Electrically-driven type dump truck

Abstract

To provide an electrically-driven type dump truck which is capable of restraining an on-vehicle battery cell from deteriorating even if the vehicle is stopped without receiving supply of electrical power from an external source.SOLUTION: An electrically-driven type dump truck 100 includes a lifting device 102 that raises and lowers a body 101, and a traveling motor 103 that rotates a tire 111. The dump truck 100 further includes a power receiving device 104, a power storage device 106, a temperature control device 108, and a battery status control device 109. The battery status control device 109 switches between a normal mode, in which the temperature control device 108 is driven to adjust the temperature of battery cells constituting the power storage device 106 while supplying electric power from the power storage device 106 to the lifting device 102 or the traveling motor 103, and a resting mode, in which the supply of electric power from the power storage device 106 to the lifting device 102 and the traveling motor 103 is stopped regardless of whether the power receiving device 104 receives electric power from the outside, and the temperature of the battery cells is adjusted by driving the temperature control device 108.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electric dump truck. [Background technology]

[0002] Trolley-charging electric dump trucks have been known for some time (see Patent Document 1 below). For example, the transport vehicle described in Patent Document 1 includes a dump body, a vehicle body, a traveling device, a trolley power receiving device, a bidirectional DC / DC converter, a power storage device, an electric motor, and a switch mechanism.

[0003] This switch mechanism switches between a first state in which power is supplied to the electric motor from the trolley wire via a bidirectional DC / DC converter, and a second state in which power is supplied to the electric motor from a storage battery via a bidirectional DC / DC converter.By using such an engine-free trolley-charging electric dump truck, carbon dioxide emissions at work sites can be reduced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-98207 A Summary of the Invention [Problem to be solved by the invention]

[0005] A work machine including the electric dump truck as described above is exposed to harsh environments such as high temperatures, low temperatures, and scorching sun at a work site such as a mining site. In such an environment, if the electric dump truck is left idle without being connected to an external power source, the temperature of the battery cells constituting the storage battery will be affected by the external environment and will fall outside the appropriate temperature range. If this condition continues for a long period of time, deterioration may progress rapidly.

[0006] The present disclosure provides an electric dump truck that is capable of suppressing deterioration of mounted battery cells even when the truck is stopped without receiving an external power supply. [Means for solving the problem]

[0007] One aspect of the present disclosure provides an electric dump truck including a lifting device that raises and lowers a body on which a load is carried, and a traveling motor that rotates tires, the electric dump truck including: a power receiving device that receives a supply of electric power from an external source; a power storage device that is charged with the power supplied from the power receiving device and supplies power to the lifting device and the traveling motor; a temperature adjustment device that is driven by the power supplied from the power receiving device or the power storage device to adjust the temperature of battery cells that constitute the power storage device; and a battery state control device that controls the power storage device and the temperature adjustment device to control the state of charge and temperature of the battery cells, the battery state control device switching between a normal mode in which power is supplied from the power storage device to the lifting device or the traveling motor while driving the temperature adjustment device to adjust the temperature of the battery cells; and a pause mode in which power supply from the power storage device to the lifting device and the traveling motor is stopped regardless of whether the power receiving device is receiving a supply of electric power from an external source, and the temperature adjustment device is driven to adjust the temperature of the battery cells. Effect of the Invention

[0008] According to the above aspect of the present disclosure, it is possible to provide an electric dump truck that is capable of suppressing deterioration of the mounted battery cells even when the electric dump truck is stopped without receiving an external power supply. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic perspective view showing an embodiment of an electric dump truck according to the present disclosure. FIG. [Diagram 2] FIG. 2 is a schematic configuration diagram of the electric dump truck shown in FIG. 1. [Diagram 3] FIG. 3 is a schematic configuration diagram showing an example of the temperature adjustment device shown in FIG. 2. [Figure 4] FIG. 3 is a flow diagram showing an example of battery state control performed by the electric dump truck of FIG. 2. [Diagram 5] FIG. 5 is a flow diagram showing an example of SOC control included in the normal mode control of FIG. 4 . [Figure 6] 5 is a flow diagram showing an example of battery temperature control included in the normal mode control of FIG. 4. [Figure 7] 5 is a flow diagram showing an example of SOC control included in the sleep mode control of FIG. 4; [Figure 8] 5 is a flow diagram showing an example of battery temperature control included in the hibernation mode control of FIG. 4; [Figure 9] 5 is a flow diagram showing another example of the SOC control included in the sleep mode control of FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of an electric dump truck according to the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic perspective view showing an embodiment of an electric dump truck according to the present disclosure. Fig. 2 is a schematic configuration diagram of the electric dump truck 100 shown in Fig. 1.

[0011] The electric dump truck 100 of this embodiment includes, for example, a body 101 on which a load is loaded, a lifting device 102 that raises and lowers the front end of the body 101 to raise and lower the body 101, and a traveling motor 103. The electric dump truck 100 also includes, for example, a power receiving device 104, a distribution device 105, a power storage device 106, a charge control device 107, a temperature adjustment device 108, and a battery state control device 109. The electric dump truck 100 also includes, for example, an auxiliary device 112.

[0012] A rear portion of the body 101 is attached, for example, via a rotating shaft to a vehicle body frame 110 of the electric dump truck 100. A front portion of the body 101 is attached, for example, via a rotating shaft to a pair of hoist cylinders constituting a lifting device 102. The lifting device 102 includes, for example, a pair of hoist cylinders and an electric hydraulic pump connected to an electricity storage device 106, and lifts and lowers the front end portion of the body 101 by extending and retracting the pair of hoist cylinders by driving the electric hydraulic pump.

[0013] The traveling motor 103, for example, rotates tires 111 attached to a vehicle body frame 110 of the electric dump truck 100 via a suspension cylinder, thereby causing the electric dump truck 100 to travel. The electric dump truck 100 may include a plurality of traveling motors 103 that drive the front and rear tires 111, respectively. The traveling motor 103 is, for example, connected to a power storage device 106, and is driven by power supplied from the power storage device 106. The traveling motor 103 is, for example, connected to a distribution device 105, and is driven by power supplied from the trolley wire 2 via a power receiving device 104 and the distribution device 105.

[0014] The power receiving device 104 receives power from an external source and supplies the power to the distribution device 105. The power receiving device 104 includes a power inlet 104A that receives power from the external power source 3 when the power receiving device 104 is connected to the external power source 3. The external power source 3 includes, for example, a stationary charging facility such as a charging stand or a charging station, or a mobile charging facility such as a mobile charging vehicle. The power inlet 104A can receive power from the external power source 3 when, for example, a connector of the external power source 3 is connected to the power inlet 104A.

[0015] Moreover, the power receiving device 104 includes, for example, a pantograph 104B that receives power from the trolley overhead line 2 when connected to the trolley overhead line 2. Note that the power receiving device 104 does not necessarily need to include both the power feed port 104A and the pantograph 104B, and may include either the power feed port 104A or the pantograph 104B.

[0016] Pantograph 104B includes, for example, a link mechanism that can expand and contract up and down, a drive motor that expands and contracts the link mechanism by receiving power from power storage device 106, and a current collector that contacts and slides with trolley overhead line 2 when the link mechanism is extended, thereby being electrically connected. Pantograph 104B can receive power from trolley overhead line 2, for example, when the link mechanism is extended and the current collector is in contact with trolley overhead line 2.

[0017] For example, distribution device 105 distributes power supplied from power receiving device 104 to traction motor 103 and temperature adjustment device 108, and also distributes the power to power storage device 106 via charging control device 107. More specifically, distribution device 105 distributes power supplied from power feed port 104A to power storage device 106 and temperature adjustment device 108, and distributes power supplied from pantograph 104B to power storage device 106, temperature adjustment device 108, and traction motor 103.

[0018] The power storage device 106 is charged by power supplied from the power receiving device 104. Specifically, the power storage device 106 is charged by power supplied from the distribution device 105 via the charge control device 107. The power storage device 106 includes, for example, a plurality of battery cells, a temperature sensor that detects the temperature of at least one of the battery cells, a current sensor that detects the current flowing through the plurality of battery cells, and a voltage sensor that detects the voltage of each battery cell. The battery cells that constitute the power storage device 106 are, for example, lithium ion secondary batteries. The battery cells that constitute the power storage device 106 may be, for example, nickel-metal hydride batteries. The power storage device 106 also supplies power to the lifting device 102, the traveling motor 103, and the auxiliary device 112.

[0019] The charging control device 107 is configured, for example, by a microcontroller, a DC / DC converter, and a switch box, and controls the power supplied from the distribution device 105 to the power storage device 106. The temperature adjustment device 108 is driven, for example, by power supplied from the power receiving device 104 (distribution device 105) or the power storage device 106, and adjusts the temperature of the battery cells constituting the power storage device 106.

[0020] 3 is a schematic diagram showing an example of the temperature adjustment device 108 of FIG. 2. As shown in FIG. 3, the temperature adjustment device 108 includes, for example, a heat medium tank 108a, a heater 108b, a first pump 108c, a second pump 108d, and a heat medium cooling unit 108e. The heat medium tank 108a stores a heat medium liquid such as water or a coolant. The heater 108b is turned on, for example, when raising the temperature of the battery cells constituting the power storage device 106, and heats the heat medium liquid stored in the heat medium tank 108a to raise the temperature.

[0021] The first pump 108c is provided, for example, in a heat medium flow path that circulates the heat medium between the heat medium tank 108a and the power storage device 106, and circulates the heat medium liquid. The second pump 108d is provided, for example, in a heat medium flow path that circulates the heat medium liquid between the heat medium tank 108a and the heat medium cooling unit 108e, and circulates the heat medium liquid. The heat medium cooling unit 108e has a heat medium gas circulation system that includes, for example, an evaporator, a compressor, a condenser, and a liquid tank. The heat medium cooling unit 108e cools the heat medium liquid by, for example, exchanging heat between the heat medium liquid that has been heated by cooling the battery cells of the power storage device 106 and the heat medium gas liquefied by the condenser in an evaporator to vaporize the heat medium gas.

[0022] 2 controls the power storage device 106 and the temperature adjustment device 108 to control the state of charge and the temperature of the power storage device 106. Also, the battery state control device 109 controls, for example, the charge control device 107 and the power storage device 106 to supply power from the power storage device 106 to the temperature adjustment device 108. The battery state control device 109 is configured, for example, by one or more microcontrollers.

[0023] The battery state control device 109 acquires detection results of voltage, current, and temperature, for example, from a voltage sensor, a current sensor, and a temperature sensor, respectively, of the power storage device 106. That is, the battery state control device 109 includes, for example, a central processing unit (CPU), memories such as ROM and RAM, programs stored in these memories, and an input / output unit, and realizes various functions described below by executing the programs with the CPU.

[0024] The battery state control device 109 calculates the state of charge (SOC) of each battery cell constituting the power storage device 106 based on, for example, the detection results of the voltage, current, and temperature, and outputs a control signal to the charge control device 107 and the temperature adjustment device 108. The auxiliary devices 112 include, for example, a wireless communication device, a pump, a blower, and other electronic devices.

[0025] Fig. 4 is a flow diagram showing an example of battery state control by the electric dump truck 100 of Fig. 2. The electric dump truck 100 executes the battery state control shown in Fig. 4 to control the state of charge and temperature of the battery cells constituting the power storage device 106 in accordance with the control mode of the electric dump truck 100. When the electric dump truck 100 starts the processing flow of the battery state control shown in Fig. 4, it first executes a process P1 for acquiring the control mode.

[0026] In this process P1, the battery state control device 109 acquires, for example, a control mode input to an input device by an operator of the electric dump truck 100. The input device is not shown, but includes, for example, a touch panel, a keyboard, a switch, or a microphone mounted in the cabin of the electric dump truck 100, or an input device of a mobile information terminal connected to a communication device of the electric dump truck 100 via a wireless communication line. In addition, the control mode of the electric dump truck 100 input by the operator to the input device includes, for example, a normal mode and a pause mode.

[0027] The normal mode is a mode in which the temperature of the battery cells is adjusted by driving the temperature adjustment device 108 while power is supplied from the power receiving device 104 (distribution device 105) to the lifting device 102 or the traveling motor 103. The pause mode is a mode in which the power supply from the power storage device 106 to the lifting device 102 and the traveling motor 103 is stopped regardless of whether the power receiving device 104 is receiving power from an external source, and the temperature adjustment device 108 is driven to adjust the temperature of the battery cells.

[0028] The normal mode is, for example, selected when the electric dump truck 100 is in operation, and is a mode in which the battery cells constituting the power storage device 106 are charged to a charge state of 100% or close to 100% at a charge rate higher than in the pause mode. The pause mode is, for example, selected when the electric dump truck 100 is at rest or not in operation, including when the electric dump truck 100 breaks down or is in storage. The pause mode is, for example, a mode in which the charge state and temperature of the battery cells constituting the power storage device 106 are maintained within a range in which deterioration of the battery cells can be suppressed. Although details will be described later, the upper limit value of the charge state of the battery cells and the charge rate in the pause mode are set lower than the upper limit value of the charge state of the battery cells and the charge rate in the normal mode.

[0029] For example, when the process P1 for acquiring the control mode is completed, the electric dump truck 100 executes a process P2 for determining the control mode. In this process P2, the battery state control device 109 determines whether or not the control mode acquired in the previous process P1 is the pause mode. When the battery state control device 109 determines that the acquired control mode is the "normal mode" and not the "pause mode" (NO), it executes a normal mode control P3. Furthermore, when the battery state control device 109 determines that the acquired control mode is the "pause mode" (YES), it executes a pause mode control P4.

[0030] Fig. 5 is a flow diagram showing an example of the SOC control P31 included in the normal mode control P3 in Fig. 4. When the control mode input to the input device by the operator of the electric dump truck 100 is the "normal mode", the battery state control device 109 starts the process flow of the SOC control P31 shown in Fig. 5 and executes a process P311 for setting an upper limit of the SOC. In this process P311, the battery state control device 109 sets the upper limit of the SOC of each battery cell in the normal mode to an upper limit value SOC_max2 that is 100% or close to 100%, for example.

[0031] Next, the battery state control device 109 executes a process P312 for acquiring the SOC of each battery cell. In this process P312, the battery state control device 109 acquires the SOC of each battery cell by calculating the SOC of each battery cell based on the detection results of the voltage, current, temperature, etc. acquired from the power storage device 106. If the power storage device 106 has a function for calculating the SOC of each battery cell, the battery state control device 109 may acquire the SOC of each battery cell from the power storage device 106.

[0032] For example, in a normal mode and in a state where the electric dump truck 100 is not receiving power supply from an external source, the electric dump truck 100 can travel by driving the traveling motor 103 with power supplied from the power storage device 106. Also, in this state, the electric dump truck 100 can drive the lifting device 102 with power supplied from the power storage device 106, for example, to lift and lower the front end portion of the body 101. Similarly, the auxiliary machine 112 is driven by receiving power supply from the power storage device 106, for example.

[0033] In this way, in the normal mode and in a state where the electric dump truck 100 is not receiving power from an external source, the electric storage device 106 supplies power to the lifting device 102 or the traveling motor 103. Therefore, in this state, the SOC of each battery cell of the electric storage device 106 gradually decreases and falls below the upper limit value SOC_max2.

[0034] Thereafter, when the power receiving device 104 of the electric dump truck 100 is connected to the trolley overhead line 2 or the external power source 3 in the normal mode, the battery cells constituting the power storage device 106 can be charged by the power supplied from the trolley overhead line 2 or the external power source 3. In addition, when the pantograph 104B is connected to the trolley overhead line 2 in the normal mode, the electric dump truck 100 can drive the traveling motor 103 by the power supplied from the trolley overhead line 2 to travel.

[0035] For example, after the process P312 of acquiring the SOC of each battery cell, the battery state control device 109 executes a process P313 of determining whether the acquired SOC is smaller than the upper limit value SOC_max2. If the battery state control device 109 determines in the process P313 that the SOC of each battery cell is smaller than the upper limit value SOC_max2 (YES), it outputs, for example, a control signal to the charging control device 107 to charge the power storage device 106.

[0036] As a result, the charging control device 107 supplies the power supplied from the trolley wire 2 and distributed by the distribution device 105 to the power storage device 106 in accordance with the control signal, thereby charging each battery cell (process P314). After that, the battery state control device 109 again executes process P312 to obtain the SOC of each battery cell.

[0037] Thereafter, as each battery cell of the power storage device 106 is charged, the SOC increases to a value equal to or greater than the upper limit value SOC_max2. As a result, in the above-mentioned process P313, the battery state control device 109 determines that the SOC of each battery cell is equal to or greater than the upper limit value SOC_max2, i.e., is not smaller than the upper limit value SOC_max2 (NO), and outputs a control signal to the charging control device 107 to terminate charging.

[0038] The charge control device 107 terminates the charging of the power storage device 106 in accordance with the control signal for charging termination input from the battery state control device 109 (process P315). After that, the electric dump truck 100 terminates the process flow of the SOC control P31 shown in Fig. 5. In addition, in the normal mode control P3 shown in Fig. 4, the electric dump truck 100 executes the process flow of the battery temperature control P32 shown in Fig. 6 in parallel with the process flow of the SOC control P31 shown in Fig. 5.

[0039] Fig. 6 is a flow diagram showing an example of the battery temperature control P32 included in the normal mode control P3 of Fig. 4. When the electric dump truck 100 starts the battery temperature control P32 shown in Fig. 6, first, it executes a process P321 for setting an upper limit temperature of the battery cells constituting the power storage device 106. In this process P321, the battery state control device 109 sets, for example, the upper limit temperature T_max2 of the battery cells in the normal mode to a temperature higher than the upper limit temperature T_max1 of the battery cells in the sleep mode. More specifically, the upper limit temperature T_max2 of the battery cells in the normal mode is set to a temperature of, for example, about 40°C to 60°C.

[0040] Next, the battery state control device 109 executes, for example, a process P322 for acquiring the temperature of each battery cell. In this process P322, the battery state control device 109 acquires, for example, a detection result of the temperature T of one or more battery cells from a temperature sensor of the power storage device 106. Thereafter, the battery state control device 109 executes a process P323 for determining whether or not the battery cell temperature T acquired in the previous process P322 exceeds an upper limit temperature T_max2.

[0041] In this process P323, when the battery state control device 109 determines that the temperature T of the battery cells exceeds the upper limit temperature T_max2 (YES), it outputs a control signal to the temperature adjustment device 108 to cool the battery cells. As a result, the temperature adjustment device 108 executes process P324 to circulate a heat transfer fluid that is lower in temperature than the temperature T of the battery cells through the heat transfer flow path to cool the multiple battery cells that constitute the power storage device 106. Thereafter, the battery state control device 109 and the temperature adjustment device 108 repeat processes P322 to P324 until the temperature T of the battery cells that constitute the power storage device 106 becomes equal to or lower than the upper limit temperature T_max2.

[0042] When the temperature T of the battery cells constituting the power storage device 106 becomes equal to or lower than the upper limit temperature T_max2, the battery state control device 109 determines in process P323 that the temperature T of the battery cells does not exceed the upper limit temperature T_max2 (NO). In this case, the electric dump truck 100 ends the process flow of the battery temperature control P32 shown in Fig. 6. When the normal mode control P3 including the SOC control P31 and the battery temperature control P32 ends, for example, the electric dump truck 100 ends the process flow of the battery state control shown in Fig. 4, and repeats it at a predetermined cycle.

[0043] The operator of the electric dump truck 100 inputs "pause mode" to the above-mentioned input device when the electric dump truck 100 is paused or not in operation, for example, when the electric dump truck 100 breaks down, undergoes maintenance, or is parked. As a result, as shown in Fig. 4, the battery state control device 109 acquires "pause mode" as the control mode in process P1, determines that the control mode is "pause mode" (YES) in process P2, and executes pause mode control P4.

[0044] Fig. 7 is a flow diagram showing an example of the SOC control P41 included in the pause mode control P4 in Fig. 4. Note that, in the SOC control P41 shown in Fig. 7, it is assumed that the electric dump truck 100 is, for example, in a pause mode and receives power supply from the external power source 3 via the power receiving device 104. In this state, the electric dump truck 100 can charge the battery cells constituting the power storage device 106 with the power supplied from the external power source 3 via the power receiving device 104 and the distribution device 105, and can also drive the temperature adjustment device 108 to adjust the temperature of the battery cells.

[0045] Furthermore, for example, in the pause mode, the electric dump truck 100 preferentially supplies power from the power storage device 106 to the temperature adjustment device 108. More specifically, the distribution device 105 stops the supply of power from the power storage device 106 to, for example, the lifting device 102, the drive motor of the pantograph 104B, the traveling motor 103, and the auxiliary devices 112 such as a pump and a blower. The distribution device 105 may stop the supply of power to these devices in accordance with a control signal from the battery state control device 109.

[0046] When the control mode input to the input device by the operator of the electric dump truck 100 is the "rest mode", the battery state control device 109 starts the process flow of SOC control P41 shown in Fig. 7 in the rest mode control P4. The battery state control device 109 first executes a process P411 for setting the range of SOC. In this process P411, the battery state control device 109 sets the upper limit of the SOC of each battery cell in the rest mode to an upper limit value SOC_max1 that is lower than the upper limit value SOC_max2 in the normal mode, for example.

[0047] The upper limit value SOC_max1 of the SOC of each battery cell in the sleep mode is set to, for example, a value of about 70% that can sufficiently suppress the deterioration of each battery cell. Also, in this process P411, the battery state control device 109 sets the lower limit value SOC_min1 of the SOC of each battery cell in the sleep mode to, for example, a value of about 30% that can sufficiently suppress the deterioration of each battery cell.

[0048] Next, the battery state control device 109 executes a process P412 for acquiring the SOC of each battery cell, for example. In this process P412, the battery state control device 109 acquires the SOC of each battery cell, similar to the process P312 in the normal mode described above. After that, the battery state control device 109 executes a process P413 for determining whether the acquired SOC is smaller than the lower limit value SOC_min1.

[0049] In this process P413, when the battery state control device 109 determines that the SOC of each battery cell is lower than the lower limit value SOC_min1 (YES), it outputs, for example, a control signal to the charging control device 107 to charge the power storage device 106. As a result, in accordance with the control signal, the charging control device 107 supplies the power supplied from the external power source 3 and distributed by the distribution device 105 to the power storage device 106 to charge each battery cell (process P414).

[0050] Here, the charge control device 107, for example, reduces the charging rate of the battery cells in the pause mode to be lower than the charging rate of the battery cells in the normal mode, thereby suppressing an increase in power consumption in the pause mode. That is, in the normal mode, the charging rate is prioritized over suppression of power consumption, whereas in the pause mode, the suppression of power consumption can be prioritized over the charging rate. This makes it possible to suppress a rise in temperature of the battery cells in the pause mode. For example, the battery state control device 109 adjusts the charging rate of the battery cells based on the power consumption rate of the temperature adjustment device 108 and the rate of increase in the temperature of the battery cells, so that the power consumption rate of the temperature adjustment device 108 is as low as possible.

[0051] Thereafter, the battery state control device 109 executes process P412 again to acquire the SOC of each battery cell. By charging each battery cell of the power storage device 106 in the previous process P414, the SOC of the battery cell increases to a value equal to or greater than the lower limit value SOC_min1. As a result, in the above-mentioned process P413, the battery state control device 109 determines that the SOC of the battery cell is equal to or greater than the lower limit value SOC_min1, that is, is not smaller than the lower limit value SOC_min1 (NO). Thereafter, the battery state control device 109 executes process P415 to determine whether the acquired SOC is smaller than the upper limit value SOC_max1.

[0052] In this process P415, when the battery state control device 109 determines that the SOC of each battery cell is lower than the upper limit value SOC_max1 (YES), it outputs, for example, a control signal to the charging control device 107 to charge the power storage device 106. As a result, the process P414 for charging each battery cell and the process P412 for acquiring the SOC are repeated until the SOC of each battery cell reaches the upper limit value SOC_max1.

[0053] Thereafter, as each battery cell of the power storage device 106 is charged, the SOC increases to a value equal to or greater than the upper limit value SOC_max1. As a result, in the above-mentioned process P415, the battery state control device 109 determines that the SOC of each battery cell is equal to or greater than the upper limit value SOC_max1, i.e., is not smaller than the upper limit value SOC_max1 (NO), and executes process P416 to supply power from the power storage device 106 to the temperature adjustment device 108.

[0054] As a result, power is supplied from the power storage device 106 to the temperature adjustment device 108, and the temperature of each battery cell constituting the power storage device 106 is maintained within a predetermined temperature range. Also, the SOC of each battery cell decreases, and the SOC of each battery cell falls below the upper limit value SOC_max1. Note that when power is supplied from the power storage device 106 to the temperature adjustment device 108, the distribution device 105 temporarily stops the power supply from the external power source 3 to the temperature adjustment device 108 in accordance with a control signal from the battery state control device 109, for example.

[0055] Thereafter, the electric dump truck 100 ends the process flow of the SOC control P41 shown in Fig. 7. Moreover, in the pause mode control P4 shown in Fig. 4, the electric dump truck 100 executes the process flow of the battery temperature control P42 shown in Fig. 8 in parallel with the process flow of the SOC control P41 shown in Fig. 7.

[0056] Fig. 8 is a flow diagram showing an example of the battery temperature control P42 included in the sleep mode control P4 in Fig. 4. When the electric dump truck 100 starts the battery temperature control P42 shown in Fig. 8, first, it executes a process P421 for setting a temperature range of the battery cells constituting the power storage device 106. In this process P421, the battery state control device 109 sets, for example, the upper limit temperature T_max1 of the battery cells in the sleep mode to a temperature lower than the upper limit temperature T_max2 of the battery cells in the normal mode.

[0057] More specifically, the upper limit temperature T_max1 of the battery cells in the sleep mode is set to a temperature of, for example, 40° C. or lower. In addition, in this process P421, the battery state control device 109 sets, for example, the lower limit temperature T_min1 of the battery cells in the sleep mode to a temperature at which deterioration of the battery cells can be sufficiently suppressed. The lower limit temperature T_min1 of the battery cells in the sleep mode is set to a temperature of, for example, about 5° C.

[0058] Next, the battery state control device 109 executes a process P422 to acquire the temperature of each battery cell, similar to the process P322 in the normal mode, and further executes a process P423 to determine whether the acquired battery cell temperature T is lower than the lower limit temperature T_min1. In this process P423, when the battery state control device 109 determines that the temperature T of at least one battery cell constituting the power storage device 106 is lower than the lower limit temperature T_min1 (YES), it outputs a control signal to the temperature adjustment device 108 to raise the temperature of the battery cell.

[0059] As a result, the temperature adjustment device 108 executes a process P424 to raise the temperature of each battery cell, for example, in accordance with a control signal input from the battery state control device 109. In this process P424, the temperature adjustment device 108 raises the temperature of each battery cell, for example, by circulating a heat transfer fluid having a higher temperature than the temperature of each battery cell through the heat transfer flow path and exchanging heat between the heat transfer fluid flowing through the heat transfer flow path and each battery cell. Thereafter, the battery state control device 109 and the temperature adjustment device 108 repeat the processes P422 to P424 to raise the temperature of each battery cell until the temperature T of each battery cell becomes equal to or higher than the lower limit temperature T_min1.

[0060] When the temperature T of each battery cell becomes equal to or higher than the lower limit temperature T_min1, the battery state control device 109 determines in process P423 that the temperature T of the battery cell is not lower than the lower limit temperature T_min1 (NO). Then, the battery state control device 109 executes process P425 to determine whether the temperature T of the battery cell exceeds the upper limit temperature T_max1. When the battery state control device 109 determines in process P425 that the temperature T of the battery cell exceeds the upper limit temperature T_max1 (YES), it outputs a control signal to the temperature adjustment device 108 to cool the battery cell.

[0061] As a result, similarly to process P324 in the normal mode, the temperature adjustment device 108 executes process P426 to cool the multiple battery cells that constitute the power storage device 106. Thereafter, the battery state control device 109 and the temperature adjustment device 108 repeat process P422, process P425, and process P426 to cool each battery cell until the temperature T of the battery cells that constitute the power storage device 106 becomes equal to or lower than the upper limit temperature T_max1.

[0062] When the temperature T of the battery cells constituting the power storage device 106 becomes equal to or lower than the upper limit temperature T_max1, the battery state control device 109 determines in process P425 that the temperature T of the battery cells does not exceed the upper limit temperature T_max1 (NO). In this case, the electric dump truck 100 ends the process flow of the battery temperature control P42 shown in Fig. 8. When the sleep mode control P4 including the SOC control P41 and the battery temperature control P42 ends, for example, the electric dump truck 100 ends the process flow of the battery state control shown in Fig. 4, and repeats it at a predetermined cycle.

[0063] Fig. 9 is a flow diagram showing another example of the SOC control P41 included in the pause mode control P4 in Fig. 4. In the SOC control P41 shown in Fig. 7, the electric dump truck 100 is assumed to be in, for example, the pause mode and receiving power supply from the external power source 3 via the power receiving device 104. In contrast to this, the SOC control P41' shown in Fig. 9 is executed, for example, in a state in which the control mode of the electric dump truck 100 is the pause mode and receiving no power supply from the outside.

[0064] In this state, the electric dump truck 100 cannot charge each battery cell constituting the power storage device 106, and adjusts the temperature of the battery cells by driving the temperature adjustment device 108 with the power stored in each battery cell. For example, in the pause mode, the electric dump truck 100 supplies power from the power storage device 106 only to the temperature adjustment device 108. That is, in the pause mode, when the power receiving device 104 is not receiving power from the outside, the battery state control device 109 may supply power from the power storage device 106 only to the temperature adjustment device 108 to drive the temperature adjustment device 108.

[0065] When the control mode input to the input device by the operator of the electric dump truck 100 is the "rest mode" and power is not being supplied from the outside, the battery state control device 109 starts the process flow of SOC control P41' shown in Fig. 9 in the rest mode control P4. The battery state control device 109 first executes a process P411' for setting a lower limit of the SOC. In this process P411', the battery state control device 109 sets, for example, the lower limit value SOC_min1 of the SOC of each battery cell in the rest mode to a value of about 30% that can sufficiently suppress deterioration of each battery cell.

[0066] Next, the battery state control device 109 executes a process P412' to acquire the SOC of each battery cell, for example, similar to the above-mentioned process P412. Thereafter, the battery state control device 109 executes a process P413' to notify the battery cell 106 of a possible storage period during which the SOC and temperature of each battery cell constituting the power storage device 106 can be maintained within an appropriate range. More specifically, the battery state control device 109 calculates the possible storage period Ts using, for example, the following formula (1), and notifies the notification recipients, including the operator of the electric dump truck 100, of the calculated possible storage period Ts via a display device or the like.

[0067] Ts=(SOC_p-SOC_min1) / (Esd+Esb+Etc)...(1)

[0068] In the above formula (1), SOC_p is the current SOC of the battery cell acquired in process P412', and SOC_min1 is the lower limit of the SOC of the battery cell set in process P411'. Also, Esd, Esb, and Etc are the estimated natural discharge power amount of the battery cell per day, the estimated standby discharge power amount of the battery cell per day, and the estimated power consumption amount of the temperature adjustment device 108 per day, respectively.

[0069] After that, the battery state control device 109 executes a process P414' to determine whether the acquired SOC is smaller than the lower limit SOC_min1. If the battery state control device 109 determines in the process P414' that the SOC of each battery cell is not smaller than the lower limit SOC_min1 (NO), it outputs, for example, a control signal to the power storage device 106 to supply power to the temperature adjustment device 108.

[0070] The power storage device 106 executes a process P415' of supplying power to the temperature adjustment device 108 in accordance with a control signal input from the battery state control device 109, for example. As a result, the temperature of each battery cell is maintained within an appropriate temperature range, and the SOC of each battery cell constituting the power storage device 106 decreases. Thereafter, the battery state control device 109 repeats a process P416' of acquiring the SOC and a process P414' of determining whether the acquired SOC is lower than the lower limit value SOC_min1. As a result, the power storage device 106 continues the process P415' of supplying power to the temperature adjustment device 108 until the SOC of each battery cell falls below the lower limit value SOC_min1.

[0071] Thereafter, when the SOC of each battery cell falls below the lower limit value SOC_min1, the battery state control device 109 determines in process P414' that the SOC of each battery cell is lower than the lower limit value SOC_min1 (YES). Then, the battery state control device 109 executes process P417' to notify the operator of the electric dump truck 100, for example, via a display device, that the temperature adjustment of the battery cells is not possible, and ends the SOC control P41' shown in FIG.

[0072] Furthermore, when the control mode of the electric dump truck 100 is the rest mode and no power is supplied from the outside, the battery state control device 109 may execute a modified example of the battery temperature control P42 shown in Fig. 8, which will be described below. In this modified example, the battery state control device 109 changes the upper limit temperature T_max1 and the lower limit temperature T_min1 of the battery cell in the battery temperature control P42 according to the SOC of the battery cell to reduce power consumption. The following Table 1 shows an example of the relationship between the SOC of the battery cell and the upper limit temperature T_max1 and the lower limit temperature T_min1.

[0073] [Table 1]

[0074] The operation of the electric dump truck 100 of the above-mentioned embodiment will be described below. As described above, the electric dump truck 100 includes the lifting device 102 that raises and lowers the body 101 on which a load is loaded, and the traveling motor 103 that rotates the tires 111. The electric dump truck 100 also includes a power receiving device 104 that receives power from an external source, and a power storage device 106 that is charged with power supplied from the power receiving device 104 and supplies power to the lifting device 102 and the traveling motor 103. The electric dump truck 100 also includes a temperature adjustment device 108 that is driven by power supplied from the power receiving device 104 or the power storage device 106 and adjusts the temperature of the battery cells that constitute the power storage device 106. The electric dump truck 100 also includes a battery state control device 109 that controls the power storage device 106 and the temperature adjustment device 108 to control the charging state and temperature of the battery cells of the power storage device 106. The battery state control device 109 switches between a normal mode in which power is supplied from the power storage device 106 to the lifting device 102 or the driving motor 103 while driving the temperature adjustment device 108 to adjust the temperature of the battery cells, and a sleep mode in which power supply from the power storage device 106 to the lifting device 102 and the driving motor 103 is stopped regardless of whether the power receiving device 104 is receiving power from an external source, and the temperature adjustment device 108 is driven to adjust the temperature of the battery cells.

[0075] With such a configuration, according to the electric dump truck 100 of the present embodiment, for example, when a breakdown occurs or the electric dump truck 100 is not in operation, the battery state control device 109 can switch the control mode from the normal mode to the pause mode. As a result, even if the electric dump truck 100 is paused without receiving power supply from the outside and exposed to a harsh environment, the temperature adjustment device 108 can be driven preferentially by the power supplied from the power storage device 106. Therefore, it is possible to provide an electric dump truck 100 that can maintain the SOC and temperature of the battery cells constituting the power storage device 106 within an appropriate temperature range and suppress deterioration of the mounted battery cells even when the electric dump truck 100 is paused without receiving power supply from the outside. Also, even when the electric dump truck 100 is receiving power supply from the outside, the control mode can be switched to the pause mode to drive the temperature adjustment device 108 preferentially. As a result, it is possible to maintain the SOC and temperature of the battery cells constituting the power storage device 106 within an appropriate temperature range to suppress deterioration of the battery cells, and to reduce power consumption compared to the normal mode.

[0076] In the electric dump truck 100 of this embodiment, the power receiving device 104 includes a power feed port 104A that receives a supply of electric power when connected to the external power source 3.

[0077] With such a configuration, the electric dump truck 100 of this embodiment can charge the power storage device 106 and drive the temperature adjustment device 108 with power supplied from the external power source 3 via the power feed port 104A in the pause mode. In addition, by controlling the battery state control device 109, the SOC of the battery cells constituting the power storage device 106 can be maintained within an appropriate range, and deterioration of the battery cells can be suppressed.

[0078] In the electric dump truck 100 of this embodiment, the power receiving device 104 includes a pantograph 104B that receives a supply of electric power when connected to the trolley wire 2.

[0079] With such a configuration, the electric dump truck 100 of this embodiment can travel by supplying power supplied from the trolley wire 2 via the pantograph 104B to the traveling motor 103. Also, the power supplied from the trolley wire 2 via the pantograph 104B can be supplied to the power storage device 106 to charge each battery cell constituting the power storage device 106. Furthermore, the power supplied from the trolley wire 2 via the pantograph 104B can be supplied to the temperature adjustment device 108 to maintain the temperature of the battery cells constituting the power storage device 106 within an appropriate range.

[0080] Furthermore, in the electric dump truck 100 of this embodiment, the battery state control device 109 controls the power storage device 106 and the temperature adjustment device 108 so that the upper limit value SOC_max1 and the upper limit temperature T_max1 of the state of charge of the battery cells in the pause mode are lower than the upper limit value SOC_max2 and the upper limit temperature T_max2 of the state of charge of the battery cells in the normal mode.

[0081] With such a configuration, the electric dump truck 100 of this embodiment can more effectively suppress deterioration of the battery cells constituting the power storage device 106 by switching the control mode from the normal mode to the pause mode by the battery state control device 109. Also, by switching the control mode from the normal mode to the pause mode, it is possible to reduce power consumption for SOC control and temperature control of the battery cells constituting the power storage device 106 compared to the normal mode.

[0082] In addition, in the electric dump truck 100 of this embodiment, when the power receiving device 104 is not receiving power supply in the sleep mode, the battery state control device 109 supplies power from the power storage device 106 only to the temperature adjustment device 108 to drive the temperature adjustment device 108.

[0083] With this configuration, the electric dump truck 100 of this embodiment can drive the temperature adjustment device 108 even when the electric dump truck 100 is at rest without receiving power supply from the outside and exposed to a harsh environment. Therefore, the SOC and temperature of the battery cells constituting the power storage device 106 can be maintained within an appropriate temperature range, and deterioration of the mounted battery cells can be suppressed.

[0084] As described above, according to this embodiment, an electric dump truck 100 can be provided that is capable of suppressing deterioration of the mounted battery cells even when the electric dump truck 100 is stopped without receiving power from an external source.

[0085] Although the embodiment of the electric dump truck according to the present disclosure has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope of the present disclosure, they are included in the present disclosure. For example, the present disclosure can be applied to work machines such as electric hydraulic excavators and electric wheel loaders in addition to electric dump trucks. [Explanation of symbols]

[0086] 2 trolley overhead line, 3 external power source, 100 electric dump truck, 101 body, 102 lifting device, 103 running motor, 104 power receiving device, 104A power supply port, 104B pantograph, 105 distribution device, 106 storage device, 107 charging control device, 108 temperature control device, 109 battery state control device, SOC_max1 upper limit, SOC_max2 upper limit, T_max1 upper limit temperature, T_max2 Upper temperature limit.

Claims

1. An electric dump truck including a lifting device that raises and lowers a body on which a load is carried, and a traveling motor that rotates tires, a power receiving device that receives power from an external source, a power storage device that is charged with power supplied from the power receiving device and supplies power to the lifting device and the traveling motor, a temperature adjustment device that is driven by power supplied from the power receiving device or the power storage device to adjust the temperature of battery cells that constitute the power storage device, and a battery state control device that controls the power storage device and the temperature adjustment device to control the state of charge and temperature of the battery cells, the battery state control device switches between a normal mode in which power is supplied from the power storage device to the lifting device or the traveling motor while driving the temperature adjustment device to adjust the temperature of the battery cells, and a pause mode in which power supply from the power storage device to the lifting device and the traveling motor is stopped regardless of whether the power receiving device is receiving power from an external source, and the temperature adjustment device is driven to adjust the temperature of the battery cells.

2. The electric dump truck according to claim 1 , wherein the power receiving device includes a power supply port that receives a supply of power when connected to an external power source.

3. The electric dump truck according to claim 1 , wherein the power receiving device includes a pantograph that receives a supply of electric power when connected to a trolley wire.

4. 2. The electric dump truck according to claim 1, wherein the battery state control device controls the power storage device and the temperature adjustment device so that an upper limit value of a state of charge and an upper limit temperature of the battery cells in the sleep mode are lower than an upper limit value of a state of charge and an upper limit temperature of the battery cells in the normal mode.

5. The electric dump truck according to claim 1, characterized in that, when the power receiving device is not supplied with power in the sleep mode, the battery state control device supplies power from the power storage device only to the temperature adjustment device to drive the temperature adjustment device.

Images