JP2006269843A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and highly accurate ignition coil for an internal combustion engine in which weight of an iron core cover is reduced, and which has almost no distortion and deformation and is capable of preventing the occurrence of cracks from the corners of the iron core to an insulating resin. <P>SOLUTION: The iron core cover is divided into two parts at the thin-walled part of the longitudinal section. One side of the two-divided iron core cover is opened. The two-divided iron core cover is provided with coupling parts that are mutually fitted when assembled on the side opposite to the open side. Dies for the iron cover are small since the iron cover is divided into a plurality of parts. Therefore, it is not only possible to achieve reduction of manufacturing costs and improvement of manufacturing accuracy, but also to eliminate the distortion due to thermal stress over a long period of time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition coil for an internal combustion engine having an iron core cover that prevents cracks from the corners of the iron core to insulating resin.

  2A to 2C are perspective views for explaining an iron core-coil assembly, an iron core cover, and an outer ring iron core in a conventional example. In FIG. 2A, an iron core-coil assembly 21 includes a primary coil (not shown) wound around a primary bobbin 211, a secondary coil 213 wound around a secondary bobbin 212, and the primary bobbin 211. It is comprised at least from the center iron core 24 inserted in the inside, and the terminal connection part 215 of a coil and the electrically conductive piece 216. FIG.

  As shown in FIG. 2 (b), the iron core cover 22 hangs downward from the annular portion 221 and the annular portion 221 and also has an arc-shaped hanging portion 222 made of an arc-shaped thin portion covering the inner side of the outer ring core described later. 223, a thin-walled portion 224 serving as a portion for housing the terminal connecting portion 215 in the coil-iron core assembly 21, a connecting portion 225 for connecting the annular portion 221, and the center iron core 24 and the outer ring iron core 23. It is comprised from the opening part 226,226 'for making it contact | abut, and the conductive piece fixing | fixed part 227 which fixes the said conductive piece 216. As shown in FIG.

  The outer ring core 23 includes a U-shaped core 231 and an I-type core 232 as shown in FIG. The iron core cover 22 is placed on the iron core-coil assembly 21. At this time, the arc-shaped hanging portions 222 and 223 that are opposed to the inner periphery of the annular portion 221 of the iron core cover 22 are in contact with the inner periphery of the outer ring core 23.

  An insulating resin (not shown) is filled between the iron core-coil assembly 21 and the outer ring iron core 23. Further, since the iron core cover 22 is provided on the inner surface of the outer ring iron core 23, cracks in the insulating resin due to corner portions of the iron core cover 22 are prevented. Furthermore, even if a crack occurs due to aging of the insulating resin, the iron core cover 22 can maintain insulation between the iron core-coil assembly 21 and the outer ring iron core 23.

The iron core cover 22 is described in detail in, for example, Japanese Patent No. 3403315, and has a function of better preventing cracks from the corners of the iron core to the insulating resin when molded by polybutylene terephthalate or the like.
Japanese Patent No. 3304315

  The conventional iron core cover 22 is made of, for example, a molding resin such as polybutylene terephthalate. The iron core cover 22 has sufficient strength to prevent cracks from the corners of the iron core to the insulating resin. However, the iron core cover 22 has a thin section and a thick section for reducing the amount of insulating resin in the case or for connecting the coil terminal and the conductive piece. Occurs. The iron core cover 22 composed of portions having different thicknesses varies in distortion and deformation depending on the portion due to thermal stress due to secular change after molding. The iron core cover 22 has a disadvantage that it is easily damaged or damaged by a slight impact due to distortion or deformation.

  Further, the iron core cover 22 eliminates the thin portion and the thick portion and has a uniform thickness, so that the problem of contact between the conductive piece and the terminal connecting portion can be reduced even if distortion and deformation can be reduced. Or, as the strength increases, the weight and price increase, which is a factor that hinders productivity.

  In order to solve the above-mentioned problems, the present invention reduces the weight of an iron core cover, reduces distortion and deformation, and can prevent cracks from the corners of the iron core to the insulating resin with high accuracy and low cost. It is an object of the present invention to provide an ignition coil.

(First invention)
An ignition coil for an internal combustion engine according to a first aspect of the present invention includes: a primary coil in which an electric wire is wound around a primary bobbin; a secondary coil in which an electric wire is wound around a secondary bobbin; and the primary coil and the secondary coil are magnetized A center iron core and side iron cores to be coupled together, and an iron core cover that covers the inner periphery of the side iron core, the iron core cover being divided into a plurality of parts, and fitted together at one end when assembled A connecting portion is provided.

(Second invention)
In the ignition coil for an internal combustion engine of the second invention, the iron core cover of the first invention has a first U-shaped portion having a first thin arc-shaped hanging portion at a lower portion and a second core having a second thin arc-shaped hanging portion at a lower portion. In addition to a U-shaped portion, a first opening formed at one end of the first U-shaped portion and the second U-shaped portion, and the first U-shaped portion and the second U-shaped portion. It is characterized by comprising at least a connecting part formed at the end part and a second opening part formed at the lower part of the connecting part.

(Third invention)
In the ignition coil for an internal combustion engine of the third invention, the connecting portion in the first invention and the second invention has a structure in which the first U-shaped portion and the second U-shaped portion are integrated by the convex portion and the concave portion. It is characterized by.

  According to the present invention, since it is divided into a plurality of parts and is arranged so as to cover the corners of the iron core, it becomes a highly accurate iron core cover without distortion or deformation, so that cracks do not occur in the insulating resin even with aging. In addition to making the mold smaller, it can be produced at a lower cost because the mold becomes smaller.

  According to the present invention, even an iron core cover having a thin cross-section at a necessary portion can maintain distortion, deformation, and strength, and can use less resin and reduce the weight. Further, the iron core cover can be reduced in weight by fitting one end to each other by unevenness and the other end being an opening for the center core.

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

(First invention)
An ignition coil for an internal combustion engine according to a first aspect of the invention includes at least a primary coil in which an electric wire is wound around a primary bobbin, a secondary coil in which an electric wire is wound around a secondary bobbin, and the primary coil and the secondary coil Are formed of a center iron core and a side iron core that are magnetically coupled to each other, and an iron core cover that covers the inner periphery of the side iron core. Moreover, the said iron core cover is divided | segmented into two in the thin part of a longitudinal cross-section, for example. The iron core cover divided into two parts is open on one side, and includes a connecting portion that fits together when assembled on the opposite open side.

  Since the iron core cover is divided into a plurality of parts, the mold is small and not only can the manufacturing cost be reduced and the production accuracy can be improved, but also distortion due to thermal stress over a long period can be eliminated. . Therefore, since the iron core cover is not distorted even with aging, it is possible to maintain insulation without being damaged, and to provide 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 is provided at one end of the first U-shaped portion, the second U-shaped portion, and the first U-shaped portion and the second U-shaped portion. It is comprised at least from the formed 1st opening part and the connection part formed in the other end part of the said 1st U-shaped part and the 2nd U-shaped part. The first U-shaped part has a first thin arc-shaped hanging part at the lower part, and the second U-shaped part has a second thin arc-shaped hanging part at the lower part. The first thin arc-like hanging part and the second thin arc-like hanging part cover the inner peripheral surface of the side iron core. In addition, the first U-shaped part and the second U-shaped part include a first opening formed at one end and a connecting part formed at the other end, and are connected to each other by the connecting part. ing. The first opening and the second opening are spaces necessary when the center iron core and the side iron core come into contact with each other. The U-shaped portion referred to in the present invention includes not only an accurate U-shape but also a shape close to a C shape or the like, and is substantially close to the outer shape of the iron core.

(Third invention)
In the ignition coil for an internal combustion engine according to the third aspect of the invention, the connecting portion has a structure in which the first U-shaped portion and the second U-shaped portion are integrated by the convex portion and the concave portion. Since the iron core cover having the above-described shape is divided, it is less distorted and highly reliable even with aging.

  FIG. 1 is a perspective view for explaining an iron core cover according to the present invention. In FIG. 1, an iron core cover 11 is substantially the same as the outer shape of an iron core-coil assembly, not shown, and includes a thick first U-shaped portion 12 and a second U-shaped portion 13 at the top. It is divided into The first U-shaped portion 12 and the second U-shaped portion 13 are provided with first thin-arc-shaped hanging portions 121 and 131 at their lower portions by integral molding. The first U-shaped portion 12 and the second U-shaped portion 13 have a thin-walled portion at one end, a convex portion 141, and a concave portion 142, and are fitted and connected to each other. It has a simple structure.

  The other end portions of the first U-shaped portion 12 and the second U-shaped portion 13 remain separated, and the first opening 15 is formed. Further, a second opening 16 is formed at the lower part of one end of the first U-shaped part 12 and the second U-shaped part 13. The first opening 15 and the second opening 16 serve as a space for bringing a center iron core and a side iron core (not shown) into contact with each other. The convex portion 141 of the first U-shaped portion 12 and the concave portion 142 of the second U-shaped portion 13 are not limited to the shapes shown in the drawing as long as they can be fitted to each other.

  By dividing the first U-shaped portion 12 and the second U-shaped portion 13 by making the mold smaller, not only the machining accuracy is improved, but also an inexpensive iron core cover 11 can be obtained. The first U-shaped portion 12 and the second U-shaped portion 13 are divided so that even if there are portions having different thicknesses, distortion and deformation after molding are less due to thermal stress due to aging. Further, since the iron core cover 11 is divided, it is easy to handle, and even if an impact is applied during handling, the iron core cover 11 does not break and is not cracked into the casting resin without being assembled. There will be no occurrence and it will be highly reliable.

  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 known as long as mechanical characteristics, heat resistance, electrical characteristics, dimensional stability, and weight reduction are achieved. Things can be used. Moreover, a well-known or well-known thing can be applied for the ignition coil for internal combustion engines described in the embodiments of the present invention.

It is a perspective view for demonstrating the iron core cover in this invention. Example 1 (A) to (C) are perspective views for explaining an iron core-coil assembly, an iron core cover, and an outer ring iron core in a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Iron core cover 12 ... 1st U-shaped part 121 ... 1st thin arc shaped hanging part 13 ... 2nd U-shaped part 131 ... 2nd thin arc shaped hanging part 132, 133- ..Conducting piece fixing part 14... Connecting part 141 .. convex part 142... Concave part 15 .. first opening part 16.

Claims (3)

A primary coil in which an electric wire is wound around a primary bobbin;
A secondary coil in which an electric wire is wound around a secondary bobbin;
A center core and a side core for magnetically coupling the primary coil and the secondary coil;
An iron core cover covering the inner periphery of the side iron core;
In an ignition coil for an internal combustion engine having at least
The internal combustion engine ignition coil according to claim 1, wherein the iron core cover is divided into a plurality of parts and includes a connecting portion that fits at one end when assembled. The iron core cover is
A first U-shaped portion having a first thin arc-like hanging portion at the bottom;
A second U-shaped portion having a second thin arc-like hanging portion at the bottom;
A first opening formed at one end of the first U-shaped part and the second U-shaped part;
A connecting portion formed at the other end of the first U-shaped portion and the second U-shaped portion;
A second opening formed in a lower portion of the connecting portion;
The ignition coil for an internal combustion engine according to claim 1, further comprising:   3. The internal combustion engine according to claim 1, wherein the connecting portion has a structure in which the first U-shaped portion and the second U-shaped portion are integrated by a convex portion and a concave portion. Ignition coil.

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