JP5392389B2 - Electrolytic capacitor - Google Patents

Description

  The present invention relates to an electrolytic capacitor, and more particularly to an electrolytic capacitor having a pressure valve that operates reliably even when the internal pressure of the capacitor is increased, even a small electrolytic capacitor.

  In an electrolytic capacitor, application of overvoltage exceeding the rated voltage generates gas inside the electrolytic capacitor, the internal pressure rises and the outer case is torn, or the sealing body that seals the opening of the outer case is detached. There is a case.

  For this reason, in an electrolytic capacitor, an explosion-proof structure is taken in order to prevent damage to the outer case and detachment of the sealing body due to a sudden rise in internal pressure. The explosion-proof structure is formed on the bottom surface of the outer case. And those formed on a sealing body for sealing an outer case. As an example of the former, when an exterior case is formed of aluminum or the like, a V-shaped pressure valve that can be opened by a specific pressure is formed on the bottom surface, and as an example of the latter, an exterior containing an electrolytic capacitor element is formed. A pressure valve composed of a thin portion is formed in the sealing body of the case.

  As a pressure valve structure provided in the sealing body 51 of the exterior case, conventionally, as shown in FIG. 7, a convex portion 53 is formed around the inner thin concave portion 52 and the thin portion 52 is hinged. When the portion 54 is formed to be thinner than the thin portion 52 and the internal gas reaches a predetermined pressure, the concave thin portion 52 is reversed by the convex 53, and the moment at the time of reversal is utilized, and the thin wall An explosion-proof structure is disclosed in which the convex portion 53 in the peripheral portion of the portion 52 comes into contact with the wall surface of the sealing body 51 and becomes a fulcrum, and the peripheral portion of the thin portion 52, mainly the hinge portion 54, is destroyed to escape the internal gas. (Patent Document 1).

  Further, as shown in FIG. 8, a circular large-area thin-walled portion 62 near the center of the sealing body 61, a small-area thin-walled portion 63 adjacent to the large-area thin-walled portion 62, and the center of the small-area thin-walled portion 63 are large. A thick-walled portion 64 that connects a predetermined range in the thin-walled area is provided, and a gap between the periphery of the large-area thin-walled portion 62 and the periphery of the thick-walled portion 64 is formed in a concave shape toward the inside of the capacitor. An explosion-proof structure is disclosed in which a small-area thin-walled portion 63 is provided with a hinge function via the thick-walled portion 64 (Patent Document 2).

Japanese Utility Model Publication No. 60-41722 Japanese Utility Model Publication No. 60-23970

  By the way, it is strongly desired to reduce the size of the electrolytic capacitor, and when a pressure valve is provided on the bottom surface of the outer case, a predetermined region is required between the bottom surface of the outer case and the substrate as an operation region of the pressure valve. This is an impediment to downsizing of electrolytic capacitors.

Then, forming a pressure valve in the sealing body of an exterior case is examined.
By the way, when the internal pressure of the electrolytic capacitor increases, the pressure applied to the pressure valve is expressed by the following equation.
F = PA
(F is the force applied to the pressure valve, P is the internal pressure of the electrolytic capacitor, and A is the cross-sectional area of the pressure valve)
That is, when the cross-sectional area of the pressure valve is increased, the operating pressure of the pressure valve is reduced.

Usually, in a relatively large electrolytic capacitor, the outer diameter of the outer case and the outer diameter of the sealing body are large, so that a sufficient cross-sectional area of the pressure valve formed on the bottom surface of the outer case and the sealing body can be secured. Therefore, when the internal pressure of the electrolytic capacitor rises, the pressure applied to the pressure valve is high, and when the internal pressure rises, the pressure valve operates to release the internal gas.
On the other hand, in a small electrolytic capacitor having a diameter of 15 mm or less, the sealing body has a lead wire through hole on the cathode side and the anode side on the sealing body, and a necessary predetermined region for caulking the exterior case. The cross-sectional area is limited.

  Accordingly, the pressure valve has a small cross-sectional area, and a high internal pressure is required to operate the pressure valve. If the internal pressure of the outer case increases, the sealing state between the sealing body and the outer case cannot be maintained, and therefore, the pressure valve does not operate and the sealing body is detached from the outer case.

  Therefore, there is a demand for a small pressure valve with a low operating pressure. However, in the explosion-proof structure disclosed in Patent Document 1, a thin-walled portion 52 having a concave inner surface that is reversed by an increase in internal pressure, and a convex portion 53 formed in the periphery thereof. In order to form the thin-walled hinge portion 54 in the elastic sealing body, the explosion-proof structure is formed on the sealing body 51 by a mold simultaneously with the molding of the sealing body 51. Therefore, it is difficult to reduce the size of the explosion-proof structure itself, and the explosion-proof structure of such a complicated structure is formed in an elastic sealing body. It was difficult to do.

  In addition, the explosion-proof structure disclosed in Patent Document 2 has a plurality of thin-walled portions 62 and 63 and a thick-walled portion 64 formed across the thin-walled portion. It requires an area and is not suitable for the explosion-proof structure of a small electrolytic capacitor, and is a complicated structure, and it is difficult to mold the elastic sealing body with a mold.

  In addition, instead of the explosion-proof structure of Patent Document 1 and Patent Document 2, a pressure valve including only a thin portion can be formed on the elastic sealing body. However, since the thickness of the thin portion is limited, the pressure valve The operating pressure cannot be lowered. Therefore, when the internal pressure rises, the entire thin portion is maintained in an expanded and deformed state, and when the sealing force between the exterior case and the sealing body is small, such as a small electrolytic capacitor, the sealing body is It may come off from the outer case.

  Therefore, the present invention reduces the operating pressure of the pressure valve, and even if the formation area of the pressure valve is limited, such as a small electrolytic capacitor, there is no detachment of the elastic sealing body from the outer case, and the It is an object of the present invention to provide an electrolytic capacitor in which a pressure valve that operates in a simple manner is formed accurately and easily.

  The electrolytic capacitor of the present invention that has solved the above problems comprises a capacitor element, a bottomed cylindrical outer case that houses the capacitor element, and an elastic sealing body that seals the opening of the outer case, The elastic sealing body includes a pressure valve including a thin wall portion made of rubber and a non-deformable portion that is provided near the center of the thin wall portion and moves to the outside of the capacitor when the internal pressure rises. When moving up, it moved to the outside of the capacitor, and the thin portion inclined from the outside of the capacitor to the inside of the capacitor, and stress was concentrated near the boundary with the inner wall of the pressure valve or near the boundary with the non-deformed portion. It is characterized by.

  According to this, since the non-deformation part is provided near the center of the thin part constituting the pressure valve, the non-deformation part is moved to the outside of the capacitor with little deformation when the internal pressure rises. The thin portion between the inner wall of the pressure valve and the non-deformed portion can be extended to concentrate the stress, and the operating pressure of the pressure valve can be lowered.

  In addition, this pressure valve can be easily configured only by forming a non-deformed portion near the center of the thin-walled portion, and can be formed only by the diameter of the thin-walled portion, so that it can be used as an elastic sealing body for small electrolytic capacitors. Can also be easily applied.

  For example, after forming the thin-walled portion with a mold, the thin-walled portion is formed even if the non-deformable plate material is pasted around the center of the thin-walled portion or the same material as the elastic sealing body. A concave portion may be formed on one surface of the mold to be molded, and the pressure valve can be easily molded.

  Further, the non-deformation part of the pressure valve is formed on both surfaces of the thin part. According to this, the strength of the non-deformed portion increases, and when the internal pressure rises, the non-deformed portion can be moved to the outside of the capacitor in a state where the deformation is extremely small, and accordingly, between the inner wall of the pressure valve and the non-deformed portion. It is possible to efficiently concentrate the stress on the thin-walled portion and reliably break it, thereby releasing the internal gas.

  Further, the non-deformable portion of the pressure valve is a thick portion made of the same material as the thin portion. According to this, simultaneous molding can be easily performed only by providing a recess in a part of a mold for molding the thin portion, and the non-deformable portion does not come off.

  Moreover, the non-deformation part of the said pressure valve consists of spherical shapes. According to this, since the internal pressure is almost uniformly applied to the non-deformed portion, the non-deformed portion can be moved to the outside of the capacitor with very little deformation, and between the inner wall of the pressure valve and the non-deformed portion. It is possible to efficiently concentrate the stress on the thin-walled portion and to break it reliably and to release the internal gas. Further, at the time of forming the pressure valve, since the non-deformed portion is spherical when the non-deformed portion is peeled off from the mold, the non-deformed portion can be easily peeled from the die, and defective products in the manufacturing process are reduced.

  Further, the non-deformable portion of the pressure valve is characterized in that a non-deformed plate material is disposed in the vicinity of the center of the thin portion. According to this, by arranging the non-deformable plate material in the vicinity of the center of the thin portion, the thin portion constituting the pressure valve that has been used conventionally can be used, and a complicated change of the process is unnecessary.

  In addition, a plurality of the pressure valves are provided symmetrically with respect to the center of the elastic sealing body. According to this, when the opening portion of the outer case is caulked and sealed by the curling process, since the pressure valve is arranged at a point-symmetrical position from the center in the elastic sealing body, there is a space through which the internal gas passes. Since they are arranged in a point symmetry, the curling process does not become uneven.

  The thin portion of the pressure valve is formed on the outside of the capacitor from the caulking position on the side surface of the exterior case. According to this, since the thin portion of the pressure valve is displaced from the caulking position of the outer case, the thin portion of the pressure valve is not deformed by the caulking pressure, and there is no problem such as malfunction of the pressure valve.

  According to the present invention, the pressure valve provided in the elastic sealing body is composed of a thin portion and an undeformed portion that is provided near the center of the thin portion and moves to the outside of the capacitor when the internal pressure increases. Since the structure is simple and can be formed in a small area, even a small electrolytic capacitor can be easily provided on its elastic sealing body, and when the internal pressure rises, the non-deformed part is moved to the outside of the capacitor. It can be broken by concentrating stress on the thin-walled part, the operating pressure of the pressure valve can be lowered, the elastic sealing body is not detached from the outer case, and the pressure valve is operated reliably to release the internal gas be able to.

It is sectional drawing which shows the electrolytic capacitor of this invention. It is a top view which shows the electrolytic capacitor of this invention. It is a top view which shows the electrolytic capacitor of this invention. It is sectional drawing which shows the pressure valve shape of the electrolytic capacitor of this invention. It is sectional drawing which shows the pressure valve shape of the electrolytic capacitor of this invention. It is sectional drawing which shows the state in which the internal pressure was provided to the pressure valve of the electrolytic capacitor of this invention. (A), (b) is sectional drawing which shows the pressure valve shape of the conventional electrolytic capacitor. (A) is a top view which shows the pressure valve shape of the conventional electrolytic capacitor. (B), (c) is sectional drawing which shows the pressure valve shape of the conventional electrolytic capacitor.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a process of mounting a cap on a capacitor element and filling an insulating resin material into a cap housing portion in an electrolytic capacitor according to an embodiment of the present invention. FIG. 2 shows a cap attached to the capacitor element in the electrolytic capacitor of the embodiment of the present invention. FIG. 3 shows a cross-sectional view of an electrolytic capacitor according to an embodiment of the present invention.

  In FIG. 1, an outer case 3 is formed by molding a metal plate such as aluminum, and has a bottomed cylindrical shape, and is formed into a circular shape, an elliptical shape, an oval shape, a rectangular shape according to the shape of the capacitor element 2 to be stored. The Capacitor element 2 is formed in a shape such as a circle, an ellipse, an oval, a square, etc. by winding or laminating electrode foils on the anode side and the cathode side via an electrically insulating separator, and from the end face of capacitor element 2 The lead wires 5 connected to the respective electrode foils are led out, and the lead wires 5 penetrate the elastic sealing body 4 and are drawn out of the outer case 3.

  The elastic sealing body 4 is formed of a gas-tight elastic material such as rubber in a shape that matches the opening of the outer case 3 and forms a circular or square columnar body. Two semicircular step portions 6 are formed apart from each other. When the curling process is performed to seal the opening of the outer case 3, the stepped portion 6 prevents a step from the top of the curling portion from occurring and stabilizes the installation on a printed circuit board or the like. Therefore, it is formed at a height that matches the top of the curling portion of the outer case 3.

The step portion 6 of the elastic sealing body 4 has a through hole for drawing out the lead wire 5, and prevents a short circuit due to contact with the curling portion of the outer case 3. As shown in FIG. 2, a pressure valve 7 is formed in a region where the step portion 6 is not formed in the vicinity of the center of the elastic sealing body 4, and the surface of the step portion 6 of the elastic sealing body 4 is placed on the printed circuit board. When brought into close contact with the surface, a space between the step 6 and the step 6 becomes a passage through which the internal gas passes when the pressure valve 7 is operated.
The pressure valve 7 may be provided at substantially the center position of the elastic sealing body 4, or a plurality of pressure valves 7 may be provided symmetrically with respect to the center of the elastic sealing body 4 as shown in FIG.

  The pressure valve 7 includes a thin portion 8 and a non-deformable portion 9 that is provided near the center of the thin portion 8 and moves to the outside of the capacitor when the internal pressure increases. In addition, when sealing the exterior case 3 by curling the side surface of the exterior case 3 corresponding to the side surface of the elastic sealing body 4 together with the curling process of the open end of the exterior case 3, the thin wall It is preferable that the portion 8 is shifted from the curling position on the side surface of the outer case 3 and provided on the outer side of the capacitor. The non-deformable portion 9 provided in the vicinity of the center of the thin portion 8 is more rigid than the thin portion 8 or has a property of being difficult to deform. Note that “non-deformation” means that when the non-deformation portion 9 moves to the outside of the capacitor due to internal pressure, stress is applied to the thin-wall portion 8 that is a fracture portion between the inner wall of the pressure valve 7 and the non-deformation portion 9. The deformation of the non-deformation part 9 to the extent is included.

  The non-deformable portion 9 is made of the same material as the thin-walled portion 8, and has a cylindrical shape, a prismatic shape, or a spherical shape protruding from the thin-walled portion 8, or a non-deformed plate material such as aluminum when a different material is used. The metal plate 11 etc. are comprised. These non-deformable portions 9 need only be disposed near the center of the thin portion 8 and formed on at least one surface of the thin portion 8, but are preferably disposed on both sides. As shown in the drawing, when a metal plate 11 such as aluminum is disposed on the thin portion 8, it is preferable to provide protrusions 12 that bite into the thin portion at both ends of the metal plate.

As shown in FIG. 5, the width t <b> 1 or t <b> 2 of the thin-walled portion 8 that is a fracture portion between the inner wall of the pressure valve 7 and the non-deformed portion 9 is preferably 0.4 mm or less. If the thickness exceeds 0.4 mm, the thin-walled portion 8 is in an expanded state without breaking, so that the operating pressure of the pressure valve 7 is increased, and in the small electrolytic capacitor 1, the elastic sealing is performed before the pressure valve 7 is operated. Problems such as the body 4 detaching occur.
Further, the thickness of the thin portion 8 is preferably 0.3 mm or less, and if it exceeds 0.3 mm, there is a problem that the pressure valve 7 is difficult to operate when the internal pressure is increased, and the elastic sealing body 4 is detached.

  The pressure valve 7 is manufactured by molding at the same time as the elastic sealing body 4 is molded. This is obtained by molding performed by pressing two molds from both the front and back surfaces of the rubber plate as a raw material of the elastic sealing body 4. The two molds include a lead wire 5 through hole projection, a stepped portion recess, a thin portion 8 projection for providing a pressure valve 7 near the center of the elastic sealing body 4, and the projection. A cylindrical, prismatic, or spherical concave portion for forming the non-deformable portion 9 is provided on the top surface. The elastic sealing body 4 is molded by forming a rubber plate as a sealing body material between the molds and peeling the mold. When the non-deformation portion 9 of the pressure valve 7 is spherical 10 at the time of peeling, it does not stick to the mold, and peeling becomes easy and defective products are reduced.

  As another method, the pressure valve 7 is formed by sandwiching a rubber plate with a protrusion for the thin portion 8 that does not have a recess for forming the non-deformable portion 9 as described above in the mold, The non-deformed portion 9 can also be formed by providing a thin-wall portion 8 on which the non-deformable portion 9 is not formed and arranging a non-deformable plate material on the thin-wall portion 8.

Next, the operation of the pressure valve 7 will be described.
As shown in FIG. 6, when a large current flows through the electrolytic capacitor 1 to generate internal gas and the internal pressure of the capacitor increases, this internal pressure is applied to the thin portion 8 and the non-deformed portion 9 of the pressure valve 7. At this time, the non-deformed portion 9 moves to the outside of the capacitor with little deformation due to the internal pressure, and due to this movement, stress concentrates on the thin-walled portion 8 between the inner wall of the pressure valve 7 and the non-deformed portion 9. Then, the thin portion 8 is broken near the boundary with the inner wall of the pressure valve 7 or near the boundary with the non-deformed portion 9, and the internal gas is released to the outside of the capacitor.
As described above, the non-deformable portion 9 is moved to the outside of the capacitor with little deformation, so that the thin portion 8 between the inner wall of the pressure valve 7 and the non-deformable portion 9 is extended to concentrate stress reliably. Therefore, the operating pressure of the pressure valve 7 can be lowered and downsizing can be realized.

  Next, examples of the present invention will be described.

Example 1
The electrolytic capacitor of Example 1 has a rated voltage of 300 V, a capacitance of 5 μF, and a size φ5 × L16 mm. The pressure valve includes a thin portion near the center of the elastic sealing body and a non-deformable portion that is provided near the center of the thin portion and moves to the outside of the capacitor when the internal pressure increases. The non-deformed portion is made of the same material as the thin-walled portion and is substantially spherical. As for the size of the pressure valve, the diameter of the thin portion is 1.0 mm, the thickness of the thin portion is 0.2 mm, the width of the thin portion is 0.2 mm, and the thickness of the non-deformed portion is 0.6 mm.

(Example 2)
In the electrolytic capacitor of Example 2, the pressure valve of Example 1 is provided with two pressure valves in a point-symmetrical position from the center of the elastic sealing body.

(Example 3)
In the electrolytic capacitor of Example 3, instead of the non-elastic part of the pressure valve of Example 1, a non-deformed part was formed by sticking an aluminum plate having a thickness of 0.1 mm on both surfaces near the center of the thin part. It is.

Example 4
In the electrolytic capacitor of Example 4, the pressure valve of Example 3 is provided with two pressure valves in a point-symmetric position from the center of the elastic sealing body.

(Conventional example 1)
The electrolytic capacitor of Conventional Example 1 is the same as that of Example 1 except that the pressure valve does not use a thin part that does not form a non-deformed part.

About the said Examples 1-4 and the prior art example 1, the following pressure valve action | operation tests were done.
A voltage having a polarity opposite to the standard polarity was applied at 1 A and 50 V between the lead wires of the electrolytic capacitor, and the state of the electrolytic capacitor after voltage application was observed. The results are shown in Table 1.

  As is clear from Table 1, in the electrolytic capacitors of Examples 1 to 4, all the pressure valves operated normally, whereas in Conventional Example 1, the pressure valve did not operate normally, and the internal pressure of the electrolytic capacitor was not obtained. As a result, the elastic sealing body itself has detached from the outer case. In Example 1 and Example 3 in which one pressure valve was provided, some of the elastic sealing bodies were swollen, and although there was little influence on the implementation, two pressure valves were provided. Examples 2 and 4 are better. As is clear from the above test results, the pressure valve structure of the present invention can reduce the operating pressure of the pressure valve, and therefore, even with a small electrolytic capacitor, the normal operation of the pressure valve can be obtained and elastic. It can be seen that problems such as removal of the sealing body can be avoided.

DESCRIPTION OF SYMBOLS 1 Electrolytic condenser 2 Capacitor element 3 Exterior case 4 Elastic sealing body 5 Lead wire 6 Step part 7 Pressure valve 8 Thin part 9 Nondeformation part 10 Spherical nondeformation part 11 Metal plate 12 Protrusion

Claims (5)

A capacitor element;
A bottomed cylindrical outer case for storing the capacitor element;
It consists of an elastic sealing body that seals the opening of the exterior case,
The elastic sealing body is a thin portion made of rubber,
A pressure valve is provided near the center of the thin wall portion, and includes a non-deformable portion that moves to the outside of the capacitor when the internal pressure rises.
The non-deformed portion moves to the outside of the capacitor when the internal pressure rises,
The thin portion is inclined from the outside of the capacitor to the inside of the capacitor,
An electrolytic capacitor characterized in that stress is concentrated near a boundary with an inner wall of the pressure valve or near a boundary with the non-deformed portion. The electrolytic capacitor according to claim 1, wherein the non-deformed portion of the pressure valve is formed on both surfaces of the thin portion. The electrolytic capacitor according to claim 1, wherein the non-deformable portion of the pressure valve is spherical. The electrolytic capacitor according to any one of claims 1 to 3, wherein a plurality of the pressure valves are provided point-symmetrically from the center of the elastic sealing body. The electrolytic capacitor according to any one of claims 1 to 4, wherein a thin portion of the pressure valve is formed on an outer side of the capacitor from a caulking position on a side surface of the outer case.

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