JPH01140706A - Ignition coil for internal combustion engine - Google Patents

Abstract

PURPOSE:To make a core small-sized and lightweight and to make an ignition coil small-sized and lightweight as a whole by a method wherein the core is constituted by using a ferrite and its outer circumference is covered with a cover made of a synthetic resin. CONSTITUTION:A ferrite whose magnetic permeability is particularly excellent is used for a core 11. A bobbin 1 2 on which a primary coil 8 or a secondary coil 9 is wound covers this ferrite core 11; the elastic bobbin 12 composed of a synthetic resin or the like is utilized as a protective material ot the ferrite core 11 which is a brittle sintered substance. By this setup, the core 11 can be made small-sized and, furthermore, an ignition coil can be made small-sized and lightweight as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coil used for ignition of an internal combustion engine, and particularly to a structure of an ignition coil for an internal combustion engine that can be made smaller and lighter.

[Conventional technology]

Ignition coils used for ignition of internal combustion engines have been strongly required to be smaller and lighter to accommodate engine compartments that have become smaller and smaller in recent years.

In order to satisfy such requirements, for example, Japanese Patent Application Laid-Open No. 52-462
As shown in Publication No. 37, a plurality of silicon steel plates are laminated to form a core, and a primary coil is placed on top of the core.

A so-called molded ignition coil is known in which a secondary coil is wound, the coils are housed in a case, and the outer periphery of the coil is coated with synthetic resin.

However, such ignition coils use a silicon steel plate as the core, which makes the core large and has a rectangular cross section, so the space factor for winding the coil is poor. However, the cross-sectional area of the ignition coil as a whole inevitably becomes large.

Also, a device using a ferrite core as the core is known, for example, from U.S. Pat. No. 3,566.202, etc. However, ferrite is a sintered body,
The ferrite core easily breaks due to impact, etc., and in a structure in which a coil is wound through an insulating material such as insulating paper, the ferrite core cracks during the winding process, resulting in poor productivity. It had a point.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems in the prior art, and its purpose is to reduce the size. An object of the present invention is to provide a large-point coil for an internal combustion engine that is lightweight and has excellent productivity.

[Means for solving problems]

The above object, according to the present invention, includes a primary coil that flows an intermittent primary current in response to the rotation of an internal combustion engine, and a magnetically coupled primary coil that generates a high ignition voltage by intermittent intermittent primary current. and a core that magnetically couples the primary coil and the secondary coil, these are housed in a resin case, and a thermosetting synthetic resin is injected and hardened for use in an internal combustion engine. This is achieved by an ignition coil for an internal combustion engine characterized in that the core is made of ferrite and the outer periphery of the core is covered with a cover made of synthetic resin.

[Effect]

That is, according to the present invention as described above, by using a ferrite core with excellent magnetic permeability, the core can be made smaller and lighter, but on the other hand, even if a wire is wound on a brittle ferrite core, the core will crack. Therefore, it is possible to provide an ignition coil for an internal combustion engine that has low flooding, is lightweight, and has excellent productivity.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an ignition coil used in a capacitor discharge type ignition device widely used in, for example, two-wheeled vehicles. That is, this capacitor discharge type ignition device
As shown in the figure, DC power supplied from a storage battery 2 mounted on the vehicle is converted to AC power by a chopper circuit 3, and charged to a charge/discharge capacitor 6 by a rectifier circuit including diodes 4, 5, etc. , the thyristor 7 is made conductive to obtain a high voltage ignition signal. As shown in the figure, the ignition coil 1, more specifically the primary coil 8, is connected in series in the discharge circuit of the charge/discharge capacitor 6 that is formed when the thyristor 7 conducts. As a result, the discharge current of the charging/discharging capacitor 6 rapidly flows, and as a result, a high voltage for ignition is induced in the secondary coil 9, and an ignition spark is generated in the ignition plug 10.

Returning to FIG. 1 again, details of the ignition coil 1 will be explained. First, the primary coil 8 is made of a primary coil bobbin 1 that houses a cylindrical ferrite core 11 therein.
It is wrapped around the outer circumference of 2.

The details will be explained again later, but this primary coil bobbin 12 is made of thermoplastic synthetic resin such as polybutylene terephthalate, and a primary side input terminal 13.13 is provided on its outer periphery, and the wire diameter is 0. 3-1. Omn
The enamelled wire of about 100 lbs. is laminated and wound over several layers, several thousand times per layer, a total of 25 to 100 times, and the winding start terminal and q winding end terminal are connected to the primary side input terminal 13.13. A primary coil 8 is formed. The outer periphery of the primary coil bobbin 12 is coated with an adhesive made of epoxy resin over which the primary coil 8 is wound, and an insulating layer 1 is formed.
4 is formed.

On the above-mentioned primary coil bobbin 12, on its outer periphery,
Furthermore, a bobbin 15 for a secondary coil is provided. The secondary coil bobbin 15 is made of the same thermoplastic synthetic resin as the primary coil bobbin, and has an inner cylindrical shape and a plurality of flanges 16 provided at equal intervals in the axial direction. A plurality of grooves (nine in the above embodiment) are formed in which the secondary coil 9 is wound.

That is, the secondary coil 9 is wound on the secondary coil bobbin 15 by so-called split winding, for example, 0.
．． 0.3~0.1mm enameled wire into each groove above.
The secondary coil is wound approximately 0 to 1,000 times, and the total number of secondary coils wound around the nine grooves is approximately 3,000 to 10,000 times. After connecting the winding start end of this secondary coil 9 to the lead wire of the primary coil 8, the ferrite core 1
The primary coil 8 wound on the coil bobbin 1 is housed in four parts of a case 17 made of an insulating material such as a thermoplastic resin similar to the primary coil bobbin 12, secondary coil bobbin 15, etc. Place the device in case 17 above.
The high-voltage terminal 18 is connected to the high-voltage terminal 18 installed in advance.

Thereafter, a thermosetting resin 19 such as an epoxy resin is injected into the case 17 in a vacuum, the resin is sufficiently impregnated around the primary coil 8 and the secondary coil 9, and the resin is thermally cured under heating. Fix and insulate. In addition, a tightening metal tube 20.20 for attaching this ignition coil to the engine is further integrally attached to the case 9,
A high voltage cord 21 is electrically connected to the tip of the high voltage terminal 18. This high voltage cord 21 is connected to the case 1 mentioned above.
A high voltage coat receiver integrally formed in a part of part 7 is attached to part 22 and fixed with adhesive 23 applied between them, and further airtight with a rubber terminal cover 24 to ensure insulation. covered.

2(a), (b) and FIG. 3(a), (b) show details of the bobbin 12 for the primary coil of the ignition coil. As shown in the figure, the cylindrical primary coil bobbin 12 is divided into two parts in the axial direction. These two divided bobbins 121, 12
2 is a recess 123 that accommodates the ferrite core 11;
124 is provided at its center, and at its upper end is a protrusion 125 to which the above-mentioned primary input terminal 13.13 is attached.
125, 126, 126 are formed. and,
These bobbins 121, 122 are made of thermosetting synthetic resin as described above. Further, one of the two bobbins 121 has four small recesses 127, 1 around the central recess 123 on the dividing surface.
27..., and four small protrusions 128, 128... are formed on the other bobbin 122 at positions corresponding to these.

And these two divided bobbins 121°122
After inserting the ferrite core 11 between the central recesses 123 and 124, the four small recesses 12 are inserted.
7, 127... and the small protrusions 128°, 128... are fitted together, and these are joined together as shown in Fig. 3(a), (
A primary coil bobbin 12 as shown in b) is formed.

Further, in the above embodiment, the ferrite core 11 has a cylindrical shape. Of course, the ferrite core 11 is not limited to this cylindrical shape, but may also be prismatic. However, the primary coil 8. This cylindrical shape is most preferable in consideration of the secondary coil 9 and also in consideration of the space factor and the like.

In the above example, ferrite, which has particularly excellent magnetic permeability, is used as the core, compared to the conventional silicon steel plate, so the core can be made smaller, and the ignition coil as a whole can be made smaller and lighter. be. Furthermore, the bobbin on which the primary coil or secondary coil is wound is made to cover the ferrite core, and the bobbin is made of synthetic resin and has elasticity to protect the ferrite core, which is a brittle sintered body. Since it can be used as a member, it will not break during the manufacturing process and will not deteriorate productivity.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, by reducing the width of the core, the entire ignition coil can be made smaller and lighter, and it is an extremely excellent product that does not deteriorate its productivity. It becomes possible to provide an ignition coil for an internal combustion engine.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the cross-sectional structure of an ignition coil for an internal combustion engine, which is an embodiment of the present invention, and FIG. 2(a). (b) and FIGS. 3(a) and 3(b) are diagrams showing the structure of the primary coil bobbin shown in FIG. FIG. 2 is a circuit diagram schematically showing the device. 8...Primary coil, 9...Secondary coil, 11...
Ferrite core, 12...Bobbin for primary coil. rate 1 diagram

Claims (4)

[Claims] 1. A primary coil that flows an intermittent primary current in response to the rotation of the internal combustion engine; a secondary coil that is magnetically coupled to the primary coil and generates a high ignition voltage by intermittent intermittent of the primary current; In an ignition coil for an internal combustion engine, the ignition coil has a core for magnetically coupling a second coil, these are housed in a resin case, and a thermosetting synthetic resin is injected and hardened, the core being made of ferrite, An ignition coil for an internal combustion engine, characterized in that its outer periphery is covered with a synthetic resin cover. 2. Claim 1, wherein the synthetic resin cover covering the outer periphery of the ferrite core is formed integrally with a primary winding bobbin around which the primary coil is wound. ignition coil. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the synthetic resin cover covering the outer periphery of the ferrite core is divided into two parts, and the ferrite core is housed in a recessed part of the synthetic resin cover. 4. The ignition coil for an internal combustion engine according to claim 1, wherein the ferrite core has a cylindrical shape.