JPH03105072A - Ignition coil with directly connected type plug - Google Patents

Abstract

PURPOSE:To improve the electric connection between respective parts by forming one edge part of an ignition coil at a connection part to a coil spring and the other edge part on a contact surface part with the head part electrode of a spark plug respectively and arranging a connecting member between these parts. CONSTITUTION:The main part of an ignition coil is constituted of a housing1 made of PBT resin, etc., which is molded so as to integrally cover the primary and secondary coils and a core, a high voltage tower 2 which is molded by the same material and in the same process as those of the housing 1 and erected from the surface of the housing 1, a coil spring 3 inserted into the inside of the high voltage tower 2, and a spring connecting member 4. The spring connecting member 4 is pressed by the head part electrode of a spark plug which is inserted into an insulating cylinder 24 and not shown in the figure, and the coil spring 3 is compressed by the spring connecting member 4. The spark plug, therefore, is connected in an electrically favorably manner to a high voltage terminal 5.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an improvement in a direct plug type ignition coil.

[Prior Art] FIG. 6 shows a conventional example of a plug-directly connected ignition coil, that is, a spark plug-directly connected ignition coil.

In this direct plug type ignition coil, a resistor 3e for noise prevention is integrally molded at the root of a cylindrical insulating high voltage tower 20 extending from a housing 1e.
One end of e is connected to an output end of a secondary coil (not shown), and the other end is connected to a head electrode (not shown) of a spark plug via a high voltage terminal 4e and a coil spring 5e.

[Problems to be Solved by the Invention] However, in the above-described conventional plug directly connected ignition coil, the resistor 3e is connected to the high voltage tower 20 and the housing 1e.
It is integrally molded with the ignition coil, especially the high voltage tower 20.
The structure of the resistor and its manufacturing process become complicated, and even if the resistor
There was a problem in that resistor b could not be replaced alone due to a problem with resistor e.

The present invention has been made in view of the above problems, and an object to be solved is to provide a plug-directly connected ignition coil that has a simple structure and excellent maintainability.

[Means for Solving the Problems] A direct plug connection type ignition coil of the present invention includes an insulating housing that accommodates a primary coil, a secondary coil, and a core therein, and a high voltage terminal connected to an output end of the secondary coil. a high-voltage tower made of an insulating cylinder with a tip opening that stands upright from the housing surface surrounding the high-voltage tower; a coil spring that is inserted into the high-voltage tower and has one end in contact with the high-voltage terminal; The connecting portion is a connecting portion connected to the other end of the coil spring, the other end is a contact surface portion that can come into contact with the head electrode of the spark plug, and the connecting portion and the contact surface portion are connected to each other. and a spring connecting member having an electrical resistance value effective for reducing high frequency noise.

The above electric resistance value of the spring connecting member is 0.5 to 10
It is preferable to set it to about k ohm.

[Operation] The spring connecting member is inserted into the high voltage tower with the connecting part connected to the other end of the coil spring, and then the head electrode of the spark plug is brought into surface contact with the contact surface of the spring connecting member, and the spring connecting member is connected to the other end of the coil spring. When the member is pressed, the spring connecting member compresses the coil spring while keeping its posture stable.

As a result, contact between the head electrode of the spark plug and the contact surface portion of the spring connecting member, contact between the connecting portion of the spring connecting member and the other end of the coil spring, and contact between one end of the coil spring and the high voltage terminal, This spring connection member provides a good and stable condition, and the appropriately set electrical resistance of the spring connection member prevents the interference of noise radio waves from the spark plug.

[Example] Hereinafter, an example of the direct plug type ignition coil of the present invention will be described with reference to FIG.

This direct-plug type ignition coil includes a housing 1 made of PBT resin that is shaped to temporarily cover the primary, secondary coils and core (not shown), and a housing 1 that is made of the same material and molded in the same process as the housing 1. It consists of a high-pressure tower 2 that is erected from the surface of the housing 1, and a coil spring 3 and a spring connecting member 4 that are inserted into the high-pressure tower 2.

The high voltage tower 2 has a cylindrical shape with an open end, and a long cylindrical high voltage terminal 5 extending from the inside of the housing 1 is coaxially embedded in the hole 20 of the high voltage tower 2.

The tip of the high-voltage terminal 5 almost reaches the tip opening of the high-voltage tower 2, and the tip of the high-voltage terminal 5 has a bottomed accommodation recess 51 with one end open and communicating with the opening of the high-voltage tower 2.
is drilled. The high voltage terminal 5 is connected to the output end of the secondary coil buried inside the housing 1, and the other end of the secondary coil and both ends of the primary coil are connected to each other (not shown) that protrudes from the housing 1. connected to the terminal. Ring-shaped protrusions 21 and 22 are expanded on the outer peripheral surface near the tip of the high-pressure tower 2 at a small distance from each other, and a ring-shaped connecting recess 23 is formed between the ring-shaped protrusions 21 and 22. It is formed. A large-diameter portion of an insulating cylinder 24 made of silicone rubber, which is open at both ends and has a large diameter at one half, is fitted into the tip of the high-pressure tower 2. The part is coaxial with the hole 20 of the high pressure tower 2.

The inner circumferential surface of the large-diameter portion of the insulating cylinder 24 is in close contact with the outer circumferential surface of the tip of the high-voltage tower 2, and the tip of the large-diameter portion of the insulating cylinder 24 is slightly bulged in the inner radial direction so that the tip of the high-voltage tower 2 It fits into the connecting recess 23.

The coil spring 3 is made of stainless steel and is inserted into the accommodation recess 51 of the high voltage terminal 5, and one end thereof is inserted into the accommodation recess 51.
is fixed to the bottom of the The diameter of the bottom of the housing recess 51 is increased to prevent one end of the coil spring 3 from being pulled out, and the diameter of the one end of the coil spring 3 is also increased accordingly.

The spring connecting member 4 is engaged with the coil spring 3, and most of it is accommodated in the accommodation recess 5 of the high voltage terminal 5. The spring connecting member 4, as shown in FIG.
For example, it has a resistor part 41 made of a metal oxide such as tin oxide, titanium oxide, or zinc oxide and having a substantially short-axis cylindrical shape, and one end of the resistor part 41 constitutes a contact surface part as referred to in the present invention. An aluminum cap 42 is shown. The other end of the resistor portion 41 is a connecting portion 43 according to the present invention, and the connecting portion 43 includes a neck portion 44 and a head portion 45 coaxial with the center portion of the resistor portion 41 .

The neck portion 44 is formed into a disk shape with a smaller diameter than the center portion of the resistor portion 41 and protrudes from the center portion of the resistor portion 41 along the axis. The head 45 is shaped into a disc shape that is smaller in diameter than the center portion of the resistor portion 41 and larger in diameter than the neck portion 44, and protrudes from the neck portion 44 along the axis. neck 4
A circumferential groove 46 is defined by the outer peripheral surface of the coil spring 4, one end of the center portion of the resistor portion 41, and the head 45, and the other end of the coil spring 3 is wound around the circumferential groove 46. .

The head 45 prevents the other parts of the coil spring 3 from separating from the neck 44, and the surfaces of the other end of the resistor 41, that is, the neck 44 and the head 45, are coated with conductive paint such as silver paint. is covered.

An insulating coating layer made of epoxy resin is applied to the outer circumferential surface of the central portion of the resistor 41 to prevent mechanical discharge, and the electrical resistance value between the cap 42 and the connecting portion 43 of the spring connecting member 4 is 0. It is designed for 5-10k ohms.

When using this direct plug type ignition coil, the head electrode (not shown) of this ignition plug (not shown) is fitted into the insulating cylinder 24, and then the ignition plug is connected to the cylinder head (not shown).
(not shown).

Thereafter, the housing 1 is attached to an intake manifold (not shown) disposed above the cylinders of an engine (not shown).
As a result, the head electrode of the spark plug comes into contact with the end of the cap 42 of the spring connecting member 4 and presses the spring connecting member 4. By this pressing, the spring connecting member 4 smoothly compresses the coil spring 3 in the axial direction, and the spark plug is electrically well connected to the high voltage terminal 5 by the coil spring 3 and the spring connecting member 4.

FIG. 3 shows the measurement results of the sonic electric field strength of this direct plug type ignition coil and the conventional plug directly connected type ignition coil. Note that the resistance value of the resistor in the experiment shown in FIG. 3 was 5 kΩ. As can be seen from FIG. 3, the ignition coil of this embodiment exhibits a cone noise prevention effect equal to or greater than that of the conventional ignition coil shown in FIG. 6 in pt<B.

Modifications of the spring connecting member 4 are shown in FIGS. 4 and 5.

In the spring connecting member 4a shown in FIG. 4, one end of the resistor 49 is coated with conductive paint 7 such as silver paint to ensure electrical connection with the plug, instead of the metal cap 42 shown in FIG. It is something.

This reduces the number of component parts and reduces manufacturing costs.

The spring connecting member 4b shown in FIG. 5 employs a wire-wound resistor 8 as the resistor part of the spring connecting member 4, and the other end is covered with an aluminum cap 6 having a circumferential groove 61 for locking the spring. are doing.

In this way, it can be manufactured at low cost.

[Effects of the Invention] As explained above, in the plug-directly connected ignition coil of the present invention, the Da section is a connecting section connected to the other end of the coil spring, and the other end is connected to the head electrode of the ignition plug. It has a contact surface that can make surface contact with the spark plug, and is also equipped with a spring connecting member that has an electric resistance value effective in reducing high-frequency noise of the spark plug, so that contact between the head electrode of the spark plug and the spring connecting member is prevented. The contact between the surface portion and the connecting portion of the spring connecting member and the other end of the coil spring is good and stable, and linear compression of the coil spring is promoted.

Furthermore, the rJ'l of the conical sound wave of the spark plug is reduced by appropriate electric resistance between the connecting part and the contact surface part of the spring connecting member.
．． Along with reducing the sword, it becomes possible to replace it in case of failure or change of resistance value.

[Brief explanation of drawings]

FIG. 1 is a partially cross-sectional side view showing an embodiment of the plug-type ignition coil of the present invention, FIG. 2 is a side view of the spring connecting member 4, FIG. 3 is a characteristic diagram showing noise measurement results, and FIG. 5 and 5 are side views showing modified versions of the spunong connecting member 4, and FIG. 6 is a partially sectional side view showing a conventional plug-type ignition coil. 1...Housing 2...High pressure tower 3...Coil spring 4...Spring connection member

Claims (1)

[Claims] (1) An insulating housing that accommodates a primary coil, a secondary coil, and a core therein, and an insulating cylinder with an opening at the end that stands up from the housing surface and surrounds a high-voltage terminal connected to the output end of the secondary coil. A high-voltage tower made of aluminum, a coil spring inserted into the high-voltage tower and having one end in contact with the high-voltage terminal, and a connecting part inserted into the high-voltage tower and having one end connected to the other end of the coil spring. a spring, the other end of which is a contact surface portion that can make surface contact with the head electrode of the spark plug, and further has an electrical resistance value effective for reducing high frequency noise between the connecting portion and the contact surface portion. A plug direct connection type ignition coil characterized by comprising: a connecting member;