Work machine

Abstract

To provide a work machine that can make an operator certainly aware of a purge process going on at stopping the operation of the work machine.SOLUTION: A work machine comprises: an operator cab 8 arranged on one side in the right-left direction and in front of an own machine; a fuel cell 21 that generates electric power to be supplied to an electric motor 23 to be a power source; and a fuel cell cooling system 70 that cools the fuel cell 21. The fuel cell cooling system 70 is arranged on one side in the right-left direction of the own machine and behind the operator cab 8.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a work machine, and more particularly to a work machine that is equipped with a fuel cell and is driven by electric power generated by the fuel cell. [Background technology]

[0002] Recently, from an environmental consideration perspective, work machines equipped with fuel cells are being used. Generally, it is necessary to keep the inside of a fuel cell humidified in order to promote the ionization of hydrogen. In addition, since water is produced during power generation, moisture may remain in the drainage path. However, this residual moisture may freeze in low-temperature environments such as below freezing, so it is necessary to remove the residual moisture when the system is shut down.

[0003] Patent Document 1 discloses a construction machine. This construction machine is provided with a first swivel unit that is provided between a main body and a traveling device that travels on the main body and that rotates the main body, a working device connected to the main body, and a storage unit that can be rotated by a second swivel unit different from the first swivel unit. The storage unit houses a hydrogen tank that stores hydrogen and a fuel cell that generates electricity using hydrogen supplied from the hydrogen tank, and a hydraulic device that drives the working device is disposed in the main body. Patent Document 2 discloses a power supply system that outputs electric power. The power supply system includes a fuel cell including a proton-conductive electrolyte layer and a hydrogen-permeable metal layer bonded to the electrolyte layer, and a fuel gas supply unit that supplies a hydrogen-containing fuel gas to the anode side of the fuel cell. The power supply system also includes a purge gas supply unit that supplies a hydrogen-free purge gas to the anode side of the fuel cell, and a purge control unit that drives the purge gas supply unit to replace the fuel gas in the fuel cell with the purge gas after power generation in the fuel cell is stopped. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-180565 A [Patent Document 2] International Publication No. 2005 / 043663 Summary of the Invention [Problem to be solved by the invention]

[0005] In a work machine equipped with a fuel cell, when the fuel cell is stopped, a purging process must be performed to remove residual moisture inside the fuel cell and in the drainage path to prevent freezing in a low-temperature environment. The purging process is performed when the operation of the work machine is terminated, i.e., after the key is turned off, but is also performed as necessary as part of the shutdown process. Meanwhile, in a work machine, there are situations in which the power supply line from the battery must be manually cut off to cut off the system power supply source for the purposes of preventing battery consumption, preventing theft, improving safety during vehicle maintenance, etc. However, if the driver does not realize that the purging process is being performed after the work is completed and turns off the system power supply, the purging process may be interrupted, and moisture may remain inside the fuel cell or in the exhaust path. In this case, there is a risk that the fuel cell will freeze in a low-temperature environment and subsequently lose its start-up capability. An object of the present invention is to provide a work machine that can more reliably make the operator aware that a purging process is being executed when operation of the work machine is terminated. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a work machine comprising a cab provided on one side of the machine in the left-right direction and at the front, a fuel cell that generates electricity to be supplied to an electric motor that serves as a power source, and a first cooling device that cools the fuel cell, the first cooling device being disposed on one side of the machine in the left-right direction and behind the cab.In this case, a work machine can be provided that can more reliably make the operator aware that purging processing is being performed when operation of the work machine is terminated.

[0007] Here, the first cooling device can be arranged adjacent to the driver's cab, which makes it easier for the driver to recognize the operating sounds of the electric fan and the electric water pump. The first cooling device has a first heat exchanger and a plurality of first cooling fans arranged facing the first heat exchanger to blow cooling air to the first heat exchanger, and the plurality of first cooling fans can be arranged along the side of the device. In this case, it becomes easier to take in outside air. Even if there are a plurality of first cooling fans, each of the first cooling fans can take in outside air. Furthermore, a counterweight is provided at the rear end of the vehicle, the first cooling device has a first heat exchanger and a first cooling fan arranged facing the first heat exchanger to send cooling air to the first heat exchanger, and the first cooling fan can be arranged between the cab and the counterweight in the fore-and-aft direction of the vehicle. In this case, the operating sound of the first cooling fan can be easily heard by the driver. The vehicle further includes a second cooling device for cooling the electric motor, the first cooling device having a first heat exchanger and a first cooling fan arranged opposite the first heat exchanger to send cooling air to the first heat exchanger, the second cooling device having a second heat exchanger and a second cooling fan arranged opposite the second heat exchanger to send cooling air to the second heat exchanger, the first cooling fan being arranged on one side of the vehicle in the left-right direction and taking in outside air from one side of the vehicle in the left-right direction, and the second cooling fan being arranged on the other side of the vehicle in the left-right direction and facing the first cooling fan and taking in outside air from the other side of the vehicle in the left-right direction. In this case, recirculation that deteriorates cooling performance can be suppressed. A counterweight is provided at the rear end of the device, and the counterweight can be provided with an opening for discharging the outside air taken in by the first cooling fan and the second cooling fan. In this case, it becomes easier to discharge hot air from the rear of the device. Furthermore, when the fuel cell is purged, the first cooling fan can be driven by the power generated by the fuel cell. In this case, the heat emitted by the fuel cell can be used to expel moisture remaining inside the fuel cell and in the connecting pipes to the outside of the vehicle. Effect of the Invention

[0008] According to the present invention, a work machine can be provided that can more reliably make the operator aware that purging processing is being performed when operation of the work machine is terminated. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing the overall configuration of a work machine in an embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing a system configuration of a hydraulic excavator. [Diagram 3] 1 is an explanatory diagram of a fuel cell cooling system for a work machine according to an embodiment of the present invention; [Figure 4] FIG. 2 is a top view of a rotating body of the hydraulic excavator according to the embodiment. [Diagram 5] FIG. 2 is a left side view of a rotating body of the hydraulic excavator according to the embodiment. [Figure 6] FIG. 2 is a right side view of a rotating body of the hydraulic excavator according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0011] <Explanation of the overall configuration of the work machine> FIG. 1 is a diagram showing the overall configuration of a work machine in this embodiment. The working machine shown in the figure is a hydraulic excavator 100. However, the working machine is not limited to this, and may be a construction machine such as a wheel loader, a bulldozer, a crane truck, etc. Furthermore, the working machine may be an agricultural machine such as a felling machine, a timber processing machine, a tractor, a forest work vehicle, a timber collector, etc.

[0012] The hydraulic excavator 100 comprises a running body 3 having a pair of left and right tracks 1, 2, a rotating body 4 mounted on the running body 3 and serving as an example of the excavator's own machine, a boom 5 rotatably connected to one end of the rotating body 4 with a pin, an arm 6 rotatably connected to one end of the boom 5 with a pin, and a bucket 7 rotatably connected to one end of the arm 6 with a pin. Furthermore, the hydraulic excavator 100 is equipped with a driver's cab 8 located on the rotating body 4 at either the left or right side of the machine and at the front, a machine room 9 housing an electric motor 23 and a main pump 31 (see FIG. 2) described below, a counterweight 10 located at the rear end of the machine, travel motors 11, 12 that drive the tracks 1, 2, a pair of left and right boom cylinders 14, 15 that drive the boom 5, an arm cylinder 16 that drives the arm 6, and a bucket cylinder 17 that drives the bucket 7. At this time, the main working arm corresponds to the boom 5, arm 6 and bucket 7, and the posture of these working arm mechanisms is determined by the extension and contraction of the boom cylinders 14, 15, arm cylinder 16 and bucket cylinder 17, respectively.

[0013] FIG. 2 is a diagram showing the system configuration of the hydraulic excavator 100. Since the traveling motors 11, 12 and the swing motor 13 all have the same configuration as hydraulic motors, the following description will take the swing motor 13 as an example, and the description of the traveling motors 11, 12 will be omitted. Similarly, since the boom cylinders 14, 15, the arm cylinder 16, and the bucket cylinder 17 all have the same configuration as hydraulic cylinders, the following description will take the arm cylinder 16 as an example, and the description of the boom cylinders 14, 15, and the bucket cylinder 17 will be omitted. Therefore, Fig. 2 shows only the hydraulic circuit configuration related to the arm cylinder 16 and the swing motor 13, and does not show the other hydraulic actuators.

[0014] The hydraulic excavator 100 has a system configuration including an electric power circuit 20 that operates the electric equipment, a hydraulic circuit 30 that generates hydraulic pressure, an operation system 40 that performs operations to control the operation of the electric power circuit 20 and the hydraulic circuit 30, a hydrogen tank 50 that stores hydrogen, a low-voltage circuit 60 that is a low-voltage electric power circuit, and a fuel cell cooling system 70 that cools the fuel cell.

[0015] The hydraulic circuit 30 includes a main pump 31, a pilot pump 32, a hydraulic oil tank 33 for storing hydraulic oil, a rotation motor 13 for driving the rotating body 4, a first directional control valve 34 for controlling the flow of hydraulic oil related to the rotation motor 13, and a second directional control valve 35 for controlling the flow of hydraulic oil related to the arm cylinder 16. The main pump 31 is a variable displacement hydraulic pump driven by the electric motor 23. This main pump 31 draws hydraulic oil from a hydraulic oil tank 33, and supplies the hydraulic oil to the swing motor 13 and the arm cylinder 16 via a first directional control valve 34 and a second directional control valve 35. Note that in this embodiment, a variable displacement hydraulic pump is used for the main pump 31, but this is not limiting, and a fixed displacement hydraulic pump may also be used. The pilot pump 32 is a fixed displacement hydraulic pump driven by the electric motor 23. This pilot pump 32 draws hydraulic oil from a hydraulic oil tank 33, and supplies it to a pair of pressure receiving chambers 34A, 34B of the first directional control valve 34 and a pair of pressure receiving chambers 35A, 35B of the second directional control valve 35, respectively. The hydraulic circuit 30 further includes a main relief valve 36 that determines the upper limit of the discharge pressure of the main pump 31, a pilot relief valve 37 that determines the upper limit of the discharge pressure of the pilot pump 32, and an on-off valve 38 that opens and closes the pipeline between the second directional control valve and the hydraulic oil tank 33.

[0016] In the operator's cab 8, an operation system 40 is provided, which includes an operation mode selection switch 41, a motor control dial 42 for setting the rotation speed of the electric motor 23 described below, operation levers 43A, 43B, a vehicle controller 45, and the like. The operation levers 43A, 43B correspond to the respective swing motors 13 and arm cylinders 16, and may be, for example, electric levers that output an electric operation signal (lever signal Lv) according to the operation amount. The vehicle body controller 45 receives the lever signal Lv of the operation levers 43A, 43B, and outputs a command signal according to the lever signal Lv to the solenoid proportional valves 34a, 34b and the solenoid proportional valves 35a, 35b, thereby controlling the switching direction and stroke amount of the first directional control valve 34 and the second directional control valve 35. At the same time, the controller outputs a command signal according to the lever signal Lv, the pump discharge pressure sensor 31S, the electric motor rotation speed sensor (not shown), etc., to the regulator 31R of the main pump 31, thereby controlling the pump capacity (discharge flow rate). With this configuration, the operation levers 43A, 43B cause each hydraulic actuator to perform a desired operation.

[0017] The first directional control valve 34 is a center bypass type directional control valve, and has a first switching position 34L for rotating the swing motor 13 forward, a neutral position 34N for communicating the main pump 31 with the hydraulic oil tank 33 to return hydraulic oil directly to the hydraulic oil tank 33, and a second switching position 34R for rotating the swing motor 13 backward. The first directional control valve 34 is configured to be switched to any one of the first switching position 34L, the neutral position 34N, and the second switching position 34R by an internal spool stroking in response to pilot pressures acting on a pair of pressure receiving chambers 34A, 34B, respectively. This controls the flow rate and direction (flow) of hydraulic oil supplied from the main pump 31 to the swing motor 13.

[0018] The second directional control valve 35 is a center bypass type directional control valve similar to the first directional control valve 34, and has a first switching position 35L for retracting the rod 16C of the arm cylinder 16, a neutral position 35N for communicating the main pump 31 with the hydraulic oil tank 33 to return hydraulic oil directly to the hydraulic oil tank 33, and a second switching position 35R for extending the rod 16C of the arm cylinder 16. The second directional control valve 35 is configured to be switched to any one of the first switching position 35L, the neutral position 35N, and the second switching position 35R by the stroke of an internal spool in response to the pilot pressures acting on the pair of pressure receiving chambers 35A and 35B, respectively, similar to the first directional control valve 34. This controls the flow rate and direction (flow) of hydraulic oil supplied from the main pump 31 to the arm cylinder 16.

[0019] The on-off valve 38 is an electromagnetic proportional valve whose opening is adjusted in proportion to the magnitude of a command current, and whose opening area is adjusted in proportion to the magnitude of a command current from the vehicle body controller 45. Therefore, even when the valve is not in operation or the load on the hydraulic actuator is small, the pressure of the main pump 31 can be freely set.

[0020] The power circuit 20 includes a fuel cell 21, an inverter 22, a secondary battery 25, a boost converter 28, and a high-voltage DCDC converter 29, and is connected to an electric motor 23 and various electric accessories (not shown). The hydraulic excavator 100 operates by driving the main pump 31 with the electric motor 23. In other words, the electric motor 23 is a power source. In this case, the electric motor 23 is driven using electric power generated by the fuel cell 21 to which hydrogen is supplied from the hydrogen tank 50. In other words, the fuel cell 21 generates electric power to be supplied to the electric motor 23.

[0021] Since the output of the fuel cell 21 is controlled by voltage, voltage conversion is required between the fuel cell voltage and the system voltage (e.g., 650 V). However, the voltage is boosted by a boost converter 28 provided in the fuel cell 21 to correspond to the rated voltage of the electric motor 23. The inverter 22 converts the DC voltage (system voltage) boosted by the boost converter 28 into an AC voltage, and controls the rotation speed of the electric motor 23. The high-voltage DCDC converter 29 is a bidirectional voltage converter that steps down the system voltage to charge the secondary battery 25 or steps up the voltage of the secondary battery 25 to the system voltage and supplies it to the inverter 22. The secondary battery 25 can store electricity using surplus power generated by the fuel cell 21, and also functions as a power source that supplies power to loads including the electric motor 23. The secondary battery 25 may be any chargeable and dischargeable power storage device, and may be, for example, a lithium ion battery or a nickel-metal hydride battery. The secondary battery 25 is provided with a battery sensor (not shown) for detecting the operating state of the secondary battery 25, such as the voltage, current, and remaining capacity (SOC (State Of Charge)).

[0022] The vehicle body controller 45 is a higher-level controller that controls the entire system of the hydraulic excavator 100, and outputs appropriate command values ​​to the electromagnetic proportional valves 34a, 34b, 35a, 35b of the hydraulic circuit 30, the lower-level controllers (fuel cell controller 47, battery controller 46), the low-voltage DCDC converter 63, the inverter 22, etc. These controllers are connected to a low-voltage circuit 60 (e.g., 24 V) including a lead battery 61. A low-voltage DC-DC converter 63 is connected to the low-voltage circuit 60, and generates a stable low voltage using power from the power circuit 20. The lead battery 61 is connected to the low voltage circuit 60 via a disconnect switch 62, and is configured to be able to cut off the system power supply source for the purposes of preventing the lead battery from wearing out, preventing theft, improving safety during vehicle maintenance, etc. Furthermore, a key switch 64 is connected to the vehicle controller 45, and starts and stops the vehicle operations.

[0023] The hydrogen tank 50 stores hydrogen to be used in the fuel cell 21. The hydrogen tank 50 is a pressure-resistant container made of, for example, metal or resin. The hydrogen tank 50 may also include a compressor that adjusts the hydrogen to an appropriate pressure, a precooler that cools the hydrogen, a hydrogen valve that adjusts the flow rate of the hydrogen, and the like.

[0024] FIG. 3 is an explanatory diagram of a fuel cell cooling system 70 for a work machine according to this embodiment. The fuel cell cooling system 70 is an example of a first cooling device that cools the fuel cell 21. The fuel cell cooling system 70 includes a fuel cell cooling circuit 71 that is a circulation path for fuel cell cooling water, a fuel cell (FC) radiator 72 that is a heat exchanger, an electric fan 73a that cools the fuel cell cooling water in the fuel cell radiator 72, an electric water pump 74 that pumps out the fuel cell cooling water, a fuel cell ion exchanger 75 that removes ions from the fuel cell cooling water, and water temperature sensors 76, 77, and 78 that measure the temperature of the fuel cell cooling water. In this embodiment, the fuel cell radiator 72 is an example of a first heat exchanger, and the electric fan 73a is an example of a first cooling fan that is disposed opposite the first heat exchanger and blows cooling air to the first heat exchanger.

[0025] A fuel cell cooling circuit 71 is connected to the fuel cell 21, and fuel cell cooling water is circulated by an electric water pump 74. A fuel cell radiator 72 is provided in the circulation path, and an electric fan 73a cools the fuel cell cooling water. Furthermore, in order to maintain the insulation of the fuel cell cooling circuit 71, a fuel cell ion exchanger 75 prevents the ion concentration in the fuel cell cooling water from becoming high. The fuel cell cooling system 70 is controlled by the vehicle controller 45 based on sensor information from water temperature sensors 76, 77, and 78 provided in the circulation path and a temperature sensor (not shown) in the fuel cell 21. The water temperature sensor 76 measures the outlet temperature of the fuel cell cooling water that has cooled the fuel cell 21. The rotation speed of the electric fan 73a is mainly controlled based on the temperature measured by the water temperature sensor 76. This allows the amount of airflow to the fuel cell radiator 72 to be adjusted. The water temperature sensor 77 measures the outlet temperature of the fuel cell cooling water cooled by the fuel cell radiator 72. The temperature measured by the water temperature sensor 77 makes it possible to see the effect of the bypass flow path that does not pass through the fuel cell radiator 72 but passes through the fuel cell ion exchanger 75. The water temperature sensor 78 measures the inlet temperature of the fuel cell cooling water flowing into the fuel cell 21. The rotation speed of the electric water pump 74 is mainly controlled based on the temperature measured by the water temperature sensor 78. This makes it possible to adjust the amount of fuel cell cooling water circulating through the fuel cell cooling circuit 71.

[0026] Fig. 4 is a top view of the revolving body 4 of the hydraulic excavator 100 of this embodiment. Fig. 5 is a left side view of the revolving body 4 of the hydraulic excavator 100 of this embodiment. Fig. 6 is a right side view of the revolving body 4 of the hydraulic excavator 100 of this embodiment. In Figs. 4 to 6, covers are removed to allow components to be seen, for ease of explanation of this embodiment.

[0027] The rotating body 4 is provided with a fuel cell 21, an inverter 22 electrically connected to the fuel cell 21, and an electric motor 23. The electric motor 23 and a main pump 31 are mechanically linked, and hydraulic oil discharged from the main pump 31 is distributed to hydraulic actuators (the rotating motor 13, the arm cylinder 16, etc.) in response to the operation of the operator, thereby enabling the hydraulic excavator 100 to perform the desired operation. The rotating body 4 is further provided with a secondary battery 25, and the fuel cell 21, the inverter 22, and the secondary battery 25 are connected by high-voltage cables (not shown) to form a power circuit 20.

[0028] A hydrogen tank 50 filled with high-pressure hydrogen is installed at the rear of the rotating body 4 and in front of the counterweight 10. With this configuration, the counterweight 10 protects the hydrogen tank 50 against object impacts from behind. The hydrogen tank 50 and fuel cell 21 are connected by hydrogen piping (not shown), making it possible to supply hydrogen to the fuel cell 21.

[0029] An oil cooler 81, an electric equipment radiator 82, and an auxiliary equipment radiator 83 are installed on the right outer edge of the rotating body 4 behind the hydraulic oil tank 33. Meanwhile, a fuel cell radiator 72 for cooling the fuel cell 21 is installed on the left outer edge of the rotating body 4 behind the driver's cab 8. Here, the fuel cell radiator 72 is configured with three units as shown in FIG. 5 because high cooling performance is required, but the number is not limited as long as the cooling performance is satisfied. Also, six electric fans 73a for cooling the fuel cell cooling water in the fuel cell radiator 72 are provided as shown in FIG. 5, but the number is not limited as long as the cooling performance is similarly satisfied.

[0030] The oil cooler 81 is connected to the hydraulic circuit 30 including the main pump 31, hydraulic oil tank 33, etc., and cools the hydraulic oil. The electric equipment radiator 82 is connected to a high-voltage equipment cooling water circuit (not shown) for the inverter 22, electric motor 23, secondary battery 25, etc., and cools the cooling water circulating through them. The auxiliary equipment radiator 83 is connected to a cooling water circuit (not shown) for the turbocharger etc. built into the fuel cell 21, and cools the cooling water circulating through them. The oil cooler 81, the electric device radiator 82, and the auxiliary device radiator 83 are each provided with an electric fan 81F, an electric fan 73b, and an electric fan 73c, similar to the fuel cell radiator 72. As shown in Fig. 6, two electric fans 81F and two electric fans 73b are provided. Also, as shown in Fig. 6, one electric fan 73c is provided. The electrically-operated device radiator 82, the auxiliary device radiator 83, the coolant circuit, the electric fan 73b, and the electric fan 73c are an example of a second cooling device that cools the electric motor 23. Among these, the electrically-operated device radiator 82 and the auxiliary device radiator 83 are an example of a second heat exchanger. Furthermore, the electric fan 73b and the electric fan 73c provided therein are an example of a second cooling fan that is disposed facing the electrically-operated device radiator 82 and the auxiliary device radiator 83 and blows cooling air to the second heat exchanger.

[0031] Returning to Fig. 2, the operation of the system in this embodiment will be described. When the driver turns on the key switch 64 in the driver's cab 8, the vehicle body controller 45 is started. The vehicle body controller 45 starts up the inverter 22, the low-voltage DCDC converter 63, the battery controller 46, and the fuel cell controller 47, and further, the battery controller 46 starts up the secondary battery 25 and the high-voltage DCDC converter 29, while the fuel cell controller 47 starts up the fuel cell 21, the boost converter 28, and a hydrogen valve (not shown) connected to the hydrogen tank 50. The vehicle controller 45 starts power generation by the fuel cell 21, driving of the electric motor 23, control of the hydraulic circuit 30, etc. according to the settings of the work mode selection switch 41, the motor control dial 42, and the lever signal Lv of the operation levers 43A, 43B.

[0032] On the other hand, when the driver turns off the key switch 64 in the driver's cab 8, the vehicle body controller 45 stops the inverter 22, thereby stopping the electric motor 23. Next, the fuel cell controller 47 executes a purge process to discharge moisture remaining inside the fuel cell 21 and in the connecting piping to the outside of the vehicle.

[0033] The purging process requires the fuel cell to generate electricity, and not only the fuel system but also devices related to charging and consuming the generated electricity are operated. In detail, the fuel cell 21 generates electricity using the fuel cell 21, the hydrogen tank 50, the boost converter 28, and the fuel cell controller 47. At this time, the amount of air required for reacting hydrogen is intentionally reduced, and the heat exhausted from the fuel cell 21 is increased, so that moisture remaining inside the fuel cell 21 and in the connecting pipes is discharged to the outside of the vehicle. The generated electricity generated by the purging process can be charged into the secondary battery 25 via the power circuit 20, but since the fuel cell cooling system 70 needs to be started, at least a part of the generated electricity generated by the fuel cell 21 during the purging process is used to drive the electric fan 73a and the electric water pump 74 of the fuel cell cooling system 70 via the low-voltage DCDC converter 63 and the low-voltage circuit 60. This means that the electric fan 73a is driven by the generated electricity generated by the fuel cell 21 when the purging process of the fuel cell 21 is being performed. Furthermore, the electric fan 73a and the electric water pump 74 of the fuel cell cooling system 70 are driven until the purging process is completed.

[0034] Therefore, since the electric fan 73a and the electric water pump 74 of the fuel cell cooling system 70 are driven while the purging process is being performed, the driver can recognize that the purging process is being performed when he or she leaves the cab 8 by the operating sounds of the electric fan 73a and the electric water pump 74 that cool the fuel cell radiator 72 located behind the cab 8. Note that the operating sound of the electric fan 73a is particularly loud, and is therefore effective in making the driver recognize that the purging process is being performed. This makes it possible to prevent the driver from interrupting the purging process by turning off the disconnect switch 62.

[0035] In this embodiment, in order to allow the driver to easily recognize the operating sounds of the electric fan 73a and the electric water pump 74, the fuel cell cooling system 70 is disposed in a position as shown in FIG. That is, the fuel cell cooling system 70, which includes the fuel cell radiator 72 and the electric fan 73a, is disposed on one of the left and right sides of the vehicle and behind (behind) the driver's cab 8. Furthermore, the fuel cell cooling system 70 is disposed adjacent to the driver's cab 8. This makes it easier for the driver to hear the operating sounds of the electric fan 73a and the electric water pump 74. Note that here, "forward" is the direction that the driver faces when riding on the rotating body 4 in normal use, and "rearward" is the opposite direction to forward.

[0036] As shown in FIG. 4, the fuel cell radiator 72 and the electric fan 73a are disposed on one side of the revolving body 4. In this case, the electric fan 73a is disposed on one side of the vehicle in the left-right direction and takes in outside air from one side of the vehicle in the left-right direction. This makes it easier to take in outside air. In addition, a plurality of electric fans 73a are provided, and each electric fan 73a is disposed along the side of the revolving body 4. By providing a plurality of electric fans 73a, cooling performance is ensured even when a large cooling performance is required for the fuel cell radiator 72. In addition, by disposing each electric fan 73a along the side of the revolving body 4, even if there are multiple electric fans 73a, each electric fan 73a can take in outside air. Note that "one side" is the direction that is the left direction when the driver gets on the revolving body 4 in a normal use state, and "the other side" is the direction that is the right direction.

[0037] 4, the electric device radiator 82, the auxiliary device radiator 83, and the electric fans 73b and 73c for cooling them are disposed on the other side of the revolving body 4, facing the fuel cell radiator 72 with the fuel cell 21 in between. These electric fans 73b and 73c are disposed on the other side of the revolving body 4 in the left-right direction and facing the electric fan 73a, and take in outside air from the other side of the revolving body in the left-right direction and send it to the fuel cell 21 side. On the other hand, the electric fan 73a for cooling the fuel cell radiator 72 is disposed on one side of the revolving body in the left-right direction and takes in outside air from one side of the revolving body in the left-right direction and sends it to the fuel cell 21 side. As a result, the hot air sent out from each radiator collides with the revolving body 4 near the center, changes direction to the counterweight 10 side, and is discharged from the rear of the revolving body 4. This makes it difficult for hot air downstream of each radiator to flow around to the upstream of other radiators, which reduces the cooling performance. Note that the counterweight 10 is provided with an opening for discharging the outside air taken in by the electric fans 73a to 73c.

[0038] 4, the electric fan 73a is disposed between the operator's cab 8 and the counterweight 10 in the front-rear direction of the rotating body 4. As a result, the sound emitted from the electric fan 73a is less likely to come out rearward due to the presence of the counterweight 10, but is more likely to come out toward the sides and front of the rotating body 4. This makes it easier for the operator to hear the operating sound of the electric fan 73a.

[0039] Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention. [Explanation of symbols]

[0040] 8...operator cab, 10...counterweight, 21...fuel cell, 23...electric motor, 70...fuel cell cooling system, 71...fuel cell cooling circuit, 72...fuel cell radiator, 73a, 73b, 73c, 81F...electric fan, 82...electric equipment radiator, 83...auxiliary equipment radiator, 100...hydraulic excavator

Claims

1. A driver's cab provided on one of the left and right sides of the aircraft and in front of the aircraft; A fuel cell that generates electricity to be supplied to an electric motor that serves as a power source; a first cooling device for cooling the fuel cell; A work machine, characterized in that the first cooling device is disposed on one of the left and right sides of the work machine and behind the operator's cab.

2. 2. The work machine according to claim 1, wherein the first cooling device is disposed adjacent to the operator's cab.

3. the first cooling device includes a first heat exchanger and a plurality of first cooling fans disposed opposite the first heat exchanger to blow cooling air to the first heat exchanger; 3. The work machine according to claim 2, wherein the plurality of first cooling fans are arranged along a side surface of the work machine.

4. A counterweight is provided at the rear end of the aircraft. the first cooling device includes a first heat exchanger and a first cooling fan disposed opposite the first heat exchanger to blow cooling air to the first heat exchanger; 2. The working machine according to claim 1, wherein the first cooling fan is disposed between the operator's cab and the counterweight in the fore-and-aft direction of the working machine.

5. A second cooling device for cooling the electric motor is further provided, the first cooling device includes a first heat exchanger and a first cooling fan disposed opposite the first heat exchanger to blow cooling air to the first heat exchanger; the second cooling device includes a second heat exchanger and a second cooling fan disposed opposite the second heat exchanger to blow cooling air to the second heat exchanger; the first cooling fan is disposed on one of the left and right sides of the device, and takes in outside air from one of the left and right sides of the device; 2. The working machine according to claim 1, wherein the second cooling fan is arranged on the other side of the left-right direction of the machine and opposite the first cooling fan, and takes in outside air from the other side of the left-right direction of the machine.

6. A counterweight is provided at the rear end of the aircraft.

6. The work machine according to claim 5, wherein the counterweight is provided with an opening for discharging outside air taken in by the first cooling fan and the second cooling fan.

7. 4. The work machine according to claim 3, wherein the first cooling fan is driven by power generated by the fuel cell while the purging process for the fuel cell is being performed.

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