JP3482385B2 - Ignition coil for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded ignition coil for an internal combustion engine, which supplies a high voltage for generating spark discharge to a spark plug of an automobile engine, for example.

[0002]

2. Description of the Related Art A primary and secondary coils, which are fitted concentrically with each other, are housed inside an insulating case having an open upper surface, an insulating resin is cast inside the insulating case, and a cured layer of the resin is formed. An ignition coil for an internal combustion engine in which both the primary coil and the secondary coil are fixed is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-20 of the present applicant.
It is known in Japanese Patent Laid-Open No. 4356 and Japanese Patent Laid-Open No. 2000-36423.

[0003]

[Problems to be Solved by the Invention]
The hardened layer 7 of an insulating resin, usually a thermosetting resin, cast to fix the secondary coil has a larger change in volume due to heat change than the other members in the insulating case 3 and is fragile.
Further, the hardened layer 7 of the insulating resin is generally the thickest between the bobbin of the secondary coil 2 fixed by the hardened layer in the case and the upper surface of the hardened layer. When the secondary bobbin is in close contact with the secondary bobbin, a stress is generated in the hardened layer which tends to largely change the volume with respect to the secondary bobbin which does not change its volume due to the heat change, and when this stress exceeds the breaking strength of the resin. As shown in FIGS. 5 (A, B) and 5 (C), cracks (C) are generated from the secondary bobbin 2'through the thick portion 7'of the hardened layer and reaching the upper surface of the hardened layer. , Quality problems occur.

[0004]

The present invention was developed for the purpose of solving the above-mentioned problems and effectively preventing the occurrence of cracks, and at least inside an insulating case having an open upper surface, For an internal combustion engine in which both primary and secondary coils fitted concentrically are housed, an insulating resin is cast inside an insulating case, and the primary and secondary coils are fixed in a cured layer of the resin. In the ignition coil, a grid member made of an insulating material, which is fitted to the inner circumference of the upper end of the insulating case and has a large number of small partitions opened in the vertical direction by a plurality of intersecting partition walls, is formed by curing the insulating resin. It is characterized by being buried in the upper part of the layer. In this case, in the insulating case, a member that comes into contact with the cured layer of the insulating resin may be provided with a supporting means for supporting the lattice member from below, or the upper part of the inner circumference of the insulating case may be engaged with the upper surface of the lattice member to form the lattice member. It is preferable to provide an upward movement preventing means for preventing the member from moving upward.

The expression "accommodating at least concentrically fitted primary and secondary coils inside an insulating case" means that the ignition coil is roughly divided into primary and secondary coils. The coil is vertically embedded in the solidified layer of insulating resin, and after fixing,
1 and 5 (A, B) in which a part of the closed magnetic circuit core is penetrated from the outside of the insulating case to the inner circumference of the primary coil;
A diagram in which both the secondary coil and the secondary coil are supported by a closed magnetic circuit core, the iron core is placed horizontally inside the insulating case together with the primary and secondary coils, and the iron core is simultaneously fixed in the solidified layer of the insulating resin. 3 and those shown in FIG. 5 (C), and the present invention is applicable to both ignition coils.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the illustrated embodiments, 1 is a primary coil, 1'is a primary socket for a primary terminal, 2 is a secondary coil concentrically fitted outside the primary coil, 3 Is an insulating case formed of synthetic resin or the like with an open upper surface, 4 is a hollow high-voltage cylinder integrally provided outward in the insulating case, 5 is a high-voltage terminal fixed in the high-voltage cylinder, 6 is a closed magnetic circuit core, and 7 is insulating A solidified layer of thermosetting insulating resin such as epoxy cast in a case, 8 is a grid member made of an insulating material such as insulating resin or synthetic rubber having a small volume change due to heat change and having high insulating property, 8 ' Is an outer frame of the lattice member, 9 is a large number of intersecting partition walls provided inside the outer frame, and 9'is a small partition formed by the partition walls and opened in the vertical direction.

In the embodiment shown in FIGS. 1 to 3, the deep bottom insulating case 3 has a hole at the center of the bottom which is closed by a collar at the lower end of the bobbin of the primary coil, and the inside of the bottom bottom side is The hollow high-pressure cylinder 4 closed by the high-voltage terminal 5 projects downward. The high-pressure cylinder may project laterally from the side wall of the case instead of protruding from the bottom of the case.

A primary coil 1 and a secondary coil 2 concentrically fitted to the outside of the primary coil 1 are housed downward in an insulating case 3, and a collar at the lower end of the bobbin of the primary coil is installed on the bottom of the insulating case. The holes are closed to prevent the resin from leaking through the holes in the bottom of the case when the insulating resin is cast. Upper collar 1a on the primary bobbin
Primary socket 1'with a primary terminal attached to one side above
Are integrated upwards. The upper end of the primary socket projects above the upper surface of the insulating case and slightly above the upper end of the primary bobbin. Before casting the insulating resin, connect the lead wire of the primary coil to the primary terminal of the primary socket, and the lead wire on the winding end side of the secondary coil to the high voltage terminal 5
Connect to.

Since the planar shape of the insulating case is oval, as is apparent from FIG. 2, the outer frame 8'of the lattice member is an oval shape that fits into the inner circumference of the insulating case. Inside the outer frame 8 ', there are a number of small compartments 9'opened in the vertical direction by the upper part of the bobbin of the primary coil and partition walls 9 intersecting each other while maintaining a space 10 for passing the primary socket 1'. It is provided.

When the grid member 8 is fitted into the insulating case 3 from above, the outer frame 8'resiliently has a plurality of sawtooth-shaped check claws 11 provided downward on the upper edge of the inner periphery of the insulating case. The upper edge is locked by the non-return pawl that pushes away and passes downward, and then returns after passing, and at the same time, the inner frame 10 'surrounding the space 10 cannot be moved upward. 1
It is received from below by a, and thus the lattice member 8 is vertically fixed above the inside of the insulating case.

After holding the lattice member 8 above the inside of the insulating case 5 in this manner, an insulating resin is cast into the insulating case to open a large number of small sections 9 inside the insulating case and in the vertical direction of the lattice member. ′ Is filled with an insulating resin and hardened, and the hardened layer 7 is used to harden the primary and secondary coils 1 and 2, and the grid member 8
May be fixed, or after the primary and secondary coils are housed in the insulating case, the insulating resin is cast before fixing the grid member,
Before the hardening, the lattice member 8 may be pushed and held in the resin layer above the inside of the insulating case to wait for the hardening of the insulating resin.

In any case, after the insulating resin is cured,
As shown in FIG. 3, one leg 6 ', 6'of the closed magnetic circuit core 6 is passed through the inner circumference of the bobbin of the primary coil, and the other leg is abutted outside the insulating case to assemble the ignition coil.

In the embodiment of FIG. 4, the insulating case 3 is provided with an inwardly projecting step 13 at the lower end of the side wall 3'of the upper half part, and on this step 13 the core-coil assembly of the closed magnetic circuit is formed. Place the outer ring core 6a. The primary coil 1 and the secondary coil 2 fitted concentrically outside the primary coil 1 are supported by a center iron core 6b that traverses the inside surrounded by the outer ring iron core and penetrates the bobbin of the primary coil. The lower half of the insulating case is composed of a downward recess 14 provided on the inner circumference of the step 13, the high pressure cylinder 4 is provided downward at the center of the bottom of the recess, and the hollow portion of this high pressure cylinder is the recess. It opens at the center of the bottom. The end of the high-voltage terminal 5 fixed in the hollow portion of the high-pressure cylinder faces the inside of the recess 14 through the opening, and preferably projects slightly.
A primary socket 1'having a primary terminal attached thereto is provided outward on one side wall 3'of the insulating case.

The iron core-coil assembly is attached to the step 13 of the insulating case.
When mounted on the top, the lead wire on the winding end side of the secondary coil is connected to the high voltage terminal 5, and the lead wire of the primary coil is connected to the primary terminal of the primary socket 1 '.

As is apparent from FIG. 4 (B), the planar shape of the insulating case 3 is substantially quadrangular, so that the outer frame 8'of the lattice member is a quadrangle fitted to the inner circumference of the insulating case. There is. Since there is no member protruding upward from the upper surface of the insulating case, a large number of small compartments 9'opened in the vertical direction are provided by intersecting partition walls 9 in the entire inside of the outer frame.

In order to hold the lattice member 8 above the inside of the insulating case 3, a protrusion 12 for receiving and supporting the outer frame 8'of the lattice member from below and an outer frame 8'on the inner periphery of the insulating case 3. A plurality of sawtooth check claws 11 are provided at different positions to prevent the outer frame from moving upward when being supported by the projections 12 from below.

When the lattice member is fitted into the inside of the insulating case from above, the outer frame elastically pushes the check claw to pass downward, and when it passes, it is received from below by the projection 12 and simultaneously returns. The non-return pawl 11 locks the upper edge of the grid member, and thus the lattice member is held vertically above the inside of the insulating case.

After holding the lattice member 8 above the inside of the insulating case 5 in this way, an insulating resin is cast into the insulating case to open a large number of small sections 9 inside the insulating case and in the vertical direction of the lattice member. ′ May be filled with an insulating resin to be hardened, and the hardened layer 7 may fix the primary and secondary coils 1, 2 and the iron core 6 and the grid member 8 to each other. After accommodating in the insulating case, the insulating resin is cast before fixing the lattice member, and before the curing, the lattice member 8 is pushed and held in the resin layer above the inside of the insulating case, and waits for the curing of the insulating resin. Good.

[0019]

According to the present invention, an insulating material is formed on the inside of an insulating case where an insulating resin is cast and cured, and a large number of small compartments opened in the vertical direction by a number of intersecting partition walls. The grid member is held, and the inside of the small section is also filled with a cured layer of insulating resin. As a result, the stress of the cured layer of the insulating resin generated by the heat change above the open inside of the insulating case is dispersed into each small section of the lattice member and is suppressed to the breaking strength of the resin or less. The occurrence of reaching cracks can be prevented.

[Brief description of drawings]

FIG. 1A is a vertical sectional side view in which a part of an embodiment of an ignition coil is enlarged, and FIG. 1B is a perspective view of a lattice member.

FIG. 2 is a plan view of the ignition coil shown in FIG.

FIG. 3 is a perspective view showing an assembled state of the ignition coil shown in FIG.

FIG. 4A is an enlarged vertical side view of a part of another embodiment of the ignition coil, and FIG. 4B is a plan view of the same.

5A is a vertical sectional side view of a conventional ignition coil in a cracked state, FIG. 5B is a plan view of the same, and FIG. 5C is a vertical sectional view of another conventional ignition coil in a cracked state. Side view.

[Explanation of symbols]

1 primary coil 2 Secondary coil 3 insulating case 7 Hardened layer of insulating resin 8 lattice members 8'lattice outer frame 9 Partition walls of lattice members 9'Lattice member subdivision 11 Check claw 12 protrusions

Claims (3)

(57) [Claims] 1. A primary case and a secondary coil, which are fitted concentrically with each other, are housed inside an insulating case having an open upper surface, an insulating resin is cast inside the insulating case, and a cured layer of the resin is formed. In the ignition coil for an internal combustion engine in which both the primary coil and the secondary coil are fixed, a large number of small compartments fitted in the inner periphery of the upper end of the insulating case and opened in the vertical direction by a plurality of intersecting partition walls are provided. An ignition coil for an internal combustion engine, wherein the formed grid member made of an insulating material is embedded in an upper portion of the hardened layer of the insulating resin. 2. The ignition coil for an internal combustion engine according to claim 1, wherein a member that comes into contact with the hardened layer of the insulating resin in the insulating case is provided with support means for supporting the lattice member from below. Ignition coil for internal combustion engine. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the lattice member is upwardly engaged with an upper surface of an inner periphery of the insulating case by engaging an upper surface of the lattice member. An ignition coil for an internal combustion engine, comprising upward movement preventing means for preventing movement.