JPH054204Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an explosion-proof sealed battery. Sealed batteries generally require extremely high airtightness to prevent leakage of electrolyte and gas generated within the battery, as well as infiltration of outside air and moisture. For these reasons, it is preferable to make the case as strong as possible. On the other hand, for example, in the case of an alkaline storage battery, depending on the conditions of use, there is a real possibility that the gas pressure within the battery may rise abnormally during charging or overdischarging, leading to the battery eventually bursting.

Conventionally, the following methods have been used to prevent such explosions of batteries. Cylindrical closed type Ni−
Cd batteries use a safety valve that uses rubber or a spring, and some flat batteries use a V-shaped groove in the center of the disc-shaped end surface of the battery case as a safety valve. These safety valves operate when the internal pressure of the battery rises abnormally, making it a so-called explosion-proof sealed battery that safely releases gas to the outside.

However, the former method has the drawback of being complicated in structure and expensive, and the latter has the drawback that a hole can be made in the battery if the thin wall of the V-shaped groove in the center is accidentally spot-welded when attaching the lead piece, etc. Therefore, in the latter case, accurate positioning of the battery is required when spot welding, which is a factor in increasing production costs.

The present invention eliminates such drawbacks and provides a sealed battery with an excellent explosion-proof function using an extremely simple method, and the details thereof will be explained below.

In a cylindrical or flat sealed battery, when the pressure inside the battery increases, stress is most concentrated on the disc-shaped end face of the battery case. The present invention creates a safety valve by providing a notch so that the stress is more likely to be concentrated in the part where the stress is most concentrated.Furthermore, according to the present invention, there is no thin wall part in the center, so it can be used for lead piece spot work, etc. can be done more easily.

That is, in the present invention, an arcuate V-shaped groove is provided at the periphery of the disc-shaped end surface of the battery case, and the V-shaped groove has one end and is arranged linearly toward the center of the arc. By providing a combination of V-shaped grooves, when the internal pressure of the battery rises abnormally, cracks will form around the intersections of the V-shaped grooves, allowing gas to be safely discharged to the outside and preventing the battery case from bursting. It is something.

In addition, when a uniform force such as gas pressure is applied from inside as in a battery, destruction (abnormal deformation) occurs in the radial direction of the disk. In the present invention, a V-shaped groove is provided in the radial direction so as to intersect with the center of the arcuate groove, thereby making it easier to cause deformation in the radial direction.
This ensures that cracks occur at the intersections with the arcuate grooves.

In addition, as shown in FIG. 1 of the embodiment described below, when the safety valves are arranged at two points at the ends of a disc-shaped battery symmetrically with respect to the center point of the disc, and the reliability of the safety valve operation is increased by this multiple arrangement, If the radial V-shaped groove deviates from the radial direction, the balance of press pressure during marking will be lost, making it difficult to maintain processing accuracy.

The following will be described in detail based on examples.

Figure 1 shows the arrangement of the V-shaped grooves provided in the flat battery case of the present invention, which has a maximum outer diameter of 23.2 mm, a height of 5.6 mm, and a fabric thickness of metal case material of 0.3 mm. In the disc-shaped end face of the case, 2 is a side surface thereof, 3 is a V-shaped groove provided in an arc along the periphery of the end face, and 4 has one end in the center of the arc-shaped V-shaped groove 3; V arranged in a straight line towards the center
In the embodiment, two V-shaped grooves were provided symmetrically. Figure 2 shows a cross section of a battery case provided with a V-shaped groove according to the present invention, and the battery case and battery cover 5 are sealed by caulking through packing coated with sealant 6. .

In the sealed battery according to the present invention as described above, when the internal pressure of the battery increases abnormally, bending stress and shear stress are concentrated at the intersection of the arcuate and linear V-shaped grooves. Therefore, by setting the withstand voltage of this part lower than the withstand voltage of the battery sealing part, the internal pressure can be safely released before the battery explodes.

Figure 3 shows the results of investigating changes in safety valve operating pressure (pressure at which cracks occur, hereinafter the same) when the radius of the arcuate V-shaped groove was varied in ratio to the radius of the battery end face. show. In case A, the ratio of the depth of the V-shaped groove to the thickness of the case is 6/10, and in case B, it is 8/10.
The width of the curve indicates the variation in operation. From Figure 3, as the radius of the arcuate V-shaped groove becomes smaller,
It can be seen that the working pressure suddenly increases and the variation also increases. Therefore, it can be seen that the radius of the arcuate V-shaped groove is required to be 3/4 (15/20) or more of the radius of the battery end face.

The operating pressure of the safety valve of the present invention is thus influenced by the radial position of the arcuate V-shaped groove. In particular, the operating pressure becomes relatively large when the position is 3/4 or less from the center of the battery end disk. Considering variations here, safety valves are formed by stamping with protrusions of the same shape, but in reality, the positions of the stamps shift during processing, which causes variations in operating pressure. When this deviation occurs at a position below 3/4 where the working pressure becomes relatively large, the change in the working pressure due to the deviation also becomes large. On the other hand, in the area of 3/4 or more, as is clear from Fig. 3, the change in the working pressure is extremely small with respect to the change in the radial direction (horizontal axis), so there is variation in the working pressure due to positional deviation. There are also few.

Next, we investigated the change in operating pressure when the depth of the V-shaped groove was changed in proportion to the thickness of the fabric of the battery case, and the relationship shown in FIG. 4 was obtained. In addition,
C: The radius of the arcuate V-shaped groove is 1 of the radius of the battery end face.
For 6/20, D is for 18/20, and the width of the curve indicates the variation in operating pressure. It can be seen that as the depth of the V-shaped groove becomes shallower, the operating pressure becomes higher and the variation becomes very large. Also, although not shown in the figure, if the depth is deeper than 9/10, defects are likely to occur during groove machining, and the strength is also weakened, making it unsuitable for practical use. Therefore, it has been found that the most preferable depth of the V-shaped groove is 6/10 to 9/10 of the thickness of the case fabric.

In the examples, a flat sealed battery was described, but it goes without saying that the same effect can be obtained with a cylindrical battery. Further, although the effects of the present invention can be sufficiently obtained with one V-shaped groove, reliability is further improved if there are two or more V-shaped grooves. Further, in this embodiment, since there is no thin part at the center of the disc-shaped end surface, the lead pot work is very easy to perform.

As described above, the present invention has an arc-shaped V-shaped groove in the peripheral part of the disc-shaped end surface constituting the battery case, and a V-shaped groove having one end in the arc-shaped V-shaped groove and arranged linearly toward the center of the arc. The radius of the arcuate V-shaped groove is set to 3/4 of the radius of the battery end face.
The depth of the V-shaped groove should be 3/5 of the case thickness.
~9/10, it became possible to obtain an explosion-proof sealed battery that was easy to process, highly reliable, and easier to perform lead spot work. Further, the operating pressure for releasing gas to the outside can be arbitrarily changed by adjusting the radius of the arcuate V-shaped groove and the depth of the V-shaped groove, which has extremely great practical value.

It should be noted that if the arc portion is short, the operating pressure will be large and the variation will also be large. If it is too long, the strength of the battery case will decrease. Furthermore, if the length of the straight section is short, the operating pressure will be large and the variation will also be large, making control difficult. On the other hand, if it is too long, the strength of the case will be reduced and the space in the center will make it impossible to achieve the purpose of the present invention (securing the spot of the connecting piece, etc.).

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the arrangement of V-shaped grooves of a sealed battery according to the present invention, and FIG. 2 is a diagram showing a cross section of the battery case of the present invention. FIG. 3 is a diagram showing the relationship between the radius of the arcuate groove and the operating pressure, where A shows the case where the ratio of the groove depth to the case thickness is 6/10, and B shows the case where the ratio is 8/10.
Figure 4 is a diagram showing the relationship between the depth of the V-shaped groove and the operating pressure.
If 0, then D is 18/20. DESCRIPTION OF SYMBOLS 1... Disk-shaped end surface of the battery case, 2... Side surface of the battery case, 3... Arc-shaped V-shaped groove, 4...
Straight V-shaped groove, 5...battery cover, 6...packing.

Claims (1)

[Scope of utility model registration request] A groove with a V-shaped cross section is provided in an arc shape in the periphery of the disc-shaped end surface constituting the battery case, and one end is provided in the center of the arc-shaped V-shaped groove, and a straight line extends toward the center of the arc. A sealed battery having a combination of grooves arranged in a V-shaped cross section, the arc-shaped V
A seal characterized in that the radius of the V-shaped groove is 3/4 or more of the radius of the disc-shaped end face of the battery case, and the depth of the V-shaped groove is 3/5 to 9/10 of the thickness of the battery case. battery.