JPH0132675Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(a) Field of Industrial Application The present invention relates to a sealed secondary battery case, and more particularly to a sealed secondary battery case that performs charge cut-off by detecting changes in the shape of the battery case. (B) Prior art In general, the charge cut-off at the completion of charging in high-rate charging of sealed secondary batteries, such as cylindrical sealed nickel-cadmium batteries, is performed by detecting changes in battery voltage or rise in battery temperature. A method has been adopted to stop the However, although this method ensures charge cut-off, the internal gas pressure increases to 4 to 5 kg/cm ² , so it cannot be used for prismatic sealed secondary batteries with low pressure resistance. On the other hand, one proposed method for charging small sealed lead batteries is one in which the resin battery case swells and deforms due to the rise in internal gas pressure at the end of charging, which activates a micro switch on the charger to end charging. has been done. This method has an extremely simple charging circuit, and is suitable as a high-rate charging method for prismatic batteries because charging is cut off at a stage when the internal gas pressure does not rise excessively. However, this method lacks the reliability of microswitch operation because the deformation size due to the bulge is small, and as the bulging, contraction and restoration are repeated over a long period of time, the elasticity of the container material is lost, the contraction and restoration function is lost, and the power is lost. There was a problem in that the tank was destroyed and it became impossible to seal the battery case. (c) Purpose of the invention The present invention improves the shape of a sealed secondary battery case that cuts off charging by detecting the rise in internal gas at the end of charging based on a change in the external shape of the case, thereby improving the charging cut-off operation. The purpose is to improve reliability and maintain operational functionality over a long period of time. (d) Structure of the invention In the sealed secondary battery case of the invention, a part of the main case that houses the power generating element inside is deformed at a lower pressure than the main case due to an increase in internal gas pressure. The battery case has a deformed portion having a W-shaped side cross section and a recessed cone shape or a recessed pyramid shape, and a joint portion between the deformed portion and the main body case and a lowermost portion of the recessed portion of the deformed portion have a hinge portion. When the gas pressure inside reaches a certain level, the deformed part instantly protrudes to the outside of the battery case and pushes up the contact of the microswitch of the charger, which has been placed in advance, to cut off charging. (E) Example Fig. 1 is a perspective view of a sealed secondary battery case of the present invention, and Fig. 2 A and B are side sectional views of the deformable portion of the present invention before and after deformation. . In the drawings, reference numeral 1 denotes a main case housing a power generating element inside, and is composed of a lower case 2 and an upper lid 3. The upper lid 3 is provided with a deformable part 4, a safety valve 5, and positive and negative electrode terminals 6, 7. There is. In addition, the deformed portion 4
is lower than the operating pressure of the safety valve 5 and the main body case 1
It has a depressed conical shape with a W-shaped side cross section that deforms at a pressure lower than the pressure at which the deformation occurs, and hinge parts 8 and 9 are provided at the joint between the deformable part 4 and the main body case 1 and at the bottom of the concave part of the deformable part. ing. This deformed part 4 is shown in Fig. 2A before charging when the gas pressure inside the battery case is low.
As shown in the figure, the side cross section has a W-shape, and when the internal gas pressure exceeds a certain value due to oxygen gas generated inside the battery case during charging, the hinge parts 8 and 9 of the deformable part 4 move toward the outside of the battery case. Turn around and bend towards
It has a chevron shape as shown in Figure 2B and protrudes outward from the battery case to signal the end of charging. Therefore, if the microswitch of the charger is placed in advance at a position facing the top 10 of the deformable portion 4, the protrusion of the deformable portion 4 will cause the top 10 to push up the microswitch and cut off charging. . If the battery charged in this way is discharged or left alone,
The oxygen gas inside the battery is internally consumed and the internal gas pressure decreases, eventually becoming negative pressure, and the hinge parts 8 and 9 of the deformed part 4 are reversed and bent towards the inside of the battery case, and the original W-shape is restored. restore to state. Here, the setting of the deformation operating pressure of the deformation section 4 requires self-recovery after deformation, and when assembling the battery in the atmosphere, the oxygen partial pressure in the atmosphere is approximately 0.2.
Kg/cm ² , so in order to recover when all the oxygen inside the container has been absorbed, it must be 0.2Kg/cm2 below atmospheric pressure.
It is sufficient to set it so that it recovers when the cm ² gas pressure decreases, but if other recovery mechanisms are taken into account, it can be selected within a wider range. Further, since the magnitude of the displacement of the deformed portion 4 can be determined by the depth dimension of the depressed portion, it can be freely designed. Further, an embodiment of the present invention will be shown and explained below together with a comparative example. (Example) A sealed prismatic nickel-cadmium storage battery with a capacity of 1.5 AH, a diameter of 5 mm, a protrusion height of 5 mm, and a set operating pressure of 0.4.
A concave cone-shaped deformable part made of polypropylene of kg/cm ² was attached, and a battery A as shown in FIG. 1 was prepared. (Comparative Example) A battery B was produced which was completely the same as the example except that the deformed portion described above was not provided. 100 cells of each of Batteries A and B of Examples and Comparative Examples were charged with a charger that cuts off charging by operating a micro switch, and performance comparisons were made. Cycle conditions are 1C charging and 1
C discharge. The table below shows the measurement results of malfunction rate and charging capacity. Incidentally, the malfunction rate is the percentage of batteries that do not operate even after being fully charged and those that cannot be charged because the deformation does not recover.

[Table] As is clear from the table, it can be seen that the battery A according to the present invention is an excellent battery that maintains high reliability with no malfunction and little decrease in charge capacity even after long-term charging and discharging cycles. On the other hand, the charging capacity of Comparative Example Battery B was significantly reduced because the battery case itself was not easily deformed and full charge could not be detected accurately, making it easy to overcharge. This is thought to be due to the adhesive part of the main body case peeling off, which adversely affected the battery. In addition, in the embodiment, a depressed conical shaped deformed part was used, but the shape may be any shape as long as the side cross section is W-shaped.
Other possible shapes include a sunken pyramid shape. In addition to the polypropylene used in the embodiment, rubber or the like can also be used as the material for this deformed portion. (f) Effects of the invention In the sealed secondary battery case of the invention, a part of the main case that houses the power generating element inside is deformed at a lower pressure than the main case due to an increase in internal gas pressure. The main body case has a deformed part in the shape of a depressed cone or a depressed pyramid with a W-shaped side cross section, and the joint part between the deformed part and the main body case and the lowermost part of the recessed part of the deformed part have a hinge part. The deformed part protrudes to the outside of the battery case before it is affected by internal gas pressure and activates the charger's micro switch to stop charging. This prevents the strength of the main case from decreasing and ensures full charging. It is possible to provide a sealed secondary battery case that can be detected and can operate reliably because there is no variation in the deformed size of the deformed portion.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a sealed secondary battery case of the present invention, and FIGS. 2A and 2B are sectional views of the deformable portion of the present invention before and after deformation. 1... Main body case, 4... Deformed part, 8, 9...
Hinge part.

Claims (1)

[Scope of utility model registration request] A part of the main body case that houses the power generation element therein has a deformable part in the shape of a sunken cone or a sunken pyramid with a W-shaped side cross section that deforms at a lower pressure than the main body case due to an increase in internal gas pressure, A sealed secondary battery case, characterized in that a joint between the deformable portion and the main body case and a lowermost portion of the concave portion of the deformable portion have a hinge portion.