fuel cells

Abstract

To provide a fuel battery having a structure that makes it difficult for water to adhere to a pressure sensor attached to a fuel pipe.SOLUTION: A fuel battery according to the present specification includes a fuel battery stack, a fuel pipe that supplies fuel to the fuel cell stack, and a pressure sensor that measures the pressure inside the fuel pipe. The fuel pipe includes an outer pipe and an inner pipe inserted into the outer pipe. The gap between the outer pipe and the inner pipe is sealed at two points in the longitudinal direction of the fuel pipe. Between the two points, a first through hole is provided in the upper part of the outer pipe and a second through hole is provided in the lower part of the inner pipe. A pressure sensor is attached to the first through hole.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a fuel cell. [Background technology]

[0002] Patent documents 1-3 exemplify fuel cells. The fuel cell includes a fuel cell stack and a fuel pipe connecting the fuel cell stack to a fuel tank. A pressure sensor is attached to the fuel pipe. Water can get into the fuel pipe. If water in the fuel pipe adheres to the pressure sensor, it can cause a malfunction of the pressure sensor. In the fuel cell of Patent document 1, the vibration of a hydrogen circulation pump connected to the fuel pipe prevents water from adhering to the pressure sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-188254 A [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-280696 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-244786 Summary of the Invention [Problem to be solved by the invention]

[0004] The present specification provides a structure that makes it difficult for water to adhere to a pressure sensor attached to a fuel pipe. [Means for solving the problem]

[0005] The fuel cell disclosed in this specification includes a fuel cell stack, a fuel pipe that supplies fuel to the fuel cell stack, and a pressure sensor that measures the pressure inside the fuel pipe. The fuel pipe includes an outer pipe and an inner pipe inserted into the outer pipe. The gap between the outer pipe and the inner pipe is sealed at two locations in the longitudinal direction of the fuel pipe. Between the two locations, a first through-hole is provided in the upper part of the outer pipe and a second through-hole is provided in the lower part of the inner pipe. A pressure sensor is attached to the first through-hole.

[0006] Fuel gas containing water flows inside the inner pipe. The force of the fuel gas can cause the water to splash around inside the inner pipe, but it is difficult for the water to enter the gap between the inner and outer pipes. In particular, since the second through-hole (hole in the inner pipe) is located at the bottom of the inner pipe and the first through-hole (hole in the outer pipe) is located at the top of the outer pipe, water that enters the gap through the second through-hole does not reach the first through-hole. This prevents water from adhering to the pressure sensor.

[0007] Details and further improvements of the technology disclosed in this specification are described in the following "Description of Embodiments of the Invention." [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a fuel cell according to an embodiment. [Figure 2] FIG. 2 is a perspective view of the vicinity of a pressure sensor of the fuel cell. [Figure 3] FIG. 2 is a plan view of the vicinity of a pressure sensor of the fuel cell. [Figure 4] FIG. 4 is a cross-sectional view of the fuel cell taken along line IV-IV in FIG. [Figure 5] FIG. 4 is a cross-sectional view of the fuel cell taken along line VV in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A fuel cell 2 according to an embodiment will be described with reference to the drawings. Hereinafter, for ease of explanation, "fuel cell" may be abbreviated as "FC." "Fuel cell stack" may be abbreviated as "FC stack." Figure 1 shows a block diagram of an FC2 (fuel cell 2). The FC2 comprises an FC stack 3, a fuel tank 4, a compressor 5, and an injector 7. Fuel (hydrogen gas) from the fuel tank 4 is supplied to the FC stack 3 through a fuel pipe 10. An injector 7 and a pressure sensor 20 are attached midway along the fuel pipe 10. The injector 7 injects the fuel from the fuel tank 4 at an appropriate pressure. The pressure sensor 20 is provided between the FC stack 3 and the injector 7, and measures the pressure of the fuel supplied to the FC stack 3.

[0010] Outside air (oxygen) is supplied to the FC stack 3 from a compressor 5. As is well known, the FC stack 3 generates electricity by causing the oxygen contained in the air to react with fuel (hydrogen gas) supplied from a fuel tank 4. The electricity generated by the FC stack 3 is sent to an electric device 90.

[0011] After the reaction, the fuel is separated into reusable fuel gas and water in a gas-liquid separator 6. The reusable fuel gas is returned to the injector 7 via a return pipe 9. The water is discharged together with the post-reaction air through a muffler 8. Note that the structure of the FC2 is greatly simplified in Figure 1.

[0012] After the reaction, the fuel is separated into reusable fuel gas and water in gas-liquid separator 6, but some of the water remains as steam and is mixed into the fuel gas. Therefore, a relatively large amount of water (steam) is contained in fuel pipe 10 between injector 7 and FC stack 3. A pressure sensor 20 is attached to fuel pipe 10 between injector 7 and FC stack 3. If water adheres to the sensor element of pressure sensor 20, it may affect measurement accuracy. In FC2 of the embodiment, fuel pipe 10 has been improved so that water is less likely to adhere to the sensor element of pressure sensor 20. Next, the structure of fuel pipe 10 will be described.

[0013] Figure 2 shows a perspective view of the area around the pressure sensor 20. The fuel pipe 10 comprises an outer pipe 11 connected to the FC stack 3, and an inner pipe 12 connected to the injector 7 and also connected to the outer pipe 11. The inner diameter of the outer pipe 11 is larger than the outer diameter of the inner pipe 12. The inner pipe 12 is inserted inside the outer pipe 11. As will be described in more detail later, the outer pipe 11 and inner pipe 12 are sealed at two points. In Figure 2 (and subsequent figures), the FC stack 3 and injector 7 are depicted in a simplified form.

[0014] Both the outer pipe 11 and the inner pipe 12 are made of metal. A flange 17 is provided at one end of the outer pipe 11, and this flange 17 is fixed to the outer wall of the FC stack 3 with bolts 31. A flange 18 is also provided at one end of the inner pipe 12, and this flange 18 is fixed to the outer wall of the injector 7 with bolts 32. The injector 7 is fixed to the outer wall of the FC stack 3 with bolts 33. With this structure, the metal fuel pipe 10 is firmly fixed to the FC stack 3. A pressure sensor 20 is attached to the outer pipe 11. As the fuel pipe 10 is firmly supported by the FC stack 3, the pressure sensor 20 is also indirectly firmly supported by the FC stack 3.

[0015] 3 shows a plan view of the vicinity of the pressure sensor 20. As shown in Fig. 3, the fuel pipe 10 bends at a right angle between the FC stack 3 and the injector 7. The pressure sensor 20 is adjacent to the FC stack 3.

[0016] A cross section taken along line IV-IV in Figure 3 is shown in Figure 4, and a cross section taken along line VV in Figure 3 is shown in Figure 5. Figure 4 shows a longitudinal cross section taken along the longitudinal direction of the fuel pipe 10, and Figure 5 shows a cross section taken across the fuel pipe 10. Note that the +Z direction of the coordinate system in the figure corresponds to the vertically upward direction. The X and Y axes of the coordinate system in the figure are parallel to the horizontal. Between the FC stack 3 and the injector 7, the fuel pipe 10 is positioned so that its longitudinal direction is horizontal.

[0017] As described above, the inner pipe 12 is inserted inside the outer pipe 11. A gap G is provided between the outer periphery of the outer pipe 11 and the inner periphery of the inner pipe 12. Furthermore, the gap between the outer periphery of the outer pipe 11 and the inner periphery of the inner pipe 12 is sealed by two O-rings 19a and 19b. In other words, the gap between the outer periphery of the outer pipe 11 and the inner periphery of the inner pipe 12 is sealed at two locations along the length of the fuel pipe 10. Between the two sealed locations, a first through-hole 13 is provided in the upper part of the outer pipe 11, and a second through-hole 14 is provided in the lower part of the inner pipe 12. In other words, the gap G between the outer pipe 11 and the inner pipe 12 is in communication with the space inside the inner pipe 12 and is isolated from the space outside the fuel pipe 10. The pressure in the gap G corresponds to the pressure inside the inner pipe 12, i.e., the internal pressure of the fuel pipe 10.

[0018] A resin body 22 of the pressure sensor 20 is attached to the first through hole 13 of the outer pipe 11. The resin body 22 is fixed to a block 15 provided on the outside of the outer pipe 11 with bolts 34. A pressure sensor element 21 is attached to the resin body 22 so as to be exposed to the first through hole 13. The space to which the pressure sensor element 21 is exposed is connected to the space inside the fuel pipe 10 through the first through hole 13 and the second through hole 14. This structure enables the pressure sensor element 21 to measure the pressure inside the fuel pipe 10. A metal terminal 23 is provided on the resin body 22, and the metal terminal 23 is connected to the pressure sensor element 21. A portion of the metal terminal 23 is exposed to the outside space so that it can be connected to an external connector.

[0019] The flow velocity of the fuel gas discharged from the injector 7 is high, and there is a risk of water (water vapor) splashing inside the fuel pipe 10. The fuel pipe 10 has a double structure at the attachment point of the pressure sensor 20 (pressure sensor element 21). This structure makes it difficult for water contained in the fuel to adhere to the pressure sensor element 21. In particular, the following structural features make it difficult for water to adhere to the pressure sensor element 21.

[0020] The second through-hole 14 is provided on the vertically lower side of the inner pipe 12, and the first through-hole 13 is provided on the vertically upper side of the outer pipe 11. The outer wall of the inner pipe 12 faces the first through-hole 13. The pressure sensor element 21 is disposed vertically above the outer pipe 11.

[0021] Furthermore, the fuel gas flows from the inner pipe 12 toward the outer pipe 11. By arranging the outer pipe 11 downstream of the inner pipe 12 (downstream of the flow of the fuel gas), water contained in the fuel gas does not hit hard against the O-ring 19a that seals between the outer pipe 11 and the inner pipe 12. By fixing the inner pipe 12 to the injector 7 and fixing the outer pipe 11 to the FC stack 3, the outer pipe 11 is arranged downstream of the inner pipe 12.

[0022] FIG. 5 shows a cross section that intersects the longitudinal direction of the fuel pipe 10 and cuts across the first through hole 13 and the second through hole 14. In this cross section, the vertical height Ha (vertical position Ha) of one edge 14a of the second through hole 14 is higher than the height Hb (vertical position Hb) of the other edge 14b. The smaller the width of the second through hole 14 in the cross section of FIG. 5, the better. However, if the width of the second through hole 14 is too small, there is a risk that the gap G will be isolated from the internal space of the inner pipe 12 when water freezes at the bottom of the outer pipe 11. By making the heights of the edges 14a and 14b different, communication between the internal space of the inner pipe 12 and the gap G on the side of the other edge 14a is ensured even if the other edge 14b becomes clogged with ice.

[0023] Here are some points to note about the technology explained in the examples. The pressure sensor 20 is supported by the FC stack 3 via a metal outer tube 11. This prevents the pressure sensor 20 from shaking. The pressure sensor 20 is placed next to the FC stack 3. The FC stack 3 generates heat through a reaction between hydrogen and oxygen. The heat from the FC stack 3 is also transferred to the pressure sensor 20 via the metal outer tube 11. The heat from the FC stack 3 makes it difficult for water to freeze near the pressure sensor 20.

[0024] The inner pipe 12 is fixed to the injector 7, and the injector 7 is fixed to the FC stack 3. Both ends of the fuel pipe 10 are supported by the FC stack 3, so that the fuel pipe 10 (i.e., the pressure sensor 20) is firmly supported.

[0025] A filter 35 is attached to the fuel pipe 10 upstream of the pressure sensor 20. The filter 35 removes dust contained in the fuel discharged from the injector 7.

[0026] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives alone is technically useful. [Explanation of symbols]

[0027] 2: Fuel cell 3: FC stack 4: Fuel tank 5: Compressor 6: Gas-liquid separator 7: Injector 8: Muffler 9: Return pipe 10: Fuel pipe 11: Outer pipe 12: Inner pipe 13: First through-hole 14: Second through-hole 15: Block 17, 18: Flange 19a, 19b: O-ring 20: Pressure sensor 21: Pressure sensor element 22: Resin body 23: Metal terminal 31, 32, 33, 34: Bolt 35: Filter

Claims

1. a fuel cell stack; a fuel pipe for supplying fuel to the fuel cell stack; a pressure sensor that measures the pressure in the fuel pipe; It is equipped with the fuel pipe includes an outer pipe and an inner pipe inserted into the outer pipe, and a gap between the outer pipe and the inner pipe is sealed at two locations in the longitudinal direction of the fuel pipe; Between the two locations, a first through hole is provided in the upper part of the outer tube and a second through hole is provided in the lower part of the inner tube, The pressure sensor is attached to the first through hole. fuel cell.

2. 2. The fuel cell according to claim 1, wherein in a cross section intersecting the longitudinal direction and traversing the second through hole, one edge of the second through hole has a higher vertical height than the other edge.

3. 3. The fuel cell according to claim 1, wherein the outer tube is fixed to the fuel cell stack.

4. 4. The fuel cell according to claim 3, wherein the inner tube is fixed to an injector that injects fuel.

5. The fuel cell of claim 4 , wherein the injector is fixed to the fuel cell stack.

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