JPH042045A - Sealed type lead acid battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF APPLICATION OF INDUSTRY AND COLLECTION This invention relates to a check valve for a sealed lead-acid battery.

BACKGROUND OF THE INVENTION Conventionally, a cap-type check valve has been used in this type of sealed lead-acid battery, as shown in FIG. The role of the valve l is to exhaust the oxygen gas or hydrogen gas ordered during charging and to maintain airtightness.

The gas is exhausted at a valve operating pressure determined by the material, hardness, etc. of the rubber. In addition, maintaining airtightness depends on the degree of adhesion between the inner wall of the check valve and the cylindrical opening 4 that is the valve seat, as well as the gas or water vapor permeability of the rubber itself, but there is a limit to the smoothness that can be obtained by machining. Therefore, these gaps are actually sealed with silicone oil 3 or the like.

Problems to be Solved by the Invention In such a conventional structure, silicone oil deteriorates chloroprene rubber. In addition, a phenomenon in which chloroprene rubber and ABS resin adhered in the presence of sulfuric acid occurred.

Among them, an anti-aging agent is added to chloroprene rubber,
Considerations have been made to use neoprene rubber that has been treated with vulcanization, but even neoprene rubber is susceptible to silicone oil, which causes the plasticizer to escape, resulting in softening and cracking.

It is also desired to reduce the gas and water vapor permeability of rubber itself, and butyl rubber has been considered in place of chloroprene rubber.

The present invention solves these problems and is a check valve that has a highly reliable opening/closing function, has no sticking between the check valve and the opening of the battery tank, and is furthermore capable of preventing gas and water vapor from the valve opening. The object of the present invention is to provide a sealed lead-acid battery equipped with a check valve that allows less permeation.

Means for Solving the Problems In order to solve the problems, the present invention provides a sealed lead-acid battery equipped with a check valve having a cap-shaped valve body coated with a fluororesin and fluorinated on the inside in contact with the exhaust port. It provides: Among these, it is particularly preferable that the valve body has a coating thickness of fluororesin of 10 μm to 20 μm on average.

Function: With this configuration, the check valve's opening/closing function is highly reliable, there is no sticking between the check valve and the opening of the battery case, and the valve body is a sealed type with a check valve that allows less gas and water vapor to pass through. Storage batteries can be provided.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to FIGS. 1 to 4.

Example 1 A sealed lead-acid battery case having a portion with a single cell cylindrical opening 4 was prepared, and silicone oil 3 was applied to the cylindrical opening 4.
The inside of the cap-shaped valve body 1 made of chloroprene rubber was fluorinated with hydrogen fluoride, and the fluororesin polytetrafluoroethylene (Teflon) 2 was sprayed and baked at 60°C. Attach a stop valve. Then, we created a so-called empty battery tank with a hollow interior.
The container with holes drilled in the part that does not affect the function of the valve is called battery case A (Figure 1). The thickness of the fluororesin coating 2 of this check valve was 15 μm on average. In addition, as a conventional product, a battery case B is made by applying silicone oil 3 to the cylindrical opening 4 of the same static battery tank and attaching a cap-shaped valve body 1 made of chloroprene rubber. Also, I tried to install a valve body that was sprayed with Teflon directly on the inside of the cap-shaped valve body and baked at 60℃, but in that case, if the surface of the valve body was not fluorinated, the fluororesin would not stick and it would rub off. I found out that it can be removed with just one.

Send air through the holes in each of the containers A and B, and make sure that when pressurized, air flows through the valves and that the pressure does not exceed a certain level. This is called the opening pressure. Also, confirm that when the pressurization is stopped, the inflow of air stops at a certain pressure. This is called valve closing pressure. Thereafter, sulfuric acid with a specific gravity similar to that of the electrolytic solution was applied to the contact portion of the cap-shaped valve body and the cylindrical opening, and after being left at 60° C. for one week, a similar test was conducted to observe the opening and closing of the valve. In case B, the valve opening pressure was three times the initial value, but the second time it was equal to the initial value. This means that the resin of the battery case material and the rubber of the cap valve adhered to each other due to the sulfuric acid, making it impossible for the valve to open. Moreover, in case A, there was no difference from the initial stage.

Example 2 A static battery tank similar to that in Example 1 was prepared, and 10 mHg/se was applied to the inside of the battery tank by a compressor in an atmosphere of 60°C.
The cycle of applying pressure until the valve opens at speed c. and then leaving it for one hour was repeated, and the valve opening pressure and valve closing pressure were recorded. The results are shown in FIG.

With conventional products, the opening and closing valve pressure varies, and as time passes, the opening pressure increases and the closing pressure decreases. The reason for this is that the valve opening pressure increases, which means that more force is applied to the wall of the battery case, which causes the battery case to bulge and crack. In addition, the closing pressure of the valve gradually decreases until it is no longer sealed and a large amount of air enters the battery case, causing oxidation of the negative electrode plate. In the product of the present invention, the opening/closing valve pressure is stable each time, which is advantageous against bulging cracks in the battery case and oxidation of the negative electrode plate.

Example 3 2V 2. In OA h's so-called single-cell sealed lead-acid batteries, the area other than the upper part where the check valve is installed is sealed with epoxy resin approximately 10 mm thick to prevent water vapor from permeating through the walls of the battery case. A battery was prepared, silicone oil was applied to the opening, and a check valve similar to that described above was installed, and this battery was designated as battery A. Furthermore, as a conventional product, a battery B was equipped with a check valve of the same type made of chloroprene rubber.

After measuring the initial capacity of the two types of batteries, they were supplemented and charged to 60
The weight change and remaining capacity after storage at ℃ for 2 weeks were measured in the fourth column.
As shown in the figure. Battery A, which uses the check valve coated with the fluororesin of the present invention, loses about 1/3 less weight than Battery B, which uses a check valve made only of chloroprene rubber, and as a result, self-discharge is also reduced. It's getting less. These batteries have the same conditions except for the check valve, so the difference in weight is due to the difference in the check valve.

By coating with a fluororesin in this manner, it is possible to obtain a check valve that has the rebound resilience of chloroprene rubber and takes advantage of the oil resistance, acid resistance, and low water permeability of the fluororesin.

If the average thickness of the fluororesin coating is less than 10 μm, there will be large variations and it will be difficult to fix the lower limit portions.

On the other hand, if it exceeds 20 μm, it will affect the elasticity of the chloroprene rubber, making it impossible to stabilize the opening/closing valve pressure.

Effects of the Invention As described above, according to the present invention, it is possible to provide a sealed silver # battery in which the opening/closing valve pressure of the check valve is stable, there is little water vapor permeation, and there is little self-discharge.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a check valve coated with fluororesin according to the present invention installed in an opening, Figure 2 is a cross-sectional view of a conventional check valve made of chloroprene rubber installed in an opening, and Figure 3 is a cross-sectional view of a conventional check valve made of chloroprene rubber installed in an opening. The figure shows the change in on-off valve pressure at 60℃ when using a static tank.
FIG. 3 is a diagram showing storage characteristics when stored at 0° C. for 2 weeks. 1... Chloroprene rubber. 2...Fluororesin, 3...Silicone oil, 4...
・Battery opening. Name of agent: Patent attorney Shigetaka Awano

Claims (2)

[Claims] (1) A check valve is composed of a cylindrical opening provided in a battery case made of ABS resin and a cap-shaped valve body combined with the cylindrical opening, and the inside of the cap-shaped valve body in contact with the cylindrical opening is made of fluorine. A sealed lead-acid battery characterized by being coated with fluororesin. (2) The average thickness of the fluororesin coating is 10μ
2. The sealed lead-acid battery according to claim 1, wherein the thickness is 20 [mu]m to 20 [mu]m.