JP5301406B2 - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve discharge performance of generated water on a reaction gas passage side and to enable to circulate uniformly the reaction gas on the separator surface. <P>SOLUTION: A fuel gas passage 34 which is communicated between a fuel gas supply communication hole 24a and a fuel gas exhaust communication hole 24b is formed on a surface 18a going to an electrolyte membrane-electrode structure 16 of a first metal separator 18 constituting a fuel cell 10. The fuel gas passage 34 has a plurality of linear passages 34a and an entrance buffer portion 36a and an exit buffer portion 36b that are installed in the vicinity of the entrance and the vicinity of the exit of the linear passage 34a. The entrance buffer portion 36a is divided into three regions 40a, 40b and 40c which are mutually independent and of which passage cross-section is established to be equal by two continuing linear guide projections 38a, 38b with different length. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  In the present invention, an electrolyte / electrode structure having electrodes provided on both surfaces of an electrolyte and a corrugated metal separator are laminated, and a fuel gas or an oxidant gas is circulated on one surface of the metal separator. The present invention relates to a fuel cell in which a reaction gas channel is formed and a reaction gas communication hole through which the fuel gas or the oxidant gas flows is formed.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte membrane made of a polymer ion exchange membrane is provided by a pair of separators. The unit cell is sandwiched. This type of fuel cell is usually used as an in-vehicle fuel cell stack, for example, by stacking a predetermined number of unit cells.

  In the above fuel cell, a fuel gas flow channel for flowing fuel gas is provided in the plane of one separator so as to face the anode side electrode, and the cathode side electrode is opposed in the plane of the other separator. An oxidant gas flow path for flowing an oxidant gas is provided. Further, between the separators, a cooling medium flow path for flowing the cooling medium is provided along the surface direction of the separator.

  At that time, the separator is formed with a fuel gas communication hole through which fuel gas passes through in the stacking direction of the fuel cell, an oxidant gas communication hole through which oxidant gas flows, and a cooling medium communication hole through which a cooling medium flows. An internal manifold type fuel cell may be configured.

  For example, Patent Document 1 is known as this type of fuel cell. As shown in FIG. 6, the separator 1 disclosed in Patent Document 1 is provided with, for example, a fuel gas passage 2, and the fuel gas passage 2 has a main passage portion 3. The main flow path portion 3 communicates with the inlet manifold 6 a and the outlet manifold 6 b via the flow distribution portion 4 and the merge portion 5.

  The main flow path part 3 is divided | segmented by the some rib 7a, and the distribution part 4 and the confluence | merging part 5 are divided | segmented by the some rib 7b, 7c. Each of the ribs 7b and 7c is divided into a plurality of parts by divided parts 8a and 8b in the middle of the longitudinal direction. The divided portions 8a and 8b of the ribs 7b and 7c are arranged so as to be shifted in the longitudinal direction of the separator 1 from the divided portions 8a and 8b of the adjacent ribs 7b and 7c.

JP 2006-172924 A

  However, in the separator 1 described above, since the ribs 7b and 7c are divided into a plurality of parts by the divided parts 8a and 8b, the generated water tends to stay in the divided parts 8a and 8b. At that time, since the fuel gas and the oxidant gas bypass the generated water and flow between the ribs 7b and 7c, the generated water may not be discharged. Thereby, the flow of fuel gas and oxidant gas will be inhibited, and there exists a problem that electric power generation performance falls.

  In addition, when water is introduced from the outside of the fuel cell stack, the water stays and is not discharged, and power generation performance may be reduced.

  Further, since the ribs 7b and 7c are divided into a plurality of parts by the dividing parts 8a and 8b, the areas of the distribution part 4 and the joining part 5 that do not substantially contribute to power generation are increased. Therefore, there exists a problem that the separator 1 whole becomes large.

  The present invention solves this type of problem, and provides a fuel cell capable of improving the discharge of produced water on the reaction gas channel side and allowing the reaction gas to flow uniformly in the separator surface. With the goal.

  In the present invention, an electrolyte / electrode structure having electrodes provided on both surfaces of an electrolyte and a corrugated metal separator are laminated, and a fuel gas or an oxidant gas is circulated on one surface of the metal separator. The present invention relates to a fuel cell in which a reaction gas flow path is formed and a reaction gas communication hole through which the fuel gas or the oxidant gas flows is formed.

The metal separator is provided with a buffer portion constituted by a plurality of embosses between the end portion of the reaction gas flow path and the reaction gas communication hole, and the buffer portion is provided on two continuous short sides having different lengths. The linear guide member and the long-side linear guide member are divided into three regions which are independent from each other. When the virtual cross section is formed in a direction crossing the linear guide member on the short side and the linear guide member on the long side through an intermediate position in the direction in which the linear guide member on the short side extends, The cross-sectional areas of the three regions are set to be equal along the cross section.

  Further, it is preferable that the two linear guide members are continuously connected to the ends of the linear flow path convex portions constituting the reaction gas flow path.

  Further, the buffer portion has an inlet side buffer portion that communicates with a reaction gas supply communication hole that is a reaction gas communication hole, and an outlet side buffer portion that communicates with a reaction gas discharge communication hole that is the reaction gas communication hole, For each of the three regions, it is preferable that the average lengths of the reaction gas flow path lengths connecting the inlet side buffer portion, the reaction gas flow path, and the outlet side buffer portion are set to be equal to each other.

  According to the present invention, the buffer portion is divided into three regions that are independent from each other and have the same flow path cross-sectional area by two continuous linear guide members. For this reason, the generated water in which the reaction gas stays is bypassed and distributed, and the generated water can be easily and reliably discharged by the reaction gas. In addition, the reaction gas can be uniformly supplied into the separator surface, and the desired power generation performance can be maintained satisfactorily. Furthermore, the buffer portion can be effectively narrowed, and the entire fuel cell can be easily reduced in size.

1 is an exploded perspective view of a fuel cell according to an embodiment of the present invention. FIG. 2 is a sectional view of the fuel cell taken along line II-II in FIG. 1. It is a front view of the 1st metal separator which comprises the said fuel cell. It is principal part expansion explanatory drawing of a said 1st metal separator. It is a front view of the 2nd metal separator which comprises the said fuel cell. It is explanatory drawing of the separator currently disclosed by patent document 1. FIG.

  As shown in FIGS. 1 and 2, the fuel cell 10 according to the embodiment of the present invention includes an electrolyte membrane / electrode structure 16 having an anode-side first metal separator 18 and a cathode-side second metal separator 20. It is pinched. The fuel cell 10 is preferably used as a vehicle-mounted fuel cell.

  The first and second metal separators 18 and 20 have a concavo-convex shape by pressing a metal thin plate into a wave shape. The first and second metal separators 18 and 20 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a metal plate whose surface is subjected to anticorrosion treatment.

  An oxidant gas supply for supplying an oxidant gas, for example, an oxygen-containing gas, communicates with each other in the direction of the arrow A at the upper edge of the long side direction (the direction of arrow C in FIG. 1) of the fuel cell 10. A communication hole (reaction gas communication hole) 22a and a fuel gas supply communication hole (reaction gas communication hole) 24a for supplying a fuel gas, for example, a hydrogen-containing gas, are provided.

  The lower end edge of the long side direction of the fuel cell 10 communicates with each other in the direction of the arrow A, and a fuel gas discharge communication hole (reaction gas communication hole) 24b for discharging the fuel gas and an oxidant gas are discharged. An oxidant gas discharge communication hole (reaction gas communication hole) 22b is provided. The oxidant gas supply communication hole 22a and the oxidant gas discharge communication hole 22b are provided so as to correspond to point-symmetrical positions, and the fuel gas supply communication hole 24a and the fuel gas discharge communication hole 24b are similarly point symmetric. Are provided corresponding to the positions.

  At one edge of the fuel cell 10 in the short side direction (arrow B direction), there is provided a cooling medium supply communication hole 26a that communicates with each other in the arrow A direction and supplies a cooling medium. A cooling medium discharge communication hole 26b for discharging the cooling medium is provided at the other end edge.

  The electrolyte membrane / electrode structure 16 includes, for example, a solid polymer electrolyte membrane 28 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 30 and a cathode side electrode 32 that sandwich the solid polymer electrolyte membrane 28. With. The anode side electrode 30 has a smaller surface area than the cathode side electrode 32, but may have the same surface area.

  The anode-side electrode 30 and the cathode-side electrode 32 have a gas diffusion layer (not shown) made of carbon paper or the like, and porous carbon particles carrying a platinum alloy on the surface uniformly on the surface of the gas diffusion layer. And an electrode catalyst layer (not shown) formed by coating. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 28.

  A fuel gas flow path (reactive gas flow path) 34 that connects the fuel gas supply communication hole 24a and the fuel gas discharge communication hole 24b is formed on the surface 18a of the first metal separator 18 facing the electrolyte membrane / electrode structure 16. Is done.

  As shown in FIG. 3, the fuel gas channel 34 includes a plurality of linear channels (or wave-shaped channels) 34 a extending in the direction of arrow B along the power generation surface and arranged in the direction of arrow C. And an inlet buffer section (distribution section) 36a and an outlet buffer section (merging section) 36b provided in the vicinity of the inlet and the outlet of the linear flow path 34a. The linear flow path 34a is formed between the linear flow path protrusions (linear flow path protrusions) 34b protruding toward the surface 18a. The inlet buffer portion 36a and the outlet buffer portion 36b have a substantially triangular shape when viewed from the front.

  As shown in FIGS. 3 and 4, the inlet buffer 36 a includes two continuous linear guide protrusions (linear guide members) 38 a and 38 b having different lengths protruding toward the fuel gas flow path 34. . The linear guide protrusions 38a and 38b are continuously connected to the end of the linear flow path protrusion 34b at a predetermined position forming the linear flow path 34a, and the inlet buffer 36a is connected to the linear guide. The protrusions 38a and 38b are divided into three regions 40a, 40b, and 40c that are independent of each other.

  When a virtual cross section is formed in a direction intersecting (substantially orthogonal) to the linear guide projection 38a and the long-side linear guide projection 38b through an intermediate position of the short-side linear guide projection 38a, The cross-sectional areas of the three regions 40a to 40c are set equal along the virtual cross section (distance ha≈distance hb≈distance hc). The fuel gas flow path 34 is equally divided into three in the flow path width direction (arrow B direction) by the linear guide protrusions 38a and 38b (distance H1≈distance H2≈distance H3).

  As shown in FIG. 3, the outlet buffer portion 36b has two continuous linear guide protrusions (linear guide members) with different lengths protruding toward the fuel gas flow path 34, like the inlet buffer portion 36a. 44a and 44b. The linear guide protrusions 44a and 44b are continuously connected to the end of the linear flow path protrusion 34b at a predetermined position forming the linear flow path 34a, and the outlet buffer 36b is connected to the linear guide. The projections 44a and 44b are divided into three regions 46a, 46b, and 46c that are independent from each other and have the same channel cross-sectional area.

  In the inlet buffer part 36a, the fuel gas flow path 34 and the outlet buffer part 36b, the average length L1 of the length of the fuel gas flow path connecting the area 40a, the straight flow path 34a and the area 46a, the area 40b, the straight flow path. The average length L2 of the fuel gas flow path length connecting the 34a and the region 46b and the average length L3 of the fuel gas flow path length connecting the region 40c, the linear flow path 34a and the region 46c are set to be equal to each other. (Average length L1≈average length L2≈average length L3).

  The inlet buffer portion 36a communicates with the fuel gas supply communication hole 24a from the surface 18b side through the plurality of through holes 42a. The outlet buffer portion 36b communicates with the fuel gas discharge communication hole 24b from the surface 18b side through the plurality of through holes 42b.

  As shown in FIG. 5, on the surface 20a of the second metal separator 20 facing the electrolyte membrane / electrode structure 16, an oxidant gas flow communicating the oxidant gas supply communication hole 22a and the oxidant gas discharge communication hole 22b. A passage (reaction gas passage) 50 is formed.

  The oxidant gas channel 50 includes a plurality of linear channels 50a extending in the direction of arrow B along the power generation surface and arranged in the direction of arrow C, and the vicinity of the inlet and the outlet of the linear channel 50a. An inlet buffer portion 52a and an outlet buffer portion 52b. The linear flow path 50a is formed between the linear flow path protrusions (linear flow path protrusions) 50b that protrude toward the surface 20a. The inlet buffer portion 52a and the outlet buffer portion 52b have a substantially triangular shape when viewed from the front.

  The inlet buffer 52a includes two continuous short-side and long-side linear guide protrusions (linear guide members) 54a and 54b that protrude toward the oxidant gas flow path 50 and have different lengths. The linear guide projections 54a and 54b form a straight channel 50a and are continuously connected to the end of the linear channel projection 50b at a position where the oxidant gas channel 50 is equally divided into three in the width direction. Is done. The inlet buffer portion 52a is divided into three regions 56a, 56b, and 56c that are independent of each other and have the same channel cross-sectional area by linear guide protrusions 54a and 54b.

  Similarly to the inlet buffer portion 52a, the outlet buffer portion 52b has two continuous long side and short side linear guide protrusions (linear guide members) projecting toward the oxidant gas flow path 50 side. ) 58a and 58b. The linear guide protrusions 58a and 58b are continuously connected to the end of the linear flow path protrusion 50b at a predetermined position forming the linear flow path 50a, and the outlet buffer 52b is connected to the linear guide. The protrusions 58a and 58b are divided into three regions 60a, 60b, and 60c that are independent from each other and have the same channel cross-sectional area.

  In the inlet buffer part 52a, the oxidant gas flow path 50 and the outlet buffer part 52b, the average length L4 of the oxidant gas flow path length connecting the region 56a, the straight flow path 50a and the region 60a, the region 56b, the straight line shape. The average length L5 of the oxidant gas flow path length connecting the flow path 50a and the area 60b, and the average length L6 of the oxidant gas flow path length connecting the area 56c, the linear flow path 50a and the area 60c, They are set equal to each other (average length L4≈average length L5≈average length L6).

  The inlet buffer portion 52a communicates with the oxidant gas supply communication hole 22a from the surface 20b side through the plurality of through holes 62a. The outlet buffer portion 52b communicates with the oxidant gas discharge communication hole 22b from the surface 20b side through the plurality of through holes 62b.

  A cooling medium flow path 64 is formed between the surface 18b of the first metal separator 18 and the surface 20b of the second metal separator 20 to communicate the cooling medium supply communication hole 26a and the cooling medium discharge communication hole 26b ( (See FIG. 1).

  A first seal member 66 is integrally formed on the surfaces 18 a and 18 b of the first metal separator 18 around the outer peripheral edge of the first metal separator 18. A second seal member 68 is integrally formed on the surfaces 20 a and 20 b of the second metal separator 20 around the outer peripheral edge of the second metal separator 20.

  The operation of the fuel cell 10 configured as described above will be described below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 22a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas supply communication hole 24a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium supply communication hole 26a.

  For this reason, the oxidant gas is introduced from the oxidant gas supply communication hole 22a through the through hole 62a of the second metal separator 20 to the oxidant gas flow path 50 side. As shown in FIG. 5, this oxidant gas moves in the direction of arrow C (vertical direction) from the inlet buffer 52a along the straight flow path 50a, and reaches the cathode side electrode 32 of the electrolyte membrane / electrode structure 16. Supplied.

  On the other hand, the fuel gas is introduced into the fuel gas flow path 34 from the fuel gas supply communication hole 24 a through the through hole 42 a of the first metal separator 18. As shown in FIG. 3, this fuel gas moves in the vertical direction (arrow C direction) along the straight flow path 34a from the inlet buffer 36a, and is supplied to the anode side electrode 30 of the electrolyte membrane / electrode structure 16. Is done.

  Therefore, in the electrolyte membrane / electrode structure 16, the oxidant gas supplied to the cathode side electrode 32 and the fuel gas supplied to the anode side electrode 30 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 32 of the electrolyte membrane / electrode structure 16 passes through the through hole 62b from the outlet buffer 52b and passes through the oxidant gas discharge communication hole as shown in FIG. It is discharged to 22b. Similarly, as shown in FIG. 3, the fuel gas supplied to and consumed by the anode side electrode 30 of the electrolyte membrane / electrode structure 16 passes through the through hole 42b from the outlet buffer 36b and passes through the fuel gas discharge communication hole 24b. To be discharged.

  On the other hand, after the cooling medium supplied to the cooling medium supply communication hole 26 a is introduced into the cooling medium flow path 64 formed between the first metal separator 18 and the second metal separator 20 constituting the fuel cell 10. Circulates in the direction of arrow B (horizontal direction). The cooling medium is discharged to the cooling medium discharge communication hole 26b after the electrolyte membrane / electrode structure 16 is cooled.

  In this case, in the present embodiment, for example, as shown in FIGS. 3 and 4, in the fuel gas flow path 34, the inlet buffer 36 a is independent of each other by two continuous linear guide protrusions 38 a and 38 b. In addition, it is divided into three regions 40a, 40b and 40c having equal channel cross-sectional areas.

  For this reason, the fuel gas does not circulate around the water droplets, and the generated water can be easily and reliably discharged by the fuel gas. In addition, the fuel gas can be uniformly supplied from the three regions 40a, 40b, and 40c having the same channel cross-sectional area over the entire channel region (in the separator surface) of the fuel gas channel 34, and desired power generation performance is achieved. Can be maintained satisfactorily. In addition, the inlet buffer portion 36a can be effectively narrowed, and the fuel cell 10 as a whole can be easily downsized.

  On the other hand, as shown in FIG. 3, the outlet buffer 36b is divided into three regions 46a, 46b, and 46c that are independent from each other and have the same channel cross-sectional area by linear guide protrusions 44a and 44b. . Therefore, the fuel gas does not circulate around the generated water, and the generated water can be easily and reliably discharged by the fuel gas, and the fuel gas can be circulated uniformly. .

  Further, the fuel gas channel 34 is equally divided into three in the channel width direction (arrow B direction), and the average length L1 of the fuel gas flow path length connecting the region 40a, the linear channel 34a and the region 46a. The average length L2 of the fuel gas flow path connecting the region 40b, the linear flow path 34a and the region 46b, and the average length of the fuel gas flow path connecting the region 40c, the linear flow path 34a and the region 46c. The lengths L3 are set equal to each other.

  As a result, in the fuel gas flow path 34, the fuel gas is evenly distributed to the three regions 40a to 40c, so that the fuel gas is supplied smoothly and uniformly along the entire power generation surface, ensuring good power generation performance. There is an advantage that it becomes possible to obtain.

  Further, in the oxidant gas flow channel 50, although the detailed description is omitted, the same effect as the fuel gas flow channel 34 can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 16 ... Electrolyte and electrode structure 18, 20 ... Metal separator 22a ... Oxidant gas supply communication hole 22b ... Oxidant gas discharge communication hole 24a ... Fuel gas supply communication hole 24b ... Fuel gas discharge communication hole 26a ... Cooling Medium supply communication hole 26b ... Cooling medium discharge communication hole 28 ... Solid polymer electrolyte membrane 30 ... Anode side electrode 32 ... Cathode side electrode 34 ... Fuel gas flow path 34a, 50a ... Linear flow path 34b, 50b ... Linear flow path Projection 36a, 52a ... Inlet buffer 36b, 52b ... Exit buffer 38a, 38b, 44a, 44b, 54a, 54b, 58a, 58b ... Linear guide projection 40a, 40b, 40c, 46a, 46b, 46c, 56a , 56b, 56c, 60a, 60b, 60c... Region 50.

Claims (3)

A reaction gas flow path in which an electrolyte / electrode structure having electrodes provided on both surfaces of an electrolyte and a corrugated metal separator are laminated, and fuel gas or oxidant gas is circulated on one surface of the metal separator Is formed, and a reaction gas communication hole through which the fuel gas or the oxidant gas flows is formed through the stacking direction,
The metal separator is provided with a buffer portion constituted by a plurality of embosses between an end portion of the reaction gas flow path and the reaction gas communication hole,
The buffer portion is divided into three independent regions by two continuous short-side linear guide members and long-side linear guide members having different lengths,
When a virtual cross section is formed in a direction crossing the linear guide member on the short side and the linear guide member on the long side through an intermediate position in the direction in which the linear guide member on the short side extends, the virtual The fuel cell according to claim 1, wherein the cross-sectional areas of the three regions are set to be equal along the cross section.   2. The fuel cell according to claim 1, wherein the two linear guide members are continuously connected to end portions of the linear flow path convex portions constituting the reaction gas flow path. . 3. The fuel cell according to claim 1, wherein the buffer section includes an inlet-side buffer section communicating with a reaction gas supply communication hole that is the reaction gas communication hole;
An outlet side buffer portion communicating with the reaction gas discharge communication hole, which is the reaction gas communication hole;
Have
The fuel is characterized in that, for each of the three regions, the average lengths of the reaction gas flow paths connecting the inlet side buffer portion, the reaction gas flow path, and the outlet side buffer portion are set to be equal to each other. battery.

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