Work machine and method for controlling a work machine

Abstract

To provide a work machine which can smoothly perform a small steering angle operation, can easily perform turning and straight-travelling operations.SOLUTION: A first steering member is operable into a left steering range, a right steering range, and a neutral range. The neutral range is positioned between the left steering range and the right steering range. A controller controls an actuator so as to change a steering angle of a running wheel to a left side at a speed according to an operation amount of the first steering member when the first steering member is positioned in the left steering range. The controller controls the actuator so as to change the steering angle of the running wheel to a right side at a speed according to the operation amount of the first steering member when the first steering member is positioned in the right steering range. The controller controls the actuator so as to return the steering angle to a neutral angle when the first steering member is positioned in the neutral range.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a work machine and a method for controlling a work machine. [Background technology]

[0002] A work machine is equipped with a steering member such as a steering wheel or a steering lever for steering the running wheels left and right. When the operator of the work machine operates the steering member, the work machine changes the steering angle of the running wheels left and right, causing the work machine to turn left and right.

[0003] Control of the steering angle by operating the steering member can be classified into a position control type and a speed control type. In the position control type, the steering angle is set to an angle corresponding to the amount of operation of the steering member. On the other hand, in the speed control type, as shown in Patent Document 1, the steering angle changes at a speed corresponding to the amount of operation of the steering member. For example, when the steering member is operated to the left from the neutral position by a predetermined amount, the steering angle changes at a speed corresponding to the predetermined amount of operation. Therefore, even if the operator maintains the steering member at the predetermined amount of operation, the steering angle continues to change to the left until it reaches the maximum steering angle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-054270 Summary of the Invention [Problem to be solved by the invention]

[0005] With the position control type described above, the operator can move the work machine in a straight line by returning the steering member to the neutral position. However, it is not easy to smoothly operate the steering angle by small increments. On the other hand, the speed control type has the advantage of being able to smoothly operate the steering angle by small increments. However, to move the work machine in a straight line after turning to the left or right, the operator must operate the steering member in the opposite direction to return the steering angle to the straight-line direction. Therefore, operating the work machine to turn and move in a straight line is not easy and requires skill. An object of the present invention is to provide a work machine that can smoothly operate the steering angle by small increments and that can easily be operated to turn and move in a straight line. [Means for solving the problem]

[0006] A work machine according to a first aspect of the present invention includes a vehicle body, running wheels, an actuator, a first steering member, and a controller. The running wheels are supported on the vehicle body. The actuator changes the steering angle of the running wheels to the left or right from a predetermined neutral angle. The first steering member is operable within a left steering range, a right steering range, and a neutral range. The neutral range is located between the left steering range and the right steering range. When the first steering member is located within the left steering range, the controller controls the actuator to change the steering angle of the running wheels to the left at a speed corresponding to the amount of operation of the first steering member. When the first steering member is located within the right steering range, the controller controls the actuator to change the steering angle of the running wheels to the right at a speed corresponding to the amount of operation of the first steering member. When the first steering member is located within the neutral range, the controller controls the actuator to return the steering angle to the neutral angle.

[0007] A method according to a second aspect of the present invention is a method for controlling a work machine. The work machine includes a vehicle body, running wheels, and an actuator. The running wheels are supported on the vehicle body. The actuator changes the steering angle of the running wheels to the left or right from a predetermined neutral angle. The method according to this aspect includes acquiring a signal indicating an operation amount of a first steering member that can be operated within a left steering range, a right steering range, and a neutral range between the left steering range and the right steering range, controlling the actuator to change the steering angle of the running wheels to the left at a speed corresponding to the operation amount of the first steering member when the first steering member is located within the left steering range, controlling the actuator to change the steering angle of the running wheels to the right at a speed corresponding to the operation amount of the first steering member when the first steering member is located within the right steering range, and controlling the actuator to return the steering angle to the neutral angle when the first steering member is located within the neutral range. [Effects of the Invention]

[0008] According to the present invention, when the first steering member is operated within the left operation range or the right operation range, the steering angle is controlled by speed control. This allows for smooth operation of small steering angles. Furthermore, when the first steering member is located within the neutral range, the steering angle is returned to the neutral angle. Therefore, after turning the work machine, the operator can easily steer the work machine straight by returning the first steering member to the neutral range. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of a work machine according to an embodiment. [Figure 2] FIG. 1 is a side view of a work machine. [Figure 3] FIG. 1 is a schematic diagram showing the configuration of a work machine. [Figure 4] FIG. 2 is a top view showing the front of the work machine. [Figure 5] FIG. 10 is a diagram showing an example of steering speed data. [Figure 6]FIG. 4 is a diagram showing an example of travel of a work machine caused by operation of a first steering member. [Figure 7] FIG. 10 is a diagram showing steering speed data according to a first modified example. [Figure 8] FIG. 10 is a diagram showing steering speed data according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a perspective view of a work machine 1 according to the embodiment. Fig. 2 is a side view of the work machine 1. As shown in Fig. 1, the work machine 1 includes a body 2, front wheels 3A, 3B, rear wheels 4A-4D, and a work implement 5. The body 2 includes a front frame 11, a rear frame 12, a cab 13, and a power compartment 14.

[0011] The rear frame 12 is connected to the front frame 11. The front frame 11 can articulate left and right relative to the rear frame 12. In the following description, the front, rear, left and right directions refer to the front, rear, left and right directions of the vehicle body 2 when the articulation angle is 0, that is, when the front frame 11 and rear frame 12 are straight.

[0012] The cab 13 and the power compartment 14 are disposed on the rear frame 12. A driver's seat (not shown) is disposed in the cab 13. The power compartment 14 is disposed behind the cab 13. The front frame 11 extends forward from the rear frame 12. The front wheels 3A, 3B are attached to the front frame 11. The rear wheels 4A-4D are attached to the rear frame 12.

[0013] The work implement 5 is movably connected to the vehicle body 2. The work implement 5 includes a support member 15 and a blade 16. The support member 15 is movably connected to the vehicle body 2. The support member 15 supports the blade 16. The support member 15 includes a draw bar 17 and a circle 18. The draw bar 17 is disposed below the front frame 11.

[0014] The drawbar 17 is connected to a front portion 19 of the front frame 11. The drawbar 17 extends rearward from the front portion 19 of the front frame 11. The drawbar 17 is supported relative to the front frame 11 so as to be swingable at least in the up-down direction and the left-right direction of the vehicle body 2. For example, the front portion 19 includes a ball joint. The drawbar 17 is rotatably connected to the front frame 11 via the ball joint.

[0015] The circle 18 is connected to the rear of the drawbar 17. The circle 18 is supported rotatably relative to the drawbar 17. The blade 16 is connected to the circle 18. The blade 16 is supported by the drawbar 17 via the circle 18. As shown in FIG. 2 , the blade 16 is supported by the circle 18 rotatably around a tilt shaft 21. The tilt shaft 21 extends in the left-right direction.

[0016] The work machine 1 is equipped with a plurality of actuators 22-26 for changing the attitude of the work implement 5. The plurality of actuators 22-26 include a plurality of hydraulic cylinders 22-25. The plurality of hydraulic cylinders 22-25 are connected to the work implement 5. The plurality of hydraulic cylinders 22-25 extend and retract by hydraulic pressure. The extension and retraction of the plurality of hydraulic cylinders 22-25 changes the attitude of the work implement 5 relative to the vehicle body 2. In the following description, the extension and retraction of the hydraulic cylinders will be referred to as "stroke operation."

[0017] In detail, the multiple hydraulic cylinders 22-25 include a left lift cylinder 22, a right lift cylinder 23, a drawbar shift cylinder 24, and a blade tilt cylinder 25. The left lift cylinder 22 and the right lift cylinder 23 are arranged spaced apart from each other in the left-right direction. The left lift cylinder 22 and the right lift cylinder 23 are connected to the drawbar 17. The left lift cylinder 22 and the right lift cylinder 23 are connected to the front frame 11 via a lifter bracket 29. The stroke movement of the left lift cylinder 22 and the right lift cylinder 23 causes the drawbar 17 to swing up and down. As a result, the blade 16 moves up and down.

[0018] The drawbar shift cylinder 24 is connected to the drawbar 17 and the front frame 11. The drawbar shift cylinder 24 is connected to the front frame 11 via a lifter bracket 29. The drawbar shift cylinder 24 extends obliquely downward from the front frame 11 toward the drawbar 17. The stroke movement of the drawbar shift cylinder 24 causes the drawbar 17 to swing left and right. The blade tilt cylinder 25 is connected to the circle 18 and the blade 16. The stroke movement of the blade tilt cylinder 25 causes the blade 16 to rotate around the tilt axis 21.

[0019] The multiple actuators 22-26 include a rotary actuator 26. The rotary actuator 26 is connected to the draw bar 17 and the circle 18. The rotary actuator 26 rotates the circle 18 relative to the draw bar 17. This causes the blade 16 to rotate around a rotation axis extending in the vertical direction.

[0020] Fig. 3 is a schematic diagram showing the configuration of the work machine 1. As shown in Fig. 3, the work machine 1 includes a drive source 31, a first hydraulic pump 32, a power transmission device 33, and a work machine valve 34. The drive source 31 is, for example, an internal combustion engine. Alternatively, the drive source 31 may be an electric motor, or a hybrid of an internal combustion engine and an electric motor. The first hydraulic pump 32 is driven by the drive source 31 to discharge hydraulic oil.

[0021] The work implement valve 34 is connected to the first hydraulic pump 32 and the plurality of hydraulic cylinders 22-25 via a hydraulic circuit. The work implement valve 34 includes a plurality of valves connected to the plurality of hydraulic cylinders 22-25, respectively. The work implement valve 34 controls the flow rate of hydraulic oil supplied from the first hydraulic pump 32 to the plurality of hydraulic cylinders 22-25. The work implement valve 34 is, for example, an electromagnetic proportional control valve. Alternatively, the work implement valve 34 may be a hydraulic pilot type proportional control valve.

[0022] In this embodiment, the rotary actuator 26 is a hydraulic motor. The work implement valve 34 is connected to the first hydraulic pump 32 and the rotary actuator 26 via a hydraulic circuit. The work implement valve 34 controls the flow rate of hydraulic oil supplied from the first hydraulic pump 32 to the rotary actuator 26. The rotary actuator 26 may also be an electric motor.

[0023] The power transmission device 33 transmits driving force from the drive source 31 to the rear wheels 4A-4D. The power transmission device 33 may include a torque converter and / or a plurality of speed change gears. Alternatively, the power transmission device 33 may be a transmission such as an HST (Hydraulic Static Transmission) or an HMT (Hydraulic Mechanical Transmission).

[0024] The work machine 1 includes a work implement operation member 35, an accelerator operation member 36, and a controller 37. The work implement operation member 35 can be operated by the operator to change the attitude of the work implement 5. The work implement operation member 35 includes, for example, a plurality of operation levers. Alternatively, the work implement operation member 35 may be another member such as a switch or a touch panel. The work implement operation member 35 outputs a signal indicating an operation of the work implement operation member 35 by the operator.

[0025] The accelerator operating member 36 can be operated by the operator to drive the work machine 1. The accelerator operating member 36 includes, for example, an accelerator pedal. Alternatively, the accelerator operating member 36 may be another member such as a switch or a touch panel. The accelerator operating member 36 outputs a signal indicating operation of the accelerator operating member 36 by the operator.

[0026] The controller 37 controls the drive source 31 and the power transmission device 33 in response to operation of the accelerator operating member 36, thereby causing the work machine 1 to travel. The controller 37 also controls the first hydraulic pump 32 and the work machine valve 34 in response to operation of the work machine operating member 35, thereby causing the work machine 5 to operate.

[0027] The controller 37 includes a storage device 38 and a processor 39. The processor 39 is, for example, a CPU, and executes programs for controlling the work machine 1. The storage device 38 includes memory such as RAM and ROM, and an auxiliary storage device such as an SSD or HDD. The storage device 38 stores programs and data for controlling the work machine 1.

[0028] As shown in Fig. 3, the work machine 1 is equipped with a steering angle sensor 40, a steering actuator 41, and a steering valve 42. The steering actuator 41 is a hydraulic cylinder. The steering actuator 41 expands and contracts using hydraulic oil from the first hydraulic pump 32. The steering actuator 41 steers the front wheels 3A, 3B by expanding and contracting.

[0029] Figure 4 is a top view showing the front of the work machine 1. As shown in Figure 4, the front wheels 3A, 3B include a first front wheel 3A and a second front wheel 3B. The first front wheel 3A and the second front wheel 3B are arranged apart in the left-right direction. The first front wheel 3A is supported by the front frame 11 so as to be rotatable about a first steering shaft 43. The second front wheel 3B is supported by the front frame 11 so as to be rotatable about a second steering shaft 44. The first steering shaft 43 and the second steering shaft 44 extend in the vertical direction.

[0030] The steering actuator 41 is connected to the front wheels 3A, 3B and the front frame 11. The steering actuator 41 changes the steering angle θ1 of the front wheels 3A, 3B to the left and right from a predetermined neutral angle. As shown in FIG. 4, the steering angle θ1 is the angle of the direction of the front wheels 3A, 3B relative to the fore-and-aft direction of the work machine 1. The fore-and-aft direction of the work machine 1 refers to the fore-and-aft direction of the front frame 11. However, the fore-and-aft direction of the work machine 1 may also refer to the fore-and-aft direction of the rear frame 12.

[0031] The neutral angle is a steering angle θ1 of 0 degrees. Therefore, when the steering angle θ1 is the neutral angle, it means that the front wheels 3A, 3B are facing directly ahead of the work machine 1. In FIG. 4, 3A' indicates the first front wheel 3A that has been steered to the left from the neutral angle by the steering angle θ1. 3B' indicates the second front wheel 3B that has been steered to the left from the neutral angle by the steering angle θ1.

[0032] The steering valve 42 is connected via a hydraulic circuit to the first hydraulic pump 32 and the steering actuator 41. The steering valve 42 controls the flow rate of hydraulic oil supplied from the first hydraulic pump 32 to the steering actuator 41. The steering valve 42 is a hydraulic pilot type control valve.

[0033] The steering angle sensor 40 detects the steering angle θ1. The steering angle sensor 40 outputs an angle signal indicating the steering angle θ1. The steering angle sensor 40 detects, for example, the stroke amount of the steering actuator 41. The steering angle θ1 is calculated from the stroke amount of the steering actuator 41. Alternatively, the steering angle sensor 40 may directly detect the steering angle θ1.

[0034] The work machine 1 includes a first steering member 45 and a second steering member 46. The first steering member 45 and the second steering member 46 can be operated by an operator to change the steering angle θ1 of the front wheels 3A, 3B to the left or right. The first steering member 45 is a lever such as a joystick. Alternatively, the first steering member 45 may be a member other than a lever. The first steering member 45 can be tilted to the left or right from a neutral position N1. The first steering member 45 outputs a first operation signal that indicates the operation of the first steering member 45 by the operator.

[0035] The second steering member 46 is a steering wheel. Alternatively, the second steering member 46 may be a member other than a steering wheel. The second steering member 46 is rotatable around a rotation axis Ax1. An operation sensor 47 is attached to the second steering member 46. The operation sensor 47 outputs a second operation signal that indicates an operation of the second steering member 46 by the operator. The operation sensor 47 detects, for example, an angular displacement of the second steering member 46 around the rotation axis Ax1.

[0036] The work machine 1 includes a second hydraulic pump 48, a first pilot valve 49, and a second pilot valve 50. The second hydraulic pump 48 is driven by the drive source 31 to discharge hydraulic oil. The first pilot valve 49 is connected to the second hydraulic pump 48 and the steering valve 42 via a hydraulic circuit. The first pilot valve 49 controls the pressure of the hydraulic oil supplied from the second hydraulic pump 48 to the pilot port of the steering valve 42. The first pilot valve 49 is an electromagnetic proportional control valve.

[0037] The first pilot valve 49 is controlled by a signal from the controller 37. The controller 37 controls the first pilot valve 49 in response to a first operation signal from the first steering member 45, thereby extending or retracting the steering actuator 41. As a result, the controller 37 controls the steering actuator 41 in response to the operation of the first steering member 45 so as to change the steering angle θ1 of the front wheels 3A, 3B. The control of the steering angle θ1 by the first steering member 45 will be described in detail later.

[0038] The second pilot valve 50 is connected to the second hydraulic pump 48 and the steering valve 42 via a hydraulic circuit. The second pilot valve 50 is connected to the second steering member 46. The second pilot valve 50 controls the pressure of the hydraulic oil supplied from the second hydraulic pump 48 to the pilot port of the steering valve 42 in accordance with the operation of the second steering member 46. As a result, the steering actuator 41 changes the steering angle θ1 of the front wheels 3A, 3B so that the steering angle θ1 of the front wheels 3A, 3B becomes an angle corresponding to the amount of operation of the second steering member 46.

[0039] When the amount of operation of the second steering member 46 is held constant, the steering actuator 41 holds the steering angle θ1 of the front wheels 3A, 3B at an angle that corresponds to the amount of operation of the second steering member 46. Note that the second pilot valve 50 may be an electromagnetic proportional control valve, similar to the first pilot valve 49. In that case, the controller 37 may control the second pilot valve 50 in accordance with the operation of the second steering member 46.

[0040] Next, the control of the steering angle θ1 by the first steering member 45 will be described. The controller 37 obtains the operation amount of the first steering member 45 from a first operation signal from the first steering member 45. The controller 37 obtains the current steering angle θ1 from a signal from the steering angle sensor 40. The controller 37 determines a target steering speed from the operation amount of the first steering member 45 by referring to the steering speed data. The controller 37 controls the steering actuator 41 so that the steering angle θ1 changes at the target steering speed. The steering speed data defines the target steering speed relative to the operation amount of the first steering member 45.

[0041] FIG. 5 is a diagram showing an example of steering speed data. As shown in FIG. 5, the first steering member 45 can be operated within a neutral range, a left steering range, and a right steering range. The neutral range is a range that includes a position where the operation amount of the first steering member 45 is 0, i.e., a neutral position N1. The neutral range is located between the left steering range and the right steering range. The left steering range is located to the left of the neutral range. The right steering range is located to the right of the neutral range.

[0042] The steering speed data defines a target leftward steering speed that increases between 0 and a maximum leftward speed VL in accordance with an increase in the leftward operation amount of the first steering member 45 within the left steering range. Therefore, when the first steering member 45 is located within the left steering range, the controller 37 controls the steering actuator 41 to change the steering angle θ1 of the front wheels 3A, 3B to the left at a speed that corresponds to the operation amount of the first steering member 45.

[0043] For example, when the first steering member 45 is operated to the left by an amount A1, the controller 37 determines a steering speed V1 corresponding to the amount A1 as the target steering speed. Then, the controller 37 controls the steering actuator 41 to change the steering angle θ1 of the front wheels 3A, 3B to the left at the steering speed V1. Furthermore, while the first steering member 45 is maintained at the amount A1 to the left, the steering angle θ1 of the front wheels 3A, 3B continues to change to the left at the steering speed V1 until it reaches the maximum steering angle to the left.

[0044] The steering speed data defines a target rightward steering speed that increases between 0 and a maximum rightward speed VR in accordance with an increase in the amount of rightward operation of the first steering member 45 within the rightward steering range. Therefore, when the first steering member 45 is located within the rightward steering range, the controller 37 controls the steering actuator 41 to change the steering angle θ1 of the front wheels 3A, 3B to the right at a speed that corresponds to the amount of rightward operation of the first steering member 45.

[0045] For example, when the first steering member 45 is operated to the right by an amount of operation A2, the controller 37 determines a steering speed V2 corresponding to the amount of operation A2 as the target steering speed. Then, the controller 37 controls the steering actuator 41 to change the steering angle θ1 of the front wheels 3A, 3B to the right at the steering speed V2. Furthermore, while the first steering member 45 is maintained at the amount of operation A2 to the right, the steering angle θ1 of the front wheels 3A, 3B continues to change to the right at the steering speed V2 until it reaches the maximum steering angle to the right.

[0046] When the first steering member 45 is located within the neutral range, the controller 37 controls the steering actuator 41 to maintain the steering angle θ1 at the neutral angle. For example, when the first steering member 45 is located within the neutral range when the steering angle θ1 is the neutral angle, the steering angle θ1 does not change and is maintained at the neutral angle.

[0047] When the first steering member 45 is positioned within the neutral range but the steering angle θ1 is not the neutral angle, the controller 37 controls the steering actuator 41 in an auto mode in which the steering angle θ1 is automatically returned to the neutral angle.

[0048] For example, when the steering angle θ1 is at a predetermined angle to the left and the first steering member 45 is returned to the neutral range, the controller 37 controls the steering actuator 41 so that the steering angle θ1 returns from the predetermined angle to the left to the neutral angle. When the steering angle θ1 is at a predetermined angle to the right and the first steering member 45 is returned to the neutral range, the controller 37 controls the steering actuator 41 so that the steering angle θ1 returns from the predetermined angle to the right to the neutral angle.

[0049] When the first steering member 45 and the second steering member 46 are operated simultaneously, the controller 37 prioritizes the operation of the second steering member 46. Therefore, when the first steering member 45 and the second steering member 46 are operated simultaneously, the controller 37 does not control the steering angle θ1 by the first steering member 45 as described above. Therefore, the steering angle θ1 changes in accordance with the operation of the second steering member 46.

[0050] FIG. 6 is a diagram showing an example of the traveling of the work machine 1 due to operation of the first steering member 45. As shown in FIG. 6, when the work machine 1 is at point P1, the first steering member 45 is located in the neutral position N1. The steering angle θ1 is the neutral angle, and the work machine 1 is traveling straight. At point P2, when the operator operates the first steering member 45 to an operation amount A1 within the left operation range, the steering angle θ1 of the front wheels 3A, 3B begins to change from the neutral angle to the left. This causes the work machine 1 to turn left.

[0051] Between points P2 and P3, when the operator maintains the first steering member 45 at the operation amount A1, the steering angle θ1 of the front wheels 3A, 3B continues to increase up to the maximum steering angle θmax to the left. As a result, the work machine 1 continues to turn to the left. Then, when the operator returns the first steering member 45 to the neutral range at point P3, the steering angle θ1 of the front wheels 3A, 3B decreases from the maximum steering angle θmax towards the neutral angle due to the auto mode. Then, at point P5, the steering angle θ1 of the front wheels 3A, 3B returns to the neutral angle. As a result, the work machine 1 moves straight ahead.

[0052] In the work machine 1 according to the present embodiment described above, when the first steering member 45 is operated within the left operation range or the right operation range, the steering angle θ1 is controlled using speed control. This allows for smooth operation of small steering angles θ1. Furthermore, when the first steering member 45 is located within the neutral range, the steering angle θ1 is returned to the neutral angle. Therefore, after turning the work machine 1, the operator can easily make the work machine 1 travel straight by returning the first steering member 45 to the neutral range.

[0053] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0054] The work machine 1 is not limited to a motor grader, but may be other work machines such as a wheel loader, a dump truck, or a forklift. The number of steering actuators 41 is not limited to one, but may be two or more. The steering actuator 41 is not limited to a hydraulic cylinder, but may be a hydraulic motor or an electric motor.

[0055] The steering speed data is not limited to that of the above embodiment and may be modified. For example, FIG. 7 is a diagram showing steering speed data according to a first modified example. As shown in FIG. 7, the steering speed data may have inflection points B1 and B2 within the left steering range and the right steering range. That is, within the left steering range, the rate of increase in the target steering speed to the left relative to the amount of operation to the left may change with inflection point B1 as the boundary. Within the right steering range, the rate of increase in the target steering speed to the right relative to the amount of operation to the right may change with inflection point B2 as the boundary.

[0056] Fig. 8 is a diagram showing steering speed data according to a second modified example. As shown in Fig. 8, the first steering member 45 may be operable to a left hold range and a right hold range. The left hold range is located between the neutral range and the left steering range. The right hold range is located between the neutral range and the right steering range.

[0057] When the first steering member 45 is located within the left hold range, the controller 37 may control the actuator to maintain the steering angle θ1 of the front wheels 3A, 3B at the current angle. For example, if the operator operates the first steering member 45 from within the left steering range into the left hold range when the steering angle θ1 of the front wheels 3A, 3B is at a predetermined angle to the left, the controller 37 maintains the steering angle θ1 of the front wheels 3A, 3B at the predetermined angle to the left. When the operator returns the first steering member 45 from within the left hold range to the neutral range, the controller 37 controls the steering actuator 41 to change the steering angle θ1 of the front wheels 3A, 3B from the predetermined angle to the left to the neutral angle.

[0058] When the first steering member 45 is located within the right hold range, the controller 37 may control the actuator to maintain the steering angle θ1 of the front wheels 3A, 3B at the current angle. For example, when the steering angle θ1 of the front wheels 3A, 3B is at a predetermined angle to the right, if the operator operates the first steering member 45 from within the right steering range into the right hold range, the controller 37 maintains the steering angle θ1 of the front wheels 3A, 3B at the predetermined angle to the right. When the operator returns the first steering member 45 from the right hold range to the neutral range, the controller 37 controls the steering actuator 41 to change the steering angle θ1 of the front wheels 3A, 3B from the predetermined angle to the right to the neutral angle. [Industrial Applicability]

[0059] According to the present invention, a work machine is provided that can smoothly perform minute steering angle operations and can easily perform turning and straight-line operations. [Explanation of symbols]

[0060] 2: Body 3A,3B: Front wheel 37: Controller 41: Steering actuator 45: First steering member 46: Second steering member

Claims

1. The car body and a running wheel supported on the vehicle body; an actuator that changes the steering angle of the running wheels to the left or right from a predetermined neutral angle; a first steering member operable within a left steering range, a right steering range, and a neutral range between the left steering range and the right steering range; A controller; Equipped with The controller When the first steering member is located within the left steering range, the actuator is controlled to change the steering angle of the running wheels to the left at a speed corresponding to an operation amount of the first steering member; When the first steering member is located within the right steering range, the actuator is controlled to change the steering angle of the running wheels to the right at a speed corresponding to an operation amount of the first steering member; When the first steering member is located within the neutral range, the actuator is controlled to return the steering angle to the neutral angle. Work machinery.

2. the first steering member is operable to a left hold range between the neutral range and the left steering range, When the first steering member is located within the left hold range, the controller controls the actuator to maintain the steering angle of the running wheels at a current angle.

2. The work machine according to claim 1.

3. the first steering member is operable to a right hold range between the neutral range and the right steering range, When the first steering member is located within the right hold range, the controller controls the actuator to maintain the steering angle of the traveling wheels at a current angle.

3. A work machine according to claim 1 or 2.

4. Further provided is a second steering member that can be operated left and right from a neutral position, The actuator changes the steering angle of the running wheels so that the steering angle of the running wheels becomes an angle corresponding to an operation amount of the second steering member. A work machine according to any one of claims 1 to 3.

5. the controller changes the steering angle of the running wheels by prioritizing the operation of the second steering member over the operation of the first steering member.

5. The work machine according to claim 4.

6. A method for controlling a work machine including a vehicle body, running wheels supported on the vehicle body, and an actuator that changes a steering angle of the running wheels to the left or right from a predetermined neutral angle, comprising: acquiring a signal indicating an operation amount of a first steering member that can be operated in a left steering range, a right steering range, and a neutral range between the left steering range and the right steering range; When the first steering member is located within the left steering range, controlling the actuator so as to change the steering angle of the running wheels to the left at a speed corresponding to an operation amount of the first steering member; When the first steering member is located within the right steering range, controlling the actuator so as to change the steering angle of the running wheels to the right at a speed corresponding to an operation amount of the first steering member; When the first steering member is located within the neutral range, controlling the actuator to return the steering angle to the neutral angle; A method for providing

7. the first steering member is operable to a left hold range between the neutral range and the left steering range, and controlling the actuator so as to maintain the steering angle of the running wheels at a current angle when the first steering member is located within the left hold range. The method of claim 6.

8. the first steering member is operable to a right hold range between the neutral range and the right steering range, and controlling the actuator so as to maintain the steering angle of the running wheels at a current angle when the first steering member is located within the right hold range.

8. The method according to claim 6 or 7.

9. further comprising receiving a signal indicating an operation amount of a second steering member that can be operated left or right from a neutral position, The actuator changes the steering angle of the running wheels so that the steering angle of the running wheels becomes an angle corresponding to an operation amount of the second steering member.

9. The method according to any one of claims 6 to 8.

10. The method further includes changing the steering angle of the running wheels by prioritizing the operation of the second steering member over the operation of the first steering member.

10. The method of claim 9.

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