Fuel cell device

Abstract

To provide a fuel cell device that can prevent hydrogen gas from remaining inside a cover for a long period of time.SOLUTION: A fuel cell device 1 includes a fuel cell 10, a supply piping unit 2, a hydrogen sensor 3 that detects hydrogen gas, and a gas collection cover 4 that covers the upper part of the supply piping unit 2 and has a storage space 400 that opens downward. The gas collection cover 4 includes a first recess 411 formed in the uppermost part of the cover where the inner wall of the cover is recessed upward, and a through-hole 410a provided in the cover area around the recess 411 that connects the storage space 400 to the outside space, and the hydrogen sensor 3 is provided at the bottom of the recess 410a.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a fuel cell device. [Background technology]

[0002] Fuel cell vehicles are equipped with fuel cells that use hydrogen as fuel gas. Such fuel cell vehicles are provided with a hydrogen sensor for detecting hydrogen leaks. For example, in the fuel cell vehicle described in Patent Document 1, a cover member that opens downward is provided to cover the top of the fuel cell, and a hydrogen sensor that detects hydrogen is located at the top inside the cover member. In the event of a hydrogen gas leak, the hydrogen gas rises inside the cover member and is detected by the hydrogen sensor located at the top inside the cover member. When a hydrogen gas leak is detected, the fuel cell system is shut down to avoid the danger of hydrogen gas leaks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-79347 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the cover member configuration described above, even after the fuel cell system is shut down due to leak detection, there is a possibility that high-concentration hydrogen gas may remain in the downward-opening cover member for a long time. Furthermore, if the hydrogen sensor located at the top of the cover member is exposed to hydrogen gas for a long time, this may lead to sensor degradation. [Means for solving the problem]

[0005] A fuel cell device according to one aspect of the present invention comprises a fuel cell, a piping unit comprising a gas supply passage for supplying hydrogen gas to the fuel cell, a gas exhaust passage for discharging excess gas from the fuel cell after power generation, and a return passage branching from the gas exhaust passage and connected to the gas supply passage, a hydrogen sensor for detecting hydrogen gas, and a gas collection cover covering the upper part of the piping unit and having a storage space that opens downward. The gas collection cover has a first recess formed in the uppermost part of the cover and recessed upward in the inner wall of the cover, and a through-hole provided in the cover area surrounding the first recess and communicating the storage space with an external space, and the hydrogen sensor is provided at the bottom of the first recess. [Effects of the Invention]

[0006] According to the present invention, it is possible to prevent hydrogen gas from remaining inside the cover for a long period of time. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the appearance of the fuel cell device of this embodiment. [Figure 2] FIG. 2 is a diagram showing an example of a vehicle equipped with a fuel cell device. [Figure 3] FIG. 3 is a cross-sectional view showing the AA cross section of FIG. [Figure 4] FIG. 4 is a perspective view showing the appearance of the gas collecting cover. [Figure 5] FIG. 5 is a cross-sectional view of a gas collection cover with a hydrogen sensor attached. [Figure 6] FIG. 6 is a diagram showing a first modified example of the gas collecting cover. [Figure 7] FIG. 7 is a diagram showing a second modified example of the gas collecting cover. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and appropriate omissions and simplifications have been made for clarity of explanation. Furthermore, in the following description, identical or similar elements and processes are designated by the same reference numerals, and redundant explanations may be omitted. Note that the content described below merely shows an example of an embodiment of the present invention, and the present invention is not limited to the following embodiment, and can be implemented in various other forms.

[0009] FIG. 1 is a diagram showing the appearance of a fuel cell device 1 of this embodiment. The fuel cell device 1 of this embodiment is mounted on a commercial vehicle such as a truck as shown in FIG. 2, but can also be used on large ships and stationary power sources. As shown in FIG. 2, in the case of a large truck, the device is placed on a frame below the cabin where the driver's seat is located. In the case of a small or medium-sized truck, the device is placed in the engine room or the like.

[0010] The fuel cell device 1 includes a fuel cell, a system for supplying anode gas and cathode gas to the fuel cell, and a hydrogen detection system for detecting leaks of hydrogen gas, which is the cathode gas. The fuel cell is housed inside a case 11. In FIG. 1, the hatched area represents a supply piping unit 2, which is made up of the equipment and piping of the cathode gas supply system. A gas collection cover 4 equipped with a hydrogen sensor 3 for detecting hydrogen is disposed above the supply piping unit 2. The gas collection cover 4 is a cover for collecting hydrogen gas that leaks from the supply piping unit 2, and is fixed to the case 11 by brackets 5a and 5b. Possible locations in the supply piping unit 2 from which hydrogen gas may leak include parts made of resin, the interface between resin parts and metal parts, and piping connections.

[0011] FIG. 3 is a diagram showing an example of the schematic configuration of a fuel cell device 1 mounted on a vehicle. The fuel cell 10 is made by stacking a plurality of power generation cells, and the stack of power generation cells is housed in a case 11. The power generation cell has a polymer electrolyte membrane sandwiched between an anode and a cathode, and further has separators arranged to face the anode and cathode, respectively. The separator arranged facing the anode has an anode flow path c1 through which anode gas (hydrogen gas) flows. The separator arranged facing the cathode has a cathode flow path c2 through which cathode gas (air) flows.

[0012] The case 11 that houses the fuel cell 10 has an anode gas supply port 110 for introducing anode gas and a post-reaction anode gas outlet 111 for discharging post-reaction anode gas (residual hydrogen gas) after power generation. The case 11 also has a cathode gas supply port 112 for introducing cathode gas and a post-reaction cathode gas outlet 113 for discharging post-reaction cathode gas after power generation.

[0013] A hydrogen tank 12 is connected to the anode gas supply port 110 via a pipe a1, a shutoff valve 13, a pipe a2, an injector (injection device) 14, and a pipe a3. A purge valve 15 is connected to a pipe a4 connected to the post-reaction anode gas discharge port 111. A reflux pipe a5 branches off from the pipe a4 at a position upstream of the purge valve 15. The reflux pipe a5 is connected to a return port of the injector 14. The injector 14 injects a mixed gas obtained by mixing hydrogen gas from the hydrogen tank 12 with post-reaction anode gas (hydrogen gas) from the reflux pipe a5 into the pipe a3 connected to the anode gas supply port 110.

[0014] The shutoff valve 13 and the purge valve 15 are electromagnetically operated valves, and are appropriately controlled to open and close by a control device 19. The purge valve 15 is opened, for example, periodically to discharge impurities remaining in the anode circulation system (pipes a3 and a4, reflux pipe a5, and anode flow path c1) to the outside.

[0015] An air compressor 16 is connected to the cathode gas supply port 112 via a pipe b1, a humidifier 17, and a pipe b2. A back pressure valve 18 is connected to the post-reaction cathode gas discharge port 113 via a pipe b3, the humidifier 17, and a pipe b4. The amount of air supplied to the cathode gas supply port 112 by the air compressor 16 is controlled by a control device 19. The back pressure valve 18 controls the pressure (cathode pressure) of the air supplied to the cathode gas supply port 112 by the control device 19. For example, the cathode pressure is controlled in accordance with the depression amount of the accelerator pedal of the vehicle (throttle opening).

[0016] The humidifier 17 removes moisture (water vapor) from the post-reaction cathode gas discharged from the post-reaction cathode gas outlet 113 and humidifies the air supplied to the cathode gas supply port 112. For example, the humidifier 17 uses a hollow fiber membrane bundle formed by bundling a plurality of water-permeable hollow fiber membranes, and the humidifying operation is performed by having air from the air compressor 16 flow to one side of the inside or outside of each hollow fiber membrane, and having the post-reaction cathode gas discharged from the post-reaction cathode gas outlet 113 flow to the other side. A detection signal from the hydrogen sensor 3 is input to the control device 19. When the hydrogen sensor 3 detects a hydrogen gas leak, the control device 19 provides a visual and / or audible warning to the driver and performs control such as stopping power generation by the fuel cell 10 and stopping the vehicle.

[0017] The supply piping unit 2 shown in Fig. 1 includes some or all of the pipes a1 to a5, shutoff valve 13, injector 14, purge valve 15, anode gas supply port 110, post-reaction anode gas discharge port 111, and hydrogen tank 12, which are provided on the anode gas path in Fig. 3. In the example shown in Fig. 3, the hydrogen tank 12 is included in the fuel cell device 1, but a hydrogen tank provided separately from the fuel cell device 1 may also be mounted on the vehicle.

[0018] 4 and 5 are diagrams illustrating the gas collection cover 4. FIG. 4 is a perspective view showing the appearance of the gas collection cover 4. FIG. 5 is a cross-sectional view of the gas collection cover 4 with the hydrogen sensor 3 attached, taken along a plane perpendicular to the x-axis in FIG. 1. The gas collection cover 4 is formed from a metal plate or a gas-impermeable resin material that does not allow hydrogen to pass through. The gas-impermeable resin material can be appropriately selected from synthetic resins such as EVOH (ethylene-vinyl alcohol copolymer), PVA (polyvinyl alcohol), and PP (polypropylene).

[0019] The gas collection cover 4 includes a flat ceiling portion 41, sidewall portions 42 extending downward from the edge of the ceiling portion 41, and a fixing portion 43. The fixing portion 43 is fixed to brackets 5a and 5b (see FIG. 1) attached to the case 11. The holes 430 are fastening holes for bolting the fixing portion 43 to the brackets 5a and 5b. A space 400 (FIG. 5) surrounded by the ceiling portion 41 and the sidewall portions 42 is a space for storing leaked hydrogen gas for detection, and hereinafter this space will be referred to as the storage space 400. A lower end portion 420 of the sidewall portions 42 surrounding the storage space 400 forms an opening that opens downward in the storage space 400. hereinafter, the lower end portion 420 may also be referred to as the opening 420.

[0020] A recess 410 is formed in the flat ceiling portion 41, with the wall portion deformed so as to be recessed upward. The term "recess" in recess 410 refers to the shape when viewed from the storage space 400 side, and as shown in FIG. 4, the outer peripheral surface side of ceiling portion 41 has a shape that protrudes upward. As shown in FIG. 5, a recess 411 that is further recessed upward is formed in the bottom of recess 410. A plurality of ventilation through-holes 410a are provided in the bottom of recess 410 around the opening of recess 411. A through-hole 412 is formed in the central region of the bottom of recess 411. A hydrogen sensor 3 is fixed to the outer peripheral surface (i.e., the upper surface) side of the bottom of recess 411.

[0021] The gas collection cover 4 is fixed to the brackets 5a and 5b so that the ceiling portion 41 is approximately horizontal. Therefore, the bottom of the recess 410 formed in the ceiling portion 41 is the uppermost portion of the gas collection cover 4 in the vertical direction. The recess 411 has a recessed shape that is recessed upward from the bottom of the recess 410, which is the uppermost portion. Hydrogen gas leaking from the supply piping unit 2 shown in FIG. 1 is lighter than air and therefore rises upward. Therefore, some of the leaked hydrogen gas enters the storage space 400 through the opening 420 of the gas collection cover 4. Hereinafter, within the storage space 400 of the gas collection cover 4, the recessed region formed by the recess 411 will be referred to as the first storage space 400a, the recessed region formed by the recess 410 will be referred to as the second storage space 400b, and the area below the second storage space 400b will be referred to as the third storage space 400c.

[0022] The hydrogen gas that has entered the storage space 400 moves toward the ceiling portion 41, and moves from the second storage space 400b in the recess 410 to the first storage space 400a. In this way, the leaked hydrogen gas that has entered the storage space 400 accumulates in the first storage space 400a, the second storage space 400b, and the third storage space 400c, starting from the upper side of the gas collecting cover 4. The hydrogen gas concentration increases in the order of the third storage space 400c, the second storage space 400b, and the first storage space 400a, with the first storage space 400a showing the earliest increase in hydrogen gas concentration. The hydrogen gas in the first storage space 400a then reaches the detection unit 30 of the hydrogen sensor 3 through the through-hole 412.

[0023] As described above, if a hydrogen gas leak occurs, the leaked hydrogen gas will accumulate in the gas collection cover 4, and when the hydrogen concentration detected by the hydrogen sensor 3 reaches a predetermined level (1% to 4%) or higher, it is determined that a hydrogen leak has occurred. If a hydrogen leak is determined, the hydrogen gas supply line is cut off and the fuel cell system is shut down.

[0024] Incidentally, if the fuel cell system is shut down due to hydrogen leak detection and the hydrogen gas accumulated in the storage space 400 is naturally ventilated only through the opening 420, there is a possibility that dangerously high concentrations of hydrogen may remain in the gas collection cover 4 for a long time. In addition, if the hydrogen sensor 3 is a catalytic combustion type hydrogen sensor, it will constantly react with the accumulated hydrogen gas, causing deterioration of the detection unit 30. Furthermore, the combustion heat generated when hydrogen reacts with the catalyst causes Si to react with siloxane in the air and oxidize, reducing the reaction area with hydrogen gas and causing deterioration of the sensitivity of the hydrogen sensor 3.

[0025] Therefore, the gas collection cover 4 of this embodiment is provided with ventilation through-holes 410a to prevent the occurrence of the above-mentioned problems. As shown in FIG. 5, the through-holes 410a are provided at the bottom of the recess 410 around the opening of the recess 411. Therefore, hydrogen gas in the storage space 400 is discharged upward through the through-holes 410a. When the leaked hydrogen gas decreases after the system is stopped due to leak detection, the hydrogen gas in the storage space 400 is discharged through the through-holes 410a and air flows in through the opening 420, resulting in smooth ventilation. As a result, the hydrogen gas concentration decreases in the third storage space 400c, the second storage space 400b, and the first storage space 400a in that order. This allows the hydrogen concentration in the region facing the detection unit 30 to decrease more quickly than when the through-holes 410a are not present.

[0026] (Variation 1) 6 is a diagram showing a first modified example of the gas collection cover 4. In the first modified example, the recess 410 (second storage space 400b) shown in FIG. 5 is omitted, and the recess 411 is formed directly in the flat ceiling portion 41. That is, in the first modified example, the ceiling portion 41 is the uppermost part of the gas collection cover 4, and a ventilation through-hole 410a is provided in the ceiling portion 41. The other configuration of the gas collection cover 4 is the same as that of the gas collection cover 4 shown in FIG.

[0027] When the amount of leaked hydrogen gas decreases after the system is shut down due to leak detection, the hydrogen gas in the storage space 400 is discharged through the through-hole 410a and air flows in through the opening 420, causing the hydrogen gas concentration to decrease in the third storage space 400c and then the first storage space 400a. In the case of the first modification, the hydrogen concentration in the region facing the detection unit 30 can also be reduced more quickly than when there is no through-hole 410a.

[0028] However, the shape of the ceiling portion 41 shown in Fig. 5 is superior in terms of strength of the gas collecting cover 4. In the configuration shown in Fig. 5, the uneven shape of the ceiling portion 41 is formed over a wide area, so the strength of the gas collecting cover 4 can be increased more than in the configuration of Fig. 6, which has a wide flat area.

[0029] (Variation 2) FIG. 7 shows a second modified example of the gas collection cover 4. In the configuration shown in FIG. 5, a recess 410 is provided in the ceiling portion 41 to form the second storage space 400b. However, in the second modified example, the recess 410 is omitted, and the entire ceiling portion is formed of an inclined ceiling portion (inclined portion) 41a, which is made up of an inclined surface. The inclined ceiling portion 41a is formed of an inclined wall that slopes downward from the edge of the recess 411 toward the side wall portion 42. The area surrounded by the inclined wall of the inclined ceiling portion 41a is the second storage space 400b. A plurality of ventilation through-holes 410a are formed in the inclined ceiling portion 41a. The through-holes 410a are preferably arranged in an area close to the recess 411. The other configuration of the gas collection cover 4 is the same as that of the gas collection cover 4 shown in FIG. 5.

[0030] 5 and 6, the upper surfaces of the walls of both the ceiling portion 41 and the recess 410 in which the through-hole 410a is provided are horizontal, which raises the risk of foreign matter adhering to the top of the cover and blocking the through-hole 410a. In Modification 2, the inclined ceiling portion 41a has an inclined surface that slopes downward toward the side wall portion 42, which makes it difficult for foreign matter to slide down the inclined surface and adhere to it, reducing the likelihood of the through-hole 410a being blocked by foreign matter. This prevents a decrease in the ventilation performance of the through-hole 410a due to the adhesion of foreign matter, etc.

[0031] The various embodiments and modifications described above are merely examples, and the present invention is not limited to these unless the features of the invention are impaired. Other embodiments that are conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention. [Explanation of symbols]

[0032] 1... fuel cell device, 2... supply piping unit, 3... hydrogen sensor, 4... gas collection cover, 10... fuel cell, 11... case, 12... hydrogen tank, 13... shut-off valve (regulating device), 14... injector (injection device), 15... purge valve, 16... air compressor, 17... humidifier, 18... back pressure valve, 19... control device, 30... detection unit, 41... ceiling portion, 41a... inclined ceiling portion, 42... side wall portion, 43... fixing portion, 110... a Node gas supply port, 111...post-reaction anode gas discharge port, 112...cathode gas supply port, 113...post-reaction cathode gas discharge port, 400...storage space, 400a...first storage space, 400b...second storage space, 400c...third storage space, 410...recess (second recess), 411...recess (first recess), 410a, 412...through holes, 420...lower end (opening), a1 to a4, b1 to b4...pipes, a5...reflux pipe

Claims

1. A fuel cell; a piping unit that includes a gas supply path that supplies hydrogen gas to the fuel cell, a gas exhaust path that exhausts excess gas from the fuel cell after power generation, and a return path that branches off from the gas exhaust path and is connected to the gas supply path; a hydrogen sensor for detecting hydrogen gas; a gas collection cover that covers the upper part of the piping unit and has a storage space that opens downward, The gas collection cover is a first recess formed in the uppermost portion of the cover, the first recess being an upward recess in the inner wall of the cover; a through-hole provided in a cover region around the first recess and communicating the storage space with an external space; The fuel cell device is characterized in that the hydrogen sensor is provided at the bottom of the first recess.

2. 2. The fuel cell device according to claim 1, The piping unit comprises at least one of a case that houses the fuel cell, a hydrogen tank that stores hydrogen gas, a supply pipe from the hydrogen tank to the case, an exhaust pipe that exhausts the excess gas from the case, a reflux pipe for the reflux path, an adjusting device that adjusts the flow rate of hydrogen gas, and an injection device that injects hydrogen gas and supplies it to the fuel cell.

3. 2. The fuel cell device according to claim 1, A fuel cell device, wherein the cover area around the first recess forms a sloped portion that slopes downward toward the opening of the storage space.

4. 4. The fuel cell device according to claim 3, The uppermost portion of the cover further includes a second recess in which the inner wall of the cover is recessed upward, the first recess is formed to be recessed upward from a bottom of the second recess, The fuel cell device is characterized in that the through hole is provided in the bottom of the second recess.

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