JP2007250667A - Ignition coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil for effectively preventing occurrence of a crack in epoxy resin at a periphery of a high voltage side winding end in a secondary coil. <P>SOLUTION: The ignition coil 1 has a coil 11 having a primary coil 2 and a secondary coil 3. The secondary coil 3 is wound to a cylindrical secondary spool 31. A high voltage terminal 6 connecting the high voltage side winding end 30 in the secondary coil 3 is fitted to a terminal fitting part 32 formed at an end of one end side in an axial direction D1 in the secondary spool 31. Adhesive resin 71 having higher adhesive strength to the high voltage terminal 6 compared to epoxide resin 15 with which a gap in the coil 11 is filled is arranged between an end face 321 of the one end side in axial direction D1 in the terminal fitting part 32 and the high voltage terminal 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition coil used for generating a spark from a spark plug in an internal combustion engine.

  In an ignition coil used for an internal combustion engine such as an engine, a primary coil formed by winding an electric wire around a primary spool and a secondary coil formed by winding an electric wire around a secondary spool are concentrically overlapped in the radial direction. To place. In addition, a central core made of a magnetic material is arranged on the inner peripheral side of the primary coil and the secondary coil, and an outer peripheral core made of a magnetic material is arranged on the outer peripheral side of the primary coil and the secondary coil. A magnetic path passing through the core is formed. A gap generated in the ignition coil is filled with a thermosetting resin such as an epoxy resin.

  Also, stick-type ignition coils are often used in which the coil portion including the primary coil, the secondary coil, the central core, and the outer core is disposed in the plug hole of the engine. And this ignition coil arrange | positions the high voltage terminal connected with the high voltage side coil | winding edge part of a secondary coil in the edge part of the axial direction one end side of a secondary spool. Then, the terminal portion of the spark plug attached to the plug cap disposed on one end side in the axial direction of the ignition coil is electrically connected to the high voltage terminal via the coil spring, and the high voltage induced electromotive force generated in the secondary coil A spark is generated between a pair of electrodes in the spark plug.

As an ignition coil in which a high voltage terminal is disposed at one end of the secondary spool in the axial direction, for example, there is a stick type ignition coil disclosed in Patent Document 1.
In this ignition coil, the high voltage terminal is formed by drawing a copper alloy disk material, and an epoxy resin is provided between the end surface on the one end side in the axial direction of the secondary spool and the high voltage terminal. Filled.

By the way, when the ignition coil is disposed in the plug hole of the engine and used, it repeats a heating / cooling cycle in which it is heated by receiving combustion from the engine and cooled after combustion. In particular, in the process in which the ignition coil is cooled, there is a possibility that interfacial separation may occur between the high voltage terminal and the epoxy resin due to a difference in coefficient of linear expansion between the high voltage terminal and the epoxy resin. In addition, when an axial load is applied to the ignition coil in response to engine vibration, interfacial delamination is more likely to occur between the high voltage terminal and the epoxy resin.
And when the said interface peeling arises, there exists a possibility that it may progress to the crack (crack) of an epoxy resin from this peeling, and may reach the high voltage side coil | winding edge part in a secondary coil.

  In particular, in an ignition coil equipped with an ion current detection function for detecting whether or not combustion is normally performed by detecting an ion current flowing between a pair of electrodes in a spark plug, the crack of the epoxy resin is high in the secondary coil. When the voltage side winding end is reached, an erroneous determination may occur in the detection of the ionic current.

JP 2005-310846 A

  The present invention has been made in view of such conventional problems, and is an ignition coil that can effectively prevent cracks from occurring in the epoxy resin around the end of the high-voltage side winding in the secondary coil. Is to provide.

According to a first aspect of the present invention, a plug mounting portion for mounting a spark plug is provided on one axial end side of a coil portion including a primary coil and a secondary coil, and a gap in the coil portion is filled with an epoxy resin. In the ignition coil
The secondary coil is wound around a cylindrical secondary spool, and a terminal mounting portion formed at one end of the secondary spool in the axial direction has a high voltage side winding end in the secondary coil. High voltage terminal to connect the part is attached,
Ignition characterized in that an adhesive resin having a higher adhesive strength to the high voltage terminal than the epoxy resin is provided between an end face on one end side in the axial direction of the terminal mounting portion and the high voltage terminal. It exists in a coil (Claim 1).

In the ignition coil of the present invention, a device for preventing the occurrence of interfacial separation between the end surface on the one end side in the axial direction of the terminal mounting portion of the secondary spool and the high voltage terminal mounted on the terminal mounting portion is performed. Yes.
That is, in the ignition coil of the present invention, the adhesive strength with respect to the high voltage terminal is higher than the epoxy resin filling the gap in the coil portion between the end surface on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal. High adhesive resin is provided.

With this adhesive resin, it is possible to firmly join the end face on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal.
As will be described later, when the epoxy resin is filled between the end face on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal, the epoxy resin and the high voltage terminal are firmly bonded by the adhesive resin. Can be joined (adhered).

Therefore, it is effective that the interface peeling occurs between the end face on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal even in the process of cooling the ignition coil in response to the engine heating / cooling cycle. Can be prevented. In addition, even when a vibration load directed in the axial direction is applied to the ignition coil in response to engine vibration, it is effective that the interface peeling occurs between the end surface on one end side in the axial direction of the terminal mounting portion and the high voltage terminal. Can be prevented.
Thereby, it can prevent effectively that the crack of an epoxy resin generate | occur | produces from the interface between the end surface of the axial direction one end side of a terminal attachment part, and a high voltage terminal.
Therefore, according to the ignition coil of the present invention, it is possible to effectively prevent cracks from occurring in the epoxy resin around the high-voltage side winding end of the secondary coil.

According to a second aspect of the present invention, a plug attachment portion for attaching a spark plug is provided on one end side in the axial direction of a coil portion having a primary coil and a secondary coil, and a gap in the coil portion is filled with an epoxy resin. In the ignition coil
The secondary coil is wound around a cylindrical secondary spool, and a terminal mounting portion formed at one end of the secondary spool in the axial direction has a high voltage side winding end in the secondary coil. High voltage terminal to connect the part is attached,
The ignition coil is characterized in that a relaxation layer not filled with the epoxy resin is provided between an end face on one end side in the axial direction of the terminal mounting portion and the high voltage terminal. ).

Also in the ignition coil of the present invention, a device for preventing the occurrence of interfacial separation between the end surface on the one end side in the axial direction of the terminal mounting portion of the secondary spool and the high voltage terminal mounted on the terminal mounting portion is performed. Yes.
That is, in the ignition coil of the present invention, a relaxation layer not filled with epoxy resin is provided between the end face on one end side in the axial direction of the terminal mounting portion and the high voltage terminal.

  Due to the formation of this relaxation layer, the end surface on one end side in the axial direction of the terminal mounting portion and the high voltage terminal are not filled with epoxy resin, and the end surface on one end side in the axial direction of the terminal mounting portion and the high voltage terminal Is in a state of facing through the relaxation layer. That is, the end face on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal are in a state of being isolated in advance by the relaxation layer.

Therefore, there is no interface between the epoxy resin and the high voltage terminal between the end face on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal, and no interface peeling occurs between them.
Thereby, it can prevent effectively that the crack of an epoxy resin generate | occur | produces from the interface between the end surface of the axial direction one end side of a terminal attachment part, and a high voltage terminal.
Therefore, even with the ignition coil of the present invention, it is possible to effectively prevent cracks from occurring in the epoxy resin around the high-voltage side winding end of the secondary coil.

A preferred embodiment in the first and second inventions described above will be described.
In the first and second inventions, the epoxy resin can be cured by heat or light after filling the gap in the coil portion with a liquid resin material. The epoxy resin can be cured by graft polymerization with an epoxy group remaining in the liquid resin raw material.
Moreover, the said high voltage terminal can be comprised with metal materials with high electroconductivity, such as a copper alloy, for example.
Further, the secondary spool including the terminal mounting portion can be made of a thermoplastic resin such as PPE (polyphenylene ether).

In the first aspect of the invention, the gap between the end face on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal is filled with the epoxy resin, and the adhesive resin is composed of the epoxy resin and the Preferably, it is provided between the high voltage terminal (claim 2).
In this case, the adhesive resin can firmly bond the epoxy resin and the high voltage terminal, and cracks are generated in the epoxy resin around the high voltage side winding end of the secondary coil. It can be effectively prevented.

The primary coil is wound around a cylindrical primary spool, the secondary spool is inserted into the primary spool, and the high voltage terminal is one end in the axial direction of the terminal mounting portion of the secondary spool. A cup portion having a bottom portion facing the side end face and an annular side portion erected from the outer periphery of the bottom portion, and the high voltage terminal is mounted on the inner periphery of the side portion. And an annular holding portion formed at the end of one end of the primary spool in the axial direction on the outer periphery of the side portion, and between the secondary spool and the primary spool. It is preferable to hold them (claim 3).
In this case, the high voltage terminal can be stably supported between the secondary spool and the primary spool, and the adhesive resin is provided between the end surface on one end side in the axial direction of the terminal mounting portion and the high voltage terminal. Can be provided stably.

Further, an insertion projecting portion to be inserted into an inner peripheral hole of the terminal mounting portion of the secondary spool is formed on the bottom portion of the high voltage terminal, and an end surface on one end side in the axial direction of the terminal mounting portion, It is preferable to fill the gap between the voltage terminals with the epoxy resin from the gap between the inner peripheral hole and the protruding portion.
In this case, the bonding strength between the terminal mounting portion and the high voltage terminal can be further improved by the epoxy resin filled in the gap between the inner peripheral hole of the terminal mounting portion and the protruding portion of the high voltage terminal.

The adhesive resin is preferably a polyamide resin.
In this case, using the property of polyamide resin formed by bonding a large number of monomers with amide bonds, the bonding strength between the end face on one end side in the axial direction of the terminal mounting portion of the secondary coil and the high voltage terminal is increased. Can be maintained.

In the second invention, it is preferable that the relaxing layer is an air layer.
In this case, the relaxation layer can be easily formed.
Further, the relaxation layer does not necessarily need to be filled with air. For example, rubber, rubber, or a resin foam may be disposed in the space as the relaxation layer.

The primary coil is wound around a cylindrical primary spool, the secondary spool is inserted into the primary spool, and the high voltage terminal is one end in the axial direction of the terminal mounting portion of the secondary spool. The cup has a cup portion formed by a bottom portion facing the side end surface and an annular side portion standing from the outer periphery of the bottom portion, and the bottom portion has a fitting protrusion protruding toward the other end in the axial direction. And the relaxation layer fits the terminal mounting portion on the inner periphery of the side portion of the high voltage terminal, and the axial direction of the primary spool on the outer periphery of the side portion of the high voltage terminal. The annular holding portion formed at the end on one end side is fitted, and the fitting protrusion of the high voltage terminal is fitted into the inner peripheral hole of the terminal mounting portion, thereby forming a sealed state. (Claim 8).
In this case, the relaxation layer can be stably formed in a sealed state.

Further, the ignition coil preferably has an ion current detection function for detecting an ion current flowing between a pair of electrodes in the spark plug after the combustion of the engine.
In this case, in an ignition coil equipped with an ion current detection function, erroneous determination is made in the detection of ion current by preventing cracks in the epoxy resin around the end of the high-voltage side winding in the secondary coil. Can be prevented.

Hereinafter, embodiments of the ignition coil according to the present invention will be described with reference to the drawings.
Example 1
As shown in FIG. 2, the ignition coil 1 of this example is provided with a plug attachment portion 12 for attaching a spark plug 65 to one end D1 in the axial direction of a coil portion 11 provided with a primary coil 2 and a secondary coil 3. In addition, the gap in the coil portion 11 is filled with the epoxy resin 15.
As shown in FIGS. 1 and 2, the secondary coil 3 is wound around a cylindrical secondary spool 31, and the terminal attachment portion 32 formed at the end portion of the secondary spool 31 on one end side D <b> 1 in the axial direction includes The high voltage terminal 6 for connecting the high voltage side winding end 30 in the secondary coil 3 is attached.

In the ignition coil 1 of the present example, the interface peeling occurs between the end surface 321 on the one end side D1 in the axial direction of the terminal attachment portion 32 of the secondary spool 31 and the high voltage terminal 6 attached to the terminal attachment portion 32. We are trying to prevent it from happening.
That is, as shown in FIG. 1, in the ignition coil 1 of this example, there is a gap in the coil portion 11 between the end surface 321 on the one end side D1 in the axial direction of the terminal mounting portion 32 and the high voltage terminal 6. An adhesive resin 71 having a higher adhesive strength to the high voltage terminal 6 than the filled epoxy resin 15 is provided.

Hereinafter, the ignition coil 1 of this example will be described in detail with reference to FIGS.
As shown in FIG. 2, the ignition coil 1 of this example is provided with a connector case portion 13 including a connector portion 52 and a mounting flange portion 53 on the other axial end side D2. The coil part 11 and the connector case part 13 are assembled by fitting the coil part 11 into a fitting hole 51 in the connector case part 13 via a cylindrical fitting member 55.
As shown in FIG. 3, the ignition coil 1 of this example has the coil portion 11 and the plug attachment portion 12 disposed in the plug hole 81 of the engine 8, and the attachment flange portion 53 in the connector case portion 13 is provided in the engine 8. The stick type is configured to be fixed to the periphery of the plug hole 81 via a bolt 535.

As shown in FIG. 2, the connector portion 52 in the connector case portion 13 is a portion that performs electrical connection between the ignition coil 1 and an electronic control unit (ECU) in the engine 8. The mounting flange 53 is a part for fixing the ignition coil 1 to the cylinder head of the engine 8. And the connector part 52 and the attachment flange part 53 are protrudingly formed from the connector case part 13 toward radial direction outward.
An igniter 54 as an electronic component including a power supply circuit and an ion current detection circuit is disposed in the connector case portion 13.

  The ignition coil 1 of this example is equipped with an ion current detection function. This ion current detection function is a function of detecting an ion current generated when ions generated when combustion is performed in the engine 8 flow between the pair of electrodes 651 in the spark plug 65. The ion current detection function is configured by an ion current detection circuit mounted on the igniter 54, and the ion current waveform detected by the ion current detection circuit is processed by an ion current detection processing circuit configured in the ECU. Thus, it is determined whether or not misfire has occurred in the combustion of the engine 8.

As shown in FIG. 2, the primary coil 2 of this example is formed by winding a primary wire coated with insulation around the outer peripheral surface of a primary spool 21 made of a thermoplastic resin having a circular cross section (cylindrical shape). . In the secondary coil 3 of this example, a secondary electric wire having a smaller diameter than the primary electric wire is coated on the outer peripheral surface of a secondary spool 31 made of a thermoplastic resin having a circular ring shape (cylindrical shape). It is wound with a greater number of turns than the wire. The secondary spool 31 in which the secondary coil 3 is formed is inserted and arranged on the inner peripheral side of the primary spool 21 in which the primary coil 2 is formed. Further, the center core 41 is inserted and arranged on the inner peripheral side of the secondary spool 31.
A coil case 43 made of a thermoplastic resin formed in an annular cross section (cylindrical shape) is disposed on the outer peripheral side of the primary coil 2.

A central core 41 made of a magnetic material is arranged on the inner peripheral side of the primary coil 2 and the secondary coil 3, and an outer peripheral core 42 made of a magnetic material is arranged on the outer peripheral side of the primary coil 2 and the secondary coil 3. It is arranged.
The center core 41 of this example is formed in a substantially circular cross section by laminating flat electromagnetic steel plates (silicon steel plates or the like) in the radial direction of the ignition coil 1. The outer peripheral core 42 of this example is formed by laminating electromagnetic steel plates (silicon steel plates or the like) formed in a cylindrical shape along the shape of the outer peripheral surface of the coil case 43. The outer peripheral core 42 of this example is disposed on the outer periphery of the coil case 43.

  As shown in FIG. 1, the high-voltage terminal 6 of this example has a cup shape, and a bottom 61 that faces the end surface 321 of one end D1 in the axial direction of the terminal mounting portion 32 of the secondary spool 31, and the bottom And an annular side portion 62 erected from the outer periphery of 61. Further, an insertion protrusion 611 that is inserted into the inner peripheral hole 322 of the terminal attachment portion 32 of the secondary spool 31 is formed on the bottom 61 of the high voltage terminal 6. Further, the high voltage terminal 6 forms an axial gap 33 for filling the epoxy resin 15 between the bottom 61 thereof and the end surface 321 on the axial end one side D1 of the terminal mounting portion 32 in the secondary spool 31. In this state, it is sandwiched between the secondary spool 31 and the primary spool 21.

A radial gap 34 is formed between the inner peripheral hole 322 in the terminal mounting portion 32 and the insertion protrusion 611 in the high voltage terminal 6. Then, the epoxy resin 15 is filled in the axial gap 33 between the end face 321 on the one end D1 side in the axial direction of the terminal mounting portion 32 and the bottom 61 of the high voltage terminal 6 through the radial gap 34. Yes.
The adhesive resin 71 of this example is applied to the inner surface of the bottom 61, the inner surface of the side portion 62, and the outer surface of the insertion protrusion 611 with respect to the high voltage terminal 6 before being attached to the terminal attachment portion 32. To do.

As shown in FIG. 1, after the high voltage terminal 6 is attached to the terminal attachment portion 32, the adhesive resin 71 of the present example has the side portion 62 of the high voltage terminal 6 in a state where the entire ignition coil 1 is assembled. Are bonded to the epoxy resin 15 and to the bottom 61 of the high voltage terminal 6 and the insertion protrusion 611 and the epoxy resin 15. The adhesive resin 71 also bonds between the tip end side of the side portion 62 of the high voltage terminal 6 and the terminal mounting portion 32.
The high voltage terminal 6 of this example is made of a copper alloy, and the secondary spool 31 including the terminal mounting portion 32 is made of PPE (polyphenylene ether). The adhesive resin 71 is made of a polyamide resin.

Further, as shown in FIG. 4, a positioning projection 621 is formed at the tip of the side portion 62 of the high voltage terminal 6 of this example, and the positioning projection is arranged on the terminal mounting portion 32 of the secondary spool 31 of this example. An engaging portion 323 that engages with 621 is formed. When the high voltage terminal 6 is attached to the terminal attachment portion 32, the positioning protrusion 621 and the engagement portion 323 are engaged, and the end surface 321 of the terminal attachment portion 32 on the one end side D <b> 1 in the axial direction and the high voltage terminal 6 An interval between the bottom portion 61 (an axial interval of the axial gap 33) can be set to a predetermined dimension.
Further, a protrusion 622 is formed at the tip of the side portion 62 of the high voltage terminal 6 for soldering or welding the high voltage side winding end portion 30 of the secondary coil 3 (see FIG. 1). ).

As shown in FIG. 2, the plug attachment portion 12 of this example is configured by attaching a rubber plug cap 64 to a cap attachment portion 22 formed to extend from one axial end side D <b> 1 of the primary spool 21.
As shown in FIGS. 1 and 2, an annular holding portion 23 for fitting the outer periphery of the side portion 62 of the high-voltage terminal 6 is formed at the end portion of the primary spool 21 on the one end side D <b> 1 in the axial direction. . Further, a cap mounting portion 22 for mounting a plug cap 64 described later is formed at the end of the primary spool 21 in the axial direction on the one end side D1, and the holding portion 23 of this example is a cap mounting portion. 22 projecting toward the other axial end D2.
The high voltage terminal 6 is fitted (inserted) with the terminal mounting portion 32 of the secondary spool 31 on the inner periphery of the side portion 62, and the holding portion 23 of the primary spool 21 is fitted with the outer periphery of the side portion 62. The secondary spool 31 and the primary spool 21 are held together.

As shown in FIGS. 1 and 3, a coil spring 63 that contacts the terminal portion 653 of the spark plug 65 is attached to the bottom 61 of the high voltage terminal 6 attached to the terminal attachment portion 32 of the secondary spool 31 in a conductive state. . The high voltage side winding end 30 of the secondary coil 3 is electrically connected to the terminal portion 653 of the spark plug 65 via the high voltage terminal 6 and the coil spring 63.
Further, the spark plug 65 is engaged with a hollow hole formed in the plug cap 64 of the lever portion 652, and the terminal portion 653 formed at the tip of the lever portion 652 is in contact with the coil spring 63, and the cylinder of the engine 8. Fixed to the head.

As shown in FIGS. 1 and 2, there is a thermosetting resin in the gap of the ignition coil 1 surrounded by the connector case portion 13, the fitting member 55, the coil case 43, the mounting base portion and the high voltage terminal 6. The epoxy resin 15 is filled. The epoxy resin 15 includes a gap between the central core 41 and the secondary spool 31, a gap between the secondary coil 3 and the primary spool 21, a gap between the primary coil 2 and the coil case 43, and A gap in the connector case 13 is filled. In addition, the epoxy resin 15 is obtained by filling the ignition coil 1 and then filling and curing the liquid epoxy resin 15 in a gap (space) formed after the assembly.
Further, as shown in FIG. 1, a through hole 324 is formed in the side portion 62 of the terminal mounting portion 32 of the secondary spool 31, and the epoxy resin 15 filled on the inner peripheral side of the secondary spool 31, The epoxy resin 15 filled on the outer peripheral side of the secondary spool 31 is connected by the epoxy resin 15 filled in the through hole 324.

  In the ignition coil 1, when a current is passed through the primary coil 2 by a pulsed spark generation signal from the ECU, a magnetic field passing through the central core 41 and the outer core 42 is formed. Next, when the current flowing through the primary coil 2 is interrupted, an induction magnetic field passing through the central core 41 and the outer core 42 is formed in a direction opposite to the magnetic field formation direction. Then, due to the formation of the induction magnetic field, high voltage induced electromotive force (back electromotive force) is generated in the secondary coil 3, and spark can be generated from the spark plug 65 attached to the plug attachment portion 12 in the ignition coil 1. it can.

In the ignition coil 1 of this example, the adhesive resin 71 can firmly bond the epoxy resin 15 filled in the axial gap 33 and the high voltage terminal 6.
Therefore, it is possible to effectively prevent the occurrence of interface separation between the epoxy resin 15 and the high voltage terminal 6 even in the process of cooling the ignition coil 1 in response to the heating / cooling cycle of the engine 8. Can do. Further, even when a vibration load directed in the axial direction D is applied to the ignition coil 1 due to the vibration of the engine 8, it is possible to effectively prevent the interface peeling between the epoxy resin 15 and the high voltage terminal 6. be able to.

Thereby, it can prevent effectively that the crack of the epoxy resin 15 generate | occur | produces from the interface between the epoxy resin 15 with which the said axial direction gap | interval 33 was filled, and the high voltage terminal 6. FIG.
Therefore, according to the ignition coil 1 of this example, it is possible to effectively prevent cracks from occurring in the epoxy resin 15 around the high-voltage side winding end 30 in the secondary coil 3.

  Further, since the occurrence of this crack can be prevented, the high voltage side winding end portion 30 is not damaged by the crack. Therefore, when a weak ionic current flows after combustion of the engine 8 through the cylinder head of the engine 8, between the pair of electrodes 651 in the spark plug 65, the coil spring 63, the high voltage terminal 6, the secondary coil 3, etc. It is possible to prevent an adverse effect on the flow of the weak ion current. Thereby, it can prevent that a misjudgment arises in the detection of ion current.

  Moreover, in this example, the effect at the time of providing the adhesive resin 71 between the said epoxy resin 15 and the high voltage terminal 6 was confirmed by simulation of the computer. In this confirmation, it was found that the distortion generated in the epoxy resin 15 adjacent to the vicinity of the tip of the side portion 62 of the high voltage terminal 6 can be reduced by about 71% compared to the case where the adhesive resin 71 is not provided. Thereby, according to the ignition coil 1 of this example, it turned out that it is hard to produce a crack in the epoxy resin 15 of the periphery of the high voltage side coil | winding edge part 30 in the secondary coil 3. FIG.

(Example 2)
As shown in FIG. 5, the ignition coil 1 of this example has the above epoxy resin instead of providing the adhesive resin 71 between the end face 321 on the one end side D <b> 1 in the axial direction of the terminal mounting portion 32 and the high voltage terminal 6. A relaxation layer 72 not filled with the resin 15 is provided.
The relaxation layer 72 of the present example is an air layer 72 made of air filled in the axial gap 33 between the end surface 321 on the one end side D1 in the axial direction of the terminal mounting portion 32 and the high voltage terminal 6.

A fitting protrusion 612 that protrudes toward the other end D2 in the axial direction is formed on the bottom 61 of the high voltage terminal 6 of this example. The fitting protrusion 612 is formed to have an outer diameter that is fitted into the inner peripheral hole 322 in the terminal mounting portion 32 of the secondary spool 31.
The relaxation layer (air layer) 72 of this example is configured such that when the high voltage terminal 6 is attached to the terminal attachment portion 32 of the secondary spool 31 with the axial clearance 33 formed, the axial clearance 33 is attached to the terminal attachment portion 32. It is formed by forming a sealed space by the portion 32 and the high voltage terminal 6. The sealed space is fitted (inserted) into the inner periphery of the side portion 62 of the high voltage terminal 6 and the primary spool is placed on the outer periphery of the side portion 62 of the high voltage terminal 6. 21, and the fitting protrusion 612 of the high voltage terminal 6 is fitted into the inner peripheral hole 322 of the terminal mounting portion 32.

  In the ignition coil 1 of this example, the epoxy resin 15 is not filled between the end surface 321 on the one end side D1 in the axial direction of the terminal mounting portion 32 and the high voltage terminal 6 due to the formation of the relaxation layer 72. The end face 321 on the one end side D1 in the axial direction of the terminal mounting portion 32 and the high voltage terminal 6 are in a state of facing each other with the relaxing layer 72 interposed therebetween. That is, the end face 321 on the one end side D1 in the axial direction of the terminal mounting portion 32 and the high voltage terminal 6 are in a state of being isolated in advance by the relaxing layer 72.

Therefore, there is no interface between the epoxy resin 15 and the high voltage terminal 6 between the end surface 321 on the one end side D1 in the axial direction of the terminal mounting portion 32 and the high voltage terminal 6, and there is interface peeling between them. It does not occur.
Thereby, it can prevent effectively that the crack of the epoxy resin 15 generate | occur | produces from the interface between the end surface 321 of the axial direction one end side D1 of the terminal attachment part 32, and the high voltage terminal 6.
Therefore, even with the ignition coil 1 of this example, it is possible to effectively prevent cracks from occurring in the epoxy resin 15 around the high-voltage side winding end 30 in the secondary coil 3.

Further, as shown in FIG. 5, also in the ignition coil 1 of this example, the adhesive resin 71 shown in Example 1 is provided between the terminal mounting portion 32 and the side portion 62 of the high voltage cup 6. Can do. In this case, when attaching the high voltage terminal 6 to the terminal attachment portion 32, the high voltage terminal 6 can be adhered to the terminal attachment portion 32 by the adhesive resin 71.
Also in this example, the other configuration of the ignition coil 1 is the same as that of the first embodiment, and the same effects as those of the first embodiment can be obtained.

  Also in this example, the effect of providing a relaxation layer (air layer) 72 between the terminal mounting portion 32 and the high voltage terminal 6 was confirmed by computer simulation. In this confirmation, it was found that the distortion generated in the epoxy resin 15 adjacent to the vicinity of the tip of the side portion 62 of the high voltage terminal 6 can be reduced by about 43% compared to the case where the relaxing layer 72 is not provided. Thus, it was found that cracks could hardly occur in the epoxy resin 15 around the high-voltage side winding end portion 30 of the secondary coil 3 even with the ignition coil 1 of this example.

Sectional explanatory drawing which shows the periphery of the high voltage terminal in an ignition coil in Example 1. FIG. Sectional explanatory drawing which shows the ignition coil in Example 1. FIG. Sectional explanatory drawing which shows the ignition coil in the state attached to the engine in Example 1. FIG. FIG. 3 is a perspective explanatory view showing a high voltage terminal in the first embodiment. Sectional explanatory drawing which shows the periphery of the high voltage terminal in an ignition coil in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 11 Coil part 12 Plug attachment part 13 Connector case part 15 Epoxy resin 2 Primary coil 21 Primary spool 22 Cap attachment part 23 Holding part 3 Secondary coil 30 High voltage side coil end part 31 Secondary spool 32 Terminal attachment part 321 End face 33 Axial clearance 41 Central core 42 Outer core 43 Coil case 6 High voltage terminal 61 Bottom 611 Insertion protrusion 612 Insertion protrusion 62 Side part 63 Coil spring 64 Plug cap 65 Spark plug 71 Adhesive resin 72 Relaxation layer (Air layer) )
D1 Axial one end side D2 Axial other end side

Claims (9)

In the ignition coil formed by providing a plug mounting portion for mounting a spark plug on one end side in the axial direction of a coil portion including a primary coil and a secondary coil, and filling a gap in the coil portion with an epoxy resin,
The secondary coil is wound around a cylindrical secondary spool, and a terminal mounting portion formed at one end of the secondary spool in the axial direction has a high voltage side winding end in the secondary coil. High voltage terminal to connect the part is attached,
Ignition characterized in that an adhesive resin having a higher adhesive strength to the high voltage terminal than the epoxy resin is provided between an end face on one end side in the axial direction of the terminal mounting portion and the high voltage terminal. coil. In claim 1, the epoxy resin is filled in the gap between the end surface on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal,
The ignition coil, wherein the adhesive resin is provided between the epoxy resin and the high voltage terminal. In Claim 1 or 2, the primary coil is wound around a cylindrical primary spool, the secondary spool is inserted into the primary spool,
The high voltage terminal has a cup shape with a bottom portion facing an end surface on one end side in the axial direction of the terminal mounting portion in the secondary spool, and an annular side portion erected from the outer periphery of the bottom portion. ,
And the said high voltage terminal is the annular | circular shaped holding | maintenance part formed in the edge part of the axial direction one end side of the said primary spool in the outer periphery of the said side part while fitting the said terminal attachment part to the inner periphery of the said side part. And an ignition coil that is sandwiched between the secondary spool and the primary spool. In Claim 3, the bottom of the high-voltage terminal is formed with an insertion protrusion to be inserted into an inner peripheral hole in the terminal mounting portion of the secondary spool.
The gap between the end face on the one end side in the axial direction of the terminal mounting portion and the high voltage terminal is filled with the epoxy resin from the gap between the inner peripheral hole and the protruding portion. Ignition coil.   The ignition coil according to claim 1, wherein the adhesive resin is a polyamide-based resin. In the ignition coil formed by providing a plug mounting portion for mounting a spark plug on one end side in the axial direction of a coil portion including a primary coil and a secondary coil, and filling a gap in the coil portion with an epoxy resin,
The secondary coil is wound around a cylindrical secondary spool, and a terminal mounting portion formed at one end of the secondary spool in the axial direction has a high voltage side winding end in the secondary coil. High voltage terminal to connect the part is attached,
An ignition coil characterized in that a relaxation layer not filled with the epoxy resin is provided between an end face on one end side in the axial direction of the terminal mounting portion and the high voltage terminal.   The ignition coil according to claim 6, wherein the relaxation layer is an air layer. In Claim 6 or 7, the primary coil is wound around a cylindrical primary spool, and the secondary spool is inserted into the primary spool.
The high voltage terminal has a cup shape with a bottom portion facing an end surface on one end side in the axial direction of the terminal mounting portion in the secondary spool, and an annular side portion erected from the outer periphery of the bottom portion. In the bottom portion, an insertion protrusion that protrudes toward the other end in the axial direction is formed,
The relaxation layer fits the terminal mounting portion on the inner periphery of the side portion of the high-voltage terminal, and on the outer periphery of the side portion of the high-voltage terminal on the end on one axial end side of the primary spool. The annular holding part formed in the part is fitted, and the fitting protrusion of the high voltage terminal is fitted into the inner peripheral hole in the terminal mounting part, thereby forming a sealed state. Features an ignition coil.   The ignition coil according to any one of claims 1 to 8, wherein the ignition coil has an ion current detection function of detecting an ion current flowing between a pair of electrodes in the spark plug after combustion of the engine. Ignition coil to play.

Images