JPH11219869A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent capacitor elements from jumping out of an open valve, when a thin part formed at the bottom of a metal case is opened and to regulate the direction of the gas blow-off, in a capacitor containing the thin part functioning as explosion-proof valve at the bottom of the metal case. SOLUTION: A cylindrical protrusion 12 is formed at the bottom of a metal case 3. The metal case 3 is covered with a heat-shrinkable outer-packaging member 4, then heat-treated to form a cylinder 21 with an open end by making a step at the bottom 25 of the metal case 3. Consequently, even if the thin part formed at the bottom of the cylindrical protrusion 12 is opened as a valve, the capacitor element with a diameter larger than the cylindrical protrusion 12 is prevented from jumping out. The direction of the gas blown off from the opened valve is regulated through the cylindrical protrusion 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor provided with a thin portion functioning as an explosion-proof valve at the bottom of a metal case.

[0002]

2. Description of the Related Art When a reverse voltage, an overvoltage or an abnormal pulse voltage is applied to an electrolytic capacitor, an overcurrent flows to generate gas or the capacitor element generates heat, so that the internal pressure increases. As a countermeasure, a thin portion is formed at the bottom of a metal case having a one-end open bottom, and the thin portion functions as an explosion-proof valve to prevent explosion and destruction of the electrolytic capacitor. As this kind of electrolytic capacitor,
For example, a valve that opens from the center of the bottom of a metal case is disclosed in Japanese Utility Model Laid-Open No. 54-146851. This electrolytic capacitor will be described with reference to FIG.

In FIG. 3, a bottomed metal case 13 having an open end accommodates a capacitor element (not shown). The opening of the metal case 13 is closed by a sealing member (not shown), and the terminal 14 protrudes toward the opening. And the bottom of the metal case 13
A thin portion 19 functioning as an explosion-proof valve is formed at 15.
This metal case 13 is covered with an exterior member 16 formed of a heat-shrinkable tube to form an electrolytic capacitor 20.
When the internal pressure of the electrolytic capacitor 20 rises, the thin portion 19
Opens (acts as an explosion-proof valve) to prevent explosion and destruction of the electrolytic capacitor. In addition to this conventional example, the valve that opens from a position offset from the center of the bottom of the metal case
57-41652.

[0003]

In a conventional electrolytic capacitor, when a thin portion formed at the bottom of a metal case is opened to function as an explosion-proof valve, the capacitor element jumps out of the valve-opening portion, or the gas flows together with gas or steam. Electrolyte splatters around and stains other parts. In some cases, the blown out electrolyte flows along the side surface of the metal case and reaches the substrate to cause a dielectric breakdown accompanied by a spark, and the blown out gas may be ignited. Therefore, improvement has been desired.

[0004] The present invention is a capacitor provided with a thin portion at the bottom of a metal case that functions as an explosion-proof valve, and prevents the capacitor element from jumping out of the valve opening when the thin portion formed at the bottom of the metal case is opened. In addition, an object of the present invention is to provide an electrolytic capacitor having a structure for regulating a blowing direction of gas to be blown.

[0005]

An electrolytic capacitor according to the present invention is formed by projecting a bottom of a bottomed cylindrical metal case for housing a capacitor element into a cylindrical shape having a diameter smaller than the outer diameter of the bottom of the metal case. A thin-walled portion functioning as an explosion-proof valve was provided on the bottom surface of the cylindrical projection, and a heat-shrinkable tube was placed over the metal case to perform a heat treatment, thereby opening the tip with a step at the bottom of the metal case. It is characterized in that a cylindrical portion is formed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings shown in FIGS. 1A is a perspective view of an electrolytic capacitor 31 according to a first embodiment of the present invention, FIG. 1B is a cross-sectional view of the electrolytic capacitor 31 shown in FIG. 1A, and FIG. c)
FIG. 2 is a sectional view showing an operation state of an explosion-proof valve of the electrolytic capacitor 31 shown in FIGS. 1 (a) and 1 (b). FIG. 2 (a),
(B) is a perspective view showing another embodiment of the electrolytic capacitor of the present invention. The same reference numerals used in FIGS. 1 and 2 indicate the same components.

[0007] In (a), (b), (c) of FIG.
The capacitor element 1 impregnated with the electrolytic solution is housed in a bottomed cylindrical metal case 3, and the opening of the metal case 3 is closed by a sealing plate 7. The sealing plate 7 is a cylindrical hard insulating plate 5
A pair of rivets 8 are fixed to the sealing plate 7 through the hard insulating plate 5 and the elastic member 6. Each tab 2 of the capacitor element 1 is fixed to each rivet 8 inside the sealing plate 7, and a terminal 11 is fixed to each rivet 8 outside the sealing plate 7. In FIG. 1A, a cylindrical projection 12 having a diameter smaller than the outer diameter of the capacitor element housed therein is formed on the bottom 25 of the metal case 3 having an open bottom and having a bottom by press working or the like. ing. A thin portion 9 functioning as an explosion-proof valve is provided on the bottom surface of the cylindrical protrusion 12.
An outer member 4 made of a heat-shrinkable tube is provided in the metal case 3.
And heat-treated. The portion of the exterior member 4 that covers the main body of the metal case 3 is formed to have a diameter substantially equal to the outer diameter of the metal case 3, and the portion that covers the cylindrical protrusion 12 above the bottom 25 of the metal case 3 has a substantially cylindrical protrusion. The cylindrical portion 21 having the outer diameter of the portion 12
And has a stepped shape with the bottom 25 of the metal case 3 as a boundary. The cylindrical portion 21 is formed so as to extend further than the cylindrical protruding portion 12, and has an opening 10 at the tip.

Next, electrolytic capacitors 32 and 33 of the second and third embodiments of the present invention will be described with reference to FIGS. 2 (a) and 2 (b). FIG. 2A shows a case where a heat-shrinkable tube shorter in length than the heat-shrinkable tube used for the electrolytic capacitor 31 of the first embodiment described with reference to FIG. FIG. 4 is a perspective view showing an embodiment in which 24 is placed on a metal case 3 adopted in the first embodiment. In the electrolytic capacitor 32 of the second embodiment shown in FIG. 2 (a), the heat-shrinkable tube 24 covering the metal case 3 partially covers the outer peripheral portion on the terminal side of the metal case 3 (about half in the figure). ) In the exposed state, the metal case 3 is heated while covering the outer peripheral surface on the bottom side. The exterior member 24 has a portion that covers the upper half of the main body of the metal case 3 having a diameter substantially equal to the outer diameter of the metal case 3.
A portion that covers the cylindrical protrusion 12 above the bottom 25 of the metal case 3 is formed as a tube 22 having an outer diameter of the substantially cylindrical protrusion 12, and borders the bottom 25 of the metal case 3. The cylindrical portion 22 is formed so as to extend further than the cylindrical protruding portion 12, and has an opening 10 at the tip.

FIG. 2B shows a case where a heat-shrinkable tube longer than the heat-shrinkable tube used for the electrolytic capacitor 31 of the first embodiment described with reference to FIG. FIG. 3 is a perspective view showing an embodiment in which the exterior member is covered by a metal case 3 employed in the first embodiment. In the electrolytic capacitor 33 according to the third embodiment shown in FIG. 2B, the heat-shrinkable tube 34 covering the metal case 3 is subjected to heat treatment in a state of covering the entire outer peripheral portion of the main body of the metal case 3. . The portion of the exterior member 34 that covers the main body of the metal case 3 is formed to have a diameter substantially equal to the outer diameter of the metal case 3, and the portion that covers the cylindrical protrusion 12 above the bottom 25 of the metal case 3 has a substantially cylindrical protrusion. It is formed in a cylindrical portion 23 having the outer diameter of the portion 12 and has a stepped shape bordering on the bottom portion 25 of the metal case 3. Tube part 23
The point that is formed to extend further than the cylindrical protrusion 12 is
It is the same as the tubular portions 21 and 22 of the first and second embodiments described above, except that the tubular portion 23 is formed longer than the tubular portions 21 and 22 and has an opening 30 at the tip.

In the electrolytic capacitors 31 and 32 of the first and second embodiments configured as described above, the thin-walled portion 9 provided on the bottom surface of the cylindrical projection 12 opens and functions as an explosion-proof valve. The capacitor element 1 whose outer diameter is larger than the diameter of the bottom surface of the cylindrical protrusion 12 cannot pass through the inside of the cylindrical protrusion 12 and is prevented from jumping out from the bottom 25 of the metal case 3. Further, the gas, steam and electrolyte blown out from the valve opening point pass through the cylindrical projection 12 which is an extension of the bottom 25 of the metal case 3 before reaching the valve opening point. When blowing, the blowing direction (of gas, vapor and electrolyte) is regulated to a predetermined direction. Further, the exterior member 4 (24 in the second embodiment) that covers the metal case 3 has a step at the bottom 25 of the metal case 3 and covers the entire cylindrical protrusion 12. It is further extended so that the tip has an opening 10. Therefore, even if the electrolytic solution blown out from the valve-opening portion scatters around the bottom surface of the cylindrical projection 12, most of the electrolyte is accumulated inside the cylindrical portion 21 (22 in the second embodiment) and accommodated therein. Almost all of the gas and vapor are released from the electrolyte, thereby preventing the electrolyte from contaminating other components.

This is the same as the electrolytic capacitor according to the third embodiment.
The same can be said for 33. In the electrolytic capacitor 33 of the third embodiment, the exterior member 34 that covers the main body of the metal case 3 and the cylindrical protrusion 12 provided on the bottom 25 of the metal case 3 The cylindrical portion 23 has a stepped shape with the boundary, and the cylindrical portion 23 covering the cylindrical protruding portion 12 is a cylindrical protruding portion.
Further extending from the thin portion 9 on the bottom surface of the 12
It is formed longer than the cylindrical portions 21 and 22 of the second embodiment, and has an opening 30 at the tip. Therefore, the electrolytic solution blown out from the valve-opened portion is securely stored inside the cylindrical portion 23, and is stored in the cylindrical portion 23.
Almost only gas or vapor is emitted from the opening 30 at the tip of the 23. Also, compared to the first and second embodiments, the opening 30
This is practical because it can be set at any position.
The heat-shrinkable tube employed as the exterior member in the first, second, and third embodiments is formed of polyester, polyvinylidene fluoride, polyvinyl chloride, or the like.

[0012]

According to the electrolytic capacitor of the present invention, when the thin portion provided on the bottom surface of the cylindrical protrusion formed on the bottom of the metal case is opened, the outer diameter is larger than the diameter of the bottom surface of the cylindrical protrusion. The capacitor element having a large diameter cannot pass through the inside of the cylindrical protrusion, and is prevented from jumping out from the bottom of the metal case. In addition, gas and vapor and electrolyte blown out from the valve opening location are
It passes through a cylindrical projection that is an extension of the bottom of the metal case before reaching the valve opening, so when blowing out from the valve opening, the blowing direction (gas, vapor and electrolyte) is restricted to a predetermined direction. Is done. Further, the exterior member covering the metal case has a step at the bottom of the metal case to cover the entire cylindrical protrusion, and further extends beyond the cylindrical protrusion to have an opening at the tip. Therefore, even if the electrolyte blown out from the valve-opening location scatters around the bottom surface of the cylindrical projection, most of it is stored inside the cylindrical portion, and almost only gas or vapor is released from the opening at the tip. Yes, the electrolyte is prevented from fouling other components. As described above, the electrolytic capacitor of the present invention has a structure in which the gas, steam, and electrolyte blown out from the valve-opening portion are not easily transmitted to the side surface of the metal case, so that the electrolyte hardly reaches the substrate, and the blown-out gas is ignited. The practical effect is great, for example, the danger of the occurrence is prevented.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view of an electrolytic capacitor showing a first embodiment of the present invention. (B) is a sectional view of the electrolytic capacitor shown in (a). (C) is sectional drawing which shows the operating state of the explosion-proof valve of the electrolytic capacitor shown to (a) and (b).

FIG. 2 (a) is a perspective view of an electrolytic capacitor showing a second embodiment of the present invention. (B) is a perspective view of an electrolytic capacitor showing a third embodiment of the present invention.

FIG. 3 is a perspective view of an electrolytic capacitor showing a conventional example of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 capacitor element 2 tab 3 metal case 4 exterior member 5 hard insulating plate 6 elastic member 7 sealing plate 8 rivet 9 thin portion 10 opening 11 terminal 12 cylindrical protrusion 13 metal case 14 terminal 15 bottom 16 exterior member 19 thin portion 20 Electrolytic capacitor 21 Tube part 22 Tube part 23 Tube part 24 Exterior material 25 Bottom 30 Opening 31 Electrolytic capacitor 32 Electrolytic capacitor 33 Electrolytic capacitor 34 Exterior material

Claims (1)

[Claims] An explosion-proof valve is provided on the bottom surface of a cylindrical projection formed by projecting the bottom of a cylindrical metal case having a bottom that houses a capacitor element into a cylindrical shape having a diameter smaller than the outer diameter of the bottom of the metal case. Electrolysis characterized by forming a cylindrical portion having a step at the bottom of the metal case and having an open end by providing a thin portion functioning as a heat treatment by covering the metal case with a heat-shrinkable tube. Capacitors.