FUEL CELL STACK

Abstract

A fuel cell stack includes a plurality of stacked unit cells. Each unit cell includes a first separator, a second separator, and a power generation section centered between the first separator and the second separator. A flow passage and a gasket are disposed between the first separator of a first unit cell and the second separator of a second unit cell. The gasket surrounds a supply manifold, the flow passage, and a discharge manifold. The gasket includes an annular body and a guide projection. The first separator of the first unit cell has at least one first rib located adjacent to an inner peripheral side of the body. The second separator of the second unit cell has at least one second rib located adjacent to the inner peripheral side of the body.The first rib and the second rib protrude so that they touch each other and extend so that they overlap each other.

Description

BACKGROUND1. Area

[0001] The present disclosure relates to a fuel cell stack. 2. Description of the state of the art

[0002] A polymer electrolyte fuel cell comprises a fuel cell stack in which several unit cells are stacked one on top of the other. The unit cell includes a membrane electrode assembly (MEA) as a power generation section, a frame member surrounding the membrane electrode assembly, an anode separator, and a cathode separator. The MEA and the frame member are centered between the anode separator and the cathode separator.

[0003] One of the stacked fuel cells may be referred to as a first unit cell. Another of the stacked fuel cells, which has the cathode separator stacked on the anode separator of the first unit cell, may be referred to as a second unit cell. In this configuration, a flow passage is formed between the anode separator of the first unit cell and the cathode separator of the second unit cell to allow coolant to flow therethrough.

[0004] Japanese Patent Application Laid-Open No. 2009-252469 describes an example of a fuel cell separator having such a configuration. The fuel cell separator described in this publication includes a coolant inlet manifold configured to draw in a coolant, a flow passage through which the coolant flows, and a coolant outlet manifold configured to discharge the coolant from the flow passage. The coolant outlet manifold and the coolant inlet manifold are disposed on opposite sides of the flow passage. The flow passage is surrounded by an annular sealing member configured to seal the gap between the two adjacent separators. Furthermore, an end flow restricting piece protrudes from an inner peripheral surface of the sealing member toward an inner side of the sealing member.When the coolant flows from the coolant inlet manifold to the coolant outlet manifold, the end flow restrictor prevents the coolant from flowing through the flow passage near the sealing component. This prevents lateral flow. This improves the cooling efficiency of the power generation section.

[0005] The fuel cell stack needs further improvement in the efficiency of cooling the power generation section so that the power generation efficiency is further improved. SUMMARY

[0006] This Summary is intended to introduce, in a simplified form, a selection of concepts that are further described in the Detailed Description below. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0007] In one embodiment of the present disclosure, a fuel cell stack includes a plurality of unit cells stacked one upon another. Each of the unit cells includes a power generation section, a first separator, and a second separator. The power generation section is positioned between the first separator and the second separator.

[0008] The first separator has a surface located at the power generation section and having a first gas passage configured to supply a first reactant gas to the power generation section. The second separator has a surface located at the power generation section and having a second gas passage configured to supply a second reactant gas to the power generation section. One of the unit cells is referred to as a first unit cell. One of the unit cells having the second separator stacked on the first separator of the first unit cell is referred to as a second unit cell. A flow passage and a gasket are disposed between the first separator of the first unit cell and the second separator of the second unit cell.The flow passage is configured to allow a coolant to flow through for cooling the power generation section. The flow passage is disposed between a supply manifold configured to supply the coolant and a discharge manifold configured to discharge the coolant. The gasket surrounds the supply manifold, the flow passage, and the discharge manifold. The gasket includes an annular body and a guide projection projecting from an inner peripheral surface of the body toward the flow passage. The guide projection is configured to guide the flow of the coolant toward the inside of the body. The first separator of the first unit cell includes at least one first rib located adjacent to an inner peripheral side of the body.The second separator of the second unit cell has at least one second rib located adjacent to the inner peripheral side of the body. The first rib and the second rib project in such a way that they touch each other and extend in such a way that they intersect each other.

[0009] Further features and aspects will become apparent from the following detailed description, drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of two unit cells included in one embodiment of a fuel cell stack separated from each other. Fig. 2 is a perspective view of an anode separator, a frame member to which a power generation section is connected, and a cathode separator included in a unit cell and separated from each other. Fig. 3 is a plan view of the frame member to which the power generation section is connected. Fig. Figure 4 is a plan view of the anode separator with a gasket glued to it. Fig. 5 is a sectional view taken along line 5-5 in Fig. 2. Fig. 6 is an enlarged plan view of a Fig. 4 shown section.

[0010] In the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings are not necessarily to scale, and the relative size, dimensions, and representation of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0011] This description provides a comprehensive understanding of the methods, devices, and / or systems. Modifications and equivalents of the described methods, devices, and / or systems will be apparent to those skilled in the art. The sequences of operations are exemplary and may be changed, as will be apparent to those skilled in the art, except for operations that necessarily occur in a particular order. Descriptions of functions and structures well known to those skilled in the art may be omitted.

[0012] Exemplary embodiments may take various forms and are not limited to the described examples. However, the described examples are thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0013] In this description, “at least one of A and B” should be understood to mean “only A, only B, or both A and B”.

[0014] With reference to the Fig. 1 to 6, an embodiment of a fuel cell stack will now be described.

[0015] For illustrative purposes, some components are exaggerated or simplified in the drawings. Therefore, the dimensional proportions of the components may differ from the actual proportions.

[0016] As in Fig. 1, the fuel cell stack comprises a plurality of unit cells 11 stacked on top of one another. Fig. 1 shows two unit cells 11A and 11B, which are among the plurality of unit cells 11 constituting the fuel cell stack. Unit cell 11

[0017] As in Fig. As shown in Figure 2, the unit cell 11 includes a membrane-electrode gas diffusion layer assembly (hereinafter referred to as the power generation section 15), an electrically insulating frame member 20 surrounding the power generation section 15, an anode separator 30, and a cathode separator 40. The power generation section 15 and the frame member 20 are centered between the anode separator 30 and the cathode separator 40. The unit cell 11 of the present embodiment has an overall rectangular plate shape.

[0018] In the following description, the stacking direction of the plurality of unit cells 11 is referred to as the first direction X. The direction in which the short sides of the unit cell 11 extend and the direction in which the long sides of the unit cell 11 extend are referred to as the second direction Y and the third direction Z, respectively. The first direction X, the second direction Y, and the third direction Z form a Cartesian coordinate system.

[0019] The unit cell 11A (see Fig. 1) corresponds to one of the unit cells 11, and the unit cell 11B (see Fig. 1) corresponds to one of the unit cells 11 that has the cathode separator 40 stacked on the anode separator 30 of the unit cell 11A. The unit cell 11A is referred to as a first unit cell 11A. The unit cell 11B is referred to as a second unit cell 11B.

[0020] As in the Fig. 1 and Fig. 2, the unit cell 11 includes supply manifolds 111, 112, and 113 configured to respectively introduce coolant, fuel gas, and oxidant gas into the unit cell 11. The unit cell 11 also includes discharge manifolds 114, 115, and 116 configured to respectively discharge the coolant, fuel gas, and oxidant gas to the outside of the unit cell 11.

[0021] The supply manifolds 111, 112 and 113 and the discharge manifolds 114, 115 and 116 extend through the unit cell 11 in the first direction X.

[0022] The supply distributor 111 is in the second direction Y on one side (lower left side in the Fig. 1 and Fig. 2) of the unit cell 11.

[0023] The delivery manifold 114 is in the second direction Y on the other side (upper right side in the Fig. 1 and Fig. 2) of the unit cell 11.

[0024] The supply manifold 113 and the discharge manifold 115 are arranged in the third direction Z on one side (lower right side in the Fig. 1 and Fig. 2) of the unit cell 11. The supply manifold 113 and the discharge manifold 115 are separated from each other in the second direction Y.

[0025] The supply manifold 112 and the discharge manifold 116 are in the third direction Z on the other side (upper left side in the Fig. 1 and Fig. 2) of the unit cell 11. The supply manifold 112 and the discharge manifold 116 are separated from each other in the second direction Y. Power generation section 15

[0026] As in Fig. 2, the power generation section 15 includes a polymer electrolyte membrane (hereinafter referred to as electrolyte membrane), an anode electrode and a cathode electrode disposed on opposite surfaces of the electrolyte membrane, and gas diffusion layers disposed on two surfaces of the anode electrode and the cathode electrode.

[0027] The power generation section 15 of the present embodiment has the shape of a rectangle having two sides extending in the second direction Y and two sides extending in the third direction Z. In Fig. 2, the anode electrode is arranged on an upper surface of the electrolyte membrane, and the cathode electrode is arranged on a lower surface of the electrolyte membrane. Anode separator 30

[0028] As in Fig. 2, the anode separator 30 is opposite to the anode electrode of the power generation section 15.

[0029] The anode separator 30 has supply manifolds 311, 312 and 313 and discharge manifolds 314, 315 and 316, which form the supply manifolds 111, 112 and 113 and the discharge manifolds 114, 115 and 116, respectively.

[0030] The anode separator 30 has a surface adjacent to the power generation section 15, defining a gas surface 30b provided with a gas passage 39 configured to supply a fuel gas to the power generation section 15. The gas passage 39 is located between the supply manifold 312 and the discharge manifold 315 in the third direction Z. The gas passage 39 is defined by ribs that protrude toward the power generation section 15.

[0031] The anode separator 30 has a surface opposite to the power generation section 15, which defines a cooling surface 30a provided with cooling passage fins 38.

[0032] As in the Fig. 2 and Fig. As shown in Figure 4, the cooling passage fins 38 are substantially Z-shaped and extend from the supply manifold 312 toward the discharge manifold 315. Portions of the cooling passage fins 38 extending in the third direction Z are in the shape of curved waves. The cooling passage fins 38 are located between the supply manifold 311 and the discharge manifold 314 in the second direction Y.

[0033] The anode separator 30 of the present embodiment is formed by pressing a plate made of metal such as stainless steel. Cathode separator 40

[0034] As in Fig. 2, the cathode separator 40 is opposite to the cathode electrode of the power generation section 15.

[0035] In the present embodiment, the cathode separator 40 and the anode separator 30 have the same shape. The cathode separator 40 is arranged in such a position that the anode separator 30 is inverted with respect to an imaginary straight line L extending in the third direction Z through the center of the anode separator 30 in the second direction Y.

[0036] In the following description, some components of the cathode separator 40 may be referred to using reference numerals obtained by adding “10” to the reference numerals for the components in the anode separator 30, so that redundant description may be omitted.

[0037] The cathode separator 40 has supply manifolds 411, 412 and 413 and discharge manifolds 414, 415 and 416, which form the supply manifolds 111, 112 and 113 and the discharge manifolds 114, 115 and 116, respectively.

[0038] The cathode separator 40 has a surface adjacent to the power generation section 15, defining a gas surface 40b provided with a gas passage 49 configured to supply an oxidizing gas to the power generation section 15. The gas passage 49 is located between the supply manifold 413 and the discharge manifold 416 in the third direction Z. The gas passage 49 is defined by ribs that protrude toward the power generation section 15.

[0039] The cathode separator 40 has a surface opposite to the power generation section 15, which defines a cooling surface 40a provided with cooling passage fins 48.

[0040] The cooling passage fins 48 are substantially S-shaped and extend from the supply manifold 413 toward the discharge manifold 416. Portions of the cooling passage fins 48 extending in the third direction Z have the shape of curved waves. The cooling passage fins 48 are located between the supply manifold 411 and the discharge manifold 414 in the second direction Y.

[0041] The cathode separator 40 of the present embodiment is formed by pressing a plate made of metal such as stainless steel. Flow passage 19

[0042] As in Fig. 1, the cooling passage fins 38 of the anode separator 30 and the cooling passage fins 48 of the cathode separator 40, which are adjacent to each other in the first direction X, define a flow passage 19 through which the coolant flows. Seal 50

[0043] As in Fig. 1, a gasket 50 is disposed between the anode separator 30 of the first unit cell 11A and the cathode separator 40 of the second unit cell 11B to seal the gap between the anode separator 30 and the cathode separator 40.

[0044] As in the Fig. 2 and Fig. 4, the gasket 50 is mounted on the cooling surface 30a of the anode separator 30 and surrounds the supply manifold 111, the flow passage 19, and the discharge manifold 114. The gasket 50 is secured to the anode separator 30 by, for example, an adhesive.

[0045] The seal 50 includes an annular body 51 and guide projections 52. The guide projections 52 protrude from an inner peripheral surface of the body 51 toward the flow passage 19 and guide the flow of coolant toward the inside of the body 51. "Annular" shapes include any configuration that forms a loop, i.e., a continuous shape without ends. "Annular" shapes include, but are not limited to, a circular shape, an elliptical shape, and a polygonal shape with sharp or rounded corners.

[0046] The body 51 includes two first portions 51a extending in the second direction Y and separated from each other in the third direction Z, and two second portions 51b connecting two ends of one of the two first portions 51a to two ends of the other of the two first portions 51a. In the present embodiment, each of the second portions 51b includes a straight portion extending in the third direction Z and inclined portions continuous with two ends of the straight portion and inclined inward with respect to the second direction Y as the inclined portions extend outward in the third direction Z.

[0047] The guide projection 52 is arranged at a central position of the anode separator 30 in the second direction Y and protrudes from the first portion 51a in the third direction Z. In the present embodiment, the two first portions 51a each have a guide projection 52.

[0048] The guide projection 52 has a distal end that is in contact with the cooling passage fin 38. Frame component 20

[0049] As in the Fig. 2 and Fig. 3, an opening 20a extends in the first direction X through the center of the frame member 20. The opening 20a of the present embodiment has the shape of a rectangle with two sides extending in the second direction Y and two sides extending in the third direction Z.

[0050] From one side (top in Fig. 2) in the first direction X, peripheral edges of the power generating section 15 are connected to peripheral walls defining the opening 20a.

[0051] The frame member 20 has supply manifolds 211, 221 and 223 and discharge manifolds 224, 225 and 226, which form the supply manifolds 111, 112 and 113 and the discharge manifolds 114, 115 and 116, respectively.

[0052] A plurality of supply through-holes 22 and 23 and a plurality of discharge through-holes 25 and 26 extend through the frame component 20 in the first direction X. The supply through-holes 22 and 23 and the discharge through-holes 25 and 26 are each elongated in the third direction Z.

[0053] As in Fig. 5, the fuel gas flowing in the supply manifold 112 is supplied to the gas passage 39 through the supply manifold 312 and the supply through-hole 22.

[0054] Although not shown, exhaust gas of the fuel gas flowing through the gas passage 39 is discharged to the discharge manifold 115 through the discharge through-hole 25 and the discharge manifold 315.

[0055] The oxidizing gas flowing in the supply manifold 113 is supplied to the gas passage 49 through the supply manifold 413 and the supply through-hole 23.

[0056] Exhaust gas of the oxidizing gas flowing through the gas passage 49 is discharged to the discharge manifold 116 through the discharge through-hole 26 and the discharge manifold 416. Details Configuration Anode Separator 30 and Cathode Separator 40

[0057] As in Fig. 4, the anode separator 30 has first ribs 31, first auxiliary ribs 32, third ribs 33 and fourth ribs 34.

[0058] The first ribs 31, the first auxiliary ribs 32, the third ribs 33, and the fourth ribs 34 protrude in a direction opposite to the power generation section 15 and are arranged adjacent to the body 51 of the gasket 50. In the present embodiment, the first ribs 31, the first auxiliary ribs 32, the third ribs 33, and the fourth ribs 34 are arranged symmetrically in the plane direction of the anode separator 30 with respect to a center point C. Therefore, the following description focuses on the first ribs 31, the first auxiliary ribs 32, the third ribs 33, and the fourth ribs 34, which are shown in Fig. 4 are arranged on the right side of the power generation section 15.

[0059] In Fig. 4, on the right side of the power generation section 15 in the second direction Y on the side of the guide projection 52 toward the supply manifold 111, a first auxiliary rib 32, a fourth rib 34, and a first rib 31 are arranged in this order from the guide projection 52.

[0060] In addition, in the second direction Y on the side of the guide projection 52 toward the discharge manifold 114, a first auxiliary rib 32, three first ribs 31, and three third ribs 33 are arranged in this order from the guide projection 52.

[0061] As in Fig. 6, the first ribs 31 are inclined with respect to the second direction Y and the third direction Z, respectively, so that they extend in the second direction Y toward the discharge manifold 114 (top side in Fig. 6) when the first ribs 31 extend in the third direction Z towards the body 51.

[0062] The first auxiliary ribs 32 are each arranged between the first rib 31 and the guide projection 52 and extend in the third direction Z.

[0063] The guide projection 52 is clamped by the first auxiliary ribs 32 which are located on opposite sides of the guide projection 52 in the second direction Y.

[0064] In the second direction Y on the side of the guide projection 52 toward the discharge manifold 114, the first rib 31 located adjacent to the first auxiliary rib 32 has an inner end continuous with an inner end of the first auxiliary rib 32.

[0065] The third rib 33 has a similar shape to the first rib 31.

[0066] The fourth rib 34 extends in the third direction Z. The fourth rib 34 has an outer end that is connected to an outer end of the first rib 31.

[0067] As in Fig. 2, the cathode separator 40 has second ribs 41, second auxiliary ribs 42, fifth ribs 43 and sixth ribs 44.

[0068] As described above, the cathode separator 40 in the present embodiment has the same shape as the anode separator 30. Therefore, the first ribs 31, the first auxiliary ribs 32, the third ribs 33, and the fourth ribs 34 of the anode separator 30, which are reversed, correspond to the second ribs 41, the second auxiliary ribs 42, the fifth ribs 43, and the sixth ribs 44.

[0069] The first ribs 31 of the anode separator 30, which are in Fig. 6 are indicated by solid lines, and the second ribs 41 of the cathode separator 40, which are shown in Fig. 6, indicated by double-dashed lines, protrude in such a way that they touch each other. Furthermore, the first ribs 31 and the second ribs 41 extend in such a way that they overlap each other.

[0070] The first auxiliary ribs 32 of the anode separator 30, which are Fig. 6 are indicated by solid lines, and the second auxiliary ribs 42 of the cathode separator 40, which are Fig. 6 indicated by double-dashed lines, protrude in such a way that they touch each other.

[0071] In the present embodiment, the first direction X, the second direction Y, and the third direction Z correspond to a stacking direction, an arrangement direction, and a width direction, respectively, according to the present disclosure. The anode separator 30 and the cathode separator 40 correspond to a first separator and a second separator, respectively, according to the present disclosure. The gas passage 39 and the gas passage 49 correspond to a first gas passage and a second gas passage, respectively, according to the present disclosure. The fuel gas and the oxidizing gas correspond to a first reaction gas and a second reaction gas, respectively, according to the present disclosure. Functionality Example

[0072] If, as in Fig. 4, when the coolant flows from the supply manifold 111 in the vicinity of the body 51 of the gasket 50 into the gas passage 19, the guide projections 52 guide the flow of the coolant toward the inside of the body 51. This structure prevents the coolant from flowing through the vicinity of the body 51 of the gasket 50 in the flow passage 19 on the downstream side of the guide projections 52. Moreover, on the downstream side of the guide projections 52, the coolant easily flows through a portion of the flow passage 19 separated inward from the body 51, that is, a portion close to the power generation section 15, where the power generation section 15 is highly efficiently cooled. In addition, the first fins 31 and the second fins 41 arranged in the vicinity of the body 51 prevent the coolant from flowing through the vicinity of the body 51.With this structure, while preventing the coolant from flowing through the periphery of the body 51 of the gasket 50, the coolant easily flows through a portion separated inward from the body 51, that is, a portion close to the power generation section 15, where the power generation section 15 is highly efficiently cooled. Thus, the cooling efficiency of the power generation section 15 is improved.

[0073] Even if, as in Fig.As shown in FIG. 5, when the anode separator 30 of the first unit cell 11A and the cathode separator 40 of the second unit cell 11B are misaligned in a planar direction orthogonal to the first direction X, the first ribs 31 and the second ribs 41 extend to intersect each other. Therefore, the state in which the first ribs 31 are in contact with the second ribs 41 is likely to be maintained. This easily ensures the surface pressure between the anode separator 30 of the first unit cell 11A and the cathode separator 40 of the second unit cell 11B. With this structure, the fuel gas flows easily along the gas passage 39 toward the power generation section 15, and the oxidizing gas flows easily along the gas passage 49 toward the power generation section 15. Thus, the reaction gases are supplied to the power generation section 15 in a preferential manner. Advantages of the example

[0074] (1) The gasket 50 includes the annular body 51 and the guide projections 52. The guide projections 52 protrude from the inner peripheral surface of the body 51 toward the flow passage 19 and guide the flow of the coolant toward the inside of the body 51. The first fins 31 of the anode separator 30 of the first unit cell 11A and the second fins 41 of the cathode separator 40 of the second unit cell 11B extend so as to intersect each other.

[0075] This structure operates as described above, further improving power generation efficiency.

[0076] (2) The first ribs 31 and the second ribs 41 extend so as to be inclined with respect to the second direction Y and the third direction Z.

[0077] With this structure, the area of ​​a rectangle having vertices corresponding to the two ends of the first fin 31 and the two ends of the second fin 41 is smaller compared to a structure in which the first fin 31 extends in the second direction Y and the second fin 41 extends in the third direction Z. This enables a compact arrangement without shortening the first fin 31 and the second fin 41. Therefore, while avoiding a reduction in surface pressure caused by misalignment of the anode separator 30 of the first unit cell 11A with the cathode separator 40 of the second unit cell 11B, the first fin 31 and the second fin 41 will not adversely affect the flow of the coolant in the flow passage 19.

[0078] (3) The first ribs 31 and the second ribs 41 are located closer to the supply manifold 111 in the second direction Y than the guide projections 52.

[0079] With this structure, the first ribs 31 and the second ribs 41, which are arranged closer to the supply manifold 111 in the second direction Y than the guide projections 52, increase the pressure loss in the vicinity of the body 51 on the upstream side of the guide projections 52. Thus, the coolant in the flow passage 19 on the upstream side of the guide projections 52 is prevented from flowing through the vicinity of the body 51 of the seal 50. Accordingly, the coolant easily flows through a portion of the flow passage 19 separated inward from the body 51, that is, a portion close to the power generation section 15, where the cooling efficiency of the power generation section 15 is high. Thus, the cooling efficiency of the power generation section 15 is improved.

[0080] (4) The first ribs 31 and the second ribs 41 are arranged closer to the discharge manifold 114 in the second direction Y than the guide projections 52.

[0081] With this structure, the first ribs 31 and the second ribs 41, which are arranged closer to the discharge manifold 114 in the second direction Y than the guide projections 52, increase the pressure loss in the vicinity of the body 51 on the downstream side of the guide portions 52. Thus, the coolant is prevented from flowing through the vicinity of the body 51 of the seal 50 on the downstream side of the guide projections 52 in the flow passage 19. Accordingly, the coolant easily flows through a portion of the flow passage 19 separated inward from the body 51, that is, a portion close to the power generation portion 15, where the power generation portion 15 is highly efficiently cooled. Thus, the cooling efficiency of the power generation portion 15 is improved.

[0082] (5) The anode separator 3 and the cathode separator 40 have the same shape. The guide projections 52 are arranged at a central position of the anode separator 30 in the second direction Y and protrude in the third direction Z.

[0083] This design allows a reduction in the number of components in separators 30 and 40.

[0084] (6) The first auxiliary ribs 32 are each arranged between the first rib 31 and the guide portion 52 and extend in the third direction Z. The second auxiliary ribs 42 are each arranged between the second rib 41 and the guide projection 52 and extend in the third direction Z.

[0085] The first rib 31 and the second rib 41 extend to intersect each other. Such a structure imposes restrictions on the arrangement of the intersection between the first rib 31 and the second rib 41 in the vicinity of the guide portion 52 in the second direction Y. Therefore, when the first rib 31 and the second rib 41 are located on opposite sides of the guide portion 52, it is difficult to shorten the distance between the intersections on the opposite sides, that is, between the portions of the first rib 31 and the second rib 41 where the surface pressure is increased.

[0086] In this regard, in the structure of the present embodiment, the anode separator 30 and the cathode separator 40 each have the first auxiliary rib 32 and the second auxiliary rib 42. This makes it possible to increase the surface pressure at a position closer to the guide projection 52 than the above-described intersections. This easily ensures the surface pressure between the anode separator 30 of the first unit cell 11A and the cathode separator 40 of the second unit cell 11B. With this structure, the fuel gas easily flows toward the power generation section 15 along the gas passage 39, and the oxidizing gas easily flows toward the power generation section 15 along the gas passage 49. Thus, the reactant gases are preferably supplied to the power generation section 15. Thus, the power generation efficiency is further improved. Modified examples

[0087] The present embodiment may be modified as described below. The present embodiment and the following modified examples may be combined as long as the combined modified examples remain technically consistent with each other.

[0088] In the exemplary embodiment, the distal end of the guide portion 52 is in contact with the cooling passage fin 38. Alternatively, the distal end of the guide portion 52 may be spaced apart from the cooling passage fin 38 in the third direction Z by a gap. In this case, the width of the gap may be changed.

[0089] The distance from the body 51 of the seal 50 to each of the first rib 31, the first auxiliary rib 32, the third rib 33, and the fourth rib 34 can be changed. The same applies to the second rib 41, the second auxiliary rib 42, the fifth rib 43, and the sixth rib 44.

[0090] The width of the first auxiliary rib 32 in the second direction Y can be increased if the first auxiliary rib 32 extends inward. The same applies to the second auxiliary rib 42.

[0091] The first auxiliary rib 42 is not limited to extending in the third direction Z. For example, the first auxiliary rib 32 may be inclined toward the discharge manifold 114 if the first auxiliary rib 32 extends inward. The same applies to the second auxiliary rib 42.

[0092] In the exemplary embodiment, the guide projection 52 is clamped by the first auxiliary ribs 32, which are arranged on opposite sides of the guide projection 52 in the second direction Y. Alternatively, the first auxiliary ribs 32 may be spaced apart from the guide projection 52 in the second direction Y.

[0093] The first auxiliary rib 32 and the second auxiliary rib 42 may be omitted.

[0094] In the exemplary embodiment, the anode separator 30 and the cathode separator 40 have the same shape. However, the anode separator 30 and the cathode separator 40 may have different shapes.

[0095] In the exemplary embodiment, the first ribs 31 are arranged on opposite sides of the guide projection 52 in the second direction Y. Instead, the rib 31 in the second direction Y can be provided only on one side of the guide projection 52. The same applies to the second rib 41.

[0096] In the exemplary embodiment, the first rib 31 extends so as to be inclined with respect to the second direction Y and the third direction Z. However, there is no limitation to such a configuration. As long as the first rib 31 intersects with the second rib 41, the first rib 31 may extend in the second direction Y, and the second rib 41 may extend in the third direction Z, in one example.

[0097] In the exemplary embodiment, the first ribs 31 are arranged on opposite sides in the third direction Z. Alternatively, the first rib 31 can be arranged on only one side in the third direction Z. The same applies to the second rib 41.

[0098] Various changes in form and details may be made to the above examples without departing from the spirit and scope of the claims and their equivalents. The examples are for the purpose of description and not limitation. Descriptions of features in each example should be considered applicable to similar features or aspects in other examples. Suitable results may be obtained by performing operations in a different order and / or by combining components in a described system, architecture, device, or circuit differently and / or by substituting or supplementing other components or their equivalents for them. The scope of the disclosure is defined by the claims and their equivalents, not the detailed description. All changes within the scope of the claims and their equivalents are intended to be included in the disclosure. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2009 - 252469

[0004]

Claims

[1] Fuel cell stack comprising: a plurality of unit cells stacked on top of each other, each of the unit cells (11) having a power generation section (15), a first separator (30) and a second separator (40), and the power generation section (15) being taken into the middle of the first separator (30) and the second separator (40), wherein the first separator (30) has a surface located on the power generation section (15) and having a first gas passage (39) configured to supply a first reaction gas to the power generation section (15), the second separator (40) has a surface located on the power generation section (15) and having a second gas passage (49) configured to supply a second reaction gas to the power generation section (15), one of the unit cells (11) is referred to as a first unit cell (11A) and one of the unit cells (11) having the second separator (40) stacked on the first separator (30) of the first unit cell (11A) is referred to as a second unit cell (11B), a flow passage (19) and a seal (50) are arranged between the first separator (30) of the first unit cell (11A) and the second separator (40) of the second unit cell (11B), the flow passage (19) being configured to allow a coolant for cooling the power generation section (15) to flow therethrough, the flow passage (19) is arranged between a supply manifold (111) configured to supply the coolant and a discharge manifold (114) configured to discharge the coolant, the seal (50) surrounds the supply manifold (111), the flow passage (19) and the discharge manifold (114), the seal (50) has the following: an annular body (51) and a guide projection (52) projecting from an inner peripheral surface of the body (51) to the flow passage (19), the guide projection (52) being configured to guide the flow of the coolant toward the inside of the body (51), the first separator (30) of the first unit cell (11A) has at least one first rib (31) located adjacent to an inner peripheral side of the body (51), the second separator (40) of the second unit cell (11B) has at least one second rib (41) located adjacent to the inner peripheral side of the body (51), and the first rib (31) and the second rib (41) project so that they touch each other and extend so that they overlap each other. [2] Fuel cell stack according to claim 1, wherein a width direction refers to a direction orthogonal to a stacking direction of the unit cells (11) and an arrangement direction of the supply manifold (111) and the discharge manifold (114), and the first rib (31) and the second rib (41) each extend so as to be inclined with respect to the arrangement direction and the width direction. [3] Fuel cell stack according to claim 1 or 2, wherein the at least one rib (31) comprises a first rib (31) arranged closer to the supply manifold (111) than the guide projection (52) in an arrangement direction of the supply manifold (111) and the discharge manifold (114) that is orthogonal to a stacking direction of the unit cells (11), and the at least one second rib (41) comprises a second rib (41) which is arranged closer to the supply manifold (111) than the guide projection (52) in the arrangement direction. [4] Fuel cell stack according to claim 3, wherein the at least one first rib (31) comprises a first rib (31) which is arranged closer to the discharge manifold (114) in the arrangement direction than the guide projection (52), and the at least one second rib (41) comprises a second rib (41) which is arranged closer to the discharge manifold (114) than the guide projection (52) in the arrangement direction. [5] Fuel cell stack according to claim 4, wherein the first separator (30) and the second separator (40) have the same shape, a width direction refers to a direction orthogonal to the stacking direction and the arrangement direction, and the guide projection (52) is arranged at a central position of the first separator (30) in the arrangement direction and projects in the width direction. [6] Fuel cell stack according to claim 5, wherein the first separator (30) of the first unit cell (11A) and the second separator (40) of the second unit cell (11B) each have a first auxiliary rib (32) and a second auxiliary rib (42) which protrude so as to contact each other, the first auxiliary rib (32) is arranged between the first rib (31) and the guide projection (52) and extends in the width direction and the second auxiliary rib (42) is arranged between the second rib (41) and the guide projection (52) and extends in the width direction.

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