JP2009111199A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil for internal combustion engine wherein an ignition coil side high pressure output terminal of a connection portion between a spring and the ignition coil side high voltage output terminal has high durability against deterioration in insulation due to corona discharge, since, in a plug top type ignition coil, an inner surface of a high voltage end portion (a side of disposing a spring) of a coil case is corona-deteriorated by the spring which electrically connects high voltage, thus deteriorating insulation reliability. <P>SOLUTION: A cylindrical portion made of a material superior in corona deterioration durability than the high voltage tower, which covers the periphery of at least one of the ignition coil side high voltage output terminal and the connection portion between the spring and the ignition coil side high voltage output terminal, is provided. Thereby, insulation reliability of the high voltage connection portion of the plug top type ignition coil can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an independent ignition type ignition coil for an internal combustion engine that is used by being directly attached to each ignition plug of an engine, and more particularly to a plug top type ignition coil device.

  A plug-top type ignition coil device known from Japanese Patent Application Laid-Open No. 2002-266738 is attached to an upper part of an engine head for generating a high voltage, and a high voltage is attached to a lower part of the engine head (in a plug hole). The high-pressure connection conductor pipe portion for energizing the spark plug is integrated.

  The plug-top type ignition coil has a separate coil part and high-voltage connection conductor pipe part, so the length of the high-voltage connection conductor pipe part can be changed according to the difference in coil mounting length that varies depending on the engine. It has an advantage that the coil part can be used in common, and the ignition coil has excellent versatility.

  The high-voltage connection conductor pipe portion includes a spring electrically connected to a coil-side high-voltage connection terminal formed in the high-voltage tower of the coil case, and an insulation pipe for interior of the spring, and on the coil portion side of the insulation pipe Is attached with a connecting elastic body (connecting rubber) for mechanical connection with the coil case of the coil portion, and a boot for ensuring mechanical connection with the spark plug and insulation on the spark plug side. Is installed.

  The stepped part (hook shape) formed over the entire outer circumference of the high-voltage tower of the coil case is mechanically connected by covering the connecting rubber mounted on the ignition coil side of the high-voltage connection conductor pipe part to prevent it from coming off. It is composed.

Japanese Patent Laid-Open No. 2002-266738

  However, the spring that electrically connects the high voltage causes corona degradation on the inner surface (spring arrangement side) of the coil case, which causes a decrease in insulation reliability.

  An object of the present invention is to provide an ignition coil for an internal combustion engine in which the ignition coil side high voltage output terminal or the joint between the spring and the ignition coil side high voltage output terminal has high durability against insulation deterioration due to corona discharge. .

  In order to achieve the above object, in the present invention, a material superior in corona deterioration durability than a high-voltage tower that covers at least one of an ignition coil-side high-voltage output terminal or a joint between a spring and an ignition coil-side high-voltage output terminal. The cylindrical part formed by was provided.

  According to the present invention configured as described above, it is possible to improve the insulation reliability of the high pressure connection portion of the plug-top type ignition coil for an internal combustion engine.

  An embodiment of the present invention will be described with reference to FIGS.

  The coil portion attached to the engine head 1 is housed in the coil case 2 and includes at least the primary coil 3, the secondary coil 4, the primary coil 3 and the iron core 5 that magnetically couples the secondary coil 4, and these. The epoxy resin 6 for electrical insulation is filled, and the high voltage terminal 7 is press-fitted into the coil case 2 at the high voltage end of the coil case 2, thereby sealing the epoxy resin 6 and generating it at the coil portion. It has the function of an output terminal for transmitting a high voltage to the high voltage connection side.

  The high voltage connecting portion for energizing the spark plug 8 with a high voltage from the coil portion includes a spring 9 for electrically connecting the high voltage terminal 7 and the spark plug 8 on the coil portion side, and an insulation for incorporating the spring 9 therein. A connecting rubber 11 for mechanically connecting to the coil case 2 of the coil portion is attached to the coil portion side of the insulating pipe 10, and a spark plug 8 and a mechanical portion are provided to the spark plug side. A boot 12 for connection is attached and configured.

  Next, a connection structure for integrating the coil part and the high-voltage connection part will be described.

  In order to transmit the high voltage generated in the coil part to the spring, the high voltage terminal 7 is arranged on the inner wall of the coil case high voltage end part. The meat stealing part 2a is connected between the inner wall part of the coil case and the outer hook part. It is provided around the circumference to improve the moldability of the case.

  The meat stealing portion 2a is filled with an epoxy resin 6 used to ensure insulation inside the coil. Epoxy resin 6 has better resistance to corona degradation than thermoplastic resin such as PBT and PPS (about twice), and the insulation reliability of the connection is improved by interposing an epoxy resin layer. To do.

  The thickness of the coil case on both sides of the meat stealing portion 2a is preferably about 1 to 2 mm for both the inner thickness 2b and the outer thickness 2c in consideration of formability and insulation. Is necessary to press fit and hold, and the outer wall thickness 2c is necessary to improve the moldability of the coil case. Considering strength and insulation properties, it is possible to suppress the expansion of the outer diameter of the connecting portion by making the thickness optimal.

  Next, a second embodiment will be described with reference to FIG.

  By providing a connection rubber layer 11a made of silicone rubber having resistance to corona deterioration on the inner side of the high voltage end of the coil case 2, the resistance of corona deterioration at the spring 9 is enhanced. In addition, since the holding strength can be increased by sandwiching the coil case 2 with rubber from both sides, in this embodiment, the hook portion on the outer side of the case is kept low and the outer diameter is not enlarged.

  A third embodiment will be described with reference to FIG.

  By providing an annular thin metal 13 inside the high voltage portion of the coil case 2, electric field concentration due to the spring 9 (the spring has a circular cross section, it becomes a point when viewed from the inside of the case) and the case and the high voltage component Corona degradation can be suppressed. A material made of aluminum, brass, iron, copper or the like having a thickness of about 0.3 to 1 mm is suitable for the material in consideration of workability and mass productivity.

  When the resin wall thickness of the high-voltage end of the coil case is partially extremely increased, the moldability is deteriorated and the reliability of the mechanical strength of the connection portion is lowered.

  If cracks occur in this part, the insulation reliability also decreases, but in this embodiment, it is not necessary to increase the resin wall thickness at the high-voltage end of the coil case so much that the moldability is good, so the machine of the connection part There is an advantage that the reliability of the mechanical strength is improved and the insulation reliability of the connecting portion can be improved.

  Embodiments are listed below.

Embodiment 1
A coil portion housed in a coil case and configured by at least a primary coil, a secondary coil, an iron core for magnetically coupling the primary coil and the secondary coil, and an insulating resin for electrically insulating them; An internal combustion engine comprising: a high voltage connection portion for energizing a spark plug with a high voltage generated in the coil portion; and the coil portion and the high voltage connection portion are integrated using an elastic member (connection elastic body) An ignition coil for an internal combustion engine, wherein the connection structure of the coil part and the high-voltage connection part is composed of a plurality of members.

Embodiment 2
The internal combustion engine according to the first embodiment, wherein the connection structural member of the coil portion and the high-voltage connection portion has a structure of a case resin member, an insulating resin, a case resin member, and a connection elastic body in order from the inner side where a high voltage is applied. Ignition coil.

Embodiment 3
2. The ignition coil for an internal combustion engine according to claim 1, wherein the connection structural member of the coil portion and the high voltage connection portion has a structure of a connection elastic body, a case resin member, and a connection elastic body in order from the inner side where a high voltage is applied.

Embodiment 4
The ignition coil for an internal combustion engine according to the first embodiment, wherein the connection structure member of the coil portion and the high-voltage connection portion is composed of an annular metal, a case resin member, and a connection elastic body in order from the inner side where a high voltage is applied.

Sectional drawing of the ignition coil for internal combustion engines. The expanded sectional view which shows the 1st Example of this invention. The expanded sectional view which shows the 2nd Example of this invention. The expanded sectional view which shows the 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine head 2 Coil case 2a Meat stealing part 2b Inner wall thickness 2c Outer wall thickness 3 Primary coil 4 Secondary coil 5 Iron core 6 Epoxy resin
7 High voltage terminal 8 Spark plug 9 Spring
10 Insulating pipe 11 Connection rubber 11a Rubber layer
12 Boots 13 Thin metal

Claims (8)

Ignition coil case,
An iron core disposed in the ignition coil case,
A primary bobbin wound with a primary coil,
A secondary bobbin wound with a secondary coil,
Insulation hardening resin that insulates the primary bobbin and the secondary bobbin that are filled in the ignition coil case and arranged to surround the iron core,
High voltage tower part as a high voltage output terminal part provided in the ignition coil case,
An insulating pipe inserted into the plug hole and having one end electrically and mechanically coupled to the plug and the other end electrically and mechanically coupled to the high-voltage tower section;
A connection rubber provided at the joint between the insulating pipe and the high-pressure tower,
Ignition coil side high voltage output terminal arranged inside the high voltage tower,
In what is provided with a spring connected to the ignition coil side high voltage output terminal and fitted in the insulating pipe,
A cylindrical portion formed of a material having better corona deterioration durability than the high-voltage tower, covering at least one of the ignition coil-side high-voltage output terminal or the joint between the spring and the ignition coil-side high-voltage output terminal. An internal combustion engine ignition coil provided. In claim 1,
An internal combustion engine ignition coil, wherein the cylindrical portion is formed of the insulating resin material filled in a cylindrical groove formed inside the high-pressure tower. In claim 1,
The cylindrical portion is formed by a cylindrical rubber portion formed integrally with the connecting rubber, which is disposed between an inner peripheral portion of the high-voltage tower and a joint portion of the spring and the ignition coil side high-voltage output terminal. An ignition coil for an internal combustion engine. In claim 1,
An ignition coil for an internal combustion engine, which is formed of a metal cylinder provided on an inner peripheral portion of the high-pressure tower around a joint portion between the ignition coil-side high-voltage output terminal or the spring and the ignition coil-side high-voltage output terminal. In any one of claims 1 to 4,
An ignition coil for an internal combustion engine, wherein the ignition coil case is made of a thermoplastic resin material of a PBT or PPS member, and an epoxy resin is used as the insulating resin. What is described in claim 5
An ignition coil for an internal combustion engine using silicone rubber as the connection rubber. The thing of Claim 4 WHEREIN:
An ignition coil for an internal combustion engine, wherein the metal cylinder uses aluminum, brass, iron, or copper as a material. What is described in claim 7,
An ignition coil for an internal combustion engine, wherein the metal cylinder has a thickness of 0.3 to 1 mm.

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