JP2647974B2 - Sealed battery safety valve device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an explosion-proof safety valve device for a sealed battery that responds to a pressure increase due to gas generation inside the battery.

[Related Art] As batteries used in portable electric devices and the like, secondary batteries typified by nickel-cadmium batteries, nickel-zinc batteries and the like, and primary batteries typified by alkaline batteries and lithium batteries are known. .

In the case of a secondary battery, an abnormal gas is generated inside the battery due to overcharging, and in the case of a primary battery, an abnormal gas is generated inside the battery due to erroneous charging or overdischarging. When the gas is generated as described above, the pressure inside the battery also increases, and there is a possibility that a burst accident such as blowing off the sealing lid may occur.

Therefore, this type of battery is provided with an explosion-proof safety valve device that discharges gas inside the battery in response to a pressure increase due to gas generation inside the battery.

This safety valve device is preferably a return type that opens when the gas pressure in the battery reaches a predetermined value or more and releases gas to the outside, and thereafter returns the inside of the battery to a sealed state again. As shown in FIGS. 3A and 3B, the sealing plate 1
A gas exhaust hole 1a is provided in the vicinity of the center of the terminal plate. A terminal plate containing an elastic valve body 2 obtained by compression molding synthetic rubber or the like is provided on the sealing plate 1 including the exhaust hole 1a. A plate-shaped valve lid 3 also serving as a valve is mounted so as to press-close the exhaust hole 1a with the elastic valve body 2, and the peripheral flange of the valve lid 3 is fixed to the sealing plate 1 by spot welding. There are many things.

In this safety valve device, when gas is generated in the battery for some reason and the internal pressure rises abnormally, the gas pressure pushes up the elastic valve body 2 to discharge gas from the gap between the sealing plate 1 and the gas. Gas is released to the outside through a gap of spot welding between the sealing plate 1 and the valve lid 3 to prevent damage and rupture of the battery.

[Problem to be Solved by the Invention] The hole diameter of the exhaust hole 1a provided in the sealing plate, the shape and structure of the elastic valve body 2, and the like need to be designed to be able to cope with a sudden gas generation.

As shown in FIG. 3 (a), the exhaust hole 1a on the lower surface of the elastic
When the center of the lower surface of the elastic valve body 2 and the center of the exhaust hole 1a deviate from each other, the elastic valve body 2 is inclined and the exhaust hole is inclined. 1a, it is easy to cause a variation in valve operating pressure, which causes gas leakage and electrolyte leakage at a low pressure less than a predetermined pressure, especially in a battery using an alkaline electrolyte, If the electrolyte leaks due to this cause, there is also a possibility that a problem of corroding peripheral components may occur.

On the other hand, as shown in FIG.
In the case of a safety valve device having a structure in which the area in contact with the surface of the sealing plate 1 except for the exhaust hole 1a is large, the function of preventing liquid leakage is reliable, but it is used as an emergency backup power source like a sealed alkaline storage battery. When used in high-temperature trickle-charged batteries or batteries used as power sources that require rapid charging and discharging such that the batteries themselves generate heat, there are many opportunities for gas generation, and safety valve devices must be used. It is required to operate, but as described above, the sealing plate 1 and the elastic valve body 2
The safety valve device having a large contact area with the valve has a structure in which the lower surface of the elastic valve body 2 easily adheres to the sealing plate 1 when used or stored for a long time at a high temperature or for a long time, and the valve operates due to charge / discharge or misuse. When the gas discharge timing is delayed, the valve operating pressure becomes much higher than the set pressure, or in extreme cases, the valve may not work, causing the battery to be damaged or exploding. was there.

The present invention has been made in order to solve the above-described problems, and against sudden gas generation under severe conditions,
It is an object of the present invention to provide a safety valve device for a sealed battery that accurately performs a valve operation.

Means and Action for Solving the Problems The present invention relates to a safety valve device for a sealed battery in which an exhaust hole of a sealing plate is closed by an elastic valve body housed in a valve lid, wherein the sealing plate of the elastic valve body is provided. The shortest diameter of the lower surface in contact with is not less than 1.8 times and not more than 3 times the exhaust hole diameter, and the surface roughness of the portion of the sealing plate contacting the elastic valve body is not less than 0.2 μmRa and not more than 1.5 μmRa. As a feature, by configuring the safety valve device in this way, a sealed battery having no liquid leakage and reliable valve operation can be configured.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view of the vicinity of a safety valve of a sealed nickel cadmium battery used in this embodiment. In FIG. 1, reference numeral 1 denotes a sealing plate obtained by pressing a flat metal plate. Is provided with a gas exhaust hole 1a. On the sealing plate 1 including the exhaust hole 1a, a metal plate-shaped valve cover 3 also serving as a terminal plate and containing an elastic valve body 2 obtained by compression molding synthetic rubber or the like is provided.
And the valve hole 3a
Is fixed to the sealing plate 1 by spot welding to form a safety valve device.

Table 1 shows that the diameter of the lower surface of the elastic valve body 2 that closes the exhaust hole 1a is the diameter of the exhaust hole 1a as the safety valve device of this embodiment.
A constant value of 2.2 times, the surface roughness of the portion of the sealing plate 1 in contact with the elastic valve body 2 was changed to 0.07 to 3 μmRa, and the storage battery was assembled at a temperature of 70 ° C and a humidity of 80 ° C.
It is a table | surface which shows the test result of the change rate of the valve operating pressure after 1 month storage under the conditions of RH%, and the presence or absence of a liquid leak.

FIG. 2 shows the lower surface diameter of the elastic valve body 2 and the exhaust hole 1a on the horizontal axis.
The experimental data shows the ratio of the diameter and the rate of change of the operating pressure on the vertical axis. The surface roughness of the portion of the sealing plate 1 in contact with the elastic valve body 2 was set to a constant value of 0.6 μmRa as an experimental condition. The diameter of the lower surface that contacts the sealing plate 1 of the valve body 2 and closes the exhaust hole 1a is set to be 1.2 to 4 times the diameter of the exhaust hole 1a, respectively.
It is a figure which shows the average change rate of valve operating pressure, and the fluctuation | variation width after assembling as a storage battery at the temperature of 70 degreeC after storing for 3 months.

According to Table 1, when the surface roughness of the sealing plate 1 is less than 0.2, sticking occurs between the sealing plate 1 and the elastic valve body 2, so that the valve operating pressure increases and the surface roughness becomes rougher than 1.5. It can be seen that, in the case of an alkaline electrolyte having high permeability, liquid leakage occurs.

According to the test results shown in FIG. 2, the diameter of the lower surface that closes the exhaust hole 1a of the elastic valve body 2 is 1.8 times the diameter of the exhaust hole 1a.
It can be seen that when the value is up to three times, a stable valve function is obtained with little variation in valve operating pressure.

That is, when the diameter of the lower surface closing the exhaust hole 1a of the elastic valve body 2 is small, the valve operating pressure due to the displacement of the elastic valve body 2 is low. It is considered that a phenomenon occurs in which the relationship is close to fixation, and a phenomenon occurs in which the valve operating pressure is increased, and in each case, the variation in the valve operating pressure is increased.

According to the above test results, the diameter of the lower surface of the elastic valve element 2 of the safety valve that is in contact with the sealing plate 1 and closes the exhaust hole 1a is 1.8 to 3 times the diameter of the exhaust hole 1a, and the elastic valve element 2 of the sealing plate 1 It has been found that a condition in which the surface roughness of the portion in contact with is 0.2 to 1.5 μmRa is preferable.

The present invention is not limited to the above-described embodiment, and can be modified and implemented without changing the gist.

For example, in the embodiment, the lower surface of the elastic valve body is described as being circular, but may be polygonal. When the diameter of the inscribed circle inscribed in this polygon is 1.8 to 3 times the diameter of the exhaust hole. Has the same effect.

In the embodiment, the valve lid also serves as the terminal plate. However, the valve lid may have an independent configuration.

[Effects of the Invention] According to the present invention, by configuring the safety valve device as described above, variation in the operating pressure of the safety valve due to misalignment of the elastic valve body and adhesion to the sealing plate, and adhesion due to storage at a high temperature, and It is possible to prevent leakage and provide a highly reliable sealed battery.

[Brief description of the drawings]

FIG. 1 is a partial sectional view mainly showing the vicinity of a safety valve device according to an embodiment of the present invention, and FIG. 2 is a sealed battery using the safety valve device according to the embodiment. FIG. 3 is a partial cross-sectional view for explaining a conventional safety valve device, in which the vertical axis represents the ratio of the diameter of the exhaust port and the operating pressure change rate on the vertical axis. DESCRIPTION OF SYMBOLS 1 ... Sealing plate, 1a ... Exhaust hole 2 ... Elastic valve body, 3 ... Valve lid

Claims (1)

(57) [Claims] 1. A safety valve device for a sealed battery in which an exhaust hole of a sealing plate is closed by an elastic valve housed in a valve lid, wherein the shortest diameter of a lower surface of the elastic valve body in contact with the sealing plate is the diameter of the exhaust hole. A safety valve device for a sealed battery, wherein the surface roughness of a portion of the sealing plate contacting the elastic valve body is 0.2 μmRa or more and 1.5 μmRa or less.