JP2003309047A - Outer case for aluminum electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an outer case for an aluminum electrolytic capacitor, which can house the aluminum electrolytic capacitor in a narrower space by reducing a buffer space required for mounting the aluminum electrolytic capacitor to the minimum, by preventing the projection of a capacitor element in operation of an explosion-proof valve, as bulging and deformation in the top part is reduced without increasing the top plate thickness of the case for the aluminum electrolytic capacitor, and the explosion-proof valve is actuated with the prescribed pressure to prevent the explosive emission of hydrogen gas, etc. <P>SOLUTION: In the cylindrical case for the aluminum electrolytic capacitor in which the upper edge is blocked by the top part 11, the explosion-proof valve 20 is arranged on the outer surface of the top part 11, and the capacitor element is housed therein. The plate thickness of the top 11 is made gradually thinner from the peripheral edge to the center so that the outer surface of the top part 11 is concave. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an outer case used for an aluminum electrolytic capacitor.

[0002]

2. Description of the Related Art An aluminum electrolytic capacitor is one in which an aluminum foil for electrodes and insulating paper are laminated and wound, and a capacitor element impregnated with an electrolytic solution is housed in an outer case made of aluminum or the like. The outer case is sealed with a lid and the terminals are drawn out. Since hydrogen gas or the like is generated by the reaction of the electrolytic solution during use of the aluminum electrolytic capacitor, the internal pressure of the outer case rises and causes an explosion, which may adversely affect the surrounding electronic circuits. Therefore, an explosion-proof valve consisting of a groove having a cross shape is formed on the top of the outer case, and when the inner pressure of the outer case rises to a certain pressure (valve operating pressure), the groove is cut to reduce the internal pressure. It escapes and prevents the aluminum electrolytic capacitor from exploding.

However, in the aluminum electrolytic capacitor, since hydrogen gas or the like is generated and the internal pressure of the outer case rises as described above, the top of the aluminum electrolytic capacitor swells outward before the operating pressure of the explosion-proof valve is reached. It may cause deformation.
Also, when the aluminum electrolytic capacitor is used for a long time in a high temperature environment, the same bulging deformation may occur. This bulging deformation of the top causes the top to come into contact with other electronic components installed above the aluminum electrolytic capacitor, which may cause a short circuit, or the aluminum electrolytic capacitor itself is pressed from above, causing disconnection of the terminals. There are problems such as being invited.

As a measure against the bulging deformation of the top portion, if the plate thickness of the top portion of the outer case is made thicker, it becomes stronger against the internal pressure, and the bulging deformation of the top portion due to the increase of the internal pressure of the outer case is reduced. Can However, at the same time, the valve operating pressure of the explosion-proof valve becomes high, and the jetting force of hydrogen gas or the like at the time of operation of the explosion-proof valve becomes a force close to an explosion, which may adversely affect the surrounding electronic circuits. Also, while keeping the plate thickness of the top part constant, bend the top part to the inner surface side of the outer case,
When the outer surface of the top is made concave (the inner surface of the top is convex), if the inner surface of the top is made convex, it is generally stronger than the flat surface, so the internal pressure of the outer case rises. However, as the valve operating pressure of the explosion-proof valve also rises at the same time, the explosive ejection of hydrogen gas, etc. generated inside the outer case is the same as when the top plate is thickened. And may adversely affect peripheral electronic circuits.

The strength of the internal pressure when the explosion-proof valve operates,
Alternatively, depending on how the explosion-proof valve is opened, the aluminum foil of the capacitor element housed inside the aluminum electrolytic capacitor unwinds spirally from the center and protrudes out of the outer case, and is installed above the aluminum electrolytic capacitor. It may come into contact with other electronic components and cause a short circuit.

[0006]

As described above, in the aluminum electrolytic capacitor, the upper part of the outer case is swollen and deformed due to the increase of the internal pressure, the explosive ejection of hydrogen gas due to the increase of the operating pressure of the explosion-proof valve, or the This causes problems such as protrusion of the capacitor element when the explosion-proof valve operates. For this reason,
When installing an aluminum electrolytic capacitor in an electronic circuit, a buffer space is provided apart from other electronic components and circuits to reduce the effects of problems such as bulging deformation of the top, but the installation space is limited. In order to improve the performance and size of an electronic circuit, it is necessary to solve the above problems of aluminum electrolytic capacitors, minimize the required buffer space, and install aluminum electrolytic capacitors in a narrower space. It has been demanded.

In view of the above, the present invention reduces the bulging deformation of the top portion of the outer case of the aluminum electrolytic capacitor without increasing the thickness of the top portion, and prevents explosion at a predetermined pressure to prevent explosive ejection of hydrogen gas or the like. In addition to operating the valve, by preventing the capacitor element from protruding when the explosion-proof valve is operating, the buffer space required when installing the aluminum electrolytic capacitor is minimized, and the aluminum electrolytic capacitor is made a narrower space. An object is to provide an outer case of an aluminum electrolytic capacitor that can be installed.

[0008]

An outer case for an aluminum electrolytic capacitor according to the present invention has been made to solve the above-mentioned problems, and has a cylindrical shape with a top portion closed at the upper end,
In an aluminum electrolytic capacitor exterior case that has a capacitor element and has an explosion-proof valve on the outer surface of the top, the thickness of the top is gradually reduced from the edge to the center, and the outer surface of the top is made concave. It is based on an outer case for an aluminum electrolytic capacitor, which is characterized by being formed. Here, the term “cylindrical shape” includes not only a cylindrical shape having a circular cross section, but also a case where the cross section has an elliptical shape or an oval shape.

The intersection of the explosion-proof valve formed on the top may be displaced from the center of the top, and the amount of displacement may be 10% to 20% of the diameter of the top.

Further, the groove bottom of the groove forming the explosion-proof valve may be formed parallel to the inner surface of the top, and the plate thickness of the top of the groove bottom may be constant.

Furthermore, the width of the groove bottom of the groove forming the explosion-proof valve may be set to 0.1 mm to 0.15 mm, and the groove side surface may be inclined with respect to the vertical.

[0012]

According to the aluminum electrolytic capacitor exterior case 10 of the present invention, the plate thickness of the top portion 11 is gradually reduced from the edge portion toward the central portion, and the outer surface of the top portion 11 is formed in a concave shape. As a result, the top portion 11 becomes relatively recessed from the edge portion toward the center portion, and in the center portion of the top portion 11, the difference between the plate thickness at the edge portion and the plate thickness at the center portion ( It is relatively depressed by "the amount of depression".
When the internal pressure of the outer case 10 rises due to generation of hydrogen gas or the like, the top portion 11 tries to bulge outward, but as described above, the top portion 11 is recessed from the edge portion toward the central portion. Therefore, the bulge of the top portion 11 is reduced by the amount of the depression, and the bulge deformation amount is reduced by the amount of the depression in the central portion. That is, by making the outer surface of the top portion 11 concave, the bulging deformation is apparently reduced as compared with the conventional case where the outer surface of the top portion 11 is flat. Therefore,
The top portion 1 may be attached to other electronic parts or the like installed above the aluminum electrolytic capacitor, which have been generated by the bulging deformation of the top portion 11.
1 is contacted with each other to cause a short circuit or the like, or the aluminum electrolytic capacitor itself is squeezed from above to cause a wire breakage of the terminal. Does not have the bulging deformation protruding from the edge, so the above problem does not occur.

Since the thickness of the top portion 11 is gradually reduced from the edge portion toward the central portion and the outer surface of the top portion 11 is formed in a concave shape, the thickness of the top portion 11 is increased or the top portion is increased. As compared with the case where the inner surface of 11 is convex, the strength of the outer case 10 against the internal pressure does not change. Therefore, the valve operating pressure of the explosion-proof valve 20 formed in the top 11 is not higher than that in the conventional case where the outer surface of the top 11 is flat, and it is desirable to prevent explosive ejection of hydrogen gas or the like. It is possible to operate the explosion-proof valve 20 with the pressure, and there is no fear of adversely affecting the electronic circuits in the vicinity. Moreover, since the valve operating pressure of the explosion-proof valve 20 can be made constant, the protrusion of the capacitor element can be suppressed.

Intersection 2 of groove 21 constituting explosion-proof valve 20
2 is displaced from the center of the top 11, the explosion-proof valve 2
Even if 0 operates, the opening portion is not the central portion of the top 11.
The aluminum foil of the capacitor element housed inside protrudes from the center of the capacitor element, but the top part 1
Since 1 always covers the central portion of the capacitor element, it is prevented from projecting to the outside of the outer case 10. Therefore, there is no case where the capacitor element comes into contact with another electronic component or the like installed above the aluminum electrolytic capacitor to cause a short circuit or the like.

As described above, the bulging deformation of the top 11 is reduced without increasing the thickness of the top 11 of the outer case 10 of the aluminum electrolytic capacitor, and the desired pressure is used to prevent explosive ejection of hydrogen gas or the like. By operating the explosion-proof valve 20 and preventing the capacitor element from projecting during the operation of the explosion-proof valve 20, the buffer space required when installing the aluminum electrolytic capacitor is minimized, and the aluminum electrolytic capacitor is further improved. It is possible to provide an outer case of an aluminum electrolytic capacitor that can be installed in a narrow space.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An outer case 10 for an aluminum electrolytic capacitor according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged side view of an outer case 10 for an aluminum electrolytic capacitor according to the embodiment. 2 is an enlarged plan view of the top portion 11 of the outer case 10 according to the embodiment, and FIG.
3-3 is a vertical cross-sectional view showing an enlarged part of a 3-3 cross section (a vertical cross section passing through the center of the top), and FIGS. 4A, 4B, and 4C are enlargements of the top 11 of the outer case 10 according to another embodiment. A plan view, a, b, and c in FIG. 5 are enlarged vertical cross-sectional views of a part of the vertical cross-section passing through the center of the top of the outer case 10 of another embodiment, and FIG. 6 constitutes the explosion-proof valve 20. FIG. 2 is an enlarged cross-sectional view of the groove portion 21, in which the outer case 10 has a cylindrical shape whose upper end is closed by the top portion 11, and the explosion-proof valve 20 is provided on the outer surface of the top portion 11.
And an aluminum electrolytic capacitor is formed by accommodating a capacitor element.

As shown in FIG. 1, the outer case 10 for an aluminum electrolytic capacitor has a cylindrical shape with an outer diameter of 16.0 mm.
The plate thickness of the side portion 12 is 0.30 mm. As shown in FIG. 3, the top portion 11 has a plate thickness reduced from the outer surface, the inner surface of the top portion 11 is flattened, and the plate thickness is gradually reduced from the edge portion to the central portion so that the outer surface of the top portion 11 is reduced. It is formed in a concave shape. Top 11
Thickness is 0.30mm at the edge and 0.20 at the center
In mm, 0.10 mm is depressed in the central portion with reference to the edge portion, and when this is the depression amount A, the plate thickness in the central portion of the top portion 11 is thinned to secure the depression amount A. This is because the central portion of the top portion 11 is the portion that is most expanded and deformed by the pressure from the inner surface. Therefore, by reducing the plate thickness of the central portion to secure the amount of depression A, the top portion 11
The amount of protrusion with respect to the edge portion of is small.

In the case of this embodiment, the dent amount A in the central portion with respect to the edge portion is 0.10 mm, and even if the top portion 11 is swollen and deformed by the pressure from the inner surface of the top portion 11, the swollen deformation is caused by the depression. If the amount A is 0.10 mm or less, the central portion of the top portion 11 is in a state of not protruding as compared with the edge portion of the top portion 11, and the top portion 1
The bulging deformation of the central part of 1 is suppressed relatively to the edge part.

The concave shape of the outer surface of the top 11 is such that
Basically, the outer thickness of the top part 11 is made into a mortar shape as shown in FIG. 3 by linearly thinning the plate thickness from the edge part toward the center part. The same effect can be obtained by making the plate thickness of 11 curvilinearly thinner from the edge portion toward the center portion and forming the outer surface of the top portion 11 into a concave lens shape.
Further, as shown in FIG. 5b, a portion where the plate thickness of the top portion 11 is thinned linearly or curvedly from the edge portion toward the central portion,
You may combine the part which makes the board thickness of the top part 11 constant,
Further, as shown in FIG. 5c, the plate thickness of the top portion 11 may be gradually reduced to make the outer surface of the top portion 11 concave.

The concave shape of the top portion 11 is the outer case 10.
It may be formed at the same time as the drawing, or the outer case 10 having a constant plate thickness of the top 11 is formed by a drawing means or the like, and then the top 11 is formed by using a pressing means.
You may form the concave shape of.

Next, an explosion-proof valve 20 formed on the outer surface of the top portion 11
2 is formed by intersecting groove portions 21 having a constant width as shown in FIG. 2, and an intersecting portion 22 where the groove portions 21 intersect is formed by being displaced from the center of the top portion 11. The amount of displacement can be selected within a range in which the central portion of the capacitor element does not project to the outside even when the intersection 22 of the groove 21 is opened by the operation of the explosion-proof valve 20 and the operating pressure of the explosion-proof valve 20 is not increased. However, in this embodiment, the amount of displacement is 2.4 mm, which corresponds to 15% of the diameter of the top 11. Even if the diameters are different, the amount of displacement of the intersecting portion 22 is about 10 to 20% of the diameter, and 1 mm or more is secured regardless of the size of the diameter.

As shown in FIG. 2, the explosion-proof valve 20 has a cross shape in which two groove portions 21 having the same length are orthogonal to each other at the midpoint position, but other than the midpoint as shown in FIG. 4a. The cross shape may be a vertically long cross shape, a horizontally long cross shape with long and short groove portions 21 as shown in FIG. 4b, or a shape in which three or more groove portions 21 are crossed as shown in FIG. 4c.

As shown in FIG. 6, the cross-sectional shape of the groove portion 21 constituting the explosion-proof valve 20 is such that the groove bottom portion 23 is formed and the outer surface is opened. The plate thickness (groove bottom thickness B) in the groove bottom 23 is 0.1 to 0.15 mm, the width of the groove bottom 23 is 0.15 mm, and the inclination angle of the groove side surface 24 is 24 degrees from the vertical. However, the groove bottom thickness B, the width dimension of the groove bottom 23,
Since the inclination of the groove side surface 24 is closely related to the operating pressure of the explosion-proof valve 20, these dimensions depend on the thickness of the top portion 11 of the outer case 10 of the aluminum electrolytic capacitor and the desired operating pressure of the explosion-proof valve 20. It is determined and is not limited to the above dimensions.

The groove 21 forming the explosion-proof valve 20 is formed by
After forming the outer surface of the top 11 into a concave shape, the inner mold is inserted into the outer case 10 and abuts against the inner surface of the top 11, the length of the explosion-proof valve 20, and the thickness of the groove bottom 23. It is performed by a pressing die having a pressing blade corresponding to the formation of the ridge.

An aluminum electrolytic capacitor was prototyped using the outer case 10 having the above-mentioned structure, and the atmosphere was 150 ° C.
An aluminum electrolytic capacitor was placed in the environment of No. 1 and a test for measuring the bulging deformation of the top portion 11 was performed at regular intervals. At the same time, the same test was performed for an aluminum electrolytic capacitor using the conventional outer case 30 in which the outer surface of the top portion 31 is not formed in a concave shape, and the bulging deformation of the top portion 31 was compared. FIG. 7 is a graph showing the results of the test, in which the bulging deformation of the central portion with respect to the edge portion of the top portion is measured. FIG. 8a is an enlarged side view of the outer case 10 according to the embodiment after the test, and FIG. 8b is an enlarged side view of the outer case 30 of the conventional aluminum electrolytic capacitor after the test.

As a result of the above test, as shown in the graph of FIG. 7, within a certain time after the start of the test, the outer case 10 of the embodiment was tested.
Since the bulging deformation of the top of the aluminum electrolytic capacitor using was less than or equal to the amount of concave depression, it was confirmed that the center did not protrude from the edge.

After a certain period of time, the top parts 11, 31 of both aluminum electrolytic capacitors were swollen and deformed, and after 80 minutes, the top parts 1 of both aluminum electrolytic capacitors were changed.
Although the swelling deformations of Nos. 1 and 31 were constant, the swelling deformation after 80 minutes was 0.55 mm as compared with the swelling deformation of the conventional aluminum electrolytic capacitor (FIG. 8b), while the outer case 10 of the embodiment was used. In the aluminum electrolytic capacitor using (3), it was suppressed to 0.3 mm (Fig. 8a), and the bulging deformation of the top portion 11 was suppressed by 45% or more. Therefore, the bulge of the top portion 11 is reduced by the amount of the depression by setting the top portion 11 to be depressed from the edge portion toward the center portion, and the swelling deformation amount is reduced by the amount of the depression in the center portion. That is, it was confirmed that the outer surface of the top portion 11 is concave so that the bulging deformation is apparently reduced as compared with the conventional case where the outer surface of the top portion is flat.

[Brief description of drawings]

FIG. 1 is an enlarged side view of an aluminum electrolytic capacitor outer case 10 according to an embodiment.

FIG. 2 is an enlarged plan view of the top portion 11 of the outer case 10 according to the embodiment.

3 is a cross section taken along line 3-3 of FIG. 2 (a vertical cross section passing through the center of the top)
FIG. 3 is an enlarged vertical sectional view of a part of FIG.

4A, 4B and 4C are enlarged plan views of a top portion 11 of an outer case 10 according to another embodiment.

5A, 5B, and 5C are vertical cross-sectional views in which a part of the vertical cross-section passing through the center of the top is enlarged in the outer case 10 of another embodiment.

FIG. 6 is an enlarged cross-sectional view of a groove portion 21 that constitutes the explosion-proof valve 20.

FIG. 7 is a graph showing the results of the test, in which the bulging deformation of the central portion with respect to the edge portion of the top portion is measured.

8A is an enlarged side view of the outer case 10 according to the embodiment after the test, and FIG. 8B is an enlarged side view of the outer case 30 of the conventional aluminum electrolytic capacitor after the test.

[Explanation of symbols]

10 Aluminum electrolytic capacitor exterior case 11 Heaven 12 sides 20 Explosion-proof valve 21 groove 22 intersection 23 Bottom of groove 24 Groove side 30 (Conventional) Aluminum Electrolytic Capacitor Case 31 (Conventional) Top 32 (conventional) side A depression amount B groove bottom thickness

Claims (5)

[Claims] 1. A top portion 11 has a cylindrical shape with its upper end closed.
In an outer case for an aluminum electrolytic capacitor that has an explosion-proof valve 20 on the outer surface of the top portion 11 and accommodates a capacitor element, the plate thickness of the top portion 11 is gradually reduced from the edge portion to the central portion,
An outer case for an aluminum electrolytic capacitor, wherein the outer surface of the top portion 11 is formed in a concave shape. 2. An intersection 2 of the explosion-proof valve 20 formed on the ceiling 11.
2. The outer case for an aluminum electrolytic capacitor according to claim 1, wherein 2 is displaced from the center of the top portion 11. 3. The crossing 22 of the explosion-proof valve 20 is displaced from the center of the top 11, and the amount of displacement is 10% to 20% of the diameter of the top 11. External case for aluminum electrolytic capacitors. 4. A groove bottom portion 2 of a groove portion 21 constituting the explosion-proof valve 20.
The outer case for an aluminum electrolytic capacitor according to claim 1, 2 or 3, wherein 3 is formed parallel to the inner surface of the top portion 11 and the plate thickness of the top portion 11 at the groove bottom portion 23 is constant. 5. A groove bottom portion 2 of a groove portion 21 constituting the explosion-proof valve 20.
3. The width of the groove 3 is 0.1 mm to 0.15 mm, and the groove side surface 24 is inclined with respect to the vertical.
An outer case for an aluminum electrolytic capacitor as described in 2, 3, 4 or 5.