JPH08162093A - Storage battery - Google Patents

Abstract

PURPOSE: To provide a storage battery in which a mechanism for avoiding an overcharge is integrated into the storage battery itself, and the battery is never unusable even when the mechanism is once operated. CONSTITUTION: In a storage battery having a generating element sealed in a case, and positive and negative terminal parts arranged on the case outer surface, it is internally provided with a normally closed type pressure sensitive contact mechanism formed of a pressure sensitive part 8 displaced by receiving the case internal pressure, and a contact mechanism 6 for ordinarily connecting at least one terminal part 4 to an internal electrode 2 and interlocking to the movement of the pressure sensitive part 8 to interrupt the connection when the pressure is excessive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed storage battery such as a nickel-cadmium battery, and more particularly to a technique for ensuring safety even when overcharged.

[0002]

As is well known, many recent storage batteries have an explosion-proof safety valve integrally incorporated therein. The explosion-proof safety valve operates when the pressure inside the battery case rises abnormally and safely discharges the gas in the battery to the outside to prevent an explosion, and various concrete mechanisms have been developed. Widely used for practical use. To give an example,
There is a gasket in which a part of the gasket is made thin so that when the internal pressure increases, the thin part is broken (the thin part becomes a safety valve). Further, there is also one in which a vent hole formed in a part of the case in advance is closed by a safety valve and the elastic force of a spring is given to the safety valve to receive a biasing force on the through hole side.

When the storage battery is charged, when the battery approaches the full charge, gas is generated from the power generation element and the pressure in the battery case rises. If the charging is completed properly when fully charged, the pressure rise will be within the range where there is no problem. However, if the battery is fully charged and accidentally continued to be charged, the pressure in the battery will rise further and may reach a dangerous level in some cases. Therefore, when the pressure in the battery becomes excessive, the explosion-proof safety valve built in the battery itself operates as described above, and when the pressure is small, the internal gas and the like are released to prevent explosion-proof.

[0004]

However, in the case of the structure in which a part of the gasket is broken as in the former case, once the explosion-proof safety valve is actuated, the internal gas and electrolytic solution can be constantly released and flowed out. It cannot be reused as a battery. Therefore, the operating pressure at which the safety valve operates (breaks) is set to a high value, which may cause explosion-proof before breaking, leaving a safety problem.

Further, in the latter method using a spring,
When the gas pressure decreases, the safety valve closes the through hole. Therefore, even if the safety valve temporarily works, the battery performance is hardly deteriorated and the battery can be reused. However, even if it is temporary, the internal gas will be released when the safety valve is open, and there is a risk that the electrolytic solution inside will also leak out. Then, if not only the surroundings are polluted but also the overcharged state continues, the safety valve keeps the open state, so that the discharge of gas and electrolyte continues, the battery performance deteriorates, and eventually the storage battery becomes unusable. May be. If the working pressure of the safety valve is set to be low in consideration of safety, the safety valve will operate even with a slight overcharge, and the above-mentioned problems will easily occur, resulting in a large economical loss.

Further, since various conventional safety valves have been developed with various structures for the purpose of preventing explosion-proof due to increase of internal gas pressure, charging is not stopped even if the safety valve operates. The overcharged state continues as long as possible. Therefore, the problems of deterioration of battery performance and heat generation due to overcharge cannot be solved.

Therefore, conventionally, the charging device is also provided with a circuit-like measure for preventing overcharging. That is, the charging device detects the full charge of the storage battery and automatically stops the charging operation. However, although some circuit methods for detecting full charge have been developed, there is currently no reliable full charge detection method. Even if the reliability of the full-charge detection circuit is improved, it is a countermeasure on the charging device side, not an overcharge prevention mechanism of the storage battery itself. Moreover, various sensors and circuits for detecting full charge based on the outputs of the sensors are required, which leads to an increase in complexity and size of the charging device, which further increases the cost. The above problem becomes more remarkable as the performance of the detection circuit is increased.

The present invention has been made in view of the above background. An object of the present invention is to incorporate a mechanism for avoiding overcharge into a storage battery itself, and the mechanism is simple and can be performed with high accuracy and to prevent failure. Another object of the present invention is to provide a storage battery that is less likely to become unusable even if the mechanism operates once.

[0009]

In order to achieve the above object, in the storage battery according to the present invention, the power generating element is sealed in the case, and the positive and negative terminal portions connected to the power generating element are arranged on the outer surface of the case. An installed storage battery, wherein the pressure-sensitive portion that is displaced by receiving the pressure in the case, and at least one of the terminal portion and the internal electrode are always connected,
A normally closed pressure-sensitive contact mechanism including a contact mechanism that interrupts the connection when the pressure becomes excessive in association with the movement of the pressure-sensitive portion is built in.

More specifically, a part of the case, which is deformed so as to bulge outward due to the internal pressure, serves as the pressure sensitive portion. As another specific configuration, the case is provided with a cylinder part having one end communicating with the case and the other communicating with the outside, and a reciprocating piston is provided in the cylinder part. And
The piston that moves based on the pressure difference between the inside and the outside of the case is the pressure-sensitive portion.

[0011]

It is assumed that, when the storage battery of the present invention is connected to the charging device and charged, the battery is erroneously charged even though it is fully charged. In this case, when the pressure in the battery case rises beyond the normal range, the pressure-sensitive portion receives the pressure and is largely displaced, and the displacement causes the contact mechanism to open. That is, the internal path connecting the terminal portion connected to the charging device and the electrode in the case is cut off, the charging current does not flow into the power generating element, and the charging is stopped.

Therefore, even in a storage battery having a general explosion-proof safety valve incorporated therein, charging is stopped before the safety valve is activated. Of course, a storage battery that does not have a safety valve will also work. If the battery is left in that state, the internal pressure drops to a normal level and the contact mechanism is closed again. Therefore, not only the safety is enhanced, but also the inconvenience that the battery becomes unusable due to the operation of the safety valve can be avoided.

[0013]

The preferred embodiments of the storage battery according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a schematic structure of a storage battery according to a first embodiment of the present invention. As shown in the figure, a metal battery case 1 having a bottomed cylindrical shape is loaded with a power generating element (a positive electrode 2 and a negative electrode 3 separated by a separator and an electrolytic solution), and an open end of the battery case 1 is a plastic sealing gasket. And a metal terminal board 4 for sealing.
The positive electrode 2 is internally connected to the metal terminal plate 4, and the metal terminal plate 4 serves as a positive electrode terminal portion.

In the present invention, the contact plate 5 connected to the negative electrode 3 is disposed on the bottom surface of the cylindrical power generating element, and the contact plate 5 is separated from the inner bottom surface of the battery case 1. Abuttable as possible. The negative electrode 3 is now the battery case 1.
The battery case 1 serves as a negative electrode terminal portion.

Further, by devising the thickness and shape of the bottom surface 1a of the battery case 1, when the pressure inside the case rises, the bottom surface 1a of the case is elastically deformed by the pressure and bulges outward. . As a condition of the member forming the bottom surface 1a of the case, it is necessary that the member has conductivity and also has the property of a leaf spring. The case bottom surface 1a is the pressure-sensitive portion described above, and the contact portion between the case bottom surface 1a and the contact plate 5 is the contact mechanism described above.

With such a structure, as shown in FIG. 2B, when the case bottom 1a is deformed and bulges outward due to an overcharged state and an excessive pressure in the case 1, the case bottom 1a and the contacts are contacted. The plate 5 is separated, and as a result, the path internally connecting the negative electrode 3 and the battery case 1 is cut off. This automatically opens the charging circuit and stops charging.

Since the case bottom surface 1a is elastically deformed and swelled, it returns to its original shape when the internal pressure decreases, and the case bottom surface 1a and the contact plate 5 come into contact again. The above is the configuration and operation of the normally closed pressure-sensitive contact mechanism.

Further, in this embodiment, the case bottom surface 1a is
Contact mechanism to consist of contact plate 5 is, in order to prevent the chattering, as shown in FIG. 2 as spring characteristics of the case bottom 1a, a bulge at 4 kgf / cm ^2, the pressure to 3 kgf / cm ² if inflated once It has a hysteresis characteristic that returns to the original state when it decreases.

Next, a specific charging operation when a CADNICA battery is used as the storage battery will be described. As a charging condition, the battery capacity was 1.8 Ah, and constant current charging of 2.7 A was performed. The temperature condition at this time was 20 ° C.
Then, as shown in FIG. 3 (A), the charge amount increases linearly with the passage of time, and as shown in FIG. 3 (D), the internal gas pressure also increases after a certain period of time as the charge amount increases. Going up. In this example, when the charged amount is 100%, the gas pressure becomes 4 kgf / cm ² and the case bottom surface 1a swells, so that the charging current is interrupted (see FIGS. 7B and 7C). Then, charging stops and further increase in gas pressure stops. Then, the generated gas is consumed inside and the gas pressure decreases. And a constant pressure (3 kgf
/ Cm ² ) or less, the bottom surface 1a of the case returns to its original state and the contacts are closed. Therefore, in this state, power can be supplied to the load as a normal battery. Also,
If the charging device continues to charge,
According to the time charts shown in the figures, the bottom surface of the case is changed (contacts are opened / closed), and the gas pressure is prevented from becoming constant.

The battery performance is not deteriorated by overcharging of about 120%, and when the battery is fully charged, the charging is stopped relatively quickly, and further, when the battery is in the fully charged state, further charging is attempted. Since the contacts are opened and charging is stopped in a short time, the overcharged state continues, the safety valve does not remain open as in the conventional case, and liquid leakage does not occur.

FIG. 4 shows a schematic structure of a storage battery according to the second embodiment of the present invention. In this example, the negative electrode 3
Is firmly connected to the battery case 1 inside, and the positive electrode 2 is connected to the metal terminal plate 4 via the contact mechanism 6. A cylinder portion 7 is formed at a portion of a plastic sealing gasket interposed between the metal terminal plates 4 of the battery case 1, and a piston 8 is slidably fitted in the cylinder portion 7. One end side of the cylinder portion 7 is open inside the battery case 1, and the other end side is in communication with the outside. Therefore, the pressure in the case 1 acts on one side of the piston 8 and the atmospheric pressure acts on the other side.

On the other hand, the contact mechanism 6 constitutes a normally-closed contact utilizing the elastic force of a leaf spring or the like, and the tip of a piston rod 9 connected to the piston 8 contacts the movable contact thereof. ing. When the pressure in the battery case 1 is within the normal range, the contact mechanism 6 is closed and the positive electrode 2
Are configured to be connected to the metal terminal board 4.

In this state, if the battery 8 becomes overcharged and the pressure in the battery case 1 becomes excessive, the piston 8 is displaced to the right in FIG. 4, and the tip of the piston rod 9 contacts the contact mechanism 6.
Then, the movable contact is pushed to open the contact mechanism 6. That is, the path internally connecting the positive electrode 2 and the metal terminal plate 4 is cut off. When the pressure in the case decreases, the piston 8 returns to its original position and the contact mechanism 6 closes again. The above is the configuration and operation of the normally closed pressure-sensitive contact mechanism. In this embodiment as well, it is possible to obtain the same effects as those of the first embodiment described above.

[0024]

Since the storage battery of the present invention has the normally closed pressure-sensitive contact mechanism integrally incorporated in the case, even if the storage battery is accidentally overcharged, the pressure in the case rises beyond the normal range. Then, the pressure-sensitive portion receives the pressure and is displaced, and the displacement causes the contact mechanism to open. That is, the internal path connecting the terminal portion connected to the charging device and the electrode in the case is cut off, and the charging current does not flow into the power generation element.

Therefore, even if a general explosion-proof safety valve is also incorporated, charging can be automatically stopped on the battery side before the safety valve is activated. Moreover, since the internal pressure does not exceed a certain value during charging, explosion protection of the storage battery can be suppressed without incorporating such a safety valve.

If the battery is left in that state,
When the internal pressure drops to a normal level, the contact mechanism closes again and power can be supplied to the load. Therefore, not only the safety is enhanced, but also the inconvenience that the battery becomes unusable due to the operation of the safety valve can be avoided.

Further, since the charging is stopped, the charging current does not flow even though the battery is fully charged, the liquid does not leak, the battery performance does not deteriorate, and the heat generation can be suppressed to the minimum. Further, it is not always necessary to provide a circuit for detecting an overcharge (full charge) state on the charging device side,
Further, even when the charging device is provided, the charging device can be downsized because the accuracy is relatively low, and the cost is reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a storage battery according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a spring characteristic of a bottom surface of a case.

FIG. 3 is a time chart diagram during charging.

FIG. 4 is a schematic configuration diagram of a storage battery according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Battery Case 1a Case Bottom (Pressure Sensing Part) 2 Positive Electrode 3 Negative Electrode 4 Metal Terminal Plate 5 Contact Plate (Contact Mechanism) 6 Contact Mechanism 7 Cylinder Part 8 Piston (Pressure Sensing Part) 9 Piston Rod

Claims (3)

[Claims] 1. A storage battery in which a power generation element is sealed in a case, and positive and negative terminals connected to the power generation element are arranged on the outer surface of the case. A contact mechanism that constantly connects the pressure section and at least one of the terminal section and the internal electrode, and disconnects the connection when the pressure becomes excessive in conjunction with the movement of the pressure sensing section. A storage battery characterized by having a normally closed pressure-sensitive contact mechanism consisting of and. 2. The storage battery according to claim 1, wherein a part of the case, which is deformed so as to bulge outward by an internal pressure, is the pressure-sensitive portion. 3. A case is provided with a cylinder part, one end of which communicates with the inside of the case and the other of which communicates with the outside, and a reciprocating piston is provided within the cylinder part, wherein a pressure difference between the inside and outside of the case is provided. The storage battery according to claim 1, wherein the piston that moves based on the pressure is the pressure-sensitive portion.