JPH0562956U - Battery safety device with rupture disc - Google Patents

Abstract

(57) [Summary] [Purpose] The current is cut off at an accurate set pressure and the internal pressure is released. Prevents malfunction due to mechanical shock. [Structure] The battery safety device includes a rupture disk 3. The current collecting lead 2 of the electrode is electrically connected to the dome-shaped projection 3A of the rupture disk 3. When the internal pressure reaches the set pressure and the rupture disk 3 is reversed and broken, the connection between the current collecting lead 2 and the rupture disk 3 is cut off and the current is cut off to release the internal pressure. [Effect] When the internal pressure reaches the set pressure, the dome-shaped protrusions of the rupture disk are reversed and the current collecting leads are separated from the rupture disk. Therefore, the dome-shaped projection is largely deformed by an accurate operating pressure to surely interrupt the current and release the internal pressure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a battery safety device, which has been attracting attention as electronic devices become portable, and more particularly to a battery safety device having a rupture disk that reverses and fractures when the internal pressure rises.

[0002]

[Prior Art]

 In recent years, as electronic devices have become portable, expectations for batteries with high energy density have increased significantly. Since these batteries have high energy, there is a risk of explosion or fire if the device is abnormal or misused. Therefore, various safety devices have been devised and invented, and measures against explosion and ignition have been taken. Most of them are internal pressure release type valves. This valve opens the internal pressure by opening it when the internal pressure rises abnormally, and is disclosed in, for example, Japanese Patent Laid-Open No. 3-69785. However, the safety device with this structure cannot realize sufficient safety in applications where a large amount of current is passed and in secondary batteries that are forcibly charged from the outside. This is because the abnormal rise in internal pressure can be prevented, but the current cannot be interrupted at the time of abnormality.

In order to solve this drawback, a safety device that cuts off an electric current at the time of an abnormality has been developed (Japanese Patent Laid-Open Nos. 11251/1990 and 288063/1990). The safety devices described in these publications are shown in FIGS. This safety device comprises a safety valve 1 which deforms when the internal pressure of the battery rises. A current collecting lead 2 is connected to the center of the lower surface of the safety valve 1. The safety valve 1 has a thin portion 1A so that the safety valve 1 is broken to release the internal pressure when the internal pressure of the battery rises abnormally. When there is no abnormality, the safety valve 1 has a current collecting lead 2 connected to the lower surface as shown in FIG. When the internal pressure of the battery rises, the safety valve 1 is deformed as shown in FIG. 2 and the collector lead 2 is peeled off. In this state, the current is cut off. When the internal pressure further rises, as shown in FIG. 3, the thin portion 1A of the safety valve 1 breaks to release the internal pressure.

[0004]

[Problems to be solved by the device]

 The safety device with this structure releases internal pressure and shuts off current when an abnormality occurs, so it is very effective for insulation from external circuits. However, for abnormalities such as internal short-circuiting, which is ineffective with current interruption, the pressure may be released, which is close to a burst. The reason is that it is difficult to achieve sufficient fracture accuracy by the method of providing the thin portion 1A on a part of the safety valve to be fractured.

Further, since the safety valve has a structure which is deformed by the internal pressure, the amount of displacement of the safety valve 1 with respect to the change of the internal pressure is small. Therefore, in order to increase the current cutoff accuracy, the connection with the current collecting lead 2 requires extremely high accuracy. Further, since the lead wire is broken when the safety valve 1 is displaced by a small amount, there is a drawback that the current collecting lead 2 is broken even by a mechanical shock, which causes a problem in reliability. In particular, if a material other than aluminum is used for the safety valve, there is a drawback that the operating accuracy is significantly reduced.

The present invention was developed for the purpose of solving these drawbacks of the related art, and the important purpose of this invention is to correct the operating pressure for releasing the internal pressure and the operating pressure for interrupting the current. A certain object of the present invention is to provide a battery safety device that can remarkably improve the safety of the battery and further reduce malfunctions caused by impact such as dropping or vibration.

[0007]

[Means for Solving the Problems]

 The battery safety device of the present invention has the following configuration in order to achieve the above-mentioned object. That is, in the battery safety device, the current collecting lead 2 of the electrode is electrically connected to the dome-shaped projection 3A of the rupture disk 3 which is inverted and broken in the internal pressure direction as the internal pressure rises. If the rupture disk 3 is reversed and ruptured when the internal pressure reaches the set pressure, the safety device disconnects the current between the current collector lead 2 and the rupture disk 3 and interrupts the current. Is configured.

[0008]

The rupture disc 3 is manufactured by processing a thin metal plate into a dome shape. The metal plate, which is the starting material for the rupture disc 3, can be made highly accurate in thickness, so when the pressure reaches the design pressure, it can be reversed at once and the dome can be cleaved. Therefore, the operating accuracy can be made very high. The operation accuracy of the rupture disc 3 is several times higher than the operation accuracy of a safety valve in which a thin portion 1A is provided on a part of a metal plate. On the other hand, in the rupture disc 3, the dome is inverted and largely deformed during operation. Therefore, the displacement amount of the dome-shaped projection 3A of the rupture disc 3 is very large, and the current collecting lead 2 connected thereto can be reliably broken. Therefore, the strength of connecting the current collecting lead 2 to the rupture disk 3 can be increased, and it is stable against mechanical shock. Therefore, the safety device of the present invention has a unique structure in which the current collecting lead 2 is connected to the protruding portion of the rupture disk 3 to enhance the operation accuracy and to cut off the current and release the internal pressure.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. However, the embodiments described below are examples of a battery safety device for embodying the technical idea of the present invention, and the safety device of the present invention includes the material, shape, structure, and arrangement of components. Is not specified in the structure below. The safety device of this invention can be modified in various ways within the scope of claims for utility model registration.

Further, in this specification, in order to make it easy to understand the scope of claims for utility model registration, the numbers corresponding to the members shown in the embodiments are referred to as "scope of claims for utility model registration" and "to solve the problems." It is added to the members shown in the column of "means for performing". However, the members shown in the scope of the utility model registration request are not limited to the members of the embodiment.

In the safety device shown in FIGS. 4 and 5, the cap 4, the rupture disc 3, and the insulating plate 8 are laminated and caulked and fixed to the upper end of the casing 9 of the battery.

The cap 4 is a metal plate and includes an upper cap 4A and a sandwiching cap 4B. The upper cap 4A and the rupture disc 3 have the same outer diameter, and the upper cap 4A and the rupture disc 3 are laminated and sandwiched by the peripheral edge of the sandwich cap 4B. The upper cap 4A has a convex shape in the central portion as a whole, and has a gas vent hole 5 in the outer peripheral portion. The sandwich cap 4B has a through hole 6 as a center, through which the convex portion of the rupture disk 3 can be inserted.

The rupture disk 3 is a thin metal plate, and has a dome-shaped projection 3A with its center protruding inside the battery. When the internal pressure of the battery becomes higher than the set pressure, the dome-shaped projection 3A of the rupture disk 3 projects in the internal pressure direction, that is, deforms upward as shown in FIG. The rupture disc 3 does not gradually deform as the pressure increases, unlike the conventional safety valve 1. The rupture disk 3 is deformed from the shape shown in FIG. 4 to the shape shown in FIG.

The insulating plate 8 is a plate material having an insulating property, and for example, a synthetic resin molded product is used. The edge plate 8 is bent upward to surround the outer periphery of the sandwich cap 4B and insulates the sandwich cap 4B from the casing 9. That is, the casing 9 of the battery is fixed by caulking the sandwich cap 4B via the insulating plate 8. A through hole 7 into which the dome-shaped projection 3A of the rupture disk 3 is inserted is also provided at the center of the insulating plate 8. The thickness of the insulating plate 8 and the sandwiching cap 4B is designed to be approximately equal to the height of the dome-shaped protrusion 3A of the rupture disc 3. In other words, the height of the dome-shaped protrusion 3A is designed to be approximately equal to the sum of the thicknesses of the sandwich cap 4B and the insulating plate 8.

A current collecting lead 2 connected to an electrode (not shown) of a battery is welded to the lower end of the dome-shaped projection 3A of the rupture disk 3 inserted into the through hole 7 of the insulating plate 8.

The battery safety device shown in FIG. 4 protrudes below the dome-shaped protrusion 3 A of the rupture disc 3 in the normal use state, that is, in the state where the internal pressure of the battery is lower than the set pressure, and the lower end The collector lead 2 is electrically connected to the. When the internal pressure of the battery becomes higher than the set pressure, as shown in FIG. 5, the dome-shaped projection 3A is deformed so as to project upward, and the connection with the current collecting lead 2 is broken. Further, a part of the dome-shaped protrusion 3A is broken, and the internal pressure of the battery is released.

The battery safety device according to the embodiment of the present invention shown in FIGS. 4 and 5 and the conventional safety device shown in FIGS. 1 to 3 were prototyped to produce a current interruption operating pressure and an internal pressure releasing operating pressure. As a result of measuring the malfunction due to the drop and the vibration, the results shown in Table 1 are obtained.

Table 1

In this experiment, in the conventional example, two kinds of current collecting leads 2 having different connection strengths were tested. In the conventional example (1), the connection strength of the current collecting lead 2 is stronger than in the conventional example (2). In the drop + vibration test, after dropping 10 times from a height of 1 m, it was vibrated and the number of failures was measured.

The safety devices of the conventional examples (1) and (2) are in the state shown in FIG. 1 when the internal pressure is equal to or lower than the set pressure. When the internal pressure rises, the safety valve 1 is deformed as shown in FIG. 2, the current collecting lead 2 is broken, and the current is cut off. When the internal pressure further rises, the safety valve 1 breaks and the internal pressure is released, as shown in FIG.

As can be seen from this table, the conventional battery safety device has a wide range of variations in operating pressure and has a drawback that it cannot be operated with high accuracy at a constant set pressure. Further, in order to reduce malfunction due to dropping and vibration, it is necessary to strengthen the connection strength of the current collecting lead 2, and it is impossible to operate at a safe working pressure. In addition, when the operating pressure is lowered, it becomes vulnerable to mechanical shock and reliability deteriorates. On the other hand, the safety valve 1 of the present invention can provide a stable operating pressure with extremely high precision, and is safe because the internal pressure is released early even when an internal short circuit occurs.

[0022]

[Effect of the device]

 The battery safety device of the present invention has a unique structure in which a thin metal plate is processed into a dome shape and a current collecting lead is connected to the dome-shaped protrusion. In the safety device of this structure, when the internal pressure becomes higher than the set pressure, the dome-shaped projection is projected in the internal pressure direction and is greatly deformed. When the dome-shaped protrusion is deformed, the current collecting lead connected here is broken and the current is cut off. The rupture disc with dome-shaped protrusions has a feature that it can be deformed rapidly with a high degree of accuracy, unlike a structure in which the amount of deformation increases in proportion to the internal pressure like the safety valve of conventional safety devices. The reason is that the dome-shaped protrusions of the rupture disc are deformed by reversing the projecting direction. Therefore, the safety device of the present invention, in which the current collecting lead is connected to the dome-shaped projection of the rupture disc, has the features that the working pressure can be made accurate and the current can be cut off surely to release the internal pressure.

Furthermore, the safety device of the present invention in which the connecting portion of the current collecting lead is largely displaced makes it possible to reliably disconnect the current collecting lead connected to the dome-shaped projection with an accurate operating pressure. Therefore, the safety device of the present invention can release the internal pressure and cut off the electric current with extremely high accuracy in an abnormal state. In addition, the safety device of the present invention operates by reversing the dome-shaped protrusion, so that the change in operating pressure due to the ambient temperature is small and the connection strength between the current collecting lead and the rupture disk is increased, so that mechanical shock is generated. It is possible to eliminate the malfunction caused by, and to obtain the one with very high reliability in normal use, and the effect is great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a conventional battery safety device.

FIG. 2 is a cross-sectional view showing the safety device shown in FIG. 1 in which a safety valve is broken from a current collecting lead.

FIG. 3 is a sectional view showing the safety device shown in FIG. 1 in a state in which a safety valve is broken.

FIG. 4 is a sectional view of a battery safety device showing an embodiment of the present invention.

5 is a cross-sectional view showing a state in which the dome-shaped projection of the safety device shown in FIG. 5 is inverted.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Safety valve 1A ... Thin portion 2 ... Current collecting lead 3 ... Rupture disk 3A ... Dome-shaped protrusion 4 ... Cap 4A ... Upper cap 4B ... Clamp cap 5 ... Gas vent hole 6 ... Through hole (Clamp cap) 7 ... Through hole (Insulating plate) 8 ... Insulating plate 9 ... Casing

Claims (1)

[Scope of utility model registration request] 1. A rupture disk having a dome-shaped protrusion (3A) which is inverted and fractured in the direction of the internal pressure as the internal pressure rises.
In the battery safety device including (3), the dome-shaped projection (3A) of the rupture disc (3) is electrically connected to the electrode current collecting lead (2), and the internal pressure reaches the set pressure and the rupture disc (3) is reached. When (3) is reversed and broken,
A battery safety device characterized in that a current is cut off by disconnecting the connection between the current collecting lead (2) and the rupture disk (3), and the current is cut off at the same time when the internal pressure is released.