JP3783957B2 - Ignition coil for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine ignition coil, and more particularly to a stick-like internal combustion engine ignition coil mounted directly in a plug hole.

  As a conventional stick-shaped internal combustion engine ignition coil (hereinafter referred to as an internal combustion engine ignition coil), a rod-shaped core is disposed at the center of the shaft, and a primary coil and a secondary coil are wound around the outer periphery thereof. A known spool made of resin, and an outer peripheral core disposed on the outer periphery thereof, are filled with resin as an insulating material between the members in the housing of the ignition coil. The resin filled in the housing not only serves as an insulating material but also penetrates between the coil wires to prevent the coil from collapsing.

  Since the outer core is in direct contact with the resin insulation in the housing, if the outer core and the resin insulation having different coefficients of thermal expansion repeatedly expand and contract due to temperature changes, the resin insulation that contacts the end corners of the outer core Cracks that are insulation defects may occur in the material. If a crack is generated in the resin insulating material in contact with the outer peripheral core that is the low voltage portion, there is a risk of discharge through the crack between the secondary coil or high voltage terminal that is the high voltage portion and the outer peripheral core. When a discharge occurs between the high voltage portion and the low voltage portion, the voltage applied to the spark plug, which is an ignition device, decreases, so that a desired high voltage cannot be applied to the spark plug.

Further, for example, when the crack reaches the lead line connecting the coil and the terminal, the lead line may be disconnected.
Although it is not a stick-like ignition coil, an ignition coil is known that covers the corners of the core by overcoating the surface of the core with an elastomer (for example, Patent Document 1). In Patent Document 1, this prevents the corner of the core and the epoxy resin from coming into direct contact with each other, and suppresses the occurrence of cracks in the epoxy resin near the corner of the core.
Japanese Utility Model Publication No.59-30501

  However, since the outer diameter of the stick-like ignition coil is regulated in accordance with the inner diameter of the plug hole, if the outer core is coated like the ignition coil disclosed in Japanese Utility Model Publication No. 59-30501, the ignition coil has a coating thickness. There is a problem that the outer diameter of the is increased.

The object of the present invention is to suppress the occurrence of cracks in the resin insulating material in the vicinity of the inner peripheral corner of the axial end of the outer core without increasing the size of the ignition coil in the radial direction. It is to provide an ignition coil that is generated.
Another object of the present invention is to provide an ignition coil in which an elastic member that is locked to an axial end of an outer peripheral core can be easily assembled.

According to the ignition coil of the first aspect of the present invention, since the elastic member is locked to the axial end of the outer peripheral core disposed on the outer periphery of the primary coil and the secondary coil, Prevents the insulating resin from coming into direct contact. Therefore, even if the outer peripheral core and the resin insulating material having different coefficients of thermal expansion repeatedly expand and contract with temperature changes, the resin insulating material near the end of the outer peripheral core that locks the elastic member will crack as an insulating defect. Occurrence can be suppressed.

Furthermore, since the elastic member is locked only between the end of the outer core and the axial end surface of the flange , the resin insulation in the vicinity of the end of the outer core without expanding the physique of the ignition coil in the radial direction. The occurrence of cracks in the material can be suppressed.
Further, since the elastic member made of an elastic body is locked between the end portion of the outer peripheral core and the axial end surface of the flange portion, the difference in the thermal expansion coefficient between the outer peripheral core and the resin insulating material having different thermal expansion coefficients can be reduced. The elastic member can be absorbed by elastic deformation. Accordingly, it is possible to further favorably suppress the occurrence of cracks in the insulating resin material at the end portion of the outer peripheral core. Thereby, since it can suppress discharging between the secondary coil as a high voltage part, a high voltage terminal, etc., and the outer periphery core as a low voltage part, it is prevented that the voltage applied to a spark plug falls and desired A high voltage can be applied to the spark plug.

  Further, by attaching the elastic member to the attachment portion formed on the primary spool, the primary spool can be inserted into the outer peripheral core with the elastic member attached to the primary spool. Therefore, the elastic member is unlikely to be detached from the primary spool at the time of insertion, so that the assembling property is improved and the assembling man-hour can be reduced.

Hereinafter, a plurality of examples showing embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
An ignition coil according to a first embodiment of the present invention is shown in FIGS.
The ignition coil 10 shown in FIG. 1 is accommodated in a plug hole formed for each cylinder in an upper portion of an engine block (not shown), and is electrically connected to an ignition plug (not shown) on the lower side of FIG.

  The ignition coil 10 includes a cylindrical housing 11 made of a resin material. A central core 15 as a core, magnets 16 and 17, a secondary spool 20, a secondary spool are formed in a storage chamber 11 a formed in the housing 11. A coil 21, a primary spool 23, a primary coil 24, an outer core 25, and the like are accommodated. The housing 11 is configured by fitting a lid portion 12 to a transformer portion 13. The epoxy resin 26 filled in the storage chamber 11a penetrates between the members in the ignition coil 10, and ensures electrical insulation between the members as a resin insulating material.

  The cylindrical central core 15 is assembled by laminating thin silicon steel plates in the radial direction so that the cross section is substantially circular. Magnets 16 and 17 having a polarity opposite to the direction of the magnetic flux generated by excitation by the coil are attached to both ends of the central core 15 in the axial direction. Further, a rubber material 18 covers the outer periphery of the center core 15 as an insulating material.

  The secondary spool 20 is disposed on the outer periphery of the rubber material 18 and is formed of a resin material. The secondary coil 21 is wound around the outer periphery of the secondary spool 20, and a dummy coil 22 is further wound around the secondary coil 20 on the high voltage side in a single turn. The dummy coil 22 electrically connects the secondary coil 21 and the terminal plate 40. By electrically connecting the secondary coil 21 and the terminal plate 40 with the dummy coil 22 instead of a single wire, the surface area of the electrical connection portion between the secondary coil 21 and the terminal plate 40 is increased, and the electrical connection portion is reached. Avoid electric field concentration.

  The primary spool 23 is disposed on the outer periphery of the secondary coil 21 and is formed of a resin material. An end portion of the primary spool 23 positioned on the low voltage side of the secondary coil 21 is formed with a flange portion 23a projecting radially outward, and a cross-sectional L-shape for fitting a ring member 51 described later to the flange portion 23a. A shaped mounting portion 23b is formed. The primary coil 24 is wound around the outer periphery of the primary spool 23 and is electrically connected to a switching circuit (not shown) via a terminal 31.

  The outer peripheral core 25 is mounted on the outer side of the primary coil 24. The outer peripheral core 25 winds a thin silicon steel plate in a cylindrical shape and does not connect the winding start end and the winding end end, so that a gap is formed in the axial direction. The outer peripheral core 25 has an axial length extending from the outer peripheral position of the magnet 16 to the outer peripheral position of the magnet 17.

  Inner peripheral corners at both axial ends of the outer peripheral core 25 are covered with ring members 50 and 51 as elastic members made of rubber which is an elastic body, and the ring members 50 and 51 are locked. The inner peripheral corner of the outer core 25 located on the high voltage side of the secondary coil 21 is covered with a ring member 50, and the inner peripheral corner of the outer core 25 located on the low voltage side of the secondary coil 21 is a ring. Covered with a member 51. As shown in FIG. 2, the ring member 51 is attached to the primary spool 24 by being fitted to an attachment portion 23b formed in the flange portion 23a. Before the ring member 51 is assembled to the mounting portion 23b, the inner diameter of the ring member 51 is set to be slightly smaller than the outer diameter of the outer peripheral surface of the mounting portion 23b. Thereby, the elastic force of the ring member 51 is working toward the inner side in the radial direction with respect to the mounting portion 23b.

  As shown in FIG. 1, a control signal input connector portion 30 is provided on the lid portion 12 so as to protrude from the plug hole, and a control signal is supplied to the primary coil 24 to the connector 30 or a secondary coil. 21 and a plurality of terminals 31 connected to the ground side of the primary coil 24 are insert-molded. A switching circuit that supplies a control signal to the primary coil 24 via the terminal 31 is provided outside the ignition coil 10. Each terminal 31, the secondary coil 21, and the primary coil 24 are electrically connected by a lead wire.

  The high voltage terminal 41 is insert-molded in the transformer section 13. The central portion of the terminal plate 40 constitutes a claw portion that is bent in the direction in which the high voltage terminal 41 is inserted. The high voltage terminal 41 is electrically connected to the terminal plate 40 by inserting the tip of the high voltage terminal 41 into the claw portion. The wire at the high voltage end of the dummy coil 22 is electrically connected to the terminal plate 40 by fusing or soldering. The spring 42 is electrically connected to the high voltage terminal 41 and electrically connected to the spark plug when the ignition coil 10 is inserted into the plug hole. A plug cap 19 made of rubber is attached to the open end of the housing 11 on the high voltage side, and an ignition plug is inserted into the plug cap 19. When a control signal is supplied from the switching circuit to the primary coil 24, a high voltage is generated in the secondary coil 21, and this high voltage is applied to the spark plug via the dummy coil 22, the terminal plate 40, the high voltage terminal 41, and the spring 42. .

Next, a procedure for assembling the ignition coil 10 will be described.
(1) The ring member 50 is fitted into one end of the outer peripheral core 25, and the outer peripheral core 25 is inserted into the transformer unit 13 having the high-voltage terminal 41 and the spring 42 from the ring member 50 side. When the ring member 50 is locked to the locking portion 13a of the transformer portion 13 shown in FIG. 3, the insertion amount of the outer peripheral core 25 is defined.

  (2) A coil assembly composed of the central core 15, the magnets 16 and 17, the secondary spool 20, the secondary coil 21, the primary spool 23 in which the ring member 51 is fitted to the mounting portion 23b, and the primary coil 24 is used as the outer core. 25. Since the ring member 51 is fitted to the mounting portion 23b by applying a radially inner elastic force, the ring member 51 is not easily displaced from the mounting portion 23b. The ring member 51 is locked to the inner peripheral corner portion of the end portion of the outer peripheral core 25, whereby the insertion amount of the coil assembly is defined.

(3) The lid portion 12 is fitted into the transformer portion 13 and an epoxy resin is injected from the opening 12 a of the lid portion 12.
In the above assembling procedure, the outer peripheral core 25 is assembled to the coil assembly, and the end inner peripheral corner of the lower voltage side of the outer peripheral core 25 is covered with the ring member 51 in advance, and then the coil assembly including the outer peripheral core 25 is transformed into the transformer section. 13 may be inserted.

  Here, since the thermal expansion coefficient of the epoxy resin 26 is larger than the thermal expansion coefficient of the outer peripheral core 25 formed from the silicon steel plate, the inner peripheral corners of both ends of the outer peripheral core 25 are not covered with the ring members 50 and 51. When the epoxy resin 26 is in direct contact with the inner peripheral corners of both ends of the outer peripheral core 25, the ring members 50 and 51 and the epoxy resin 26 repeat expansion and contraction due to temperature change, so that the inner peripheral corners of both ends of the outer core 25 Cracks are likely to occur in the epoxy resin 26 in contact with. If a crack occurs in the epoxy resin 26 in contact with the inner peripheral corners of both ends of the outer core 25, the high voltage side of the secondary coil 21, which is a high voltage portion, the dummy coil 22, the terminal plate 40 or the high voltage terminal 41, and the low voltage It may discharge through the crack between the outer peripheral core 25 which is a part. When discharging is performed between the high voltage portion and the low voltage portion, the voltage applied to the spark plug is lowered, so that a desired high voltage cannot be applied to the spark plug.

  However, in the first embodiment, the inner peripheral corners of both ends of the outer core 25 are covered with rubber ring members 50 and 51 to prevent the inner peripheral corners of both ends of the outer core 25 from directly contacting the epoxy resin 26. . Further, the difference in thermal expansion coefficient between the outer core 25 and the epoxy resin 26 can be absorbed by the elastic deformation of the ring members 50 and 51. Therefore, since no crack is generated in the epoxy resin 26 near the inner peripheral corners of the both ends of the outer peripheral core 25, the high voltage side of the secondary coil 21, the dummy coil 22, the terminal plate 40 or the high voltage terminal 41 and the outer peripheral core 25. It is possible to suppress the discharge. Therefore, a desired high voltage can be applied to the spark plug.

  Further, since the ring member 51 can be fitted to the mounting portion 23 b of the primary spool 23, the ring member 51 is unlikely to come off from the primary spool 23 when the primary spool 23 is inserted into the outer peripheral core 25. Thereby, the assembling property of the ring member 51 is improved, and the assembling man-hour is reduced.

(Second embodiment)
An ignition coil according to a second embodiment of the present invention is shown in FIG. Components that are substantially the same as those in the first embodiment are denoted by the same reference numerals.
A flange portion 27a is formed at the end of the primary spool 27 located on the low voltage side of the secondary coil 21, and an annular groove as a mounting portion for fitting and attaching a ring member 52 as an elastic member to the flange portion 27a. 27b is formed. Since the ring member 52 is fitted into the annular groove 27b and the axial movement of the ring member 52 is restricted, the ring member 52 is not easily displaced when the primary spool 27 is inserted into the outer peripheral core 25. Therefore, the assembly of the primary spool 27 fitted with the ring member 52 is further facilitated, and the number of assembling steps is reduced. The inner peripheral corner of the outer core 25 located on the high voltage side of the secondary coil 21 is covered with a ring member 50 (not shown) as in the first embodiment.

  In the first embodiment and the second embodiment described above, the ring member as the elastic member covers the inner peripheral corners of both ends in the axial direction of the outer core 25 and is locked to the inner peripheral corners of both ends of the outer core 25. Thus, the epoxy resin 26 is prevented from coming into direct contact with the inner peripheral corners of both ends of the outer core 25. Thereby, it is suppressed that the crack by the temperature change generate | occur | produces in the epoxy resin 26 of the outer peripheral core 25 near the inner peripheral corner part of both ends. Furthermore, since the ring member is formed of rubber as an elastic body, the difference in thermal expansion coefficient between the outer peripheral core 25 and the epoxy resin 26 is absorbed by the elastic deformation of the ring member, so that cracks are less likely to occur. Therefore, it is possible to suppress discharge between the high voltage side of the secondary coil 21 that is the high voltage portion, the dummy coil 22, the terminal plate 40 or the high voltage terminal 41, and the outer peripheral core 25 that is the low voltage portion. A desired high voltage can be applied to the coil.

In addition, since not only the entire surface of the outer peripheral core 25 but the end inner peripheral corners are covered with the ring member, the diameter of the ignition coil does not increase.
In addition, when an elastic member is formed of a material capable of shrinking volume, for example, a single foam sponge, the single foam sponge is easily deformed, so that the single foam sponge that abuts the outer core by pressing the outer core against the single foam sponge. The cross-sectional shape of the outer peripheral core is deformed into an L shape in accordance with the shape of the end inner peripheral corner of the outer core, and the end inner peripheral corner of the outer core can be covered. Therefore, since the cross-sectional shape of the elastic member can be formed in a simple plate shape without being formed in an L shape in advance, the elastic member can be easily processed.

In the above embodiments, the inner peripheral corners of both ends of the outer core 25 are covered with the ring member. However, it is also possible to cover only one inner end corner of the outer core 25 with the ring member. .
Further, in the above embodiments, the inner peripheral corners of both ends of the outer core 25 are covered. However, when there is no limit in the radial direction, for example, the end of the outer core on the secondary coil low voltage side of this embodiment is used. It may be covered with a ring member having a U-shaped cross section. Even if the elastic member does not cover the end of the outer core 25 and the elastic member is merely locked to the end of the outer core 25, the epoxy resin 26 is directly connected to the end of the outer core 25. It is possible to prevent contact. Thereby, it can suppress that a crack generate | occur | produces in the epoxy resin 26 of the edge part vicinity of the outer periphery core 25. FIG.

  In the above embodiments, the end corners of the outer core 25 are chamfered and rounded by a method such as chamfering or cutting, thereby preventing damage to the ring member in contact with the end corners of the outer core 25. it can. In addition, even when the ring member does not cover the end corners of the outer peripheral core 25, it is possible to suppress the occurrence of cracks in the epoxy resin 26 near the end corners of the outer core 25.

It is sectional drawing which shows the ignition coil by 1st Example of this invention. It is typical sectional drawing which shows the low voltage side of the ignition coil by 1st Example. It is sectional drawing which shows the high voltage side of the ignition coil by 1st Example. It is typical sectional drawing which shows the low voltage side of the ignition coil by 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ignition coil, 11 Housing, 15 Center core (core), 16, 17 Magnet, 20 Secondary spool, 21 Secondary coil, 23 Primary spool, 23b Mounting part, 24 Primary coil, 25 Outer core, 26 Epoxy resin (resin Insulating material), 27 primary spool, 27a collar, 27b annular groove (mounting part), 50, 51, 52 ring member (elastic member)

Claims (1)

An internal combustion engine ignition coil that generates a high voltage to be applied to an internal combustion engine ignition device,
A rod-shaped core,
A primary coil and a secondary coil wound around the outer periphery of the core;
A secondary spool that winds the secondary coil, and a primary spool that is disposed on the outer peripheral side of the secondary spool and winds the primary coil;
A flange formed on the end of the primary spool so as to protrude radially outward of the primary spool;
An outer peripheral core disposed on the outer periphery of the primary coil and the secondary coil;
A resin insulation filled in the ignition coil;
Attached to an attachment portion formed on the flange, and is locked between an end of the outer core located on the secondary coil low voltage side in the axial direction of the outer core and an axial end surface of the flange An elastic member made of an elastic body,
An ignition coil for an internal combustion engine, comprising:

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