Motor grader control system and method

Abstract

To improve the operability of a motor grader.SOLUTION: A system comprises a lift operation component, a sensor and a controller. The lift operation component is operated to raise and lower a blade with a lift cylinder. The sensor acquires actual pitch angles of the blade against the vehicle body. In the case where the lift operation component is operated for a designated duration or longer while the vehicle body is traveling, and then is returned to the neutral position, the controller controls the lift cylinder to execute an automatic blade control for raising or lowering the blade to a designated target position. The controller acquires an actual pitch angle of the blade against the vehicle body. The controller acquires a target pitch angle of the blade against the vehicle body according to the target point. The controller controls, in the automatic blade control, the variation speed of the actual pitch angle according to the actual pitch angel so that the actual pitch angle becomes the target pitch angle.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present disclosure relates to a system and method for controlling a motor grader.

Background Art

[0002] A motor grader includes a blade, a lift cylinder, and a lift operating member. The lift cylinder raises and lowers the blade. The lift operating member is operated to raise and lower the blade by the lift cylinder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A motor grader may perform an operation in which the blade is placed near the ground, moves forward to level the ground or smooth the surface, then raises the blade, moves backward, and then moves forward again to repeat the leveling or surface smoothing operation. In such a case, it is not easy for an operator to simultaneously perform the operation of raising the blade during backward movement or lowering the blade during forward movement and other operations such as a steering operation. The object of the present disclosure is to improve the operability of a motor grader.

Means for Solving the Problems

[0005] A system according to one aspect of the present disclosure is a system for controlling a motor grader. The motor grader includes a vehicle body, a working machine, and a lift cylinder. The vehicle body includes traveling wheels. The working machine is operably connected to the vehicle body and includes a blade. The lift cylinder is connected to the working machine and raises and lowers the blade. The system includes a lift operation member, a sensor, and a controller. The lift operation member is operated to raise and lower the blade by the lift cylinder. The sensor acquires the actual pitch angle of the blade with respect to the vehicle body. The controller is capable of receiving a signal corresponding to the operation of the lift operation member. When the vehicle body is traveling and the lift operation member returns to the neutral position after being operated for a predetermined continuous time or more, the controller controls the lift cylinder to perform automatic blade control to raise or lower the blade to a predetermined target position. The controller acquires the actual pitch angle of the blade with respect to the vehicle body. The controller acquires the target pitch angle of the blade with respect to the vehicle body according to the target position. In the automatic blade control, the controller controls the change speed of the actual pitch angle according to the actual pitch angle so that the actual pitch angle becomes the target pitch angle.

[0006] A method according to another aspect of the present disclosure is a method for controlling a motor grader. The motor grader includes a vehicle body, a working machine, and a lift cylinder. The vehicle body includes traveling wheels. The working machine is operably connected to the vehicle body and includes a blade. The lift cylinder is connected to the working machine and raises and lowers the blade. The method includes receiving a signal corresponding to the operation of a lift operation member that is operated to raise and lower the blade by the lift cylinder, performing automatic blade control to control the lift cylinder to raise or lower the blade to a predetermined target position when the vehicle body is traveling and the lift operation member returns to the neutral position after being operated for a predetermined continuous time or more, acquiring the actual pitch angle of the blade with respect to the vehicle body, acquiring the target pitch angle of the blade with respect to the vehicle body according to the target position, and controlling the change speed of the actual pitch angle according to the actual pitch angle so that the actual pitch angle becomes the target pitch angle in the automatic blade control.

Advantages of the Invention

[0007] According to the present disclosure, when the vehicle body is traveling, after the lift operation member is operated by the operator for a predetermined continuous time or more and then returns to the neutral position, the blade automatically moves to the target position by automatic blade control. Therefore, other operations such as steering operations become easier. Further, the change speed of the actual pitch angle of the blade is controlled according to the actual pitch angle. Therefore, the blade can be raised to the target position quickly and accurately. Thereby, the operability of the motor grader is improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10A

Figure 10B

Figure 10C

Figure 11

Figure 12A

Figure 12B

Figure 12C

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a perspective view of a motor grader 1 according to an embodiment. FIG. 2 is a side view of the motor grader 1. As shown in FIG. 1, the motor grader 1 includes a vehicle body 2, a plurality of traveling wheels 3A, 3B, 4A - 4D, and a working machine 5. The vehicle body 2 includes a front frame 11, a rear frame 12, a cab 13, and a power chamber 14. The plurality of traveling wheels 3A, 3B, 4A - 4D include front wheels 3A, 3B and rear wheels 4A - 4D.

[0010] The rear frame 12 is connected to the front frame 11. The front frame 11 is articulable left and right with respect to the rear frame 12. The cab 13 and the power chamber 14 are disposed on the rear frame 12. A driver's seat (not shown) is disposed in the cab 13. The power chamber 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.

[0011] The working machine 5 is operably connected to the vehicle body 2. The working machine 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 drawbar 17 and a circle 18. The drawbar 17 is disposed below the front frame 11.

[0012] The drawbar 17 is connected to the 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 by the front frame 11 so as to be swingable at least in the vertical and horizontal directions 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.

[0013] The circle 18 is connected to the rear portion of the drawbar 17. The circle 18 is rotatably supported by 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 rotatably supported by the circle 18 around the tilt axis 21. The tilt axis 21 extends in the left - right direction.

[0014] The motor grader 1 includes a plurality of actuators 22 - 26 for changing the attitude of the working machine 5. The plurality of actuators 22 - 26 includes a plurality of hydraulic cylinders 22 - 25. The plurality of hydraulic cylinders 22 - 25 are connected to the working machine 5. The plurality of hydraulic cylinders 22 - 25 expand and contract by hydraulic pressure. By expanding and contracting, the plurality of hydraulic cylinders 22 - 25 change the attitude of the working machine 5 with respect to the vehicle body 2. In the following description, the expansion and contraction of the hydraulic cylinder is called a "stroke operation".

[0015] Specifically, the plurality of 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 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. Due to the stroke operation of the left lift cylinder 22 and the right lift cylinder 23, the drawbar 17 swings up and down. Thereby, the blade 16 moves up and down.

[0016] 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. Due to the stroke operation of the drawbar shift cylinder 24, the drawbar 17 swings left and right. The blade tilt cylinder 25 is connected to the circle 18 and the blade 16. Due to the stroke operation of the blade tilt cylinder 25, the blade 16 rotates around the tilt axis 21.

[0017] The plurality of actuators 22-26 include a rotary actuator 26. The rotary actuator 26 is connected to the drawbar 17 and the circle 18. The rotary actuator 26 rotates the circle 18 with respect to the drawbar 17. Thereby, the blade 16 rotates around a rotation axis extending in the up-down direction.

[0018] Figure 3 is a schematic diagram showing the configuration of the drive system of the motor grader 1. Figure 4 is a schematic diagram showing the configuration of the control system of the motor grader 1. As shown in Figure 3, the motor grader 1 includes a drive source 31, a hydraulic pump 32, a power transmission device 33, and a work implement 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 hydraulic pump 32 discharges hydraulic oil when driven by the drive source 31.

[0019] The work implement valve 34 is connected to the hydraulic pump 32 and a plurality of hydraulic cylinders 22-25 via a hydraulic circuit. The work implement valve 34 includes a plurality of valves respectively connected to the plurality of hydraulic cylinders 22-25. The work implement valve 34 controls the flow rate of the hydraulic oil supplied from the 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.

[0020] The rotary actuator 26 is a hydraulic motor. The work implement valve 34 is connected to the hydraulic pump 32 and the rotary actuator 26 via a hydraulic circuit. The work implement valve 34 controls the flow rate of the hydraulic oil supplied from the hydraulic pump 32 to the rotary actuator 26. Alternatively, the rotary actuator 26 may be an electric motor.

[0021] The power transmission device 33 transmits the 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 transmission gears. Alternatively, the power transmission device 33 may be another transmission such as an HST (Hydraulic Static Transmission) or an HMT (Hydraulic Mechanical Transmission).

[0022] The motor grader 1 includes a steering cylinder 35 and a steering valve 36. The steering cylinder 35 is a hydraulic cylinder. The steering cylinder 35 expands and contracts by the hydraulic oil from the hydraulic pump 32. The steering cylinder 35 expands and contracts to steer the front wheels 3A and 3B left and right.

[0023] The steering valve 36 is connected to the hydraulic pump 32 and the steering cylinder 35 via a hydraulic circuit. The steering valve 36 controls the flow rate of the hydraulic oil supplied from the hydraulic pump 32 to the steering cylinder 35. The steering valve 36 is an electromagnetic control valve. Alternatively, the steering valve 36 may be a hydraulic pilot control valve.

[0024] The motor grader 1 includes articulation cylinders 37A and 37B and an articulation valve 38. The articulation valve 38 is a hydraulic cylinder. The articulation valve 38 expands and contracts by the hydraulic oil from the hydraulic pump 32. As shown by the dashed-dotted line in FIGS. 5 and 6, when the articulation cylinders 37A and 37B expand and contract, the front frame 11 articulates left and right with respect to the rear frame 12.

[0025] The articulation valve 38 is connected to the hydraulic pump 32 and the articulation cylinders 37A and 37B via a hydraulic circuit. The articulation valve 38 controls the flow rate of the hydraulic oil supplied from the hydraulic pump 32 to the articulation cylinders 37A and 37B. The articulation valve 38 is an electromagnetic control valve. Alternatively, the articulation valve 38 may be a hydraulic pilot control valve.

[0026] As shown in FIG. 4, the motor grader 1 includes a controller 40. The controller 40 includes a storage device 401 and a processor 402. The processor 402 is, for example, a CPU and executes a program for controlling the motor grader 1. The storage device 401 includes a memory such as a RAM and a ROM, and an auxiliary storage device such as an SSD or an HDD. The storage device 401 stores a program and data for controlling the motor grader 1.

[0027] The motor grader 1 includes an accelerator operation member 41, an FNR switching member 42, a steering operation member 43, and an articulation operation member 44. The accelerator operation member 41 is operable by an operator to run the motor grader 1. The accelerator operation member 41 includes, for example, an accelerator pedal. Alternatively, the accelerator operation member 41 may be another member such as a switch or a lever. The accelerator operation member 41 outputs a signal corresponding to an operation of the accelerator operation member 41 by the operator to the controller 40. The controller 40 controls the drive source 31 and the power transmission device 33 in response to the operation of the accelerator operation member 41 to run the motor grader 1.

[0028] The FNR switching member 42 is operable by an operator to switch between forward and reverse of the motor grader 1. The FNR switching member 42 is operable to a neutral position, a forward position, and a reverse position. The FNR switching member 42 includes, for example, a switch. Alternatively, the FNR switching member 42 may be another member such as a lever. The FNR switching member 42 outputs a signal corresponding to an operation of the FNR switching member 42 by the operator to the controller 40. The controller 40 controls the power transmission device 33 in response to the operation of the FNR switching member 42 to switch between forward and reverse of the motor grader 1.

[0029] The steering operation member 43 is operable by an operator to steer the front wheels 3A and 3B left and right. The steering operation member 43 is a lever such as a joystick. Alternatively, the steering operation member 43 may be a member other than a lever such as a steering wheel. The steering operation member 43 outputs a signal corresponding to an operation on the steering operation member 43 to the controller 40. The controller 40 controls the steering cylinder 35 in response to an operation on the steering operation member 43 to steer the front wheels 3A and 3B left and right.

[0030] The articulation operation member 44 is operable by an operator to articulate the front frame 11 left and right with respect to the rear frame 12. The articulation operation member 44 is a lever. Alternatively, the articulation operation member 44 may be another member such as a switch. The articulation operation member 44 outputs a signal corresponding to an operation on the articulation operation member 44 to the controller 40. The controller 40 controls the articulation cylinders 37A and 37B in response to an operation on the articulation operation member 44 to articulate the front frame 11 left and right with respect to the rear frame 12.

[0031] The motor grader 1 includes a left lift operation member 45 and a right lift operation member 46. The left lift operation member 45 and the right lift operation member 46 are, for example, levers. Alternatively, the left lift operation member 45 and the right lift operation member 46 may be other members such as switches.

[0032] The left lift operation member 45 is operated by an operator to raise and lower the blade 16 by means of the left lift cylinder 22. The right lift operation member 46 is operated by an operator to raise and lower the blade 16 by means of the right lift cylinder 23. Each of the left lift operation member 45 and the right lift operation member 46 is operable to a blade raising position, a neutral position, and a blade lowering position. Each of the left lift operation member 45 and the right lift operation member 46 outputs a signal corresponding to the operation of each operation member 45, 46 by the operator to the controller 40.

[0033] The controller 40 controls the left lift cylinder 22 in response to an operation on the left lift operation member 45 to raise and lower the left end portion of the blade 16. Specifically, when the left lift operation member 45 is operated to the blade raising position, the controller 40 controls the left lift cylinder 22 to raise the left end portion of the blade 16 at a speed corresponding to the operation amount of the left lift operation member 45. When the left lift operation member 45 is operated to the blade lowering position, the controller 40 controls the left lift cylinder 22 to lower the left end portion of the blade 16 at a speed corresponding to the operation amount of the left lift operation member 45.

[0034] The controller 40 raises and lowers the right end portion of the blade 16 in response to an operation on the right lift operation member 46. Specifically, when the right lift operation member 46 is operated to the blade raising position, the controller 40 controls the right lift cylinder 23 to raise the right end portion of the blade 16 at a speed corresponding to the operation amount of the right lift operation member 46. When the right lift operation member 46 is operated to the blade lowering position, the controller 40 controls the right lift cylinder 23 to lower the right end portion of the blade 16 at a speed corresponding to the operation amount of the right lift operation member 46.

[0035] The motor grader 1 includes a dozer shift operation member 47, a rotation operation member 48, and a blade tilt operation member 49. The dozer shift operation member 47, the rotation operation member 48, and the blade tilt operation member 49 are, for example, levers. Alternatively, the dozer shift operation member 47, the rotation operation member 48, and the blade tilt operation member 49 may be other members such as switches.

[0036] The dozer shift operation member 47 is operated by the operator to swing the dozer 17 left and right. The rotation operation member 48 is operated by the operator to rotate the circle 18 relative to the dozer 17. The blade tilt operation member 49 is operated by the operator to rotate the blade 16 around the tilt axis 21. Each of the dozer shift operation member 47, the rotation operation member 48, and the blade tilt operation member 49 outputs a signal corresponding to the operation of each operation member 43 - 46 by the operator to the controller 40.

[0037] The controller 40 controls the dozer shift cylinder 24 in response to an operation on the dozer shift operation member 47 to swing the dozer 17 left and right. The controller 40 controls the rotation actuator 26 in response to an operation on the rotation operation member 48 to rotate the circle 18. The controller 40 controls the blade tilt cylinder 25 in response to an operation on the blade tilt operation member 49 to rotate the blade 16 around the tilt axis 21.

[0038] The motor grader 1 includes a first attitude sensor 51 and a second attitude sensor 52. The first attitude sensor 51 detects the attitude of the vehicle body 2. The second attitude sensor 52 detects the attitude of the working machine 5. The first attitude sensor 51 and the second attitude sensor 52 are, for example, inertial measurement units (IMUs). As shown in FIG. 1, the first attitude sensor 51 is attached to the front frame 11. The first attitude sensor 51 detects the pitch angle and roll angle of the vehicle body 2 with respect to the horizontal direction. The first attitude sensor 51 outputs a signal indicating the pitch angle and roll angle of the vehicle body 2 with respect to the horizontal direction to the controller 40.

[0039] The second attitude sensor 52 is attached to the dozer 17. The second attitude sensor 52 detects the pitch angle and roll angle of the dozer 17 with respect to the horizontal direction. The second attitude sensor 52 outputs a signal indicating the pitch angle and roll angle of the dozer 17 with respect to the horizontal direction to the controller 40. The controller 40 calculates the pitch angle θ1 of the dozer 17 with respect to the vehicle body 2 shown in FIG. 7 based on the pitch angle of the vehicle body 2 detected by the first attitude sensor 51 and the pitch angle of the dozer 17 detected by the second attitude sensor 52.

[0040] The motor grader 1 includes a rotation angle sensor 53 and an articulation angle sensor 54. The rotation angle sensor 53 detects the rotation angle θ2 of the blade 16 with respect to the dozer 17 shown in FIG. 8. The rotation angle sensor 53 outputs a signal indicating the rotation angle θ2 of the blade 16 with respect to the dozer 17 to the controller 40.

[0041] The articulation angle sensor 54 detects the articulation angle θ3 of the front frame 11 with respect to the rear frame 12 shown in FIGS. 5 and 6. The articulation angle sensor 54 outputs a signal indicating the articulation angle θ3 of the front frame 11 with respect to the rear frame 12 to the controller 40.

[0042] The motor grader 1 includes an input device 55. The input device 55 is operable by an operator to set the control of the motor grader 1. The input device 55 includes, for example, a touch panel. Alternatively, the input device 55 may include operation members such as switches or buttons. The input device 55 outputs a signal indicating the input to the input device 55 by the operator to the controller 40.

[0043] The motor grader 1 includes a mode switching member 56 for automatic blade control. The mode switching member 56 is, for example, a switch. However, the mode switching member 56 may be other members such as a lever or a touch panel. The mode switching member 56 is operated by an operator to switch the mode of automatic blade control. The automatic blade control includes automatic blade raising control and automatic blade lowering control.

[0044] In the automatic blade raising control, when the vehicle body 2 is moving backward and the left lift operating member 45 or the right lift operating member 46 returns to the neutral position after being operated to raise the blade for a predetermined first continuous time or more, the controller 40 controls the left lift cylinder 22 and the right lift cylinder 23 to raise the blade 16 to a predetermined target rising position. In the automatic blade lowering control, when the vehicle body 2 is moving forward and the left lift operating member 45 or the right lift operating member 46 returns to the neutral position after being operated to lower the blade for a predetermined second continuous time or more, the controller 40 controls the left lift cylinder 22 and the right lift cylinder 23 to lower the blade 16 to a predetermined target lowering position.

[0045] The mode switching member 56 outputs a signal corresponding to the operation on the mode switching member 56 to the controller 40. The controller 40 switches the mode of automatic blade control to an off mode, a first mode, and a second mode according to the operation on the mode switching member 56. In the off mode, the controller 40 invalidates both the automatic blade raising control and the automatic blade lowering control. In the first mode, the controller 40 validates both the automatic blade raising control and the automatic blade lowering control. In the second mode, the controller 40 validates the automatic blade raising control and invalidates the automatic blade lowering control. Hereinafter, the automatic blade raising control and the automatic blade lowering control will be described.

[0046] FIG. 9 is a flowchart showing the process of automatic blade raising control. As shown in FIG. 9, in step S101, the controller 40 acquires data from the sensors. The controller 40 acquires the data detected by each sensor from the first attitude sensor 51, the second attitude sensor 52, the rotation angle sensor 53, and the articulation angle sensor 54 described above.

[0047] In step S102, the controller 40 determines whether the vehicle body 2 is moving backward. As shown in FIG. 10A, the controller 40 determines that the vehicle body 2 is moving backward when the FNR switching member 42 is in the reverse position R. When the controller 40 determines that the vehicle body 2 is moving backward, the process proceeds to step S103.

[0048] In step S103, the controller 40 determines whether the left lift operation member 45 or the right lift operation member 46 is being operated to raise the blade. As shown in FIG. 10A, the controller 40 determines that the left lift operation member 45 or the right lift operation member 46 is being operated to raise the blade when the left lift operation member 45 or the right lift operation member 46 is in the blade raising position U1. When the left lift operation member 45 or the right lift operation member 46 is being operated to raise the blade, the process proceeds to step S104.

[0049] In step S104, the controller 40 raises the blade 16 according to the operations of the lift operation members 45 and 46. For example, when the left lift operation member 45 is being operated to raise the blade, the left end of the blade 16 is raised according to the operation of the left lift operation member 45. When the right lift operation member 46 is being operated to raise the blade, the right end of the blade 16 is raised according to the operation of the right lift operation member 46. When both the left lift operation member 45 and the right lift operation member 46 are being operated to raise the blade, both the left end and the right end of the blade 16 are raised according to the operations of the left lift operation member 45 and the right lift operation member 46.

[0050] In step S105, the controller 40 determines whether the elapsed time T1 after the start of the blade raising operation is equal to or greater than the first elapsed time Th1. If the elapsed time T1 after the start of the blade raising operation is equal to or greater than the first elapsed time Th1, the process proceeds to step S106.

[0051] In step S106, the controller 40 determines whether the lift operation members 45 and 46 have returned to the neutral position. As shown in FIG. 10B, if the lift operation members 45 and 46 have returned to the neutral position N1, the process proceeds to step S107.

[0052] In step S107, the controller 40 determines whether the posture of the work implement 5 is in a predetermined risk posture. The predetermined risk posture indicates a posture in which there is a risk of the blade 16 interfering with the vehicle body 2 due to the automatic blade raising control. For example, the controller 40 determines that the posture of the work implement 5 is in the predetermined risk posture when the roll angle of the dozer blade 17 or the pitch angle θ1 of the blade 16 with respect to the vehicle body 2 is equal to or greater than a predetermined threshold value. Alternatively, the controller 40 may determine whether the posture of the work implement 5 is in the predetermined risk posture based on the rotation angle θ2 of the blade 16 or the articulation angle θ3.

[0053] Alternatively, the predetermined risk posture may be a posture in which the blade 16 does not move vertically with respect to the ground. For example, the controller 40 may determine that the posture of the work implement 5 is in the predetermined risk posture when the left and right lift cylinders 22 and 23 are greatly inclined from the vertical direction. If the posture of the work implement 5 is in the predetermined risk posture, the controller 40 prohibits the automatic blade raising control. If the posture of the work implement 5 is not in the predetermined risk posture, the process proceeds to step S108. Note that when the controller 40 determines that the posture of the work implement 5 is in the predetermined risk posture, the controller 40 may prohibit the automatic blade raising control and issue an alarm to notify the operator of this fact.

[0054] In step S108, the controller 40 raises the blade 16 toward the target raised position by automatic blade raising control. As shown in FIG. 10B, in the automatic blade raising control, the controller 40 automatically raises the blade 16 even if the lift operation members 45 and 46 are returned to the neutral position N1.

[0055] Note that the controller 40 sets and stores a target raised position in advance according to an operation on the input device 55 by the operator. The target raised position can be selected from a plurality of height levels. The plurality of height levels include, for example, a high level and a low level. However, the plurality of height levels may include three or more levels. The controller 40 determines a height corresponding to the set height level as the target raised position.

[0056] In step S109, the controller 40 determines whether the blade 16 has reached the target raised position. The controller 40 determines that the blade 16 has reached the target raised position when the tip of the blade 16 reaches the target raised position. When the blade 16 reaches the target raised position, in step S110, the controller 40 stops the raising of the blade 16. Thereby, as shown in FIG. 10C, the blade 16 stops at the target raised position.

[0057] Note that during the automatic blade raising control, if the left lift operation member 45 or the right lift operation member 46 is operated to lower the blade, the controller 40 cancels the automatic blade raising control. That is, the controller 40 stops the raising of the blade 16 and returns to the process from step S101.

[0058] Also, during the automatic blade raising control, if the left lift operation member 45 or the right lift operation member 46 is operated to raise the blade, the controller 40 temporarily stops the automatic blade raising control. Thereafter, when the left lift operation member 45 or the right lift operation member 46 returns to the neutral position N1, the controller 40 resumes the automatic blade raising control. That is, the controller 40 resumes the process after step S108.

[0059] Next, the automatic blade lowering control will be described. FIG. 11 is a flowchart showing the process of the automatic blade lowering control. As shown in FIG. 11, in step S201, similar to step S101, the controller 40 acquires data from the sensor.

[0060] In step S202, the controller 40 determines whether the vehicle body 2 is moving forward. As shown in FIG. 12A, the controller 40 determines that the vehicle body 2 is moving forward when the FNR switching member 42 is in the forward position F. If the controller 40 determines that the vehicle body 2 is moving forward, the process proceeds to step S203.

[0061] In step S203, the controller 40 determines whether the left lift operation member 45 or the right lift operation member 46 is being operated to lower the blade. As shown in FIG. 12A, the controller 40 determines that the left lift operation member 45 or the right lift operation member 46 is being operated to lower the blade when the left lift operation member 45 or the right lift operation member 46 is in the blade lowering position D1. If the left lift operation member 45 or the right lift operation member 46 is being operated to lower the blade, the process proceeds to step S204.

[0062] In step S204, the controller 40 lowers the blade 16 according to the operations of the lift operation members 45 and 46. For example, when the left lift operation member 45 is being operated to lower the blade, the left end of the blade 16 is lowered according to the operation of the left lift operation member 45. When the right lift operation member 46 is being operated to lower the blade, the right end of the blade 16 is lowered according to the operation of the right lift operation member 46. When both the left lift operation member 45 and the right lift operation member 46 are being operated to lower the blade, both the left end and the right end of the blade 16 are lowered according to the operations of the left lift operation member 45 and the right lift operation member 46.

[0063] In step S205, the controller 40 determines whether the elapsed time T2 after the start of the blade lowering operation is equal to or greater than a second elapsed time Th2. The second elapsed time Th2 may be the same as the first elapsed time Th1. Alternatively, the second elapsed time Th2 may be different from the first elapsed time Th1. If the elapsed time T2 after the start of the blade lowering operation is equal to or greater than the second elapsed time Th2, the process proceeds to step S206.

[0064] In step S206, the controller 40 determines whether the lift operation members 45, 46 have returned to the neutral position N1. As shown in FIG. 12B, if the lift operation members 45, 46 have returned to the neutral position N1, the process proceeds to step S207.

[0065] In step S207, the controller 40 determines whether the posture of the work implement 5 is a predetermined risk posture. The predetermined risk posture indicates a posture in which there is a risk that the blade 16 will interfere with the vehicle body 2 due to the automatic blade lowering control. The predetermined risk posture in the automatic blade lowering control may be the same as or different from the predetermined risk posture in the automatic blade raising control. If the posture of the work implement 5 is the predetermined risk posture, the controller 40 prohibits the automatic blade lowering control. If the posture of the work implement 5 is not the predetermined risk posture, the process proceeds to step S208.

[0066] In step S208, the controller 40 raises the blade 16 toward the target lowering position by the automatic blade lowering control. As shown in FIG. 12B, in the automatic blade lowering control, the controller 40 automatically lowers the blade 16 even if the lift operation members 45, 46 have been returned to the neutral position N1.

[0067] Note that the controller 40 sets and stores a target lowering position in advance in response to an operation on the input device 55 by the operator. The target lowering position can be set more finely than the target raising position. The target lowering position can be set arbitrarily. For example, it can be set by numerically inputting the target position to the input device 55. Alternatively, when the operator arranges the blade 16 at an arbitrary height by operating the lift operation member and then operates the input device 55 (for example, presses a setting button), the controller 40 determines the height of the blade 16 at that time as the target lowering position.

[0068] In step S209, the controller 40 determines whether the blade 16 has reached the target lowering position. The controller 40 determines that the blade 16 has reached the target lowering position when the tip of the blade 16 reaches the target lowering position. When the blade 16 reaches the target lowering position, in step S210, the controller 40 stops the descent of the blade 16. Thereby, as shown in FIG. 12C, the blade 16 stops at the target lowering position.

[0069] Note that during the automatic blade lowering control, if the left lift operation member 45 or the right lift operation member 46 is operated to raise the blade, the controller 40 cancels the automatic blade lowering control. That is, the controller 40 stops the descent of the blade 16 and returns to the process from step S201.

[0070] Also, during the automatic blade lowering control, if the left lift operation member 45 or the right lift operation member 46 is operated to lower the blade, the controller 40 temporarily stops the automatic blade lowering control. After that, when the left lift operation member 45 or the right lift operation member 46 returns to the neutral position N1, the controller 40 resumes the automatic blade lowering control. That is, the controller 40 resumes the process after step S208.

[0071] Next, the control of the lift cylinders 22 and 23 in the automatic blade control will be described. FIG. 13 is a flowchart showing the process of controlling the lift cylinders 22 and 23 in the automatic blade control. As shown in FIG. 13, in step S301, the controller 40 acquires the actual pitch angle of the blade 16 with respect to the vehicle body 2. The controller 40 acquires the pitch angle θ1 of the drover 17 with respect to the vehicle body 2 described above as the actual pitch angle of the blade 16.

[0072] In step S302, the controller 40 acquires the target pitch angle of the blade 16 with respect to the vehicle body 2. In the automatic blade raising control, the controller 40 calculates, as the target pitch angle of the blade 16, the pitch angle of the blade 16 corresponding to the target raising position. In the automatic blade lowering control, the controller 40 calculates, as the target pitch angle of the blade 16, the pitch angle of the blade 16 corresponding to the target lowering position.

[0073] In step S303, the controller 40 determines a spool stroke command. The spool stroke command is a command value for the spool stroke of the work implement valve 34 for controlling the lift cylinders 22 and 23. The controller 40 stores spool stroke - actual pitch angle data. The spool stroke - actual pitch angle data is data that defines the relationship between the spool stroke command and the actual pitch angle of the blade 16. The spool stroke - actual pitch angle data will be described later.

[0074] In step S304, the controller 40 controls the work implement valve 34 based on the spool stroke command. Thereby, in the automatic blade raising control, the lift cylinders 22 and 23 are controlled so that the blade 16 rises at a speed corresponding to the spool stroke command. Also, in the automatic blade lowering control, the lift cylinders 22 and 23 are controlled so that the blade 16 descends at a speed corresponding to the spool stroke command.

[0075] FIG. 14 is a diagram showing an example of spool stroke - actual pitch angle data. In FIG. 14, L1 shows the spool stroke - actual pitch angle data in the automatic blade raising control. L2 shows the spool stroke - actual pitch angle data in the automatic blade lowering control.

[0076] A positive value of the spool stroke command indicates that the work implement valve 34 is controlled to contract the lift cylinders 22, 23, that is, to raise the blade 16. A negative value of the spool stroke command indicates that the work implement valve 34 is controlled to extend the lift cylinders 22, 23, that is, to lower the blade 16.

[0077] The greater the absolute value of the spool stroke command, the faster the stroke speed of the lift cylinders 22, 23. That is, the greater the absolute value of the spool stroke command, the faster the change speed of the actual pitch angle of the blade 16 and the faster the raising and lowering speed of the blade 16. Conversely, the smaller the absolute value of the spool stroke command, the slower the change speed of the actual pitch angle of the blade 16 and the slower the raising and lowering speed of the blade 16.

[0078] Also, as the blade 16 rises, the actual pitch angle decreases. In the automatic blade raising control, as shown in the spool stroke - actual pitch angle data L1, the controller 40 sets the spool stroke command to the first command value S1A until the actual pitch angle decreases and reaches the actual pitch angle A1 at the deceleration start point P1. While the actual pitch angle reaches the target pitch angle A2 corresponding to the target raising position from the actual pitch angle A1 at the deceleration start point, the controller 40 decreases the spool stroke command to the second command value S2A in response to the decrease in the actual pitch angle. That is, the controller 40 decelerates the change speed of the actual pitch angle, that is, the raising speed of the blade 16, in response to the rise of the blade 16.

[0079] Conversely, in response to the lowering of the blade 16, the actual pitch angle increases. In the automatic blade lowering control, as shown in the spool stroke - actual pitch angle data L2, the controller 40 sets the spool stroke command to the third command value S1B until the actual pitch angle increases and reaches the actual pitch angle B1 at the deceleration start point P2. While the actual pitch angle reaches from the actual pitch angle B1 at the deceleration start point P2 to the target pitch angle B2 corresponding to the target lowering position, the controller 40 increases the spool stroke command to the fourth command value S2B in response to the increase in the actual pitch angle. That is, the controller 40 decelerates the change rate of the actual pitch angle, that is, the lowering speed of the blade 16, in response to the lowering of the blade 16.

[0080] In step S109 of the automatic blade raising control described above, the controller 40 determines that the blade 16 has reached the target raising position when the actual pitch angle reaches the target pitch angle A2. In step S209 of the automatic blade lowering control, the controller 40 determines that the blade 16 has reached the target lowering position when the actual pitch angle reaches the target pitch angle B2.

[0081] According to the motor grader 1 according to the present embodiment described above, when the vehicle body 2 reverses, after the operator raises the left lift operation member 45 or the right lift operation member 46 for a duration of the first continuous time Th1 or more and then returns to the neutral position, the blade 16 automatically rises to the target raising position by the automatic blade raising control. Therefore, other operations such as the steering operation become easier. Thereby, the operability of the motor grader 1 is improved.

[0082] When the vehicle body 2 moves forward, after the operator lowers the left lift operation member 45 or the right lift operation member 46 for a duration of the second continuous time Th2 or more and then returns to the neutral position, the blade 16 automatically descends to the target lowering position by the automatic blade lowering control. Therefore, other operations such as the steering operation become easier. Thereby, the operability of the motor grader 1 is improved.

[0083] The changing speed of the actual pitch angle of the blade 16 is controlled according to the actual pitch angle. Specifically, the changing speed of the actual pitch angle of the blade 16 is fast until the actual pitch angle of the blade 16 reaches the actual pitch angle at the deceleration start point, and is decelerated after passing the deceleration start point until reaching the target pitch angle. Therefore, the blade 16 can be raised to the target rising position quickly and accurately.

[0084] As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0085] The motor grader 1 may be operable remotely. In that case, the above-described operating member and the controller 40 may be disposed outside the motor grader 1.

[0086] The process of automatic blade control is not limited to that of the above embodiment and may be changed. For example, in the automatic blade lowering control, the controller 40 may store the height of the blade 16 when the vehicle body 2 is switched from forward to reverse as the target lowering position. Alternatively, the target lowering position may be selectable from a plurality of height levels.

[0087] During the automatic blade raising control, the controller 40 may cancel the automatic blade raising control even when the left lift operating member 45 or the right lift operating member 46 is operated to raise the blade. Also, during the automatic blade lowering control, the controller 40 may cancel the automatic blade lowering control even when the left lift operating member 45 or the right lift operating member 46 is operated to lower the blade.

Industrial Applicability

[0088] According to the present disclosure, the operability of the motor grader can be improved.

Explanation of Reference Numerals

[0089] 2: Vehicle body, 3A, 3B, 4A - 4D: Running wheels, 5: Working machine, 16: Blade, 22: Left lift cylinder, 23: Right lift cylinder, 40: Controller, 45: Left lift operation member, 46: Right lift operation member, 51: First attitude sensor, 52: Second attitude sensor, 55: Input device

Claims

1. A system for controlling a motor grader, comprising: wherein the motor grader includes: a vehicle body including traveling wheels; a working implement operably connected to the vehicle body and including a blade; a lift cylinder connected to the working implement for raising and lowering the blade; the system includes: a lift operating member operated to raise and lower the blade by the lift cylinder; a sensor for acquiring an actual pitch angle of the blade with respect to the vehicle body; a controller capable of receiving a signal corresponding to an operation of the lift operating member; and is provided with: the controller: when the vehicle body is traveling, if the lift operating member returns to the neutral position after being operated for a predetermined continuous time or more, controls the lift cylinder to perform automatic blade control to raise or lower the blade to a predetermined target position; acquires the actual pitch angle of the blade with respect to the vehicle body; acquires a target pitch angle of the blade with respect to the vehicle body corresponding to the target position; in the automatic blade control, controls a change speed of the actual pitch angle according to the actual pitch angle so that the actual pitch angle becomes the target pitch angle; a system.

2. The controller decelerates the change speed of the actual pitch angle when the actual pitch angle is between a predetermined deceleration start point and the target pitch angle, The system according to Claim 1.

3. Further includes an input device operable by an operator, The controller sets the target position according to an operation on the input device, The system according to Claim 1.

4. The controller: acquires the posture of the working implement; when the posture of the working implement is a predetermined risk posture, prohibits the automatic blade control, The system according to Claim 1.

5. The automatic blade control includes automatic blade raising control, In the automatic blade raising control, when the vehicle body is moving backward and the lift operating member returns to the neutral position after being operated for a predetermined first continuous time or more for blade raising operation, the controller controls the lift cylinder to raise the blade to a predetermined target raising position, The system according to Claim 1.

6. During the automatic blade raising control, if the lift operating member is operated for blade lowering, the controller cancels the automatic blade raising control, The system according to Claim 5.

7. During the automatic blade raising control, when the lift operation member is operated to raise the blade, the controller temporarily stops the automatic blade raising control, and when the lift operation member returns to the neutral position, the controller resumes the automatic blade raising control. The system according to claim 5.

8. The automatic blade control includes an automatic blade lowering control. In the automatic blade lowering control, when the lift operation member is operated to lower the blade for a predetermined second continuous time or more and then returns to the neutral position while the vehicle body is moving forward, the controller controls the lift cylinder to lower the blade to a predetermined target lowering position. The system according to claim 1.

9. During the automatic blade lowering control, when the left lift operation member or the right lift operation member is operated to raise the blade, the controller cancels the automatic blade lowering control. The system according to claim 8.

10. During the automatic blade lowering control, when the left lift operation member or the right lift operation member is operated to lower the blade, the controller temporarily stops the automatic blade lowering control, and when the left lift operation member or the right lift operation member returns to the neutral position, the controller resumes the automatic blade lowering control. The system according to claim 8.

11. The system further includes an input device operable by an operator. The controller sets the target rising position and the target lowering position according to an operation on the input device. The target lowering position can be set more finely than the target rising position. The system according to claim 8.

12. The target rising position can be selected from a plurality of height levels. The system according to claim 11.

13. The target lowering position can be set arbitrarily. The system according to claim 11.

14. The controller stores the height of the blade when the vehicle body is switched from forward to reverse as the target lowering position. The system according to claim 8.

15. A method for controlling a motor grader, the motor grader including a vehicle body including traveling wheels, a working machine operably connected to the vehicle body and including a blade, a lift cylinder connected to the working machine for raising and lowering the blade, and the method includes The method includes ​ Receiving a signal corresponding to an operation of a lift operation member that is operated to raise and lower the blade by the lift cylinder; When the lift operation member returns to the neutral position after being operated for a predetermined continuous time or more while the vehicle body is traveling, executing automatic blade control to control the lift cylinder to raise or lower the blade to a predetermined target position; Obtaining an actual pitch angle of the blade with respect to the vehicle body; Obtaining a target pitch angle of the blade with respect to the vehicle body corresponding to the target position; In the automatic blade control, controlling a change speed of the actual pitch angle according to the actual pitch angle so that the actual pitch angle becomes the target pitch angle; A method comprising the above.

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