JP2720559B2 - Ignition switch cap for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition power distribution device cap for an internal combustion engine, and more particularly to a means for preventing radio noise generated in a power distribution device.

[Prior art] Conventionally, as means for preventing radio noise of an ignition distributor for an internal combustion engine, as shown in Nippon Denso Publication Technical Report No. 16-075 (issued on October 20, 1979), it is embedded in a power distribution cap. The center electrode and the side electrode are formed of a conductive resin to which a conductive additive such as carbon is added.

[Problems to be solved by the invention]

However, in the above-described conventional apparatus, a thin resin insulating layer is inevitably formed on the surface of the conductive resin (electrode surface) after molding the electrode made of the conductive resin. Therefore, when a distribution contact is directly connected to an electrode made of a conductive resin, a corona discharge occurs between the electrode (conductive resin) and the distribution contact, causing a problem that the electrode made of the conductive resin is deteriorated.

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

[Means for solving the problem]

Accordingly, the present invention provides a means for solving the problem, a distribution contact contacting a brush integrated with a distribution rotor, and a 3 to 50 kΩ connecting the distribution contact and an ignition coil.
A center electrode made of a conductive resin having a resistance value of: a conductor is fixed to a contact portion of the center electrode with the distribution contact, and a conductor is connected to a connection portion of the center electrode with the ignition coil. The present invention proposes an ignition distributor cap for an internal combustion engine, wherein the cap is fixed.

[Action]

Thus, high-frequency noise can be reduced by using an electrode made of a conductive resin having a resistance value of 3 to 50 kΩ to connect the distribution contact and the ignition coil. In addition, since the conductor is fixed to the contact portion of the electrode with the distribution contact and the connection portion with the ignition coil, the conduction at each of the connection portions can be improved to prevent corona discharge.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A first embodiment is shown in FIG. 1 and FIG. FIG. 1 is a sectional view of a main part showing a configuration of an embodiment of the present invention, and FIG. 2 is an enlarged front view of a center electrode in the power distribution device shown in FIG. 1 is a resin cap for enclosing the power distribution body, 2 is a carbon coil contact having one end connected to the secondary high voltage terminal 12a of the ignition coil, and 3 is connected to a brush integrated with the power distribution rotor. Distribution contact made of carbon, 4 is coil contact 2
A central electrode that connects the power supply and the distribution contact 3 is embedded and fixed in the cap 1. 5 is a coil spring for pressing the coil contact 2 against the ignition coil, 6 is a coil spring for pressing the distribution contact against the distribution rotor, 7 and 8
Is a conductive layer that is a conductor fixed to the center electrode, 9 is a brush that connects the distribution contact 3 to the side electrode 11, and 10 is a distribution rotor that distributes voltage to each cylinder, and the brush 9 is fixed. Reference numeral 11 denotes a side electrode provided for each cylinder, which is embedded and fixed in the cap 1. Reference numeral 12 denotes an ignition coil having a primary coil and a secondary coil, which is fixed in the ignition distributor. 13 is a rotating shaft connected to the engine camshaft,
Reference numeral 14 denotes a signal rotor fixed to the rotating shaft 13, and reference numeral 15 denotes an electromagnetic pickup that emits a signal in accordance with the rotation of the signal rotor 14.

The center electrode 4 is formed of a conductive resin having a resistance of 3 to 50 kΩ in order to reduce high frequency noise generated by the ignition coil. The molding method will be described later. This conductive resin is made of a thermoplastic resin such as polypropylene (PP) or polybutylene terephthalate (PBT). As shown in FIG. 3, the thermoplastic resin changes its volume resistivity according to the amount of carbon black added. be able to. 7, 8
Is a conductive layer forming a conductor. The conductive layers 7 and 8 are formed on the surface of each contact housing hole of the center electrode 4 when the center electrode 4 made of a conductive resin is formed by using a conductive paint integral forming method (for example, Japanese Patent Laid-Open No. 111335/1986). It can be formed integrally as a whole. In this embodiment, Ni 88 wt%,
A conductive paint made of acrylic 12 wt% and charged to about -50 kV is electrostatically applied to portions corresponding to the conductive layers 7 and 8 of the preheated molding die. Then, a conductive resin made of nylon 6-6 containing carbon black was injected into a molding die to obtain a center electrode 4 having a resistance value of 10 kΩ under molding conditions of a mold temperature of 115 ° C. and a resin temperature of 270 ° C. . At this time, the conductive layer 7,
8 has a thickness of about 50 μm. Here, PBT (polybutylene terephthalate), nylon 6-10, or PET (polyethylene terephthalate) shown in FIG. 3 may be used instead of nylon 6-6. Since the conductive layer (conductor) formed by this method is integrally formed at the time of molding the center electrode, the adhesion is high due to the pressure, heat, and the anchoring effect of the conductive paint into the conductive resin at the time of molding. The conductive layers 7 and 8 can be obtained. Since an insulating layer is not formed on the surface (center electrode) of the conductive resin to which the conductive layers 7 and 8 are fixed, corona discharge occurs at the connection between the center electrode 4 and the coil contact 2 and the connection between the distribution contact 3. Can be prevented from occurring. Therefore, the center electrode is not deteriorated.

A second embodiment will be described with reference to FIG. The second embodiment is the same as the first embodiment except for the method of fixing the conductive layer to the center electrode. In the second embodiment, after the center electrode 4 is molded with a conductive resin, a conductive paint serving as a conductor is applied to a connection portion 16 (contact housing hole) between the center electrode 4 and the coil contact 2 in FIG. Then, a conductive layer is obtained by applying to the connecting portion 17 (contact receiving hole) between the center electrode 4 and the distribution contact.

A description will be given based on the third embodiment and FIG. The difference from the first and second embodiments is that a metal is used as the conductor instead of the conductive layer. The cylindrical portion 18 (contact receiving hole) serving as a connection portion between the center electrode 4 and the coil contact 2 and the distribution contact 3
A metal such as copper, which is excellent in conductivity, is used for the cylindrical portion 19 (contact receiving hole) serving as a connecting portion with the contact portion. Metal tube
18 and 19 are insert-molded in the conductive resin (center electrode) 4. The center electrode 4 made of a conductive resin to which a metal is fixed,
The center electrode 4 formed of the connection portion with the coil contact 2 is located at the connection portion with the coil contact 2 and the connection portion with the distribution contact 3 so that the conductivity is improved, and corona discharge can be prevented.

In the first to third embodiments, the distributor cap of the ignition coil integrated type distributor is used. However, in the case of the distributor cap in which the ignition coil and the distributor are connected through a high-voltage cord, a conductive resin cap is used. The conductor may be fixed to the connection portion of the center electrode with the high voltage cord.

〔The invention's effect〕

As described above, in the present invention, since the radio noise can be prevented by the center electrode made of a conductive resin having a resistance value of 3 to 50 KΩ attached between the ignition coil and the power distribution rotor, the radio noise preventing resistor is separately provided. There is no need to prepare the body, which has the effect of reducing costs.Furthermore, since the conductor is fixed to the connection of the center electrode to the ignition coil and the connection to the distribution contact, each connection is Has an excellent effect of preventing corona discharge and preventing the center electrode from being deteriorated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a main part of a first embodiment of a power distribution device for an internal combustion engine according to the present invention, and FIG. 2 is an enlarged view of a center electrode in the power distribution device shown in FIG. FIG. 3 is a longitudinal sectional view, and FIG. 3 is a characteristic diagram of the material of the center electrode in the ignition distributor of the present invention.
FIGS. 4 and 5 are enlarged longitudinal sectional views showing the center electrode in the second and third embodiments of the present invention. 2 ... Coil contact, 3 ... Distribution contact, 4 ... Center electrode,
7, 8... A conductive layer forming a conductor, 18, 19... A metal cylinder forming a conductor.

Claims (1)

(57) [Claims] 1. A distribution contact contacting a brush integrated with a distribution rotor, and a center electrode made of a conductive resin having a resistance of 3 to 50 kΩ for connecting the distribution contact and an ignition coil. An ignition conductor for an internal combustion engine, wherein a conductor is fixed to a contact portion of the center electrode with the distribution contact, and a conductor is fixed to a connection portion of the center electrode to an ignition coil. cap.