JPH03217661A - Ignition coil by cylinder for internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition coil for an internal combustion engine, and particularly to means for preventing radio noise generated when an ignition coil is directly connected to a spark plug without using a high-voltage wire. It is something.

[Conventional technology]

Conventional means for preventing radio noise in this type of ignition coil are as follows:
For example, as shown in Japanese Unexamined Patent Publication No. 63-58910, a secondary bobbin made of an insulating material has a resistivity of lO to 103ΩCa.
There is one in which a cylindrical high-voltage terminal made of conductive resin is assembled and this high-voltage terminal is connected to a terminal of a spark plug via an elastic metal terminal.

[Problem to be solved by the invention]

However, in the conventional apparatus described above, after the high voltage terminal made of conductive resin is molded, a thin resin insulating layer is inevitably formed on the surface of the conductive resin (high voltage terminal surface). Therefore, if a terminal with elasticity is attached directly to a high voltage terminal made of conductive resin, the conductive resin (
There is a problem in that corona discharge occurs between the terminal (high voltage terminal) and the high voltage terminal made of conductive resin deteriorates.

Therefore, an object of the present invention is to prevent deterioration of a high voltage terminal made of conductive resin for preventing radio wave noise.

[Means to solve the problem]

Therefore, as a means to solve the problem, the present invention provides a secondary coil and a 3 to 50k
The secondary coil high voltage terminal of the high voltage terminal includes a high voltage terminal made of conductive resin having a resistance value of Ω, and a spring having one end connected to the high voltage terminal and the other end connected to the spark plug. The present invention proposes a cylinder-specific ignition coil for an internal combustion engine, characterized in that a conductor is fixed to the connection part with the spring and the connection part with the spring. Also, 2
3 connected to the secondary coil and the high voltage terminal of this secondary coil.
The secondary coil high voltage of the high voltage terminal is equipped with a high voltage terminal made of conductive resin having a resistance value of ~50 kΩ, and a spring whose one end is connected to the high voltage terminal and the other end is connected to the spark plug. The present invention also proposes a cylinder-specific ignition coil for an internal combustion engine, characterized in that a conductor is fixed to a connection portion with a terminal, and one end of the spring is embedded and fixed in the high-voltage terminal.

[Operation] This allows 3 to 50k between the ignition coil and the spring.
High frequency noise can be reduced by connecting a high voltage terminal made of conductive resin with a resistance value of Ω. Further, since the conductor is fixed to the connection portion of the high voltage terminal with the secondary coil high voltage terminal and the connection portion with the spring, it is possible to improve conduction at each of the connection portions and prevent corona discharge.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

A first embodiment is shown in FIGS. 1-3. FIG. 1 is a sectional view of a main part showing the configuration of an embodiment of the present invention, FIG. 2 is an enlarged front view of a high voltage terminal in the ignition coil of the present invention shown in FIG. 1, and FIG. 3 is an enlarged front view of the high voltage terminal. FIG.

1 is a coil body having a primary coil and a secondary coil wound on an iron core, 2 is a high voltage terminal of the secondary coil, 3 is a high voltage terminal, 4 is a metal coil spring, and 5 is a rubber cylinder. The secondary coil high-voltage terminal 2 has a chrysanthemum socket at the connection part with the high-voltage terminal 3, and the conical part 7 at one end of the high-voltage terminal 3 is inserted into it to connect the secondary coil and the high-voltage terminal 3. . Further, as shown in FIG. 2, an annular groove 6 for locking the coil spring 4 is provided on the outer periphery of the cylindrical base 9 at the bottom of the high voltage terminal to prevent the coil spring 4 from falling off. In addition, the high voltage terminal 3 is set to 3 to 5 in order to reduce high frequency noise generated from the ignition device.
Molded from conductive resin with a resistance value of 0kΩ.

The molding method will be described later. This conductive resin is polybrobylene (PP), polybutylene terephthalate 1- (
As shown in FIG. 4, the volume resistivity of this thermoplastic resin can be changed depending on the amount of carbon black added. Conductive resin (
The volume resistivity of the high voltage terminal (high voltage terminal) is determined by the cylindrical portion 8 shown in FIG. Since the cylindrical portion 8 is a cylinder with a cross-sectional area S and a length ρ, the volume resistivity of the cylindrical portion (specific resistance of the high voltage terminal) is expressed by the following equation.

R=ρ)l/S...■ R: Resistance value of high voltage terminal (Ω) ρ: Volume specific resistance value (ΩCll)! = Length of the cylindrical portion 8 (cva) S: Cross-sectional area of the cylindrical portion 8 (ciJ) The resistance R of any high voltage terminal can be obtained from the formula (■). Further, conductive layers 10 and 11, which are conductors, are formed on the entire outer surfaces of the conical portion 7 and the cylindrical base portion 9, which are dotted in FIG.
is formed. The conductive layers 10 and 11 are formed using a conductive paint integral molding method (for example, Japanese Patent Application Laid-open No. 111335/1983).
By using this, it is possible to integrally form the high voltage terminal 3 made of conductive resin when molding it.

In this example, a conductive paint made of 88 wt % Ni and 12 wt % acrylic and charged to about -50 kV is electrostatically applied to portions corresponding to the conical portion 7 and cylindrical base 9 of a preheated molding die. Then, a conductive resin made of nylon 6-6 containing carbon black was injected into the mold, and the molding temperature was 115°C and the resin temperature was 270°C.
A high voltage terminal 3 having a resistance value of Ω is obtained. Here, instead of nylon 6-6, PBT (
Polybutylene terephthalate, nylon 6-10, PE
T (polyethylene terephthalate) may also be used. Note that the thickness of the conductive layers 10 and l1 at this time is about 50 μm as shown in FIG.

Since the conductive layer formed by this method is integrally formed during high-pressure terminal molding, the conductive layer 10 has a high degree of adhesion due to the pressure and heat during molding, and the anchoring effect of the conductive paint in the conductive resin. , l1 can be obtained. This conductive layer 1
0,11 is fixed on the conductive resin surface (high voltage terminal 3
Since no insulating layer is formed on the surface), it is possible to prevent corona discharge from occurring at the connection portion between the high voltage terminal 3 and the secondary coil high voltage terminal 2 and the connection portion between the coil spring 4. Therefore, the high voltage terminal 3 does not deteriorate.

A second embodiment will be described based on FIG. This embodiment is the same as the first embodiment except for the method of fixing the conductive layer to the high voltage terminal. In the second embodiment, after molding the high voltage terminal 3 with a conductive resin, a conductive paint forming a conductor is applied to the cylindrical base l3 of the conical part 12 in FIG. 5 to obtain a conductive layer.

A third embodiment will be explained based on FIG. The difference from the first and second embodiments is that metal is used as the conductor instead of the conductive layer. In the high voltage terminal 3, a metal such as copper, which has excellent electrical conductivity, is used for each of the conical portion 14, which is the connection portion with the secondary coil high voltage terminal 2, and the cylindrical base portion 16, which is the connection portion with the spring coil. Metal parts 14 and 1
6 is insert molded into conductive resin 15. Further, the metal portion 16 is provided with an annular groove l7 for locking the coil spring 4, as in the first embodiment. The high voltage terminal 3 made of conductive resin to which metal is fixed has improved conductivity at the connection portion with the high voltage terminal 2 of the secondary coil and the connection portion with the coil spring 4.

A fourth embodiment will be explained based on FIG. 7. The difference from the first and second embodiments is that the cylindrical base 18, which is the connecting part between the high voltage terminal and the coil spring, does not have an annular groove for locking the conductive layer and the coil spring. This is because one end of the coil spring 4 is inserted and fixed by insert molding. By insert-molding the coil spring 4 into the cylindrical base 18 of the high voltage terminal, the electrical conductivity at the connection portion can be improved and the coil spring 4 can be prevented from falling off from the high voltage terminal 3.

A plate spring may be used instead of the coil spring used in the above embodiments.

〔Effect of the invention〕

As described above, in the present invention, the high voltage terminal made of conductive resin assembled between the ignition coil and the spark plug has the effect of preventing radio noise. By fixing a conductor to the connection part with the coil spring or insert-molding the high voltage terminal and the coil spring, there is an excellent effect of preventing corona discharge and preventing deterioration of the high voltage terminal.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view of essential parts showing the configuration of a first embodiment of an ignition coil for an internal combustion engine according to the present invention, FIG. 2 is an enlarged front view of a high voltage terminal in the coil shown in FIG. 1, and FIG. 2 is a partially sectional front view showing a further enlarged view of the high voltage terminal shown in FIG. 2; FIG. FIG. 4 is a characteristic diagram of the material of the high-pressure terminal in the ignition device of the present invention. FIGS. 5 and 6 are partially sectional front views showing enlarged high-pressure terminals in second and third embodiments of the present invention, respectively. FIG. 7 shows the fourth embodiment of the present invention.
FIG. 2 is a sectional view of a main part of an ignition coil in an embodiment. 2...Secondary coil high voltage terminal. 3...High pressure terminal, 4...Coil spring forming a spring, 10,
11... Conductive layer forming a conductor, 14.15... Metal piece forming a conductor. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7

Claims (2)

[Claims] (1) In a cylinder-specific ignition coil for an internal combustion engine that is directly connected to the spark plug without using a high-voltage wire, a conductive resin with a resistance value of 3 to 50 kΩ is connected to the secondary coil and the high-voltage terminal of this secondary coil. a spring having one end connected to the high voltage terminal and the other end connected to the ignition plug, and a connecting portion of the high voltage terminal to the secondary coil high voltage terminal and the spring. A cylinder-specific ignition coil for an internal combustion engine, characterized in that a conductor is fixed to the connection part. (2) In a cylinder-specific ignition coil for an internal combustion engine that is directly connected to the spark plug without using a high-voltage wire, a conductive coil with a resistance value of 3 to 50 Ω is connected to the secondary coil and the high-voltage terminal of this secondary coil. a high voltage terminal made of a rubber resin; and a spring having one end connected to the high voltage terminal and the other end connected to the spark plug, and a conductor connected to the secondary coil high voltage terminal of the high voltage terminal. A cylinder-specific ignition coil for an internal combustion engine, characterized in that the spring is firmly fixed and one end of the spring is embedded and fixed in the high-pressure terminal.