Dump truck

Abstract

To provide a dump truck that can effectively utilize regenerative power and promote the optimization of power management.SOLUTION: A dump truck 1 being an electric dump truck includes a first battery 21, a second battery 26 having characteristics different from those of the first battery 21, a traveling motor 13 that is driven using power supplied from the first battery 21 as a power source and generates regenerative power during braking, and a control device 35 that controls the charging and discharging operations of the first battery 21 and the second battery 26, and the capacity of the first battery 21 is greater than that of the second battery 26 and the charging and discharging rate of the second battery 26 is higher than that of the first battery 21. The control device 35 monitors the operation of the traveling motor 13 and controls the charging operation of the regenerative power to the second battery 26 on the basis of the magnitude of the regenerative power generated by the traveling motor 13 and the charging and discharging rate of the first battery 21.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electric dump truck powered by a battery.

Background Art

[0002] For a stable power supply to a traveling motor, an electric vehicle equipped with a plurality of power sources having different characteristics is known (for example, Patent Document 1).

[0003] Patent Document 1 discloses an electric vehicle that mounts a fuel cell as a main power source and a secondary battery as an auxiliary power source, and drives a desired traveling motor by efficiently using each power source. When the output of the main power source exceeds the requirement on the traveling motor side, the electric vehicle disclosed in Patent Document 1 charges the auxiliary power source with the surplus power.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An electric dump truck is equipped with a large-capacity battery that has a low charge-discharge rate but a large capacity for the purpose of extending the cruising range. In this type of dump truck, in order to effectively utilize electric power, the regenerative power generated during the operation of the electric brake or the like is charged into the battery. However, since the vehicle weight of a dump truck is significantly heavier than that of a passenger car, a larger amount of regenerative power is generated in a short time when the dump truck brakes compared to a passenger car. Therefore, in this type of dump truck, it is difficult to charge all of the regenerative power into a large-capacity battery with a low charge-discharge rate, and most of it is converted into heat and released to the outside. The electric vehicle disclosed in Patent Document 1 does not consider the effective utilization of regenerative power at all, and there is room for improvement in terms of optimizing power management.

[0006] In view of the above circumstances, an object of the present invention is to provide a dump truck capable of effectively utilizing regenerative power and promoting the optimization of power management.

Means for Solving the Problems

[0007] In order to solve the above problems, the dump truck of the present invention is an electric dump truck, comprising a first battery, a second battery having characteristics different from those of the first battery, a traveling motor that is driven by electric power supplied from the first battery as a power source and generates regenerative power during braking, and a control device that controls the charge-discharge operations of the first battery and the second battery. The capacity of the first battery is larger than that of the second battery, the charge-discharge rate of the second battery is higher than that of the first battery, and the control device monitors the operation of the traveling motor and controls the charging operation of the regenerative power to the second battery based on the magnitude of the regenerative power generated by the traveling motor and the charge-discharge rate of the first battery.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a dump truck that can effectively utilize regenerative power and promote the optimization of power management.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For the configurations denoted by the same reference numerals in the respective embodiments, unless otherwise specified, they have the same functions in the respective embodiments, and the description thereof will be omitted.

[0011] [First Embodiment] FIG. 1 is a side view showing a schematic configuration of a dump truck 1 according to the first embodiment.

[0012] The dump truck 1 is an electric dump truck having a battery (a rechargeable power storage device) as a power source for traveling. The dump truck 1 is, for example, a dump truck that transports earth and sand, minerals, etc. excavated in an open-pit mine. As shown in FIG. 1, the dump truck 1 is composed of a front wheel 11, a rear wheel 12, and a body 14 which is a sturdy frame connected to the front wheel 11 and the rear wheel 12. On the body 14, a loading platform 15 for loading earth and sand, etc. is mounted. The body 14 is provided with a hoist cylinder 16 for tilting the loading platform 15 with respect to the body 14 during unloading. The rear wheel 12 is a drive wheel, and a traveling motor 13 is provided on the rotating shaft portion of the rear wheel 12.

[0013] FIG. 2 is a schematic circuit diagram of the dump truck 1 according to the first embodiment. FIG. 3 is a graph showing the electrical characteristics of the first battery 21 and the second battery 26 according to the first embodiment. In FIG. 3, the characteristics of the first battery 21 are shown by a solid line, and the characteristics of the second battery 26 are shown by a dotted line.

[0014] As shown in FIG. 2, the dump truck 1 includes a first battery 21, a traveling motor 13, a second battery 26, a first power supply path (first connection line) 22, a second power supply path (second connection line) 27, and a third power supply path (third connection line) 29. Further, the dump truck 1 includes a DC / DC converter 23, an inverter for traveling motor 24, a second switch 25, a chopper 28, a first switch 30, a third switch 31, a fourth power supply path (fourth connection line) 32, and a control device 35. Further, the dump truck 1 includes an auxiliary machine drive motor 17, an auxiliary machine power supply path (fifth connection line) 33, and an inverter for auxiliary machine 34.

[0015] The first battery 21 is a battery that serves as a power source for the traveling motor 13. The first battery 21 is connected to the traveling motor 13 via the first power supply path 22. The first battery 21 supplies power to the traveling motor 13 via the first power supply path 22. The first power supply path 22 is a connection line that electrically connects between the first battery 21 and the traveling motor 13 and serves as a path for transmitting the power output from the first battery 21 to the traveling motor 13.

[0016] The first battery 21 is a large-capacity type battery that can supply power to the traveling motor 13 for a long time. The capacity of the first battery 21 (the product of power W1 and time h1), shown by the solid line in FIG. 3, is larger than the capacity of the second battery 26 (the product of power W2 and time h2), shown by the dotted line in FIG. 3. The first battery 21 according to the present embodiment may be a battery with a charge-discharge rate of less than 4C.

[0017] The traveling motor 13 is an electric motor that is driven by the power supplied from the first battery 21 (generates a rotational force that is the traveling force of the dump truck 1). The traveling motor 13 is connected to the first battery 21 via the first power supply path 22. The traveling motor 13 according to the present embodiment is an AC motor and is connected to an inverter 24 for traveling motor provided on the path of the first power supply path 22. The traveling motor 13 according to the present embodiment is driven by the power supplied from the first battery 21 via the first power supply path 22 and the inverter 24 for traveling motor.

[0018] Further, the traveling motor 13 acts as a generator when the dump truck 1 decelerates (when braking by using the electric brake), and generates regenerative power (performs a regenerative operation) by converting rotational energy into electric energy. The traveling motor 13 is connected to the second battery 26 via the second power supply path 27. The traveling motor 13 supplies (charges) the generated regenerative power to the second battery 26 via the second power supply path 27. The second power supply path 27 is a connection line that electrically connects between the traveling motor 13 and the second battery 26 and serves as a path for transmitting the regenerative power generated by the traveling motor 13 to the second battery 26. Note that the traveling motor 13 becomes a rotational resistance as the regenerative power is generated. Thereby, the dump truck 1 obtains a braking force.

[0019] The second battery 26 is a battery to which the regenerative power generated by the traveling motor 13 is supplied (charged). The second battery 26 is charged by the regenerative power generated by the traveling motor 13. Further, the second battery 26 is connected to the traveling motor 13 via the second power supply path 27. The second battery 26 according to the present embodiment is connected to the inverter 24 for traveling motor connected to the traveling motor 13 via the second power supply path 27.

[0020] The second battery 26 has characteristics different from those of the first battery 21. Specifically, as shown by the dotted line in FIG. 3, the second battery 26 is a high-output type battery with a large amount of charge and dischargeable power per unit time, that is, a high charge and discharge rate. The charge and discharge rate of the second battery 26 is higher than the charge and discharge rate of the first battery 21. Thereby, the second battery 26 can recover the high-output regenerative power that could not be recovered and was discharged in the conventional dump truck. The second battery 26 according to the present embodiment may be a battery with a charge and discharge rate of 4C or more.

[0021] Moreover, the second battery 26 according to this embodiment is connected to the first battery 21 via a third power supply path 29. The second battery 26 according to this embodiment can supply the charged power to the first battery 21 via the third power supply path 29. This allows the first battery 21 to charge the power supplied from the second battery 26. The third power supply path 29 is a connection line that electrically connects the second battery 26 and the first battery 21 and serves as a path for transmitting the power output from the second battery 26 to the first battery 21.

[0022] The DC / DC converter 23 is provided on the first power supply path 22 between the first battery 21 and the travel motor inverter 24. Based on a control command from the control device 35, the DC / DC converter 23 steps up or steps down the DC power supplied from the first battery 21 to a predetermined voltage and supplies the DC power to the travel motor inverter 24. The DC / DC converter 23 is also connected to a third power supply path 29. Based on a control command from the control device 35, the DC / DC converter 23 steps up or steps down the DC power supplied from the second battery 26 to a predetermined voltage and supplies the DC power to the first battery 21.

[0023] The travel motor inverter 24 is provided between the DC / DC converter 23 and the travel motor 13 on the first power supply path 22. Based on a control command from the control device 35, the travel motor inverter 24 converts the DC power supplied from the DC / DC converter 23 into AC power and supplies it to the travel motor 13. The travel motor inverter 24 is also connected to the second battery 26 via a second power supply path 27. Based on a control command from the control device 35, the travel motor inverter 24 converts the regenerative power generated by the travel motor 13 into DC power and supplies it to the second battery 26.

[0024] The chopper 28 is provided between the traveling motor 13 and the second battery 26 on the path of the second power supply path 27. When the regenerative power generated by the traveling motor 13 exceeds a preset threshold value, the chopper 28 supplies the regenerative power to the second battery 26 based on a control command from the control device 35. The magnitude of this threshold value is equal to or less than the magnitude of the power that the first battery 21 can be charged with. In the present embodiment, the magnitude of the threshold value is set to be the same as the magnitude of the power that the first battery 21 can be charged with.

[0025] The second switch 25 is provided on the path of the first power supply path 22 and switches between conduction and interruption of the first power supply path 22. The second switch 25 is a switch that permits or stops the power supply from the first battery 21 to the traveling motor 13. Specifically, the second switch 25 is provided between the DC / DC converter 23 and the inverter 24 for the traveling motor on the path of the first power supply path 22. The second switch 25 performs a closing operation or an opening operation to permit or stop the power supply from the first battery 21 to the traveling motor 13 based on a control signal from the control device 35.

[0026] The first switch 30 is provided on the path of the third power supply path 29 and switches between conduction and interruption of the third power supply path 29. The first switch 30 is a switch that permits or stops the power supply from the second battery 26 to the first battery 21. Specifically, the first switch 30 is provided between the second battery 26 and the DC / DC converter 23 on the path of the third power supply path 29. The first switch 30 performs a closing operation or an opening operation to permit or stop the power supply from the second battery 26 to the first battery 21 based on a control signal from the control device 35.

[0027] The third switch 31 is provided on the path of the second power supply path 27 and switches the conduction path of the second power supply path 27. The third switch 31 is a switch that switches the supply destination of the regenerative power generated by the traveling motor 13 to the first battery 21 or the second battery 26. Specifically, the third switch 31 is provided between the inverter 24 for the traveling motor and the chopper 28 on the path of the second power supply path 27. Also, the third switch 31 is connected to the DC / DC converter 23 via the fourth power supply path 32. The fourth power supply path 32 is electrically connected to the second power supply path 27 via the third switch 31, and is a connection line that becomes a path for transmitting the regenerative power generated by the traveling motor 13 to the first battery 21 via the DC / DC converter 23. In other words, the fourth power supply path 32 is a connection line that becomes a path for electrically connecting between the traveling motor 13 and the first battery 21. Based on the control signal from the control device 35, the third switch 31 switches the connection destination of the third switch 31 connected to the inverter 24 for the traveling motor to the fourth power supply path 32 connected to the DC / DC converter 23 or the second power supply path 27 connected to the chopper 28. Thereby, the third switch 31 can switch the supply destination of the regenerative power generated by the traveling motor 13 to the first battery 21 or the second battery 26.

[0028] The auxiliary machine drive motor 17 is an electric motor that drives auxiliary machines included in the dump truck 1, such as the above-described hoist cylinder 16, a brake device, a cooling blower device, and a steering device. The auxiliary machine drive motor 17 is connected to the first battery 21 via an auxiliary machine power supply path 33. The auxiliary machine power supply path 33 is a connection line that electrically connects between the first battery 21 and the auxiliary machine drive motor 17 and serves as a path for transmitting the power output from the first battery 21 to the auxiliary machine drive motor 17. The auxiliary machine drive motor 17 is driven using the power supplied from the first battery 21 via the auxiliary machine power supply path 33. The auxiliary machine drive motor 17 according to the present embodiment is an AC motor and is connected to an auxiliary machine inverter 34 provided on the path of the auxiliary machine power supply path 33. In the example shown in FIG. 2, the dump truck 1 includes one auxiliary machine drive motor 17, but the dump truck 1 may include a plurality of auxiliary machine drive motors 17.

[0029] The auxiliary machine inverter 34 is provided between the DC / DC converter 23 connected to the first battery 21 and the auxiliary machine drive motor 17 on the path of the auxiliary machine power supply path 33. The auxiliary machine inverter 34 converts the DC power supplied from the DC / DC converter 23 into AC power based on a control command from the control device 35 and supplies it to the auxiliary machine drive motor 17.

[0030] The control device 35 is configured to include a processor such as a CPU, a memory, and an input / output interface. Information is input to the control device 35 from each component connected by a signal line, such as the inverter 24 for the traveling motor. The control device 35 is connected to sensors (not shown) attached to the traveling motor 13 and the like, and detection results are input from each sensor. The control device 35 controls the operations of the components of the dump truck 1 by executing a program stored in the memory by the CPU based on the information from each component and / or the detection results from each sensor. The control device 35 controls the charge and discharge operations of the first battery 21 and the second battery 26, for example, based on the information from each component and / or the detection results from each sensor.

[0031] Based on the detection results of sensors attached to the traveling motor 13 and the like, the control device 35 monitors the power running (traveling) operation and the regeneration (braking) operation, which are the operations of the traveling motor 13. For example, based on the information of the regenerative power input from the inverter 24 for the traveling motor, the control device 35 monitors whether the traveling motor 13 is generating regenerative power and whether the generated regenerative power is less than or equal to the power that can be charged to the first battery 21.

[0032] Based on the magnitude of the regenerative power and the charge-discharge rate of the first battery 21, the control device 35 controls the charging operation of the regenerative power generated by the traveling motor 13 to the first battery 21 or the second battery 26. Specifically, when the regenerative power is less than or equal to the power that can be charged to the first battery 21, the control device 35 controls the inverter 24 for the traveling motor and the DC / DC converter 23 to supply (charge) the regenerative power from the traveling motor 13 to the first battery 21. Further, when the regenerative power is less than or equal to the power that can be charged to the first battery 21, the control device 35 controls the third switch 31 so that the supply destination of the regenerative power becomes the first battery 21 (switches the connection destination of the third switch 31). Also, when the regenerative power is greater than the power that can be charged to the first battery 21, the control device 35 controls the inverter 24 for the traveling motor and the chopper 28 to supply (charge) the regenerative power from the traveling motor 13 to the second battery 26. Further, when the regenerative power is greater than the power that can be charged to the first battery 21, the control device 35 controls the third switch 31 so that the supply destination of the regenerative power becomes the second battery 26 (switches the connection destination of the third switch 31).

[0033] When the operation of the traveling motor 13 has stopped, the control device 35 causes power to be supplied from the second battery 26 to the first battery 21. Specifically, when the operation of the traveling motor 13 has stopped, the control device 35 controls the DC / DC converter 23 and the first switch 30 so as to supply power from the second battery 26 to the first battery 21 (closes the first switch 30). Further, when the power supply from the first battery 21 to the traveling motor 13 has stopped, the control device 35 causes power to be supplied from the second battery 26 to the first battery 21. Specifically, when the power supply from the first battery 21 to the traveling motor 13 has stopped by controlling the second switch 25 (opening the second switch 25), the control device 35 controls the DC / DC converter 23 and the first switch 30 so as to supply power from the second battery 26 to the first battery 21.

[0034] Note that the case where the operation of the traveling motor 13 has stopped includes cases where the dump truck 1 is stopped, such as during loading of earth and sand, minerals, etc. from an excavating machine or the like onto the loading platform 15, during unloading of earth and sand, minerals, etc. on the loading platform 15, during a temporary stop after such work and during traveling, and during parking at a predetermined location. Note that the predetermined location is, for example, a location provided assuming parking of the dump truck 1 such as a workshop.

[0035] FIG. 4 is a flowchart showing an example of the operation of the dump truck 1 according to the first embodiment.

[0036] In the operation example shown in FIG. 4, the default open / close state of the second switch 25 is preset to a closed state that permits power supply from the first battery 21 to the traveling motor 13. In the operation example shown in FIG. 4, the default open / close state of the first switch 30 is preset to an open state that stops power supply from the second battery 26 to the first battery 21. In the operation example shown in FIG. 4, the connection destination of the third switch 31 is preset so that the default supply destination of the regenerative power is the second battery 26. Also, in the operation example shown in FIG. 4, it is started when the traveling motor 13 generates regenerative power during deceleration of the dump truck 1.

[0037] In step S1, the control device 35 determines that regenerative power is generated in the traveling motor 13 based on the information on the regenerative power input from the inverter 24 for the traveling motor.

[0038] In step S2, the control device 35 determines whether the regenerative power generated by the traveling motor 13 is less than or equal to the power that can be charged to the first battery 21 based on the information on the regenerative power input from the inverter 24 for the traveling motor. If it is determined that the regenerative power is less than or equal to the power that can be charged to the first battery 21, the control device 35 proceeds to step S3. If it is determined that the regenerative power is greater than the power that can be charged to the first battery 21, the control device 35 proceeds to step S5.

[0039] In step S3, the control device 35 causes the connection destination of the third switch 31 to be switched so that the supply destination of the regenerative power becomes the first battery 21.

[0040] In step S4, the control device 35 controls the DC / DC converter 23 so that regenerative power is supplied from the traveling motor 13 to the first battery 21. Then, the control device 35 ends the operation shown in FIG. 4.

[0041] In step S5, the control device 35 controls the chopper 28 so that regenerative power is supplied from the traveling motor 13 to the second battery 26.

[0042] In step S6, the control device 35 determines whether the traveling motor 13 has stopped based on the detection result of the sensor attached to the traveling motor 13. The control device 35 waits until it is determined that the traveling motor 13 has stopped, and if it is determined that the traveling motor 13 has stopped, it proceeds to step S7.

[0043] In step S7, the control device 35 causes the second switch 25 to be turned on to stop the power supply from the first battery 21 to the traveling motor 13.

[0044] In step S8, when the power supply from the first battery 21 to the traveling motor 13 via the first power supply path 22 is stopped, the control device 35 closes the first switch 30 to allow power supply from the second battery 26 to the first battery 21.

[0045] In step S9, the control device 35 controls the DC / DC converter 23 so that power is supplied from the second battery 26 to the first battery 21. Thereafter, the control device 35 ends the operation shown in FIG. 4.

[0046] FIG. 5 is a graph showing the variation range of the state of charge (SoC) in one cycle of the first battery 21 according to the first embodiment and the power source of a conventional electric dump truck. Among the graphs in FIG. 5, the variation range of the state of charge in one cycle of the first battery 21 is indicated by a solid line, and the variation range of the state of charge in one cycle of the power source of the conventional electric dump truck is indicated by a dotted line.

[0047] Due to the above configuration, the dump truck 1 according to the present embodiment has regenerative power supplied to the first battery 21, so that the cruising range can be extended by the amount of regenerative power supplied. That is, the first battery 21 according to the present embodiment does not need to discharge power by the amount of regenerative power supplied. As a result, as shown in FIG. 5, the first battery 21 according to the present embodiment can make the variation range D1 of the state of charge of the first battery 21 smaller than the variation range D2 of the state of charge in the power source of the conventional electric dump truck. Therefore, the first battery 21 according to the present embodiment can make the depth of discharge (DoD) shallower than that of the power source of the conventional electric dump truck.

[0048] As described above, the dump truck 1 according to the present embodiment is an electric dump truck, and includes a first battery 21, a second battery 26 having characteristics different from those of the first battery 21, and a traveling motor 13 that is driven using the electric power supplied from the first battery 21 as a power source and generates regenerative electric power during braking. The dump truck 1 according to the present embodiment further includes a control device 35 that controls the charging and discharging operations of the first battery 21 and the second battery 26. In the dump truck 1 according to the present embodiment, the capacity of the first battery 21 is larger than that of the second battery 26, the charging and discharging rate of the second battery 26 is higher than that of the first battery 21, and the control device 35 monitors the operation of the traveling motor 13 and controls the charging operation of the regenerative electric power to the second battery 26 based on the magnitude of the regenerative electric power generated by the traveling motor 13 and the charging and discharging rate of the first battery 21.

[0049] With this configuration, in the dump truck 1 according to the present embodiment, the second battery 26 having a higher charging and discharging rate than the first battery 21, which is the power source, can recover the regenerative electric power that has conventionally been discharged without being fully recovered. Therefore, the dump truck 1 according to the present embodiment can effectively utilize the recovered regenerative electric power as, for example, electric power for traveling and / or auxiliary equipment. As a result, the dump truck 1 according to the present embodiment can extend the cruising range compared to the conventional one, and thus can promote the optimization of power management. Therefore, according to the present embodiment, it is possible to provide a dump truck capable of effectively utilizing regenerative electric power and promoting the optimization of power management.

[0050] Furthermore, in the dump truck 1 according to the present embodiment, when the traveling motor 13 is stopped, the control device 35 causes the second battery 26 to supply electric power to the first battery 21.

[0051] With this configuration, in the dump truck 1 according to the present embodiment, while the traveling motor 13 is stopped, power is supplied from the second battery 26 to the first battery 21, so that the first battery 21 can surely receive the power supplied from the second battery 26. Therefore, the dump truck 1 according to the present embodiment can surely extend the cruising range, and thus can surely promote the optimization of power management. Further, the first battery 21 according to the present embodiment can prevent so-called charging, so that deterioration due to excessive temperature rise of the first battery 21 can be prevented. Also, the first battery 21 according to the present embodiment does not need to discharge as much power as that supplied from the second battery 26, so that the fluctuation range of the charge rate can be made smaller than before, and the depth of discharge of the first battery 21 can be made shallower. Therefore, the dump truck 1 according to the present embodiment can suppress the deterioration of the first battery 21.

[0052] Furthermore, in the dump truck 1 according to the present embodiment, when the power supply from the first battery 21 to the traveling motor 13 is stopped, the control device 35 causes the second battery 26 to supply power to the first battery 21.

[0053] With this configuration, in the dump truck 1 according to the present embodiment, when the power supply from the first battery 21 to the traveling motor 13 is stopped, power is supplied from the second battery 26 to the first battery 21. As a result, the first battery 21 can more surely receive the power supplied from the second battery 26. Therefore, the dump truck 1 according to the present embodiment can more surely extend the cruising range, and thus can more surely promote the optimization of power management. Further, the first battery 21 according to the present embodiment can prevent so-called charging, so that deterioration due to excessive temperature rise of the first battery 21 can be prevented. Therefore, the dump truck 1 according to the present embodiment can further suppress the deterioration of the first battery 21.

[0054] Furthermore, in the dump truck 1 according to the present embodiment, when the regenerative power is equal to or less than the power that can be charged to the first battery 21, the control device 35 charges the first battery 21 with the regenerative power.

[0055] With this configuration, the dump truck 1 according to the present embodiment includes a plurality of batteries having different characteristics as supply destinations of the regenerative power, and can select an optimal supply destination according to the state of the regenerative power as the supply destination of the regenerative power. Therefore, the dump truck 1 according to the present embodiment can eliminate power losses that may occur when the regenerative power is supplied via a battery that is not the supply destination. As a result, the dump truck 1 according to the present embodiment can further effectively utilize the regenerative power and further promote the optimization of power management.

[0056] The dump truck 1 according to the present embodiment may include a sensor that detects the voltage of the first battery 21. The control device 35 may estimate the charge rate of the first battery 21 based on the detection result of the sensor. Then, when the dump truck 1 is stopped and the charge rate of the first battery 21 is less than the first predetermined value, the control device 35 may control the DC / DC converter 23, the first switch 30, and the second switch 25. Specifically, the control device 35 may control the DC / DC converter 23, the first switch 30, and the second switch 25 to supply power from the second battery 26 to the first battery 21 until the charge rate of the first battery 21 reaches the first predetermined value. Note that the first predetermined value in the charge rate of the first battery 21 is the upper limit value of the charge rate at which charging to the first battery 21 is permitted.

[0057] Thereby, the dump truck 1 according to the present embodiment can ensure that the first battery 21 receives the power supplied from the second battery 26 and can suppress the first battery 21 from being overcharged. Therefore, the dump truck 1 according to the present embodiment can surely promote the optimization of power management and further suppress the deterioration of the first battery 21.

[0058] Also, in the dump truck 1 according to the present embodiment, when the control device 35 supplies power from the second battery 26 to the first battery 21, if the charge rate of the first battery 21 is equal to or higher than a first predetermined value, the auxiliary machine inverter 34 may be controlled. Specifically, the control device 35 may control the auxiliary machine inverter 34 to supply power from the first battery 21 to the auxiliary machine drive motor 17 until the charge rate of the first battery 21 becomes less than the first predetermined value.

[0059] Thereby, the dump truck 1 according to the present embodiment can effectively utilize the power charged in the first battery 21 without wasting it, and can suppress the first battery 21 from being overcharged. Therefore, the dump truck 1 according to the present embodiment can promote the optimization of power management and can suppress the deterioration of the first battery 21.

[0060] Also, the dump truck 1 according to the present embodiment may include a sensor that detects the voltage of the second battery 26. The control device 35 may estimate the charge rate of the second battery 26 based on the detection result of the sensor. When the charge rate of the first battery 21 is equal to or higher than a first predetermined value and the charge rate of the second battery 26 is equal to or higher than a second predetermined value, the control device 35 may control the auxiliary machine inverter 34, the DC / DC converter 23, the first switch 30, and the second switch 25. Specifically, the control device 35 controls the auxiliary machine inverter 34 to make the charge rate of the first battery 21 less than the first predetermined value. Thereafter, the control device 35 may control the DC / DC converter 23, the first switch 30, and the second switch 25 to supply power from the second battery 26 to the first battery 21 until the charge rate of the second battery 26 becomes less than the second predetermined value. Note that the second predetermined value in the charge rate of the second battery 26 is a value lower than the upper limit value of the charge rate at which charging of the second battery 26 is permitted.

[0061] As a result, the dump truck 1 according to the present embodiment can avoid the first battery 21 and the second battery 26 from remaining in a fully charged state. As a result, the dump truck 1 according to the present embodiment can effectively utilize the power charged in the first battery 21 and the second battery 26 and the regenerative power without wasting them, and can suppress the first battery 21 and the second battery 26 from being overcharged. Therefore, the dump truck 1 according to the present embodiment can promote the optimization of power management and can suppress the deterioration of the first battery 21 and the second battery 26.

[0062] [Second Embodiment] Next, the dump truck 1 according to the second embodiment will be described with reference to FIGS. 6 and 7. In the dump truck 1 according to the second embodiment, the description of the same configuration and operation as those of the dump truck 1 according to the first embodiment will be omitted.

[0063] The dump truck 1 according to the second embodiment is different from the dump truck 1 according to the first embodiment in that the power supply source of the power flowing through the auxiliary power supply path 33 is changed from the first battery 21 to the second battery 26, and the third power supply path 29 and the first switch 30 are eliminated. That is, in the dump truck 1 according to the first embodiment, power is supplied from the second battery 26 to the first battery 21, and power is supplied from the first battery 21 to the auxiliary machine. On the other hand, in the dump truck 1 according to the second embodiment, power is supplied from the second battery 26 to the auxiliary machine.

[0064] FIG. 6 is a schematic circuit diagram of the dump truck 1 according to the second embodiment.

[0065] The auxiliary machine drive motor 17 according to the second embodiment is connected to the second battery 26 via the auxiliary machine power supply path 33. The auxiliary machine drive motor 17 according to the second embodiment drives using the power supplied from the second battery 26 via the auxiliary machine power supply path 33 as power, and drives an auxiliary machine including the hoist cylinder 16. The auxiliary machine power supply path 33 according to the second embodiment is a connection line that electrically connects between the second battery 26 and the auxiliary machine (auxiliary machine drive motor 17) and serves as a path for transmitting the power output from the second battery 26 to the auxiliary machine (auxiliary machine drive motor 17). The auxiliary machine inverter 34 according to the second embodiment is provided between the second battery 26 and the auxiliary machine drive motor 17 on the path of the auxiliary machine power supply path 33. The auxiliary machine inverter 34 according to the second embodiment converts the DC power supplied from the second battery 26 into AC power based on a control command from the control device 35 and supplies it to the auxiliary machine drive motor 17. The control device 35 according to the second embodiment controls the auxiliary machine inverter 34 to control the power supply from the second battery 26 to the auxiliary machine.

[0066] Figure 7 is a flowchart showing an example of the operation of the dump truck 1 according to the second embodiment. In the operation example shown in Figure 7, the default open / closed state of the second switch 25 is preset to a closed state that always allows power supply from the first battery 21 to the travel motor 13.

[0067] In steps S11 to S15, the control device 35 according to the second embodiment performs the same operations as steps S1 to S5 shown in Figure 4.

[0068] In step S16, the control device 35 according to the second embodiment controls the auxiliary machine inverter 34 so that power is supplied from the second battery 26 to the auxiliary machine drive motor 17. Thereafter, the control device 35 according to the second embodiment ends the operation shown in Figure 7.

[0069] As described above, the dump truck 1 according to the second embodiment includes auxiliary equipment including a hoist cylinder 16, a first power supply path 22 that connects the first battery 21 and the traveling motor 13 and supplies power from the first battery 21 to the traveling motor 13, a second power supply path 27 that connects the traveling motor 13 and the second battery 26 and supplies regenerative power from the traveling motor 13 to the second battery 26, and an auxiliary equipment power supply path 33 that connects the second battery 26 and the auxiliary equipment (auxiliary equipment drive motor 17) and supplies power from the second battery 26 to the auxiliary equipment. In the dump truck 1 according to the second embodiment, the control device 35 controls the power supply from the second battery 26 to the auxiliary equipment.

[0070] With this configuration, the dump truck 1 according to the second embodiment can collect the regenerative power that has been conventionally released by the second battery 26 and supply it to the auxiliary equipment while having a simple circuit configuration. Further, in the dump truck 1 according to the second embodiment, since power is supplied from the second battery 26 to the auxiliary equipment, it is not necessary to discharge the power of the first battery 21 that has been conventionally supplied to the auxiliary equipment. Therefore, the dump truck 1 according to the second embodiment can extend the cruising range by the amount of power that has been conventionally supplied from the first battery 21 to the auxiliary equipment, so that optimization of power management can be promoted. Furthermore, since the first battery 21 according to the second embodiment does not have to discharge the power that has been conventionally supplied to the auxiliary equipment, the variation range of the charge rate can be made smaller than before. Therefore, the dump truck 1 according to the second embodiment can reduce the depth of discharge of the first battery 21, so that deterioration of the first battery 21 can be suppressed.

[0071] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention described in the claims. The present invention can add the configuration of one embodiment to the configuration of another embodiment, replace the configuration of one embodiment with that of another embodiment, or delete a part of the configuration of one embodiment.

Explanation of reference numerals

[0072] 1…Dump truck, 13…Travel motor, 16…Hoist cylinder, 21…First battery, 22…First power supply path, 25…Second switch, 26…Second battery, 27…Second power supply path, 29…Third power supply path, 30…First switch, 31…Third switch, 32…Fourth power supply path, 35…Control device, 33…Auxiliary equipment power supply path

Claims

1. An electric dump truck, comprising: a first battery; a second battery having characteristics different from those of the first battery; a traveling motor that is driven using electric power supplied from the first battery as a power source and generates regenerative electric power during braking; a control device that controls the charging and discharging operations of the first battery and the second battery; wherein: the capacity of the first battery is larger than that of the second battery; the charge-discharge rate, which is the magnitude of the charge-dischargeable electric power per unit time of the second battery, is higher than that of the first battery; the control device: monitors the operation of the traveling motor, and when the magnitude of the regenerative electric power generated by the traveling motor is less than or equal to the chargeable electric power per unit time of the first battery, causes the regenerative electric power to be supplied to the first battery, and when the magnitude of the regenerative electric power is greater than the chargeable electric power per unit time of the first battery, causes the regenerative electric power to be supplied to the second battery; when the traveling motor is stopped or the power supply from the first battery to the traveling motor is stopped, causes the second battery to supply power to the first battery. A dump truck characterized by the above.

2. An electric dump truck, comprising: a first battery; a second battery having characteristics different from those of the first battery; a traveling motor that is driven using electric power supplied from the first battery as a power source and generates regenerative electric power during braking; a control device that controls the charging and discharging operations of the first battery and the second battery; auxiliary equipment including a hoist cylinder; a first power supply path that connects the first battery and the traveling motor and supplies power from the first battery to the traveling motor; a second power supply path that connects the traveling motor and the second battery and supplies the regenerative electric power from the traveling motor to the second battery; an auxiliary equipment power supply path that connects the second battery and the auxiliary equipment and supplies power from the second battery to the auxiliary equipment; wherein: the capacity of the first battery is larger than that of the second battery; the charge-discharge rate, which is the magnitude of the charge-dischargeable electric power per unit time of the second battery, is higher than that of the first battery; the control device: monitors the operation of the traveling motor, and When the magnitude of the regenerative power generated by the traveling motor is equal to or less than the power that can be charged per unit time of the first battery, the regenerative power is supplied to the first battery. When the magnitude of the regenerative power is greater than the power that can be charged per unit time of the first battery, the regenerative power is supplied to the second battery. Power is supplied from the second battery to the auxiliary machine. A dump truck characterized by the above.

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