System for controlling work machine, and method for controlling work machine

Abstract

To further reduce power consumption when the state of charge of an electricity storage device is low.SOLUTION: A system 1 for controlling a work machine 100 comprises a controller 9. The work machine comprises an electric motor 4 driven by power from an electricity storage device 2, and a hydraulic pump 12 driven by the electric motor 4. The work machine is driven by a hydraulic oil supplied from the hydraulic pump 12. The controller 9 detects the state of charge of the electricity storage device 2, and controls, on the basis of the state of charge, the idling rotational speed in performing automatic idling control.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In electric hydraulic excavators, in order to reduce the power consumption of the electric motor, an auto idle control is known in which the voltage of the electric motor is controlled so that the rotation speed is low when the operating position of the operating means is in the neutral position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-078277 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, when the operating position of the operating means is in the neutral position, the voltage of the electric motor is controlled so that the rotation speed is low idling, thereby making it possible to reduce the power consumption of the battery. However, since the control in Patent Document 1 is not related to the remaining charge of the battery, it is desirable to further reduce the power consumption when the remaining charge of the power storage device becomes low.

[0005] The present disclosure aims to further reduce power consumption when the remaining amount of stored electricity in a power storage device becomes low. [Means for solving the problem]

[0006] The system for controlling a work machine according to the present disclosure is a system for controlling a work machine that includes an electric motor driven by electricity from a power storage device and a hydraulic pump driven by the electric motor, and is driven by hydraulic oil supplied from the hydraulic pump, and includes a controller that detects the remaining amount of electricity stored in the power storage device and controls the idle speed when performing auto idle control based on the remaining amount of electricity stored.

[0007] A method for controlling a work machine according to the present disclosure is a method for controlling a work machine driven by power from a power storage device, and includes detecting the remaining amount of power stored in the power storage device, and controlling the idle speed when performing auto idle control based on the remaining amount of power stored. [Effects of the Invention]

[0008] According to the present disclosure, when the remaining amount of stored power in the power storage device becomes low, it is possible to further reduce power consumption. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view that schematically shows the configuration of a work machine according to a first embodiment. [Figure 2] FIG. 2 is a diagram that schematically shows a configuration related to control of the work machine according to the first embodiment. [Figure 3] FIG. 3 is a block diagram showing a computer system according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of auto idle control when the remaining amount of stored electricity in the electricity storage device has not decreased to a predetermined threshold value according to the first embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of auto-idle control when the remaining amount of stored electricity in the electricity storage device drops to a predetermined threshold value according to the first embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of a method for controlling a work machine according to the first embodiment. [Figure 7]FIG. 7 is a diagram showing an example of auto idle control according to the second embodiment when the remaining amount of stored electricity in the electricity storage device has not decreased to a predetermined threshold value. [Figure 8] FIG. 8 is a diagram showing an example of auto idle control when the remaining amount of stored electricity in the electricity storage device drops to a predetermined threshold value according to the second embodiment. [Figure 9] FIG. 9 is a diagram that schematically shows a modified example of the configuration related to the control of the work machine. [Figure 10] FIG. 10 is a diagram that schematically shows a modified example of the configuration related to the control of the work machine. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiments. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0011] In the embodiments, an electrically driven hydraulic excavator powered by a battery, which is an electricity storage device, will be described as an example of a work machine. However, the present disclosure is also applicable to other work machines, such as a forklift, a wheel loader, a bulldozer, and a dump truck, in addition to hydraulic excavators.

[0012] [First embodiment] <Work machinery> Fig. 1 is a perspective view that shows a schematic configuration of a work machine according to Embodiment 1. As shown in Fig. 1, a work machine 100 in the embodiment is, for example, a hydraulic excavator.

[0013] The work machine 100 is equipped with a running body 102, a rotating body 103, and a work implement 105. The running body 102 has a travel motor 17 and tracks 171. The tracks 171 have a right track 171R and a left track 171L. The work machine 100 is capable of traveling by rotation of the tracks 171. Note that the work machine 100 may have tires instead of the tracks 171.

[0014] The rotating body 103 is rotatably supported on the traveling body 102. The work implement 105 is rotatably connected to the rotating body 103. The work implement 105 has a boom 105A, an arm 105B, and a bucket 105C. The work implement 105 is driven by a cylinder 18, which will be described later. The rotating body 103 has a cab 112. The cab 112 contains an operation device 5 and a rotation speed setting device 7. The work machine 100 is equipped with a system 1.

[0015] <System> Figure 2 is a diagram that shows a schematic configuration related to control of a work machine according to the first embodiment. System 1 is a system for controlling a work machine 100 that is driven by electric power from a power storage device 2. System 1 includes a controller 9 that is made up of at least one processor.

[0016] As shown in Fig. 2, the system 1 includes a power storage device 2, an inverter 3, an electric motor 4, an operation device 5, a rotation speed setting device 7, and a controller 9. The system 1 further includes a main hydraulic pump 12, a pilot hydraulic pump 13, a hydraulic control valve 15, a swing motor 16, a traveling motor 17, and a cylinder 18. In the embodiment, the swing motor 16, the traveling motor 17, and the cylinder 18 are hydraulic actuators driven by hydraulic oil supplied from the main hydraulic pump 12, but are not limited to this. For example, any of the swing motor 16, the traveling motor 17, and the cylinder 18 may be an electric actuator driven by electric power from the power storage device 2.

[0017] The work machine 100 has a swing motor 16 that causes the swing body 103 to swing. The work machine 100 travels by rotating the tracks 171 using the travel motor 17. The work machine 100 has a work implement 105 that is actuated by a cylinder 18. In this embodiment, the work machine 100 is equipped with a right travel motor 17R and a left travel motor 17L to rotate the right track 171R and the left track 171L.

[0018] The power storage device 2 supplies power to drive the work machine 100. The power storage device 2 outputs to the controller 9 state of charge (SOC) data indicating the remaining amount of stored power.

[0019] The inverter 3 supplies electric power from the power storage device 2 to the electric motor 4. The inverter 3 supplies electric power to the electric motor 4 based on a motor control command from the controller 9. The inverter 3 controls the electric motor 4 based on the motor control command from the controller 9.

[0020] The electric motor 4 is driven by electric power from the power storage device 2. The electric motor 4 is the power source of the work machine 100. The electric motor 4 supplies power for driving the work machine 100. The electric motor 4 drives the main hydraulic pump 12, the pilot hydraulic pump 13, etc. The electric motor 4 outputs power to the main hydraulic pump 12, the pilot hydraulic pump 13, etc.

[0021] The operating device 5 is an operator input device for operating the work machine 100. The operating device 5 includes, for example, a work machine operating lever 51 and a travel operating pedal 52.

[0022] The work implement control lever 51 is a work implement operating device for controlling the work implement 105. The work implement control lever 51 is operated by an operator to control, for example, each of the boom 105A, arm 105B, and bucket 105C. By operating the work implement control lever 51, the operator controls the operating speed of the cylinder 18 that drives the boom 105A, arm 105B, and bucket 105C. The work implement control lever 51 includes a lever operation amount sensor (not shown). The lever operation amount sensor is, for example, a pilot pressure sensor that detects pilot pressure that changes depending on the operation amount. The lever operation amount sensor outputs an operation command indicating the operation amount of the work implement control lever 51 to the controller 9.

[0023] 2, the work implement control lever 51 is shown, but the number of control levers is not limited. The work implement control lever 51 may have control levers associated with the boom 105A, the arm 105B, and the bucket 105C. The work implement control lever 51 may also be associated with the rotation operation of the revolving unit 103 relative to the traveling unit 102. The work implement control lever 51 may be a single control lever that is used for a combination of any two of the operation of the boom 105A, the operation of the arm 105B, the operation of the bucket 105C, and the rotation operation of the revolving unit 103.

[0024] The travel operation pedal 52 is a travel operation device for controlling the travel of the work machine 100. The travel operation pedal 52 is operated by an operator, for example, to control the travel speed of the work machine 100. The operator controls the rotation speed of the travel motor 17 by operating the travel operation pedal 52. The travel operation pedal 52 includes a pedal operation amount sensor (not shown). The pedal operation amount sensor is configured, for example, with a potentiometer or the like. The pedal operation amount sensor outputs an operation command indicating the operation amount of the travel operation pedal 52 to the controller 9.

[0025] The rotation speed setting device 7 is an operating device for setting a target rotation speed of the electric motor 4. The rotation speed setting device 7 is operated by an operator. The rotation speed setting device 7 is, for example, a dial switch. The rotation speed setting device 7 outputs an operation command indicating the target rotation speed of the electric motor 4 to the controller 9.

[0026] The main hydraulic pump 12 supplies hydraulic oil for operating the work machine 105. The main hydraulic pump 12 is driven by the electric motor 4 to discharge hydraulic oil. The main hydraulic pump 12 is, for example, a variable displacement hydraulic pump whose discharge capacity changes depending on the tilt angle of a swash plate. The main hydraulic pump 12 has a swash plate drive device 11 for controlling the tilt angle of the swash plate. The swash plate drive device 11 controls the flow rate of hydraulic oil discharged from the main hydraulic pump 12 based on a control command from the controller 9. The swash plate drive device 11 controls the tilt angle of the swash plate of the main hydraulic pump 12. The swash plate drive device 11 is, for example, a proportional solenoid valve, and controls the tilt angle of the swash plate of the main hydraulic pump 12 based on an energized current from the controller 9. The hydraulic oil discharged from the main hydraulic pump 12 is supplied to the swing motor 16, the travel motor 17, and the cylinder 18 via a hydraulic circuit.

[0027] The pilot hydraulic pump 13 supplies hydraulic oil to the operating device 5 .

[0028] The hydraulic control valve 15 is a flow direction control valve. The hydraulic control valve 15 moves a spool (not shown) according to the operating direction of each operating lever of the operating device 5, and controls the flow rate and flow direction of hydraulic oil to each hydraulic actuator. The hydraulic control valve 15 supplies hydraulic oil according to the operating amount of the operating device 5 to hydraulic actuators such as the swing motor 16, the travel motor 17, and the cylinder 18.

[0029] The swing motor 16 is a motor for swinging that generates a driving force for swinging the swing body 103. The swing motor 16 is driven by hydraulic oil discharged from the main hydraulic pump 12.

[0030] The travel motor 17 is a motor for travel that generates a driving force for rotating the crawler belt 171. The travel motor 17 is driven by hydraulic oil discharged from the main hydraulic pump 12. The rotation speed and rotation direction of the travel motor 17 are changed according to the discharge direction of the hydraulic oil from the main hydraulic pump 12.

[0031] The cylinder 18 is a cylinder for driving the work implement 105. The cylinder 18 is driven by hydraulic oil discharged from the main hydraulic pump 12. The cylinder 18 is, for example, a boom cylinder 126A, an arm cylinder 126B, or a bucket cylinder 126C.

[0032] The controller 9 includes at least one processor and a memory 91. The controller 9 performs processing for controlling the work machine 100. The memory 91 stores data and programs for controlling the work machine 100. The controller 9 is electrically connected to each of the power storage device 2, the inverter 3, the swash plate drive device 11, the operation device 5, and the rotation speed setting device 7.

[0033] The memory 91 stores a determination time, which is a threshold value for the time period during which the operating device 5 is not operated (a no-operation state). In the embodiment, the memory 91 stores a first determination time and a second determination time that is shorter than the first determination time. The first determination time is a determination time when it is determined that the remaining amount of power stored in the power storage device 2 is greater than a predetermined threshold value. The second determination time is a determination time when it is determined that the remaining amount of power stored in the power storage device 2 is equal to or less than a predetermined threshold value.

[0034] The memory 91 stores the speed at which the rotation speed of the electric motor 4 is returned to the target rotation speed when auto-idle control, which will be described later, is released. In this embodiment, the memory 91 stores a first return speed and a second return speed that is slower than the first return speed. The first return speed is the return speed when it is determined that the remaining amount of electricity stored in the power storage device 2 is greater than a predetermined threshold. The second return speed is the return speed when it is determined that the remaining amount of electricity stored in the power storage device 2 is equal to or less than the predetermined threshold.

[0035] The controller 9 detects the remaining amount of electricity stored in the power storage device 2. The controller 9 obtains, from the power storage device 2, charge state data indicating the remaining amount of electricity stored in the power storage device 2.

[0036] The controller 9 acquires an operation command from the operating device 5. More specifically, the controller 9 acquires a work machine operation command from a work machine operation lever 51. The controller 9 acquires a travel operation command from a travel operation pedal 52.

[0037] The controller 9 controls the inverter 3 in response to an operation command from the operating device 5, thereby controlling the rotation speed of the electric motor 4. The controller 9 controls the rotation speed of the electric motor 4, for example, by adjusting a target value and gain of the rotation speed of the electric motor 4 and controlling the motor current supplied to the electric motor 4.

[0038] The controller 9 controls the main hydraulic pump 12 by outputting a control command to the swash plate drive device 11 to control the tilt angle of the swash plate of the main hydraulic pump 12 in response to an operation command from the operation device 5. In other words, the controller 9 controls the flow rate of hydraulic oil discharged from the main hydraulic pump 12 and the absorption torque by controlling the swash plate drive device 11 in response to an operation command from the operation device 5.

[0039] The controller 9 determines whether the operation device 5 is being operated based on an operation command from the operation device 5. For example, when the operation amount of the operation device 5 is smaller than a predetermined threshold, the controller 9 determines that the operation device 5 is not being operated (non-operation state).

[0040] When the operating device 5 remains unoperated, the controller 9 performs control (auto idle control) to reduce the rotation speed of the electric motor 4 from the target rotation speed to a predetermined idle rotation speed. In the embodiment, the state in which the rotation speed of the electric motor 4 is reduced to the predetermined idle rotation speed by the auto idle control is referred to as the auto idle state. Whether or not to enable the auto idle control may be set by an operator.

[0041] The controller 9 controls the timing for reducing the rotation speed of the electric motor 4 from a target rotation speed to a predetermined idle rotation speed based on the detected remaining amount of stored power in the power storage device 2. The controller 9 determines a judgment time based on the detected remaining amount of stored power in the power storage device 2. The controller 9 judges whether or not the non-operation state of the operating device 5 has continued for the judgment time based on an operation command from the operating device 5. If the controller 9 judges that the non-operation state of the operating device 5 has continued for the judgment time, it starts auto-idle control.

[0042] In the embodiment, when it is determined that the detected remaining amount of stored power of the power storage device 2 is greater than a predetermined threshold, the controller 9 selects the first determination time stored in the memory 91. When it is determined that the detected remaining amount of stored power of the power storage device 2 is equal to or less than the predetermined threshold, the controller 9 selects the second determination time stored in the memory 91. Note that when the auto idle control is set to be disabled by an operator's operation, the controller 9 may enable the auto idle control and select the second determination time when it is determined that the detected remaining amount of stored power of the power storage device 2 is equal to or less than the predetermined threshold.

[0043] Furthermore, when the controller 9 determines that the detected remaining amount of stored power of the power storage device 2 is equal to or less than a predetermined threshold, the controller 9 may select a second determination time and notify the operator. The controller 9 may, for example, notify the operator that the remaining amount of stored power of the power storage device 2 is equal to or less than a predetermined threshold, that charging is recommended, or that the device will enter an auto-idle state if no operation is performed for the second determination time or longer. The notification to the operator is performed based on a control command from the controller 9, for example, by displaying a message on a monitor (not shown), outputting a sound from a speaker (not shown), or turning on a warning light (not shown).

[0044] Furthermore, in the auto idle state, the controller 9 determines whether or not the operating device 5 has been operated based on an operation command from the operating device 5. When the controller 9 determines that the operating device 5 has been operated, it cancels the auto idle control and returns the rotation speed of the electric motor 4 from a predetermined idle rotation speed to a target rotation speed.

[0045] The controller 9 controls the speed at which the rotation speed of the electric motor 4 is restored from a predetermined idle rotation speed to a target rotation speed based on the detected remaining amount of electricity stored in the electricity storage device 2. When it is determined that the remaining amount of electricity stored in the electricity storage device 2 is equal to or less than a predetermined threshold, the controller 9 controls the restoration of the rotation speed of the electric motor 4 to be slower than when it is determined that the remaining amount of electricity stored in the electricity storage device 2 is greater than the predetermined threshold.

[0046] The controller 9 determines the return speed based on the detected remaining amount of electricity stored in the power storage device 2. In the embodiment, when the controller 9 determines that the detected remaining amount of electricity stored in the power storage device 2 is greater than a predetermined threshold, the controller 9 selects the first return speed stored in the memory 91. When the controller 9 determines that the detected remaining amount of electricity stored in the power storage device 2 is equal to or less than the predetermined threshold, the controller 9 selects the second return speed stored in the memory 91.

[0047] 3 is a block diagram showing a computer system according to the first embodiment. The controller 9 includes a computer system. The controller 9 outputs a command signal for controlling the work machine.

[0048] As shown in FIG. 3 , the controller 9 has a processor 1001, a main memory 1002, a storage 1003, and an interface 1004. The processor 1001 executes a computer program to perform arithmetic processing for the operation of the work machine 100. The processor 1001 is, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The main memory 1002 is, for example, a non-volatile memory or a volatile memory. An example of the non-volatile memory is a ROM (Read Only Memory). An example of the volatile memory is a RAM (Random Access Memory). The storage 1003 is a non-transitory tangible storage medium. The storage 1003 is, for example, a magnetic disk, a magneto-optical disk, or a semiconductor memory. The storage 1003 may be an internal medium directly connected to the bus of the controller 9, or may be an external medium connected to the controller 9 via the interface 1004 or a communication line. The storage 1003 stores a computer program for controlling the work machine 1000. The controller 9 is not limited to being an integrated unit, but may be divided into multiple controllers.

[0049] FIG. 4 is a diagram showing an example of auto-idle control according to the first embodiment when the remaining amount of stored power of the power storage device 2 has not fallen to a predetermined threshold. FIG. 4(a) shows the operating state of the operating device 5. FIG. 4(b) shows the relationship between the motor control command and the rotation speed of the electric motor 4 when the remaining amount of stored power of the power storage device 2 has not fallen to the predetermined threshold, in other words, when the remaining amount of stored power of the power storage device 2 is greater than the predetermined threshold. As shown in FIG. 4(a), the operating device 5 is in an operating state from time 0 to time T1. The operating device 5 is in an unoperated state from time T1 to time T2. After time T2, the operating device 5 is in an operating state.

[0050] When the controller 9 determines that the remaining amount of electricity stored in the electricity storage device 2 is greater than the predetermined threshold, the controller 9 selects the first determination time T11 and the first return speed.

[0051] When the non-operation state of the operating device 5 continues from time T1 to the first determination time T11, as shown in FIG. 4(b), the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotational speed of the electric motor 4 from the target rotational speed r1 to the idle rotational speed r2.

[0052] When the operating device 5 is operated at time T2, the controller 9 outputs a motor control command to the inverter 3 to return the rotational speed of the electric motor 4 from the idle rotational speed r2 to the target rotational speed r1 based on the selected first return speed. In the example shown in FIG. 4(b), the controller 9 outputs a motor control command to return the rotational speed of the electric motor 4 to the target rotational speed r1 at time T13.

[0053] FIG. 5 is a diagram showing an example of auto-idle control when the remaining charge amount of the power storage device 2 according to the first embodiment drops to a predetermined threshold value. FIG. 5(a) shows the operation state of the operating device 5. FIG. 5(b) shows the relationship between the motor control command and the rotational speed of the electric motor 4 in a state where the remaining charge amount of the power storage device 2 has dropped to a predetermined threshold value, or in other words, in a state where the remaining charge amount of the power storage device 2 is less than or equal to the predetermined threshold value. As shown in FIG. 5(a), the operating device 5 is in an operating state from time 0 to time T1. The operating device 5 is in a non-operation state from time T1 to time T2. After time T2, the operating device 5 is in an operating state.

[0054] When the controller 9 determines that the remaining charge amount of the power storage device 2 is less than or equal to the predetermined threshold value, the controller 9 selects the second determination time T21 and the second return speed.

[0055] When the non-operation state of the operating device 5 continues from time T1 to the second determination time T21 (T21 < T11), as shown in FIG. 5(b), the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotational speed of the electric motor 4 from the target rotational speed r1 to the idle rotational speed r2.

[0056] When the operating device 5 is operated at time T2, the controller 9 outputs a motor control command to the inverter 3 to return the rotational speed of the electric motor 4 from the idle rotational speed r2 to the target rotational speed r1 based on the selected second return speed. In the example shown in FIG. 5(b), the controller 9 outputs a motor control command to the inverter 3 to return the rotational speed of the electric motor 4 to the target rotational speed r1 at time T23 (T13 < T23).

[0057] <Control method> A method for controlling a working machine will be described with reference to FIG. 6. FIG. 6 is a flowchart showing an example of a method for controlling a working machine according to the first embodiment. The controller 9 detects the remaining charge amount of the power storage device 2 (step ST11).

[0058] The controller 9 determines a determination time used for determining whether to start the auto idle control based on the detected remaining charge amount of the power storage device 2 (step ST12). More specifically, when the controller 9 determines that the detected remaining charge amount of the power storage device 2 is greater than a predetermined threshold value, the first determination time is selected. When the controller 9 determines that the detected remaining charge amount of the power storage device 2 is less than or equal to the predetermined threshold value, the second determination time is selected.

[0059] The controller 9 determines a return speed for returning the rotational speed of the electric motor 4 from a predetermined idle rotational speed to a target rotational speed when the auto idle control is released based on the detected remaining charge amount of the power storage device [2] (step ST13). More specifically, when the controller 9 determines that the detected remaining charge amount of the power storage device 2 is greater than a predetermined threshold value, the first return speed is selected. When the controller 9 determines that the detected remaining charge amount of the power storage device 2 is less than or equal to the predetermined threshold value, the second return speed is selected.

[0060] The controller 9 determines whether the operation device 5 is being operated based on an operation command from the operation device 5 (step ST14). If the controller 9 determines that the operation device 5 is being operated (Yes in step ST14), the controller 9 ends the processing. If the controller 9 determines that the operation device 5 is not being operated (No in step ST14), the controller 9 proceeds to step ST15.

[0061] The controller 9 determines whether or not the non-operation state of the operation device 5 has continued for the determination time or longer based on the determination time determined in step ST12 and the operation command from the operation device 5 (step ST15). If the controller 9 determines that the non-operation state of the operation device 5 has continued for the determination time or longer (Yes in step ST15), the controller 9 proceeds to step ST16. If the controller 9 determines that the non-operation state of the operation device 5 has not continued for the determination time or longer (No in step ST15), the controller 9 ends the process.

[0062] If it is determined that the non-operation state of the operating device 5 has continued for the determination time or longer (Yes in step ST15), the controller 9 executes auto-idle control (step ST16).

[0063] The controller 9 determines whether the operation device 5 has been operated based on an operation command from the operation device 5 (step ST17). If the controller 9 determines that the operation device 5 has been operated (Yes in step ST17), the controller 9 proceeds to step ST18. If the controller 9 determines that the operation device 5 has not been operated (No in step ST17), the controller 9 executes the process of step ST16 again.

[0064] If it is determined that the operating device 5 has been operated (Yes in step ST17), the controller 9 cancels the auto-idle control (step ST18). The controller 9 returns the rotation speed of the electric motor 4 from the predetermined idle rotation speed to the target rotation speed based on the return speed determined in step ST12.

[0065] <Effects> As described above, in the embodiment, the determination time used to determine whether or not to start auto idle control is determined based on the remaining amount of stored power in the power storage device 2. According to the embodiment, the timing for decelerating the rotation speed of the electric motor 4 from the target rotation speed to a predetermined idle rotation speed can be controlled based on the remaining amount of stored power in the power storage device 2. According to the embodiment, when the remaining amount of stored power in the power storage device 2 decreases, it is possible to further reduce power consumption.

[0066] In the embodiment, when it is determined that the remaining amount of stored power of the power storage device 2 is greater than a predetermined threshold, a first determination time is selected, and when it is determined that the remaining amount of stored power is equal to or less than the predetermined threshold, a second determination time that is shorter than the first determination time is selected. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the timing for decelerating the rotation speed of the electric motor 4 from the target rotation speed to a predetermined idle rotation speed can be made earlier. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the auto idle control is performed more frequently, thereby urging the operator to charge the power storage device 2.

[0067] In the embodiment, the speed at which the rotation speed of the electric motor 4 is restored from a predetermined idle rotation speed to a target rotation speed when auto idle control is released is determined based on the remaining amount of electricity stored in the power storage device 2. According to the embodiment, the speed at which the rotation speed of the electric motor 4 is restored from a predetermined idle rotation speed to a target rotation speed can be controlled based on the remaining amount of electricity stored in the power storage device 2. According to the embodiment, when the remaining amount of electricity stored in the power storage device 2 decreases, it is possible to further reduce power consumption.

[0068] In the embodiment, when it is determined that the remaining amount of stored power of the power storage device 2 is greater than a predetermined threshold, a first return speed is selected, and when it is determined that the remaining amount of stored power is equal to or less than the predetermined threshold, a second return speed slower than the first return speed is selected. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the return of the rotation speed of the electric motor 4 can be slowed down. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the return of the rotation speed of the electric motor 4 can be slowed down, thereby urging the operator to charge the battery.

[0069] In the embodiment, when the remaining amount of electricity stored in the power storage device 2 falls to a predetermined threshold, the operating speed of the hydraulic actuator, the rotation speed and maximum output of the electric motor 4 are not reduced, and the operator can be prompted to charge. According to the embodiment, when the remaining amount of electricity stored in the power storage device 2 falls, the operating speed of the hydraulic actuator, the rotation speed and maximum output of the electric motor 4 are not reduced, so that the operator can continue the same work as when the remaining amount of electricity stored in the power storage device 2 is not low.

[0070] [Second embodiment] The second embodiment will be described with reference to Figures 7 and 8. The second embodiment differs from the first embodiment in the processing in the controller 9. The same or corresponding reference numerals are used for the same configurations as the first embodiment, and the description thereof will be omitted. The same applies to the following embodiments.

[0071] The memory 91 stores a speed at which the rotation speed of the electric motor 4 is decelerated to the standby rotation speed when the operating device 5 is in a non-operated state. In this embodiment, the memory 91 stores a first deceleration speed and a second deceleration speed that is faster than the first deceleration speed. The first deceleration speed is a deceleration speed used when it is determined that the remaining amount of electricity stored in the power storage device 2 is greater than a predetermined threshold. The second deceleration speed is a deceleration speed used when it is determined that the remaining amount of electricity stored in the power storage device 2 is equal to or less than a predetermined threshold.

[0072] The memory 91 stores the idle rotation speed when performing auto idle control. In this embodiment, the memory 91 stores a first idle rotation speed and a second idle rotation speed that is lower than the first idle rotation speed. The first idle rotation speed is the idle rotation speed when it is determined that the remaining amount of electricity stored in the power storage device 2 is greater than a predetermined threshold. The second idle rotation speed is the idle rotation speed when it is determined that the remaining amount of electricity stored in the power storage device 2 is equal to or less than a predetermined threshold.

[0073] The controller 9 controls the speed at which the rotation speed of the electric motor 4 is reduced from the target rotation speed to the standby rotation speed when the operating device 5 is in a non-operated state, based on the detected remaining amount of electricity stored in the electricity storage device 2. When it is determined that the remaining amount of electricity stored in the electricity storage device 2 is equal to or less than a predetermined threshold, the controller 9 controls the rotation speed of the electric motor 4 to be reduced more quickly than when it is determined that the remaining amount of electricity stored in the electricity storage device 2 is greater than the predetermined threshold.

[0074] The controller 9 determines the deceleration speed based on the detected remaining amount of electricity stored in the power storage device 2. In the embodiment, when the controller 9 determines that the detected remaining amount of electricity stored in the power storage device 2 is greater than a predetermined threshold, the controller 9 selects the first deceleration speed stored in the memory 91. When the controller 9 determines that the detected remaining amount of electricity stored in the power storage device 2 is equal to or less than the predetermined threshold, the controller 9 selects the second deceleration speed stored in the memory 91.

[0075] The controller 9 controls the idle rotation speed when performing auto idle control based on the detected remaining amount of electricity stored in the power storage device 2. When it is determined that the remaining amount of electricity stored in the power storage device 2 is equal to or less than a predetermined threshold, the controller 9 controls the idle rotation speed to be lower than when it is determined that the remaining amount of electricity stored in the power storage device 2 is greater than the predetermined threshold.

[0076] The controller 9 determines the idle rotation speed based on the detected remaining amount of electricity stored in the power storage device 2. In the embodiment, when the controller 9 determines that the detected remaining amount of electricity stored in the power storage device 2 is greater than a predetermined threshold, the controller 9 selects the first idle rotation speed stored in the memory 91. When the controller 9 determines that the detected remaining amount of electricity stored in the power storage device 2 is equal to or less than the predetermined threshold, the controller 9 selects the second idle rotation speed stored in the memory 91.

[0077] FIG. 7 is a diagram showing an example of auto-idle control according to the second embodiment when the remaining amount of stored power of the power storage device 2 has not fallen to a predetermined threshold. FIG. 7(a) shows the operating state of the operating device 5. FIG. 7(b) shows the relationship between the motor control command and the rotation speed of the electric motor 4 when the remaining amount of stored power of the power storage device 2 has not fallen to the predetermined threshold, in other words, when the remaining amount of stored power of the power storage device 2 is greater than the predetermined threshold. As shown in FIG. 7(a), the operating device 5 is in an operating state from time 0 to time T1. The operating device 5 is in an unoperated state from time T1 to time T2. After time T2, the operating device 5 is in an operating state.

[0078] When the controller 9 determines that the remaining amount of stored electricity in the electricity storage device 2 is greater than the predetermined threshold, the controller 9 selects a first deceleration speed, a first determination time T11, a first idle rotation speed r4, and a first return speed.

[0079] As shown in Fig. 7(a), when the operating device 5 enters a non-operated state at time T1, the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotational speed of the electric motor 4 from the target rotational speed r1 to the standby rotational speed r3 based on the selected first deceleration speed, as shown in Fig. 7(b). In the example shown in Fig. 7(b), the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotational speed of the electric motor 4 to the standby rotational speed r3 at time T31.

[0080] Thereafter, if the non-operation state of the operating device 5 continues until the first judgment time T11, as shown in Figure 7(b), the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotation speed of the electric motor 4 from the standby rotation speed r3 to the first idle rotation speed r4.

[0081] At time T2, when the operating device 5 is operated, the controller 9 outputs a motor control command to the inverter 3 to return the rotation speed of the electric motor 4 from the first idle rotation speed r4 to the target rotation speed r1 based on the selected first return speed. In the example shown in Fig. 7(b), the controller 9 outputs a motor control command to the inverter 3 to return the rotation speed of the electric motor 4 to the target rotation speed r1 at time T13.

[0082] FIG. 8 is a diagram showing an example of auto idle control when the remaining charge amount of the power storage device 2 according to the second embodiment has decreased to a predetermined threshold value. FIG. 8(a) shows the operation state of the operation device 5. FIG. 8(b) shows the relationship between the motor control command and the rotational speed of the electric motor 4 in a state where the remaining charge amount of the power storage device 2 has decreased to a predetermined threshold value, or rather, in a state where the remaining charge amount of the power storage device 2 is less than or equal to the predetermined threshold value. As shown in FIG. 8(a), the operation device 5 is in an operating state from time 0 to time T1. The operation device 5 is in a non-operating state from time T1 to time T2. After time T2, the operation device 5 is in an operating state.

[0083] When the controller 9 determines that the remaining charge amount of the power storage device 2 is less than or equal to the predetermined threshold value, the second deceleration speed, the second determination time T21, the second idle rotational speed r5, and the second return speed are selected.

[0084] As shown in FIG. 8(a), when the operation device 5 becomes non-operating at time T1, the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotational speed of the electric motor 4 from the target rotational speed r1 to the standby rotational speed r3 based on the selected second deceleration speed, as shown in FIG. 8(b). In the example shown in FIG. 8(b), the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotational speed of the electric motor 4 to the standby rotational speed r3 at time T41 (T41 < T31).

[0085] Thereafter, when the non-operating state of the operation device 5 continues until the second determination time T21 (T21 < T11), as shown in FIG. 8(b), the controller 9 outputs a motor control command to the inverter 3 to decelerate the rotational speed of the electric motor 4 from the standby rotational speed r3 to the second idle rotational speed r5 (r5 < r4).

[0086] When the operating device 5 is operated at time T2, the controller 9 outputs a motor control command to the inverter 3 to return the rotational speed of the electric motor 4 from the second idle rotational speed r5 to the target rotational speed r1 based on the selected second return speed. In the example shown in FIG. 8(b), the controller 9 outputs a motor control command to the inverter 3 to return the rotational speed of the electric motor 4 to the target rotational speed r1 at time T23 (T13 < T23).

[0087] <Effect> As described above, in the embodiment, based on the remaining charge amount of the power storage device 2, when the operating device 5 becomes in the non-operated state, the speed at which the rotational speed of the electric motor 4 is decelerated from the target rotational speed to the standby rotational speed is determined. According to the embodiment, based on the remaining charge amount of the power storage device 2, the speed at which the rotational speed of the electric motor 4 is decelerated from the target rotational speed to the standby rotational speed can be controlled. According to the embodiment, when the remaining charge amount of the power storage device 2 decreases, further reduction of power consumption can be achieved.

[0088] In the embodiment, when it is determined that the remaining charge amount of the power storage device 2 is greater than a predetermined threshold, the first deceleration speed is selected, and when it is determined that the remaining charge amount is less than or equal to the predetermined threshold, a second deceleration speed faster than the first deceleration speed is selected. According to the embodiment, when the remaining charge amount of the power storage device 2 decreases, the rotational speed of the electric motor 4 can be quickly decelerated from the target rotational speed to the standby rotational speed. According to the embodiment, when the remaining charge amount of the power storage device 2 decreases, by causing the auto-idle control to occur frequently, the operator can be prompted to charge.

[0089] In the embodiment, based on the remaining charge amount of the power storage device 2, the determination time used for determining whether to start the auto-idle control is determined. According to the embodiment, based on the remaining charge amount of the power storage device 2, the timing at which the rotational speed of the electric motor 4 is decelerated from the target rotational speed to a predetermined idle rotational speed can be controlled. According to the embodiment, when the remaining charge amount of the power storage device 2 decreases, further reduction of power consumption can be achieved.

[0090] In the embodiment, when it is determined that the remaining amount of stored power of the power storage device 2 is greater than a predetermined threshold, a first determination time is selected, and when it is determined that the remaining amount of stored power is equal to or less than the predetermined threshold, a second determination time that is shorter than the first determination time is selected. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the timing for decelerating the rotation speed of the electric motor 4 from the target rotation speed to a predetermined idle rotation speed can be made earlier. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the auto idle control is performed more frequently, thereby urging the operator to charge the power storage device 2.

[0091] In the embodiment, the idle speed when performing auto idle control is determined based on the remaining amount of stored power in the power storage device 2. According to the embodiment, the idle speed when performing auto idle control can be controlled based on the detected remaining amount of stored power in the power storage device 2. According to the embodiment, when the remaining amount of stored power in the power storage device 2 decreases, it is possible to further reduce power consumption.

[0092] In the embodiment, when it is determined that the remaining amount of stored power in the power storage device 2 is greater than a predetermined threshold, a first idle rotation speed is selected, and when it is determined that the remaining amount of stored power is equal to or less than the predetermined threshold, a second idle rotation speed lower than the first idle rotation speed is selected. According to the embodiment, when the remaining amount of stored power in the power storage device 2 decreases, the idle rotation speed can be lowered. According to the embodiment, when the remaining amount of stored power in the power storage device 2 decreases, the idle rotation speed is lowered, thereby urging the operator to charge the power storage device 2.

[0093] In the embodiment, the speed at which the rotation speed of the electric motor 4 is restored from a predetermined idle rotation speed to a target rotation speed when auto idle control is released is determined based on the remaining amount of electricity stored in the power storage device 2. According to the embodiment, the speed at which the rotation speed of the electric motor 4 is restored from a predetermined idle rotation speed to a target rotation speed can be controlled based on the remaining amount of electricity stored in the power storage device 2. According to the embodiment, when the remaining amount of electricity stored in the power storage device 2 decreases, it is possible to further reduce power consumption.

[0094] In the embodiment, when it is determined that the remaining amount of stored power of the power storage device 2 is greater than a predetermined threshold, a first return speed is selected, and when it is determined that the remaining amount of stored power is equal to or less than the predetermined threshold, a second return speed slower than the first return speed is selected. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the return of the rotation speed of the electric motor 4 can be slowed down. According to the embodiment, when the remaining amount of stored power of the power storage device 2 decreases, the return of the rotation speed of the electric motor 4 can be slowed down, thereby urging the operator to charge the battery.

[0095] In the second embodiment described above, the controller 9 controls the deceleration speed, the determination time, the idle rotation speed, and the return speed based on the remaining amount of electricity stored in the power storage device 2. However, it is not necessary to control all of these. The controller 9 only needs to control at least one of these based on the remaining amount of electricity stored in the power storage device 2.

[0096] [Variation 1] Fig. 9 is a diagram schematically illustrating a modified example of the configuration related to the control of the work machine. The example shown in Fig. 9 differs from the first embodiment in that a pilot control valve 19 is provided and the operating device 5 is an electric operating device. The controller 9 has the same functions as in the first embodiment.

[0097] The pilot control valve 19 controls the hydraulic control valve 15 .

[0098] The work implement control lever 51 is an electric control lever, and outputs an operation command indicating the amount of operation of the work implement control lever 51 to the controller 9.

[0099] The traveling operation pedal 52 is an electric operation pedal, and outputs an operation command indicating the operation amount of the traveling operation pedal 52 to the controller 9.

[0100] [Variation 2] Fig. 10 is a diagram showing a schematic diagram of a modified example of the configuration related to the control of the work machine. The example shown in Fig. 10 differs from the first embodiment in that the travel motor 17 is an electric motor and the travel operation pedal 52 is an electric operation pedal.

[0101] The traction motor 17 is driven by the electric power from the power storage device 2.

[0102] The traveling operation pedal 52 is an electric operation pedal, and outputs an operation command indicating the operation amount of the traveling operation pedal 52 to the controller 9.

[0103] The controller 9 may control the traveling motor 17 in response to an operation command from the traveling operation pedal 52, regardless of the detected remaining amount of stored electricity in the electricity storage device 2. [Explanation of symbols]

[0104] 1...system, 2...power storage device, 3...inverter, 4...electric motor (electric motor), 5...operation device, 7...rotation speed setting device, 9...controller, 11...swash plate drive device, 12...main hydraulic pump, 13...pilot hydraulic pump, 15...hydraulic control valve, 16...swing motor (hydraulic actuator), 17...travel motor (hydraulic actuator), 18...cylinder (hydraulic actuator), 51...work implement operation lever, 52...travel operation pedal, 91...memory, 100...work machine, 102...traveling body, 103...swinging body, 105...work implement, 105A...boom, 105B...arm, 105C...bucket, 106...operator's seat, 109...display device, 110...support arm, 111...support column, 112...operator's cab, 126...work implement cylinder, 126A...boom cylinder, 126B...arm cylinder, 126C...bucket cylinder.

Claims

1. A system for controlling a work machine that includes an electric motor driven by electric power from a power storage device and a hydraulic pump driven by the electric motor and is driven by hydraulic oil supplied from the hydraulic pump, Equipped with a controller, The controller Detecting the remaining charge of the power storage device; controlling the idle rotation speed when performing auto idle control based on the remaining amount of stored electricity; system.

2. The controller controlling whether to select a first idle rotation speed or a second idle rotation speed lower than the first idle rotation speed as the idle rotation speed when performing auto idle control based on the remaining amount of stored electricity and a predetermined threshold value of the remaining amount of stored electricity; The system of claim 1 .

3. The controller When it is determined that the remaining amount of stored electricity is greater than a predetermined threshold, the first idle rotation speed is selected, and when it is determined that the remaining amount of stored electricity is equal to or less than the predetermined threshold, the second idle rotation speed which is lower than the first idle rotation speed is selected. The system of claim 2 .

4. 1. A method for controlling a work machine powered by electric power from a power storage device, comprising: Detecting a remaining amount of electricity stored in the electricity storage device; controlling an idle rotation speed when performing auto idle control based on the remaining amount of stored electricity; A method comprising:

5. controlling whether to select a first idle rotation speed or a second idle rotation speed lower than the first idle rotation speed as an idle rotation speed when performing auto idle control based on the remaining amount of stored electricity and a predetermined threshold value of the remaining amount of stored electricity; The method of claim 4, comprising:

6. selecting the first idle rotation speed when it is determined that the remaining amount of stored electricity is greater than a predetermined threshold, and selecting the second idle rotation speed that is lower than the first idle rotation speed when it is determined that the remaining amount of stored electricity is equal to or less than the predetermined threshold; The method of claim 5 , comprising:

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