JPH0737434A - Ignition cable - Google Patents

Abstract

PURPOSE:To improve mechanical strength such as rupture strength, etc., without degrading flexibility in processing and, bending, etc., and to protect from corrosion in the case of adhesion of fuel, oil, etc. CONSTITUTION:A fluororesin coating which has higher mechanical strength than silicon rubber and high resistance to fuel, oil, etc., is formed on the outer circumference of a silicon rubber sheath layer 4. The thickness is made from 0.1mm or thicker to 0.3mm or thinner so as not to degrade the flexibility in processing and bending.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage resistance electric wire used in an ignition device of an internal combustion engine.
For commercial use or for general commercial use.

[0002]

2. Description of the Related Art Conventionally, for this type of high voltage electric wire, for example, the one shown in FIGS. 3 and 4 has been used. In the winding structure type of FIG. 3, a metal wire 2 made of a nichrome wire is tightly wound on a magnetic core 1, and an insulator 3 and a sheath layer 4 made of silicon rubber or the like are coated on the metal wire 2. ing. Figure 4
In the resistance cord type, the resistance cord core 5 formed by impregnating the glass fiber with the resistance material is covered with the insulator 3 and the sheath layer 4 made of silicon rubber or the like.

[0003]

However, when the sheath layer 4 for high-voltage wires is made of silicone rubber, mechanical strength such as tear resistance is low. In order to satisfy such a problem, in the past, a partial EPDM (e
styrene-propyrene-diene-t
Although an erpolymer rubber tube, an EPDM rubber sponge, a polyethylene tube and the like have been used as cord protectors, they have not been sufficiently satisfactory in heat resistance and oil resistance. Further, while silicon rubber has excellent heat resistance, it has a problem that it is significantly swelled when fuel (gasoline, etc.) adheres to it.

An object of the present invention is to improve the mechanical strength of a sheath material made of silicone rubber and prevent deterioration when fuel or oil adheres.

[0005]

In order to achieve the above object, the present invention provides a resistance conductor 1 as shown in FIGS. 1 and 2.
Alternatively, the ignition cable having the resistance cord core 5, the insulating layer 3 and the sheath layer 4 is characterized by being coated with the fluororesin 6.

[0006]

The fluororesin has a higher mechanical strength than the conventional protective sheath layer made of silicone rubber and can improve the tear strength and the like. Further, the fluororesin is less likely to swell even if fuel (gasoline or the like) is attached thereto, and can improve oil resistance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a high voltage resistance electric wire which is a first embodiment of the present invention. In this embodiment, the resistance conductor 1 is formed by winding a metal wire 2 made of a nichrome wire around a core wire formed by extruding a glass fiber reinforcing material with rubber containing ferrite and covering the resistance conductor 1. The rubber insulator layer 3 is formed. Furthermore, EPD
A silicon rubber sheath layer 4 is formed on the M insulator layer 3 and further has a thickness of 0.1 mm or more and 0.3 mm on the outer periphery thereof.
The following fluororesin 6 is coated. If it is less than 0.1 mm, the mechanical strength is insufficient (see FIG. 5), and
This is because if it is larger than 3 mm, the workability and flexibility as an ignition cable are impaired (see FIG. 6).

The fluororesin may be of a tubular shape that is loosely fitted to the outer periphery of the silicone rubber sheath layer 4 and then contracts by being heated to be fixed to the sheath layer.

FIG. 2 shows a high voltage resistance electric wire according to a second embodiment of the present invention. In the second embodiment, the resistance core 5 is different from the resistance conductor 1 and the metal wire 2 of the first embodiment, but the EPDM rubber insulator layer 3, the silicone rubber sheath layer 4, and the fluororesin 6 are used. Have the same structure.

[0010]

As described above, the high-voltage resistance electric wire coated with the fluororesin of the present invention has flexibility in workability and flexibility as an ignition cable by reducing the thickness of the fluororesin coated. It is possible to improve mechanical strength and prevent deterioration when fuel or the like adheres without causing a problem of damage.

[0011]

[Brief description of drawings]

FIG. 1 is a perspective view of an ignition cable according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an ignition cable according to a second embodiment of the present invention.

FIG. 3 is a perspective view of a conventional product.

FIG. 4 is a perspective view of another conventional product.

FIG. 5 is a graph showing the tensile strength when the thickness of the fluororesin according to the present invention is changed.

FIG. 6 is a graph showing flexibility when the thickness of the fluororesin according to the present invention is changed.

[Explanation of symbols]

 1 Resistance Conductor 2 Metal Wire 3 Insulator Layer 4 Sheath Layer 5 Resistance String Core 6 Fluorine Resin

Claims (2)

[Claims] 1. A high-voltage resistance electric wire having a silicone rubber sheath layer, wherein the sheath layer has an outer periphery covered with a fluororesin. 2. A high-voltage resistance electric wire, characterized in that the fluororesin according to claim 1 is in the form of a tube, and the tube shrinks when heated and is fixed to the sheath layer.