JPH041642Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a safety valve for a sealed lead-acid battery, particularly a thin sealed lead-acid battery.

Conventional technology As shown in Fig. 2, the safety valve conventionally used in sealed lead-acid batteries consists of a cap-shaped rubber valve 6 that covers the exhaust port of a cylindrical valve tube 7 provided in the battery case. I am using it. This structure is a safety valve that utilizes the elasticity of rubber. When the internal pressure of the battery rises and exceeds the elasticity of the rubber, the gas inside the battery is released, and when the internal pressure decreases, the elasticity of the rubber is overcome. It is designed to block the exhaust port.

Problems to be solved by the invention In the safety valve structure using the above rubber valve 6,
In order to make the battery thinner, it is necessary to provide a valve cylinder 7 into which the rubber valve 6 is fitted, and there are limits to the manufacturing accuracy of the valve cylinder 7 and the accuracy of manufacturing the rubber valve 6. Thin batteries have great difficulties. To address this drawback, a safety valve has been proposed in which an unwelded portion is left in the battery case material film 1a that encloses the electrode plate group, and silicone oil 4 is poured into that portion, as shown in FIG. Showa 59-207558
Publication No.). This structure allows the battery to be made thinner and is an effective means. However, with this structure, only the heat welded part 3 of the battery case material film 1a,
In other words, the valve can only be provided on the outer periphery of the battery, and the installation position of the valve is not flexible. Furthermore, since the portion into which the silicone oil 4 is placed, that is, the valve portion, is the outer periphery of the electrode plate group, the valve extends in the vertical or horizontal direction of the battery, reducing the energy density of the battery.

Means for Solving the Problems To address the above problems, the safety valve for sealed lead-acid batteries of the present invention has a hole partially formed in the film surrounding the electrode plate group, and a separate hole that can be heat welded to the film on the top surface. A safety valve is formed by heat welding a small piece of film, leaving one or more places, and by infiltrating oil between the film and the small piece of film.

How it works Because the film that wraps around the electrode plates has a hole in it, the hole can be placed at any position on the flat surface of the battery, and a small piece of film is heat welded on top of it, allowing oil to infiltrate. It forms an oil seal between the film and the small piece of film, and is highly effective as a safety valve. Furthermore, since the valve is provided on the film above the electrode plate group, there is no need to make the battery case wider for the valve, and the energy density of the battery is not reduced. Of course, it is fully applicable to batteries with a thickness of 5 mm or less.

Example An embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the safety valve of the present invention and a battery using it. In a battery in which a group of electrode plates is wrapped in a laminated or single-layer film 1, a hole 5 is made in a part of the film 1, and a small piece of heat-weldable film 2 is fixed on the top surface by heat-welding 3'. Silicone oil 4 is infiltrated between the small pieces of film 2 and film 1. In this example, a 50 x 50 x 4 mm electrode plate group was wrapped in a three-layer film 1 of polypropylene-aluminum-polypropylene and a 2φ hole 5 was punched approximately in the center of the battery. On top of that, polypropylene 12.5 x 7 mm x 0.05
A small single-layer film 2 having a diameter of 2 mm was fixed by heat welding, and silicone oil 4 was infiltrated. As a result of checking the valve operating pressure with this safety valve, it was 50mmHg/min.
Valve operation was confirmed at a pressure increase rate of 15 mmHg. We also conducted pressurization and depressurization cycle tests at the same time.
Stable working pressure was maintained for over 2000 cycles.

Effects of the invention As mentioned above, this invention has a hole in a part of the film that wraps the electrode plate group, a small piece of film fixed by heat welding on the top surface, and an oil seal between the film and the small piece of film, making it thin. In a sealed lead-acid battery, the valve function can be sufficiently performed even if the thickness is 5 mm or less, and the valve can be installed anywhere, even in the center of the battery, and can be shaped without waste in relation to the external shape of the battery. Furthermore, the method of preparation is simple and the valve operating pressure is reliable, so it has great practical value.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
This figure and FIG. 3 are perspective views of essential parts showing a conventional example. 1 is a laminate or single layer film, 2 is a small piece of film, 3 and 3' are heat welded parts, 4 is silicone oil, and 5 is a hole.

Claims (1)

[Scope of utility model registration request] In the safety valve of a sealed lead-acid battery, where the electrode plates are wrapped in a laminated film or a single-layer film, a hole is made in a part of the film, and a small piece of film that can be heat-welded to the film is left in one or more places and heat-welded on the top surface. A safety valve for sealed lead-acid batteries with oil infiltrated between the film and the small piece of film.