JPS5975577A - Fuel cell assembly - Google Patents

Abstract

PURPOSE:To apply a constant clamping force to a fuel cell assembly regardless of operating conditions of the same, by providing clamping boards disposed on both top and bottom faces of the fuel cell assembly, formed of a plurality of unit cells stacked one upon another, and providing clamping forcd between the boards with the use of clamping members having coil springs. CONSTITUTION:A plurality of unit cells, each thereof being formed of a matrix impregnated with phosphoric acid, a pair of electrodes, and an interconnector provided with passage for fluids thereon, are stacked up, and manifolds 4 are provided on the side faces of the cell stack thereby to form a fuel cell assembly 6. Clamping boards 7A, 7B are provided on both top and bottom faces of the cell assembly, clamping rods 13 each thereof being formed of a normally shrunk coil spring 11 and two rods 12 attached to both its ends are inserted through holes provided in the clamping board, and nuts are used for the clamping and fixation. Since the coil springs 11 used are of a low spring constant, even if the fuel cell assembly 6 exhibits great thermal expansions and shrinkages, such displacement amounts can readily be absorbed by the springs. Therefore a constant clamping force is always provided, and reduced efficiency can thus be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fuel cell device in which a tightening member for tightening and holding a fuel cell formed by stacking a plurality of unit cells is improved.

[Technical background of the invention]

A fuel cell device is known as a device that directly converts energy contained in fuel into electrical energy.

In this fuel cell device, a pair of electrodes of a porous material is usually arranged with an electrolyte sandwiched therebetween. Then, a fluid fuel such as liquefied hydrogen is brought into contact with the back surface of one electrode, and a fluid oxidizer such as liquefied oxygen is brought into contact with the back surface of the other electrode to cause an electrochemical reaction between the electrodes. Electrical energy is extracted from between the electrodes. Such a fuel cell device can extract wind energy with high conversion efficiency as long as the fuel and oxidizer are supplied.

In the above-mentioned fuel cell device, a specific example of a structure in which phosphoric acid is used as an electrolyte will be described with reference to FIG. In FIG. 1, l is a matrix impregnated with phosphoric acid as an electrolyte. Two electrodes 2 are arranged so as to sandwich both sides of this matrix lV (for example).The electrodes 2 are usually made of a porous material made of carbonaceous material, and a catalyst is added thereto. A plate-shaped interconnector 3 usually made of a mixed bond of graphite and thermosetting resin is disposed on the back surface of each of the connectors 2 .

Fluid circulation grooves 31.3B are formed on each surface of the interconnector 3 in contact with the electrodes 2, the directions of which are perpendicular to each other.

Above matrix 1. Electrode 2. The interconnectors 3 are closely laminated to form a unit cell.

Fluid circulation grooves 3A, 3 of interconnector 3 of this unit cell
B are formed in directions perpendicular to each other, and the fuel or oxidant fluid flows into the openings at the edges thereof. In this case, fluid fuel is allowed to flow through the fluid flow groove 3A of one interconnector 3 of the unit cell, and fluid oxidizer is allowed to flow through the fluid flow path 3B of the other interconnector 3 of the unit cell.

Further, the unit cells are stacked airtight, and the fluid flow path, 9
Since A, 9B are formed in directions perpendicular to each other, the fluid fuel and the fluid oxidizer do not mix.

A plurality of unit cells configured as described above are stacked to form a fuel cell. A manifold P shown in FIG. 2 is assigned to each side of this fuel cell. In Figure 2, 4A
is a fuel supply manifold provided with a fuel supply pipe 5A. 4B is a fuel discharge manifold installed opposite to the fuel supply manifold 4AK and provided with a solvent discharge pipe 5B. 4C is the above manifold 4
This is an oxidizing agent supply manifold installed in a direction perpendicular to the 48V voltage and provided with an oxidizing agent supplying pipe 5C. 4D is an oxidant discharge manifold that is installed opposite to the oxidant supply manifold 4C and is provided with an oxidant discharge pipe 5D.

A fuel cell in which a large number of unit cells are stacked has a manifold 4 applied to each side thereof, and is tightened by a tightening member as shown in FIG. 3. In FIG. 3, 6 is This is a fuel cell, and a manifold 4 is placed on the side surface of the fuel cell 6, and clamping plates 7A and 7B are placed on the upper and lower surfaces of the fuel cell 6.The edges of the clamping plates 7A and 7B are provided with penetrating holes. A hole is provided, and a rod 8 is inserted into the through hole.A disc spring 9 is attached to the end of the upper front rod 8, and the disc spring 9 is tightened with a seat 10 to provide a shock absorber. The clamping plates 7A and 7B are movable inwardly.
is tightened upward and downward.

[Problems with background technology]

The above tightening plates 7A, 7B, rod 8, disc spring 9, built 1
The tightening member made of zero is applied with a predetermined tightening force in order to maintain the shape of a plurality of stacked unit cells and to reduce the electrical contact resistance value between each unit cell, and in consideration of the strength of the unit cells. must be configured so that it occurs. On the other hand, when the fuel cell device is operated at a normal rating, the temperature of the fuel cell 6 rises to around 200°C, and the temperature of the tightening member rises to around 100°C. Also, the thermal expansion coefficient of the fuel cell 6 is 5 x 1
0'/°C, the thermal expansion coefficient of the clamping member usually made of steel is 1.2, 1.7X1o-'y°C, and the fuel cell 6 expands by 10 C3 during operation. , the tightening member expands by 1.7×1σ3, and the fuel cell 6 expands more.

However, since the disc spring 9 has a large spring constant θ, the tightening pressure of the fuel cell 6 varies greatly depending on the operating state of the fuel cell device. If the tightening member made of the disc spring 9 cannot absorb the expansion of the fuel cell 6 and the tightening pressure increases, each unit cell may be crushed.

Further, if the tightening pressure is small, the electrical resistance value between the many unit cells forming the fuel cell 6 increases, and the voltage drop becomes large and the loss of the output electrical energy becomes large.

Moreover, a predetermined tightening pressure is obtained by arranging a large number of disc springs 9 in series or in parallel. However, there is a drawback that it takes time to arrange the disc spring 9 during manufacturing.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks, and its purpose is to maintain a constant tightening pressure of the fuel cell against changes in operating conditions by simplifying the structure, and thereby to output electricity. It is an object of the present invention to provide a fuel cell device that prevents a decrease in energy efficiency and does not damage unit cells forming a fuel cell.

[Summary of the invention]

In the fuel cell device according to the present invention, clamping members are respectively installed on both end faces in the stacking direction of the unit cells of a fuel cell formed by stacking a plurality of unit cells, and each clamping member has a coil spring. By having the following configuration, the above object is achieved.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Fourth
The figure is a cross-sectional configuration diagram showing an embodiment of a fuel cell device according to the present invention.

In FIG. 4, a manifold 4 is attached to the side surface of a fuel cell 6 formed by stacking a plurality of unit cells, and clamping plates 7A and 7B are installed at the upper and lower parts. This tightening plate 7
Through-holes are provided at the ends of A and 7B, and in these through-holes, openings and doors 12 are attached to both ends of a normally closed coil spring 11, and a tightening rod 13 is cut out. The end is inserted and installed. The ends of the tightening rod 13 are tightened with bolts 10 and tightening plates 7A and 7B.
is moved inward and the fuel chamber is tightened.

Next, the operation of this embodiment configured as above will be described. That is, compared to the disc spring 9 conventionally used as a tightening means, the coil spring 11 in this embodiment has a spring constant of about 1/100 to 1/1000. Therefore, even if the fuel cell 6 undergoes significant thermal expansion or contraction, the displacement can be easily absorbed because the coil spring 11 having a low spring constant value is used. Further, since the coil spring 1 can generate a predetermined spring pressure by itself, it is easy to assemble the fuel cell 6 and the tightening member.

Note that the present invention is not limited to the above embodiments. For example, by connecting two coil springs in series instead of one coil spring as shown in FIG. 4, displacement due to thermal expansion can be more easily absorbed. In addition, the present invention can be implemented with various modifications without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, a fuel cell formed by stacking a plurality of unit cells is tightened by a tightening member having a coil spring. It is possible to provide a fuel cell device that maintains the clamping pressure of the fuel cell constant against changes, thereby preventing a decrease in the efficiency of the output electrical energy, and not damaging the unit cells forming the fuel cell.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a fuel cell, FIG. 2 is a perspective view showing a fuel cell with a manifold installed, FIG. 3 is a cross-sectional configuration diagram showing a conventional fuel cell device, and FIG. 4 is a diagram according to the present invention. FIG. 1 is a cross-sectional configuration diagram showing an example of a fuel cell device. 1...Matrix, 2... to pole 1.9-...ink connector, 3, 3B...fluid flow medium, 4 A +
4 B e4C, 4D... Manifold, 5A,
5B, 5C. 5D...pipe, 6...fuel cell, 7, 7B...
・Tightening plate, 8...Rod, 9...Disc spring, 0.
...Holt, 1 piece...Coil spring, 12 ports 1. 13...Tightening rod. Applicant's agent Patent attorney Takeshi Suzue Hikoga 1 Zuga 2v! J D Fang 3 Illustrated Fang 4

Claims (1)

[Claims] An electrolyte is interposed between the surfaces of the pair of electrodes, and the rear side of the one electrode is il? : #f, a fuel made by stacking a plurality of unit cells that output electric energy between a pair of electrodes, formed by circulating body fuel and circulating an IC fluid oxidizer on the back side of the other electrode. A fuel cell device, wherein a tightening member is installed between both end faces in the stacking direction of the unit cells, and each of the tightening members has a coil spring.