JPH0222982Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the prevention of cracks caused by temperature changes in a molded capacitor.

Conventionally, this type of capacitor has been constructed as shown in Figure 1, in which 1 is a capacitor element formed of a dielectric and electrodes, 2 is a synthetic resin in which the capacitor element 1 is molded, and the synthetic resin used here is The glass transition temperature of the resin 2 was approximately 90° C. or higher, taking into account the external ambient temperature and the internal heat generation temperature of the capacitor element 1.

In such a configuration, the coefficient of thermal expansion of the dielectric material, metal electrode, etc. forming the capacitor element 1 is different from that of the synthetic resin 2 for molding the capacitor element 1, so that the temperature when using this type of capacitor is different. Due to the change, expansion stress or contraction stress due to the above-mentioned difference in coefficient of thermal expansion is applied to the capacitor element 1 and the synthetic resin 2, and if this is repeated, cracks will eventually occur in the synthetic resin 2, which is a drawback.

In view of the above-mentioned points, this invention provides a molded capacitor that prevents the occurrence of cracks due to temperature changes by using two types of interior and exterior synthetic resins with different glass transition temperatures as the synthetic resins used to mold the capacitor element. It is something.

An embodiment of this invention is shown in FIG. 2 and will be described in detail below. In addition, in this figure, parts with the same reference numerals as those in FIG. 1 are the same or corresponding parts. In the illustrated example, the capacitor element 1 is molded with an interior synthetic resin 3 and an exterior synthetic resin 4 that is further molded around the interior synthetic resin 3. The interior synthetic resin 3 used to mold the capacitor element 1 has a glass transition temperature of about 10 DEG C. to 30 DEG C., and the exterior synthetic resin 4 has a glass transition temperature of 90 DEG C. or higher.

In this configuration, the interior synthetic resin 3 is made of a material with a glass transition temperature of about 10°C to 30°C because it exhibits a certain degree of elasticity at room temperature, and the exterior synthetic resin 4 is made of a material with a glass transition temperature of about 10°C to 30°C. For the reason explained above, a material with a glass transition temperature of 90°C or higher is used.

In such a configuration, the interior synthetic resin 3
has a glass transition temperature of about 10°C to 30°C, so
For example, if this type of capacitor is exposed to a high temperature higher than the glass transition temperature of the interior synthetic resin 3 (however, considering the external ambient temperature and the internal heat generation temperature of the capacitor element 1, it is thought to be up to about 80°C), Expansion stress due to the difference in thermal expansion coefficient between the dielectric and metal electrodes forming the capacitor element 1 and the exterior synthetic resin 4 can be absorbed and relaxed by the elasticity of the interior synthetic resin 3.

On the other hand, if it is exposed to a low temperature below the glass transition temperature of the interior synthetic resin 3, the interior synthetic resin 3 itself will harden and lose its elasticity, but its glass transition temperature is lower than that of the exterior synthetic resin 4. , the shrinkage stress due to the temperature difference is relaxed, and the shrinkage stress applied to the exterior synthetic resin 4 can be relaxed.

The capacitor element used in this invention is, for example, a wound type in which a thin dielectric material and electrode foil or a dielectric material with a vapor-deposited electrode is wound, or a capacitor element in which a ceramic material is used as the dielectric material. It may be a laminated type, or it may be unimpregnated, or it may be impregnated once.
In short, it is of course applicable to any device in which the capacitor element is molded from synthetic resin.

As explained above, according to this invention, the periphery of the capacitor element is constructed using two types of synthetic resins with different glass transition temperatures, so that the stress caused by expansion and contraction due to temperature changes in this type of capacitor can be alleviated. This has the effect of preventing cracks from occurring.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing a conventional example, and FIG. 2 is a front sectional view showing an embodiment of the present invention. 1: Capacitor element, 3: Interior synthetic resin, 4:
Exterior synthetic resin.

Claims (1)

[Scope of utility model registration request] The capacitor element is molded with interior synthetic resin,
A molded capacitor formed by molding the interior synthetic resin around the interior synthetic resin with an exterior synthetic resin having a glass transition temperature higher than that of the interior synthetic resin.