FUEL CELL SYSTEM

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a fuel cell system.

2. Description of the Related Art

[0002] Japanese Patent Application Publication No. 2005-116226 (JP-A-2005-116226) describes a fuel cell system that includes pipes fitted to a fuel cell stack, and connected to manifolds inside the fuel cell stack. A reactant gas needs to be supplied to each fuel cell in the fuel cell stack so that electric power is generated in the fuel cell system. Also, it is preferable to maintain the temperature of each fuel cell at an appropriate temperature by supplying a coolant in the fuel cell stack, to maintain the fuel cell system in a good power generation state.

[0003] In order to achieve the objects, manifolds, which are connected to the fuel cells, are provided in the conventional fuel cell stack. The reactant gas and the coolant flow through the manifolds. The pipes, which are connected to the manifolds, are provided so that the gases and the like flow to and from the manifolds through the pipes. [0004] The operation of fitting the pipes to the fuel cell stack may be complicated, depending on the configuration of the pipes. Accordingly, in the above-described conventional fuel cell system, pipes are assembled to provide more appropriate pipe components, that is, to make it easier to fit the pipes to the fuel cell stack, and to reduce the number of components. [0005] Technologies related to the invention are described in. Japanese Patent

Application Publication No. 2005-228542 (JP-A-2005-228542), Japanese Patent Application Publication No. 2001-76751 (JP-A-2001-76751), Japanese Patent Application Publication No. 2006-221915 (JP-A-2006-221915), Japanese Patent Application Publication No. 2005-332674 (JP-A-2005-332674), Japanese Patent

Application Publication No. 2002-367637 (JP-A-2002-367637), Japanese Patent Application Publication No. 2002-362164 (JP-A-2002-362164), and the like, in addition to the above-described publication No. 2005-116226.

[0006] In the above-described fuel cell system, however, each of the pipe components needs to be fitted to the fuel cell stack. Therefore, the operation of fitting the pipes to the fuel cell stack is complicated, and the number of man-hours required for fitting the pipes to the fuel cell stack is large. Thus, improvement needs to be made to provide an appropriate pipe component.

SUMMARY OF THE INVENTION

[0007] The invention provides a fuel cell system in which a pipe component with a simplified configuration is fitted to a fuel cell stack.

[0008] An aspect of the invention relates to a fuel cell system that includes: a fuel cell stack in which a plurality of fuel cells and a plurality of manifolds are provided, and outlets/inlets of the manifolds are formed in one surface; a pipe component which is one component formed of resin, and is fitted to the fuel cell stack, and which includes a contact portion that contacts the one surface of the fuel cell stack, and a plurality of fluid passages that extend from positions in the contact portion, the positions corresponding to the outlets/inlets of the respective manifolds, wherein the fluid passages are connected to the respective manifolds when the pipe component is fitted to the one surface of the fuel cell stack.

[0009] In the above-described fuel cell system, the pipe component, which is fitted to the fuel cell stack, is one component formed of resin. Therefore, the number of components is reduced, and the pipe component can be fitted to the fuel cell stack extremely easily.

[0010] In the fuel cell system, the fluid passages of the pipe component may extend through the pipe component from the positions in the contact portion, the positions corresponding to the outlets/inlets of the respective manifolds.

[0011] In the above-described fuel cell system, the plurality of fluid passages

extend through the pipe component. Thus, the pipes with the complicated configurations can be formed in one component.

[0012] In the above-described fuel cell system, the manifolds may include a gas supply manifold through which gas to be supplied to the fuel cells flows, and a gas discharge manifold through which gas discharged from the fuel cells flows.

[0013] In the above-described fuel cell system, when the pipe component is fitted to the fuel cell stack that includes different types of manifolds, that is, the gas supply manifold and the gas discharge manifold, it is possible to reduce the number of components, and to fit the pipe component to the fuel cell stack extremely easily. [0014] In the above-described fuel cell system, the manifolds may include a coolant flow manifold through which a coolant that cools the fuel cells flows; and among the fluid passages, a fluid passage connected to the coolant flow manifold may be adjacent to a fluid passage connected to the gas discharge manifold.

[0015] In the above-described fuel cell system, heat is exchanged between the coolant flowing in a cooling system of the fuel cell system, and an off-gas flowing in the gas discharge manifold.

[0016] In the above-described fuel cell system, the manifolds may include a coolant flow manifold through which a coolant that cools the fuel cells flows; the gas supply manifold may include a hydrogen supply manifold through which hydrogen to be supplied to the fuel cells flows; and among the fluid passages, a fluid passage connected to the hydrogen supply manifold may be adjacent to a fluid passage connected to the coolant flow manifold.

[0017] In the above-described fuel cell system, the hydrogen to be supplied to the fuel cells can be warmed using the coolant flowing in the cooling system. [0018] Ih the above-described fuel cell system, the fluid passages may include a fluid passage in which an end portion that is not connected to the manifold extends in substantially parallel with the one surface of the fuel cell stack.

[0019] In the above-described fuel cell system, the end portion of the fluid passage extends in substantially parallel with the end surface of the fuel cell stack.

Therefore, it is possible to prevent the size of the structure around the fuel cell stack from being excessively increased in the fuel cell stacking direction.

[0020] In the above-described fuel cell system, the fluid passages may include a fluid passage that includes a portion that extends in substantially parallel with the one surface of the fuel cell stack.

[0021] In the above-described fuel cell system, a portion of the fluid passage extends in substantially parallel with the end portion of the fuel cell stack. Therefore, it is possible to prevent the size of the structure around the fuel cell stack from being excessively increased in the fuel cell stacking direction. [0022] In the above-described fuel cell system, the fluid passages may include a first fluid passage that extends in substantially parallel with the one surface of the fuel cell stack, and a second fluid passage that extends to overlap the first fluid passage at a position at which the second fluid passage is farther from the one surface than the first fluid passage is. [0023] In the above-described fuel cell system, the plurality of fluid passages are three-dimensionally formed in the pipe component that is one component. Thus, the pipes with complicated configurations can be formed in one component.

[0024] In the above-described fuel cell system, the manifolds may include a coolant flow manifold through which a coolant that cools the fuel cells flows; and one of the first fluid passage and the second fluid passage may be connected to the coolant flow manifold, and the other of the first fluid passage and the second fluid passage may be connected to a gas supply manifold through which gas to be supplied to the fuel cells flows, or a gas discharge manifold through which gas discharged from the fuel cells flows. [0025] In the above-described fuel cell system, the cooling liquid flows adjacent to the off-gas in the fluid passages that are three-dimensionally overlap each other. Thus, the pipes with the complicated configurations can be formed in one component, and heat is exchanged between the coolant and the off-gas.

[0026] In the above-described fuel cell system, the fluid passages may include a

first fluid passage that extends in substantially parallel with the one surface of the fuel cell stack, and a third fluid passage that three-dimensionally crosses the first fluid passage at a position at which the third fluid passage is farther from the one surface than the first fluid passage is. [0027] In the above-described fuel cell system, the plurality of fluid passages three-dimensionally cross each other in the pipe component that is one component. Thus, the pipes with the complicated configurations can be formed in one component.

[0028] In the above-described fuel cell system, the manifolds may include a coolant flow manifold through which a coolant that cools the fuel cells flows; and one of the first fluid passage and the third fluid passage may be connected to the coolant flow manifold, and the other of the first fluid passage and the third fluid passage may be connected to a gas supply manifold through which gas to be supplied to the fuel cells flows, or a gas discharge manifold through which gas discharged from the fuel cells flows. [0029] In the above-described fuel cell system, the cooling liquid flows adjacent to the off-gas in the fluid passages that are three-dimensionally overlap each other. Thus, the pipes with the complicated configurations can be formed in one component, and heat is transferred between the cooling liquid and the off-gas.

[0030] In the above-described fuel cell system, the manifolds may include a hydrogen supply manifold; and the fluid passages may include a hydrogen inlet passage that is a fluid passage connected to the hydrogen supply manifold, and a fluid passage that includes a portion that is farther from the one surface of the fuel cell stack (10) than a portion of the hydrogen inlet passage is.

[0031] In the above-described fuel cell system, among the plurality of fluid passages, the fluid passage in which the hydrogen flows is disposed inside (i.e., close to the end surface of the fuel cell stack), as compared to the other fluid passages. As a result, the fluid passage in which the hydrogen flows is protected from, for example, an impact applied from the outside.

[0032] In the above-described fuel cell system, the fluid passage may have a

substantially rectangular cross section in a direction perpendicular to a direction in which a fluid flows.

[0033] In the above-described fuel cell system, the plurality of fluid passages are made closer to each other, and the size of the pipe component is reduced. [0034] In the above-described fuel cell system, a shape and a size of a cross section of the fluid passage in a direction perpendicular to a direction in which a fluid flows may be gradually changed from a position close to the manifold.

[0035] In the above-described fuel cell system, the shape and the size of the cross section of the fluid passage are gradually changed. Thus, the fluid smoothly flows. [0036] In the above-described fuel cell system, end portions of at least two of the fluid passages, which are not connected to the manifolds, may be disposed at the substantially same position in the pipe component.

[0037] In the above-described fuel cell system, the end portions of the fluid passages are disposed close to each other at a certain position in the pipe component. Therefore, it is possible to easily fit pipes and the like to the fluid passages.

[0038] In the above-described fuel cell system, a pressure control device that controls a pressure of gas in the manifold may be integrated into the pipe component.

[0039] In the above-described fuel cell system, the pipe component is integrated with the pressure control device. Therefore, it is possible to fit the device to the fuel cell stack extremely easily.

[0040] In the above-described fuel cell system, a flow rate control device that controls a flow rate of a fluid flowing through the manifold may be integrated into the pipe component.

[0041] In the above-described fuel cell system, the pipe component is integrated with a pump. Therefore, it is possible to fit the device to the fuel cell stack extremely easily.

[0042] In the above-described fuel cell system, a pressure sensor that detects a pressure of gas in the manifold may be integrated into the pipe component.

[0043] In the above-described fuel cell system, the pipe component is integrated

with the pressure sensor. Therefore, it is possible to fit the device to the fuel cell stack extremely easily.

[0044] In the above-described fuel cell system, in the pipe component, a contact portion that contacts the one surface of the fuel cell stack may be formed to be a substantially flat surface.

[0045] In the above-described fuel cell system, it is possible to easily make the pipe component closely contact the fuel cell stack.

[0046] In the above-described fuel cell system, the pipe component may includes: a flat plate portion which has a substantially flat plate shape, and is fitted to the one surface of the fuel cell stack, and in which through-holes are formed at positions in a surface that contacts the one surface, the positions corresponding to positions of the manifolds; and a pipe passage portion that includes pipes whose one ends are connected to the respective through-holes so that the pipes and the through holes form the fluid passages. The pipe passage portion may be integrated with the flat plate portion so that the pipe passage portion and the flat plate portion form one component.

[0047] In the above-described fuel cell system, the weight of the pipe component can be reduced.

[0048] In the above-described fuel cell system, the pipe component may be formed of a resin material that has reduced hydrogen permeability. [0049] In the above-described fuel cell system, the hydrogen can be reliably and easily sealed in the fluid passages.

[0050] Another aspect of the invention relates to a pipe component that is one component formed of resin, and that includes a plurality of fluid passages that are connected to respective manifolds provided in a fuel cell stack. [0051] In the above-described pipe component, the plurality of pipes are assembled. Thus, the pipe component is one component formed of a resin material. Therefore, it is possible to reduce the number of components, and to easily handle the pipe component.

[0052] The above-described pipe component may include: a flat plate portion

which has a substantially flat plate shape, and contacts the one surface of the fuel cell stack, and in which through-holes are formed at positions corresponding to positions of the manifolds of the fuel cell stack; and a pipe passage portion that includes pipes whose one ends are connected to the respective through-holes so that the pipes and the through-holes form the fluid passages. The pipe passage portion may be integrated with the flat plate portion so that the pipe passage portion and the flat plate portion form one component.

[0053] With the above-described pipe component, the weight of the pipe component can be reduced. [0054] The above-described pipe component may be formed of a resin material that has reduced hydrogen permeability.

[0055] In the above-described pipe component, the hydrogen can be reliably and easily sealed in the fluid passages.

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The features, advantages, and technical and industrial significance of this invention will be better understood by reading the following detailed description of example embodiments of the invention, when considered in connection with the accompanying drawings, in which: FIG. 1 is a diagram illustrating a configuration according to an embodiment of the invention;

FIG. 2 is a diagram illustrating the configuration according to the embodiment of the invention;

FIG. 3A is a lateral view of a pipe component according to the embodiment, seen from the left side in FIG. 2;

FIG. 3B is a lateral view of the pipe component according to the embodiment, seen from the right side in FIG. 2;

FIG. 3 C is a diagram showing only the pipe component according to the embodiment;

FIG. 4A is a cross sectional view of the pipe component taken along the line X-X in FIG. 2;

FIG. 4B is a cross sectional view of the pipe component taken along the line Y-Y in FIG. 2; FIG. 4C is a cross sectional view of the pipe component taken along the line Z-Z in

FIG. 2;

FIG. 5 is a diagram illustrating the configuration according to the embodiment of the invention;

FIG. 6 is a diagram illustrating the configuration according to the embodiment of the invention;

FIG. 7A is a cross sectional view of the pipe component taken along the chain line A-A in FIG. 6;

FIG. 7B is a cross sectional view of the pipe component taken along the chain line B-B in FIG. 6; FIG. 7C is a cross sectional view of the pipe component taken along the chain line

C-C in FIG. 6;

FIG. 7D is a cross sectional view of the pipe component taken along the chain line D-D in FIG. 6;

FIG. 7E is a cross sectional view of the pipe component taken along the chain line E-E in FIG. 6;

FIGS. 8 A and 8B are perspective views illustrating the configuration of a stack case according to the embodiment of the invention;

FIGS. 9A, 9B, 9C, and 9D are diagrams illustrating an example of a manufacturing method according to the embodiment of the invention; FIGS. 1OA, 1OB, and 1OC are diagrams illustrating an example of a method of manufacturing a portion where hollow structures are adjacent to each other, in an example of the manufacturing method according to the embodiment of the inveniton;

FIG. 11 is a diagram illustrating a first modified example of the invention;

FIG. 12 is a diagram showing an air pressure adjusting valve according to the first

modified example of the invention;

FIG. 13 is a cross sectional view taken along the line A-A in FIG. 11;

FIG. 14 is a diagram showing a pipe component according to the first modified example, into which pressure sensors and a hydrogen circulation pump are integrated; FIG. 15 is a diagram illustrating a second modified example of the embodiment of the invention;

FIG. 16 is a diagram illustrating a third modified example of the embodiment of the invention; and

FIG. 17 is a diagram illustrating an eighth modified example of the embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0057] In the following description and the accompanying drawings, the invention will be described in more detail with reference to example embodiments. [0058] First, a configuration according to an embodiment of the invention will be described. FIG. 1 is a diagram illustrating a fuel cell system according to the embodiment of the invention. The fuel cell system according to the embodiment includes a fuel cell stack 10. FIG. 1 shows an enlarged area that includes the fuel cell stack 10. In the fuel cell stack 10, a plurality of fuel cells are provided. [0059] Gas flow holes are provided in each fuel cell to extend through the fuel cell in the thickness direction of the fuel cell. The gas flow holes are connected to an anode and a cathode. Similarly, coolant flow holes are provided in each fuel cell to extend through the fuel cell in the thickness direction of the fuel cell. The coolant flow holes are connected to a coolant passage formed to extend in the surface of the fuel cell. When a plurality of fuel cells are stacked to form the fuel cell stack 10, the flow holes of the fuel cells are connected to each other in a direction in which the fuel cells are stacked (hereinafter, referred to as "fuel cell stacking direction"). Thus, various manifolds (an anode gas supply manifold, an anode gas discharge manifold, a cathode gas supply manifold, a cathode gas discharge manifold, and a coolant flow manifold) are formed to

extend in the fuel cell stacking direction.

[0060] A stack end plate 12 is fitted to the end surface of the fuel cell stack 10.

Through-holes are formed in the stack end plate 12 at positions corresponding to the positions of the plurality of manifolds in the end surface of the fuel cell stack 10. With the configuration, the end portions of the manifolds are exposed in the end surface of the fuel cell stack 10 (i.e., the surface facing obliquely downward in FIG. 1).

[0061] A fuel cell stack that includes various manifolds extending in the fuel cell stacking direction, such as the fuel cell stack 10, is available as described in, for example,

Japanese Patent Application Publication No. 2005-116226 (JP-A-2005- 116226). Therefore, the detailed description of the structure thereof is omitted. Also, the illustration of the manifolds is omitted in the drawings.

[0062] A pipe component 20 is fitted to the stack end plate 12. The pipe component 20 is one component that is integrally formed of a resin material. As described below, the pipe component 20 includes a plurality of pipe passage portions. The pipe passage portions are hollow pipes or pipes in which grooves are formed. The spaces inside the pipe passage portions function as fluid passages through which gases and a coolant flow.

[0063] In the fuel cell system according to the embodiment, an anode gas supply system (not shown) is provided to supply hydrogen to the fuel cell stack 10. That anode gas supply system includes a hydrogen tank and a hydrogen pressure adjusting valve.

Also, a cathode gas supply system (not shown) is provided to supply air to the fuel cell stack 10. The cathode gas supply system includes an air compressor and an air pressure adjusting valve. Also, an anode gas discharge system and a cathode gas discharge system are provided to discharge gases (anode off-gas, and cathode off-gas, respectively) that are discharged from the fuel cell stack 10 due to electric power generation.

[0064] Also, in the fuel cell system according to the embodiment, a cooling system that includes a pump for supplying the coolant is provided. The devices constituting the fuel cell system (for example, the above-described hydrogen tank and an air compressor) are the same as those used in the conventional fuel cell system as

constituent components. Thus, such devices are not novel, and do not constitute the main portion of the invention. Therefore, the description thereof is omitted.

[0065] As shown in FIG. 1, the pipe component 20 includes a hydrogen inlet pipe passage portion 22. A hydrogen inlet passage 24 is formed inside the hydrogen inlet pipe passage portion 22 to extend through the hydrogen inlet pipe passage portion 22. The hydrogen inlet passage 24 is connected to the anode gas supply manifold in the fuel cell stack 10 via the through-hole in the stack end plate 12. Also, the opposite end portion of the hydrogen inlet passage 24 (i.e., the end portion that does not contact the stack end plate 12) is connected to the above-described anode gas supply system (not shown).

[0066] The pipe component 20 includes a hydrogen outlet pipe passage portion 26. A hydrogen outlet passage 28 is formed inside the hydrogen outlet pipe passage portion 26 to extend through the hydrogen outlet pipe passage portion 26, in the same manner as the manner in which the hydrogen inlet passage 24 is formed inside the hydrogen inlet pipe passage portion 22. The hydrogen outlet passage 28 is connected to the anode gas discharge manifold in the fuel cell stack 10 in the same manner as the manner in which the hydrogen inlet passage 24 is connected to the anode gas supply manifold. The opposite end portion of the hydrogen outlet passage 28 (i.e., the end portion that does not contact the stack end plate 12) is connected to the above-described anode gas discharge system (not shown).

[0067] The pipe component 20 includes an air inlet pipe passage portion 30 inside which an air inlet passage 32 is formed; and an air outlet pipe passage portion 34 inside which an air outlet passage 36 is formed. The air inlet passage 32 and the air outlet passage 36 are connected to the cathode gas supply manifold and the cathode gas discharge manifold in the fuel cell stack 10, respectively, via the through-holes of the stack end plate 12. The opposite end portions of the air inlet passage 32 and the air outlet passage 36, which do not contact the stack end plate 12, are connected to the cathode gas supply system (not shown) and the cathode gas discharge system (not shown), respectively.

[0068] As shown in FIG. 1, the diameter of each of the air inlet pipe passage portion 30 and the air outlet pipe passage portion 34 is gradually changed. Accordingly, the cross section of each of the air inlet passage 32 inside the air inlet pipe passage portion 30 and the air outlet passage 36 inside the air outlet pipe passage portion 34, in a direction perpendicular to the direction in which air flows, is gradually decreased from a position close to the manifold.

[0069] The pipe component 20 includes a coolant outlet pipe passage portion 40 inside which a coolant outlet passage 42 is formed; and a coolant inlet pipe passage portion 44 inside which a coolant inlet passage 46 is formed. Theses passages are connected to the coolant flow manifold in the fuel cell stack 10. The opposite end portions of these passages, which do not contact the stack end plate 12, are connected to the above-described cooling system (not shown).

[0070] When electric power is generated in the fuel cell system according to the embodiment, hydrogen is supplied from the anode gas supply system to the anodes of the fuel cell stack 10 through the hydrogen inlet passage 24, and the anode gas supply manifold in the stated order. The air is supplied to the cathodes of the fuel cell stack 10 from the cathode gas supply system through the air inlet passage 32 and the cathode gas supply manifold. The hydrogen and air are supplied to the fuel cell stack 10, and electrochemical reaction is caused, and thus electric power is generated. [0071] When the electric power is generated, the anode off-gas and the cathode off-gas are discharged from the anode and cathode of each fuel cell, respectively. The anode off-gas is discharged to the anode gas discharge system through the anode gas discharge manifold and the hydrogen outlet passage 28 in the stated order. The cathode off-gas is discharged to the cathode gas discharge system through the cathode gas discharge manifold and the air outlet passage 36 in the stated order.

[0072] When the electric power is generated, the coolant is supplied to the fuel cell stack 10 via the coolant inlet passage 46. The coolant flows through the coolant passage formed in each fuel cell in the fuel cell stack 10 to cool each fuel cell. After the coolant cools each fuel cell, the temperature of the coolant increases. Then, the coolant

flows out from the fuel cell stack 10 through the coolant outlet passage 42.

[0073] (Configuration of the pipe component 20) Hereinafter, the specific configuration of the pipe component 20 will be described in detail. FIG. 2 is a front view showing the pipe component 20 in the fuel cell system according to the embodiment. In FIG. 2, the dashed lines indicate the fluid passages inside the pipe passage portions. The fluid passages are formed to be independent of each other. In reality, the plurality of fluid passages are three-dimensionally disposed at positions at which the plurality of fluid passages cross or overlap each other in FIG. 2. However, in FIG. 2, the fluid passages are shown on one plane for the sake of convenience. [0074] As described above, the pipe component 20 is one component that is integrally formed of the resin material. More specifically, the pipe component 20 includes a flat plate portion 21, and the plurality of pipe passage portions formed integrally with the flat plate portion 21. The flat plate portion 21 has a flat plate shape, and contacts the stack end plate 12 when the pipe component 20 is fitted to the stack end plate 12. The flat plate portion 21 has the substantially same size and the substantially same outer shape as those of the stack end plate 12.

[0075] As shown in FIG. 2, in the pipe component 20, the pipe passage portions are adjacent to each other, and the pipe passage portions extend near the flat plate portion 21 in a manner such that the pipe passage portions three-dimensionally cross or overlap each other. More specifically, the hydrogen inlet pipe passage portion 22 extends downward from an upper left position on the flat plate portion 21 in FIG. 2. The hydrogen inlet pipe passage portion 22 contacts the coolant outlet pipe passage portion 40 at a certain position. The hydrogen inlet pipe passage portion 22 extends further downward, and then bends in an L-shape, and then extends toward the left side in FIG. 2. [0076] The hydrogen outlet pipe passage portion 26 extends toward the left side from a lower right position on the flat plate portion 21 in FIG. 2. The hydrogen outlet pipe passage portion 26 contacts the air inlet pipe passage portion 30 at a certain position in a manner such that the hydrogen outlet pipe passage portion 26 is positioned closer to the rear surface of paper of FIG. 2 than the air inlet pipe passage portion 30 is, and the

hydrogen outlet pipe passage portion 26 crosses the air inlet pipe passage portion 30 at the certain position. Then, the hydrogen outlet pipe passage portion 26 also contacts the air outlet pipe passage portion 34 at a certain position. The air outlet pipe passage portion 34 extends downward from an upper position in FIG. 2. The air outlet pipe passage portion 34 is positioned closer to the surface of paper of FIG. 2 than the coolant outlet pipe passage portion 40 and the air inlet pipe passage portion 30 are, and the air outlet pipe passage portion 34 three-dimensionally cross the coolant outlet pipe passage portion 40 and the air inlet pipe passage portion 30 at certain positions in the stated order. The coolant inlet pipe passage portion 44 and the coolant outlet pipe passage portion 40 overlap each other at a right position in FIG. 2 on the flat plate portion 21.

[0077] Also, in the pipe component 20 according to the embodiment, the hydrogen inlet pipe passage portion 22 contacts the air outlet pipe passage portion 34 at a certain position, and the air outlet pipe passage portion 34 contacts the hydrogen outlet pipe passage portion 26 at a certain position. The hydrogen inlet pipe passage portion 22, the air outlet pipe passage portion 34, and the hydrogen outlet pipe passage portion 26 extend in the substantially same direction toward the left side in FIG. 2. The air inlet pipe passage portion 30, the coolant outlet pipe passage portion 40, and the coolant inlet pipe passage portion 44 extend in the substantially same direction toward the opposite side, that is, the right side in FIG. 2. These pipe passage portions extend in substantially parallel with the planar direction of the flat plate portion 21 (that is, the planar direction of the fuel cell stack 10 in the embodiment).

[0078] FIGS. 3 A and 3B are lateral views showing the pipe component 20. FIG. 3A is a lateral view seen from the left side in FIG. 2. FIG. 3B is a lateral view seen from the right side in FIG. 2. FIG. 3C shows only the pipe component 20. Thus, the pipe component 20 is one component that can be fitted to the fuel cell stack 10, or removed from the fuel cell stack 10 according to need. Accordingly, it is extremely easy to handle the pipe component 20, and to fit the pipe component 20 to the fuel cell stack 10.

[0079] FIGS. 4 A, 4B ₅ and 4C are cross sectional views of the pipe component 20 taken along the line X-X, the line Y-Y, and the line Z-Z, respectively. Although the flat

plate portion 21 and the plurality of pipe passage portions of the pipe component 20 have been described separately, the pipe component 20 is one integrally-formed component that cannot be divided, as shown in FIGS. 4A to 4C. In the cross sectional view in each of FIGS. 4A to 4C, the hydrogen outlet passage 28, the air inlet passage 30, the air outlet passage 36, and the coolant outlet passage 42 are shown. As shown in FIGS. 4A to 4C, the passages constitute flow passages that are independent of each other. The gas or the coolant flows in each passage.

[0080] FIG. 5 is a rear view showing the pipe component 20. FIG. 5 shows the surface of the pipe component 20, which is regarded as the surface that contacts the stack end plate 12 in FIG. 1. Portions of the fluid passages are exposed in the surface of the flat plate portion 21 as opening portions. Before the pipe component 20 is fitted to the stack end plate 12, beads are burned onto areas around the opening portions. Then, the pipe component 20 is fitted to the stack end plate 12 while sealing is provided. As shown in FIGS. 4 A to 4C ₅ the surface of the flat plate portion 21, which contacts the stack end plate 12, is a flat surface. Accordingly, sealing is easily and reliably provided between the flat plate portion 21 and the stack end plate 12 (i.e., the flat plate portion 21 closely contacts the stack end plate 12).

[0081] Also, the cross sectional shapes of the manifolds (not shown) in the fuel cell stack 10 according to the embodiment are the same as the cross sectional shapes of the fluid passages in FIG. 5. That is, when the flat plate portion 21 is fitted to the stack end plate 12, the manifolds, whose cross sectional shapes are the same as the shapes of the through-holes of the flat plate portion 21, extend in the fuel cell stack 10 from the through-holes. For example, the anode gas supply manifold is connected to the hydrogen inlet passage 24, and the circular cross section of the anode gas supply manifold has the same shape and size as those of the cross section of the hydrogen inlet passage 24. The cathode gas supply manifold and the cathode gas discharge manifold are connected to the air inlet passage 32 and the air outlet passage 36, respectively, and each of the cathode gas supply manifold and the cathode gas discharge manifold has an elongated slit-shape cross section, like the slit-shape holes shown in FIG. 5. The width

of the slit shape may vary in the longitudinal direction of the slit shape, to uniformly distribute the air.

[0082] FIG. 6 is a diagram illustrating the pipe component 20 in more detail.

FIG. 6 shows the pipe component 20 that is connected to other pipes. In FIG. 6, the end portions of the pipe passage portions, which do not contact the stack end plate 12 (that is, the end portions that are not directly connected to the manifolds), are connected to the pipes 60, 62, 64, 66, and 68. In the pipe component 20 according to the embodiment, the end portions of the plurality of fluid passages are disposed close to each other at certain positions (i.e., a lower left position and a lower right position in FIG. 6). The end portions of the fluid passages extend in the same direction (i.e., toward the left side or the right side in FIG. 6). Accordingly, the pipes 60 to 68 are disposed close to each other at the certain positions, and extend in the same directions.

[0083] FIGS. 7 A to 7E show cross sections of the pipe component 20 taken along the chain lines in FIG. 6. FIG. 7 A shows the cross section of the pipe component 20 taken along the line A-A, that is, taken at the position at which the hydrogen inlet pipe passage portion 22 crosses the coolant outlet pipe passage portion 40. As shown in FIG.

7A, the hydrogen inlet passage 24 is adjacent to the coolant outlet passage 42 at this position.

[0084] Similarly, in each of the cross sections taken along the lines B-B to E-E, the fluid passages are adjacent to each other at the position at which the plurality of pipe passage portions contact each other, or three-dimensionally cross or overlap each other.

As evident from the comparison between FIG. 7A and FIG. 7B, a main portion of the air outlet passage 36 is farther from the flat plate portion 21 than a main portion of the hydrogen inlet passage 24 is. [0085] As described above, the pipe component 20 according to the embodiment is formed using the resin material as one component. In the embodiment, as the resin material used to form the pipe component 20, polypropylene resin is used because polypropylene has reduced gas permeability, especially low hydrogen permeability.

[0086] FIGS. 8 A and 8B are perspective views showing an example of a stack

case in the fuel cell system according to the embodiment. In a stack case 90, the above-described fuel cell stack 10 and the pipe component 20 (the fuel cell stack 10 and the pipe component 20 are shown by the dashed line) are provided. As shown in FIGS. 8A and 8B, pipes 92, 94, and 98 are disposed close to each other on the side of one surface of the stack case 90. Pipes 96, 100, and 102 are disposed close to each other on the side of the other surface of the stack case 90. As described above, the end portions of the pipe passage portions of the pipe component 20, which do not contact the stack end plate 12, extend in parallel with the end surface of the fuel cell stack 10. As a result, the pipes disposed outside the stack case 90 also extend in parallel with the end surface of the fuel cell stack 10.

[0087] Next, advantageous effects obtained in the embodiment will be described. Various fluids, such as the hydrogen, air, and coolant, need to be supplied to the fuel cell stack 10 to generate electric power. Accordingly, the pipes used for supplying the fluids are fitted to the fuel cell stack so that the gases and the like are supplied to the manifolds in the fuel cell stack through the pipes.

[0088] It is preferable that the pipes should be simple to make it easy to fit the pipes to the fuel cell stack. In order to make it more easy to fit the pipes to the fuel cell stack, and to reduce the number of components, further improvement is required. Accordingly, in the embodiment, the fuel cell system is configured using the pipe component 20 which is one component integrally formed of the resin material, and in which the plurality of fluid passages are formed.

[0089] When the number of components is large as in the conventional fuel cell system, the number of man-hours required for fitting the components to the fuel cell stack is increased. Also, it tends to be difficult to fit the components to the fuel cell stack due to the manufacturing tolerance and fit tolerance of each component. In this regard, the fuel cell system according to the embodiment has the extremely simple configuration where the pipe component 20, which is one component, is fitted to the fuel cell stack 10. With this extremely simple configuration, it is possible to connect all the manifolds in the fuel cell stack 10 (all of the anode gas supply manifold, the cathode gas supply manifold,

the anode gas discharge manifold, the cathode gas discharge manifold, and the coolant flow manifold) to the fluid passages of the pipe component 20. Accordingly, the number of components is reduced, and the pipe component 20 can be fitted to the fuel cell stack 10 extremely easily. [0090] When the number of pipe components is large, it is necessary to check whether sufficient sealing is provided in each component (i.e., whether each fluid passage is sealed). Naturally, this increases the number of man-hours required to check whether sufficient sealing is provided in each component. The increase in the number of man-hours is undesirable, because manufacturing efficiency is decreased, and maintenance is made difficult. In this regard, according to the embodiment, only the pipe component 20, which is one component, is fitted to fuel cell stack 10. Thus, the configuration according to the embodiment is extremely simple. Therefore, sealing is provided in all the fluid passages at the same time. Thus, the fuel cell system can be configured extremely efficiently. [0091] The pipe component 20 according to the embodiment is formed using the resin material. The pipe component, which is one component including the plurality of fluid passages, needs to be easily manufactured. In addition, the fuel cells need to be insulated from the outside when electric power is generated. Therefore, components around the fuel cell stack need to be insulated. In this regard, in the pipe component 20 according to the embodiment, the resin material has a general advantageous effect of making it possible to easily manufacture the pipe component, and an advantageous effect of making it possible to manufacture the insulated pipe component that is fitted to the fuel cell stack. Thus, the resin material functions as an extremely useful material.

[0092] Further, according to the embodiment, the material of the pipe component 20 is polypropylene resin that is the resin material with reduced hydrogen permeability. Thus, the pipe component 20 can be integrally formed as one component, and the hydrogen inlet passage 24 and the hydrogen outlet passage 28 can be reliably sealed (i.e., leakage of hydrogen can be reliably prevented). According to the method in the embodiment, it is possible to prevent leakage of hydrogen more reliably and more easily,

as compared to other methods, for example, a method in which a coating is provided on the inner surfaces of the fluid passages where hydrogen flows, to reduce hydrogen permeability.

[0093] Also, the fluid passages (the hydrogen inlet passage 24, the hydrogen outlet passage 28, the air inlet passage 32, and the air outlet passage 36) in the pipe component 20 are connected to the anode gas supply manifold, the anode gas discharge manifold, the cathode gas supply manifold, and the cathode gas discharge manifold, respectively. With this configuration, when the pipe component is fitted to the fuel cell stack that includes different types of manifolds, that is, the gas supply manifolds, and the gas discharge manifolds, the number of components can be reduced, and the pipe component can be fitted to the fuel cell stack extremely easily.

[0094] Also, according to the embodiment, as described above, the coolant outlet pipe passage portion 40, in which the coolant flows, contacts the hydrogen outlet pipe passage portion 26, and the air outlet pipe passage portion 34. Thus, as described with reference to the cross sectional view in FIG. 7, the coolant outlet passage 42 is adjacent to the hydrogen outlet passage 28 and the air outlet passage 36 via the resin material. With the configuration, the coolant in the cooling system flows adjacent to the off-gases in the gas discharge manifolds via the resin material. As a result, heat is exchanged between the gases and the cooling liquid. For example, it is possible to obtain the advantageous effect of preventing freezing of the gas discharge system in the fuel cell system.

[0095] Also, according to the embodiment, as described above, the coolant outlet pipe passage portion 40, in which the coolant flows, contacts the hydrogen inlet pipe passage portion 24. Thus, as shown also in FIG. 7, the hydrogen inlet passage 24 is adjacent to the coolant outlet passage 42. When the high-pressure hydrogen stored in the hydrogen tank is discharged to a low-pressure side, the temperature of the hydrogen is further decreased in the situation where the temperature of the atmosphere is low. If the low-temperature hydrogen directly flows into the fuel cell stack, the sealing function may be damaged due to the temperature difference. In this regard, according to the embodiment, the above-described low-temperature hydrogen supplied to the fuel cells

can be warmed using the coolant. As a result, the above-described problem is prevented, and the fuel cells generate electric power in a good temperature condition.

[0096] In addition, according to the embodiment, the pipe component 20 is formed using the resin material. Therefore, it is possible to obtain the synergistic advantageous effect of effectively exchanging heat among the various fluids, effectively preventing the freezing of the gas discharge system, and effectively heating the hydrogen supplied to the fuel cells.

[0097] Also, according to the embodiment, the end portions of the fluid passages extend in substantially parallel with the end surface of the fuel cell stack 10 (the surface of the stack end plate 12). The manifolds in the fuel cell stack 10 extend through the plurality of stacked fuel cells, and therefore, the manifolds extend in the direction perpendicular to the end surface of the fuel cell stack 10. If the pipes also extend in the direction perpendicular to the end surface of the fuel cell stack 10, which is the same direction as the direction in which the manifolds extend, the size of the structure around the fuel cell stack is increased in only one direction.

[0098] When the fuel cell system needs to output a certain amount of electric power, for example, when the fuel cell system is installed in a vehicle, several hundred fuel cells are stacked in most cases. Therefore, the shape of the fuel cell stack tends to be increased in the fuel cell stacking direction. However, when the fuel cell system is installed in a limited space, the size of the structure around the fuel cell stack needs to be minimized.

[0099] Particularly when the fuel cell system is installed in the vehicle, it is necessary to install a large amount of components in an extremely limited space. In this case, if the size of the structure around the fuel cell stack is increased in only the fuel cell stacking direction, the flexibility in selecting the space where the fuel cell system is installed, and the flexibility in designing a layout are reduced. In this regard, according to the embodiment, it is possible to prevent the size of the pipe component from being excessively increased in the fuel cell stacking direction. Thus, it is possible to obtain the advantageous effect of reducing the space required for installing the fuel cell system,

in addition to the advantageous effects obtained by configuring the pipe component 20 as one component, in a synergistic manner.

[0100] Further, according to the embodiment, as shown in FIG. 3A, the end portions of the hydrogen inlet passage 24, the hydrogen outlet passage 28, and the air outlet passage 36 extend in substantially parallel with the end surface of the fuel cell stack 10, and the substantially same direction (i.e., toward the left side in FIG. 2). Also, as shown in FIG. 3B, the end portions of the air inlet passage 32, the coolant outlet passage 42, and the coolant inlet passage 46 extend in substantially parallel with the end surface of the fuel cell stack 10, and the substantially same direction (i.e., toward the right side in FIG. 2). If the end portions of the fluid passages extend in various directions, the other pipe components connected to the fluid passages also extend in various directions. As a result, space use efficiency is deteriorated, and the size of the structure around the fuel cell stack 10 is excessively increased. In this regard, according to the embodiment, it is possible to avoid the situation where the end portions of the fluid passages extend in various directions, and therefore, the space required for installing the fuel cell system is increased.

[0101] Also, according to the embodiment, the fluid passages extend in substantially parallel with the end surface of the fuel cell stack 10. With the configuration, it is possible to prevent the size of the pipe component from being excessively increased in the fuel cell stacking direction. Thus, it is possible to effectively avoid the above-described problems.

[0102] Also, according to the embodiment, the fluid passages extend in substantially parallel with the end surface of the fuel cell stack 10, and the end portions of the fluid passages extend in substantially parallel with the end surface of the fuel cell stack 10. Accordingly, it is possible to obtain the above-described advantageous effects in a synergistic manner. Thus, it is possible to further effectively prevent the size of the structure around the fuel cell stack from being excessively increased in the fuel cell stacking direction.

[0103] Also, according to the embodiment, in the pipe component 20 _. that is one

component, the plurality of fluid passages are three-dimensionally formed (i.e., the plurality of fluid passages three-dimensionally cross or overlap each other near the flat plate portion 21). When the fuel cells generate electric power, the plurality types of different fluids, such as the reactant gas (anode gas), the air (cathode gas), and the coolant, need to be supplied to the fuel cells. Accordingly, gas supply holes, through which the fluids are supplied to each fuel cell, may be disposed at positions apart from each other in the surface of each fuel cell (for example, refer to Japanese Patent Application Publication No. 2005-116226 (JP-A-2005-116226)). In this case, the manifolds formed by stacking the fuel cells are disposed at positions apart from each other in the end surface of the fuel cell stack.

[0104] If a plurality of pipes are appropriately fitted to the fuel cell stack with the above-described configuration, and the pipes are three-dimensionally disposed, the operation of fitting the pipes to the fuel cell stack is complicated. Also, the positions at which the pipes are fitted may deviate, or interfere with each other due to the synergistic influence of the manufacturing tolerance and the fit tolerance of each component. Thus, it tends to be difficult to fit the pipes to the fuel cell stack. In this regard, according to the embodiment, the plurality of fluid passages are formed in one component, and only the one component is fitted to the fuel cell stack. Therefore, it is not necessary to fit the plurality of pipes in a complicated layout, and the configuration of the pipe component is extremely simple.

[0105] More specifically, for example, in the pipe component 20 according to the embodiment, the coolant outlet passage 42 and the coolant inlet passage 46 overlap each other in the direction perpendicular to the end surface of the fuel cell stack 10. Thus, it is possible to form the plurality of fluid passages in one component while reliably preventing the fluid' passages from interfering with each other. Accordingly, it is possible to obtain the pipe component 20 that is one component including the plurality of fluid passages, regardless of the positional relation among the manifolds.

[0106] Also, the manifolds may have various cross sectional shapes to efficiently supply the different types of fluids to the fuel cells. More specifically, in the fuel cell

stack 10 according to the embodiment, the manifolds have various cross sectional shapes as shown in FIG. 5. When the manifolds have various complicated cross sectional shapes, it is difficult to dispose the plurality of fluid passages on one plane in a manner such that the fluid passages do not interfere with each other. In this regard, according to the embodiment, the fluid passages are three-dimensionally disposed. Therefore, it is possible to form, in one component, the fluid passages that can be connected to the manifolds with complicated cross sectional shapes.

[0107] Also, according to the embodiment, the plurality of fluid passages are formed to three-dimensionally cross each other in the pipe component 20 that is one component. With this configuration, as described above, it is possible to form, in one component, the fluid passages that can be connected to the manifolds with complicated cross sectional shapes.

[0108] Also, according to the embodiment, the fluid passage in which the coolant flows three-dimensionally crosses, and is adjacent to the fluid passage in which the anode off-gas or the cathode off-gas flows. Thus, it is possible to obtain the synergistic effect of forming the pipes with the complicated configurations in one component, and exchanging heat between the coolant and the off-gases.

[0109] Also, according to the embodiment, the main portion of the air outlet passage 36 is farther from the flat plate portion 21 than the main portion of the hydrogen inlet passage 24 is. With this configuration, among the plurality of fluid passages, the fluid passage in which the hydrogen flows is disposed inside (i.e., close to the flat plate portion 21), as compared to the other fluid passages. As a result, the hydrogen inlet passage 24 is protected by the other fluid passages (pipe passage portions). Thus, it is possible to protect the fluid passage in which the hydrogen flows from, for example, an impact applied from the outside.

[0110] Also, according to the embodiment, each of the air inlet passage 32 and the air outlet passage 36 has the substantially rectangular cross section in the direction perpendicular to the direction in which the air flows. Also, each of the coolant outlet passage 42 and the coolant inlet passage 46 has the substantially rectangular cross section

in the direction perpendicular to the direction in which the coolant flows. With this configuration, the two passages are made closer to each other, and the size of the pipe component is reduced.

[0111] Also, according to the embodiment, the cross sectional shapes of the air inlet passage 32 and the air outlet passage 36 in the direction perpendicular to the direction in which the air flows are gradually changed from positions close to the manifolds. If the cross sectional shapes in the direction perpendicular to the direction in which the fluids flow are sharply changed, for example, the loss of pressure may be increased, and accordingly, the fluids may not flow smoothly, which is undesirable. In this regard, according to the embodiment, the gases and the coolant are kept flowing smoothly.

[0112] Also, according to the embodiment, the end portions of the hydrogen inlet passage 24, the hydrogen outlet passage 28, and the air outlet passage 36 are disposed close to each other at the certain position in one side of the pipe component 20. Also, the end portions of the air inlet passage 32, the coolant outlet passage 42, and the coolant inlet passage 46 are disposed close to each other at the certain position in the other side of the pipe component 20. Thus, the end portions of the fluid passages are disposed close to each other at the certain positions, instead of disposing the end portions apart from each other. This makes it easier to fit the other components, such as the pipes, to the pipe component 20.

[0113] Also, according to the embodiment, the pipe component 20 is configured by forming the plurality of pipe passage portions integrally with the flat plate portion 21. With this configuration, it is easy to ensure sufficient sealing performance between the flat plate portion 21 and the stack end plate 12. Also, according to the embodiment, the pipe component 20 is configured by forming the pipe passage portions having pipe shapes, inside which the through-passages are formed (for example, the hydrogen inlet pipe passage portion 22 inside which the hydrogen inlet passage 24 is formed), integrally with the flat plate portion 21. With this configuration, no excess material is used, and the weight and size of the pipe component 20 can be reduced.

[0114] The rear surface of the pipe component 20 (refer to FIG. 5) may be regarded as "a contact portion that contacts the one surface of the fuel cell stack". For example, the hydrogen inlet passage 22 provided in the pipe component 20 may be regarded as one of "a plurality of fluid passages". [0115] In the above-described embodiment, the coolant output passage 42 and the coolant inlet passage 46 may be regarded as "a fluid passage connected to the coolant flow manifold". The hydrogen outlet passage 28 and the air outlet passage 36 may be regarded as "a fluid passage connected to the gas discharge manifold".

[0116] In the above-described embodiment, the hydrogen inlet passage 24 may be regarded as "a fluid passage connected to the hydrogen supply manifold". All the fluid passages provide in the pipe component 20 may be regarded as "a fluid passage in which an end portion that is not connected to the manifold extends in substantially parallel with the one surface of the fuel cell stack".

[0117] In the above-described embodiment, all the fluid passages provided in the pipe component 20 may be regarded as "a fluid passage that includes a portion that extends in substantially parallel with the one surface of the fuel cell stack". Also, in the above-described embodiment, for example, the coolant outlet passage 42 may be regarded as "a first fluid passage" that extends in substantially parallel with the one surface of the fuel cell stack. The coolant inlet passage 46 may be regarded as "a second fluid passage" that extends to overlap "the first fluid passage" at a position at which the second fluid passage is farther from the one surface than "the first fluid passage" is.

[0118] In the above-described embodiment, the coolant outlet passage 42 may be regarded as "the first fluid passage", and the air outlet passage 36 may be regarded as "a third fluid passage" that three-dimensionally crosses "the first fluid passage".

[0119] In the above-described embodiment, the hydrogen inlet passage 24 may be regarded as "a fluid passage connected to the hydrogen supply manifold". The air outlet passage 36 may be regarded as "a fluid passage that includes a portion that is farther from the one surface of the fuel cell stack than a portion of the hydrogen inlet passage is".

[0120] In the above-described embodiment, the hydrogen inlet passage 24, the hydrogen outlet passage 28, and the air outlet passage 36 may be regarded as "at least two fluid passages in which end portions that are not connected to the manifolds are disposed at the substantially same position in the pipe component". The end portions of the air inlet passage 32, the coolant outlet passage 42, and the coolant inlet passage 46 are disposed close to each other at the position different from the position where the end portions of the hydrogen inlet passage 24, the hydrogen outlet passage 28, and the air outlet passage 36 are disposed close to each other. Thus, the air inlet passage 32, the coolant outlet passage 42, and the coolant inlet passage 46 may be also regarded as "at least two fluid passages in which end portions that are not connected to the manifolds are disposed at the substantially same position in the pipe component".

[0121] In the above-described embodiment, the plurality of pipe passage portions (for example, the hydrogen inlet pipe passage portion 22) provided in the pipe component 20 may be regarded as "a pipe passage portion". [0122] The pipe component 20 according to the embodiment has the feature that

"among the fluid passages in which the end portions that are not connected to the manifolds extend in substantially parallel with the one surface of the fuel cell stack 10, end portions of at least two fluid passages extend in the substantially same direction". As a result, it is possible to avoid the situation where the end portions of the fluid passages extend in various directions, and therefore, the space required for installing the fuel cell system is increased.

[0123] In the above-described embodiment, the hydrogen inlet passage 24, the hydrogen outlet passage 28, and the air outlet passage 36 may be regarded as "at least two fluid passages in which end portions extend in the substantially same direction" in the above-described feature. The end portions of the air inlet passage 32, the coolant outlet passage 42, and the coolant inlet passage 46 extend in the substantially same direction that is different from the direction in which the end portions of the hydrogen inlet passage 24, the hydrogen outlet passage 28, and the air outlet passage 36 extend. Thus, the air inlet passage 32, the coolant outlet passage 42, and the coolant inlet passage

46 may also be regarded as "at least two fluid passages in which end portions extend in the substantially same direction" in the above-described feature.

[0124] The pipe component 20 according to the embodiment also has the feature "in the fluid passage that has the portion that extends in substantially parallel with the one surface of the fuel cell stack 10, an end portion that is not connected to the manifold extends in substantially parallel with the one surface of the fuel cell stack 10". With this configuration, it is possible to effectively prevent the size of the pipe component from being excessively increased in the fuel cell stacking direction.

[0125] A method of manufacturing the pipe component according to the embodiment will be described. FIGS. 9 A to 9D and FIGS. 1OA to 1OC illustrate an example of a method of manufacturing the pipe component 20 according to the embodiment. As described above, the pipe component 20 is one resin component in which the plurality of fluid passages are provided. Thus, the plurality of fluid passages (that is, grooves, through-holes, and hollow portions) can be formed in one resin component using a conventional known manufacturing technology, or using a plurality of conventional known manufacturing technologies in combination. Hereinafter, a part of a process of manufacturing a hollow resin molded component will be described as an example of a method appropriate for forming the pipe component according to the embodiment. [0126] FIGS. 9 A to 9D illustrate the process of manufacturing the hollow resin molded component, which is applied to the manufacturing of the pipe component 20 according to the embodiment. FIG. 9A shows a process of injecting resin, in the process of manufacturing the hollow resin molded component. As shown in FIG. 9A, in this process, a mold 152 and a mold 154 are used. The mold 154 is connected to a hydraulic pressure cylinder 150 for slide movement. In the process of injecting resin, the resin material is supplied into the mold 152 and the mold 154 that contact each other in the manner shown in FIG. 9A. Thus, a resin molded component 160 is formed.

[0127] Then, as shown in FIG. 9B, the mold 152 and the mold 154 are separated from each other, a runner is taken out, and the mold 154 is slid. More specifically, in

this process, first, the mold 152 and the mold 154 are separated from each other, and the runner is taken out. Thus, the resin molded component 160 is divided into resin molded components 162 and 166. Then, the mold ^' 154 is pulled by the hydraulic cylinder 150 for slide movement. Thus, the mold 154 is slid. Next, as shown in FIG. 9C, the mold 152 and the mold 154 are fitted to each other, and the resin molded components 162 and 166 are joined to each other by injection molding while the resin molded components 162 and 166 contact each other. As a result, a resin molded component 170 shown in FIG. 9C is formed. Then, the mold 152 and the mold 154 are separated from each other again, and the hollow resin molded component 170 is taken out, as shown in FIG. 9D. In the process that has been described, the hollow resin molded component is manufactured. By applying this method, the pipe component 20 according to the embodiment can be formed.

[0128] Also, FIGS. 1OA to 1OC illustrate an example of a method of manufacturing a portion of the pipe component 20, where hollow structures are adjacent to each other, in an example of the process of manufacturing the pipe component 20. More specifically, FIGS. 1OA to 1OC illustrate an example of the method of manufacturing, for example, the portion where the air outlet passage 36 and the coolant outlet passage 42 are adjacent to each other, as shown in FIG. 7B. In the method illustrated in FIGS. 1OA to 1OC, first, resin molded components 180 and 182 are joined to each other to form one component in which a hollow portion 184 is provided, using the above-described method shown in FIGS. 9 A to 9D (FIGS. 1OA and 10B). Then, as shown in FIG. 1OC, a resin material 190 is added at a position to form a hollow portion 192. By using this method, it is possible to form the portion where the hollow structures are adjacent to each other. [0129] The method of manufacturing the pipe component 20 is not limited to the above-described method. The pipe component 20 may be manufactured by various manufacturing methods. For example, two or more components are formed using different molds for resin molding, and then, the two or more components are integrated with each other.

[0130] Modified examples of the above-described embodiment will be described. First, a first modified example will be described. The first modified example relates to "the integration of various devices into the pipe component". In the above-described embodiment, the fuel cell system is configured using the pipe component 20 that includes the plurality of pipe passage portions. In contrast, in the first modified example, the fuel cell system is configured using the pipe component 20 into which devices that adjust the flow rates of the gases and the coolant supplied to the fuel cell stack, and pressure sensors that detect the pressures of the gases in the fuel cell stack 10 are further integrated.

[0131] FIG. 11 illustrates a pipe component 220 according to the first modified example of the embodiment. FIG. 11 is a front view showing the pipe component 220. FIG. 11 corresponds to FIG. 2 in the embodiment. As shown in FIG. 11, the pipe component 220 includes a hydrogen inlet pipe passage portion 222, a hydrogen outlet pipe passage portion 226, an air inlet pipe passage portion 230, an air outlet pipe passage portion 234, a coolant inlet pipe passage portion 244, and a coolant outlet pipe passage portion 240. Like the pipe passage portions of the pipe component 20 according to the embodiment, each of the pipe passage portions of the pipe component 220 includes a fluid passage therein, and the pipe passage portions are formed integrally with the flat plate portion 221 to form one component.

[0132] The pipe component 220 according to the first modified example includes a hydrogen pressure adjusting valve 260 at the end portion of the hydrogen inlet pipe passage portion 222, a hydrogen discharge valve 270 at the end of the hydrogen outlet pipe passage portion 226, and an air pressure adjusting valve 250 in the air outlet pipe passage portion 234. FIG. 12 shows a long butterfly valve that is an example of the air pressure adjusting valve 250. FIG. 13 is a cross sectional view taken along the line A-A in FIG. 11.

[0133] In the first modified example, the pipe component 220, into which the various pressure control devices are integrated, is fitted to the fuel cell stack 10, as in the embodiment. Thus, in the first modified example, because the pressure control devices are integrated into the pipe component 220, it is possible to fit these components to the

fuel cell stack extremely easily, and to reduce the number of components. That is, it is possible to make it easier to fit the components to the fuel cell stack.

[0134] In the above-described first modified example, the pressure control devices that control the pressures in the manifolds in the fuel cell stack 10 are integrated into the pipe component 220. However, in addition to the pressure control devices, pumps such as a hydrogen circulation pump, and various valves may be integrated into the pipe component 220 as flow rate control devices that control the flow rates of the fluids flowing through the manifolds, and/or pressure sensors that detect the pressures of the gases in the manifolds may be integrated into the pipe component 220. [0135] FIG. 14 shows an example in which pressure sensors 290 and a hydrogen circulation pump 280 are further integrated into the pipe component 220 in the first modified example in FIG. 11. The pipe component 220 in FIG. 14 includes a hydrogen circulation pipe passage portion 223 that connects the hydrogen inlet pipe passage portion 222 to the hydrogen outlet pipe passage portion 226. By driving the hydrogen circulation pump 280, it is possible to circulate the hydrogen through the fluid passage for circulating the hydrogen, which is formed inside the hydrogen circulation pipe passage portion 223.

[0136] In FIG. 11 in the above-described first modified example, the hydrogen pressure adjusting valve 260, the air pressure adjusting valve 250, and the like may be regarded as "a pressure control device". The hydrogen discharge valve 270 in FIG. 11 and the hydrogen circulation pump 280 in FIG. 14 may be regarded as "a flow rate control device".

[0137] A second modified example of the embodiment will be described. The second modified example relates to "the other configurations of the fluid passages and the pipe passage portions". In the above-described embodiment, as described with reference to FIG. 5, the manifolds in the fuel cell stack 10 have various cross sectional shapes, such as a circular shape, a rectangular shape, and a slit shape. However, the cross sectional shapes and the positions of the manifolds in the fuel cell stack 10 according to the invention are not limited to the shapes and the positions shown in FIG. 5.

The invention may be applied to any configuration, as long as a plurality of manifolds are provided in the fuel cell stack, and the manifolds extend to the end surface of the fuel cell stack in the configuration.

[0138] FIG. 15 illustrates a pipe component 320 according to a second modified example of the embodiment. Each of the dashed lines in FIG. 15 indicates a through-hole formed in a flat plate portion 321. The shapes and sizes of the through-holes correspond to the cross sectional shapes and sizes of the respective manifolds in the fuel cell stack according to the second modified example, which is fitted to the rear surface of the pipe component 320 in FIG. 15. In the second modified example, a hydrogen inlet pipe passage portion 322, a hydrogen outlet pipe passage portion 326, an air inlet pipe passage portion 330, an air outlet pipe passage portion 334, a coolant inlet pipe passage portion 344, and a coolant outlet pipe passage portion 340 are provided at positions corresponding to the positions of the through-holes.

[0139] Thus, the positions and cross sectional shapes of the pipe passage portions are set according to the positions and cross sectional shapes of the respective manifolds in the fuel cell stack. When the pipe component is fitted to the fuel cell stack that includes manifolds with various cross sectional shapes other than the cross sectional shapes shown in FIG. 15, the pipe component may be formed in a manner such that the positions and cross sectional shapes of the fluid passages appropriately correspond to the positions and cross sectional shapes of the manifolds.

[0140] Also, in the above-described embodiment, the coolant outlet passage 42 three-dimensionally crosses, and is adjacent to the hydrogen inlet passage 24, the hydrogen outlet passage 28, and the air outlet passage 36. This promotes the heat exchange. However, as described above, the arrangement of the fluid passages is not limited to the arrangement in the above-described embodiment. The fluid passages may be arranged in various manners. For example, in another modified example, the coolant outlet passage 42 may be formed to extend in substantially parallel with the end surface of the fuel cell stack 10, and the hydrogen inlet passage 24 or the like may be formed to overlap the coolant outlet passage 42 at a position at which the hydrogen inlet passage 24

or the like is apart from the coolant outlet passage 42 in the direction perpendicular to the end surface of the fuel cell stack 10.

[0141] A third modified example of the embodiment will be described. The third modified example relates to "the other configurations of the pipe component". In the above-described embodiment, the pipe component 20 is configured as one component that includes the plurality of fluid passages, by forming the plurality of pipe passage portions integrally with the flat plate portion 21. However, the pipe component provided in the fuel cell system according to the invention is not limited to this pipe component. The pipe component need not necessarily include the flat plate portion 21 and the plurality of pipe passage portions as described in the above embodiment, as long as the pipe component is one resin component that includes the plurality of fluid passages. More specifically, for example, a pipe component 420 shown in FIG. 16 may be employed. The pipe component 420 is a rectangular prism member which is made of resin, and in which fluid passages 422, 424, and 426 are formed. [0142] The pipe component 20 and the pipe component 420 may be regarded as

"one resin pipe component that includes a plurality of fluid passages that are connected to the respective manifolds provided in a fuel cell stack, wherein the pipe component includes a contact portion that contacts one surface of the fuel cell stack, where outlets/inlets of the manifolds are formed; and the fluid passages extend through the pipe component from positions in the contact portion, the positions corresponding to the outlets/inlets of the respective manifolds".

[0143] A fourth modified example of the embodiment will be described. The fourth modified example relates to "materials used to form the pipe component". The resin material used to form the pipe component 20 is not limited to the material described in the embodiment. As described above, it is preferable that the pipe component 20 should be integrally formed of a resin material with reduced hydrogen permeability. Accordingly, when the material used to form the pipe component 20 is selected, an appropriate material may be comprehensively determined and selected, taking into account that the material should be easily shaped when the pipe component 20 is

manufactured, the material should have sufficient insulation properties to form the pipes constituting the fuel cell system, and the material should have reduced hydrogen permeability. For example, in addition to polypropylene resin, nylon resin, polyamide resin, and fluorine resin may be used. [0144] The pipe component according to the invention need not necessarily be integrally formed of a material with reduced hydrogen permeability. Various modifications may be made. For example, a coating may be provided inside the fluid passages in which the hydrogen flows (in the embodiment, the hydrogen inlet passage 24 and the hydrogen outlet passage 28). Alternatively, the hydrogen inlet pipe passage portion 22 and the hydrogen outlet pipe passage portion 26 may be formed of a resin material with reduced hydrogen permeability, or portions of the hydrogen inlet pipe passage portion 22 and the hydrogen outlet pipe passage portion 26 may be formed of a resin material with reduced hydrogen permeability, and then, the hydrogen inlet pipe passage portion 22 and the hydrogen outlet pipe passage portion 26 may be integrated with the other pipe passage portions to form the pipe component 20. As the coating material with low hydrogen permeability, various known materials (various materials with poor hydrogen permeability including resin) may be used.

[0145] At least the above-described various materials are included in "a resin material with reduced hydrogen permeability". [0146] Next, a fifth modified example of the embodiment will be described.

The fifth modified example relates to "a pipe component in which only a portion is integrally formed of resin". The entire pipe component 20 need not necessarily be formed as one component. In the pipe component according to the fifth modified example, at least two pipes, in which fluids different from each other flow, are integrally formed of resin. Examples of the fluids different from each other include the hydrogen to be supplied and the discharged hydrogen, the air to be supplied and the discharged air, and the coolant to be supplied and the discharged coolant. The fluids different from each other may be different types of fluids.

[0147] Next, a sixth modified example of the embodiment will be described.

The sixth modified example relates to "a pipe component formed by integrating a plurality of resin components with each other". In the above-described embodiment, the pipe component is formed by integral molding. However, the pipe component need not necessarily be formed by integral molding. In the sixth modified example, the pipe component is a resin pipe component formed by integrating a plurality of separately formed resin components with each other. That is, the pipe component may be formed by a plurality of components, as long as pipes, in which fluids different from each other flow, are integrated with each other before the pipe component is fitted to the fuel cell stack. In this case as well, the operation of fitting the pipes to the fuel cell stack is greatly simplified, as compared to the conventional technology. The resin components may be integrated with each other by, for example, vibration welding, impulse welding, hot plate welding, noncontact hot plate welding, ultrasonic welding, high frequency welding, and laser welding. In the vibration welding, the resin components are welded to each other by friction heat generated by vibration. In the impulse welding, a linear heater is used. In the hot plate welding, a mold that includes a heat source is used. In the noncontact hot plate welding, a mold is heated at high temperature, and heat radiated from the mold is used. In the ultrasonic welding, friction heat generated by ultrasonic vibration is used, hi the high frequency welding, heat generated by dielectric heating is used. [0148] Next, a seventh modified example of the embodiment will be described.

The seventh modified example relates to "a pipe component connected to pipes formed of metal". When an air compressor is connected to the fuel cell stack through the pipe component integrally formed of resin, pipes that have higher radiation performance than that of the resin pipe component may be provided between the air compressor and the resin pipe component. As the pipes with higher radiation performance than that of the resin pipe component, pipes formed of metal may be used.

[0149] Next, an eighth modified example of the embodiment will be described with reference to FIG. 17. The eighth modified example relates to "connection with an end portion of the pipe component". It is preferable that an end portion 520 of the pipe

component 20 integrally formed of resin, which is connected to a pipe or a hose 550, should have higher stiffness than that of other portions. The pipe or the hose 550 needs to be connected to the pipe component 20 with - strong tightening force to increase air-tightness. If the end portion 520 of the pipe component 20 has high stiffness, the tightening force for connecting the pipe or the hose 550 to the pipe component 20 can be appropriately supported by the resin pipe component 20. In order to increase the stiffness of only the end portion 520 connected to the pipe or hose 550, the thickness of the end portion 520 may be increased, or a core material or a filler that has higher stiffness than that of the resin base material may be provided in the end portion 520. Also, for example, when the hose 550 is connected to the pipe component 20 as shown in FIG. 17, a protrusion portion 525, which outwardly protrudes in a radial direction, may be provided in the end portion 520 of the pipe component 20. In this case, it is possible to prevent the pipe or the hose 550 from being removed from the pipe component 20.

[0150] Further, other modified examples will be described. In the above-described embodiment, the fluid passages are adjacent to each other in the pipe component 20 so that heat is exchanged between the fluids (more specifically, between the coolant and the anode off-gas, and between the coolant and the cathode off-gas). However, this configuration may be made according to need. The fluid passages need not necessarily be disposed adjacent to each other for heat exchange. That is, the fluid passages may be disposed far from each other. Also, in the above-described embodiment, the coolant outlet passage 42 is adjacent to the other fluid passages to promote the heat exchange. However, heat need not necessarily be exchanged between the off-gases and the coolant that flows out from the fuel cell stack. That is, instead of the coolant outlet passage 42, the coolant inlet passage 46 may be adjacent to the other fluid passages so that heat is exchanged between the coolant and the off-gases.

[0151] In the above-described embodiment, in the pipe component 20, the end portions of the fluid passages extend in parallel with the end surface of the fuel cell stack 10. Also, the fluid passages extend in parallel with the end surface of the fuel cell stack 10. However, this configuration may be made according to need. All the fluid

passages need not necessarily have this configuration. For example, the fluid passage(s) may extend in the direction perpendicular to the end surface of the fuel cell stack 10 according to need.

[0152] In the above-described embodiment, in the pipe component 20, the fluid passages are three-dimensionally disposed (in a manner such that the fluid passages three-dimensionally cross or overlap each other). However, this configuration may be made according to need. In the pipe component of the fuel cell system according to the invention, the fluid passages need not necessarily be three-dimensionally disposed. That is, more specifically, the plurality of fluid passages may be two-dimensionally disposed in the same plane on or near the flat plate portion 21.

[0153] In the above-described embodiment, the feature that the main portion of the air outlet passage 36 is farther from the flat plate portion 21 than the main portion of the hydrogen inlet passage 24 is, the feature that the cross sectional shapes of the fluid passages are rectangular, and the feature that the end portions of the fluid passages of the pipe component 20 are disposed close to each other at the certain positions, may be appropriately employed in combination. All the features need not necessarily be employed. In the above-described embodiment, the cross sections of the air inlet passage 32 and the air outlet passage 36 are gradually decreased from the positions close to the manifolds. However, this configuration need not necessarily be made. The cross sectional shapes and sizes of the air inlet passage 32 and the air outlet passage 36 may be changed according to need. Also, the cross sectional shapes of the other fluid passages may be gradually changed according to need.

[0154] In the above-described embodiment, the pipe component 20 is fitted to the fuel cell stack that includes both of the gas supply manifolds and the gas discharge manifolds. However, the invention is not limited to this configuration. For example, the invention may be applied to a fuel cell system of so-called anode dead end type. In this fuel cell system, a reactant gas is supplied to fuel cells, and used to generate electric power, but off-gases are not discharged from the fuel cell system. In this case as well, the pipe component that is one resin component including a plurality of fluid passages is

configured according to the positions and cross sectional shapes of the manifolds that are exposed in the end portion of the fuel cell stack. Then, the fuel cell system is configured using the pipe component.