JPH02119048A - Sealed lead-acid battery - Google Patents

Abstract

PURPOSE:To obtain a sealed lead-acid battery with reasonable cost and higher reliability by installing a safety valve made of ethylene-propylene rubber into a valve cylinder made of propylene resin. CONSTITUTION:If propylene resin is selected as the resin material for a valve cylinder, ethylene-propylene rubber among such as, SBR, NBR, ethylene- propylene rubber and isoprene rubber is employed as a safety valve in view of chemical resistance, thermal resistance and high reliability. Accordingly, the interface between the valve cylinder and the safety valve is not decomposited and not stuck thereto, so that constant valve opening-pressure is always obtained. The cost for per unit weight of the ethylene-propylene rubber is almost the same as proloprene rubber, however, specific gravity of the former is smaller than the latter. Therefore, material cost for producing the safety valve of constant volume is cheaper when the ethylene-propylene rubber is used.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sealed lead-acid battery having an improved safety valve section.

BACKGROUND ART Conventionally, the safety valve section of a sealed lead acid battery has been constructed such that a safety valve made of chloroprene rubber is attached to a safety valve cylinder made of embryonic resin or polypropylene resin.

Problems to be Solved by the Invention In general, safety valves in sealed lead-acid batteries open when the internal pressure rises due to gas generation due to water electrolysis, and then close once gas is released and oxygen gas is absorbed into the cathode plate. When the valve is closed and the pressure is reduced, a characteristic (depressurization compensation characteristic) is required in which the valve is closed to prevent the inflow of outside air.

However, in conventional sealed lead-acid batteries, high temperatures (4
When used for a long period of time at temperatures above 0°C, sticking occurs at the interface between the safety valve and the valve cylinder, causing the problem that the valve opening pressure becomes abnormally large. The cause of this is that the sulfuric acid that has entered the contact surface between the safety valve and the valve barrel alters the quality of the interface between the two.

In order to solve this problem, ``a safety valve made of fluorosilicone rubber, fluororubber, or a mixture thereof, was used with a battery case and lid made of polypropylene resin.''
A method has been proposed in which the valve is attached to the valve barrel provided on the lid.

Shikashi, fluorosilicone rubber, fluororubber, and mixtures thereof are about 2 to 4 times more expensive than conventional safety valve materials, and are problematic because they increase the cost of batteries.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a safety valve section for a sealed lead-acid battery that is inexpensive and highly reliable.

Means for Solving the Problem A safety valve part that is highly reliable for long-term use at high temperatures requires safety valve materials and valve barrel materials that have good chemical resistance and heat resistance.

Therefore, from the aspects of chemical resistance, heat resistance, and price.

When polypropylene resin is selected as the valve barrel material resin, the safety valve material is 5BR1NBR from the above-mentioned viewpoint and from the viewpoint of high reliability.

Among ethylene/propylene rubber, isogrene rubber, etc.
It has been found that ethylene φ propylene rubber is the best.

Function By doing so, the interface between the valve barrel and the safety valve does not change in quality even when used at high temperatures for a long period of time, and stickiness does not occur, so that a constant valve opening pressure can be maintained at all times.

In addition, the price per unit weight of ethylene O globylene rubber is almost the same as the price per unit weight of conventional chloroprene rubber, but the specific gravity of ethylene propylene rubber is smaller, so it can be used to create a safety valve with a fixed volume. In this case, the material cost can be reduced by using ethylene/propylene rubber. In addition, it is reduced by about half compared to fluororubber and fluorosilicone rubber.

EXAMPLE In the safety valve part shown in FIG. 1, in which the safety valve 1 was attached to the valve barrel 2, evaluation was performed using a sealed lead-acid battery in which the safety valve 1 and the valve barrel 2 were made of different materials. Evaluation is 060℃, 2
A comparison was made between the valve opening pressure after being left for a week and the initial valve opening pressure, and (2) a comparison of the price of safety valves, and the results are shown in Table 1.

More T4 white Table 1 1 is a safety valve, 2 is a valve cylinder.

Claims (1)

[Claims] 1. A sealed lead-acid battery having a safety valve cylinder made of polypropylene resin, characterized in that a safety valve made of ethylene-propylene rubber is attached to the valve cylinder.