JP2004014980A - Ignition coil for internal-combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil for an internal-combustion engine capable of reducing a blanked scrap material by blanking and realizing the effective use of a steel plate. <P>SOLUTION: The ignition coil for the internal-combustion engine includes a primary coil 12, a secondary coil 13, a center core 14 for penetrating the primary coil 12 and the secondary coil 13 and an annular side core 15 arranged on circumference thereof to form a closed magnetic circuit with the center core 14, and therewith forms a gap portion 16 or a magnet 17 at a butt portion with the center core 14 and the side core 15 in the magnet circuit and the cross sectional area of the butt portion is made to a T-type shape so as to enlarge the area thereof. Therein the center core 14 with the T-type shape is divided into two parts on a symmetrical axis L penetrating the coils and the center core 14 is formed by combining these parts. Consequently the effective use of the silicon steel plate can be realized by reducing the blanked scrap material by blanking. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ignition coil for an internal combustion engine for supplying a high voltage to an ignition plug of an internal combustion engine such as an automobile and performing spark discharge.
[0002]
[Prior art]
In general, an ignition coil for an internal combustion engine is formed by punching a silicon steel sheet into a predetermined shape, laminating and forming an iron core to form a closed magnetic circuit, and secondary current is generated by a change in magnetic flux generated in the iron core by a current flowing through the primary coil. A high-voltage current is generated in the coil. FIG. 6 is an explanatory view showing a conventional iron core punching shape, and FIG. 7 is a plan view showing an example of a conventional internal combustion engine ignition coil. An endless outer ring core 2 housed inside an insulating case 1, a closed magnetic path is formed with the outer ring core across the inside surrounded by the outer ring core 2, and the primary and secondary cores are fitted concentrically. It has a center iron core 3 that penetrates and supports the coil. The outer ring core 2 and the center core 3 are formed by laminating a plurality of silicon steel plates, and constitute a magnetic circuit forming a closed magnetic circuit as a whole. The winding ratio between the primary coil and the secondary coil for generating a high-voltage current is set to, for example, about 1:80 to 120.
[0003]
Further, in order to increase the change of magnetic flux, in a magnetic circuit forming a closed magnetic circuit type, an air gap 5 (generally about 0.5 to 1.5 mm) is provided or permanent to eliminate magnetic flux saturation of the iron core. A high voltage current is generated in the secondary coil by mounting the magnet 6 so that a magnetic flux flows in a direction opposite to the use state and increasing a change in the magnetic flux.
[0004]
The magnetic resistance of the air gap 5 is proportional to the gap length / cross-sectional area. If the resistance value of the air gap portion is the same, the larger the cross-sectional area can be, the larger the gap length can be. And the like, the allowable range becomes larger. Further, when the permanent magnet 6 is mounted, the change in magnetic flux can be increased by flowing the magnetic flux in the opposite direction to the magnetic saturation point of the iron core used. Therefore, the end 3a of the center iron core 3 is generally expanded as shown in FIGS. 6 and 7, so that the cross-sectional area upon lamination is generally increased.
However, when the center iron core 3 is punched by a continuous press in order to produce an iron core having such a shape, an arrangement as shown in FIG. 6 has been used. Therefore, in order to manufacture iron core materials having these shapes, many punching margins (material loss) 4 have occurred.
[0005]
[Problems to be solved by the invention]
However, in the conventional ignition coil for an internal combustion engine configured as described above, a T-shaped iron core in which only the end of the center iron core is enlarged is manufactured by a press punching process, and as shown in FIG. In this case, a large amount of blanking margin 4 remained, and the steel plate was wastefully consumed. The material loss in the production of the iron core has a yield in the range of 30% to 40% depending on the shape, and greatly affects the production cost of the ignition coil for the internal combustion engine.
[0006]
SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and provides an ignition coil for an internal combustion engine capable of improving the yield of materials by reducing the punching allowance of a T-shaped center core having only an enlarged end. The purpose is to do.
[0007]
[Means for Solving the Problems]
Means for Solving the Problems To achieve the above object, an invention according to claim 1 includes a primary coil and a secondary coil, a center core penetrating the primary coil and the secondary coil, and a peripheral core for forming a closed magnetic circuit with the center core. And a gap or a magnet is formed at the butting portion of the center core and the side core of the magnetic circuit, and has a T-shape to enlarge the cross-sectional area of the butting portion. In the ignition coil for an internal combustion engine described above, the T-shaped center core is divided into two on an axis of symmetry passing through the coil, and these are combined to constitute a center core.
[0008]
According to a second aspect of the present invention, in addition to the first aspect of the present invention, the center iron core forms irregularities on a symmetrical axis divided into two parts, and combines these irregularities to form a T-shaped shape. It is characterized by comprising.
[0009]
According to a third aspect of the present invention, in addition to the first aspect of the present invention, the center core is formed by forming a groove on one of the divided portions and a convex portion on the other.
[0010]
According to a fourth aspect of the present invention, in addition to the first aspect of the present invention, the center iron core has a plurality of irregularities formed on a symmetrical axis divided into two parts.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment. FIG. 1 is a plan view showing an example of an internal combustion engine ignition coil according to the present invention, and FIG. 2 is a longitudinal sectional view of the internal combustion engine ignition coil of the present invention. The ignition coil 10 for an internal combustion engine includes a primary coil 12 and a secondary coil 13 housed in an insulating case 11, a center core 14 passing through the primary coil 12 and the secondary coil 13, a center core 14 and a closed magnetic circuit. A gap 16 or a magnet 17 is formed at the butting portion of the center core 14 and the side core 15 of the magnetic circuit, and the breaking of the butting portion is performed. An ignition coil for an internal combustion engine having a T-shape to increase the area, wherein the center iron core 14 is divided into two core elements 14a, 14a on an axis of symmetry L passing through the primary coil 12 and the secondary coil 13, It is configured by combining these. The core elements 14a are symmetrical with respect to the axis L and have the same shape.
[0012]
FIG. 3 is a plan view showing a process of assembling a center iron core used in the ignition coil for an internal combustion engine of the present invention. In the present embodiment, the center iron core 14 can form the I-shaped portion 18 and the enlarged portion 19 by vertically combining the iron core elements 14a, 14a. The enlarged portion 19 has a substantially trapezoidal shape and is formed in a shape whose width decreases toward the tip thereof. Further, the I-shaped portion 18 has a substantially rectangular shape.
[0013]
In the case of the above configuration, the center core 14 can be formed by combining the separately formed core elements 14a. Therefore, when the abutting portion between the center iron core 14 and the side iron core 15 is an air gap, the allowable range for manufacturing variation of the gap length can be increased. Further, when the butted portion of the center iron core 14 and the side iron core 15 is a permanent magnet, the magnetic flux change of the magnetic circuit can be increased.
[0014]
FIG. 4 is a plan view showing a step of punching a center iron core used in the ignition coil for an internal combustion engine of the present invention. Here, the core element 14 a forming the center core 14 can be manufactured by stamping out a band-shaped silicon steel plate 20. The punching allowance 20a resulting in a punching loss can be extremely reduced as compared with the case where these are integrally manufactured.
[0015]
Therefore, it is possible to reduce the punching loss of the steel plate at the time of manufacturing the center core 14 and reduce the manufacturing cost without lowering the output performance of the ignition coil 10 for the internal combustion engine. The shape of the enlarged portion 19 of the center iron core 14 can be a shape such as a rectangle, a trapezoid, a triangle, or the like that can increase the cross-sectional area. The center iron cores 14 configured as described above can be laminated to form a T-shape having an I-shaped portion 18 and an enlarged portion 19.
[0016]
FIGS. 5A and 5B are plan views showing an assembled state of a center iron core used in the second embodiment of the present invention. In the present embodiment, the center core 21 is composed of a core element 21a and a core element 21b that are divided into two. The core element 21a has a concave portion 22 formed on the axis L, and the core element 21b has a convex portion 23 fitted to the concave portion. In the present embodiment, since these uneven portions 22 and 23 are combined to form a T-shape, there is no risk that the two divided cores will be separated at the combined portion during manufacture, and the manufacturing tolerance of the air gap portion will be reduced. The tolerance can be increased.
[0017]
In the above embodiment, the case where one concave portion and one convex portion are formed is described, but a plurality of concave and convex portions may be formed. In the case of the above-described configuration, the separately formed core element 21a and the core element 21b are fitted and connected. The circuit can be maintained.
[0018]
【The invention's effect】
Since the present invention has the above-described configuration, the following effects can be obtained.
[0019]
According to the first aspect of the present invention, the primary coil and the secondary coil, a center core penetrating the primary coil and the secondary coil, and an annular side disposed around the center core and the closed core to form a closed magnetic circuit. An ignition coil for an internal combustion engine having a T-shape in which a gap or a magnet is formed at the butting portion of the center core and the side cores of the magnetic circuit having a core, and the cross-sectional area of the butting portion is enlarged. The T-shaped center core is divided into two parts on the axis of symmetry passing through the coil, and the center core is formed by combining these. Thus, the press blanking margin can be significantly reduced, and the amount of silicon steel sheet used can be reduced. And the generation of waste materials can be reduced.
[0020]
According to the second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the center core has irregularities formed on a symmetrical axis line divided into two, and these irregularities are combined to form T. Since the mold shape is formed, there is no possibility that the two divided cores are separated at the combination part at the time of manufacturing, and the allowable range for manufacturing variation of the air gap part can be increased.
[0021]
In the invention according to claim 3, in addition to the configuration of the invention described in claim 1, the center iron core is divided because one of the divided cores has a concave groove and the other has a convex portion. There is no risk that the two sets of cores will separate at the combination during manufacturing.
[0022]
In addition, in the invention according to claim 4, in addition to the configuration of the invention described in claim 1, the center iron core has a plurality of irregularities formed on a symmetrical axis line divided into two, so that two divided core sets are formed. Can be more firmly bonded.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of an ignition coil for an internal combustion engine according to the present invention.
FIG. 2 is a longitudinal sectional view of the ignition coil for the internal combustion engine.
FIG. 3 is a plan view showing an assembling process of a center iron core used in the ignition coil for the internal combustion engine.
FIG. 4 is a plan view showing a step of punching a center iron core used in the ignition coil for the internal combustion engine.
FIGS. 5A and 5B are plan views showing an assembled state of a center iron core used in a second embodiment of the present invention.
FIG. 6 is an explanatory view showing a conventional iron core punching shape.
FIG. 7 is a plan view showing an example of a conventional ignition coil for an internal combustion engine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Ignition coil 11 for internal combustion engine 11 Insulating case 12 Primary coil 13 Secondary coil 14 Center iron core 14a Iron core element 15 Side iron core 16 Gap part 17 Magnet 18 I-shaped part 19 Enlarged part 20 Silicon steel plate 21 Center iron core 21a, b Iron core element 22 Recess 23 convex

Claims (4)

A primary coil and a secondary coil;
A center iron core penetrating the primary coil and the secondary coil,
A center gap between the center core and the side core of the magnetic circuit to form a gap or a magnet, the center core having an annular side core disposed around the center core to form a closed magnetic circuit; In an ignition coil for an internal combustion engine having a T-shape to increase the cross-sectional area of
An ignition coil for an internal combustion engine, wherein the T-shaped center core is divided into two on a symmetric axis passing through the coil, and these are combined to form a center core. The ignition coil for an internal combustion engine according to claim 1, wherein the center iron core forms irregularities on a symmetrical axis line divided into two, and forms a T-shape by combining these irregularities. The ignition coil for an internal combustion engine according to claim 1, wherein the center core is formed by forming a groove on one side and a protrusion on the other side. The ignition coil for an internal combustion engine according to any one of claims 1 to 3, wherein the center iron core has a plurality of irregularities formed on a symmetrical axis line divided into two.

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