JP2003092116A - Thermal battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal battery having an ignition agent layer producing no gap that discourages firing between lead wire ends, and having strength capable of holding the sufficient amount of an ignition agent. SOLUTION: This thermal battery is equipped with a power generating body formed by alternately stacking unit cells and heating agents; a firing sheet for firing the heating agent; and an ignition plug located near to the firing sheet and connected to a piezoelectric element with a pair of lead wires 6. The ignition plug is equipped with a holder 15 holding the lead wire end parts 6a to face each other; a first ignition agent layer 16a covering the lead wire end parts 6a; and a second ignition agent layer 16b containing a fiber material and covering the first ignition agent layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal battery provided with a spark plug, and more particularly to improvement of an ignition agent layer of the spark plug.

[0002]

2. Description of the Related Art A thermal battery is a type of storage type battery that is inactive at room temperature but becomes active at high temperature to supply electric power to the outside. The storage stability of the thermal battery is extremely good, and the same characteristics as immediately after production are maintained even after storage for 5 to 10 years. Moreover, since the thermal battery operates at high temperature,
Electrode reaction is easy to proceed and high output, and it is used as a power source for defense equipment such as missiles, induction equipment, and emergency power source.

Conventionally, an electric ignition ball, a percussion type detonator, etc. have been adopted for the ignition device of the thermal battery, and they have been used for various projectiles. However, a thermal battery using an electric ignition ball, a percussion type detonator, etc. is inconvenient in that it can be handled only by a limited authorized supplier according to the regulations. On the other hand, in Japanese Patent Publication No. 48-1457 and Japanese Patent Publication No. 64-45063, an ignition device using a piezoelectric element is examined.

FIG. 1 shows the structure of a thermal battery having an ignition device using a piezoelectric element. However, the main body portion excluding the ignition device is shown in cross section. The unit cell 1 and the heat generating agent 2 that heats the unit cell 1 to activate the unit cell 1 are alternately stacked to form a power generator 3. The heat generating agent 2 is connected to an ignition sheet 4 provided along the outer surface of the power generator 3. The ignition sheet 4 is close to the spark plug 5, and the spark plug 5 is connected to the ignition device 7 by a pair of lead wires 6. Power generator 3
Are housed in a heat insulating case 14 in a state of being covered with a heat insulating material 8 of ceramic fiber. The opening of the heat insulating case 14 has the positive electrode lead 9 and the negative electrode lead 10 of the power generator 3.
And a lid 1 having a hole 11 through which the pair of lead wires 6 pass.
It is sealed at 2. The hole 11 is hermetically sealed. The ignition device 7 includes a piezoelectric element 13. When a shock or the like is applied to the piezoelectric element 13, a high voltage is applied to the spark plug 5, the spark plug 5 is ignited, and the ignition sheet 4 is ignited. Then, the combustion of the ignition sheet 4 further propagates to the heat generating agent 2 and heats the unit cell 1.

Next, FIG. 3 shows an enlarged sectional view of an example of the spark plug 5. The spark plug 5 includes the end portions 6a of the pair of lead wires 6,
The holding body 15 holds 6a facing each other, and the ignition layer 16 formed so as to cover a part of the surface of the holding body 15 and the lead wire end portions 6a, 6a. Ignition agent layer 16
Is made from an igniter consisting of a metal powder such as zirconium and an oxide such as barium chromate (BaCrO ₄ ). Normally, the lead wire ends 6a, 6a on the holder 15 are immersed in a paste prepared by mixing water with an igniting agent,
By repeating the operation of drying, the ignition layer 16
Is formed. In order to retain a sufficient amount of the igniting agent in the igniting agent layer to ignite the ignition sheet, the strength is insufficient with the igniting agent alone. Therefore, glass fiber or ceramic fiber is mixed into the igniting agent layer as a reinforcing material Suggestions have been made.
Further, in order to prevent the ignition agent layer from falling off or collapsing, it has been proposed to coat the ignition agent layer with the holder 15 integrally with the resin coating 17.

[0006]

As described above, when ceramic fibers or the like are mixed in the igniting agent layer, the strength of the igniting agent layer is increased and it is possible to retain an amount of the igniting agent necessary for ignition. However, by mixing the fibers, the fibers enter between the lead wire end portions 6a, 6a, and the ignition agent does not enter the lead wire end portions 6a, 6a and the portion surrounded by the fibers, which is indicated by 18 in FIG. Such voids may be formed. If such a gap is formed between the lead wire end portions 6a, 6a, the spark generated by the piezoelectric element does not burn to the igniter, the ignition plug does not ignite, and the battery does not operate. In view of the above points, the present invention provides a thermal battery including an igniting agent layer having a strength capable of retaining a sufficient amount of igniting agent without forming voids that cause misfires between lead wire ends. The purpose is to provide.

[0007]

According to the present invention, in a thermal battery having an ignition plug, a holding member for holding the lead wire end portions facing each other, and a first ignition for covering the lead wire end portion. An igniter layer and a second igniter layer that includes a fibrous material and covers the first igniter layer. It is preferable that the second igniting agent layer is integrally covered with the holding body by a coating film of a resin composition containing a fiber material. Also, the second
The fibrous material of the igniter layer is preferably glass fiber or ceramic fiber.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The thermal battery of the present invention comprises a power generation body in which unit cells and a heat generating agent are alternately laminated, an ignition sheet for igniting the heat generating agent, and a pair of ignition sheets close to the ignition sheet. A spark plug connected to the piezoelectric element by a lead wire is provided.

A unit cell comprises a negative electrode layer made of lithium, calcium, etc., an electrolyte layer made of lithium chloride-potassium chloride eutectic mixed salt, etc., and a positive electrode layer containing iron disulfide, calcium chromate, etc. as main components. Become. The exothermic agent that heats and activates the unit cell is composed of metal powder and an oxidant. For example, an exothermic agent in which iron powder and potassium perchlorate are mixed is used. The ignition sheet consists of metal powder and an oxidizer. Examples of the metal powder include zirconium powder, and examples of the oxidizing agent include barium chromate. The piezoelectric element is installed in the ignition device. When a shock or the like is applied to the piezoelectric element, a high voltage is applied to the spark plug. At this time, the sparks generated by the discharge are used to ignite the ignition sheet.

As shown in FIG. 2, the spark plug 5 has a holder 15 made of glass for holding the lead wire ends 6a, 6a opposed to each other, and a first ignition layer 16 for covering the lead wire ends.
a and a second ignition agent layer 16b covering the first ignition agent layer 16a. The igniter is composed of metal powder and an oxidizer. A mixture of zirconium powder and barium chromate is typically used. First ignition layer 16a
Is basically composed only of an igniting agent, and the second igniting agent layer 16b is composed of an igniting agent mixed with inorganic short fibers as a reinforcing material.

As the fiber material of the second ignition layer, it is preferable to use inorganic fibers such as glass fibers and ceramic fibers. These may be used alone or in combination of two or more. Among these, ceramic fibers containing silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) as main components are particularly preferable because they are stable under high temperature and high humidity and have excellent chemical resistance. Fiber length is 0.1
It is preferably about 3.0 mm. Fiber length is 0.1m
If it is less than m, the entanglement (bonding force) between the fibers is weak,
The strength may be insufficient, and if it exceeds 3.0 mm, the spark plug surface is liable to be fluffed or the fiber is likely to be broken. The content ratio of the fibers of the second ignition layer is 1 to 2
0% by weight is preferred. If it is less than 1% by weight, the reinforcing effect is insufficient, and if it exceeds 20% by weight, the ignition performance is deteriorated.

The surface of the second igniting agent layer 16b is preferably covered with a film 17 made of a resin composition integrally with the holder 15 for holding the ends of the lead wires. When the thermal battery is applied to various flying objects, the required performance is extremely high. That is, under severe conditions, for example, several thousand to several hundred thousand m /
It is desired to further improve the reliability of the spark plug under the conditions of high impact of s ² and high turning of several thousands to several tens of thousands rpm. In order to satisfy such requirements, it is preferable that the coating film 17 be made of a resin composition containing the above-mentioned fiber materials. The content of the fiber material with respect to the total amount of the resin component and the fiber material of the coating film 17 is preferably 5 to 80% by weight, more preferably 10 to 80% by weight, and particularly preferably 20 to 40% by weight. When the content of the fibrous material is less than 5% by weight, the strength of the resin composition becomes insufficient, and sufficient results cannot be obtained even in a cold heat temperature impact test, a temperature-humidity cycle test and the like. On the other hand, if the content exceeds 80% by weight, combustion of the igniting agent and ignition of the ignition sheet may be hindered.

As the resin component of the coating film 17, a thermoplastic resin such as polyvinyl acetate, cellulose acetate, polyvinyl chloride or vinyl chloride-vinyl acetate copolymer is preferably used. These may be used alone or in combination of two or more. Among these, polyvinyl acetate is particularly preferable because it is water-soluble and has the optimum viscosity at around 20 ° C. and is easy to handle.

When the surface of the igniter is coated with the support member integrally with the coating film 17 of the resin composition, for example, a resin component is dissolved in a solvent, and a fiber material is mixed with the resin component. It can be soaked and then pulled up. The resin concentration when the resin component is dissolved in the solvent is preferably 10 to 50% by weight from the viewpoint of workability and the like. After pulling up, the resin composition can be solidified by drying at 50 to 80 ° C. for 8 to 15 hours.

When a thermosetting resin is used for the coating film 17, the resin film is cured after the coating film is dried, so that the resin coating film is likely to be broken during high impact. In addition, sparks may be less likely to be scattered during ignition.

Examples of the solvent include water, methyl acetate, ethanol and the like. These may be used alone or in combination of two or more. Of these, water is particularly preferred from the viewpoints of ease of handling and consideration for the environment. As a preferred embodiment of the resin composition before coating, for example, 100 parts by weight of an aqueous polyvinyl acetate solution having a concentration of 10 to 50% by weight, and 2.5 to 20 parts by weight of inorganic fibers are mixed, a concentration of 10 to 50% by weight. And 100 parts by weight of a solution of poly (cellulose acetate) dissolved in methyl acetate so that 2.5 to 20 parts by weight of inorganic fibers are mixed.

[0017]

EXAMPLES Next, the thermal battery of the present invention will be described more specifically based on examples.

Example 1 A thermal battery similar to that shown in FIG. 1 was manufactured except that the spark plug shown in FIG. 2 was used.
A mixture of 35 parts by weight of metallic zirconium powder and 65 parts by weight of barium chromate powder was used as the igniter. Inorganic fibers have a fiber length of 0.1 to 10 with silica and alumina as the main components.
0.3 mm of ceramic fiber was used and in the second igniter layer, 6.5 wt% was mixed with the igniter. The first igniting agent layer is formed by immersing the end portion of the lead wire in a paste prepared by mixing 100 parts by weight of the igniting agent with 490 parts by weight of water and drying the paste to form a layer made of about 0.1 g of the igniting agent. did.
The second igniting agent layer was prepared by mixing 460 parts by weight of water with 100 parts by weight of the igniting agent mixed with the fibers to prepare a paste, and immersing the portion of the first igniting agent layer in the paste. The drying operation was repeated to form a layer of about 0.2 g.

Then, a coating 1 made of a resin composition containing a fibrous material is integrally formed on the surface of the igniting agent with the holder.
Formed 7. The coating 17 is made of polyvinyl acetate and the same ceramic fiber as described above. Here, the ratio of the fiber to the total amount of the resin component and the fiber is 5% by weight.
And When forming the coating, the spark plug before coating was immersed in a mixture of an aqueous solution containing 25% by weight of polyvinyl acetate and the fiber, then pulled up and dried at 50 ° C. for 12 hours.

Comparative Example 1 As shown in FIG. 3, the ignition layer 16 contains ceramic fibers and is made of the same material as the second ignition layer in Example 1.

Ten thermal batteries each of Example 1 and Comparative Example 1 were used.
0 pieces were produced and the operation test of the battery was implemented by the piezoelectric element. As a result, the number of batteries that did not operate because the spark plug did not ignite was 0 in Example 1, but three of the batteries of Comparative Example did not operate.

[0022]

According to the present invention, the heat provided with the igniting agent layer having the strength capable of retaining a sufficient amount of the igniting agent without forming the void portion which causes the misfire between the lead wire ends. A battery can be provided. Also, by coating the ignition layer with the resin coating along with the holding portion at the end of the lead wire, the strength of the ignition plug is further increased, and a thermal battery that can reliably perform ignition to the ignition sheet is provided. Can be provided.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a thermal battery according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the spark plug.

FIG. 3 is an enlarged cross-sectional view of a spark plug of a thermal battery of a comparative example.

[Explanation of symbols]

1 unit cell 2 exothermic agent 3 generator 4 ignition sheet 5 Spark plug 6 lead wire 7 Ignition device 8 insulation 9 Positive electrode lead 10 Negative electrode lead 11 holes 12 Lid 13 Piezoelectric element 14 Insulation case 15 Holder 16a First ignition layer 16b Second ignition layer 17 Resin coating 18 Void

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhiro Nishimura             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5H025 AA19 CC25 CC34 CC40 KK02                       KK07

Claims (3)

[Claims] 1. A power generator in which unit cells and a heating agent are alternately laminated, an ignition sheet for igniting the heating agent, and a piezoelectric element that is adjacent to the ignition sheet and is connected by a pair of lead wires. A thermal battery having a spark plug,
A holding body in which the spark plug holds the lead wire ends opposite to each other, a first ignition agent layer covering the lead wire ends, and a second ignition agent containing a fibrous material and covering the first ignition agent layer. A thermal battery comprising a layer. 2. The thermal battery according to claim 1, wherein the second igniter layer is integrally coated with the holder by a resin composition containing a fiber material. 3. The thermal battery according to claim 1, wherein the fiber material of the second ignition layer is glass fiber or ceramic fiber.