System and method for controlling a work machine

Abstract

To improve work efficiency in excavation work, and to prevent an operator from feeling discomfort in the behavior of a work machine.SOLUTION: A system according to the present disclosure includes an operation member and a controller. The operation member is operable by an operator of the work machine. The controller determines whether the work machine is performing an excavation work. When it is determined that the work machine is performing excavation work, the controller executes high rotation speed control for increasing the rotation speed of the power source. The controller determines whether the work machine has ended the excavation work. The controller cancels the high rotation speed control when it is determined that the work machine has finished the excavation work. Even when it is determined that the work machine is performing excavation work, the controller cancels the high rotation speed control when a predetermined operation is performed by the operation member.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to systems and methods for controlling a work machine. [Background technology]

[0002] Conventionally, there is known a technology (hereinafter referred to as high rotation speed control) that determines whether a work machine is performing excavation work and increases the engine rotation speed if the work machine is performing excavation work. This technology prevents the engine rotation speed from decreasing when the work implement of the work machine suddenly decelerates due to penetrating into the ground. This improves the work efficiency during excavation work. Furthermore, the fuel economy of the work machine is improved compared to when the engine rotation speed is always kept high even when excavation work is not being performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2008-8183 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described technology, high rotational speed control is released when the work machine finishes excavation work. However, even if the operator does not want the engine rotational speed to increase, high rotational speed control is maintained while the work machine is performing excavation work. For example, even if the operator determines that a large traction force is not necessary during excavation work and releases the accelerator pedal, a high engine rotational speed is maintained by high rotational speed control. This causes the operator to feel uncomfortable with the behavior of the work machine. An object of the present disclosure is to improve work efficiency during excavation work and to prevent the operator from feeling uncomfortable with the behavior of the work machine. [Means for solving the problem]

[0005] A system according to one aspect of the present disclosure is a system for controlling a work machine. The work machine includes a power source, a hydraulic pump driven by the power source, and a work implement operated by hydraulic fluid from the hydraulic pump. The system according to this aspect includes an operation member and a controller. The operation member is operable by an operator of the work machine. The controller determines whether the work machine is performing excavation work. If the controller determines that the work machine is performing excavation work, the controller executes high rotational speed control to increase the rotational speed of the power source. The controller determines whether the work machine has finished excavation work. If the controller determines that the work machine has finished excavation work, the controller cancels the high rotational speed control. Even if the controller determines that the work machine is performing excavation work, the controller cancels the high rotational speed control if a predetermined operation is performed using the operation member.

[0006] A method according to another aspect of the present disclosure is a method for controlling a work machine. The work machine includes a power source, a hydraulic pump driven by the power source, and a work implement operated by hydraulic fluid from the hydraulic pump. The method according to this aspect includes acquiring an operation using an operating member operable by an operator of the work machine, determining whether the work machine is performing excavation work, and if it is determined that the work machine is performing excavation work, executing high rotational speed control to increase the rotational speed of the power source, determining whether the work machine has finished excavation work, and if it is determined that the work machine has finished excavation work, canceling the high rotational speed control, and even if it is determined that the work machine is performing excavation work, canceling the high rotational speed control if a predetermined operation is performed using the operating member. [Effects of the Invention]

[0007] According to the present disclosure, high rotational speed control improves work efficiency during excavation work. Furthermore, even when it is determined that the work machine is performing excavation work, if the operator performs a predetermined operation using the operating member, the high rotational speed control is released. This reduces the operator's discomfort with the behavior of the work machine. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side view of a work machine according to an embodiment. [Figure 2] FIG. 1 is a schematic diagram showing the configuration of a work machine. [Figure 3] FIG. 10 is a diagram showing an output torque line and a matching line of a driving source. [Figure 4] 10 is a flowchart showing a process of high rotation speed control. [Figure 5] FIG. 10 is a diagram showing an example of target rotation speed data for high rotation speed control. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a side view of a work machine 1 according to an embodiment of the present disclosure. The work machine 1 according to this embodiment is a wheel loader. As shown in Fig. 1, the work machine 1 includes a vehicle body 2, a work implement 5, and a traveling device 6.

[0010] The vehicle body 2 includes a front vehicle body 3 and a rear vehicle body 4. The rear vehicle body 4 is connected to the front vehicle body 3 so as to be able to swing left and right. A driver's cab 7 and a power compartment 8 are arranged in the rear vehicle body 4. The work implement 5 is movably connected to the vehicle body 2. The work implement 5 is used for work such as excavation. The work implement 5 is attached to the front vehicle body 3. The work implement 5 includes a boom 11, a bucket 12, a boom cylinder 13, and a bucket cylinder 14. The boom cylinder 13 and the bucket cylinder 14 are, for example, hydraulic cylinders. The boom cylinder 13 is connected to the boom 11. The boom 11 moves when the boom cylinder 13 extends and retracts. The bucket cylinder 14 is connected to the bucket 12 via a bell crank 15. The bucket 12 moves when the bucket cylinder 14 extends and retracts.

[0011] The traveling device 6 is attached to the vehicle body 2. The traveling device 6 causes the work machine 1 to travel. The traveling device 6 includes front wheels 16 and rear wheels 17. The front wheels 16 are rotatably supported by the front vehicle body 3. The rear wheels 17 are rotatably supported by the rear vehicle body 4. Note that in the drawings, only one of the left and right front wheels 16 and only one of the left and right rear wheels 17 are shown.

[0012] Fig. 2 is a schematic diagram showing the drive system and control system of the work machine 1. As shown in Fig. 2, the work machine 1 is equipped with a power source 21, a hydraulic pump 22, a control valve 23, and a transmission 24. The power source 21 is, for example, an internal combustion engine. Alternatively, the power source 21 may include an electric motor. The power source 21 is arranged in a power chamber 8.

[0013] The hydraulic pump 22 is connected to the power source 21. The hydraulic pump 22 is driven by the power source 21 to discharge hydraulic oil. The hydraulic pump 22 is connected to the boom cylinder 13 and the bucket cylinder 14 via a control valve 23. The boom cylinder 13 and the bucket cylinder 14 are driven by the hydraulic oil from the hydraulic pump 22.

[0014] The transmission 24 is, for example, a HMT (Hydro Mechanical Transmission) that includes a planetary gear mechanism 25 and pump / motors 26, 27. The transmission 24 changes the speed ratio by controlling the capacity of the pump / motors 26, 27. The transmission 24 transmits driving force from the power source 21 to the traveling device 6. This drives the front wheels 16 and rear wheels 17, causing the work machine 1 to travel.

[0015] The work machine 1 is equipped with a travel operation member 31, an accelerator operation member 32, and a work implement operation member 33. The travel operation member 31, the accelerator operation member 32, and the work implement operation member 33 are arranged in the operator's cab 7. The travel operation member 31, the accelerator operation member 32, and the work implement operation member 33 can be operated by the operator.

[0016] The travel operating member 31 is operated to switch the working machine 1 between forward and reverse. The travel operating member 31 is, for example, a lever. The travel operating member 31 may also be another member such as a switch. The travel operating member 31 can be operated to a forward position F, a reverse position R, and a neutral position N. The travel operating member 31 outputs a signal indicating the operating position of the travel operating member 31.

[0017] The accelerator operating member 32 is operated to control the output rotation speed of the power source 21. The accelerator operating member 32 is, for example, a pedal. The accelerator operating member 32 may also be another member such as a lever or a switch. The accelerator operating member 32 outputs a signal indicating the amount of operation of the accelerator operating member 32 (hereinafter referred to as accelerator operation amount).

[0018] The work implement operation member 33 is operated to operate the work implement 5. The work implement operation member 33 is, for example, a lever. The work implement operation member 33 may also be another member such as a switch. The work implement operation member 33 outputs a signal indicating the amount of operation of the work implement operation member 33 (hereinafter referred to as the work implement operation amount).

[0019] The work machine 1 includes a power source sensor 34, a vehicle speed sensor 35, a boom pressure sensor 36, and an attitude sensor 37. The power source sensor 34 detects the output rotation speed of the power source 21. The power source sensor 34 outputs a signal indicating the output rotation speed of the power source 21. The vehicle speed sensor 35 detects the vehicle speed of the work machine 1. The vehicle speed sensor 35 outputs a signal indicating the vehicle speed of the work machine 1. The boom pressure sensor 36 detects the bottom pressure of the boom cylinder 13 (hereinafter referred to as boom bottom pressure). The boom pressure sensor 36 outputs a signal indicating the boom bottom pressure.

[0020] The attitude sensor 37 detects the attitude of the work implement 5. The attitude of the work implement 5 includes the boom angle. The boom angle is the angle of the boom 11 with respect to the horizontal direction. The attitude sensor 37 is, for example, an angle sensor attached to the boom 11. Alternatively, the attitude sensor 37 may be a stroke sensor that detects the stroke amount of the boom cylinder 13. In that case, the boom angle may be calculated from the stroke amount of the boom cylinder 13 detected by the stroke sensor.

[0021] The work machine 1 includes a controller 41. The controller 41 includes a processor such as a CPU (central processing unit) and storage devices such as RAM and ROM. The controller 41 may also include an auxiliary storage device such as a hard disk or an SSD (Solid State Drive). The controller 41 stores programs and data for controlling the work machine 1. The controller 41 executes processing for controlling the work machine 1 in accordance with the stored programs and data.

[0022] The controller 41 receives a signal indicating the output rotation speed of the power source 21 from the power source sensor 34. The controller 41 receives a signal indicating the vehicle speed from the vehicle speed sensor 35. The controller 41 receives a signal indicating the boom bottom pressure from the boom pressure sensor 36. The controller 41 receives a signal indicating the attitude of the work implement 5 from the attitude sensor 37.

[0023] The controller 41 receives a signal indicating the operating position of the travel operating member 31 from the travel operating member 31. The controller 41 controls the transmission 24 in accordance with the signal from the travel operating member 31, thereby switching the work machine 1 between forward and reverse travel.

[0024] The controller 41 receives a signal indicating the accelerator operation amount from the accelerator operating member 32. The controller 41 controls the output rotation speed of the power source 21 by sending a command signal to the power source 21 according to the accelerator operation amount. For example, the controller 41 determines a target rotation speed of the power source 21 according to the accelerator operation amount.

[0025] In particular, the controller 41 determines the target tractive force of the work machine 1 in accordance with the accelerator operation amount. For example, the controller 41 increases the target tractive force of the work machine 1 in accordance with an increase in the accelerator operation amount. The controller 41 determines the target output torque of the power source 21 from the target tractive force. The controller 41 determines the target rotational speed of the power source 21 based on the target output torque.

[0026] The controller 41 stores an output torque line L1 and a matching line L2 of the driving source 21. FIG. 3 is a diagram showing an example of the output torque line L1 and the matching line L2 of the driving source 21 under normal rotation speed control. The output torque line L1 defines the relationship between the output torque of the driving source 21 and the output rotation speed of the driving source 21 in the full load range. The matching line L2 defines the relationship between the target output torque of the driving source 21 and the target rotation speed of the driving source 21. The controller 41 determines the target rotation speed N1 of the driving source 21 based on the target output torque Tr1 of the driving source 21 by referring to the matching line L2.

[0027] The controller 41 controls the output rotation speed of the power source 21 by sending a command signal to the power source 21 according to the target rotation speed. The controller 41 also controls the gear ratio of the transmission 24 by sending a command signal to the transmission 24 according to the output rotation speed of the power source 21 and the vehicle speed.

[0028] The controller 41 receives a signal indicating the amount of work implement operation from the work implement operation member 33. The controller 41 controls the work implement 5 by sending command signals to the hydraulic pump 22 and the control valve 23 in accordance with the amount of work implement operation.

[0029] Next, a description will be given of the high rotational speed control processing executed by the controller 41. In high rotational speed control, the output rotational speed of the power source 21 is increased compared to normal rotational speed control while the work machine 1 is performing excavation work. Fig. 4 is a flowchart showing the high rotational speed control processing.

[0030] 4, in step S101, the controller 41 acquires status data. The status data indicates the operating status of the work machine 1. The status data includes, for example, the operating position of the travel operating member 31 described above, the boom bottom pressure, the boom angle, and the vehicle speed.

[0031] In step S102, the controller 41 determines whether the start conditions for high rotational speed control are satisfied. The controller 41 determines whether the start conditions for high rotational speed control are satisfied based on the status data described above. The start conditions for high rotational speed control include the vehicle speed being equal to or greater than the first speed threshold and the excavation flag being on. The first speed threshold is set to a speed at which the work machine 1 is considered not to be stopped. The excavation flag is set on when the work machine 1 is performing excavation work, and is set off when the work machine 1 is not performing excavation work.

[0032] When the conditions for determining whether excavation work is in progress are met, the controller 41 determines that the work machine 1 is performing excavation work and sets the excavation flag to ON. The conditions for determining whether excavation work is in progress include, for example, the travel operating member 31 being in the forward position F, the boom bottom pressure being equal to or greater than a predetermined pressure threshold, and the boom angle being equal to or less than a predetermined angle threshold.

[0033] When the conditions for determining whether excavation has ended are satisfied, the controller 41 determines that the work machine 1 is not performing excavation work and sets the excavation flag to OFF. The conditions for determining whether excavation has ended include, for example, the boom bottom pressure remaining lower than the pressure threshold for a predetermined period of time or more, or the travel operating member 31 being in the neutral position N or the reverse position R.

[0034] If the conditions for starting the high rotation speed control are satisfied in step S102, the process proceeds to step S103. In step S103, the controller 41 executes the high rotation speed control. The controller 41 increases the output rotation speed of the power source 21 through the high rotation speed control.

[0035] Specifically, the controller 41 determines the target rotation speed of the power source 21 for high rotation speed control based on the vehicle speed. The controller 41 determines the target rotation speed of the power source 21 from the vehicle speed by referring to the target rotation speed data for high rotation speed control. The target rotation speed data for high rotation speed control defines the relationship between the vehicle speed and the target rotation speed of the power source 21.

[0036] FIG. 5 is a diagram showing an example of target rotation speed data for high rotation speed control. As shown in FIG. 5, the target rotation speed data includes a first speed range (0-V1), a second speed range (V1-V2), a third speed range (V2-V3), and a fourth speed range (V3 and above). In the first speed range, the target rotation speed increases as the vehicle speed increases. In the second speed range, the target rotation speed is constant at the maximum rotation speed Nmax in high rotation speed control. In the third speed range, the target rotation speed decreases as the vehicle speed increases. In the fourth speed range, the target rotation speed is 0.

[0037] During the high rotation speed control, the controller 41 determines the final target rotation speed to be the larger of the target rotation speed for the high rotation speed control and the target rotation speed for the normal rotation speed control. Therefore, when the target rotation speed for the high rotation speed control is higher than the target rotation speed for the normal rotation speed control, the output rotation speed of the power source 21 increases due to the high rotation speed control.

[0038] In detail, when the vehicle speed is in the first speed range, the controller 41 increases the increment of the output rotation speed of the power source 21 in response to an increase in the vehicle speed. When the vehicle speed is in the second speed range, the controller 41 increases the output rotation speed of the power source 21 to the maximum rotation speed Nmax under high rotation speed control, regardless of the vehicle speed. When the vehicle speed is in the third speed range, the controller 41 decreases the increment of the output rotation speed of the power source 21 in response to an increase in the vehicle speed. When the vehicle speed is in the fourth speed range, the controller 41 does not increase the output rotation speed of the power source 21. As described above, the controller 41 adjusts the output rotation speed of the power source 21 in response to the vehicle speed during high rotation speed control.

[0039] In step S104, the controller 41 determines whether excavation work has ended. The controller 41 determines that excavation work has ended when the above-mentioned excavation flag is off. Therefore, for example, when the travel operating member 31 is operated to the neutral position N or the reverse position R, the controller 41 determines that excavation work has ended. Alternatively, when the boom bottom pressure remains lower than the pressure threshold for a predetermined period of time or longer, the controller 41 determines that excavation work has ended.

[0040] If the controller 41 determines that the excavation work has ended, the process proceeds to step S106. In step S106, the controller 41 cancels the high rotational speed control. That is, the controller 41 ends the increase in the output rotational speed of the power source 21 through the high rotational speed control. Therefore, the controller 41 controls the output rotational speed of the power source 21 through the normal rotational speed control in accordance with the accelerator operation amount.

[0041] If in step S104 the controller 41 determines that the excavation work has not ended, the processing proceeds to step S105. In step S105, the controller 41 determines whether the conditions for canceling the high rotational speed control are met. The conditions for canceling the high rotational speed control include the work machine 1 being engaged in excavation work, the vehicle speed being lower than a second speed threshold, and the accelerator operation amount being lower than a predetermined operation amount threshold. The second speed threshold is set to a speed at which the work machine 1 can be considered to be stopped. The second speed threshold may be the same as the first speed threshold. Alternatively, the second speed threshold may be lower than the first speed threshold. The operation amount threshold is set to an operation amount at which it can be considered that the operator is not operating the accelerator operating member 32.

[0042] If the controller 41 determines that the conditions for canceling the high rotational speed control are satisfied, then in step S106 the controller 41 cancels the high rotational speed control. In other words, even if the controller 41 determines that the work machine 1 is performing excavation work, the controller 41 cancels the high rotational speed control if the operator eases up on the operation of the accelerator operating member 32 so that the operation amount of the accelerator operating member 32 becomes smaller than the operation amount threshold. Therefore, the controller 41 controls the output rotational speed of the power source 21 according to the accelerator operation amount using normal rotational speed control.

[0043] According to the work machine 1 according to the present embodiment described above, the output rotation speed of the power source 21 is increased during excavation work by the high rotation speed control. This reduces the speed ratio of the transmission 24, thereby preventing a decrease in the output rotation speed of the power source 21 due to the load during excavation. This improves work efficiency during excavation work. Furthermore, even if it is determined that the work machine 1 is performing excavation work, the high rotation speed control is released when the operator eases up on the operation of the accelerator operating member 32. This prevents the operator from feeling uncomfortable with the behavior of the work machine 1.

[0044] 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.

[0045] The work machine 1 is not limited to a wheel loader, but may be other machines such as a bulldozer or a grader. The configuration of the work machine 1 is not limited to that of the above embodiment and may be modified. For example, the transmission 24 is not limited to an HMT and may be an HST (Hydro Static Transmission). The attitude sensor 37 is not limited to that of the above embodiment and may be modified. For example, the attitude sensor 37 may be a camera. Alternatively, the controller 41 may detect the attitude of the work machine 5 from the amount of work machine operation.

[0046] The work machine 1 may be operable remotely. In that case, the above-mentioned operating members 31-33 may be located outside the work machine 1. The processing by the controller 41 may be distributed and executed by a remote controller located outside the work machine 1 and an on-board controller located in the work machine 1. The controller 41 may include multiple controllers that are separate from each other. The above-mentioned processing by the controller 41 may be distributed and executed by multiple controllers.

[0047] The high rotational speed control process is not limited to that of the embodiment described above and may be modified. For example, the start conditions and release conditions of the high rotational speed control are not limited to those of the embodiment described above and may be modified, omitted, or added. For example, the start condition of the high rotational speed control may include the tractive force of the work machine 1 being equal to or greater than a predetermined threshold. The start condition of the high rotational speed control may include a condition related to the bucket cylinder 14. The release condition of the high rotational speed control may include the operation of an operating member other than the accelerator operating member 32. [Industrial Applicability]

[0048] According to the present disclosure, the work efficiency in excavation work is improved, and the operator is prevented from feeling uncomfortable with the behavior of the work machine. [Explanation of symbols]

[0049] 1:Work machine 5: Work equipment 21: Power source 22: Hydraulic pump 32: Accelerator operating member 35: Vehicle speed sensor 41: Controller

Claims

1. A system for controlling a work machine including a power source, a hydraulic pump driven by the power source, and a work implement operated by hydraulic fluid from the hydraulic pump, an operating member operable by an operator of the work machine; A controller; Equipped with The controller determining whether the work machine is performing an excavation operation; When it is determined that the work machine is performing the excavation operation, a high rotational speed control is executed to increase the rotational speed of the power source; determining whether the work machine has completed the excavation operation; When it is determined that the work machine has completed the excavation work, the high rotational speed control is released, Even when it is determined that the work machine is performing the excavation work, if a predetermined operation is performed by the operating member, the high rotation speed control is released. system.

2. the operating member includes an accelerator operating member, The controller acquiring an operation amount of the accelerator operation member; determining whether to release the high rotation speed control based on the operation amount of the accelerator operation member; The system of claim 1 .

3. the controller cancels the high rotation speed control when the operation amount of the accelerator operation member is smaller than a predetermined operation amount threshold. The system of claim 2 .

4. The work machine further includes a vehicle speed sensor that detects a vehicle speed of the work machine, The controller Acquire the vehicle speed; determining whether to release the high rotation speed control based on the operation amount of the accelerator operation member and the vehicle speed; The system of claim 2 .

5. the controller cancels the high rotation speed control when the operation amount of the accelerator operation member is smaller than a predetermined operation amount threshold and the vehicle speed is smaller than a predetermined speed threshold. The system of claim 4.

6. A method for controlling a work machine including a power source, a hydraulic pump driven by the power source, and a work implement operated by hydraulic fluid from the hydraulic pump, comprising: acquiring an operation by an operating member operable by an operator of the work machine; determining whether the work machine is performing an excavation operation; when it is determined that the work machine is performing the excavation operation, executing a high rotational speed control to increase the rotational speed of the power source; determining whether the work machine has completed the excavation operation; canceling the high rotational speed control when it is determined that the work machine has completed the excavation work; canceling the high rotation speed control when a predetermined operation is performed by the operating member even when it is determined that the work machine is performing the excavation work; A method for providing the above.

7. the operating member includes an accelerator operating member, acquiring an operation amount of the accelerator operation member; determining whether to release the high rotation speed control based on the operation amount of the accelerator operation member; The method of claim 6 comprising:

8. canceling the high rotation speed control when the operation amount of the accelerator operation member is smaller than a predetermined operation amount threshold; The method of claim 7 comprising:

9. Acquire the vehicle speed of the work machine; determining whether to cancel the high rotation speed control based on the operation amount of the accelerator operation member and the vehicle speed; The method of claim 7 comprising:

10. canceling the high rotation speed control when the operation amount of the accelerator operation member is smaller than a predetermined operation amount threshold and the vehicle speed is smaller than a predetermined speed threshold; The method of claim 9 comprising:

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