JPS6113348B2 - - Google Patents

Abstract

PURPOSE:To enable the cooling performance of a fuel cell to be changed automatically without using any pumps or fans by installing a radiator plate facing a heat-collecting metallic body formed on the surface of the fuel cell body and installing bimetals between the metallic body and the radiator plate. CONSTITUTION:After a metallic body 13 is affixed to the surface of a cell body 1, the whole body is covered with a heat insulator 14. Ends of U-shaped bimetals 15 are fixed to two surfaces of the metallic body 13 by brazing. The other free ends of the bimetals 15 are located in a space 12 formed by the heat insulator 14 and a radiator plate 11. The material and the shape of the bimetals 15 are selected so that the free ends of the bimetals 15 touch the radiator plate 11 when the temperature exceeds a given level. Owing to the above constitution, temperature increase of the battery is accelerated by reducing its heat radiation when the battery is started at low temperature and the cooling performance of the battery is increased after its temperature reaches a given level, thereby achieving controlling of the temperature increase.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel cell, and is particularly suitable for a cell using a low boiling point liquid such as metalail as fuel.

The power generation performance of a fuel cell varies depending on the electrode temperature. That is, as the temperature decreases, the battery output decreases. When a fuel cell is in operation, heat is generated due to loss between the electrodes. Its size is determined by energy conversion efficiency.
Since it outputs 30-70%, it is about twice the battery output at maximum. This causes the battery temperature to rise, but if the battery temperature becomes excessive, the electrolyte will evaporate and the liquid fuel will vaporize, interfering with fuel supply and shortening the battery life. Cooling means must be provided to prevent this.

The basic configuration of a conventional fuel cell is shown in FIG. There is an electrolyte chamber 4 between the electrodes, that is, the fuel electrode 2 and the air electrode 3, and the fuel chamber 5 is adjacent to the fuel electrode 2.
Adjacent to the air electrode 3 is an air chamber 6. Reference numeral 7 is a container, and 8 is a terminal. In this way, the unit battery main body 1 is constructed. Conventionally, a method has been used to cool the battery by (1) causing air to flow into the air chamber 6 in the direction of the arrow to remove heat generated from the air electrode. As another method, (2) the fuel is circulated by the pump 10 in the closed loop system shown in FIG. 2, and a heat sink 11 is provided in the system to exchange heat generated in the fuel chamber using the fuel as a medium. There is a way. code 9
indicates the fuel circulation path. In this case, the fuel is
It is preferable that it is liquid at the operating temperature, such as metal rail,
Hydrazine and the like are used.

These methods are suitable for relatively high-output batteries, but for small batteries of several watts, using a rotating body such as a fan or pump for forced cooling not only increases the weight and size but also increases the cost. So it's not practical. Therefore, cooling using natural convection of air is used.

On the other hand, as mentioned above, since fuel cells have poor power generation performance at low temperatures, it is necessary to heat the cells to a required temperature by some means at the time of startup.

For portable devices, it is difficult to obtain energy for heating, so it is necessary to be able to heat the device to the required temperature in the shortest possible time with as little energy as possible. To achieve this objective, it is best to insulate the battery body well to reduce heat dissipation to the surroundings. Conventionally, to keep the battery temperature constant, the rotational speed of a cooling fan is varied or the fuel flow rate is adjusted, but this method cannot be used if there are no rotating parts.

The purpose of the present invention is to
The purpose of the present invention is to provide a fuel cell that can automatically change the cooling performance of the battery.

That is, the present invention provides a metal body for collecting heat on at least a part of the surface of the battery body, a heat insulating material on the surface of the battery body, and a heat dissipating material facing the metal body and dissipating heat to the outside of the heat insulating material. a plate is provided, a bimetal is provided between the heat dissipation plate and the metal body, and one end of the bimetal is fixed to the metal body,
Thermal deformation of the bimetal causes thermal connection between the metal body and the heat sink when the battery body reaches a predetermined temperature or higher, thereby achieving the intended purpose. .

FIG. 3 shows an embodiment of the present invention. In FIG. 3, the reference numeral 1 is the battery body as shown in FIG. 1. 5a is a fuel injection port, and 6a and 6b are air intake ports and exhaust ports, respectively, and natural convection is used to take in air. Since such a battery body is usually made of plastic, a metal body 13 is attached to its surface. Since the purpose is to collect heat inside the battery, copper or aluminum plates are good, but metal has higher thermal conductivity than plastics, so the type does not matter. Furthermore, it is not necessary to affix the metal body 13 to all sides of the battery as shown.

A heat insulating material 14 covers the surface of the battery body including the metal body 13.
cover with Suitable materials for this material include paper, polyethylene terephthalate, polyethylene film woven fabric, non-woven fabric, thin foamed urethane, etc., and commercially available materials with adhesive on one side can be used. In this example, a polyethylene plate with a thickness of 0.5 mm was attached using a rubber adhesive.

One end of a U-shaped bimetal 15 is fixed to two sides of the metal body 13 by soldering, and the other end is placed as a free end in a space 12 formed by a heat insulating material 14 and a heat sink 11. The space 12 is sealed using the above-mentioned heat insulating material so as to prevent communication with outside air. The material and shape of the bimetal are determined so that the free end of the bimetal comes into contact with the heat sink when the temperature exceeds a predetermined value. Figure 4 shows an enlarged view of this part.
A metal plate 16 made of copper or the like having high thermal conductivity is fixed to the free end of the bimetal 15 that contacts the heat sink.

In the embodiment, a fuel cell using metal rail as fuel was used, the set temperature was set at 60° C., and two bimetallic contact portions were provided, but the number may be increased or decreased as necessary. With this configuration, when the battery body reaches 60 degrees Celsius, the heat dissipation performance can be increased approximately five times. When installing multiple bimetals, the contact temperature between the heat sink and the bimetal can be changed by changing the material of the bimetal or by changing the distance between the free end of the bimetal and the heat sink. This is possible with temperature control.

The effect of the present invention is that when the battery is started at a low temperature, heat dissipation is deteriorated to promote the temperature rise of the battery.
When the specified temperature is reached, the cooling performance is increased,
The purpose is to be able to control the temperature rise to a constant level. By changing the contact temperature of each of the plurality of bimetal contacts, even more precise temperature control can be achieved. If the cooling performance at low temperatures is lowered by such means, the battery can be started by external heating, or the small battery output at low temperatures can be converted into Joule heat, allowing steady output in a relatively short period of time. It is possible to reach the set temperature obtained by

FIG. 5 shows another embodiment of the invention. Like FIG. 4, this is an enlarged view of the bimetal contact portion. Metal plate 16 due to thermal deformation of bimetal 15
is pressed against a heat sink (not shown) (corresponding to the heat sink 11 in FIGS. 3 and 4), and the metal plate 16 is thermally connected to the metal body 13 by a deformable high heat conduction plate 17. There is. In this example, a strip made of thin copper wires was used. The feature of this system is that the heat flow passes through the high thermal conductivity plate 17 and the metal plate 16 to a heat sink (not shown), so that even if the dimensions of the bimetal are reduced, the heat transfer performance is not affected. By using a plurality of such thermal contacts, it is possible to achieve the same effect as the embodiments shown in FIGS. 3 and 4.

[Brief explanation of the drawing]

Figure 1 shows the basic structure of a fuel cell, and is a cross-sectional view of a unit cell. Figure 2 is a schematic diagram showing a conventional fuel cell cooling system. Figure 3 is a cross-sectional view of an embodiment of the present invention. FIG. 4 is an enlarged view of the bimetallic portion of FIG. 3, and FIG. 5 is a schematic diagram showing a thermal switch portion in another embodiment of the present invention. 1... Battery body, 2... Fuel electrode, 3... Air electrode, 4... Electrolyte chamber, 5... Fuel chamber, 6... Air chamber, 7... Container, 8... Terminal, 11... heat sink,
13...metal body, 15...bimetal.

Claims (1)

[Claims] 1. In a fuel cell equipped with a cell main body consisting of a pair of electrodes facing each other, an electrolyte chamber disposed between the electrodes, and a fuel chamber and an air chamber disposed adjacent to the electrodes on the side opposite to the electrolysis chamber. , a heat collecting metal body is provided on at least a part of the surface of the battery body, a heat insulating material is provided on the surface of the battery body, and a heat sink is further provided on the outside of the heat insulating material facing the metal body. , a bimetal is provided between the heat dissipation plate and the metal body, and one end of the bimetal is fixed to the metal body, and thermal deformation of the bimetal causes the metal body to change when the temperature of the battery body reaches a predetermined temperature or higher. A fuel cell characterized in that the fuel cell is thermally connected to the heat sink.