JP2006278380A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight ignition coil for internal combustion engine having a core cover for preventing cracking from the corner of a core to insulating resin in which adhesion to the insulating resin is improved. <P>SOLUTION: The ignition coil comprises at least a primary coil and a secondary coil, a center core and a side core, a core cover for covering them, a case for containing the primary coil and secondary coil and the center core and side core, and insulating resin filling the case. The core cover is arranged to cover the corner of the core so that the insulating resin is not cracked by the corner of the core, and resin molded under foamed state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition coil for an internal combustion engine that has an iron core cover that prevents cracks from the corners of an iron core to an insulating resin, has good adhesion to the insulating resin, and is lightweight.

  FIG. 3 is a perspective view for explaining a primary coil and a secondary coil, an iron core, and an iron core cover in a conventional example. In FIG. 3, an iron core-coil assembly 10 includes a center iron core 14, a primary coil 11 fitted and supported on the outer periphery of the center iron core 14, and a secondary coil 12 fitted and supported outside the primary coil 11. At least. The annular outer ring core 13 is composed of a C-shaped core 13a and I-shaped cores 13b that connect the open ends of the C-shaped core 13a. The outer ring core 13 may be composed of two opposing U-shaped cores having a semicircular arc shape.

  The iron core composed of the outer ring core 13 and the center iron core 14 is formed by connecting the E-shaped iron core whose center arm is the center iron 14 among the three arms and the three arms of the E-shaped iron core at right angles. And an I-shaped iron core 13b. The iron core includes an annular outer ring core 13 and a center iron core 14 that passes through the outer ring core 13 and supports the primary coil 11 and the secondary coil 12 that are fitted concentrically inside and outside. That's fine.

  The iron core cover 30 is substantially the same shape as the iron core-coil assembly 10, and is provided with a thick annular portion 31 on the upper portion, and is continuously provided so as to hang from the inner periphery of the annular portion 31, and straddles each end of the center iron core 14. The opposed arc-like hanging walls 32 and 32 'contacting the opposed inner peripheral surfaces of the outer ring core 13 are integrally formed of synthetic resin. The iron core cover 30 is placed on the outer ring iron core 13 of the iron core-coil assembly 10. At this time, the arc-like hanging walls 32 and 32 ′ that are suspended from the inner circumference of the annular portion of the iron core cover 30 come into contact with the inner circumference of the outer ring iron core 13.

  An insulating resin is filled between the iron core-coil assembly 10 and the outer ring iron core 13. Further, since the iron core cover 30 is provided on the inner surface of the outer ring iron core 13, cracks to the insulating resin by the corners of the iron core cover 30 are prevented. Furthermore, even if a crack occurs due to aging of the insulating resin, the iron core cover 30 can maintain insulation between the iron core-coil assembly 10 and the outer ring iron core 13.

The iron core cover 30 is described in detail in Japanese Patent Application Laid-Open No. 2001-196248. When the iron core cover 30 is formed of polybutylene terephthalate, the iron core cover 30 has a function of preventing cracks from the corners of the iron core to the insulating resin.
JP 2001-196248 A

  The conventional iron core cover is made of, for example, a molding resin such as polybutylene terephthalate. The iron core cover has sufficient strength to prevent cracks from the corners of the iron core to the insulating resin. However, since the iron core cover also serves to reduce the amount of insulating resin in the case, the thickness is partially increased. For this reason, the volume of the iron core cover is increased, and the accompanying increase in weight makes it difficult to reduce the weight of the ignition coil for the internal combustion engine.

  In order to solve the above-described problems, an object of the present invention is to provide an ignition coil for an internal combustion engine that can reduce the weight of the iron core cover and prevent cracks from the corners of the iron core to the insulating resin. .

(First invention)
An ignition coil for an internal combustion engine according to a first aspect of the present invention includes a primary coil and a secondary coil around which an electric wire is wound, a center core and a side core that magnetically couple the primary coil and the secondary coil, and corners of the core An iron core cover molded in a foamed state, a primary coil and a secondary coil, a center iron core and side iron cores, a case containing the iron core cover, and an insulating resin filling the case And at least.

(Second invention)
The ignition coil for an internal combustion engine of the second invention is characterized in that the iron core cover of the first invention is made of polybutylene terephthalate.

(Third invention)
The ignition coil for an internal combustion engine of the third invention is characterized in that irregularities are formed on the surface of the iron core cover of the first invention and the second invention.

  According to the present invention, since the core cover that is resin-molded in the foamed state is disposed so as to cover the corners of the core, it is possible to prevent the insulating resin from being cracked.

  According to the present invention, even if the core cover is molded in a foamed state, the strength can be maintained, the amount of resin used can be reduced, and the weight can be reduced. In addition, since the resin is in a foamed state, the iron core cover can improve the adhesion with the insulating resin and can be a highly reliable ignition coil for an internal combustion engine.

  According to the present invention, an iron core cover is produced by molding a polybutylene terephthalate or the like in a foamed state to produce an iron core cover that is excellent in mechanical characteristics, heat resistance, electrical characteristics, dimensional stability, and lightweight. I was able to.

  According to the present invention, it is possible to improve the adhesiveness with the insulating resin filled in the case by forming irregularities on the inner surface of the iron core cover.

(First invention)
An ignition coil for an internal combustion engine according to a first aspect of the present invention includes a primary coil and a secondary coil, a center iron core and a side iron core, an iron core cover covering these, a primary coil and a secondary coil, a center iron core and a side iron core, and an iron core cover. It is comprised at least from the case to accommodate and the insulating resin with which the said case was filled. The iron core cover is disposed so as to cover the corners of the iron core, prevents cracking due to the corners of the iron core in the insulating resin, and is molded in a foamed state.

  The core cover formed by resin molding in the foamed state can maintain strength as a cover, reduce the amount of resin used, and reduce the weight. In addition, since the resin is in a foamed state, the iron core cover can improve the adhesion with the insulating resin and can be a highly reliable ignition coil for an internal combustion engine.

(Second invention)
In the ignition coil for an internal combustion engine of the second invention, the iron core cover of the first invention is formed of polybutylene terephthalate (PBT) or the like. The polybutylene terephthalate, which has good mechanical properties, heat resistance, electrical characteristics, and dimensional stability, is used as an iron core cover, and in a foamed state, is not only lightweight by providing irregularities on the inner surface, The adhesion with the insulating resin could be improved at the same time.

(Third invention)
The ignition coil for an internal combustion engine of the third invention has the iron core cover of the first and second inventions, for example, irregularities such as sponges are formed on the inner surface. The irregularities positively formed on the surface of the iron core cover can improve the adhesion with the insulating resin filled in the case.

  FIG. 1 is a perspective view for explaining an iron core cover according to the present invention. 2 is an AA cross-sectional view of the iron core cover according to the present invention shown in FIG. 1 and 2, the iron core cover 111 is substantially the same shape as an iron core-coil assembly (not shown), and a thick annular portion 131 is provided on the upper portion, and is continuously provided so as to hang from the inner periphery of the annular portion 131. A synthetic resin is integrally formed with opposed arc-shaped drooping walls 132 and 132 ′ that straddle each end of the center iron core, not shown, and that are in contact with the opposed inner peripheral surfaces of the outer ring iron core. It is molded with. The iron core cover 111 is placed on the outer ring iron core of the iron core-coil assembly. At this time, the arc-like hanging walls 132 and 132 ′ that face down from the inner periphery of the annular portion 131 of the core cover 111 are in contact with the inner periphery of the outer ring core.

  An insulating resin is filled between the iron core-coil assembly and the outer ring iron core. Moreover, since the iron core cover 111 is provided on the inner surface of the outer ring iron core, cracks in the insulating resin are prevented. Furthermore, even if a crack occurs due to aging of the insulating resin, the iron core cover 111 can maintain insulation between the iron core-coil assembly and the outer ring iron core. The iron core cover 111 is manufactured by finely dispersing a gas such as air in a molten polybutylene terephthalate (PBT) or the like. In the polybutylene terephthalate or the like, the gas such as the compressed air expands when the resin immediately after molding is not completely cured, and in particular, the surface of the inner surface of the resin molding is uneven. The unevenness of the resin molded body can improve the adhesion with the insulating resin molded body and ensure high reliability.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example. The present invention can be modified in various ways without departing from the scope of the claims. The material of the iron core cover of the ignition coil for an internal combustion engine described in the embodiment of the present invention is known or well-known as long as mechanical characteristics, heat resistance, electrical characteristics, dimensional stability, and weight reduction are achieved. Can be used. In addition, for the foam molding of the iron core cover of the ignition coil for the internal combustion engine described in the embodiment of the present invention, a known or well-known technique can be used. Furthermore, a well-known or well-known thing can be used for the molding resin material which can be used for this invention.

It is a perspective view for demonstrating the iron core cover in this invention. Example 1 It is AA sectional drawing of the iron core cover in this invention shown in FIG. It is a perspective view for demonstrating the primary coil and secondary coil, iron core, and iron core cover in a prior art example.

Explanation of symbols

111 ... Iron core cover 131 ... Annular part 132, 132 '... Arc hanging wall

Claims (3)

A primary coil and a secondary coil around which an electric wire is wound;
A center core and a side core for magnetically coupling the primary coil and the secondary coil;
An iron core cover that is disposed so as to cover the corners of the iron core and is molded in a foamed state;
A case for accommodating the primary coil and the secondary coil, the center iron core and the side iron core, and the iron core cover;
An insulating resin filling the case;
An ignition coil for an internal combustion engine characterized by comprising:   The ignition coil for an internal combustion engine according to claim 1, wherein the iron core cover is made of polybutylene terephthalate.   The ignition coil for an internal combustion engine according to claim 1 or 2, wherein the surface of the iron core cover is formed with irregularities.

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