JP2004363357A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil for internal combustion engine which is enhanced in the assembling workability and productivity and has stable performance, in order to solve the problem that an ignition coil assembling a permanent magnet piece for bias into a part of an iron core is deteriorated in performance due to displacement of the permanent magnet piece at the time of assembling. <P>SOLUTION: The ignition coil for internal combustion engine is provided with a closed magnetic path iron core which is formed by coupling a linear iron core 3' where a primary coil 1 and a secondary coil 2 are engaged at the external side thereof and an external annular iron core 3 surrounding the primary and secondary cores 1, 2 via the permanent magnet piece 8. The cross-sectional area at the end face of one end of the linear iron core 3' in contact with the permanent magnet piece 8 is more smoothly enlarged than the cross-sectional area of the other portion, and also, the edge of the surface of the permanent magnet piece 8 in contact with the end face of one end is located at the internal side of the circumference of the end face of one end. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ignition coil for an internal combustion engine used for supplying a high voltage to an ignition plug of an internal combustion engine such as an automobile engine to generate spark discharge.
[0002]
[Prior art]
Generally, as shown in FIG. 6, a mold-type ignition coil for an internal combustion engine includes a secondary coil 2, a primary coil 1 penetrating the inside of the secondary coil 2, and a straight line penetrating the inside of the primary coil 1. A closed magnetic circuit core including an iron core part 3 ′ and an outer ring core part 3 surrounding the primary and secondary coils 1 and 2 is housed inside the insulating case 4, and a part is housed inside the insulating case 4. A high-pressure cylinder 5 accommodating a high-voltage terminal 6 to be penetrated is provided in the insulating case 4, and an insulating resin 7 is injected into the insulating case 4 and solidified. In order to increase the output of the ignition coil, a magnetic bias is applied to the closed magnetic path core between one end surface of the linear core portion 3 ′ of the closed magnetic circuit core and the inner surface of the outer ring core portion 3 facing this one end surface. (See, for example, Patent Document 1).
[0003]
The permanent magnet piece 8 used in this case is desirably in contact with both the surface of one end of the linear core portion 3 ′ and the inner surface of the outer ring core portion 3 with as large an area as possible. Therefore, the surface of the permanent magnet piece 8 was almost the same shape as the surface of the one end of the linear iron core 3 ', and was the same square.
[0004]
[Patent Document 1]
JP-A-8-45755 (paragraph [0014], paragraph [0015], FIGS. 1 and 3)
[0005]
[Problems to be solved by the invention]
When the ignition coil for an internal combustion engine having such a conventional structure is assembled into a closed magnetic circuit core by combining the straight core portion 3 ′ and the outer ring core portion 3, the permanent magnet piece 8 is attached to the outer ring core portion 3. When it comes into contact with the inner side surface, it is likely to be displaced, and if it protrudes from one end of the linear core portion 3 ′, it interferes with the primary bobbin accommodating the primary coil 1 and is damaged, or the performance is impaired even if it is not damaged. In addition, there is a problem that it takes time and effort to reassemble the permanent magnet piece 8 at a correct position, and that productivity is reduced.
[0006]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention has been developed to solve the above problems, and has a straight core portion having a primary coil and a secondary coil fitted outside, and an outer ring surrounding the primary and secondary coils. In an ignition coil for an internal combustion engine having a closed magnetic circuit core formed by coupling a core portion through a permanent magnet piece, a cross-sectional area of an end surface of one end of the linear core portion in contact with the permanent magnet piece is different from that of another portion. It is characterized in that it is enlarged so as to be smoother than the cross-sectional area, and that the peripheral edge of the surface of the permanent magnet piece that is in contact with the end face of the one end is located inside the peripheral edge of the end face of the one end. .
Further, by providing a space sufficient to simultaneously accommodate one end of the linear core and the permanent magnet piece at an end of the coil bobbin to which the linear core is fitted, the outer ring core side end is provided. The assembly of the magnet pieces can be performed extremely easily and with high accuracy, and the occurrence of a shift in the mounting position can be prevented.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an assembled state of essential parts of an embodiment of an ignition coil for an internal combustion engine according to the present invention. FIG. 2 shows a straight core portion 3 ', a C-shaped core portion 3A and the C-shaped core portion. FIG. 3 is a top view of a closed magnetic circuit core configured by combining an outer ring core 3 composed of an I-shaped connection core 3 ″ connecting the open ends of the section 3A. FIG. 3 'is a horizontal sectional view of 3', wherein the straight core portion 3 'is formed by laminating a large number of magnetically permeable steel plates formed in a T-shape with the width of one end being smoothly expanded; This shows that the cross-sectional area of the straight core portion 3 'has a shape that smoothly increases near the end face of one end.
[0008]
On the other hand, the coil bobbin 9 fitted to the outside of the straight core portion 3 'has an inner surface shape adapted to the outer surface of the straight core portion 3', and the enlarged end thereof has a straight core portion 3 '. A space 9a for accommodating the permanent magnet piece 8 provided so as to be in contact with the end face of one end of the linear iron core 3 'together with one end of the linear core 3' is formed. The upper end and the lower end of the enlarged end of the coil bobbin 9 cover the upper surface and the lower surface of the outer ring core 3 facing the one end of the linear core 3 'via the permanent magnet piece 8, respectively. The pressing plate 9b and the pressing plate 9c which can be provided are provided in a protruding manner.
[0009]
As shown in FIGS. 4 and 5, a permanent magnet piece 8 is accommodated in the space 9a, and the width and height of the permanent magnet piece 8 are determined by the peripheral wall of the space 9a. It is sufficient if it is within the range of dimensions that can be inserted without insertion. Therefore, the peripheral edge of the surface of the permanent magnet piece 8 which is in contact with the enlarged end surface of the linear core portion 3 'is inside the peripheral edge of the one end portion of the linear core portion 3'. The thickness of the permanent magnet piece 8 need not be less than the depth of the space 9a as shown in FIG. 5, and the thickness between the opposing surfaces of the straight core portion 3 'and the outer ring core portion 3 is not limited. It is necessary that it be formed in a dimension that can be securely adhered and held.
[0010]
In the ignition coil for an internal combustion engine according to the present invention, as described above, the end face of the linear core portion 3 ′ having a T-shaped cross-section at one end is smoothly enlarged and the outer ring core portion 3 is opposed to each other. A permanent magnet piece 8 for forming a magnetic bias is sandwiched between the surfaces, and the peripheral edge of the permanent magnet piece 8 is located inside the peripheral edge of the wide end face of the linear core portion 3 '. A portion facing the surface of the outer ring core portion 3 in a non-contact state with the permanent magnet piece 8 is left at the peripheral edge of the wide end face of the portion 3 ′.
[0011]
Therefore, when the linear core portion 3 'and the permanent magnet piece 8 having such a configuration are used, the permanent magnet piece 8 attracted to the end face of the linear core portion 3' naturally has a correct posture in the space 9a. Therefore, assembling accuracy can be improved and the efficiency of the assembling work can be improved. Further, since a gap is left between the end face of the linear core portion 3 ′ and the outer ring core portion 3 outside the periphery of the permanent magnet piece 8, the gap is formed when the assembled ignition coil is operated. A magnetic circuit bypassing the permanent magnet piece 8 is generated, and the fringing magnetic flux can be increased.
[0012]
【The invention's effect】
Advantageous Effects of Invention The ignition coil for an internal combustion engine according to the present invention has an effect that a product which is easy to assemble, has high accuracy and is free from defects can be economically provided. In addition, since one end of the straight core portion is smoothly enlarged, and a gap serving as a detour magnetic path is formed outside the periphery of the permanent magnet piece for applying a magnetic bias, the operation of the ignition coil is performed. In some cases, the fringing magnetic flux can be increased, and the demagnetization characteristics of the permanent magnet pieces can be stabilized, so that the reliability of quality can be further improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing main components constituting an ignition coil for an internal combustion engine of the present invention and an assembly structure thereof.
FIG. 2 is a top view showing an assembled state of FIG. 1;
FIG. 3 is a sectional view taken along line III-III in FIG. 2;
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;
FIG. 5 is a sectional view taken along the line VV of FIG. 4;
FIG. 6 is a sectional view of a general example of a conventional ignition coil.
[Explanation of symbols]
1 Primary coil 2 Secondary coil 3 Outer ring core (closed magnetic circuit core)
3A C type core (outer ring core)
3 'straight core (closed magnetic circuit core)
3 "I-shaped core (outer ring core)
Reference Signs List 4 Insulation case 5 High-pressure cylinder 6 High-voltage terminal 7 Insulating resin 8 Permanent magnet piece 9 Coil bobbin 9a Space 9b Press plate 9c Press plate

Claims (2)

A closed magnetic circuit core is provided in which a linear core portion on which a primary coil and a secondary coil are fitted outside and an outer ring core portion surrounding the primary and secondary coils are connected via permanent magnet pieces. In the ignition coil for internal combustion engine
The cross-sectional area of the end face of one end of the linear core portion that is in contact with the permanent magnet piece is smoothly expanded from the cross-sectional area of the other part, and the peripheral edge of the surface of the permanent magnet piece that is in contact with the end face of the one end is It is configured to be inside the peripheral edge of the end face of the one end,
An ignition coil for an internal combustion engine. The ignition coil for an internal combustion engine according to claim 1,
At the end of the coil bobbin to which the linear core is fitted, an outer ring core side end is provided with a space sufficient to simultaneously accommodate one end of the linear core and the permanent magnet piece.
An ignition coil for an internal combustion engine.

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