JP2013077782A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor which allows a user to adjust a valve operation pressure at which a safety valve is operated and improves the valve operability of the safety valve.SOLUTION: An electrolytic capacitor has an exterior case 2 forming a cup shape and is provided with a safety valve 9 forming a recessed shape at a side peripheral part 7 of the exterior case 2. In the electrolytic capacitor, when the internal pressure of the exterior case 2 is increased and stress is applied to the side peripheral part 7 and a bottom part 8 of the exterior case 2, stress is applied in the expansion direction due to the internal pressure in a region F1 of the side peripheral part 7 and stress is applied in the contraction direction due to the expansion of the bottom part 8, which is caused by the internal pressure, in a region F2 of the side peripheral part 7. The safety valve 9 is provided at a border part L between the first region F1 and the second region F2.

Description

  The present invention relates to an electrolytic capacitor having an outer case having a bottomed cylindrical shape and provided with a safety valve in the outer case.

  In the electrolytic capacitor, a leakage current flows during use, and this leakage current generates hydrogen gas inside the electrolytic capacitor. And since the electrolytic capacitor has a sealed structure, the internal pressure rises due to the generation of hydrogen gas inside the electrolytic capacitor, and in the worst case, the entire outer case of the electrolytic capacitor bursts, and the fragments are surrounded by the surroundings. There is a risk of splashing. In order to prevent this rupture, the electrolytic capacitor is formed with a mechanical fragile portion such as a groove on the bottom and side surfaces of the outer case, and when the internal pressure rises, the outer case breaks along the groove. Thus, a safety valve is provided that opens the valve to release hydrogen gas inside the outer case to the outside and prevent the entire outer case from bursting.

  As a conventional example in which a safety valve is provided on the side surface of an outer case, there is one in which an explosion-proof portion (safety valve) is provided in a throttle portion (clamping portion) of a cylindrical outer cylinder case (outer case) (see, for example, Patent Document 1) . In some cases, a groove-shaped explosion-proof portion (safety valve) is formed in the flat surface portion of the flat case (exterior case) (see, for example, Patent Document 2).

Japanese Utility Model Publication No. 54-172267 Japanese Utility Model Publication No. 62-37917

  However, in the capacitor described in Patent Document 1, since the elastic sealing body formed of rubber or the like is in the throttle portion (caulking portion), when the internal pressure of the outer cylinder case (exterior case) increases, Stress applied to the outer case is difficult to be applied to the explosion-proof portion (safety valve), and the valve operability is deteriorated. In addition, the drawn portion is a portion whose thickness is reduced by drawing, and it is difficult to form an explosion-proof portion for this drawn portion.

  Further, in the capacitor described in Patent Document 2, the valve operating pressure, which is the internal pressure when the explosion-proof part (safety valve) is opened, is adjusted by the length and depth of the groove of the explosion-proof part. ing. When this valve operating pressure is set low, the depth of the groove must be formed very deep, resulting in variations in valve operating pressure due to manufacturing errors. In addition, unlike the cylindrical case, the flat case (exterior case) is easily deformed in the flat plane part that is structurally weak against internal pressure. There is a problem that it is difficult to adjust the pressure.

  The present invention has been made paying attention to such problems, and provides an electrolytic capacitor that can easily adjust the valve operating pressure at which the safety valve operates and can improve the valve operability of the safety valve. Objective.

  When the internal pressure of the electrolytic capacitor is increased, the bottom surface of the outer case, which is a flat surface, is most easily deformed. Therefore, a safety valve has been conventionally arranged on the bottom surface of the outer case. However, the inventor found that the most deformable part when the internal pressure rises is the bottom part of the exterior case, but the most stressed part is not the bottom part of the exterior case, but the region of the case side peripheral part where the stress is applied in the expansion direction by the internal pressure And the knowledge that it is a boundary site | part of the area | region of the case side peripheral part to which stress is applied to a contraction direction by expanding a bottom part by internal pressure.

  This invention is made | formed based on the said knowledge, and can provide an electrolytic capacitor with favorable valve operativity by providing a safety valve in a boundary part.

In order to solve the above problems, the electrolytic capacitor of the present invention is:
In an electrolytic capacitor having an outer case having a bottomed cylindrical shape and providing a safety valve having a concave shape on the side periphery of the outer case,
When the internal pressure of the exterior case is increased and stress is applied to the side periphery and bottom of the exterior case, the region of the side periphery where stress is applied in the expansion direction by the internal pressure, and the bottom is expanded by the internal pressure. Thus, the safety valve is provided at a boundary portion between the region of the side peripheral portion to which stress is applied in the contraction direction.
According to this feature, the boundary part of the side periphery of the exterior case is a part where the stress applied in the expansion direction and the stress applied in the contraction direction are reversed when the internal pressure of the exterior case increases. Since the exterior case is easily sheared due to the influence, the valve operability of the safety valve can be improved by providing a safety valve at the boundary portion. Since this boundary part is on the side near the bottom of the exterior case in the outer case side peripheral portion, the safety valve is provided on the side near the bottom of the exterior case. Further, when the safety valve is formed, it is easy to adjust the valve operating pressure by appropriately setting the depth of the concave safety valve.

The electrolytic capacitor of the present invention is
The safety valve is provided along a circumferential direction of the side peripheral portion.
According to this feature, by providing a safety valve at the boundary portion along the circumferential direction of the side periphery of the exterior case, stress due to the increase in the internal pressure of the exterior case is applied to the entire safety valve, improving the valve operability of the safety valve Can be made. Furthermore, when the safety valve is formed, it is easy to adjust the valve operating pressure by setting the length of the safety valve.

The electrolytic capacitor of the present invention is
The safety valve is provided over a range of approximately one half or more in the circumferential direction of the side peripheral portion.
According to this feature, since most of the stress applied in the circumferential direction (circumferential direction of the cylinder) is used for the valve operation of the safety valve at the boundary portion of the side peripheral portion, variation in the valve operating pressure is reduced, and the safety valve Valve operability can be improved.

The electrolytic capacitor of the present invention is
The thickness dimension of the outer case at the position of the safety valve is 0.1 mm or more.
According to this feature, the strength of the outer case against the internal pressure can be maintained, and the safety valve can be prevented from being inadvertently operated at an internal pressure equal to or lower than the valve operating pressure.

The electrolytic capacitor of the present invention is
The safety valve is provided in a portion within 15 mm from the bottom in the side periphery.
According to this feature, the boundary part in the side periphery of the outer case is within 15 mm from the bottom, and the safety valve is provided at a part within 15 mm from the bottom so that the safety valve is located at the position assumed to be the boundary part. As a result, it is possible to improve the valve operability of the safety valve. In addition, the position of 10 mm from the bottom is the optimal arrangement position of the safety valve, and the valve operability is good.

The electrolytic capacitor of the present invention is
A height dimension from the bottom to the opening in the outer case is 25 mm or more, and a diameter of the outer case is 35 mm or more.
According to this feature, in an exterior case having a height dimension of 25 mm or more and a diameter of 35 mm or more, a part within 15 mm from the bottom part in the side peripheral part is a boundary part, and a safety valve is provided in this boundary part. By providing, the valve operability of the safety valve can be improved.

1 is a partially longitudinal front view showing an electrolytic capacitor in Example 1. FIG. It is a vertical side view which shows the safety valve formed in the exterior case. It is a vertical side view which shows the safety valve when the internal pressure of an exterior case is raised. It is a vertical side view which shows the safety valve in Example 2. FIG. It is a vertical side view which shows the safety valve in Example 3. FIG. It is a vertical side view which shows the safety valve in Example 4. FIG. 10 is a partially longitudinal front view showing an electrolytic capacitor according to Example 5. FIG. 10 is a partially longitudinal front view showing an electrolytic capacitor in Example 6. FIG.

  EMBODIMENT OF THE INVENTION The form for implementing the electrolytic capacitor which concerns on this invention is demonstrated below based on an Example.

  The electrolytic capacitor according to Example 1 will be described with reference to FIGS. Reference numeral 1 in FIG. 1 denotes an electrolytic capacitor to which the present invention is applied. This electrolytic capacitor 1 has an outer case 2 having a substantially bottomed cylindrical shape, and an opening 3 is formed at one end of the outer case 2, and the opening 3 is a sealing body 4 made of a synthetic resin and having a substantially cylindrical shape. Is blocked. The exterior case 2 is made of a metal material such as aluminum, and the sealing body 4 is made of an elastic material having elasticity such as resin rubber.

  As shown in FIG. 1, this electrolytic capacitor 1 has a capacitor element 5 in which a plurality of electrode foils formed of aluminum are wound or laminated with a separator interposed therebetween, and the capacitor element 5 is packaged together with an electrolytic solution. Case 2 is housed. Two lead terminals 6, an anode and a cathode, are connected to the capacitor element 5.

  As shown in FIGS. 1 and 2, the outer case 2 is made of a metal material such as aluminum having a purity of 99.7%. At the time of manufacturing the outer case 2, the aluminum plate material is pressed by a mold and formed into a substantially bottomed cylindrical shape having the side peripheral portion 7 and the bottom portion 8. Then, the capacitor element 5 described above is inserted from the opening 3 of the outer case 2, and the vicinity of the opening 3 is crimped in a state where the opening 3 of the outer case 2 is closed by the sealing body 4. The inside is sealed.

  Moreover, the height dimension from the bottom part 8 to the opening part 3 in the exterior case 2 in a present Example is about 50 mm, and the diameter of the exterior case 2 is 35 mm. In addition, the height dimension of the exterior case 2 should just be 25 mm or more, and the diameter of the exterior case 2 should just be 35 mm or more. Furthermore, the thickness dimension of the side peripheral part 7 of the exterior case 2 in the present embodiment is approximately 0.35 mm, and the thickness dimension of the bottom part 8 is approximately 0.7 mm.

  In addition, a safety valve 9 formed in a concave shape by pressing or the like is provided in a portion near the bottom portion 8 of the side peripheral portion 7 of the exterior case 2. The safety valve 9 in the present embodiment is a single groove extending linearly along the circumferential direction of the side peripheral portion 7 of the outer case 2, and the safety valve 9 is formed in the height direction (cylindrical of the outer case 2). It is formed so as to be substantially orthogonal to (axial direction).

  And the depth dimension of the recessed part of the safety valve 9 is about 0.25 mm. The thickness dimension S (see FIG. 2) of the outer case 2 at the position of the safety valve 9 only needs to be 0.1 mm or more, and the depth dimension of the recess may be appropriately changed when the safety valve 9 is formed. Further, by adjusting the depth dimension of the recess of the safety valve 9, the valve operating pressure, which is the internal pressure of the outer case 2 when the safety valve 9 is opened, can be adjusted.

  The safety valve 9 is provided in a range of approximately one half or more in the circumferential direction of the side peripheral portion 7 of the outer case 2. In this embodiment, the safety valve 9 is a circle of the side peripheral portion 7. It is provided over a range of approximately 5/8 in the circumferential direction. Further, the safety valve 9 may be formed over the entire circumference of the side peripheral portion 7 of the outer case 2. Furthermore, the valve operating pressure of the safety valve 9 can be adjusted by adjusting the circumferential dimension of the safety valve 9.

  In this embodiment, the distance D from the bottom surface of the bottom 8 to the safety valve 9 is about 10 mm in the side peripheral portion 7 of the outer case 2. In addition, the safety valve 9 should just be the range within 15 mm from the bottom face of the bottom part 8 in the side peripheral part 7 of the exterior case 2. FIG. The reason for this will be described later.

  By the way, in the electrolytic capacitor 1, a leakage current flows during use. This leakage current generates hydrogen gas inside the electrolytic capacitor, and the generation of this hydrogen gas raises the pressure inside the outer case 2. Since the bottom 8 of the outer case 2 has a flat plate shape, it is deformed so as to bulge outward as the internal pressure of the outer case 2 increases as shown in FIG.

  The inventor of the present invention, in the side peripheral portion 7 of the outer case 2, the region F1 of the side peripheral portion 7 where stress is applied in the expansion direction in which the diameter of the outer case 2 is expanded by the internal pressure, and the bottom 8 is expanded by the internal pressure. Thus, it was found that two regions F1 and F2 of the side peripheral portion 7 where stress is applied in the contraction direction in which the diameter of the outer case 2 contracts are generated. Then, it is recalled that the safety valve 9 is arranged at a position assumed to be a boundary portion L between the two regions F1 and F2.

  Thus, the boundary part L of the side periphery 7 of the outer case 2 is a part where the stress applied in the expansion direction and the stress applied in the contraction direction are reversed when the internal pressure of the outer case 2 rises. Since the outer case 2 is easily sheared by the influence of the stress, the valve operability of the safety valve 9 can be improved by providing the safety valve 9 at the boundary portion L. Since the boundary portion L is on the side near the bottom 8 of the exterior case in the outer case side peripheral portion, the safety valve 9 is provided on the side close to the bottom 8 of the exterior case. Further, when the safety valve is formed, it is easy to adjust the valve operating pressure by appropriately setting the depth of the concave safety valve 9 and the like.

  In addition, by providing the safety valve 9 near the bottom 8 of the side peripheral portion 7 of the outer case 2, a protrusion (not shown) for fixing the capacitor element 5 can be provided on the bottom 8 of the outer case 2. Thus, the heat generated by the capacitor element 5 can be transmitted to the outer case 2 by the protrusions to improve heat dissipation.

  Further, by providing a safety valve at the boundary portion L along the circumferential direction of the side peripheral portion 7 of the outer case 2, stress due to an increase in internal pressure of the outer case 2 is applied to the entire safety valve, and the valve operability of the safety valve 9 is improved. Can be improved. Furthermore, when the safety valve 9 is formed, the valve operating pressure can be easily adjusted by setting the length of the safety valve 9 and the like.

  In addition, since the safety valve 9 is provided over a range of approximately one half or more in the circumferential direction of the side circumferential portion 7, the circumferential direction (cylindrical of the cylinder) Most stress applied in the circumferential direction) can be utilized for opening (valve operation) of the safety valve 9, and the valve operability of the safety valve 9 can be improved.

  Further, the thickness dimension of the outer case 2 at the position of the safety valve 9 is 0.1 mm or more, so that the strength against the internal pressure of the outer case 2 is maintained, and the safety valve 9 is inadvertently at an internal pressure equal to or lower than the valve operating pressure. Can be prevented from being operated.

  Moreover, the boundary part L in the side peripheral part 7 of the exterior case is within 15 mm from the bottom surface of the bottom part 8, and the safety valve 9 is provided in the part within 15 mm from the bottom part 8, so that the safety valve 9 is separated from the boundary part L. It comes to be arrange | positioned appropriately in the assumed position and the valve operativity of the safety valve 9 can be improved. Note that the optimal position of the safety valve 9 is 10 mm from the bottom.

  Further, in the exterior case 2 having a height dimension of 25 mm or more and a diameter of 35 mm or more, a part within 15 mm from the bottom 8 in the side peripheral part 7 is a boundary part L. By providing the safety valve 9, the valve operability of the safety valve 9 can be improved.

  Next, an example of an experiment conducted by the inventor is shown below. Table 1 shows the valve operating pressure when the circumferential length of the safety valve 9 is changed. In this experiment, the height dimension from the bottom 8 to the opening 3 in the exterior case 2 is approximately 50 mm, and the diameter of the exterior case 2 is 35 mm. Furthermore, the thickness dimension of the side peripheral portion 7 of the outer case 2 is approximately 0.35 mm, and the thickness dimension of the bottom portion 8 is approximately 0.7 mm. And the depth dimension of the recessed part of the safety valve 9 is about 0.25 mm. The safety valve 9 is provided at a position 10 mm from the bottom surface of the bottom portion 8 in the side peripheral portion 7 of the exterior case 2.

  As shown in Table 1, when the safety valve 9 was provided over a substantially quarter range in the circumferential direction of the side peripheral portion 7 of the exterior case 2, the safety valve 9 did not operate. Further, when the safety valve 9 was provided over a range of approximately one third in the circumferential direction of the side peripheral portion 7 of the outer case 2, the safety valve 9 operated at an internal pressure of 2.5 MPa. Further, when the safety valve 9 was provided over a range of about one half in the circumferential direction of the side peripheral portion 7 of the outer case 2, the safety valve 9 operated at an internal pressure of 1.2 MPa. Further, when the safety valve 9 was provided over a range of about 5/8 in the circumferential direction of the side peripheral portion 7 of the outer case 2, the safety valve 9 operated at an internal pressure of 1.0 MPa. Moreover, when the safety valve 9 was provided over the range of about 2/3 in the circumferential direction of the side peripheral part 7 of the exterior case 2, the safety valve 9 operated with an internal pressure of 0.8 MPa. Moreover, when the safety valve 9 was provided over the range of about 3/4 in the circumferential direction of the side peripheral part 7 of the exterior case 2, the safety valve 9 operated with an internal pressure of 0.8 MPa.

  As shown in the experimental results, the safety valve 9 operates (opens) at an appropriate internal pressure (valve operating pressure) as long as it is in a range of approximately one half or more in the circumferential direction of the side peripheral portion 7 of the outer case 2. You can see that

  As shown in FIG. 4, in the safety valve 9a according to the second embodiment, when the safety valve 9a is recessed by pressing the side peripheral portion 7 of the outer case 2, the side peripheral portion 7 of the outer case 2 is disposed on the inner surface. Projected to the side. In addition, although the thickness dimension of the site | part in which the safety valve 9a in the side periphery 7 was formed, and other thickness dimensions are the substantially same thickness dimensions, since the safety valve 9a is recessed, exterior case 2 is concentrated on the portion of the safety valve 9a. When the internal pressure of the outer case 2 is increased, the outer case 2 is torn from the safety valve 9a.

  As shown in FIG. 5, in the safety valve 9 b in the third embodiment, the safety valve 9 b is formed by recessing both the outer surface side and the inner surface side of the side peripheral portion 7 of the exterior case 2. That is, one groove portion is formed on both the outer surface side and the inner surface side of the side peripheral portion 7, and both the groove portions are formed at the same position, whereby the safety valve 9b is configured.

  As shown in FIG. 6, in the safety valve 9c according to the fourth embodiment, the safety valve 9c is recessed by being provided with different positions in the height direction on both the outer surface side and the inner surface side of the side peripheral portion 7 of the exterior case 2. Is formed. One groove portion is formed on both the outer surface side and the inner surface side of the side peripheral portion 7, and both the groove portions are formed at positions shifted vertically to constitute the safety valve 9 c.

  In the above-described third and fourth embodiments, the safety valves 9b and 9c are formed by recessing both the outer surface side and the inner surface side of the side peripheral portion 7 of the outer case 2, but the side of the outer case 2 The safety valve 9 may be formed only by recessing the inner surface side of the peripheral portion 7.

  As shown in FIG. 7, the safety valve 9d in the fifth embodiment is a single groove extending along the circumferential direction of the side peripheral portion 7 of the exterior case 2, but the safety valve 9d is not linear. Rather, it is bent in the height direction with a predetermined curvature. Further, the groove portion of the safety valve 9d is within 15 mm from the bottom portion 8 even at the portion farthest from the bottom portion 8. By doing in this way, the stress added to the site | part nearest to the bottom part 8 in the groove part of the safety valve 9d and the part farthest from the bottom part 8 becomes imbalance, and the safety valve 9d of the exterior case 2 is easy to tear.

  As shown in FIG. 8, the safety valve 9e according to the sixth embodiment is a single groove portion extending linearly along the circumferential direction of the side peripheral portion 7 of the exterior case 2, and is orthogonal to the groove portion. A plurality of short grooves are formed. By doing in this way, the safety valve 9e of the exterior case 2 is easy to tear.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

  For example, although the electrolytic capacitor is exemplified as the capacitor in the above embodiment, the capacitor to which the present invention is applied is not limited to this, and can be applied to various capacitors and capacitors such as an electric double layer capacitor and an electrochemical capacitor.

  In the embodiment, aluminum having a purity of 99.7% is used as the metal material constituting the outer case 2, but the outer case 2 is made of an aluminum alloy (purity 99.0%, Mn-based or Mg-based). It can also be manufactured. Further, a metal material other than aluminum may be used.

  In the above-described embodiment, the safety valve 9 is formed by pressing the outer case 2. However, the safety valve 9 may be formed by cutting the outer case 2. .

  In the embodiment, the safety valve 9 is formed by forming one groove portion in the side peripheral portion 7 of the outer case 2. However, the safety valve 9 may be formed by forming a plurality of groove portions. Good.

DESCRIPTION OF SYMBOLS 1 Capacitor 2 Exterior case 3 Opening part 4 Sealing body 5 Capacitor element 6 Lead terminal 7 Side periphery part 8 Bottom part 9 Safety valve 10 Recessed part

Claims (6)

In an electrolytic capacitor having an outer case having a bottomed cylindrical shape and providing a safety valve having a concave shape on the side periphery of the outer case,
When the internal pressure of the exterior case is increased and stress is applied to the side periphery and bottom of the exterior case, the region of the side periphery where stress is applied in the expansion direction by the internal pressure, and the bottom is expanded by the internal pressure. An electrolytic capacitor characterized in that the safety valve is provided at a boundary portion between the region of the side peripheral portion where stress is applied in the contraction direction.   The electrolytic capacitor according to claim 1, wherein the safety valve is provided along a circumferential direction of the side peripheral portion.   The electrolytic capacitor according to claim 2, wherein the safety valve is provided over a range of approximately one half or more in a circumferential direction of the side peripheral portion.   The electrolytic capacitor according to any one of claims 1 to 3, wherein a thickness dimension of the outer case at the position of the safety valve is 0.1 mm or more.   5. The electrolytic capacitor according to claim 1, wherein the safety valve is provided in a portion within 15 mm from the bottom portion in the side peripheral portion.   The electrolytic capacitor according to claim 5, wherein a height dimension from the bottom portion to the opening portion in the outer case is 25 mm or more, and a diameter of the outer case is 35 mm or more.

Images