JPH05251290A - Cased capacitor - Google Patents

Abstract

PURPOSE:To provide a capacitor designed to prevent damage to other electronic components due to the action of its explosion-proof valve. CONSTITUTION:A capacitor element 4 is housed in a case 1 equipped with an explosion-proof valve 3. The case 1 is hermetically closed after terminals 7 and 8 are led out from it. The case 1 is covered with an insulating cap 9. A contact switch 10 is provided to the insulating cap 9 adjacent to the explosion-proof valve 3, and a current fuse 16 connected to the contact switch 10 in series is provided. The contact switch 10 is connected to the capacitor element 4 in parallel, and the current fuse 16 is connected to the element 4 in series, and thus a cased capacitor 18 can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cased capacitor having an explosion-proof valve.

[0002]

2. Description of the Related Art A cased capacitor such as an aluminum electrolytic capacitor adopts various techniques in order to prevent it from exploding when an overvoltage is applied or a reverse current is applied to cause abnormal heat generation. is doing. For example, a fuse such as a current fuse or a temperature fuse is arranged inside or outside the case, and this fuse is connected in series with the capacitor element. Then, when an overvoltage is applied, the fuse is blown to disconnect the capacitor from the circuit. Further, in order to prevent the condenser from exploding due to the gas filled inside the case, an explosion-proof valve is provided on the case and the lid.

[0003]

However, the capacitor provided with the explosion-proof valve has a drawback that the fuse operates after the explosion-proof valve operates when the voltage is applied slowly. If the explosion-proof valve operates first, the gas inside the case is discharged, and the electrolytic solution impregnated in the capacitor element is scattered, possibly damaging other electronic parts of the device incorporating the capacitor.

It is an object of the present invention to provide a cased capacitor which can remedy the above drawbacks and prevent the explosion-proof valve from operating and damaging other electronic components.

[0005]

In order to achieve the above-mentioned object, the present invention provides a case-type capacitor in which a capacitor element is housed in a case provided with an explosion-proof valve, and terminals are pulled out and sealed, in the vicinity of the explosion-proof valve. Providing an insulating cap over the case having a contact switch located and a current fuse connected in series with this contact switch, connecting a capacitor element in parallel with the contact switch and in series with the current fuse; To provide a cased capacitor.

The capacitor element and the contact switch may be preliminarily connected in parallel with each other by a lead wire or the like before the cased capacitor is incorporated in the device, or in parallel with the circuit wiring in a state where the capacitor is connected to an external circuit. You may connect.

[0007]

[Function] When an overvoltage or the like is applied to a capacitor such as an aluminum electrolytic capacitor, the electrolytic solution is gasified by the heat generated by the capacitor element. The pressure of this gas inflates the explosion-proof valve provided in the case. When the explosion-proof valve swells, the pressure activates the contact switch disposed near the explosion-proof valve.
When the contact switch operates, the current flowing through the capacitor element flows toward the contact switch because the contact switch is connected in parallel with the capacitor element. Since this current is much larger than the current flowing through the capacitor element, the current fuse connected in series with the contact switch is blown. This allows the capacitor to be released from the circuit and prevent the explosion proof valve from operating.

[0008]

EXAMPLES The present invention will be described below based on examples.
In FIGS. 1A and 1B, 1 is a case made of aluminum or the like, and a thin explosion-proof valve 3 is provided on a bottom surface 2. Four
Is a capacitor element housed in this case 1, which is formed by stacking an aluminum anode foil and a cathode foil over a separator, and impregnated with an electrolytic solution. Reference numeral 5 is a lid attached to the opening 6 of the case 1, and is provided with terminals 7 and 8. The capacitor element 4 is connected to the terminals 7 and 8. Reference numeral 9 denotes an insulating cap made of insulating resin, which covers the case 1 from the bottom. Reference numeral 10 is a contact switch provided in the insulating cap 9, and its contacts 11 and 12 are arranged in the vicinity of the explosion-proof valve 3 and its terminal 1
3 and 14 are pulled out from the edge 15. Reference numeral 16 denotes a current fuse provided in the insulating cap 9, which is connected in series with the contact switch 10 and has its terminal 17 brought close to the terminal 14 of the contact switch 10 and pulled out from the edge 15.
Then, when connecting the case-encapsulated capacitor 18 to an external circuit, as shown in FIG.
And 8 and the terminals 13 and 14 of the contact switch 10, respectively. As a result, the contact switch 10 is connected in parallel with the capacitor element 4. At this time, the current fuse 16 is connected in series with the capacitor element 4. The terminals 7 and 8 and the terminals 13 and 14 may be connected to each other by a lead wire or the like separately from the external circuit.

In the above embodiment, when an overvoltage is applied to the capacitor 18 and the electrolytic solution decomposes to generate gas,
The internal pressure of case 1 rises. Therefore, as shown in FIG. 3A, the explosion-proof valve 3 swells, hits one contact 11 of the contact switch 10, and moves this contact 11 toward the other contact 12. And before the explosion-proof valve 3 is broken,
As shown in (b), the contact 11 contacts the contact 12. As a result, the capacitor element 4 is short-circuited by the contact switch 10. Therefore, a large current flows through the current fuse 16 and is blown. Due to the blowout of the current fuse 16, the gas pressure in the capacitor 18 is prevented from rising and the explosion-proof valve 3 is prevented from operating.

Next, an overvoltage application test was conducted on the above-mentioned embodiment and the conventional example to examine the operating condition of the explosion-proof valve. As the sample, 10 aluminum electrolytic capacitors rated at 200 V-680 μF each are used. The conventional example has the same structure as the above example except that the insulating cap is removed. The test conditions are an applied voltage of DC 300 V, a current of 7 AMAX, and an ambient temperature of room temperature. As a result of the test, in all the examples, the explosion-proof valves did not operate. Then, the current fuse incorporated in the test circuit was blown. On the other hand, in the conventional example, all explosion-proof valves were activated.

FIG. 4 shows another embodiment of the present invention.
In this embodiment, in particular, the explosion-proof valve 19 is provided on the side surface of the case 20. Then, the contact switch 21 arranges the contacts 22 and 23 in the vicinity of the explosion-proof valve 19 so that the insulating cap 24
In addition to being provided inside, the terminals 25 and 26 are drawn out from the edge 27. The current fuse 28 has an insulating cap 2
It is provided at a position facing the contacts 22 and 23 in FIG. 4, and its terminal 29 is brought close to the terminal 26 and pulled out from the edge 27. Also in the case of the case-containing capacitor 30 of this embodiment,
When connecting to an external circuit, the terminals 33 and 34 for the capacitor element 32 provided on the lid 31 are respectively connected to the terminals 25 and 26 of the contact switch 21, and the contact switch 21 is connected in parallel with the capacitor element 32 and in series. Current fuse 28
Are connected. Therefore, the gas pressure in the case 20 rises, the explosion-proof valve 19 swells, and the contacts 22 and 23 come into contact with each other. Due to this contact, the capacitor element 32 is short-circuited by the contact switch 21. Then, it is possible to prevent the current fuse 28 from being blown out and the explosion-proof valve 19 from operating.

Further, FIG. 5 shows another embodiment of the present invention. In this embodiment, as the capacitor element 35,
A cathode foil 36 having a structure protruding from the bottom surface is used.
Then, the capacitor element 35 is housed in the case 37 with the cathode foil 36 portion in contact with the bottom surface 38 of the case 37. The contact switch 39 has only one contact 40 and is arranged in the vicinity of the explosion-proof valve 41 provided on the bottom surface 38 of the case 37. The terminal 42 of the contact switch 39 is the edge 44 of the insulating cap 43.
Draw only one from The current fuse 45 is provided in the insulating cap 43 on the lead-out side of the terminal 42,
The terminal 46 is drawn out from the edge 44 close to the terminal 42. In this case, when the explosion-proof valve 41 contacts the bulge contact 40, the cathode foil 36 contacts the bottom surface 38 of the case 37, so that the capacitor element 35 is short-circuited by the contact switch 39. Due to this short circuit, the current fuse 45 is melted and the cased capacitor 47 can prevent the explosion-proof valve 41 from operating.

[0013]

As described above, according to the present invention, the case is covered with the insulating cap having the contact switch and the current fuse connected in series to the contact switch, and the contact switch is provided in the vicinity of the explosion-proof valve. And place it in
Since the contact switch is connected in parallel to the capacitor element and the current fuse is connected in series, the current fuse can be melted and blown by the operation of the contact switch, and the operation of the explosion proof valve can be prevented in advance, and other electronic parts will be damaged. A cased capacitor that can prevent the occurrence of

[Brief description of drawings]

FIG. 1 shows a front sectional view and a plan view of an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an embodiment of the present invention incorporated in a circuit.

FIG. 3 is a front sectional view showing an operating state of the explosion proof valve of the embodiment of the present invention.

FIG. 4 shows a front sectional view of another embodiment of the present invention.

FIG. 5 shows a front sectional view of another embodiment of the present invention.

[Explanation of symbols]

1, 20, 37 ... Case, 3, 19, 41 ... Explosion-proof valve,
4, 32, 35 ... Capacitor element, 9, 24, 43 ...
Insulating cap, 10, 21, 39 ... Contact switch,
16, 28, 45 ... Current fuses, 18, 30, 47 ...
A capacitor in a case.

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[Procedure amendment]

[Submission date] April 16, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

Claims (1)

[Claims] 1. In a case-encapsulated capacitor in which a capacitor element is housed in a case provided with an explosion-proof valve and terminals are drawn out and hermetically sealed, a contact switch located near the explosion-proof valve and a current fuse connected in series to the contact switch are provided. A case-encapsulated capacitor having an insulating cap that covers the case, the capacitor element being connected in parallel to the contact switch and being connected in series with the current fuse.