JPH0256910A - Core of ignition coil - Google Patents

Abstract

PURPOSE:To improve the workability when a permanent magnet provided in the magnetic circuit of a core is fixed by covering the circumference of the permanent magnet with thermoplastic resin or thermoplastic elastomer. CONSTITUTION:A core 4 is composed of an excitation part 7, a first closed magnetic path forming part 10, a second closed magnetic path forming part 11 and a permanent magnet 9. The circumferences of the excitation part 7, the first closed magnetic path forming part 10 and the permanent magnet 9 are covered with thermoplastic resin (or thermoplastic elastomer) 12 except the end parts of the excitation part 7 and the first closed magnetic path forming part 10 where the respective protrusions 7b and 10a are formed. The circumference of the second closed magnetic path forming part 11 is covered with thermoplastic resin (or thermoplastic elastomer) 12 except the parts which correspond to the end parts of the excitation part 7 and the first closed magnetic path forming part 10 where the respective protrusions 7b and 10a are formed. With this constitution, it is not necessary to use biscous adhesive and the workability when the permanent magnet is fixed can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an iron core of an ignition coil in which a permanent magnet is arranged in a magnetic circuit.

[Conventional technology] In recent years, permanent magnets that repel the magnetic flux of the primary coil have been placed in the magnetic circuit of the iron core to increase the amount of stored magnetic energy, improving ignition performance and making the ignition coil smaller and lighter. What is measured is devised.

An example of an ignition coil core provided with such permanent magnets is shown in FIG.

The iron core 100 has a primary coil 10 cast-impregnated on the outer periphery.
1 and the excitation part 103 to which the secondary coil 102 is attached.
03, an I-shaped second iron core 105 is provided to form an annular shape together with the first iron core 104.
A permanent magnet 1 is provided in the air gap formed between the Wit magnetic part 103 of the first iron core 104 and the second iron core 105.
It is configured by arranging 0G.

The first iron core 104, the second iron core 105, and the permanent magnet 106 are fixed by applying an adhesive to each joint surface.

[Problems to be Solved by the Invention] However, in the above-described iron core, the first iron core 104, the second iron core 105, and the permanent magnet 106 are bonded together after applying an adhesive to each joint surface of the first iron core 104, the second iron core 105, and the permanent magnet 106, respectively. iron core 105,
Then, the permanent magnet 106 is positioned and joined.

Therefore, due to the handling of viscous adhesives, it is difficult to automate the work process from applying the adhesive to each joint surface to joining the joints.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an iron core of an ignition coil with good workability when fixing a permanent magnet.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes an excitation section in which a coil and a secondary coil are once wound around the outer periphery and is excited by energizing the primary coil; A closed magnetic path forming part that closes the magnetic flux generated by the exciting part, and a permanent magnet disposed between the exciting part and the closed magnetic path forming part so as to repel the magnetic flux generated by the exciting part. As a technical means, in the iron core of the ignition coil, at least the periphery of the permanent magnet, together with the excitation part and the closed magnetic path forming part, is coated with thermoplastic resin or thermoplastic elastomer.

[Operations and Effects of the Invention] The present invention having the above-mentioned configuration is capable of forming an excitation part and a closed magnetic circuit forming part by coating the periphery of a permanent magnet disposed in a magnetic circuit of an iron core with a thermoplastic resin or a thermoplastic elastomer. A permanent magnet is fixed between them.

Therefore, there is no need to use a viscous adhesive, and the iron core on which the permanent magnets are arranged can be coated with thermoplastic resin or thermoplastic elastomer all at once. Therefore, since the workability when fixing the permanent magnet is good, it becomes possible to automate the work process and mass-produce it.

[Example] Next, the iron core of the ignition coil of the present invention will be described based on an example shown in the drawings.

FIG. 1 is a cross-sectional view of an ignition coil employing the iron core of the ignition coil of the present invention.

The ignition coil 1 of this embodiment is a closed magnetic circuit type ignition in which a primary coil 2 and a secondary coil 3 are integrally molded together with a core (iron core of the present invention) 4 in a coil case 6 using a casting resin 5 such as epoxy resin. This is coil 1.

The core 4 includes an excitation section 7 around which the primary coil 2 and the secondary coil 3 are wound, which is excited when the primary coil 2 is energized, and a closed magnetic path forming section 8 for closing the magnetic flux generated by the excitation section 7. , and a plate-shaped permanent magnet 9 disposed between the excitation section 7 and the closed magnetic path forming section 8 so as to repel the magnetic flux generated by the excitation section 7.

By arranging the permanent magnet 9 in the magnetic circuit of the core 4 as in this embodiment, the excitation part 7 is
Since the magnetic flux generated by the primary coil 2 is repelled by the magnetic flux generated by the permanent magnet 9, a large amount of magnetic energy can be stored in the core 4 even if the magnetic flux generated by the primary coil 2 is small, and therefore ignition performance can be improved. can.

The excitation part 1 is made by punching out a thin plate-like magnetic material (for example, soft iron) with oriented particles using a press or the like into a roughly T-shape, and then laminating a plurality of press-formed products and press-caulking them. Upper side) It has a wide and flat head 7a, and a convex portion 7b is formed at the other end.

The closed magnetic path forming section 8 includes a first closed magnetic path forming section 10 formed in a U-shape and a second closed magnetic path forming section 11 formed in a U-shape.
The excitation part 7 is arranged inside, and the first closed magnetic path forming part 10 and the second closed magnetic path forming part 11 are provided so that the outer periphery of the excitation part 7 forms an annular shape. Note that an air gap A is formed between the head 7a of the excitation section 7 and the first closed magnetic path forming section 10, in which the permanent magnet 9 is disposed.

The first closed magnetic path forming section 10 and the second recessive magnetic path forming section 11 are
Similar to the excitation part 7, a thin plate-like magnetic material with oriented particles is punched out into a substantially U-shape and an I-shape using a press or the like.
Thereafter, a plurality of press-formed products are laminated and press caulked, and convex portions 10a are formed at both ends of the first closed magnetic path forming portion 10, and excitation portions 7 are formed on the second closed magnetic path forming portion 11. Three recesses 11a are formed which fit into the projection 7b formed at the other end and the two projections 10a formed on the first closed magnetic path forming section 10.

The permanent magnets 9 are arranged within the above-mentioned near gap A so as to repel the magnetic flux generated when the excitation part 7 is excited, as shown in FIG. 2, that is, so that adjacent surfaces thereof have the same polarity. It is set up.

This plate-shaped permanent magnet 9 is disposed over the entire width of the head 7a of the excitation section 7, and uses rare earth magnets such as neodymium magnets and rare earth-cobalt magnets, which generate large magnetic force even in a thin shape. There is.

As shown in FIG. 1, the core 4 composed of the above-mentioned excitation section 7, first closed magnetic path forming section 10, second closed magnetic path forming section 11, and permanent magnet 9 is connected to the head 7a of the excitation section 7. With the permanent magnet 9 disposed between the first closed magnetic path forming section 10 and the excitation section 7 and the first closed magnetic path forming section 10, each of the convex portions 7
The excitation part 7 is formed by leaving only the end face where b and 10a are formed.
, the first locking magnetic path forming portion 1G, and the outer periphery of the permanent magnet 9 are coated with a thermoplastic resin (or thermoplastic elastomer) 12.

In addition, the second closed magnetic path forming section 11 is arranged so that the excitation section 7 and the first closed magnetic path forming section 10 have a portion opposite to the end surface where the convex portions 7b and 10a are formed, respectively. The outer periphery is coated with a thermoplastic resin (or thermoplastic elastomer) 12.

Then, the primary spool 13 in which the primary coil 2 is wound around the outer periphery of the excitation part 7 covered with the thermoplastic resin 12 and the secondary spool 14 in which the secondary coil 3 is wound are fitted, and the excitation part 7 and the 1 Each convex portion 7 of the closed magnetic path forming portion 10
A closed magnetic path is formed by fitting the concave portion 11a of the second closed magnetic path forming portion 11 into b and 10a.

Thereafter, the core 4 with the primary coil 2 and the secondary coil 3 attached thereto is housed in a coil case 6, and a casting resin 5 is injected and hardened to form the ignition coil 1 as shown in FIG.

In this way, the permanent magnet 9 disposed in the magnetic circuit of the core 4 is fixed by coating the periphery of the permanent magnet 9 with thermoplastic resin (or thermoplastic elastomer) 12. There is no need to use any agent, and the core 4 on which the permanent magnets 9 are arranged can be coated with the thermoplastic resin 12 all at once.

As a result, it becomes possible to automate the work process for fixing the permanent magnets 9 and mass-produce the cores 4 on which the permanent magnets 9 are arranged.

In addition, by covering the outer periphery of the core 4 with the thermoplastic resin 12, the casting resin 5 is injected and hardened to integrate the core 4, the primary coil 2, and the secondary coil 3 into the coil case 6. Even when molded, it is possible to prevent cracks from occurring due to heat shock caused by temperature changes.

Furthermore, by adjusting the temperature applied to the permanent magnet 9 when covering the core 4 with the thermoplastic resin 12, it is possible to omit heat treatment called heat drying, which is conventionally performed to stabilize magnetic properties. can.

In addition, by creating a structure in the mold that constitutes a closed magnetic circuit including the permanent magnet 9 during molding, the permanent magnet 9
It is possible to increase permeance and suppress demagnetization caused by heat during molding.

When the core 4 is housed in the coil case 6 and the casting resin 5 is injected and hardened as in this embodiment, since the outer periphery of the core 4 is coated with the thermoplastic resin 12 in advance, the primary coil The secondary coil 3 can be inserted into the coil case 6 in a state where it is assembled to the core 4.

Therefore, the opening of the coil case 6 when storing the core 4 with the primary coil 2 and the secondary coil 3 assembled has to have the size of the minimum projected area of the core 4 with the primary coil 2 and the secondary coil 3 assembled. If possible, the coil case 6 can be made smaller.

FIG. 3 shows a second embodiment of the present invention.

In this embodiment, the excitation part 7 is formed into a rectangular shape, and
One of the closed magnetic path forming portions (U-shaped) 15 of the closed magnetic path forming portion 8 which is divided into two parts, 1-shaped and U-shaped, is insert-molded in the coil case 6 in advance, and then the thermoplastic resin 12 is inserted into the coil case 6.
The other closed magnetic circuit forming section 16, excitation section 7, and permanent magnet 9 covered with are inserted into the coil case 6 later.

Therefore, one closed magnetic path forming section 15 has a thermoplastic resin 12.
However, when insert molding is performed in the coil case 6, the coil case 6 is covered with a resin film.

Moreover, since the primary spool 13 is fitted into the excitation part 7, no coating with the thermoplastic resin 12 is formed on the parts other than the part where the permanent magnet 9 is fixed.

Similarly to this second embodiment, the second closed magnetic path forming portion 11 shown in the first embodiment may be insert molded into the coil case 6.

FIG. 4 shows a third embodiment of the present invention.

In this embodiment, as shown in FIG. 4, the core 4 has an annular shape so that the excitation part 7 and the closed magnetic path forming part 8 form one magnetic loop.

(Modification) In the above-described ignition coil 1, since the entire outer circumferential portion of the core 4 is covered with the thermoplastic resin 12, the convex portions 7b and 10a of the excitation portion 7 and the first closed magnetic path forming portion 10 are When the concave portion 11a of the two closed magnetic path forming portions 11 are fitted together, water resistance can be ensured by joining the joint portion by means such as thermal welding or ultrasonic welding.

Therefore, in this embodiment, the ignition coil 1 is shown in which the core 4 equipped with the primary coil 2 and the secondary coil 3 is housed in the coil case 6, and the casting resin 5 is injected and hardened.
Even when used with the magnet exposed to the outside, there is no need to use cobalt-based magnets with excellent corrosion resistance or iron-based magnets with surface treatment, and relatively inexpensive magnets can be used.

Furthermore, since the outer periphery of the excitation part 7 to which the primary coil 2 and secondary coil 3 are attached is coated with thermoplastic resin 12, the spool for winding the coil can be eliminated and a fused wire can be used instead. can.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention. FIG. 1 is a cross-sectional view of an ignition coil employing the iron core of the ignition coil of the present invention, and FIG. 2 is a partial cross-sectional view of the ignition coil of the present invention. 3 is a sectional view of the iron core of an ignition coil showing a second embodiment of the present invention,
FIG. 4 is a cross-sectional view of an ignition coil core showing a third embodiment of the present invention, and FIG. 5 is a front view showing an example of the ignition coil core. In the diagram 2...Primary coil 3...Secondary coil 4...
- Core (iron core) 7... Excitation part 8... Closed magnetic path forming part 9... Permanent magnet 10... First closed magnetic path forming part 11... 217I magnetic path forming part 12... Heat Plastic resin (or thermoplastic elastomer) Figure 3

Claims (1)

[Scope of Claims] 1) An excitation part around which a primary coil and a secondary coil are wound, and which is excited when the primary coil is energized; and a closed magnetic circuit forming part that closes the magnetic flux generated by the excitation part. and a permanent magnet disposed between the excitation part and the closed magnetic path forming part so as to repel the magnetic flux generated by the excitation part, at least around the permanent magnet. An iron core for an ignition coil, characterized in that the excitation part and the closed magnetic path forming part are coated with a thermoplastic resin or a thermoplastic elastomer.