JP2013033658A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a conventional fuel cell that since a high density filler is interposed between a hood covering the outer periphery of a fuel cell stack and a case housing the same, expansion or contraction caused in the case by thermal shock increases a burden on the hood.SOLUTION: In a fuel cell FC, a fuel cell stack 1 consisting of a plurality of cell units C which are laminated one on another via a space, a hood 2 covering the outer periphery of the fuel cell stack 1, and a case 3 housing the same are arranged in coaxial form, where gas is supplied to spaces between the cell units C themselves of the fuel cell stack 1 through a gas passage 7 formed between the hood 2 and the case 3. The fuel cell FC includes, in at least one of the opposite ends in axial direction of the hood 2, a connection member 11 which blocks a gap between the hood 2 and the case 3 and is elastically deformable in the axial direction. Therefore, even when the case 3 expands or contracts by thermal shock, this composition helps to reduce a load imposed on the hood 2.

Description

  The present invention relates to a solid electrolyte fuel cell, and more particularly to an improvement in a fuel cell in which a reaction gas is circulated in a case containing a fuel cell stack.

  Conventionally, as a fuel cell as described above, there has been one described in Patent Document 1, for example. The fuel cell described in Patent Document 1 has a structure in which a plurality of cell units are stacked to form a fuel cell stack, and the fuel cell stack is accommodated in a case. The cell unit includes a single cell having a structure in which an electrolyte layer is sandwiched between a fuel electrode layer and an air electrode layer, and a separator that forms a closed space (gas flow path) between the fuel electrode layer of the single cell. The air electrode layer is exposed outside the unit.

  The above fuel cell introduces an anode gas into each cell unit of the fuel cell stack and supplies the anode gas to the fuel electrode layer. Further, a cathode gas is introduced into the case and is circulated between the cell units, and the cathode gas is supplied to the air electrode layer. In this way, electric energy is generated by an electrochemical reaction in each cell unit.

  In addition, in this type of fuel cell, in order to improve power generation efficiency, there is a type in which a cylindrical hood is disposed on the outer periphery of the fuel cell stack and a gas flow path is formed between the hood and the case. In this fuel cell, the cathode gas introduced into the case is preheated by passing through the gas flow path, and the preheated cathode gas is supplied to the fuel cell stack.

JP 2007-141767 A

  By the way, in the conventional fuel cell as described above, in order to increase the supply efficiency of the cathode gas to the fuel cell stack, a high-density filler is packed between the hood and the case to improve the airtightness between the two. Was maintained. For this reason, if the case expands or contracts due to a temperature change caused by operation / stop of the fuel cell, the case presses the hood through the filler, and this is repeatedly performed. There was a problem to solve such problems.

  The present invention has been made paying attention to the above-described conventional problems, and is a fuel cell stack formed by stacking a plurality of cell units, a hood that covers the outer periphery of the fuel cell stack, and a case for housing these. It is an object of the present invention to provide a fuel cell that can reduce the burden on the hood even when the case expands and contracts due to thermal shock.

  The fuel cell of the present invention includes a fuel cell stack formed by laminating a plurality of cell units with a gap therebetween, a hood that covers the outer periphery of the fuel cell stack, and a case that accommodates these in a coaxial state. This fuel cell has a structure in which gas is preheated through a gas passage formed between the outer peripheral surface of the hood and the inner peripheral surface of the case, and the preheated gas is supplied to the gap between the cell units of the fuel cell stack. Yes.

  The fuel cell has a configuration in which at least one end portion of both ends in the axial direction of the hood is provided with a connecting member that closes the space between the hood and the case and is elastically deformable in the axial direction. It is a means to solve the problem.

  According to the present invention, in a fuel cell comprising a fuel cell stack composed of a plurality of cell units, a hood that covers the outer periphery of the fuel cell stack, and a case that accommodates the fuel cell stack, the case is expanded by thermal shock. Even when contracted, the burden on the hood can be reduced. Thereby, thickness reduction and weight reduction of a food | hood are realizable.

It is sectional drawing (A) explaining one Embodiment of the fuel cell concerning this invention, and the expanded sectional view (B) of the principal part. It is sectional drawing explaining a fuel cell stack. It is a perspective view of the hood and connection member shown in FIG. It is the top view (A) explaining the connection member shown in FIG. 1, and the perspective view (B) which abbreviate | omitted the half. It is sectional drawing (A) explaining other embodiment of the fuel cell which concerns on this invention, and the expanded sectional view (B) of the principal part. FIG. 6 is a perspective view of the hood and connection member shown in FIG. 5. It is the top view (A) and side view (B) explaining the connection member shown in FIG. It is sectional drawing (A) explaining further another embodiment of the fuel cell concerning this invention, and the expanded sectional view (B) of the principal part. It is a perspective view explaining the food | hood shown in FIG. 8, a connection member, and a buffer member. It is a top view explaining the food | hood shown in FIG. 8, a connection member, and a buffer member.

  The fuel cell FC shown in FIG. 1 is a solid electrolyte fuel cell, and includes a fuel cell stack 1 formed by stacking a plurality of cell units, a hood 2 that covers the outer periphery of the fuel cell stack 1, and these components. The case 3 is provided in a coaxial state.

  The fuel cell stack 1 is composed of a plurality of cell units C as shown in FIG. The cell unit C includes a single cell having a structure in which an electrolyte layer is sandwiched between a fuel electrode layer and an air electrode layer, and a separator that forms a sealed space between the fuel electrode layer of the single cell. The structure is exposed to the outside. Each cell unit C has an anode gas (hydrogen) discharge hole in the center, and an anode gas supply hole in the outer periphery of the discharge hole. The gas flow path leading to is formed.

  The cell unit C constitutes the fuel cell stack 1 by being stacked in multiple stages with a gap between each other. At this time, the supply holes and the discharge holes are made to be continuous with each other in the axial direction, thereby supplying the anode gas supply path. 4A and the discharge path 4B are formed.

  As shown in FIG. 3, the hood 2 is a metal member having a cylindrical shape, and has flange portions 2A and 2A over the entire circumference at both end portions in the axial direction, and is opposed to the body portion by 180 degrees. At the position, it has an introduction opening 2B and a discharge opening 2C. These openings 2B and 2C are formed over the axial direction of the trunk.

  The hood 2 is integrally provided with cathode gas (air) supply pipes 2D and 2D on both sides of the discharge opening 2C. Both supply pipes 2D are formed by making the wall portion of the hood 2 into a double structure, and are continuous over the axial direction of the trunk portion, and the cathode gas ejection portions 2E are disposed at positions opposite to each other in the circumferential direction. Have.

  The case 3 is a metal member having a cylindrical shape as shown in FIG. 1. In the illustrated example, the case 3 has a main body 5 that forms a body portion, and an annular portion 6 that is connected to the lower end of the main body 3A. It consists of Further, the case 3 has openings at both ends in the axial direction for allowing the supply passage 4A and the discharge passage 4B of the fuel cell stack 1 to pass through, and the edge portions of the openings become inward flange portions 3A and 3A. ing.

  In the fuel cell FC, the fuel cell stack 1 and the hood 2 are accommodated in the case 3 in a coaxial state. At this time, an arc-shaped gas flow path 7 is provided between the outer peripheral surface of the hood 2 and the inner peripheral surface of the case 3. Form. A discharge pipe (not shown) is disposed in the discharge opening 2C of the hood 2.

  In this way, the fuel cell FC has a structure for preheating and supplying gas (cathode gas) to the fuel cell stack 1 by the gas flow path 7 formed between the outer peripheral surface of the hood 2 and the inner peripheral surface of the case 3. It has become a thing.

  That is, in the fuel cell stack 1, the fuel cell FC introduces the anode gas from the supply path 4A to each cell unit C and supplies the anode gas to the fuel electrode layer. The anode off gas is discharged to the outside from the discharge path 4B.

  In addition, the fuel cell FC circulates the anode gas as described above, while introducing the cathode gas into the gas flow path 7 from the ejection portion 2E of the supply pipe 2D of the hood 2, and using the fuel cell stack 1 as a heat source, the gas flow The cathode gas in the passage 7 is preheated. Next, the preheated cathode gas is introduced into the hood 2 from the introduction opening 2B. As a result, the cathode gas is circulated in the gap between the cell units C of the fuel cell stack 1 and supplied to the air electrode layer exposed to the outside of the unit. The cathode off gas is discharged outside through a discharge pipe (not shown).

  The fuel cell FC includes a connecting member 11 that closes between the hood 2 and the case 3 and is elastically deformable in the axial direction at at least one end of both axial ends of the hood 2. Yes. In this embodiment, connecting members 11 and 11 are provided at both ends (upper and lower ends in FIG. 1) of the hood 2 in the axial direction.

  As shown in FIG. 4, the connecting member 11 is a ring-shaped member, and in this embodiment, has a bellows shape having a waveform cross section continuous in the axial direction. It is elastically deformable. The connecting member 11 has flat surfaces at both ends so that it can be airtightly bonded to the hood 2 and the case 3. The material of the connecting member 11 is not particularly limited, but it is more preferable to form the connecting member 11 from a heat-resistant metal such as high chromium steel or nickel alloy.

  The connecting member 11 is interposed between the flange portion 2A of the hood 2 and the inward flange portion 3A of the case 3. At this time, the hood 2 and the case 3 are all welded or brazed by metal. Airtightly joined around the circumference. Thereby, both ends (upper and lower ends) of the gas flow path 7 formed between the hood 2 and the case 3 are sealed to prevent the cathode gas from leaking. Thereby, the supply efficiency of the cathode gas to the fuel cell stack 1 is increased.

  In the fuel cell FC having the above configuration, when the case 3 expands / contracts due to thermal shock, specifically, when the case 3 expands / contracts due to a temperature change associated with the operation / stop of the fuel cell FC. However, the connecting member 11 is elastically deformed to absorb the displacement of the case 3 and the burden on the hood 2 can be greatly reduced. Therefore, the hood 2 can be reduced in thickness and weight, and this contributes to improvement in the preheating efficiency of the cathode gas flowing through the gas flow path 7 and weight reduction of the fuel cell itself. Can do.

  In addition, if the connecting member 11 is provided at one end of both ends of the hood 2 in the axial direction, a predetermined effect can be obtained. However, the connecting member 11 is provided at both ends of the hood 2 in the axial direction as in the above embodiment. For example, the function of reducing the burden on the hood 2 and the function of sealing the gas flow path 7 can be further enhanced.

  Furthermore, in the fuel cell FC, since the connecting member 11 is formed of a heat-resistant metal such as high chromium steel or nickel alloy, the heat resistance of the solid oxide fuel cell with respect to the high operating temperature is sufficiently secured, and the function is maintained for a long time. can do. Further, since the hood 2 and the connecting member 11 and the connecting member 11 and the case 3 are joined by welding or metal brazing material, the gas flow path 7 can be kept airtight for a long time.

  5-7 is a figure explaining other embodiment of the fuel cell of this invention. In the following embodiments, the same components as those of the previous embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The fuel cell FC shown in FIG. 5 includes connecting members 21 that close the space between the hood 2 and the case 3 and are elastically deformable in the axial direction at both ends in the axial direction of the hood 2. As shown in FIGS. 6 and 7, the connecting member 21 of this embodiment has a bellows shape having a wave-like cross section continuous in the axial direction, an end portion having an outer dimension corresponding to the end surface of the hood 2, and a case 3. The other end of the outer dimensions corresponding to the inner method.

  In the illustrated fuel cell FC, since the hood 2 and the case 3 have a cylindrical shape, the connection member 21 includes a small-diameter end portion (one end portion) having a diameter corresponding to the annular end surface of the flange portion 2A of the hood 2. And has a large-diameter end (the other end) having a diameter corresponding to the inner diameter of the case 3, and in particular, as shown in FIG. Yes.

  Even in the fuel cell FC described above, as in the previous embodiment, the gas flow path 7 between the hood 2 and the case 3 is sealed by the connecting member 21 to prevent the cathode gas from leaking, and the fuel cell The cathode gas supply efficiency to the stack 1 is increased. Even when the case 3 expands and contracts due to thermal shock, the connection member 11 absorbs the displacement, and the burden on the hood 2 can be greatly reduced.

  Further, in the fuel cell FC, the connecting member 21 has one end portion (large diameter end portion) having an outer dimension corresponding to the end surface of the hood 2 and the other end portion (small diameter) corresponding to the inner method of the case 3. In particular, positioning in the case 3 is very easy. At this time, the joining member 21 may be arranged in the case 3 in advance, or may be joined in advance to the hood 2 as shown in FIG.

8-10 is a figure explaining further another embodiment of the fuel cell of this invention.
A fuel cell FC shown in FIG. 8 includes connecting members 11 that close between the hood 2 and the case 3 and are elastically deformable in the axial direction at both ends of the hood 2 in the axial direction. The connection member 11 of this embodiment is the same as that of the embodiment shown in FIG.

  The fuel cell FC includes a buffer member that is elastically deformable in a direction perpendicular to the axis of the hood 2 between the outer peripheral surface of one end of the both ends of the hood 2 in the axial direction and the inner peripheral surface of the case 3. 31 is provided. In this embodiment, as shown in FIGS. 9 and 10, a total of four pieces at 90 degree intervals around the axis of the hood 2 between the outer peripheral surface of both ends in the axial direction of the hood 2 and the inner peripheral surface of the case 3. The buffer member 31 is arranged.

  The buffer member 31 is formed by bending a flat plate into a wave shape and can be elastically deformed. The material of the buffer member 31 is not particularly limited, but, like the connection member 11, high chromium steel, nickel alloy, or the like It is more desirable to form with a refractory metal. The number of the buffer members 31 is not particularly limited. However, if the number is too large, the entire periphery of the hood 2 is constrained, and the effect of releasing the load from the case 3 side is reduced. Depending on the size, it is desirable to arrange about 2 to 6 at a predetermined interval.

  Even in the fuel cell FC described above, as in the previous embodiment, the connecting member 11 seals the gas flow path 7 between the hood 2 and the case 3 to prevent the cathode gas from leaking. The cathode gas supply efficiency to the stack 1 is increased.

  In the fuel cell FC, even when the case 3 expands and contracts due to thermal shock, the connecting member 11 absorbs the displacement in the axial direction, and the buffer member 31 absorbs the displacement in the direction perpendicular to the axis of the hood 2, that is, in the radial direction. Absorbs and greatly reduces the burden on the hood 2. In this embodiment, the connecting member 11 that is elastically deformed in the axial direction and the buffer member 31 that is elastically deformed in the radial direction can also have a function of holding the hood 2 in a fixed position in the case 3.

  The configuration of the fuel cell of the present invention is not limited to the above-described embodiments, and details of the configuration can be appropriately changed without departing from the gist of the present invention. It may be a hood or case having a shape.

C cell unit FC fuel cell 1 fuel cell stack 2 hood 3 case 7 gas flow path 11 connection member 21 connection member 31 buffer member

Claims (8)

A fuel cell stack formed by stacking a plurality of cell units, a hood that covers the outer periphery of the fuel cell stack, and a case that accommodates these are provided in a coaxial state,
A fuel cell having a structure for preheating and supplying gas to a fuel cell stack by a gas flow path formed between an outer peripheral surface of a hood and an inner peripheral surface of a case,
A fuel cell comprising a connecting member that closes between the hood and the case and is elastically deformable in the axial direction at at least one end of both ends in the axial direction of the hood.   The fuel cell according to claim 1, wherein the connecting member has a bellows shape having a corrugated cross section continuous in the axial direction.   3. The fuel cell according to claim 2, wherein the connecting member has one end portion having an outer dimension corresponding to the end face of the hood and the other end portion having an outer dimension corresponding to the inner method of the case.   A shock absorbing member that is elastically deformable in a direction perpendicular to the axis of the hood is provided between the outer peripheral surface of one end of the both ends in the axial direction of the hood and the inner peripheral surface of the case. The fuel cell according to any one of 1 to 3.   The fuel cell according to claim 4, wherein the buffer members are arranged at predetermined intervals around the axis of the hood.   The fuel cell according to any one of claims 1 to 5, wherein the connecting member is formed of a heat-resistant metal such as high chromium steel or nickel alloy.   The fuel cell according to any one of claims 1 to 6, wherein the hood and the connecting member, and the connecting member and the case are joined by welding.   The fuel cell according to any one of claims 1 to 6, wherein the hood and the connecting member, and the connecting member and the case are joined by a metal brazing material.

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