JP2002170727A - Method of manufacturing core of ignition coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an iron core for obtaining an ignition coil which has a high output power and a long service life and is inexpensive. SOLUTION: An ignition coil is equipped with a secondary coil wound on a secondary bobbin, a primary coil wound on a primary bobbin, an iron core which enables a magnetic flux induced by the primary coil to pass through, and another iron core positioned at an iron core insertion part which forms the primary coil or secondary coil. The ignition coil is housed in a case and sealed up with thermosetting synthetic insulating resin for the formation of an internal combustion engine ignition coil. The iron core of the internal combustion engine ignition coil is formed through a manner where a prismatic silicon steel plate laminate is formed into a column by machining. A plurality of steel bands of the same width of iron core material is laminated for forming the prismatic silicon steel plate laminate. When the steel bands are laminated, they are bonded together with adhesives, and the steel band laminate is cut in required length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil for supplying a high voltage to an ignition plug, and more particularly to an iron core.

[0002]

2. Description of the Related Art For an internal combustion engine, especially for an automobile, an ignition coil is required to have a small size and high characteristics in accordance with the miniaturization of the internal combustion engine. Conventionally, in a double overhead cam type internal combustion engine, an ignition coil that does not require a distributor is arranged in a space created between cylinder heads, and various plug-in type ignition coils have been put to practical use in other types of internal combustion engines. ing. However, such an ignition coil is also required to have additional values such as improved output characteristics and the incorporation of an igniter, and it is actually difficult to reduce the size of the ignition coil body. It has become difficult to arrange the coils in the limited space of the internal combustion engine, especially the cylinder head.

[0003] Under the circumstances described above, there have been proposed some types in which a part or all of an ignition coil is arranged in a space formed in a plug hole to which an ignition plug is attached. Generally, the outer diameter of a spark plug of an internal combustion engine for a vehicle is about 16 mm to 20 mm, and a plug hole into which the spark plug is inserted has an inner diameter of about 20 mm to 35 mm and a depth of about 100 mm.

FIG. 7 is a side view of a conventional plug-hole insertion type ignition coil, and FIG. 8 is a cross-sectional view of FIG. 7 and 8, the ignition coil 20 has a cylindrical shape according to the shape of the plug hole, and has a primary connector 26 for inputting a primary voltage and a case 2.
7 and the lower part of the case 27 is a plug hole 1
0, and the lower end is connected to the spark plug 30.
The primary and secondary coil portions are configured as shown in the sectional view of FIG. That is, a center iron core 23 disposed on the cylinder axis of the plug hole, and a secondary winding wound around the center iron core 23 and perpendicular to the longitudinal direction of the center iron core 23. 222 and a secondary winding 222
A primary winding 212 coaxially wound with the outer core 40 between the coils and the case 27;
As is well known, the secondary winding 222 is attached to a secondary bobbin 223,
Further, the primary winding 212 is wound around the primary bobbin 211, respectively. The central iron core 23 is formed by stacking a plurality of types of single plates having different widths in a multi-stage manner so as to form a circular shape, thereby improving the iron core occupancy.

[0005]

While a high-performance, trouble-free and low-priced automobile is desired, ignition coils are required to have higher output, longer life, and lower cost. Since the ignition coil having the above-described configuration uses an iron core that is stacked in multiple stages, the following problems occur in order to satisfy the requirements.
Since the iron core occupation ratio is less than 90% with respect to the perfect circular space in which the iron core inside the secondary bobbin is inserted, there is a problem that the voltage conversion efficiency is poor and a desired output voltage cannot be obtained.

In addition, in the case of an iron core in which a plurality of types of veneers having different widths are stacked in multiple stages, if the balance of the uniform arrangement of parts around the iron core is lost, concentration of an electric field and stress occurs due to a large number of steps and edges. Therefore, concentration of electrolysis causes dielectric breakdown, and concentration of stress causes cracks, resulting in a problem of shortening the life.

Further, in order to produce a plurality of types of veneers having different widths, a plurality of types of dies are required, and the yield (weight of the iron core / weight of the steel strip) is reduced when the veneers are produced by the dies. Since it is about 40%, there is a problem that the iron core becomes expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in an iron core for an ignition coil for supplying a high voltage to an ignition plug, an improvement in the occupancy of the iron core, elimination of steps and edges,
The purpose is to improve the yield.

[0009]

According to the present invention, there is provided a steel strip having the same width coated with an adhesive.
The laminated steel strip, which is integrally hardened with an adhesive by pressing and laminating so as to have the same diameter as when inserted into the inner diameter of the next bobbin, is cut into required lengths and cut into prismatic silicon steel plates. Form a laminate. Next, it was formed into a cylindrical shape by machining.

[0010] A plurality of strips, each of which is cut into the same width and coated with an adhesive, are laminated so that the lamination cross section becomes a square having a diameter dimension when inserted into the inner diameter of the secondary bobbin.
A prismatic silicon steel sheet laminated material integrally hardened by an adhesive under pressure is formed. Next, it may be formed into a cylindrical shape by machining and cut to a required length while being fixed by a fixing jig.

[0011]

1 is a side sectional view showing a state in which a cylindrical ignition coil manufactured by a method according to the present invention is mounted on an internal combustion engine. FIG. 2 is a view of the AA cross section of FIG. 1 as viewed in the direction of the arrow. 1 and 2, the ignition coil 20 includes a primary connector 26 for inputting a primary voltage and a case 27. The lower portion of the case 27 is embedded in the plug hole 10, and the lower end is connected to the ignition plug. . The primary and secondary coils and the iron core are configured as shown in the sectional view of FIG. That is, a center iron core 23 disposed on the cylinder axis of the plug hole, and a secondary winding wound around the center iron core 23 and perpendicular to the longitudinal direction of the center iron core 23. 222, and a primary winding 212 wound coaxially with the secondary winding 222 on the outer periphery. As is well known, the secondary winding 222 is wound on the secondary bobbin 223, and the primary winding 212 is wound on the primary bobbin 211, respectively. A first outer core 40 and a second outer core 42 are provided between the coils and the case 27.

FIGS. 3 and 4 show an apparatus for manufacturing an iron core 23 according to a first embodiment of the present invention. A plurality of silicon steel strips 70 coated with an adhesive having the same width as the length in the longitudinal direction of the iron core 23 are prepared, and a pressure is applied when a plurality of the steel strips are aligned by the roll 71 in a bundling process. The adhesive is solidified and integrated to form a laminated steel strip. And
By holding the jigs 73 and 74 and cutting them to a required length using a high-speed cutting machine 72, a prismatic silicon steel sheet laminate is formed.

Finally, an unnecessary portion is fixed by a fixing jig (not shown), and an unnecessary portion is cut off by a cutting or polishing machine to form a circular shape.

FIG. 3 and FIG. 4 show an apparatus for manufacturing an iron core 23 according to a second embodiment of the present invention. A plurality of silicon steel sheet strips 70, which are cut to the same diameter as when inserted into the inner diameter of the secondary bobbin and coated with an adhesive, are prepared, and a plurality of said strips are rolled in a bundling step. When aligned by 71, the adhesive is pressurized to solidify and integrate to form a prismatic silicon steel sheet laminate.

The prismatic silicon steel sheet laminate is transferred to a cutting or polishing machine 75, and unnecessary parts are cut off and processed into a circular shape. Finally, the iron core for the ignition coil is formed by holding the jigs 73 and 74 and cutting it to a required length using a high-speed cutting machine 72. With the above configuration, a series of operations can be performed simultaneously.

In this embodiment, each coil and the central iron core 23
Describes an ignition coil having a shape attached to the plug hole 10, but the ignition coil of the present invention can obtain the same effect not only in an ignition coil having such a shape but also in other ignition coils. It is.

[0017]

As described above, according to the present invention, the prismatic silicon steel sheet laminate is formed into a cylindrical shape by machining, so that the iron core occupancy becomes 90% to 98% of the conventional voltage. Conversion efficiency can be improved and a desired output voltage can be obtained. In addition, steps and edges are eliminated, and concentration of an electric field and concentration of stress can be prevented, thereby improving reliability and extending the life.

The prismatic silicon steel sheet laminate is formed by laminating a plurality of strips of iron core material having the same width, and bonding the strips with an adhesive to form a laminate strip. By cutting the laminated strip to a required length, a mold is not required, and equipment costs can be reduced. Further, in contrast to the conventional yield of 40%, in the present invention, only the portion removed by machining is lost, so that the yield can be improved to 70% or more, and the material cost can be reduced. .

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a state where an ignition coil according to an embodiment of the present invention is mounted on an internal combustion engine.

FIG. 2 shows a view of the ignition coil of FIG.

FIG. 3 is a schematic side view of an iron core manufacturing apparatus according to a first embodiment of the present invention.

FIG. 4 shows a schematic front view of the iron core manufacturing apparatus of FIG.

FIG. 5 is a schematic side view of an iron core manufacturing apparatus according to a second embodiment of the present invention.

FIG. 6 shows a schematic front view of the iron core manufacturing apparatus of FIG.

FIG. 7 is a side sectional view showing a state where a conventional ignition coil is attached to an internal combustion engine.

8 shows a view of the ignition coil shown in FIG.

[Description of References] In the drawings, the same reference numerals indicate the same or corresponding parts. DESCRIPTION OF SYMBOLS 10 Plug hole 20 Ignition coil 21 Primary coil 211 Primary bobbin 212 Primary winding 22 Secondary coil 222 Secondary winding 223 Secondary bobbin 23 Center iron core 40 Outer iron core 50 Thermosetting resin 60 Electric insulating sheet

Claims (6)

[Claims] 1. A secondary bobbin wound with a secondary coil, a primary bobbin wound with a primary coil, a center iron core through which magnetic flux induced by the primary coil passes, and a primary coil or a secondary coil A central iron core is provided in the central iron core insertion part formed by the core, and an outer core is provided on the outer periphery of the coil.The iron core of the cylindrical ignition coil housed in the case and molded of a thermosetting synthetic insulating resin has a prismatic shape. A method for producing an iron core for an ignition coil, characterized in that the silicon steel sheet laminated material is formed into a cylindrical shape by machining. 2. A secondary bobbin wound with a secondary coil, a primary bobbin wound with a primary coil, an iron core through which magnetic flux induced by the primary coil passes, and a primary coil or a secondary coil. Ignition characterized in that, in an iron core of an ignition coil having an iron core in an iron core insertion portion to be formed, a laminated steel strip is cut to a required length to form a prismatic silicon steel sheet laminated material. Manufacturing method of iron core for coil. 3. A secondary bobbin wound with a secondary coil, a primary bobbin wound with a primary coil, an iron core through which magnetic flux induced by the primary coil passes, and a primary coil or a secondary coil. In the iron core of an ignition coil having an iron core in an iron core insertion portion to be formed, a plurality of silicon steel strips of the same iron core material are laminated to form a laminated steel strip. Manufacturing method of iron core for ignition coil. 4. A secondary bobbin wound with a secondary coil, a primary bobbin wound with a primary coil, an iron core through which magnetic flux induced by the primary coil passes, and a primary coil or a secondary coil. When laminating a silicon steel strip coated with an adhesive with an iron core material of the same width in the iron core of an ignition coil having an iron core in the iron core insertion part to be formed, A method for producing an iron core for an ignition coil, wherein a laminated steel strip is formed by being integrally cured by an adhesive by pressure. 5. A secondary bobbin wound with a secondary coil, a primary bobbin wound with a primary coil, a center iron core through which magnetic flux induced by the primary coil passes, and a primary coil or a secondary coil In the core of the cylindrical ignition coil which is provided with the center iron core in the insertion part formed by the above and has the outer core on the outer periphery of the coil and is housed in the case and molded with thermosetting synthetic insulating resin, A plurality of strips of silicon steel plate, which are cut to the same width as the diameter when inserted into the inner diameter of the bobbin and coated with an adhesive, are laminated, and the pressure is applied during the lamination to integrally cure the adhesive. A method for manufacturing an iron core for an ignition coil, wherein the iron core is formed into a cylindrical shape by post-machining and then cut into a required length. 6. A method for manufacturing an iron core for an ignition coil, comprising combining two or more of the above-mentioned claims 1 to 4.