JP2008108485A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of balancing application of optimum pressing force to a plurality of stacked cells with restraint on manufacturing cost. <P>SOLUTION: This fuel cell is provided with a pressing part arranged at an end of a stack in a cell stacking direction, and a pair of support members sandwiching the stack and the pressing part therebetween. The pressing part includes: a first member having a first part pressing a reaction part of the plurality of stacked cells, and a second part pressing a manifold part, and pressed against an end of the stack in the cell stacking direction; a plurality of elastic members; and a second member arranged oppositely to the first member. The plurality of elastic members are sandwiched between the first part and the second part, and the second member. When the stack and the pressing part are sandwiched between the pair of support members, the plurality of elastic members are compressed, and held to set the compressed length of the elastic members arranged in the second part larger than that of the elastic members arranged in the first part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell including a stack in which a plurality of cells are stacked.

  A fuel cell is formed by stacking a plurality of single cells including a reaction part where an electrochemical reaction occurs and a manifold part serving as an inlet / outlet of gas or cooling water, and the stacked body is pressed by end plates disposed at both ends of the single cell in the stacking direction. The structure of being attached is common. By pressing both ends of the single cell stack with the end plates, the single cells are pressed against each other to prevent gas leakage and to ensure the sealing performance of the fuel cell.

  In order to improve the sealing performance of the fuel cell, it is preferable to increase the pressing force of the end plate. However, if the pressing force is set high, the reaction part of the single cell may be crushed by the pressing force. Therefore, the end plate that is pressed against one end of the cell stack is divided into an inner part that presses the reaction part of a plurality of stacked single cells and an outer part that presses the manifold part. A technique is known in which springs having different elastic coefficients are arranged on the inner side and the outer side, and the springs are held between the inner and outer sides and the spring retainer. (For example, refer to Patent Document 1).

JP 2004-335336 A

  In order to prevent the reaction part of the cell from being crushed by the pressing force while ensuring the sealing performance of the fuel cell, the manufacturing cost is increased, such as dividing the end plate or requiring a plurality of different types of springs. There was a problem that it would be expensive.

  The present invention is a fuel cell including a stack in which a plurality of cells including a reaction part where an electrochemical reaction occurs and a manifold part serving as an inlet / outlet of a gas or a coolant are stacked, and is disposed at an end of the stack in the cell stacking direction. A pressing portion, and a pair of support members that sandwich the stack and the pressing portion, and the pressing portion presses the first portion that presses the reaction portion of the stacked cells and the manifold portion. A first member that is pressed against an end of the stack in the cell stacking direction, a plurality of elastic members, and a second member that is disposed to face the first member. The plurality of elastic members are sandwiched between at least the first part and the second part and the second member, and the distance between the first member and the second member in the second part is the first part Smaller than the distance between the first member and the second member in the portion When the stack and the pressing portion are sandwiched between the pair of support members, the plurality of elastic members are compressed, and the elastic member provided in the second portion has a compression length provided in the first portion. The member is held so as to be larger than the compressed length of the member.

  According to such a configuration, it is not necessary to divide the end plate in order to prevent the reaction part of the cell from being crushed by the pressing force while ensuring the sealing performance of the fuel cell, and thus the manufacturing cost of the fuel cell can be reduced. Can be planned.

  In the fuel cell according to the present invention, it is preferable that the thickness of the first member in the cell stacking direction in the second part is larger than the thickness of the first part in the cell stacking direction.

  In the fuel cell according to the present invention, the second member has a third portion that faces the first portion and a fourth portion that faces the second portion, and the fourth portion of the second member. It is preferable that the thickness in the cell stacking direction is larger than the thickness in the cell stacking direction in the third portion.

  In the fuel cell according to the present invention, it is preferable that the plurality of elastic members are all the same.

  According to such a configuration, since a plurality of different types of springs are not required, the manufacturing cost of the fuel cell can be further reduced.

  ADVANTAGE OF THE INVENTION According to this invention, coexistence with giving the optimal pressing force to the reaction part and manifold part of several laminated | stacked cells, and suppressing the manufacturing cost of a fuel cell can be aimed at.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a side view of a fuel cell 10 showing an embodiment of the present invention. The fuel cell 10 includes a fuel cell stack 3, a spring box 12, and a pair of end plates 14. The spring box 12 is disposed at one end of the fuel cell stack 3, and the spring box 12 and the fuel cell stack 3 are sandwiched by a pair of end plates 14. The fastening rod 16 passes through the pair of end plates 14, and both ends thereof are fixed by fixing nuts 18. A plurality of adjustment bolts 20 pass through one end plate 14, and the tip ends of the adjustment bolts 20 are pressed against the spring box 12. The adjustment bolt 20 can appropriately change the force with which the spring box 12 is pressed.

  The fuel cell stack 3 is configured by stacking a plurality of single cells 1. In the present embodiment, the stacked body in which a plurality of single cells 1 are stacked is used as the fuel cell stack 3, but the fuel cell stack 3 is a current collecting member for collecting the power generated by each single cell 1, Of course, the structure may include an insulating member, and the present invention is not limited to this, and various modifications are possible. FIG. 2 is a schematic configuration diagram showing the configuration of the single cell 1 according to the present embodiment. Hereinafter, a description will be given with reference to FIG. Each unit cell 1 includes a membrane electrode assembly 26 formed by attaching a pair of an anode electrode 22 and a cathode electrode 24 to both sides of an electrolyte membrane (for example, a polymer membrane), a first separator 28, and a second It is configured to be sandwiched between the separators 30.

Each single cell 1 generates power by receiving supply of hydrogen gas as a fuel and air as an oxidant. Hydrogen gas, which is a fuel gas, is supplied to the hydrogen gas inlet manifold 32 provided at the outer edge surrounding the portion of the second separator 30 in contact with the anode electrode 22 through the hydrogen gas inlet passage 40. The hydrogen gas inlet manifold 32 flows into the anode electrode 22 through a hydrogen gas supply passage (not shown) provided in the second separator 30. In the anode electrode 22, an electrochemical reaction as shown in the following formula (1) occurs.
H ₂ → 2H ⁺ + 2e ⁻ (1)
The hydrogen gas that has not been used in the electrochemical reaction gathers in the hydrogen gas outlet manifold 34 provided at the outer edge of the second separator 30 that surrounds the portion in contact with the anode electrode 22, and the hydrogen gas outlet flow It is discharged through the path 42. Protons (H ⁺ ) generated by the chemical reaction move to the cathode electrode 24 through the electrolyte membrane, and electrons (e ⁻ ) move to the cathode electrode 24 through an external electric circuit (not shown).

Air that is an oxidant is supplied to an air inlet manifold 36 provided on the outer edge of the first separator 28 that surrounds the portion in contact with the cathode electrode 24 through the air inlet channel 44. The air flows from the inlet manifold 36 to the cathode electrode 24 through the air supply passage 48 provided in the first separator. In the cathode electrode 24, an electrochemical reaction as shown in the following formula (2) occurs.
2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O (2)
The air that has not been used for the electrochemical reaction gathers in an air outlet manifold (not shown) provided on the outer edge of the first separator 28 that surrounds the portion in contact with the cathode electrode 24, It is discharged through 46.

  The cooling water for cooling the membrane electrode assembly 26 that has generated heat due to the electrochemical reaction passes through the cooling water inlet passage 54 and surrounds the periphery of the portion of the second separator 30 that contacts the anode electrode 22. The membrane electrode assembly 26 is cooled through the cooling water supply passage 58 provided in the second separator 30 from the cooling water inlet manifold 50. Then, the cooling water gathers at the cooling water outlet manifold 52 provided at the outer edge portion surrounding the periphery of the portion of the second separator 30 that contacts the anode electrode 22, and is discharged through the cooling water outlet channel 56.

  Returning again to FIG. The spring box 12 includes a lower plate 5 pressed against the end of the stack 3 in the unit cell stacking direction, a plurality of springs 7, and an upper plate 9 disposed to face the lower plate. Here, the lower plate 5 is a separator provided with a first portion B that presses a reaction portion where an electrochemical reaction of a plurality of stacked single cells 1 occurs, and a manifold portion that is an inlet / outlet of gas or cooling water. A second portion A that presses the outer edge portion. The lower plate 5 is a member having a thickness that can be bent by receiving an elastic force due to compression of the spring 7. Further, as shown in FIG. 3, the thickness of the second portion A of the lower plate 5 in the single cell stacking direction is larger than the thickness of the first portion B in the single cell stacking direction.

  In the first portion B, a plurality of springs 7 having substantially the same shape, size, spring coefficient and the like are arranged. In the second part A, a plurality of springs 7 identical to the springs 7 arranged in the first part B are arranged along the outer edge of the lower plate 5. These springs 7 are sandwiched between the lower plate 5 and the upper plate 9. Since the thickness in the single cell stacking direction in the second portion A of the lower plate 5 is larger than the thickness in the single cell stacking direction in the first portion B, the lower plate 5 and the upper plate 9 in the second portion A Is smaller than the distance between the lower plate 5 and the upper plate 9 in the first portion B.

  When the spring box 12 and the fuel cell stack 3 are sandwiched between the pair of end plates 14, the plurality of springs 7 sandwiched between the upper plate 9 and the lower plate 5 are compressed, and elasticity generated by the compression of the springs 7. The force is a force that presses the fuel cell stack 3 in the stacking direction of the single cells 1. As described above, the interval between the lower plate 5 and the upper plate 9 in the second portion A is smaller than the interval between the lower plate 5 and the upper plate 9 in the first portion B. The length in which the spring 7 disposed in the portion A contracts in the cell stacking direction is larger than the length in which the spring 7 disposed in the first portion B contracts in the cell stacking direction.

  At this time, the elastic force generated by the compression of the spring 7 disposed in the second portion A is larger than the elastic force generated by the compression of the spring 7 disposed in the first portion B, and the lower plate 5 is bent, The second part A is displaced below the first part B. And the force by which the outer edge part of the separator of the laminated | stacked several single cell 1 is pressed becomes larger than the force by which the reaction part is pressed.

  The force with which the spring box 12 presses the gas / cooling water inlet / outlet manifolds of the plurality of stacked single cells 1 is greater than the force of pressing the reaction part where the electrochemical reaction of the stacked single cells 1 occurs. By enlarging it, gas leakage is prevented and the sealing property of the fuel cell 10 is secured, and the pressing force applied to the reaction part becomes excessive, and the electrode and the electrolyte membrane provided in the reaction part are pushed. It can prevent being crushed. And according to this embodiment, since it is not necessary to divide | segment an end plate etc. and a different kind of spring is not required, the manufacturing cost of the fuel cell 10 does not become expensive.

  In the present embodiment, the thickness of the second portion A of the lower plate 5 of the spring box 12 in the cell stacking direction is larger than the thickness of the first portion B in the cell stacking direction. The thickness in the cell stacking direction of 5 is set to be uniform, and the thickness in the cell stacking direction of the fourth portion of the upper plate 9 facing the second portion A of the lower plate 5 is set to the first thickness of the lower plate 5. The thickness may be larger than the thickness of the third portion of the upper plate 9 facing the portion B in the cell stacking direction. Further, the thickness in the cell stacking direction of the second portion A of the lower plate 5 is made larger than the thickness of the first portion B in the cell stacking direction, and the thickness of the fourth portion of the upper plate 9 in the cell stacking direction. The thickness may be larger than the thickness of the third portion of the upper plate 9 in the cell stacking direction, and the present invention is not limited to this, and various changes can be made.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, Of course, in the range which does not change the summary of this invention, it can implement with a various form. It is.

1 is a side view of a fuel cell according to an embodiment of the present invention. It is a block diagram of the single cell which concerns on embodiment of this invention. It is a perspective view of the lower plate concerning the embodiment of the present invention.

Explanation of symbols

  1 single cell, 3 fuel cell stack, 5 lower plate, 7 spring, 9 upper plate, 10 fuel cell, 12 spring box, 14 end plate, 16 fastening rod, 18 fixing nut, 20 adjustment bolt, 22 anode electrode, 24 cathode Electrode, 26 Membrane electrode assembly, 28 First separator, 30 Second separator, 32 Hydrogen gas inlet manifold, 34 Hydrogen gas outlet manifold, 36 Air inlet manifold, 40 Hydrogen gas inlet channel, 42 Hydrogen gas outlet channel, 44 Air inlet passage, 46 Air outlet passage, 48 Air supply passage, 50 Cooling water inlet manifold, 52 Cooling water outlet manifold, 54 Cooling water inlet passage, 56 Cooling water outlet passage, 58 Cooling water supply passage.

Claims (4)

A fuel cell comprising a stack in which a plurality of cells including a reaction part where an electrochemical reaction occurs and a manifold part serving as an inlet / outlet of a gas or a coolant are stacked,
A pressing portion disposed at an end of the stack in the cell stacking direction;
A pair of support members sandwiching the stack and the pressing portion,
The pressing portion includes a first portion that presses a reaction portion of a plurality of stacked cells and a second portion that presses a manifold portion, and is pressed against an end portion of the stack in the cell stacking direction. One member;
A plurality of elastic members;
A second member disposed opposite to the first member,
The plurality of elastic members are sandwiched between at least the first part and the second part, and the second member,
An interval between the first member and the second member in the second portion is smaller than an interval between the first member and the second member in the first portion,
When the stack and the pressing portion are sandwiched between the pair of support members, the plurality of elastic members are compressed, and the compressed length of the elastic member provided in the second portion is the first length. A fuel cell, characterized in that the fuel cell is held so as to be longer than the length of compression of an elastic member provided in the portion. The fuel cell according to claim 1,
The fuel cell according to claim 1, wherein a thickness of the first member in the cell stacking direction in the second portion is larger than a thickness of the first member in the cell stacking direction. The fuel cell according to claim 1 or 2,
The second member has a third portion facing the first portion, and a fourth portion facing the second portion,
The fuel cell according to claim 1, wherein a thickness in the cell stacking direction of the fourth part of the second member is larger than a thickness of the third part in the cell stacking direction. The fuel cell according to any one of claims 1 to 3,
The plurality of elastic members are all the same.

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