Work machine and method

Abstract

To suppress output fluctuations of a fuel cell.SOLUTION: A control device switches a target generated power of a fuel cell to any one of power generation candidates including a first power and a second power lower than the first power on the basis of a charging rate of a power storage device. The control device updates a value of the first power or the second power in association with switching of the target generated power between the first power and the second power.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to work machines and methods. [Background technology]

[0002] As shown in Patent Document 1, work machines equipped with fuel cells that use hydrogen as fuel are being considered. Work machines powered by fuel cells are equipped with a power storage device such as a battery to limit the amount of fuel cell installed and to absorb regenerative power. For this reason, the control device of the work machine needs to perform energy management that appropriately distributes the energy between the fuel cell and the power storage device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-110969 Summary of the Invention [Problem to be solved by the invention]

[0004] The amount of power required by a work machine varies depending on the type of work, the skill of the operator, etc. However, frequent output fluctuations in fuel cells can lead to cell deterioration. An object of the present disclosure is to provide a work machine and method that can suppress output fluctuations of a fuel cell. [Means for solving the problem]

[0005] According to one aspect of the present invention, a work machine includes a fuel cell, a power storage device, and a control device, and the control device switches the target power generation of the fuel cell to one of candidate power generation options including a first power and a second power lower than the first power based on the charging rate of the power storage device, and updates the value of the first power or the second power when the target power generation option is switched between the first power and the second power. [Effects of the Invention]

[0006] According to the above aspect, the work machine can suppress output fluctuations of the fuel cell. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view that schematically shows a work machine according to a first embodiment. [Figure 2] 1 is a schematic block diagram showing the configuration of a work machine according to a first embodiment. [Figure 3] 1 is a schematic block diagram showing the configuration of a control system provided in a work machine according to a first embodiment. FIG. [Figure 4] FIG. 4 is a diagram illustrating a control mode switching method according to the first embodiment. [Figure 5] FIG. 4 is a diagram illustrating an example of a first update method for the second generated power according to the first embodiment. [Figure 6] FIG. 10 is a diagram illustrating an example of a second update method for the second generated power according to the first embodiment. [Figure 7] 3 is a flowchart showing a control method for a work machine according to the first embodiment. [Figure 8] FIG. 10 is a perspective view schematically showing a work machine according to a second embodiment. [Figure 9] FIG. 4 is a schematic block diagram showing the configuration of a work machine according to a second embodiment. [Figure 10] FIG. 1 is a schematic block diagram illustrating the configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] First Embodiment <Configuration of work machine 10> Hereinafter, the embodiments will be described in detail with reference to the drawings. FIG. 1 is a perspective view that schematically shows a work machine 10 according to a first embodiment. The work machine 10 according to the first embodiment is, for example, a dump truck. The work machine 10 comprises a vehicle body 11, a traveling device 12, and a dump body 13. The dump body 13 is an example of a work implement.

[0009] The vehicle body 11 supports a dump truck body 13. The vehicle body 11 is supported by a traveling device 12.

[0010] The traveling device 12 supports the vehicle body 11. The traveling device 12 causes the work machine 10 to travel. The traveling device 12 causes the work machine 10 to move forward or backward. At least a portion of the traveling device 12 is disposed below the vehicle body 11. The traveling device 12 is equipped with a pair of front wheels and a pair of rear wheels. The front wheels are steered wheels, and the rear wheels are drive wheels. Note that the combination of steered wheels and drive wheels is not limited to this, and the traveling device 12 may be four-wheel drive or four-wheel steering.

[0011] The dump body 13 is a member for loading a load. The dump body 13 is subjected to dumping and lowering operations by the hoist cylinder 154. In this embodiment, the dumping operation includes raising the front end of the dump body 13 and tilting the loading surface of the dump body 13 downward toward the rear of the vehicle body. The lowering operation includes lowering the front end of the raised dump body 13.

[0012] Figure 2 is a schematic block diagram showing the configuration of a work machine 10 according to the first embodiment. As shown in Figure 2, the work machine 10 is equipped with a power system 14, a drive system 15, and a control system 16. The power system 14 is configured to generate power for operating the work machine 10. The drive system 15 is configured to operate the work machine 10 using the power generated by the power system 14. The control system 16 is configured to control the power system 14 and the drive system 15.

[0013] The power system 14 generates electric power as a power source and includes a hydrogen tank 141, a hydrogen supply device 142, an air intake device 143, a fuel cell 144, a first power converter 145, a battery 146, a second power converter 147, and a retarder 148.

[0014] The hydrogen supply device 142 supplies hydrogen filled in the hydrogen tank 141 to the fuel cell 144. The air intake device 143 supplies air to the fuel cell 144. The air intake device 143 is, for example, a blower or a compressor. The fuel cell 144 generates electricity by causing an electrochemical reaction between the hydrogen supplied from the hydrogen supply device 142 and the oxygen contained in the air supplied from the air intake device 143.

[0015] The first power converter 145 controls the output of the electric power generated by the fuel cell 144. The first power converter 145 is, for example, a DC-DC converter. The first power converter 145 converts the electric power generated by the fuel cell 144 into electric power of a predetermined voltage and outputs it in accordance with a command from the control system 16. The electric power output by the first power converter 145 is output to the drive system 15 via the bus B.

[0016] The battery 146 stores the power generated in the fuel cell 144. The battery 146 is an example of a power storage device. Note that in other embodiments, the work machine 10 may be equipped with another power storage device, such as a capacitor, instead of the battery 146. The battery 146 is provided with a monitoring device (not shown) that monitors the state of the battery 146. The monitoring device determines the maximum chargeable power and the maximum dischargeable power using measurement data that indicates the state of the battery 146, such as the temperature, charging rate, and voltage of the battery 146. For example, the maximum chargeable power and the maximum dischargeable power become smaller as the temperature of the battery 146 increases. The monitoring device may calculate the charging rate of the battery 146 based on measurement data of the voltage and current of the battery 146, for example.

[0017] The second power converter 147 controls the input and output of power to and from the battery 146. It converts the input power and outputs it. The second power converter 147 is, for example, a DC-DC converter. The second power converter 147 converts the power input from the battery 146 into power of a predetermined voltage and outputs it in accordance with a command from the control system 16. The power output by the second power converter 147 is output to the drive system 15 via the bus B.

[0018] The retarder 148 converts regenerated electric power generated by the electric traction motor 156 (described later) into thermal energy when the regenerated electric power cannot be charged into the battery 146. The retarder 148 is an example of a consumption device for consuming surplus electric power.

[0019] The drive system 15 includes an inverter 151, an electric pump motor 152, a hydraulic pump 153, a hoist cylinder 154, an inverter 155, and an electric travel motor 156. The inverter 151 converts DC current from the bus B into three-phase AC current and supplies it to the electric pump motor 152. The electric pump motor 152 drives the hydraulic pump 153. Hydraulic oil discharged from the hydraulic pump 153 is supplied to the hoist cylinder 154 via a control valve (not shown). The supply of hydraulic oil to the hoist cylinder 154 activates the hoist cylinder 154. The hoist cylinder 154 performs a dumping or lowering operation on the dump body 13. The inverter 155 converts DC current from the bus B into three-phase AC current and supplies it to the electric travel motor 156. The rotational force generated by the electric travel motor 156 is transmitted to the drive wheels of the traveling device 12.

[0020] 3 is a schematic block diagram showing the configuration of the control system 16 provided in the work machine 10 according to the first embodiment. The control system 16 includes a measuring device 161, an operating device 162, and a control device 163.

[0021] The measuring device 161 acquires measurement data indicating the state of the battery 146. The measuring device 161 includes at least a monitoring device for the battery 146. The measuring device 161 outputs the acquired measurement data to the control device 163. The measuring device 161 may also acquire measurement data relating to the operating state of the work machine 10. The measuring device 161 may have, for example, a speed sensor for measuring the vehicle speed of the work machine 10, an acceleration sensor for measuring the acceleration of the work machine 10, and a GNSS (Global Navigation Satellite System) for measuring the position of the work machine 10 and the direction in which the work machine 10 is facing.

[0022] The operating device 162 is provided in the driver's cab and is operated by the operator to operate the work machine 10. The operating device 162 includes, for example, an accelerator pedal, a brake pedal, a steering wheel, a work equipment lever, etc. The operating device 162 outputs an operation signal to the control device 163.

[0023] The control device 163 is configured to drive the work machine 10 in accordance with an operation signal from the operation device 162. The control device 163 includes a receiving unit 201, a vehicle body control unit 202, a target generated power determination unit 203, a fuel cell control unit 204, a battery control unit 205, an update unit 206, and a generated power storage unit 207.

[0024] The receiving unit 201 receives measurement data from the measuring device 161. The receiving unit 201 receives an operation signal from the operation device 162.

[0025] The vehicle body control unit 202 generates a control signal for controlling the work machine 10 based on an operation signal from the operation device 162. The vehicle body control unit 202 generates control signals for controlling, for example, the steering, accelerator, brakes, and operation of the dump body of the traveling device 12.

[0026] The target generated power determination unit 203 determines the target generated power of the fuel cell 144 based on the charging rate of the battery 146. Specifically, the target generated power determination unit 203 determines the control mode of the fuel cell 144 to be either high output mode, medium output mode, or low output mode based on the charging rate of the battery 146. When the control mode is the high output mode, the target generated power determination unit 203 determines the target generated power to be a first generated power (first power) that is sufficiently greater than the difference between the power required for power running and the power generated by regeneration in one cycle of the work machine 10. When the control mode is the low output mode, the target generated power determination unit 203 determines the target generated power to be a third generated power (third power) that is sufficient to operate the auxiliary devices of the fuel cell 144. In other words, the fuel cell 144 according to the first embodiment is controlled to perform idling operation in the low output mode. When the control mode is the medium output mode, target generated power determination unit 203 determines the target generated power to be a second generated power (second power) that is smaller than the first generated power and larger than the third generated power. That is, the target generated power determination unit 203 determines the target generated power of the fuel cell 144 to be one of the first generated power, second generated power, or third generated power, which are candidate generated powers. The magnitude of the second generated power is updated by the update unit 206. In other embodiments, the target generated power in the low output mode may be zero. In this case, the fuel cell 144 may be stopped in the low output mode.

[0027] 4 is a diagram showing a control mode switching method according to the first embodiment. Target power generation power determination unit 203 switches the control mode by comparing the charging rate of battery 146 with a threshold. When the current control mode is the medium output mode, target power generation power determination unit 203 switches the control mode from the medium output mode to the high output mode when the charging rate of battery 146 falls below threshold Th1 (first threshold). When the current control mode is the high output mode, target power generation power determination unit 203 switches the control mode from the high output mode to the medium output mode when the charging rate of battery 146 exceeds threshold Th3 (second threshold). When the current control mode is the medium output mode, target power generation power determination unit 203 switches the control mode from the medium output mode to the low output mode when the charging rate of battery 146 exceeds threshold Th4 (third threshold). When the current control mode is the low output mode, target generated power determination unit 203 switches the control mode from the low output mode to the medium output mode when the charging rate of battery 146 falls below threshold Th2 (fourth threshold). The relationship between each threshold is as follows: Th1 <Th2<Th3<Th4である。

[0028] The fuel cell control unit 204 controls the amount of power generated by the fuel cell 144 in accordance with the target power generation determined by the target power generation determination unit 203. The fuel cell control unit 204 controls the amount of hydrogen supplied by the hydrogen supply device 142, the amount of air supplied by the air intake device 143, and the first power converter 145 connected to the fuel cell 144 so that the fuel cell 144 generates power in accordance with the target power generation determined by the target power generation determination unit 203. The fuel cell control unit 204 causes the fuel cell 144 to output a constant amount of generated power until the control mode is switched.

[0029] The battery control unit 205 controls the second power converter 147 connected to the battery 146 so as to discharge or charge the battery 146 with the power difference between the power required for control by the vehicle body control unit 202 and the power generated by the fuel cell 144.

[0030] When the control mode is switched to the medium output mode, the updating unit 206 updates the magnitude of the second generated power based on the most recent operation history of the work machine 10. The updating unit 206 records the updated magnitude of the second power in the generated power storage unit 207. Specifically, when the control mode is switched from the high output mode to the medium output mode, the updating unit 206 sets the new second generated power to a value obtained by weighting the first generated power and the second generated power with a weight according to the ratio of the time in the medium output mode to the time in the high output mode immediately before the switch. Furthermore, when the control mode is switched from the low output mode to the medium output mode, the updating unit 206 sets the new second generated power to a value obtained by weighting the third generated power and the second generated power with a weight according to the ratio of the time in the medium output mode to the time in the low output mode immediately before the switch.

[0031] FIG. 5 is a diagram illustrating an example of a first method for updating the second generated power according to the first embodiment. In the example illustrated in FIG. 5, the control mode is switched to the medium output mode at time t1, then the control mode is switched to the high output mode at time t2, and then the control mode is switched back to the medium output mode at time t3. At time t3, the update unit 206 updates the second generated power based on the operation history from time t1 to time t3. The update unit 206 according to the first embodiment updates the second generated power before switching the control mode. Note that the update unit 206 according to other embodiments may update the second generated power after switching the control mode.

[0032] The update unit 206 updates the control period T mid and the control period T of the high-power mode immediately before the switching high And the previous second power generation power P mid old and the first power generation power P high Based on this, the new second power generation power P mid new In the example shown in FIG. 5, the control period T mid is the period from time t1 to time t2, and the high-power mode control period T highis the period from time t2 to time t3. The update unit 206 calculates the new second generated power P mid new Ask for.

[0033]

number

[0034] Fig. 6 is a diagram showing an example of a second update method for the second generated power according to the first embodiment. In the example shown in Fig. 6, the control mode is switched to the medium output mode at time t4, then the control mode is switched to the low output mode at time t5, and then the control mode is switched back to the medium output mode at time t6. At time t6, the update unit 206 updates the second generated power based on the operation history from time t4 to time t6.

[0035] The update unit 206 updates the control period T mid and the control period T of the low output mode immediately before the switching low And the previous second power generation power P mid old and Third Power Generation Power P low Based on this, the new second power generation power P mid new In the example shown in FIG. 6, the control period T mid is the period from time t4 to time t5, and the control period T low is the period from time t5 to time t6. The update unit 206 calculates the new second generated power P mid new Ask for.

[0036]

number

[0037] The generated power storage unit 207 stores the values ​​of the first generated power, the second generated power, and the third generated power, which are the target generated power for each mode. Note that the value of the first generated power, which is the target generated power for the high output mode, and the value of the third generated power, which is the target generated power for the low output mode, are fixed values, so the generated power storage unit 207 does not need to store the values ​​of the first generated power and the third generated power. In other words, the generated power storage unit 207 stores at least the value of the second generated power, which is the target generated power for the medium output mode.

[0038] Control Method FIG. 7 is a flowchart showing a control method for the work machine 10 according to the first embodiment. When the work machine 10 according to the first embodiment is started, the target power generation determination unit 203 of the control device 163 determines the initial value of the control mode to be the medium output mode and determines the target power generation of the fuel cell 144 to be the second output power (step S1). When the work machine 10 is started, the second output power has not been updated, so the target power generation determined in step S1 is the initial value of the second output power. The fuel cell control unit 204 controls the amount of power generated by the fuel cell 144 so as to output the second output power. At this time, the update unit 206 stores the time when the medium output mode was selected. The receiving unit 201 receives measurement data of the charging rate of the battery 146 from the measurement device 161 (step S2). The target power generation determination unit 203 determines whether the charging rate indicated by the measurement data is below threshold value Th1 (step S3). If the charging rate is not below threshold value Th1 (step S3: NO), the target power generation determination unit 203 determines whether the charging rate indicated by the measurement data is above threshold value Th4 (step S4). If the charging rate is not lower than the threshold value Th1 and is not higher than the threshold value Th4 (step S4: NO), the control device 163 returns the process to step S2 and continues the control in the medium output mode.

[0039] If the charging rate is below threshold value Th1 (step S3: YES), target power generation determination unit 203 switches the control mode to high-output mode and determines the target power generation of fuel cell 144 to be the first power generation power (step S5). Fuel cell control unit 204 controls fuel cell 144 to output the first power generation power. At this time, update unit 206 stores the time when high-output mode was selected. Receiving unit 201 receives measurement data of the charging rate of battery 146 from measuring device 161 (step S6). Target power generation determination unit 203 determines whether the charging rate indicated by the measurement data exceeds threshold value Th3 (step S7). If the charging rate does not exceed threshold value Th3 (step S7: NO), control device 163 returns the process to step S6 and continues control in high-output mode.

[0040] If the charging rate is above threshold value Th3 (step S7: YES), update unit 206 calculates the control period of the medium output mode immediately before the switching from the stored times when the medium output mode was switched to the high output mode and the stored times when the high output mode was switched to, and calculates the control period of the high output mode immediately before the switching from the stored times when the high output mode was switched to and the current time. Then, update unit 206 updates the second generated power using equation (1) above and records the new value of the second generated power in generated power storage unit 207 (step S8). Next, target generated power determination unit 203 switches the control mode to the medium output mode and determines the target generated power of fuel cell 144 to be the updated second generated power (step S9). Fuel cell control unit 204 controls fuel cell 144 to output the updated second generated power. At this time, update unit 206 stores the time when the high output mode was switched to. Control device 163 returns the process to step S2 and continues control in the medium output mode.

[0041] If the charging rate is above threshold value Th4 (step S4: YES), target power generation determination unit 203 switches the control mode to low output mode and determines the target power generation of fuel cell 144 to be the third power generation power (step S10). Fuel cell control unit 204 controls fuel cell 144 to output the third power generation power. At this time, update unit 206 stores the time when low output mode was entered. Receiving unit 201 receives measurement data of the charging rate of battery 146 from measuring device 161 (step S11). Target power generation determination unit 203 determines whether the charging rate indicated by the measurement data is below threshold value Th2 (step S12). If the charging rate is not below threshold value Th2 (step S12: NO), control device 163 returns the process to step S11 and continues control in high output mode.

[0042] If the charging rate is below threshold Th2 (step S12: YES), update unit 206 calculates the control period of the medium output mode immediately before the switching from the stored times when the mode switched to the medium output mode and the low output mode, and calculates the control period of the low output mode immediately before the switching from the stored times when the mode switched to the low output mode and the current time. Then, update unit 206 updates the second generated power using equation (2) above and records the new value of the second generated power in generated power storage unit 207 (step S13). Next, target generated power determination unit 203 switches the control mode to the medium output mode and determines the target generated power of fuel cell 144 to be the updated second generated power (step S14). Fuel cell control unit 204 controls fuel cell 144 to output the updated second generated power. At this time, update unit 206 stores the time when the mode switched to the high output mode. Control device 163 returns the process to step S2 and continues control in the medium output mode.

[0043] Actions and Effects In this way, the control device 163 according to the first embodiment controls the amount of power generated by the fuel cell 144 in the medium output mode, and when the charging rate of the battery 146 decreases, switches the control mode of the fuel cell 144 to the high output mode. As a result, the control device 163 controls the fuel cell 144 to increase the power generation, thereby increasing the charging rate of the battery 146. When the charging rate of the battery 146 recovers to a predetermined value in the high output mode, the control device 163 updates the second generated power, which is the target power generation power of the fuel cell 144 in the medium output mode. Because the charging rate of the battery 146 has been on a decreasing trend due to the previous control in the medium output mode, the control device 163 updates the second generated power to increase the amount of power generated by the fuel cell 144. As a result, the control device 163 can control the amount of power generated by the fuel cell 144 so as to balance the charging rate of the battery 146 during control in the medium output mode. For example, according to the example shown in FIG. 5, it can be seen that the slope of the change in the charging rate of the battery 146 after time t3 is gentler than the slope of the change in the charging rate of the battery 146 from time t1 to time t2. Therefore, the control device 163 can suppress fluctuations in the output of the fuel cell 144.

[0044] Furthermore, the control device 163 according to the first embodiment controls the amount of power generated by the fuel cell 144 in the medium output mode, and when the charging rate of the battery 146 increases, switches the control mode of the fuel cell 144 to the low output mode. As a result, the control device 163 controls the fuel cell 144 to reduce the power generated, thereby reducing the charging rate of the battery 146. When the charging rate of the battery 146 settles to a predetermined value in the low output mode, the control device 163 updates the second generated power, which is the target power generated by the fuel cell 144 in the medium output mode. Because the charging rate of the battery 146 has been increasing due to the previous control in the medium output mode, the control device 163 updates the second generated power to reduce the amount of power generated by the fuel cell 144. As a result, the control device 163 can control the amount of power generated by the fuel cell 144 so that the charging rate of the battery 146 is balanced during control in the medium output mode. For example, according to the example shown in FIG. 6, it can be seen that the slope of the change in the charging rate of the battery 146 after time t6 is gentler than the slope of the change in the charging rate of the battery 146 from time t3 to time t4. Therefore, the control device 163 can suppress fluctuations in the output of the fuel cell 144.

[0045] Furthermore, when updating the second generated power when switching from the high output mode to the medium output mode, the control device 163 according to the first embodiment calculates a weighted average of the second generated power and the first generated power based on the most recent control time in the medium output mode and the most recent control time in the high output mode. That is, the shorter the length of the medium output mode, the greater the increase in the second generated power. On the other hand, the longer the length of the medium output mode, the smaller the increase in the second generated power. This allows the control device 163 to quickly suppress output fluctuations of the fuel cell 144.

[0046] Furthermore, when updating the second generated power when switching from the low output mode to the medium output mode, the control device 163 according to the first embodiment calculates a weighted average of the second generated power and the third generated power based on the most recent control time in the medium output mode and the most recent control time in the low output mode. That is, the shorter the length of the medium output mode, the greater the amount of reduction in the second generated power. On the other hand, the longer the length of the medium output mode, the smaller the amount of reduction in the second generated power. This enables the control device 163 to quickly suppress output fluctuations of the fuel cell 144.

[0047] Second Embodiment <Configuration of work machine 10> Figure 8 is a perspective view that schematically shows a work machine 10 according to the second embodiment. The work machine 10 according to the second embodiment is, for example, a hydraulic excavator. The work machine 10 comprises a vehicle body 11 (swinging body), a traveling device 12, a work implement 13', and a control device 163. The work machine 10, which is a hydraulic excavator, excavates earth and sand and levels the ground at a work site or the like.

[0048] The vehicle body 11 is rotatably supported by the traveling device 12. The vehicle body 11 according to the second embodiment is rotated relative to the traveling device 12 by an electric rotation motor 322, which will be described later. The traveling device 12 supports the work machine 10 so that it can travel. The traveling device 12 according to the second embodiment has a pair of left and right tracks. The work machine 10 moves forward, turns, or moves backward by rotation of the pair of tracks.

[0049] The work implement 13' is operably supported on the vehicle body 11 of the work machine 10. The work implement 13' includes a boom 131, an arm 132, and an attachment 133 which is a working implement. In the example shown in FIG. 8, the attachment 133 is a bucket. The base end of the boom 131 is rotatably attached to the vehicle body 11. The base end of the arm 132 is rotatably attached to the tip of the boom 131. The attachment 133 is rotatably attached to the tip of the arm 132.

[0050] The work machine 10 is equipped with a plurality of actuators for driving the work implement 13'. The plurality of actuators are, for example, a boom cylinder 131C, an arm cylinder 132C, and an attachment cylinder 133C.

[0051] The boom cylinder 131C is a hydraulic cylinder for driving the boom 131. A base end of the boom cylinder 131C is attached to the vehicle body 11. A tip end of the boom cylinder 131C is attached to the boom 131. The arm cylinder 132C is a hydraulic cylinder for driving the arm 132. A base end of the arm cylinder 132C is attached to the boom 131. A tip end of the arm cylinder 132C is attached to the arm 132. The attachment cylinder 133C is a hydraulic cylinder for driving the attachment 133. A base end of the attachment cylinder 133C is attached to the arm 132. A tip end of the attachment cylinder 133C is attached to the attachment 133.

[0052] Figure 9 is a schematic block diagram showing the configuration of a work machine 10 according to the second embodiment. As shown in Figure 9, the work machine 10 is equipped with a power system 14, a drive system 15, and a control system 16. The configurations of the power system 14 and the control system 16 are the same as those in the first embodiment.

[0053] The drive system 15 according to the second embodiment includes a hydraulic travel motor 158 connected to a hydraulic pump 153, a boom cylinder 131C, an arm cylinder 132C, and an attachment cylinder 133C, instead of the hoist cylinder 154 of the first embodiment. The rotational force generated by the hydraulic travel motor 158 is transmitted to the traveling device 12. The drive system 15 according to the second embodiment includes an electric swing motor 157 connected to an inverter 155, instead of the electric travel motor 156 of the first embodiment. The electric swing motor 157 rotates by the supplied three-phase AC current and swings the carbody 11 relative to the traveling device 12. The electric swing motor 322 performs power running to swing the carbody 11 and regenerative running to generate regenerative power to decelerate the swing of the carbody 11.

[0054] As in the first embodiment, the control device 163 according to the second embodiment is configured to drive the work machine 10 in accordance with an operation signal from the operating device 162. The first generated power according to the second embodiment may be any power that is sufficiently greater than the difference between the power required for power running and the power generated by regenerative operation in, for example, one cycle related to excavation and loading of the work machine 10. The method of determining the target generated power and the method of updating the second generated power by the control device 163 according to the second embodiment are the same as those in the first embodiment.

[0055] Actions and Effects In this way, the control device 163 according to the second embodiment can suppress output fluctuations of the fuel cell 144, similar to the first embodiment, even when the work machine 10 is a hydraulic excavator.

[0056] In the work machine 10 according to the second embodiment, the electric swing motor 157 rotates the rotating body 120, but this is not limited to this. For example, in the work machine 10 according to other embodiments, the hydraulic swing motor, which is a hydraulic actuator, may rotate the rotating body 120.

[0057] <Computer Configuration> FIG. 8 is a schematic block diagram illustrating the configuration of a computer according to at least one embodiment. The computer 90 includes a processor 91 , a main memory 92 , a storage 93 , and an interface 94 . The above-mentioned control device 163 is implemented in a computer 90. The operations of the above-mentioned processing units are stored in the form of a program in a storage 93. The processor 91 reads the program from the storage 93, loads it into the main memory 92, and executes the above-mentioned processing in accordance with the program. The processor 91 also allocates storage areas in the main memory 92 corresponding to the above-mentioned storage units in accordance with the program. Examples of the processor 91 include a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), and a microprocessor.

[0058] The program may be for realizing some of the functions to be performed by the computer 90. For example, the program may be combined with other programs already stored in storage or implemented in other devices to perform the functions. In another embodiment, the computer 90 may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor 91 may be realized by the integrated circuit. Such an integrated circuit is also an example of a processor. In another embodiment, the computer 90 may be virtualized on one or more computers.

[0059] Examples of storage 93 include a magnetic disk, a magneto-optical disk, an optical disk, and a semiconductor memory. Storage 93 may be an internal medium directly connected to the bus of computer 90, or an external medium connected to computer 90 via interface 94 or a communication line. Furthermore, when this program is distributed to computer 90 via a communication line, computer 90 that receives the program may load the program into main memory 92 and execute the above-described processing. In at least one embodiment, storage 93 is a non-transitory tangible storage medium.

[0060] The program may also be a program for realizing some of the above-described functions. Furthermore, the program may be a so-called differential file (differential program) that realizes the above-described functions in combination with another program already stored in storage 93.

[0061] Other Embodiments Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design modifications are possible. That is, in other embodiments, the order of the above-described processes may be changed as appropriate. Furthermore, some processes may be executed in parallel. The control device 163 according to the above-described embodiment may be configured by a single computer 90, or the configuration of the control device 163 may be divided among multiple computers 90, and the multiple computers 90 may function as the control device 163 by working together. In this case, some of the computers 90 that make up the control device 163 may be mounted inside the work machine 10, and other computers 90 may be provided outside the work machine 10. For example, when a work machine 10 according to another embodiment is remotely operated, configurations other than the fuel cell control unit 204 and the battery control unit 205 may be provided in a remote computer 90.

[0062] Furthermore, the update unit 206 of the control device 163 according to the above-described embodiment updates the value of the second generated power to a weighted average of the first generated power and the second generated power, with the weight corresponding to the ratio between the time spent generating power at the first generated power and the time spent generating power at the second generated power, but this is not limited to this. For example, the update unit 206 according to other embodiments may update the value of the second generated power by increasing or decreasing it by a fixed amount.

[0063] Furthermore, the control device 163 according to the embodiment described above updates the magnitude of the second generated power based on the most recent operation history of the work machine 10 when the control mode switches to the medium output mode, but this is not limited to this. For example, the control device 163 according to other embodiments may update the magnitude of the second generated power based on the relationship between the first generated power or the third generated power and the second generated power, for example, two or more cycles ago. In other words, the control device 163 according to other embodiments may update the magnitude of the second generated power by referring to older operation history rather than the most recent operation history at the time when the second generated power is to be updated.

[0064] Furthermore, the control device 163 according to another embodiment may update the second generated power not only when the control mode switches to the medium output mode but also at any timing after the timing at which the relationship between the first generated power or the third generated power and the second generated power is identified in order to update the second generated power. In other words, the second generated power may not be updated immediately when the control mode switches to the medium output mode, but may be updated at a later timing.

[0065] Furthermore, the control device 163 according to the above-described embodiment has three control modes: a high output mode, a medium output mode, and a low output mode; however, this is not limiting. For example, the control modes according to other embodiments may be two: a high output mode and a medium output mode, or two: a medium output mode and a low output mode. When the control modes are the high output mode and the medium output mode, the control device 163 switches the target power generation of the fuel cell 144 between a first power generation (first power) and a second power generation (second power) lower than the first power generation, based on the charging rate of the battery 146. When the target power generation is switched between the first power generation and the second power generation, the control device 163 updates the value of the second power generation. When the control modes are the medium output mode and the low output mode, the control device 163 switches the target power generation of the fuel cell 144 between the second power generation (first power) and a third power generation (second power) lower than the second power generation, based on the charging rate of the battery 146. When the target generated power is switched between the second generated power and the third generated power, the control device 163 updates the value of the second generated power.

[0066] Furthermore, although the work machine 10 according to the embodiment described above is equipped with a retarder 148 that consumes surplus power, this is not limited to this. For example, a work machine 10 according to another embodiment may not be equipped with a retarder 148, and may instead consume surplus power by an electric pump motor 152 or an accessory mounted on the work machine 10.

[0067] Furthermore, in the above-described embodiment, a dump truck and a hydraulic excavator have been described as examples of work machines equipped with a fuel cell 144 and a battery 146, but the present invention is not limited to these. For example, work machines according to other embodiments may be other work machines such as a bulldozer, a wheel loader, a crane, a forklift, or a motor grader. [Explanation of symbols]

[0068] 10...Work machine 11...Vehicle body 12...Traveling device 13...Dump body 14...Power system 141...Hydrogen tank 142...Hydrogen supply device 143...Air intake device 144...Fuel cell 145...First power converter 146...Battery 147...Second power converter 148...Retarder 15...Drive system 151...Inverter 152...Electric pump motor 153...Hydraulic pump 154...Hoist cylinder 155...Inverter 156...Electric travel motor 16...Control system 161...Measuring device 162...Operation device 163...Control device 201...Receiver 202...Vehicle body control unit 203...Target generated power determination unit 204...Fuel cell control unit 205...Battery control unit 206...Update unit 207...Generated power storage unit 90...Computer 91...Processor 92...Main memory 93...Storage 94...Interface

Claims

1. A work machine equipped with a fuel cell and a power storage device, A control device is provided, The control device switching the target power generation output of the fuel cell to one of power generation output candidates including a first power and a second power lower than the first power based on the charging rate of the power storage device; updating the value of the first power or the second power when the target generated power is switched between the first power and the second power; Work machinery.

2. The control device When the target power generation power is switched between the first power and the second power, the value of the first power or the second power is updated based on the ratio of the time spent generating power at the first power to the time spent generating power at the second power before the switching.

2. The work machine according to claim 1.

3. the control device updates the value of the first power or the second power when switching the target generated power between the first power and the second power.

2. The work machine according to claim 1.

4. when switching the target power generation power between the first power and the second power, the control device updates the value of the first power or the second power based on a ratio between a time spent generating power at the first power and a time spent generating power at the second power immediately before the switching.

3. The work machine according to claim 2.

5. The control device when the charging rate of the power storage device falls below a first threshold, the target generated power is switched to the first power; When the charging rate of the power storage device exceeds a second threshold value that is higher than the first threshold value, the target generated power is switched to the second power.

2. The work machine according to claim 1.

6. the candidate generated powers include a third power that is lower than the second power; The control device updating the value of the second power or the third power when the target generated power is switched between the second power and the third power; 2. The work machine according to claim 1.

7. The control device When the target power generation power is switched between the second power and the third power, the value of the second power or the third power is updated based on the ratio of the time spent generating power at the second power to the time spent generating power at the third power before the switching.

7. The work machine according to claim 6.

8. The control device updating the value of the second power based on a ratio of a time spent generating power at the first power to a time spent generating power at the second power before switching the target generated power between the first power and the second power; updating the value of the second power based on a ratio of a time spent generating power at the second power to a time spent generating power at the third power before switching the target generated power between the second power and the third power; 8. The work machine according to claim 7.

9. The control device When the target power generation power is the second power and the charging rate of the power storage device falls below a first threshold, the target power generation power is switched to the first power; When the target power generation power is the first power and the charging rate of the power storage device exceeds a second threshold value that is higher than the first threshold value, the target power generation power is switched to the second power; When the target power generation power is the second power and the charging rate of the power storage device exceeds a third threshold value that is higher than the second threshold value, the target power generation power is switched to the third power; when the target power generation power is the third power and the charging rate of the power storage device falls below a fourth threshold that is higher than the first threshold and lower than the second threshold, the target power generation power is switched to the second power; 7. The work machine according to claim 6.

10. The control device When the target power generation power is switched between the first power and the second power, a weighted average of the first power and the second power is updated to the value of the first power or the second power, with a weight corresponding to the ratio of the time spent generating power at the first power to the time spent generating power at the second power before the switching. A work machine according to any one of claims 1 to 9.

11. 1. A method for controlling a work machine equipped with a fuel cell and a power storage device, comprising: switching the target power generation output of the fuel cell to one of power generation output candidates including a first power and a second power lower than the first power based on the charging rate of the power storage device; updating a value of the first power or the second power when the target power generation power is switched between the first power and the second power; A method for providing the above.

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