JP2012014940A - Separator for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator for a fuel cell that prevents an electrode structure from damaging and reduces costs.SOLUTION: A plurality of streak portions T each comprising ribs 36 and a web 37 are formed in a substrate 35 in parallel, and grooves 18 for gas flow passage are formed between the respective streak portions T. The grooves 18 for gas flow passage and an electrode structure 11 form gas flow passages 20. A pair of right and left ribs 36 of each streak portion T are inclined decreasing in interval from the substrate 35 to the web 37. Both the ribs 36 have thin portions 36a formed so as to elastically deform both the ribs 36 when the web 37 receives external force as shown by an arrow Q to be closer to the substrate 35.

Description

  The present invention relates to a fuel cell separator, and more particularly to a fuel cell separator that can prevent an electrode structure from being damaged, reduce electric resistance, and improve power generation efficiency.

As shown in FIG. 7, the solid polymer type fuel cell has positive electrode (cathode) and negative electrode (anode) separators 16 and 17 on both sides of a plate-like electrode structure 11 (MEA: Membrane / Electrode / Asembly). Are stacked to form a fuel cell stack. In the electrode structure 11, an electrolyte membrane 13 made of an ion exchange resin or the like is sandwiched between a pair of gas diffusion type positive electrode layers 14 and negative electrode layers 15 constituting a positive electrode (cathode) and a negative electrode (anode). It has a three-layer structure. The separators 16 and 17 are in contact with both electrode layers 14 and 15 of the electrode structure 11, and an oxidizing gas flow path 20 and a fuel gas flow path 27 for flowing gas between the electrode layers 14 and 15 are formed. ing. Then, for example, by flowing an oxidizing gas such as oxygen or air through the gas flow path 20 facing the positive electrode layer 14 and flowing hydrogen gas as a fuel through the gas flow path 27 facing the negative electrode layer 15, electrochemical Reaction occurs and electricity is generated. (See Patent Document 1)
A plurality of protrusions T each including a pair of ribs 36 and a web 37 are formed on the substrate 35 constituting the separators 16 and 17. The ribs 36 are bent so as to be inclined with respect to the substrate 35 by an inclination angle α. A gas channel groove 18 is formed between the protrusions T, and the gas channel 20 is formed by closing the opening 19 of the gas channel groove 18 with the positive electrode layer 14. Yes.

  The reason why the rib 36 is inclined with respect to the substrate 35 is that the contact area of the web 37 as a contact portion with respect to the positive electrode layer 14 is widened to conduct electricity properly, and the passage sectional area of the gas flow path 20 is also increased. This is to ensure appropriateness. In order to incline the ribs 36, a precision coining process is performed using a molding apparatus.

JP 2004-265856 A (see paragraphs 0009 and 0010 of FIG. 1 and FIG. 1)

  However, in the fuel cell using the separators 16 and 17 in which the ribs 36 are inclined as shown in FIG. In other words, in order to reduce the electrical resistance at the contact interface between the electrode layers 14 and 15 and the separators 16 and 17, the plurality of power generation cells 10 have a predetermined tightening between two end plates (not shown) in a stacked state. The contact surfaces of the separators 16 and 17 and the electrode layers 14 and 15 are pressed against each other by being pressed against each other by the applied force. When the fuel cell is generating power, water is generated by an electrochemical reaction between hydrogen and oxygen on the cathode side of the electrode structure 11, and most of the generated water is oxidized (oxygen) flowing through the gas flow path 20. It is discharged outside by the gas flow. The remaining generated water penetrates into the electrode structure 11 and enters the gas flow path 27 as permeated water. For this reason, the electrode structure 11 is expanded by the permeated water, and a pressing force in the directions of arrows P and Q acts on the separators 16 and 17. However, the separators 16 and 17 are formed of, for example, a stainless steel plate having high rigidity, and the rib 36 has a large inclination angle α, so that it is not elastically deformed in the directions of the arrows P and Q. Therefore, the electrode structure 11 receives a compression reaction force in the directions of the anti-P and Q arrows, and the electrode structure 11 may be excessively compressed and damaged.

  In addition, for example, when the fuel cell is operated at a low load, the amount of generated water is reduced, so that the amount of generated water that permeates the electrode structure 11 is also reduced, and the high-temperature heat generated during power generation is reduced. As a result, the electrode structure 11 becomes dry. Then, the positive electrode layer 14 and the negative electrode layer 15 of the electrode structure 11 shrink due to drying and the thickness decreases, but the separators 16 and 17 are not deformed, so the contact surface between the electrode structure 11 and the separators 16 and 17 There was a problem that the pressure became weak, the electrical resistance between both members increased, and the power generation efficiency was lowered.

  The present invention eliminates the problems in the prior art described above, prevents damage to the electrode structure, facilitates production, and improves the power generation efficiency, and its separator It is to provide a manufacturing method.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a plurality of protrusions formed of ribs and webs are formed in parallel on a substrate, and a gas channel groove is formed between the protrusions. In the fuel cell separator, the left and right pair of ribs of the protrusion are inclined so that the distance increases from the substrate to the web, and the web approaches the substrate with respect to the rib. The gist is that an elastic deformation allowing portion for elastically deforming both the ribs when receiving an external force is provided.

The gist of the invention according to claim 2 is that, in claim 1, the elastic deformation allowing portion is a thin portion formed on the both ribs.
The invention according to claim 3 is summarized in that, in claim 1, the elastic deformation allowing portion is a meandering portion formed in both ribs.

  According to a fourth aspect of the present invention, in the first aspect, the elastic deformation allowing portion is a thin portion that is partially formed on the ribs, and the thick portion other than the thin portion is an inner side of the ridge. The gist of the present invention is that it is formed so as to protrude toward the cooling water groove.

(Function)
In the invention according to any one of claims 1 to 4, since the elastic deformation allowing portion is provided on the pair of ribs of the protruding portion, the generated water is generated in the electrode structure during power generation of the fuel cell. Even if the electrode structure expands and the web is pressed in the direction approaching the substrate, the rib is elastically deformed by the elastic deformation allowing portion. For this reason, expansion of the electrode structure is allowed, internal stress generated in the electrode structure is reduced, and damage to the electrode structure is prevented.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to prevent damage to an electrode structure, electric power generation efficiency can be improved.

The fragmentary sectional view of the fuel cell using the separator of this invention. The disassembled perspective view which shows the component of the electric power generation cell of a fuel cell. Sectional drawing which passes along the center of the protrusion part of a separator. (A) is a fragmentary sectional view of the flat plate material which has a meandering part used for manufacture of another separator of this invention, (b) is a fragmentary sectional view of the shape | molded separator. The fragmentary sectional view of the separator of another embodiment of this invention. The fragmentary sectional view of the separator of another embodiment of this invention. The fragmentary sectional view of the electrode structure and separator of the conventional fuel cell.

Hereinafter, an embodiment of a fuel cell separator embodying the present invention will be described with reference to FIGS.
First, a fuel cell using the separator of this embodiment will be described with reference to FIG.

  An electrode structure 11 constituting the power generation cell 10 of the fuel cell includes a square annular frame 12, a solid polymer electrolyte membrane 13 accommodated inside the frame 12, and a solid polymer electrolyte membrane 13. It is comprised by the positive electrode layer 14 and the negative electrode layer 15 as a gas diffusion electrode laminated | stacked on the surface. A positive separator 16 is brought into contact with the surfaces of the frame 12 and the positive electrode layer 14, and a negative separator 17 is brought into contact with the surfaces of the frame 12 and the negative electrode layer 15. A large number of the power generation cells 10 are stacked to constitute a fuel cell stack.

  On the surface of the positive electrode separator 16 in contact with the positive electrode layer 14, an oxidizing gas channel groove 18 is formed in the vertical direction and parallel to each other. The opening 19 of the oxidizing gas channel groove 18 is closed by the positive electrode layer 14 to form an oxidizing gas channel 20. An oxygen gas supply hole 21 is formed in the upper part of the separator 16, and oxygen gas is distributed and supplied from the oxygen gas supply hole 21 to the oxidant gas flow paths 20 through the common gas flow path 22. An oxygen gas discharge hole 23 is formed in the lower part of the separator 16, and oxygen off-gas supplied for power generation from each oxidizing gas flow path 20 is discharged from the oxygen gas discharge hole 23 through the common gas flow path 24. Yes.

  On the surface of the negative electrode separator 17 in contact with the negative electrode layer 15, fuel gas channel grooves 25 are formed in the vertical direction and parallel to each other. A fuel gas channel 27 is formed by closing the opening 26 of the gas channel groove 25 by the negative electrode layer 15. A fuel gas supply hole 28 is formed in the upper portion of the separator 17, and fuel gas passes from the fuel gas supply hole 28 to each fuel gas flow path 27 through a gas flow path (not shown, but see the common gas flow path 22). It is designed to be distributed. A fuel gas discharge hole 29 is formed in the lower part of the separator 17, and the fuel off-gas supplied to the power generation from each fuel gas passage 27 passes through a common gas passage (not shown, but see the common gas passage 24). The gas is discharged from the discharge hole 29. The frame 12 is formed with a passage 12a that communicates the oxygen gas supply hole 21 and the fuel gas supply hole 28, and a passage 12b that communicates the oxygen gas discharge hole 23 and the fuel gas discharge hole 29. Yes.

  Next, the configuration of the separator 16 will be described. Since one separator 17 is configured in the same manner as the other separator 16, description of the configuration is omitted. In this embodiment, in FIG. 1, both sides of the gas flow channel groove 18 (oxidation gas flow channel 20) of the separator 16 are left and right, the positive electrode layer 14 side is the upper side, and the side away from the positive electrode layer 14 is the lower side. To do.

  As shown in FIG. 1, ribs 36 are integrally formed on both left and right edges of the substrate 35 of the separator 16 and are inclined so that the distance between the upper ends (on the positive electrode layer 14 side) increases. A flat plate web 37 that is in contact with the positive electrode layer 14 is integrally formed between the tip portions of 36. A plurality of protrusions T are formed on the substrate 35 in parallel with each other by the ribs 36 and the web 37. The gas channel groove 18 is formed between the protrusions T, and the gas channel groove 18 is oxidized by closing the opening 19 of the gas channel groove 18 with the positive electrode layer 14. It is formed in the gas flow path 20.

  The inclination angle α of the rib 36 with respect to the substrate 35 is set in a range of 50 ° to 80 °, for example, and in this embodiment is set to 70 °. The boundary portion 38 between the substrate 35 and the rib 36 is formed in an arc shape that swells outside the gas flow channel groove 18. A boundary portion 39 between the rib 36 and the web 37 is formed in an arc shape that swells outward in the width direction of the web 37. The groove formed on the inner side of the protrusion T is used as a cooling water groove 40 for flowing cooling water during power generation of the fuel cell.

  The plate thickness t1 of the thin portion 36a of the rib 36 is set to be thinner than the plate thickness t2 and t3 dimensions of the boundary portions 38 and 39, and the entire rib 36 is a thin portion 36a as an elastic deformation allowing portion. .

  As shown in FIG. 2, the protrusions T formed on the separators 16 and 17 are simplified in illustration. As shown in FIG. 3, the ribs 36 of the ridge T and the openings of both ends of the web 37 are closed by thin plate-like closing ribs 361 that can be elastically deformed, and the common gas flow paths 22 and 24 and the cooling water groove 40. In FIG. 3, the separator 16 is configured to circulate and supply cooling water to the cooling water groove 40, but this is not shown.

According to the fuel cell separator of the above embodiment, the following effects can be obtained.
(1) In the above embodiment, as shown in FIG. 1, the thin portion 36 a that allows elastic deformation is formed in the rib 36 of the separator 16. For this reason, there is a problem even when the electrode structure 11 expands when the electrode structure 11 is impregnated with the generated water generated in the oxidizing gas flow path 20 of the cathode when hydrogen and oxygen react during power generation of the fuel cell. Does not occur. That is, when a pressing force is applied to the web 37 of the separator 16 in the direction of the arrow Q compressing the ridge T, the thin portion 36a is elastically deformed and the web 37 is displaced downward, so that the positive electrode layer 14 It is possible to prevent the contact pressure of the contact surface between the web 37 and the web 37 from increasing. As a result, internal stress generated by the pressing force inside the electrode structure 11 can be reduced, and damage to the electrode structure 11 can be prevented.

  (2) In the above embodiment, since the rib 36 is elastically deformed by the thin portion 36a, the amount of generated water is reduced and the electrode structure 11 is in a dry state in a low load power generation state of the fuel cell. When the electrode structure 11 contracts, the thin portion 36a of the rib 36 is elastically deformed and the web 37 is appropriately pressed against the positive electrode layer 14. For this reason, the contact surface pressure between the positive electrode layer 14 and the web 37 can be properly maintained, and an increase in electric resistance can be prevented, thereby improving power generation efficiency.

  (3) In the above embodiment, as shown in FIG. 3, since the blocking ribs 361 at both ends of the ridge T are thinned, the elastic deformation at both ends of the ridge T is allowed, and the electrode structure 11 expansion or contraction can be appropriately handled.

In addition, you may change the said embodiment as follows.
As shown in FIG. 4A, the meandering portion 36b is formed on the workpiece 47 by using a forming apparatus (not shown). Thereafter, the workpiece 47 is formed using a forming apparatus, and the separator 16 is formed as shown in FIG. This embodiment also has the same effect as the above-described embodiment.

  -As shown in FIG. 5, the thin part 36a is partially formed in the boundary part 39 side of the both ribs 36, and the thick part 36c other than the thin part 36a is formed on the inner side of the protrusion T. You may form so that it may protrude to the groove | channel 40 for water. In this case, the thin portion 36a and the thick portion 36c can be formed without reducing the passage area of the oxidizing gas passage 20.

  As shown in FIG. 6, the thickness of the web 37 may be larger than the thickness of the substrate 35 and the ribs 36.

  T ... ridge part, 18, 25 ... groove for gas flow path, 35 ... substrate, 36 ... rib, 36a ... thin part, 36b ... meandering part, 36c ... thick part, 37 ... web, 40 ... for cooling water groove.

Claims (4)

In a fuel cell separator in which a plurality of ridges composed of ribs and webs are formed in parallel on a substrate, and gas channel grooves are formed between the ridges,
When the pair of left and right ribs of the ridge is inclined so that the interval increases from the substrate to the web, and the rib receives an external force in the direction in which the web approaches the substrate, A fuel cell separator comprising an elastic deformation allowing portion for elastically deforming both ribs. 2. The fuel cell separator according to claim 1, wherein the elastic deformation allowing portion is a thin portion formed on the both ribs. 2. The fuel cell separator according to claim 1, wherein the elastic deformation allowing portion is a meandering portion formed on both ribs. 2. The elastic deformation allowing portion according to claim 1, wherein the elastic deformation allowing portion is a thin portion partially formed on the both ribs, and the thick portion other than the thin portion is formed on the cooling water groove side formed inside the protrusion. A separator for a fuel cell, wherein the separator is formed so as to protrude.

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