Work machine

Abstract

To prevent unintended stopping of an engine due to a high load.SOLUTION: A work machine comprises: a main pump operated by power of the engine and discharges hydraulic oil; a work unit performing a work by operation of an actuator which includes a work device and an attachment attached to the work device and is provided in at least one of the work device and the attachment, by hydraulic oil; a solenoid valve changing a flow rate of the hydraulic oil to the actuator in response to an input control signal; a control device inputting the control signal to the solenoid valve; an accelerator device inputting a target rotation speed of the engine; and a rotation speed sensor detecting an actual rotation speed of the engine. When a drop amount, that is an amount of decrease in the actual rotation speed of the engine compared to the target rotation speed, becomes equal to or greater than a first threshold value when the work unit is performing a specified work that places a high load on the engine, the control device changes the control signal in response to the actual rotation speed, to limit the flow rate of the hydraulic oil to the actuator.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to work machines such as skid steer loaders and compact track loaders. [Background technology]

[0002] Working machines such as skid steer loaders and compact track loaders perform various tasks using a working unit including a working device mounted on the machine body and various attachments such as a bucket attached to the working device while traveling on a traveling device that supports the machine body. In such working machines, when a large load is applied to the prime mover, the prime mover may stop unintentionally. When the prime mover is an engine, this phenomenon is called an engine stall.

[0003] In order to prevent unintended stops due to the load on the prime mover of the work machine, for example, in the technology disclosed in FIG. 1 of Patent Document 1, when the engine speed falls below a predetermined value, the pilot pressure that operates the travel pump is reduced by an electromagnetic proportional valve, thereby limiting the output of the travel pump (i.e., the output of the travel system). Also, in the technology disclosed in FIG. 3 of Patent Document 1, the electromagnetic proportional valve that reduces the pilot pressure to the travel pump also reduces the pilot pressure to the control valve for the boom cylinder, thereby also limiting the flow rate of hydraulic oil from the control valve to the boom cylinder (i.e., the output of the work system).

[0004] Also, as disclosed in Patent Document 2, for example, there is a technique in which a plurality of dedicated electromagnetic variable throttle valves are provided to respectively reduce the pilot pressure to a first control valve for the boom cylinder and the pilot pressure to a second control valve for the bucket cylinder, thereby individually restricting the flow rate of hydraulic oil from the first control valve to the boom cylinder and the flow rate of hydraulic oil from the second control valve to the bucket cylinder. As described above, the techniques disclosed in Patent Documents 1 and 2 restrict the flow rate of hydraulic oil to a specific actuator so as not to affect other hydraulic equipment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6629282 [Patent Document 2] JP 2019-65999 A Summary of the Invention [Problem to be solved by the invention]

[0006] Some work performed by the working unit of a work machine places a high load on the prime mover. For example, when an attachment is used that is equipped with a high-output actuator that requires a large flow rate of hydraulic oil to operate, or when a large external force is applied to the work device, a high load is placed on the prime mover. When the working unit performs work that places a high load on the prime mover, a high proportion of the prime mover's power is consumed by the hydraulic pump of the work system, causing the rotation speed of the prime mover to drop rapidly, making the prime mover more likely to stop unintentionally. However, the reality is that such cases where a high load is placed on the prime mover are not anticipated.

[0007] In view of the above problems, an object of the present invention is to provide a work machine capable of preventing unintended stopping of a prime mover due to a high load. [Means for solving the problem]

[0008] The working machine according to the present invention is operated by the power of a prime mover mounted on the machine body and discharges hydraulic oil. The present invention relates to a working unit that includes a main pump for supplying hydraulic fluid to a working device, a working device and an attachment attached to the working device, and an actuator provided on at least one of the working device and the attachment is operated by the hydraulic oil to perform work using the working device and the attachment, a solenoid valve that changes the flow rate of the hydraulic oil to the actuator in response to an input control signal, a control device that inputs the control signal to the solenoid valve, an accelerator device that inputs a target rotation speed of the prime mover, and a rotation speed sensor that detects the actual rotation speed of the prime mover. When a drop amount, which is an amount of decrease in the actual rotation speed of the prime mover relative to the target rotation speed, becomes equal to or greater than a predetermined first threshold value while the working unit is performing a predetermined work that places a high load on the prime mover, the control device changes the control signal in response to the actual rotation speed to limit the flow rate of the hydraulic oil to the actuator. Effect of the Invention

[0009] Based on the above, it is possible to provide a work machine capable of preventing unintended stopping of the prime mover due to a high load. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram showing a hydraulic circuit of a working system of a working machine. [Diagram 2] FIG. 2 is a diagram showing a hydraulic circuit of a traveling system of the work machine. [Diagram 3] FIG. [Figure 4] 4 is a flowchart showing an example of an operation of a work machine during work. [Diagram 5] 5 is a flowchart showing an example of the light-load / medium-load output process of FIG. 4. [Figure 6] FIG. 11 is a diagram showing an example of a control map of an AUX solenoid valve during light-load / medium-load output processing. [Figure 7A] 5 is a flowchart showing an example of the high-load output process of FIG. 4. [Figure 7B] 7B is a continuation of the flowchart of FIG. 7A. [Figure 8] FIG. 4 is a diagram showing an example of a control map of the AUX solenoid valve during high load output processing. [Figure 9A] FIG. 4 is a diagram showing an example of a shift in a control map for the AUX solenoid valve during high load. [Figure 9B] FIG. 4 is a diagram showing an example of shifting between a normal control map and a high load control map of the AUX solenoid valve. [Figure 10] FIG. 4 is a diagram showing an example of a change in a current value of a control signal for an AUX solenoid valve. [Figure 11A] 11A and 11B are diagrams illustrating an example of an accelerator signal, an accelerator pseudo signal, and the rotation speed of the prime mover when the target rotation speed of the prime mover is increased. [Figure 11B] 11 is a diagram showing an example of an accelerator signal, an accelerator pseudo signal, and a rotation speed of the prime mover when a target rotation speed of the prime mover is reduced; FIG. [Figure 12] FIG. 4 is a diagram showing another example of a hydraulic circuit of a working system of a working machine. [Figure 13] 10 is a flowchart showing an example of an output process when a work machine is working. [Figure 14] FIG. 4 is a diagram showing an example of a control map of an operating solenoid valve. [Figure 15] FIG. 4 is a diagram showing another example of a hydraulic circuit of a traveling system of a work machine. [Figure 16] FIG. 4 is a diagram showing an example of a control map of a traveling solenoid valve. [Figure 17] FIG. 4 is a diagram showing another example of a hydraulic circuit of a working machine. [Figure 18] FIG. 4 is a diagram showing another example of a hydraulic circuit of a working machine. [Figure 19] FIG. 11 is a diagram showing an example of correction of a slope of a control map for an AUX solenoid valve during high load. [Figure 20A] FIG. 13 is a diagram showing an example of correction performed by shifting a control map of the AUX solenoid valve under high load in the horizontal axis direction. [Figure 20B] FIG. 13 is a diagram showing an example of correction performed by shifting a control map of the AUX solenoid valve during high load in the vertical axis direction. [Figure 20C] FIG. 13 is a diagram showing an example of correction performed by shifting a control map of the AUX solenoid valve during high load in the horizontal and vertical axis directions. [Figure 21] FIG. 4 is a diagram showing another example of a hydraulic circuit of a working system of a working machine. [Figure 22] FIG. 13 is a diagram illustrating an example of an anti-stall priority setting screen. [Diagram 23] 13 is a diagram showing another example of correction of the slope of the control map during high load of the AUX solenoid valve. FIG. [Figure 24A] FIG. 13 is a diagram showing another example of correction in which the control map for the AUX solenoid valve under high load is shifted in the horizontal axis direction. [Figure 24B] FIG. 13 is a diagram showing another example of correction in which the control map for the AUX solenoid valve under high load is shifted in the vertical axis direction. [Figure 24C] 13 is a diagram showing another example of correction performed by shifting the control map of the AUX solenoid valve during high load in the horizontal and vertical axis directions. FIG. [Diagram 25] FIG. 13 is a diagram showing an example of correction of the slope of a control map for a working solenoid valve during high load. [Figure 26A] FIG. 13 is a diagram showing an example of correction performed by shifting a high-load control map of the working solenoid valve in the horizontal axis direction. [Figure 26B] FIG. 13 is a diagram showing an example of correction performed by shifting a high-load control map of the working solenoid valve in the vertical axis direction. [Figure 26C] FIG. 13 is a diagram showing an example of correction performed by shifting a control map of the working solenoid valve during high load in the horizontal and vertical axis directions. [Figure 27] FIG. 13 is a diagram showing another example of the anti-stall priority setting screen. [Figure 28] FIG. 13 is a diagram showing another example of the anti-stall priority setting screen. [Figure 29] FIG. 13 is a diagram illustrating an example of an anti-stall setting screen. [Diagram 30] FIG. 2 is a side view of a work machine equipped with a bucket (standard attachment). [Diagram 31] FIG. 2 is a side view of the work machine with the mulcher (accessory attachment) attached. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 30 and Fig. 31 show side views of a working machine 1 according to an embodiment of the present invention. In this embodiment, a compact track loader is shown as an example of the working machine 1. The working machine according to the present invention is not limited to a compact track loader, and may be, for example, another loader working machine such as a skid steer loader, or a working machine other than a loader working machine. Looking at Figs. 30 and 31, the left direction, right direction, front direction, and depth direction are the front, rear, left, and right directions of the working machine 1, respectively. The direction perpendicular to the front-rear direction and the up-down direction of the working machine 1 will be referred to as the machine body width direction hereinafter.

[0012] As shown in FIG. 30 and the like, the work machine 1 comprises a machine body 2, a cabin 3, a working unit 4U, and a traveling device 5. The cabin 3 is mounted on the machine body 2. A driver's seat 8 is provided inside the cabin 3. A prime mover 6 is provided at the rear of the machine body 2. The prime mover 6 is the power source of the work machine 1. In this embodiment, the prime mover 6 is a diesel engine, but it may be another internal combustion engine (engine) such as a gasoline engine, or it may be an electric motor such as an electric motor.

[0013] A traveling device 5 is provided on each of the left and right sides of the machine body 2. That is, the traveling devices 5 are provided in a pair on the left and right sides. The pair of left and right traveling devices 5 supports the machine body 2 so that it can travel. In this embodiment, a crawler type traveling device is exemplified as the traveling device 5, but other than this, it may be a wheeled traveling device having front wheels and rear wheels, or a semi-crawler type traveling device. The traveling device 5 provided on the left side of the machine body 2 may be called the first traveling device 5, and the traveling device 5 provided on the right side of the machine body 2 may be called the second traveling device 5.

[0014] The working unit 4U includes a working implement 4 mounted on the machine body 2 and an attachment 11 attached to the working implement 4. The working implement 4 has a boom 10, a first link 12, a second link 13, a lift cylinder 14, and a tilt cylinder 15.

[0015] The booms 10 are provided on the left and right sides of the cabin 3 so as to be able to swing up and down. The front end 10a of the left boom 10 and the front end 10a of the right boom 10 are connected by a specially shaped connecting pipe. The rear end 10b of the left boom 10 and the rear end 10b of the right boom 10 are connected by a circular connecting pipe. The first link 12, the second link 13, the lift cylinder 14, and the tilt cylinder 15 are provided on the left and right sides of the machine body 2 corresponding to the left boom 10 and the right boom 10, respectively. The first link 12 and the second link 13 support the rear end 10b of the boom 10 so that it can swing up and down.

[0016] More specifically, the first link 12 is provided vertically at the rear end 10b of the boom 10. The upper end 12a of the first link 12 is pivoted to the rear end 10b of the boom 10 via a pivot shaft 16 so as to be rotatable about a horizontal axis. The pivot shaft 16 passes through the rear of a bracket 10k attached to the rear of the boom 10. The lower end 12b of the first link 12 is pivoted to the rear of the body 2 via a pivot shaft 17 so as to be rotatable about a horizontal axis. The pivot shaft 17 is provided at the upper rear part of the body 2.

[0017] The second link 13 is provided in front of the first link 12. A front end 13a of the second link 13 is pivoted by a pivot shaft 20 so as to be rotatable about a horizontal axis. The pivot shaft 20 is supported by a bracket 2d fixed to the aircraft body 2. A rear end 13b of the second link 13 is pivoted by a pivot shaft 21 so as to be rotatable about a horizontal axis. The pivot shaft 21 is disposed in front of and above the pivot shaft 17, and is supported by a lower portion of the bracket 10k.

[0018] The upper end 14a of the lift cylinder 14 is pivoted freely around a horizontal axis by a pivot shaft 18. The pivot shaft 18 is provided in the center of the boom 10 and passes through the front part of the bracket 10k. The lower end 14b of the lift cylinder 14 is pivoted freely around a horizontal axis by a pivot shaft 19. The pivot shaft 19 is provided in the rear lower part of the machine body 2.

[0019] As the lift cylinder 14 expands and contracts, the boom 10 swings up and down around the pivot shaft 16. That is, the front end 10a of the boom 10 moves up and down. The second link 13 swings up and down around the pivot shaft 20 in conjunction with the up and down swing of the boom 10. The first link 12 swings back and forth around the pivot shaft 17 in conjunction with the up and down swing of the second link 13. That is, the boom 10 can move in the front-to-rear direction. The front end 10a of the boom 10 is pivoted freely rotatably around a horizontal axis by a pivot shaft 23a provided at the bottom of the hitch 24.

[0020] The tilt cylinders 15 are respectively disposed in front of the left and right booms 10. The upper end portions 15a of the tilt cylinders 15 are pivoted rotatably about the horizontal axis via pivot shafts 22. The pivot shafts 22 are provided on brackets 10j fixed to the curved portion 10c of the boom 10. The lower end portions 15b of the tilt cylinders 15 are pivoted rotatably about the horizontal axis by pivot shafts 23b provided on the upper portion of the hitch 24.

[0021] The attachment 11 is attached to the front surface of the hitch 24. The hitch 24 is a connecting device to which the attachment 11 can be detached. As the tilt cylinder 15 extends and retracts, the hitch 24 swings about the pivot shaft 23a, and the attachment 11 attached to the hitch 24 swings up and down and back and forth. In other words, the attachment 11 is attached to the front end portion 10a of the boom 10 via the hitch 24 so as to be able to swing freely (tilt).

[0022] The attachment 11 is a working tool for performing work. In Fig. 30, a bucket 11a is illustrated as an example of the attachment 11. A boom 10 of the working device 4 is raised and lowered by a lift cylinder 14, and the bucket 11a is swung by a tilt cylinder 15, so that a predetermined work (such as excavation work) can be performed.

[0023] Instead of the bucket 11a, for example, as shown in Fig. 31, another attachment 11 can be attached to the front end 10a of the boom 10 via a hitch 24. Examples of the other attachments 11 include a mulcher, a crusher, a breaker, a grapple, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, and a snow blower. Fig. 31 shows a state in which a mulcher (felled tree crusher) 11b is attached to the front end 10a of the boom 10 via the hitch 24 as another attachment 11.

[0024] When the bucket 11a is the attachment 11 that is standardly equipped on the work machine 1, the attachments 11, 11b other than the bucket 11a may be called additional attachments. Some of the additional attachments 11, 11b are provided with an actuator 27 such as a hydraulic motor and a hydraulic cylinder. For example, the mulcher 11b is provided with a hydraulic motor as the actuator 27. The actuator 27 provided on the additional attachments 11, 11b may be called an additional actuator.

[0025] The auxiliary actuator 27 is operated by hydraulic oil supplied from the work machine 1. An AUX port 25 is provided at the curved portion 10c of the boom 10. The AUX port 25 is a port through which hydraulic oil flows in and out of the auxiliary actuator 27. The AUX port 25 has a first AUX port 25a and a second AUX port 25b. The boom 10 and the machine body 2 are provided with a plurality of oil passages connected to the first AUX port 25a and the second AUX port 25b, respectively.

[0026] For example, as shown in Fig. 31, a worker (or the driver of the work machine 1) connects an external oil passage 26a consisting of a hose or the like to the first AUX port 25a and the inflow port of the attached attachment (mulcher) 11b, and connects the external oil passage 26b to the outflow port of the attached attachment 11b and the second AUX port 25b. This allows hydraulic oil to flow out (be supplied) from the work machine 1 to the attached actuator 27 of the attached attachment 11b, and allows hydraulic oil to flow in (return) from the attached actuator 27 to the work machine 1. Then, a hydraulic circuit is established between the work machine 1 and the attached actuator 27, and the attached actuator 27 is operated by the hydraulic oil from the work machine 1, making it possible for the attached attachment 11b to perform a predetermined task (such as crushing fallen trees).

[0027] As described above, the working unit 4U performs work using the working device 4 and the attachment 11 by operating the actuators 14, 15, 27 provided on at least one of the working device 4 and the attachment 11 with hydraulic oil.

[0028] FIG. 1 is a diagram showing a hydraulic circuit of a working system constructed in a working machine 1. This hydraulic circuit of the working system is a hydraulic circuit for operating a working unit 4U. The working machine 1 is equipped with 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. The pilot pump P1 is operated by the power of a prime mover 6, and discharges hydraulic oil stored in a hydraulic oil tank T to a discharge oil passage 40. The hydraulic oil discharged by the pilot pump P1 is pilot oil for controlling various hydraulic devices provided in the working machine 1. The pressure of the pilot oil is pilot pressure.

[0029] The main pump P2 is operated by the power of the prime mover 6 and discharges hydraulic oil stored in the hydraulic oil tank T to the main oil passage 45. The hydraulic oil discharged by the main pump P2 is used to operate the hydraulic actuators provided in the work unit 4U, i.e., the lift cylinder 14 and tilt cylinder 15 provided in the work device 4, and the accessory actuators 27 provided in the accessory attachments 11, 11b. The lift cylinder 14 and tilt cylinder 15 provided in the work device 4 are sometimes collectively referred to as the work actuators.

[0030] The work machine 1 is equipped with a plurality of control valves 60. The plurality of control valves 60 include a lift control valve 60A, a tilt control valve 60B, and an AUX control valve 60C. The plurality of control valves 60 are valves that can respectively control the operation of the actuators 14, 15, 27 of the work unit 4U. Each of the plurality of control valves 60 is connected to the main oil passage 45. The plurality of control valves 60 are valves for switching the flow rate (output) and supply direction of hydraulic oil supplied from the main oil passage 45 to the corresponding actuators 14, 15, 27 to control the operation of the corresponding actuators 14, 15, 27.

[0031] The lift control valve 60A is connected to the lift cylinder 14, which raises and lowers the boom 10, by multiple oil passages. The lift control valve 60A is a pilot-operated direct-acting spool-type three-position switching valve. The lift control valve 60A has multiple work pressure receiving portions 61a, 61b, and switches to a third position (neutral position), a first position different from the third position, and a second position different from the third position and the first position, depending on the pilot pressure acting on the work pressure receiving portions 61a, 61b. When the lift control valve 60A is in the third position, no hydraulic oil is supplied from the main oil passage 45 to the lift cylinder 14.

[0032] By switching the lift control valve 60A to either the first position or the second position, hydraulic oil is supplied from the main oil passage 45 to the lift cylinder 14, and the supply direction of the hydraulic oil is switched. Furthermore, when the lift control valve 60A is in either the first position or the second position, the opening degree of the lift control valve 60A changes according to the pilot pressure, thereby changing the flow rate of hydraulic oil supplied from the main oil passage 45 to the lift cylinder 14. In this way, the lift control valve 60A controls the flow rate and supply direction of hydraulic oil supplied from the main oil passage 45 to the lift cylinder 14 according to the pilot pressure acting on the work pressure receiving portions 61a, 61b, thereby extending and contracting the lift cylinder 14.

[0033] The tilt control valve 60B is connected to the tilt cylinder 15 that swings the attachment 11 by multiple oil passages. The tilt control valve 60B is a pilot-operated direct-acting spool-type three-position switching valve. The tilt control valve 60B has multiple work pressure receiving portions 62a, 62b, and switches to a third position (neutral position), a first position different from the third position, and a second position different from the third position and the first position, depending on the pilot pressure acting on the work pressure receiving portions 62a, 62b. When the tilt control valve 60B is in the third position, no hydraulic oil is supplied from the main oil passage 45 to the tilt cylinder 15.

[0034] By switching the tilt control valve 60B to either the first position or the second position, hydraulic oil is supplied from the main oil passage 45 to the tilt cylinder 15, and the supply direction of the hydraulic oil is switched. When the tilt control valve 60B is in either the first position or the second position, the opening degree of the tilt control valve 60B changes according to the pilot pressure, and the flow rate of the hydraulic oil supplied from the main oil passage 45 to the tilt cylinder 15 is changed. In this way, the tilt control valve 60B controls the flow rate and supply direction of the hydraulic oil supplied from the main oil passage 45 to the tilt cylinder 15 according to the pilot pressure acting on the work pressure receiving parts 62a, 62b, to extend and retract the tilt cylinder 15. The lift control valve 60A and the tilt control valve 60B are valves that control the operation of the work actuators 14, 15 provided in the work device 4, and therefore may be collectively referred to as work control valves.

[0035] The AUX control valve 60C is connected to the AUX port 25 by a plurality of oil passages 64. More specifically, the first port of the AUX control valve 60C is connected to the first AUX port 25a via an oil passage 64a, and the second port of the AUX control valve 60C is connected to the second AUX port 25b via an oil passage 64b. The AUX control valve 60C is a pilot-operated direct-acting spool-type three-position switching valve. The AUX control valve 60C has a plurality of AUX pressure receiving parts 63a, 63b, and switches to a third position (neutral position) 60d, a first position 60a different from the third position 60d, the third position 60d, and a second position 60b different from the first position 60a, depending on the pilot pressure acting on the AUX pressure receiving parts 63a, 63b.

[0036] When the AUX control valve 60C is in the third position 60d, hydraulic oil is not supplied from the main oil passage 45 to the auxiliary actuator 27 via the oil passage 64 and the AUX port 25. When the AUX control valve 60C is switched to either the first position 60a or the second position 60b, hydraulic oil is supplied from the main oil passage 45 to the auxiliary actuator 27 via the oil passage 64 and the AUX port 25, and the supply direction of the hydraulic oil is switched.

[0037] In detail, when the AUX control valve 60C is switched to the first position 60a, hydraulic oil is supplied from the main oil passage 45 to the auxiliary actuator 27 via the oil passage 64a and the first AUX port 25a, and hydraulic oil returns from the auxiliary actuator 27 to the AUX control valve 60C via the oil passage 64b and the second AUX port 25b, and is discharged from the AUX control valve 60C. When the AUX control valve 60C is switched to the second position 60b, hydraulic oil is supplied from the main oil passage 45 to the auxiliary actuator 27 via the oil passage 64b and the second AUX port 25b, and hydraulic oil returns from the auxiliary actuator 27 to the AUX control valve 60C via the oil passage 64a and the first AUX port 25a, and is discharged from the AUX control valve 60C.

[0038] Furthermore, when the AUX control valve 60C is in either the first position 60a or the second position 60b, the opening degree of the AUX control valve 60C changes in response to the pilot pressure, thereby changing the flow rate of hydraulic oil supplied from the main oil passage 45 to the auxiliary actuator 27 via the AUX port 25. In this manner, the AUX control valve 60C controls the flow rate and supply direction of hydraulic oil supplied from the main oil passage 45 to the auxiliary actuator 27 via the oil passage 64 and the AUX port 25 in response to the pilot pressure acting on the AUX pressure receiving portions 63a, 63b, to operate the auxiliary actuator 27.

[0039] The work machine 1 is provided with a plurality of AUX solenoid valves 65. The plurality of AUX solenoid valves 65 are solenoid valves that operate the AUX control valve 60C. Each of the plurality of AUX solenoid valves 65 is a proportional valve in which a solenoid is excited and an opening degree is changed according to an input control signal (current signal). Each of the plurality of AUX solenoid valves 65 is provided in a branch oil passage 40c branched from the discharge oil passage 40, and changes the opening degree to change the pilot pressure of the pilot oil supplied from the discharge oil passage 40. As the current value of the control signal input to each of the plurality of AUX solenoid valves 65 increases, the opening degree of each of the plurality of AUX solenoid valves 65 increases, and the pilot pressure output from each of the plurality of AUX solenoid valves 65 increases.

[0040] The multiple AUX solenoid valves 65 include a first AUX solenoid valve 65A and a second AUX solenoid valve 65B. The first AUX solenoid valve 65A and the second AUX solenoid valve 65B are respectively connected to the AUX pressure receiving portions 63a, 63b of the AUX control valve 60C by a control oil passage 66. In detail, the control oil passage 66 includes a first control oil passage 66a that connects the first AUX solenoid valve 65A and the AUX pressure receiving portion 63a of the AUX control valve 60C, and a second control oil passage 66b that connects the second AUX solenoid valve 65B and the AUX pressure receiving portion 63b of the AUX control valve 60C.

[0041] When the opening degree of the first AUX solenoid valve 65A becomes larger than 0 (zero), pilot oil from the discharge oil passage 40 acts on the AUX pressure receiving portion 63a of the AUX control valve 60C via the first AUX solenoid valve 65A and the first control oil passage 66a. At this time, pilot pressure according to the opening degree of the first AUX solenoid valve 65A acts on the AUX pressure receiving portion 63a. When the pilot pressure acting on the AUX pressure receiving portion 63a reaches or exceeds a predetermined value, a spool provided in the AUX control valve 60C moves, the AUX control valve 60C switches from the third position 60d to the first position 60a, and hydraulic oil is supplied from the AUX control valve 60C to the auxiliary actuator via the oil passage 64a and the first AUX port 25a. It will be possible to supply to Ta27.

[0042] In addition, the opening degree of the first AUX solenoid valve 65A changes, and the pilot pressure acting on the AUX pressure receiving portion 63a changes, so the opening degree of the first position 60a of the AUX control valve 60C also changes. The change in the opening degree of the first position 60a changes the flow rate and pressure of the hydraulic oil supplied from the AUX control valve 60C to the auxiliary actuator 27 via the oil passage 64a and the first AUX port 25a.

[0043] When the opening degree of the second AUX solenoid valve 65B becomes larger than 0 (zero), pilot oil from the discharge oil passage 40 acts on the AUX pressure receiving portion 63b of the AUX control valve 60C via the second AUX solenoid valve 65B and the second control oil passage 66b. At this time, pilot pressure according to the opening degree of the second AUX solenoid valve 65B acts on the AUX pressure receiving portion 63b. When the pilot pressure acting on the AUX pressure receiving portion 63b becomes equal to or greater than a predetermined value, the spool of the AUX control valve 60C moves, and the AUX control valve 60C switches from the third position 60d to the second position 60b, and hydraulic oil can be supplied from the AUX control valve 60C to the auxiliary actuator 27 via the oil passage 64b and the second AUX port 25b.

[0044] In addition, the opening degree of the second AUX solenoid valve 65B changes, and the pilot pressure acting on the AUX pressure receiving portion 63b changes, so that the opening degree of the second position 60b of the AUX control valve 60C also changes. The change in the opening degree of the second position 60b changes the flow rate and pressure of the hydraulic oil supplied from the AUX control valve 60C to the auxiliary actuator 27 via the oil passage 64b and the second AUX port 25b.

[0045] As described above, the multiple AUX solenoid valves 65 (first AUX solenoid valve 65A, second AUX solenoid valve 65B) change the flow rate of hydraulic oil from the AUX control valve 60C to the auxiliary actuator 27 by changing the pilot pressure acting on the AUX pressure receiving sections 63a, 63b of the AUX control valve 60C, respectively, in response to the input control signal.

[0046] The work implement 1 is equipped with a work operation device 67. The work operation device 67 is a device that operates the lift cylinder 14 and the tilt cylinder 15 of the work implement 4. The work operation device 67 switches the flow rate and supply direction of hydraulic oil supplied to the lift cylinder 14 and the tilt cylinder 15 by changing the pilot pressures acting on the work pressure receiving portions 61a, 61b, 62a, and 62b of the work control valves 60A and 60B, respectively. The work operation device 67 includes a work operation member 68 and a plurality of work operation valves 69.

[0047] The work operation member 68 is an operation lever that can be swung left and right (machine body width direction) or forward and backward. The work operation member 68 is supported by a plurality of work operation valves 69. The work operation member 68 can be operated forward (arrow A1 direction) and backward (arrow A2 direction) from the neutral position, and can also be operated left (arrow A3 direction) and right (arrow A4 direction) from the neutral position. In other words, the work operation member 68 can be swung in at least four directions based on the neutral position.

[0048] The multiple work operation valves 69 are valves that operate in response to operation of a common work operation member 68. Specifically, the multiple work operation valves 69 are connected to the discharge oil passage 40, and change the pilot pressure of the pilot oil supplied from the discharge oil passage 40. The multiple work operation valves 69 are operated by the work operation member 68. The multiple work operation valves 69 are a first pilot valve 69A, a second pilot valve 69B, a third pilot valve 69C, and a fourth pilot valve 69D.

[0049] The first pilot valve 69A is a pilot valve for lowering the lift, and outputs a pilot valve in response to the amount of operation (operation) when the work operation member 68 is swung (forward operation) forward (in the A1 direction). The second pilot valve 69B is a pilot valve for lift up, and when the work operating member 68 is swung backward (in the A2 direction) (rear operation), it changes the pilot pressure output in accordance with the amount of operation. The third pilot valve 69C is a pilot valve for upward tilt, and when the work operating member 68 is swung leftward (left operation), it changes the pilot pressure output in accordance with the amount of operation. The fourth pilot valve 69D is a pilot valve for downward tilt, and when the work operating member 68 is swung rightward (right operation), it changes the pilot pressure output in accordance with the amount of operation.

[0050] The work operation valves 69 are connected to the control valves 60 by the work oil passages 46. The work oil passages 46 have a first work oil passage 46a, a second work oil passage 46b, a third work oil passage 46c, and a fourth work oil passage 46d. The first work oil passage 46a is an oil passage that connects the first pilot valve 69A and the work pressure receiving portion 61a of the lift control valve 60A. The second work oil passage 46b is an oil passage that connects the second pilot valve 69B and the work pressure receiving portion 61b of the lift control valve 60A. The third work oil passage 46c is an oil passage that connects the third pilot valve 69C and the work pressure receiving portion 62a of the tilt control valve 60B. The fourth work oil passage 46d is an oil passage that connects the fourth pilot valve 69D and the work pressure receiving portion 62b of the tilt control valve 60B.

[0051] When the work operating member 68 is swung forward (in the A1 direction), the first pilot valve 69A is operated and pilot oil is supplied from the first pilot valve 69A to the first work oil passage 46a. The pilot pressure of the pilot oil supplied from the first pilot valve 69A acts on the work pressure receiving portion 61a of the lift control valve 60A via the first work oil passage 46a. As a result, the lift control valve 60A changes the flow rate and supply direction of the hydraulic oil supplied to the lift cylinder 14, so that the lift cylinder 14 contracts and the boom 10 descends.

[0052] When the work operating member 68 is swung backward (in the direction of A2), the second pilot valve 69B is operated and pilot oil is supplied from the second pilot valve 69B to the second work oil passage 46b. The pilot pressure of the pilot oil supplied from the second pilot valve 69B acts on the work pressure receiving portion 61b of the lift control valve 60A through the second work oil passage 46b. As a result, the lift control valve 60A changes the flow rate and supply direction of the hydraulic oil supplied to the lift cylinder 14, so that the lift cylinder 14 extends and the boom 10 rises.

[0053] When the work operating member 68 is swung to the left (in the direction of A3), the third pilot valve 69C is operated and pilot oil is supplied from the third pilot valve 69C to the third work oil passage 46c. The pilot pressure of the pilot oil supplied from the third pilot valve 69C acts on the work pressure receiving portion 62a of the tilt control valve 60B via the third work oil passage 46c. As a result, the tilt control valve 60B changes the flow rate and supply direction of the hydraulic oil supplied to the tilt cylinder 15, so that the tilt cylinder 15 contracts and the attachment 11 swings upward. At this time, if the attachment 11 is a bucket 11a, the bucket 11a performs a shoveling operation.

[0054] When the work operating member 68 is swung to the right (in the direction of A4), the fourth pilot valve 69D is operated and pilot oil is supplied from the fourth pilot valve 69D to the fourth work oil passage 46d. The pilot pressure of the pilot oil supplied from the fourth pilot valve 69D acts on the work pressure receiving portion 62b of the tilt control valve 60B via the fourth work oil passage 46d. This changes the flow rate and supply direction of the hydraulic oil supplied from the tilt control valve 60B to the tilt cylinder 15, so that the tilt cylinder 15 extends and the attachment 11 swings downward. At this time, if the attachment 11 is a bucket 11a, the bucket 11a performs a dumping operation.

[0055] The work machine 1 is equipped with a LS (load sensing) system 80. controls the flow rate of hydraulic oil discharged by the main pump P2 so that the differential pressure obtained by subtracting the maximum load pressure among the load pressures of the multiple actuators 14, 15, 27 operated by the hydraulic oil discharged by the main pump P2, from the hydraulic oil discharge pressure by the variable displacement main pump P2, becomes a constant pressure.

[0056] 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 applies hydraulic pressure to the swash plate changing cylinder 81 to operate the swash plate changing cylinder 81. The opening changing cylinder 83 is operated by the pilot pressure of the pilot oil from the pilot pump P1 to change the opening of the flow rate compensation valve 82.

[0057] A PLS oil passage 84 and a PPS oil passage 85 are connected to the flow rate compensation valve 82. The PLS oil passage 84 is an oil passage that transmits the PLS pressure, which is the maximum load pressure (maximum actuator load pressure) among the load pressures of the multiple actuators 14, 15, and 27. The PPS oil passage 85 is an oil passage that transmits the PPS pressure, which is the discharge pressure of the main pump P2. The flow rate compensation valve 82 operates the swash plate changing cylinder 81 to adjust the angle of the swash plate of the main pump P2 so that the differential pressure obtained by subtracting the PLS pressure from the PPS pressure becomes a constant pressure. This controls the amount of hydraulic oil discharged by the main pump P2, and hydraulic power corresponding to the load on the work device 4 and the auxiliary attachments 11 and 11b is output from the main pump P2.

[0058] In this embodiment, the swash plate of the main pump P2 is pressed in a direction to increase the discharge amount of hydraulic oil from the main pump P2 by the self-pressure of the main pump P2. The swash plate changing cylinder 81 is configured to apply a force to the swash plate that counteracts the self-pressure of the main pump P2. The flow rate compensation valve 82 is configured to adjust the hydraulic pressure acting on the swash plate changing cylinder 81 to control the discharge amount of the main pump P2. Therefore, when the hydraulic pressure acting on the swash plate changing cylinder 81 is released (returns to zero), the angle of the swash plate of the main pump P2 becomes the maximum angle, and the flow rate of hydraulic oil discharged from the main pump P2 becomes the maximum flow rate.

[0059] 2 is a diagram showing a hydraulic circuit of a traveling system provided in the work machine 1. This hydraulic circuit of the traveling system is a hydraulic circuit for operating the traveling device 5 to travel the work machine 1. The work machine 1 is equipped with a traveling pump 50 and a traveling motor 51.

[0060] The travel pump 50 is a hydraulic pump that is operated by the power of the prime mover 6. The travel pump 50 is a swash plate type variable displacement axial pump, and has pump pressure receiving parts 50a, 50b on which pilot pressure acts. The pump pressure receiving parts 50a, 50b are composed of a forward pump pressure receiving part 50a and a reverse pump pressure receiving part 50b. The travel pump 50 changes the angle of the swash plate according to the pilot pressure acting on the pump pressure receiving parts 50a, 50b. By changing the angle of the swash plate of the travel pump 50, the flow rate and discharge direction of the hydraulic oil discharged from the travel pump 50 change. The travel pump 50 includes a first travel pump 50L corresponding to the first travel device 5 and a second travel pump 50R corresponding to the second travel device 5.

[0061] The travel motor 51 is a hydraulic motor that is operated by the hydraulic oil discharged from the travel pump 50. The travel motor 51 includes a first travel motor 51L corresponding to the first travel device 5 and the first travel pump 50L, and a second travel motor 51R corresponding to the second travel device 5 and the second travel pump 50R.

[0062] The first travel motor 51L is connected to the first travel pump 50L by a closed loop circulation oil passage 53a. The first travel motor 51L is operated by hydraulic oil supplied from the first travel pump 50L. The first travel motor 51L has an output shaft 51Lj. The rotation speed of the output shaft 51Lj is changed according to the flow rate of hydraulic oil supplied from the first traveling motor 51L. The output of the first traveling motor 51L is transmitted from the output shaft 51Lj to the drive shaft of the first traveling device 5 via a transmission mechanism, thereby driving the first traveling device 5.

[0063] The first traveling motor 51L has a swash plate, and the angle of the swash plate can be changed by the swash plate switching cylinder 52L to change the rotation speed of the output shaft 51Lj between a first speed stage (low speed stage) and a second speed stage (high speed stage) that is faster than the first speed stage. In more detail, the swash plate switching cylinder 52L contracts to set the rotation speed of the output shaft 51Lj of the first traveling motor 51L to the first speed stage. The swash plate switching cylinder 52L expands to set the rotation speed of the output shaft 51Lj of the first traveling motor 51L to the second speed stage.

[0064] The second traveling motor 51R is connected to the second traveling pump 50R by a closed-loop circulation oil passage 53b. The second traveling motor 51R is operated by hydraulic oil supplied from the second traveling pump 50R, and drives the second traveling device 5 via the output shaft 51Rj and the like. The second traveling motor 51R can change the rotation speed of the output shaft 51Rj between a first speed stage and a second speed stage by changing the angle of the swash plate by the swash plate switching cylinder 52R. The configurations of the second traveling motor 51R, the second traveling pump 50R, the second traveling device 5, and the swash plate switching cylinder 52R are similar to the configurations of the first traveling motor 51L, the first traveling pump 50L, the first traveling device 5, and the swash plate switching cylinder 52L, respectively, and therefore detailed description thereof will be omitted.

[0065] The work machine 1 is equipped with a travel operation device 54. The travel operation device 54 is a device that operates the travel pump 50, the travel motor 51, and the travel device 5. The travel operation device 54 changes the angle of the swash plate of the travel pump 50 by changing the pilot pressure acting on the pump pressure receiving parts 50a, 50b of the travel pump 50, and switches the discharge amount and discharge direction of the hydraulic oil from the travel pump 50, the rotation speed and rotation direction of the output shafts 51Lj, 51Rj of the travel motor 51, and the operating speed and operating direction of the travel device 5. The travel operation device 54 includes a travel operation member 55 and a plurality of travel operation valves 56.

[0066] The travel operation member 55 is an operation lever that swings left and right (machine body width direction) or front and rear. The travel operation member 55 is supported by a plurality of travel operation valves 56. The travel operation member 55 can be operated forward (arrow A1 direction) and backward (arrow A2 direction) from the neutral position, and can also be operated left (arrow A3 direction) and right (arrow A4 direction) from the neutral position. In other words, the travel operation member 55 can swing in at least four directions with the neutral position as the reference.

[0067] The multiple travel operation valves 56 are valves that are actuated by operation of a common travel operation member 55. Specifically, the multiple travel operation valves 56 are connected to the discharge oil passage 40, and change the pilot pressure of the pilot oil, which is the hydraulic oil supplied from the discharge oil passage 40. The multiple travel operation valves 56 are operated by the travel operation member 55. The multiple travel operation valves 56 are a first operation valve 56A, a second operation valve 56B, a third operation valve 56C, and a fourth operation valve 56D.

[0068] The first operating valve 56A changes the pilot pressure to be output according to the amount of operation (operation) when the travel operating member 55 is swung forward (A1 direction) (forward operation). The second operating valve 56B changes the pilot pressure to be output according to the amount of operation when the travel operating member 55 is swung backward (A2 direction) (rear operation). The third operating valve 56C changes the pilot pressure to be output according to the amount of operation when the travel operating member 55 is swung left (A3 direction) (left operation). The fourth operating valve 56D changes the pilot pressure to be output according to the amount of operation when the travel operating member 55 is swung right (A4 direction) (right operation).

[0069] The plurality of travel operation valves 56 are connected to the corresponding travel pumps 50 by the travel oil passages 42. The travel oil passage 42 has a first travel oil passage 42a, a second travel oil passage 42b, a third travel oil passage 42c, a fourth travel oil passage 42d, and a fifth travel oil passage 42e. The first travel oil passage 42a is connected to the forward pump pressure receiving portion 50a of the first travel pump 50L. The second travel oil passage 42b is connected to the reverse pump pressure receiving portion 50b of the first travel pump 50L. The third travel oil passage 42c is connected to the forward pump pressure receiving portion 50a of the second travel pump 50R. The fourth travel oil passage 42d is connected to the reverse pump pressure receiving portion 50b of the second travel pump 50R.

[0070] The fifth traveling oil passage 42e is connected to the plurality of traveling operation valves 56 and the plurality of traveling oil passages 42. More specifically, the fifth traveling oil passage 42e includes a bridge oil passage 42e1 and a plurality of connecting oil passages 45e2. The bridge oil passage 42e1 is alternately connected to the plurality of shuttle valves 43 and one end of the plurality of connecting oil passages 45e2. The other ends of the plurality of connecting oil passages 45e2 are respectively connected to the plurality of traveling operation valves 56. The plurality of shuttle valves 43 are respectively connected to the plurality of traveling oil passages 42.

[0071] When the travel operating member 55 is swung forward (in the A1 direction), the first operating valve 56A is operated, and pilot oil is supplied from the first operating valve 56A to the fifth travel oil passage 42e. The pilot pressure of the pilot oil supplied from the first operating valve 56A acts on the forward pump pressure receiving portion 50a of the first travel pump 50L via the fifth travel oil passage 42e and the first travel oil passage 42a. In addition, the pilot pressure from the first operating valve 56A acts on the forward pump pressure receiving portion 50a of the second travel pump 50R via the fifth travel oil passage 42e and the third travel oil passage 42c. As a result, the angles of the swash plates of the first travel pump 50L and the second travel pump 50R are changed, respectively, and the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R rotate in the normal direction (forward rotation), driving the first travel device 5 and the second travel device 5 forward, and causing the work machine 1 to move straight forward.

[0072] Furthermore, when the travel operating member 55 is swung backward (in the A2 direction), the second operating valve 56B is operated, and pilot oil is supplied from the second operating valve 56B to the fifth travel oil passage 42e. The pilot pressure of the pilot oil supplied from the second operating valve 56B acts on the reverse pump pressure receiving portion 50b of the first travel pump 50L via the fifth travel oil passage 42e and the second travel oil passage 42b. Furthermore, the pilot pressure from the second operating valve 56B acts on the reverse pump pressure receiving portion 50b of the second travel pump 50R via the fifth travel oil passage 42e and the fourth travel oil passage 42d. As a result, the angles of the swash plates of the first travel pump 50L and the second travel pump 50R are respectively changed, and the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R rotate in the reverse direction (reverse rotation), driving the first travel device 5 and the second travel device 5 in reverse, and causing the work machine 1 to move straight backwards.

[0073] Furthermore, when the travel operating member 55 is swung to the left (A3 direction), the third operating valve 56C is operated, and pilot oil is supplied from the third operating valve 56C to the fifth travel oil passage 42e. The pilot pressure of the pilot oil supplied from the third operating valve 56C acts on the forward pump pressure receiving portion 50a of the second travel pump 50R via the fifth travel oil passage 42e and the third travel oil passage 42c. Furthermore, the pilot pressure from the third operating valve 56C acts on the reverse pump pressure receiving portion 50b of the first travel pump 50L via the fifth travel oil passage 42e and the second travel oil passage 42b. As a result, the angles of the swash plates of the first travel pump 50L and the second travel pump 50R are each changed, the output shaft 51Lj of the first travel motor 51L rotates in the reverse direction, driving the first travel device 5 in reverse, and the output shaft 51Rj of the second travel motor 51R rotates in the forward direction, driving the second travel device 5 forward, and the work machine 1 turns left.

[0074] Furthermore, when the travel operating member 55 is swung to the right (in the direction of A4), the fourth operating valve 56D is operated, and pilot oil is supplied from the fourth operating valve 56D to the fifth travel oil passage 42e. The pilot pressure of the pilot oil supplied from the fourth control valve 56D acts on the forward pump pressure receiving portion 50a of the first travel pump 50L via the fifth travel oil passage 42e and the first travel oil passage 42a. The pilot pressure from the fourth control valve 56D acts on the reverse pump pressure receiving portion 50b of the second travel pump 50R via the fifth travel oil passage 42e and the fourth travel oil passage 42d. This changes the angles of the swash plates of the first travel pump 50L and the second travel pump 50R, causing the output shaft 51Lj of the first travel motor 51L to rotate forward, driving the first travel device 5 forward, and the output shaft 51Rj of the second travel motor 51R to rotate reverse, driving the second travel device 5 backward, and turning the work machine 1 to the right.

[0075] Furthermore, when the travel operating member 55 is swung diagonally, the direction and speed of rotation of the output shafts 51Lj, 51Rj of the first travel motor 51L and the second travel motor 51R are determined by the differential pressure of the pilot pressure acting on the forward pump pressure receiving portion 50a and the reverse pump pressure receiving portion 50b, and the work machine 1 turns right or left while moving forward or backward.

[0076] In detail, when the travel operating member 55 is swung diagonally forward to the left, the work machine 1 turns left while moving forward at a speed corresponding to the swing angle of the travel operating member 55. When the travel operating member 55 is swung diagonally forward to the right, the work machine 1 turns right while moving forward at a speed corresponding to the swing angle of the travel operating member 55. When the travel operating member 55 is swung diagonally backward to the left, the work machine 1 turns left while moving backward at a speed corresponding to the swing angle of the travel operating member 55. When the travel operating member 55 is swung diagonally backward to the right, the work machine 1 turns right while moving backward at a speed corresponding to the swing angle of the travel operating member 55.

[0077] The work machine 1 is equipped with a travel switching valve 57. The travel switching valve 57 can be switched between a first state in which the rotation speed of the output shafts 51Lj, 51Rj of the travel motor 51 is set to a first speed stage, and a second state in which the rotation speed is set to a second speed stage. The travel switching valve 57 has first switching valves 58L, 58R and a second switching valve 59.

[0078] The first switching valve 58L is a two-position switching valve that can be switched between a first position 58L1 and a second position 58L2. The first switching valve 58L is connected to the swash plate switching cylinder 52L by an oil passage. When the first switching valve 58L is in the first position 58L1, the supply of hydraulic oil to the swash plate switching cylinder 52L is stopped. This causes the swash plate switching cylinder 52L to contract due to the elastic force of the spring. When the first switching valve 58L is in the second position 58L2, the first switching valve 58L supplies hydraulic oil to the swash plate switching cylinder 52L. This causes the swash plate switching cylinder 52L to extend due to hydraulic pressure.

[0079] The second switching valve 59 is a valve that switches the switching positions of the first switching valve 58L and the first switching valve 58R. Specifically, the second switching valve 59 is a two-position switching valve in which a solenoid is excited in response to an input control signal to switch to either a first position 59a or a second position 59b. The second switching valve 59 is connected to the first switching valve 58L and the first switching valve 58R by an oil passage 41.

[0080] When the second switching valve 59 is in the first position 59a, the second switching valve 59 supplies hydraulic oil to the pressure receiving portions of the first switching valve 58L and the first switching valve 58R. As a result, the first switching valve 58L is switched to the first position 58L1, and the first switching valve 58R is switched to the first position 58R1. In other words, when the second switching valve 59 is in the first position 59a, the traveling switching valve 57 is in the first state, the swash plate switching cylinders 52L, 52R are contracted, and the rotation speed of the output shafts 51Lj, 51Rj of the traveling motor 51 (first traveling motor 51L, second traveling motor 51R) is switched to the first speed stage.

[0081] When the second switching valve 59 is in the second position 59b, the second switching valve 59 does not supply hydraulic oil to the pressure receiving portions of the first switching valve 58L and the first switching valve 58R. As a result, the first switching valve 58L is switched to the second position 58L2, and the first switching valve 58R is switched to the second position 58R2. When the second switching valve 59 is in the second position 59b, the travel switching valve 57 is in the second state, the swash plate switching cylinders 52L, 52R extend, and the rotation speed of the output shafts 51Lj, 51Rj of the travel motors 51 (first travel motor 51L, second travel motor 51R) is switched to the second speed stage. In this way, the travel switching valve 57 switches the travel motors 51 (first travel motor 51L, second travel motor 51R) between the first speed stage and the second speed stage.

[0082] 3 is an electrical block diagram of the work machine 1. The work machine 1 is equipped with a control device 100, a storage device 110, and an input / output interface 111. The control device 100 is composed of a CPU, an MPU, a memory, etc., and is a controller of the work machine 1. The memory of the control device 100 is volatile and non-volatile memory. The memory of the control device 100 is called an internal memory. The internal memory stores software programs and data for the control device 100 to control each part of the work machine 1. Furthermore, data for controlling each part of the work machine 1 is stored in the internal memory by the control device 100.

[0083] The storage device 110 is composed of a non-volatile memory and the like. Data for controlling each part of the work machine 1 is also stored in the storage device 110. The input / output interface 111 is a user interface such as a touch panel or a tablet-type terminal device. The control device 100 displays (outputs) various information related to the work machine 1 stored in the internal memory or the storage device 110 to a driver or the like (or another worker) via the input / output interface 111.

[0084] Furthermore, the driver of the work machine 1 or the like inputs various information through the input / output interface 111. For example, information indicating the attachment 11 mounted on the work machine 4 is input through the input / output interface 111. The input / output interface 111 is an input interface. The control device 100 stores the information input through the input / output interface 111 in an internal memory or the storage device 110. The input / output interface 111 is both an input interface and an output interface. The input / output interface 111 may be provided with at least any one of operation members such as a button, a switch, a dial, and a slider.

[0085] The work machine 1 is equipped with an accelerator device 101, a speed operation device 102, and an auxiliary operation device 103. These devices 101 to 103 are connected to a control device 100. Furthermore, these devices 101 to 103 are installed near the driver's seat 8 in the cabin 3, and are operated by the driver of the work machine 1.

[0086] The accelerator device 101 is a device for inputting a target rotation speed of the prime mover 6, and includes an accelerator operating member and an accelerator sensor. The accelerator operating member is an operating member such as a lever, a pedal, a dial, or a slider. The accelerator sensor outputs a signal according to the operating position of the accelerator operating member. The control device 100 determines the target rotation speed of the prime mover 6 based on the accelerator signal output from the accelerator sensor of the accelerator device 101.

[0087] The speed operating device 102 is an input device for inputting an instruction to switch the traveling motors 51 (first traveling motor 51L, second traveling motor 51R) to either the first speed stage or the second speed stage, and includes a speed change operating member and a speed change instruction detection sensor. The speed change operating member is an operating member such as an operating switch, dial, or slider, and can be operated to a position corresponding to the first speed stage and a position corresponding to the second speed stage. The speed change instruction detection sensor outputs a signal according to the operating position of the speed change operating member.

[0088] The control device 100 judges whether or not there is an instruction to switch to either the first speed stage or the second speed stage corresponding to the operation position of the speed change operation member based on an output signal from the speed change instruction detection sensor of the speed change operation device 102. Then, the control device 100 judges whether or not there is an instruction to switch to the first speed stage. If it is determined that the motor 51 (first motor 51L, second motor 51R) has reached the first speed stage, the motor 51 (first motor 51L, second motor 51R) is switched to the first speed stage by the travel switching valve 57 (first switching valves 58L, 58R and second switching valve 59). This reduces the rotation speed of the output shafts 51Lj, 51Rj of the travel motors 51, the operating speed of the travel devices 5 (first travel device 5, second travel device 5), and the vehicle speed of the work machine 1.

[0089] Furthermore, when the control device 100 determines that there has been an instruction to switch to the second speed stage, it switches the traveling motor 51 to the second speed stage by the traveling switching valve 57. This causes the rotation speed of the output shafts 51Lj, 51Rj of the traveling motor 51, the operating speed of the traveling device 5, and the vehicle speed of the work machine 1 to increase.

[0090] The accessory operation device 103 is an input device for inputting an AUX output start instruction to cause hydraulic oil to flow in and out of the accessory actuator 27 provided on the accessory attachment 11, 11b through the AUX port 25, and an AUX output stop instruction to stop the flow of hydraulic oil. The accessory operation device 103 includes an accessory output operation member and an output instruction detection sensor. The accessory output operation member is an operation member such as an operation switch, dial, or slider, and can be operated to a start position corresponding to an AUX output start instruction and a stop position corresponding to an AUX output stop instruction. The detection sensor outputs a signal according to the operation position of the accessory output operation member.

[0091] When the control device 100 determines that there is an AUX output start command (a command to start output from the AUX port 25) based on an output signal from the detection sensor of the auxiliary operating device 103, it switches the AUX control valve 60C to either the first position 60a or the second position 60b using the AUX solenoid valve 65 (first AUX solenoid valve 65A, second AUX solenoid valve 65B), causing hydraulic oil to flow from the AUX control valve 60C through the oil passage 64 and the AUX port 25 to the auxiliary actuator 27. This causes the auxiliary actuator 27 to operate, making it possible to perform work using the auxiliary attachments 11, 11b.

[0092] Furthermore, when the control device 100 determines that there is an instruction to stop the AUX output (an instruction to stop the output from the AUX port 25) based on the detection sensor output signal of the auxiliary operation device 103, it switches the AUX control valve 60C to the third position 60d by the AUX solenoid valve 65 to stop the flow of hydraulic oil into and out of the auxiliary actuator 27. This stops the auxiliary actuator 27.

[0093] The flow rate of hydraulic oil flowing from the AUX port 25 to the auxiliary actuator 27 is controlled by the control device 100. For example, attachment information related to the attachment 11 that can be used with the work machine 1 is pre-stored in the storage device 110. The attachment information includes information indicating the identification information and specifications of the attachment 11. The specifications of the attachment 11 include information indicating the presence or absence of an auxiliary actuator 27, and if an auxiliary actuator 27 is present, further includes information indicating the specifications of the auxiliary actuator 27. The specifications of the auxiliary actuator 27 include the type and output magnitude of the auxiliary actuator 27, the required flow rate of hydraulic oil for operating the auxiliary actuator 27, control data for the AUX solenoid valve 65, etc.

[0094] When information indicating the attachment 11 attached to the working apparatus 4 is input via the input / output interface 111, the control device 100 reads attachment information corresponding to the attached attachment 11 from the storage device 110 based on the input information. The control device 100 also determines from the read attachment information whether or not the attachment 11 attached to the working apparatus 4 has an attached actuator 27, and if the attachment 11 has an attached actuator 27, further reads the specifications of the attached actuator 27 from the attachment information.

[0095] When the control device 100 determines that an AUX output start command has been issued based on an output signal from a detection sensor of the auxiliary operation device 103, it controls the current value of the control signal input to the first AUX solenoid valve 65A and the second AUX solenoid valve 65B based on control data included in the specifications of the auxiliary actuator 27 to adjust the opening of the first AUX solenoid valve 65A and the second AUX solenoid valve 65B. As a result, the AUX control valve 60C switches to either the first position 60a or the second position 60b according to the auxiliary actuator 27, and the opening of the AUX control valve 60C is adjusted, so that the hydraulic oil flows in and out of the auxiliary actuator 27 from the AUX control valve 60C via the AUX port 25 or the like in a direction and flow rate according to the auxiliary actuator 27.

[0096] The auxiliary operation device 103 is also an input device for inputting an instruction to change the flow rate of hydraulic oil to the auxiliary actuator 27. The auxiliary operation device 103 includes an auxiliary flow rate operation member and a flow rate instruction detection sensor. The auxiliary flow rate operation member is an operation member such as an operation switch, a dial, or a slider. The flow rate instruction detection sensor outputs a signal according to the operation position of the auxiliary flow rate operation member.

[0097] The control device 100 receives a flow rate change instruction for the hydraulic oil to the auxiliary actuator 27 based on an output signal from a flow rate instruction detection sensor of the auxiliary operation device 103. Then, the control device 100 controls the current value of the control signal input to the first AUX solenoid valve 65A and the second AUX solenoid valve 65B based on the control data of the auxiliary actuator 27 and the flow rate change instruction to adjust the opening degree of the first AUX solenoid valve 65A and the second AUX solenoid valve 65B. As a result, the AUX control valve 60C switches to either the first position 60a or the second position 60b according to the auxiliary actuator 27, and the opening degree of the AUX control valve 60C is adjusted, so that the flow rate of the hydraulic oil flowing into or out of the auxiliary actuator 27 from the AUX control valve 60C is changed from a flow rate (default value) corresponding to the control data to a flow rate (user input value) corresponding to the flow rate change instruction.

[0098] The operation of the auxiliary attachments 11, 11b (switching between drive (on) and stop (off), drive state, etc.) may be operated by a dedicated attachment operating device, or an operating application program previously stored in the storage device 110 may be executed by the control device 100 to operate the auxiliary attachments 11, 11b by the input / output interface 111. In either of these cases, the control device 100 may change the position and opening of the AUX control valve 60C by the AUX solenoid valve 65 in accordance with the operating state of either the dedicated attachment operating device or the input / output interface 111, and may start, adjust (adjust the amount and direction of inflow and outflow) and stop the flow of hydraulic oil into the auxiliary actuator 27. Also, the auxiliary operating device 103 may be omitted, and the configuration of the auxiliary operating device 103 described above may be provided in the input / output interface 111.

[0099] The work machine 1 is equipped with a rotation speed sensor 104, a swash plate angle sensor 105, a pressure sensor 106, and a temperature sensor 107. These sensors 104 to 107 are connected to the control device 100.

[0100] The rotation speed sensor 104 detects the actual rotation speed of the prime mover 6. The control device 100 controls the drive of the prime mover 6 so that the actual rotation speed of the prime mover 6 matches the target rotation speed input by the accelerator device 101. As another example, a control device (e.g., an engine control unit) other than the control device 100 provided in the work machine 1 may control the drive of the prime mover 6 so that the actual rotation speed of the prime mover 6 matches the target rotation speed.

[0101] In addition, the control device 100 detects the actual rotation speed of the prime mover 6 detected by the rotation speed sensor 104. The travel motor 51 may be automatically switched to either the first speed stage or the second speed stage based on the speed control device 102. For example, when the travel motor 51 is in the second speed stage, if the actual rotation speed of the prime mover 6 falls below a predetermined value, the control device 100 switches the travel motor 51 to the first speed stage by the travel switching valve 57 (automatic deceleration). The control device 100 may also automatically switch the travel motor 51 to either the first speed stage or the second speed stage based on other parameters such as the vehicle speed of the work machine 1 detected by a sensor. In this way, switching of the travel motor 51 to either the first speed stage or the second speed stage may be performed not only by manual operation by the speed operation device 102 but also automatically by the control device 100.

[0102] The swash plate angle sensor 105 detects the angle of the swash plate of the main pump P2. The temperature sensor 107 detects the temperatures of the hydraulic oil and the pilot oil. A plurality of pressure sensors 106 are provided in each section of the hydraulic circuit of the working system in Fig. 1 and the hydraulic circuit of the traveling system in Fig. 2. The pressure sensors 106 include AUX pressure sensors 106a, 106b, working pressure sensors 106c, 106d, 106e, 106f, traveling pressure sensors 106g, 106h, 106i, 106j, and a load pressure sensor 106k.

[0103] 1, the AUX pressure sensors 106a, 106b are connected to the oil passages 64a, 64b, respectively, and detect the pressure of hydraulic oil acting from the AUX control valve 60C to the AUX port 25. The work pressure sensors 106c, 106d, 106e, 106f are connected to the work oil passages 46a, 46b, 46c, 46d, respectively, and detect the pilot pressure acting on the work pressure receiving portions 61a, 61b, 62a, 62b of the work control valves 60A, 60B from the work operation valve 69 (pilot valves 69A, 69B, 69C, 69D).

[0104] The load pressure sensor 106k is connected to the PLS oil passage 84 and detects the highest load pressure (PLS pressure) among the load pressures of the actuators 14, 15, 27. The travel pressure sensors 106g, 106h, 106i, 106j are connected to the travel oil passages 42a, 42b, 42c, 42d, respectively, as shown in Fig. 2, and detect pilot pressure acting on the pump pressure receiving parts 50a, 50b of the travel pumps 50 (50L, 50R) from the travel operation valves 56 (56A, 56B, 56C, 56D). In addition to or instead of the pressure sensors 106 (106a to 106k), a flow rate sensor that detects the flow rate of the hydraulic oil may be provided.

[0105] Fig. 4 is a flow chart showing an example of the operation of the work machine 1 during work. Each step in Fig. 4 is repeatedly executed by the control device 100 based on a software program stored in the internal memory while the prime mover 6 is being driven. The same applies to each step in the flow charts of other figures described later.

[0106] The control device 100 reads input information indicating the attachment 11 that is input via the input / output interface 111 and stored in the internal memory or the storage device 110, and attachment information corresponding to the attachment 11 indicated by the input information (S1 in FIG. 4). That is, the control device 100 reads input information indicating the attachment 11 mounted on the working device 4, and attachment information corresponding to the input information.

[0107] If the attachment 11 mounted on the work implement 4 is an attachment that does not have an auxiliary actuator 27, such as a bucket 11a, the control device 100 determines that the attachment 11 does not have an auxiliary actuator 27 based on the attachment information of the attachment 11 (S2: NO). In this case, even if work (such as excavation work) is being performed by the work implement 4 and the attachment 11, the load on the prime mover 6 is light and the work is light-load work, so the control device 100 fully closes the AUX solenoid valve 65 and holds the AUX control valve 60C in the neutral position (third position) 60d in accordance with the light-load work (S3). As a result, hydraulic oil does not flow into or out of the AUX port 25 from the AUX control valve 60C, AUX port 25 will be unused.

[0108] On the other hand, if the attachment 11 mounted on the working device 4 is an auxiliary attachment having an auxiliary actuator 27, the control device 100 determines that the auxiliary actuator 27 is present based on the attachment information corresponding to the auxiliary attachment 11 (S2: YES).

[0109] Also, if the attachment 11 mounted on the working device 4 is an auxiliary attachment having a low- or medium-output auxiliary actuator 27 such as a broom, when the working device 4 and the auxiliary attachment 11 perform work (cleaning work using a brush), the load on the prime mover 6 is low or medium. That is, the work performed by the working device 4 and the auxiliary attachment 11 is light-load work or medium-load work. In this case, the control device 100 determines that the auxiliary actuator 27 provided on the auxiliary attachment 11 is not a high-output auxiliary actuator based on the attachment information corresponding to the auxiliary attachment 11 (S4: NO). Then, since the work performed by the working device 4 and the auxiliary attachment 11 is light-load work or medium-load work, the control device 100 executes a light-load / medium-load output process for controlling the output (supply amount of hydraulic oil) from the AUX port 25 to the auxiliary actuator 27 in accordance with the work (S5).

[0110] Furthermore, if the attachment 11 mounted on the working implement 4 is an auxiliary attachment having a high-output auxiliary actuator 27, such as a mulcher 11b, the load on the prime mover 6 increases when the working implement 4 and the auxiliary attachment 11 perform work (such as crushing fallen trees). That is, the work performed by the working implement 4 and the auxiliary attachment 11 is high-load work. In this case, the control device 100 determines that the auxiliary actuator 27 provided on the auxiliary attachment 11 is a high-output auxiliary actuator based on the attachment information corresponding to the attachment 11 (S4: YES). Then, since the work performed by the working implement 4 and the auxiliary attachment 11 is high-load work, the control device 100 executes high-load output processing to control the output from the AUX port 25 to the auxiliary actuator 27 in accordance with the high-load work (S6).

[0111] Fig. 5 is a flow chart showing an example of the light-load / medium-load output processing (S5) of Fig. 4. Fig. 6 is a diagram showing an example of a control map for the AUX solenoid valve 65 during the light-load / medium-load output processing. The horizontal axis of the graph shown in Fig. 6 indicates the rotation speed of the prime mover 6, and the vertical axis indicates the current value of the control signal input to the AUX solenoid valve 65. The same applies to the graph showing the control map in Fig. 8 described later.

[0112] In the light-load / medium-load output process, when the driver of the work implement 1 operates the accessory output operation member of the accessory operation device 103 to the start position, an AUX output start command is input from the accessory operation device 103 (S11 in FIG. 5). Then, the control device 100 reads control data corresponding to the accessory actuator 27 provided on the accessory attachment 11 from the attachment information corresponding to the accessory attachment 11 mounted on the work implement 4 (S12). Then, based on the control data, the control device 100 determines either the first AUX solenoid valve 65A or the second AUX solenoid valve 65B as the active AUX solenoid valve that receives the control signal (S13).

[0113] The control data read in step S12 includes a control map L1 (FIG. 6) corresponding to the auxiliary attachment 11 (auxiliary actuator 27) for performing light-load work or medium-load work. As shown by the solid line in FIG. 6, the control map L1 indicates the current value of the control signal input to the operating AUX solenoid valve when the rotation speed of the prime mover 6 is within the working rotation speed range E1. In the control map L1, even if the rotation speed of the prime mover 6 changes within the working rotation speed range E1, the operating The current value of the control signal for the AUX solenoid valve is constant. The control map L1 is an example of a non-high load control map.

[0114] When the driver does not operate the accessory flow rate operating member of the accessory operating device 103 (S14: NO in FIG. 5), the control device 100 inputs a control signal to the operating AUX solenoid valve based on the control map L1. That is, the control device 100 inputs a control signal of a current value indicated in the control map L1 corresponding to the accessory attachment 11 (accessory actuator 27) to the operating AUX solenoid valve. As a result, hydraulic oil is output (supplied) from the AUX control valve 60C to the accessory actuator 27 of the accessory attachment 11 via the AUX port 25 or the like (S16).

[0115] Furthermore, when the driver operates the auxiliary flow rate operating member of the auxiliary operating device 103 to input an instruction to change the flow rate of hydraulic oil to the auxiliary actuator 27 (S14: YES), the control device 100 shifts the control map L1 in accordance with the flow rate change instruction (S15). In detail, the control device 100 determines a change value of the control signal to the operating AUX solenoid valve from the flow rate change instruction, and shifts the control map L1 in the vertical axis direction along which the current value of the control signal in Fig. 6 changes so that the current value indicated by the control map L1 matches the change value. In Fig. 6, the shifted control map L1s is indicated by a thin solid line.

[0116] 6 shows an example in which the control map L1 indicates an upper limit value of the current of the control signal to the operating AUX solenoid valve and can be shifted in a decreasing direction of the current. Alternatively, the control map L1 may be configured to indicate, for example, an intermediate value of the current range in which the control signal can be input to the operating AUX solenoid valve and can be shifted in both a decreasing direction and an increasing direction of the current.

[0117] When the control device 100 shifts the control map L1, it inputs a control signal to the active AUX solenoid valve based on the post-shift control map L1s. That is, the control device 100 inputs a control signal of a current value indicated by the post-shift control map L1s according to the driver's instruction to the active AUX solenoid valve. As a result, hydraulic oil at a flow rate desired by the driver is output (supplied) from the AUX control valve 60C to the auxiliary actuator 27 of the auxiliary attachment 11 via the AUX port 25 or the like (S16).

[0118] More specifically, in step S16, the control device 100 inputs a control signal of a current value according to the control map L1 or the shifted control map L1s to the determined active AUX solenoid valve of the first AUX solenoid valve 65A and the second AUX solenoid valve 65B. This opens the active AUX solenoid valve, and the opening degree of the active AUX solenoid valve is adjusted. At this time, a control signal is not input to the AUX solenoid valve that is not determined as the active AUX solenoid valve of the first AUX solenoid valve 65A and the second AUX solenoid valve 65B, and the AUX solenoid valve remains closed. For this reason, a pilot pressure acts from the active AUX solenoid valve to the corresponding AUX pressure receiving portion 63a, 63b of the AUX control valve 60C, and the AUX control valve 60C is switched to either the first position 60a or the second position 60b. In addition, the opening degree of the AUX control valve 60C is adjusted.

[0119] Then, hydraulic oil is supplied from the AUX control valve 60C to the auxiliary actuator 27 via the oil passage 64 and the AUX port 25 in a supply direction and at a supply amount (or a supply amount desired by the operator) according to the auxiliary attachment 11 (auxiliary actuator 27). In addition, hydraulic oil from the auxiliary actuator 27 flows into the AUX control valve 60C via the AUX port 25 and the oil passage 64 in a direction and at a flow rate (or a flow rate desired by the operator) according to the auxiliary attachment 11, and is discharged from the AUX control valve 60C. This causes the auxiliary actuator 27 to operate, and the auxiliary actuator 27 and the working device 4 can perform the corresponding light-load work or medium-load work. Note that the working machine 1 may perform light-load work or medium-load work on the auxiliary actuator 27 and the working device 4 while traveling by the traveling device 5. (The same applies to high-load work.)

[0120] Thereafter, even if the rotation speed of the prime mover 6 changes within the work rotation speed range E1 during light load work or medium load work, the control device 100 keeps the current value of the control signal input to the operating AUX solenoid valve constant based on the control map L1, and maintains the opening of the operating AUX solenoid valve. As a result, hydraulic oil continues to flow into the auxiliary actuator 27 through the AUX port 25 or the like in a direction and at a flow rate according to the auxiliary actuator 27.

[0121] Furthermore, thereafter, when an AUX output stop command is input from the accessory operation device 103 in response to the driver operating the accessory output operation member to the stop position (S17 in FIG. 5: YES), the control device 100 stops the control current input to the operating AUX solenoid valve and stops the output of hydraulic oil from the AUX port 25 to the accessory actuator 27 provided on the accessory attachment 11 (S18). This stops the operation of the accessory actuator 27, ends the light-load / medium-load output process, and also ends the light-load or medium-load work.

[0122] 7A and 7B are flow charts showing an example of the high load output process (S6) in FIG. 4. FIG. 8 is a diagram showing an example of a control map of the AUX solenoid valve 65 during the high load output process. In the high load output process, when an AUX output start command is input from the accessory operating device 103 as described above (S21 in FIG. 7A), the control device 100 reads control data from the attachment information corresponding to the accessory attachment 11 attached to the working device 4 (S22). Then, the control device 100 determines, based on the control data, which of the first AUX solenoid valve 65A and the second AUX solenoid valve 65B is the active AUX solenoid valve (S23).

[0123] The control data read in step S22 in Fig. 7A includes a plurality of control maps L2, L3 (Fig. 8) corresponding to the additional attachment 11 for performing high-load work. Of these, the normal control map L2 indicates the current value of the control signal input to the active AUX solenoid valve when the rotation speed of the prime mover 6 is within the working rotation speed range E1, as shown by the two-dot chain line in Fig. 8. In the normal control map L2, the current value of the control signal for the active AUX solenoid valve is constant even if the rotation speed of the prime mover 6 changes within the working rotation speed range E1. The normal control map L2 is also an example of a non-high-load control map.

[0124] The high load control map L3 indicates the current value of the control signal to be input to the operating AUX solenoid valve according to the rotation speed of the prime mover 6 when the actual rotation speed of the prime mover 6 detected by the rotation speed sensor 104 drops below the target rotation speed of the prime mover 6 input by the accelerator device 101, and the amount of drop becomes equal to or exceeds a predetermined threshold (drops).

[0125] As shown by the solid line in Fig. 8, in the high load control map L3, the current value of the control signal for the operating AUX solenoid valve decreases from the constant current value shown in the normal control map L2 in proportion to the decrease in the rotation speed of the prime mover 6. Also, in the high load control map L3, the slope, which is the ratio of the increase in the current value to the increase in the rotation speed of the prime mover 6, is larger when the current value of the control signal for the operating AUX solenoid valve is in the second range C2 smaller than the first range C1 than when it is in the first range C1. The high load control map L3 and the normal control map L2 have a coincidence point Q1 that indicates the same current value of the control signal at the same rotation speed of the prime mover 6.

[0126] When the driver operates the auxiliary flow rate operating member of the auxiliary operating device 103 to input a command to change the flow rate of hydraulic oil to the auxiliary actuator 27 (S24: YES), the control device 100 shifts the normal control map L2 in response to the command to change the flow rate (S25). In detail, like the control map L1 described above, the control device 100 determines the change value of the control signal to the operating AUX solenoid valve from the command to change the flow rate, and shifts the normal control map L2 in the vertical axis direction along which the current value of the control signal in Fig. 8 changes so that the current value indicated by the normal control map L2 matches the change value. In Fig. 8, the shifted normal control map L2s is indicated by a thin two-dot chain line.

[0127] 8 shows an example in which the normal control map L2 indicates an upper limit value of the current of the control signal to the operating AUX solenoid valve and can shift the current in a decreasing direction. Alternatively, the normal control map L2 may be configured to indicate, for example, an intermediate value of the current range in which the control signal can be input to the operating AUX solenoid valve and can shift the current in both a decreasing direction and an increasing direction.

[0128] If the driver does not operate the auxiliary flow rate operating member of the auxiliary operating device 103 (S24 in FIG. 7A: NO), the normal control map L2 is not shifted by the control device 100.

[0129] Next, the control device 100 acquires the actual rotation speed and the target rotation speed of the prime mover 6, and compares the actual rotation speed with the target rotation speed. If the actual rotation speed of the prime mover 6 is not lower than the target rotation speed (S26: NO), the control device 100 inputs a control signal of a current value based on the normal control maps L2 and L2s to the operating AUX solenoid valve.

[0130] At this time, if the normal control map L2 has not been shifted, the control device 100 inputs a control signal of a constant current value (predetermined value) indicated by the normal control map L2 corresponding to the auxiliary attachment 11 (auxiliary actuator 27) to the operating AUX solenoid valve. If the normal control map L2 has been shifted, the control device 100 inputs a control signal of a constant current value indicated by the normal control map L2s after the shift in response to the driver's instruction to the operating AUX solenoid valve. As a result, the hydraulic oil is output (supplied) from the AUX control valve 60C to the auxiliary actuator 27 of the auxiliary attachment 11 via the AUX port 25 or the like (S32 in FIG. 7B).

[0131] 7B, the control device 100 inputs a control signal of a constant current value indicated in the normal control map L2 or the post-shift normal control map L2s to an active AUX solenoid valve of either the first AUX solenoid valve 65A or the second AUX solenoid valve 65B. At this time, no control signal is input to an AUX solenoid valve that has not been determined as an active AUX solenoid valve of the first AUX solenoid valve 65A or the second AUX solenoid valve 65B, and the AUX solenoid valve remains closed.

[0132] Thereby, the operating AUX solenoid valve opens, the opening degree of the operating AUX solenoid valve is adjusted according to the auxiliary attachment 11, and hydraulic oil is caused to flow into the auxiliary actuator 27 through the AUX control valve 60C, the oil passage 64, and the AUX port 25 in a direction and flow rate according to the auxiliary attachment 11 (auxiliary actuator 27). Then, the auxiliary actuator 27 operates, and the corresponding high-load work can be performed by the auxiliary actuator 27 and the working device 4.

[0133] After step S32 in Fig. 7A, if an AUX output stop command is not input from the auxiliary operating device 103 (S35: NO), the control device 100 again acquires the actual rotation speed and the target rotation speed of the prime mover 6. Then, if the actual rotation speed of the prime mover 6 has not decreased relative to the target rotation speed (S26 in Fig. 7A: NO), the control device 100 continues to input a control signal of a constant current value indicated by the normal control map L2 or the normal control map L2s after the shift to the operating AUX solenoid valve (S32 in Fig. 7B).

[0134] If the actual rotation speed of the prime mover 6 is lower than the target rotation speed (S26 in FIG. 7A: YES), the control device 100 calculates a drop amount, which is the amount of drop of the actual rotation speed from the target rotation speed (target rotation speed-actual rotation speed) (S27). At this time, if a control signal is not input to the operating AUX solenoid valve (S28: NO), the auxiliary actuator 27 is not activated, so the control device 100 checks whether the drop amount is equal to or greater than a second threshold value. The second threshold value is a threshold value (e.g., 300 to 500 rpm) that is applied during activation of the auxiliary actuator 27 or immediately after activation.

[0135] Furthermore, if the control device 100 is inputting a control signal to the operating AUX solenoid valve (S28: YES), it checks whether a predetermined time has passed since it started inputting a control signal to the operating AUX solenoid valve. If the predetermined time has not passed (S29: NO), the auxiliary actuator 27 is in operation or has just been started, so the control device 100 checks whether the drop amount is equal to or greater than the second threshold. If the drop amount is less than the second threshold (S30: NO in FIG. 7B), the control device 100 continues to input a control signal of a constant current value indicated by the normal control map L2 or the normal control map L2s after the shift to the operating AUX solenoid valve (S32).

[0136] On the other hand, if the drop amount is equal to or greater than the second threshold (S30: YES), the control device 100 shifts the high load control map L3 included in the control data read in step S22 in accordance with the actual rotation speed of the prime mover 6 (S33). At this time, if the normal control map L2 has not been shifted, the control device 100 shifts the high load control map L3 in the horizontal axis direction along which the rotation speed changes, so that the rotation speed indicated by the coincidence point Q1 between the high load control map L3 and the normal control map L2 coincides with the actual rotation speed Rc of the prime mover 6 when the drop amount becomes equal to or greater than the second threshold, as shown in FIG. 9A, for example.

[0137] Furthermore, if the normal control map L2 has already been shifted, the control device 100 shifts the high load control map L3 in the horizontal axis direction along which the rotation speed changes so that the rotation speed indicated by the coincidence point Q2 between the high load control map L3 and the normal control map L2s after the shift coincides with the actual rotation speed Rc of the prime mover 6 when the drop amount becomes equal to or greater than the second threshold, as shown in Fig. 9B for example. In Fig. 9B and Fig. 9A, the high load control map L3s after the shift is indicated by a thin solid line.

[0138] Then, the control device 100 changes the current value of the control signal input to the operating AUX solenoid valve in accordance with the high load control map L3s after the shift and the actual rotation speed of the prime mover 6 (the rotation speed after the drop amount becomes equal to or greater than the second threshold value), thereby limiting the output of hydraulic oil to the auxiliary actuator 27 (S34 in FIG. 7B).

[0139] In step S34, the control device 100 determines a limit current value according to the actual rotation speed of the prime mover 6 from the shifted high load control map L3s, and changes the current value of the control signal input to the operating AUX solenoid valve to a smaller limit current value. This reduces the pilot pressure acting on the AUX pressure receiving parts 63a, 63b of the AUX control valve 60C, reducing the opening of the AUX control valve 60C, and restricts (reduces) the flow rate of hydraulic oil from the AUX control valve 60C to the auxiliary actuator 27 via the AUX port 25, etc. In other words, the control device 100 restricts the output from the AUX port 25, thereby executing anti-stall control that prevents unintended stop of the prime mover 6. This anti-stall control is sometimes called AUX anti-stall control.

[0140] After step S34, if the AUX output stop command is not input from the auxiliary operation device 103 (S35: NO), the control device 100 again acquires the actual rotation speed and the target rotation speed of the prime mover 6. Then, if the actual rotation speed of the prime mover 6 falls below the target rotation speed (S26 in FIG. 7A: YES), the control device 100 calculates the drop amount (S27).

[0141] Also, if a predetermined time has passed since the start of inputting a control signal to the operating AUX solenoid valve (S28: YES, S29: YES), the driving state of the auxiliary actuator 27 is stable, so the control device 100 checks whether the drop amount is equal to or greater than the first threshold value. The first threshold value is a threshold value applied during driving of the auxiliary actuator 27, and is set to a value (e.g., 200 rpm) smaller than the second threshold value during or immediately after the start of the auxiliary actuator 27 described above. If the drop amount is less than the first threshold value (S31: NO in FIG. 7B), the control device 100 inputs a control signal of a constant current value indicated by the normal control map L2 or the normal control map L2s after the shift to the operating AUX solenoid valve (S32).

[0142] On the other hand, if the drop amount is equal to or greater than the first threshold (S31: YES), the control device 100 shifts the high load control map L3 according to the actual rotation speed of the prime mover 6 as described above (S33). Then, the control device 100 changes the current value of the control signal input to the operating AUX solenoid valve according to the shifted high load control map L3s and the actual rotation speed of the prime mover 6 (the rotation speed after the drop amount becomes equal to or greater than the first threshold) to limit the output to the auxiliary actuator 27 (S34). That is, the control device 100 executes AUX anti-stall control.

[0143] In step S34, the control device 100 may, for example, suddenly change (suddenly decrease) the current value of the control signal input to the operating AUX solenoid valve to make it coincide with the limited current value (target current value) calculated from the high load control map L3s and the actual rotation speed of the prime mover 6. Alternatively, since the control device 100 inputs a control signal to the operating AUX solenoid valve by PWM (pulse width modulation), the control device 100 may gradually decrease the duty ratio of the PWM to gradually change (slowly decrease) the current value Ac of the control signal input to the operating AUX solenoid valve at a predetermined speed (for example, 10 mA / sec) as shown in Fig. 10 to make it coincide with the limited current value Ar over a predetermined time T1.

[0144] Furthermore, by executing step S34 in FIG. 7B, even if the current value of the control signal for the operating AUX solenoid valve is reduced according to the high load control map L3s and the actual rotation speed of the prime mover 6 and the output to the auxiliary actuator 27 is reduced, the actual rotation speed may continue to decrease and the drop amount may not become less than the first threshold value (S35: NO in FIG. 7B, S26: YES, S27, S28: YES, S29: YES, S31: YES in FIG. 7A).

[0145] In this case, the control device 100 again changes the current value of the control signal for the operating AUX solenoid valve in accordance with the high load control map L3s and the actual rotation speed of the prime mover 6 to limit the output to the auxiliary actuator 27 (S34 in FIG. 7B). At this time, when the current value of the control signal for the operating AUX solenoid valve is in the second range C2 (FIG. 8), the control device 100 reduces the current value to a greater extent than when it is in the first range C1.

[0146] In addition, after limiting the output to the auxiliary actuator 27 in step S34 in Fig. 7B, the target rotation speed of the prime mover 6 may decrease, or the load on the prime mover 6 may be reduced, and the drop amount may become less than the first threshold value (S35: NO, S26: YES, S27, S28: YES, S29: YES, S31: NO in Fig. 7A). In this case, the control device 100 inputs a control signal of a current value indicated in the normal control map L2 or the normal control map L2s after the shift to the operating AUX solenoid valve (S32 in Fig. 7B).

[0147] As a result, the output of hydraulic oil to the auxiliary actuator 27 is no longer restricted, and the AUX anti-stall control is stopped. At that time, the control device 100 may suddenly change (increase) the current value of the control signal input to the operating AUX solenoid valve so that it coincides with the current value indicated in the normal control map L2 or the normal control map L2s after the shift, or may gradually change (increase) it at a predetermined speed (for example, 10 mA / sec).

[0148] Thereafter, when an instruction to stop the AUX output is input from the auxiliary operating device 103 (S35: YES in FIG. 7B), the control device 100 stops the output from the AUX port 25 to the auxiliary actuator 27 (S36). This stops the operation of the auxiliary actuator 27, and the high-load output process and the high-load operation are terminated.

[0149] In the above embodiment, an example was shown in which the threshold value to be compared with the drop amount is different between after a predetermined time has elapsed since the hydraulic oil was supplied to the auxiliary actuator 27 and before that time. The pressure may be the same before and after a predetermined time has elapsed since the hydraulic oil was supplied to the actuator 27.

[0150] While the prime mover 6 is being driven, the control device 100 or another ECU (electronic control device) controls the prime mover 6 so that the actual rotation speed coincides with the target rotation speed. However, when an accelerator operating member of the accelerator device 101 is operated suddenly and significantly, for example, as shown in Fig. 11A, the accelerator signal Ja output from the accelerator device 101 changes suddenly (changes suddenly and significantly), and the target rotation speed Rt of the prime mover 6 based on the accelerator signal Ja also changes suddenly (suddenly increases in Fig. 11A).

[0151] Therefore, the control of the prime mover 6 is delayed, and the actual rotation speed Rc of the prime mover 6 temporarily deviates significantly from (significantly drops) the target rotation speed Rt, and the drop amount temporarily becomes equal to or greater than the first threshold value (S31 in FIG. 7B: YES). If the control device 100 then reduces the current value of the control signal to the operating AUX solenoid valve in response to this, as described above, to limit the flow rate of hydraulic oil to the auxiliary actuator 27 (S34 in FIG. 7B), the operability of the auxiliary attachment 11 will be unnecessarily reduced.

[0152] As a countermeasure, the control device 100 may generate an accelerator pseudo signal Jf based on the accelerator signal Ja input from the accelerator device 101, as shown in FIG. 11A, when a high-load task is being performed by the work unit 4U (attachment 11). Specifically, the control device 100 generates an accelerator pseudo signal Jf that changes at a predetermined speed (slope) by the same amount of change as the accelerator signal Ja (the absolute value of the difference between a constant value before the change in the accelerator signal Ja and a constant value after the change). The control device 100 may also generate the accelerator pseudo signal Jf only in the case of a sudden change in which the amount of change in the accelerator signal Ja is equal to or greater than the predetermined amount. In the example of FIG. 11A, the accelerator signal Ja has risen sharply, so the accelerator pseudo signal Jf changes more slowly than the accelerator signal Ja. That is, the rate of change of the accelerator pseudo signal Jf is slower than the rate of change of the accelerator signal Ja.

[0153] After generating the accelerator pseudo signal Jf as shown in Fig. 11A, the control device 100 etc. determines the target rotation speed Rt of the prime mover 6 based on the accelerator signal Ja, and controls the driving of the prime mover 6 so that the actual rotation speed Rc coincides with the target rotation speed Rt. Note that the actual rotation speed Rc shown in Fig. 11A is an example of the actual rotation speed when a predetermined normal load (non-high load) is applied and the prime mover 6 does not stop unintentionally (the same applies to the actual rotation speed Rc shown in Fig. 11B described later). The control device 100 also calculates the pseudo rotation speed Rf of the prime mover 6 based on the accelerator pseudo signal Jf.

[0154] 11A, when the target rotation speed Rt of the prime mover 6 is increased by the accelerator device 101, the control device 100 calculates the amount of decrease in the actual rotation speed Rc relative to the target rotation speed Rt as the drop amount. If the drop amount is equal to or greater than the first threshold value or equal to or greater than the second threshold value (S31: YES or S30: YES in FIG. 7B), the control device 100 shifts the high load control map L3 as described above based on the pseudo rotation speed Rf1 corresponding to the occurrence of the drop (see S33 in FIG. 7B, FIGS. 9A and 9B).

[0155] Then, the control device 100 changes the current value of the control signal input to the operating AUX solenoid valve according to the high load control map L3s after the shift and the pseudo rotation speed Rf (the pseudo rotation speed Rf after the point at which the drop amount becomes equal to or greater than the first threshold value or the second threshold value), thereby limiting the output of hydraulic oil to the auxiliary actuator 27. Alternatively, the control device 100 may reduce the current value of the control signal to the operating AUX solenoid valve according to the high load control map L3s after the shift and the actual rotation speed Rc of the prime mover 6, thereby limiting the flow rate of hydraulic oil to the auxiliary actuator 27 (S34 in FIG. 7B).

[0156] As a result, even if the target rotation speed Rt of the prime mover 6 rises suddenly and the actual rotation speed Rc temporarily deviates significantly from the target rotation speed Rt (even if the actual rotation speed Rc drops suddenly relative to the target rotation speed Rt) due to the accelerator operating member being operated suddenly and significantly when no high load is applied to the prime mover 6, the high load control map L3 is not shifted unnecessarily. Therefore, the AUX anti-stall control is appropriately executed according to the amount of drop caused by the application of a high load to the prime mover 6, and the deterioration of workability caused by the attachment 11 is suppressed.

[0157] The example of Figure 11A shows a case where the accelerator signal Ja and the target rotation speed Rt suddenly increase due to a sudden and drastic upward operation of the accelerator device 101, but the control device 100 may also generate the accelerator pseudo signal Jf when the accelerator signal Ja and the target rotation speed Rt suddenly decrease due to a sudden and drastic downward operation of the accelerator device 101, as shown in Figure 11B.

[0158] The control device 100 may also make the rate of change of the accelerator pseudo signal Jf when the accelerator device 101 is suddenly and significantly lowered different from the rate of change of the accelerator pseudo signal Jf when the accelerator device 101 is suddenly and significantly raised. Furthermore, the control device 100 may make the rate of change of the accelerator pseudo signal Jf when the accelerator device 101 is suddenly and significantly lowered faster than the rate of change of the accelerator pseudo signal Jf when the accelerator device 101 is suddenly and significantly raised. The control device 100 may also generate the accelerator pseudo signal Jf by performing moving average processing of the accelerator signal Ja over a predetermined time.

[0159] When high-load work is being performed by the work unit 4U (attachment 11), the control device 100 etc. generates an accelerator pseudo signal Jf as shown in Fig. 11B, then determines a target rotation speed Rt based on the accelerator signal Ja, and controls the prime mover 6 so that the actual rotation speed Rc matches the target rotation speed Rt. The control device 100 also calculates a pseudo rotation speed Rf for the prime mover 6 based on the accelerator pseudo signal Jf.

[0160] 11B shows a case where the accelerator device 101 is suddenly and significantly lowered when a drop occurs (a state in which the amount of drop is equal to or greater than the first threshold value or the second threshold value) and AUX anti-stall control is being executed (during the drop occurrence), causing the accelerator signal Ja to suddenly drop. In this case, if the control device 100 calculates the amount of drop in the actual rotation speed Rc relative to the target rotation speed Rt as the amount of drop, the amount of drop may become less than the first threshold value or the second threshold value by the time the actual rotation speed Rc drops to the same level as the target rotation speed Rt after the sudden drop (for example, at the time of the actual rotation speed Rc1 in FIG. 11B), causing the AUX anti-stall control to be stopped and the load on the prime mover 6 to increase.

[0161] Therefore, when high-load work is being performed by the work unit 4U, if the accelerator device 101 is suddenly and significantly lowered, causing a sudden drop in the target rotation speed Rt of the prime mover 6, the control device 100 may calculate the amount of drop in the actual rotation speed Rc relative to the target rotation speed Rt multiple times within a predetermined period of time, and calculate the average of the multiple calculated amounts of drop as the drop amount. This allows the AUX anti-stall control to continue appropriately, preventing an unintended drop in the prime mover 6 and suppressing a decrease in workability caused by the auxiliary attachment 11.

[0162] When high-load work is being performed by the work unit 4U, even if the accelerator device 101 is suddenly and significantly raised, causing a sudden rise in the target rotation speed Rt of the prime mover 6, the control device 100 may calculate the amount of decrease in the actual rotation speed Rc relative to the target rotation speed Rt multiple times within a predetermined period of time and calculate the average of the multiple calculated amounts of decrease as the drop amount. That is, the control device 100 may calculate the drop amount by performing moving average processing on the amount of decrease in the actual rotation speed Rc relative to the target rotation speed Rt.

[0163] In the embodiment described above, when high-load work is being performed by the work unit 4U in the work machine 1, the control device 100 executes AUX anti-stall control to limit the output from the AUX control valve 60C to the auxiliary actuators 27 of the auxiliary attachments 11, 11b. However, instead of or in addition to this, the control device 100 may execute anti-stall control to limit the output from the work control valves 60A, 60B to the work actuators 14, 15, respectively, using the solenoid valve 71 shown in FIG.

[0164] Fig. 12 is a diagram showing another example of a hydraulic circuit of the work system of the work implement 1. As shown in Fig. 12, the work implement 1 is equipped with a work solenoid valve 71. The work solenoid valve 71 is a solenoid valve that changes the flow rate of hydraulic oil to the work actuators 14, 15 of the work implement 4 in response to a control signal (current signal) input from the control device 100. The work solenoid valve 71 is a proportional valve whose solenoid is excited and whose opening degree is changed in response to the control signal (current signal) input from the control device 100.

[0165] The work solenoid valve 71 is provided in a branch oil passage 40b branched from the discharge oil passage 40. The branch oil passage 40b branches into a plurality of passages midway, which are respectively connected to a plurality of work operation valves 69 of the work operation device 67. The opening degree of the work solenoid valve 71 changes according to the current value of the control signal input to the work solenoid valve 71, and the pilot pressure of the pilot oil supplied from the discharge oil passage 40 changes. Specifically, as the current value of the control signal input to the work solenoid valve 71 increases, the opening degree of the work solenoid valve 71 increases, and the pilot pressure output from the work solenoid valve 71 to the plurality of work operation valves 69, i.e., the primary pressure of the work operation valves 69, increases.

[0166] The secondary pressure of the work operation valve 69, i.e., the pilot pressure acting on the work pressure receiving parts 61a, 61b, 62a, and 62b of the work control valves 60A and 60B through the work oil passages 46a, 46b, 46c, and 46d from the work operation valve 69, changes in response to a change in the primary pressure of the work operation valve 69. The aperture of the work control valves 60A and 60B changes in response to a change in the secondary pressure of the work operation valve 69, and the output (supply amount of hydraulic oil) from the work control valves 60A and 60B to the corresponding work actuators 14 and 15 also changes. Specifically, as the primary pressure of the work operation valve 69 increases, the secondary pressure of the work operation valve 69 also increases, the aperture of the work control valves 60A and 60B increases, and the output from the work control valves 60A and 60B to the corresponding work actuators 14 and 15 increases.

[0167] According to the above configuration, the work solenoid valve 71 changes the pilot pressure acting on the work pressure receiving portions 61a, 61b, 62a, 62b of the work control valves 60A, 60B in response to the input control signal, thereby changing the flow rate of hydraulic oil from the work control valves 60A, 60B to the work actuators 14, 15. The control device 100 changes the current value of the control signal input to the work solenoid valve 71 to change the opening of the work solenoid valve 71, thereby adjusting the primary pressure and secondary pressure of the work operating valve 69, and controlling the output to the work actuators 14, 15.

[0168] Fig. 13 is a flow chart showing an example of output processing during operation of the work machine 1. This output processing is repeatedly executed by the control device 100 in place of or in addition to the output processing of Figs. 5, 7A, and 7B. Fig. 14 is a diagram showing an example of a control map of the work solenoid valve 71 during the output processing of Fig. 13. The horizontal axis of the graph shown in Fig. 14 indicates the rotation speed of the prime mover 6, and the vertical axis indicates the current value of the control signal input to the work solenoid valve 71. Information showing the control map of Fig. 14 is stored in, for example, the storage device 110.

[0169] When the control device 100 executes the light-load / medium-load output process in the procedure shown in Fig. 4 (S5 in Fig. 4, S41 in Fig. 13: light-load / medium-load output process), it reads the normal control map L4 (Fig. 14) corresponding to the working device 4 from the storage device 110. The normal control map L4 indicates the current value (predetermined value) of the control signal input to the working solenoid valve 71 when the rotation speed of the prime mover 6 is within the working rotation speed range E1, as shown by the two-dot chain line in Fig. 14. Normal Control Map L4 In this case, even if the rotation speed of the prime mover 6 changes within the working rotation speed range E1, the current value of the control signal of the working solenoid valve 71 is constant. The normal control map L4 is an example of a non-high load control map.

[0170] For example, when the driver operates the input / output interface 111 to input a flow rate change command to change the flow rate of hydraulic oil to the work actuators 14, 15 of the work implement 4 (S42: YES in FIG. 13), the control device 100 shifts the normal control map L4 in response to the flow rate change command (S43). This shift of the normal control map L4 is similar to the shift of the normal control map L2 described above (see FIG. 8). Hereinafter, for convenience, this will be referred to as the shifted normal control map L4s (not shown). Then, the control device 100 inputs a control signal of a current value indicated by the shifted normal control map L4s to the work solenoid valve 71 (S44 in FIG. 13).

[0171] In addition, if the driver does not input a command to change the flow rate of hydraulic oil to the work actuators 14, 15 via the input / output interface 111 (S42: NO), the control device 100 does not shift the normal control map L4, and inputs a control signal of the current value indicated in the normal control map L4 to the work solenoid valve 71 (S44).

[0172] When a control signal of a current value indicated in the normal control map L4 or the normal control map L4s after the shift is input to the work solenoid valve 71, the work solenoid valve 71 opens, the opening degree of the work solenoid valve 71 becomes a predetermined opening degree, and the primary pressure of the plurality of work operation valves 69 is set to a predetermined unrestricted magnitude. In this situation, when the work operation member 68 is operated in any direction, the work operation valve 69 among the plurality of work operation valves 69 corresponding to the operation direction of the work operation member 68 is operated, and pilot pressure is applied from the operated work operation valve 69 to the work pressure receiving portion 61a, 61b, 62a, 62b of any corresponding one of the work control valves 60A, 60B.

[0173] This switches the position and opening of any of the corresponding work control valves 60A, 60B, and hydraulic oil is supplied unrestricted from the work control valves 60A, 60B to any of the work actuators 14, 15 of the corresponding work device 4, causing the work actuator (lift cylinder) 14 to operate and the boom 10 to rise and fall, or the work actuator (tilt cylinder) 15 to operate and the attachment 11 attached to the work device 4 (hitch 24) to swing (tilt). In other words, light-load work or medium-load work can be performed by the work device 4 and the attachment 11.

[0174] On the other hand, when the control device 100 executes the high load output process in the procedure shown in Fig. 4 (S6 in Fig. 4, S41 in Fig. 13: high load output process), if an instruction to change the flow rate of hydraulic oil to the work actuators 14, 15 is input via the input / output interface 111 (S45: YES), the control device 100 shifts the normal control map L4 in response to the flow rate change instruction (S46). On the other hand, if an instruction to change the flow rate of hydraulic oil to the work actuators 14, 15 is not input via the input / output interface 111 (S45: NO), the control device 100 does not shift the normal control map L4.

[0175] Next, the control device 100 acquires the actual rotation speed and the target rotation speed of the prime mover 6, and if the actual rotation speed of the prime mover 6 has not decreased relative to the target rotation speed (FIG. 13S47: NO), it inputs a control signal of a current value indicated by the normal control maps L4, L4s to the working solenoid valve 71 (S50).

[0176] At this time, if the normal control map L4 has not been shifted, the control device 100 inputs a control signal of a constant current value (predetermined value) indicated by the normal control map L4 to the work solenoid valve 71. On the other hand, if the normal control map L4 has been shifted, the control device 100 inputs a control signal of a constant current value indicated by the normal control map L4s after the shift in response to the driver's instruction to the work solenoid valve 71. As a result, the work actuators 14, 15 operate the work operation member 68. and heavy-load work can be performed by the working device 4 and the auxiliary attachments 11, 11b. After step S50, the control device 100 executes step S41 again.

[0177] Then, when the actual rotation speed of the prime mover 6 falls below the target rotation speed (S47 in FIG. 13: YES), the control device 100 calculates the drop amount (S48) and checks whether the drop amount is equal to or greater than a predetermined first threshold value. The first threshold value at this time may be the same as or different from the first threshold value in step S31 in FIG. 7A described above.

[0178] If the drop amount is less than the first threshold (S49: NO in FIG. 13), the control device 100 continues to input a control signal of a constant current value indicated by the normal control map L4 or the normal control map L4s after the shift to the working solenoid valve 71 (S50). On the other hand, if the drop amount is equal to or greater than the first threshold (S49: YES), the control device 100 reads out the high load control map L5 corresponding to the working device 4 from the storage device 110. As shown by the solid line in FIG. 14, the high load control map L5 indicates the current value of the control signal input to the working solenoid valve 71 according to the rotation speed of the prime mover 6 when the decrease amount (drop amount) of the actual rotation speed of the prime mover 6 with respect to the target rotation speed becomes equal to or greater than the threshold. The tendency of the change in the high load control map L5 is similar to that of the high load control map L3 shown in FIG. 8, and therefore a description thereof will be omitted.

[0179] The control device 100 shifts the high load control map L5 according to the actual rotation speed of the prime mover 6 when the drop amount becomes equal to or greater than the first threshold value (S51 in FIG. 13). At this time, if the normal control map L4 has not been shifted, the control device 100 shifts the high load control map L5 in the horizontal axis direction along which the rotation speed changes, similar to the high load control map L3 shown in FIG. 9A. If the normal control map L4 has been shifted, the control device 100 shifts the high load control map L5 in the horizontal axis direction along which the rotation speed changes, similar to the high load control map L3 shown in FIG. 9B. Hereinafter, for convenience, this will be referred to as the shifted high load control map L5s (not shown).

[0180] Then, the control device 100 changes the current value of the control signal input to the working solenoid valve 71 according to the high load control map L5s after the shift and the actual rotation speed of the prime mover 6 (the rotation speed after the drop amount becomes equal to or greater than the first threshold value) to limit the output to the working actuators 14, 15 (S52). In detail, the control device 100 obtains a limit current value according to the actual rotation speed of the prime mover 6 from the high load control map L5 or the high load control map L5s after the shift, and changes the current value of the control signal input to the working solenoid valve 71 to a smaller limit current value.

[0181] As a result, the pilot pressure acting on the work pressure receiving portions 61a, 61b, 62a, 62b of the work control valves 60A, 60B decreases, the opening of the work control valves 60A, 60B decreases, and the amount of hydraulic oil supplied from the work control valves 60A, 60B to the work actuators 14, 15 is restricted (reduced). In other words, the control device 100 restricts the output from the work control valves 60A, 60B to the work actuators 14, 15, thereby executing anti-stall control that prevents unintended stop of the prime mover 6. This anti-stall control is sometimes called work anti-stall control.

[0182] At that time, the control device 100 may suddenly change (suddenly decrease) the current value of the control signal input to the working solenoid valve 71 so that it coincides with the limit current value, or may gradually change (gradually decrease) it at a predetermined speed. After step S52 in Fig. 13, the control device 100 executes step S41 again.

[0183] As another example, instead of the working solenoid valve 71 of FIG. 12, a plurality of working solenoid valves may be provided in the plurality of working oil passages 46a, 46b, 46c, and 46d. In this case, the control device 10 Based on the target rotation speed, actual rotation speed, and control maps L4, L5 of the prime mover 6, the control circuit 0 changes the current value of the control signal input to each of the multiple work solenoid valves to change the pilot pressure acting on the work pressure receiving sections 61a, 61b, 62a, 61b of the work control valves 60A, 60B, respectively, and controls or limits the output (amount of hydraulic oil supplied) from the work control valves 60A, 60B to the work actuators 14, 15.

[0184] In the above-described embodiment, an example has been shown in which the control device 100 determines whether the work performed by the working device 4 and the auxiliary attachment 11 is high-load work or other load work (light-load work, medium-load work) based on input information related to the attachment 11 inputted by the input / output interface 111 and attachment information corresponding to the input information. However, in addition to this, for example, when the control device 100 is flowing in or out of hydraulic oil through the AUX port 25, it may determine whether the work is high-load work or other load work based on a result of comparing the pressure of hydraulic oil acting on the AUX port 25 detected by the AUX pressure sensors 106a, 106b with a predetermined pressure.

[0185] Alternatively, the control device 100 may determine whether the work is high-load work or other load work based on the results of comparing the highest load pressure (PLS pressure) among the load pressures of the actuators 14, 15, 27 detected by the load pressure sensor 106k with a predetermined pressure.

[0186] Furthermore, even when work is being performed by an attachment 11 that is not provided with an auxiliary actuator 27, such as the bucket 11a, if an excessive external force acts on the attachment 11, a high load may be placed on the prime mover 6. For this reason, even when work is being performed by an attachment 11 that is not provided with an auxiliary actuator 27, the control device 100 may detect that high-load work is being performed based on, for example, pressure detected by at least one of the AUX pressure sensors 106a, 106b and the load pressure sensor 106k, and may execute at least one of the AUX anti-stall control and the work anti-stall control.

[0187] In addition, in addition to at least one of the AUX anti-stall control and the working anti-stall control, the control device 100 may execute anti-stall control to limit the output of the travel pump 50 by changing the pilot pressure from the travel operation valve 56 to the travel pump 50 using the solenoid valve 72 shown in FIG. 15.

[0188] Fig. 15 is a diagram showing another example of a hydraulic circuit of the travel system of the work machine 1. As shown in Fig. 15, the work machine 1 is equipped with a travel solenoid valve 72. The travel solenoid valve 72 is a solenoid valve that changes the flow rate of hydraulic oil to the travel pump 50 in response to a control signal (current signal) input from the control device 100. In addition, the travel solenoid valve 72 is a proportional valve in which a solenoid is excited and the opening degree is changed in response to the control signal (current signal) input from the control device 100.

[0189] The travel solenoid valve 72 is provided in a branch oil passage 40a branched from the discharge oil passage 40. The branch oil passage 40a branches into a plurality of passages downstream of the travel solenoid valve 72, and is connected to the plurality of travel operation valves 56 of the travel operation device 54, respectively. The opening degree of the travel solenoid valve 72 changes according to the current value of the control signal input to the travel solenoid valve 72, and the pilot pressure of the pilot oil supplied from the discharge oil passage 40 changes. Specifically, as the current value of the control signal input to the travel solenoid valve 72 increases, the opening degree of the travel solenoid valve 72 increases, and the pilot pressure output from the travel solenoid valve 72 to the plurality of travel operation valves 56, i.e., the primary pressure of the travel operation valves 56, increases.

[0190] The secondary pressure of the travel operation valve 56, i.e., the pilot pressure acting on the pump pressure receiving parts 50a and 50b of the travel pump 50 (first travel pump 50L, second travel pump 50R) from the travel operation valve 56 through the travel oil passages 42a, 42b, 42c, and 42d, changes in response to a change in the primary pressure of the travel operation valve 56. Then, the angle of the swash plate of the travel pump 50 (first travel pump 50L, second travel pump 50R) changes in response to a change in the secondary pressure of the travel operation valve 56, and the output (supply amount of hydraulic oil) from the travel pump 50 to the travel motor 51 (first travel motor 51L, second travel motor 51R) changes. Specifically, as the primary pressure of the travel operation valve 56 increases, the secondary pressure of the travel operation valve 56 also increases, the angle of the swash plate of the travel pump 50 increases, and the output from the travel pump 50 to the travel motor 51 increases.

[0191] According to the above configuration, the travel solenoid valve 72 changes the pilot pressure acting on the pump pressure receiving sections 50a, 50b of the travel pump 50 in response to the input control signal, thereby changing the flow rate of hydraulic oil from the travel pump 50 to the travel motor 51. The control device 100 adjusts the primary pressure and secondary pressure of the travel operation valve 56 by changing the current value of the control signal input to the travel solenoid valve 72, thereby controlling the output from the travel pump 50 to the travel motor 51.

[0192] Fig. 16 is a diagram showing an example of a control map of the traveling solenoid valve 72. The horizontal axis of the graph shown in Fig. 16 indicates the rotation speed of the prime mover 6, and the vertical axis indicates the current value of the control signal input to the traveling solenoid valve 72. Information showing the control map in Fig. 16 is stored in, for example, the storage device 110.

[0193] When the actual rotation speed of the prime mover 6 is not lower than the target rotation speed during the traveling of the work machine 1 by the traveling device 5, the control device 100 determines the current value of the control signal of the traveling solenoid valve 72 according to the normal control map L6 shown by the two-dot chain line in FIG. 16 and the actual rotation speed of the prime mover 6. In addition, when the actual rotation speed of the prime mover 6 is lower than the target rotation speed but the drop amount is less than a predetermined third threshold, the control device 100 determines the current value of the control signal of the traveling solenoid valve 72 according to the normal control map L6 and the actual rotation speed of the prime mover 6. Then, the control device 100 inputs the control signal of the determined current value to the traveling solenoid valve 72 to open the traveling solenoid valve 72, set the opening degree of the traveling solenoid valve 72 to a predetermined opening degree, and set the primary pressure of the multiple traveling operation valves 56 to a predetermined magnitude.

[0194] In this state, when the travel operating member 55 is operated in any direction, one of the multiple travel operating valves 56 that corresponds to the operating direction of the travel operating member 55 is actuated, and pilot pressure is applied to the pump pressure receiving portions 50a, 50b of the corresponding travel pumps 50 (first travel pump 50L, second travel pump 50R) from the actuated travel operating valve 56. As a result, hydraulic oil is supplied from the corresponding travel pump 50 to the travel motor 51, which actuates the travel motor 51, which actuates the travel device 5, and the work machine 1 travels.

[0195] On the other hand, when the actual rotation speed of the prime mover 6 drops below the target rotation speed and the drop amount becomes equal to or greater than the third threshold value, the control device 100 determines the current value of the control signal for the traveling solenoid valve 72 according to the drop control map L7 shown by the solid line in Fig. 16 and the actual rotation speed of the prime mover 6, and inputs the control signal of the determined current value to the traveling solenoid valve 72. The current value of the control signal for the traveling solenoid valve 72 shown in the drop control map L7 is smaller than the current value of the control signal for the traveling solenoid valve 72 shown in the normal control map L6.

[0196] Therefore, when the control device 100 inputs a control signal of a current value determined according to the drop time control map L7 and the actual rotation speed of the prime mover 6 to the traveling solenoid valve 72, the opening of the traveling solenoid valve 72 becomes smaller, and the primary pressure of the multiple traveling operation valves 56 becomes lower than normal and is limited to a predetermined magnitude. Then, even if the traveling operation valve 56 operates in response to the operation of the traveling operation member 55, the pilot pressure (secondary pressure) acting on the pump pressure receiving parts 50a, 50b of the corresponding traveling pump 50 from the traveling operation valve 56 is limited (reduced) compared to normal, and the output (discharge amount of hydraulic oil) of the corresponding traveling pump 50 is also limited (reduced). In addition, the output of the traveling motor 51 is also limited.

[0197] That is, the control device 100 performs anti-stall control to prevent an unintended stop of the prime mover 6 by limiting the output from the travel pump 50 to the travel motor 51. Stall control is sometimes called running anti-stall control.

[0198] When the traveling anti-stall control and at least one of the AUX anti-stall control and the working anti-stall control are executed in parallel by the control device 100, the third threshold value of the drop amount for executing the traveling anti-stall control and the first and second threshold values ​​of the drop amount for executing at least one of the AUX anti-stall control and the working anti-stall control are set to different values. As a result, the timing at which the traveling anti-stall control is started differs from the timing at which at least one of the AUX anti-stall control and the working anti-stall control is started.

[0199] Also, the third threshold may be set to a value smaller than the first threshold (for example, the third threshold=50 rpm, the first threshold=200 rpm, etc.). With this, when a load is applied to the prime mover 6, the actual rotation speed of the prime mover 6 falls below the target rotation speed and the drop amount becomes equal to or greater than the third threshold, the traveling anti-stall control is started, and when the actual rotation speed of the prime mover 6 subsequently falls further below the target rotation speed and the drop amount becomes equal to or greater than the first threshold, at least one of the AUX anti-stall control and the working anti-stall control is started.

[0200] As another example, instead of the travel solenoid valve 72 in Fig. 15, a plurality of travel solenoid valves may be provided in the plurality of travel oil passages 42a, 42b, 42c, 42d, respectively. In this case, the control device 100 changes the current value of the control signal input to each of the plurality of travel solenoid valves based on the target rotation speed, actual rotation speed, and control maps L6, L7 of the prime mover 6, thereby changing the pilot pressure acting on the pump pressure receiving sections 50a, 50b of the travel pump 50, and controlling or limiting the output from the travel pump 50 to the travel motor 51.

[0201] As another example, as shown in Fig. 17, a solenoid valve 73 may be provided in the discharge oil passage 40 upstream (on the pilot pump P1 side) of each branch point of the multiple branch oil passages 40a, 40b. The control device 100 may then change the primary pressure of the travel operation valve 56 and the primary pressure of the work operation valve 69 using the solenoid valve 73 to limit the output from the travel pump 50 to the travel motor 51 and limit the output from the work control valves 60A, 60B to the work actuators 14, 15. In this case, the control device 100 may control the current value of the control signal input to the solenoid valve 73 using any of the control maps L4, L5 shown in Fig. 14 and the control maps L6, L7 shown in Fig. 16.

[0202] 18, a solenoid valve 74 may be provided in the discharge oil passage 40 upstream of each of the branch points of the multiple branch oil passages 40a, 40b, 40c. The control device 100 may then use the solenoid valve 74 to change the primary pressure of the travel operation valve 56, the primary pressure of the work operation valve 69, and the primary pressure of the AUX solenoid valve 65 (the pilot pressure of the pilot oil flowing to the AUX solenoid valves 65A and 65B), respectively, to limit the output from the travel pump 50 to the travel motor 51 and the output from the control valves 60A, 60B, and 60C to the actuators 14, 15, and 27.

[0203] In this case, the control device 100 may control the current value of the control signal input to the solenoid valve 74 using any one of the control maps L4, L5 and the control maps L6, L7. The control device 100 may also control the current value of the control signal input to the AUX solenoid valve 65 using the control maps L1, L2, L3 shown in Figs. 6 and 8.

[0204] The magnitude of the load on the prime mover 6 changes depending on at least one of the conditions of the work machine 1, the work device 4, and the hydraulic oil. The magnitude of the load on the prime mover 6 also changes depending on the attachment 11 attached to the work device 4. Furthermore, the magnitude of the load on the prime mover 6 also changes when the control device 100 controls each part of the work machine 1 in response to input information. To become.

[0205] Therefore, the control device 100 may correct the high load control maps L3 and L5 according to at least any one of the state of the work implement 1, the state of the work implement 4, the state of the hydraulic oil, the attachment 11, and the input information. The control device 100 may also correct the high load control maps L3 and L5 after determining that the drop amount is equal to or greater than the first threshold value (step S31 in FIG. 7A: YES, step S49 in FIG. 13: YES) and before changing the current value of the control signal to the solenoid valves 65 and 71 (or the solenoid valves 73 and 74) (step S34 in FIG. 7B, step S52 in FIG. 13).

[0206] In addition, when, for example, the state of the work machine 1, the state of the work device 4, the state of the hydraulic oil, the attachment 11, and / or the input information meets predetermined conditions that further increase the load on the prime mover 6, the control device 100 may correct the high load control maps L3, L5 so as to further reduce the flow rate of hydraulic oil to the actuators 27, 14, 15.

[0207] Furthermore, when at least one of the state of the work implement 1, the state of the work implement 4, the state of the hydraulic oil, the attachment 11, and the input information meets a predetermined condition for ensuring the workability of the work implement 1, the control device 100 may correct the high load control maps L3, L5 so that the flow rate of the hydraulic oil to the actuators 27, 14, 15 is less likely to be reduced. A specific example of the correction of the high load control maps L3, L5 will be described below.

[0208] The control device 100 calculates the horsepower and output of the main pump P2 and the output from the AUX port 25 to the auxiliary actuator 27 of the auxiliary attachment 11 based on, for example, the angle of the swash plate of the main pump P2 detected by the swash plate angle sensor 105 and the pressure of hydraulic oil acting on the AUX port 25 detected by the AUX pressure sensors 106a, 106b. Next, the control device 100 calculates the horsepower consumption of the auxiliary actuator 27 from the horsepower and output of the main pump P2 and the output to the auxiliary actuator 27.

[0209] Then, the control device 100 may correct the high load control map L3 according to the horsepower consumption in the auxiliary actuator 27. In this case, for example, if the horsepower consumption is equal to or greater than a predetermined value, the control device 100 multiplies the high load control map L3 by a correction coefficient according to the horsepower consumption to correct the gradient of the high load control map L3 (the ratio of the increase in the current value of the control signal of the operating AUX solenoid valve to the increase in the rotation speed of the prime mover 6). At this time, the greater the horsepower consumption, the greater the load on the prime mover 6. Therefore, for example, the greater the horsepower consumption, the greater the gradient of the high load control map L3, so that the control device 100 may multiply the high load control map L3 by a larger correction coefficient (a value of 1 or more) to increase the gradient of the high load control map L3. In FIG. 19, an example of the high load control map L3t after the gradient correction in this case is shown by a dashed line.

[0210] Alternatively, if the horsepower consumption is equal to or greater than a predetermined value, the control device 100 shifts the high load control map L3 in at least one of the horizontal and vertical directions as shown in Figs. 20A to 20C. At this time, the control device 100 may shift the high load control map L3 in at least one of the horizontal and vertical directions as the horsepower consumption increases. Fig. 20A shows an example of a corrected high load control map L3u shifted in the increasing direction of the horizontal axis. Fig. 20B shows an example of a corrected high load control map L3v shifted in the decreasing direction of the vertical axis by a dashed line. Fig. 20C shows an example of a corrected high load control map L3w shifted in both the increasing direction of the horizontal axis and the decreasing direction of the vertical axis by a dashed line.

[0211] In addition, the control device 100 performs high load control in response to the supply pressure of hydraulic oil from the AUX port 25 to the auxiliary actuator 27 detected by the AUX pressure sensors 106a and 106b. The map L3 may be corrected. In this case, for example, if the supply pressure is equal to or higher than a predetermined value, the control device 100 multiplies the high load control map L3 by a correction coefficient corresponding to the supply pressure to correct the gradient of the high load control map L3 (see FIG. 19). At this time, the control device 100 may multiply the high load control map L3 by a larger correction coefficient as the supply pressure increases, thereby increasing the gradient of the high load control map L3. Alternatively, if the supply pressure is equal to or higher than a predetermined value, the control device 100 may shift the high load control map L3 in at least one of the horizontal and vertical directions (see FIGS. 20A to 20C). At this time, the control device 100 may increase the shift amount of the high load control map L3 in at least one of the horizontal and vertical directions as the supply pressure increases.

[0212] Furthermore, the control device 100 may correct the high load control map L3 in accordance with the amount of hydraulic oil supplied from the AUX port 25 to the auxiliary actuator 27. In this case, for example, as shown in Fig. 21, flow rate sensors 108a, 108b may be provided in the oil passages 64a, 64b, and the amount of hydraulic oil supplied from the AUX port 25 to the auxiliary actuator 27 may be detected by the flow rate sensors 108a, 108b.

[0213] Alternatively, the control device 100 may calculate the discharge pressure of the hydraulic oil from the main pump P2 based on the detection value of the rotation speed sensor 104 (the actual rotation speed of the prime mover 6) and the detection value of the swash plate angle sensor 105 (the angle of the swash plate of the main pump P2), and calculate the differential pressure between the discharge pressure of the hydraulic oil from the main pump P2 and the pressure of the hydraulic oil acting on the AUX port 25 based on the discharge pressure and the detection values ​​of the AUX pressure sensors 106a and 106b. Then, the control device 100 may calculate (detect) the amount of hydraulic oil supplied from the AUX port 25 to the auxiliary actuator 27 based on the differential pressure, the opening cross-sectional area of ​​the AUX port 25, a predetermined flow coefficient, and the density of the hydraulic oil.

[0214] Then, for example, if the supply amount is equal to or greater than a predetermined value, the control device 100 multiplies the high load control map L3 by a correction coefficient corresponding to the supply pressure to correct the gradient of the high load control map L3 (see FIG. 19). At this time, the control device 100 may multiply the high load control map L3 by a larger correction coefficient as the supply amount increases, thereby increasing the gradient of the high load control map L3. Alternatively, if the supply amount is equal to or greater than a predetermined value, the control device 100 may shift the high load control map L3 in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 20A to 20C). At this time, the control device 100 may increase the shift amount of the high load control map L3 in at least one of the directions of the horizontal axis and the vertical axis as the supply amount increases.

[0215] The control device 100 may also correct the high-load control map L3 in response to input information indicating the attachment 11 (attachment 11 attached to the working device 4) input through the input / output interface 111. For example, if the input information through the input / output interface 111 indicates that the attachment 11 is a predetermined attachment that is subjected to a high load, such as a mulcher 11b, the control device 100 may multiply the high-load control map L3 by a predetermined correction coefficient corresponding to the predetermined attachment to increase the slope of the high-load control map L3 (see FIG. 19). Alternatively, the control device 100 shifts the high-load control map L3 by a predetermined shift width corresponding to the predetermined attachment in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 20A to 20C).

[0216] 22, for example. The anti-stall priority setting screen G1 is a screen for inputting priority information indicating which of the following is to be prioritized: limiting the discharge rate of the travel pump 50 by the travel solenoid valve 72, i.e., travel anti-stall control, and limiting the flow rate of hydraulic oil to the auxiliary actuator 27 by the AUX solenoid valve 65, i.e., AUX anti-stall control.

[0217] On the anti-stall priority setting screen G1, when the AUX anti-stall key K1 is selected (operated) by the driver of the work machine 1 or the like, priority information indicating that the AUX anti-stall control has priority over the traveling anti-stall control is input from the input / output interface 111 to the control device 100. Also, when the traveling anti-stall key K2 is selected by the driver or the like, priority information indicating that the traveling anti-stall control has priority over the AUX anti-stall control is input from the input / output interface 111 to the control device 100.

[0218] Among the AUX anti-stall key K1 and the running anti-stall key K2, the selected key and the unselected key are displayed in different manners. In the example of Fig. 22, the fact that the AUX anti-stall key K1 is selected is indicated by surrounding the AUX anti-stall key K1 with a thick frame.

[0219] The control device 100 may correct the high-load control map L3 in accordance with the priority information inputted through the input / output interface 111. In particular, when the priority information inputted through the input / output interface 111 indicates that the AUX anti-stall control is prioritized over the traveling anti-stall control, the control device 100 multiplies the high-load control map L3 by a predetermined correction coefficient to increase the gradient of the high-load control map L3 (see FIG. 19). Alternatively, the control device 100 shifts the high-load control map L3 by a predetermined shift width in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 20A to 20C).

[0220] Furthermore, when the priority information input from the input / output interface 111 indicates that the driving anti-stall control has priority over the AUX anti-stall control, the control device 100 multiplies the high-load control map L3 by a predetermined correction coefficient (a value greater than 0 and less than 1) to reduce the slope of the high-load control map L3. In Fig. 23, an example of the high-load control map L3r after the slope correction in this case is shown by a dashed dotted line.

[0221] Alternatively, when the traveling anti-stall control has priority over the AUX anti-stall control, the control device 100 shifts the high-load control map L3 by a predetermined shift width in at least one of the horizontal and vertical directions. FIG. 24A shows an example of a corrected high-load control map L3x shifted in the decreasing direction of the horizontal axis by a dashed line. FIG. 24B shows an example of a corrected high-load control map L3y shifted in the increasing direction of the vertical axis by a dashed line. FIG. 24C shows an example of a corrected high-load control map L3z shifted in both the decreasing direction of the horizontal axis and the increasing direction of the vertical axis by a dashed line.

[0222] The control device 100 may also correct the high load control map L3 depending on whether the travel switching valve 57 (FIG. 2, etc.) is in a first state in which the rotation speed of the output shafts 51Lj, 51Rj of the travel motor 51 is in a first speed stage or a second state in which the rotation speed is in a second speed stage. In this case, for example, when the travel switching valve 57 is in the second state, the rotation speed of the output shafts 51Lj, 51Rj of the travel motor 51 is in the second speed stage and the load on the prime mover 6 increases further, so the control device 100 multiplies the high load control map L3 by a predetermined correction coefficient to increase the slope of the high load control map L3 (see FIG. 19). Alternatively, the control device 100 shifts the high load control map L3 by a predetermined shift width on at least one of the horizontal axis and the vertical axis (see FIGS. 20A to 20C).

[0223] Furthermore, the control device 100 may correct the high load control map L3 according to the temperature of the hydraulic oil detected by the temperature sensor 107. In this case, if the temperature of the hydraulic oil is equal to or lower than a predetermined value, the viscous resistance of the hydraulic oil increases, and the load on the prime mover 6 further increases. Therefore, the control device 100 increases the gradient of the high load control map L3, for example, by multiplying the high load control map L3 by a predetermined correction coefficient (see FIG. 19). Alternatively, the control device 100 shifts the high load control map L3 by a predetermined shift width in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 20A to 20C).

[0224] In addition, the control device 100 may determine the operation state (operation direction) of the travel operating member 55 from the pilot pressure of the pilot oil flowing through the travel oil passages 42a, 42b, 42c, and 42d detected by the travel pressure sensors 106g, 106h, 106i, and 106j, and correct the high load control map L3 according to the operation state.

[0225] For example, the control device 100 determines whether the working machine 1 is in a forward, reverse, or swing state based on the operation direction of the travel operation member 55, and corrects the high load control map L3 according to the determined state. In this case, if the working machine 1 is in a swing state, the load on the prime mover 6 is greater than when the working machine 1 is in a straight-ahead state, so the control device 100, for example, multiplies the high load control map L3 by a predetermined correction coefficient to increase the slope of the high load control map L3 (FIG. 19). Alternatively, the control device 100 shifts the high load control map L3 by a predetermined shift width in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 20A to 20C).

[0226] In addition, the control device 100 may determine the operation state (operation direction and operation amount) of the work operation member 68 from the pilot pressure of the pilot oil flowing through the work oil passages 46a, 46b, 46c, and 46d detected by the work pressure sensors 106c, 106d, 106e, and 106f, and correct the high load control map L3 according to the operation state.

[0227] For example, the control device 100 determines the elevation state of the working device 4 (boom 10) from, for example, the operation direction and amount of the work operation member 68, and corrects the high load control map L3 according to the elevation state. In this case, the higher the working device 4 (front end 10a of the boom 10) is elevated to, the greater the load on the prime mover 6 becomes, so the control device 100, for example, multiplies the high load control map L3 by a large correction coefficient to increase the slope of the high load control map L3 (see FIG. 19). Alternatively, the control device 100 shifts the high load control map L3 by a predetermined shift width in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 20A to 20C).

[0228] In addition to the above, the control device 100 may correct the high load control map L3 according to, for example, the traveling speed of the work machine 1, the rotation speed of the prime mover 6, the specifications (size, etc.) of the attachment 11, the specifications (rated output, etc.) of the attached actuator 27, and the specifications of the work machine 1.

[0229] In addition, the control device 100 may correct the high load control map L5 for the work anti-stall control, similarly to the high load control map L3. In FIG. 25, an example of the high load control maps L5t and L5r after the inclination correction is shown by a dashed line. In FIG. 26A, an example of the high load control maps L5u and L5x after the correction shifted in the horizontal axis direction is shown by a dashed line. In addition, in FIG. 26B, an example of the high load control maps L5v and L5y after the correction shifted in the vertical axis direction is shown by a dashed line. Furthermore, in FIG. 26C, an example of the high load control maps L3w and L5z after the correction shifted in both the horizontal axis direction and the vertical axis direction is shown by a dashed line.

[0230] Furthermore, the control device 100 may display an anti-stall priority setting screen G2, for example as shown in Fig. 27, via the input / output interface 111. The anti-stall priority setting screen G2 is a screen for inputting priority information indicating which of the traveling anti-stall control and the working anti-stall control (limitation of the flow rate of hydraulic oil to the working actuators 14, 15 by the working solenoid valve 71) is to be given priority.

[0231] In the anti-stall priority setting screen G2, the working anti-stall key K3 is selected. When the driving anti-stall key K2 is selected by the driver or the like, priority information indicating that the working anti-stall control has priority over the traveling anti-stall control is input to the control device 100 from the input / output interface 111. When the driving anti-stall key K2 is selected by the driver or the like, priority information indicating that the traveling anti-stall control has priority over the working anti-stall control is input to the control device 100 from the input / output interface 111. Correction of the high-load control map L5 by the control device 100 when such priority information is input is similar to the correction of the high-load control map L3 based on the priority information input through the anti-stall priority setting screen G1 described above, and therefore will not be described again (see FIG. 25 and FIG. 26A to FIG. 26C).

[0232] Furthermore, the control device 100 may display an anti-stall priority setting screen G3, for example, as shown in Fig. 28, via the input / output interface 111. The anti-stall priority setting screen G3 is a screen for inputting priority information indicating which of the AUX anti-stall control and the working anti-stall control is to be given priority.

[0233] When the AUX anti-stall key K1 is selected on the anti-stall priority setting screen G3, priority information indicating that the AUX anti-stall control has priority over the working anti-stall control is input to the control device 100 from the input / output interface 111. In this case, the control device 100 increases the gradient of the high-load control map L3 as described above (see FIG. 19), or shifts the high-load control map L3 in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 20A to 20C).

[0234] Furthermore, when the working anti-stall key K3 is selected, priority information indicating that the working anti-stall control has priority over the AUX anti-stall control is input to the control device 100 from the input / output interface 111. In this case, the control device 100 increases the gradient of the high-load control map L5 (see FIG. 25), or shifts the high-load control map L5 in at least one of the directions of the horizontal axis and the vertical axis (see FIGS. 26A to 26C).

[0235] Furthermore, the control device 100 may display an anti-stall setting screen G4, for example as shown in Fig. 29, via the input / output interface 111. The anti-stall setting screen G4 is a screen for manually setting the AUX anti-stall control, work anti-stall control, and traveling anti-stall control to any desired enabled or disabled state in the work machine 1. The anti-stall setting screen G4 is provided with alternative ON keys K1a, K2a, K3a and OFF keys K1b, K2b, K3b corresponding to the AUX anti-stall control, work anti-stall control, and traveling anti-stall control, respectively.

[0236] Among them, when the ON key K1a is selected, the control device 100 executes the AUX anti-stall control during high-load work as described above, and when the OFF key K1b is selected, the control device 100 does not execute the AUX anti-stall control even if the drop amount becomes equal to or greater than the first threshold or the second threshold during high-load work. Also, when the ON key K2a is selected, the control device 100 executes the work anti-stall control during high-load work as described above, and when the OFF key K2b is selected, the control device 100 does not execute the work anti-stall control even if the drop amount becomes equal to or greater than the first threshold during high-load work. Furthermore, when the ON key K3a is selected, the control device 100 executes the running anti-stall control as described above, and when the OFF key K3b is selected, the control device 100 does not execute the running anti-stall control even if the drop amount becomes equal to or greater than the third threshold.

[0237] The anti-stall setting screen G4 as described above allows a user such as a driver to arbitrarily set the work machine 1 to limit or ensure workability using the work unit 4U, workability using the attached attachments 11, 11b, and driving performance, respectively, thereby improving convenience.

[0238] Also, the control device 100 may automatically turn on (enable) / off (disable) the AUX anti-stall control, the work anti-stall control, and the traveling anti-stall control. Specifically, for example, the control device 100 selects an anti-stall control that is effective for preventing an unintended stop of the prime mover 6 from among the AUX anti-stall control, the work anti-stall control, and the traveling anti-stall control, based on at least any of information such as the traveling state of the work implement 1, the driving state of the work implement 4, the output state to the auxiliary actuator 27, and the type of the attachment 11 attached to the work implement 1. Then, the control device 100 may execute (ON, i.e., enable) only the selected anti-stall control. Alternatively, the control device 100 may select a performance to be secured from among the workability by the auxiliary attachments 11, 11b, the workability by the work implement 4, and the traveling performance, based on at least any of the above information, and execute only the anti-stall control that does not correspond to the selected performance.

[0239] In the above-described embodiment, an example has been shown in which the anti-stall control solenoid valves 65, 71 to 74 are proportional valves, but the anti-stall control solenoid valves (AUX solenoid valves, work solenoid valves, traveling solenoid valves, etc.) may be configured by other solenoid valves such as solenoid throttle valves and solenoid switching valves. Also, instead of the hydraulic work operation device 67 and traveling operation device 54, electric work operation devices and traveling operation devices having operating members such as joysticks may be used. Also, instead of the hydraulic work operation valve 69 and traveling operation valve 56, electromagnetic work operation valves and traveling operation valves may be used.

[0240] In the above-described embodiment, an example has been shown in which information indicating the attachment 11 and priority information for each anti-stall control are input via the input / output interface 111. However, in addition to this, information indicating the attachment 11, priority information for each anti-stall control, and on / off information for each anti-stall control may also be input to the control device 100 via, for example, a communications interface that communicates with a computer external to the work machine 1 or an operating member such as an operating switch which is hardware.

[0241] In the above-described embodiment, an example is shown in which the high load control maps L3 and L5 in which the current value of the control signal for the solenoid valves 65 and 71 changes proportionally and the slope changes once with respect to the change in the rotation speed of the prime mover 6, and the non-high load control maps L1, L2, and L4 in which the current value of the control signal for the solenoid valves 65 and 71 is constant are adopted. However, a high load control map in which the current value of the control signal for the solenoid valves 65 and 71 changes in a curved manner with respect to the change in the rotation speed of the prime mover 6, or a high load control map in which the slope is constant or changes multiple times, may be adopted. Also, a non-high load control map in which the current value of the control signal for the solenoid valves 65 and 71 changes regularly or irregularly with respect to the change in the rotation speed of the prime mover 6 may be adopted.

[0242] 11A and 11B, the control device 100 may execute not only the AUX anti-stall control but also the working anti-stall control and the running anti-stall control. Furthermore, the control device 100 may perform a moving average process of the amount of decrease in the actual rotation speed with respect to the target rotation speed of the prime mover 6, and may execute not only the AUX anti-stall control but also the working anti-stall control and the running anti-stall control.

[0243] The work machine 1 of the present embodiment described above has the configurations described in the following items and provides the following effects. [Item 1] The work machine 1 includes a main pump P2 that operates by the power of a prime mover 6 mounted on a machine body 2 to discharge hydraulic oil, a work unit 4U that includes a work device 4 and an attachment 11 attached to the work device 4 and performs work using the work device 4 and the attachment 11 by operating an actuator provided on at least one of the work device 4 and the attachment 11 with hydraulic oil, solenoid valves 65, 71, 73, 74 that change the flow rate of hydraulic oil to the actuators in response to an input control signal, a control device 100 that inputs a control signal to the solenoid valves 65, 71, 73, 74, an accelerator device 101 that inputs a target rotation speed of the prime mover 6, and a rotation speed sensor 104 that detects the actual rotation speed of the prime mover 6. When a predetermined work that places a high load on the prime mover 6 is being performed by the work unit 4U, and a drop amount that is a decrease amount of the actual rotation speed of the prime mover 6 from the target rotation speed becomes equal to or greater than a predetermined first threshold value, the control device 100 changes the control signal in response to the actual rotation speed to limit the flow rate of hydraulic oil to the actuators.

[0244] With the configuration of item 1 above, when a predetermined task that places a high load on the prime mover 6 is being performed in the work machine 1, if the amount of drop in the rotation speed of the prime mover 6 reaches or exceeds the first threshold, the flow rate of hydraulic oil to the actuator of the working unit 4U is restricted, thereby reducing the load on the prime mover 6 and preventing unintended stopping of the prime mover 6 due to a high load. Also, when a task that does not place a high load on the prime mover 6 is being performed, the flow rate of hydraulic oil to the actuator of the working unit 4U is not restricted, ensuring operability.

[0245] [Item 2] The work machine 1 described in item 1 above further includes an AUX port 25 which is a port through which hydraulic oil flows in and out of the auxiliary actuator 27 which is an actuator provided on the attachment 11, a pilot pump P1 which is operated by the power of the prime mover 6 to discharge pilot oil, and an AUX control valve 60C which has AUX pressure receiving portions 63a, 63b and controls the flow rate of hydraulic oil supplied to the auxiliary actuator 27 via the AUX port 25 in accordance with the pilot pressure which is the pressure of the pilot oil acting on the AUX pressure receiving portions 63a, 63b. The solenoid valves 65, 71, 73, 74 include an AUX solenoid valve 65 (first AUX solenoid valve 65A, second AUX solenoid valve 65B) that changes the flow rate of hydraulic oil from the AUX control valve 60C to the associated actuator 27 by changing the pilot pressure acting on the AUX pressure receiving parts 63a, 63b in accordance with a control signal input from the control device 100, and when a specified task is being performed by a specified attachment (accessory attachment) 11, 11b to which the associated actuator 27 is provided, the control device 100 changes the control signal in accordance with the actual rotational speed of the prime mover 6 to reduce the pilot pressure acting on the AUX pressure receiving parts 63a, 63b, thereby limiting the flow rate of hydraulic oil from the AUX control valve 60C to the associated actuator 27 when the drop amount becomes equal to or greater than a first threshold value with respect to the target rotational speed.

[0246] With the configuration of item 2 above, when a predetermined task that places a high load on the prime mover 6 is being performed, if the drop amount becomes equal to or greater than the first threshold, the flow rate of hydraulic oil to the auxiliary actuator 27 is restricted, making it possible to prevent unintended stopping of the prime mover 6 due to a high load. Also, when a task that does not place a high load on the prime mover 6 is being performed, the flow rate of hydraulic oil to the auxiliary actuator 27 is not restricted, making it possible to ensure operability using the auxiliary attachments 11, 11b, etc.

[0247] [Item 3] In the work machine 1 described in item 2 above, the control device 100 sets the current value of the control signal to the AUX solenoid valve 65 to a predetermined value when the control device 100 is performing another task (light load task or medium load task that does not place a high load on the prime mover 6) other than the predetermined task with the attachments 11 other than the predetermined attachments 11, 11b, and when the drop amount is not equal to or greater than the first threshold value even if the predetermined task is being performed with the predetermined attachments 11, 11b. In addition, when the control device 100 is performing the predetermined task with the predetermined attachments 11, 11b and the drop amount becomes equal to or greater than the first threshold value, the control device 100 reduces the current value of the control signal to the AUX solenoid valve 65 and reduces the flow rate of hydraulic oil to the auxiliary actuator 27, compared to when the control device 100 is performing the other task with the other attachments 11 and when the drop amount is not equal to or greater than the first threshold value during the predetermined task.

[0248] When other work that does not place a high load on the prime mover 6 is being performed due to the configuration of item 3 above. When a predetermined task that places a high load on the prime mover 6 is being performed and the drop amount is not equal to or greater than the first threshold, the flow rate of hydraulic oil to the auxiliary actuator 27 is not limited, so that workability with the auxiliary attachments 11, 11b, etc. can be ensured. Also, when a predetermined task is being performed and the drop amount becomes equal to or greater than the first threshold, the flow rate of hydraulic oil to the auxiliary actuator 27 is reduced, so that unintended stop of the prime mover 6 due to a high load can be prevented.

[0249] [Item 4] The work machine 1 described in any one of items 1 to 3 above further includes a pilot pump P1, and work control valves 60A, 60B (lift control valve 60A, tilt control valve 60B) which have work pressure receiving portions 61a, 61b, 62a, 62b and control the flow rate of hydraulic oil supplied to work actuators 14, 15 (lift cylinder 14, tilt cylinder 15) provided in the work device 4 in accordance with a pilot pressure, which is the pressure of pilot oil acting on the work pressure receiving portions 61a, 61b, 62a, 62b. The solenoid valves 65, 71, 73, 74 include a work solenoid valve 71 that changes the flow rate of hydraulic oil from the work control valves 60A, 60B to the work actuators 14, 15 by changing the pilot pressure acting on the work pressure receiving portions 61a, 61b, 62a, 62b in accordance with a control signal input from the control device 100, and when a specified task is being performed by the work device 4 and the attachment 11, the control device 100 changes the control signal in accordance with the actual rotational speed of the prime mover 6 to reduce the pilot pressure acting on the work pressure receiving portions 61a, 61b, 62a, 62b, thereby limiting the flow rate of hydraulic oil from the work control valves 60A, 60B to the work actuators 14, 15 when the drop amount becomes equal to or greater than one threshold value.

[0250] With the configuration of item 4 above, when a predetermined task that places a high load on the prime mover 6 is being performed, if the drop amount becomes equal to or greater than the first threshold, the flow rate of hydraulic oil to the work actuators 14, 15 is restricted, making it possible to prevent unintended stopping of the prime mover 6 due to a high load. Also, when a task that does not place a high load on the prime mover 6 is being performed, the flow rate of hydraulic oil to the work actuators 14, 15 is not restricted, making it possible to ensure operability by the work device 4 and the like.

[0251] [Item 5] In the work machine 1 described in item 4 above, the control device 100 sets the current value of the control signal to the work control valves 60A, 60B to a predetermined value when other work that does not involve a high load other than the predetermined work is being performed, and when the drop amount is not equal to or greater than the first threshold value even when the predetermined work is being performed. In addition, when the drop amount becomes equal to or greater than the first threshold value while the predetermined work is being performed, the control device 100 reduces the current value of the control signal to the work control valves 60A, 60B to reduce the flow rate of hydraulic oil to the work actuators 14, 15, compared to when other work is being performed and when the drop amount is not equal to or greater than the first threshold value during the predetermined work.

[0252] With the configuration of item 5 above, when other work that does not place a high load on the prime mover 6 is being performed, and when a predetermined work that places a high load on the prime mover 6 is being performed and the drop amount is not equal to or greater than the first threshold, the flow rate of hydraulic oil to the work actuators 14, 15 is not restricted, so workability by the work device 4 and the like can be ensured. In addition, when a predetermined work is being performed and the drop amount becomes equal to or greater than the first threshold, the flow rate of hydraulic oil to the work actuators 14, 15 is reduced, so that unintended stop of the prime mover 6 due to a high load can be prevented.

[0253] [Item 6] The work machine 1 described in any one of items 1 to 5 above is provided with an input device (input / output interface) 111 for inputting information indicating the attachment 11 attached to the work implement 4, and the control device 100 determines whether the work performed by the work unit 4U is a specified high-load work based on the information indicating the attachment.

[0254] With the configuration of item 6 above, when a predetermined task that places a high load on the prime mover 6 is being performed, if the decrease in the actual rotation speed of the prime mover 6 relative to the target rotation speed becomes equal to or greater than the first threshold value, the flow rate of hydraulic oil to the actuators 27, 14, 15 is reliably restricted, making it possible to prevent unintended stoppage of the prime mover 6. Furthermore, when a task that does not place a high load on the prime mover 6 is being performed, the flow rate of hydraulic oil to the actuators 27, 14, 15 is not reliably restricted, making it possible to ensure operability.

[0255] [Item 7] In the work machine 1 described in item 2 or 3 above, when the drop amount becomes equal to or greater than a predetermined second threshold (start-up threshold) that is greater than the first threshold until a predetermined time has elapsed since the start of a predetermined task, the control device 100 limits the flow rate of hydraulic oil to the actuators 27, 14, 15 by changing the control signal input to the solenoid valves 65, 71, 73, 74 in accordance with the actual rotation speed of the prime mover 6.

[0256] Due to the configuration of item 7 above, the flow rate of hydraulic oil to the actuators 27, 14, 15 is not restricted during and immediately after the actuators 27, 14, 15 are started up, so that the actuators 27, 14, 15 can be started up stably and work can be commenced.

[0257] [Item 8] The working machine 1 according to any one of items 1 to 7 above further includes a variable displacement travel pump 50 that operates by the power of the prime mover 6 and has pump pressure receivers 50a, 50b (forward pump pressure receiver 50a, reverse pump pressure receiver 50b) and changes the discharge amount of hydraulic oil depending on the pilot pressure, which is the pressure of the pilot oil acting on the pump pressure receivers 50a, 50b, a travel motor 51 that operates by the hydraulic oil discharged from the travel pump 50, a travel device 5 that operates by the output of the travel motor 51 to travel the machine body 2, and a travel solenoid valve 72 that changes the pilot pressure acting on the pump pressure receivers 50a, 50b in response to a control signal input from the control device 100. When the drop amount reaches a predetermined third threshold value different from the first threshold value during travel of the machine body 2 by the travel device 5, the control device 100 changes the control signal input to the travel solenoid valve 72 in response to the actual rotation speed of the prime mover 6, thereby limiting the discharge amount of hydraulic oil from the travel pump 50.

[0258] With the configuration of item 8 above, when a high load is applied to the prime mover 6 while the work machine 1 is traveling or working while traveling, and the drop amount becomes equal to or greater than the third threshold, the amount of hydraulic oil discharged from the travel pump 50 is restricted, so the output from the travel pump 50 to the travel motor 51 is also restricted, reducing the load on the prime mover 6 and preventing unintended stopping of the prime mover 6. In addition, since the third threshold is different from the first threshold, the timing for starting to restrict the amount of hydraulic oil discharged from the travel pump 50 differs from the timing for starting to restrict the flow rate of hydraulic oil to the actuators 27, 14, 15, so that the load on the prime mover 6 is not suddenly reduced, and it is possible to prevent the occurrence of a state such as hunting that makes the drive state of the prime mover 6 unstable.

[0259] [Item 9] The working machine 1 according to any one of items 1 to 7 above further includes a storage device 110 storing high load control maps L3 and L5 indicating the current value of the control signal to the solenoid valves 65, 71, 73, and 74 when a predetermined task is being performed and the drop amount is equal to or greater than the first threshold value. The high load control maps L3 and L5 indicate that the current value of the control signal decreases in proportion to the decrease in the rotation speed of the prime mover 6. The control device 100 determines the current value of the control signal based on the high load control maps L3 and L5 and the actual rotation speed of the prime mover 6, and inputs the control signal of the determined current value to the solenoid valves 65, 71, 73, and 74 to limit the flow rate of hydraulic oil to the actuators 27, 14, and 15 to a reduced value.

[0260] With the configuration of item 9 above, when a predetermined task is being performed and the drop amount becomes equal to or greater than the first threshold, control signals are input to the solenoid valves 65, 71, 73, 74 in accordance with the high load control maps L3, L5, making it possible to appropriately and easily reduce the flow rate of hydraulic oil to the actuators 27, 14, 15 and prevent unintended stoppage of the prime mover 6. In addition, it is also possible to prevent the flow rate of hydraulic oil to the actuators 27, 14, 15 from being excessively reduced, thereby preventing a decrease in the workability and operability (operational feeling) of the working unit 4U of the work machine 1 and the like.

[0261] [Item 10] In the work machine 1 described in item 9 above, the control device 100 gradually changes the current value of the control signal input to the solenoid valves 65, 71, 73, 74 at a predetermined speed so as to match the current value determined by the high load control maps L3, L5 and the actual rotation speed of the prime mover 6.

[0262] The configuration of item 10 above prevents the flow rate of hydraulic oil to the actuators 27, 14, 15 from being suddenly restricted (reduced), further preventing a decrease in the workability and operability of the working unit 4U.

[0263] [Item 11] In the work machine 1 described in item 9 or 10 above, the high load control maps L3, L5 indicate that the slope, which is the ratio of the increase in the current value of the control signal to the increase in the rotation speed of the prime mover 6, is greater when the current value of the control signal is in a second range C2 smaller than the first range C1 than when the current value of the control signal is in the first range C1, and when the drop amount becomes equal to or greater than the first threshold value during a specified operation, the control device 100 significantly changes the current value of the control signal in accordance with the actual rotation speed based on the high load control maps L3, L5 when the current value of the control signal is in the second range C2 rather than in the first range C1.

[0264] With the configuration of item 11 above, when the actual rotation speed of the prime mover 6 begins to drop (reduced) due to a high load, the amount of restriction on the flow rate of hydraulic oil to the actuators 27, 14, and 15 can be reduced to suppress a decrease in workability. Also, when the actual rotation speed of the prime mover 6 drops significantly due to a high load, the amount of restriction on the flow rate of hydraulic oil to the actuators 27, 14, and 15 can be increased to further prevent unintended stoppage of the prime mover 6.

[0265] [Item 12] In the work machine 1 described in any one of items 9 to 11 above, input devices 103, 111 (accessory operating device 103, input / output interface 111) are provided for inputting an instruction to change the flow rate of hydraulic oil to the actuators 27, 14, 15, and at least one non-high load control map L1, L2, L4 (control map L1, normal control maps L2, L4) indicating a constant current value of a control signal to the solenoid valves 65, 71, 73, 74 is stored in the memory device 110, and the control device 100 inputs a control signal of a constant current value indicated by the non-high load control map L1, L2, L4 corresponding to the actuators 27, 14, 15 to the solenoid valves 65, 71, 73, 74 when performing an operation other than the predetermined operation and when the drop amount is not equal to or greater than the first threshold value even if the predetermined operation is being performed, and shifts the non-high load control map L1, L2, L4 in a direction in which the current value of the control signal changes in accordance with the instruction inputted by the input device 103, 111.

[0266] With the configuration of item 12 above, when the working unit 4U is performing other work that does not place a high load on the prime mover 6, and when the working unit 4U is performing a predetermined work that places a high load on the prime mover 6 but the drop amount is not equal to or greater than the first threshold, control signals are input to the solenoid valves 65, 71, 73, 74 according to the non-high load control maps L1, L2, L4, and the flow rate of hydraulic oil to the actuators 27, 14, 15 can be set appropriately and easily, making it possible to stably perform the predetermined work or other work. In addition, the operator of the work machine 1 or the like can change the flow rate of hydraulic oil to the actuators 27, 14, 15 using the input devices 103, 111, improving convenience.

[0267] [Item 13] In the working machine 1 according to any one of items 9 to 12, the storage device 110 The normal control maps L2, L4 are stored which indicate a constant current value of the control signal to the solenoid valves 65, 71, 73, 74 when a specified task is being performed and the amount of drop is not equal to or greater than a first threshold value. The high load control maps L3, L5 indicate that the current value of the control signal decreases in proportion to a decrease in the rotation speed of the prime mover 6. The high load control maps L3, L5 and the normal control maps L2, L4 have coincidence points which indicate the same current value of the control signal at the same rotation speed of the prime mover 6. When a specified task is being performed and the amount of drop is equal to or greater than the first threshold value, the control device 100 shifts the high load control maps L3, L5 in the direction in which the rotation speed of the prime mover 6 changes so that the rotation speed at the coincidence point coincides with the actual rotation speed of the prime mover 6.

[0268] With the configuration of the above item 13, even if a predetermined work is being performed, when the drop amount is not equal to or greater than the first threshold, the control signal is input to the solenoid valves 65, 71, 73, 74 according to the normal control maps L2, L4, and the flow rate of hydraulic oil to the actuators 27, 14, 15 can be set appropriately and easily, and the predetermined work can be performed stably. Also, when the drop amount becomes equal to or greater than the first threshold during the predetermined work, the current value of the control signal to the solenoid valves 65, 71, 73, 74 can be reduced while keeping the reduction in the current value small according to the high load control maps L3s, L5s after the shift according to the actual rotation speed of the prime mover 6 at that time. Therefore, the flow rate of hydraulic oil to the actuators 27, 14, 15 is prevented from being suddenly reduced, and it is possible to suppress the operation of the actuators 27, 14, 15 from becoming unstable and the workability from being reduced.

[0269] [Item 14] In the work machine 1 described in any one of Items 9 to 13 above, the control device 100 corrects the high load control maps L3, L5 according to at least one of the state of the work machine 1, the state of the work implement 4, the state of the hydraulic oil, the attachment 11, and the input information.

[0270] The configuration of the above item 14 makes it possible to appropriately limit the flow rate of hydraulic oil to the actuators 27, 14, 15 depending on at least one of the state of the work machine 1, the state of the work device 4, the state of the hydraulic oil, the attachment 11, and the input information, thereby preventing unintended stoppage of the prime mover 6 and deterioration of the workability of the work machine 1.

[0271] [Item 15] In the work machine 1 described in Item 14 above, when at least any one of the state of the work machine 1, the state of the work device 4, the state of the hydraulic oil, the attachment 11, and the input information meets predetermined conditions that further increase the load on the prime mover 6, the control device 100 corrects the high load control maps L3, L5 so that the flow rate of hydraulic oil to the actuators 27, 14, 15 is further reduced.

[0272] By configuring item 15 above, the flow rate of hydraulic oil to the actuators 27, 14, and 15 can be appropriately limited in accordance with the corrected high-load control maps L3t, L3u, L3v, L3w, L5t, L5u, L5v, and L5w, thereby further preventing unintended stoppage of the prime mover 6 due to high load.

[0273] [Item 16] In the work machine 1 described in Item 14 above, when at least any one of the state of the work machine 1, the state of the work device 4, the state of the hydraulic oil, the attachment 11, and the input information meets specified conditions for ensuring the operability of the work machine 1, the control device 100 corrects the high load control maps L3, L5 so that the flow rate of hydraulic oil to the actuators 27, 14, 15 is less likely to be reduced.

[0274] By configuring item 16 above, the flow rate of hydraulic oil to the actuators 27, 14, 15 is appropriately limited in accordance with the corrected high-load control maps L3r, L3x, L3y, L3z, L5r, L5x, L5y, L5z, thereby preventing unintended stoppage of the prime mover 6 due to high load while further preventing a decrease in the operability of the work machine 1.

[0275] [Item 17] The work machine 1 described in any one of Items 14 to 16 above further includes a swash plate angle sensor 105 for detecting the angle of a swash plate of the variable displacement main pump P2, an AUX port 25 for feeding hydraulic oil to and from an auxiliary actuator 27, which is an actuator provided on the attachments 11 and 11b, and AUX pressure sensors 106a, 106b for detecting the pressure of the hydraulic oil acting on the AUX port 25. The control device 100 calculates the horsepower consumed by the auxiliary actuator 27 based on the detection value of the swash plate angle sensor 105 and the detection values ​​of the AUX pressure sensors 106a, 106b, and corrects the high load control maps L3, L5 in accordance with the horsepower consumed.

[0276] By the configuration of item 17 above, the flow rate of hydraulic oil to the actuators 27, 14, and 15 can be appropriately limited according to the horsepower consumed in the auxiliary actuator 27, thereby preventing unintended stopping of the prime mover 6 due to high load and a decrease in the workability of the work machine 1.

[0277] [Item 18] In the work machine 1 described in any one of Items 14 to 17 above, an AUX port 25 and AUX pressure sensors 106a, 106b are further provided, and the control device 100 corrects the high load control maps L3, L5 in accordance with the pressure of hydraulic oil from the AUX port 25 to the auxiliary actuator 27 detected by the AUX pressure sensors 106a, 106b.

[0278] By the configuration of the above item 18, the flow rate of hydraulic oil to the actuators 27, 14, and 15 can be appropriately limited depending on the pressure of the hydraulic oil output to the auxiliary actuator 27, thereby preventing unintended stopping of the prime mover 6 due to high load and a decrease in the workability of the work machine 1.

[0279] [Item 19] In the work machine 1 described in any one of Items 14 to 18 above, an AUX port 25 is further provided, and the control device 100 corrects the high load control maps L3, L5 in accordance with the flow rate of hydraulic oil from the AUX port 25 to the auxiliary actuator 27 detected by the AUX pressure sensors 106a, 106b.

[0280] By the configuration of item 19 above, the flow rate of hydraulic oil to the actuators 27, 14, and 15 can be appropriately limited depending on the amount of hydraulic oil supplied to the auxiliary actuator 27, thereby preventing unintended stopping of the prime mover 6 due to high load and a decrease in the workability of the work machine 1.

[0281] [Item 20] In the work machine 1 described in any one of Items 14 to 19 above, an input device 111 is provided for inputting information indicating the attachment 11 attached to the work implement 4, and the control device 100 corrects the high load control maps L3, L5 in accordance with the information indicating the attachment 11 input by the input device 111.

[0282] By the configuration of the above item 20, the flow rate of hydraulic oil to the actuators 27, 14, 15 can be appropriately limited according to the attachment 11 mounted on the work device 4, thereby preventing unintended stopping of the prime mover 6 due to high load and deterioration of the workability of the work machine 1.

[0283] [Item 21] In the work machine 1 described in any one of Items 14 to 20 above, there are provided a variable displacement travel pump 50, a travel motor 51, a travel device 5, a travel solenoid valve 72 that limits the amount of hydraulic oil discharged from the travel pump 50 by changing the pilot pressure acting on the pump pressure receiving parts 50a, 50b in response to a control signal input from the control device 100, and an input device 111 for inputting priority information indicating which of the limitation of the discharge amount of the travel pump 50 by the travel solenoid valve 72 and the limitation of the flow rate of hydraulic oil to the actuators 27, 14, 15 by the solenoid valves 65, 71, 73, 74 is to be prioritized, and the control device 100 corrects the high load control maps L3, L5 in response to the priority information.

[0284] With the configuration of item 21 above, the flow rate of hydraulic oil to the actuators 27, 14, 15 can be appropriately limited depending on the desire of the driver or the like as to whether or not to prioritize work system anti-stall control (AUX anti-stall control, work anti-stall control) over traveling anti-stall control, thereby preventing unintended stoppage of the prime mover 6 due to high load and deterioration of the workability of the work machine 1.

[0285] [Item 22] In the work machine 1 described in any one of Items 14 to 21 above, the work machine 1 is equipped with an AUX port 25, a pilot pump P1, an AUX control valve 60C, work control valves 60A, 60B, and an input device 111, and the solenoid valves 65, 71, 73, 74 include an AUX solenoid valve 65 that limits the flow rate of hydraulic oil from the AUX control valve 60C to the auxiliary actuator 27 by changing the pilot pressure acting on the AUX pressure receiving portions 63a, 63b of the AUX control valve 60C in accordance with a control signal input from the control device 100, and work solenoid valves 71, 73 that limit the flow rate of hydraulic oil from the work control valves 60A, 60B to the work actuators 14, 15 by changing the pilot pressure acting on the work pressure receiving portions 61a, 61b, 62a, 62 of the work control valves 60A, 60B in accordance with a control signal input from the control device 100. The input device 111 is capable of inputting priority information indicating which of the limitation of the hydraulic oil flow rate by the AUX solenoid valve 65 and the limitation of the hydraulic oil flow rate by the work solenoid valves 71, 73 is to be prioritized, and the control device 100 corrects the high load control maps L3, L5 in accordance with the priority information.

[0286] With the configuration of item 22 described above, the flow rate of hydraulic oil to the actuators 27, 14, 15 can be appropriately limited according to the desires of the driver or the like to prioritize between AUX anti-stall control and working anti-stall control, thereby preventing unintended stoppage of the prime mover 6 due to high load and deterioration of the operability of the work machine 1.

[0287] [Item 23] The work machine 1 described in any one of Items 14 to 22 above further includes a travel switching valve 57 that can switch the rotation speeds of the travel pump 50, the travel motor 51, and the output shafts 51Lj, 51Rj of the travel motor 51 between a first state in which the rotation speeds are set to a first speed stage and a second state in which the rotation speeds are set to a second speed stage higher than the first speed stage, and the control device 100 corrects the high load control maps L3, L5 depending on whether the travel switching valve 57 is in the first state or the second state.

[0288] With the configuration of item 23 above, during a specified operation in which a high load is placed on the prime mover 6, the flow rate of hydraulic oil to the actuators 27, 14, 15 can be appropriately restricted in accordance with the gear stage of the travel motor 51 at which the load changes, thereby preventing unintended stopping of the prime mover 6 and a decrease in the operability of the work machine 1.

[0289] [Item 24] In the work machine 1 described in any one of Items 14 to 23 above, a temperature sensor 107 is further provided for detecting the temperature of the hydraulic oil, and the control device 100 corrects the high load control maps L3 and L5 according to the temperature detected by the temperature sensor 107.

[0290] By the configuration of item 24 above, the flow rate of hydraulic oil to the actuators 27, 14, 15 can be appropriately limited in accordance with the viscous resistance that depends on the temperature of the hydraulic oil, thereby preventing unintended stopping of the prime mover 6 and a decrease in the operability of the work machine 1.

[0291] [Item 25] The working machine 1 described in any one of Items 14 to 24 above further comprises a pair of traveling devices 5 (first traveling device 5, second traveling device 5) provided on the left and right sides of the body 2, and a traveling operation member 55 which is operated to a forward position, a reverse position, and a turning position, respectively, in order to move the body 2 forward, backward, and turning using the pair of traveling devices 5, and the control device 100 corrects the high load control maps L3, L5 according to the operating state of the traveling operation member 55.

[0292] By the configuration of the above item 25, the load on the prime mover 6 changes depending on the forward and rearward positions of the work machine 1. By appropriately limiting the flow rate of hydraulic oil to the actuators 27, 14, 15 depending on the traveling state, such as the forward position and the turning position, it is possible to prevent unintended stopping of the prime mover 6 and a decrease in the workability of the work machine 1.

[0293] [Item 26] The work machine 1 described in any one of Items 14 to 25 above further includes a work operation member 68 that is operated to operate the work device 4, and the control device 100 corrects the high load control maps L3 and L5 according to the operation state of the work operation member 68.

[0294] By the configuration of the above item 26, the flow rate of hydraulic oil to the actuators 27, 14, 15 can be appropriately limited depending on the operating state of the work implement 4, such as lifting, lowering, and tilting, which changes the load on the prime mover 6, thereby preventing unintended stoppage of the prime mover 6 and deterioration of the workability of the work machine 1.

[0295] [Item 27] ​​In the work machine 1 described in any one of items 1 to 26 above, the control device 100 generates an accelerator pseudo signal Jf that changes at a predetermined speed based on an accelerator signal Ja input from the accelerator device 101, determines a pseudo rotation speed of the prime mover 6 based on the accelerator pseudo signal Jf, and changes the control signal to the solenoid valves 65, 71, 73, 74 in accordance with the pseudo rotation speed instead of the actual rotation speed of the prime mover 6.

[0296] With the configuration of item 27 above, even if the accelerator operating member of the accelerator device 101 is operated suddenly and significantly while the prime mover 6 is running and not under a high load, causing a temporary large deviation between the actual rotation speed and the target rotation speed of the prime mover 6, the AUX anti-stall control and the work anti-stall control can be appropriately executed, thereby preventing a decrease in the workability of the work machine 1.

[0297] [Item 28] In the work machine 1 described in items 1 to 27 above, when the target rotation speed suddenly changes by more than a predetermined value due to the accelerator device 101 while a specified task is being performed by the work unit 4U, the control device 100 calculates the amount of decrease in the actual rotation speed relative to the target rotation speed multiple times in a specified period of time, and calculates the average value of the decrease amounts calculated multiple times as the drop amount.

[0298] With the configuration of item 28 above, even if a sudden and significant operation of the accelerator device causes the target rotation speed of the prime mover 6 to suddenly rise and the actual rotation speed to temporarily fall significantly below the target rotation speed, or the target rotation speed to suddenly fall and the actual rotation speed to temporarily rise significantly above the target rotation speed, the AUX anti-stall control and the working anti-stall control are each appropriately executed and continued, preventing unintended stoppage of the prime mover 6 and suppressing deterioration of workability. Furthermore, when at least one of the configurations of items 27 and 28 above is applied to changing the control signal to the solenoid valve 72, the traveling anti-stall control is appropriately executed and continued, preventing unintended stoppage of the prime mover 6 and suppressing deterioration of the travelling performance of the work machine 1.

[0299] Although the present invention has been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0300] 1 Work equipment 2. Aircraft 4 Work equipment 4U Work Unit 5 Running gear 6 Prime Mover 11 Attachment 11a Bucket (attachment) 11b Mulcher (attachment, accessory attachment) 14 Lift cylinder (actuator, working actuator) 15 Tilt cylinder (actuator, working actuator) 25 AUX port 27 Attached actuator (actuator) 50 Travel pump 50a, 50b (pump pressure receiving part) 51 Travel motor 51Lj, 51Rj output shaft 55 Travel control member 57 Travel changeover valve 60A Lift control valve, Work control valve 60B Tilt control valve, work control valve 60C AUX control valve 61a, 61b, 62a, 62b Working pressure receiving part 63a, 63b AUX pressure receiving part 65 AUX solenoid valve (solenoid valve) 68 Operation operation parts 71 Working solenoid valve (solenoid valve) 72 Travel solenoid valve 100 Control device 101 Accelerator 104 RPM sensor 105 Swash plate angle sensor 106a, 106b AUX pressure sensor 107 Temperature Sensor 110 Storage device 111 Input / Output Interface (Information Input Device) Am constant value Ar Limit current value (current value) C1 1st range C2 2nd range Ja Accelerator signal Jf Accelerator pseudo signal L1 control map (non-high load control map) L2, L4 Normal control map (non-high load control map) L3, L5 high load control map P1 Pilot pump P2 Main pump Rc Actual rotation speed Rf Pseudo rotation speed Rt Target RPM

Claims

1. A main pump that is operated by the power of a prime mover mounted on the aircraft and discharges hydraulic oil; a working unit including a working device and an attachment attached to the working device, the working device and the attachment being operated by an actuator provided on at least one of the working device and the attachment using the hydraulic oil to perform a work; a solenoid valve that changes the flow rate of the hydraulic oil to the actuator in response to an input control signal; a control device that inputs the control signal to the solenoid valve; an accelerator device for inputting a target rotation speed of the prime mover; A rotation speed sensor for detecting an actual rotation speed of the prime mover, The control device, when a drop amount, which is the amount by which the actual rotational speed of the prime mover decreases from the target rotational speed, becomes equal to or greater than a predetermined first threshold value while the work unit is performing a specified task that places a high load on the prime mover, limits the flow rate of hydraulic oil to the actuator by changing the control signal in accordance with the actual rotational speed.

2. an AUX port that is a port through which the hydraulic oil flows in and out of an auxiliary actuator that is the actuator provided on the attachment; A pilot pump that is operated by the power of the prime mover and discharges pilot oil; an AUX control valve having an AUX pressure receiving portion and controlling a flow rate of the hydraulic oil supplied to the auxiliary actuator through the AUX port in response to a pilot pressure which is the pressure of the pilot oil acting on the AUX pressure receiving portion; the solenoid valve includes an AUX solenoid valve that changes the pilot pressure acting on the AUX pressure receiving portion in response to the control signal input from the control device, thereby changing the flow rate of the hydraulic oil from the AUX control valve to the auxiliary actuator, 2. The work machine according to claim 1, wherein when the drop amount becomes equal to or greater than the first threshold value while the specified work is being performed by a specified attachment provided with the auxiliary actuator, the control device changes the control signal in accordance with the actual rotational speed of the prime mover, thereby reducing the pilot pressure acting on the AUX pressure receiving portion and limiting the flow rate of the hydraulic oil from the AUX control valve to the auxiliary actuator.

3. The control device includes: when an attachment other than the predetermined attachment is used to perform another task different from the predetermined task, and when the predetermined task is performed by the predetermined attachment but the drop amount is not equal to or greater than the first threshold value, a current value of the control signal to the AUX solenoid valve is set to a predetermined value; 3. The work machine according to claim 2, wherein when the predetermined work is being performed with the predetermined attachment, the flow rate of the hydraulic oil to the auxiliary actuator is reduced by reducing a current value of the control signal to the AUX solenoid valve compared to when the other work is being performed with the other attachment and when the drop amount is not equal to or greater than the first threshold during the predetermined work.

4. A pilot pump that is operated by the power of the prime mover and discharges pilot oil; a work control valve having a work pressure receiving portion and controlling a flow rate of the hydraulic oil supplied to a work actuator provided in the work device in response to a pilot pressure which is a pressure of the pilot oil acting on the work pressure receiving portion, the solenoid valve includes a work solenoid valve that changes the pilot pressure acting on the work pressure receiving portion in response to the control signal input from the control device, thereby changing a flow rate of the hydraulic oil from the work control valve to the work actuator, 2. The work machine according to claim 1, wherein when the specified work is being performed by the work device and the attachment, when the drop amount becomes equal to or greater than the first threshold value, the control device changes the control signal in accordance with the actual rotational speed of the prime mover, thereby reducing the pilot pressure acting on the work pressure receiving portion and restricting the flow rate of the hydraulic oil from the work control valve to the work actuator.

5. The control device includes: When the predetermined work is being performed and the drop amount is not equal to or greater than the first threshold value, the current value of the control signal to the work solenoid valve is set to a predetermined value; 5. The work machine according to claim 4, wherein when the drop amount becomes equal to or greater than the first threshold value while the specified work is being performed, the current value of the control signal to the work solenoid valve is reduced to reduce the flow rate of the hydraulic oil to the work actuator, compared to when the other work is being performed and when the drop amount is not equal to or greater than the first threshold value during the specified work.

6. an input device for inputting information indicating the attachment attached to the working device; The work machine according to claim 1 , wherein the control device determines whether or not the work performed by the work unit is the predetermined work that imposes a high load, based on the information indicating the attachment.

7. The work machine according to claim 2, wherein the control device limits the flow rate of the hydraulic oil to the actuator by changing the control signal input to the solenoid valve in accordance with the actual rotation speed of the prime mover when the drop amount reaches a predetermined second threshold value that is greater than the first threshold value until a predetermined time has elapsed since the start of the specified work.

8. a variable displacement travel pump that is operated by the power of the prime mover, has a pump pressure receiving portion, and a discharge amount of hydraulic oil is changed by a pilot pressure that is the pressure of pilot oil acting on the pump pressure receiving portion; a travel motor that is operated by the hydraulic oil discharged by the travel pump; a traveling device that operates by the output of the traveling motor to cause the machine body to travel; a traveling solenoid valve that changes the pilot pressure acting on the pump pressure receiving portion in response to a control signal input from the control device, The work machine according to claim 1, wherein when the drop amount becomes equal to or greater than a predetermined third threshold value different from the first threshold value while the machine body is traveling by the traveling device, the control device limits the amount of hydraulic oil discharged from the traveling pump by changing the control signal input to the traveling solenoid valve in accordance with the actual rotational speed of the prime mover.

9. a storage device that stores a high-load control map indicating a current value of the control signal to the solenoid valve when the predetermined work is being performed and the drop amount becomes equal to or greater than the first threshold value; the high load control map indicates that the current value of the control signal decreases in proportion to a decrease in the rotation speed of the prime mover, The work machine described in claim 1, wherein the control device determines a current value of the control signal based on the high load control map and the actual rotation speed of the prime mover, and inputs the control signal of the determined current value to the solenoid valve, thereby reducing and limiting the flow rate of the hydraulic oil to the actuator.

10. The work machine according to claim 9, wherein the control device gradually changes the current value of the control signal input to the solenoid valve at a predetermined speed so as to match the current value determined by the high load control map and the actual rotation speed of the prime mover.

11. the high load control map indicates that a slope, which is a ratio of an increase in the current value of the control signal to an increase in the rotation speed of the prime mover, is greater when the current value of the control signal is in a second range that is smaller than the first range than when the current value of the control signal is in a first range; The work machine according to claim 9, wherein when the drop amount becomes equal to or greater than the first threshold value during the specified work, the control device significantly changes the current value of the control signal in accordance with the actual rotation speed when the current value of the control signal is in the second range more than when it is in the first range, based on the high load control map.

12. an input device for inputting an instruction to change the flow rate of the hydraulic oil to the actuator; the storage device stores at least one non-high load control map indicating a constant current value of the control signal to the solenoid valve; 10. The work machine according to claim 9, wherein the control device inputs the control signal of the constant current value indicated in the non-high load control map corresponding to the actuator to the solenoid valve when the work other than the specified work is being performed and when the specified work is being performed but the drop amount is not equal to or greater than the first threshold value, and shifts the non-high load control map in a direction in which the current value of the control signal changes in accordance with the instruction input by the input device.

13. the storage device stores a normal control map indicating a constant current value of the control signal to the solenoid valve when the predetermined task is being performed and the drop amount is not equal to or greater than the first threshold value; the high load control map indicates that the current value of the control signal decreases in proportion to a decrease in the rotation speed of the prime mover, The high-load control map and the normal control map have a matching point that indicates the same current value of the control signal at the same rotation speed of the prime mover, The work machine according to claim 9, wherein the control device, when performing the specified work and when the drop amount becomes equal to or greater than the first threshold value, shifts the high load control map in a direction in which the rotation speed of the prime mover changes so that the rotation speed of the coincidence point coincides with the actual rotation speed of the prime mover.

14. The work machine according to claim 9 , wherein the control device corrects the high load control map in response to at least one of a state of the work machine, a state of the work device, a state of the hydraulic oil, the attachment, and input information.

15. The work machine according to claim 14, wherein the control device corrects the high load control map so as to further reduce the flow rate of the hydraulic oil to the actuator when at least one of the state of the work machine, the state of the work device, the state of the hydraulic oil, the attachment, and input information meets predetermined conditions that further increase the load on the prime mover.

16. The control device corrects the high-load control map so that the flow rate of the hydraulic oil to the actuator is less likely to be reduced when at least one of the state of the work machine, the state of the work device, the state of the hydraulic oil, the attachment, and input information meets specified conditions for ensuring the operability of the work machine.

17. a swash plate angle sensor that detects the angle of a swash plate of the variable displacement main pump; an AUX port through which the hydraulic oil flows to and from an auxiliary actuator, which is the actuator provided on the attachment; an AUX pressure sensor that detects the pressure of the hydraulic oil acting on the AUX port; The work machine according to claim 14, wherein the control device calculates horsepower consumption in the auxiliary actuator based on the detection value of the swash plate angle sensor and the detection value of the AUX pressure sensor, and corrects the high-load control map in accordance with the horsepower consumption.

18. an AUX port through which the hydraulic oil flows to and from an auxiliary actuator, which is the actuator provided on the attachment; an AUX pressure sensor that detects the pressure of the hydraulic oil acting on the AUX port; The work machine according to claim 14, wherein the control device corrects the high load control map in accordance with the pressure of the hydraulic oil from the AUX port to the auxiliary actuator, detected by the AUX pressure sensor.

19. an AUX port through which the hydraulic oil flows to and from an auxiliary actuator, which is the actuator provided on the attachment; The work machine according to claim 14, wherein the control device detects a flow rate of the hydraulic oil from the AUX port to the auxiliary actuator, and corrects the high load control map in accordance with the flow rate.

20. an input device for inputting information indicating an attachment attached to the working device; The work machine according to claim 14, wherein the control device corrects the high load control map in accordance with the information indicating the attachment.

21. a variable displacement travel pump that is operated by the power of the prime mover, has a pump pressure receiving portion, and a discharge amount of hydraulic oil is changed by a pilot pressure that is the pressure of pilot oil acting on the pump pressure receiving portion; a travel motor that is operated by the hydraulic oil discharged by the travel pump; a traveling device that operates by the output of the traveling motor to cause the machine body to travel; a travel solenoid valve that changes the pilot pressure acting on the pump pressure receiving portion in response to a control signal input from the control device, thereby limiting the discharge amount of the hydraulic oil from the travel pump; an input device for inputting priority information indicating which of the limiting of the discharge amount of the traveling pump by the traveling solenoid valve and the limiting of the flow rate of the hydraulic oil to the actuator by the solenoid valve is to be prioritized, The work machine according to claim 14, wherein the control device corrects the high load control map in accordance with the priority information.

22. an AUX port through which the hydraulic oil flows to and from an auxiliary actuator, which is the actuator provided on the attachment; A pilot pump that is operated by the power of the prime mover and discharges pilot oil; an AUX control valve having an AUX pressure receiving portion and controlling a flow rate of the hydraulic oil supplied to the auxiliary actuator via the AUX port in response to a pilot pressure which is the pressure of the pilot oil acting on the AUX pressure receiving portion; a work control valve having a work pressure receiving portion and controlling a flow rate of the hydraulic oil supplied to a work actuator provided in the work device in response to the pilot pressure acting on the work pressure receiving portion; An input device, The solenoid valve is an AUX solenoid valve that limits a flow rate of the hydraulic oil from the AUX control valve to the auxiliary actuator by changing the pilot pressure acting on the AUX pressure receiving portion of the AUX control valve in response to a control signal input from the control device; a work solenoid valve that limits a flow rate of the hydraulic oil from the work control valve to the work actuator by changing the pilot pressure acting on the work pressure receiving portion of the work control valve in response to a control signal input from the control device, the input device is capable of inputting priority information indicating which of the limiting of the flow rate of the hydraulic oil by the AUX solenoid valve and the limiting of the flow rate of the hydraulic oil by the work solenoid valve is to be prioritized, The work machine according to claim 14, wherein the control device corrects the high load control map in accordance with the priority information.

23. a travel pump that is operated by the power of the prime mover and discharges hydraulic oil; a travel motor having an output shaft and actuated by the hydraulic oil discharged by the travel pump to rotate the output shaft; a travel switching valve that can switch the rotation speed of the output shaft of the travel motor between a first state in which the rotation speed is a first speed stage and a second state in which the rotation speed is a second speed stage higher than the first speed stage, The work machine according to claim 14, wherein the control device corrects the high load control map depending on whether the travel changeover valve is in the first state or the second state.

24. A temperature sensor is provided to detect the temperature of the hydraulic oil. The work machine according to claim 14, wherein the control device corrects the high load control map in accordance with the temperature detected by the temperature sensor.

25. A pair of traveling devices provided on the left and right sides of the body; a travel operating member that is operated to a forward position, a reverse position, and a turning position, respectively, in order to move the vehicle forward, backward, and turning by the pair of traveling devices; The work machine according to claim 14, wherein the control device corrects the high load control map in accordance with an operation state of the travel operation member.

26. A work operation member is provided which is operated to operate the working device, The work machine according to claim 14, wherein the control device corrects the high load control map in accordance with an operation state of the work operation member.

27. 2. The work machine according to claim 1, wherein the control device generates an accelerator pseudo signal that changes at a predetermined speed based on an accelerator signal input from the accelerator device, determines a pseudo rotation speed of the prime mover based on the accelerator pseudo signal, and changes the control signal in accordance with the pseudo rotation speed instead of the actual rotation speed.

28. 2. The work machine according to claim 1, wherein when the target rotation speed is suddenly changed by the accelerator device by more than a predetermined value while the specified work is being performed by the work unit, the control device calculates the amount of reduction in the actual rotation speed relative to the target rotation speed a plurality of times within a predetermined period of time, and calculates the average value of the reduction amounts calculated a plurality of times as the drop amount.

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