JP2848120B2 - Thermal battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal battery having a built-in exothermic agent inside a battery and igniting the exothermic agent when the battery is used to heat and activate the inside of the battery to a high temperature. This facilitates checking of the battery.

[0002]

2. Description of the Related Art A thermal battery is a battery using a molten salt as an electrolyte, and is in an inactive state during storage because the electrolyte is a non-conductive solid salt. Then, by heating the inside of the battery to a high temperature, the electrolyte is melted and becomes conductive and activated.

[0003] A thermal battery is a type of storage battery that has little self-discharge during storage, can be stored for a long period of time, and can be activated instantaneously when needed. In addition, it can be used in a wide range of environmental temperatures such as -55 to 100 ° C, and is indispensable as a power source for missiles, rockets and other flying objects, and various emergency power sources.

A well-known system using calcium as a negative electrode and calcium chromate as a positive electrode as an active material of a thermal battery is known. However, for higher capacity and higher output, lithium or a lithium alloy is used as a negative electrode and a positive electrode is used as a positive electrode. Thermal batteries using sulfides and oxides have also been developed.

[0005] Iron, nickel, chromium, cobalt, copper,
Sulfides and oxides such as tungsten and molybdenum have high electromotive force and energy density. The positive electrode is made of a composite compound of these metals or a part of which is doped with lithium ions to improve thermal stability and discharge characteristics.

As an electrolyte, LiCl-59 mol%, KCl-4
1 mol% eutectic salt is commonly used, but KBr-LiBr
Other molten salts with high ionic conductivity such as -LiCl, LiBr-KBr-LiF, LiBr-LiCl-LiF, etc. can also be used, and insulator powder such as kaolin, magnesium oxide, boron nitride, zirconium oxide, etc. Is used in a state where fluidity is lost by mixing. The electrolyte layer is a conductor of ions during operation of the thermal battery, and also functions as a separator between the positive electrode and the negative electrode.

[0007] As the exothermic agent, a mixture of an oxidizing agent and a reducing agent that generates little gas upon combustion is used. In general,
A mixture of iron powder and potassium perchlorate is used, and a plate-shaped product is alternately laminated with a unit cell. The exothermic agent is ignited when the battery is activated, causing an oxidation-reduction reaction to generate heat, thereby heating the inside of the battery to the operating temperature. This exothermic agent contains iron in excess of the amount required for the exothermic reaction, is conductive even after the exothermic reaction,
It also acts as a connector between adjacent unit cells.

[0008]

A thermal battery generates an electromotive force only by an activation operation for igniting a built-in exothermic agent. When using a thermal battery, the ignition ball is ignited by connecting an external power supply to the built-in ignition ball and energizing it.
The exothermic reaction of the exothermic agent starts with the energy.

In general, an ignition ball is composed of a filament called an electric bridge made of platinum, tungsten, or the like, and an igniting agent such as a mixture of lead thiocyanate and potassium chlorate or DDNP (diazodinitrophenol). Normally, the current required to ignite the ignition ball is 1 A, and the energizing time is 10 milliseconds or less. When the ignition ball ignites, the filament burns out, and the current supplied to the ignition circuit is automatically cut off.

[0010] However, the ignition ball used in the thermal battery sometimes shows a short circuit state after ignition. This is because the tip of the burnt ignition ball comes in contact with the impact accompanying the combustion of the explosive or the exothermic agent.

Since the electric power of the ignition ball is supplied from an external circuit, if the ignition circuit is not cut off, an excessive current flows through a lead wire for supplying electric power to the ignition circuit to generate heat or adversely affect the external circuit. did. In particular, when the thermal battery is used as an auxiliary power source of the main power source, the influence is large.
That is, the main power supply and the thermal battery are connected in parallel, and when igniting the ignition ball with the power from the main power supply, if the ignition circuit is not automatically cut off, the current generated from the thermal battery also flows into the ignition circuit, In some cases, a short circuit occurred.

In the case of a terminal configuration which also serves as a terminal for an ignition ball and an output terminal for a thermal battery, more serious results are caused. When the voltage of the ignition power supply and the voltage of the thermal battery are the same, the ignition terminal and the output terminal can be used in common. Before the activation of the thermal battery, the power generation unit is in an insulated state, there is no electromotive force, and all the current for the ignition ball is supplied to the ignition ball. After the activation, the ignition ball ignites and changes to an insulated state, so that all the generated current is supplied from the terminal to the outside.
However, if the ignition ball is short-circuited after activation, it is an internal short-circuit at the terminal, which is extremely dangerous.

[0013]

SUMMARY OF THE INVENTION The present invention relates to a thermal battery in which a unit cell and a heating agent are wrapped in a heat insulating material, housed in a closed container, and activated by applying an external current to the ignition ball. And a current limiting fuse is connected in series.

[0014]

In general, an energized ignition ball ignites in less than 10 milliseconds. On the other hand, the fuse is set to 10
The time until cutting can be varied in the range of milliseconds to several seconds. The rise time of the voltage due to activation of the thermal battery is between 50 milliseconds and several seconds. By connecting a current limiting fuse in series with the ignition ball,
When the ignition ball is short-circuited, the fuse is activated immediately to cut off the ignition circuit. By selecting the operating condition of the fuse, it is possible to operate the fuse before the rising of the electromotive force of the thermal battery.

[0015]

FIG. 1 is a sectional view of a thermal battery manufactured as an embodiment of the present invention. Reference numeral 1 denotes a unit cell, and 2 denotes a heat generating agent. 4 is a positive terminal,
5 is a negative electrode terminal. Reference numeral 6 denotes an ignition ball for activating the thermal battery, 7 denotes a fuse connected in series with the ignition ball, and 8 denotes an ignition terminal. By supplying an ignition current to the ignition terminal 8, the thermal battery is activated, and an electromotive force is generated between the positive terminal 4 and the negative terminal 5. 9 is a heat insulating material and 10 is a container, which keeps the inside of the thermal battery warm.

The resistance of the ignition ball 6 is about 0.6 Ω, and is ignited by supplying a current of 1 A. The fuse 7 used was one that cuts off the circuit in 100 milliseconds when a current of 1 A was applied.

An activation test was performed on 20 batteries of the present invention. An external power supply of 10 V was connected to the ignition terminal and activated. About 0.3 seconds after the ignition terminal was energized, the voltage between the positive terminal and the negative terminal reached 28 V, and the thermal battery was activated. After activation, all of the ignition terminals are open.
It was shown that the invention worked effectively. After the test was completed, the thermal battery was disassembled and the ignition balls and fuses were inspected. As a result, it was confirmed that the tips of the ignition balls of the four thermal batteries were short-circuited and the fuses were activated.

[0018]

According to the present invention, even if the ignition ball is short-circuited,
To ensure that the fuse is activated and cut off the ignition circuit,
It no longer adversely affects the ignition power supply. Therefore, it is possible to use the ignition terminal with the external power supply connected to it, and it is also possible to use both the ignition terminal and the output electrode terminal. Conventionally, it is not easy to check a used thermal battery. However, in the thermal battery of the present invention, since the ignition terminal is reliably turned off after activation, it is easy to determine whether or not the thermal battery is used. There is also an effect.

[Brief description of the drawings]

FIG. 1 is a sectional view of a thermal battery showing one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unit cell 2 Heating agent 3 Power generation part 4 Positive electrode terminal 5 Negative electrode terminal 6 Ignition ball 7 Fuse 8 Ignition terminal 9 Heat insulation material 10 Container

Claims (1)

(57) [Claims] 1. A thermal battery in which a unit cell and a heating agent are wrapped in a heat insulating material and stored in a closed container, and a current limiting fuse is connected in series with the ignition ball in a thermal battery which is activated by supplying an external current to the ignition ball. A thermal battery, characterized in that a thermal battery is connected.