JP3459120B2 - Electrolytic capacitor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor, and more particularly to improvement of its explosion-proof device.

[0002]

2. Description of the Related Art Conventionally, a large-sized electrolytic capacitor having a screw-type external terminal is constructed as shown in FIG.
That is, in FIG. 4, first, reference numeral 1 is a capacitor element having the internal lead terminal 2. The capacitor element 1 is formed by winding an anode foil and a cathode foil together with an insulating spacer such as capacitor paper and impregnating a driving electrolytic solution. The anode foil and the cathode foil used in this capacitor element 1 are formed by electrochemically roughening a high-purity aluminum foil to increase the surface area and forming a dielectric oxide film by anodic oxidation. is there. Next, in FIG.
3 is a molded terminal board. As shown in FIG. 5, the molded terminal plate 3 includes a screw-type external terminal 4 arranged so as to penetrate the molded terminal plate 3, and a rivet portion 5 provided at one end of the external terminal 4. ing. Further, as shown in FIG. 4, the internal lead-out terminal 2 of the capacitor element 1 is connected to the rivet portion 5.

In such a connected state, the capacitor element 1 is housed in the bottomed cylindrical metal case 6, and the molded terminal plate 3 covers the opening of the metal case 6. It is attached to the case 6. In this case, the rubber ring 7 is provided on the outer peripheral portion of the outer surface of the molded terminal plate 3.
Is arranged, and the open end of the metal case 6 bites into the rubber ring 7 by the winding process.
The metal case 6 and the molded terminal plate 3 are hermetically sealed.

By the way, an electrolytic capacitor having such a structure may have an overvoltage due to a circuit abnormality or the like during its use.
When a reverse voltage or an overcurrent is applied, the internal pressure rises rapidly. Then, this increase in internal pressure causes explosion of the electrolytic capacitor. Therefore, in order to prevent the electrolytic capacitor from exploding, it is necessary to suppress the rise of the internal pressure of the electrolytic capacitor. For this reason, in general, an electrolytic capacitor has an explosion-proof device 1 as shown in FIG.
0 is provided. As shown in FIG. 6, the explosion-proof device 10 includes a small diameter portion 11a provided in a part of the molded terminal plate 3.
And the explosion-proof hole 11 including the large-diameter portion 11b, and the explosion-proof hole 11
Explosion-proof valve 1 made of thin rubber and arranged on the large-diameter portion 11b side of the
2 and a metal washer 13 for fixing the explosion-proof valve 12
It consists of and. By providing such an explosion-proof device 10, when the internal pressure of the electrolytic capacitor rises, the internal pressure can be released to the outside to prevent the explosion. That is, when the internal pressure of the electrolytic capacitor in FIG. 6 rises sharply, the internal pressure rises because the internal pressure is released and the explosion-proof valve 12 of the explosion-proof device 10 opens in a tearing manner. It can be suppressed.

[0005]

However, the electrolytic capacitor of FIG. 4 having the above structure has the following problems. That is, in the electrolytic capacitor shown in FIG. 4, since the material of the explosion-proof valve 12 of the explosion-proof device 10 is rubber as described above, the explosion-proof valve 12 made of rubber is accompanied by the change in quality of the rubber over time. Deteriorates during use of the electrolytic capacitor. Specifically, the hardness of the rubber forming the explosion-proof valve 12 increases with time and the tear strength thereof increases. As a result, the operating pressure of the explosion-proof valve 12 changes with time and gradually increases.

As described above, the rubber explosion-proof valve 12
If the operating pressure becomes higher due to the change with time, the explosion-proof valve 12 may not open when the internal pressure of the capacitor rises due to a circuit abnormality or the like. If the explosion-proof valve 12 does not open when the internal pressure of the capacitor rises, the internal pressure of the capacitor becomes remarkably high and the molded terminal plate 3 is broken and scattered to explode the capacitor, or the internal capacitor There is a possibility of short circuit and ignition at, which is a fatal problem for safety.

The present invention has been proposed in order to solve the above problems of the prior art, and its purpose is to:
An object of the present invention is to provide a highly safe electrolytic capacitor having a stable and high explosion-proof function that does not change with time.

More specifically, the object of the invention as set forth in claim 1 is to avoid the deterioration of the explosion-proof function over time due to deterioration of the material of the explosion-proof valve over time, and to ensure that the explosion-proof valve is fixed to the terminal board under normal conditions. Keeps the electrolytic capacitor sealed and keeps the capacitor highly reliable, reduces the size and simplifies the explosion-proof device, increases the degree of freedom in design, and simplifies the manufacturing process. By providing a weak point in terms of strength, its explosion-proof function is improved.
An object of the invention described in claim 2 is to increase the degree of freedom in designing an explosion-proof device and facilitate the manufacturing process thereof by appropriately selecting the material of the explosion-proof valve.

[0009]

According to the present invention, an anode foil and a cathode foil are wound together with an insulating spacer and impregnated with a driving electrolytic solution to form a capacitor element, and an internal lead terminal of this capacitor element is connected to a terminal plate. In the electrolytic capacitor, the capacitor element is housed in a cylindrical metal case with a bottom in a state of being connected to an external terminal penetrating the terminal plate, and the space between the open end of the metal case and the terminal plate is sealed. Has an explosion-proof device that includes a metal-made explosion-proof valve that has an explosion-proof hole that penetrates through the front and back, and that has a groove that is thinner than other parts in one part so as to block this explosion-proof hole. Is characterized by.

Further, the explosion-proof valve is characterized by being made of aluminum.

[0011]

The function of the electrolytic capacitor of the present invention having the above construction is as follows. That is, according to the invention of claim 1, since the material of the explosion-proof valve of the electrolytic capacitor is metal, as in the case of using the rubber explosion-proof valve,
The deterioration of the material of the explosion-proof valve does not cause the explosion-proof function to deteriorate during the use of the electrolytic capacitor. That is, the explosion-proof valve made of metal can maintain a predetermined performance as the explosion-proof valve for a long period of time, as compared with the explosion-proof valve made of rubber. Therefore, if a sudden pressure rise occurs inside the electrolytic capacitor due to a circuit abnormality during long-term use, the explosion-proof valve will surely destroy and release the internal gas, and the internal pressure of the capacitor thereafter. The rise can be surely suppressed. Therefore,
The terminal plate does not break and scatter due to the rise in the internal pressure of the capacitor, and as a result, the electrolytic capacitor can be prevented from exploding, and there is no possibility of causing a short circuit or ignition inside the capacitor. According to the second aspect of the present invention, the explosion-proof valve is inserted into the terminal plate to form the explosion-proof device, so that the explosion-proof valve is securely fixed to the terminal plate and the sealed state of the inside of the capacitor during normal operation is maintained. It can be surely held, and the reliability of the capacitor can be maintained high.
Since the explosion-proof device can be made as small and simple as possible, the degree of freedom in design can be increased and the manufacturing process thereof can be facilitated. Furthermore, by providing a groove in a part of the explosion-proof valve, this part becomes a weak point in strength of the explosion-proof valve. Therefore, when a rapid pressure increase occurs inside the electrolytic capacitor during long-term use, the explosion-proof valve can be more reliably broken and the internal gas can be released, starting from this groove.

According to the second aspect of the present invention, the explosion-proof valve is inserted into the terminal plate to form the explosion-proof device, so that the explosion-proof valve is securely fixed to the terminal plate and the inside of the capacitor is normally sealed. Can be reliably held, and the reliability of the capacitor can be maintained high. Moreover, since the explosion-proof device can be made as small and simple as possible, the degree of freedom in design can be increased and the manufacturing process thereof can be facilitated. According to the third aspect of the present invention, by providing the groove portion in a part of the explosion-proof valve, this part becomes a weak point in strength of the explosion-proof valve.
Therefore, when a rapid pressure increase occurs inside the electrolytic capacitor during long-term use, the explosion-proof valve can be more reliably broken and the internal gas can be released, starting from this groove.

According to the invention of claim 4, since aluminum is used as the material of the explosion-proof valve, the aluminum explosion-proof valve can be used as an explosion-proof valve for a longer period of time than the rubber explosion-proof valve. Because it can maintain the prescribed performance of
When the internal pressure of the electrolytic capacitor rises, the explosion-proof valve can be reliably destroyed to release the internal gas. Further, by using aluminum, which is a material having excellent workability, the degree of freedom in designing the explosion-proof device can be increased and the manufacturing process thereof can be facilitated. In particular, aluminum is also a material used for the electrode foil of the capacitor element, so the number of types of materials used in the manufacturing process of the electrolytic capacitor can be reduced as much as possible, and from this point also the manufacturing process is further simplified. be able to. Further, since aluminum is cheap, there is also an advantage that an increase in manufacturing cost can be prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment to which the invention described in claims 1 to 4 of the present invention is applied will be described below with reference to FIGS. It should be noted that the same parts as those of the conventional example of FIG.

As shown in FIG. 1, the molded terminal board 3 of this embodiment is provided with an explosion-proof device 20 according to the present invention.
As shown in FIG. 2, the explosion-proof device 20 includes a molded terminal board 3
It has an explosion-proof hole 21 penetrating therethrough and an explosion-proof valve 22 arranged so as to close the explosion-proof hole 21. In this case, the explosion-proof valve 22 is configured as a part of the aluminum explosion-proof valve unit 23, and the explosion-proof valve unit 23 is inserted and molded in the molded terminal plate 3. That is, the explosion-proof valve unit 23 made of aluminum is formed in a lower opening type case shape as shown in FIG. 3, and has an explosion-proof valve 22 corresponding to the upper surface portion and a cylindrical shape that supports the periphery of the explosion-proof valve 22. The support portion 24 and a mounting and fixing portion 25 protruding outward from the lower end portion of the support portion 24 in a brim shape are provided. And
In this explosion-proof valve unit 23 made of aluminum, the inner peripheral surface of the cylindrical support portion 24 is substantially coincident with the inner peripheral surface of the explosion-proof hole 21, and the mounting fixing portion 25 is embedded in the molded terminal board 3. So that it is fixed. Also, the explosion-proof valve 22
A groove portion 26 having a smaller wall thickness than the other portions is provided in a part of the. The other parts are configured in exactly the same manner as the conventional example shown in FIG.

The operation of this embodiment having the above construction is as follows. First, in the present embodiment, since the material of the explosion-proof valve 22 provided as a part of the explosion-proof valve unit 23 is aluminum, the use of the electrolytic capacitor during the use of the electrolytic capacitor as in the prior art using the rubber explosion-proof valve 12 is prohibited. In addition, deterioration of the explosion-proof function due to deterioration of the material of the explosion-proof valve 22 does not occur, and the predetermined performance of the explosion-proof valve 22 can be maintained for a long period of time. Moreover, in particular, in this embodiment, since the thin groove portion 26 is provided in a part of the explosion-proof valve 22, this part is a weak point in strength of the explosion-proof valve 22. Therefore, when a sudden pressure increase occurs inside the electrolytic capacitor due to a circuit abnormality or the like during long-term use, the explosion-proof valve 22 is reliably destroyed from the groove portion 26 to release the internal gas, It is possible to reliably suppress the subsequent increase in the internal pressure of the condenser. Therefore, unlike the conventional case, the terminal plate is not broken and scattered due to the rise of the internal pressure of the capacitor, and as a result, the electrolytic capacitor can be prevented from exploding, and there is no possibility of causing a short circuit or ignition inside the capacitor.

Further, in this embodiment, since the explosion-proof valve unit 23 made of aluminum including the explosion-proof valve 22 is inserted and molded into the molded terminal plate 3 to form the explosion-proof device 20, the explosion-proof valve 22 is reliably molded. By fixing it to the terminal plate 3, the sealed state of the electrolytic capacitor under normal conditions can be reliably maintained, and the reliability of the capacitor can be maintained high. In addition, a single explosion-proof valve unit 23 including the explosion-proof valve 22 is formed into the molded terminal board 3
The explosion-proof device 20, which is formed by insert molding in, has a small number of parts, is extremely small and simple, and can be easily arranged in a small space. Therefore, this small explosion-proof device 20 can be freely arranged at any position of the molded terminal plate 3, and the degree of freedom in design is high. and again,
As described above, it is extremely easy to manufacture the small and simple explosion-proof device 20, which leads to the simplification of the entire manufacturing process of the electrolytic capacitor.

Moreover, in this embodiment, the explosion-proof valve unit 2
By using aluminum, which is a material having excellent workability, as the material of No. 3, the degree of freedom in designing the explosion-proof device 20 can be increased and the manufacturing process thereof can be facilitated. In particular, since aluminum is also a material used for the electrode foil of the capacitor element 1, it is possible to reduce the kinds of materials used in the manufacturing process of the electrolytic capacitor as much as possible. From this point as well, the manufacturing process is further simplified. can do. Further, since aluminum is cheap, there is also an advantage that an increase in manufacturing cost can be prevented.

As described above, according to this embodiment, by using the explosion-proof valve unit 23 including the aluminum explosion-proof valve 22, the explosion-proof valve generated in the conventional example in which the rubber explosion-proof valve 12 is used. Since the problem of the change with time can be solved, it is possible to provide a highly safe electrolytic capacitor having a stable and high explosion-proof function as compared with the conventional one. Also,
In order to more specifically show the effect of this embodiment,
Actually, electrolytic capacitors based on the present invention and the prior art were produced, and a life test and an explosion-proof valve operation test were performed under the same conditions. The results of this actual comparative test will be described below.

First, as an electrolytic capacitor, rated 400
A product having the explosion-proof device 20 of FIG. 1 (invention product A) and a rubber-made explosion-proof device 10 of FIG.
A product having the above (conventional product B) was produced. The material of the molded terminal plate 3 is polyphenylene sulfide (PPS) for both the product A of the present invention and the conventional product B. The explosion-proof valve unit 23 made of aluminum of the product A of the present invention has an outer diameter of 10.0 mm,
Outer diameter of mounting / fixing portion 25 is 14.0 mm, valve opening pressure is 18.0
It was configured as kg / cm ² . Then, a life test and an explosion-proof valve operation test were performed on both the product A of the present invention and the conventional product B under the same conditions. That is, first, a voltage of 400 V was applied for 5000 hours at a temperature of 85 ° C. to perform a life test, and then an overvoltage of 650 V and an inrush current of 4000 A was applied to perform an explosion-proof valve operation test. The results of the explosion-proof valve operation test in this case are shown in Table 1 below.

[0021]

[Table 1]

As shown in Table 1, in the case of the conventional product B, the valve operation was as low as 60%, the terminal plate of 40% was broken, and the ignition was present in 25%. ing. On the other hand, in the product A of the present invention, 100% of the products perform the valve operation, and the terminal plate is not broken or ignited at all. This result indicates that the effect of the product A of the present invention, that is, since the explosion-proof valve 22 operates even in the product after the life test, the molded terminal plate 3 is not destroyed even when the internal pressure rises, and there is a risk of ignition. It proves to be extremely safe.

The present invention is not limited to the above embodiment, and the specific structure of the explosion-proof valve can be changed as appropriate. For example, it is possible to use a metal other than aluminum as the material of the explosion-proof valve, and it is also possible to use an alloy or a ceramic. Further, the structure for fixing the explosion-proof valve to the terminal plate can be appropriately selected.

[0024]

As described above, according to the present invention, by providing a metal explosion-proof valve on a terminal plate, it is possible to provide a highly safe electrolytic capacitor having a stable and high explosion-proof function without change over time. You can

[Brief description of drawings]

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

FIG. 2 is a sectional view showing the molded terminal plate of FIG.

3 is a sectional view showing an explosion-proof valve unit that constitutes the explosion-proof device of FIG.

FIG. 4 is a sectional view showing an example of a conventional electrolytic capacitor.

5 is a cross-sectional view showing the molded terminal plate of FIG.

6 is a cross-sectional view showing an explosion-proof device provided on the molded terminal board of FIG.

[Explanation of symbols]

1 ... Capacitor element 2 ... Internal lead-out terminal 3 ... Molded terminal board 4 ... External terminal 5 ... Rivet part 6 ... Metal case 7 ... Rubber ring 10 ... Explosion-proof device 11 ... Explosion-proof hole 11a ... small diameter part 11b ... Large diameter part 12 ... Explosion-proof valve 13 ... washers 20 ... Explosion-proof device 21 ... Explosion-proof hole 22 ... Explosion-proof valve 23 ... Explosion-proof valve unit 24 ... Supporting part 25 ... Mounting and fixing part 26 ... Groove

Claims (2)

(57) [Claims] 1. An anode foil and a cathode foil are wound together with an insulating spacer and impregnated with a driving electrolyte to form a capacitor element, and an internal lead terminal of this capacitor element is connected to an external terminal penetrating a terminal plate. In this state, the capacitor element is housed in a cylindrical metal case having a bottom, and the open end of the metal case is hermetically sealed between the terminal plate and the terminal plate. And an explosion-proof device including a metal explosion-proof valve having a groove portion thinner in thickness than other portions so as to close the explosion-proof hole. 2. The electrolytic capacitor according to claim 1, wherein the explosion-proof valve is made of aluminum.