11 to the turn posture.

[0265] With the configuration according to item 12, it is possible to change the posture of the attachment 11 attached to the working device 4 to the turn posture corresponding to the attachment 11 and cause the working machine 1 to turn more stably, and possible to further reduce the burden on the driver to perform operations.

[0266] While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.

Examples

Embodiment Construction

[0033]Example embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. The drawings are to be viewed in an orientation in which the reference numerals are viewed correctly.

[0034]Example embodiments of the present invention will now be described with reference to the accompanying drawings as necessary.

[0035]FIG. 12 is a side view of a working machine 1 of the present example embodiment. In the present example embodiment, a compact track loader is illustrated as an example of the working machine 1. However, the working machine according to an example embodiment of the present invention is not limited to a compact track loader, and may be, for example, some other construction machine, agricultural machine, or working machine such as a skid-steer loader, a backhoe, or a tractor. The left direction, right direction, the direction approaching the viewer of F...

Claims

1. A working machine comprising:a machine body;a traveling device to cause the machine body to travel and turn;a working device to:attach thereto an attachment which is one of a plurality of attachments to perform work by contacting a target object; andchange a posture of the attachment attached thereto including a position of the attachment in an up-down direction;a work manual operator to be operated to actuate the working device to change the posture of the attachment; anda controller configured or programmed to control the working device; whereinthe controller is configured or programmed to:cause a memory and / or a storage to store actual control information relating to the posture of the attachment at a time when a predetermined condition is satisfied, the predetermined condition being a condition which, when satisfied, allows estimation that the work is being performed by the attachment attached to the working device; andafter the predetermined condition becomes not satisfied and the machine body turns, actuate the working device based on the actual control information to change the posture of the attachment back to a previous work posture which is the posture of the attachment at the time when the predetermined condition is satisfied.

2. The working machine according to claim 1, further comprising a detector to detect a posture of the working device that includes a position of the working device in an up-down direction; whereinthe controller is configured or programmed to:include, in the actual control information, device information relating to the posture of the working device at the time when the predetermined condition is satisfied; andafter the predetermined condition becomes not satisfied and the machine body turns, actuate the working device based on the device information to change the posture of the working device back to the posture of the working device at the time when the predetermined condition is satisfied.

3. The working machine according to claim 1, whereinthe working device includes:an arm connected to the machine body swingably in the up-down direction;a hitch connected to a distal portion of the arm swingably in the up-down direction and operable to attach and detach the attachment thereto and therefrom;a first actuator to swing the arm; anda second actuator to swing the hitch; whereinthe work manual operator is operable to be operated to actuate the first actuator and / or the second actuator to swing the arm and / or the hitch to change the posture of the attachment that includes the position and an orientation of the attachment; andthe controller is configured or programmed to actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

4. The working machine according to claim 3, further comprising a travel manual operator to be operated to cause the traveling device to cause the machine body to travel and turn; whereinthe controller is configured or programmed to:after the predetermined condition is satisfied, when the travel manual operator is operated to cause the machine body to turn, actuate the first actuator and / or the second actuator to swing the arm and / or the hitch to move the attachment attached to the working device in a direction away from the target object; andwhen the travel manual operator has not been operated to cause the machine body to turn for a predetermined period or more, or when the travel manual operator is operated to cause the machine body to travel straight after the travel manual operator stops being operated to cause the machine body to turn, actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

5. The working machine according to claim 3, wherein the controller is configured or programmed to:include, in the actual control information, device information relating to an actuated position of the first actuator and / or an actuated position of the second actuator at the time when the predetermined condition is satisfied; andafter the predetermined condition becomes not satisfied and the machine body turns, change the actuated position of the first actuator and / or the actuated position of the second actuator each back to the actuated position indicated by the device information.

6. The working machine according to claim 3, further comprising an input interface to receive input of information relating to the attachment attached to the working device; whereinthe controller is configured or programmed to, in a case that the attachment corresponding to the information inputted via the input interface is a specific attachment, keep an orientation of the attachment constant by actuating the second actuator to swing the hitch when actuating the first actuator to swing the arm to raise or lower the attachment.

7. The working machine according to claim 3, further comprising:a first detector to detect a position of the arm; anda second detector to detect a position of the hitch; whereinthe controller is configured or programmed to include, in the predetermined condition, a condition that an actuated position of the first actuator and / or an actuated position of the second actuator determined based on a detection result from the first detector and / or a detection result from the second detector each has / have been in a corresponding actuation range for a predetermined period.

8. The working machine according to claim 7, further comprising an input interface to receive input of information relating to the attachment attached to the working device; whereinthe controller is configured or programmed to define the actuation range corresponding to the first actuator and / or the second actuator based on the information inputted via the input interface.

9. The working machine according to claim 7, wherein the controller is configured or programmed to include, in the predetermined condition, a condition that the machine body is traveling straight.

10. The working machine according to claim 9, further comprising a travel manual operator to be operated to cause the traveling device to cause the machine body to travel and turn; whereinthe controller is configured or programmed to, when the predetermined condition becomes not satisfied because, while the machine body is traveling straight, the work manual operator is operated to swing the arm to move the attachment attached to the working device in a direction away from the target object, after the travel manual operator is operated to cause the machine body to turn, upon passage of a predetermined period or more since the travel manual operator stopped being operated to cause the machine body to turn, or upon operation of the travel manual operator to cause the machine body to travel straight after stoppage of operation of the travel manual operator to cause the machine body to turn, actuate the first actuator and / or the second actuator based on the actual control information to swing the arm and / or the hitch to change the posture of the attachment back to the previous work posture.

11. The working machine according to claim 1, further comprising:a power output circuit to output power to an auxiliary actuator provided in or on the attachment to drive the attachment; andan input interface to receive input of information relating to the attachment attached to the working device; whereinthe controller is configured or programmed to, in a case that the attachment corresponding to the information inputted via the input interface is a specific attachment including the auxiliary actuator, include, in the predetermined condition, a condition that the controller has been in a predetermined mode in which the controller keeps constant a state of power output to the auxiliary actuator for a predetermined period.

12. The working machine according to claim 1, further comprising an input interface to receive input of information relating to the attachment attached to the working device; whereinthe working device is operable to change an orientation of the attached attachment that is included in the posture of the attached attachment; andthe controller is configured or programmed to define, based on the information inputted via the input interface, a turn posture of the attachment that includes the position and the orientation of the attachment when the machine body turns, and, when the machine body turns, actuate the working device to change the posture of the attachment to the turn posture.

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