Separator

An example separator includes: a flat plate-shaped first plate member; a flat plate-shaped second plate member joined with the first plate member; an oxidation gas flow channel wall, which forms a flow channel of oxidation gas; a fuel gas flow channel wall, which forms a flow channel of fuel gas; a cooling medium flow channel wall, which forms a flow channel of a cooling medium; a first through hole, which penetrates the first plate member and the second plate member; a second through hole, which penetrates the first plate member and the second plate member; a first cooling medium passage part; a second cooling medium passage part; one projection, which is formed on at least one of the first cooling medium passage part and the second cooling medium passage part; and another projection, which is formed at a position corresponding to the one projection.

FIELD

The present disclosure relates to a separator wherein a surface on the anode side and a surface on the cathode side are constructed by joining two plate members.

BACKGROUND AND SUMMARY

A fuel battery is provided with a stack composed of laminated unit battery cells, each of which is obtained by sandwiching a membrane electrode assembly (MEA) with a pair of separators. An MEA has, for example, a cathode electrode and an anode electrode on both sides of a solid polymer electrolyte film. A fuel battery is, for example, a solid polymer fuel battery provided with a solid polymer electrolyte film. In a solid polymer fuel battery, fuel gas (e.g., hydrogen) supplied to an anode electrode in each unit battery cell of the stack reacts with oxidation gas (e.g., air) supplied to a cathode electrode, so that electric power and water are generated.

Among components of a solid polymer fuel battery, a separator is constituted of a plate member, which is electrically conductive. A flow channel of fuel gas is formed on one outer surface of the separator. A flow channel of oxidation gas is formed on the other outer surface of the separator. Some separators are obtained by constructing one separator from one plate member, while the others are obtained by constructing one separator from two joined plate members. Regarding a separator obtained by two joined plate members, a flow channel of fuel gas is formed on the outer surface of one plate member, and a flow channel of oxidation gas is formed on the outer surface of the other plate member. A flow channel of a cooling medium is formed on the inner surface which lies on the inner side of the two joined plate members.

One of conventional separators obtained by joining two plate members, for example, a separator, which has a structure that two separator plates obtained by processing conductive carbon sheets by cutting work are joined with each other, is disclosed. The two separator plates are respectively provided with a manifold hole, which functions as an inlet of cooling water, and another manifold hole, which functions as an outlet of cooling water. A flow channel of cooling water is formed on the inner surface of the two separator plates. On at least one of the two separator plates, a groove to be filled with sealant is provided at a position surrounding a manifold hole of each of an inlet and an outlet. As the groove is filled with sealant, leakage of cooling water is prevented.

A stack of a solid polymer fuel battery is constructed by laminating a plurality of unit battery cells. The plurality of unit battery cells are tightened in the lamination direction with a plurality of bolts. A conventional separator is composed of two separator plates obtained by processing conductive carbon sheets by cutting work. A conventional separator thus has high rigidity and therefore is unlikely to be deformed by pressure in the lamination direction. Accordingly, a flow channel of cooling water would not be closed by deformation of the separator plates.

However, in a case where a separator is composed of two thin metal plates, it is impossible to obtain high rigidity like a conventional separator. Possible separators composed of two thin metal plates include, for example, a separator which has a convex/concave shape formed by press work, cutting work or the like. The convex/concave shape forms a flow channel of fuel gas or oxidation gas on the outer surface of a thin metal plate, and forms a flow channel of cooling water on the inner surface of a thin metal plate. A separator having such a structure may possibly be deformed by pressure in the lamination direction when a stack is constructed. As the separator is deformed, the distribution channel of cooling water may possibly be closed.

In consideration of the above-described circumstances, it is an object to provide a separator, which can be constructed with two thin metal films and has a distribution channel of a cooling medium that can be maintained if being subject to pressure in the lamination direction.

According to one aspect of the example embodiment, the separator includes: a flat plate-shaped first plate member; a flat plate-shaped second plate member joined with the first plate member; an oxidation gas flow channel wall, which is provided on a first surface of the first plate member and forms a flow channel of oxidation gas; a fuel gas flow channel wall, which is provided on a second surface of the second plate member and forms a flow channel of fuel gas; a cooling medium flow channel wall, which is provided on at least one of a second surface that is a surface on a side opposite to the first surface of the first plate member and faces the second plate member, and a first surface that is a surface on a side opposite to the second surface of the second plate member and faces the first plate member, corresponds to at least one of the oxidation gas flow channel wall and the fuel gas flow channel wall, and forms a flow channel of a cooling medium; a first through hole, which is formed at a position different from the cooling medium flow channel wall and penetrates the first plate member and the second plate member; a second through hole, which is formed at a position different from the cooling medium flow channel wall and from the first through hole and penetrates the first plate member and the second plate member; a first cooling medium passage part, which is formed by separating a part of the second surface of the first plate member and a part of the first surface of the second plate member from each other and establishes communication between the first through hole and one end of the cooling medium flow channel wall; a second cooling medium passage part, which is formed by separating a part of the second surface of the first plate member and a part of the first surface of the second plate member from each other and establishes communication between the second through hole and the other end of the cooling medium flow channel wall; one projection, which is formed on at least one of the first cooling medium passage part and the second cooling medium passage part, is projected from the second surface of the first plate member toward the first surface of the second plate member, and is separated from the cooling medium flow channel wall; and another projection, which is formed at a position corresponding to the one projection on at least one of the first cooling medium passage part and the second cooling medium passage part, is projected from the first surface of the second plate member to the second surface of the first plate member, is separated from the cooling medium flow channel wall, and comes into contact with the one projection in a state where the first plate member and the second plate member are joined with each other.

According to one aspect of the example embodiment, the separator includes: a flat plate-shaped first plate member, which is made of metal; a flat plate-shaped second plate member, which is made of metal and is joined with the first plate member; an oxidation gas flow channel wall, which is provided on a first surface of the first plate member, is projected from the first surface, and forms a flow channel of oxidation gas; a fuel gas flow channel wall, which is provided on a second surface of the second plate member, is projected from the second surface, and forms a flow channel of fuel gas; a cooling medium flow channel wall, which is provided on a second surface that is a surface on a side opposite to the first surface of the first plate member and faces the second plate member as a groove corresponding to the oxidation gas flow channel wall, is provided on a first surface that is a surface on a side opposite to the second surface of the second plate member and faces the first plate member as a groove corresponding to the fuel gas flow channel wall, and forms a flow channel of a cooling medium; a first through hole, which is formed at a position different from the cooling medium flow channel wall and penetrates the first plate member and the second plate member; a second through hole, which is formed at a position different from the cooling medium flow channel wall and from the first through hole and penetrates the first plate member and the second plate member; a first cooling medium passage part, which is formed by separating a part of the second surface of the first plate member and a part of the first surface of the second plate member from each other and establishes communication between the first through hole and one end of the cooling medium flow channel wall; a second cooling medium passage part, which is formed by separating a part of the second surface of the first plate member and a part of the first surface of the second plate member from each other and establishes communication between the second through hole and the other end of the cooling medium flow channel wall; at least one first gasket line, which is a protrusion formed at a position of the first plate member corresponding to at least one of the first cooling medium passage part and the second cooling medium passage part and projected from the first surface of the first plate member; at least one second gasket line, which is a protrusion formed at a position of the second plate member corresponding to at least one of the first cooling medium passage part and the second cooling medium passage part and projected from the second surface of the second plate member; at least one first groove corresponding to the first gasket line formed on the second surface of the first plate member; at least one second groove corresponding to the second gasket line formed on the first surface of the second plate member; and a projection, which is formed on at least one of the first cooling medium passage part and the second cooling medium passage part, is projected from one toward the other of the second surface of the first plate member and the first surface of the second plate member, is extended in a direction crossing at least one of the first groove and the second grove, is formed to be divided into a plurality of parts with at least one of the first groove and the second groove being sandwiched therebetween, and is separated from the cooling medium flow channel wall.

According to one aspect of the example embodiment, the separator includes: a flat plate-shaped first plate member; a flat plate-shaped second plate member joined with the first plate member; an oxidation gas flow channel wall, which is provided on a first surface of the first plate member and forms a flow channel of oxidation gas; a fuel gas flow channel wall, which is provided on a second surface of the second plate member and forms a flow channel of fuel gas; a cooling medium flow channel wall, which is provided on at least one of a second surface that is a surface on a side opposite to the first surface of the first plate member and faces the second plate member and a first surface that is a surface on a side opposite to the second surface of the second plate member and faces the first plate member, corresponds to at least one of the oxidation gas flow channel wall and the fuel gas flow channel wall, and forms a flow channel of a cooling medium; a first through hole, which is formed at a position different from the cooling medium flow channel wall and penetrates the first plate member and the second plate member; a second through hole, which is formed as a position different from the cooling medium flow channel wall and from the first through hole and penetrates the first plate member and the second plate member; a first cooling medium passage part, which is formed by separating a part of the second surface of the first plate member and a part of the first surface of the second plate member from each other and establishes communication between the first through hole and one end of the cooling medium flow channel wall; a second cooling medium passage part, which is formed by separating a part of the second surface of the first plate member and a part of the first surface of the second plate member from each other and establishes communication between the second through hole and the other end of the cooling medium flow channel wall; and a plurality of projections, which are formed side by side in a cross direction to a passage direction of the cooling medium in at least one of the first cooling medium passage part and the second cooling medium passage part, is projected from one toward the other of the second surface of the first plate member and the first surface of the second plate member, and is separated from the cooling medium flow channel wall, wherein an interval between two projections including a center of a width in the cross direction of at least one of the first cooling medium passage part and the second cooling medium passage part is larger than an interval between an end part in the cross direction of at least one of the first cooling medium passage part and the second cooling medium passage part, and a projection adjacent to the end part.

With a separator of the present disclosure, it becomes possible to construct a separator with two thin metal plates and to maintain a distribution channel of a cooling medium if the separator is subject to pressure in the lamination direction.

DETAILED DESCRIPTION OF NON-LIMITING EXAMPLE EMBODIMENTS

The following description will explain a separator according to one embodiment of the present disclosure and a fuel battery provided with the separator with reference toFIGS. 1A to 7. It is to be noted that the front-back, up-down and right-left directions in these figures are represented by orthogonal arrows in the respective figures.

<Entire Structure of Fuel Battery>

InFIGS. 1A to 1C, a fuel battery1is provided with a stack1A, two end plates1B, a collector plate20(seeFIG. 7) and eight bolts1C. The stack1A is composed of a plurality of laminated unit battery cells100(seeFIG. 4). The two end plates1B are provided on both ends of the stack1A. The eight bolts1C penetrate the stack1A and the two end plates1B in the lamination direction of the plurality of unit battery cells100and sandwich the stack1A and the two end plates1B. As illustrated inFIG. 1C, four of the eight bolts1C and the other four are arranged at equal intervals along the respective first sides S1, which are a pair of long sides that are opposed to each other of each end plate1B. It is to be noted that the longer direction of the two end plates1B illustrated inFIGS. 1A to 1Cis referred herein to as a right-left direction, and the short direction of the two end plates1B is referred herein to as an up-down direction. In addition, the lamination direction of the plurality of unit battery cells100in the stack1A illustrated inFIG. 1Bis referred herein to as a front-back direction.

As illustrated inFIG. 4, each unit battery cell100which constitutes the stack1A has a membrane electrode assembly130, two gaskets120aand120b, and two separators10. One gasket120acontacts with one surface of the membrane electrode assembly130, and the other gasket120bcontacts with the other surface of the membrane electrode assembly130. One of the two separators10contacts with one surface of the membrane electrode assembly130via the gasket120a. The other of the two separators10contacts with the other surface of the membrane electrode assembly130via the gasket120b. The collector plate20illustrated inFIG. 7is laminated adjacent to each of separators10positioned at both ends of the laminate of the unit battery cells100.

As illustrated inFIGS. 1A and 1C, trapezoidal notches2A are provided at the middle in the right-left direction of each end plate1B, which constitutes the stack1A, that is, at the middle of a pair of long sides opposed to each other. Corresponding to the notches2A, trapezoidal notches2B and2C are respectively provided at the separators10illustrated inFIGS. 2A and 2Band at the collector plates20illustrated inFIG. 7. When a fuel battery1is constructed as illustrated inFIG. 1B, all notches2A,2B and2C of the respective end plates1B, the respective separators10and the collector plates20match with each other, and a concave groove is formed over the fuel battery1in the front-back direction.

As illustrated inFIGS. 1B and 1C, terminal parts21of the respective collector plates20are respectively projected from both ends in the front-back direction of concave grooves formed of the notches2A,2B and2C on the upper side of the fuel battery1. Each terminal part21is connected with a power supply wire3to be used for taking out generated electricity. One of these power supply wires3which lies on the front side is installed along a concave groove formed of the notches2A,2B and2C.

As illustrated inFIG. 1C, an oxidation gas introduction port1D is provided at one end side (i.e., left side) in a direction along a long side of the end plate1B on the front side. Moreover, a fuel gas introduction port1F is provided at one end side (i.e., left side) in a direction along a long side of the end plate1B on the front side. The fuel gas introduction port1F is provided at a position lower than the oxidation gas introduction port1D. Here, the fuel battery1is of water cooling type. Cooling water, for example, is used as a cooling medium. A cooling water introduction port1H is provided on the other end side (i.e., right side) in a direction along a long side of the end plate1B on the front side. The cooling water introduction port1H is provided at a position lower than the central position in the up-down direction of the end plate1B on the front side.

On the other hand, as illustrated inFIG. 1A, an oxidation gas discharge port1E is provided on the other end side (i.e., right side) in a direction along a long side of the end plate1B on the back side. A fuel gas discharge port1G is provided on the other end side (i.e., right side) in a direction along a long side of the end plate1B on the back side. The fuel gas discharge port1G is provided at a position upper than the oxidation gas discharge port1E. Moreover, a cooling water discharge port1I is provided on one end side (i.e., left side) in a direction along a long side of the end plate1B on the back surface side. The cooling water discharge port1I is provided at a position upper than the central position in the up-down direction of the end plate1B on the back side.

Next, the separators10, which constitute the aforementioned fuel battery1, will be described with reference toFIGS. 2A, 2B, 3A, 3B and 4.

As illustrated inFIG. 4, one separator10is constructed by joining a first plate member10A and a second plate member10B with each other. The first plate member10A and the second plate member10B respectively have two surfaces. A first surface10aof the first plate member10A is drawn inFIG. 2A. The first surface10aof the first plate member10A is an outer surface on the cathode side where oxidation gas flows. A second surface10dof the second plate member10B is drawn inFIG. 2B. The second surface10dof the second plate member10B is an outer surface on the anode side where fuel gas flows. On the other hand, a second surface10bof the first plate member10A is drawn inFIG. 3A. A first surface10cof the second plate member10B is drawn inFIG. 3B. The second surface10bof the first plate member10A and the first surface10cof the second plate member10B are inner surfaces, which face each other in a state where one separator10is constructed. The aforementioned cooling water flows between the second surface10bof the first plate member10A and the first surface10cof the second plate member10B.

The first plate member10A and the second plate member10B are constituted of thin (e.g., thickness of approximately 1 mm to 2 mm) metal plates such as stainless steel, for example. By respectively processing these two thin metal plates by press work, for example, a convex/concave shape illustrated at the respective surfaces10a,10b,10cand10dinFIGS. 2A, 2B, 3A and 3Bis formed. In a case where press work is conducted, the convex/concave shape formed on the first surface10aof the first plate member10A illustrated inFIG. 2Ais directly inverted and becomes a convex/concave shape on the second surface10bof the first plate member10A illustrated inFIG. 3A. Similarly, a convex/concave shape formed on the second surface10dof the second plate member10B illustrated inFIG. 2Bis directly inverted and becomes a convex/concave shape on the first surface10cof the second plate member10B illustrated inFIG. 3B.

As illustrated inFIG. 4, a pair of separators10, which constitute a unit battery cell100, sandwich both surfaces of the membrane electrode assembly130. Regarding one of the pair of separators10, the first surface10a(i.e., outer surface on the cathode side) of the first plate member10A illustrated inFIG. 2Acontacts with a cathode electrode133of the membrane electrode assembly130. A plurality of convex parts11and concave parts11aare formed alternately on the first surface10aof the first plate member10A.

Moreover, regarding the other of the pair of separators10which constitute a unit battery cell100, the second surface10d(outer surface on the anode side) of the second plate member10B illustrated inFIG. 2Bcontacts with an anode electrode132of the membrane electrode assembly130as illustrated inFIG. 4. A plurality of convex parts19and concave parts19aare formed alternately on the second surface10dof the second plate member10B.

Furthermore, a plurality of concave parts31a, which are obtained by inverting the convex parts11of the first surface10a, and a plurality of convex parts31, which are obtained by inverting the concave parts11aof the first surface10a, are formed alternately on the second surface10bof the first plate member10A illustrated inFIG. 3A. On the other hand, a plurality of concave parts39a, which are obtained by inverting the convex parts19of the second surface10d, and a plurality of convex parts39, which are obtained by inverting the concave parts19aof the second surface10d, are formed alternately on the first surface10cof the second plate member10B illustrated inFIG. 3B. As illustrated inFIG. 4, the concave parts31awhich are formed on the second surface10bof the first plate member10A and the concave parts39awhich are formed on the first surface10cof the second plate member10B are opposed to each other inside one separator10.

InFIG. 2A, a first through hole12is formed to penetrate, in the front-back direction, the left end of the first plate member10A, which constitutes the separator10. A second through hole13is formed to penetrate, in the front-back direction, the right end of the first plate member10A. The plurality of convex parts11are provided in parallel and at intervals in the middle in the right-left direction of the first plate member10A. The plurality of convex parts11are extended from the first through hole12to the second through hole13in the right-left direction. As illustrated inFIG. 4, each of the plurality of convex parts11is projected from the first surface10aof the first plate member10A toward the front side. The top part of each convex part11contacts with the cathode electrode133of the membrane electrode assembly130. Moreover, concave parts11aare respectively formed between respective convex parts11. The bottom part of each of the plurality of concave parts11aand the cathode electrode133are separated from each other. Oxidation gas supplied to the cathode electrode133flows from the first through hole12, flows between the plurality of convex parts11, that is, flows through the plurality of concave parts11a, and is discharged from the second through hole13. That is, a plurality of oxidation gas flow channel walls, which define a flow channel of oxidation gas, are formed of the plurality of convex parts11and the plurality of concave shapes11a.

As illustrated inFIG. 2A, the first plate member10A has an outer shape corresponding to each aforementioned end plate1B and has an elongate shape in the right-left direction. The first plate member10A has the first sides S1, which are the pair of long sides opposed to each other, and second sides S2, which are a pair of short sides opposed to each other. In addition, four bolt through holes18A,18B,18B and18A are provided at equal intervals respectively along the first sides S1of the separator10. The aforementioned eight bolts1C are respectively inserted into these bolt through holes18A and18B.

The aforementioned trapezoidal notches2B are respectively formed in the middle in the right-left direction of the first sides S1of the first plate member10A. These notches2B are formed between two bolt through holes18B and18B, which are adjacent to each other with the center in the right-left direction of the first sides S1being sandwiched therebetween, in the right-left direction.

A first through hole14is formed to penetrate, in the front-back direction, a lower position (i.e., left lower side) on one end side of the first plate member10A. Moreover, a second through hole15is formed to penetrate, in the front-back direction, an upper position (i.e., right upper side) of the other end side of the first plate member10A. The first through hole14is formed between two of a bolt through hole18A and a bolt through hole18B which lie on the left lower side of the first plate member10A. The second through hole15is formed between two of a bolt through hole18A and a bolt through hole18B which are formed on the right upper side of the first plate member10A.

A first through hole16is formed to penetrate, in the front-back direction, a lower position (i.e., right lower side) on the other end side of the first plate member10A. Moreover, a second through hole17is formed to penetrate, in the front-back direction, an upper position (i.e., left upper side) on one end side of the first plate member10A. The first through hole16is formed between two of a bolt through hole18A and a bolt through hole18B which are formed on the right lower side of the first plate member10A. The second through hole17is formed between a bolt through hole18A and a bolt through hole18B which are formed on the left upper side of the first plate member10A.

As illustrated inFIGS. 2A and 4, gasket lines37A and37B projected toward the front side are formed on the first surface10aof the first plate member10A. The gasket lines37A and37B surround the outer circumference of the plurality of convex parts11, the plurality of concave parts11a, the first through hole12and the second through hole13without any space.

<Flow Channel on Anode Side>

InFIG. 2B, a plurality of convex parts19are provided in parallel and at intervals in the middle of the second plate member10B, which constitutes the separator10. The plurality of convex parts19are extended in the right-left direction. As illustrated inFIG. 4, each of the plurality of convex parts19is projected from the second surface10dof the second plate member10B toward the back side. The top part of each convex part19contacts with the anode electrode132of the membrane electrode assembly130. Moreover, concave shapes19aare respectively formed between respective convex parts19. The bottom part of each of the plurality of concave parts19aand the anode electrode132are separated from each other. The width in the right-left direction of a region where the plurality of convex parts19are formed is smaller than the width in the right-left direction of a region where the plurality of convex parts11are formed in the first plate member10A. A pair of a diffusion region19band a transition region19care respectively formed between the left end of the plurality of convex parts19and the first through hole12and between the right end of the plurality of convex parts19and the second through hole13.

A number of elliptical convex parts projected from the second surface10dof the second plate member10B toward the back side are formed in the transition regions19c. All of these elliptical convex parts are extended in a direction of the second side S2(i.e., up-down direction), which is a short side of the second plate member10B. A number of circular convex parts projected from the second surface10dof the second plate member10B to the back side are formed in the diffusion regions19b. The top part of each of the plurality of elliptical convex parts formed in the transition regions19cand the top part of each of the plurality of circular convex parts formed in the diffusion regions19brespectively contact with the anode electrode132. Fuel gas supplied to the anode electrode132flows in from the first through hole14, and the inflow direction is transited in the up-down direction and the right-left direction by the transition region19con the left side. The fuel gas is diffused equally in the up-down direction by the circular convex parts provided in the diffusion region19bon the left side. In addition, fuel gas then flows between the plurality of convex parts19, that is, flows through the plurality of concave parts19a. Fuel gas, which has flown through the plurality of concave parts19a, flows through the diffusion region19bon the right side and the transition region19con the right side, and is discharged from the second through hole15. That is, a plurality of fuel gas flow channel walls, which define a flow channel of fuel gas, are formed of the plurality of convex parts19, the plurality of concave parts19a, the right and left diffusion regions19b, and the right and left transition regions19c. It is to be noted that, instead of the right and left diffusion regions19band the right and left transition regions19c, the left ends of the plurality of concave parts19aand the plurality of convex parts19may be bent downward at a right angle and extended to the first through hole14, and the right ends of the plurality of concave parts19aand the plurality of convex parts19may be bent upward at a right angle and extended to the second through hole15, so that a plurality of serpentine-type fuel gas channel walls are formed.

The gasket lines37A and37B projected toward the back side are formed on the second surface10dof the second plate member10B. The gasket lines37A and37B surround the outer circumference of the plurality of convex parts19, the plurality of concave parts19a, the right and left diffusion regions19b, the right and left transition regions19c, the first through hole14and the second through hole15without any space.

InFIG. 4, the membrane electrode assembly130has a solid polymer electrolyte film131, the anode electrode132and the cathode electrode133. The solid polymer electrolyte film131is proton conductive, in a hydrous state. The solid polymer electrolyte film131is constituted of fluorine polymer having a sulfonic acid group, such as Nafion® (Registered Trademark), for example.

The cathode electrode133contacts with one surface of the solid polymer electrolyte film131. The cathode electrode133has a catalyst layer133aand a gas diffusion layer133b. The gas diffusion layer133bis electrically conductive and is permeable to oxidation gas (e.g., air). The gas diffusion layer133bis constituted of, for example, carbon paper (also referred to as “carbon microfiber”) or the like. The catalyst layer133ais provided between one surface of the membrane electrode assembly130and the gas diffusion layer133b. The catalyst layer133aincludes catalyst, which is composed mainly of carbon powder carrying platinum-based metal catalyst. The catalyst layer133ais formed by applying paste, which is obtained by dispersing catalyst in organic solvent, to carbon paper, which constitutes the gas diffusion layer133b.

The anode electrode132contacts with the other surface of the solid polymer electrolyte film131. The anode electrode132has a catalyst layer132aand a gas diffusion layer132b. The gas diffusion layer132bis electrically conductive and is permeable to fuel gas (e.g., hydrogen). The gas diffusion layer132bis constituted of, for example, carbon paper or the like. The catalyst layer132ais provided between the other surface of the membrane electrode assembly130and the gas diffusion layer132b. The catalyst layer132aincludes catalyst, which is composed mainly of carbon powder carrying platinum-based metal catalyst. The catalyst layer132ais formed by applying paste, which is obtained by dispersing catalyst in organic solvent, to carbon paper, which constitutes the gas diffusion layer132b.

InFIG. 4, the gasket120ais adjacent to the outer circumference of the cathode electrode133and contacts with one surface of the solid polymer electrolyte film131. The gasket120ais constituted of an elastic body such as elastomer or rubber processed to be thin. A plurality of through holes are formed at the gasket120a. The plurality of through holes are formed at positions corresponding to the first through hole12, the second through hole13, the first through hole14, the second through hole15, the first through hole16, and the second through hole17of the separator10, and regions where the plurality of convex parts11and concave parts11aare formed on the first surface10aof the first plate member10A. The gasket120ais pressed by the gasket lines37A and37B which are formed on the first surface10aof the first plate member10A. The gasket120aprevents air, which flows in a flow channel of oxidation gas, from leaking from a unit battery cell100to the outside.

The gasket120bis adjacent to the outer circumference of the anode electrode132and contacts with the other surface of the solid polymer electrolyte film131. The gasket120bis constituted of an elastic body such as elastomer or rubber processed to be thin. A plurality of through holes are formed at the gasket120b. The plurality of through holes are formed at positions corresponding to the first through hole12, the second through hole13, the first through hole14, the second through hole15, the first through hole16, and the second through hole17of the separator10, and regions where the plurality of convex parts19, the plurality of concave parts19a, the right and left diffusion regions19b, and the right and left transition regions19care formed on the second plate member10B. The gasket120bis pressed by the gasket lines37A and37B formed on the second surface10dof the second plate member10B. The gasket120bprevents hydrogen, which flows in a flow channel of fuel gas, from leaking from a unit battery cell100to the outside.

<Operation of Fuel Battery>

Hydrogen as fuel gas is supplied from the fuel gas supply source through piping to the fuel gas introduction port1F. The fuel gas supply source is, for example, a high-pressure hydrogen cylinder, hydrogen storage alloy or the like. Hydrogen gas, which has been supplied from the fuel gas introduction port1F to the inside of the stack1A, flows into the first through hole14of each of the plurality of unit battery cells100laminated in the front-back direction. The hydrogen gas flows from the first through hole14into a flow channel of fuel gas, that is, a region which is formed of a plurality of convex parts19, a plurality of concave parts19a, the right and left diffusion regions19b, and the right and left transition regions19con the second surface10dof the second plate member10B that constitutes the separator10, and the anode electrode132. Hydrogen is diffused in the surface direction (i.e., up-down and right-left directions) of the membrane electrode assembly130by the diffusion layer132bof the anode electrode132, and contacts with the catalyst layer132aof the anode electrode132. Hydrogen gas, which has contacted with the catalyst layer132a, is separated into a hydrogen ion and an electrode by catalyst included in the catalyst layer. Hydrogen ions are conducted by the solid polymer film131and reach the catalyst layer133aof the cathode electrode133. On the other hand, electrons are taken out from a terminal part21on the front side. Hydrogen gas, which has contacted with the anode electrode132, is discharged from the second through hole15through the fuel gas discharge port1G to the outside of the stack1A.

On the other hand, air as oxidation gas is supplied from an unillustrated air compressor through piping to the oxidation gas introduction port1D. Air, which has been supplied to the oxidation gas introduction port1D, flows into a first through hole12of each of a plurality of unit battery cells100laminated in the front-back direction. Air flows from the first through hole12into a flow channel of oxidation gas, that is, a region, which is formed of the plurality of convex parts11, the plurality of concave shapes11aand the cathode electrode133. Air is diffused in the surface direction (i.e., up-down and right-left directions) of the membrane electrode assembly130by the diffusion layer133bof the cathode electrode133, and contacts with the catalyst layer133aof the cathode electrode133. Oxygen included in air is caused by catalyst included in the catalyst layer133ato react with hydrogen ions, which has been conducted by the solid polymer film131, and with electrodes, which have been taken out from the terminal part21on the front side and conducted through an external load from a terminal part21on the back surface side, and generates water. This electrode transfer generates electric power. Air, which has contacted with the cathode electrode133, reaches the second through hole13together with the generated water, and is discharged from the stack1A through the oxidation gas discharge port1E.

As described above, the second surface10bof the first plate member10A and the first surface10cof the second plate member10B are inner surfaces, which face each other in a state where one separator10is constructed. Cooling water, which functions as a cooling medium, flows between the second surface10bof the first plate member10A and the first surface10cof the second plate member10B. The following description will explain a convex/concave shape formed on the second surface10bof the first plate member10A and on the first surface10cof the second plate member10B.

As illustrated inFIGS. 3A and 4, the first plate member10A of two metal plates, which constitute the separator10, lies on the front side. The plurality of convex parts31, which are convex to the back side, and the plurality of concave parts31a, which are concave to the front side, are formed on the second surface10bof the first plate member10A. The convex parts31correspond to the concave parts11aformed on the first surface10aof the first plate member10A. The concave parts31acorrespond to the convex parts11formed on the first surface10aof the first plate member10A.

As illustrated inFIGS. 3B and 4, the second plate member10B of two metal plates, which constitute the separator10, lies on the back side. The plurality of convex parts39, which are convex to the front side, and the plurality of concave parts39a, which are concave to the back side, are formed on the first surface10cof the second plate member10B. The convex parts39correspond to the concave parts19aformed on the second surface10dof the second plate member10B. The concave parts39acorrespond to the convex parts19formed on the second surface10dof the second plate member10B.

When the second surface10bof the first plate member10A and the first surface10cof the second plate member10B are bonded with each other, the top part of each convex part31and the top part of each convex part39are opposed and contact to each other. Cooling water flows through a region, which is formed of the concave parts31aand the concave parts39aand is sandwiched by the convex parts31and the convex parts39adjacent to each other in the up-down direction. That is, a plurality of cooling medium flow channel walls, which define a flow channel of cooling water, are composed of the convex parts31, the convex parts39, the concave parts31aand the concave parts39a.

Here, a region39cwhich lies on the right side of the first surface10cof the second plate member10B illustrated inFIG. 3Bcorresponds to the transition region19cwhich lies on the left side of the second surface10dof the second plate member10B illustrated inFIG. 2B. Similarly, a region39cwhich lies on the left side of the first surface10cof the second plate member10B illustrated inFIG. 3Bcorresponds to the transition region19cwhich lies on the right side of the second surface10dof the second plate member10B illustrated inFIG. 2B.

A number of elliptical convex parts formed in the transition region19cillustrated inFIG. 2Bare inverted into a number of elliptical concave parts formed in the region39cillustrated inFIG. 3B. The length in the direction of the second side S2(i.e., up-down direction) of an elliptical concave part, which is formed in the region39c, is set equal to or larger than the length from one concave part31ato the other concave part31awhich are adjacent to each other and formed on the second surface10bof the first plate member10A illustrated inFIG. 3A. With such a structure, in the case where the first surface10cof the second plate member10B and the second surface10bof the first plate member10A are bonded with each other and the separator10is constructed, an elliptical concave part formed in the region39cof the first surface10coverlaps with two adjacent concave parts31aon the second surface10b, so that an inner flow channel which establishes communication in the up-down and right-left directions is formed. As a result, cooling water, which has been supplied from the first through hole16to the inside of the separator10, flows through the elliptical concave part in the region39con the right side inFIG. 3Band into the right end of the concave part31aillustrated inFIG. 3A. Then, after reaching the left end of the concave part31a, cooling water flows through an elliptical concave part in the region39con the left side inFIG. 3Band is discharged from the second through hole17.

Regarding the separator10, in the case where the second surface10bof the first plate member10A and the first surface10cof the second plate member10B are bonded with each other, a part of the second surface10band a part of the first surface10care separated from each other and a cooling water passage part (cooling medium passage part) is formed. The cooling water passage part is space which is formed when the second surface10bof the first plate member10A and the first surface10cof the second plate member10B are separated from each other. However, for convenience of explanation, a part of the second surface10band a part of the first surface10c, which define the cooling water passage part, are represented as a cooling water passage part inFIGS. 3A, 3B, 5A, 5B, 6A and 6B.

On the second surface10bof the first plate member10A illustrated inFIG. 3A, a first cooling water passage part32is formed in a region between the first through hole16and a lower right convex part31nearest to this first through hole16. Similarly, a second cooling water passage part33is formed in a region between the second through hole17and an upper left convex part31nearest to this second through hole17. The first cooling water passage part32and the second cooling water passage part33illustrated inFIG. 3Aare an example of a cooling medium passage part.

On the first surface10cof the second plate member10B illustrated inFIG. 3B, a first cooling water passage part34is formed in a region between the first through hole16and the lower end of the region39con the right side. Similarly, a second cooling water passage part35is formed in a region between the second through hole17and the upper end of the region39con the left side. The first cooling water passage part34and the second cooling water passage part35illustrated inFIG. 3Bare an example of a cooling medium passage part.

One separator10is constructed by bonding the second surface10bof the first plate member10A and the first surface10cof the second plate member10B with each other. Here, the first cooling water passage part32of the second surface10band the first cooling water passage part34of the first surface10care separated from each other, and space where cooling water can flow is formed (seeFIG. 5B). Similarly, the second cooling water passage part33of the second surface10band the second cooling water passage part35of the first surface10care separated from each other, and space where cooling water can flow is formed. Space formed of the two first cooling water passage parts32and34establishes communication between the first through hole16and the right end of the aforementioned cooling water flow channel wall. On the other hand, space formed of the two second cooling water passage parts33and35establishes communication between the second through hole17and the left end of the aforementioned cooling water flow channel wall.

Cooling water as a cooling medium is supplied from an unillustrated pump through piping to the cooling water introduction port1H. Cooing water, which has been supplied from the cooling water introduction port1H to the inside of the stack1A, flows into the first through hole16of each of the plurality of unit battery cells100laminated in the front-back direction. Cooling water, which has flown into the first through hole16, flows through space which is formed of the two first cooling water passage parts32and34into the right end of a flow channel of cooling water. As described above, a flow channel of cooling water is a region which is defined by a cooling water flow channel wall that is composed of the convex part31, the convex part39, the concave part31aand the concave part39a, between the second surface10bof the first plate member10A and the first surface10cof the second plate member10B. Cooling water flows from the right end to the left end of the flow channel of cooling water. Cooling water, which has reached the left end of the flow channel of cooling water, flows through space which is formed of the two second cooling water passage parts33and35into the second through hole17. Cooling water, which has flown into the second through hole17, is discharged from the cooling water discharge part1I to the outside.

<Projection According to First Embodiment>

As described above, cooling water in the separator10flows through space which is formed of the first cooling water passage parts32and34, and space which is formed of the second cooling water passage parts33and35. However, the separator10is composed of the first plate member10A and the second plate member10B, which are two thin metal plates illustrated inFIGS. 2A, 2B, 3A and 3B. Moreover, the stack1A is composed of a plurality of laminated separators10. The separator10is therefore subject to pressure in the lamination direction (i.e., front-back direction) generated by fastening of the eight bolts1C. If the first cooling water passage parts32and34and the second cooling water passage parts33and35lie around the bolt through holes18A and18B as illustrated inFIGS. 3A and 3B, for example, pressure in the lamination direction with a relatively large ratio is applied to the first cooling water passage parts32and34and the second cooling water passage parts33and35. Moreover, the gasket lines37A and37B illustrated inFIGS. 2A and 2Bare provided on surfaces on opposite sides corresponding to the first cooling water passage parts32and34and the second cooling water passage parts33and35, for example. Repulsive force applied from the gaskets120aand120bto the gasket lines37A and37B is therefore applied directly to the first cooling water passage parts32and34and the second cooling water passage parts33and35. If such pressure or repulsive force deforms the part of the first cooling water passage parts32and34and the part of the second cooling water passage parts33and35in the thin metal plates which constitute the separator10, space where cooling water can flow is closed. In order to solve such a problem, a plurality of projections36are respectively formed at the first cooling water passage part32and the second cooling water passage part33of the first plate member10A illustrated inFIG. 3A.

The following description will explain the projections36according to First Embodiment of the present disclosure with reference toFIGS. 3A, 5A and 5B. It is to be noted that projections36provided at the first cooling water passage part32and projections36provided at the second cooling water passage part33have the same structure as illustrated inFIG. 3A. Therefore, projections36provided at the first cooling water passage part32will be described in First Embodiment. Description of projections36provided at the second cooling water passage part33will be omitted.

As illustrated inFIGS. 3A and 5A, two projections36are provided at the first cooling water passage part32by press work. The projections36are extended in the up-down direction. One projection36is composed of a first projection part36A and a second projection part36B. The length of the first projection part36A in the up-down direction is larger than the length of the second projection part36B in the up-down direction. The first projection part36A and the second projection part36B are formed on the same line along the up-down direction. As illustrated inFIG. 5B, a projection36is projected from the second surface10bof the first plate member10A toward the first cooling water passage part34formed on the first surface10cof the second plate member10B. A projection36of First Embodiment has a height from the second surface10bof the first plate member10A to the first cooling water passage part34formed on the first surface10cof the second plate member10B.

Two projections36are provided side by side in the longer direction of the first cooling water passage part32. Cooling water flows through the first cooling water passage part32in the short direction (i.e., up-down direction) thereof. That is, the two projections36are provided side by side in a direction crossing the passage direction of the cooling water (i.e., right-left direction). Moreover, each projection36is extended straight in the up-down direction along the passage direction of the cooling water. Accordingly, none of the projections36blocks passage of cooling water.

Here, as illustrated inFIGS. 3A and 5A, two gasket lines37A and37B are provided in parallel along the longer direction of the first cooling water passage part32at positions corresponding to the first cooling water passage part32on the first surface10aof the first plate member10A. The gasket lines37A and37B are protrusions for supporting a part of the gasket120a. As illustrated inFIG. 4, the gasket lines37A and37B constitute protrusions, which are convex toward the front side, on the first surface10aof the first plate member10A. On the other hand, the gasket lines37A and37B constitute grooves, which are obtained by inverting the protrusions and are concave toward the front side, on the second surface10bof the first plate member10A.

As illustrated inFIG. 5A, the two projections36are extended in a direction crossing the gasket lines37A and37B. Each projection36is formed to be divided into the first projection part36A and the second projection part36B with the gasket lines37A being sandwiched therebetween.

As illustrated inFIG. 5A, the lower end of the first projection part36A is provided continuously to an edge part which defines the first through hole16. The upper end of the first projection part36A finishes in front of the gasket line37A and does not cross the gasket line37A. The second projection part36B lies between the gasket line37A and the gasket line37B. The lower end of the second projection part36B finishes in front of the gasket line37A and does not cross the gasket line37A. The upper end of the second projection part36B finishes in front of the gasket line37B and does not cross the gasket line37B.

The projection36is not provided in a region upper than the gasket line37B in the first cooling water passage part32. That is, every upper end of the projection part36is separated from a cooling water flow channel wall, which is composed of the convex parts31, the convex parts39, the concave parts31aand the concave parts39aillustrated inFIGS. 3A and 3B.

The projections36having such a structure forms three spaces SP1, SP2and SP3illustrated inFIG. 5Bbetween the respective first cooling water passage parts32and34, when the second surface10bof the first plate member10A and the first surface10cof the second plate member10B are bonded with each other. Cooling water, which has flown in from the first through hole16, flows through the three spaces SP1, SP2and SP3from the lower side to the upper side to one end (i.e., right end) of a cooling water flow channel wall, which is composed of the convex parts31, the convex parts39, the concave parts31aand the concave parts39aillustrated inFIGS. 3A and 3B.

As illustrated inFIGS. 5A and 5B, the width of the first cooling water passage part32in the longer direction (i.e., right-left direction) is defined by two end parts E. The width L1of the first through hole16in the longer direction is larger than the width of the first cooling water passage part32in the longer direction. Two projections36of First Embodiment are provided at positions to equally divide the width L1of the first through hole16in the longer direction into three. The interval L2between two projections36including the center of the width of the first cooling water passage part32in the longer direction is therefore larger than the interval L3between an end part E of the first cooling water passage part32in the longer direction and a projection36adjacent to this end part E. The interval L2between the two projections36is set equal to or larger than 5 mm, and equal to or smaller than 20 mm. Similarly, the interval L3between a projection36and an end part E is set equal to or larger than 5 mm, and equal to or smaller than 20 mm.

<Projection According to Second Embodiment>

Next, projections38according to Second Embodiment of the present disclosure will be explained with reference toFIGS. 6A and 6B. In Second Embodiment, like codes will be attached to components similar to those of Embodiment 1, and detailed description thereof will be omitted.

In Second Embodiment, two projections38are provided at both of the first cooling water passage part32, which is formed on the second surface10bof the first plate member10A, and the first cooling water passage part34, which is formed on the first surface10cof the second plate member10B, as illustrated inFIG. 6B. Projections38provided at the first plate member10A and projections38provided at the second plate member10B correspond to each other. When the second surface10bof the first plate member10A and the first surface10cof the second plate member10B are bonded with each other, corresponding projections38come into contact with each other. This forms three spaces SP1, SP2and SP3between the first cooling water passage part32of the first plate member10A and the first cooling water passage part34of the second plate member10B. Cooling water, which has flown into the first through hole16, flows through these three spaces SP1, SP2and SP3from the lower side to the upper side to one end (i.e., right end) of a cooling water flow channel wall, which is composed of the convex parts31, the convex parts39, the concave parts31aand the concave parts39aillustrated inFIGS. 3A and 3B. The height of each projection38is ½ of the height of these three spaces SP1, SP2and SP3.

As illustrated inFIG. 6A, the projections38provided at the first plate member10A are provided at positions, which equally divide the width L4of the cooling medium passage part32in the longer direction (i.e., right-left direction) into three. Therefore, the interval L5between the two projections38including the center of the width of the first cooling water passage part32in the longer direction is equal to the interval L5between an end part E of the first cooling water passage part32and a projection38adjacent to this end part E as illustrated inFIG. 6B. Both of these intervals L5are set equal to or larger than 5 mm, and equal to or smaller than 20 mm. Projections38provided at the second plate member10B have the same structure as that of the aforementioned projections38provided at the first plate member10A.

Next, a collector plate20, which constitutes the aforementioned fuel battery1of Second Embodiment, will be described with reference toFIG. 7.

InFIG. 7, the collector plate20is constituted of a metal plate having the same outer shape as that of the aforementioned separator10. First through holes22,24and26and second through holes23,25and27are provided to have outer shapes and positions corresponding to those of respective the first through holes12,14and16and the second through holes13,15and17illustrated inFIG. 2B. The collector plate20is also provided with eight bolt through holes28A and28B having outer shapes and positions corresponding to those of the respective bolt through holes18A and18B illustrated inFIG. 2B.

Here, unlike the aforementioned separator10, a terminal part21is provided continuously to an upper notch2C of the collector plate20. This terminal part21is projected in a direction crossing a first side S1, which is a long side of the collector plate20. In Second Embodiment, the projection length of the terminal part21is set equal to the height of the first side S1(see the dotted line in the figure), so that the terminal part21is not projected from the notch2C.

Moreover, the formation position of the terminal part21in Second Embodiment is shifted from the center (see the long dashed short dashed line in the figure) in the right-left direction of the notch2C to the left side. With such a structure, installation space L for power supply wiring3(seeFIGS. 1A to 1C) is formed in the notch2C, and power supply wiring3connected with the terminal part21can be kept in the notch2C in a favorable manner.

Although Second Embodiment has a structure wherein the collector plate20is not provided with any convex-concave shape to constitute a flow channel wall of oxidation gas or fuel gas, it is to be noted that the present embodiment may have a structure that the collector plate20is provided with flow channel walls of oxidation gas and fuel gas formed on any one surface, since the collector plate20is laminated on both ends of the stack1a, which is laminate of unit battery cells.

Separators10of First Embodiment and Second Embodiment have structures wherein projections36and38illustrated inFIGS. 5A and 5BorFIGS. 6A and 6Bare provided. The projections36and38are interposed in space between the first cooling water passage part32, which is formed on the second surface10bof the first plate member10A, and the first cooling water passage part34, which is formed on the first surface10cof the second plate member10B. The projections36and38withstand pressure from the separator10in the lamination direction caused by fastening of the eight bolts1C, and repulsive force applied from the gaskets120aand120bto the gasket lines37A and37B, and suppress deformation, such as deflection or collapse, of thin metal plates corresponding to the part of the first cooling water passage parts32and34. This maintains space where cooling water can flow in or out the separator10.

As illustrated inFIGS. 5A and 6A, one projection36,38is formed to be divided into a first projection part36A and a second projection part36B with a gasket line37A being sandwiched therebetween. With such a structure, the airtightness of the gasket line37A is maintained. That is, on the first surface10aof the first plate member10A, the gasket line37A constitutes a protrusion, and the projections36and38are inverted and constitute a groove. If one projection36,38is provided to cross the gasket line37A, a protrusion as the gasket line37A on the first surface10aof the first plate member10A is divided in the middle in the longer direction (i.e., right-left direction) by a groove obtained by inverting the projections36and38. If the gasket line37A is divided by a groove, the airtightness of the gasket line37A is deteriorated at the divided part. Accordingly, the continuity of the gasket line37A is maintained by the structure wherein one projection36,38extended in a direction crossing the gasket line37A is formed to be divided into a first projection part36A and a second projection part36B with the gasket line37A being sandwiched therebetween. As a result, the airtightness of the gasket line37A is maintained.

The upper ends of the projections36and38illustrated inFIGS. 5A and 6Aare separated from all of the convex parts31, the convex parts39, the concave parts31aand the concave parts39aillustrated inFIGS. 3A and 3B. With such a structure, cooling water, which has been guided by the projections36and38from the lower side to the upper side of the first cooling water passage parts32and34, spreads in the right-left direction in front of the cooling water flow channel wall, which is composed of the convex parts31, the convex parts39, the concave parts31aand the concave parts39a. As a result, cooling water, which has flown through the first cooling water passage parts32and34, flows smoothly into a flow channel of cooling water defined by the cooling water flow channel wall.

Since the intervals L2, L3and L5illustrated inFIGS. 5Band6B are set equal to or larger than 5 mm, preferable flow of cooling water through the three spaces SP1, SP2and SP3is achieved. On the other hand, since these intervals L2, L3and L5are set equal to or smaller than 20 mm, thin metal plates corresponding to the part of the first cooling water passage parts32and34are divided to have a hardly deformable length. This enhances the rigidity of the thin metal plates corresponding to the part of the first cooling water passage parts32and34, and suppresses deformation thereof.

As in Second Embodiment illustrated inFIGS. 6A and 6B, the height of each projection38becomes smaller in case where projections38corresponding to each other are provided at both of the first cooling water passage part32, which is formed on the second surface10bof the first plate member10A, and the first cooling water passage part34, which is formed on the first surface10cof the second plate member10B. This decreases the drawing amount of the metal plates in the process of forming of the projections38by press work, and facilitates processing of the projections38.

Accordingly, since the projections36and38are provided as described above, the separator10can be constructed with thinner metal plates. As two metal plates which constitute the separator10become thinner, miniaturization and weight reduction of the stack1A are achieved.

It is to be noted that similar effects are obtained and the present embodiment contributes to thinning of two metal plates which constitute the separator10, even in case where the aforementioned projections36and38are provided at the second cooling water passage part33of the first plate member10A illustrated inFIG. 3Aand at the second cooling water passage part35of the second plate member10B illustrated inFIG. 3B.

A separator according to the present disclosure is not limited to the structure described above. For example, a metal plate which constitutes the separator is not limited to a plate processed by press work. For example, the separator may be constituted of a metal plate processed by cutting work. Moreover, projections to be provided at the first cooling water passage part and the second cooling water passage part are not limited to the illustrated structure. For example, the number, shape, interval or the like of projections may be modified.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. Since the scope of the present invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope defined by the appended claims are also included in the technical scope of the present invention.