JP2010232675A - Electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor having a pressure valve that reliably operates when the internal pressure rises abruptly, wherein the storage efficiency of a capacitor element in the large electrolytic capacitor is improved, the lifetime of the electrolytic capacitor is prolonged by suitably discharging a gas generated in normal use. <P>SOLUTION: The electrolytic capacitor is characterized in that an air vent valve is provided to a sealing body, and has a through hole having large and small diameters, thin-film type gas-permeable rubber of nearly the same size as the large diameter of the through hole, and a fixing means having a plate material having a plurality of through holes and an upright wall connecting with an outer peripheral edge of the plate member and having nearly the same size as the large diameter of the through hole, wherein the gas-permeable rubber and fixing means are inserted from the large diameter side of the through hole, and the gas-permeable rubber is brought into contact with the inside of the through hole by the fixing means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor, and more particularly to an electrolytic capacitor having an explosion-proof structure that releases a predetermined amount of internal gas when the internal pressure of the capacitor is increased due to generation of internal gas and that reliably operates when the internal pressure is suddenly increased.

  In an electrolytic capacitor, gas may be generated inside due to the operating current due to its structure. However, when a large current flows, the generation of the gas becomes significant, and the internal pressure of the outer case increases due to the generation of the gas. There are cases where the case is torn or the sealing part between the sealing body and the outer case is torn and the sealing body is detached.

For this reason, in an electrolytic capacitor, an explosion-proof structure is taken in order to prevent damage to the outer case and separation of the sealing body due to a sudden increase in internal pressure. As this explosion-proof structure, a sealing body that seals the outer case There is something to form. There has been disclosed one in which a plurality of pressure valves are provided in which a through-hole is provided in a sealing body of an outer case containing a capacitor element and covered with rubber or the like (Patent Document 1).
Further, it is known that a leakage current flows inside an electrolytic capacitor during use. Then, when this leakage current flows, hydrogen gas is generated inside the electrolytic capacitor. As a result, the internal pressure of the electrolytic capacitor rises, and therefore, a gas vent valve is disclosed in which a through hole is provided in a part of the sealing body, covered with foamed silicone rubber, and this hydrogen gas is released to the outside (Patent Document 2).

JP-A-8-45797 JP 2001-15391 A

By the way, the pressure valve and the gas vent valve are provided in the sealing body, the internal gas generated by the leakage current is permeated through the gas vent valve, and when the internal pressure is suddenly increased, the pressure valve is operated to release the internal gas. I can.
However, in a large electrolytic capacitor, since the area of the electrode foil is large, a large amount of gas is generated due to leakage current or the like. In this state, the amount of gas generated may be greater than the amount of gas that permeates the normal vent valve. If this state continues, the pressure valve operates and the life of the electrolytic capacitor is shortened. Therefore, the occupation ratio (accommodation efficiency) of the capacitor element inside the electrolytic capacitor is lowered, and a predetermined space is provided as a buffer when the internal pressure increases. However, providing this predetermined space increases the electrolytic capacitor, increases the area occupied by the substrate, and hinders downsizing of electronic devices.

  Therefore, the present invention improves the storage efficiency of the capacitor element in a large electrolytic capacitor, and at the same time, extends the life of the electrolytic capacitor by suitably discharging the gas generated during normal use to the outside. It is an object of the present invention to provide an electrolytic capacitor having a pressure valve that operates reliably when the internal pressure is suddenly increased.

The electrolytic capacitor of the present invention that has solved the above problems includes a capacitor element, a bottomed cylindrical outer case that houses the capacitor element, a sealing body that seals an opening of the outer case, and the sealing body. It comprises a pressure valve made of rubber and a gas vent valve made of permeable rubber, the gas vent valve being provided in the sealing body, a through hole having a large diameter and a small diameter, and a large diameter of the through hole A thin film-like transparent rubber having substantially the same size, a plate having a plurality of through holes, and a standing wall connected from the outer peripheral edge of the plate, and having fixing means having the same size as the large diameter of the through holes The permeable rubber and the fixing means are inserted from the large diameter of the through hole, and the permeable rubber is brought into close contact with the through hole by the fixing means.
According to this, the permeable rubber which permeate | transmits the internal gas of an electrolytic capacitor can be easily attached to a sealing body. In addition, the internal gas that has passed through the permeable rubber is discharged to the outside of the electrolytic capacitor through a plurality of through holes provided in the fixing means, and the thin permeable rubber is covered with the fixing means. For this reason, there is no problem that the thinly formed permeable rubber is damaged during transportation and transportation or when it comes into contact with other electronic components during mounting, and the driving electrolyte flows out.

  Further, when the pressure permeation amount of the pressure valve and the gas vent valve is 1, the gas vent valve is set to 8 or more.

Usually, the pressure valve is set to be weaker than the strength of the curling portion to the sealing plate of the outer case, and the internal gas is released by operating the pressure valve when the internal pressure rises. The strength of the curling portion varies depending on the size of the electrolytic capacitor. If the electrolytic capacitor is large, the strength of the curling portion is increased by a predetermined ratio. Therefore, the breaking strength of the pressure valve is also a predetermined ratio depending on the size of the electrolytic capacitor. Set by. The rubber thickness of the pressure valve is set by the breaking strength of the pressure valve, and the gas permeation amount of the rubber is set by this thickness. Therefore, the gas permeation amount of the pressure valve is naturally set within a certain range depending on the size of the electrolytic capacitor.
The present inventors provide a gas vent valve having a predetermined amount of permeation amount with respect to the permeation amount of the pressure valve, thereby appropriately releasing the gas generated inside the electrolytic capacitor, and thereby extending the life of the electrolytic capacitor. It was found that In other words, by increasing the gas permeation amount of the degassing valve to 8 times the permeation amount of the pressure valve, the gas generated inside the electrolytic capacitor by normal use is appropriately released, and when the internal pressure suddenly rises, the pressure valve Can be operated reliably, and the life can be extended. When the gas permeation amount of the gas vent valve is 7 times or less than the gas permeation amount of the pressure valve, the gas permeation amount is small, the pressure valve operates, and the electrolytic capacitor becomes short-lived.

  Further, the thickness of the gas vent valve is set to 0.5 mm or less. Thus, by reducing the thickness of the gas vent valve, the permeability of the internal gas can be increased.

  The degassing valve has an inner diameter of φ20 or less. If the inner diameter of the gas vent valve exceeds φ20, the strength of the sealing body is lowered, and there is a problem that the arrangement position of the external terminal is restricted.

  Further, the occupation ratio of the capacitor element in the outer case is set to 90% or more. Even when the occupation rate is high and the space for buffering when the internal pressure is increased is small, the present invention can achieve a long life.

  According to the present invention, the permeable rubber that allows the internal gas of the electrolytic capacitor to pass through can be easily attached to the sealing body. In addition, the internal gas that has passed through the permeable rubber is discharged to the outside of the electrolytic capacitor through a plurality of through holes provided in the fixing means, and the thin permeable rubber is covered with the fixing means. For this reason, there is no problem that the thinly formed permeable rubber is damaged during transportation and transportation or when it comes into contact with other electronic components during mounting, and the driving electrolyte flows out. In addition, even an electrolytic capacitor with an occupation ratio of the capacitor element in the outer case of 90% or more can appropriately release internal gas during normal use, achieving a longer life of the electrolytic capacitor and a sudden increase in internal pressure. Sometimes, the pressure valve can be operated reliably, and a highly reliable electrolytic capacitor can be provided.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the capacitor element 2 has an internal terminal at an arbitrary portion of an anode foil having a roughened surface of an aluminum foil to form an anodized film and a cathode foil having a similarly roughened surface. 4 is connected by a connecting method such as ultrasonic welding, and is wound or laminated by interposing an electrically insulating separator (for example, manila paper, kraft paper, etc.) between the anode foil and the cathode foil. .

  The capacitor element 2 is impregnated with a driving electrolyte, and the internal terminal 4 led out from the capacitor element 2 is provided through the sealing plate 3 formed of a moldable insulating material such as a synthetic resin having a predetermined thickness. The external terminal 5 is connected to the rivet by caulking and welding. The sealing plate 3 is provided with a rivet made of aluminum, an external terminal 5 made of a screw part integrated with the rivet, a pressure valve 7 and a gas vent valve 10. As shown in FIG. 2, the external terminal 5 is provided at a point-symmetrical position from the center of the sealing plate 3, and the pressure valve 7 and the vent valve 10 are also point-symmetrical from the center of the sealing plate 3. Are spaced apart from each other.

  The pressure valve 7 has a function of partially breaking when the internal pressure of the electrolytic capacitor 1 suddenly rises and releasing the internal gas to the outside of the electrolytic capacitor 1. It consists of thin rubber covering. Examples of rubber include silicon rubber. This rubber is a cap 8 having a flange, and is inserted from the side of the capacitor element 2 of the sealing plate 3, and the cap 8 closes the through hole 9. By forming a thin portion in the cap 8, the breakability of the cap 8 may be increased when the internal pressure of the electrolytic capacitor 1 is increased.

The rubber of the pressure valve 7 has an inner diameter of 4 mm and a thickness of 1 mm, and the permeation amount of the internal gas is 1260 cc at a case internal pressure of 5 kg / cm ² .

  The gas vent valve 10 has a function of releasing the internal gas of the electrolytic capacitor 1 to the outside of the electrolytic capacitor 1 as needed, and is made of a through-hole 11 and a gas-permeable thin film rubber covering the through-hole 11. Examples of the rubber include rubber having excellent gas permeability such as silicon rubber, foamed silicon rubber, fluorine rubber, butyl rubber, and ethylene-propylene-diene rubber. As shown in FIG. 3A, the permeable rubber 12 has a wall thickness 13 around the center and a wall near the center. Further, a thick cross is formed that intersects at the center from the surrounding thickness 13 to maintain the strength of the permeable rubber 12.

The gas permeable rubber 12 of the gas vent valve 10 has an inner diameter of 11 mm, a thickness of 0.4 mm, and an internal gas permeation amount of 11860 cc at a case internal pressure of 5 kg / cm ² . If the thickness of the gas permeable rubber 12 is larger than 0.5 mm, the inner diameter of the permeable rubber 12 must be increased in order to increase the gas permeation amount, and the strength of the sealing plate 3 is reduced. .

  As shown in FIG. 3B, the fixing means 14 is made of a metal material such as aluminum, and a disk material 15 and standing walls 16 connected to the disk material 15 are intermittently formed around a plurality of outer circumferences. ing. The disk portion of the fixing means 14 is provided with a plurality of holes 17, and the gas that has passed through the permeable rubber 12 passes through the holes and is released to the outside of the electrolytic capacitor 1.

  Next, the attachment state of the gas vent valve to the sealing plate will be described. As shown in FIG. 4, the sealing plate is provided with a through hole 11 for a gas vent valve. The through hole 11 has a large diameter on the outer side of the sealing plate 3 and a small diameter on the inner side. Is formed. The small diameter of the through-hole 11 is narrowed for a while toward the outside of the sealing plate. The circular thin film permeable rubber 12 is inserted from the large diameter side of the through hole 11 and placed on the stepped portion 18. Further, the through-hole 11 has a disk shape that presses the thick portion 13 on the outer periphery of the permeable rubber 12 from the large-diameter side of the through-hole 11 to fix the permeable rubber 12 inside the through-hole 11. The fixing means 14 is inserted to fix the permeable rubber 12, and the permeable rubber 12 is brought into close contact with the sealing plate 3 to be hermetically sealed.

  The outer diameter of the standing wall 16 of the fixing means 14 is slightly smaller than the inner diameter of the through hole 11 of the sealing plate 3, and when the fixing means 14 is inserted into the through hole 11, the elasticity of the fixing means 14 makes the standing wall 16 elastic. The outer diameter is inserted with being contracted along the inner diameter of the through hole 11 and is held and fixed in the through hole 11 by the repulsive force of the fixing means 14.

  According to this gas vent valve 10, the gas generated inside the electrolytic capacitor 1 enters from the small diameter side of the gas vent through hole 11 of the sealing plate 3 and presses the permeable rubber 12. When the inside of the electrolytic capacitor reaches a predetermined pressure, the internal gas passes through the permeable rubber 12, passes through the holes 17 of the fixing means 14, and is released to the outside. Since the permeable rubber 14 is covered with the plate material 15 of the fixing means 14, swelling of the permeable rubber 14 due to the internal pressure of the electrolytic capacitor 1 is prevented.

  The capacitor element 2 integrated with the sealing plate 3 is housed in an outer case 6 of a bottomed cylinder made of aluminum, and the opening end of the outer case 6 is sealed by the sealing plate 3 by a curling process. The capacitor element 2 housed in the outer case 6 has an occupation ratio of 90% or more of the outer case 6. This is because by increasing the capacitor element 2 housed in the outer case 6, the area of the anode foil constituting the capacitor element 2 can be increased and the capacitance can be increased.

  Thus, the permeation amount of the internal gas discharged to the outside of the electrolytic capacitor 1 is 1260 cc for the pressure valve 7 and 11860 cc for the gas vent valve 10. The permeation amount of the gas vent valve 10 is the permeation amount of the pressure valve 7. Therefore, even if the occupation rate of the capacitor element 2 in the outer case 6 is high, the pressure valve 7 does not operate and the life can be extended.

  In the electrolytic capacitor 1 configured as described above, since the pressure valve 7 and the gas vent valve 10 are provided on the sealing plate 3, the internal gas during normal use can be discharged as appropriate, and the life of the electrolytic capacitor 1 can be extended. In addition, when the internal pressure is suddenly increased, the pressure valve 7 can be reliably operated, and the highly reliable electrolytic capacitor 1 can be provided.

  Next, examples of the present invention will be described.

(Example)
The electrolytic capacitor of the example has a rated voltage of 400 V, a capacitance of 12000 μF, and a size of φ89 × L180 mm. The rubber of the pressure valve provided on the sealing plate is made of silicon rubber, has an inner diameter of 4 mm and a thickness of 1 mm, and the internal gas permeation amount is 1260 cc at a case internal pressure of 5 kg / cm ² . The permeable rubber of the gas vent valve provided on the sealing plate is made of silicon rubber, the inner diameter is 11 mm, the thickness is 0.4 mm, and the internal gas permeation amount is 11860 cc at an internal pressure of 5 kg / cm ² . The internal gas permeation amount of the pressure valve and the gas vent valve is 1: 8 or more. A capacitor element was attached to the sealing plate and housed in an outer case, and the opening was curled and sealed. The occupation ratio of the capacitor element to the outer case was 94%.

(Comparative example)
The permeable rubber of the degassing valve of the example had an inner diameter of 8 mm and a thickness of 1 mm, and the internal gas permeation ratio of the pressure valve and the degassing valve was 1: 5. The occupation ratio of the capacitor element to the outer case was set to 94%.

  As described above, the life test was conducted on the two electrolytic capacitors at a temperature of 85 ° C. with a constant rated voltage. At that time, the electrolytic capacitor was taken out at a fixed time, and the appearance change of the electrolytic capacitor was observed every time elapsed.

  The test result showed that the pressure valve operated in 1500 hours in the electrolytic capacitor of the comparative example, whereas the pressure valve did not operate even after 5000 hours in the electrolytic capacitor in the example. Also, the decrease in capacitance is -2.0%, so that the performance of the electrolytic capacitor is maintained and the life is extended.

It is sectional drawing which shows the electrolytic capacitor of the Example of this invention. It is a top view which shows the electrolytic capacitor of the Example of this invention. (A) shows the permeable rubber which comprises the degassing valve of the Example of this invention. (B) shows the fixing means which comprises the degassing valve of the Example of this invention. It is sectional drawing which shows the attachment process of the degassing valve of the Example of this invention.

DESCRIPTION OF SYMBOLS 1 Electrolytic capacitor 2 Capacitor element 3 Sealing plate 4 Internal terminal 5 External terminal 6 Exterior case 7 Pressure valve 8 Cap 9 Pressure valve through hole 10 Gas vent valve 11 Gas vent valve through hole 12 Permeable rubber 13 Thick portion 14 Fixed Means 15 Plate material 16 Standing wall 17 Hole 18 Step

Claims (5)

A capacitor element, a bottomed cylindrical outer case that houses the capacitor element, a sealing body that seals the opening of the outer case, a pressure valve made of rubber provided in the sealing body, and a permeable rubber A degassing valve
The gas vent valve is provided in a sealing body, and includes a through hole having a large diameter and a small diameter, a thin film-like transparent rubber having substantially the same size as the large diameter of the through hole, a plate material having a plurality of through holes, It has a standing wall connected from the outer peripheral edge of the plate material, and includes a fixing means having substantially the same size as the large diameter of the through hole,
An electrolytic capacitor in which a permeable rubber and fixing means are inserted from a large diameter of the through hole, and the permeable rubber is brought into close contact with the through hole by the fixing means.   The electrolytic capacitor according to claim 1, wherein when the pressure valve is set to 1 as the gas permeation amount of the pressure valve and the gas vent valve, the gas vent valve is set to 8 or more.   The electrolytic capacitor according to claim 1 or 2, wherein a thickness of the permeable rubber of the degassing valve is 0.5 mm or less.   The electrolytic capacitor according to claim 1, wherein an inner diameter of the gas vent valve is φ20 or less.   5. The electrolytic capacitor according to claim 1, wherein an occupation ratio of the capacitor element in the outer case is 90% or more.

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