Hydrogen detection system and hydrogen detection method for machine

Abstract

A fuel cell stack (22) generates electricity by reacting oxygen with hydrogen stored in a hydrogen tank (21). An electrically-driven fan (26) blows cooling air toward at least one of the hydrogen tank (21), the fuel cell stack (22), and a hydrogen flow path connecting the hydrogen tank (21) and the fuel cell stack (22). A revolution rate detection sensor (2) detects the number of revolutions of the electrically-driven fan (26). A hydrogen leak detection sensor (1) detects the amount of hydrogen outside the hydrogen tank (21). A controller (10) performs determination for the amount of hydrogen detected by the hydrogen leak detection sensor (1) on the basis of whether or not the number of revolutions of the electrically-driven fan (26) detected by the revolution rate detection sensor (2) is equal to or lower than a designated number of revolutions set in advance.

Description

Hydrogen detection system and method for machines

[0001] SUMMARY The present disclosure relates to a hydrogen detection system and method for a machine having a fuel cell.

[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. One such energy source that has attracted attention is fuel cells. 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] Power sources that use hydrogen as a raw material, such as fuel cells, use hydrogen stored in tanks. If hydrogen leaks from the tank, raw material is lost and the efficiency of hydrogen utilization decreases. For this reason, there is a demand for a method to accurately detect the amount of leaking hydrogen.

[0005] An object of the present disclosure is to provide a hydrogen detection system and method for a machine having a hydrogen power source that can accurately detect the amount of leaking hydrogen.

[0006] The hydrogen detection system for a machine according to the present disclosure includes a hydrogen tank, a hydrogen power source, a fan, a hydrogen leak detection sensor, and a controller. The hydrogen power source is a power source that utilizes hydrogen stored in the hydrogen tank. The fan blows cooling air toward at least one of the hydrogen tank, the hydrogen power source, and a hydrogen distribution path connecting the hydrogen tank and the hydrogen power source. The hydrogen leak detection sensor detects the amount of hydrogen outside the hydrogen tank. The controller acquires the fan's rotation speed and determines the amount of detected hydrogen based on whether the acquired fan rotation speed is equal to or less than a predetermined rotation speed.

[0007] The hydrogen detection method for a machine according to the present disclosure is a method for detecting hydrogen in a machine having a hydrogen tank, a hydrogen-powered source that utilizes hydrogen stored in the hydrogen tank, and a fan. The fan blows cooling air toward at least one of the hydrogen tank, the hydrogen-powered source, and a hydrogen distribution path connecting the hydrogen tank and the hydrogen-powered source. The hydrogen detection method for a machine according to the present disclosure includes the following steps:

[0008] The rotation speed of the fan is acquired. The amount of hydrogen outside the hydrogen tank is acquired. The amount of hydrogen acquired is determined based on whether the rotation speed of the fan acquired is equal to or less than a predetermined rotation speed.

[0009] According to the present disclosure, it is possible to realize a hydrogen detection system and a hydrogen detection method for a machine having a hydrogen power source, which can accurately detect the amount of leaking hydrogen.

[0010] FIG. 2 is a side view showing the configuration of a machine having a fuel cell in an embodiment of the present disclosure. FIG. 3 is a perspective view showing the arrangement of a fuel cell stack and a hydrogen tank in the machine shown in FIG. 1. FIG. 4 is a side view showing the arrangement of a fuel cell stack and a hydrogen tank in the machine shown in FIG. 1. FIG. 5 is a rear view showing the flow of leaked hydrogen when the electric fan is rotated forward. FIG. 6 is a rear view showing the flow of leaked hydrogen when the electric fan is stopped. FIG. 7 is a rear view showing the flow of leaked hydrogen when the electric fan is rotated in reverse at low speed. FIG. 8 is a functional block diagram showing a hydrogen detection system for a machine in an embodiment of the present disclosure. FIG. 9 is a diagram showing the change over time in the rotation speed of the electric fan. FIG. 10 is a flow chart showing a hydrogen detection method for a machine in an embodiment of the present disclosure.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] <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.

[0016] The work machine of the present disclosure is not limited to a shovel, but may also be a bulldozer, wheel loader, motor grader, dump truck, forklift, or the like equipped with a fuel cell. Furthermore, the present disclosure is not limited to a work machine, but may be applicable to any machine equipped with a fuel cell. Furthermore, the machine to which the present disclosure is applied is not limited to one equipped with a fuel cell, but may be any machine equipped with a hydrogen power source, which is a power source that uses hydrogen. The hydrogen power source may be, in addition to a fuel cell, a hydrogen-mixed combustion engine that burns hydrogen mixed with fossil fuel, or a hydrogen-only combustion engine that burns only hydrogen without using fossil fuel.

[0017] 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 electricity (electrical energy) by causing a chemical reaction between hydrogen and oxygen.

[0018] The generated electrical energy drives the hydraulic pump. The hydraulic oil discharged from the hydraulic pump as the hydraulic pump is driven operates each hydraulic actuator (swing motor, travel motor, each hydraulic cylinder). If each hydraulic actuator is an electric motor, the generated electrical energy is supplied to the electric motor.

[0019] 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.

[0020] The work machine 100 has hydrogen tanks 21 for supplying hydrogen to the fuel cell stack 22. The work machine 100 has, for example, four hydrogen tanks 21, but the number of hydrogen tanks 21 mounted on the work machine 100 is not limited to four and may be one, or may be two, three, five or more. The hydrogen stored in the hydrogen tanks 21 may be in the form of gas or liquid. The hydrogen tanks 21 may also be tanks for storing generated hydrogen. The hydrogen tanks 21 may also be tanks for temporarily storing hydrogen generated from, for example, ethanol, ammonia, 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 tracks 15Cr and a travel motor 15M. The work machine 100 is capable of traveling by rotation of the tracks 15Cr. The travel motor 15M is provided as a drive source for the running body 15. The travel motor 15M may be a hydraulic motor or an electric motor.

[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. The rotation motor may be a hydraulic motor or an electric motor.

[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. Each of the cylinders 19a, 19b, and 19c may be a hydraulic cylinder or may be driven by an electric motor.

[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. The machinery room of the rotating body 13 is a space surrounded by the exterior panel OP. 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, etc. are surrounded 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] <Arrangement of Fuel Cell Stack and Hydrogen Tank> Next, the arrangement of the fuel cell stack 22 and the hydrogen tank 21 in the work machine 100 shown in FIG. 1 will be described with reference to FIGS. 2 and 3. FIG.

[0030] Figures 2 and 3 are a perspective view and a side view, respectively, showing the arrangement of the fuel cell stack and the hydrogen tank in the work machine shown in Figure 1. As shown in Figures 2 and 3, the fuel cell stack 22 is disposed on the rotating frame 20. The hydrogen tank 21 is disposed on top of the fuel cell stack 22.

[0031] A lower plate UP is supported on the revolving frame 20 via damper mounts DM and the like. Two fuel cell stacks 22, for example, are disposed on the lower plate UP. The two fuel cell stacks 22 are arranged side by side in the front-to-rear direction and extend in the left-to-right direction so as to be substantially parallel to each other. An upper plate TP is disposed on top of the fuel cell stacks 22. The upper plate TP is supported by the lower plate UP via pillar members CM extending in the up-down direction.

[0032] A tank frame TF is disposed on the upper plate TP. Four hydrogen tanks 21, for example, are supported on the tank frame TF. The four hydrogen tanks 21 are arranged in two rows and two columns in a side view. That is, the four hydrogen tanks 21 are arranged so that two are lined up in the front-to-rear direction and two are lined up in the top-to-bottom direction in a side view. Each of the four hydrogen tanks 21 extends in the left-to-right direction so as to be approximately parallel to one another.

[0033] A pressure reducer 23 is attached to the tank frame TF. The pressure reducer 23 has a pressure reducing valve and functions to reduce the pressure of the high-pressure hydrogen gas supplied from the hydrogen tanks 21 to a level that can be used in the fuel cell stack 22, which is a power generation device. The pressure reducer 23 is disposed, for example, in front of the arrangement area AR of the four hydrogen tanks 21. The arrangement position of the pressure reducer 23 is not limited to being in front of the arrangement area AR, but may be behind or to the side of the arrangement area AR.

[0034] A hood frame FF is disposed on the tank frame TF and the hydrogen tank 21. The hood frame FF is a member that supports the upper panel of the exterior panel OP (Figure 1). The hood frame FF is disposed so as to straddle the tank frame TF and the hydrogen tank 21 in the front-to-rear direction. The hood frame FF has a pair of left and right frame members FFR, FFL. The pair of left and right frame members FFR, FFL extend in the front-to-rear direction and are disposed so as to be substantially parallel to each other with a gap between them in the left-to-right direction.

[0035] The hydrogen tank 21 and the pressure reducer 23 are connected by a tank hose (not shown). High-pressure hydrogen gas in the hydrogen tank 21 is supplied to the pressure reducer 23 through this tank hose. An on-off valve 24 is disposed between the hydrogen tank 21 and the tank hose. The on-off valve 24 opens and closes to control the start and stop of the supply of high-pressure hydrogen gas from the hydrogen tank 21 to the pressure reducer 23.

[0036] The pressure reducer 23 and the fuel cell stack 22 are connected by a stack hose SH. Hydrogen gas decompressed by the pressure reducer 23 is supplied to the fuel cell stack 22 through this stack hose SH.

[0037] The connection P1 between the fuel cell stack 22 and the stack hose SH, the connection P2 between the hydrogen tank 21 and the tank hose, the connection P3 between the stack hose and the pressure reducer 23, and the connection P3 between the tank hose and the pressure reducer 23 are locations where hydrogen gas is likely to leak. These connection P1, P2, and P3 are located on the same side in the left-right direction. For example, connection P1 may be located at the left end of the fuel cell stack 22, connection P2 may be located at the left end of the hydrogen tank 21, and connection P3 may be located at the left end of the pressure reducer 23. Alternatively, connection P1 may be located at the right end of the fuel cell stack 22, connection P2 may be located at the right end of the hydrogen tank 21, and connection P3 may be located at the right end of the pressure reducer 23.

[0038] The work machine 100 has a hydrogen leak detection sensor 1. The hydrogen leak detection sensor 1 detects hydrogen gas leaks from the connection parts P1, P2, P3, etc. Various types of sensors can be used for the hydrogen leak detection sensor 1.

[0039] The hydrogen leak detection sensor 1 may be of various types, including thermal conduction (gas thermal conduction), semiconductor, solid electrolyte, thermoelectric, and optical. Thermal conduction sensors utilize the high thermal conductivity of hydrogen gas to detect the amount of hydrogen by detecting the difference in thermal conductivity between the reference gas (air) and the gas detected by the sensor as the amount of hydrogen increases. Semiconductor sensors detect the amount of hydrogen by detecting the change in electrical conductivity caused by the adsorption of hydrogen gas onto the surface of a metal oxide semiconductor. Solid electrolyte sensors use a solid electrode as a reference electrode and a solid electrolyte as a hydrogen gas-sensitive material, detecting the amount of hydrogen by measuring the voltage generated by the oxidation reaction between the two electrodes. Thermoelectric sensors utilize the temperature change caused by a catalytic reaction, converting the local temperature difference within the sensor into a voltage signal via heat-to-voltage conversion (the Seebeck effect). Optical sensors detect the amount of hydrogen by detecting the change in light reflectance caused by the reaction of hydrogen with an alloy thin film. The detected amount of hydrogen is measured in units of hydrogen concentration (%), for example.

[0040] The hydrogen leak detection sensor 1 is disposed, for example, above the fuel cell stack 22 or the hydrogen tank 21. The hydrogen leak detection sensor 1 is disposed above any of the connection parts P1, P2, and P3. The hydrogen leak detection sensor 1 may also be disposed directly above each of the connection parts P1, P2, and P3. The hydrogen leak detection sensor 1 is disposed, for example, above the connection parts P1 and P2 between the hose (stack hose, tank hose) and the fuel cell stack 22 or the hydrogen tank 21. The hydrogen leak detection sensor 1 is also disposed, for example, above the connection part P3 between the hose (stack hose, tank hose) and the pressure reducer 23.

[0041] The hydrogen leak detection sensor 1 includes a hydrogen leak detection sensor 1a and a hydrogen leak detection sensor 1b. The hydrogen leak detection sensor 1a is disposed on the upper plate TP. The hydrogen leak detection sensor 1a is disposed above the connection portion P1. The hydrogen leak detection sensor 1a is disposed below the hydrogen tank 21. The hydrogen leak detection sensor 1a is disposed, for example, on the lower surface of the upper plate TP. The hydrogen leak detection sensor 1a may also be disposed directly above the connection portion P1.

[0042] The hydrogen leak detection sensor 1b is disposed on the hood frame FF. The hydrogen leak detection sensor 1b is disposed above the connection portions P2 and P3. The hydrogen leak detection sensor 1b is disposed above the hydrogen tank 21. The hydrogen leak detection sensor 1b is disposed, for example, on the underside of the hood frame FF. The hydrogen leak detection sensor 1b may also be disposed directly above the connection portion P2 or P3. The hydrogen leak detection sensor 1b is attached to the frame member FFL of the hood frame FF. The hydrogen leak detection sensor 1b may also be attached to the frame member FFR, not just the frame member FFL.

[0043] <Layout of Cooling Unit and Flow of Leaked Hydrogen> Next, the layout of the cooling unit and the flow of leaked hydrogen in the work machine 100 shown in FIG. 1 will be described with reference to FIGS. 4 to 6. FIG.

[0044] 4, 5, and 6 are rear views showing the flow of leaked hydrogen when the electric fan 26 is rotated forward, stopped, and rotated in the reverse direction at low speed. As shown in Fig. 4, the work machine 100 has a cooling unit CU. The cooling unit CU has a radiator 25 and an electric fan (cooling fan) 26.

[0045] A cooling circuit through which a cooling medium passes to cool the fuel cell stack 22 is arranged around the fuel cell stack 22. The radiator 25 is a device for dissipating heat from the cooling medium (coolant, for example, water) that cools the fuel cell stack 22. The radiator 25 is, for example, a heat exchanger. The radiator 25 is arranged, for example, to the side of the fuel cell stack 22, for example, on the left side of the fuel cell stack 22. The radiator 25 may also be arranged, for example, on the right side of the fuel cell stack 22, or on the front or rear side of the fuel cell stack 22.

[0046] The electric fan 26 blows air onto the radiator 25 to dissipate heat emitted from the radiator 25. The electric fan 26 is disposed, for example, between the radiator 25 and the fuel cell stack 22.

[0047] When the electric fan 26 rotates forward, the radiator 25 is located upstream of the electric fan 26, and the fuel cell stack 22 is located downstream of the electric fan 26. Therefore, when the electric fan 26 rotates forward, air is drawn into the electric fan 26 through the radiator 25. The air blown out from the electric fan 26 is then sent toward at least one of the fuel cell stack 22, the hydrogen tank 21, and the hydrogen distribution path connecting the fuel cell stack 22 and the hydrogen tank 21. The hydrogen distribution path may include an on-off valve 24, a tank hose, a pressure reducer 23, a stack hose SH, etc. The air blown out from the electric fan 26 is sent into a machinery room in which at least one of the fuel cell stack 22, the hydrogen tank 21, and the hydrogen distribution path is located. Any one of the above-mentioned connections P1, P2, and P3 may be located in the machinery room into which the air blown out from the electric fan 26 is sent.

[0048] In this case, hydrogen gas leaking from connections P1, P2, and P3 flows in the direction indicated by the arrow in Figure 4 (upper right in the figure), and therefore most of the leaked hydrogen gas cannot be detected by the hydrogen leak detection sensor 1.

[0049] As shown in Figure 5, when the operation of the electric fan 26 is stopped, hydrogen gas leaking from the connections P1, P2, and P3 flows almost directly above the connections P1, P2, and P3, as shown by the arrows in Figure 5. Therefore, most of the leaked hydrogen gas can be detected by the hydrogen leak detection sensor 1.

[0050] As shown in Figure 6, when the electric fan 26 rotates in reverse, hydrogen gas leaking from the connections P1, P2, and P3 flows in the direction indicated by the arrow in Figure 6 (to the upper left in the figure). For this reason, most of the leaked hydrogen gas cannot be detected by the hydrogen leak detection sensor 1. However, when the electric fan 26 rotates in reverse at a low speed (when it rotates in reverse at a low speed), the electric fan 26 is rotating at a low speed, so the hydrogen gas leaking from the connections P1, P2, and P3 is not attracted to the electric fan 26 as much. For this reason, in such cases, the leaked hydrogen gas can be detected by the hydrogen leak detection sensor 1. The electric fan 26 is rotated in reverse, for example, when cleaning the fins of the radiator 25.

[0051] <Hydrogen Detection System> Next, a hydrogen detection system for the work machine 100 according to one embodiment of the present disclosure will be described with reference to FIGS. 7 and 8. FIG.

[0052] Fig. 7 is a functional block diagram showing a hydrogen detection system for a machine according to an embodiment of the present disclosure. Fig. 8 is a diagram showing the change in the rotation speed of an electric fan over time. As shown in Fig. 7, the controller 10 includes a hydrogen amount acquisition unit 10a, a rotation speed acquisition unit 10b, a hydrogen amount determination unit 10c, a display control unit 10d, a valve control unit 10e, and a memory 10f.

[0053] The hydrogen amount obtaining unit 10a obtains information relating to the amount of hydrogen output from the hydrogen leak detection sensor 1. The rotation speed obtaining unit 10b obtains information relating to the rotation speed of the electric fan 26. The rotation speed obtaining unit 10b obtains information relating to the rotation speed of the electric fan 26 output, for example, from the rotation speed detection sensor 2. The rotation speed detection sensor 2 is installed in the vicinity of the electric fan 26. The detection signal of the rotation speed detection sensor 2 is input to the controller 10. The rotation speed obtaining unit 10b may also obtain information relating to the rotation speed of the electric fan 26 based on a command value for the rotation speed of the electric fan 26.

[0054] The hydrogen amount determination unit 10c obtains information about the amount of hydrogen from the hydrogen amount acquisition unit 10a and information about the rotation speed of the electric fan 26 from the rotation speed acquisition unit 10b. The hydrogen amount determination unit 10c also obtains a predetermined rotation speed and a predetermined hydrogen amount that are pre-stored in memory 10f. The predetermined rotation speed is the rotation speed of the electric fan 26 and is a preset numerical value. The predetermined hydrogen amount is the amount of hydrogen outside the hydrogen tank 21 and is a preset numerical value for the amount of hydrogen.

[0055] The hydrogen amount determination unit 10c determines the amount of hydrogen detected by the hydrogen leak detection sensor 1 based on whether the rotation speed of the electric fan 26 detected by the rotation speed detection sensor 2 is equal to or lower than a predetermined rotation speed. This determination is specifically performed as follows.

[0056] The hydrogen amount determination unit 10c determines whether the rotation speed of the electric fan 26 detected by the rotation speed detection sensor 2 is equal to or lower than a predetermined rotation speed. If the hydrogen amount determination unit 10c determines that the rotation speed of the electric fan 26 is equal to or lower than the predetermined rotation speed, it recognizes (confirms) the amount of hydrogen acquired from the hydrogen amount acquisition unit 10a at that time. The hydrogen amount determination unit 10c can specify the recognized (confirmed) amount of hydrogen as the amount of leaked hydrogen. The hydrogen amount determination unit 10c determines whether the recognized (confirmed) amount of hydrogen is equal to or higher than a predetermined hydrogen amount.

[0057] When the hydrogen amount determination unit 10c determines that the recognized hydrogen amount is equal to or greater than the predetermined hydrogen amount, it outputs a signal indicating the determination result to the display control unit 10d and the valve control unit 10e. The hydrogen amount determination unit 10c also outputs signals indicating the hydrogen amount detected by the hydrogen leak detection sensor 1, the rotation speed detected by the rotation speed detection sensor 2, etc. to the display control unit 10d.

[0058] The display control unit 10d controls the display unit 27 to display on the display unit 27 information obtained from the hydrogen amount determination unit 10c, such as the amount of hydrogen detected by the hydrogen leak detection sensor 1 and the rotation speed detected by the rotation speed detection sensor 2. The display control unit 10d may also control the display unit 27 to display on the display unit 27 that hydrogen is leaking, based on a signal indicating the determination result obtained from the hydrogen amount determination unit 10c.

[0059] The valve control unit 10e controls the opening and closing of the on-off valve 24 based on a signal indicating the determination result obtained from the hydrogen amount determination unit 10c. Specifically, when the valve control unit 10e determines that the amount of hydrogen detected by the hydrogen leak detection sensor 1 is equal to or greater than a predetermined amount when the rotation speed of the electric fan 26 detected by the rotation speed detection sensor 2 falls below a predetermined rotation speed, the valve control unit 10e controls the on-off valve 24 to close. This stops the supply of hydrogen gas from the hydrogen tank 21 and prevents hydrogen leakage from each of the connections P1, P2, and P3. A gate valve can generally be used for the on-off valve 24.

[0060] In the above, the hydrogen leak detection sensor 1 may continuously detect and output the amount of hydrogen. In this case, the hydrogen amount acquisition unit 10a of the controller 10 continuously acquires the amount of hydrogen from the hydrogen leak detection sensor 1. The display control unit 10d of the controller 10 controls the display unit 27 to continuously display on the display unit 27 the changes in the continuously acquired amount of hydrogen.

[0061] The hydrogen leak detection sensor 1 may also temporarily detect and output the amount of hydrogen. In this case, the hydrogen amount acquisition unit 10a of the controller 10 temporarily acquires the amount of hydrogen from the hydrogen leak detection sensor 1. The display control unit 10d of the controller 10 controls the display unit 27 to display the temporarily acquired amount of hydrogen on the display unit 27.

[0062] The controller 10 includes a processor, a main memory, and a storage. The processor is, for example, a central processing unit (CPU). The main memory includes, for example, a nonvolatile memory such as a read-only memory (ROM) and a volatile memory such as a random access memory (RAM).

[0063] The controller 10 reads out a program stored in the storage, loads it into the main memory, and executes a predetermined process in accordance with the program. The program may be distributed to the controller 10 via a network.

[0064] The controller 10 may be mounted on the work machine 100, or may be located remotely outside the work machine 100. When the controller 10 is located remotely outside the work machine 100, the controller 10 may be wirelessly connected to the hydrogen leak detection sensor 1, the rotation speed detection sensor 2, the display unit 27, the on-off valve 24, etc. The controller 10 may be stored in a server remote from the work machine 100.

[0065] <Timing for Setting the Rotational Speed ​​of the Electric Fan to a Predetermined Speed ​​or Less> Next, the timing for setting the rotational speed of the electric fan to a predetermined speed or less will be described with reference to FIG.

[0066] Figure 8 compares (A) the case where the fan rotation speed is maintained at approximately the same value from the time the electric fan is started until it is stopped, with (B) the case where the fan rotation speed is controlled to be equal to or lower than a predetermined value. In Figures 8(A) and 8(B), plus (+) symbols indicate that the fan is rotating in the forward direction, and minus (-) symbols indicate that the fan is rotating in the reverse direction.

[0067] 8(B), the controller 10 may control the electric fan 26 so that the rotation speed of the electric fan 26 is equal to or lower than a predetermined rotation speed at timing T1, which is a first predetermined time after the start of hydrogen supply from the hydrogen tank 21 to the fuel cell stack 22. Alternatively, the controller 10 may control the electric fan 26 so that the rotation speed of the electric fan 26 is equal to or lower than a predetermined rotation speed at timing T2, which is a second predetermined time before the stop of hydrogen supply from the hydrogen tank 21 to the fuel cell stack 22.

[0068] The controller 10 may also control the electric fan 26 so that the rotation speed of the electric fan 26 is equal to or less than a predetermined rotation speed at timing T3 when the electric fan 26 is reversed from forward rotation to reverse rotation. The controller 10 may also control the electric fan 26 so that the rotation speed of the electric fan 26 is equal to or less than a predetermined rotation speed at timing T4 immediately after the rotation of the electric fan 26 is started.

[0069] At each of the times T1, T2, T3, and T4, the rotation speed of the electric fan 26 may be maintained at or below a predetermined rotation speed for a predetermined time.

[0070] <Hydrogen Detection Method> Next, a hydrogen detection method for the work machine 100 according to one embodiment of the present disclosure will be described with reference to FIGS. 7 and 9. FIG.

[0071] 7 and 9, the hydrogen amount acquiring unit 10a acquires information relating to the amount of hydrogen output from the hydrogen leak detection sensor 1 (step S1). The rotation speed acquiring unit 10b acquires information relating to the rotation speed of the electric fan 26 output from the rotation speed detection sensor 2 (step S2).

[0072] The hydrogen amount determination unit 10c obtains information about the amount of hydrogen from the hydrogen amount acquisition unit 10a, obtains information about the rotation speed of the electric fan 26 from the rotation speed acquisition unit 10b, and obtains a predetermined rotation speed and a predetermined hydrogen amount from the memory 10f. The hydrogen amount determination unit 10c determines whether the rotation speed of the electric fan 26 detected by the rotation speed detection sensor 2 is equal to or lower than a predetermined rotation speed (step S3).

[0073] If it is determined that the rotation speed of the electric fan 26 is not equal to or lower than the predetermined rotation speed, step S3 is repeated. On the other hand, if it is determined that the rotation speed of the electric fan 26 is equal to or lower than the predetermined rotation speed, the amount of hydrogen when the rotation speed of the electric fan 26 is equal to or lower than the predetermined rotation speed is recognized (confirmed) (step S4).

[0074] Next, the hydrogen amount determination unit 10c determines whether the recognized hydrogen amount is equal to or greater than a predetermined hydrogen amount (step S5). If it is determined that the recognized hydrogen amount is less than the predetermined hydrogen amount, step S3 is repeated. On the other hand, if it is determined that the confirmed hydrogen amount is equal to or greater than the predetermined hydrogen amount, the hydrogen amount determination unit 10c outputs a signal indicating the determination result to the valve control unit 10e.

[0075] Based on the determination result, the valve control unit 10e controls the on-off valve 24 to close (step S6), thereby stopping the supply of hydrogen gas from the hydrogen tank 21 to the fuel cell stack 22 and preventing hydrogen gas from leaking from the connections P1, P2, and P3.

[0076] In this manner, the hydrogen detection method for the work machine 100 in this embodiment is carried out. <Effects> Next, the effects of the present disclosure will be described.

[0077] According to this embodiment, as shown in Figure 7, the controller 10 determines the amount of hydrogen detected by the hydrogen leak detection sensor 1 based on whether the rotation speed of the electric fan 26 detected by the rotation speed detection sensor 2 is equal to or lower than a predetermined rotation speed. When the rotation speed of the electric fan 26 is zero or a low rotation speed, the air flow is restricted, and most of the hydrogen gas leaking from the connections P1, P2, and P3 can be detected by the hydrogen leak detection sensor 1, as shown in Figure 5 or Figure 6. Therefore, by determining the amount of hydrogen detected by the hydrogen leak detection sensor 1 when the rotation speed of the electric fan 26 is equal to or lower than a predetermined rotation speed, the amount of leaked hydrogen can be detected with high accuracy.

[0078] 7, the controller 10 recognizes the amount of hydrogen detected by the hydrogen leak detection sensor 1 when the rotation speed of the electric fan 26 detected by the rotation speed detection sensor 2 falls below a predetermined rotation speed. This makes it possible to recognize the amount of hydrogen detected when the rotation speed of the electric fan 26 falls below the predetermined rotation speed as the amount of hydrogen that has leaked from the connections P1, P2, and P3.

[0079] 7, in this embodiment, if the controller 10 determines that the amount of hydrogen detected by the hydrogen leak detection sensor 1 is equal to or greater than a predetermined amount when the rotation speed of the electric fan 26 detected by the rotation speed detection sensor 2 falls below a predetermined rotation speed, the controller 10 controls the on-off valve 24 to close. As a result, if it determines that hydrogen gas is leaking from the connections P1, P2, and P3, the on-off valve 24 can be closed to stop the hydrogen gas leak.

[0080] 8, the controller 10 controls the electric fan 26 so that the rotation speed of the electric fan 26 is equal to or lower than a predetermined rotation speed at timing T1, which is a first predetermined time after the start of hydrogen supply from the hydrogen tank 21 to the fuel cell stack 22. This makes it possible to accurately detect the amount of hydrogen that has leaked at timing T1, even while the work machine 100 is in operation.

[0081] 8, the controller 10 controls the electric fan 26 so that the rotation speed of the electric fan 26 is equal to or less than a predetermined rotation speed at timing T2, which is a second predetermined time before the supply of hydrogen from the hydrogen tank 21 to the fuel cell stack 22 is stopped. This makes it possible to accurately detect the amount of leaked hydrogen before the work machine 100 is stopped.

[0082] 9, the controller 10 controls the electric fan 26 so that the rotation speed of the electric fan 26 is equal to or lower than a predetermined rotation speed when the electric fan 26 is reversed from forward rotation to reverse rotation. This makes it possible to accurately detect the amount of leaked hydrogen when the electric fan 26 is reversed.

[0083] Furthermore, according to this embodiment, as shown in Figure 3, the hydrogen leak detection sensor 1 is disposed above the fuel cell stack 22 or the hydrogen tank 21. Hydrogen is lighter than air. Therefore, hydrogen gas leaking from the connections P1, P2, and P3 disperses upward. By disposing the hydrogen leak detection sensor 1 as described above, it is possible to accurately detect the amount of leaked hydrogen.

[0084] Furthermore, according to this embodiment, the hydrogen leak detection sensor 1 continuously detects and outputs the amount of hydrogen, thereby making it possible to continuously check the amount of hydrogen detected by the hydrogen leak detection sensor 1.

[0085] According to this embodiment, the hydrogen leak detection sensor 1 temporarily detects and outputs the amount of hydrogen. This allows the hydrogen leak detection sensor 1 to detect the amount of hydrogen, for example, at the timing when it is determined that the rotation speed of the electric fan 26 is equal to or lower than a predetermined rotation speed. This makes it possible to pinpoint the amount of hydrogen leak at the desired timing.

[0086] <Additional Notes> The above-described embodiment includes the following technical ideas.

[0087] (Supplementary Note 1) A hydrogen detection system for a machine comprising: a hydrogen tank; a hydrogen power source that is a power source that utilizes hydrogen stored in the hydrogen tank; a fan that blows cooling air toward at least one of the hydrogen tank, the hydrogen power source, and a hydrogen distribution path connecting the hydrogen tank and the hydrogen power source; a hydrogen leak detection sensor that detects the amount of hydrogen outside the hydrogen tank; and a controller, wherein the controller obtains the rotation speed of the fan and determines the amount of hydrogen detected by the hydrogen leak detection sensor based on whether the obtained rotation speed of the fan is equal to or less than a predetermined rotation speed.

[0088] (Supplementary Note 2) The hydrogen detection system for a machine according to Supplementary Note 1, wherein the controller recognizes the amount of hydrogen detected by the hydrogen leak detection sensor when the rotation speed of the fan falls below the predetermined rotation speed.

[0089] (Appendix 3) A hydrogen detection system for a machine as described in Appendix 1 or Appendix 2, further comprising an on-off valve for opening and closing the hydrogen tank, wherein the controller controls the on-off valve to close when it determines that the amount of hydrogen detected by the hydrogen leak detection sensor is equal to or greater than a predetermined amount of hydrogen when the rotation speed of the fan is below the predetermined rotation speed.

[0090] (Appendix 4) A hydrogen detection system for a machine described in any one of Appendices 1 to 3, wherein the controller controls the fan so that the rotation speed of the fan is equal to or less than a predetermined first predetermined time after hydrogen supply from the hydrogen tank to the hydrogen power source begins.

[0091] (Appendix 5) A hydrogen detection system for a machine described in any one of Appendices 1 to 4, wherein the controller controls the fan so that the rotation speed of the fan is equal to or less than the predetermined rotation speed at a timing that is a second predetermined time before the supply of hydrogen from the hydrogen tank to the hydrogen power source is stopped.

[0092] (Supplementary Note 6) The hydrogen detection system for a machine described in any one of Supplementary Note 1 to Supplementary Note 5, wherein the controller controls the fan so that the rotation speed of the fan is equal to or less than the predetermined rotation speed when the fan is reversed from forward rotation to reverse rotation.

[0093] (Supplementary Note 7) A hydrogen detection system for a machine according to any one of Supplementary Note 1 to Supplementary Note 6, wherein the hydrogen leak detection sensor is disposed above the hydrogen power source or the hydrogen tank.

[0094] (Appendix 8) A hydrogen detection system for a machine as described in Appendix 7, further comprising a hose connected to the hydrogen power source or the hydrogen tank, wherein the hydrogen leak detection sensor is positioned above the connection between the hose and the hydrogen power source or the hydrogen tank.

[0095] (Supplementary Note 9) A hydrogen detection system for a machine according to any one of Supplementary Note 1 to Supplementary Note 8, wherein the hydrogen leak detection sensor continuously detects and outputs the amount of hydrogen.

[0096] (Supplementary Note 10) The hydrogen detection system for a machine according to any one of Supplementary Note 1 to Supplementary Note 8, wherein the hydrogen leak detection sensor temporarily detects and outputs the amount of hydrogen.

[0097] (Supplementary Note 11) The hydrogen detection system for a machine described in any one of Supplementary Note 1 to Supplementary Note 10, wherein the hydrogen power source is a fuel cell.

[0098] (Supplementary Note 12) A hydrogen detection system for a machine described in any one of Supplementary Note 1 to Supplementary Note 11, wherein the fan blows cooling air into a machine room in which at least one of the hydrogen tank, the hydrogen power source, and the hydrogen distribution path is located.

[0099] (Appendix 13) A hydrogen detection system for a machine described in any one of Appendices 1 to 12, further comprising a rotation speed detection sensor that detects the rotation speed of the fan, and the controller determines the amount of hydrogen detected by the hydrogen leak detection sensor based on whether the rotation speed of the fan detected by the rotation speed detection sensor is equal to or lower than the predetermined rotation speed that has been set in advance.

[0100] (Appendix 14) A hydrogen detection method for a machine having a hydrogen tank, a hydrogen power source that is a power source that utilizes hydrogen stored in the hydrogen tank, and a fan, wherein the fan blows cooling air toward at least one of the hydrogen tank, the hydrogen power source, and a hydrogen distribution path connecting the hydrogen tank and the hydrogen power source, the hydrogen detection method for a machine comprising the steps of: acquiring the rotation speed of the fan; acquiring the amount of hydrogen outside the hydrogen tank; and determining the amount of hydrogen acquired based on whether the acquired rotation speed of the fan is equal to or less than a predetermined rotation speed that has been set in advance.

[0101] (Appendix 15) A hydrogen detection method for a machine as described in Appendix 14, wherein when the rotation speed of the fan is below the predetermined rotation speed and it is determined that the amount of hydrogen acquired is equal to or greater than a predetermined hydrogen amount, the opening / closing valve for opening and closing the hydrogen tank is controlled to close.

[0102] (Appendix 16) A hydrogen detection method for a machine as described in Appendix 14 or Appendix 15, which controls the fan so that the rotation speed of the fan is equal to or less than a predetermined rotation speed when a first predetermined time has elapsed since the start of hydrogen supply from the hydrogen tank to the hydrogen power source.

[0103] (Appendix 17) A hydrogen detection method for a machine described in any one of Appendices 14 to 16, wherein the fan is controlled so that the rotation speed of the fan is equal to or less than a predetermined rotation speed at a timing before a second predetermined time period that is set in advance after the supply of hydrogen from the hydrogen tank to the hydrogen power source is stopped.

[0104] (Supplementary Note 18) A hydrogen detection method for a machine as described in any one of Supplementary Note 14 to Supplementary Note 17, wherein the fan is controlled so that the rotation speed of the fan is equal to or less than the predetermined rotation speed when the fan is reversed from forward rotation to reverse rotation.

[0105] (Supplementary Note 19) The hydrogen detection method for a machine according to any one of Supplementary Note 14 to Supplementary Note 18, wherein in the step of acquiring the amount of hydrogen, the amount of hydrogen is acquired continuously.

[0106] (Supplementary Note 20) The hydrogen detection method for a machine according to any one of Supplementary Note 14 to Supplementary Note 18, wherein in the step of acquiring the amount of hydrogen, the amount of hydrogen is acquired temporarily.

[0107] 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.

[0108] DESCRIPTION OF SYMBOLS 1, 1a, 1b Hydrogen leak detection sensor, 2 Rotation speed detection sensor, 10 Controller, 10a Hydrogen amount acquisition unit, 10b Rotation speed acquisition unit, 10c Hydrogen amount determination unit, 10d Display control unit, 10e Valve control unit, 10f Memory, 11 Main body, 12 Work machine, 13 Swing body, 14 Driver's cab, 14S Driver's seat, 15 Running body, 15Cr Track, 15M Travel motor, 16 Boom, 17 Arm, 18 Bucket, 19a Boom cylinder, 19b Arm cylinder, 19c Bucket cylinder, 20 Swing frame, 21 Hydrogen tank, 22 Fuel cell stack, 23 Pressure reducer, 24 On-off valve, 25 Radiator, 26 Electric fan, 27 Display unit, 100 Work machine, AR Placement area, AT Arm top pin, BF Boom foot pin, BT Boom top pin, CU cooling unit, DM damper mount, FF hood frame, FFL, FFR frame members, OP exterior panel, P1, P2, P3 connection part, RX swivel shaft, SH stack hose, TF tank frame, TP upper plate, UP plate.

Claims

1. A hydrogen detection system for a machine comprising: a hydrogen tank; a hydrogen power source that is a power source that utilizes hydrogen stored in the hydrogen tank; a fan that blows cooling air toward at least one of the hydrogen tank, the hydrogen power source, and a hydrogen distribution path connecting the hydrogen tank and the hydrogen power source; a hydrogen leak detection sensor that detects the amount of hydrogen outside the hydrogen tank; and a controller, wherein the controller acquires the rotation speed of the fan and determines the amount of hydrogen detected by the hydrogen leak detection sensor based on whether the acquired rotation speed of the fan is equal to or lower than a predetermined rotation speed.

2. A hydrogen detection system for a machine as set forth in claim 1, wherein said controller recognizes the amount of hydrogen detected by said hydrogen leak detection sensor when the rotation speed of said fan falls below said predetermined rotation speed.

3. A hydrogen detection system for a machine as described in claim 1, further comprising an on-off valve for opening and closing the hydrogen tank, wherein the controller controls the on-off valve to close when it determines that the amount of hydrogen detected by the hydrogen leak detection sensor is equal to or greater than a predetermined amount of hydrogen when the rotation speed of the fan falls below the predetermined rotation speed.

4. A hydrogen detection system for a machine as described in claim 1, wherein the controller controls the fan so that the rotation speed of the fan becomes equal to or lower than a predetermined rotation speed at a timing when a first predetermined time has elapsed since the start of hydrogen supply from the hydrogen tank to the hydrogen power source.

5. A hydrogen detection system for a machine as described in claim 1, wherein the controller controls the fan so that the rotation speed of the fan is equal to or lower than the predetermined rotation speed at a timing that is a second predetermined time before the supply of hydrogen from the hydrogen tank to the hydrogen power source is stopped and is preset.

6. A hydrogen detection system for a machine as described in claim 1, wherein the controller controls the fan so that the rotation speed of the fan is equal to or lower than the predetermined rotation speed when the fan is reversed from forward rotation to reverse rotation.

7. The hydrogen detection system for a machine as set forth in claim 1, wherein said hydrogen leak detection sensor is disposed above said hydrogen power source or said hydrogen tank.

8. A hydrogen detection system for a machine as described in claim 7, further comprising a hose connected to said hydrogen power source or said hydrogen tank, and said hydrogen leak detection sensor is positioned above a connection between said hose and said hydrogen power source or said hydrogen tank.

9. The hydrogen detection system for a machine according to claim 1, wherein the hydrogen leak detection sensor continuously detects and outputs the amount of hydrogen.

10. The hydrogen detection system for a machine according to claim 1, wherein the hydrogen leak detection sensor temporarily detects and outputs the amount of hydrogen.

11. The machine hydrogen detection system of claim 1, wherein said hydrogen power source is a fuel cell.

12. The hydrogen detection system for a machine as described in claim 1, wherein the fan blows cooling air into a machine room in which at least one of the hydrogen tank, the hydrogen power source, and the hydrogen distribution path are located.

13. A hydrogen detection system for a machine as described in claim 1, further comprising a rotation speed detection sensor that detects the rotation speed of the fan, and wherein the controller determines the amount of hydrogen detected by the hydrogen leak detection sensor based on whether the rotation speed of the fan detected by the rotation speed detection sensor is equal to or lower than a predetermined rotation speed.

14. A hydrogen detection method for a machine having a hydrogen tank, a hydrogen power source that is a power source that utilizes hydrogen stored in the hydrogen tank, and a fan, wherein the fan blows cooling air toward at least one of the hydrogen tank, the hydrogen power source, and a hydrogen distribution path connecting the hydrogen tank and the hydrogen power source, the hydrogen detection method for the machine comprising the steps of: acquiring the rotation speed of the fan; acquiring an amount of hydrogen outside the hydrogen tank; and determining the amount of hydrogen acquired based on whether the acquired rotation speed of the fan is equal to or lower than a predetermined rotation speed.

15. A hydrogen detection method for a machine as described in claim 14, further comprising the step of controlling an on-off valve for opening and closing the hydrogen tank to close when it is determined that the amount of hydrogen acquired is equal to or greater than a predetermined amount of hydrogen when the rotation speed of the fan falls below the predetermined rotation speed.

16. A hydrogen detection method for a machine as described in claim 14, further comprising controlling the fan so that the rotation speed of the fan becomes equal to or lower than a predetermined rotation speed at a timing when a first predetermined time has elapsed since the start of hydrogen supply from the hydrogen tank to the hydrogen power source.

17. A hydrogen detection method for a machine as described in claim 14, further comprising controlling the fan so that the rotation speed of the fan becomes equal to or lower than the predetermined rotation speed at a timing set in advance a second predetermined time before the supply of hydrogen from the hydrogen tank to the hydrogen power source is stopped.

18. The method for detecting hydrogen in a machine according to claim 14, further comprising controlling the fan so that the rotation speed of the fan is equal to or lower than the predetermined rotation speed at the timing when the fan is reversed from forward rotation to reverse rotation.

19. The method of claim 14, wherein in said step of obtaining an amount of hydrogen, the amount of hydrogen is obtained continuously.

20. The method of claim 14, wherein in said step of obtaining an amount of hydrogen, the amount of hydrogen is obtained temporarily.

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