Work machine, work machine cooling system, and work machine cooling method

Abstract

A fuel cell stack (22) extracts electricity by reacting oxygen with hydrogen in a hydrogen tank (21). A water tank (2) stores water generated by the fuel cell stack (22). A spray unit (1) sprays water in the water tank (2) in a region that includes a core of a heat exchanger (25). The spray unit (1) sprays the water at a prescribed timing. A controller (30) acquires load information pertaining to the load of a work machine (100) from a load sensor (41), and performs control such that the spray unit (1) sprays the water on the basis of the load information.

Description

Work machine, cooling system for work machine, and cooling method for work machine

[0001] The present disclosure relates to a work machine having a fuel cell, a cooling system in the work machine, and a cooling method in the work machine.

[0002] New energy sources that do not emit greenhouse gases such as carbon dioxide have been developed for use in work machines and the like. Fuel cells have attracted attention as such an energy source. Fuel cells generate electrical energy by chemically reacting hydrogen and oxygen in a fuel cell stack. After power generation, fuel cells only emit water, and no carbon dioxide. A work machine equipped with such a fuel cell is described, for example, in International Publication No. 2022 / 137688 (Patent Document 1).

[0003] International Publication No. 2022 / 137688

[0004] Fuel cells are prone to high temperatures because they cannot dissipate heat through exhaust gas like internal combustion engines such as internal combustion engines. When a fuel cell becomes too hot, its power generation efficiency decreases and its lifespan is shortened. This necessitates a cooling device (radiator, fan, etc.) that is larger than the cooling devices used in internal combustion engines. However, the internal space of a work machine is limited, making it difficult to increase the size of the cooling device. Furthermore, increasing the fan rotation speed to prevent the fuel cell from becoming too hot requires more fan energy, which reduces fuel efficiency and increases noise, affecting the operator's riding comfort.

[0005] An object of the present disclosure is to provide a work machine, a cooling system in the work machine, and a cooling method in the work machine that can efficiently cool a fuel cell.

[0006] The work machine and the cooling system for the work machine of the present disclosure each include a fuel cell, a heat exchanger, a water tank, and a spray unit. The fuel cell generates electricity by reacting oxygen and hydrogen. The heat exchanger has a core. The water tank stores water produced by the fuel cell. The spray unit sprays water from the water tank onto an area including the core of the heat exchanger. A controller acquires load information related to the load of the work machine from a sensor and controls the spray unit to spray based on the load information.

[0007] The cooling method for a work machine disclosed herein is a cooling method for a work machine having a fuel cell that generates electricity by reacting oxygen and hydrogen, a heat exchanger having a core, a water tank that stores water produced by the fuel cell, and a spray unit that sprays water from the water tank onto an area including the core of the heat exchanger. The cooling method for a work machine disclosed herein includes the steps of acquiring load information related to the load on the work machine from a sensor, and spraying by the spray unit based on the acquired load information.

[0008] According to the present disclosure, it is possible to realize a work machine, a cooling system for a work machine, and a cooling method for a work machine that can efficiently cool a fuel cell.

[0009] Fig. 7 is a side view showing the configuration of a work machine having a fuel cell according to an embodiment of the present disclosure. Fig. 8 is a top view showing the configuration of a cooling unit in the work machine shown in Fig. 1. Fig. 9 is a side view showing the configuration of a cooling unit in the work machine shown in Fig. 1. Fig. 10 is a rear view showing the configuration of a cooling unit in the work machine shown in Fig. 1. Fig. 11 is a top view showing the configuration of a modified example in which the spray unit is arranged on the outside of an exterior door. Fig. 8 is a block diagram showing the configuration of a cooling system in a work machine according to an embodiment of the present disclosure. Fig. 9 is a functional block diagram of the controller shown in Fig. 6. Fig. 10 is a flow chart showing a cooling method in a work machine according to an embodiment of the present disclosure.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the specification and drawings, identical or corresponding components are designated by the same reference numerals, and redundant explanations will not be repeated. In addition, in the drawings, configurations may be omitted or simplified for the sake of convenience.

[0011] In the following description, the terms "up," "down," "front," "rear," "left," and "right" refer to directions relative to the operator seated in the driver's seat 14S in the driver's cab 14 shown in Figure 1.

[0012] Therefore, in the following description, the fore-aft direction refers to the direction in which the boom 16 extends between the base end and the tip end in a top view. The left-right direction refers to the direction perpendicular to the fore-aft direction in a top view. The up-down direction refers to the direction perpendicular to a plane that includes the fore-aft direction and the left-right direction, which are perpendicular to each other.

[0013] The direction from the base end of the boom 16 to the tip end is the front, and the direction from the tip end of the boom 16 to the base end is the rear. When looking forward from the rear, the right and left sides are the right and left, respectively. In the up-down direction, the side with the ground is the bottom, and the side with the sky is the top. A top view refers to a perspective from which the work machine 100 is viewed from above and below. A side view refers to a perspective from which the rotating unit 13 is viewed from the left and right. A rear view refers to a perspective from which the rotating unit 13 is viewed from the rear to the front.

[0014] <Configuration of Work Machine> Hereinafter, a work machine according to the present disclosure will be described using FIG. 1 , taking a shovel equipped with a fuel cell as an example.

[0015] The work machine of the present disclosure is not limited to a shovel, but may be a bulldozer, wheel loader, motor grader, or the like equipped with a fuel cell.

[0016] Fig. 1 is a side view that schematically shows the configuration of a work machine according to one embodiment of the present disclosure. As shown in Fig. 1, the work machine 100 according to this embodiment is, for example, a shovel equipped with a fuel cell. The fuel cell generates electrical energy by chemically reacting hydrogen and oxygen.

[0017] The work machine 100 has a fuel cell stack 22 as a fuel cell. The fuel cell stack 22 is a stack of multiple fuel cell units connected in series. The work machine 100 has, for example, two fuel cell stacks 22, but the number of fuel cell stacks 22 mounted on the work machine 100 is not limited to two and may be one, or may be three or more.

[0018] The work machine 100 has hydrogen tanks 21 for supplying hydrogen to the fuel cell stack 22. The work machine 100 has, for example, three hydrogen tanks 21, but the number of hydrogen tanks 21 mounted on the work machine 100 is not limited to three and may be one, or may be two or four or more.

[0019] The work machine 100 has a cooling unit CU for cooling the fuel cell stack 22. The cooling unit CU has a heat exchanger 25. The heat exchanger 25 has one or more selected from the group consisting of a radiator, an oil cooler, and an air conditioner outdoor unit heat exchanger. The radiator is a heat exchanger for dissipating heat from a cooling medium (coolant, for example, water) that cools the fuel cell stack 22, fuel cell accessories 53, electrical components 54, etc. The oil cooler is a heat exchanger for dissipating heat from hydraulic oil used in hydraulic actuators such as hydraulic cylinders and hydraulic motors. The air conditioner outdoor unit heat exchanger is, for example, an air conditioner outdoor unit heat exchanger for conditioning the air in the cab 14.

[0020] The work machine 100 has fuel cell accessories 53 ( FIG. 6 ) related to the power generation operation of the fuel cell stack 22. The fuel cell accessories 53 cause the fuel cell stack 22 to operate to generate power or assist the power generation operation of the fuel cell stack 22. The fuel cell accessories 53 include, for example, a pump, a blower, a fuel shutoff valve, etc. for supplying gas to the fuel cell stack 22. The fuel cell accessories 53 may also include, for example, a flow meter, a pressure gauge, etc. for monitoring the fuel cell stack 22. The work machine 100 may also include electrical components 54 ( FIG. 6 ). The electrical components 54 include, for example, a power conversion device that converts DC power generated by the fuel cell stack 22 into AC power, a DC / DC converter, an electric motor, etc.

[0021] The work machine 100 has a main body 11 and a hydraulically operated work implement 12. The main body 11 has a revolving body 13 and a traveling body 15.

[0022] The running body 15 has a pair of left and right crawler tracks 15Cr and a traveling motor 15M. The work machine 100 can travel by rotation of the crawler tracks 15Cr. The traveling motor 15M is provided as a drive source for the running body 15.

[0023] The rotating body 13 is disposed on and supported by the running body 15. The rotating body 13 can be rotated relative to the running body 15 about a rotation axis RX by a rotation motor (not shown). The rotation axis RX is an imaginary straight line that serves as the rotation center of the rotating body 13.

[0024] The rotating body 13 has a driver's cab 14. A driver's seat 14S where an operator sits is provided inside the driver's cab 14. The operator sits in the driver's seat 14S and can operate the work implement 12, rotate the rotating body 13 relative to the traveling body 15, and travel the work machine 100 using the traveling body 15.

[0025] The work implement 12 is supported by the rotating bed 13. The work implement 12 has a boom 16, an arm 17, and a bucket 18. The work implement 12 further has a boom cylinder 19a, an arm cylinder 19b, and a bucket cylinder 19c. Hydraulic cylinders such as the boom cylinder 19a, the arm cylinder 19b, and the bucket cylinder 19c, and hydraulic motors such as the swing motor correspond to an example of a hydraulic actuator 51 ( FIG. 6 ) of the present disclosure.

[0026] The boom 16 is rotatably connected to the main body 11. Specifically, the base end of the boom 16 is rotatably connected to the revolving unit 13 with a boom foot pin BF as a fulcrum. The base end of the boom 16 is disposed to the left and right of the operator's cab 14. The arm 17 is rotatably connected to the boom 16. Specifically, the base end of the arm 17 is rotatably connected to the tip of the boom 16 with a boom top pin BT as a fulcrum. The bucket 18 is rotatably connected to the arm 17. Specifically, the base end of the bucket 18 is rotatably connected to the tip of the arm 17 with an arm top pin AT as a fulcrum.

[0027] The rotating body 13 has an exterior panel OP that surrounds a machinery room. A hydrogen tank 21, a fuel cell stack 22, a cooling unit CU, etc. are arranged in the machinery room of the rotating body 13. The hydrogen tank 21, the fuel cell stack 22, the cooling unit CU, the fuel cell auxiliary machinery 53, the electrical components 54, etc. are all covered by the exterior panel OP.

[0028] Although the above describes a configuration in which the driver's seat 14S is located inside the driver's cab 14, the driver's seat 14S may be exposed to the outside without the driver's cab 14. The work machine 100 may also not have a driver's cab 14 and operate automatically without a human. The work machine 100 may also not have a driver's cab 14 and be remotely operated by a remote controller.

[0029] <Configuration of Cooling Unit> Next, the configuration of the cooling unit in the work machine 100 shown in FIG. 1 will be described with reference to FIGS. 2 to 4. FIG.

[0030] Figures 2, 3 and 4 are a top view, a side view and a rear view, respectively, showing the configuration of the cooling unit in the work machine shown in Figure 1. As shown in Figure 2, the revolving body 13 has a revolving frame RF. Arranged on the revolving frame RF are a hydrogen tank 21, a fuel cell stack 22, a heat exchanger 25, a cooling fan 26, a water tank 2, a water pump 3 and a spray unit 1.

[0031] The cooling unit CU has a heat exchanger 25, a cooling fan 26, a water tank 2, a water pump 3, a spray unit 1, and flow paths 4 and 5. The hydrogen tank 21 stores hydrogen. The hydrogen tank 21 is connected to the fuel cell stack 22 by a hose. As a result, the hydrogen stored in the hydrogen tank 21 is supplied to the fuel cell stack 22 via the hose.

[0032] A pressure reducer (not shown) is disposed between the hydrogen tank 21 and the fuel cell stack 22. The pressure reducer has a pressure reducing valve and functions to reduce the pressure of the high-pressure hydrogen gas supplied from the hydrogen tank 21 to a level that can be used in the fuel cell stack 22, which is a power generation device.

[0033] The fuel cell stack 22 generates electrical energy by chemically reacting hydrogen gas, which has been decompressed by a pressure reducer, with oxygen. After power generation, the fuel cell stack 22 only emits water; no carbon dioxide is emitted.

[0034] The heat exchanger 25 includes a radiator, an oil cooler, a heat exchanger for an outdoor unit of an air conditioner, etc. The heat exchanger 25 has, for example, a core, a header pipe, and a side sheet. The core of the heat exchanger 25 is the part that releases heat from the cooling medium and has heat transfer tubes and fins. Fins are attached to the heat transfer tubes to improve heat transfer. Header pipes are connected to the cooling medium inlet and outlet of the heat transfer tubes. The side sheet is located on the side of the core.

[0035] The radiator included in the heat exchanger 25 is a device for releasing heat from the cooling medium after cooling the fuel cell stack 22, fuel cell accessories 53, electrical components 54, etc. The cooling fan 26 cools the heat exchanger 25 by blowing air through it. The cooling fan 26 is, for example, an axial fan. The cooling fan 26 may be a single axial fan or may be made up of multiple axial fans. The cooling fan 26 is, for example, an electric fan that is provided with driving force by a motor.

[0036] The heat exchanger 25, the cooling fan 26, and the fuel cell stack 22 are arranged side by side in the left-right direction. The cooling fan 26 is arranged between the heat exchanger 25 and the fuel cell stack 22. The cooling fan 26 is arranged between the heat exchanger 25 and the hydrogen tank 21. The cooling fan 26 is arranged, for example, to the right of the heat exchanger 25 and to the left of the fuel cell stack 22 and the hydrogen tank 21.

[0037] A water tank 2 is connected to the fuel cell stack 22. The fuel cell stack 22 and the water tank 2 are connected by a flow path 5 such as a pipe or a hose. As a result, water discharged from the fuel cell stack 22 reaches the water tank 2 through the flow path 5 and is stored in the water tank 2.

[0038] A water pump 3 is attached to the water tank 2. The water pump 3 operates by receiving driving force from, for example, an electric motor. The water pump 3 pumps up the water stored in the water tank 2 when it operates.

[0039] The spray unit 1 is connected to the water pump 3. The water pump 3 and the spray unit 1 are connected by a flow path 4 such as a pipe or a hose. As a result, water pumped from the water tank 2 by the water pump 3 is supplied to the spray unit 1 through the flow path 4. Only one spray unit 1 may be connected to the water pump 3, or multiple spray units 1 may be connected to the water pump 3.

[0040] The spray unit 1 sprays the supplied water onto an area including the core of the heat exchanger 25 in the cooling unit CU. The area including the core may include not only the core of the heat exchanger 25 but also the header pipe, side sheet, etc. surrounding the core. In other words, the spray unit 1 may spray not only the core of the heat exchanger 25 but also the header pipe, side sheet, etc. surrounding the core. The spray unit 1 is, for example, a component having a spray hole. The spray unit 1 may be a nozzle. The spray hole of the spray unit 1 opens toward the heat exchanger 25. The spray unit 1 sprays water in a mist form onto the area where the core of the heat exchanger 25 is stepped on. In this case, the spray unit 1 has a spray hole with an extremely fine diameter.

[0041] The spray unit 1 is controlled to spray onto an area including the core of the heat exchanger 25 based on load information related to the load on the work machine 100. The spray unit 1 is controlled to spray onto an area including the core of the heat exchanger 25, for example, when it is determined that the load on the work machine 100 is high.

[0042] The spray unit 1 may spray the area including the core of the heat exchanger 25 at a predetermined timing. The predetermined timing may be, for example, immediately after startup, immediately after the load on the work machine 12 detected by the work machine load sensor increases, or immediately after the amount of water in the water tank 2 detected by the water level sensor exceeds a threshold. "Immediately after startup" refers to immediately after the fuel cell stack 22 starts supplying electricity to the electric motor or the like that serves as the drive source. The load on the work machine 12 increases, for example, when the work machine 12 excavates and lifts the excavation target and swings, such as when the bucket 18 is carrying a load, when the bucket 18 has dug into the excavation target, or when the work machine 12 is swinging.

[0043] The spray unit 1 is disposed in the left-right direction of the heat exchanger 25. In this embodiment, the spray unit 1 is disposed, for example, on the left side of the heat exchanger 25. However, the spray unit 1 may be disposed on the right side of the heat exchanger 25, or may be disposed in the front-rear direction of the heat exchanger 25.

[0044] The spray unit 1 is disposed on the opposite side of the heat exchanger 25 from the cooling fan 26, the hydrogen tank 21, and the fuel cell stack 22. The spray unit 1 is disposed upwind of the heat exchanger 25 in the direction of airflow when the cooling fan 26 is operating normally. Note that the cooling fan 26 may rotate in the opposite direction, for example, during cleaning. The spray unit 1 is disposed further outside the machine room than the heat exchanger 25. The spray unit 1 is located closer to the side panel of the exterior panel OP than the heat exchanger 25.

[0045] The spray unit 1 may be provided inside an exterior door OPD included in the exterior panel OP. That is, the spray unit 1 may be disposed inside a machine room surrounded by the exterior panel OP. The exterior door OPD is a part that opens and closes the machine room surrounded by the exterior panel OP to the outside.

[0046] As shown in Fig. 3, it is preferable that one spray unit 1 or multiple spray units 1 are arranged and configured so as to spray the entire surface of the heat exchanger 25. For example, one spray unit 1 may be arranged approximately in the center of the heat exchanger 25 in a side view. The approximately in the center of the heat exchanger 25 in a side view refers to the midpoint of the height dimension DH of the heat exchanger 25 and the midpoint of the front-to-rear dimension DW, as shown in Fig. 3. Furthermore, for example, one spray unit 1 may be arranged above the approximately in the center of the heat exchanger 25 in a side view.

[0047] For example, multiple spray units 1 may be arranged in a matrix in the front-to-back direction (the direction of dimension DW) and the up-to-down direction (the direction of dimension DH) in a side view. Furthermore, when multiple spray units 1 are arranged, they are not limited to a matrix arrangement, and any arrangement is possible as long as they can spray the entire heat exchanger 25.

[0048] The spray unit 1 may also be disposed at a position higher than the upper end of the heat exchanger 25. In this way, mist-like water may be sprayed onto the heat exchanger 25 from the spray unit 1 disposed at a position higher than the heat exchanger 25.

[0049] The water tank 2 is located at a lower position than the fuel cell stack 22. This allows water discharged from the fuel cell stack 22 to be smoothly sent to the water tank 2 through the flow path 5 (FIG. 2) due to its own weight. The water tank 2 is preferably located closer to the center of rotation (rotation axis RX) than the heat exchanger 25. By locating the water tank 2 closer to the center of rotation, it is less susceptible to the centrifugal force when the rotating body 13 rotates, the water level in the water tank 2 is less likely to fluctuate, and water is prevented from spilling from the water tank 2 and being unable to be supplied to the water pump 3.

[0050] As shown in Fig. 4, the cooling fan 26 preferably has a height approximately equal to that of the heat exchanger 25. Specifically, the cooling fan 26 preferably has a height approximately equal to that of the portion (core) of the heat exchanger 25 that has heat dissipation fins, excluding the header pipe. When the cooling fan 26 is made up of multiple axial fans, it is preferable that the height of the area in which the multiple axial fans are arranged is approximately equal to the height of the heat exchanger 25. Note that the cooling fan 26 may have a height greater than that of the heat exchanger 25.

[0051] As shown in FIG. 5 , the spray unit 1 may be provided outside the exterior door OPD included in the exterior panel OP. In other words, the spray unit 1 may be located outside the machine room surrounded by the exterior panel OP. In this case, the spray unit 1 sprays water through an air inlet portion AI provided in the exterior door OPD toward an area including the core of the heat exchanger 25 located inside the machine room. The air inlet portion AI is a through-hole provided in the exterior door OPD. The air inlet portion AI is configured, for example, by any one of slits, fins, punched metal, etc., or any combination thereof. When the spray unit 1 is located outside the exterior door OPD, the spray unit 1 may be attached to the exterior door OPD so as not to interfere with the opening and closing of the exterior door OPD, and may operate in conjunction with the opening and closing of the exterior door OPD.

[0052] <Cooling System and Cooling Method in Work Machine> Next, a cooling system and a cooling method in the work machine of this embodiment will be described with reference to FIGS. 6 to 8. FIG.

[0053] Fig. 6 is a block diagram showing the configuration of a cooling system in a work machine according to an embodiment of the present disclosure. Fig. 7 is a functional block diagram of the controller shown in Fig. 6. Fig. 8 is a flow chart showing a cooling method in a work machine according to an embodiment of the present disclosure.

[0054] As shown in Figure 6, the load sensor 41 detects load information related to the load on the work machine 100. The controller 30 acquires the load information detected by the load sensor 41. The controller 30 is electrically connected to the water pump 3. Specifically, the controller 30 is electrically connected to an electric motor (not shown) that drives the water pump 3. This enables the controller 30 to control the driving of the water pump 3.

[0055] The controller 30 controls the water pump 3 so that the spray unit 1 sprays toward an area including the core of the heat exchanger 25, based on load information related to the load on the work machine 100 acquired from the load sensor 41. For example, when the controller 30 determines that the load on the work machine 100 is high, the controller 30 controls the water pump 3 so that the spray unit 1 sprays toward an area including the core of the heat exchanger 25.

[0056] The load information includes, for example, hydraulic oil information relating to the hydraulic oil supplied to the hydraulic actuator 51, fuel cell information relating to the fuel cell stack 22 as a fuel cell, the working state of the work machine 100, and the temperature of the coolant (the temperature of the coolant that cools the fuel cell stack 22, the fuel cell accessories 53, or the electrical components 54).

[0057] The controller 30 controls the spray unit 1 to spray based on hydraulic oil information related to the hydraulic oil supplied to the hydraulic actuator 51. The hydraulic oil information is at least one of the oil pressure and oil temperature of the hydraulic oil supplied to the hydraulic actuator 51. When the workload is heavy, both the oil pressure and the oil temperature of the hydraulic oil become high. Therefore, the load on the work machine 100 can be estimated from both the oil pressure and the oil temperature of the hydraulic oil.

[0058] The hydraulic pressure of the hydraulic oil is detected by pressure sensors (an example of load sensors 41) installed in, for example, the boom cylinder 19 a, the arm cylinder 19 b, the bucket cylinder 19 c, and the swing motor. The temperature of the hydraulic oil is detected by a hydraulic oil temperature sensor (an example of load sensors 41) installed in a hydraulic oil flow path 52 such as a hydraulic pipe or an oil tank.

[0059] The controller 30 also controls the spray unit 1 to spray based on fuel cell information relating to the fuel cell stack 22. The fuel cell information is one or more items selected from the group consisting of a command value that commands the amount of electricity to be output from the fuel cell stack 22, the amount of electricity output from the fuel cell stack 22, and the temperature of the fuel cell stack 22.

[0060] When the workload is increased, the command value requests a larger quantity of electricity to be output from the fuel cell stack 22. When the workload is increased, the quantity of electricity output from the fuel cell stack 22 also increases. When the workload is increased, the temperature of the fuel cell stack 22 also increases. For this reason, the load on the work machine 100 can be estimated from each of the command value that commands the quantity of electricity to be output from the fuel cell stack 22, the quantity of electricity output from the fuel cell stack 22, and the temperature of the fuel cell stack 22. Note that when the command value requests a larger quantity of electricity to be output from the fuel cell stack 22, the quantity of electricity output from the fuel cell stack 22 increases, and the temperature of the fuel cell stack 22 increases. For this reason, the need for cooling of the heat exchanger 25 also increases.

[0061] The command value is output by the controller 30 and can therefore be detected from the output value of the controller 30. The amount of electricity output from the fuel cell stack 22 is detected by a sensor (an example of a load sensor 41) such as an ammeter or voltmeter installed in the output circuit of the fuel cell stack 22. The temperature of the fuel cell stack 22 is detected by a temperature sensor (an example of a load sensor 41) such as a temperature sensor installed in the fuel cell stack 22 or a temperature sensor installed in the flow path of the coolant that cools the fuel cell stack 22.

[0062] The controller 30 controls the spray unit 1 to spray based on the working state of the work machine 100. Working states in which the load on the work machine 100 is large include, for example, when the work implement 12 excavates and lifts the excavation target while swinging, such as a state in which the bucket 18 is carrying a load, a state in which the bucket 18 has dug into the excavation target, or a state in which the work implement 12 is swinging. Such states of the work machine 100 are acquired, for example, from the oil pressure of the hydraulic oil supplied to the hydraulic actuator 51, the acceleration when the work implement 12 is operating or when the swing unit 13 is swinging, the operation signal of the operating lever 55, etc.

[0063] As described above, the hydraulic pressure of the hydraulic oil supplied to the hydraulic actuator 51 is detected by a pressure sensor (an example of a load sensor 41). The acceleration during operation of the work implement 12 or during rotation of the revolving body 13 is detected by a sensor (an example of a load sensor 41) such as an acceleration sensor or an IMU (Inertial Measurement Unit). The operation signal of the control lever 55 is a signal detected by, for example, a potentiometer (an example of a load sensor 41) if the control lever 55 is an electric control lever, or is the pressure of pilot oil, for example, detected by a hydraulic sensor if the control lever 55 is a hydraulic control lever. In addition to the above, the working state of the work machine 100 may be acquired from the detection results of a stroke sensor, angle sensor, imaging device, or the like, which are examples of the load sensor 41.

[0064] The controller 30 controls the spray unit 1 to spray based on the temperature of the coolant that cools the fuel cell stack 22, the fuel cell accessories 53, or the electrical components 54. When the workload is heavy, the temperature of the coolant rises. Therefore, the load on the work machine 100 can be estimated from the coolant temperature. The coolant temperature is detected by a temperature sensor (an example of a load sensor 41), such as a temperature sensor installed in each of the fuel cell stack 22, the fuel cell accessories 53, and the electrical components 54, or a temperature sensor installed in the coolant flow path.

[0065] The controller 30 may control the spray unit 1 to spray based on one or more selected from the group consisting of the amount of water in the water tank 2, the start of the work machine 100, and the outside air temperature of the work machine 100. The controller 30 may also control the spray unit 1 to spray when it is determined that the amount of water in the water tank 2 detected by the water amount sensor 42 has exceeded a predetermined threshold. This makes it possible to prevent the water tank 2 from becoming full.

[0066] The controller 30 may control the spray unit 1 to spray when the start sensor 43 detects that a start operation of the start device 56 has been performed. The start device 56 is, for example, a key switch or a start button. When the operator inserts a key into the key switch and performs a key operation such as turning it, the controller 30 may acquire that signal from the start sensor 43 and determine that start has begun. When the operator presses the start button, the controller 30 may acquire that signal from the start sensor 43 and determine that start has begun. By having the spray unit 1 spray based on the start of start of the work machine 100, cooling can begin immediately after start-up.

[0067] The controller 30 may control the spray unit 1 to spray when it is determined that the outside air temperature detected by an outside air temperature sensor 44 installed at any location on the work machine 100 has exceeded a predetermined threshold. When the outside air temperature is high, the temperature of the coolant that cools the fuel cell stack 22 is likely to also increase, so the spray unit 1 cools the coolant by spraying.

[0068] It is also possible for the spray unit 1 to spray without using the controller 30. For example, a water volume switch that turns on and off based on the amount of water in the water tank 2 may be provided, and the start and stop of spraying by the spray unit 1 may be controlled based on the on / off status of the water volume switch. Alternatively, the start and stop of spraying by the spray unit 1 may be controlled based on the on / off status of the starting device 56. Alternatively, a switch that turns on and off based on the attitude of the work machine 12, the rotation angle of the rotating body 13, etc. may be provided, and the start and stop of spraying by the spray unit 1 may be controlled based on the on / off status of the switch.

[0069] As shown in FIG. 7, the controller 30 includes an acquisition unit 30a, a determination unit 30b, a control unit 30c, and a memory 30d.

[0070] 7 and 8 , in the cooling method for a work machine of this embodiment, first, load information relating to the load on the work machine 100 is detected by the load sensor 41. The load sensor 41 outputs the detected load information of the work machine 100 to the controller 30.

[0071] The acquisition unit 30a of the controller 30 acquires load information of the work machine 100 from the load sensor 41 (step S1: FIG. 8). The determination unit 30b determines whether or not the spray unit 1 should spray based on the load information of the work machine 100 acquired from the acquisition unit 30a (step S2: FIG. 8). Specifically, the determination unit 30b determines whether or not the load on the work machine 100 is heavy based on the load information of the work machine 100 acquired from the acquisition unit 30a, and if it determines that the load is heavy, it determines that spraying should be performed by the spray unit 1. On the other hand, if it determines that the load on the work machine 100 is light, it determines that spraying should not be performed by the spray unit 1.

[0072] When making the above-mentioned determination, the determination unit 30b refers to determination criteria stored in advance in the memory 30d. The determination criteria are various thresholds, such as a threshold for hydraulic oil pressure, a threshold for hydraulic oil temperature, a threshold for a command value to the fuel cell stack 22, a threshold for the amount of electricity output from the fuel cell stack 22, and a threshold for the refrigerant temperature.

[0073] If the determination unit 30b determines that spraying should not be performed by the spray unit 1, the steps from step S1 onwards are repeated. On the other hand, if the determination unit 30b determines that spraying should be performed by the spray unit 1, the control unit 30c controls the water pump 3 to start operating the water pump 3 (step S3: FIG. 8). As a result, spraying by the spray unit 1 is performed.

[0074] As shown in Figure 7, the controller 30 may acquire detection information from each of the water volume sensor 42, start sensor 43, and outside air temperature sensor 44 using an acquisition unit 30a, determine whether each of the acquired detection information satisfies the spray start conditions of the spray unit 1 using a judgment unit 30b, and control the operation of the water pump 3 using a control unit 30c based on the judgment result.

[0075] Specifically, when the determination unit 30b determines that the amount of water in the water tank 2 detected by the water volume sensor 42 has exceeded a threshold value, the control unit 30c operates the water pump 3 and controls the spray unit 1 to spray. Furthermore, when the determination unit 30b determines that the start sensor 43 has detected the start of startup of the work machine 100, the control unit 30c operates the water pump 3 and controls the spray unit 1 to spray. Furthermore, when the determination unit 30b determines that the outside air temperature of the work machine 100 detected by the outside air temperature sensor 44 has exceeded a threshold value, the control unit 30c operates the water pump 3 and controls the spray unit 1 to spray.

[0076] <Effects> Next, the effects of the present disclosure will be described.

[0077] 2 to 4, in this embodiment, the water in the water tank 2 is sprayed by the spray unit 1 onto an area including the heat exchanger 25. This makes it possible to effectively use the water produced by the fuel cell stack 22 to cool the heat exchanger 25.

[0078] Furthermore, because the heat exchanger 25 can be cooled by water, there is no need to increase the size of the radiator (heat exchanger 25) and cooling fan 26 for cooling the fuel cell stack 22, etc. This reduces space and noise problems.

[0079] The water tank 2 also stores water produced by the fuel cell stack 22. This prevents the water produced by the fuel cell stack 22 from leaking. Storing water in the water tank 2 also allows the water to be cooled within the water tank 2. Storing water in the water tank 2 also makes it easier to adjust the amount of water sprayed onto the heat exchanger 25.

[0080] Furthermore, the spray unit 1 sprays based on load information relating to the load on the work machine 100. As a result, when the load on the work machine 100 increases and the heat exchanger 25 becomes hot, the spray unit 1 can spray onto the heat exchanger 25. Therefore, when there is a high need to cool the heat exchanger 25, the heat exchanger 25 can be cooled efficiently by the spray from the spray unit 1.

[0081] 6, the magnitude of the load on the work machine 100 can be determined from information about the hydraulic oil supplied to the hydraulic actuator 51 (for example, oil pressure and oil temperature), information about the fuel cell stack 22 (for example, a command value to the fuel cell stack 22, the amount of electricity output from the fuel cell stack 22, and the temperature of the fuel cell), the temperature of the coolant that cools the fuel cell stack 22 and the like, or the working state of the work machine 100. Therefore, by detecting this information and controlling the spray unit 1, the heat exchanger 25 can be cooled efficiently.

[0082] The spray unit 1 may also spray water at a predetermined timing onto the area including the heat exchanger 25. This allows the heat exchanger 25 to be cooled when the heat exchanger 25 becomes hot, and makes it possible to cool the heat exchanger 25 efficiently.

[0083] 2 to 4, the spray unit 1 may spray mist-like water onto the heat exchanger 25. This makes it easier for the mist-like water sprayed onto the heat exchanger 25 to vaporize due to the heat of the heat exchanger 25. The heat exchanger 25 is efficiently cooled as the heat of vaporization is removed by the vaporization of the water.

[0084] Furthermore, since the water sprayed onto the heat exchanger 25 evaporates into water vapor, the sprayed water is prevented from remaining liquid and wetting the work machine 100 .

[0085] 2 and 3, the water pump 3 supplies water stored in the water tank 2 to the spray unit 1. This makes it possible to efficiently cool the heat exchanger 25 by controlling the operation of the water pump 3. It also makes it possible to position the spray unit 1 higher than the water tank 2, improving the flexibility of the spray unit 1 placement.

[0086] 2 and 4, the cooling fan 26 is disposed on the opposite side of the heat exchanger 25 from the spray unit 1. This allows the spray unit 1 to spray onto the heat exchanger 25 from upwind of the heat exchanger 25 in the airflow direction of the cooling fan 26. This allows the water discharged from the spray unit 1 to be effectively directed towards the heat exchanger 25 by the airflow from the cooling fan 26.

[0087] According to this embodiment, as shown in FIG. 2 , the heat exchanger 25 includes one or more components selected from the group consisting of a radiator that dissipates heat from a coolant that cools the fuel cell stack 22, fuel cell accessories 53 ( FIG. 6 ), electrical components 54 ( FIG. 6 ), etc., an oil cooler that dissipates heat from hydraulic oil used to operate the hydraulic actuator 51 ( FIG. 6 ), and an air conditioner exterior heat exchanger. By cooling the radiator, the fuel cell stack 22, fuel cell accessories 53, and electrical components 54 can be cooled. Furthermore, by cooling the oil cooler, the hydraulic oil supplied to the hydraulic actuator can be cooled. Furthermore, by cooling the air conditioner exterior heat exchanger, the interior of the cab 14 can be efficiently cooled.

[0088] <Additional Notes> The above-described embodiment includes the following technical ideas.

[0089] (Supplementary Note 1) A work machine comprising: a fuel cell that generates electricity by reacting oxygen and hydrogen; a heat exchanger having a core; a water tank that stores water produced by the fuel cell; a spray unit that sprays water from the water tank onto an area of ​​the heat exchanger that includes the core; and a controller that acquires load information related to the load on the work machine from a sensor and controls the spray unit to spray based on the load information.

[0090] (Supplementary Note 2) The work machine according to Supplementary Note 1, further comprising a hydraulic actuator that operates the work machine, wherein the load information includes hydraulic oil information related to hydraulic oil supplied to the hydraulic actuator.

[0091] (Supplementary Note 3) The work machine according to Supplementary Note 2, wherein the hydraulic oil information is at least one of a hydraulic pressure and an oil temperature of the hydraulic oil supplied to the hydraulic actuator.

[0092] (Supplementary Note 4) The work machine according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the load information includes fuel cell information related to the fuel cell.

[0093] (Supplementary Note 5) The work machine according to Supplementary Note 4, wherein the fuel cell information is one or more selected from the group consisting of a command value that commands the amount of electricity to be output from the fuel cell, the amount of electricity output from the fuel cell, and the temperature of the fuel cell.

[0094] (Supplementary Note 6) The work machine according to any one of Supplementary Notes 1 to 5, further comprising a fuel cell auxiliary device and an electrical component that are involved in the power generation operation of the fuel cell, and the load information includes a temperature of a coolant that cools the fuel cell, the fuel cell auxiliary device, or the electrical component.

[0095] (Supplementary Note 7) The work machine according to any one of Supplementary Notes 1 to 6, wherein the load information includes a work state of the work machine.

[0096] (Supplementary Note 8) The work machine according to any one of Supplementary Notes 1 to 7, further comprising an exterior panel that surrounds a machine room in which the heat exchanger is arranged and has an exterior door that opens and closes the machine room, and the spray unit is provided inside the exterior door.

[0097] (Supplementary Note 9) The working machine according to any one of Supplementary Notes 1 to 8, further comprising an exterior panel surrounding a machine room in which the heat exchanger is arranged and having an exterior door for opening and closing the machine room, wherein the exterior door has an air inlet portion that leads from the outside of the exterior panel to the machine room, and the spraying portion is provided on the outside of the exterior door and sprays water onto the area including the core through the air inlet portion.

[0098] (Supplementary Note 10) A cooling system for a work machine, comprising: a fuel cell that reacts oxygen and hydrogen to generate electricity; a heat exchanger having a core; a water tank that stores water produced by the fuel cell; a spray unit that sprays water from the water tank onto an area of ​​the heat exchanger that includes the core; and a controller that acquires load information related to the load on the work machine from a sensor and controls the spray unit to spray based on the load information.

[0099] (Supplementary Note 11) The cooling system for a work machine according to Supplementary Note 10, further comprising a hydraulic actuator that operates the work machine, wherein the load information includes hydraulic oil information related to hydraulic oil supplied to the hydraulic actuator.

[0100] (Supplementary Note 12) The cooling system for a work machine according to Supplementary Note 10 or Supplementary Note 11, wherein the load information includes fuel cell information related to the fuel cell.

[0101] (Supplementary Note 13) The cooling system for a work machine according to any one of Supplementary Note 10 to Supplementary Note 12, further comprising a fuel cell auxiliary device and an electrical component related to the power generation operation of the fuel cell, and the load information includes a temperature of a coolant that cools the fuel cell, the fuel cell auxiliary device, or the electrical component.

[0102] (Supplementary Note 14) A cooling method for a work machine having a fuel cell that reacts oxygen and hydrogen to generate electricity, a heat exchanger having a core, a water tank that stores water produced by the fuel cell, and a spray unit that sprays water from the water tank onto an area of ​​the heat exchanger that includes the core, the cooling method for a work machine comprising the steps of: acquiring load information related to a load on the work machine from a sensor; and spraying by the spray unit based on the acquired load information.

[0103] (Supplementary Note 15) The cooling method for a work machine according to Supplementary Note 14, wherein the work machine has a hydraulic actuator that operates the work machine, and the load information includes hydraulic oil information related to hydraulic oil supplied to the hydraulic actuator.

[0104] (Supplementary Note 16) The cooling method for a work machine according to Supplementary Note 15, wherein the hydraulic oil information is at least one of a hydraulic pressure and an oil temperature of the hydraulic oil supplied to the hydraulic actuator.

[0105] (Supplementary Note 17) The cooling method for a work machine according to any one of Supplementary Note 14 to Supplementary Note 16, wherein the load information includes fuel cell information related to the fuel cell.

[0106] (Supplementary Note 18) A cooling method for a work machine as described in Supplementary Note 17, wherein the fuel cell information is one or more selected from the group consisting of a command value that commands the amount of electricity to be output from the fuel cell, the amount of electricity output from the fuel cell, and the temperature of the fuel cell.

[0107] (Supplementary Note 19) A cooling method for a work machine according to any one of Supplementary Notes 14 to 18, wherein the work machine has fuel cell accessories and electrical components involved in the power generation operation of the fuel cell, and the load information includes a temperature of a coolant that cools the fuel cell, the fuel cell accessories, or the electrical components.

[0108] (Supplementary Note 20) The cooling method for a work machine according to any one of Supplementary Notes 14 to 19, wherein the load information includes a working state of the work machine.

[0109] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0110] DESCRIPTION OF SYMBOLS 1 Spray unit, 2 Water tank, 3 Water pump, 4, 5 Flow path, 11 Main body, 12 Work machine, 13 Swing body, 14 Cab, 14S Cab, 15 Traveling body, 15Cr Track, 15M Traveling motor, 16 Boom, 17 Arm, 18 Bucket, 19a Boom cylinder, 19b Arm cylinder, 19c Bucket cylinder, 21 Hydrogen tank, 22 Fuel cell stack, 25 Heat exchanger, 26 Cooling fan, 30 Controller, 30a Acquisition unit, 30b Determination unit, 30c Control unit, 30d Memory, 41 Load sensor, 42 Water volume sensor, 43 Start sensor, 44 Outside air temperature sensor, 51 Hydraulic actuator, 52 Hydraulic oil flow path, 53 Fuel cell auxiliary equipment, 54 Electrical component, 55 Operation lever, 56 Starting device, 100 Work machine, AI Air inlet unit, AT Arm top pin, BF boom foot pin, BT boom top pin, CU cooling unit, OP exterior panel, OPD exterior door, RF rotating frame, RX rotating axis.

Claims

1. A work machine comprising: a fuel cell that reacts oxygen and hydrogen to produce electricity; a heat exchanger having a core; a water tank that stores water produced by the fuel cell; a spray unit that sprays water from the water tank onto an area of ​​the heat exchanger including the core; and a controller that obtains load information regarding the load of the work machine from a sensor and controls the spray unit to spray based on the load information.

2. The work machine according to claim 1, further comprising a hydraulic actuator for operating said work machine, wherein said load information includes hydraulic oil information relating to hydraulic oil supplied to said hydraulic actuator.

3. A work machine according to claim 2, wherein the hydraulic oil information is at least one of the hydraulic pressure and the oil temperature of the hydraulic oil supplied to the hydraulic actuator.

4. The work machine of claim 1, wherein said load information includes fuel cell information relating to said fuel cell.

5. A work machine as described in claim 4, wherein the fuel cell information is one or more selected from the group consisting of a command value that commands the amount of electricity to be output from the fuel cell, the amount of electricity output from the fuel cell, and the temperature of the fuel cell.

6. The work machine according to claim 1, further comprising fuel cell auxiliaries and electrical components related to the power generation operation of the fuel cell, and the load information includes a temperature of a coolant that cools the fuel cell, the fuel cell auxiliaries or the electrical components.

7. The work machine according to claim 1, wherein the load information includes a working state of the work machine.

8. The work machine according to claim 1, further comprising an exterior panel surrounding a machine room in which the heat exchanger is disposed and having an exterior door for opening and closing the machine room, and the spray unit is provided on the inside of the exterior door.

9. The work machine according to claim 1, further comprising an exterior panel surrounding a machine room in which the heat exchanger is arranged and having an exterior door for opening and closing the machine room, the exterior door having an air inlet portion leading to the machine room from the outside of the exterior panel, and the spraying portion being provided on the outside of the exterior door and spraying water onto the area including the core through the air inlet portion.

10. A cooling system for a work machine comprising: a fuel cell that reacts oxygen and hydrogen to extract electricity; a heat exchanger having a core; a water tank that stores water produced by the fuel cell; a spray unit that sprays water from the water tank onto an area of ​​the heat exchanger including the core; and a controller that obtains load information regarding the load of the work machine from a sensor and controls the spray unit to spray based on the load information.

11. The cooling system for a work machine according to claim 10, further comprising a hydraulic actuator for operating the work machine, wherein the load information includes hydraulic oil information relating to hydraulic oil supplied to the hydraulic actuator.

12. The cooling system in a work machine according to claim 10, wherein the load information includes fuel cell information relating to the fuel cell.

13. A cooling system for a work machine as described in claim 10, further comprising fuel cell accessories and electrical components related to the power generation operation of the fuel cell, and the load information includes a temperature of a coolant that cools the fuel cell, the fuel cell accessories, or the electrical components.

14. A cooling method for a work machine having a fuel cell that reacts oxygen and hydrogen to extract electricity, a heat exchanger having a core, a water tank that stores water produced by the fuel cell, and a spray unit that sprays water from the water tank onto an area of ​​the heat exchanger including the core, the cooling method for a work machine comprising the steps of: acquiring load information relating to the load of the work machine from a sensor; and spraying by the spray unit based on the acquired load information.

15. A cooling method for a work machine according to claim 14, wherein the work machine has a hydraulic actuator that operates the work machine, and the load information includes hydraulic oil information related to hydraulic oil supplied to the hydraulic actuator.

16. The cooling method for a work machine according to claim 15, wherein the hydraulic oil information is at least one of the hydraulic pressure and the oil temperature of the hydraulic oil supplied to the hydraulic actuator.

17. The method of cooling a work machine according to claim 14, wherein the load information includes fuel cell information relating to the fuel cell.

18. A cooling method for a work machine as described in claim 17, wherein the fuel cell information is one or more selected from the group consisting of a command value that commands the amount of electricity to be output from the fuel cell, the amount of electricity output from the fuel cell, and the temperature of the fuel cell.

19. A cooling method for a work machine as described in claim 14, wherein the work machine has fuel cell accessories and electrical components related to the power generation operation of the fuel cell, and the load information includes a temperature of a coolant that cools the fuel cell, the fuel cell accessories, or the electrical components.

20. The cooling method for a work machine according to claim 14, wherein the load information includes an operating state of the work machine.