JPH10112412A - Ignition coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure stable output characteristics even when a gap between an ignition coil main body and a non-permeable material is narrow, by setting a specific cross-section area ratio between an outside layer iron core provided on the outer periphery of a coil and a center iron core. SOLUTION: A center iron core 23 assigned on a cylinder axis of a plug hole, a secondary coil 222 which, on the outside periphery of the center iron core 23, wound in vertical direction against a longitudinal direction of the center iron core 23, and a primary coil 222 wound coaxially, on its outer periphery, with the secondary coil 222, are provided. The secondary coil 222 is wound on a secondary bobbin 223, and the primary coil 212 is wound on a primary bobbin 211. Between the coils and a case 27, the first outside layer iron core 40 and the second outside layer iron core 42 are provided. The cross-section area ratio formed between the first and second outside layer iron cores 40 and 42 is 70% of the center iron core 23 or above. Thereby, the attenuation in output characteristics after insertion in the plug hole is set about 7%, for stable output characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil used in an internal combustion engine for a motor vehicle, and more particularly to an ignition coil having a central iron core and an outer iron core.

[0002]

2. Description of the Related Art In an internal combustion engine, particularly for an automobile, an ignition coil is required to have a small size and high characteristics with the miniaturization of the internal combustion engine. Conventionally, in a double overhead cam type internal combustion engine, an ignition coil that does not require a distributor is arranged in a space created between cylinder heads, and various plug-in type ignition coils have been put to practical use in other types of internal combustion engines. ing. 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.

Under the above circumstances, 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 in which a spark plug is mounted. Generally, the outer diameter of a spark plug of a vehicle internal combustion engine is about 16 mm to 20 mm, and a plug hole into which the spark 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 side view of a conventional plug-hole insertion type ignition coil, and FIG. 3 is a cross-sectional view of FIG. 2 and 3, the ignition coil
Numeral 20 comprises a primary connector 26 for inputting a primary voltage and a case 27. The lower portion of the case 27 is embedded in a plug hole (not shown), and the lower end is connected to a spark plug. 1
Next, the secondary coil portion is configured as shown in the sectional view of FIG. That is, a center iron core 23 disposed on the cylinder axis of the plug hole, and a secondary winding that is wound around the outer periphery of the center iron core 23 and perpendicular to the longitudinal direction of the center iron core 23. 222, a primary winding 212 coaxially wound around the secondary winding 222 on the outer periphery thereof, and an outer layer iron core 40 between the coils and the case 27. The secondary winding 222 is wound around the secondary bobbin 223, and the primary winding 212 is wound around the primary bobbin 211. In the conventional ignition coil described above, the cross-sectional area ratio of the outer iron core 40 is about 50% of the center iron core 23.

[0005]

The ignition coil having the above configuration has the following problems. That is,
When an ignition coil having a cross-sectional area ratio of the outer iron core 40 of about 50% of that of the center iron core 23 is mounted in a plug hole, particularly in a plug hole formed of a non-magnetically permeable material, the magnetic flux induced from the primary coil is reduced. The plug hole is cut off, and the performance of the ignition coil itself is reduced. Such a phenomenon becomes more conspicuous as the gap between the plug hole and the ignition coil is smaller.

In view of the above problems, the present invention is directed to an ignition coil shaped to be buried in a plug hole, even if the gap between the ignition coil body and the non-magnetically permeable material (plug hole) is narrow. An object of the present invention is to provide a high-performance ignition coil.

[0007]

According to the present invention, there is provided a secondary coil wound around a secondary bobbin.
A primary coil wound around the primary bobbin, a central iron core through which magnetic flux induced by the primary coil passes, and a central iron core in a central iron core insertion portion forming the primary coil or the secondary coil;
An ignition coil for an internal combustion engine having an outer core on an outer periphery of the coil, wherein a cross-sectional area ratio of the outer core is 70% or more of the center iron core.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a side view of an ignition coil according to an embodiment of the present invention, and FIG. 1 is a cross-sectional view of the AA cross section of FIG. 1 and 2, the ignition coil 20 has a primary connector 26 for inputting a primary voltage and a case 27.
The lower part of the case 27 is embedded in a plug hole (not shown), and the lower end is connected to a spark plug.
The primary and secondary coils and the iron core are configured as shown in the sectional view of FIG. That is, a center iron core 23 disposed on the cylinder axis of the plug hole, and a secondary winding that is wound around the outer periphery of the center iron core 23 and perpendicular to the longitudinal direction of the center iron core 23. 222, and a primary winding 212 wound coaxially with the secondary winding 222 on the outer periphery thereof. As is well known, the secondary winding 222 is wound around a secondary bobbin 223, and the primary winding 212 is wound around a primary bobbin 211. A first outer core 40 and a second outer core 42 are provided between the coils and the case 27. In the ignition coil of this embodiment, the first outer core 40 and the second
The cross-sectional area ratio of the outer core 42 and the outer core 42 is 70
%.

The outer core in the above configuration is provided with a second outer core 42 in order to divert the conventional outer core 40. Such an outer core has a sectional area of the central iron core 23. Of 70
%, Two or more iron cores may be combined to form the outer iron core. Also, if 70% or more of the cross-sectional area of the central iron core 23 is obtained, two or more outer cores may be formed as one part if the outer core has a large cross-sectional area without being composed of two or more outer cores. Can also.

Although the present embodiment describes an ignition coil in which each coil and the central iron core 23 are mounted in the plug hole 10, the ignition coil of the present invention is not limited to such an ignition coil. Of course, the same effect can be obtained in other ignition coils, particularly in a type in which the periphery of the coil is covered with a non-magnetic material.

In the above embodiment, the secondary coil 22 is provided on the outer periphery of the center iron core 23, and the primary coil 21 is provided on the outer periphery.
1. A configuration such as a secondary coil 22 may be provided on the outer periphery.

[0012]

The sectional area of the conventional central iron core 23 is 50
%, The output characteristics after insertion into the plug hole were about 20% inferior to those before insertion in the ignition coil provided with the outer iron core 40 having a cross-sectional area ratio of about 20%. It has been experimentally revealed that the attenuation of this output characteristic can be suppressed to about 7%. According to the present invention, a stable output characteristic can be obtained even with an ignition coil having the same shape, and a high-quality ignition coil can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an ignition coil according to an embodiment of the present invention;
The figure which looked at the A section in the arrow direction is shown.

FIG. 2 is a side view of the present invention and a conventional ignition coil.

FIG. 3 is a diagram showing a cross section AA of the ignition coil shown in FIG.

[Explanation of symbols]

 In the drawings, the same reference numerals indicate the same or corresponding parts. Reference Signs List 20 ignition coil 21 primary coil 211 primary bobbin 212 primary winding 22 secondary coil 222 secondary winding 223 secondary bobbin 23 center iron core 40 first outer iron core 42 second outer iron core

Claims (3)

[Claims] A secondary coil wound around a secondary bobbin;
A primary coil wound around a secondary bobbin, a central iron core through which a magnetic flux induced by the primary coil passes, and a central iron core in a central iron core insertion portion forming a primary coil or a secondary coil; In an ignition coil for an internal combustion engine having an outer core on an outer periphery, a cross-sectional area ratio of the outer core is 7% of that of the center iron.
An ignition coil characterized by being at least 0%. 2. The ignition coil according to claim 1, wherein the high voltage output section of the ignition coil is directly connected to the ignition plug. 3. An ignition coil according to claim 1, wherein the ignition coil according to claim 1 is of a plug-hole mounting type.