JP2020188041A - Ignition-coil for internal combustion engine - Google Patents

Abstract

To provide an ignition-coil for internal combustion engine capable of preventing breakdown of a magnet body during assembly.SOLUTION: An ignition-coil 1 for an internal combustion engine has a primary coil 5 and a secondary coil 6 magnetically coupled with each other, a center core 2, an outer peripheral core 3, and a magnet body 4. The center core 2 is formed by laminating multiple magnetic steel plates, and placed on the inside of the primary coil 5 and the secondary coil 6. The outer peripheral core 3 forms a magnetic circuit orthogonal to the lamination direction of the magnetic steel plates, together with the center core 2, and placed on the outside of the primary coil 5 and the secondary coil 6. The magnet body 4 is placed between the center core 2 and the outer peripheral core 3 in the magnetic circuit. At a part of a center side opposite face 212 facing the magnet body 4 in the center core 2, a groove 211 is formed entirely in the lamination direction of the magnetic steel plates. The center side opposite face 212 is covered with coating resin 213.SELECTED DRAWING: Figure 1

Description

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

Some ignition coils for internal combustion engines form a magnetic circuit and have a central core and an outer peripheral core formed by laminating a plurality of plate-shaped magnetic steel plates. Then, there is an ignition coil in which a magnet body that gives a magnetic flux in the opposite direction to the magnetic flux generated in the magnetic circuit by energizing the primary coil is arranged between the central core and the outer peripheral core in the magnetic circuit. As a result, the amount of change in the magnetic flux when the energization of the primary coil is cut off becomes large, and the input energy increases, thereby increasing the voltage induced in the secondary coil.

However, disposing a thin magnet body between the central core and the outer peripheral core in a state where the central core and the outer peripheral core are assembled may cause damage to the magnet body.

Therefore, the ignition coil described in Patent Document 1 is intended to be easily arranged and to prevent damage to the magnet body by forming the tip of the plate-shaped magnet body into a tapered shape.

Japanese Unexamined Patent Publication No. 2000-331853

However, the ignition coil described in Patent Document 1 has the following problems.
Even if the magnet body has a tapered surface, it may be caught in a step between magnetic steel plates on the end surface of the central core. Then, in the end, it is not always possible to prevent damage such as chipping or cracking of the magnet body at the time of assembling the magnet body.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an ignition coil for an internal combustion engine capable of preventing damage to a magnet body during assembly.

One aspect of the present invention includes a primary coil (5) and a secondary coil (6) that are magnetically coupled to each other.
A central core (2) formed by laminating a plurality of magnetic steel plates (13) and inserted and arranged inside the primary coil and the secondary coil.
A magnetic circuit orthogonal to the stacking direction of the magnetic steel plate is formed together with the central core, and the outer peripheral core (3) arranged outside the primary coil and the secondary coil is formed.
It has a magnet body (4) arranged between the central core and the outer peripheral core in the magnetic circuit.
A groove portion (211) over the entire stacking direction of the magnetic steel plate is formed in a part of the center side facing surface (212) which is a surface facing the magnet body in the center core, and the center side facing surface is formed. Is in the ignition coil (1) for an internal combustion engine, which is covered with a coating resin (213).

In the ignition coil for an internal combustion engine, the facing surface on the center side is covered with a coating resin. Therefore, it is possible to prevent the step caused by the edge of the magnetic steel plate from being exposed to the magnet body side on the facing surface on the center side.

Further, a groove portion is formed in a part of the center-side facing surface of the central core facing the magnet body. Therefore, in the manufacturing process of the ignition coil, the resin can be supplied to the facing surface on the center side through this groove. Therefore, it is possible to easily obtain a configuration in which the central facing surface is covered with the coating resin. As a result, damage to the magnet body during assembly can be prevented.

As described above, according to the above aspect, it is possible to provide an ignition coil for an internal combustion engine that can prevent damage to the magnet body during assembly.
The reference numerals in parentheses described in the scope of claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. It's not a thing.

The cross-sectional view of the ignition coil for the internal combustion engine in Embodiment 1. FIG. FIG. 1 is a cross-sectional view taken along the line II-II in FIG. Cross-sectional view of the unit in which the central core and the outer peripheral core are assembled, before assembling the magnet body. Cross-sectional view of the unit in which the central core and the outer peripheral core are assembled, after the magnet body is assembled. The plan view of the central core seen from the Z direction in Embodiment 1. The plan view of the central core seen from the front side in the X direction in Embodiment 1. FIG. 5 is a cross-sectional view of a mold for insert molding a primary spool together with a central core in the first embodiment as viewed from the Y direction. FIG. 7 is a cross-sectional view taken along the line VIII-VIII in FIG. FIG. 8 is a cross-sectional view taken along the line IX-IX in FIG. FIG. 7 is an enlarged cross-sectional view of the vicinity of the facing surface on the center side. The plan view of the primary spool seen from the Y direction in Embodiment 1. The plan view of the primary spool seen from the X direction in Embodiment 1. FIG. 11 is a cross-sectional view taken along the line XIII-XIII. FIG. 1 is an enlarged cross-sectional view of a central core whose central facing surface is not covered with a coating resin in the first embodiment near a groove. FIG. 1 is an enlarged cross-sectional view of a central core whose central facing surface is covered with a coating resin in the first embodiment in the vicinity of a groove.

(Embodiment 1)
An embodiment relating to the ignition coil 1 for an internal combustion engine will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the ignition coil 1 for an internal combustion engine in the present embodiment includes a primary coil 5 and a secondary coil 6 magnetically coupled to each other, a central core 2, an outer peripheral core 3, and a magnet body 4. Have. The central core 2 is formed by laminating a plurality of magnetic steel plates 13. Further, the central core 2 is inserted and arranged inside the primary coil 5 and the secondary coil 6. The outer peripheral core 3 forms a magnetic circuit orthogonal to the stacking direction of the magnetic steel plates 13 together with the central core 2. Further, the outer peripheral core 3 is arranged outside the primary coil 5 and the secondary coil 6. The magnet body 4 is arranged between the central core 2 and the outer peripheral core 3 in the magnetic circuit. As shown in FIG. 6, a groove portion 211 over the entire stacking direction of the magnetic steel plate 13 is formed on a part of the central side facing surface 212 which is a surface facing the magnet body 4 in the central core 2. The central facing surface 212 is covered with the coating resin 213.

As shown in FIGS. 1 and 2, a primary spool 51 in which the primary coil 5 is wound around the outer peripheral surface is provided on the outer peripheral surface of the central core 2. As shown in FIG. 12, the coating resin 213 is integrally formed with the primary spool 51.

The primary coil 5 is formed by winding the primary winding around the outer peripheral surface of the primary spool 51. The secondary coil 6 is formed by winding a secondary winding around the outer peripheral surface of the secondary spool 61. The winding shaft of the secondary coil 6 is coaxial with the winding shaft of the primary coil 5. Further, the primary coil 5 is arranged on the outer peripheral side of the central core 2. The secondary coil 6 is arranged on the outer peripheral side of the primary coil 5. The winding shafts of the primary coil 5 and the secondary coil 6 and the central shaft C of the central core 2 are coaxial with each other. The axial direction, which is the direction parallel to the central axis C of the central core 2, is also appropriately referred to as the X direction. Further, the direction in which the plurality of magnetic steel plates 13 constituting the central core 2 are laminated and orthogonal to the X direction is also appropriately referred to as the Z direction. Further, a direction orthogonal to both the X direction and the Z direction is also appropriately referred to as a Y direction. Further, in the X direction, the protruding side of the connector portion 52 is referred to as the front side, and the opposite side thereof is referred to as the rear side. Further, in the Z direction, the side on which the high voltage tower portion 72 is provided is referred to as a lower side, and the opposite side thereof is referred to as an upper side.

As shown in FIGS. 1 and 2, the case 7 houses the primary coil 5, the secondary coil 6, the central core 2, the outer peripheral core 3, and other parts inside. The case 7 is filled with the mold resin 12 together with these components. The mold resin 12 is, for example, an epoxy resin.

Further, as shown in FIG. 2, the case 7 is fitted with a connector portion 52 for connecting the ignition coil 1 to the outside. The connector portion 52 projects forward in the X direction. The connector portion 52 includes a connector terminal 521 inside. For example, when the ignition coil 1 is mounted on a vehicle, the connector terminal 521 is connected to a control device (not shown). The connector terminal 521 is also connected to the terminal of the igniter 11.

As shown in FIG. 1, the igniter 11 is located between the outer peripheral core 3 and the connector portion 52. The igniter 11 energizes and shuts off the primary coil 5 by an ignition signal determined by the control device. The igniter 11 is housed in the case 7, and the entire igniter 11 is embedded in the mold resin 12.

As shown in FIG. 2, the high voltage tower portion 72 is formed on the lower side of the case 7. The high voltage tower portion 72 has a tubular shape. The high-voltage tower portion 72 is formed so as to project downward. A conduction terminal 721 is provided on the high voltage tower portion 72. The conduction terminal 721 is connected to the secondary coil 6 via the high voltage terminal 62. Then, the igniter 11 cuts off the energization of the primary coil 5, so that a high voltage is generated in the secondary coil 6 by electromagnetic induction. The generated high voltage generates a discharge spark in the discharge gap of the spark plug (not shown) electrically connected to the secondary coil 6 via the conduction terminal 721. The generated discharge spark ignites the air-fuel mixture in the internal combustion engine.

The magnet body 4 is arranged between the central core 2 and the outer peripheral core 3 in the magnetic circuit formed by the central core 2 and the outer peripheral core 3. That is, as shown in FIG. 1, the magnet body 4 faces both the central facing surface 212, which is the front surface of the central core 2, and the outer peripheral facing surface 31 on the inner peripheral side of the outer peripheral core 3. Is arranged. The magnet body 4 is assembled so as to cover the entire center-side facing surface 212 of the central core 2. The magnet body 4 is, for example, a permanent magnet such as a neodymium magnet or a rare earth cobalt magnet.

The magnet body 4 is arranged so that the direction of the magnetic field generated from the magnet body 4 is opposite to the direction of the magnetic field generated in the central core 2 when a current is passed through the primary coil 5. Then, the magnet body 4 applies a magnetic bias to the central core 2 so as to increase the input energy of the ignition coil 1. That is, by increasing the amount of change in the magnetic flux when the energization of the primary coil 5 is cut off, the input energy is increased and the voltage induced in the secondary coil 6 is increased.

Further, the magnet body 4 has a plate-like shape. As shown in FIG. 2, the size of the magnet body 4 in the Z direction when the ignition coil 1 is viewed from the Y direction is approximately the same as the width of the central core 2 in the Z direction. Further, the size of the magnet body 4 in the Z direction is smaller than the width of the outer peripheral core 3 in the Z direction.

The magnet body 4 is assembled by driving in the Z direction to the unit to which the central core 2 and the outer peripheral core 3 are assembled before being assembled in the case 7. As shown in FIG. 3, the magnet body 4 is assembled to the unit in the Z direction from the lower side to the upper side when the unit is incorporated in the ignition coil 1. That is, the magnet body 4 is assembled to the unit along the direction of the arrow shown in FIG. Further, the magnet body 4 is inserted along the stacking direction of the magnetic steel plate 13 of the central core 2. Then, as shown in FIG. 4, the magnet body 4 is inserted between the center side facing surface 212 of the central core 2 and the outer peripheral side facing surface 31 of the outer peripheral core 3.

As shown in FIG. 1, the outer peripheral core 3 has a rectangular ring shape when viewed from the Z direction. The outer peripheral core 3 and the central core 2 form a closed magnetic path.

The outer peripheral core 3 is formed by laminating a plurality of magnetic steel plates 14. The stacking direction of the magnetic steel plates 14 of the outer peripheral core 3 is the same as the stacking direction of the magnetic steel plates 13 of the central core 2. That is, the magnetic steel plates 14 of the outer peripheral core 3 are laminated in the Z direction. Further, the outer peripheral side facing surface 31, which is the surface of the outer peripheral core 3 facing the magnet body 4, is covered with an insulating film 32.

The plurality of magnetic steel plates 13 and 14 constituting the central core 2 and the outer peripheral core 3 are fixed to each other in the stacking direction by caulking the caulked portions formed on the magnetic steel plates 13 and 14. The magnetic steel plates 13 and 14 may be fixed to each other by laser welding or adhesion.

The insulating film 32 covers the outer peripheral surface on the front side of the outer peripheral core 3. Then, as shown in FIGS. 1 and 2, the insulating film 32 is covered so as to cover the entire outer peripheral side facing surface 31. The insulating film 32 may be wound around the outer peripheral surface on the front side of the outer peripheral core 3 by one or more turns. The insulating film 32 is, for example, an insulating tape.

As shown in FIGS. 1 and 5, the central core 2 has a flange portion 21 protruding in the width direction, which is the Y direction orthogonal to both the stacking direction and the axial direction. The central core 2 has a central facing surface 212 on the collar portion 21.

Further, the central core 2 has a core main body 22 arranged inside the primary coil 5. The collar portion 21 projects in the Y direction on the front side of the core main body portion 22. When viewed from the Z direction, the collar portion 21 is in a direction away from the central axis C of the central core 2, and the width in the X direction decreases toward both the Y directions. The central core 2 has a T-shape as a whole.

As shown in FIG. 1, a groove portion 211 is arranged on the center side facing surface 212 at a position where the central axis C of the central core 2 passes. That is, the central axis C passes through the groove portion 211. Further, the central axis C passes through the center of the groove portion 211 in the Y direction. Further, the central axis C passes through the center of the groove portion 211 in the Z direction.

As shown in FIG. 5, the width of the groove portion 211 in the Y direction is smaller than the width of the core main body portion 22 in the Y direction. Further, the center-side facing surfaces 212 located on both sides of the groove portion 211 in the Y direction are on the same plane. Further, the center side facing surface 212 is a plane orthogonal to the X direction as a whole. However, the center-side facing surface 212 is formed with irregularities due to a slight deviation between the edge of the plurality of magnetic steel plates 13 and the shape of the edge itself.

Next, a method of manufacturing the primary spool 51 will be described.
The primary spool 51 is insert-molded with the central core 2 arranged inside. The primary spool 51 is made of an insulating resin.

In manufacturing the primary spool 51, as shown in FIGS. 7 to 9, the central core 2 is predetermined inside the mold composed of the fixed mold M1, the movable mold M2, and the slide molds M3 and M4 in advance. Place in position. As shown in FIG. 7, the central core 2 is fixed so as to be sandwiched in the Z direction by the fixed type M1 and the movable type M2. Further, as shown in FIG. 8, the central core 2 is fixed so as to be sandwiched in the X direction by the two slide types M3 and M4. Then, the primary spool 51 and the central core 2 are integrally molded by pouring the molten resin into the cavity 510 formed in the mold.

The end portion of the magnetic steel plate 13 constituting the central core 2 has a burr portion 131 formed by press working. That is, the burr portion 131 is formed by pulling the magnetic steel sheet 13 so that a part of the steel sheet is torn off when the steel sheet is sheared by a die to be pressed. After that, the plurality of magnetic steel plates 13 are laminated and pressurized, so that the burr portion 131 projects outward in the spreading direction of the magnetic steel plate 13. As a result, the burr portion 131 projects to the edge of the central core 2 as shown in FIG. Therefore, unevenness is formed on the edge of the central core 2.

As shown in FIG. 8, the central facing surface 212 of the central core 2 is in contact with the mold surface of the slide type M3. Further, when a part of the center side facing surface 212 shown in FIG. 7 is enlarged and viewed, as shown in FIG. 10, a part of the burr portion 131 of the magnetic steel plate 13 constituting the central core 2 and the slide type M3 It is in contact with the mold surface. Then, an end space 130 surrounded by an end including the burr portion 131 of the laminated magnetic steel plate 13 and a mold surface of the slide type M3 is formed. The end space 130 is formed along the Y direction. The end space 130 communicates with the groove 211 at one end in the Y direction.

In the process of manufacturing the primary spool 51, a part of the molten resin flows into the groove portion 211 formed on the center side facing surface 212 of the central core 2. That is, as shown in FIGS. 7 and 9, the molten resin flows into the groove space 214 continuous in the Z direction formed between the groove portion 211 and the mold surface of the slide type M3 facing the groove portion 211. Then, as shown in FIG. 10, the resin that has flowed into the groove space 214 flows into the end space 130 from the groove space 214 toward both sides in the Y direction. Then, the end space 130 is filled with the inflowing resin.

Next, after the resin poured into the cavity 510 has solidified, the primary spool 51 is removed from the mold. At this time, the movable M2 moves in the Z direction away from the primary spool 51. Further, the two slide types M3 and M4 move in the X direction in the direction away from the primary spool 51. Then, by removing it from the fixed type M1, the primary spool 51 is obtained.

As shown in FIG. 11, the molded primary spool 51 is integrally formed with the central core 2. Then, as shown in FIG. 12, when the primary spool 51 is viewed from the front side in the X direction, the entire center side facing surface 212 of the central core 2 is covered with the coating resin 213. As a result, the center side facing surface 212 is flattened. That is, even if there is a step formed by the edge edges of the plurality of magnetic steel plates 13 on the center side facing surface 212, the center side facing surface 212 is flattened by being covered with the coating resin 213. Further, the coating resin 213 is integrally formed with the primary spool 51.

Further, as shown in FIG. 13, the resin of the groove portion 211 of the central core 2 is also integrated with the primary spool 51. That is, the groove portion 211 is filled with resin, and the resin in the groove portion 211 is also a part of the coating resin 213.

More specifically, as shown in FIG. 14, the end portion of the press-processed magnetic steel plate 13 is exposed on the center-side facing surface 212 of the central core 2 before the coating resin 213 is formed. Further, as described above, the end portion of the magnetic steel plate 13 has a burr portion 131. Since the center-side facing surface 212 is a laminated surface in which magnetic steel plates 13 are laminated, it has a plurality of steps.

Then, as described above, the primary spool 51 is insert-molded together with the central core 2, so that the coating resin 213 is formed on the center side facing surface 212. Therefore, the burr portion 131 and the groove portion 211 of the central facing surface 212 are covered with the coating resin 213 as shown in FIG. Then, the center side facing surface 212 is flattened by the coating resin 213.

Next, the action and effect of this embodiment will be described.
In the ignition coil 1 for an internal combustion engine of the present embodiment, the central facing surface 212 is covered with a coating resin 213. Therefore, it is possible to prevent the step caused by the edge of the magnetic steel plate 13 from being exposed to the magnet body 4 side on the center side facing surface 212.

Further, a groove portion 211 is formed in a part of the center side facing surface 212 of the center core 2 facing the magnet body 4. Therefore, in the manufacturing process of the ignition coil 1, the resin can be supplied to the center side facing surface 212 through the groove portion 211. Therefore, it is possible to easily obtain a configuration in which the central facing surface 212 is covered with the coating resin 213. As a result, damage to the magnet body 4 during assembly can be prevented.

Further, the coating resin 213 formed on the center side facing surface 212 is integrally formed with the primary spool 51. Therefore, higher strength and durability can be obtained as compared with the case where only the coating resin 213 is formed.

Further, the central core 2 and the outer peripheral core 3 form a magnetic circuit. The magnetic flux density is small near the center of the central core 2 in the Y direction and tends to be large on the outside. Further, the groove portion 211 is arranged at a position through which the central axis C of the central core 2 passes. That is, the groove portion 211 is arranged near the center where the magnetic flux density is small. Further, the groove portion 211 is not formed on the outside of the central core 2. Therefore, it is possible to prevent damage to the magnet body 4 during assembly without deteriorating the performance of the ignition coil 1.

Further, the outer peripheral side facing surface 31 of the outer peripheral core 3 is covered with an insulating film 32. Therefore, it is possible to prevent the step caused by the edge of the magnetic steel plate 14 from being exposed to the magnet body 4 side on the outer peripheral side facing surface 31. As a result, damage to the magnet body 4 during assembly can be prevented. Further, since the outer peripheral core 3 is covered with the insulating film 32, it is possible to suppress a voltage leak from the outer peripheral core 3 to the igniter 11 adjacent to the outer peripheral core 3.

Further, the central core 2 has a collar portion 21 protruding in the Y direction. The central core 2 has a central facing surface 212 on the collar portion 21. Therefore, even if the groove portion 211 is formed on the center side facing surface 212, it is easy to sufficiently secure a magnetic path from the central core 2 to the outer peripheral core 3. As a result, damage to the magnet body 4 during assembly can be prevented without deteriorating the performance of the ignition coil 1.

As described above, according to the present embodiment, it is possible to provide the ignition coil 1 for an internal combustion engine that can prevent damage to the magnet body 4 at the time of assembly.

In the ignition coil 1 of the above embodiment, one groove portion 211 is formed in a part of the center side facing surface 212. However, it is also possible to form two or more groove portions 211 on a part of the center side facing surface 212.

Further, in the ignition coil 1 of the above embodiment, the shape of the groove portion 211 is a substantially rectangular shape in which the width in the Y direction is larger than the width in the X direction when viewed from the Z direction. However, the shape of the groove portion 211 may have a width in the X direction greater than or equal to the width in the Y direction. Further, the shape of the groove portion 211 may be substantially triangular or substantially semicircular.

The present invention is not limited to each of the above embodiments, and can be applied to various embodiments without departing from the gist thereof.

1 Ignition coil 13 Magnetic steel plate 2 Center core 211 Groove 212 Center side facing surface 213 Coated resin 3 Outer core 4 Magnet body 5 Primary coil 6 Secondary coil

Claims (5)

The primary coil (5) and the secondary coil (6), which are magnetically coupled to each other,
A central core (2) formed by laminating a plurality of magnetic steel plates (13) and inserted and arranged inside the primary coil and the secondary coil.
A magnetic circuit orthogonal to the stacking direction of the magnetic steel plate is formed together with the central core, and the outer peripheral core (3) arranged outside the primary coil and the secondary coil is formed.
It has a magnet body (4) arranged between the central core and the outer peripheral core in the magnetic circuit.
A groove portion (211) over the entire stacking direction of the magnetic steel plate is formed in a part of the center side facing surface (212) which is a surface facing the magnet body in the center core, and the center side facing surface is formed. Is an ignition coil (1) for an internal combustion engine, which is covered with a coating resin (213). According to claim 1, a primary spool (51) in which the primary coil is wound around the outer peripheral surface is provided on the outer peripheral surface of the central core, and the coating resin is integrally formed with the primary spool. The ignition coil for the internal combustion engine described. The ignition coil for an internal combustion engine according to claim 1 or 2, wherein the groove portion is arranged at a position through which the central axis (C) of the central core passes. The outer peripheral core is formed by laminating a plurality of magnetic steel plates (14), and the laminating direction of the magnetic steel plates of the outer peripheral core is the same as the laminating direction of the magnetic steel plates of the central core, and the outer peripheral core is said to have the same laminating direction. The ignition coil for an internal combustion engine according to any one of claims 1 to 3, wherein the outer peripheral side facing surface (31), which is a surface facing the magnet body, is covered with an insulating film (32). Any one of claims 1 to 4, wherein the central core has a collar portion (21) protruding in the width direction orthogonal to both the stacking direction and the axial direction, and the collar portion has the center side facing surface. The ignition coil for the internal combustion engine described in the section.

Images