JP2009167978A - Ignition coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil surely preventing a plug installation part to a spark plug from coming off. <P>SOLUTION: A high voltage terminal 4 of the plug installation part of the ignition coil includes a cylindrical insertion part 41 for inserting a conductive male screw terminal 61 formed at a tip side of an insulator 62 of the spark plug 6. A clip spring 5 for preventing the male screw terminal 61 inserted in the insertion part 41 from coming off is provided at an outer circumference of the insertion part 41. The clip spring 5 includes a retaining part 51 retaining the clip spring at the outer circumference of the insertion part 41, and a fitting part 52 extended from the retaining part 51 and fitted in a screw valley 611 of the male screw terminal 61 via a notch hole 411 formed at an outer circumference of the insertion part 41. The fitting part 52 has an acute edge 521 fitting in a V-shaped groove at the screw valley 611 of the male screw terminal 61 in a section shape thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ignition coil used for generating a spark between a pair of electrodes in a spark plug in an internal combustion engine.

An ignition coil used in an internal combustion engine such as an engine is used to apply a high voltage for generating a spark to a spark plug for generating a spark in a combustion chamber of the engine. A plug mounting portion for mounting the spark plug in the ignition coil includes a high voltage terminal electrically connected to the high voltage winding end portion of the secondary coil and a rubber plug cap for press-fitting the insulator portion of the spark plug. Provided.
In particular, in a spark plug for a motorcycle, the shape of the terminal portion is a shape in which a male screw is formed (hereinafter referred to as a male screw terminal portion). The male screw terminal portion is formed as a high voltage terminal. By being hooked by the protrusions, separation from the high voltage terminal is prevented.

However, in the high voltage terminal of the conventional ignition coil, the structure for hooking the male terminal portion of the spark plug is not sufficient. In other words, the projection for hooking the male screw terminal portion is formed in a circular cross section, and further contrivance is required to prevent the plug mounting portion from being detached from the spark plug.
In the plug connection body of Patent Document 1, the plug terminal is configured to be separated into a crimping terminal for crimping and fixing an electric wire and an ignition plug holding terminal for connecting an ignition plug, and prevents the plug cap from coming off. We are doing something to do.
However, even in Patent Document 1, no attempt has been made to prevent the plug terminal from falling off the spark plug having the male screw terminal portion.

JP 2001-230049 A

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an ignition coil that can reliably prevent the plug mounting portion from being detached from the spark plug.

The present invention
In the ignition coil formed by connecting a plug mounting portion for connecting a high-voltage side winding end of the secondary coil to a spark plug to a coil portion including a primary coil and a secondary coil,
The plug mounting portion is provided with a high voltage terminal connected to the high voltage side winding end on the inner peripheral side of the tower portion formed by forming the insulating resin forming the coil portion into a cylindrical shape. And a rubber plug cap for press-fitting the insulator portion of the spark plug on the outer peripheral side of the tower portion.
The high-voltage terminal has a cylindrical insertion portion for inserting a conductive male screw terminal portion formed on the tip side of the insulator portion of the spark plug,
A clip spring is provided on the outer periphery of the insertion portion to prevent the male screw terminal portion inserted into the insertion portion from coming off.
The clip spring includes a holding portion to be held on the outer peripheral portion of the insertion portion, and a thread valley portion of the male screw terminal portion through a notch hole formed in the outer peripheral portion of the insertion portion. And a fitting portion for fitting into
An ignition coil characterized in that the fitting portion has an acute corner portion that fits into a V-shaped groove in a thread valley portion of the male screw terminal portion in the cross-sectional shape thereof.
(Claim 1).

The ignition coil of the present invention is devised in the shape of the high voltage terminal and clip spring constituting the plug mounting portion.
Specifically, a clip spring is provided on the outer peripheral portion of the insertion portion of the high voltage terminal, and the cross-sectional shape of the insertion portion of the clip spring is changed to a V-shaped groove in the thread valley portion of the screw terminal portion of the spark plug. The shape has sharp corners to be fitted.
Thereby, the acute angle corner | angular part in the insertion part of a clip spring can be engage | inserted in the V-shaped groove | channel in the thread valley part of the external thread terminal part inserted in the insertion part of a high voltage terminal. Therefore, the acute corner portion of the fitting portion can be fitted to a position as deep as possible with respect to the V-shaped groove in the thread valley portion of the male screw terminal portion.

  Therefore, according to the ignition coil of the present invention, it is possible to reliably prevent the plug mounting portion from being detached from the spark plug.

A preferred embodiment of the present invention described above will be described.
In the present invention, it is preferable that the fitting portion of the clip spring has a substantially triangular cross-sectional shape including the acute corner portion.
In this case, an acute corner can be easily formed in the fitting portion of the clip spring.

Further, the cutout hole of the insertion portion is formed in a state in which the clip spring is positioned in the axial direction at two locations in the axial direction of the insertion portion, and the insertion portion is formed from the two cutout holes. It is preferable that the interval between the acute corner portions of the fitting portion protruding to the inner periphery is set to an interval that is a multiple of the pitch of the male screw terminal portion.
In this case, it is possible to more stably prevent the plug mounting portion from being detached from the spark plug by using two clip springs.

Embodiments of the ignition coil according to the present invention will be described below with reference to the drawings.
As shown in FIG. 3, the ignition coil 1 of the present example is for connecting a high voltage side winding end portion of the secondary coil 22 to the spark plug 6 in the coil portion 11 including the primary coil 21 and the secondary coil 22. The plug mounting part 12 is connected. The plug mounting portion 12 is provided with a high voltage terminal 4 connected to a high voltage side winding end on the inner peripheral side of a tower portion 31 formed by forming an insulating resin constituting the coil portion 11 into a cylindrical shape. The rubber plug cap 35 for press-fitting the insulator portion 62 of the spark plug 6 is mounted on the outer peripheral side of the tower portion 31.

As shown in FIGS. 1 and 2, the high voltage terminal 4 has a cylindrical insertion portion 41 for inserting a conductive male screw terminal portion 61 formed on the tip side of the insulator portion 62 of the spark plug 6. Have. A clip spring 5 for preventing the male screw terminal portion 61 inserted into the insertion portion 41 from coming off is provided on the outer peripheral portion of the insertion portion 41.
The clip spring 5 has a holding portion 51 held on the outer peripheral portion of the insertion portion 41, and extends from the holding portion 51, and a screw of the male screw terminal portion 61 through a notch hole 411 formed on the outer peripheral portion of the insertion portion 41. And a fitting portion 52 for fitting into the valley portion 611. The fitting portion 52 has an acute corner portion 521 that fits into a V-shaped groove in the thread valley portion 611 of the male screw terminal portion 61 in the cross-sectional shape thereof.
3 shows the periphery of the plug mounting portion 12 in the ignition coil 1, FIG. 1 shows only the connection portion between the high voltage terminal 4 and the spark plug 6, and FIG. The state which attaches the clip spring 5 is shown.

Hereinafter, the ignition coil 1 of this example will be described in detail with reference to FIGS.
As shown in FIG. 3, the ignition coil 1 of this example has a plug mounting portion 12 connected to the lower end side in the axial direction of the coil portion 11, and an ECU (engine control unit) or the like on the upper end side in the axial direction of the coil portion 11. A connector case for electrically connecting to an external device is provided. The ignition coil 1 of this example is a stick type in which the coil portion 11 is disposed in the plug hole 81 provided in the cylinder head 8 and the cylinder head cover of the engine, and the connector case portion is disposed outside the plug hole 81. belongs to.

The coil unit 11 may be configured by arranging the central core 23 on the inner peripheral side of the primary coil 21 and the secondary coil 22 and accommodating the central core 23, the primary coil 21, and the secondary coil 22 in the coil case 3. it can. The primary coil 21 is formed by winding an insulating-coated primary electric wire 212 around the outer periphery of a primary spool 211 made of a resin molded into a cylindrical shape. The secondary coil 22 is wound around the outer periphery of a secondary spool 221 made of a resin molded into a cylindrical shape with a secondary wire 222 having a diameter smaller than that of the primary wire 212 with a greater number of turns than the primary wire 212. Turn. In this example, the secondary coil 22 is disposed on the inner peripheral side of the primary coil 21.
In addition, an insulating sheet for thermal stress relaxation is wound around the outer periphery of the central core 23, and the central core 23 in this example is disposed on the inner peripheral side of the secondary coil 22. The central core 23 can be formed by laminating soft magnetic flat magnetic steel sheets in a direction orthogonal to the axial direction.
Further, an outer peripheral core 24 made of a soft magnetic material is disposed on the outer peripheral side of the coil case 3. The outer peripheral core 24 can be formed by laminating soft magnetic arc-shaped electromagnetic steel plates in the radial direction. The outer peripheral core 24 can also be disposed on the inner peripheral side of the coil case 3.

  Although illustration is omitted, the connector case portion of this example is formed separately from the coil case 3, and the upper end portion in the axial direction of the coil portion 11 is fitted in a fitting hole formed in the connector case portion. . On the outer periphery of the connector case portion, a connector connecting portion for electrically connecting both winding ends of the primary coil 21 to an external device is formed to project radially outward.

As shown in FIG. 3, in the plug mounting portion 12 of this example, the high voltage side winding end of the secondary coil 22 is connected to the axial lower end 223 of the secondary spool 221, and the high voltage terminal 4 A high voltage metal fitting 45 to be conducted is held.
Further, as shown in FIGS. 1 and 2, the high voltage terminal 4 has a conductive fitting hole 451 provided in the high voltage fitting 45 at the axial upper end of the flange portion 40 having the largest outer diameter in the high voltage terminal 4. And a cylindrical insertion portion 41 having an opening hole at the lower end in the axial direction is formed at the lower end in the axial direction of the flange portion 40.

As shown in FIG. 2, the clip spring 5 of this example is formed in a shape in which the holding portion 51 and the fitting portion 52 face each other by bending (forming) a high hardness spring material such as a piano wire. It is. The holding portion 51 of this example is formed in an arc shape along the outer peripheral surface of the cylindrical insertion portion 41. Moreover, the fitting part 52 of this example is bent in a state facing the holding part 51 and formed in a linear shape.
Further, as shown in FIG. 1, the clip spring 5 of the present example performs a bending process on a spring material having a circular cross section, and by pressing or the like, the fitting part 52 is a substantially triangular shape including an acute corner part 521. The cross-sectional shape is processed. The fitting portion 52 having a substantially triangular cross-sectional shape is processed so that the acute corner portion 521 faces the holding portion 51 side.
In addition, the angle of the V-shaped groove of the thread valley portion 611 in the male screw terminal portion 61 of the spark plug 6 was about 60 °, and the angle of the acute corner portion 521 was about 60 °.

As shown in the figure, the cutout holes 411 in the insertion portion 41 of the high voltage terminal 4 are formed in a state where the clip spring 5 is positioned in the axial direction at two locations in the axial direction of the insertion portion 41. The clip spring 5 is attached to the high voltage terminal 4 by inserting the fitting portion 52 into each notch hole 411 and holding the holding portion 51 on the outer peripheral portion of the insertion portion 41.
When the clip is attached to the high voltage terminal 4, the interval between the acute corner portions 521 of the fitting portion 52 that protrudes from the two cutout holes 411 to the inner periphery of the insertion portion 41 is approximately The interval is set to a multiple of the pitch of the screw terminal portion 61. The interval between the acute corner portions 521 can be set to 2 to 6 times the pitch of the male screw terminal portions 61, for example. The interval between the acute corner portions 521 in this example was set to be three times the pitch of the male screw terminal portion 61.

As shown in FIG. 3, the tower portion 31 of this example is extended from the lower end portion in the axial direction of the coil case 3. The tower portion 31 is formed by protruding a locking portion 311 for locking the inner peripheral side of the plug cap 35 on the outer periphery thereof.
The plug cap 35 has a cylindrical shape, a cylindrical hooked portion 351 that is hooked by the locking portion 311 of the tower portion 31, and a press-fit portion 352 that press-fits the lever portion 62 of the spark plug 6. have.

  The spark plug 6 includes a housing portion 63 in which a mounting screw 631 that is screwed into the cylinder head 8 is formed, a male screw terminal portion 61 that is electrically connected to the central shaft portion, and an insulator portion that insulates the central shaft portion from the housing portion 63. 62. And it is comprised so that a spark may be generated between the center electrode 612 which conducted with the center axis | shaft part, and the outer side electrode 632 formed in the housing part 63. FIG. The male screw terminal portion 61 is formed with an M4 screw.

  The gap in the ignition coil 1 is filled with a thermosetting resin (epoxy resin or the like) 15 for insulating and fixing the primary coil 21, the secondary coil 22, the center core 23, and the like. This thermosetting resin 15 is used for each component of the ignition coil 1 (primary coil 21, secondary coil 22, central core 23, outer core 24, coil case 3, high-voltage fitting 45, high-voltage terminal 4, clip spring 5. Etc.), after the gap in the ignition coil 1 is evacuated, the gap in the vacuum state is filled in a liquid state, and then cured.

The ignition operation in the ignition coil 1 can be performed as follows.
That is, in the ignition coil 1, when the primary coil 21 is energized by the operation of the switching control circuit in response to a command from the ECU, a magnetic field that passes through the central core 23 and the outer core 24 is formed. Next, when the energization of the primary coil 21 is interrupted, a voltage is generated in the primary coil 21 by the self-induction action, and a high-voltage induced electromotive force is generated in the secondary coil 22 by the mutual induction action. A spark can be generated between a pair of electrodes in the mounted spark plug 6.

The ignition coil 1 of this example is devised in the shape of the high voltage terminal 4 and the clip spring 5 that constitute the plug mounting portion 12.
Specifically, the clip spring 5 is provided on the outer peripheral portion of the insertion portion 41 of the high voltage terminal 4, and the cross-sectional shape of the fitting portion 52 of the clip spring 5 is changed to the thread valley of the screw terminal portion 61 of the spark plug 6. The portion 611 has a sharp corner 521 that fits into the V-shaped groove.
Accordingly, the acute corner portion 521 of the fitting portion 52 of the clip spring 5 is fitted into the V-shaped groove in the thread valley portion 611 of the male screw terminal portion 61 inserted into the insertion portion 41 of the high voltage terminal 4. be able to. Therefore, the acute corner portion 521 of the fitting portion 52 can be fitted as deep as possible to the V-shaped groove in the thread valley portion 611 of the male screw terminal portion 61.

  Therefore, according to the ignition coil 1 of the present example, the detachment of the plug mounting portion 12 with respect to the spark plug 6 can be reliably prevented.

Sectional explanatory drawing which extracts and shows only the connection part of the high voltage terminal and spark plug in an Example. The perspective view which shows the state which attaches a clip spring to the high voltage terminal in an Example. Cross-sectional explanatory drawing which shows the periphery of the plug mounting part in an ignition coil in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 11 Coil part 12 Plug mounting part 21 Primary coil 22 Secondary coil 3 Coil case 31 Tower part 35 Plug cap 4 High voltage terminal 41 Insertion part 411 Notch hole 45 High voltage metal fitting 5 Clip spring 51 Holding part 52 Insertion part 521 Sharp corner portion 6 Spark plug 61 Male screw terminal portion 611 Screw valley portion 62 Insulator portion

Claims (3)

In the ignition coil formed by connecting a plug mounting portion for connecting a high-voltage side winding end of the secondary coil to a spark plug to a coil portion including a primary coil and a secondary coil,
The plug mounting portion is provided with a high voltage terminal connected to the high voltage side winding end on the inner peripheral side of the tower portion formed by forming the insulating resin forming the coil portion into a cylindrical shape. And a rubber plug cap for press-fitting the insulator portion of the spark plug on the outer peripheral side of the tower portion.
The high-voltage terminal has a cylindrical insertion portion for inserting a conductive male screw terminal portion formed on the tip side of the insulator portion of the spark plug,
A clip spring is provided on the outer periphery of the insertion portion to prevent the male screw terminal portion inserted into the insertion portion from coming off.
The clip spring includes a holding portion to be held on the outer peripheral portion of the insertion portion, and a thread valley portion of the male screw terminal portion through a notch hole formed in the outer peripheral portion of the insertion portion. And a fitting portion for fitting into
An ignition coil characterized in that the fitting portion has an acute corner portion that fits into a V-shaped groove in a thread valley portion of the male screw terminal portion in the cross-sectional shape thereof.   The ignition coil according to claim 1, wherein the fitting portion of the clip spring has a substantially triangular cross-sectional shape including the acute corner portion. In Claim 1 or 2, the notch hole of the insertion part is formed in a state where the axial direction of the clip spring is positioned at two places in the axial direction of the insertion part,
The interval between the acute corners of the fitting portion protruding from the two cutout holes to the inner periphery of the insertion portion is set to a multiple of the pitch of the male screw terminal portion. An ignition coil characterized by that.

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