JP2003309030A - Bobbin structure of ignition coil for internal combustion engine - Google Patents

Abstract

(57) [Summary] A secondary bobbin of a conventional ignition coil is provided with ribs at both ends to increase the strength of the secondary bobbin by increasing the wall thickness of the secondary bobbin. The increase in the wall thickness hinders the provision of a high-performance ignition coil. In an ignition coil for an internal combustion engine in which primary and secondary coils and an iron core are arranged in a case and an epoxy resin is injected and hardened in the case, a bobbin of the primary or secondary coil has a winding portion. And a rib for dividing the winding portion into a plurality of portions, wherein the rib is provided only at both end portions of the bobbin to form a section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil for an internal combustion engine which supplies a high voltage to an ignition plug, and more particularly to a bobbin structure for winding the coil.

[0002]

2. Description of the Related Art FIG. 4 is a vertical cross-sectional view of a cylindrical ignition coil for an internal combustion engine in which ribs are provided at both ends of a secondary bobbin to which a conventional technique is applied, and oblique winding is performed from one end to the other end. . A conventional cylindrical ignition coil for an internal combustion engine has a large opening in the upper part and an opening in the lower part of the cylindrical shape, and has a good electrical insulation characteristic, polyphenylene sulfide (“PPS”).
And a cylindrical case 11 made of a flame-retardant insulating resin material such as polybutylene terephthalate (“PBT”)
And the primary coil 1 in which the primary copper wire is wound around the tower portion 14.
5 and ribs on both ends, with a wall thickness of 1.
A secondary coil 17 having a secondary bobbin 16 of about 2 mm or more and a secondary copper wire wound from one end to the other by oblique winding.
And a central iron core 18 formed of a silicon steel plate or the like, which is a cylindrical ignition coil for an internal combustion engine, wherein a primary voltage for supplying a power supply voltage to the primary coil 15 in the upper housing portion 11b of the case 11 An igniter 13 for mounting the input section 12 and for turning on / off the primary current in the upper housing section 11b.
To store. Further, at the tip of the cylindrical portion of the case 11, there is provided a hole 1 for fitting with an engaging projection 14t of a tower portion 14 which will be described later.
1d is provided.

Further, the central iron core 18 and the central iron core 18
And the secondary coil 17 coaxially with the tower portion 14
The outer iron core 19 which is arranged inside and which is formed into a cylindrical shape and has a cutout portion in a part of its circumference is arranged on the outside thereof. At both ends of the central iron core 18, a magnetic flux generated in the primary coil 15 for suppressing saturation of magnetic flux of the iron core is provided in a secondary coil 17 in which a secondary copper wire is wound around a secondary bobbin 16. Magnets 21 that generate magnetic flux in opposite directions are attached to both ends to increase ignition energy. These are called the primary coil assembly 10.

The bottom portion of the tower portion 14 supplies the high voltage generated in the secondary coil 17 to a spark plug (not shown), and the secondary high voltage terminal 22 is provided on the inner bottom portion of the tower portion 14 and the outer peripheral surface of the tower portion 14 is provided. An O-ring 41 for preventing liquid leakage of the insulating casting material is attached to 114u, and two key-shaped locks protruding outward in the radial direction at equal intervals of 180 ° are attached to the tip of the outer peripheral surface 14u. The mating protrusion 14t is formed.

Next, the above-mentioned primary coil assembly 10
When assembling into the case 11, the two engaging projections 14t provided around the bottom of the tower portion 14 and the hole 11d of the case 11 are fitted into the case 11 at the same time as being inserted from the upper opening of the case 11. The primary voltage input section 21 and the 1
It is electrically connected to the next coil assembly 10. Further, the secondary high voltage terminal 22 is electrically connected to a conductive spring 23, and rubber or the like having excellent electrical insulation is provided so that a high voltage does not leak to a metal part such as a plug hole (not shown) at the bottom of the tower part 14. The protector 25 molded in step 1 is attached to cover the spring 23. In addition, the case 11
Insulation casting material is injected and filled from the opening in the upper part to be cured, and insulation is sealed.

During operation of the ignition coil, a primary current is input from the primary voltage input section 12 to energize the primary coil 15, and the magnetic energy generated in the primary coil 15 is transferred to the central iron core 18 and the exterior. Propagating through the iron core 19, a high voltage corresponding to the winding ratio of the primary coil 15 and the secondary coil 17 is generated in the secondary coil 17. The generated high voltage is the secondary coil 17
Is passed from the secondary high-voltage terminal 22 through the spring 23 to a spark plug (not shown) connected to the spring 23.

FIG. 3 shows a block diagram of the secondary bobbin 16 described above. As shown in FIG. 3, the secondary bobbin 16 includes the winding portion 30 of the secondary coil 17. In the above-mentioned conventional technique, the number of sections is one, and the winding portion 30 is formed by obliquely winding the wire loop to form the secondary coil.

[0008]

In the above-mentioned conventional ignition coil, the secondary bobbin structure is formed from a single section, and if the ignition coil is used for a long time for winding the section, it will be aged. Due to the cold heat stress, mechanical stress is applied to both ends of the central iron core in the epoxy resin, and the stress causes cracks and breakage of the bobbin. In order to be able to withstand this stress, in the above structure, the thickness of the bobbin should be 1.2 mm or more to increase the strength of the bobbin itself, or ribs 31 should be added to the entire winding part as shown in FIG. ing.

Generally, in the engine plug hole size of which the diameter is 20 mm to 35 mm, the number of windings is limited especially for thickening the secondary bobbin of the ignition coil of the type housed in the plug hole. This hinders the provision of a high-performance ignition coil, and along with the demand for miniaturization and high performance, thinning the bobbin is an important design requirement.

In view of the above problems, it is an object of the present invention to provide an ignition coil for an internal combustion engine which supplies a high voltage to an ignition plug, which has a long life and high reliability.

[0011]

In order to solve the above problems, the present invention has the following configuration. In the ignition coil for an internal combustion engine according to claim 1, wherein primary and secondary coils and an iron core are arranged in a case, and epoxy resin is injected and hardened in the case, the bobbin of the primary or secondary coil is wound. 3. A bobbin structure for an ignition coil for an internal combustion engine, comprising: a portion; and a rib that divides the winding portion into a plurality of portions, the rib being provided only at both end portions of the bobbin to form a section. The bobbin having the rib is a secondary bobbin around which a secondary coil is wound. The bobbin structure for an internal combustion engine ignition coil according to claim 1, wherein the bobbin has an epoxy resin. A bobbin structure for an ignition coil for an internal combustion engine according to claim 1, wherein the section is formed by providing a rib in a portion affected by the mechanical stress due to. Further, according to claim 4, in the ignition coil having a cylindrical case, the tower part in which the primary and secondary coils are arranged is attached to the case, and the case is embedded in the plug hole of the internal combustion engine, the secondary bobbin is provided. A bobbin structure for an ignition coil for an internal combustion engine is characterized in that ribs are provided so as to form sections at both end portions of the.

[0012]

As described above, by using the ribs only near both ends of the bobbin, it is possible to use a bobbin that can withstand the mechanical stress applied to both ends of the central iron core due to aged thermal stress. Therefore, the influence on the bobbin due to the aged cooling heat stress generated in the conventional ignition coil is eliminated. As a result, the problem has conventionally been dealt with by increasing the thickness of the bobbin, but since the strength of the secondary bobbin is maintained even if the thickness of the bobbin is reduced, an ignition coil capable of high performance and downsizing can be provided. Can be provided.

[0013]

Embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows a configuration diagram of a bobbin as a first embodiment to which the technique of the present invention is applied, and FIG. 2 shows a longitudinal sectional view of a cylindrical ignition coil for an internal combustion engine including the bobbin.

First, the structure of the ignition coil of the present invention will be described with reference to FIG. The embodiment of the present invention has a large opening in the upper portion and an opening in the cylindrical lower portion, and has a good electrical insulating property, such as polyphenylene sulfide (“PPS”) and polybutylene terephthalate (“PBT”). A cylindrical case 111 made of a flammable insulating resin material, and a primary coil 115 in which a primary copper wire is wound around a tower portion 114.
In a portion forming a section on the secondary bobbin 116 in which ribs are provided so as to form sections on both end portions of the bobbin, a secondary coil 17 formed by winding a secondary copper wire in a laminated winding and a silicon steel plate or the like. A cylindrical ignition coil for an internal combustion engine having a central iron core 118 formed therein, wherein the primary coil 115 is provided in an upper housing portion 111b of the case 111.
A primary voltage input unit 112 that supplies a power supply voltage to
In some cases, an igniter 113 for turning on / off the primary current is stored in the upper storage portion 111b. Further, the central iron core 118 and the secondary coil 117 coaxially with the central iron core 118 are arranged in the tower portion 114, and they are formed into a cylindrical shape on the outside thereof and cut into a part of the circumference thereof. Placing the exterior iron core 119 having a cutout

A secondary coil 117 in which a secondary copper wire is wound around a secondary bobbin 116 is provided at both ends of the central iron core 118.
In order to suppress the saturation of the magnetic flux of the iron core, the primary coil 11
Magnet 1 that generates a magnetic flux in the opposite direction to the magnetic flux generated in 5
In some cases, 21 is attached to both ends to increase the ignition energy. These are referred to as the primary coil assembly 110.

The bottom portion of the tower portion 114 supplies the high voltage generated in the secondary coil 117 to a spark plug (not shown), the bottom inner portion of the tower portion 114 is provided with a secondary high voltage terminal 122, and the outer periphery of the tower portion 114 is provided. An O-ring 141 for preventing liquid leakage of the insulating casting material is attached to the surface 114u, and two key-shaped parts protruding outward in the radial direction at equal intervals of 180 ° are attached to the tip of the outer peripheral surface 14u. The engagement protrusion 14t is formed.

Next, the above-mentioned primary coil assembly 11
When assembling 0 into the case 111, the case 1
11 Two engaging projections 114t provided around the bottom of the tower 114 and fitted into the hole 111d of the case 111 at the same time as the primary voltage input 121 and the primary coil assembly. It is electrically connected to 110. Further, the secondary high-voltage terminal 122 is electrically connected to a conductive spring 123, and a rubber or the like having excellent electrical insulation is provided so that a high voltage does not leak to a metal portion such as a plug hole (not shown) at the bottom of the tower portion 114. The protector 125 molded by
Cover 3. Further, an insulating casting material is injected and filled from the opening in the upper part of the case 111, and is cured to insulate and seal.

During operation of the ignition coil, a primary current is input from the primary voltage input section 112 to energize the primary coil 115, and the magnetic energy generated in the primary coil 115 is transferred to the central iron core 118 and the exterior. Propagating through the iron core 119, a high voltage corresponding to the winding ratio of the primary coil 115 and the secondary coil 117 is generated in the secondary coil 117. The generated high voltage is sent from the secondary coil 117 to the spark plug (not shown) connected to the spring 123 through the secondary high voltage terminal 122 and the spring 123.

Further, the secondary bobbin 116 will be described in detail with reference to FIG. 1. In the secondary bobbin 116 constituted by the winding portion 130, a plurality of parts are provided on the high pressure side or the low pressure side. The rib 131 is provided. Even if the bobbin has a wall thickness of about 0.8 mm, there is no problem in practical use.

In the first embodiment, the ribs are evenly provided at both ends of the low pressure side and the high pressure side. However, as another embodiment, the ribs are arranged only at the positions where the cold stress of the ignition coil is applied. It is sufficient to provide only one on the high pressure side or only on the low pressure side. If the number of bobbins can be obtained without providing a plurality of them, the same effect can be obtained by providing only one. Is obtained. The type of the bobbin is not limited to the secondary bobbin, and may be applied to the primary bobbin if necessary.

[0021]

When the ignition coil of the present invention is used, the thickness of the bobbin can be made thinner by about 0.4 mm or more than the conventional one, and this requirement can be satisfied even for the ignition coil which is required to be downsized.
Further, even when it is not necessary to reduce the size, more windings can be made with the same size, so that a high-performance ignition coil can be provided.

As described above, it is possible to provide an inexpensive and highly reliable ignition coil for an internal combustion engine which is mounted in the plug hole of the engine and supplies a high voltage to the ignition plug.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a bobbin to which the technique of the present invention is applied.

FIG. 2 is a vertical cross-sectional view of a cylindrical ignition coil for an internal combustion engine showing an embodiment having a secondary bobbin provided with a plurality of sections in a low pressure portion and a high pressure portion of a secondary bobbin to which the technique of the present invention is applied. .

FIG. 3 shows a configuration diagram of a conventional bobbin.

FIG. 4 is a vertical cross-sectional view of a cylindrical ignition coil for an internal combustion engine in which ribs are provided at both end portions of a secondary bobbin to which a conventional technique is applied, and oblique winding is performed from one end to one end.

FIG. 5 shows a configuration diagram of another conventional bobbin.

[Explanation of symbols]

In the drawings, the same reference numerals indicate the same or corresponding parts. 10 Primary coil assembly 11 cases 11b Upper storage 11d hole 21 Primary voltage input section 13 Igniter 14 Tower 14u High-pressure tower outer peripheral surface 14t engagement protrusion 15 Primary coil 16 Secondary bobbin 16a secondary bobbin 17 Secondary coil 18 center iron core 19 Exterior iron core 21 Permanent magnet 22 Secondary high voltage terminal 23 spring 25 Protector section 30 winding part 31 ribs 41 O-ring 110 Primary coil assembly 111 cases 111b Upper storage 111d hole 121 Primary voltage input section 113 Igniter 114 tower section 114u High pressure tower outer peripheral surface 114t engagement protrusion 115 Primary coil 116 Secondary bobbin 116a secondary bobbin 117 Secondary coil 118 center iron core 119 Exterior iron core 121 permanent magnet 122 Secondary high voltage terminal 123 spring 125 protector section 130 winding part 131 ribs 141 O-ring

Claims (4)

[Claims] 1. An ignition coil for an internal combustion engine in which primary and secondary coils and an iron core are arranged in a case, and epoxy resin is injected and hardened in the case, wherein a bobbin of the primary or secondary coil is wound. A bobbin structure for an ignition coil for an internal combustion engine, comprising: a portion; and a rib that divides the winding portion into a plurality of portions, the rib being provided only at both end portions of the bobbin to form a section. 2. The bobbin provided with the rib is a secondary bobbin around which a secondary coil is wound.
A bobbin structure for an ignition coil for an internal combustion engine according to claim 1. 3. The bobbin structure for an ignition coil for an internal combustion engine according to claim 1, wherein the section is formed by providing a rib on a portion of the bobbin that is affected by the mechanical stress caused by the epoxy resin. 4. An ignition coil having a cylindrical case, and a tower part having primary and secondary coils arranged in the case, and the case being embedded in a plug hole of an internal combustion engine. A bobbin structure for an ignition coil for an internal combustion engine is characterized in that a rib is provided so as to form a section in a portion.