JP4417703B2 - Thermal battery - Google Patents

Description

  The present invention relates to a thermal battery, and more particularly to a spark plug thereof.

The structure of a conventional thermal battery will be described with reference to FIG. FIG. 1 is a schematic perspective view in which a part of a general thermal battery is cut away.
A power generation body in which unit cells 7 composed of a positive electrode layer, a negative electrode layer, and an electrolyte layer and heat generating agents 5 are alternately stacked is housed in a metal outer case 1. An ignition pad 4 is arranged on the uppermost part of the power generator, and a spark plug 3 is installed in the vicinity of the upper part of the ignition pad 4. A heat conduction zone 6 is arranged around the power generation body, and a heat insulating material 9 is filled between the outer case 1 and the power generation body.

The outer case 1 is sealed by a battery lid 10 having a pair of ignition terminals 2 and positive and negative terminals. The pair of ignition terminals 2 is connected to a pair of lead wires.
Moreover, the positive electrode terminal is connected to the positive electrode layer of the unit cell 7 at the top of the power generator via a positive electrode lead plate. On the other hand, the negative electrode terminal is connected to the negative electrode layer of the unit cell 7 at the lowest part of the power generator via the negative electrode lead plate 8.

  When a current is applied to the ignition terminal 2 from a power source connected to the ignition terminal 2, the spark plug 3 is ignited. As a result, the combustion is propagated to the ignition pad 4 and the igniting zone 6, the exothermic agent 5 is combusted, and the unit cell 7 is heated. And the electrolyte layer containing the molten salt which comprises the unit cell 7 fuse | melts, and becomes an ionic conductor. As a result, the battery is activated and can be discharged.

Here, FIG. 2 shows a schematic longitudinal sectional view of an example of the spark plug 3.
The spark plug 3 includes a ceramic holding body 14 that holds a pair of lead wires 13, an electric bridge wire 12 that connects the tip ends of the pair of lead wires 13, an ignition agent 11 that covers the electric bridge wire 12, a holding body 14, and It consists of a cylindrical member 15 that houses the ignition powder 11.
Further, the cylindrical member 15 is accommodated by the case 16 having openings at the upper and lower portions. The lead wire 13 passes through the upper opening, and the lower opening is closed with a metal plate 18 from the inside so that the ignition agent 11 does not go outside. During ignition, combustion propagates from the lower opening to the ignition pad 4.

  Here, if the sensitivity of the spark plug 3 is too good, the thermal battery may malfunction when a current smaller than the ignition current is applied. On the other hand, there is a demand for the development of a thermal battery that completely prevents ignition of the spark plug 3 and does not cause malfunction under non-ignition conditions in which a current less than a predetermined ignition current flows.

For example, Patent Document 1 discloses that a resistive heating element is provided between a pair of lead wires to guarantee a non-ignition current of 400 mA (a current that does not reliably operate the battery).
However, depending on the contact state between the spark plug holder and the cylindrical member, the spark plug's heat dissipation varies, and the spark plug ignites under the non-firing condition in which a current of 1A is applied for 5 minutes. The battery may malfunction.
JP 2000-241099 A

  Therefore, in order to solve the above problem, the present invention improves the contact state between the holder and the cylindrical member in the spark plug, and improves the thermal conductivity from the holder to the cylindrical member. An object of the present invention is to provide a highly reliable thermal battery that does not malfunction even when a current less than a predetermined ignition current flows.

The thermal battery of the present invention is a thermal battery comprising a power generation body in which unit cells and a heat generating agent are alternately laminated, an ignition pad disposed on the power generation body, and an ignition plug for igniting the ignition pad. The ignition plug accommodates the holding body that holds the pair of lead wires, the electric bridge wire that connects the tip ends of the pair of lead wires, the ignition agent that covers the electric bridge wire, and the holding body and the ignition agent. It is made of a cylindrical member, and an adhesive layer having a thermal conductivity of 10 to 60 W / m · deg is formed between the holding body and the cylindrical member.
It is preferable that the adhesive layer is formed of a thermally conductive adhesive made of an epoxy resin containing silver powder.
The cylindrical member is preferably made of metal.

  According to the present invention, the contact state between the holder and the cylindrical member in the ignition plug of the thermal battery can be improved, and the thermal conductivity from the holder to the cylindrical member can be improved, and less than a predetermined ignition current. It is possible to provide a highly reliable thermal battery that does not cause a malfunction even when the current flows.

An embodiment of the spark plug 3 in the thermal battery of the present invention will be described with reference to FIG. FIG. 3 is a schematic longitudinal sectional view of a spark plug in the thermal battery of the present invention.
The spark plug 3 includes a holding body 14 that holds a pair of lead wires 13, an electric bridge wire 12 that connects tips of the pair of lead wires 13, an ignition agent 11 that covers the electric bridge wire 12, and a holding body 14 and an ignition agent. It consists of a cylindrical member 15 that houses and holds 11.
An adhesive layer 17 having thermal conductivity is formed between the holding body 14 and the cylindrical member 15. The adhesive layer 17 improves the adhesion between the holding body 14 and the cylindrical member 15 and improves the thermal conductivity from the holding body 14 to the cylindrical member 15. For this reason, it is possible to reliably prevent malfunction of the thermal battery that occurs below the ignition current.

The adhesive layer 17 is preferably formed using a heat conductive adhesive made of an epoxy resin containing silver powder. An adhesive layer 17 having excellent adhesion between the holding body 14 and the cylindrical member 15 and thermal conductivity from the holding body 14 to the cylindrical member 15 is obtained.
As this heat conductive adhesive, for example, an adhesive obtained by dispersing 88 to 93% by weight of silver powder as a heat transfer material in a solution obtained by dissolving an epoxy resin in a solvent such as isopropyl alcohol or glycol ether is used. Can do.

  The adhesive layer 17 is obtained by uniformly applying the above-described heat conductive adhesive to the circumferential portion of the side surface of the holding body 14 and inserting it into the cylindrical member 15 and then curing the adhesive under predetermined conditions. . At this time, the obtained adhesive layer 17 is in a state in which silver powder is almost uniformly dispersed in the epoxy resin.

The thermal conductivity of the adhesive layer 17 is preferably 10 W / m · deg or more.
The heat generated in the bridge 12 is transferred to the holding body 14 and transferred to the cylindrical member 15 and the case 16 via the adhesive layer 17. Therefore, the heat transfer from the holding body 14 increases as the thermal conductivity of the adhesive layer 17 increases. That is, as the thermal conductivity of the adhesive layer 17 increases, the temperature rise of the bridge 12 is suppressed.
When the thermal conductivity of the adhesive layer 17 is 10 W / m · deg or higher, the thermal conductivity of the holding body 14 made of glass is 10 W / m · deg or lower. Can be suppressed.
What is necessary is just to use the conventionally used thing for the igniting agent 11.

Furthermore, the cylindrical member 15 is accommodated in a case 16 having openings at the upper and lower portions. The lead wire 13 passes through the upper opening 16a, and the lower opening 16b is blocked by a metal plate 18 from the inside to prevent the ignition powder 11 from going out and to prevent moisture.
The cylindrical member 15 and the case 16 are preferably made of metal such as stainless steel because they have excellent heat dissipation and high heat capacity.

The thermal battery using the above spark plug includes a power generation body in which unit cells and a heat generating agent are alternately laminated, an ignition pad disposed on the top of the power generation body, a heat conduction belt that covers a side portion of the power generation body, and the like. Constituent members are provided, but these members may be those conventionally used.
The adhesive layer having thermal conductivity may be other than an epoxy resin in which silver powder is dispersed, and other materials may be used as long as they have thermal conductivity and heat dissipation.
Examples of the present invention will be described in detail below.

Example 1
A spark plug having the same structure as that of FIG. 3 was produced as follows.
An electric bridge wire 12 made of nichrome wire and a lead wire 13 made of Fe—Ni—Co alloy (Kovar) (weight ratio Fe: Ni: Co = 54: 29: 17) drawn from a ceramic holder 14. Welded the tip of the. A cylindrical member 15 made of stainless steel was disposed outside the holding body 14. At this time, an adhesive layer 17 was formed between the holder 14 and the cylindrical member 15 using a heat conductive adhesive.

  As the heat conductive adhesive, DM6030HK (thermal conductivity 30 to 60 W / m · deg) manufactured by Diamat was used. This was applied to the circumferential portion of the side surface of the holding body 14 with a thickness of about 0.2 to 0.4 mm, and inserted into the cylindrical member 15. Thereafter, the lead wire side was held at 110 ° C. for 60 minutes, and then the adhesive was cured in a dryer at 205 ° C. for 30 minutes to obtain an adhesive layer 17.

  And the ignition powder 11 was filled so that the bridge line 12 might be covered, and the spark plug main body was obtained. The ignition agent 11 is a mixture of boron, potassium perchlorate, barium nitrate, and a copolymer of vinylidene fluoride and propylene hexafluoride as a binder in a weight ratio of 40: 30: 24: 6. Was used. After filling the igniting agent 11, the spark plug body was inserted into a case 16 made of aluminum, and the upper end portion of the case 16 was bent inward to fix the cylindrical member 15 to the case 16. At this time, a metal plate 18 made of aluminum was disposed inside the case 16 so as to close the opening 16 b of the case 16.

Using the spark plug shown in FIG. 3 obtained above, a thermal battery having the same structure as in FIG. 1 was produced.
As the power generation body, one in which a plurality of unit cells 7 and heat generating agents 5 are alternately stacked is used, and the power generation body is arranged so that the opening 16b of the spark plug 3 faces the upper portion of the power generation body. At this time, 16 unit cells were used. In the positive electrode layer, a component mainly composed of FeS ₂ was used as an active material. In the negative electrode layer, a component mainly composed of lithium was used as an active material. For the electrolyte layer, a mixture of Li—KCl eutectic salt and MgO as a retaining agent was used. As the exothermic agent 5, a mixture of iron powder and potassium perchlorate was used. A mixture of zirconium and barium chromate was used for the ignition pad 4 and the conduction zone 6.

<< Comparative Example 1 >>
A thermal battery was fabricated in the same manner as in Example 1 except that an ignition plug as shown in FIG. 2 was used instead of the ignition plug of Example 1. FIG. 2 is a schematic longitudinal sectional view of the spark plug, which is the same as FIG. 3 except that the adhesive layer 17 is not formed between the cylindrical member 15 and the holding body 14.
The thermal battery of Example 1 and Comparative Example 1 obtained above was evaluated as follows.

[Evaluation]
For each of the 40 batteries of Example 1 and Comparative Example 1, a predetermined power source was connected between the ignition terminals, and a current of 4.8 A was applied for 20 ms as an ignition condition. At this time, the ratio of the batteries that were ignited and activated by the spark plug was examined. The results are shown in Table 1.

As a result, in all cases of Example 1 and Comparative Example 1, all the batteries were activated.
Further, for each of the 40 batteries of Example 1 and Comparative Example 1, a power source was connected between the ignition terminals, and currents of 1.0 A, 1.25 A, and 1.5 A were applied for 5 minutes as non-firing conditions. did. At this time, the percentage of batteries that ignited and activated the spark plug and caused malfunction was examined. The results are shown in Table 2.

In Comparative Example 1, there was a battery that malfunctioned under any condition, but in Example 1, there was no battery that malfunctioned under any condition.
From the above, it was found that the thermal battery of Example 1 of the present invention operates reliably under ignition conditions and does not malfunction under non-ignition conditions, and thus has high reliability.

  As described above, the thermal battery of the present invention has an ignition plug with excellent thermal conductivity from a holding body that holds a pair of lead wires to a cylindrical member that houses the holding body. It can be applied to equipment power supplies, emergency power supplies, and the like.

It is the schematic perspective view which notched a part of common thermal battery. It is a schematic longitudinal cross-sectional view of the conventional ignition plug. It is a schematic longitudinal cross-sectional view of the ignition plug of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exterior case 2 Ignition terminal 3 Spark plug 4 Ignition pad 5 Heating agent 6 Heating zone 7 Unit cell 8 Negative electrode lead board 9 Heat insulating material 10 Battery cover 11 Igniting agent 12 Electric bridge wire 13 Lead wire 14 Holder 15 Cylindrical member 16 Case 16a, 16b Opening 17 Adhesive layer 18 Metal plate

Claims (3)

A thermal battery comprising a power generator in which unit cells and a heat generating agent are alternately laminated, an ignition pad disposed on an upper portion of the power generator, and an ignition plug for igniting the ignition pad,
The ignition plug has a holding body that holds a pair of lead wires, an electric bridge wire that connects the tip ends of the pair of lead wires, an ignition agent that covers the electric bridge wire, and a cylinder that houses the holding body and the ignition agent It consists of a member
A thermal battery , wherein an adhesive layer having a thermal conductivity of 10 to 60 W / m · deg is formed between the holding body and the cylindrical member.   The thermal battery according to claim 1, wherein the adhesive layer is formed of a heat conductive adhesive made of an epoxy resin containing silver powder.   The thermal battery according to claim 1, wherein the cylindrical member is made of metal.

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