JPH0945303A - Explosion-proof gasket of alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an explosion-proof gasket of an alkaline battery which is excellent in explosion-proof operability by arranging an annular groove part in another position of a battery outside surface besides an annular groove part arranged on a battery inside surface of a plate part of the explosion-proof gasket, and constituting bottom wall parts of the respective groove sparts out of thin parts. SOLUTION: In an explosion-proof gasket 11 of an alkaline battery, an outside annular groove part 11c is arranged in a position different from a pressure receiving side annular groove part 11a on the outside of the battery on the opposite side of a pressure receiving surface separately from a conventional pressure receiving side annular groove 11a arranged on a battery inside surface of its plate part 11b. At this time, corner thick parts composed of recessed curved surfaces having a radius of 0.01mm, 0.02mm and 0.05mm are respectively arranged in corner parts of the groove parts 11a and 11c, and a thickness of the plane part 11b is set in 0.6mm, and a thickness of thin parts of bottom wall parts of the groove parts 11a and 11c is set in 0.3mm. Therefore, an explosion-proof gasket excellent in explosion-proof operability is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an explosion-proof gasket for an alkaline battery that breaks and releases gas safely when the battery internal pressure rises abnormally.

[0002]

2. Description of the Related Art FIG. 3 is a front view showing a cross section of a part of a conventional alkaline dry battery. In a battery case 8 made of iron, which also serves as a positive electrode terminal, a plurality of positive electrode mixtures 6 having manganese dioxide and graphite as main constituent materials and formed into a short cylindrical shape are inserted. The gel negative electrode 5 is injected inside the positive electrode mixture 6 via the separator 7. Gel negative electrode 5
The negative electrode current collector 2 is inserted therein. Generally, the gasket 1 is made of plastic or rubber and has a bottom plate 3,
In combination with the current collector 2 and the like, the structure is such that the opening of the battery case 8 is sealed. 4 is a washer, 9 is an outer label, 1
0 is an insulating cap.

The gasket 1 receives battery internal pressure from its upper side. By providing the annular groove portion 1a on the pressure receiving side of the flat plate portion 1b of the gasket 1, the bottom wall portion thereof has a thin wall portion. Then, when gas is generated and the battery internal pressure rises, when the battery internal pressure reaches a certain pressure, the thin-walled portion of the bottom wall of the groove 1a is ruptured and acts as an explosion-proof mechanism for discharging the gas inside the battery (for example, JP-A-59-139549). Generally, the gasket 1 is formed by, for example, an injection molding method in which a molten thermoplastic resin is fed into a mold.

[0004]

However, when the groove is formed by such a molding method, there is a problem from the viewpoint of molding technology or mold processing accuracy, and the thin wall formed by the groove bottom wall is formed. The wall thickness of the part is 0.3-0.
5 mm is the minimum limit, and it is difficult to make it thinner than that. Further, the thickness of the thin portion thus formed has a large variation. Therefore, in order to secure the safety of the explosion-proof mechanism and the reliability such as operation stability, it is necessary to examine the shape and perform fine dimension control. Therefore, by disposing the annular groove portion on the gas pressure receiving surface side at the time of explosion-proof operation, the breaking pressure of the thin-walled portion of the gasket is lowered and the breaking is facilitated. However, when the annular groove is arranged on the gas pressure receiving surface side, when the gas pressure inside the battery rises after the battery reaction proceeds, the gel negative electrode, which is the battery negative electrode active material, expands in volume and enters the gasket groove to solidify. By doing so, stable explosion-proof operation cannot be obtained, and there is a problem that the battery bursts or the cap portion breaks in some cases.

The present invention solves the above problems and provides an explosion-proof gasket that operates reliably when the gas pressure inside the battery rises after the battery reaction has proceeded.

[0006]

An explosion-proof gasket for an alkaline battery according to the present invention is an explosion-proof gasket for sealing an opening of a case of an alkaline battery, wherein an annular groove portion disposed on a battery inner surface of a flat plate portion, and By providing a thin portion formed by each bottom wall portion of the groove portion arranged at a position different from the groove portion on the outer surface of the battery, the gelled negative electrode enters the groove portion of the gasket arranged inside the battery and solidifies. Even in such a case, the operation is stable. Further, the bottom corner portion of the groove on the outer surface of the battery is curved with a radius of 0.02 mm or less, or is chamfered with a side of 0.02 mm or less, so that stress concentration when the internal pressure of the battery rises It enhances the notch effect and reduces the breaking pressure of the explosion-proof gasket.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] As shown in FIG.
In addition to the conventional annular groove 11a on the pressure receiving side provided on the surface (pressure receiving surface) that receives the internal pressure of the battery, the annular groove 1c is provided on the opposite side of the pressure receiving surface, that is, on the outside of the battery. In Examples 1A, 1B and 1C, the groove portion 1 of the gasket 11 is used.
1a and 11c with curved corners at the bottom corners having a radius of 0.01 mm, 0.02 mm and 0.05 mm, that is, grooves 11a and 11c
0.01mm and 0.0mm at the bottom corners of the
A fillet portion having concave curved surfaces of 2 mm and 0.05 mm is provided. Here, the thickness of the flat plate portion 11b is 0.6
mm, and the thickness of the thin portion formed by the bottom wall portions of the groove portions 11a and 11c was both 0.3 mm.

[Embodiment 2] As shown in FIG. 2, a gasket 21 having a radial groove portion 21d on the outside of the battery was prepared in addition to the conventional pressure receiving side annular groove portion 21a provided on the pressure receiving surface. In Examples 2A, 2B and 2C, the corner portions of the bottom wall surfaces of the groove portions 21a and 21d of the gasket 21 are curved surfaces having radii of 0.01 mm, 0.02 mm and 0.05 mm, respectively. here,
The thickness of the flat plate portion 21b was 0.6 mm, and the thickness of the thin portion formed by the bottom wall portions of the groove portions 21a and 21c was both 0.3 mm.

[Comparative Example] As Comparative Examples 1 to 3, a gasket 1 as shown in FIG. 3 was used. These are obtained by subjecting the bottom corners of the groove 1a of the gasket 1 to curved surfaces having radii of 0.01 mm, 0.02 mm and 0.05 mm, respectively. Here, the flat plate portion 1b has a thickness of 0.6 mm, and the thin portion formed by the bottom wall portion of the groove portion 1a has a thickness of 0.3 mm.

The molds used for these moldings are precisely manufactured by cutting a predetermined shape with a lathe or the like and polishing it with a grinding stone with finer abrasive grains than the 180th count, A gasket was molded using these molds.

With respect to the alkaline battery (LR-6) produced by using the above-mentioned gasket, the breaking pressure of the gasket groove portion due to filling with nitrogen gas was measured. Also,
An explosion-proof mounting test (1 out of 4 reverse connection) was carried out on the initial battery and the battery after discharging (1Ω-50 hours). 30 of each of these batteries were measured. The results are shown in Table 1, Table 2 and Table 3, respectively.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

As shown in Tables 1 to 3, in the measurement of the breaking pressure of the thin portion, the smaller the radius of the curved surface formed at the corner of the bottom of the groove is, the better the result is obtained, particularly when the radius is 0.02 mm or less. The explosion-proof safety of the initial battery was confirmed. Further, regarding the explosion-proof mounting test of the battery after discharge, it is good for the batteries using the gaskets of Examples 1 and 2 each having a groove portion on the side opposite to the pressure receiving surface at the time of operating the explosion-proof mechanism, apart from the groove portion of the conventional gasket. I got the result.

In the above embodiment, the thickness (thickness of thin portion / thickness of flat plate portion) of the gasket is set to 0.5, but the same effect can be obtained by further reducing this value. As the thickness of the thin portion is smaller than the thickness of the flat plate portion, stress is more likely to concentrate on the thin portion, and a stable breaking pressure can be obtained. Therefore, (thickness of thin portion / thickness of flat plate portion) is preferably 0.5 or less. In addition, in the above-mentioned embodiment, the gasket having the curved bottom corners was examined. However, the bottom corner of the groove was chamfered with 0.02 mm or less on each side, that is, the corners of the groove were 0. 02 mm
Similar results were obtained in the case of using a gasket having a fillet portion having a flat surface cut out below.

The gasket of the present invention has an explosion-proof structure in which a gas pressure receiving surface of the flat plate portion and a groove portion are provided on the surface opposite to the gas pressure receiving surface. Even if the gel negative electrode that has flowed into the groove on the pressure receiving surface side is blocked and the explosion-proof mechanism of the groove on the gas pressure receiving surface side is damaged, the thin portion formed by the groove located on the surface opposite to the gas pressure receiving surface is activated. Can be made. In addition, the thin part that becomes the starting point at the time of breakage due to gas generation inside the battery regulates the size of the fillet at the corner of the bottom of the groove to increase the likelihood of cracking at the starting part (notch effect). , Even if the thickness of the thin part is set to the same, the breaking pressure of the thin part due to the gas internal pressure is reduced,
Moreover, a stable explosion-proof structure with little variation was obtained.

[0018]

According to the present invention, it is possible to provide an explosion-proof gasket for an alkaline battery which is excellent in explosion-proof operation.

[Brief description of drawings]

FIG. 1 shows a gasket according to an embodiment of the present invention, (a) is a partially sectional front view, and (b) is a bottom view.

FIG. 2 shows a gasket according to another embodiment of the present invention, (a) is a partial cross-sectional front view, and (b) is a sectional view.
Is a bottom view.

FIG. 3 is a front view showing a cross section of a part of an alkaline battery using a conventional gasket.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gasket 1a Pressure receiving side annular groove part 1b Flat plate part 2 Negative electrode collector 3 Bottom plate 4 Washer 5 Gel negative electrode 6 Positive electrode mixture 7 Separator 8 Battery case 9 Exterior label 10 Insulation cap 11 Gasket 11a Pressure receiving side annular groove part 11b Flat plate part 11c Outer annular part Groove portion 21 Gasket 21a Pressure receiving side annular groove portion 21b Flat plate portion 21d Outer radial groove portion

Claims (2)

[Claims] 1. An explosion-proof gasket for sealing an opening of a case of an alkaline battery, wherein the flat groove is provided at a position different from an annular groove provided on an inner surface of the battery and an outer groove provided on an outer surface of the battery. An explosion-proof gasket for an alkaline battery, which has a thin portion constituted by each bottom wall portion of the groove portion. 2. The bottom corner of the groove on the outer surface of the battery is curved to have a radius of 0.02 mm or less,
Alternatively, the explosion-proof gasket for an alkaline battery according to claim 1, which is chamfered with a side of 0.02 mm or less.