JPS6011638Y2 - Explosion-proof device for electrolytic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an explosion-proof device for electrolytic capacitors, and more particularly to an improvement in an explosion-proof device that maintains a constant gas pressure within a case.

Since the electrolytic capacitor has a polar structure, hydrogen gas is generated from its negative electrode foil, and this hydrogen gas fills the sealed case and increases the internal pressure of the case.

In particular, if the polarities are reversed and a reverse voltage is applied between the electrodes, or if an overvoltage is applied between the electrodes, hydrogen gas generation will rapidly increase and the internal pressure of the case will rise abnormally. Therefore, if the internal pressure of the case exceeds the allowable stress of the case, there is a risk of explosion.

If the electrolytic capacitor explodes, the electrolytic waves filled in the case will scatter and deteriorate the circuit components adjacent to the electrolytic capacitor, so in order to prevent the risk of explosion, Large electrolytic capacitors are equipped with explosion-proof equipment.

In addition, since electrolytic capacitors generate hydrogen gas not only in the above-mentioned abnormal conditions but also in normal usage conditions, in order to suppress the increase in internal pressure of the case due to hydrogen gas, the capacitor is gradually removed from the case. Explosion-proof devices having a structure for discharging hydrogen gas have been proposed.

FIG. 1 shows a conventional explosion-proof device.

In the figure, a sealing plate 6 is fitted into the opening of the case 4 in which the electrolytic capacitor element 2 is housed.
An open end 10 of the inwardly bent case 4 faces the step 8 provided at the edge of the case 4, and the open end 10 is embedded in a sealing member 12 inserted into the step 8.

A through hole 14 is bored in the sealing plate 6 of the case 4 which is tightly sealed in this way, and a cap having a flange 16 molded from a rubber plate that selectively transmits only hydrogen gas is inserted into the through hole 14. 18 is inserted from the back side of the sealing plate 6, and the through hole 14 is closed with this cap 18.

In such an explosion-proof device that also has a gas exhaust function in normal conditions, the ceiling of the cap 18 is thin, so that when the internal pressure of the case 4 increases, the ceiling of the cap 18 is exposed as shown by the broken line A. It will bulge out in the opposite direction.

The cap 18, which is molded from a rubber plate, has a certain degree of elasticity, but if it is constantly expanded by gas pressure, its elasticity will deteriorate, resulting in deterioration of capacitor characteristics due to electrolyte leakage and evaporation. Alternatively, due to thermal deterioration, the mechanical strength decreases, and even a slight increase in internal pressure causes the cap 18 to
There are disadvantages such as destruction.

Furthermore, since there is a risk that the cap 18 may bulge out even before use, there is also the drawback that it may be mistakenly determined to be a defective product.

One way to solve this problem is to make the ceiling of the cap 18 thicker.
In this case, destruction of the ceiling section is suppressed in an emergency, and it does not function as an explosion-proof device.

Note that when silicone rubber is used as the material for the cap 18, gas permeability is improved and the bulge of the ceiling can be avoided; however, since the ceiling is thin, evaporation of electrolyte, etc. increases, and the characteristics of the capacitor are affected. It has the disadvantage of significant deterioration and deterioration of life characteristics.

Further, the sealing plate 6 shown in FIG. 2 is made by bonding a rubber plate 6B that selectively transmits only hydrogen gas to the surface of a phenol laminate 6A, and has through holes 20 in the phenol laminate 6A.
This through hole 20 and a rubber plate 6B that closes this through hole 20 constitute an explosion-proof device.

This explosion-proof device also has the same drawbacks as the above-mentioned explosion-proof device.

FIG. 3 shows a part of case 4, and this case'
The permissible pressure strength of the case 4 is reduced by providing a groove 22 having a V-shaped cross section on the bottom surface of the case 4, and the groove 22 constitutes an explosion-proof device.

This explosion-proof device does not suffer from the above-mentioned inconveniences due to elastic deterioration, but if the case 4 is made of an aluminum plate, it has no hydrogen gas evacuation function under normal conditions, which suppresses the increase in the internal pressure of the case 4. That is difficult.

The purpose of this invention is to provide an explosion-proof device for an electrolytic capacitor that allows good discharge of hydrogen gas within the case, maintains the internal pressure of the case constant, and prevents characteristic deterioration.

This idea provides a pressure buffer chamber in the case or sealing plate of the electrolytic capacitor that is closed off with a shielding plate that selectively permeates and exhausts only the hydrogen gas generated within the case. It is characterized by the presence of a buffer chamber.

This invention will be described in detail below based on embodiments shown in the drawings.

FIG. 4 shows a preferred embodiment of an explosion-proof device for electrolytic capacitors.

In the figure, a synthetic resin sealing plate 36 is fitted into an opening 34 of a case 32 in which an electrolytic capacitor element 30 is sealed.

The end portion 40 of the case 32 bent inward is exposed to the stepped portion 38 formed at the edge of the sealing plate 36, and the end portion 40 of the case 32, which is bent inward, is exposed, and the sealing material 42 filled in the stepped portion 38 connects the end of the sealing plate 36 and the case 32. The case 32 is sealed with a sealing plate 36.

An electrode terminal 44 is passed through and fixed to the sealing plate 36, and a tab 46 connected to the electrode foil of the electrolytic capacitor element 30 is fixed to the electrode terminal 44 inside the case 32.

A through hole 48 is formed in the sealing plate 36, and a stepped portion 50 having a diameter larger than that of the through hole 46 is formed on the front and back surfaces of the sealing plate 36 at the opening edge of the through hole 46.
, 52 are provided.

The surfaces of the stepped portions 50 and 52 have protrusions 54 having a V-shaped cross section.
56 is provided protrudingly.

Shielding plates 58 and 60 made of a material such as silicone rubber that selectively transmits only hydrogen gas generated inside the case 32 are fitted into the stepped portions 50 and 52.
are engaged with the protrusions 54, 56 of the stepped portions 50, 52, and are firmly joined to the stepped portions 50, 52, ie, the sealing plate 36, with an adhesive or the like.

In this way, the through hole 46 of the sealing plate 36 is opened to the shielding plate 58.
60 is closed to form a pressure buffer chamber 62.

This pressure buffer chamber 62 is interposed between the internal pressure of the case 32 and the external pressure, and functions as a pressure buffer.

Therefore, the outside pressure is P. Then, the internal pressure P2 of the case 32 increases due to the generation of hydrogen gas, so the pressure buffer chamber 68
Since the internal pressure P1 is higher than the internal pressure P1, the pressure distribution is P.

<P□<P2 and changes in stages.

FIG. 5 shows this relationship, where a is the case 32, b is the shielding plate 60, C is the pressure buffer chamber 62, d is the shielding plate 58, and e is the outside air.

Further, on the surface of the shielding plate 58 facing the pressure buffer chamber 62 and the surface of the shielding plate 60 facing the inner surface of the case 32, portions with reduced pressure resistance, that is, recesses 64 and 66, are formed, respectively, to provide an explosion-proof function. It is in good condition.

With the above configuration, hydrogen gas generated in the electrolytic capacitor element 30 fills the case 32, and the internal pressure of the case 32 increases. However, when this internal pressure exceeds the pressure P2 shown in FIG. Gas flows into the pressure buffer chamber 62 from the shielding plate 60 .

This inflow increases the internal pressure of the pressure buffer chamber 62,
When the internal pressure exceeds the pressure P1 shown in FIG. 5, hydrogen gas is discharged from the shielding plate 58 to the outside air.

In this way, the pressure distribution changes stepwise, and the internal pressure of the case 32 communicates with the outside pressure via the pressure buffer chamber 62.

As a result, the hydrogen gas generated within the case 32 is discharged to the outside air while being maintained at a constant pressure, and the internal pressure of the case 32 is always maintained at a constant pressure P2.

The shielding plates 58, 60 that transmit hydrogen gas are composed of two sheets, and the pressure buffering effect is performed in the pressure buffering chamber 62 surrounded by the shielding plates 58, 60 and the sealing plate 36, so that the shielding plates The outward bulge of the shield plates 58, 60 is extremely small, and the elastic deterioration of the shield plates 58, 60 due to the discharge of □' hydrogen gas can be negligibly small.

Therefore, characteristic deterioration due to evaporation of the electrolytic solution of the electrolytic capacitor is suppressed, and the life of the electrolytic capacitor can be increased.

In particular, it is extremely advantageous that evaporation of the electrolyte is prevented.

In addition, if hydrogen gas is suddenly generated in an abnormal state such as application of reverse polarity voltage or overvoltage to the electrolytic capacitor element 30, and the internal pressure of the case 32 suddenly increases, the shielding plate 5
8.60 is destroyed and the hydrogen gas inside the case 32 is discharged to the outside air.

At that time, the recess 66 of the shielding plate 58 and the recess 6 of the shielding plate 60
8 makes it easy to destroy and has a good explosion-proof effect.

Note that in this embodiment, the protrusions 54 of the stepped portions 50 and 52
．． 56 can be tightly joined to the shielding plates 58 and 60, and the pressure distribution shown in FIG. 5 can be maintained with high precision.

In this embodiment, the through hole 48 constituting the pressure buffer chamber 62 is circular, but it may also be rectangular.
An orifice may be provided in the middle to adjust the pressure.

Providing an orifice is advantageous in that the outflow of the electrolyte in the case 32 can be restricted when the shielding plates 58, 60 break and hydrogen gas flows out.

Next, FIGS. 6 to 8 show other embodiments of this invention.

The explosion-proof device shown in FIG. 6 includes a sealing plate 36, a shielding plate 58.
In order to increase the strength of the joint with 60, joint members 70 and 72 are attached across the joint.

According to this embodiment, the degree of sealing of the pressure buffer chamber 62 can be maintained with high precision, and harmful effects such as peeling of the shielding plates 58, 60 due to long-term use can be reliably prevented.

In the explosion-proof device shown in FIG. 7, the walls that stand upright on the stepped portions 50 and 52 provided on the sealing plate 36 are inclined toward the opening, making the entrance portion narrow.

Therefore, the cross-sectional shape of the shielding plates 58 and 60 is made into a trapezoidal shape to match the shape described above, and as a result, the sealing plate 36
Coupled with the adhesive effect with the adhesive, the bonding with the adhesive becomes extremely high, and the same effects as in the embodiments described above can be obtained.

The explosion-proof device shown in FIG.
The through holes 48A, 48B, 48C form two shielding plates 58.
．． 60 and three pressure buffer chambers 62A, 62B,
62C is formed.

The pressure buffer chambers 62A, 62B, 62 of the shielding plate 58
The surface facing C has recesses 64A and 64B.

64C, and the surface of the shielding plate 60 facing the case 32 is similarly provided with recesses 66A, 66B, and 66C.

As in this embodiment, a plurality of pressure buffer chambers 62A, 62B
, 62C is suitable for large electrolytic capacitors, and can adjust the internal pressure of the case 32 and provide a good explosion-proof function.

Note that a spongy material having a pressure buffering effect may be inserted into the pressure buffering chamber of each embodiment, and in this way, a highly accurate pressure buffering effect can be expected.

Further, in each embodiment, the pressure buffer chamber is provided on the sealing plate, but the same effect can be obtained even if the pressure buffer chamber is provided on the case.

Next, FIG. 8 shows the experimental results.

The electrolytic capacitor used in the experiment was 35W■, 10000μ
The experiment was a high temperature load test at 105°C.

In FIG. 8, A shows the characteristics when the explosion-proof device of this invention is implemented, and B shows the characteristics of the conventional one.

As the test time (HR3) increases, the rate of change in capacitance increases, but since there is no evaporation of the electrolyte in the capacitor equipped with the explosion-proof device of this invention, the change is small and the degree of characteristic deterioration is small. I can understand small things.

As explained above, according to this invention, the hydrogen gas generated inside the case is better discharged, and the electrolyte inside the case is prevented from evaporating, thereby minimizing the deterioration of characteristics due to long-term use. I can do it.

In particular, the internal pressure of the case can be maintained constant at all times, helping to stabilize changes in characteristics and increasing the lifespan.

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams of a conventional explosion-proof device for electrolytic capacitors, and FIG. 4 is a longitudinal sectional view showing an embodiment of this invention.
FIG. 5 is an explanatory diagram showing pressure distribution, FIGS. 6 to 8 are longitudinal sectional views showing other embodiments, and FIG. 9 is an explanatory diagram showing experimental results. 32... Case, 36... Sealing plate, 5
8.60... Shielding plate, 62... Pressure buffer chamber.

Claims (2)

[Scope of utility model registration request] (1) Electrolytic capacitor case 32 or sealing plate 36
A pressure buffer chamber 62 that is closed with two shielding plates 58 and 60 that selectively transmits only the hydrogen gas generated within the case 32 is provided, and the internal pressure of the case 32 is connected to the pressure buffer chamber 62 through the pressure buffer chamber 62. An explosion-proof device for electrolytic capacitors characterized by applying external pressure. (2) Shielding plate 58°60 that closes the pressure buffer chamber 62
2. The explosion-proof device for an electrolytic capacitor according to claim 1, wherein a portion having low pressure resistance is provided on a surface portion of the case 32 on which internal pressure acts.