JPS6242371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an electrolytic capacitor, and more specifically, the present invention relates to a method for manufacturing an electrolytic capacitor. This invention relates to a method for sealing an electrolytic capacitor, which is placed in a shaped case and the open end is sealed.

Conventionally, an aluminum electrolytic capacitor has been constructed as shown in FIG. That is, a capacitor element 1 made by winding an anode foil and a cathode foil together with a separator and impregnating it with a driving electrolyte is placed in a bottomed cylindrical case 2, and the open end is provided with an outer diameter smaller than the inner diameter of the case 2. A sealing rubber 3 with a handle was inserted, and the open end was drawn together with the sealing rubber 3 to produce a product. Note that 4 is an external lead wire.

Recently, methods that do not involve drawing have been proposed as an improved sealing method. That is, the sealing is completed by pushing a sealing rubber having an outer diameter larger than the inner diameter of the case 1, which is a cylindrical case 1 with a bottom.

However, this method of manufacturing an aluminum electrolytic capacitor by press-fitting the sealing rubber has the following drawbacks. In other words, since the hardness of sealing rubber is low, when using it as a sealing material for aluminum electrolytic capacitors, the inner diameter of the bottomed cylindrical case is
The sealing rubber, which has a fairly large outer diameter, must be pushed in with a fairly large force.

Furthermore, since rubber has a large coefficient of friction, it does not easily slip, and an extremely large amount of force is used for pushing and inserting. The use of an extremely large force when inserting the capacitor is a major hindrance to the manufacturing method of electrolytic capacitors, and in particular hinders the speeding up of the manufacturing method and the stabilization of product quality. In other words, when the product is inserted with a large pressing force, a large inertial force still acts upon completion of the insertion, which puts pressure on the internal elements, resulting in leakage current defects in the product.

As described above, due to variations in the dimensions of the case, particularly variations in the dimensions of the open end and the bottom, and variations in the thickness of the sealing rubber material, the capacitor element comes into contact with the inner bottom of the case, causing leakage current defects in the product.

Furthermore, it is generally extremely difficult to process rubber-like elastic bodies to size, and sealing rubber is no exception. especially,
When sealing is performed by the press-fitting method, no external compressive force due to so-called drawing is applied to the sealing rubber. In the conventional press-fitting method, sealability was maintained only by the repulsive force of the press-fitted sealing rubber. Therefore, the quality of the sealing property mainly depends on the outer diameter and density of the sealing rubber.

In this way, it is extremely difficult to produce sealing rubber for aluminum electrolytic capacitors in large quantities at a constant size and density at a low cost, and variations in sealing rubber result in
Conventional press-fitting methods have caused variations in the characteristics of aluminum electrolytic capacitors, particularly variations in lifespan and electrolyte leakage problems.

The present invention eliminates such conventional drawbacks, and uses a synthetic resin sealing member for an electrolytic capacitor, and completes the electrolytic capacitor by press-fitting it with a small force, thereby obtaining an electrolytic capacitor with less variation in characteristics. The purpose is to

In order to achieve this purpose, in the present invention,
The sealing member is composed only of a non-rubber-like elastic body with a friction coefficient of 0.7 or less, and the electrolytic capacitor is sealed by a press-fitting method.

With this configuration, the electrolytic capacitor is press-fitted with a non-rubber-like elastic body that has an outer diameter slightly larger than the inner diameter of the bottomed cylindrical case.
It is preferable to use non-rubber-like elastic bodies because it does not require a larger force than the conventional method, and non-rubber-like elastic bodies are much easier to process than rubber-like elastic bodies, and products with better dimensional accuracy can be obtained. The sealing properties of the electrolytic capacitor obtained by the method of press-fitting and sealing are uniform, and an electrolytic capacitor with less variation in product characteristics can be obtained.

Hereinafter, one embodiment of the present invention will be described using the drawings of FIGS. 2 to 4. Note that in FIGS. 2 and 3, the same parts as in FIG. 1 are given the same numbers.

In the figure, 1 is a capacitor element wound in a conventional manner and impregnated with a driving electrolyte. An external lead wire 4 is connected to this. A sealing member 5 made of a non-rubber-like elastic material and having an outer diameter slightly larger than the inner diameter of a conventional bottomed cylindrical case 2 is press-fitted into the case 2 using the slope of the insertion guide 6. Electrolytic capacitors are composed of:

The non-rubber-like elastic body used as the sealing member 5 according to the present invention has the following properties, that is, it contracts slightly while moving on the inclined surface of the insertion guide 6;
Any item that can be restored to its original state when placed in Case 2 is fine. As materials having this property, polytetrafluoroethylene, polyethylene trifluoride, chlorotrifluoroethylene, polyethylene, polypropylene, tetrafluoroethylene-hexafluoropolypropylene copolymer, etc. were effective. Moreover, these composites can also achieve the intended purpose.

Further, in the electrolytic capacitor according to the present invention, since the sealing member 5 made of a non-rubber-like elastic body is press-fitted using the insertion guide 6, the sealing property is maintained by the restoring force at the time when it passes through the smallest part of the insertion guide 6. Therefore, the ratio between the inner diameter of the bottomed cylindrical case 2 and the outer diameter of the sealing member 5 is extremely important. Of course, if it is too large, a large force will be required in the press-fitting method, and if it is even larger, it will not be press-fitted. In addition, if it is small, sealing will not be done substantially,
The life of the aluminum electrolytic capacitor will be extremely short due to leakage and evaporation of the electrolyte (so-called dry up).

As a result of various studies regarding this point, the present inventors determined that the optimal value was 2 for the bottomed cylindrical case.
It was found that the ratio between the inner diameter of the sealing member 5 and the outer diameter of the sealing member 5 made of a non-rubber-like elastic body was 1.01 to 1.15. That is, according to the experimental results, in order to ensure the airtightness of the sealing part, the outer diameter of the sealing member 5 should be 1.01 times or more compared to the inner diameter of the case 2, and the sealing member 5 should not be attached to the case 2. In terms of workability when pushing in, the outer diameter of the sealing member 5 is smaller than the inner diameter of the case 2.
It was found that it is sufficient if it is 1.15 times or less. For these reasons, by setting the ratio of the inner diameter of the case 2 and the outer diameter of the sealing member 5 to 1.01 to 1.15, good airtightness and workability during press-fitting can be achieved.

Furthermore, since the aluminum electrolytic capacitor according to the present invention uses a method in which the sealing member 5 made of a non-rubber-like elastic body is slid on the inclined surface of the insertion guide 6,
The coefficient of friction of the sealing member 5 made of a non-rubber-like elastic material is important for the efficiency of carrying out the press-fitting method.
If the coefficient of friction is large, a large force is naturally required for press-fitting, and it is desirable from the viewpoint of workability that the pushing force at press-fit is 1 kg or less. The inventors also conducted various studies on the coefficient of friction, and found that the optimal value for keeping the pushing force below 1 kg was 0.7.
I got the following.

FIG. 4 is a diagram showing the relationship between the coefficient of friction and the pushing force when pushing the sealing member into the case.

As is clear from FIG. 4, in order to reduce the pushing force to 1 kg or less, the friction coefficient of the sealing member 5 must be set to 0.7.
It is necessary to do the following.

Here, in the aluminum electrolytic capacitor according to the present invention, a sealing member 5 made of a non-rubber-like elastic material is press-fitted into the open end of the case 2, and the coefficient of friction of the sealing member 5 made of a non-rubber-like elastic material is important. If the coefficient of friction is large, a large force will be required when press-fitting the sealing member 5. In this regard, in the present invention,
The sealing member is made of a non-rubber-like elastic material with a coefficient of friction of 0.7 or less, and even if a non-rubber-like elastic material is used and it is press-fitted into the open end of the case, it can be done with a small force and a large amount of force. Since there is no room for inertial force to act, there is no characteristic disadvantage such as an increase in leakage current.

As described above, according to the method of manufacturing an electrolytic capacitor of the present invention, since the sealing member made of only a non-rubber-like elastic material is used and the sealing is performed by press-fitting, the drawing process is performed using a sealing member made of a rubber-like elastic material. Alternatively, productivity is improved compared to the conventional method of sealing by press-fitting, and since press-fitting is performed with a small force, there is no room for large inertial forces to work, so there is no possibility of characteristic deterioration such as increased leakage current. Not at all. In addition, the manufacturing method is simple because the sealing member made of a non-rubber-like elastic material can be processed with extremely high precision, and the ratio of the inner diameter of the case to the outer diameter of the sealing member can be reduced. Therefore, it is possible to obtain an electrolytic capacitor of stable quality with little variation in sealing performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional aluminum electrolytic capacitor, and FIG. 2 is a sectional view showing an aluminum electrolytic capacitor obtained by a manufacturing method according to an embodiment of the present invention.
Figure 3 is a cross-sectional view showing the sealing method of the capacitor.
FIG. 4 is a characteristic diagram showing the relationship between the friction coefficient of the sealing member and the pushing force into the case. 1... Capacitor element, 2... Case, 5...
Sealing member.

Claims (1)

[Claims] 1. Electrode foil is wound together with a separator, and a capacitor element impregnated with electrolyte is housed in a bottomed cylindrical metal case, and the open end of the metal case is made of a non-rubber-like elastic body with a friction coefficient of 0.7 or less. A method for manufacturing an electrolytic capacitor, in which a sealing member is press-fitted to seal the cap, and the ratio of the inner diameter of the metal case to the outer diameter of the sealing member is 1.01 to 1.15.