JPH09213543A - Ignition coil for internal combustion engines - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate structure of ignition coil having a satisfactory bond strength which is easy to form an inner core having a nearly circular section. SOLUTION: A primary coil 12 and secondary coil 22 are wound round an inner core 10 and housed in a hollow space of an outer core 30 housed in a case 60. The inner core 10 has a first and second members composed of magnetic flat sheets (Si steel strips MP) laminated in the sheet width reducing order and bonded by the stacking such that their broadside faces are bonded by the stacking (recesses Str are formed into one face of each flat sheet and protrusions Stp are formed on the other face thereof and driven into the recesses of the mutually opposed faces, thereby laminating the sheets one above another) to form nearly circular sections.

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 an internal combustion engine, and more particularly to an ignition coil for an internal combustion engine in which a primary coil and a secondary coil are mounted on a columnar member formed by laminating a plurality of magnetic flat plates.

[0002]

2. Description of the Related Art Recently, there has been a demand for further miniaturization of ignition coils for internal combustion engines, and as a core structure thereof, for example, a magnetic wire is used as disclosed in Japanese Patent Laid-Open No. 4-87311. It is known that a central iron core is formed by bundling. This is intended to form the ignition coil into a small cylindrical shape so as to be housed in the cylindrical plug hole of the engine.

In the publication, as a method of creating a central iron core,
A method of pulling out the wire through a round die, a method of filling the space made by the upper mold and the lower mold with the wire and then press-forming, aligning the wire, and a material with resin powder adhered to the surface of the metal powder, depending on the mold A method of pressing, a method of drawing a silicon steel tube in a die while installing a wire in the silicon steel tube and heating, and a method of winding a thin plate of silicon steel in a couple of layers and then drawing it in the die are disclosed. ing.
The publication also discloses, as an example, a center iron core in which wires are bundled in a cylindrical shape and both ends are squared.

[0004]

When the ignition coil is formed in a cylindrical shape as described in the above publication, a central core,
That is, it is desirable that the inner core is also formed in a cylindrical shape. As one of the means, there is a method of bundling a plurality of wire rods as described in the above publication, but both are difficult to manufacture and assemble,
This will increase costs.

On the other hand, when a plurality of steel plates are laminated to form a cylindrical core as in the prior art, for example, as shown in FIG.
The laminated structure is as shown in FIG. 20 and is fixed by stacking. That is, FIGS.
At 0, a concave portion is formed on one surface of each of the plurality of silicon steel plates MPx having different widths and a convex portion is formed on the other surface as the flat plate of the magnetic body. Then, these are sequentially pressed and laminated, and the convex portions and the concave portions of the opposite surfaces are fitted to each other to form the cylindrical inner core 10x having the stacking portion Stb formed therein. Hatching is omitted in the cross sections of FIGS. 18 and 20. Here, stacking means forming a concave portion on one surface and a convex portion on the other surface at the time of press molding for each of a plurality of flat plates, and forming a plurality of flat plates on the convex portions of the surfaces facing each other. Means to form a laminate by press-fitting into the recesses and sequentially polymerizing.

However, if a cylindrical inner core having a diameter of about 8 mm is formed by this method, the width of the outermost steel sheet becomes about 2 mm. For this reason, when a plurality of steel plates are to be joined by stacking, the diameter of the stacking portion becomes small, the joining strength of each layer becomes 2 kgf or less, and the sheets easily peel off. In addition, after stacking a wide steel plate on a narrow steel plate and sequentially widening it, it will be stacked so that the width will gradually decrease from the center part, but by stacking a wide steel plate on a narrow steel plate, Stacking causes bending in the longitudinal direction and makes stacking difficult. For this reason, press working by the progressive die cannot be performed, which not only lowers workability but also increases cost.

Therefore, the present invention is an ignition coil for an internal combustion engine in which a primary coil and a secondary coil are mounted on a magnetic columnar member, and a columnar member having a substantially circular cross section can be easily formed with a laminated structure having sufficient bonding strength. An object is to have a structure that can be formed.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a primary coil and a secondary coil are wound around a columnar member made of a magnetic material and housed in a hollow portion of a cylindrical member made of a magnetic material. In an ignition coil for an internal combustion engine in which the cylindrical member is housed in a cylindrical container, the columnar member is formed by stacking a plurality of flat plates of magnetic material in the order in which the widths of the flat plates are gradually reduced and joining them by stacking. It has a member, and the plate surfaces on the wide side of each of the first and second members are joined by stacking to form a substantially circular cross section. Thus, an ignition coil for an internal combustion engine, which is a laminated body of a plurality of magnetic flat plates, is provided with a columnar member having a substantially circular cross section in which the respective layers are firmly joined.

Of the plurality of flat plates constituting the first and second members, at least each of the flat plates facing the first and second members is provided with a plurality of holes and a plurality of holes are formed. It is preferable that the stacking portion is formed so that the convex side of the stacking portion fits into the hole when the first and second members are joined.

It is desirable that the plurality of holes and the stacking portion formed on the flat plate have a rectangular shape in plan view.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an ignition coil for an internal combustion engine of the present invention will be described below with reference to the drawings. FIG. 12 shows an ignition coil for an internal combustion engine according to an embodiment of the present invention. A case 60 includes an igniter portion 60d of a casing having an opening at the top, and a cylindrical coil portion extending downward from the bottom surface thereof. It is a container-like housing made of synthetic resin having 60a and a plug cap portion 60b. FIG. 1 shows a coil section 60.
2 is a view showing only a and omitting other parts, and FIG. 2 is a view showing a cross section taken along the line AA of FIG.

As shown in FIG. 1, the coil portion 60a has an inner core 10 which is a columnar member of the present invention, a primary bobbin 11 and a primary coil 12 integrally molded with the inner core 10, a secondary coil assembly 20, and a cylindrical member of the present invention. Outer core 30,
And a pair of auxiliary cores and permanent magnets (representatively 4
(Represented by 0,50). An igniter (not shown) is housed in the igniter portion 60d shown in FIG. 12, and a connector portion 60c is integrally formed. The igniter controls the primary current of the primary coil 12 and is also called an ignition module.

The inner core 10 is composed of a plurality of magnetic flat plates,
That is, silicon steel plates (representatively represented by MP) are laminated and configured as shown in FIGS. As shown in FIG. 10, these silicon steel plates MP are formed such that the width of each of the silicon steel plates MP arranged on both sides to the silicon steel plate MP arranged in the center gradually increases, and these are laminated. And the intermediate portion becomes a columnar member having a substantially circular cross section with a diameter of about 8 mm. On the other hand, the end faces of the end portions on both sides are rectangular as shown in FIG. 8, and have a larger cross-sectional area than the cross section of the intermediate portion. Each silicon steel plate MP has a concave portion formed on one surface and a convex portion formed on the other surface at the time of press forming, and then sequentially pressed and laminated to form a stacking portion.

As shown in FIGS. 5 and 6, the inner core 10 is formed by joining a pair of inner core members 10a, 10a, which are the first and second members of the present invention, to the outermost side (for example, FIGS. 5 and 6). The outer peripheral silicon steel plate MPt arranged at the uppermost stage of the upper inner core member 10a in FIG. 6 is formed in the shape shown in FIG. 3, and is formed on the center side (for example, in the lower inner core member 10a in FIGS. The central silicon steel plate MPc arranged in the uppermost stage is formed in the shape shown in FIG. That is, in the former, the middle portion Mtb is set to have the smallest width as compared with the both ends Mta, and in the latter, the middle portion Mcb is set to the largest width (however, smaller than the both ends Mca). The silicon steel plate MP interposed between them has the outer peripheral side silicon steel plate MPt and the center shown in FIGS. 3 and 4 such that the width of the intermediate portion at the interposed position gradually decreases from the center side toward the outer peripheral side. Two or three silicon steel plates MP having the same shape and having a similar shape to the side silicon steel plate MPc are stacked.

The outer peripheral side silicon steel plate MPt shown in FIG. 3 is provided with two holes Hbt having a rectangular shape in plan view and four stacking parts St (hereinafter, the convex part is represented by Stp and the concave part is represented by Stp).
(represented by tr) is formed, and the concave portion Str side is shown in FIG. Further, the center side silicon steel plate MPc shown in FIG.
Two holes Hbc having a rectangular shape in a plan view and two holes Hsc smaller than the rectangular hole are bored in the hole. Two stacking parts St are formed, and the convex part Stp side is shown in FIG. The hole Hbc has the same shape as the hole Hbt shown in FIG. 3, and both are fitted with the convex portion Stp side of the stacking portion St to be joined, and are integrated by frictional engagement between their contact surfaces (side surfaces). On the other hand, in the hole Hsc of FIG. 4, the tip of the convex portion Stp of the stacking portion St does not come into contact with the surface of the silicon steel sheet MP to be joined, and the tip of the convex portion Stp does not protrude from the opposite surface. Thus, the convex portion Stp is accommodated and frictional engagement is performed on the contact surface.

First, the center side silicon steel plate MPc shown in FIG.
After stacking three sheets, each convex portion Stp is press-fitted into each concave portion Str and joined by stacking. Of three identical-shaped silicon steel plates MP having a narrow intermediate portion are sequentially joined by stacking, and further three identical-shaped silicon steel sheets MP having a narrower intermediate portion are sequentially joined by stacking, and Further, two silicon steel plates MP having the same shape and having a narrow width in the middle portion are sequentially joined by stacking. When two outer peripheral side silicon steel plates MPt having the minimum width intermediate portion Mtb shown in FIG. 3 are sequentially joined thereto by stacking, a total of 13 silicon steel plates MPt shown in FIGS. 5 and 6 are obtained.
The inner core member 10a having a substantially semicircular cross section is formed. The pair of inner core members 10a, 10a are arranged so that their center-side silicon steel plates MPc sides face each other as shown in FIGS. 5 and 6 of the cross section taken along the line BB in FIG. If they are rotated 180 degrees with respect to each other and press-contacted to each other, the stacking portion St has a hole H at the convex portion Stp side.
fit to bc.

Thus, in this embodiment, as shown in FIG. 9, the plurality of silicon steel plates MP adjacent to each other are joined by the stacking portions St at a total of four positions. The stacking portion St has a rectangular shape in plan view as apparent from FIGS. 3 and 4, and is fitted into the hole Hbt (or Hbc) as shown in FIG. Becomes In the present embodiment, the side surface shape of the convex portion Stp is triangular (V-shaped), but it may be another shape such as a semicircle. As described above, since the side area of the convex portion Stp of the stacking portion St is large and the contact area with the concave portion Str or the holes Hbt and Hbc is large, a bonding strength of 2 kgf or more can be secured. 5 and 6, the inner core 1
The hatching of the 0 cross section is omitted because it is difficult to distinguish the drawings.

A primary bobbin 11 is integrally formed on the outer surface of the inner core 10 with a synthetic resin, and the winding of the primary coil 12 is wound in two or four layers on the outer peripheral surface of the primary bobbin 11. And the secondary coil assembly 20 is arrange | positioned so that these may be surrounded. The secondary coil assembly 20 includes a secondary bobbin 21 and a secondary coil 22.
Is wound. The secondary bobbin 21 is a resin cylindrical body in which a plurality of collar portions 21a are formed at predetermined intervals in the axial direction, and the secondary coil 22 is provided in a plurality of annular grooves formed between the collar portions 21a. The windings are sequentially wound.

On the other hand, the outer core 30 forming a magnetic circuit together with the inner core 10 is cylindrically formed of a silicon steel plate as shown in FIGS. 1 and 2, and is housed in close contact with the inside of the coil portion 60a of the case 60. Has been done. Further, as shown in FIGS. 1 and 2, rectangular permanent magnets 50 are arranged at both ends of the inner core 10 in the axial direction, and an auxiliary core 40 formed by laminating substantially rectangular silicon steel plates on the outer side thereof. (Hatching is omitted in FIG. 1). The permanent magnets 50 arranged at both ends are arranged such that the directions of the generated magnetic fluxes are the same and are opposite to the direction of the magnetic flux formed in the inner core 10 when the primary coil 12 is energized. . Thus, the inner core 10, the permanent magnet 50, the auxiliary core 40, and the outer core 3 described above.
A magnetic circuit is constituted by 0s.

In manufacturing and assembling the ignition coil having the above structure, first, as described above, a plurality of (for example, 13
A plurality of silicon steel plates MP (for example, thickness 0.3 mm) are joined by stacking to form a pair of inner core members 10
When a and 10a are configured and the plate surfaces on the wide side are joined, the inner core 10 having the ends on both sides of the large cross section and the intermediate portion of the small cross section is formed as shown in FIG. Then, as shown in FIG. 1, the primary bobbin 11 is integrally formed on the outer surface of the inner core 10, and the winding of the primary coil 12 is wound around the primary bobbin 11.

On the other hand, the outer core 30 is formed of a silicon steel plate into a cylindrical shape, and is inserted or press-fitted into the coil portion 60a of the case 60. Further, the secondary coil 22 is wound around the secondary bobbin 21 to form the secondary coil assembly 20. Then, the primary bobbin 11 and the inner core 1 in which the primary coil 12 is wound inside the hollow portion of the secondary bobbin 21.
0 is accommodated, and both ends of the primary bobbin 11 are the secondary bobbin 2
It is arranged so as to be fitted to the inner surface of the hollow portion 1.

Further, after the permanent magnets 50 and the auxiliary cores 40 are attached to both ends of the inner core 10 in the axial direction, the inner core 10, the secondary coil assembly 20 and the like are housed in the outer core 30. An igniter (not shown) is housed in the igniter portion 60d of the case 60,
Both ends of the winding of the primary coil 12 are electrically connected to the igniter. On the other hand, one end of the winding of the secondary coil 22 is grounded and the other end is connected to a high voltage terminal (not shown).

Thereafter, the coil portion 60a and the igniter portion 60d are filled with a thermosetting synthetic resin, for example, an epoxy resin, and cured to form a resin portion 13 in the coil portion 60a as shown by a dotted line in FIG. (Not shown in the igniter portion 60d). As a result, the primary coil 12 and the secondary coil 22 are impregnated and fixed, and the electrical connection portion is appropriately insulated, and further, the insulating property capable of withstanding the high output voltage of the secondary coil 22 is secured. The coil portion 60a and the plug cap portion 60b shown in FIG. 12, the igniter portion 60d and the connector portion 60c are formed as separate bodies,
The coil portion 60a and the igniter portion 60d may be joined together.

The internal combustion engine ignition coil 1 is shown in FIG.
A plug socket (not shown), which has the outer shape shown in FIG. 2 and is formed in a cylindrical shape by an insulating material (for example, rubber), is attached to the outside of the coil portion 60a and the plug cap portion 60b. Then, it is mounted on an internal combustion engine (not shown) and connected to a spark plug (not shown). When the primary current of the primary coil 12 is interrupted in this state, a counter electromotive force is induced in the secondary coil 22 to generate a high voltage of 30 to 40 kv, which is output to the ignition plug. As a result, spark discharge occurs in the electrode portion of each ignition plug, and the compressed air-fuel mixture in each combustion chamber (not shown) is ignited.

As described above, the inner core 10 of the ignition coil 1 for an internal combustion engine has a plurality of silicon steel plates MP stacked and a sufficient joining strength is secured by the stacking portion St. As a result, the entire cross section of the middle portion of the inner core 10 can be a magnetic circuit, and the effective magnetic flux density can be increased by the end portion having the enlarged cross section. Therefore, the cross-sectional area of the inner core 10 can be reduced while maintaining a predetermined ignition performance, and the entire device can be made small.

FIGS. 13 to 16 show another embodiment of the inner core according to the present invention. In this embodiment, the holes are formed only in the central silicon steel plate MPc.
The other silicon steel plates MP are formed with stacking parts St at four places without forming holes. That is, the holes Hbc and Hsc are formed by the pair of inner core members 10a and 10a.
It is necessary to join a, but the hole Hbt is not necessary for joining by stacking of the silicon steel plates MP with each other, so that this is omitted. The other configurations are similar to those of the embodiment shown in FIGS.

[0027]

Since the present invention is configured as described above, the following effects can be obtained. That is, the ignition coil for an internal combustion engine of the present invention has first and second members obtained by stacking a plurality of magnetic flat plates in the order in which the widths of the flat plates are gradually reduced and joining them by stacking. Since the wide plate surfaces of the two members are joined by stacking to form a substantially circular cross section, the columnar member is formed to have a substantially circular cross section, and a laminated structure having sufficient joining strength is obtained. In addition, the magnetic flux generated through the columnar member can be effectively used. Thus, a small ignition coil having a predetermined ignition performance can be easily manufactured.

According to a second aspect of the present invention, at least each of the flat plates on which the first and second members face each other is provided with a plurality of holes, and a plurality of stacking portions are formed, If the convex portion side of the stacking portion is arranged to be fitted into the hole when the first and second members are joined, the first and second members have the same shape and are easily joined. You can Further, as described in claim 3, the plurality of holes and the stacking portion formed in the flat plate have a rectangular shape in a plan view, so that they can be firmly joined.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a coil portion of an ignition coil for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a coil portion of an internal combustion engine ignition coil according to an embodiment of the present invention.

FIG. 3 is a plan view of an outer peripheral silicon steel plate forming an inner core according to an embodiment of the present invention.

FIG. 4 is a plan view of a center-side silicon steel plate forming an inner core according to an embodiment of the present invention.

FIG. 5 is a side view of a pair of inner core members according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view of a pair of inner core members according to an embodiment of the present invention.

FIG. 7 is a plan view of the inner core according to the embodiment of the present invention.

FIG. 8 is a vertical cross-sectional view of an inner core according to an embodiment of the present invention.

FIG. 9 is a side view of the inner core according to the embodiment of the present invention.

FIG. 10 is a cross-sectional view of an inner core according to an embodiment of the present invention.

FIG. 11 is a perspective view showing a stacking portion of a pair of inner cores according to the embodiment of the present invention.

FIG. 12 is a perspective view of an internal combustion engine ignition coil according to an embodiment of the present invention.

FIG. 13 is a plan view of an inner core according to another embodiment of the present invention.

FIG. 14 is a vertical cross-sectional view of an inner core according to another embodiment of the present invention.

FIG. 15 is a side view of an inner core according to another embodiment of the present invention.

FIG. 16 is a cross-sectional view of an inner core according to another embodiment of the present invention.

FIG. 17 is a plan view of an inner core formed in a substantially circular cross section by stacking silicon steel plates.

FIG. 18 is a vertical cross-sectional view of an inner core formed in a substantially circular cross section by stacking silicon steel plates.

FIG. 19 is a side view of an inner core formed in a substantially circular cross section by stacking silicon steel plates.

FIG. 20 is a cross-sectional view of an inner core formed in a substantially circular cross section by stacking silicon steel plates.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ignition coil for internal combustion engine 10 Inner core (columnar member) 10a Inner core member (first and second members) 11 Primary bobbin 12 Primary coil 13 Resin part 20 Secondary coil assembly 21 Secondary bobbin 22 Secondary coil 30 Outer core (cylindrical) Member) 40 auxiliary core 50 permanent magnet 60 case (cylindrical container)

Claims (3)

[Claims] 1. An ignition coil for an internal combustion engine, wherein a primary coil and a secondary coil are wound around a magnetic columnar member, housed in a hollow portion of a magnetic cylindrical member, and the cylindrical member is housed in a cylindrical container. In the above, the columnar member has first and second members obtained by stacking a plurality of flat plates of magnetic material in the order in which the widths of the flat plates are gradually reduced and joining them by stacking, and each of the first and second members is An ignition coil for an internal combustion engine, characterized in that the wide plate surfaces are joined by stacking to form a substantially circular cross section. 2. A plurality of holes are bored in at least each of the flat plates which the first and second members face each other among the plurality of flat plates which form the first and second members. ,
2. The internal combustion engine according to claim 1, wherein a plurality of stacking parts are formed, and the stacking parts are arranged such that the convex side of the stacking parts fits into the holes when the first and second members are joined. Ignition coil. 3. The ignition coil for an internal combustion engine according to claim 2, wherein the plurality of holes and the stacking portion formed in the flat plate have a rectangular shape in plan view.