JPH0262019A - Capacitor - Google Patents

Abstract

PURPOSE:To surely prevent an explosion accident by a method wherein a soft flexible port of a prescribed width is formed into ring-shape at an upper lid, ribs extended in a diameter direction are formed collectively at a plurality of positions in a peripheral direction of the flexible part and the upper lid is swollen and deformed instantaneously at an abnormality. CONSTITUTION:An upper lid 3 which is attached at a hermetically sealing pressure and where external terminals 9, 10 connected to lead wires extracted from a capacitor element 2 are installed is made of a synthetic resin. A flexible pert 13, of a prescribed width, which is softer than other parts is formed to be ring-shaped around installation parts of the terminals 9, 10 at the upper lid 3. Ribs 14 extended in a diameter direction are formed collectively at a plurality of positions in a peripheral direction of the flexible part 13. When an internal pressure is raised abnormally, the flexible part 13 is reinforced by the ribs 14 and is hard to deform in a wavy form; the terminals 9, 10 are hard to deform; the upper lid 3 as a whole is swollen and deformed to be a conical trapezoid shape. Thereby, it is possible to surely prevent an explosion accident.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention provides a capacitor, more specifically, a safety function that utilizes fluctuations in the internal pressure of a sealed container housing the capacitor element to cut off current to the capacitor element. The present invention relates to a capacitor having a capacitor.

(Prior art) This type of capacitor uses the increased pressure to bulge and deform the top lid of the container when the internal pressure of the sealed container increases, and the capacitor element is connected to an external terminal provided on the top lid. When this safety function operates properly, explosions caused by dielectric breakdown of the capacitor element are prevented.

In conventional capacitors, the top cover is made of a thermoplastic resin plate with a predetermined thickness, and when the internal pressure of the sealed container rises abnormally, the top cover flexes into a bulging shape due to the flexibility of the thermoplastic resin itself. Known (Japanese Patent Publication No. 55-80
Publication No. 45).

(Problem to be solved by the invention) By the way, in order to sensitively detect the increase in the internal pressure of a closed container and improve its operation accuracy, the top cover should be made of highly flexible thermoplastic resin as in the past. This is desirable.

In addition, in order to reliably disconnect the external terminal from the lead wire due to the bulging deformation of the top cover, the external terminal must be reliably pulled up by the top cover with a sufficiently large force when the bulge width of the top cover reaches a predetermined width. is required.

However, if the top cover is made of a simple thermoplastic resin plate with a predetermined thickness as in the past, the flexibility of the top cover is uniform in all parts including the area where the external terminals are installed, and the external terminals are connected to the lead wires. Therefore, due to the rise in internal pressure of the sealed container, the parts other than the part where the external terminal is installed bulge and deform at the initial stage, deforming the whole into a wavy shape, and the bulging and deforming part is pulled. In the next step, the external terminal mounting portion bulges and deforms, deforming into a dome shape as a whole, and the external terminal exhibits a behavior in which it is cut off from the lead wire. Furthermore, the manner in which the top lid deforms into a wavy shape is determined by the relationship between various factors, such as how the top lid is attached to the sealed container and how well the external terminals are installed. It is difficult to predict with certainty. Therefore, with conventional capacitors, it is difficult to accurately predict when the external terminal will be disconnected from the lead wire due to an abnormal increase in the internal pressure of the sealed container, and when the current flow to the capacitor element is cut off. There were constraints on increasing the accuracy of the operation.

This invention was made in view of the above circumstances, and although the pressure detection sensitivity can be maintained at the same level as before by devising the top cover, the operation when cutting off current to the capacitor element is difficult. The present invention aims to provide a capacitor whose accuracy can be easily increased.

(Means for Solving the Problems) In the capacitor of the present invention, the top cover is made of synthetic resin and is mounted under sealed pressure and provided with an external terminal connected to a lead wire led out from a capacitor element, and the top cover is made of synthetic resin. A flexible portion having a predetermined width that is softer than other portions is formed in an annular shape around the installation portion, and ribs extending in the radial direction are integrally provided at a plurality of locations in the circumferential direction of this flexible portion.

(Function) According to the capacitor having this configuration, an increase in the internal pressure of the sealed pressure is sensitively detected by the synthetic resin top cover. When the internal pressure rises abnormally, the top cover is pressed upward by the internal pressure, and the outer and inner edges of the annular flexible part of the top cover are bent in opposite directions, and are surrounded by these flexible parts. The external terminal installation section that is currently in place will be pushed upwards. During this series of deformation processes, the annular flexible part is reinforced by the ribs and becomes difficult to deform into a wavy shape.
Further, since the external terminal installation portion is less likely to deform than the flexible portion, the top cover bulges and deforms into a truncated conical shape as a whole. That is, although the upper lid is made of flexible synthetic resin, it suddenly bulges and deforms in a state similar to an elastic reversal movement due to an abnormal increase in internal pressure.

(Embodiment) FIG. 1 is a longitudinal cross-sectional view of a capacitor C according to an embodiment of the present invention, where T is a sealed container made of synthetic resin, in which a capacitor element 2 is housed, and an upper M3 is placed in the opening at its upper end. It is installed. The end of the lead wire 4.5 led out from the capacitor element 2 is held in the hole 7.8 of the support plate 6 arranged on the back side of the upper M3. External terminals 9.10 provided on the two lids 3 are connected to the lead wires 4.5, respectively.

The upper lid 3 is made of synthetic resin such as thermoplastic resin, and the fourth
It is formed into a circle as shown in the figure, and the external terminals 9 and 10 are upper M3.
A boss portion 11 is provided in the center of the left and right portions.
It is fitted in 12. Further, a flexible part 13 that is thinner and more flexible than other parts is formed in an annular shape around the external terminal installation part X in the upper M3, and this flexible part 13 is the fifth
As shown in the figure and FIG. 6, the upper region is tapered. Further, as shown in FIG. 4, ribs 14 extending in the width direction of the flexible portion 13 (in the radial direction of the top cover) are integrally provided at a plurality of locations at equal intervals in the circumferential direction of the flexible portion 13.

The above-mentioned flexible portion 13 can be formed without changing the thickness of the upper lid 3. For example, it is also possible to form only the flexible portion 13 by using a resin layer that is more flexible than other parts. Also, the rib 14 may be placed on the back side of the upper M3.

The operating accuracy when the upper M3 bulges and deforms due to an increase in the internal pressure of the closed container I is determined by the set position of the flexible portion 13 and the rib 14.
, the slope and width of the flexible portion 13, the degree of flexibility of the synthetic resin making up the top cover 3, etc., so these should be selected appropriately taking into consideration various factors such as the degree of increase in internal pressure. Should.

Figure 2 shows the normal state of the capacitor C, where the external terminal installation part X on the top cover 3 is recessed downward with respect to its surroundings, and the external terminals 9 and 10 are connected to the ends of the lead wires 4 and 5, respectively. has been done. When the internal pressure of the closed container 1 rises abnormally, the pressure in the space between the temporary support 6 and the upper lid 3 also rises abnormally, and the upper lid 3 is pressed upward by this pressure, as shown in FIG. The outer edge and inner edge of the flexible portion 13 are bent in opposite directions, and the external terminal installation portion X is pushed upward. During this series of deformation processes, the flexible portion 13 is reinforced by the ribs 14, so it is difficult to deform into a wavy shape similar to the thick external terminal installation portion X, and as a result, the top cover 3 has an elastic In a state similar to a reversal motion, the external terminal 9 suddenly bulges and deforms into a truncated conical shape.
．． 10 is momentarily cut from the end of the lead wire 5.6,
Power to the capacitor element 2 is cut off.

(Effects of the Invention) According to the present invention, when the internal pressure of the sealed container abnormally increases due to dielectric breakdown of a capacitor element, the top cover is instantly bulged and deformed due to the pressure, and the external terminal is disconnected from the lead wire. Since the capacitor element is disconnected and electricity is cut off reliably to the capacitor element, explosions and other accidents can be reliably prevented. Moreover, the bulging deformation of the top cover is instantaneously and reliably performed in a state similar to an elastic reversal motion whose behavior is determined by the rigidity and setting position of the annular flexible part, and the flexible part reinforced by ribs. Since this method is less likely to cause wavy bulging deformation, the timing at which the external terminal will be disconnected from the lead wire can be predicted with high precision, improving its operating accuracy.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a capacitor according to an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of the main part of the capacitor under normal conditions, and Fig. 3 is a longitudinal cross-sectional view of the main part of the capacitor when the top cover is bulging and deformed. , Fig. 4 is a plan view of the upper lid, Fig. 5 is a longitudinal cross-sectional view of Fig. 4,
FIG. 6 is an enlarged sectional view of the main part of FIG. 4. 1... Airtight container, 2... Capacitor element, 3...
- Top lid, 4.5... Lead wire, 9.10 - External terminal, 13... Flexible part, 14... Rib, C... Capacitor, X... External terminal installation part. Figure 5

Claims (1)

[Claims] 1. A top lid that bulges and deforms when the internal pressure of the capacitor element increases is attached to the airtight container that houses the capacitor element, and an external terminal that connects to a lead wire led out from the capacitor element is provided on the top lid to prevent the bulge of the top lid. In a capacitor whose external terminal is cut off from the lead wire due to deformation, the top cover is made of synthetic resin, and a flexible part of a predetermined width that is more flexible than other parts is formed in an annular shape around the external terminal installation part of the top cover. A capacitor characterized in that ribs extending in the radial direction are integrally provided at a plurality of locations in the circumferential direction of the flexible portion.