JPH0219943Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the structure of an ignition coil for a meat combustion engine.

Conventionally, in the case of ignition coils in which the primary coil and secondary coil are inserted into the case and then insulated and fixed using cast resin such as thermosetting resin, both ends of the iron core are used to attach to the engine, and the case is closed. It has a structure that protrudes from the end surface, and requires a hole in the bottom of the case for the core to pass through.In order to prevent the casting resin from leaking between the core and the case, adhesive is attached to the mating surface of the case and core. Methods have been used, such as applying an agent to make them adhere tightly, or forming the case into a doughnut-shaped cross section in advance, and then inserting the core into the inner diameter of the case and fixing it with adhesive. It has the following drawbacks. (1) In the former case, it is necessary to glue the case and the core, and if the adhesive is not applied firmly, there will be a problem that the molding resin will leak later. In addition, it is necessary to cure the adhesive, which causes problems such as excess adhesive flowing out during curing. (2) In the latter case, it is of course necessary to bond and harden the core and case with an adhesive as described above, and in addition, in the case of this method,
There was a problem in which the coil body and core moved due to engine vibrations, etc.

In order to solve the above-mentioned drawbacks, the present invention has a tapered part integrated into the hole on the bottom of the case and a tapered part provided at one end of the primary bobbin. The purpose is to eliminate leakage and to be able to reliably prevent leakage without using extra materials such as adhesives as in the past.

The present invention will be described below with reference to embodiments shown in the drawings. In FIGS. 1 to 6, reference numeral 1 denotes a case made of injection molded synthetic resin or the like, and has a ring-shaped tapered portion 1a projecting inward at the bottom.
Reference numeral 1b denotes a collar portion partially opposed to the small diameter side of the tapered portion 1a, which is inserted into a groove 3d of the primary bobbin 3, which will be described later, and serves as a retainer. Reference numeral 2 denotes a central iron core (hereinafter referred to as core) made of laminated iron plates, which is partially provided with holes 2a, and when it is insert-molded into the primary bobbin 3, which will be described later, resin is filled in the holes 2a and the primary Bobbin 3
The core 2 is designed not to fall out. Reference numerals 2b denote mounting holes for attaching this coil to an engine or the like, which are provided at both ends of the core 2. Reference numeral 3 designates a primary bobbin made of resin, which is formed by insert molding a core 2 with mounting holes 2b at both ends thereof protruding to the outside. 3
A is a tapered portion provided at one end of the primary bobbin 3, and is fitted into the tapered portion 1a of the case 1.
3b and 3d are retaining protrusions and grooves into which the collar portion 1b of the case 1 is inserted and which prevents the primary bobbin 3 from coming out once inserted into the case 1;
A pair are provided at opposing positions at the tip of the tapered portion 3a of the primary bobbin 3. Reference numerals 3c and 3e denote a pair of collars that serve as the primary bobbin winding frame, and these collars 3c and 3e are provided on the outer periphery of both ends of the primary bobbin 3.
A primary coil 7 is wound between them. Reference numeral 4 denotes a secondary bobbin made of resin having a plurality of winding grooves in the axial direction on its outer periphery, and a secondary coil 8 is wound in sections around each of the winding grooves. Reference numeral 5 denotes a control circuit board on which electronic components 5a constituting a control circuit for controlling the primary current are mounted, and is disposed close to the low-voltage side end surface of the secondary bobbin 4. A resin 6 is injected into the case 1 after assembling the above-mentioned parts with casting resin, and serves to insulate and fix each part.

In the detailed views of the main parts shown in FIGS. 3 to 6, the large inner diameter D of the tapered portion 1a of the case 1 and the large outer diameter C of the tapered portion 3a of the primary bobbin 3 have a relationship of D<C, and the case The relationship between the width E between the tips of the pair of collar portions 1b of 1, the width A between the bottom surfaces of the pair of grooves 3d of the primary bobbin 3, and the width B between the outer ends of the pair of retaining protrusions 3b of the primary bobbin 3 is as follows. Since they are made in the relationship of A<E<B, each tapered part 1a, 3a is press-fitted, eliminating resin leakage, and connecting the retaining protrusion 3b and groove 3d of the primary bobbin 3 with the collar of the case 1. Due to the portion 1b, once inserted, the tapered portions 1a and 3a will not come off, making it possible to securely prevent leakage and fix.

In addition, since the collar portions 1b and the retaining protrusions 3b of both the tapered portions 1a and 3a are partially provided,
When the tapered portions 1a and 3a of the case 1 and the primary bobbin 3 are fitted together and are made of a relatively hard material, the collar portion 1b or the retaining protrusion 3b is relatively easily deformed, making assembly easy.

Furthermore, since the flange portion 1b is provided at the tip of the small diameter side of the inner periphery of the tapered portion 1a of the case 1, the flange portion 1b can also be formed by die cutting in the axial direction. The flange portion 1b can also be formed at the same time when the molding of the molding member 1 is performed, and the molding thereof is also easy. Note that since the primary bobbin 3 is formed by die cutting in the radial direction, the grooves 3d and the protrusions 3b can be easily formed.

As mentioned above, in this invention, the ring-shaped taper part provided on the bottom of the case and the taper part provided at one end of the primary coil bobbin are press-fitted into a taper fit, so there is no resin leakage when pouring resin. This has the excellent effect of providing a more reliable leak-proof structure that is easier to fix than conventional methods using adhesives or the like. Furthermore, since the collar and retaining protrusion are partially provided on each tapered part, the collar or retaining protrusion deforms relatively easily when the two taper parts are fitted together, making assembly easier. In addition, since the flange portion is provided on the small diameter side of the inner circumference of the tapered portion of the case, the flange portion can also be formed by die cutting in the axial direction, so there is an excellent effect that the case can be easily die-cut.

[Brief explanation of the drawing]

1 and 2 are longitudinal cross-sectional views and right side views thereof showing one embodiment of the ignition coil of the present invention, and FIGS. 3 and 4 are longitudinal cross-sectional views showing the main structure of the primary bobbin portion of the above-mentioned ignition coil. The figure, its right side view, and FIGS. 5 and 6 are a plan view and a longitudinal cross-sectional view showing the configuration of the main part of the case in the above-mentioned ignition coil. 1...Case, 1a, 3a...Tapered portion, 2...
...Center iron core (core), 3...Primary bobbin, 4...
Secondary bobbin, 6...Casting resin, 7...Primary coil, 8...Secondary coil.

Claims (1)

[Scope of utility model registration request] The primary coil and secondary coil are stored inside the case.
An ignition coil for an internal combustion engine that is cast with casting resin, includes a tapered part formed in a ring shape at the bottom of the case, a primary bobbin around which the primary coil is wound, and a tapered part provided at one end of the primary bobbin. A tapered part press-fitted into the tapered part of the case, a collar part partially opposed to the small diameter side of the inner periphery of the tapered part of the case, and a collar part corresponding to the collar part at the outer periphery tip of the tapered part of the primary bobbin. An ignition coil for an internal combustion engine, comprising a retaining protrusion and a groove that are partially provided as a flange and into which the collar is inserted.