JP2002231543A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly efficient ignition coil for an internal combustion engine which is reduced in eddy current loss caused by magnetic fluxes generated in an iron core. SOLUTION: In this ignition coil for an internal combustion engine, the widths of thin iron core plates 23 are reduced by making the direction of lamination of several thin iron core plates 23 of the same kind near the center of the cross section of a center iron core 23 perpendicular to the direction of lamination of the other thin iron core plates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an iron core structure of an ignition coil for an internal combustion engine.

[0002]

2. Description of the Related Art As an internal combustion engine is miniaturized, an ignition coil for an internal combustion engine is required to have a small size and high characteristics. 2. Description of the Related Art Conventionally, in a double overhead cam type internal combustion engine, a direct plug type ignition coil which does not require a distributor in a space created between cylinder heads has been put to practical use. However, such an ignition coil is also required to have additional values such as improved output characteristics and the incorporation of an igniter, and it is actually difficult to reduce the size of the ignition coil body. It has become difficult to arrange the coils in the limited space of the internal combustion engine, especially the cylinder head.

[0003] Under the circumstances described above, there have been proposed some types in which a part or all of an ignition coil is arranged in a space formed in a plug hole 60 in which an ignition plug is mounted. Generally, the outer diameter of a spark plug of an internal combustion engine for an automobile is about 16 mm to 20 mm, and a plug hole 60 into which the plug is inserted.
Has an inner diameter of about 20 mm to 35 mm and a depth of about 100 mm.

FIG. 2 is a longitudinal sectional view of an ignition coil for directly supplying a high voltage to an ignition plug to which the prior art is applied. In FIG. 2, an ignition coil 10 for directly supplying a high voltage to an ignition plug includes a primary connector 26 on an upper part of a case 27,
An igniter 2 for turning on / off the primary current in some cases
5 are stored. A secondary coil 22 in which a secondary winding 222 is wound around a secondary bobbin 223 coaxially with a central iron core 23.
And a primary coil 21 in which a primary winding 212 is wound around a primary bobbin 211, and an exterior iron core 40 formed in a cylindrical shape and having a cutout in a part of the circumference thereof are arranged in order. A secondary high voltage terminal 24 is provided at the bottom of the case 27, and the secondary high voltage terminal 24 is electrically connected to the secondary coil 22 and the spring 23 in the high voltage tower 11 a provided in the case 27, and an opening at the top of the case 27. A thermosetting resin 50 is injected and filled to cure the resin, and is insulated and sealed. Further, the high-pressure tower 11a is provided with a plug boot 28 so that a high voltage does not leak to a metal part such as the plug hole 60.

The center iron core 23 has a thickness of 0.5 mm to 0.5 mm.
In order to improve the efficiency of the magnetic circuit with a thin silicon steel sheet of 35 mm, its cross section is made close to a circle and the iron core occupancy is improved. For this purpose, a multi-stage shape in which about 8 to 12 single plates of different widths are stacked, that is, the thin plates 231a, 231
1b, 231c, 231d, 231e, 231, 231
f, an iron core 23 formed by fixing thin plates 231 laminated in the order of 231 g with an adhesive, welding, or caulking. In particular, if a number of types of thin plates having different widths are formed, the profitability deteriorates due to the mold making thereof. I have.

When a primary current is input from the primary connector 26 of the ignition coil 10, a magnetic flux is generated in the primary coil 21. The generated magnetic flux is easily passed by the central iron core 23, and the primary current is interrupted at the ignition timing to generate a high voltage in the secondary coil 22. Further, the high voltage generated in the secondary coil 23 is applied to the ignition plug 30 via the secondary high voltage terminal 24 and the spring 29.

When the ignition coil 10 is operated in this manner, a vortex current flows through the thin plate 231 of the central iron core 23 so as to cancel the change in magnetic flux by electromagnetic induction. This current is called an eddy current, and this eddy current causes a loss of energy and hinders the improvement of the output performance of the ignition coil 10.

[0008]

As one of the measures against such eddy current loss, an eddy current loss generated in a thin plate is formed by laminating ultra-thin plates having a smaller thickness than before to form a central iron core. However, it is known that the iron core of an ultra-thin plate is expensive and difficult to process in order to maintain the thickness accuracy.
Therefore, an object of the present invention is to provide an ignition coil for an internal combustion engine that improves output performance by reducing eddy current loss without using an extremely thin plate.

[0009]

In order to solve the above-mentioned problems, an ignition coil for an internal combustion engine according to the present invention is provided with a primary connector 26 in an upper storage portion of a case 27 as shown in FIG. The igniter 25 is turned on and off, and the secondary bobbin 22 is coaxially arranged with a circular center iron core 23 formed by stacking several thin plates 231 having several types of widths.
3, a secondary coil 22 having a secondary winding 222 wound thereon, and a primary coil 2 having a primary winding 212 wound around a primary bobbin 211.
1 and an exterior coil 40 formed in a cylindrical shape and having a notch in a part of its circumference in an ignition coil for an internal combustion engine, in which a thin plate 2 near the center of the central core 23 is provided.
31 is characterized in that a thin plate 231h whose width is reduced and which is arranged so as to be in a stacking direction perpendicular to another stacking direction is used.

[0010]

By applying the technique of the present invention to the center iron core 23 of the ignition coil for an internal combustion engine as described above, it is possible to increase the electrical resistivity per thin plate 231 of the center iron core 23 whose width is reduced. Can be. As a result, the eddy current on the thin plate due to the magnetic flux generated in the central iron core due to the operation of the ignition coil becomes difficult to flow, and the eddy current loss is reduced. As a result, the loss of the magnetic circuit is reduced, and a highly efficient internal combustion engine ignition coil with improved output performance can be provided.

[0011]

FIG. 1 is a sectional view of a center iron core of an ignition coil for an internal combustion engine to which the technology of the present invention is applied.

The center iron core 23 of the present invention uses a center iron core whose width is reduced in a thin plate near the center of the center iron core in FIG. 1 and which is arranged perpendicular to the other laminating directions. In particular,
The center iron core is prepared by preparing several types of thin plates 231 having different widths from thin plates formed of a silicon steel plate having a thickness of 0.35 mm, and disposing them on multiple stages 231a, 231b, 231c, 231d, 231.
e, 231f are stacked in this order, and two of them are fixed with an adhesive, welding or caulking. Next, about 20 thin plates 231h are stacked and fixed in the same manner as described above. By joining and fixing the thin plates 231 so that the laminating direction is vertical, a center iron core having a circular cross section is completed.

By using the above-mentioned center iron core for the ignition coil for the internal combustion engine, the primary current input from the primary current input section 26 attached to the case 27 of the ignition coil is:
Although a magnetic flux is generated in the primary coil 21, the magnetic flux is more easily passed through the central iron core 23 because the eddy current loss is reduced, and the primary current is cut off at the ignition timing, so that the secondary coil 23 is To generate high voltage. And the secondary coil 23
Is applied to the ignition plug 30 via the secondary high voltage terminal 21 and the spring 29.

[0015]

As described above, by applying the technique of the present invention, the electrical resistivity per sheet can be increased,
Since the eddy current loss is reduced, a highly efficient internal combustion engine ignition coil can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a center iron core 23 of an ignition coil for an internal combustion engine to which the technology of the present invention is applied.

FIG. 2 is a longitudinal sectional view of an ignition coil for an internal combustion engine to which the prior art is applied.

FIG. 3 is a sectional view of a center iron core 23 of an ignition coil for an internal combustion engine to which the related art is applied.

[Explanation of symbols]

 In the drawings, the same reference numerals indicate the same or corresponding parts. DESCRIPTION OF SYMBOLS 10 Ignition coil 21 Primary coil 211 Primary bobbin 212 Primary winding 22 Secondary coil 222 Secondary winding 223 Secondary bobbin 23 Center iron core 231a, b, c, d, e, f, g Thin plate 231h Thin plate 24 Secondary high voltage terminal 25 Igniter 26 Primary connector 27 Case 28 Plug boot 29 Spring 30 Spark plug 40 Armor core 50 Thermosetting resin 60 Plug hole

Claims (1)

[Claims] An igniter for turning on and off a primary connector and, in some cases, a primary current in an upper storage portion of a case.
Is stored in the secondary bobbin coaxially with a central iron core 23 formed in a circular shape by stacking several thin plates having several widths.
A secondary coil wound with a secondary winding, a primary coil wound with a primary winding on a primary bobbin, and an armored iron core formed into a cylindrical shape and having a cutout in a part of its circumference. In the internal combustion engine ignition coil, the width is reduced to a thin plate near the center of the center iron core, and the thin plate is arranged so as to be in a stacking direction perpendicular to another stacking direction. Ignition coil for internal combustion engine.