JP2003086439A - Ignition coil device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil device for a internal combustion engine, capable of relaxing thermal stress due to the difference in thermal expansion between resin used widely for component and iron cores. SOLUTION: The ignition coil device for the internal combustion engine comprises at least a primary coil 3 and a secondary coil 4, and a center iron core 1 running through the inside periphery of the primary coil 3 and a side iron core 2, running on the outside periphery of the secondary coil 4 for magnetically coupling the two coils, with the primary coil 3, the secondary coil 4, the center iron core 1, and the side iron core 2 embedded in an insulation material to insulate them from high voltage, and a high voltage generated in the secondary coil 4 transmitted to an ignition plug via a spring 9 in a protector composed of three parts, a rubber 10, an adaptor 11, and a boot 12. The arrangement of a stress relaxing material 22 in a periphery section composing an iron core cover 21 covering the side iron core 2 can relax the thermal stress generated by the difference of the thermal expansion with the iron core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil device for an internal combustion engine for supplying a high voltage to an ignition plug of an internal combustion engine of an automobile or the like to perform spark discharge, and more particularly to mitigating thermal stress of the ignition coil device. .

[0002]

2. Description of the Related Art Generally, an ignition coil device for an internal combustion engine is
In many cases, it is mounted in the engine room of an automobile or the like, and dimensional restrictions required by other engine parts and the like are severe, and miniaturization is progressing. In addition, various means for preventing cracks caused by thermal stress generated in the iron core have been proposed.

For example, as shown in FIG. 4, in an ignition coil device for an internal combustion engine, a center iron core 1 and a side iron core 2 forming a closed magnetic circuit are wound around the outer periphery of the center iron core 1 and energized to form a center iron core l. A primary coil 3 for exciting the side core 2, a secondary coil 4 wound around the outer periphery of the primary coil 3,
An insulating material 5 that insulates them is housed in a case 6.

A relaxation material 7 is arranged on the step portion 6a formed on the case 6 in order to reduce the thermal stress of the side iron core 2. Further, a high voltage terminal 8 for supplying the high voltage induced by the secondary coil 4 to the spark plug, and the high voltage terminal 8
It is composed of a spring 9 that is pressed into contact with, a rubber 10 that accommodates the spring 9, an adapter 11, a boot 12, and the like. The boot 12 seals an ignition plug.

[0005]

However, in the conventional ignition coil device for an internal combustion engine configured as described above, the constituent materials of the internal parts are changed due to a change in ambient temperature and self-heating caused by the operation of the ignition coil. Thermal stress is generated due to the difference in the linear expansion coefficient. Most of the components are made of synthetic resin, whereas the linear expansion coefficient of the iron core is extremely small. Therefore, the maximum thermal stress is generated at the outer peripheral corners of the iron core. This stress causes a crack in the insulating resin in contact with the iron core, and then the crack extends and is exposed on the surface of the ignition coil.

Further, in the prior art, only the bottom portion is relaxed, and cracks occur at the unrelaxed portion.
There was a possibility that these cracks would extend and reach the surface of the ignition coil. Further, since the stress relaxation structure needs to be filled with silicone rubber and cured, it takes a lot of man-hours and is an expensive structure.

The present invention has been proposed in view of the above situation, and an object thereof is to dispose a stress relaxation material on the side surface of the iron core cover to completely alleviate the thermal stress generated by the iron core. Moreover, it aims at providing a stress relaxation structure at low cost.

[0008]

In order to achieve the above object, the invention according to claim 1 provides at least a primary coil and a secondary coil, and the primary coil for magnetically coupling the two coils. Has a center iron core passing through the inner circumference of the core and a side iron core passing through the outer circumference of the secondary coil, and is embedded in an insulating material for insulating the primary coil, the secondary coil, the center core and the side core from high voltage. In the ignition coil device for an internal combustion engine, which transmits the high voltage generated in the secondary coil to the ignition plug through the high voltage terminal, the stress relaxation material is arranged on the outer peripheral portion of the iron core cover that covers the side iron core. It is characterized by

Further, in the invention described in claim 2, in addition to the structure of the invention described in claim 1, the iron core cover is made of synthetic resin and has a U-shaped cross section. It is characterized by that.

Further, in the invention as set forth in claim 3, the stress relieving material arranged on the outer peripheral portion of the iron core cover is 0.3 from the upper surface and the lower surface of the side iron core.
It is characterized by being extended by mm or more.

In the invention according to claim 4, the stress relaxation material is a material having an elastic modulus of 100 MPa or less.

Further, in the invention according to claim 5, the thickness of the stress relaxation material is at least 0.2 mm or more.

Further, in the invention according to claim 6, the stress relieving material forming the iron core cover is bonded to the outer periphery of the side iron core.

Further, in the invention according to claim 7, the stress relaxation material is at least 1 on the outer circumference of the side core.
It is characterized in that more than one layer is provided.

In the invention according to claim 8, the iron core cover for covering the side iron core is made of synthetic resin PBT.
(Poly Butylene Terephthalate) mixed with an elastic material such as rubber.

Further, in the invention of claim 9, the iron core cover for covering the side iron core is a PPE which can be easily joined with an insulating material which insulates the primary coil and the secondary coil.
(Polyphenylene ether) is used.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings showing one embodiment. FIG. 1 is a vertical sectional view of an ignition coil device for an internal combustion engine according to the present invention, and FIG. 2 is an enlarged sectional view of a main part of the ignition coil device for an internal combustion engine. The same parts as those of the conventional device are designated by the same reference numerals and the description thereof will be omitted.

Here, the ignition coil device 20 for an internal combustion engine
Is at least a primary coil 3 and a secondary coil 4, a center iron core 1 passing through the inner circumference of the primary coil 3 that magnetically couples the two coils, and a side iron core 2 passing through the outer circumference of the secondary coil 4. The primary coil 3, the secondary coil 4, the center iron core 1 and the side iron core 2 are embedded in an insulating material 5 for insulating them from a high voltage, and the high voltage generated in the secondary coil 4 is applied from a high voltage terminal 8. The side iron core 2 is for transmitting to a spark plug through a spring 9 in a protector composed of three parts of a rubber 10, an adapter 11 and a boot 12.
An iron core cover 21 is provided to cover the.

The iron core cover 21 is made of synthetic resin and has a U-shaped cross section. Further, the stress relaxation material 22 is arranged on the outer peripheral portion of the U-shaped cross section. Furthermore, as the stress relaxation material 22, a material having an elastic modulus of 100 MPa or less can be preferably used. Also, the stress relaxation material 2
The thickness T of 2 is preferably at least 0.2 mm or more.

Further, as shown in FIG.
Is preferably extended from the upper surface 2a and the lower surface 2b of the side iron core 2 with a dimension of H = 0.3 mm or more. Furthermore, the stress relaxation material 22 that constitutes the side wall of the iron core cover 21 may be adhered to the outer periphery of the side iron core 2. Also,
The iron core cover 21 that covers the side iron core 2 is made of synthetic resin PB.
An elastic material such as rubber is mixed with T (polybutylene terephthalate).

Further, as shown in FIG. 3, as a second embodiment of the present invention, the stress relaxation material 22 is composed of at least two layers of a first layer 22a and a second layer 22b on the outer periphery of the side core 2. ing. In this way, in the case of the multilayer structure, the stress due to the thermal expansion of the side iron core 2 can be relaxed. The stress relaxation material 22 may be composed of two or more layers.

Further, an iron core cover 22 for covering the side iron core 2
May use PPE (polyphenylene ether) that can be easily bonded to the insulating material that insulates the primary coil 3 and the secondary coil 4.

In the ignition coil device for an internal combustion engine of the present invention configured as described above, the thermal stress generated in the outer peripheral portion of the side iron core 2 can be relaxed by the stress relaxing material 22.
The reliability of the ignition coil can be greatly improved. In addition, the step of heating for hardening or the like can be omitted in the manufacturing process, and the manufacturing cost can be reduced with the reduction of the number of steps.

[0024]

Since the present invention has the above-mentioned structure,
The effects described below can be achieved.

In the invention described in claim 1, at least 1
A secondary coil, a secondary coil, a center iron core passing through the inner circumference of the primary coil that magnetically couples the two coils, and a side iron core passing through the outer circumference of the secondary coil,
The primary coil, the secondary coil, the center iron core and the side iron core are embedded in an insulating material to insulate them from high voltage, and the high voltage generated in the secondary coil is composed of three parts: a high voltage terminal, a rubber, an adapter and a boot. In the ignition coil device for an internal combustion engine, which transmits to a spark plug through a spring in a protector, a stress relaxation material is arranged on an outer peripheral portion that constitutes an iron core cover that covers the side iron core, so that thermal expansion with the iron core is performed. The stress generated by the difference can be relaxed to prevent the occurrence of cracks.

Further, in the invention described in claim 2, in addition to the structure of the invention described in claim 1, the iron core cover is made of synthetic resin and has a U-shaped cross section. Therefore, the stress generated by the difference in thermal expansion from the side core can be relaxed by wrapping the side core.

Further, in the invention described in claim 3, in addition to the structure of the invention described in claim 1, the stress relieving material arranged on the outer peripheral portion of the iron core cover is the same as that of the side iron core. Since it is extended by 0.3 mm or more from each of the upper surface and the lower surface, it is possible to prevent the insulating case and the like from being cracked even if stress is generated due to a difference in thermal expansion from the side iron core.

Further, in the invention described in claim 4, in addition to the structure of the invention described in claim 1, since the stress relaxation material is a material having an elastic modulus of 100 MPa or less, The thermal stress due to the difference in thermal expansion can be relaxed.

In addition, in the invention described in claim 5, in addition to the structure of the invention described in claim 1, since the thickness of the stress relaxation material is at least 0.2 mm or more, the side core and The thermal stress due to the difference in thermal expansion can be relaxed.

In addition, in the invention described in claim 6, in addition to the structure of the invention described in claim 1, the stress relaxation material constituting the iron core cover is adhered to the outer periphery of the side iron core. The bond between the side core and the stress relaxation material can be made stronger.

Further, in the invention described in claim 7, in addition to the structure of the invention described in claim 1, at least one layer of the stress relaxation material is provided on the outer periphery of the side iron core. The stress generated due to the difference in thermal expansion from the iron core can be sufficiently relaxed.

Further, in the invention described in claim 8, in addition to the structure of the invention described in claim 1, the iron core cover for covering the side iron core is made by mixing an elastic material such as rubber into PBT of synthetic resin. Since it is configured so that it can be sufficiently deformed to cope with the extension due to the difference in thermal expansion from the iron core.

According to the invention of claim 9, in addition to the structure of the invention of claim 1 described above, an iron core cover for covering the side iron core insulates the primary coil and the secondary coil. Since PPE that can be easily bonded to the insulating material is used, it can be bonded to the insulating material.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an ignition coil device for an internal combustion engine according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the ignition coil device for the internal combustion engine.

FIG. 3 is an enlarged vertical sectional view of an essential part showing another embodiment of the present invention.

FIG. 4 is a vertical sectional view showing an example of a conventional ignition coil device for an internal combustion engine.

[Explanation of symbols]

1 Center iron core 2 side iron core 3 primary coil 4 secondary coil 5 insulation 6 cases 7 relaxation materials 8 high voltage terminals 9 springs 10 rubber 11 Adapter 12 boots 20 Ignition coil device for internal combustion engine 21 iron core cover 22 Stress relaxation material 22a First layer 22b Second layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mitsuru Tokioka             Hyogo Prefecture Kobe City Nada-ku, Tsudori 2-chome 1-226 Saka             Shin Electric Co., Ltd. (72) Inventor Masaaki Hori             Hyogo Prefecture Kobe City Nada-ku, Tsudori 2-chome 1-226 Saka             Shin Electric Co., Ltd.

Claims (9)

[Claims] 1. At least a primary coil and a secondary coil, a center iron core passing through the inner circumference of the primary coil that magnetically couples the two coils, and a side iron core passing through the outer circumference of the secondary coil. The primary coil, the secondary coil, the center iron core, and the side iron core are embedded in an insulating material for insulating from high voltage, and the high voltage generated in the secondary coil is transmitted to the ignition plug via the high voltage terminal. An ignition coil device for an internal combustion engine, wherein a stress relaxation material is arranged on an outer peripheral portion of an iron core cover that covers the side iron core. 2. The ignition coil device for an internal combustion engine according to claim 1, wherein the iron core cover is made of synthetic resin and has a U-shaped cross section. 3. The stress relaxation material disposed on the outer peripheral portion of the iron core cover is extended by 0.3 mm or more from the upper surface and the lower surface of the side iron core, respectively. An ignition coil device for an internal combustion engine as described. 4. The stress relaxation material has an elastic modulus of 100 MP.
The ignition coil device for an internal combustion engine according to claim 1, wherein the ignition coil device is made of a material having a or less. 5. The ignition coil device for an internal combustion engine according to claim 1, wherein the stress relaxation material has a thickness of at least 0.2 mm or more. 6. The ignition coil device for an internal combustion engine according to claim 1, wherein the stress relaxation material forming the iron core cover is adhered to an outer periphery of the side iron core. 7. The ignition coil device for an internal combustion engine according to claim 1, wherein at least one layer of the stress relaxation material is provided on the outer periphery of the side iron core. 8. The iron core cover for covering the side iron core is formed by mixing an elastic material such as rubber into PBT (polybutylene terephthalate) made of synthetic resin. An ignition coil device for an internal combustion engine as described. 9. An iron core cover for covering the side iron core is 1
The ignition coil device for an internal combustion engine according to any one of claims 1 to 7, wherein PPE (polyphenylene ether) that can be easily joined to an insulating material that insulates the secondary coil and the secondary coil is used. .