Control device, agricultural machine, construction machine, control method, and control program

Abstract

This control device (7) comprises: an acquisition unit (70) that acquires vehicle state information pertaining to the vehicle state of a work vehicle (100) provided with a work machine (5) driven by an electric motor (54a); and a control unit (72) that controls a holding mechanism (55) that holds the stopped state of the electric motor on the basis of the vehicle state information.

Description

Control device, agricultural machine, construction machine, control method, and control program

[0001] The present disclosure relates to a control device, an agricultural machine, a construction machine, a control method, and a control program. CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on and claims the benefit of priority from patent application serial number 2024-147856, filed August 29, 2024, the entire contents of which are incorporated herein by reference.

[0003] Japanese Patent Application Laid-Open Publication No. 2023-173118 discloses a locking mechanism for an electric motor having a rotor that is disposed inside a casing from which a main shaft protrudes and that is rotatable around the main shaft, and a stator that applies a rotational force to the rotor, the locking mechanism comprising: a lock plate that is disposed on the rotor and has at least one hole or recess; a locking member that is disposed on the stator and that can slide in a direction along the insertion direction of the hole or recess; a solenoid that can pull the locking member out of the hole or recess by supplying power; first biasing means that causes the locking member to insert into the hole or recess when power supply to the solenoid is not in an appropriate state; and an unlocking slide pin that moves the solenoid in the sliding direction of the locking member, allowing the locking member to be pulled out of the hole or recess, wherein a portion of the unlocking slide pin is exposed to the outside of the casing.

[0004] In work vehicles equipped with a work implement, such as agricultural machinery or construction machinery, there are cases where it is desirable to keep the work implement stopped. When the work implement is driven by a hydraulic pump, the work implement can be kept stopped simply by closing a valve that controls the hydraulic pressure. In contrast, when the work implement is driven by an electric motor, maintaining the work implement stopped requires energy to maintain the electric motor at 0 rpm, which is inefficient. For this reason, it is conceivable to provide a holding mechanism to keep the electric motor stopped, but controlling the holding mechanism regardless of the vehicle state of the work vehicle may result in the holding mechanism being activated at an inappropriate time.

[0005] The present disclosure aims to provide a control device, agricultural machinery, construction machinery, a control method, and a control program that can properly operate a holding mechanism that keeps an electric motor that drives a work implement of a work vehicle in a stopped state.

[0006] The control device (7) according to the first aspect of the present disclosure includes an acquisition unit (70) that acquires vehicle state information relating to the vehicle state of a work vehicle (100) equipped with a work implement (5) driven by an electric motor (54a), and a control unit (72) that controls a holding mechanism (55) that holds the electric motor in a stopped state based on the vehicle state information.

[0007] The control method according to the second aspect executes processing in which at least one processor (21A) acquires vehicle condition information relating to the vehicle condition of a work vehicle equipped with a work implement driven by an electric motor, and controls a holding mechanism that keeps the electric motor stopped based on the vehicle condition information.

[0008] The control program (23A) according to the third aspect causes at least one processor to execute processing including acquiring vehicle condition information regarding the vehicle condition of a work vehicle equipped with a work implement driven by an electric motor, and controlling a holding mechanism that keeps the electric motor stopped based on the vehicle condition information.

[0009] According to the present disclosure, it is possible to provide an effect of appropriately operating a holding mechanism that keeps an electric motor that drives a work implement of a work vehicle in a stopped state.

[0010] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a diagram showing a vehicle 100 equipped with a control device 7 according to an embodiment of the present disclosure, Fig. 2 is a cross-sectional view of an electric cylinder 54, Fig. 3 is a diagram for explaining a holding mechanism 55, Fig. 4 is a diagram showing a hardware configuration of the control device 7 according to an embodiment of the present disclosure, Fig. 5 is a diagram showing an example configuration of a drive unit 60 including a rotating electric machine 54a and an inverter 10, Fig. 6 is a block diagram showing an example functional configuration of a CPU 21A of the control device 7, and Fig. 7 is a flowchart of control processing by a control program 23A executed by the CPU 21A of the control device 7.

[0011] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0012] FIG. 1 is a diagram illustrating a vehicle 100 equipped with a control device 7 according to an embodiment of the present disclosure. The vehicle 100 is a work vehicle used in agriculture or the construction industry and may be interpreted as an agricultural construction machine (hereinafter, "agricultural construction machine"). The agricultural construction machine may include agricultural machinery and construction machinery. The agricultural construction machine may include an electric tractor, an electric wheel loader, an electric bulldozer, an electric excavator, an electric crane, and the like. FIG. 1 illustrates an electric excavator as an example of the agricultural construction machine. The agricultural construction machine may include a vehicle 100 that moves using crawlers as well as a vehicle 100 that moves using tires. The control device 7 according to the present disclosure may be provided in a vehicle 100 other than an agricultural construction machine. The control device 7 may be interpreted as a device that controls a rotating electric machine 54a, which is an example of an electric motor that drives a work implement 5 provided on the vehicle 100.

[0013] The vehicle 100 may include a traveling device 2 and a main body 3. The traveling device 2 may be provided below the main body 3 and may support the main body 3 so that it can rotate freely in the horizontal direction. The traveling device 2 may include a pair of left and right crawlers 2a. The main body 3 may include a cab 4 in which an operator rides, a work implement 5 provided in front of the cab 4, a battery 6, and a control device 7.

[0014] (Control device 7)

[0015] The control device 7 may be interpreted as a device that controls one or more electric cylinders 54. Specifically, the control device 7 may independently control the rotation speed, rotation direction, rotation torque (hereinafter, torque), etc. of the rotating electric machine 54a included in each of, for example, three electric cylinders 54. For example, the control device 7 may rotate the rotating electric machine 54a included in the electric cylinder 54 that drives the boom 51 in a first rotation direction, while rotating the rotating electric machine 54a included in the electric cylinder 54 that drives the arm 52 in a second rotation direction opposite to the first rotation direction. At this time, the control device 7 may stop the rotation of the rotating electric machine 54a included in the electric cylinder 54 that drives the bucket 53.

[0016] (Battery 6)

[0017] The battery 6 is a storage battery for supplying power to the rotating electric machine 54a. The battery 6 may be, for example, a lithium ion battery or a fuel cell.

[0018] (Work machine 5)

[0019] The work machine 5 may have a multi-joint structure including a boom 51, an arm 52, and a bucket 53. The boom 51 may be supported so as to be swingable in the vertical direction relative to the cab 4. The arm 52 may be supported so as to be swingable at the tip of the boom 51. The bucket 53 may be supported so as to be swingable at the tip of the arm 52. Each of the boom 51, the arm 52, and the bucket 53 may be driven by an electric cylinder 54.

[0020] (Electric cylinder 54)

[0021] The electric cylinder 54 may be interpreted as a mechanism in which the rod 54b moves back and forth when driven by the rotating electric machine 54a. The work machine 5 of the present disclosure uses the ball screw type electric cylinder 54, but the electric cylinder 54 is not limited to the ball screw type and may be of another type, for example, a linear motor type.

[0022] As shown in FIG. 2, the electric cylinder 54 may include a rotating electric machine 54a, a speed reducing mechanism 54c, a case 54d, a nut 54e, a ball screw 54f, and a rod 54b.

[0023] The reduction mechanism 54c reduces the rotation speed of the rotating electric machine 54a and transmits the torque of the rotating electric machine 54a to the ball screw 54f in the case 54d. The reduction mechanism 54c may reduce the rotation speed by, for example, using a small-diameter first pulley 54c1 connected to the rotating shaft 54a1 of the rotating electric machine 54a, a large-diameter second pulley 54c2 connected to the ball screw 54f, and a belt 54c3 connecting the first pulley 54c1 and the second pulley 54c2. The configuration of the reduction mechanism 54c is not limited thereto, and the reduction mechanism 54c may reduce the rotation speed by, for example, using a small-diameter gear connected to the rotating shaft 54a1 of the rotating electric machine 54a and a large-diameter gear connected to the ball screw 54f.

[0024] The ball screw 54f may convert the rotational motion of the rotating electric machine 54a into the linear motion of linearly moving members such as the nut 54e and the rod 54b. The ball screw 54f may include a screw shaft 54f1 and balls 54f2. The balls 54f2 may be interpreted as rolling elements provided between the nut 54e and the screw shaft 54f1.

[0025] When the rotating electric machine 54a rotates, i.e., when the rotary shaft 54a1 rotates, the torque of the rotating electric machine 54a is transmitted to the ball screw 54f. As the ball screw 54f rotates, the rotational motion of the ball screw 54f is converted into linear motion of the nut 54e provided in the case 54d. As a result, the rod 54b connected to the nut 54e reciprocates, i.e., moves forward and backward, relative to the case 54d.

[0026] The rotating shaft 54a1, the reduction mechanism 54c, the ball screw 54f, the nut 54e, etc. may be interpreted as a mechanical element 540 that moves the rod 54b, which drives the work machine 5, back and forth. More strictly, the rotating shaft 54a1, the first pulley 54c1, the belt 54c3, the second pulley 54c2, the ball screw 54f, and the nut 54e may be interpreted as a mechanical element 540 that moves the rod 54b back and forth.

[0027] Although not shown in FIGS. 1 and 4, the pair of left and right crawlers 2a and the rotating part that rotates the cab 4 are also examples of work machines driven by the rotating electric machine 54a.

[0028] As shown in FIG. 3 , the rotating electric machine 54a is provided with a holding mechanism 55. The holding mechanism 55 locks the rotating shaft 54a1 of the rotating electric machine 54a in response to an instruction from the control device 7, thereby maintaining the stopped state of the rotating electric machine 54a. As a result, the rotating shaft 54a1 becomes non-rotatable, and the stopped state of the load, such as the boom 51, connected to the electric cylinder 54 is maintained. Furthermore, the holding mechanism 55 releases the stopped state of the rotating electric machine 54a by unlocking the rotating shaft 54a1 of the rotating electric machine 54a in response to an instruction from the control device 7. As a result, the rotating shaft 54a1 becomes rotatable, and the stopped state of the load, such as the boom 51, connected to the electric cylinder 54 is released. Note that, hereinafter, locking the rotating shaft 54a1 of the rotating electric machine 54a may be simply referred to as locking the rotating electric machine 54a, and unlocking the rotating shaft 54a1 of the rotating electric machine 54a may be simply referred to as unlocking the rotating electric machine 54a. In the example of FIG. 3, the holding mechanism 55 is configured to be provided inside the rotating electric machine 54a, but it may also be configured to be provided outside the rotating electric machine 54a.

[0029] Next, the hardware configuration of the control device 7 will be described with reference to Fig. 4. Fig. 4 is a diagram showing the hardware configuration of the control device 7 according to an embodiment of the present disclosure. The control device 7 includes a control unit 21, a communication unit 22, and a storage unit 23.

[0030] The control unit 21 is configured as a device including a general computer. The control unit 21 includes a CPU (Central Processing Unit) 21A, a ROM (Read Only Memory) 21B, a RAM (Random Access Memory) 21C, and an input / output interface (I / O) 21D. The CPU 21A, ROM 21B, RAM 21C, and I / O 21D are connected to each other via a bus 21E. The bus 21E includes a control bus, an address bus, a data bus, etc.

[0031] The I / O 21D is connected to a communication unit 22, a storage unit 23, and a sensor group 200. The communication unit 22 is an interface for communicating with external devices such as the inverter 10, the holding mechanism 55, and the vehicle controller 30. Although only one holding mechanism 55 is shown in Fig. 4 for convenience, a holding mechanism 55 is provided for each rotating electric machine 54a.

[0032] The storage unit 23 is configured as a non-volatile external storage device such as a hard disk, etc. The storage unit 23 stores a control program 23A.

[0033] The CPU 21A is an example of a computer. The term "computer" as used herein refers to a processor in a broad sense, and includes a general-purpose processor (e.g., the CPU 21A) or a dedicated processor (e.g., a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a programmable logic device, etc.).

[0034] The control program 23A may be stored in a non-volatile, non-transitory recording medium or distributed via a network and appropriately installed in the control device 7, thereby being stored in the storage unit 23. The control program 23A may also be appropriately updated via so-called OTA (Over The Air).

[0035] Examples of non-volatile non-transient recording media include CD-ROMs (Compact Disc Read Only Memory), magneto-optical disks, HDDs (Hard Disk Drives), DVD-ROMs (Digital Versatile Disc Read Only Memory), flash memories, memory cards, etc.

[0036] The sensor group 200 may include a wheel speed sensor, an acceleration sensor, a current sensor, an accelerator sensor, a temperature sensor, a gradient sensor, a brake sensor, a yaw rate sensor, a rotation speed sensor, and the like.

[0037] The sensor group 200 may also include a sensor that detects at least one of the speed of the vehicle 100 , the speed of the work implement 5 , the position of the work implement 5 , the torque of the work implement 5 , and the propulsive force of the work implement 5 .

[0038] The rotation speed sensor may be understood as a sensor for detecting the rotation angle and rotation speed of the rotating electric machine 54 a. The rotation speed sensor is, for example, a resolver or a rotary encoder, and detects the rotation angle and rotation speed of the rotor of the rotating electric machine 54 a. A signal indicating the rotation speed detected by the rotation speed sensor is input to the control device 7.

[0039] The current sensor may be understood as a sensor for detecting the value of the current flowing through the rotating electric machine 54a. As an example, the current sensor detects the current flowing through any two windings (e.g., the V phase and the W phase) among the windings of the U phase, V phase, and W phase. A signal indicating the value of the drive current detected by the current sensor is input to the control device 7.

[0040] The temperature sensor may be interpreted as a sensor for detecting the temperatures of a plurality of switch elements included in the inverter 10. A signal indicating the temperature detected by the temperature sensor is input to the control device 7.

[0041] The inverter 10 may convert the DC power supplied from the battery 6 into AC power in accordance with instructions from the control device 7, and supply the AC power to the rotating electric motors 54a in the electric cylinders 54 provided in each of the boom 51, arm 52, and bucket 53, thereby controlling the rotation of the rotating electric motors 54a.

[0042] A boom 51, an arm 52, a bucket 53, etc. are connected to each of the multiple electric cylinders 54, and these may be considered as part of the load of the electric cylinder 54 or the rotating electric machine 54a.

[0043] 5 is a diagram showing an example configuration of a drive unit 60 including a rotating electric machine 54a and an inverter 10. The rotating electric machine 54a includes a stator 153, a rotor 154, a current sensor 203, and a rotation speed sensor 211. The rotating electric machine 54a is a three-phase motor generator, and the stator 153 has windings 155U, 155V, and 155W of multiple phases. The winding 155U is a U-phase winding, the winding 155V is a V-phase winding, and the winding 155W is a W-phase winding. The current sensor 203, for example, detects the current flowing through the winding 155V and the current flowing through the winding 155W. The rotation speed sensor 211 is, for example, a resolver, and detects the rotation angle and rotation speed of the rotor 154.

[0044] The inverter 10 has six power elements 156Uu, 156Ud, 156Vu, 156Vd, 156Wu, and 156Wd. Hereinafter, when there is no need to distinguish between the six power elements 156Uu, 156Ud, 156Vu, 156Vd, 156Wu, and 156Wd, the six power elements 156Uu, 156Ud, 156Vu, 156Vd, 156Wu, and 156Wd will be referred to as "power elements 156." These power elements 156 may be interpreted as inverter elements or switch elements. Each power element 156 is, for example, a power transistor. The power elements 156Uu and 156Ud are U-phase power elements, the power elements 156Vu and 156Vd are V-phase power elements, and the power elements 156Wu and 156Wd are W-phase power elements. The power elements 156Uu and 156Ud are bridge-connected to the winding 155U, the power elements 156Vu and 156Vd are bridge-connected to the winding 155V, and the power elements 156Wu and 156Wd are bridge-connected to the winding 155W.

[0045] The inverter 10 has a plurality of temperature sensors 157. The temperature sensor 157 may be provided for each of the plurality of power elements 156.

[0046] The vehicle controller 30 transmits vehicle state information relating to the vehicle state of the vehicle 100 to the control device 7. The vehicle state information includes, for example, information on whether or not an abnormal state has occurred in which rotation of the rotating electric machine 54a should be stopped, and, if an abnormal state has occurred, information on the details of the abnormal state.

[0047] Abnormal conditions in which the rotation of the rotating electric machine 54a should be stopped include, but are not limited to, a condition in which a malfunction has occurred in the rotating electric machine 54a, a condition in which the inverter 10 has malfunctioned, a condition in which the harness system related to at least one of the rotating electric machine 54a and the inverter 10 has malfunctioned, a condition in which the battery 6 is nearly fully charged and regeneration is not possible, and so on.

[0048] Next, an example of the functional configuration of the CPU 21A of the control device 7 will be described with reference to FIG.

[0049] Fig. 6 is a block diagram showing the functional configuration of the CPU 21A of the control device 7. As shown in Fig. 6, the CPU 21A functionally includes an acquisition unit 70 and a control unit 72. The CPU 21A functions as each functional unit by reading and executing a control program 23A stored in the storage unit 23.

[0050] The acquisition unit 70 acquires, from the vehicle controller 30, vehicle state information relating to the vehicle state of the vehicle 100, which is a work vehicle equipped with a work implement 5 driven by a rotating electric machine 54a.

[0051] The control unit 72 controls the holding mechanism 55 that holds the rotating electric machine 54a in a stopped state, based on the vehicle state information acquired by the acquisition unit 70. This makes it possible to operate the holding mechanism 55 and improve the efficiency and safety of driving the vehicle 100, even if the operator operating the vehicle 100 is not aware of any abnormality.

[0052] Specifically, when the control unit 72 detects an abnormality in the rotating electric machine 54a, it activates the holding mechanism 55. This forcibly stops the rotating electric machine 54a, making it possible to ensure safety.

[0053] Furthermore, even when an abnormality related to the rotating electric machine 54a is detected, if the vehicle state of the vehicle 100 is an inoperable state in which the holding mechanism 55 should not be activated, the control unit 72 does not activate the holding mechanism 55. Here, the inoperable state in which the holding mechanism 55 should not be activated refers to a state in which safety may not be ensured if the holding mechanism 55 is activated to stop the rotating electric machine 54a.

[0054] The control unit 72 determines whether or not the vehicle 100 is in an inoperable state based on, for example, at least one of the speed (vehicle speed) of the vehicle 100, the speed of the work implement 5, the position of the work implement 5, the torque of the work implement 5, and the propulsive force of the work implement 5. The vehicle speed of the vehicle 100, the speed of the work implement 5, the position of the work implement 5, the torque of the work implement 5, and the propulsive force of the work implement 5 can be acquired from sensors included in the sensor group 200.

[0055] For example, the control unit 72 determines that the vehicle 100 is in an inoperable state if the speed of the vehicle 100 is equal to or greater than a speed at which safety may not be ensured if the rotating electric machine 54a that drives the crawler 2a is suddenly stopped.

[0056] In addition, the control unit 72 determines that the work machine 5 is in an inoperable state if the speed of the work machine 5 is equal to or greater than a threshold speed at which safety may not be ensured if the rotating electric machine 54a that drives the work machine 5 is suddenly stopped.

[0057] Furthermore, if the position of the work machine 5 is such that safety may not be ensured if the rotating electric machine 54a that drives the work machine 5 is suddenly stopped, the control unit 72 determines that the work machine 5 is in an inoperable state.

[0058] Furthermore, the control unit 72 determines that the working machine 5 is in an inoperable state when the torque of the working machine 5 is such that safety may not be ensured if the rotating electric machine 54a that drives the working machine 5 is suddenly stopped.

[0059] Furthermore, the control unit 72 determines that the working machine 5 is in an inoperable state if the thrust of the working machine 5 is such that safety may not be ensured if the rotating electric machine 54a that drives the working machine 5 is suddenly stopped.

[0060] In this way, even if control unit 72 detects an abnormality in rotating electric machine 54a, if the vehicle state of vehicle 100 is an inoperable state in which holding mechanism 55 should not be activated, control unit 72 does not activate holding mechanism 55. Therefore, it is possible to prevent a situation in which the safety of vehicle 100 cannot be ensured by activating holding mechanism 55.

[0061] Furthermore, when the rotating electric machine 54 a is in the inoperable state as described above, the control unit 72 may control the rotating electric machine 54 a to be in an operable state in which the holding mechanism 55 can be operated.

[0062] For example, when the control unit 72 determines that the vehicle 100 is in an inoperable state because the speed of the vehicle 100 is equal to or greater than the threshold speed, the control unit 72 reduces the rotation speed of the rotating electric machine 54a that drives the crawler 2a, thereby decelerating the vehicle 100 so that the speed of the vehicle 100 becomes less than the threshold speed. This makes it possible to put the holding mechanism 55 in an operable state.

[0063] In addition, if the control unit 72 determines that the position of the work machine 5 is in an inoperable state because it is at a position where safety may not be ensured if the rotating electric motor 54a that drives the work machine 5 is suddenly stopped, it controls the rotating electric motor 54a that drives the work machine 5 so that the position of the work machine 5 is at a position where safety can be ensured.

[0064] In addition, if the control unit 72 determines that the work machine 5 is in an inoperable state because the torque of the work machine 5 is such that safety may not be ensured if the rotating electric motor 54a that drives the work machine 5 is suddenly stopped, the control unit 72 controls the rotating electric motor 54a that drives the work machine 5 so that the torque of the work machine 5 becomes a torque that can ensure safety.

[0065] In addition, if the control unit 72 determines that the thrust of the work machine 5 is in an inoperable state because it is a thrust that may not ensure safety if the rotating electric motor 54a that drives the work machine 5 is suddenly stopped, the control unit 72 controls the rotating electric motor 54a that drives the work machine 5 so that the thrust of the work machine 5 becomes a thrust that can ensure safety.

[0066] In this way, when the control unit 72 becomes inoperable as described above, the rotating motor 54a controls the rotating motor 54a to become operable, allowing the holding mechanism 55 to be quickly put into an operable state.

[0067] Furthermore, the control unit 72 may activate the holding mechanism 55 when the target rotation speed of the rotating electric machine 54a is a rotation speed at which the vehicle 100 is considered to be in a stopped state, or when an instruction to stop the vehicle 100 is received. This makes it possible to stop the supply of power to the rotating electric machine 54a. For example, cases in which the target rotation speed of the rotating electric machine 54a is a rotation speed at which the vehicle 100 is considered to be in a stopped state include, but are not limited to, when the crawler 2a receives a reaction force during excavation work, when the vehicle 100 is stopped on a slope, when the work machine 5 is in a stopped state while maintaining the position of the work machine 5, such as when performing a pushing work, or when working with only specific parts fixed.

[0068] Furthermore, an instruction to stop the vehicle 100 may be, for example, when the driver of the vehicle 100 operates the shift lever to the parking position, but is not limited to this.

[0069] In this way, when the target rotation speed of the rotating motor 54a is a rotation speed at which the vehicle 100 can be considered to be in a stopped state, or when the vehicle 100 is instructed to stop, by activating the holding mechanism 55, it is possible to reduce unnecessary energy consumption from the perspective of energy efficiency, and to improve the electric power consumption of the vehicle 100.

[0070] Furthermore, when the target rotation speed of the rotating electric machine 54a that drives the crawler 2a is a rotation speed at which the vehicle 100 is considered to be in a stopped state, or when the vehicle state of the vehicle 100 is an inoperable state in which the holding mechanism 55 should not be activated even when an instruction to stop the vehicle 100 has been given by the driver of the vehicle 100, the control unit 72 may not activate the holding mechanism 55. Whether or not the vehicle is in an inoperable state is determined based on at least one of the speed of the vehicle 100, the speed of the work implement 5, the position of the work implement 5, the torque of the work implement 5, and the propulsive force of the work implement 5, as described above.

[0071] In this way, even if it is desired to operate the holding mechanism 55 from the viewpoint of energy efficiency, the holding mechanism is not operated if the vehicle state of the vehicle 100 is an inoperable state in which the holding mechanism 55 should not be operated. Therefore, it is possible to prevent a situation in which the safety of the vehicle 100 cannot be ensured by operating the holding mechanism 55.

[0072] Furthermore, for example, if the holding mechanism 55 provided on the rotating electric machine 54a that drives the crawler 2a is frequently activated and deactivated, the rotating electric machine 54a may be stopped and rotated frequently, which may deteriorate drivability.

[0073] Therefore, the control unit 72 may be configured to activate the holding mechanism 55 when a certain time has elapsed since the previous activation and deactivation of the holding mechanism 55. This makes it possible to prevent the holding mechanism 55 from being activated and deactivated frequently, and to prevent a deterioration in drivability.

[0074] Next, a flowchart of the control process executed by the CPU 21A will be described with reference to Fig. 7. The control process of Fig. 7 is executed repeatedly. The control process of Fig. 7 is also executed for each of the plurality of rotating electrical machines 54a.

[0075] In step S100 , the CPU 21A acquires vehicle state information from the vehicle controller 30 .

[0076] In step S101, the CPU 21A determines whether or not the rotating electric machine 54a should be locked from a safety standpoint. Specifically, based on the vehicle state information acquired in step S100, the CPU 21A determines whether or not an abnormality related to the rotating electric machine 54a has been detected, i.e., whether or not an abnormal state has occurred that requires the rotation of the rotating electric machine 54a to be stopped.

[0077] If an abnormal condition has occurred that requires the rotation of the rotating electric machine 54a to be stopped, the process proceeds to step S102; if an abnormal condition has not occurred that requires the rotation of the rotating electric machine 54a to be stopped, the process proceeds to step S106.

[0078] In step S102, the CPU 21A determines whether it is safe to lock the rotating electric machine 54a. Specifically, it determines whether the vehicle state of the vehicle 100 is an inoperable state in which the holding mechanism 55 should not be operated. That is, it determines whether the vehicle state is an inoperable state based on at least one of the speed (vehicle speed) of the vehicle 100, the speed of the work implement 5, the position of the work implement 5, the torque of the work implement 5, and the propulsive force of the work implement 5.

[0079] If the holding mechanism 55 is not in an inoperable state, the process proceeds to step S103, and if the holding mechanism 55 is in an inoperable state, the process proceeds to step S108.

[0080] In step S103, the CPU 21A activates the holding mechanism 55 to lock the rotating electric machine 54a.

[0081] In step S104, the CPU 21A determines whether the locking of the rotating electric machine 54a has been completed, i.e., whether the operation of the holding mechanism 55 has been completed. Specifically, for example, the operation of the holding mechanism 55 is determined to be completed when a predetermined time has elapsed since the operation of the holding mechanism 55. Here, the predetermined time is set to a time from the start of operation of the holding mechanism 55 at which the locking of the rotating electric machine 54a can be considered to be completed. Alternatively, the load on the rotating electric machine 54a may be detected, and the locking of the rotating electric machine 54a may be determined to be completed when the detected load is equal to or less than a predetermined threshold. If it is determined in step S104 that the locking has been completed, the process proceeds to step S105. If it is determined that the locking has not been completed, the process repeats the determination of whether the locking has been completed.

[0082] In step S105, the CPU 21A sets the driving force of the rotary electric machine 54a to 0 Nm, that is, stops the power supply to the inverter 10. This reduces unnecessary power consumption.

[0083] In step S106, the CPU 21A determines whether a condition for locking the rotating electric machine 54a is met from the viewpoint of energy efficiency. Specifically, the condition for locking the rotating electric machine 54a from the viewpoint of energy efficiency is met when the target rotation speed of the rotating electric machine 54a is a rotation speed at which the vehicle 100 is considered to be in a stopped state, or when an instruction to stop the vehicle 100 has been issued.

[0084] If the conditions for locking the rotating electric machine 54a from the viewpoint of energy efficiency are met, the process proceeds to step S107, and if the conditions for locking the rotating electric machine 54a from the viewpoint of energy efficiency are not met, the process proceeds to step S108.

[0085] In step S107, the CPU 21A determines whether it is safe to lock the rotating electric machine 54a, similarly to step S102. Note that the threshold value used to determine whether it is safe to lock the rotating electric machine 54a may be set to a value different from the threshold value used in step S102.

[0086] In step S108, the CPU 21A unlocks the rotating electric machine 54a. That is, if the holding mechanism 55 is operating and the rotating electric machine 54a is locked, the CPU 21A releases the operation of the holding mechanism 55 and unlocks the rotating electric machine 54a. This allows the rotating electric machine 54a to rotate. On the other hand, if the holding mechanism 55 is not operating and the rotating electric machine 54a is unlocked, no particular action is taken.

[0087] As described above, in this embodiment, the holding mechanism 55 for maintaining the stopped state of the rotating electric machine 54a is controlled based on vehicle state information relating to the vehicle state of the vehicle 100 equipped with the work implement 5 driven by the rotating electric machine 54a. This allows the holding mechanism 55 for maintaining the stopped state of the rotating electric machine 54a that drives the work implement 5 of the vehicle 100 to be appropriately operated. Therefore, even if the operator operating the vehicle 100 is not aware of the safety or energy efficiency of driving the vehicle 100, the holding mechanism 55 can be operated as necessary to improve the safety or energy efficiency of driving the vehicle 100.

[0088] The present disclosure is not limited to the above-described embodiments, and various modifications and applications are possible within the scope of the gist of the present disclosure.

[0089] Furthermore, the configuration of the control device 7 described in the above embodiment (see Figure 4) is one example, and it goes without saying that unnecessary parts may be deleted or new parts may be added within the scope of the gist of the technology disclosed herein.

[0090] Furthermore, the processing flow of the control program 23A described in the above embodiment (see Figure 7) is also an example, and it goes without saying that unnecessary steps may be deleted, new steps may be added, or the processing order may be rearranged within the scope of the gist of the technology disclosed herein.

[0091] The controller and methods described herein may be implemented by a special-purpose computer having a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by a special-purpose computer having a processor configured with dedicated hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers configured by a combination of a processor executing a computer program and one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0092] The following notes are provided regarding the technology of the present disclosure.

[0093] <Notes> (Note 1) A control device (7) comprising: an acquisition unit (70) that acquires vehicle state information related to the vehicle state of a work vehicle (100) equipped with a work implement (5) driven by an electric motor (54a); and a control unit (72) that controls a holding mechanism (55) that holds the electric motor in a stopped state based on the vehicle state information. (Note 2) A control device as set forth in Note 1, wherein the control unit activates the holding mechanism when an abnormality related to the electric motor is detected. (Note 3) A control device as set forth in Note 2, wherein the control unit does not activate the holding mechanism when the vehicle state is an inoperable state in which the holding mechanism should not be activated. (Note 4) A control device as set forth in Note 3, wherein the control unit controls the electric motor to bring the holding mechanism into an operable state in which it is possible to activate the holding mechanism. (Note 5) A control device as set forth in Note 1, wherein the control unit activates the holding mechanism when a target rotation speed of the electric motor is a rotation speed at which the work vehicle is considered to be in a stopped state, or when an instruction to stop the work vehicle is received. (Supplementary Note 6) The control device according to Supplementary Note 5, wherein the control unit does not activate the holding mechanism when the vehicle state is an inoperable state in which the holding mechanism should not be activated. (Supplementary Note 7) The control device according to any one of Supplementary Notes 1 to 6, wherein the control unit activates the holding mechanism when a certain time has elapsed since the holding mechanism was previously activated and then deactivated. (Supplementary Note 8) An agricultural machine equipped with the control device according to any one of Supplementary Notes 1 to 7. (Supplementary Note 9) A construction machine equipped with the control device according to any one of Supplementary Notes 1 to 7. (Supplementary Note 10) A control method, wherein at least one processor (21A) executes processing including: acquiring vehicle state information relating to the vehicle state of a work vehicle equipped with a work implement driven by an electric motor, and controlling a holding mechanism that maintains the electric motor in a stopped state based on the vehicle state information. (Supplementary Note 11) A control program (23A) that causes at least one processor to execute processing including: acquiring vehicle state information relating to the vehicle state of a work vehicle equipped with a work implement driven by an electric motor; and controlling a holding mechanism that holds the electric motor in a stopped state based on the vehicle state information.

Claims

1. A control device (7) comprising: an acquisition unit (70) that acquires vehicle state information relating to the vehicle state of a work vehicle (100) equipped with a work implement (5) driven by an electric motor (54a); and a control unit (72) that controls a holding mechanism (55) that holds the electric motor in a stopped state based on the vehicle state information.

2. The control device according to claim 1, wherein the control unit activates the holding mechanism when an abnormality related to the electric motor is detected.

3. The control device according to claim 2, wherein the control unit does not activate the holding mechanism when the vehicle state is an inoperable state in which the holding mechanism should not be activated.

4. The control device according to claim 3, wherein the control unit controls the electric motor so as to bring the holding mechanism into an operable state in which it can be operated.

5. A control device as described in claim 1, wherein the control unit activates the holding mechanism when the target rotation speed of the electric motor is a rotation speed at which the work vehicle can be considered to be in a stopped state, or when an instruction to stop the work vehicle is received.

6. The control device according to claim 5, wherein the control unit does not activate the holding mechanism when the vehicle state is an inoperable state in which the holding mechanism should not be activated.

7. The control device according to claim 1, wherein the control unit activates the holding mechanism when a predetermined time has elapsed since the holding mechanism was last activated and then deactivated.

8. An agricultural machine equipped with a control device according to any one of claims 1 to 7.

9. A construction machine equipped with the control device according to any one of claims 1 to 7.

10. A control method in which at least one processor (21A) executes processing including: acquiring vehicle status information relating to the vehicle status of a work vehicle equipped with a work implement driven by an electric motor; and controlling a holding mechanism that holds the electric motor in a stopped state based on the vehicle status information.

11. A control program (23A) that causes at least one processor to execute processing including: acquiring vehicle status information relating to the vehicle status of a work vehicle equipped with a work implement driven by an electric motor; and controlling a holding mechanism that holds the electric motor in a stopped state based on the vehicle status information.

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