JP2013239633A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for an internal combustion engine, having an iron core, a first coil and a second coil inside a case, and fixed and insulated by a thermosetting mold resin, the ignition coil solving the problem in which the ignition coil is heated to a high temperature during operation to cause thermal expansion of an outer peripheral iron core, resulting in peeling and cracking in the mold resin.SOLUTION: In an ignition coil for an internal combustion engine, an outer peripheral iron core 40 is arranged so that a magnetic path of an iron core is in a direction perpendicular to a case opening surface 70a, and a parallel coil part 42 of the outer peripheral iron core 40 is partially exposed from a resin surface 92. The periphery of the outer peripheral iron core 40 is covered with a first cover 60 which is peeled from a mold resin 90. The first cover 60 forms a first cover opening 66 in a surface on an opposite side to a second coil opposite part 62. Furthermore, the periphery of the first cover 60 includes a second cover 50, and an exposed part 42a of the outer peripheral iron core 40 is directly covered with the second cover 50 which adheres to the mold resin 90 by the first cover opening 66.

Description

The present invention relates to an ignition coil for an internal combustion engine.

Conventionally, an ignition coil for an internal combustion engine that has an iron core, a primary coil, and a secondary coil in a case, and is fixed and insulated by a thermosetting mold resin, when the operation is at a high temperature and when left at a stop Due to the low-temperature thermal stress, peeling or cracking may occur in the mold resin due to thermal expansion of the outer peripheral iron core.

In order to solve such problems, it is proposed that the cover arranged around the outer peripheral iron core is composed of a core cover made of a material that peels away from the insulating resin, contrary to a core cover made of a material that adheres to the insulating resin. For example, Japanese Patent No. 3900169 (hereinafter referred to as “Patent Document 1”) has been proposed.

FIG. 6 shows a top sectional view of the ignition coil described in Patent Document 1. In FIG. 6, in Patent Document 1, a transformer composed of a primary coil 10, a secondary coil 20, and a center core 30 disposed inside the primary coil 10, and a center disposed outside the secondary coil 20. Side core 40 for returning magnetic flux generated in the core 30, covers 200a and 200b arranged around the side core 40, a case 70 for storing these components, and an insulating resin for fixing the components in the case 70 The cover 200a, 200b includes two types of covers, a first core cover 200a made of a material that is in close contact with the insulating resin 90 and a second core cover 200b made of a material that is peeled off from the insulating resin 90. It is composed of at least three layers of insulating resin 90, first core cover 200a, and second core cover 200b between the side core 40 and the transformer, and the second core cover 200b is disposed on the side core 40 side. And transformer And the first core cover 200a disposed.

Japanese Patent No. 3900139

However, the conventional ignition coil has the following problems. That is, in the ignition coil of Patent Document 1, since the cover is composed of a core cover made of a material that peels away from the insulating resin, contrary to a core cover made of a material that is in close contact with the insulating resin, a buffering action by a portion that easily peels off from the insulating resin Therefore, it is possible to prevent the insulation resin from peeling and cracking at the necessary parts, and to reduce distortion to the parts. However, the insulation resin between the core cover of the material to be separated from the insulation resin and the outer core (side core) There arises a problem that cracks generated by the edge of the outer peripheral iron core (side core) spread to the case opening surface. Further, there also arises a problem that water droplets or the like enter the ignition coil from the crack that reaches the surface of the case opening.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a small ignition coil that can prevent cracks generated from the edge of an outer peripheral iron core and can be accommodated in a limited space in an engine room. .

In order to solve the above problems, the present invention is configured as follows. That is, an iron core composed of a central iron core and an outer peripheral iron core, a primary coil in which a primary winding is wound around a primary bobbin, a secondary coil in which a secondary winding is wound around a secondary bobbin, In an ignition coil for an internal combustion engine comprising a case that houses an iron core, a primary coil, and a secondary coil, and a mold resin that fills the case, the outer peripheral iron core has a magnetic path of the iron core that is A first cover that is disposed in a direction perpendicular to the opening surface of the case and that is separated from the mold resin on an outer periphery of at least a part of a surface and a side surface facing the secondary coil; Is characterized in that at least part of the periphery is covered with a second cover that adheres to the mold resin, and the second cover has a second cover protrusion protruding from the resin surface of the mold resin. Ignition coil for internal combustion engine That.

In the above configuration, the first cover is formed with a first cover opening that exposes the exposed portion of the outer peripheral iron core parallel to the case opening surface, and the outer peripheral iron core exposed portion is the second cover. It is good also as a structure covered only by the cover. Further, the first cover may be formed from an elastic member, and the second cover may be fitted and fixed to the first cover. Further, the first cover may be disposed at a corner of the outer peripheral iron core, and the first cover is disposed on a surface perpendicular to the case opening surface of the outer peripheral iron core. Also good.

Further, at least a part of the outer peripheral iron core may protrude from the resin surface, and the second cover may cover the outer peripheral iron core exposed portion. Further, the second cover may be molded from PBT (polybutylene terephthalate) or PET (polyethylene terephthalate), and the first cover 60 may be molded from elastomer or silicon.

As described above, the outer peripheral iron core is arranged such that the magnetic path of the iron core is arranged in a direction perpendicular to the opening surface of the case, and the mold resin is disposed on the outer periphery of at least a part of the surface and side surface facing the secondary coil. The first cover is peeled off, and the first cover is covered with a second cover at least a part of the periphery of which is bonded to the mold resin, and the second cover has a second cover protruding portion as the mold resin. By projecting from the resin surface, it is possible to realize a small ignition coil which can prevent cracks generated from the outer peripheral iron core and can be accommodated in a limited space in the engine room.

The first cover is formed with a first cover opening that exposes the exposed portion of the outer peripheral iron core parallel to the case opening surface, and the outer peripheral iron core exposed portion is covered only by the second cover. By doing so, since the height dimension of the iron core is suppressed only to the thickness of the second cover, the height dimension of the ignition coil can be suppressed and the size can be reduced.

1 is a perspective view of an ignition coil for an internal combustion engine according to a first embodiment of the present invention. It is BB sectional drawing seen from the arrow (A) direction of FIG. It is a perspective view showing the assembly of the outer periphery iron core which is a 1st Example. It is a perspective view of the iron core assembly which becomes a 1st Example. It is side surface sectional drawing of the iron core assembly made into a 1st Example. It is an upper surface sectional view of an ignition coil made into patent documents 1.

Hereinafter, examples showing embodiments of the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view of an ignition coil for an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line BB of FIG. FIG. 3 is a perspective view, FIG. 4 is a perspective view of the iron core assembly, and FIG. 5 is a side sectional view of the iron core assembly.

1 and 2, the case 70 forming the outer shape of the ignition coil 100 is formed in a box shape having an opening surface 70a formed on the upper surface in the vertical direction made of an insulating resin. Further, the case 70 is formed with a substantially triangular prism-like flange 72 for attaching and fixing the ignition coil 100 to the engine block.

The ignition coil 100 includes an iron core having a closed magnetic circuit structure by combining an I-shaped central iron core 30 formed by laminating about 30 silicon steel plates and a U-shaped outer iron core 40; A primary coil 10 in which a primary winding is wound about 100 turns on the outer periphery of a primary bobbin formed of resin on the outer periphery of the central iron core 30, and a secondary bobbin formed of resin on the outer periphery of the primary coil 10 It comprises a coil portion of a secondary coil 20 in which a secondary winding is wound about 8000 to 15000 turns on the outer periphery. Further, the central iron core 30 and the outer peripheral iron core 40 are laminated with the silicon steel plates in a direction parallel to the case opening surface 70a.

The outer peripheral iron core 40 is arranged so that the magnetic path of the iron core is perpendicular to the case opening surface 70a. Further, a magnet 32 for generating a magnetic flux in a direction opposite to the magnetic flux generated in the primary coil 10 in one of the connecting surfaces of the central iron core 30 and the outer peripheral iron core 40 is provided.

Further, a high voltage tower 74 is formed on the outer bottom surface of the case 70 so as to project into a plug hole formed in the upper part of the engine. The high voltage tower 74 receives a secondary voltage output from the secondary coil 20. A high voltage terminal 76 is provided for supplying the spark plug.

A secondary high voltage terminal 22 for supplying a secondary voltage to the high voltage terminal 76 is provided at one end of the secondary coil 20. Further, a secondary low voltage terminal (not shown) for receiving a primary voltage from the primary coil 10 is provided at the other end of the secondary coil 20.

The case 70 is provided with a switching element for supplying an ignition signal to the primary coil 10 and an igniter 82 made of an insulating resin molded lead frame. Further, the lead frame has a function as an igniter terminal 84 for connecting each of the base, collector, and emitter of the switching element to the outside.

Further, a connector 78 is formed on the side surface of the case 70, and the connector 78 is insert-molded with a connector terminal 80 for electrical connection with the battery, ECU, the iron core, and the igniter 82. . Further, the connector terminal 80 includes a terminal connecting the low voltage side of the primary coil 10 and the secondary coil 20 from the battery, and a terminal connecting the igniter terminal 84 disposed on the base side of the igniter 82 from the ECU. The igniter 82 is arranged on the emitter side of the igniter terminal 84 and the terminal connecting the iron core to the ground.

The connector terminal 80 and the igniter terminal 84 are substantially flat metal terminals, the connector terminal 80 and the igniter terminal 84 are led out in a direction perpendicular to the case opening surface 70a, and the connector terminal 80 is connected to the case. It is disposed along the inner wall of the case 70 on the same plane as the connector 78 formed on the 70. Further, two of the connector terminal 80 and the igniter terminal 84 are led out in the same direction, and are connected by welding so as to realize electrical conduction between the two.

The case 70 is filled with the mold resin 90 that realizes electrical insulation of the ignition coil 100 and physical fixation of each member. Further, the mold resin 90 is filled up to the vicinity of the case opening surface 70a, and the central iron core 30, the primary coil 10, the secondary coil 20, and the igniter 82 are formed in the vicinity of the case opening surface 70a. A part of the coil parallel part 42 of the outer peripheral iron core 40 is exposed at a position higher than the resin surface 92.

In addition, the periphery of the outer peripheral iron core 40 is provided with a first cover 60 formed of an elastomer made of a material that peels off from the mold resin 90. Further, the first cover 60 includes a secondary coil facing portion 62 on a surface 44 that is perpendicular to the case opening surface 70 a of the outer peripheral iron core 40 and a surface 46 that faces the secondary coil 20.

Further, the periphery of the first cover 60 is provided with a second cover 50 formed of PBT (polybutylene terephthalate) made of a material that adheres to the mold resin 90. Further, the second cover 50 includes a second cover protrusion 50 a at a position higher than the resin surface 92.

3 to 5, the first cover 60 has a first cover opening 66 formed on the surface opposite to the secondary coil facing portion 62, and the exposed portion 42a of the outer peripheral iron core 40 has the first cover 60a. The first cover opening 66 directly covers the second cover 50. The first cover 60 covers the periphery of the outer peripheral iron core 40 except for the connection surface between the central iron core 30 and the magnet 32 and the first cover opening 66. Further, the second cover 50 is disposed so as to cover the first cover side face portion 64 and the first cover opening 66, and is fitted and fixed to the first cover 60.

Further, a second cover protrusion 52 is formed on the side surface portion 54 of the second cover 50 so as to be fixed in pressure contact with the inner wall of the case 70 when the coil portion is stowed in the case 70. Yes. Further, the second cover side surface portion 54 is formed at a position lower than the resin surface 92.

With the above configuration, the periphery of the outer peripheral iron core 40 includes the first cover 60, and the first cover 60 has a connection surface between the outer peripheral iron core 40 and the central iron core 30 and the magnet 32, and the The periphery except for the first cover opening 66 is covered. Thereby, since the said outer periphery iron core 40 has peeled from the said mold resin 90, it can prevent the crack generation by the expansion | swelling by the high temperature at the time of ignition coil operation | movement, and the shrinkage | contraction by the low temperature at the time of standing at the time of a stop. Further, since the silicon steel sheet is laminated in a direction perpendicular to the case opening surface 70a in the outer peripheral iron core 40, cracks in the direction of the case opening surface 70a are likely to occur. Generation of cracks in the resin surface 92 can be prevented by separating the laminated surface from the mold resin 90.

The first cover opening 66 is formed such that the height H of the iron core does not include the thickness of the first cover 60, and the exposed portion of the outer iron core 40 is formed. 42a is directly covered by the second cover 50 by the first cover opening 66, so that the height dimension H (shown in FIG. 5) of the iron core is the thickness Ch (see FIG. 5) of the second cover 50. 5), the height of the ignition coil 100 can be suppressed and the size can be reduced.

Further, the outer peripheral iron core 40 is disposed so that the magnetic path of the iron core is perpendicular to the case opening surface 70a, and a part of the coil parallel part 42 of the outer peripheral iron core 40 is formed from the resin surface 92. In addition to being exposed at a high position, the periphery of the first cover 60 is provided with the second cover 50, and the exposed portion 42 a of the outer peripheral iron core 40 is formed by the first cover opening 66 to the second. Directly covered by the cover 50. Thereby, the exposed portion 42a of the outer peripheral iron core 40 can be protected from the external environment.

As a modification of the first embodiment, the shapes of the central iron core 30 and the outer peripheral iron core 40 and the number of laminated silicon steel plates may be appropriately changed according to design circumstances, or the primary coil 10 and the secondary coil. The number of windings wound around the coil 20 may be arbitrarily changed according to design circumstances such as an output required for the ignition coil 100. Further, the first cover 60 may be molded using a material other than an elastomer such as silicon as long as it has elasticity and a property of peeling off from the mold resin 90. Further, the second cover 50 may be molded using a material other than PBT such as PET ((polyethylene terephthalate)) as long as it has a property of adhering to the mold resin 90.

The first cover 60 may be disposed at a position covering at least a part of the secondary coil facing surface 46 and the outer peripheral iron core side surface 44 of the outer peripheral iron core 40, or the first cover 60. May be arranged at a position covering only the corner of the outer peripheral iron core 40. Furthermore, as long as the second cover 50 is disposed at least on the exposed portion 42a of the outer peripheral iron core 40, other configurations may be arbitrarily changed depending on design circumstances.

Further, the ignition coil 100 may be changed to any shape according to design circumstances as long as at least the second cover protrusion 50a of the second cover 50 protrudes from the resin surface 92. . Further, the second cover 50 and the first cover 60 may be fixed using, for example, an adhesive or the like other than fitting.

Further, the first cover opening 66 may be changed to an arbitrary shape depending on design circumstances as long as the height of the iron core is prevented from increasing due to the thickness of the first cover 60. .

10: 1 primary coil
20: Secondary coil
22: Secondary high-voltage terminal
30: Central iron core
32: Magnet
40: Outer iron core
42: Coil parallel part
42a: Peripheral iron core exposed part
44: Outer iron core side
46: Secondary coil facing surface
50: Second cover
50a: second cover protrusion
52: Second cover protrusion
54: Second cover side surface
60: First cover
62: Secondary coil facing part
64: First cover side surface
66: First cover opening
70: Case
70a: Case opening surface
72: Flange
74: High pressure tower
76: High voltage terminal
78: Connector
80: Connector terminal
82: Igniter
84: Igniter terminal
90: Mold resin
92: Resin surface
100: Ignition coil

Claims (7)

An iron core comprising a central iron core 30 and an outer iron core 40; a primary coil 10 in which a primary winding is wound around a primary bobbin; and a secondary coil 20 in which a secondary winding is wound around a secondary bobbin; In an ignition coil 100 for an internal combustion engine, comprising: a case 70 having an opening that accommodates the iron core and the primary coil 10 and the secondary coil 20;
The outer iron core 40 has a magnetic path of the iron core arranged in a direction perpendicular to the case opening surface 70a, a secondary coil facing surface 46 facing the secondary coil 20, and an outer iron core side surface 44. A first cover 60 that peels from the mold resin 90 on at least a part of the outer periphery of
The first cover 60 is covered with a second cover 50 that is at least partially adhered to the mold resin 90;
The ignition coil 100 for an internal combustion engine, wherein the second cover 50 has a second cover protrusion 50a protruding from a resin surface 92 of the mold resin 90. The first cover 60 is formed with a first cover opening 66 that exposes the outer peripheral iron core exposed portion 42a of the outer peripheral iron core 40 parallel to the case opening surface 70a.
2. The ignition coil 100 for an internal combustion engine according to claim 1, wherein the outer peripheral iron core exposed portion 42 a is covered only by the second cover 50. The first cover 60 is formed from an elastic member,
The ignition coil 100 for an internal combustion engine according to claim 1 or 2, wherein the second cover 50 is fitted and fixed to the first cover 60. 4. The ignition coil 100 for an internal combustion engine according to claim 1, wherein the first cover 60 is disposed at a corner of the outer peripheral iron core 40. 5. The internal combustion engine according to claim 1, wherein the first cover 60 is disposed on a surface perpendicular to the case opening surface 70 a of the outer peripheral iron core 40. Ignition coil 100. At least a part of the outer peripheral iron core 40 protrudes from the resin surface 92,
The ignition coil 100 for an internal combustion engine according to any one of claims 1 to 5, wherein the second cover 50 covers the outer peripheral iron core exposed portion 42a. The second cover 50 is molded from PBT (polybutylene terephthalate) or PET (polyethylene terephthalate),
The ignition coil 100 for an internal combustion engine according to any one of claims 1 to 6, wherein the first cover 60 is formed of an elastomer or silicon.

Images