Work machine and method

Abstract

In the present invention, a control device starts a stopping process for a set of first fuel cell modules. After the start of the stopping process for the set of first fuel cell modules, the control device starts a stopping process for a set of second fuel cell modules.

Description

Work machine and method

[0001] This application claims priority to Japanese Patent Application No. 2024-056152, filed on March 29, 2024, the contents of which are incorporated herein by reference.

[0002] In the technical field of work machines, work machines equipped with fuel cell modules are known. Fuel cells generate electrical energy through a chemical reaction between hydrogen and oxygen. The hydrogen fuel is supplied from a tank filled with hydrogen gas, and the oxygen is supplied from the atmosphere.

[0003] During the shutdown process of a fuel cell, if hydrogen remains in the anode and air remains in the cathode, the air and hydrogen may combine while the fuel cell is shut down, creating an undesirable potential and potentially resulting in oxidation or corrosion. Therefore, it is desirable to completely react the hydrogen and oxygen remaining in the fuel cell. In this case, the reaction of the hydrogen and oxygen remaining in the fuel cell generates surplus power. Patent Document 1 discloses a technology for charging a capacitor with the surplus power generated when the fuel cell is shut down in order to improve energy efficiency.

[0004] JP 2018-006125 A

[0005] However, the remaining capacity of a power storage device mounted on a work machine is not necessarily sufficient, and it may not be possible to charge all of the surplus power into the power storage device. Patent Document 1 discloses that when the remaining capacity of the power storage device is depleted, the power of the power storage device and the power generated by the fuel cell are consumed by the load. On the other hand, if a work machine is equipped with multiple fuel cell modules, there is a possibility that the power generated during the shutdown process will exceed the upper limit of the power consumption of the load. In this case, the bus voltage will exceed the allowable voltage of the bus.

[0006] An object of the present disclosure is to provide a work machine and method that can appropriately consume generated power that is generated by shutting down a plurality of fuel cell modules.

[0007] According to one aspect of the present disclosure, a work machine is a work machine equipped with a work implement, and includes a plurality of fuel cell modules and a control device, and when the control device receives a stop request signal to stop the work machine, it starts a stop process for a first set of fuel cell modules that are part of the plurality of fuel cell modules, and after the stop process for the first set of fuel cell modules has started, it starts a stop process for a second set of fuel cell modules that are part of the plurality of fuel cell modules, and supplies the generated power generated by the stop process for the first set of fuel cell modules and the generated power generated by the stop process for the second set of fuel cell modules to a load or a power storage device.

[0008] According to the above aspect, the work machine can appropriately consume the generated power that is produced by the shutdown process of the multiple fuel cell modules.

[0009] Fig. 1 is a perspective view of a work machine according to a first embodiment. Fig. 2 is a schematic block diagram showing the configuration of a work machine according to a first embodiment. Fig. 3 is a schematic block diagram showing the configuration of a control system provided in the work machine according to the first embodiment. Fig. 4 is a flowchart showing stop processing of a work machine according to the first embodiment. Fig. 5 is a schematic block diagram showing the configuration of a computer according to the embodiment.

[0010] First Embodiment Configuration of Work Machine 1 Figure 1 is a perspective view of a work machine 1 according to the first embodiment. The work machine 1 according to the first embodiment is, for example, a hydraulic excavator. The work machine 1 includes a traveling body 110, a revolving body 120, a work implement 130, a driver's cab 140, and a machine room 150. The work machine 1, which is a hydraulic excavator, excavates earth and sand and levels the ground at a work site or the like. The traveling body 110 and the revolving body 120 form a vehicle body.

[0011] The running body 110 supports the work machine 1 so that it can travel. The running body 110 has a pair of left and right tracks. The work machine 1 moves forward, swing, or reverse by rotation of the pair of tracks. The rotating body 120 is supported on the running body 110 so that it can swing. The rotating body 120 swings relative to the running body 110 by an electric swing motor 322, which will be described later. The rotating body 120 supports the work implement 130, the operator's cab 140, the machine room 150, and the fuel cell system 20.

[0012] The work implement 130 is operably supported on the body of the work machine 1. The work implement 130 includes a boom 131, an arm 132, and an attachment 133 which is a working tool. The attachment 133 is an example of a working tool. In the example shown in FIG. 1 , the attachment 133 is a bucket. The base end of the boom 131 is rotatably attached to the front end of the rotating unit 120. 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.

[0013] The work implement 130 is driven by a plurality of actuators, which include, for example, a boom cylinder 131C, an arm cylinder 132C, and an attachment cylinder 133C.

[0014] The boom cylinder 131C is a hydraulic cylinder for driving the boom 131. The base end of the boom cylinder 131C is attached to the revolving unit 120. The 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. The base end of the arm cylinder 132C is attached to the boom 131. The 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. The base end of the attachment cylinder 133C is attached to the arm 132. The tip end of the attachment cylinder 133C is attached to the attachment 133.

[0015] The cab 140 is where the operator of the work machine 1 gets in and operates and pilots the work machine 1. The cab 140 is located, for example, on the left side of the front end of the rotating bed 120. The cab 140 of the work machine 1 is equipped with an operating device 142 for operating the work machine 1, and a power switch 143.

[0016] The operating device 142 is operated by an operator to operate the work machine 1. The operating device 142 outputs an operating signal in response to operation by the operator. The power switch 143 is a switch for starting or terminating operation of the work machine 1. The power switch 143 outputs a signal in response to operation by the operator. The power switch 143 outputs a start request signal when operated on when the power to the work machine is off. The power switch 143 outputs a stop request signal when operated off when the power to the work machine is on. The power switch 143 may be, for example, a switch that outputs a start request signal when pressed by the operator when the power to the work machine 1 is off, and a switch that outputs a stop request signal when pressed by the operator when the power to the work machine 1 is on. Alternatively, for example, the power switch 143 may be a key switch that is operated by turning a key from the off position to the on position and then to the start position. In this case, the power switch 143 outputs a start request signal when the key is turned from the off position to the start position, and outputs a stop request signal when the key is turned from the on position to the off position. Furthermore, for example, the power switch 143 may be a portable operating device carried by an operator, and when the operator operates the portable operating device, wireless communication is established between the portable operating device and the main control device 145, and a start request signal and a stop request signal are output on the condition that communication is established. The portable operating device may be, for example, a remote control key with an embedded electronic chip, or a portable computer device such as a smartphone or a personal digital assistant. Furthermore, the power switch 143 may be configured to be located in a remote location and to output the start request signal and the stop request signal by remote operation, for example.

[0017] The main control device 145 controls the work machine 1. The main control device 145 receives operation signals from the operation device 142. Based on the operation signals from the operation device 142, the main control device 145 controls the travel of the traveling body 110, the drive of the work machine 130, and the swing operation of the swing body 120.

[0018] The main control device 145 acquires a signal from the power switch 143. When the main control device 145 acquires a start request signal from the power switch 143, it starts the work machine 1. When the main control device 145 acquires a start request signal from the power switch 143, it performs start-up processing for each fuel cell module. When the main control device acquires a stop request signal from the power switch 143, it stops the work machine 1. When the main control device 145 acquires a stop request signal from the power switch 143, it performs stop processing for each fuel cell module.

[0019] The fuel cell system 20, which will be described later, is disposed in the machinery room 150. The machinery room 150 is disposed, for example, behind the operator's cab 140. The machinery room 150 forms a space in which the fuel cell system 20 is disposed.

[0020] 2 is a schematic block diagram showing the configuration of a work machine 1 according to the first embodiment. The work machine 1 is equipped with a fuel cell system 20 and a drive system 30. The fuel cell system 20 generates electric power for driving the work machine 1. The fuel cell system 20 generates electric power for driving the drive system 30. The electric power generated by the fuel cell system 20 is output to the drive system 30 via a bus line B. The drive system 30 uses the electric power generated by the fuel cell system 20 to cause the traveling body 110 to travel, drive the work implement 130, and perform the swing operation of the swing body 120.

[0021] The fuel cell system 20 includes a plurality of fuel cell modules 21 and a power storage device module 22 connected in parallel to a bus B.

[0022] Each fuel cell module 21 includes a fuel cell 211, a power converter 212, auxiliary equipment 213, and a fuel cell control device 214. The fuel cell 211 generates electricity by causing an electrochemical reaction between hydrogen and oxygen. The power converter 212 is, for example, a DC-DC converter, and is configured to be able to control the output of the power generated by the fuel cell 211. The power converter 212 converts the power generated by the fuel cell 211 and supplies it to the bus B. The auxiliary equipment 213 is a device for operating the fuel cell 211. The fuel cell module 21 includes, as the auxiliary equipment 213, a hydrogen pump for supplying hydrogen gas to the fuel cell 211, an air compressor for generating compressed air to be supplied to the fuel cell 211, and a water pump for supplying cooling water to cool the fuel cell 211. The fuel cell control device 214 controls the fuel cell module 21 in accordance with commands from the main control device 145. The fuel cell control device 214 monitors the status of the fuel cell 211 and outputs data indicating the status of the fuel cell 211 to the main control device 145.

[0023] The power storage device module 22 includes a power storage device 221 and a power converter 222. The power storage device 221 is configured to be able to charge or discharge surplus power from the bus B. The power converter 222 is, for example, a DC-DC converter, and controls the input and output of power to and from the power storage device 221. The power converter 222 outputs power from the power storage device 221 in accordance with a command from the main control device 145. The power storage device 221 is, for example, a capacitor.

[0024] The drive system 30 includes a hydraulic drive module 31 and a slewing module 32 .

[0025] The hydraulic drive module 31 includes an inverter 311, an electric pump motor 312, a hydraulic pump 313, and a hydraulic actuator 314. The inverter 311 converts DC current from the bus B into three-phase AC current and supplies it to the electric pump motor 312. The electric pump motor 312 generates power for driving the work machine 130 and the traveling vehicle 110. The electric pump motor 312 is rotated by the supplied three-phase AC current and drives the hydraulic pump 313. The hydraulic pump 313 discharges hydraulic oil to be supplied to the hydraulic actuator 314. The hydraulic oil discharged from the hydraulic pump 313 is supplied to the hydraulic actuator 314 via a control valve (not shown). The hydraulic actuator 314 is driven by the supplied hydraulic oil. The hydraulic actuator 314 includes a boom cylinder 131C, an arm cylinder 132C, an attachment cylinder 133C, and a traveling motor 134. The rotational force generated by the traveling motor 134 is transmitted to the traveling body 110. The electric pump motor 312 is an example of a load.

[0026] The swing module 32 includes an inverter 321 and an electric swing motor 322. The inverter 321 converts DC current from the bus B into three-phase AC current and supplies it to the electric swing motor 322. The electric swing motor 322 generates power for swinging the swing unit 120. The electric swing motor 322 rotates by the supplied three-phase AC current, causing the swing unit 120 to swing relative to the traveling unit 110.

[0027] The work machine 1 is equipped with a control system 14 for controlling the work machine 1. Figure 3 is a schematic block diagram showing the configuration of the control system 14 equipped in the work machine 1 according to the first embodiment. The control system 14 is equipped with a main control device 145, an operation device 142, and a power switch 143. The main control device 145 is equipped with a receiving unit 401, a fuel cell control unit 402, a stop target determination unit 403, a stop target storage unit 404, a drive control unit 405, and a standby time determination unit 406.

[0028] (Explanation of the configuration within the main control device) The receiving unit 401 receives operation signals for the work machine 1 from the operating device 142, and receives stop commands for the work machine 1 from the power switch 143. The fuel cell control unit 402 outputs control commands for controlling the fuel cell module 21. Control commands for the fuel cell module 21 include power control commands, idling commands, stop commands, etc. The stop target determination unit 403 determines which of the multiple fuel cell modules 21 to stop. The stop target memory unit 404 temporarily stores identification information for the fuel cell module 21 determined as the stop target by the stop target determination unit 403. The drive control unit 405 outputs control commands for controlling the drive system 30. The drive control unit 405 outputs control commands for the rotation speeds of the electric pump motor and the electric swing motor. The standby time determination unit 406 determines the standby time for issuing a stop command for the fuel cell module 21.

[0029] <<Control When Stopping the Work Machine 1>> Figure 4 is a flowchart showing the process for stopping the work machine 1 according to the first embodiment. When the operator turns off the power switch 143, the power switch 143 outputs a command signal to stop the work machine 1 to the receiving unit 401 of the main control device 145. When a command signal to stop the work machine 1 is input from the power switch 143 to the receiving unit 401 of the main control device 145 by operation of the operator, the main control device 145 stops the fuel cell system 20 in the following procedure.

[0030] First, the fuel cell control unit 402 outputs a power control command to set the output power to zero to the fuel cell control devices 214 of all fuel cell modules 21 (step S1). As a result, power is no longer supplied from all fuel cell modules 21. At this time, the fuel cell control device 214 controls the fuel cells 211 to generate the power necessary to maintain operation of the auxiliary devices 213. In other words, the power control command to set the output power to zero may be an idling command to put the fuel cell module 21 into an idling state.

[0031] Next, the stop target determination unit 403 determines the number of fuel cell modules 21 to be used for the operation of the electric pump motor 312 (step S2). The allowable range (upper and lower limits) of power consumption of the electric pump motor 312 and the power generated during the stop process of the fuel cell modules 21 can be calculated based on design values. The stop target determination unit 403 according to the first embodiment calculates the number of fuel cell modules 21 required to generate the required power based on the allowable range of power consumption of the electric pump motor 312 and the power generated during the stop process of the fuel cell modules. The number of fuel cell modules to be used for the operation of the electric pump motor is, for example, a number such that the power generated during the stop process of the fuel cell modules 21 falls below the allowable range of power consumption of the electric pump motor. Note that if the power generated during the stop process of the fuel cell modules 21 varies depending on factors such as the outside temperature or the operating time, the required number may be calculated using the average value of the power generated during the stop process. Furthermore, according to other embodiments, the main control unit 145 may correct the power generated by the fuel cell modules 21 based on the outside temperature or the operating time. Furthermore, the main control device 145 may change the power consumed by the electric pump motor 312 depending on the state of the inverter 311 and the electric pump motor 312. For example, if the inverter 311 or the electric pump motor 312 is overheating, the main control device 145 may determine the power consumed by the electric pump motor 312 to be lower than the upper limit of power consumption. In other embodiments, the number of fuel cell modules 21 used to operate the electric pump motor 312 may be determined in advance. The power generated by stop control of the fuel cell modules 21 varies depending on the outside temperature, operating time, etc., but if this variation is sufficiently small compared to the allowable range of power consumption of the electric pump motor 312, there is no problem in calculating the required number of units using the average value of power generated by stop control. Power within the allowable range of power consumption is called allowable power.

[0032] Next, the shutdown target determination unit 403 identifies the amount of power to be supplied to the bus B by the shutdown process of the fuel cell modules 21 (step S3). The amount of power to be supplied to the bus B can be calculated, for example, by multiplying the average value of power generation during the shutdown process by the number of units identified in step S2. Note that if the number of fuel cell modules 21 used to operate the electric pump motor 312 is predetermined, the amount of power to be supplied to the bus B by the shutdown process may also be identified in advance.

[0033] Next, the drive control unit 405 outputs a drive instruction to drive the electric pump motor 312 with the power specified by the stop target determination unit 403 in step S3 (step S4). At this time, when the power stored in the power storage device 221 is discharged, the electric pump motor 312 consumes the power discharged from the power storage device 221. Variations in the power generated by the fuel cell module 21 may be absorbed by charging and discharging the power storage device module 22, or by controlling the output of the inverter 311. Note that when the work machine 1 is stopped, the actuators are not operated, so the control valves provided between the hydraulic pump 313 and the hydraulic actuators 314 are switched to the unload position. Therefore, the hydraulic oil supplied from the hydraulic pump 313 by the rotation of the electric pump motor 312 is returned to the tank by the unload circuit of the control valve.

[0034] Next, the shutdown target determination unit 403 determines a set of fuel cell modules 21 to be shut down from the multiple fuel cell modules 21 (step S5). The number of fuel cell modules 21 constituting one set is equal to the number determined by the shutdown target determination unit 403 in step S2. If the number determined in step S2 is one, the set of fuel cell modules 21 is a single fuel cell module. The set of fuel cell modules 21 includes at least one fuel cell module. If the number determined in step S2 is more than one, the set of fuel cell modules 21 is a fuel cell module group. The shutdown target determination unit 403 records identification information of the fuel cell modules 21 determined to be shut down in step S5 in the shutdown target storage unit 404. Note that in another embodiment, the order in which the multiple fuel cell modules 21 are shut down may be predetermined. In this case, the shutdown target determination unit 403 does not need to record identification information of the fuel cell modules 21 determined to be shut down in the shutdown target storage unit 404.

[0035] Next, the fuel cell control unit 402 outputs a shutdown command to the fuel cell control device 214 of each fuel cell module 21 associated with the group determined by the shutdown target determination unit in step S5 (step S6). The group of fuel cell modules 21 to be shut down initially is a first fuel cell module or group of fuel cell modules. The first fuel cell module or group of fuel cell modules to be shut down initially is also referred to as a first group of fuel cell modules. The first group of fuel cell modules includes at least one fuel cell module.

[0036] When the fuel cell control device 214 of the fuel cell module 21 to be shut down receives the shutdown command, it executes a predetermined shutdown process (step S7). For example, the fuel cell control device 214 executes the shutdown process in the following procedure. The fuel cell control device 214 stops the hydrogen pump, which is the auxiliary device 213, and uses the air compressor to compress air into the fuel cell 211, causing the hydrogen remaining in the fuel cell module 21 to react with the oxygen in the air. The fuel cell control device 214 controls the power converter 212 to supply the power generated by the fuel cell 211 to the bus B. The fuel cell control device 214 monitors the power generated by the fuel cell 211 and continues power generation until the power generation falls below a predetermined value. When the power generation falls below the predetermined value, the fuel cell control device 214 shuts down all of the auxiliary devices 213 and the power converter 212. This allows the fuel cell control device 214 to completely react the remaining hydrogen in the fuel cell 211. Once all of the remaining hydrogen has reacted, the fuel cell 211 shuts down. After stopping all of the auxiliaries 213 and the power converter 212, the fuel cell control device 214 outputs a shutdown processing end signal to the main control device 145. After all of the auxiliaries 213 and the power converter 212 have stopped, the main control device 145 receives the shutdown processing end signal from the fuel cell control device 214. This allows the main control device 145 to recognize that the shutdown processing has been completed after all of the auxiliaries 213 and the power converter 212 have stopped.

[0037] The fuel cell control unit 402 detects the start of the shutdown process of the fuel cell module 21, which is executed in step S7 (step S8). Note that a fuel cell control unit 402 according to another embodiment may regard the output of the shutdown command as the start of the shutdown process, and may not need to detect the start of the shutdown process.

[0038] Next, the standby time determination unit 406 determines the standby time for shutting down the next set of fuel cell modules 21 (step S9). The main control device 145 waits for the standby time determined by the standby time determination unit 406 (step S10). For example, the standby time determined by the standby time determination unit 406 may be the time required for the reaction of hydrogen and oxygen remaining in the fuel cell modules 21 to complete. The time required for the reaction of hydrogen and oxygen remaining in the fuel cell modules 21 varies depending on the outside temperature and the operating time, but this variation is small. Therefore, the average time required for the reaction of hydrogen and oxygen remaining in the fuel cell modules 21 can be calculated in advance as the time required for the reaction of hydrogen and oxygen remaining in the fuel cell modules 21. Alternatively, the standby time determination unit 406 may monitor changes in the output voltage of the fuel cell modules 21, predict the time required for the reaction of hydrogen and oxygen remaining in the fuel cell modules 21 to complete, and determine the predicted time as the standby time.

[0039] Next, the shutdown target determination unit 403 determines whether there are any fuel cell modules 21 for which shutdown processing has not been initiated (step S11). For example, if there is identification information of a fuel cell module 21 that is not recorded in the shutdown target storage unit 404, the shutdown target determination unit 403 determines that there are any fuel cell modules 21 for which shutdown processing has not been initiated. If there are any fuel cell modules 21 for which shutdown processing has not been initiated (step S11: YES), the main control unit 145 returns to step S5 and determines the next set of fuel cell modules 21 for which shutdown processing will be initiated. The next set of fuel cell modules 21 for which shutdown processing will be initiated is selected from among the fuel cell modules 21 for which shutdown processing has not been initiated. The set of fuel cell modules 21 to be shut down the second time is the second fuel cell module or fuel cell module group. In other words, if the set of fuel cell modules 21 to be shut down the Nth time is the first fuel cell module or fuel cell module group, the set of fuel cell modules 21 to be shut down the N+1th time will be the second fuel cell module or fuel cell module group. The second fuel cell module or group of fuel cell modules selected from the fuel cell modules 21 for which shutdown processing has not yet begun and to be the next target for shutdown is also referred to as a second set of fuel cell modules. The second set of fuel cell modules includes at least one fuel cell module for which shutdown processing has not yet begun.

[0040] After waiting for the waiting time in step S10, the main control device 145 performs the shutdown process for the next group without waiting for the actual completion of the shutdown process. For example, the main control device 145 performs the shutdown process for the next group before recognizing that the shutdown process for the group of fuel cell modules to be shut down has been completed. This allows the main control device 145 to prevent a period of no power generation from occurring between the end of the shutdown process for the previous group and the start of the shutdown process for the next group, or to minimize this period of no power generation.

[0041] On the other hand, if there is no fuel cell module 21 that has not started the shutdown process (step S11: NO), the drive control unit 405 outputs an instruction to stop control of the electric pump motor 312 by the inverter 311 (step S12), and ends the shutdown process of the work machine 1.

[0042] <<Functions and Effects>> As described above, the main controller 145 according to the first embodiment functions as follows. The main controller 145 initiates shutdown processing for a first fuel cell module or fuel cell module group, which is part of the plurality of fuel cell modules 21. Next, after initiating shutdown processing for the first fuel cell module or fuel cell module group, the main controller 145 initiates shutdown processing for a second fuel cell module or fuel cell module group. The main controller 145 causes the electric pump motor 312, which is a load, to consume the power generated by the shutdown processing for the first fuel cell module or fuel cell module group and the power generated by the shutdown processing for the second fuel cell module or fuel cell module group. The main controller 145 does not shut down all fuel cell modules 21 simultaneously, but shuts down each set of fuel cell modules 21, each consisting of at least one fuel cell module 21, at different times. The power generated by the fuel cell modules during shutdown processing is smaller when each set of fuel cell modules 21 is shut down at different times than when all fuel cell modules 21 are shut down simultaneously. In other words, the main controller 145 can appropriately consume the generated power.

[0043] Furthermore, the power generated by the shutdown process for the first fuel cell module or fuel cell module group, and the power generated by the shutdown process for the second fuel cell module or fuel cell module group, are both lower than the upper limit of power consumption of the electric pump motor 312. This allows the main control device 145 to appropriately consume the generated power without the surplus power generated by the shutdown process exceeding the upper limit of power consumption of the load.

[0044] Furthermore, the work machine 1 does not require a large retarder because the load can consume the generated power produced by the shutdown process of the fuel cell module 21. Therefore, the work machine 1 may be equipped with a small retarder, or may not be equipped with a retarder at all.

[0045] The main control device 145 controls the timing of the shutdown process for the fuel cell module 21 so that the generated power supplied to the bus B does not become zero, but this is not limited to this. For example, the main control device 145 according to another embodiment may start the shutdown process for the second fuel cell module or fuel cell module group after recognizing that the shutdown process for the first fuel cell module or fuel cell module group has been completed. Specifically, the main control device 145 may recognize that the fuel cell 211 has been shut down by receiving a notification from the fuel cell control device 214 that the shutdown process has been completed, or may monitor changes in the output voltage of the fuel cell module 21 and determine that the fuel cell 211 has been shut down when the output voltage no longer changes.

[0046] Other Embodiments Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design modifications and the like are possible. For example, the main control device 145 according to the embodiment described above may be configured by a single computer, or the configuration of the main control device 145 may be divided into multiple computers that function as the main control device 145 by working together. In this case, some of the computers that make up the main control device 145 may be installed inside the work machine 1, and other computers may be provided external to the work machine 1. The main control device 145 according to the embodiment described above may also have the functionality of the fuel cell control device 214. In this case, each fuel cell module 21 does not need to be equipped with the fuel cell control device 214, and the power converters 212 and auxiliaries 213 of each fuel cell module 21 may operate based on command signals from the main control device 145. The main control device 145 may also function as a monitoring device, having the function of monitoring the status of the fuel cells 211.

[0047] Furthermore, although the work machine 1 according to the embodiment described above is a hydraulic excavator, this is not limiting. For example, the work machine 1 according to other embodiments may be another work machine such as a wheel loader or a dump truck.

[0048] Furthermore, in the work machine 1 according to the embodiment described above, the electric swing motor 322 of the swing module 32 swings the swing unit 120, but this is not limited to this. For example, a work machine 1 according to another embodiment may not be equipped with a swing module 32, and the hydraulic swing motor, which is the hydraulic actuator 314, may swing the swing unit 120.

[0049] Furthermore, in the work machine 1 according to the embodiment described above, the electric pump motor 312 drives the hydraulic actuator 314 to drive the work implement 130 and the traveling body 110, but this is not limited to this. For example, the work machine 1 may be equipped with an electric actuator instead of the electric pump motor 312 and the hydraulic actuator 314, and the work implement 130 may be driven and the traveling body 110 may be traveled by the electric actuator. Also, for example, a work machine 1 according to another embodiment may be equipped with an electric travel motor instead of the travel motor 134, which is the hydraulic actuator 314, and the work implement 130 may be driven by hydraulic pressure and the traveling body may be traveled by the electric motor.

[0050] The main control device 145 according to the embodiment described above causes the electric pump motor 312 to consume the power stored in the power storage device 221, but this is not limited to this. For example, the main control device 145 according to other embodiments may cause the electric swing motor 322 or an auxiliary device (such as an air compressor or fan) not shown to consume power. In this case, the main control device 145 may separate the motor from the machine driven by the motor using a clutch not shown so that the rotational force generated by the motor is not transmitted to the machine. Furthermore, for example, the work machine 1 according to other embodiments may be equipped with a retarder, and the retarder may consume power. Furthermore, for example, the work machine 1 according to other embodiments may cause an electric actuator not shown to consume power.

[0051] Furthermore, in the above-described embodiment, a capacitor is given as an example of the power storage device 221, but this is not limiting. For example, the power storage device 221 of a work machine 1 according to other embodiments may be a battery. Note that the main control device 145 according to other embodiments may charge the power storage device 221 with part of the power generated when the fuel cell modules 21 are stopped. In this case, the main control device 145 determines the number of fuel cell modules 21 to be stopped so that the instantaneous power generated when the fuel cell modules 21 are stopped is smaller than the sum of the upper limit of the allowable power when the power storage device 221 is charging and the upper limit of the power consumption of the load.

[0052] Furthermore, although the main control device 145 according to the embodiment described above randomly determines the order in which the shutdown process is performed on the multiple fuel cell modules 21, this is not limiting. For example, the main control device 145 according to other embodiments may determine the order in which the shutdown process is performed based on the degree of deterioration of the fuel cell modules 21. In this case, the main control device 145 shuts down the fuel cell modules 21 that are more deteriorated first, and shuts down the fuel cell modules 21 that are less deteriorated later. Furthermore, the main control device 145 according to other embodiments may determine the order in which the shutdown process is performed so as to rotate the multiple fuel cell modules 21. For example, in a work machine 1 having four fuel cell modules A-D, if the order in which the previous shutdown process was performed was A, B, C, D, the order in which the next shutdown process is performed may be determined to be D, B, C, A. Furthermore, the main control device 145 according to other embodiments may randomly determine the order in which the shutdown process is performed when the multiple fuel cell modules 21 have been stopped a predetermined number of times. For example, in a work machine 1 having four fuel cell modules A-D, if the fuel cell modules are stopped a predetermined number of times in the order of A, B, C, and D, the order in which the next shutdown process is performed may be determined to be B, C, D, and A.

[0053] <Computer Configuration> Fig. 5 is a schematic block diagram showing the configuration of a computer according to an embodiment. The computer 90 includes a processor 91, a main memory 92, a storage 93, and an interface 94. The main control device 145 and the fuel cell control device 214 described above are implemented in the computer 90. The operations of the above-described processing units are stored in the storage 93 in the form of a program. The processor 91 reads the program from the storage 93, loads it into the main memory 92, and executes the above-described processing in accordance with the program. The processor 91 also allocates storage areas in the main memory 92 corresponding to the above-described 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.

[0054] The program may be for implementing some of the functions to be performed by the computer 90. For example, the program may be implemented in combination with other programs already stored in storage or in combination with other programs implemented in other devices. In another embodiment, the computer 90 may include a custom large-scale integrated circuit (LSI) such as a programmable logic device (PLD) in addition to or instead of the above configuration. Examples of PLDs include programmable array logic (PAL), generic array logic (GAL), complex programmable logic device (CPLD), and field programmable gate array (FPGA). In this case, some or all of the functions implemented by the processor 91 may be implemented 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.

[0055] 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.

[0056] The program may also be a program for realizing part 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.

[0057] According to the above aspect, the work machine can appropriately consume the generated power that is produced by the shutdown process of the multiple fuel cell modules.

[0058] 1...Work machine 110...Traveling body 120...Swinging body 130...Working machine 131...Boom 131C...Boom cylinder 132...Arm 132C...Arm cylinder 133...Attachment 133C...Attachment cylinder 134...Travel motor 140...Driver's cab 142...Operating device 143...Power switch 145...Main control device 150...Machine room 20...Fuel cell system 21...Fuel cell module 211...Fuel cell 212...Power converter 213...Auxiliary device 214...Fuel cell control device 22...Electricity storage device module 221...Electricity storage device 222...Power converter 30...Drive system 31...Hydraulic drive module 311...Inverter 312...Electric pump motor 313...Hydraulic pump 314...Hydraulic actuator 32...Swing module 321...Inverter 322...Electric swing motor 401: Receiving unit 402: Fuel cell control unit 403: Stop target determining unit 404: Stop target storage unit 405: Drive control unit 406: Standby time determining unit 90: Computer 91: Processor 92: Main memory 93: Storage 94: Interface B: Bus

Claims

1. A work machine equipped with a work implement, comprising: a plurality of fuel cell modules; and a control device, wherein when the control device receives a stop request signal to stop the work machine, it starts a stop process for a first set of fuel cell modules that are part of the plurality of fuel cell modules; and after the start of the stop process for the first set of fuel cell modules, it starts a stop process for a second set of fuel cell modules that are part of the plurality of fuel cell modules; and supplies the generated power generated by the stop process for the first set of fuel cell modules and the generated power generated by the stop process for the second set of fuel cell modules to a load or a power storage device.

2. A work machine according to claim 1, wherein the control device waits for a waiting time after starting the shutdown process for the first set of fuel cell modules before starting the shutdown process for the second set of fuel cell modules.

3. A work machine according to claim 2, wherein the standby time is a time period during which the power generated by the plurality of fuel cell modules does not become zero.

4. The work machine according to claim 3, wherein the standby time is determined by calculating the time required for the reaction of hydrogen and oxygen remaining in the plurality of fuel cell modules to be completed.

5. A work machine according to claim 4, wherein the standby time is determined based on detected values ​​of output voltages of the plurality of fuel cell modules.

6. A work machine according to claim 1, wherein the generated power generated by the shutdown process of the first fuel cell module set and the generated power generated by the shutdown process of the second fuel cell module set are both lower than the upper limit of the allowable power of the load or the power storage device.

7. The work machine according to claim 1, wherein the control device outputs a command to set the output power of the plurality of fuel cell modules to zero before starting the shutdown process for the first set of fuel cell modules.

8. A work machine as described in claim 1 or claim 6, wherein the work machine is provided with a hydraulic pump as the load that pressurizes hydraulic oil to operate the work equipment, and the control device operates the hydraulic pump to consume the generated power generated by the shutdown process of the first fuel cell module set and the generated power generated by the shutdown process of the second fuel cell module set.

9. The work machine according to claim 6, wherein the control device determines the number of fuel cell modules constituting the first set of fuel cell modules and the second set of fuel cell modules based on an upper limit of the allowable power of the load or the power storage device.

10. A work machine equipped with a work implement, comprising: a plurality of fuel cell modules; and a control device, wherein the plurality of fuel cell modules include a plurality of sets of fuel cell modules, each set consisting of at least one of the fuel cell modules, and the control device stops each of the sets of fuel cell modules at different times.

11. A method relating to a work machine having a work implement and a plurality of fuel cell modules supported on a vehicle body, comprising the steps of: initiating shutdown processing for a first set of fuel cell modules that are part of the plurality of fuel cell modules; after initiating the shutdown processing for the first set of fuel cell modules, initiating shutdown processing for a second set of fuel cell modules that are part of the plurality of fuel cell modules; and supplying the generated power generated by the shutdown processing for the first set of fuel cell modules and the generated power generated by the shutdown processing for the second set of fuel cell modules to a load or a power storage device.

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