Working machine and method for controlling working machine

Abstract

To enable an arm and a working tool to be sufficiently brought close to a boom side regardless of the attitude of the boom. [Solution] The work machine is equipped with a control device that, when rotating the boom in a direction away from the boom reference position, sets the stroke range of the arm cylinder toward the boom in accordance with the boom rotation position so that the shortest trajectory distance, which is the shortest distance between the rotation trajectory of the tip of the bucket and the boom cylinder, is maintained at a predetermined value even if the boom rotation position changes.

Description

[Technical field]

[0001] The present invention relates to a work machine such as a backhoe. [Background technology]

[0002] 2. Description of the Related Art A working machine disclosed in Patent Document 1 is known in the art. The work machine disclosed in Patent Document 1 is a backhoe that includes a machine body, a boom attached to the machine body, an arm supported on the boom so as to be able to swing freely, and a bucket attached to the tip of the arm. In this work machine, the boom, arm, and bucket can be swung by extending and retracting the boom cylinder, arm cylinder, and bucket cylinder, respectively. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-65569 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in conventional work machines such as that disclosed in Patent Document 1, the stroke range of the arm cylinder is set to a reference position where the boom cylinder is furthest from the underside of the boom toward the arm so as to prevent the bucket from colliding with the boom cylinder, and is set so that the bucket and boom cylinder do not collide at this reference position. However, if the stroke range of the arm cylinder is fixed within the range set for the reference position, the distance between the boom cylinder and the bucket when the boom is rotated away from the reference position becomes wider than the distance between the boom cylinder and the bucket at the reference position. This causes a problem that, depending on the posture of the boom, it may not be possible to move the arm and bucket sufficiently toward the boom, resulting in a large minimum turning radius.

[0005] SUMMARY OF THEINVENTION In view of the above problems, an object of the present invention is to provide a work machine that can bring an arm and a work tool sufficiently close to the boom side regardless of the attitude of the boom. [Means for solving the problem]

[0006] The working machine according to one aspect of the present invention comprises a machine body and a base end portion. Machine body a swing bracket attached to the front of the support bracket protruding forward from the front of the vehicle so as to be swingable about a vertical axis; a boom pivotally supported on the first rotation axis; , B Room The first A boom cylinder that rotates around one axis and a base end Gabu Tip of the arm Second an arm pivotally supported to be rotatable about a second axis of rotation parallel to the first axis of rotation; ,a Room The first An arm cylinder that rotates around two rotation axes ,a Tip of the arm Second The boom sensor detects a rotation position of the boom about the first rotation axis. , B Room Cylinder Gabu Located on one side of the frame ,a Room Cylinder Gabu The other side of the The boom is a one-piece boom having no joint between the base end and the tip end. It is a work machine ,a Room Wobu To the side closest to the room No.A The stroke range of the cylinder is , B Even if the rotation position of the arm changes , written by Tool tip The first Rotation orbit around three rotation axes Tobu The minimum distance between the track and the cylinder is kept constant at a specified value. Nibu The control device changes the rotational position of the arm. The control device rotates the boom while changing a stroke range of an arm cylinder according to a rotation position of the boom so as to keep the shortest path distance, which changes according to a rotation position of the boom, constant at the predetermined value. . Effect of the Invention

[0007] According to the above configuration, the arm and the work tool can be brought sufficiently close to the boom side regardless of the attitude of the boom. [Brief description of the drawings]

[0008] [Figure 1] FIG. [Diagram 2] FIG. 2 is a schematic diagram of a hydraulic system of the work machine. [Diagram 3] FIG. 4 is a side view of the work implement when the boom is in the boom reference position S1. [Figure 4] 1 is a side view of the working machine in a state in which the boom has been rotated upward from the boom reference position S1 while the stroke of the arm cylinder is kept constant. FIG. [Diagram 5] FIG. 1 is a side view of the working machine in a state in which the boom has been rotated upward from the boom reference position S1 while the stroke range of the arm cylinder is changed according to the boom rotation position so as to keep the distance between the rotation path of the working tool and the boom cylinder constant at a reference distance. [Figure 6] FIG. 6 is a side view of the working machine in a state where the boom has been rotated from the state in FIG. 5 in a direction approaching the boom reference position while the stroke of the arm cylinder is kept constant. [Figure 7] 10 is a side view of the work machine illustrating a method for setting the possible stroke range of the arm cylinder so that the distance between the tip of the bucket and the boom cylinder is equal to or greater than a reference distance. FIG. [Figure 8] FIG. 11 is a side view of a work machine illustrating a method for determining whether the pivoting position of the bucket is in a first range where the tip is positioned closer to the boom cylinder than a predetermined position, or in a second range where the tip is positioned farther from the boom cylinder (toward the dump truck). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Embodiment 1] An embodiment of the present invention will now be described. (1-1. Overall configuration of work machine 1) 1 is a schematic side view of a working machine 1 according to this embodiment. In this embodiment, a backhoe, which is a rotating working machine, is exemplified as the working machine 1.

[0010] As shown in Fig. 1, the work machine 1 includes a machine body (swivel base) 2, a traveling device 3, and a work device 4. A cabin 5 is mounted on the machine body 2. Inside the cabin 5, a driver's seat (seat) 6 is provided where a driver (operator) sits. In this embodiment, the front side of the driver seated in the driver's seat 6 of the work machine 1 (the direction of the arrow A1 in FIG. 1) will be described as the front, the rear side of the driver (the direction of the arrow A2 in FIG. 1) as the rear, the left side of the driver as the left side, and the right side of the driver as the right side. In addition, as shown in FIG. 1, the horizontal direction that is perpendicular to the front-rear direction K1 will be described as the machine body width direction (the width direction of the machine body 2).

[0011] As shown in Fig. 1, the traveling device 3 is a device that supports the machine body 2 so that it can travel. The traveling device 3 is driven by a traveling motor 11 that is configured with a hydraulic motor (hydraulic actuator) or an electric motor or the like. Note that, although a crawler-type traveling device 3 is used in this embodiment, this is not limiting, and a wheel-type traveling device or the like may also be used. A dozer device 7 is attached to the front of the traveling device 3. The dozer device 7 can raise and lower (raise and lower) a blade (blade) 74 by extending and contracting a dozer cylinder (hydraulic actuator) not shown.

[0012] The machine body 2 is supported on the traveling device 3 via a swivel bearing 8 so as to be rotatable about a swivel axis X1. The swivel axis X1 is an axis that extends in the vertical direction and passes through the center of the swivel bearing 8. A prime mover is mounted on the machine body 2. The prime mover is a diesel engine. The prime mover may be a gasoline engine, an LPG engine, or an electric motor, or may be a hybrid type having an engine and an electric motor.

[0013] The machine body 2 has a swivel base plate 9 that rotates around a rotation axis X1. The swivel base plate 9 is made of a steel plate or the like, and constitutes the bottom of the machine body 2. The prime mover is mounted on this swivel base plate 9. Vertical ribs 9L, 9R, which are reinforcing members, are provided on the center side of the upper surface of the swivel base plate 9 from the front to the rear. A weight 10 is provided at the rear of the aircraft body 2.

[0014] A support 20 that supports the working device 4 is provided at the front of the machine body 2. The support 20 has a support bracket 20A and a swing bracket 20B. The support bracket 20A is fixed to the front of the vertical ribs 9L, 9R, and is provided so as to protrude forward from the machine body 2. A swing bracket 20B is attached to the front of the support bracket 20A (the portion protruding from the machine body 2) via a swing shaft 21 so as to be swingable about a vertical axis. Therefore, the swing bracket 20B is rotatable in the machine body width direction K2 (horizontally around the swing shaft 21).

[0015] The swing bracket 20B is formed with a cylindrical first pivot part 23 provided on an upper part of the main body 22 and a cylindrical second pivot part 24 provided on a lower part of the main body 22. The working device 4 includes a boom device 30, an arm device 40, and a working implement device 50. The boom device 30 includes a boom 31 and a boom cylinder 32. The boom 31 includes a base 31A supported swingably (rotatably) via a horizontal shaft (first rotation shaft) 35 extending in the machine width direction K2 of the first pivotal support part 23 of the swing bracket 20B, a tip end 31B supporting the arm 41 swingably, and an intermediate part 31C provided between the base 31A and the tip end 31B. The intermediate part 31C is elongated along the longitudinal direction and bent downward at the middle part. A lower bracket 33 is provided on one side (lower side) of the bent part of the intermediate part 31C, and an upper bracket 34 is provided on the other side (upper side) of the bent part of the intermediate part 31C.

[0016] The boom cylinder 32 is an extendable hydraulic cylinder that swings (rotates) the boom 31, and includes a cylindrical cylinder portion 32A and a rod 32B whose one end is slidably inserted into the cylinder portion 32A. A guard member (cylinder guard) that prevents other objects from contacting the rod 32B and / or the cylinder portion 32A may be provided on the surface of the boom cylinder 32 on the arm 41 side (lower side). The base end of the boom cylinder 32 is swingably supported by a horizontal shaft (fourth rotation shaft) 36 of the second pivot portion 24, and the tip end of the boom cylinder 32 is swingably supported by a horizontal shaft 37 of the lower bracket 33. Therefore, the boom device 30 (boom 31) can rotate around the horizontal shaft 35 on the first pivot portion 23, and the boom device 30 (boom 31) can swing up or down.

[0017] The arm device 40 has an arm 41 and an arm cylinder 42. The arm 41 is elongated along the longitudinal direction. A base end of the arm 41 is supported to be freely swingable on the tip 31B of the boom 31 via a horizontal shaft (second rotation shaft) 43. An upper bracket 44 is provided on the upper surface side of the base end of the arm 41. The arm cylinder 42 is an extendable hydraulic cylinder that swings the arm 41. A base end of the arm cylinder 42 is supported so as to be freely swingable by the horizontal shaft 38 of the upper bracket 34 of the boom 31, and a tip end of the arm cylinder 42 is supported so as to be freely swingable by the horizontal shaft 46 of the upper bracket 44. Therefore, the arm device 40 (arm 41) is rotatable around the horizontal shaft 43 of the boom 31, and the arm device 40 (arm 41) is freely swingable in the upward or downward direction.

[0018] The work implement device 50 has a bucket 51 as a work implement, and a bucket cylinder 52 as a work implement cylinder. The bucket 51 is supported swingably on the tip of the arm 41 via a horizontal shaft (third rotation shaft) 57. A link mechanism 53 is provided between the bucket 51 and the tip of the arm 41. The bucket cylinder 52 is composed of an extendable hydraulic cylinder that swings the bucket 51. The base end of the bucket cylinder 52 is supported to be freely swingable by the horizontal shaft 48 of the upper bracket 44 of the arm 41, and the tip end of the bucket cylinder 52 is supported to be freely swingable by the horizontal shaft 56 of the link mechanism 53. Therefore, the implement device 50 (bucket 51) is provided on the tip side of the arm 41 so as to be capable of scooping and dumping operations. The scooping operation is an operation of swinging the tip end 58 of the bucket 51 in a direction (scooping direction) approaching the boom 31, for example, an operation for scooping up soil and sand. The dumping operation is an operation of swinging the tip end 58 of the bucket 51 in a direction (dumping direction) away from the boom 31, for example, an operation for dropping (discharging) the scooped up soil and sand.

[0019] The work machine 1 can be equipped with other working tools (hydraulic attachments) that can be driven by a hydraulic actuator, instead of or in addition to the bucket 51. Examples of other working tools include a hydraulic breaker, a hydraulic crusher, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, and a snow blower. (1-2. Configuration of hydraulic system and control system in work machine 1) FIG. 2 is a diagram showing a hydraulic system of the working machine 1 that operates the working device 4. As shown in FIG.

[0020] As shown in FIG. 2, the hydraulic system of the work machine 1 has a boom control valve 71, an arm control valve 72, a bucket control valve 73, a control device 60, control devices 19L, 19R, a boom angle sensor 91, an arm angle sensor 92, and a work tool angle sensor 93. The boom control valve 71, the arm control valve 72, and the bucket control valve 73 are connected via oil passages to the boom cylinder 32, the arm cylinder 42, and the bucket cylinder 52. In addition, the boom control valve 71, the arm control valve 72, and the bucket control valve 73 are connected via oil passages to a hydraulic pump P1 that discharges hydraulic oil.

[0021] The boom control valve 71, the arm control valve 72, and the bucket control valve 73 are, for example, electromagnetic three-position switching valves. Specifically, the boom control valve 71 can be switched to a first position 71A, a second position 71B, or a third position 71C by energizing or deenergizing a first solenoid 71D and a second solenoid 71E. When the boom control valve 71 is switched to the first position 71A, the boom cylinder 32 is extended by supplying and discharging hydraulic oil to and from the boom cylinder 32, and the boom 31 swings in the upward direction. On the other hand, when the boom control valve 71 is switched to the second position 71B, the boom cylinder 32 is contracted by supplying and discharging hydraulic oil to and from the boom cylinder 32, and the boom 31 swings in the downward direction.

[0022] The arm control valve 72 can be switched to a first position 72A, a second position 72B, or a third position 72C by energizing or deenergizing the first solenoid 72D and the second solenoid 72E. When the arm control valve 72 is switched to the first position 72A, the arm cylinder 42 is extended by supplying and discharging hydraulic oil to and from the arm cylinder 42, and the arm 41 swings backward and downward. On the other hand, when the arm control valve 72 is switched to the second position 72B, the arm cylinder 42 is contracted by supplying and discharging hydraulic oil to and from the arm cylinder 42, and the arm 41 swings forward and upward.

[0023] The bucket control valve 73 can be switched to a first position 73A, a second position 73B, or a third position 73C by energizing or deenergizing a first solenoid 73D and a second solenoid 73E. When the bucket control valve 73 is switched to the first position 73A, the bucket cylinder 52 is extended by supplying and discharging hydraulic oil to and from the bucket cylinder 52, and the bucket 51 swings in the direction of the scoop. On the other hand, when the bucket control valve 73 is switched to the second position 73B, the bucket cylinder 52 is contracted by supplying and discharging hydraulic oil to and from the bucket cylinder 52, and the bucket 51 swings in the direction of the dump.

[0024] The control device 60 includes a boom control unit 61, an arm control unit 62, and a bucket control unit 63, and controls the switching operations of a boom control valve 71, an arm control valve 72, and a bucket control valve 73. That is, the control device 60 controls the operations of the boom 31, the arm 41 and the bucket 51. The control device 60 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software using a computer. In the latter case, the computer includes a recording medium on which a program, which is software for realizing each function of the control device 60, and various data related to the work machine 1 are recorded in a computer-readable manner, an arithmetic circuit such as a CPU (Central Processing Unit) that executes the instructions of the program, and a RAM (Random Access Memory) that expands the program and various data. The arithmetic circuit then reads the program from the recording medium. The functions of the control device 60 are realized by reading and executing the program.

[0025] The control device 60 is connected to operation devices 19L, 19R that are held by an operator during operation. The operation devices 19L, 19R are each provided near the driver's seat 6. Each of the operation devices 19L, 19R has an operation lever 15 and a position sensor 16. The operation lever 15 can be freely swung forward, backward, right, and left from a neutral position, and the position sensor 16 detects the amount of swing (amount of operation) of the operation lever 15 from the neutral position of forward, backward, right, and left.

[0026] For example, when the operator swings the control lever 15 of the control device 19R forward or backward, the swing amount when swinging forward or backward is input to the control device 60. The control device 60 switches the boom control valve 71 by exciting or demagnetizing the first solenoid 71D and the second solenoid 71E according to the swing direction and swing amount of the control lever 15. Also, when the operator swings the control lever 15 of the control device 19L forward or backward, the swing amount when swinging forward or backward is input to the control device 60. The control device 60 switches the arm control valve 72 by exciting or demagnetizing the first solenoid 72D and the second solenoid 72E according to the swing direction and swing amount of the control lever 15. Also, when the operator swings the control lever 15 of the control device 19R left or right, the swing amount when swinging left or right is input to the control device 60. The control device 60 switches the bucket control valve 73 by exciting or de-energizing the first solenoid 73D and the second solenoid 73E in accordance with the swing direction and swing amount of the operating lever 15.

[0027] The control device 60 also includes a boom angle sensor 91 that detects a swing angle θ2 (rotation position) of the boom 31, an arm angle sensor 92 that detects a swing angle θ3 (rotation position) of the arm 41, and a work tool angle sensor 93 that detects a swing angle θ4 (rotation position) of the bucket 51 around the horizontal axis 57 with respect to the tip of the arm 41. In this embodiment, potentiometers are used as the boom angle sensor 91, the arm angle sensor 92, and the work tool angle sensor 93, but this is not limiting and other angle sensors may be used, or the strokes (extended positions) of the boom cylinder 32, the arm cylinder 42, and the bucket cylinder 52 may be detected, and the swing angles of the boom 31, the arm 41, and the bucket 51 may be calculated from the detection results.

[0028] (1-3. Arm cylinder operation control) (1-3-1. Setting the reference distance L1) Next, there will be described operation control of the arm cylinder 42 in the work machine 1. First, there will be described a method for setting the possible stroke range of the arm cylinder 42 when the boom device 30 (boom 31) is in the boom reference position S1.

[0029] 3, the control device 60 (arm control unit 62) sets the extension range of the arm cylinder 42 (the possible stroke range towards the side where the arm 41 approaches the boom cylinder 32) so that the distance between the boom device 30 and the tip 58 of the bucket 51 becomes a reference distance (predetermined value) L1 for avoiding interference between the boom device 30 and the tip 58 of the bucket 51 when the boom device 30 (boom 31) is in the boom reference position S1. The value of the reference distance L1 may be a fixed value set by default, or may be arbitrarily changeable.

[0030] The boom reference position S1 is a rotation position of the boom 31 where the shortest path distance, which is the shortest distance between the boom cylinder 32 and the rotation path M3 of the tip 58 of the bucket 51 about the horizontal shaft 57 when the boom 31 is rotated about the horizontal shaft 35 while keeping the stroke of the arm cylinder 42 constant, is minimum. In other words, the boom reference position S1 is the boom position (boom angle) where the distance between the boom cylinder 32 and the underside 31D of the boom 31 is the greatest.

[0031] In this embodiment, at the boom reference position S1, in the swing bracket 20B, the angle θ1 between a first straight line M1 connecting the center of the horizontal axis 35 of the first pivot part 23 that supports the base end of the boom 31 so as to be freely swingable and the center of the horizontal axis 36 of the second pivot part 24 that supports the base end of the boom cylinder 32 so as to be freely swingable and a second straight line M2 that passes through the center of the horizontal axis 36 and is parallel to the extension direction (axial direction) of the boom cylinder 32 is approximately a right angle.

[0032] As described above, the control device (arm control section 62) 60 sets the extendable range of the arm cylinder 42 so that the shortest trajectory distance at the boom reference position S1 is the reference distance L1. That is, the control device (arm control section 62) 60 sets the strokeable range of the arm cylinder 42 so that, with the boom 31 in the boom reference position S1, the shortest trajectory distance, which is the distance between the boom device 30 (boom cylinder 32) and the proximity point P10 that is closest to the boom device 30 (boom cylinder 32) in the rotation trajectory M3 of the tip end 58 when the bucket 51 is swung, is the reference distance L1.

[0033] In this embodiment, the reference distance L1 is set to 80 mm, but is not limited to this value. The reference distance L1 may be set to be as short as possible within a range that appropriately prevents contact between the boom cylinder 32 and the bucket 51, and is preferably set within a range of 50 mm to 120 mm, and more preferably within a range of 60 mm to 100 mm.

[0034] In this embodiment, the arm cylinder 42 has a margin for further extension in a direction to make the shortest trajectory distance shorter than the reference distance L1 at the boom reference position S1, but the control device (arm control unit 62) 60 limits the possible stroke range (extendable range) of the arm cylinder 42 so that the shortest trajectory distance does not become less than the reference distance L1. As a result, as shown in Fig. 3, when the boom 31 is at the boom reference position S1, even if the bucket 51 is swung, the tip 58 of the bucket 51 does not come into contact with the boom device 30 (boom cylinder 32).

[0035] (1-3-2. When the boom moves away from the reference position) Next, the operation control of the arm cylinder 42 when the boom 31 is moved in a direction away from the boom reference position S1 will be described. 4 shows a boom swing position S2 in the case of performing conventional control in which the boom 31 is swung upward while keeping the stroke of the arm cylinder 42 constant, from a state in which the arm cylinder 42 is extended so that the shortest trajectory distance becomes the reference distance L1 at the boom reference position S1. In this state, the rotation trajectory M3 of the tip 58 of the bucket 51 and the shortest trajectory distance L2 between the boom cylinder 32 increases beyond the reference distance L1.

[0036] In contrast, in this embodiment, when the boom 31 is rotated in a direction away from the boom reference position S1, the arm control unit 62 (control device 60) sets the stroke range of the arm cylinder 42 (the stroke range toward the side where the arm 41 moves closer to the boom 31) according to the rotation position of the boom 31 so that the shortest trajectory distance, which is the shortest distance between the rotation trajectory M3 of the tip 58 of the bucket 51 and the boom cylinder 32, is maintained at the reference distance L1.

[0037] Specifically, when the operator operates the control device 19R to operate the boom 31, the boom control unit 61 operates the boom 31 in response to the operator's operation. Also, the arm control unit 62 sets the possible stroke range of the arm cylinder 42 based on the detection result of the rotation position of the boom 31 by the boom angle sensor 91 and the pre-stored relationship between the rotation position of the boom 31 and the possible stroke range of the arm cylinder 42 for making the shortest trajectory distance the reference distance L1.

[0038] More specifically, the arm control unit 62 refers to the swing angle θ2 (rotation position) of the boom 31 input from the boom angle sensor 91 and the direction of rotation operation of the boom 31 by the operator, and determines whether the operation is in a direction to move the boom 31 away from the boom reference position S1. If the arm control unit 62 determines that the operation is in a direction to move the boom 31 away from the boom reference position S1, it refers to a table or function indicating the relationship between the rotation position of the boom 31 and the possible stroke range of the arm cylinder 42 for making the shortest trajectory distance the reference distance L1, and sets the possible stroke range of the arm cylinder 42 based on the reference result.

[0039] As a result, for example, when the operator operates the control device 19L to move the arm 41 closer to the boom cylinder 32 at the boom swing position S2 described above, the arm cylinder 42 is allowed to extend to a position where the shortest trajectory distance coincides with the reference distance L1, as shown in Fig. 5. That is, if the maximum length of the arm cylinder 42 when the conventional control shown in Fig. 4 is performed is L10, and the maximum length of the arm cylinder 42 when the control of this embodiment shown in Fig. 5 is performed is L11, then L11>L10.

[0040] As a result, as shown in FIG. 5, the arm 41 and the bucket 51 can be moved sufficiently toward the boom 31 regardless of the posture of the boom 31, and the fore-aft length Lb of the working mechanism 4 can be made shorter than the length La (see FIG. 4) when the stroke range of the arm cylinder 42 is kept at the same constant value as the boom reference position S1. 4 and 5 show an example in which the boom 31 is rotated upward from the boom reference position S1, but the arm control unit 62 (control device 60) performs the same control when the boom 31 is rotated downward from the boom reference position S1. That is, when the boom 31 is swung in a direction away from the boom reference position S1 downward, the control device 60 sets the strokeable range of the arm cylinder 42 (the strokeable range of the arm cylinder 42 toward the side where the arm 41 approaches the boom 31) in accordance with the rotation position of the boom 31 so that the shortest path distance, which is the shortest distance between the rotation path M3 of the tip 58 of the bucket 51 and the boom cylinder 32, is kept at the reference distance L1. As a result, even when the boom 31 is rotated downward from the boom reference position S1, the tip 58 of the bucket 51 can be moved to a position close to or in contact with the blade 74 of the dozer device 7. Therefore, the work of scooping up earth and sand with the bucket 51 and the blade 74 of the dozer device 7 (so-called dust removal work) can be easily performed.

[0041] (1-3-3. When the boom moves towards the reference position) Next, the operation control of the arm cylinder 42 when the boom 31 is moved in a direction approaching the boom reference position S1 will be described. Fig. 6 shows a state in which the boom 31 is rotated from the boom swing position S2 to a boom swing position S3 that is closer to the boom reference position S1 than the boom swing position S2, while keeping the possible stroke range of the arm cylinder 42 constant at the possible stroke range of the arm cylinder 42 set at the boom swing position S2. That is, Fig. 6 shows a state in which the boom 31 is rotated from the boom swing position S2 to the boom swing position S3, while keeping the maximum length L12 of the arm cylinder 42 constant at the maximum length L11 of the arm cylinder 42 set at the boom swing position S2 (see Fig. 5) (L12 = L11).

[0042] As shown in FIG. 6, when the boom 31 is brought closer to the boom reference position S1 while maintaining the stroke range within the range set at the boom swing position S2, the boom cylinder 32 enters the rotation trajectory M3 of the tip 58 of the bucket 51, which may cause interference between the boom cylinder 32 and the tip 58 of the bucket 51. In contrast, in this embodiment, when the arm control unit 62 (control device 60) rotates the boom 31 in a direction approaching the boom reference position S1, and when operating only the boom 31 without operating the arm cylinder 42 would cause the shortest trajectory distance, which is the shortest distance between the boom cylinder 32 and the rotation trajectory M3 of the tip 58 of the bucket 51, to be less than the reference distance L1, the arm cylinder 42 is operated to retract the arm 41 in a direction away from the boom cylinder 32 for the tip 58 of the bucket 51.

[0043] Specifically, when the operator operates the control device 19R to move the boom 31, the boom control unit 61 moves the boom 31 in response to the operator's operation. Also, the arm control unit 62 refers to the swing angle θ2 (rotation position) of the boom 31 input from the boom angle sensor 91 and the direction of rotation operation of the boom 31 by the operator, and determines whether the operation is in a direction to bring the boom 31 closer to the boom reference position S1.

[0044] Then, when the arm control unit 62 judges that the operation is in the direction of bringing the boom 31 closer to the boom reference position S1, it judges whether or not the shortest trajectory distance will be less than the reference distance L1 if only the boom 31 is operated without operating the arm cylinder 42, based on the detection result of the rotation position of the boom 31 by the boom angle sensor 91 and the detection result of the rotation position of the arm 41 by the arm angle sensor 92. Then, when it is judged that the shortest trajectory distance will be less than the reference distance L1, the arm control unit 62 operates (contracts) the arm cylinder 42 until the shortest trajectory distance becomes the reference distance L1, and retracts the arm 41 in a direction in which the tip 58 of the bucket 51 moves away from the boom cylinder 32. That is, the arm control unit 62 refers to a table or a function indicating the relationship between the rotation position of the boom 31 and the rotation position of the arm 41, specifies the stroke amount (contraction amount) of the arm cylinder 42 for making the shortest trajectory distance the reference distance L1, and operates the arm cylinder 42 according to the specified stroke amount. This makes it possible to prevent interference between the boom cylinder 32 and the bucket 51.

[0045] (1-3-4. Electronic cushion) Furthermore, when the arm cylinder 42 is extended beyond the possible stroke range set at the boom reference position S1, the arm control section 62 performs electronic cushion control to limit the operating speed of the arm cylinder 42 more than when it is extended within the possible stroke range. Specifically, when the arm cylinder 42 is extended beyond the possible stroke range set at the boom reference position S1 in a state in which the boom 31 is rotated in a direction away from the boom reference position S1, the arm control section 62 reduces the pilot pressure supplied to the pressure receiving section (pilot pressure receiving section) of the arm control valve 72. This makes it possible to easily limit the operating speed of the arm cylinder 42 at the terminal end of the possible stroke range, regardless of the setting status of the possible stroke range of the arm cylinder 42.

[0046] [Embodiment 2] Another embodiment of the present invention will be described below. For convenience of explanation, the same reference numerals are used for members having the same functions as those in the first embodiment, and the explanation thereof will be omitted. In the first embodiment, an example has been described in which the possible stroke range of the arm cylinder 42 is set in accordance with the rotation position of the boom 31. In contrast, in the present embodiment, the possible stroke range of the arm cylinder 42 is set based on the rotation position of the boom 31 and the rotation position of the bucket 51.

[0047] (2-1. Initial setting of arm cylinder stroke range) First, the arm control unit 62 calculates a tip distance, which is a distance between the tip 58 of the bucket 51 in the current swing posture and the boom cylinder 32, based on the detection result of the swing angle θ2 (rotation position) of the boom 31 by the boom angle sensor 91, the detection result of the swing angle θ3 (rotation position) of the arm 41 by the arm angle sensor 92, and the detection result of the swing angle θ4 (rotation position) of the bucket 51 by the implement angle sensor 93. Then, the arm control unit 62 sets the strokeable range of the arm cylinder 42 (the strokeable range to the side where the arm 41 approaches the boom 31) to be strokeable up to a position where the calculated tip distance becomes the reference distance L1, as shown in FIG. 7. As a result, as shown in FIG. 7, the maximum length L13 of the arm cylinder 42 is set longer than the maximum length L11 of the arm cylinder 42 set at the boom swing position S2 (see FIG. 5) in the first embodiment according to the swing angle θ4 of the bucket 51, and the arm 41 and the bucket 51 can be brought closer to the boom 31 side than in the first embodiment.

[0048] (2-2. When the boom moves away from the reference position) When the boom 31 is rotated in a direction away from the boom reference position S1, the arm control unit 62 sets the stroke range of the arm cylinder 42 so that the tip distance, which is the distance between the tip 58 of the bucket 51 and the boom cylinder 32, is maintained at the reference distance L1, depending on the swing angle (rotation position) of the boom 31, arm 41, and bucket 51.

[0049] Specifically, when the operator operates the control device 19R to move the boom 31 in a direction away from the boom reference position S1, the boom control unit 61 operates the boom 31 in response to the operator's operation. Also, the arm control unit 62 sets the possible stroke range of the arm cylinder 42 based on the detection results of the rotation positions of the boom 31, arm 41, and bucket 51 by the boom angle sensor 91, arm angle sensor 92, and implement angle sensor 93, and a pre-stored table or function indicating the relationship with the possible stroke range of the arm cylinder 42 for making the tip distance, which is the distance between the tip 58 of the bucket 51 and the boom cylinder 32, the reference distance L1.

[0050] Thereby, by setting the possible stroke range of the arm cylinder 42 taking into consideration the swing posture (rotation position) of the bucket 51, it is possible to move the arm 41 and the bucket 51 closer to the boom 31 side than in the first embodiment. (2-3. When moving the boom towards the reference position) When the boom 31 is rotated in a direction approaching the boom reference position S1, and the tip distance between the boom cylinder 32 and the tip 58 of the bucket 51 would be less than the reference distance L1 if only the boom 31 were operated without operating the arm cylinder 42, the arm control unit 62 operates the arm cylinder 42 to retract the arm 41 in a direction away from the boom cylinder 32.

[0051] Specifically, when the operator operates the control device 19R to operate the boom 31 in a direction approaching the boom reference position S1, the boom control unit 61 operates the boom 31 in response to the operator's operation. Also, the arm control unit 62 judges whether the tip distance will be less than the reference distance L1 if the boom 31 is operated without operating the arm cylinder 42 and the bucket 51, based on the detection result of the rotation position of the boom 31 by the boom angle sensor 91, the detection result of the rotation position of the arm 41 by the arm angle sensor 92, and the detection result of the rotation position of the bucket 51 by the implement angle sensor 93. Then, when it is judged that the tip distance will be less than the reference distance L1, the arm control unit 62 operates (contracts) the arm cylinder 42 until the tip distance becomes the reference distance L1, and retracts the arm 41 in a direction in which the tip 58 of the bucket 51 moves away from the boom cylinder 32. That is, the arm control unit 62 determines whether the tip distance will be less than the reference distance L1 based on the rotation position of the boom 31, the rotation position of the arm 41, and the rotation position of the bucket 51, and the stroke of the arm cylinder 42. The stroke amount (retraction amount) of the arm cylinder 42 for bringing the tip distance into the reference distance L1 is specified by referring to a table or function showing the relationship between the stroke and the tip distance, and the arm cylinder 42 is operated according to the specified stroke amount. This makes it possible to prevent interference between the boom cylinder 32 and the bucket 51.

[0052] (2-4. When the bucket is in operation) When the bucket 51 is rotated in a direction approaching the boom cylinder 32, and the tip distance would be less than the reference distance L1 if the bucket 51 were operated without operating the arm cylinder 42, the arm control unit 62 operates the arm cylinder 42 to retract the arm 41 in a direction such that the tip 58 of the bucket 51 moves away from the boom cylinder 32.

[0053] Specifically, when the operator operates the control device 19R to operate the bucket 51 in a direction to move it closer to the boom cylinder 32 (scooping operation), the bucket control unit 63 operates the bucket 51 in response to the operation of the operator. Also, the arm control unit 62 determines whether or not the tip distance will be less than the reference distance L1 if the bucket 51 is operated without operating the arm cylinder 42, based on the detection result of the rotation position of the boom 31 by the boom angle sensor 91, the detection result of the rotation position of the arm 41 by the arm angle sensor 92, and the detection result of the rotation position of the bucket 51 by the work tool angle sensor 93. Then, when it is determined that the tip distance will be less than the reference distance L1, the arm control unit 62 operates (contracts) the arm cylinder 42 until the tip distance becomes the reference distance L1, and retracts the arm 41 in a direction in which the tip 58 of the bucket 51 moves away from the boom cylinder 32. That is, the arm control unit 62 refers to a table or function indicating the relationship between the rotational position of the boom 31, the rotational position of the arm 41, and the rotational position of the bucket 51 and the stroke and tip distance of the arm cylinder 42, specifies the stroke amount (contraction amount) of the arm cylinder 42 for making the tip distance the reference distance L1, and operates the arm cylinder 42 according to the specified stroke amount. This makes it possible to prevent interference between the boom cylinder 32 and the bucket 51. Note that even when the boom 31 and the bucket 51 are operated simultaneously (combined operation), the arm control unit 62 operates the arm cylinder 42 as necessary in a similar manner to retract the arm 41 in a direction in which the tip 58 of the bucket 51 moves away from the boom cylinder 32.

[0054] [Embodiment 3] Further, for the sake of convenience, the same reference numerals are used to designate members having the same functions as those in the above-described embodiment, and the description thereof will be omitted. In the first embodiment, an example has been described in which the stroke range of the arm cylinder 42 is set in accordance with the rotation position of the boom 31, regardless of the rotation position of the bucket 51. In contrast, in the present embodiment, based on the rotation position of the boom 31 and the rotation position of the bucket 51, it is switched whether the stroke range of the arm cylinder 42 is set in accordance with the rotation position of the boom 31 or is constant regardless of the rotation position of the boom 31.

[0055] First, based on the detection result of the swing angle θ4 (rotation position) of the bucket 51 by the work tool angle sensor 93, the arm control unit 62 judges whether the current rotation position of the bucket 51 is in a first range in which the tip 58 is disposed closer to the boom cylinder 32 side (cloud side) than when the bucket 51 is disposed at a predetermined position (see FIG. 8), or in a second range in which the tip 58 is disposed farther from the boom cylinder 32 side (dump side). The above-mentioned predetermined position is not particularly limited, and may be set to the rotation position of the bucket 51 when the control device 19R is in the neutral position, may be a position in which the tip 58 of the bucket 51 is disposed on the axis of the arm 41 (a straight line passing through the center of the horizontal shaft 43 and the center of the horizontal shaft 57), or may be set to the center position of the rotatable range of the tip 58 of the bucket 51.

[0056] Then, the arm control unit 62 detects whether the current rotation position of the bucket 51 is within a first range (above a predetermined position). If it is determined that the boom 31 is on the crowd side (rather than the crowd side), the stroke range of the arm cylinder 42 is set according to the rotation position of the boom 31 in the same manner as in the first embodiment described above. Furthermore, when the arm control unit 62 determines that the current rotation position of the bucket 51 is in the second range (closer to the dump truck side than the predetermined position), it sets the possible stroke range of the arm cylinder 42 to a constant value within which the shortest trajectory distance is a second predetermined value shorter than the reference distance L1 at the boom reference position S1. As a result, as shown in Fig. 8, when the current rotation position of the bucket 51 is in the second range, the maximum length L14 of the arm cylinder 42 is set to be longer than the maximum length L11 of the arm cylinder 42 set at the boom swing position S2 (see Fig. 5) in the first embodiment, and the arm 41 and the bucket 51 can be moved even closer to the boom 31 side than in the first embodiment.

[0057] This prevents the bucket 51 from coming into contact with the boom cylinder 32, and allows the arm 41 and the bucket 51 to be brought sufficiently close to the boom 31 regardless of the attitude of the boom 31. Furthermore, when a crowding operation (operation of rotating tip 58 of bucket 51 toward boom cylinder 32) is performed when the current rotation position of bucket 51 is in the second range (toward the dump truck side from the predetermined position), bucket control unit 63 sets the rotatable range of bucket 51 up to the predetermined position, and stops the operation of bucket 51 when the rotation position of bucket 51 reaches the predetermined position. This makes it possible to reliably prevent tip 58 of bucket 51 from contacting the boom cylinder 32.

[0058] When the arm control unit 62 determines that the current rotation position of the bucket 51 is in the first range (closer to the cloud side than the predetermined position), the possible stroke range of the arm cylinder 42 may be set constant within the possible stroke range in which the shortest trajectory distance at the boom reference position S1 is the reference distance L1, regardless of the rotation position of the boom 31. This makes it possible to reliably prevent the bucket 51 from contacting the boom cylinder 32 when the bucket 51 is in the first range, and also makes it possible to move the arm 41 and the bucket 51 sufficiently closer to the boom 31 side than before, regardless of the attitude of the boom 31, when the bucket 51 is in the second range.

[0059] [Embodiment 4] Further, for the sake of convenience, the same reference numerals are used to designate members having the same functions as those in the above-described embodiment, and the description thereof will be omitted. In the third embodiment, a configuration has been described in which, based on the rotation position of the boom 31 and the rotation position of the bucket 51, the possible stroke range of the arm cylinder 42 is switched between being set in accordance with the rotation position of the boom 31 or being constant regardless of the rotation position of the boom 31. In contrast, in the present embodiment, the possible stroke range of the arm cylinder 42 is set in accordance with the rotation position of the bucket 51, regardless of the rotation position of the boom 31.

[0060] First, the arm control unit 62 judges whether the current rotation position of the bucket 51 is in the first range or the second range based on the detection result of the swing angle θ4 (rotation position) of the bucket 51 by the work tool angle sensor 93. The method of setting the first range and the second range is the same as in embodiment 3. Then, when the arm control unit 62 judges that the current rotation position of the bucket 51 is in the first range (closer to the crowd side than the predetermined position), it sets the possible stroke range of the arm cylinder 42 to a fixed range in which the shortest trajectory distance becomes the reference distance (predetermined value) L1 at the boom reference position S1 regardless of the rotation position of the boom 31.

[0061] Furthermore, when the arm control unit 62 determines that the current rotation position of the bucket 51 is in the second range (closer to the dump truck side than the predetermined position), it sets the stroke possible range of the arm cylinder 42 to a fixed range in which the shortest trajectory distance is a second predetermined value shorter than the reference distance L1 at the boom reference position S1. As a result, as shown in FIG. 8, when the current rotation position of the bucket 51 is in the second range In this case, the maximum length L14 of the arm cylinder 42 is set longer than the maximum length L11 of the arm cylinder 42 set at the boom swing position S2 (see Figure 5) in embodiment 1, and the arm 41 and bucket 51 can be moved even closer to the boom 31 than in embodiment 1.

[0062] This prevents the bucket 51 from coming into contact with the boom cylinder 32, and allows the arm 41 and the bucket 51 to be brought sufficiently close to the boom 31 regardless of the attitude of the boom 31. Furthermore, when a crowding operation (operation of rotating tip 58 of bucket 51 toward boom cylinder 32) is performed when the current rotation position of bucket 51 is in the second range (toward the dump truck side from the predetermined position), bucket control unit 63 sets the rotatable range of bucket 51 up to the predetermined position, and stops the operation of bucket 51 when the rotation position of bucket 51 reaches the predetermined position. This makes it possible to reliably prevent tip 58 of bucket 51 from contacting the boom cylinder 32.

[0063] 〔summary〕 As described above, the working machine 1 according to one aspect of the present invention is a working machine comprising a body, a boom having a base end pivotally supported on the body so as to be rotatable about a first rotation axis, a boom cylinder for rotating the boom about the first rotation axis, an arm having a base end pivotally supported on a tip end of the boom so as to be rotatable about a second rotation axis parallel to the first rotation axis, an arm cylinder for rotating the arm about the second rotation axis, and a working tool pivotally supported on the tip end of the arm so as to be rotatable about a third rotation axis parallel to the first rotation axis, the boom cylinder being disposed on one side of the boom and the arm cylinder being disposed on the other side of the boom, The boom reference position is defined as a boom rotation position at which a first line connecting a fourth rotation shaft provided on the base end side of the boom and rotatably supporting the boom cylinder and a second line parallel to the extension direction of the boom cylinder form a right angle. When the boom is rotated in a direction away from the boom reference position, the control device sets the possible stroke range of the arm cylinder toward the boom in accordance with the boom rotation position so that the minimum trajectory distance, which is the minimum distance between the rotation trajectory of the tip of the work tool about the third rotation shaft and the boom cylinder, is maintained at a predetermined value even if the boom rotation position changes.

[0064] According to the above configuration, the stroke range of the arm cylinder is set according to the boom rotation position so that the shortest trajectory distance is maintained at a predetermined value even if the boom rotation position changes, so that the arm and work tool can be moved sufficiently close to the boom side regardless of the boom posture. The control device may set a possible stroke range of the arm cylinder so that the range becomes longer as the boom is rotated in a direction away from the boom reference position.

[0065] According to the above configuration, the arm and the work tool can be brought sufficiently close to the boom side regardless of the attitude of the boom. The control device may also include a boom sensor that detects a rotational position of the boom about the first rotation axis and an arm sensor that detects a rotational position of the arm about the second rotation axis, and when the boom is rotated in a direction approaching the boom reference position and the boom is rotated while keeping the stroke of the arm cylinder constant, if the shortest trajectory distance becomes less than the predetermined value, the control device may operate the arm cylinder to rotate the arm to a position where the shortest trajectory distance is equal to or greater than the predetermined value.

[0066] According to the above configuration, the implement can be appropriately prevented from coming into contact with the boom cylinder. Further, the rotation position of the working tool about the third rotation axis is in a first range in which the tip of the working tool is disposed closer to the boom cylinder than a predetermined position, or is farther from the boom cylinder. the control device may set a stroke range of the arm cylinder toward the boom in accordance with the rotational position of the boom so that, when the rotational position of the work tool is in the first range, the shortest trajectory distance remains at the predetermined value even if the rotational position of the boom changes, and set a stroke range of the arm cylinder toward the boom in accordance with the rotational position of the boom so that, when the rotational position of the work tool is in the second range, the shortest trajectory distance remains at a second predetermined value shorter than the predetermined value even if the rotational position of the boom changes.

[0067] A working machine according to another aspect of the present invention includes a machine body, a boom having a base end pivotally supported on the machine body so as to be rotatable about a first rotation axis, a boom cylinder for rotating the boom about the first rotation axis, an arm having a base end pivotally supported on a tip of the boom so as to be rotatable about a second rotation axis parallel to the first rotation axis, an arm cylinder for rotating the arm about the second rotation axis, a working tool pivotally supported on the tip of the arm so as to be rotatable about a third rotation axis parallel to the first rotation axis, and a working tool sensor for detecting whether a rotation position of the working tool about the third rotation axis is in a first range in which the tip of the working tool is positioned closer to the boom cylinder than a predetermined position, or in a second range in which the tip of the working tool is positioned farther from the boom cylinder, wherein the boom cylinder is positioned on one side of the boom and the arm cylinder is positioned on the other side of the boom. The boom reference position is defined as a boom rotation position where a first line connecting the first rotation shaft and a fourth rotation shaft provided on the base end side of the boom and rotatably supporting the boom cylinder forms a right angle with a second line that is a line parallel to the extension direction of the boom cylinder, and a shortest distance between the rotation path of the tip of the working tool about the third rotation shaft and the boom cylinder is defined as a shortest path distance. The boom reference position is defined as a boom rotation position where a first line connecting the first rotation shaft and a fourth rotation shaft provided on the base end side of the boom and rotatably supporting the boom cylinder forms a right angle with a second line that is a line parallel to the extension direction of the boom cylinder, and a shortest path distance is defined as a shortest path distance. The boom reference position is defined as a boom reference position where a first line connecting the first rotation shaft and a fourth rotation shaft provided on the base end side of the boom and rotatably supporting the boom cylinder forms a right angle with a second line that is parallel to the extension direction of the boom cylinder, and a shortest path distance is defined as a shortest path distance.

[0068] According to each of the above configurations, with a simple configuration, the working implement can be appropriately prevented from contacting the boom cylinder, and the arm and the working implement can be sufficiently brought closer to the boom side regardless of the attitude of the boom. In addition, when the shortest trajectory distance is smaller than the predetermined value and the work tool is rotated from a state in which the work tool is in the second range toward the first range, the control device may limit the stroke range of the work tool cylinder to a range in which the tip of the work tool does not enter the first range.

[0069] According to the above configuration, the implement can be appropriately prevented from coming into contact with the boom cylinder. A working machine according to yet another aspect of the present invention includes a body, a boom having a base end pivotally supported on the body so as to be rotatable about a first rotation axis, a boom cylinder for rotating the boom about the first rotation axis, an arm having a base end pivotally supported on a tip end of the boom so as to be rotatable about a second rotation axis parallel to the first rotation axis, an arm cylinder for rotating the arm about the second rotation axis, a working tool pivotally supported on the tip end of the arm so as to be rotatable about a third rotation axis parallel to the first rotation axis, and a working tool sensor for detecting a rotation position of the working tool about the third rotation axis, wherein the boom cylinder is disposed on one side of the boom and the arm cylinder is disposed on the other side of the boom. the boom reference position is a boom reference position at which a first line connecting the first rotation shaft and a fourth rotation shaft provided on the base end side of the boom and rotatably supporting the boom cylinder forms a right angle with a second line that is a line parallel to the extension direction of the boom cylinder, and when the boom is rotated in a direction away from the boom reference position, a control device sets a possible stroke range of the arm cylinder toward the boom in accordance with the boom reference position and the working implement so that a tip distance, which is the shortest distance between the tip of the working implement and the boom cylinder, is maintained at a predetermined value even if the boom reference position changes.

[0070] According to the above configuration, the stroke range of the arm cylinder is set according to the boom rotation position and the work tool rotation position so that the shortest trajectory distance is maintained at a predetermined value even if the boom rotation position changes, so that the arm and work tool can be moved sufficiently close to the boom side regardless of the boom posture. In addition, when the control device rotates the work tool in a direction such that the tip of the work tool approaches the boom cylinder, and if rotating the work tool while keeping the stroke of the arm cylinder constant would cause the tip distance to be less than the predetermined value, the control device may operate the arm cylinder to rotate the arm to a position where the tip distance is equal to or greater than the predetermined value.

[0071] According to the above configuration, the implement can be appropriately prevented from coming into contact with the boom cylinder. In addition, when the boom is rotated in a direction approaching the boom reference position, and if rotating the boom while keeping the rotational position of the work tool constant would cause the tip distance to be less than the predetermined value, the control device may operate the arm cylinder to rotate the arm to a position where the tip distance is equal to or greater than the predetermined value.

[0072] According to the above configuration, the implement can be appropriately prevented from coming into contact with the boom cylinder. Furthermore, the control device may limit the operating speed of the arm cylinder when the arm cylinder is caused to stroke beyond a possible stroke range at the boom reference position. According to the above configuration, by slowing down the operating speed of the arm cylinder near the end of the arm cylinder's possible stroke range, it is possible to prevent vibrations and impacts from occurring due to the arm operation suddenly stopping.

[0073] Furthermore, in a control method for a work machine according to one embodiment of the present invention, if the boom rotation position where a first line connecting the first rotation shaft and a fourth rotation shaft provided on the base end side of the boom and rotatably supporting the boom cylinder is perpendicular to a second line which is a line parallel to the extension direction of the boom cylinder, is defined as the boom reference position, when the boom is rotated in a direction away from the boom reference position, the possible stroke range of the arm cylinder to bring the arm closer to the boom is set according to the boom rotation position so that the shortest trajectory distance, which is the shortest distance between the rotation trajectory around the third rotation shaft of the tip of the work tool and the boom cylinder, is maintained at a predetermined value even if the boom rotation position changes.

[0074] In addition, in a control method for a work machine according to another aspect of the present invention, the boom rotation position where a first line connecting the first rotation axis and a fourth rotation axis provided on the base end side of the boom and rotatably supporting the boom cylinder and a second line connecting both longitudinal ends of the boom cylinder are perpendicular to each other is defined as the boom reference position, and the shortest distance between the rotational trajectory around the third rotation axis of the tip of the work tool and the boom cylinder is defined as the shortest trajectory distance. The possible stroke range of the arm cylinder toward the side bringing the arm closer to the boom is set to a fixed range where the shortest trajectory distance is a predetermined value at the boom reference position when the work tool rotation position is in a first range, regardless of the boom rotation position, and is set to a fixed range where the shortest trajectory distance is a second predetermined value shorter than the predetermined value at the boom reference position when the work tool rotation position is in a second range.

[0075] In a control method for a work machine according to still another aspect of the present invention, when a boom reference position is a boom rotation position where a first line connecting a first rotation shaft and a fourth rotation shaft that is provided on a base end side of the boom and that rotatably supports the boom cylinder is perpendicular to a second line that is a line parallel to an extension direction of the boom cylinder, the boom is rotated in a direction away from the boom reference position. In this case, the stroke range of the arm cylinder to bring the arm closer to the boom is set according to the boom rotation position and the working tool rotation position so that the tip distance, which is the shortest distance between the tip of the working tool and the boom cylinder, is maintained at a predetermined value even if the boom rotation position changes.

[0076] The control device provided in each of the above-mentioned work machines may be realized by a computer. In this case, the scope of the present invention also includes a program for realizing the control device in a computer by causing the computer to operate as each part of the control device, and a computer-readable recording medium on which the program is recorded. Although the embodiments of the present invention have been described above, the embodiments disclosed herein are illustrative in all respects and are not restrictive. 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. In addition, embodiments obtained by appropriately combining the above-mentioned embodiments are also included in the scope of the present invention. [Explanation of symbols]

[0077] 1 Work equipment 2. Aircraft 4 Work equipment 7 Dozer equipment 19L Steering Device 19R Controls 30 Boom device 31 Boom 32 Boom cylinder 35 Horizontal axis (first rotation axis) 43 Horizontal axis (second rotation axis) 50 Work equipment 51 Bucket 52 Bucket cylinder 57 Horizontal axis (third rotation axis) 58 Tip 60 Control device 61 Boom control unit 62 Arm control section 63 Bucket control section 91 Boom angle sensor 92 Arm angle sensor 93 Tool Angle Sensor S1 Boom reference position S2, S3 Swing posture L1 Reference Distance L2 Shortest orbit distance L2 M3 rotation track θ2 Boom swing angle θ3 Arm swing angle θ4 Bucket swing angle

Claims

1. a boom pivoted rotatably about a first rotation axis on a swing bracket whose base end is attached to a front part of a support bracket that protrudes forward from a front part of the body so as to be swingable about a vertical axis, a boom cylinder that rotates the boom about the first rotation axis, an arm whose base end is pivoted rotatably about a second rotation axis parallel to the first rotation axis on a tip part of the boom, an arm cylinder that rotates the arm about the second rotation axis, a working tool pivoted rotatably about a third rotation axis parallel to the first rotation axis on the tip part of the arm, and a boom sensor that detects a rotation position of the boom about the first rotation axis, wherein the boom cylinder is disposed on one side of the boom and the arm cylinder is disposed on the other side of the boom, and the boom is a one-piece boom having no joint between the base end and the tip end, a control device that varies a strokeable range of the arm cylinder toward the boom in accordance with the boom rotation position so that a minimum trajectory distance, which is the minimum distance between the boom cylinder and a rotation trajectory about a third rotation shaft of the tip of the work tool, is kept constant at a predetermined value even if the boom rotation position changes; The control device is a work machine that rotates a boom while changing a possible stroke range of an arm cylinder in accordance with the rotational position of the boom so as to keep the shortest trajectory distance, which changes in accordance with the rotational position of the boom, constant at the predetermined value.

2. If a boom rotation position where a first line connecting the first rotation shaft and a fourth rotation shaft that is provided on the base end side of the boom and rotatably supports the boom cylinder forms a right angle with a second line that is a line parallel to the extension direction of the boom cylinder, is defined as a boom reference position, 2. The work machine according to claim 1, wherein the predetermined value is set to a reference distance at which the tip of the work implement and the boom cylinder do not come into contact with each other when the boom is in a reference position, and is kept constant at the reference distance even if the rotational position of the boom changes.

3. 3. The work machine according to claim 2, wherein, when the boom is rotated in a direction away from the boom reference position, the control device sets a possible stroke range of the arm cylinder corresponding to the boom rotation position indicated by the detection result of the boom rotation position by the boom sensor and a pre-stored table or function indicating the relationship between the boom rotation position and the possible stroke range of the arm cylinder for making the shortest trajectory distance the reference distance, allows extension of the arm cylinder to a position where the shortest trajectory distance matches the reference distance, and limits the possible stroke range of the arm cylinder so that the shortest trajectory distance does not become less than the reference distance.

4. 4. The work machine according to claim 2 or 3, wherein the control device sets the possible stroke range of the arm cylinder to be longer as the boom is rotated in a direction away from the boom reference position.

5. The work machine according to any one of claims 2 to 4, wherein when the boom is rotated in a direction approaching the boom reference position, and when the boom is rotated while keeping the stroke of the arm cylinder constant, the control device operates the arm cylinder to rotate the arm to a position where the shortest trajectory distance is equal to or greater than the predetermined value,

6. a work tool sensor that detects whether a rotation position of the work tool about a third rotation axis is in a first range in which a tip of the work tool is disposed closer to the boom cylinder than a predetermined position, or in a second range in which the tip of the work tool is disposed farther from the boom cylinder, 2. The work machine according to claim 1, wherein the control device sets the possible stroke range of the arm cylinder toward the boom according to the rotational position of the boom so that the shortest trajectory distance remains constant at the specified value even if the rotational position of the boom changes when the rotational position of the work tool is in a first range, and sets the possible stroke range of the arm cylinder toward the boom according to the rotational position of the boom so that the shortest trajectory distance remains constant at a second specified value shorter than the specified value even if the rotational position of the boom changes when the rotational position of the work tool is in a second range.

7. The work machine according to claim 6, wherein the control device limits the stroke range of the work tool cylinder to a range in which the tip of the work tool does not enter the first range when the shortest trajectory distance is smaller than the predetermined value and the work tool is rotated in a direction approaching the first range from a state in which the work tool is in the second range.

8. a boom pivoted rotatably about a first rotation axis on a swing bracket whose base end is attached to a front part of a support bracket that protrudes forward from a front part of the body so as to be swingable about a vertical axis, a boom cylinder for rotating the boom about the first rotation axis, an arm whose base end is pivoted rotatably about a second rotation axis parallel to the first rotation axis on a tip part of the boom, an arm cylinder for rotating the arm about the second rotation axis, a working tool pivoted rotatably about a third rotation axis parallel to the first rotation axis on the tip part of the arm, a boom sensor for detecting a rotation position of the boom about the first rotation axis, and a working tool sensor for detecting a rotation position of the working tool about the third rotation axis, wherein the boom cylinder is disposed on one side of the boom and the arm cylinder is disposed on the other side of the boom, and the boom is a one-piece boom having no joint between the base end and the tip end, a control device that varies a strokeable range of the arm cylinder toward the side where the arm approaches the boom in accordance with the boom rotation position and the working tool rotation position so that a tip distance, which is the shortest distance between the tip of the working tool and the boom cylinder, is kept constant at a predetermined value even if the boom rotation position changes; The control device is a work machine that rotates the boom while changing the possible stroke range of an arm cylinder in accordance with the rotational position of the boom so as to keep the tip distance, which changes in accordance with the rotational position of the boom, constant at the predetermined value.

9. If a boom rotation position where a first line connecting the first rotation shaft and a fourth rotation shaft that is provided on the base end side of the boom and rotatably supports the boom cylinder forms a right angle with a second line that is a line parallel to the extension direction of the boom cylinder, is defined as a boom reference position, 9. The work machine according to claim 8, wherein the predetermined value is set to a reference distance at which the tip of the work implement and the boom cylinder do not come into contact with each other when the boom is in a reference position, and is kept constant at the reference distance even if the rotational position of the boom changes.

10. 10. The work machine according to claim 9, wherein, when the boom is rotated in a direction away from the boom reference position, the control device sets a possible stroke range of the arm cylinder corresponding to the boom rotation position indicated by the detection result of the boom rotation position by the boom sensor and a pre-stored table or function indicating a relationship between the boom rotation position and the possible stroke range of the arm cylinder for setting the tip distance to the reference distance, allows extension of the arm cylinder to a position where the tip distance matches the reference distance, and limits the possible stroke range of the arm cylinder so that the tip distance does not become less than the reference distance.

11. The work machine according to claim 8, wherein, when the working tool is rotated in a direction such that a tip of the working tool approaches the boom cylinder, and when the tip distance would be less than the predetermined value if the working tool were rotated while keeping the stroke of the arm cylinder constant, the control device operates the arm cylinder to rotate the arm to a position where the tip distance is equal to or greater than the predetermined value.

12. The work machine according to claim 8, wherein, when the boom is rotated in a direction approaching the boom reference position, if the tip distance would be less than the predetermined value if the boom were rotated while keeping the rotational position of the work tool constant, the control device operates the arm cylinder to rotate the arm to a position where the tip distance is equal to or greater than the predetermined value.

13. The work machine according to any one of claims 1 to 12, wherein the control device limits the operating speed of the arm cylinder when the arm cylinder is caused to stroke beyond a possible stroke range at the boom reference position.

14. a boom that is pivotally supported about a first rotation axis on a swing bracket that is swingably attached about a vertical axis to a front part of a support bracket that protrudes forward from a front part of the body, a boom cylinder that rotates the boom about the first rotation axis, an arm that is pivotally supported about a second rotation axis parallel to the first rotation axis on a front part of the support bracket that protrudes forward from a front part of the body, an arm cylinder that rotates the arm about the second rotation axis, a working tool that is pivotally supported about a third rotation axis parallel to the first rotation axis on the front part of the arm, and a boom sensor that detects a rotation position of the boom about the first rotation axis, wherein the boom cylinder is disposed on one side of the boom and the arm cylinder is disposed on the other side of the boom, and the boom is a one-piece boom that does not have a joint between the base end and the tip end, A method for rotating a boom while varying the stroke range of the arm cylinder toward the boom in accordance with the boom rotation position so that even if the boom rotation position changes when rotating the boom, the shortest trajectory distance, which is the shortest distance between the rotation trajectory around the third rotation axis of the tip of the work tool and the boom cylinder, is kept constant at a predetermined value.

15. a boom that is rotatably supported about a first rotation axis extending horizontally on a swing bracket whose base end is attached to a front part of a support bracket that protrudes forward from a front part of the body so as to be swingable about a vertical axis, a boom cylinder that rotates the boom about the first rotation axis, an arm whose base end is rotatably supported about a second rotation axis parallel to the first rotation axis on a tip part of the boom, an arm cylinder that rotates the arm about the second rotation axis, a working tool that is rotatably supported about a third rotation axis parallel to the first rotation axis on the tip part of the arm, a boom sensor that detects a rotation position of the boom about the first rotation axis, and a working tool sensor that detects a rotation position of the working tool about the third rotation axis, wherein the boom cylinder is disposed on one side of the boom and the arm cylinder is disposed on the other side of the boom, and the boom is a one-piece boom that does not have a joint between the base end and the tip end, A method of rotating a boom while varying the stroke range of the arm cylinder toward the boom in accordance with the boom rotation position and the working tool rotation position so that the tip distance, which is the shortest distance between the tip of the working tool and the boom cylinder, is kept constant at a predetermined value even if the boom rotation position changes when rotating the boom.

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