JP2874394B2 - Capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor with a security device.

[0002]

2. Description of the Related Art Generally, a capacitor such as an aluminum electrolytic capacitor is formed by laminating and winding an anode foil and a cathode foil via electrolytic paper to form a capacitor element, which is housed in a case and sealed by a lid. In addition, a lead terminal drawn from the capacitor element is connected to an external terminal provided on the lid.

[0003] In the capacitor of this configuration, if an overvoltage is applied by mistake or a voltage is applied with the opposite polarity,
Heat is generated and the gas pressure in the case rises, causing an explosion or ignition, which may cause a short circuit. Therefore, in order to prevent an explosion, an explosion-proof valve is provided on a lid or a case, and when the internal pressure of the case increases, the explosion-proof valve is activated to discharge gas in the case to the outside. In order to prevent ignition, the spark voltage of the electrolytic solution impregnated in the capacitor element is increased, the formation voltage of the anode foil is increased, and the electrolytic paper is thickened.

[0004]

However, when the explosion-proof valve is operated, there is a disadvantage that the electrolyte impregnated in the capacitor element leaks. Further, it is very difficult to completely prevent ignition by the conventional means, and there is a disadvantage that the fire leaks from the activated explosion-proof valve and damages other electronic components and the like.

The present invention has been made to solve the above-mentioned drawbacks and to provide a capacitor which prevents a leakage due to a short circuit before the explosion-proof valve is operated.

[0006]

According to the first aspect of the present invention, there is provided an anode external terminal and a cathode external terminal.
And a metal piece coated with an insulating material between the two.

The invention according to claim 2 is characterized in that the anode external terminal and
It is an object of the present invention to provide a capacitor characterized in that a metal piece which is partially opposed to and overlapped with a cathode external terminal is provided with an insulating material interposed therebetween.

[0008]

[Function] A metal piece covered with an insulating material such as a polymer film or an insulating resin, or a metal piece partially overlapped with an insulating material interposed therebetween is provided between lead terminals drawn out of a capacitor element or on a lid. Placed between external terminals. When an overvoltage or the like is applied to the capacitor having this configuration, the capacitor element generates heat, and the temperature of the core usually rises to about 200 ° C. This heat dissolves the polymer film and the like, exposing the metal pieces, and short-circuiting between the lead terminals. This allows
Almost no voltage is applied to the capacitor element,
Heat generation can be suppressed, and the explosion-proof valve can be prevented from operating.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
FIGS. 1A and 1B show an embodiment of the first aspect of the present invention. Reference numeral 1 denotes a case made of aluminum or the like, which has a thin portion as an explosion-proof valve 2 on the bottom surface. Reference numeral 3 denotes a capacitor element housed in the case 1, which is formed by laminating and winding an anode foil and a cathode foil via electrolytic paper, and from which an anode lead terminal 4 and a cathode lead terminal 5 are drawn. Reference numeral 6 denotes a lid that seals the case 1, and is provided so as to penetrate the anode external terminal 7 and the cathode external terminal 8. The anode lead terminal 4 and the cathode lead terminal 5 are bent in the middle and are connected to the anode external terminal 7 and the cathode external terminal 8, respectively. 9 is an insulating material 1 such as a polypropylene film or a polypropylene resin as shown in FIG.
0 is a metal piece such as aluminum covered with an anode lead terminal 4 and a cathode lead terminal 5.

Next, in the above embodiment, a rated voltage of 250 V,
Ten aluminum electrolytic capacitors having a size of 820 μF and a size of φ35 × 50 l were used, a voltage of 375 V was applied thereto, and a current of 7 A was passed to observe the state of breakdown. In addition, the metal piece 9
The width is 5 mm, the length is 20 mm, and the thickness is 0.2 mm. A polypropylene resin having a thickness of 0.3 mm and 2 mm protruding from an end is applied to both surfaces. As a result, before the explosion-proof valve was operated, the metal piece 9 was exposed and the anode lead terminal 4 and the cathode lead terminal 5 were short-circuited before the explosion-proof valve was operated. When the temperature of the core of the capacitor element 3 was measured using a thermocouple, the temperature rose to 180 ° C.

FIG. 3 shows another embodiment of the present invention, in which a metal piece 11 coated with an insulating material is connected to a capacitor element 1.
2 and wound around the anode lead terminal 13 and the cathode lead terminal 14 drawn out from the terminal 2.

FIG. 4 shows a lid used in an embodiment of the present invention. In this embodiment, the lid 1
A metal piece 18 is connected between an anode external terminal 16 and a cathode external terminal 17 that penetrate through 5. As shown in FIG. 5, the metal piece 18 has a first metal piece 19 and a second metal piece 20 that partially face each other and are overlapped with an insulating material 21 interposed therebetween. Also in this case, the insulating material 21 is melted by the heat generated by the capacitor element, and the first metal piece 19 and the second metal piece 20 come into contact with each other.
And short-circuit.

[0013]

As described above, according to the first aspect of the present invention,
By providing a metal piece coated with an insulating material between the anode external terminal and the cathode external terminal, the terminals can be short-circuited before the explosion-proof valve operates, preventing the electrolyte and fire from leaking from the explosion-proof valve. Is obtained.

According to the second aspect of the present invention, the outside of the anode is also provided.
By providing a metal piece that partially overlaps between the external terminal and the cathode external terminal with an insulating material interposed therebetween, it is possible to obtain a capacitor that can prevent the electrolyte or the like from leaking from the explosion-proof valve.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of a metal piece used in the embodiment of FIG.

FIG. 3 shows a diagram of a capacitor element used in another embodiment of the invention of claim 1;

FIG. 4 is a rear view of a lid used in the embodiment of the second invention.

5 shows a sectional view of a metal piece used in the embodiment of FIG.

[Explanation of symbols]

3,12 ... capacitor element, 4,13 ... anode lead terminal, 5,14 ... cathode lead terminal, 6,15 ... lid,
7, 16: anode external terminal, 8, 17: cathode external terminal,
9, 11, 18 ... metal pieces, 10, 21 ... insulating materials.

Claims (2)

(57) [Claims] 1. A capacitor comprising a metal piece coated with an insulating material between an anode external terminal and a cathode external terminal . 2. A capacitor comprising a metal piece partially opposed and overlapped between an anode external terminal and a cathode external terminal with an insulating material interposed therebetween.