JP2013246895A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem of a conventional fuel cell stack that it is difficult to make a single cell thin, while maintaining a displacement absorption function, and thereby it is difficult to make the fuel cell stack compact.SOLUTION: In a fuel cell stack FS where a plurality of single cells C, each consisting of a membrane electrode assembly 1 held by a pair of separators 2, are laminated, a circulation space F of cooling liquid is formed between adjoining single cells C, and a displacement absorption member 10 is placed in the space F. The separator 2 has an uneven cross-sectional shape continuously in the circulation direction of the cooling liquid. The displacement absorption member 10 is such a member that, when it deforms in the thickness direction, the contact part with the separator 2 moves in the in-plane direction. Moving direction of the contact part is the continuous direction of the uneven shape of the separator 2, and the displacement absorption member 10 is in contact with the protrusions 2A of the separator 2. The fuel cell stack is thereby made compact while maintaining excellent displacement absorption function between the single cells C.

Description

  The present invention relates to a fuel cell such as a polymer electrolyte fuel cell (PEFC), and more particularly to a fuel cell stack having a structure in which a coolant is circulated between stacked single cells.

  Conventionally, as a fuel cell stack as described above, for example, there is one described in Patent Document 1 as a fuel cell. The fuel cell described in Patent Document 1 is a stack of a plurality of fuel cells. The fuel cell includes a hydrogen electrode having a concavo-convex shape on both sides of an MEA (membrane electrode assembly) and an oxygen electrode including a drainage layer having a concavo-convex shape, and between the hydrogen electrode and the oxygen electrode. A flat plate separator for forming a hydrogen channel and an oxygen channel is provided. Further, the fuel cell includes a refrigerant flow path portion on the oxygen electrode side.

  The refrigerant flow path section includes two flat plate separators and a preload plate sandwiched therebetween, and a cooling water flow path is formed between the two flat plate separators. The preload plate has a cross-sectional wave shape, and applies a uniform load to each component by dispersing a load generated locally due to a shape error of each component of the fuel cell.

Japanese Patent No. 4432518

  By the way, when this type of fuel cell stack is used as a power source for a vehicle such as an automobile, the mounting space is limited and the miniaturization is very important. However, in the conventional fuel cell stack (fuel cell) as described above, a single cell (fuel cell) is a combination of an electrode having an uneven cross-sectional shape, a flat plate separator, and a pressurizing plate. It has been difficult to reduce the thickness of a single cell while maintaining its function, making it difficult to reduce the size of the fuel cell stack.

  The present invention has been made in view of the above-described conventional situation, and is a fuel cell stack having a structure in which a coolant is circulated between stacked single cells, and has a good displacement absorbing function between the single cells. It aims at providing the fuel cell stack which can implement | achieve size reduction, maintaining.

  The fuel cell stack according to the present invention is configured by laminating a plurality of single cells formed by sandwiching a membrane electrode assembly between a pair of separators. The fuel cell stack includes a displacement absorbing member that forms a coolant circulation space between adjacent single cells and absorbs the displacement between the single cells arranged in the circulation space. Convex and concave shapes are continuously provided in the flow direction of the coolant.

  In the fuel cell stack, the displacement absorbing member is a member in which the contact portion with the separator moves in the in-plane direction with deformation in the thickness direction, and the moving direction of the contact portion is a continuous direction of the unevenness of the separator. The arrangement is such that it is in contact with the convex portion of the separator, and the above arrangement is used as a means for solving the conventional problems.

  The fuel cell stack according to the present invention is a fuel cell stack having a structure in which a coolant is circulated between stacked single cells, and can achieve downsizing while maintaining a good displacement absorbing function between the single cells. it can.

It is sectional drawing (A) of the uneven | corrugated width direction explaining one Embodiment of the fuel cell stack concerning this invention, and sectional drawing (B) of the continuous direction of uneven | corrugated shape. It is the perspective view (A) explaining a displacement absorption member, and the side view (B) explaining operation | movement of a spring function part. FIG. 6 is a cross-sectional view (A) (B) for explaining still another embodiment of the fuel cell stack according to the present invention. FIG. 6 is a cross-sectional view (A) (B) for explaining still another embodiment of the fuel cell stack according to the present invention. It is a perspective view explaining further another embodiment of the fuel cell stack concerning the present invention. It is sectional drawing (A) and the perspective view (B) of the continuous direction of uneven | corrugated shape explaining further another embodiment of the fuel cell stack concerning this invention.

  A fuel cell stack FS shown in FIGS. 1A and 1B is formed by stacking a plurality of single cells C that are power generation elements. The fuel cell stack FS includes a displacement absorbing member 10 that forms a coolant circulation space F between adjacent unit cells C and that is disposed in the circulation space F to absorb displacement between the unit cells C. I have.

  The single cell C has a structure in which the membrane electrode assembly 1 is sandwiched between a pair of separators 2 and 2. The membrane electrode structure 1 is generally called a MEA (Membrane Electrode Assembly), and detailed illustration is omitted. However, an electrolyte layer made of a solid polymer membrane is formed of a pair of electrode layers, an anode layer and a cathode layer. Is sandwiched between. The anode layer and the cathode layer have a structure in which a catalyst layer and an appropriate number of gas diffusion layers are laminated.

  The separators 2 and 2 are made of, for example, stainless steel, and at least a portion corresponding to the membrane electrode assembly 1 is formed in a concavo-convex shape. The separators 2 and 2 have the cross-sectional irregularities continuously in the flow direction of the coolant (the direction of arrow A in FIG. 1B), and the anode gas (between the membrane electrode assembly 1 and the anode gas ( Gas flow paths 3 and 3 for hydrogen-containing gas) and cathode gas (oxygen-containing gas: air) are formed. In addition, the separator 2 in the illustrated example has a convex portion 2A and a concave portion 2B each having a square cross section. Therefore, the upper surface of the convex portion 2A is a plane.

  In the fuel cell stack FS, the coolant flow direction (arrow A direction) in the flow space F, the anode gas flow direction (arrow B direction), and the cathode gas flow direction (arrows) in the gas flow paths 3 and 3. C direction) is in the same direction.

  The separator 2 has an inverted shape. Therefore, in the separator 2, the convex portion 2A protruding to the flow space F side becomes a concave portion on the opposite side, and the concave portion 2B opened to the flow path space F side becomes a convex portion on the opposite side. Such a separator 2 can be manufactured by, for example, press working, and the uneven shape can increase the mechanical strength and form channels on both sides, so that the membrane electrode assembly 1 is thin. And thinning of the single cell C can be realized.

  In addition, between the membrane electrode assembly 1 and each separator 2 or between adjacent single cells C, that is, the flow path space F, an appropriate gas seal is applied to the outer periphery, and is not shown between the layers. Anode gas, cathode gas and coolant are circulated through the supply path and the discharge path.

  In general, the displacement absorbing member 10 is a member in which a contact portion with the separator 2 moves in an in-plane direction (left-right direction in FIG. 1B) with deformation in the thickness direction. The displacement absorbing member 10 is arranged so that the moving direction of the contact portion is the continuous direction of the uneven shape of the separator 2. In addition, the uneven | corrugated continuous direction is a direction (longitudinal direction of the convex part 2A and the recessed part 2B) where the uneven | corrugated shaped cross section continues, and is not a direction where an unevenness | corrugation continues in order.

  As shown in FIG. 2A, the displacement absorbing member 10 of this embodiment is made of a thin metal plate and has conductivity to serve as a connector between the single cells C, and is provided on one side of the substrate 10A. This is a structure in which a large number of spring function portions 10B are arranged vertically and horizontally. As a result, the displacement absorbing member 10 has the substrate 10A in contact with one separator 2 (the lower separator of the single cell C in FIG. 1) of the pair of separators 2 and 2 facing each other through the flow space F. Then, the spring function portion 10B contacts the other separator 2 (the upper separator of the single cell C in FIG. 1).

  The spring function portion 10B has a tongue-like shape with a cantilever structure in which a base end is a fixed end to the substrate 10A and a distal end side is a free end. As shown in FIG. 2 (B), the spring function portion 10B changes its angle with the substrate 10A in accordance with the deformation in the thickness direction, and the tip of the free end that is a contact portion with the separator 2 is indicated by an arrow. As shown, it is displaced in the continuous direction of the concavo-convex shape which is the in-plane direction.

  Further, the displacement absorbing member 10 is formed in a state in which each spring function portion 10B is cut and raised from the substrate 10A. Thereby, 10 A of board | substrates have the opening part 10C formed by the raising and lowering of the spring function part 10B below each spring function part 10B. Further, in the displacement absorbing member 10, at least one of the spring function portions 10B is arranged with the free end directed downstream in the flow direction of the coolant, and in the illustrated example, all the spring function portions 10B are arranged. The same direction.

  In the fuel cell stack FS having the above-described configuration, the single cell C is a combination of the separator 2 having the concavo-convex shape of the cross section and the displacement absorbing member 10, so that the gas flow path 3 and the circulation space F of the coolant are predetermined. It is efficiently arranged with the flow path area, and the single cell C is thinned.

  Further, the fuel cell stack FS absorbs the displacement between the single cells C by the displacement absorbing member 10. At this time, the fuel cell stack FS is arranged so that the direction of the spring function portion 10B of the displacement absorbing member 10 matches the continuous direction of the uneven shape of the separator 2, and the convex portion of the separator 2 that the spring function portion 10B contacts. The upper surface of 2A is a plane.

  Thereby, in the fuel cell stack FS, even if the contact portion between the free end of the spring function portion 10B and the separator 2 moves as shown in FIG. Since the free end of the spring function portion 10B is always in contact with the upper surface of the convex portion 2A and does not fall into the concave portion 2B, the displacement absorbing function of the displacement absorbing member 10 can be sufficiently exhibited. Moreover, since the free end of the spring function portion 10B and the convex portion 2A of the separator 2 are in surface contact, the contact resistance between the separator 2 and the displacement absorbing member 10 can be reduced.

  In this way, the fuel cell stack FS has a structure that allows the coolant to flow between the stacked single cells C, and realizes downsizing while maintaining a good displacement absorbing function between the single cells C. Can do.

  Further, in the fuel cell stack FS, in the flow space F, the displacement absorbing member 10 is disposed with the free ends of the spring function portions 10B facing the downstream side in the flow direction of the cooling liquid. It becomes easy to flow and the pressure loss of the coolant can be reduced.

  Further, in the fuel cell stack FS, the flow direction of the coolant in the flow space F (the direction of the arrow A) and the flow direction of the gas in the gas flow paths 3 and 3 (the directions of the arrows A and B) are the same direction. Since the flow direction of the coolant (arrow A direction) and the flow direction of the anode gas (arrow B direction) are the same direction, the temperature control of the reaction surface of the membrane electrode assembly 1, that is, the gas flow direction of the reaction surface Control of the temperature field can be facilitated.

  3-6 is a figure explaining other embodiment of the fuel cell stack of this invention. In the following embodiments, the same components as those of the previous embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

   In the displacement absorbing member 10 of the fuel cell stack shown in FIG. 3A, the width Wa of the free end of the spring function portion 10B is larger than the width Wb of the convex portion 2A of the separator 2 with which the spring function portion 10B contacts. It has become.

  The fuel cell stack having the above-described configuration can obtain the same effects as those of the previous embodiment, and the free end of the spring function portion 10B always comes into contact with the upper surface of the convex portion 2A, so that the concave portion 2B It is possible to obtain a large electrical contact area.

  In the displacement absorbing member 10 of the fuel cell stack shown in FIG. 3B, the width Wa of the free end of the spring function portion 10B is larger than the width Wc of the recess 2B of the separator 2 with which the spring function portion 10B contacts. It has become.

  Even in the fuel cell stack having the above-described configuration, the same effect as in the previous embodiment can be obtained, and the free end of the spring function portion 10B always comes into contact with the upper surface of the convex portion 2A. Further, the depression into the recess 2B is prevented, and the electrical contact area can be increased.

  In the displacement absorbing member 10 of the fuel cell stack shown in FIG. 4A, the free end of the spring function portion 10B is in contact with the plurality of convex portions 2A of the separator 2 with which the spring function portion 10B contacts. In the example of illustration, the free end of the spring function part 10B is contacting the two adjacent convex parts 2A and 2A.

  The fuel cell stack having the above configuration can obtain the same effects as those of the previous embodiment, and can reduce the pressure loss of the coolant. That is, in the fuel cell stack, as described above, the free end of each spring function portion 10B is directed to the downstream side in the flow direction of the coolant to facilitate the flow of the coolant. It is inevitable that the spring function part 10B interferes itself.

  Therefore, in the fuel cell stack, the free end of the spring function portion 10B is brought into contact with the plurality of convex portions 2A of the separator 2 to secure a flow path by the recess portion 2B of the separator 2 in the portion where the spring function portion 10B is disposed. That is, the concave portions 2B between the plurality of convex portions 2A and 2A with which the spring function portion 10B comes into contact are ensured as a flow path of the arrangement portion of the spring function portion 10B. Thereby, the fuel cell stack can distribute the coolant to the arrangement portion of the spring function unit 10B, improve the flowability in the arrangement portion, and reduce the pressure loss of the coolant as a whole.

  As described above with reference to FIG. 2A, the displacement absorbing member 10 of the fuel cell stack shown in FIG. 4B has a substrate 10A of the displacement absorbing member 10 having an opening portion below each spring function portion 10B. 10C. In the fuel cell stack, the recess 2B of the separator 2 with which the substrate 10A comes into contact is communicated with the opening 10C.

  In the fuel cell stack described above, on the side of the separator 2 with which the substrate 10A comes into contact, a flow path by the recess 2B and the opening 10C is secured in the arrangement portion of the spring function portion 10B. Thereby, the fuel cell stack can distribute the coolant to the arrangement portion of the spring function unit 10B, improve the flowability in the arrangement portion, and reduce the pressure loss of the coolant as a whole.

  4A and 4B, in the separators 2 and 2 on the upper and lower sides of the displacement absorbing member 10, a flow path is secured by the upper and lower recesses 2B and 2B and the opening 10C. The flowability in the arrangement part of the spring function part 10B can be further enhanced.

  The displacement absorbing member 10 of the fuel cell stack shown in FIG. 5 includes springs on the substrate 10A in the continuous direction of the concavo-convex shape of the separator 2 (upward in the figure) and in the width direction (left and right in the figure) intersecting this. The functional units 10B are arranged, and the spring functional units 10B adjacent in the width direction are offset (arrow OS) in the continuous direction of the concavo-convex shape. The offset amount in the illustrated example is approximately one spring function portion 10B. The continuous direction of the uneven shape of the separator 2 is the same as the flow direction of the coolant.

  In the above fuel cell stack, in the in-plane direction, as indicated by the arrows in the figure, the coolant flows around the spring function unit 10B to the left and right, and the number of points where the coolant stagnates is reduced. The pressure loss of the coolant can be reduced. Further, when the fuel cell stack described above is combined with the configuration of the displacement absorbing member 10 and the separator 2 shown in FIG. 4, for example, the in-plane direction and thickness direction flowability is reduced, and the coolant pressure as a whole is reduced. Loss can be greatly reduced.

  In the fuel cell stack FS shown in FIGS. 6 (A) and 6 (B), in the previous embodiment, the displacement absorbing member 10 in which a large number of spring function portions 10B are arranged on one side of the substrate 10A is employed. A shape-shaped displacement absorbing member 20 is employed. Even in the displacement absorbing member 20, the contact portion with the separator 2 moves in the in-plane direction (waveform traveling direction) with deformation in the thickness direction. In FIG. 6B, only the wave shape of the displacement absorbing member 20 is shown.

  The fuel cell stack FS forms a coolant circulation space F between adjacent single cells C, and includes the displacement absorbing member 20 in the circulation space F. The separator 2 has a concave-convex shape in cross section. In the flow direction of the coolant (left and right in FIG. 1A). The displacement absorbing member 20 is arranged so that the moving direction of the contact portion is the continuous direction of the uneven shape of the separator 2, that is, the traveling direction of the waveform is the continuous direction of the uneven shape of the separator 2 as shown in FIG. It is in contact with the convex portions 2A of the upper and lower separators 2, respectively.

  Even in the fuel cell stack provided with the displacement absorbing member 20 described above, similarly to the previous embodiment, it has a structure in which the coolant flows between the stacked single cells C, and the displacement between the single cells C. Miniaturization can be realized while maintaining the absorption function well.

  The configuration of the fuel cell stack according to the present invention is not limited to the above-described embodiment, and details of the configuration can be changed as appropriate without departing from the gist of the present invention.

C single cell F distribution area FS fuel cell stack 1 membrane electrode assembly 2 separator 2A convex part 2B concave part 10 displacement absorbing member 10A substrate 10B spring function part 10C opening part 20 displacement absorbing member

Claims (11)

A fuel cell stack configured by laminating a plurality of single cells formed by sandwiching a membrane electrode assembly with a pair of separators,
Between the adjacent single cells, a cooling liquid flow space is formed, and a displacement absorbing member that is disposed in the flow space and absorbs the displacement between the single cells is provided.
The separator has an uneven cross-sectional shape continuously in the flow direction of the coolant,
The displacement absorbing member is a member whose contact portion with the separator moves in the in-plane direction with deformation in the thickness direction, and is arranged so that the moving direction of the contact portion is a continuous direction of the uneven shape of the separator. A fuel cell stack characterized by being in contact with a convex portion of the separator.   The fuel cell stack according to claim 1, wherein the convex portion of the separator has a flat upper surface. The displacement absorbing member has a structure in which a large number of spring function parts in contact with the other are arranged on one side of the substrate in contact with one of the opposing separators, and the spring function part has a base end to the substrate. A cantilever structure with a fixed end and a free end at the end,
The fuel cell stack according to claim 1 or 2, wherein the width of the free end of the spring function part is larger than the width of the convex part of the separator with which the spring function part contacts.   4. The fuel cell stack according to claim 3, wherein a width of a free end of the spring function part is larger than a width of a recess of a separator with which the spring function part contacts.   5. The fuel cell stack according to claim 3, wherein the free end of the spring function portion is in contact with a plurality of convex portions of the separator with which the spring function portion is in contact.   4. The substrate of the displacement absorbing member has an opening below each spring function portion, and the recess of the separator that contacts the substrate communicates with the opening. The fuel cell stack according to any one of 5.   The displacement absorbing member arranges the spring function parts on the substrate in the continuous direction of the uneven shape of the separator and the width direction intersecting the separator, and the spring function parts adjacent in the width direction are in the continuous direction of the uneven shape. The fuel cell stack according to any one of claims 3 to 6, wherein the fuel cell stack is offset.   8. At least one of the spring function portions of the displacement absorbing member is disposed with the free end facing downstream in the coolant flow direction. The fuel cell stack described in 1.   The flow direction of the coolant in the flow space and the flow direction of the gas in the gas flow path formed between the membrane electrode assembly and the separator are the same direction. The fuel cell stack according to item.   The fuel cell stack according to claim 9, wherein the gas is an anode gas.   The fuel cell stack according to any one of claims 1 to 10, wherein the separator has an inverted shape.

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