JPH0547397A - Fuel cell - Google Patents

Abstract

PURPOSE:To shorten the temperature rise time at the time of a start without reducing the cell performance by inserting conducting plates electrically connecting electric heaters and unit cells between the unit cells at the intermediate area in the lamination direction of a stack. CONSTITUTION:Plate-like electric heaters 10 are inserted between multiple unit cells 2 at an interval to be pinched by adjacent unit cells 2 at several positions on both end faces and the intermediate area in the laminating direction of a stack 1. The heater 10 is inserted between metal conducting plates folded into a U-shape, it is surrounded by the inside of a gasket 13, and the conducting plate electrically connects the upper and lower unit cells 2. The heater 10 is connected to the battery 15 of an external power source via a controller 14, and the whole cell is controlled at the uniform temperature distribution by the detection signal of a temperature sensor 16. Heating has no relation to vapor, the reduction of the cell performance due to the dilution and scattering of an electrolyte at the time of a start is prevented, and the temperature rise time can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell capable of shortening the temperature rising time at the time of starting.

[0002]

2. Description of the Related Art As is well known, a fuel cell is one in which a fuel gas such as hydrogen is reacted with air in a single cell to generate electricity. Generally, in order to obtain a desired high voltage, The stack is composed of stacks in which a plurality of single cells for performing the power generation reaction are stacked. Since the reaction of this fuel cell is an exothermic reaction, the power generation voltage at the time of start-up is not stable unless the temperature rises above a certain level. Conventionally, in order to shorten the time until such a generated voltage is stabilized, for example, Japanese Patent Laid-Open No.
As described in Japanese Patent Laid-Open No. 48379, there is a device in which external heat is supplied at startup.

However, since the conventional heating means of the fuel cell mainly uses the combustion gas from the reformer for producing fuel gas, it is difficult to efficiently use the heat energy to raise the temperature, and the heating time is shortened. There was a limit to further shortening. Further, since the combustion gas contains water vapor, when this water vapor is supplied to the low temperature fuel cell body, dew condensation occurs, which dilutes the electrolytic solution (phosphoric acid) or evaporates as the temperature rises. In some cases, phosphoric acid is scattered outside the fuel cell body, which causes a problem that the cell performance is deteriorated. In particular, in a fuel cell that is used for applications where it is frequently turned on and off, the above phenomenon is frequently repeated, so that there is a drawback in that deterioration of cell performance is significantly accelerated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel cell in which the temperature rise time at startup is further shortened and the cell performance is not deteriorated.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention relates to a fuel cell in which a plurality of unit cells are stacked to form a stack, and the unit cells are adjacent to each other in the intermediate region in the stacking direction of the stack. It is characterized in that an electric heater and a conductive means for electrically connecting the both unit cells are interposed so as to be sandwiched between them.

When the electric heater is provided together with the conductive means in this way, the electric heater can be inserted into the stack intermediate region without hindering the electrical connection between the single cells, thereby eliminating waste of heat energy. It becomes possible to raise the temperature and further shorten the temperature raising time. Further, since the electric heater is not a heating means containing water vapor, it does not dilute or scatter the electrolytic solution, and the battery performance is not deteriorated.

The present invention will be described below with reference to the embodiments shown in the drawings. In FIGS. 1 and 2, 1 is a stack, which is formed by stacking a large number of single cells 2 in multiple stages. The unit cell 2 has the same structure as a conventionally known structure, and is configured by interposing a matrix layer impregnated with an electrolytic solution (phosphoric acid or the like) between an anode plate and a cathode plate.

In the stack 1, the upper end plate 3 and the lower end plate 4 are brought into contact with the upper surface and the lower surface, respectively, and the outer side of the upper end plate 3 has a tightening bar 5 and a spring 6 each having an X shape in plan view. And a tightening bar 7 having an X shape in plan view is also provided outside the lower end plate 4, and four bolts 8 are respectively passed through the four corners of the lower end plate 4 so as to be tightened and fixed. Four spring bearings 5a are integrally formed at the X-shaped intersection of the upper tightening bar 5 so as to sandwich the intersection, and the upper end of the spring 6 is engaged with the spring bearing 5a and the lower end thereof is engaged. Presses the upper surface of the upper end plate 3.

Inner manifolds 11a, 11b; 12a, 12b are provided inside the four sides of the stack 1 so as to vertically penetrate therethrough. Of these, fuel gas (hydrogen, etc.) is distributed to the inner manifolds 11a to 11b, and air is distributed to the inner manifolds 12a to 12b into each of the multi-stage single cells 2, and both gases are supplied to each of the single cells 2. Water and electric energy are generated by reacting in the matrix layer.

Further, the stack 1 is arranged so that it is sandwiched between adjacent unit cells at intervals between a plurality of unit cells 2 at both end faces in the stacking direction and at several places in the intermediate region. A plate-shaped electric heater 10 is inserted. More specifically, as shown in FIGS.
Is inserted between the conductive plates 9 made of metal bent in a U shape, surrounded by the inside of the gasket 13, and sandwiched between two unit cells 2 and 2 vertically adjacent to each other in that state. There is. The conductive plate 9 is bent in a U shape so as to electrically connect the upper and lower unit cells 2 and 2 with the electric heater 10 inserted inside.

As the conductive plate 9, instead of a metal plate, a gel-like material such as an organic synthetic resin having conductivity may be used to cover the periphery of the electric heater 10. Alternatively, instead of using the conductive plate 9, the gasket 13 may be made of conductive rubber or resin. Each of the plurality of electric heaters 10 is connected to a battery 15 of an external power source via a control unit 14 by a lead wire 10a. Further, in the stack 1, a temperature sensor 16 is inserted in an intermediate portion where a plurality of electric heaters 10 are adjacent to each other, and each temperature sensor 16 is connected to the control unit 14 via a lead wire 16a. The temperature sensor 16 detects the temperature of the area in which the temperature sensor 16 is inserted and inputs the detection signal to the control unit 14. On the other hand, the control unit 14 controls the amount of current to each electric heater 10 based on the input temperature detection signal, and controls the individual amount of heat generation so that the entire fuel cell has a uniform temperature distribution.

The above-mentioned heating by the electric heater 10 is performed without wasting heat energy, so that the fuel cell main body is heated in a short time to a desired stable power generation temperature by heating at the time of starting the fuel cell. Therefore, the temperature raising time can be further shortened. Further, in the case of the above embodiment, the fuel cell main body can be heated so as to have a uniform temperature distribution by controlling the amount of electricity supplied to the electric heater 10 by the detection signal of the temperature sensor 16. Further, since the electric heater 10 is not a heating means containing steam like combustion gas, it dilutes the electrolyte solution of the matrix layer in the single cell 2 or scatters the electrolyte solution to the outside of the fuel cell body. The battery performance does not deteriorate.

[0013]

As described above, in the fuel cell of the present invention, the electric heater and the two unit cells are electrically connected so as to be sandwiched between the unit cells adjacent to each other in the intermediate region of the stack stacking direction. The electric heater can be inserted into the stack intermediate region without hindering the electrical connection between the unit cells. Therefore, the electric heater can raise the temperature without wasting heat energy at the time of start-up, and the temperature raising time can be further shortened. Moreover, since the electric heater is a heating means that has nothing to do with water vapor, it may dilute the electrolytic solution during heating at the time of startup,
It does not scatter and the battery performance does not deteriorate.

[Brief description of drawings]

FIG. 1 is a front view of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a plan view of the fuel cell.

FIG. 3 is a plan view of a portion of an electric heater provided in the fuel cell.

4 is an enlarged view of a cross section taken along the line VI-VI of FIG.

[Explanation of symbols]

1 Stack 2 Single cell 3
Upper end plate 4 Lower end plate 9 Conductive plate (conductive means) 1
0 electric heater

Claims (1)

[Claims] 1. A fuel cell in which a stack is formed by stacking a plurality of unit cells, and an electric heater and both unit cells are sandwiched between adjacent unit cells in an intermediate region of the stack in the stacking direction. A fuel cell in which a conductive means for electrically connecting cells is also interposed.