JPH03199672A - Insulating cap for power distribution device and its manufacture - Google Patents

Abstract

PURPOSE:To provide electric insulation and electromagnetic wave shielding by providing an inner layer consisting of an electric insulator layer at a part of the inside at the lower part of an insulating cap and an outer layer consisting of an electromagnetic wave shielding layer at a part of a boundary surface to the inner layer at the lower part. CONSTITUTION:A central electrode 2, a side electrode 4, a central electrode high voltage distributing circuit 3, a side electrode high voltage distributing circuit 5 and so on are embedded. An inner layer 11 provided with a peeling-off preventing groove 13 at a part of the inside at the lower part is formed. The inner layer 11 consists of an electric insulator layer, and the outer layer 9 consists of an electromagnetic wave shielding layer. It is thus possible to provide excellent electric insulation and electromagnetic wave shielding quality which is opposite to this quality at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an insulating cap for a power distributor (hereinafter referred to as an insulating cap) used for ignition of an automobile engine, and a method for manufacturing the same.

(Prior Art) As shown in FIG. 3, a conventional insulating cap has a carbon electrode 6 attached to the upper part of the inside at approximately the center via a spring 8 with its tip protruding downward, and an electrical insulator 1. Inside the center electrode 2. Center electrode high voltage distribution circuit 3. Side electrode 4. It has a structure in which the side electrode high voltage power distribution circuit 5 is buried.

The insulating cap is attached by passing a bolt (not shown) through the metal fitting 7 and fixing it to the main body of the power distribution device (not shown).

Conventionally, thermoplastic polymer molding materials such as polypropylene resin, polybutylene terephthalate resin, polyethylene terephthalate resin, etc. Epoxy resin, phenolic resin,
Thermosetting polymer molding materials such as polyester resin were used.

(Problem to be Solved by the Invention) However, although the molding material shown above has excellent electrical insulation properties, it has the disadvantage that magnetic wave shielding properties cannot be imparted at the same time because they are inverse properties to electrical insulation properties. There is.

In order to provide electromagnetic shielding properties, it is sufficient to use electromagnetic shielding polymer molding materials that can lower electrical resistance and provide conductivity, but this material is not suitable for insulating caps that require high voltage insulation. Such molding materials cannot be used alone.

To overcome this drawback, it is possible to form the inner layer with an electrically insulating material and coat the outer layer with electromagnetic shielding paint, but this method is not only time-consuming and expensive, but also requires a thick coating. It is difficult to obtain a suitable thickness, and it also has the disadvantage of poor adhesion and easy peeling.

SUMMARY OF THE INVENTION The object of the present invention is to provide an insulating cap that eliminates the above-mentioned drawbacks and a method for manufacturing the same.

Fi! Means for Solving the Problem) The present invention has a carbon electrode attached to the inner upper part approximately at the center via a spring with its tip protruding downward, and further includes a center electrode and side electrodes in an electrical insulator. , an insulating cap in which a center electrode high voltage power distribution circuit and a side electrode high voltage power distribution circuit are embedded; It has a carbon electrode attached via a spring with its tip protruding downward.

Furthermore, in a method for manufacturing an insulating cap in which a center electrode, side electrodes, a center electrode high-voltage power distribution circuit, and a side electrode high-voltage power distribution circuit are embedded in an electrical insulator, an electrically insulating polymer molding material is injected into a mold and molded. The present invention relates to an M-adic method for an insulating cap, in which the inner layer is formed by injection molding, and the outer layer is formed by injection molding by injecting an electromagnetic shielding polymer molding material into a mold, or by injection molding.

In the present invention, the inner layer refers to the inner layer of the resulting insulating cap, and the outer layer refers to the outer layer of the resulting insulating camp.

There are no particular restrictions on the thickness of each layer, but it is desirable that the inner layer that performs electrical insulation has a thickness that provides the necessary electrical insulation performance and allows efficient injection molding work.
It is preferable that the thickness of the handle 1 is, for example, 0.5 to 4 mm. It is desirable that the outer layer, which shares the electromagnetic shielding performance, impart the necessary electromagnetic shielding performance and have a thickness that allows efficient injection molding work.9 For example, 1.5 to 4 m+
It is preferable that the thickness of the case be .

The inner layer in the present invention can be formed of a non-foamed electrical insulating layer or a foamed electrical insulating layer.

It is preferable to form the electrical insulating layer using an electrically insulating polymer molding material containing a foaming agent in the inner layer, since this is effective in preventing the generation of large bubbles.

In the present invention, the polymer molding materials for electrical insulation include polypropylene resin, polybutylene terephthalate resin, and polyethylene terephthalate resin.

Thermoplastic polymer molding materials such as polyethylene resin, polyvinyl chloride resin, IJ2 ethylene resin, polyacrylonitrile butadiene styrene resin, polycarbonate resin, and thermosetting polymer molding materials such as epoxy resin, phenol resin, polyester resin, etc. material is used.

Polymer molding materials for electromagnetic wave shielding include the above-mentioned thermoplastic resins and thermosetting resins, as well as copper and aluminum.

Fine metal wires such as brass and stainless steel, metal powders, thin wire cuttings, carbon fibers, carbon powders, etc. are mixed in to achieve a specific volume resistivity of 100Ω and a surface resistivity of 100Ω.
A molding material adjusted to around Ω is used.

The blowing agent used is azodicarbonamide.

Benzene sulfonyl hydrazide and the like are used, and there are no particular limitations, but it is preferable to use a blowing agent that decomposes and gasifies at a temperature higher than the melting temperature of the molding material used.

According to the molding method (injection molding, injection molding) according to the present invention, the inner layer of the electrical insulator layer and the outer layer of the electromagnetic shielding layer can be integrated in close contact with each other.

It is preferable to form peel-preventing grooves, peel-preventing hooks, etc. on the boundary surfaces of each layer of the insulating cap, since this is effective in preventing peeling at the boundary surfaces. There are no particular restrictions on the shapes of the peeling prevention grooves and peeling prevention hooks.

(Example) The present invention will be explained in detail below.

Example 1 Polypropylene resin molding material containing Tal 240 weight (manufactured by Hitachi Chemical Mold Co., Ltd., trade name Highform M40 B)
) is injection molded to form a center electrode 2. as shown in FIG. Side electrode 4. An inner layer 11 was formed in which the center electrode high-voltage power distribution circuit 3, the side electrode high-voltage power distribution circuit 5, etc. were embedded, and a peel-preventing groove 13 as shown in FIG. 2 was provided in a part of the inside of the lower part. The resulting molded product with inner layer 11 does not eject from the mold! It was left in the mold on the casing core side.

The thickness of the inner layer 11 was 2 mm at the thinnest point and Fi7 at the thickest point.

Next, the mold on the cavity side is replaced with a mold with a gap equal to the thickness of the outer layer, the mold is closed, and metal fibers are added to this gap to increase the specific volume resistivity to lo0Ω-■ and the surface resistivity to 400.
Polypropylene resin-based electromagnetic wave shielding polymer molding material adjusted to Ω (manufactured by Sumitomo Bakelite Co., Ltd., product name: Sumikon F)
M-CP301) is injection molded (filled) to form the lower inner layer 1.
An insulating cap having a two-layer structure as shown in FIG. 1 was obtained by forming an outer layer 9 having a thickness of 2111 m and having a peel-preventing catch 12 as shown in FIG. In addition, the outer layer is equipped with an insulating cap that absorbs electromagnetic waves on the surface using gold AM.
It was designed to leak into the main body metal A (not shown). Furthermore, a grounding portion 10 was formed between the outer layer and the insulating cap fitting to allow leakage to the main body fitting (not shown) through the mounting screw (not shown).

Observation of the appearance of the obtained insulation cap.

The surfaces of the inner layer and outer layer were smooth and had good transfer of the surface of the mold. Further, there was no peeling at the interface between the inner layer and the outer layer, and the adhesion was good, and in some areas the two were fused.

In FIG. 1, reference numeral 6 indicates a carbon electrode, and reference numeral 8 indicates a spring that constantly presses the carbon electrode against a mating component (not shown, but a rotating electrode, usually called a rotor head).

Example 2 Polypropylene/resin molding material containing 40 wt% talc (manufactured by Hitachi Kasei Mold Co., Ltd., trade name Highform M40B) 9
Example 1 except that the inner layer was molded by injection molding a molding material containing 9.7% by weight and 0.3% by weight of azodicarbonamide (manufactured by Santsutsu Kasei Co., Ltd., trade name Cellmic CE) added as a foaming agent. A two-layer insulating cap was obtained through a similar process.

When we cut and observed a cross-section of the inner layer of the resulting insulating cap, we found that the thickness was 7-7 at the thickest point, but there were only small bubbles with a diameter of about 1 mm in that area, but there were large bubbles. I was not able to admit.

There was no peeling at the interface between the inner layer and outer layer of the casing, and the adhesion was good, with the two fused together in some areas.

Example 3 The same inner layer as in Example 1 was formed through the same steps as in Example 1. After forming the inner layer, it was left for a while, so the surface temperature dropped. For this purpose, an infrared lamp was installed on the upper surface of the inner layer to heat the inner layer to a surface temperature of 125°C. After heating, the mold on the cavity side was replaced with a mold with a gap equal to the thickness of the outer layer, and the mold was closed.The molding materials of Example 1 and P1 were injection molded into the gap of the mold to create an example. An insulating cap with a two-layer structure having an outer layer similar to that in Example 1 was obtained.

When the appearance of the obtained insulating cap was observed, it was found that the surfaces of the inner layer and outer layer were smooth and had good transfer of the surface of the mold. There was no peeling at the interface between the inner layer and outer layer of the casing, and the adhesion was good, with the two fused together in some areas.

In button embodiment 3, an infrared lamp was used to heat the inner layer, but the present invention is not limited to this method, and heating may be performed using an induction heating device using high frequency electromagnetic waves. Various methods for elevating can be used.

Example 4 An epoxy resin molding material with a volume resistivity of 1014 to 1QI5Ω- mark and a surface resistivity of 1015 to 10]6Ω was used as an electrically insulating polymer molding material for molding the inner layer.
Manufactured by Hitachi Chemical Co., Ltd., product name Stand light CE CE
-J-610), mold the outer layer with a volume specific resistivity of 1
00Ω-cm K I! An insulating cap having a two-layer structure similar to that in Example 1 was obtained by using the molding material prepared in II and going through the same steps as in Example 1.

The obtained insulating cap had beautiful inner and outer layers, and there was no peeling at the interface between the inner layer and the outer layer.

(Effect of the invention) According to the present invention, the following effects can be obtained.

(1) It has excellent electrical insulation properties and can simultaneously provide electromagnetic wave shielding properties, which are the opposite characteristics.

(2) It is efficient because molding can be done in a short time. As a result, an insulating cap having magnetic wave shielding performance can be manufactured at low cost.

(3) Excellent adhesion at the interface between the inner and outer layers, allowing for easy peeling.

(4) If a molding material containing a foaming agent is used in the inner layer, the generation of large bubbles can be prevented, resulting in excellent insulation performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an insulating cap according to an embodiment of the present invention.
FIG. 2 is an enlarged view of section A in FIG. 1, and FIG. 3 is a sectional view of a conventional insulating cap. Explanation of symbols 1... Electric insulator 2... Center electrode 3...
Center electrode high voltage power distribution circuit 4...Side electrode 5...Side electrode high voltage power distribution circuit 6...Carbon electrode 7...Insulation cap mounting bracket 8...Spring 9...Outer layer 10... Grounding part 11 between the outer layer and the insulating cap mounting bracket...inner layer
12... Hook for preventing peeling is part 13... Groove for preventing peeling Fig. 1 Fig. 3

Claims (1)

[Scope of Claims] 1. A carbon electrode is attached to the upper part of the inner side at approximately the center via a spring so that its tip protrudes downward, and a center electrode, side electrodes, and a center electrode are provided in the electrical insulator. An insulating cap for a power distributor in which a high-voltage power distribution circuit and a side electrode high-voltage power distribution circuit are embedded, the inner layer of which is made of an electrical insulator layer and the outer layer of which is an electromagnetic wave shielding layer. 2. The insulating cap for a power distributor according to claim 1, wherein the inner layer is made of a non-foamed electrical insulating material layer or a foamed electrical insulating material. 3. A carbon electrode is attached to the upper center of the inner side with its tip protruding downward via a spring, and the center electrode, side electrodes, center electrode high voltage distribution circuit, and side electrodes are installed in the electrical insulator. In a method of manufacturing an insulating cap for a power distribution device in which an electrode high-voltage distribution circuit is embedded, an electrically insulating polymer molding material is injected into a mold and molded, or an inner layer is formed by injection molding, and a polymer molding material for electromagnetic wave shielding is formed. A method of manufacturing an insulating cap for a power distributor, characterized in that the outer layer is formed by injecting a material into a mold or by injection molding. 4. The method for manufacturing an insulating cap for a power distributor according to claim 3, wherein the inner layer is molded with an electrically insulating polymer molding material that does not contain a foaming agent or is molded with an electrically insulating polymer molding material that contains a foaming agent.