JPH09246070A - Ignition coil of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil which increased spark energy output and is excellent in durability without using plastic cylinder case. SOLUTION: This ignition coil has a plastic front cylinder 8 having a high voltage terminal 9 on its closed front end, a plastic rear cylinder 11 having a primary terminal 13, a multiwall hollow cylinder 16 also serving as a clad core formed by multi-layered cylindrical magnetized metal sheet, and an open magnetic-circuit core 3 fitted on its outskirts with a bobbin 20 wound with either a primary coil 1 or secondary coil 2. The front end of the multi wall hollow cylinder 16 is fitted on to the front cylinder 8, and a rear end to the rear cylinder 11, so that the open magnetic-circuit core 3 having another coil on its outskirts is put in the center of a multiwall hollow cylinder 16 also serving as a clad core. The other coil is concentrically wound additionally on it; the secondary coil is connected to the high voltage terminal 9, and the primary coil 1 to the primary terminal, and thermally hardened insulation resin is filled into the interior of the front cylinder 8, the interior surrounded by the multiwall hollow cylinder 16 also serving as a clad core, and the interior of the rear cylinder 11, so that the open magneticcircuit core, the primary coil, and the secondary coil are fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug which is inserted into a plug hole provided in each cylinder of an engine, and a high voltage terminal is electrically connected to a head terminal of the spark plug at the bottom of the plug hole. The present invention relates to an elongated tubular ignition coil that applies a high voltage.

[0002]

2. Description of the Related Art As a spark plug used in this way,
An open magnetic circuit core is formed in the center of an elongated cylindrical case made of resin having a high voltage terminal at the closed front end and having a wall thickness of 0.8 to 1 mm, and a primary coil is wound around the core to form a resin wall thickness of 0. 8 ~
A primary bobbin of about 1 mm and a resin-made secondary bobbin wound with a secondary coil with a thickness of about 0.8 to 1 mm are concentrically provided, and a silicon steel plate or the like is formed on the inner peripheral surface of the cylindrical case. A magnetic metal plate is wound in a cylindrical shape and fitted with an outer core, and an open magnetic circuit core and a primary coil wound around a primary bobbin are inserted into a thermosetting insulating resin layer cast in this cylindrical case. The one with the secondary coil wound on the secondary bobbin and the outer iron core fixed is the actual flat blade 5.
It is known from JP-A-21423. In this way, the ignition coil inserted into the plug hole of the engine and attached is
Since the inner diameter of the plug hole is small, the outer diameter of the resin cylindrical case is limited to 22 to 24 mm, and the spark energy output of the ignition coil to the ignition plug is limited to about 20 mJ.

[0003]

The outer core fixed along the inner peripheral surface of the resin cylindrical case has a thickness of 0.
Since the silicon steel plate of about 35 to 0.5 mm is wound only once in a cylindrical shape, the magnetic shielding effect of the outer iron core is small, and when used, magnetic flux leaks into the engine plug hole and eddy current is generated in the plug hole. The spark energy of the spark plug due to the flow of the ignition coil was attenuated to reduce the efficiency. Therefore, the mixture of gasoline, which is the fuel of the engine, is operated near the ideal mixture, and it is practical for a normal engine that does not require much spark energy of the spark plug by the ignition coil, but it is practical, However, it has not been put to practical use for an engine that requires about 40 mJ of spark energy for an ignition plug of an ignition coil such as an alternative fuel engine. Further, a high-pressure corona is generated every time spark discharge occurs in the gap between the outer core and the plug hole, and the insulation of the resin cylindrical case deteriorates during long-term use, and there is a risk of misfire.

[0004]

In view of the above, the present invention uses an inner-outer multi-wall hollow cylinder having a cylindrical magnetic metal plate, for example, a plurality of silicon steel plates inside and outside, in close contact with each other instead of a resin cylindrical case. It also serves as an outer core, thereby improving the magnetic shield effect by increasing the cross-sectional area of the outer core and obtaining an ignition coil that makes spark spark energy higher than that of a conventional ignition coil with the same outer diameter. Of.

[0005]

Therefore, an ignition coil according to claim 1 of the present invention comprises a resin front cylinder having a high voltage terminal at a closed front end, a resin rear cylinder having a primary terminal, and a cylindrical shape. An inner and outer multi-walled hollow cylinder having a plurality of magnetic metal plates inside and outside and also serving as an outer core, and an open magnetic circuit core having a bobbin wound with either one of a primary coil and a secondary coil fitted on the outer periphery. A front end portion of the inner-outer multi-wall hollow cylinder is fixed to the front cylinder, the rear end portion is fitted and fixed to the rear cylinder, respectively, and the one of the one of the inner and outer multi-wall hollow cylinders also serving as the exterior iron core is fixed. An open magnetic circuit core having a coil on the outer circumference is arranged, and the other coil is concentrically provided outside the core, and the secondary coil is connected to the high-voltage terminal and the primary coil is connected to the primary terminal. Inside, the inside surrounded by a multi-wall hollow cylinder that also serves as the exterior iron core,
Also, the inside of the rear tube is filled with a thermosetting insulating resin, and the open magnetic circuit core, the primary coil and the secondary coil are fixed in the insulating resin layer. An ignition coil according to a second aspect of the present invention has a resin front cylinder having a high voltage terminal at a closed front end, a resin rear cylinder having a primary terminal, and a plurality of cylindrical magnetic metal plates inside and outside. It has an inner / outer multi-wall hollow cylinder that also serves as an outer core and an open magnetic circuit core in which a thin heat-resistant insulating sheet is wound around the outer periphery and one of the primary coil or the secondary coil is wound around it. The front end of the inner-outer multi-wall hollow cylinder is fixed to the front cylinder, and the rear end is fitted and fixed to the rear cylinder, and the one coil is provided on the outer circumference at the center of the inner-outer multi-wall hollow cylinder that also serves as the outer core. An open magnetic circuit core is provided and the other coil is concentrically provided outside the core, and the secondary coil is connected to the high-voltage terminal and the primary coil is connected to the primary terminal. Thermosetting insulation inside the inner and outer multi-wall hollow cylinders that also serve as the iron core and inside the rear cylinder Filled with fat, to an open magnetic path iron core in the insulating resin layer, characterized in that fixed to the primary coil and the secondary coil. And
In both the case of the ignition coil of claim 1 and the case of the ignition coil of claim 2, it is preferable to provide a plurality of openings in at least the innermost layer of the inner and outer multi-walled hollow cylinder also serving as the outer core made of a magnetic metal plate.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In each of the illustrated embodiments, 1 is a primary coil,
Reference numeral 2 indicates a secondary coil, and 3 indicates an open magnetic circuit core. Open magnetic circuit core 3
In FIG. 2 and FIG. 4, a large number of strip-shaped silicon steel plates 3 ′ are laminated so that their cross-sectional shapes are close to a circular shape.
For example, one silicon steel plate may be wound in a spiral shape and wound into a predetermined diameter.

Reference numeral 4 denotes a primary coil or a secondary coil 2 on the outer circumference.
Is a synthetic resin bobbin cylinder having a wall thickness of about 0.8 to 1 mm, and this bobbin cylinder 4 has an elongated cylindrical shape with a front end closed and a rear end open, and a forward-facing projection 5 at the center of the front end. , Has a concave portion 6 facing rearward, and a plurality (3 in the figure
6), the protruding pieces 7 radially protrude (see FIG. 6A). The rearward-facing concave portion 6 described above is inserted with the front end portion of the open magnetic circuit core,
This is for concentrically positioning the front end of the open magnetic circuit core 3 in the cylinder.

Reference numeral 8 denotes a synthetic resin front tube having a high voltage terminal 9 attached to the center of the closed front end, and a receiving tube 10 for receiving the forward projection 5 of the bobbin tube at the center of the closed front end.
Is equipped backwards. Reference numeral 11 denotes a synthetic resin rear cylinder in which a primary terminal and an earth terminal 13 are penetratingly attached to a connector portion 12 projecting from the outer periphery of the rear portion, and as shown in FIG. 6B, the rear end of the open magnetic circuit core is centered inside. A support cylinder 14 is provided that fits and holds the parts concentrically. The support cylinder 14 is integrally supported inside the rear cylinder by a protrusion 14 ′ that protrudes radially inward from the inner circumference of the rear cylinder.

Reference numeral 16 designates a magnetic metal plate, for example, an inner / outer multi-wall hollow cylinder having a plurality of non-oriented or directional silicon steel plates 16 'inside and outside and also serving as an exterior core. As shown in FIGS. 2 (A) and 4 (A) A, the inner / outer multi-wall hollow cylinder 16 is formed by closely adhering a silicon steel plate having a thickness of about 0.35 to 0.5 mm to a cylindrical shape 2 to 4 times. By spirally winding the coil, the shield effect is enhanced, the attenuation of the output energy of the ignition coil is significantly reduced, and the efficiency is improved. Further, if a silicon steel sheet having a low loss of about 0.1 mm is used and closely wound about 10 to 15 times and wound in a spiral shape, the efficiency is further enhanced.
The end of the winding start and the end of the winding of the silicon steel plate closely wound can be fixed only by the binding force of the winding, but if necessary, they may be fixed by welding or adhesion.

As shown in FIGS. 2 (B) and 4 (B), the inner / outer multi-wall hollow cylinder 16 also serving as the outer iron core has a diameter of one thin silicon steel plate rolled into a cylindrical shape. A plurality of different cylindrical bodies 16a, 16b, 16c ... Are closely attached to the inner and outer multiple layers, with the smaller diameter inside and the larger diameter outside, and the opposing seams 16 of the silicon steel plates of each cylindrical body.
It is also possible to shift and fit d in the circumferential direction to be fitted.

The plurality of projecting pieces 7 radially protruding from the outer periphery of the rear end of the bobbin cylinder 4 come into contact with the inner periphery of the inner / outer multi-wall hollow cylinder 16 which also serves as the outer core, and the rear end of the bobbin cylinder. Is positioned concentrically with respect to the inner and outer multi-wall hollow cylinder 16.

The front end portion of the front cylinder 8 and the inner / outer multi-wall hollow cylinder 16 which also serves as the outer core, and the rear end portion and the rear cylinder 11 are described.
In order to assemble the above, in each of the illustrated embodiments, the outer circumference of the rear end of the front tube and the inner circumference of the front end of the rear tube are fitted with the inner circumference of the front end of the inner-outer multi-wall hollow cylinder and the outer circumference of the rear end. There are provided annular step portions 8'and 11 'which come into contact with each other.

In the embodiment of claim 1 shown in FIGS. 1 and 2, a bobbin 20 made of synthetic resin and having a primary coil 1 wound around the outer periphery of the open magnetic circuit core 3 and having a wall thickness of about 0.8 to 1 mm. Although not shown, the secondary coil 2 is wound around the outer circumference of the bobbin cylinder 4 by fitting.

In order to assemble the ignition coil according to the first embodiment shown in FIGS.
Is inserted into the receiving cylinder 10 of the front cylinder 8, the high-voltage end of the secondary coil is electrically connected to the high-voltage terminal 9 of the front cylinder, and the front end of the inner / outer multi-wall hollow cylinder 16 also serving as the exterior iron core is moved forward. It fits until it contacts the annular stepped portion 8'on the outer periphery of the rear portion of the barrel, and if necessary, adheres and fixes it. Then, the open magnetic circuit core 3 and the primary coil wound around the core 3 via the bobbin 20 are attached to the bobbin cylinder 4
While inserting the front end of the open magnetic circuit core into the concave portion 6 of the bobbin cylinder while inserting the rear part of the open magnetic circuit core into the support cylinder 14 of the rear cylinder, The outer periphery is fitted until it comes into contact with the annular stepped portion 11 'of the rear cylinder, and if necessary, adhered and fixed. As a result, the radial protruding piece 7 at the rear end of the bobbin cylinder having the secondary coil wound around the outer circumference comes into contact with the inner circumference of the hollow portion of the inner-outer multi-wall hollow cylinder. Then, the electric wire of the primary coil or the electric wire attached to the inner / outer multi-wall hollow cylinder is passed through the notch 15 provided in the rear cylinder to electrically connect to the primary terminal or the ground terminal 13.

In this way, the open magnetic circuit core 3 having the primary coil provided on the outer periphery via the bobbin 20, the bobbin cylinder 4 having the secondary coil on the outer periphery, and the inner and outer multi-wall hollow cylinder 1 also serving as the outer core.
6, the front cylinder 8 and the rear cylinder 11 are held concentrically, so a thermosetting insulating resin such as epoxy resin is vacuum-cast from the inside of the rear end of the rear cylinder 11. As a result, the resin flows into the bobbin cylinder 4 later, and the inner circumference of the bobbin cylinder, the primary coil 1,
The space between the open magnetic circuit core 3 and the support cylinder 14 is filled and solidified, and the inside of the front cylinder 8 and the inside / outside multi-wall hollow cylinder 16 are passed through the space between the radial projecting pieces 7, 7 at the rear end of the bobbin cylinder. Between the circumference and the bobbin cylinder, the secondary coil, and the interior of the rear cylinder 11 is filled and solidified, and the resin layer 18 thus solidified forms the open magnetic circuit core and the primary coil, the bobbin cylinder and the secondary coil, the front cylinder, The rear cylinder and the inner and outer multi-wall hollow cylinders that also serve as the outer core are fixed concentrically.

In the embodiment of the ignition coil according to claim 1 of FIGS. 1 and 2, the primary coil is wound around the outer circumference of the bobbin 20 fitted in the open magnetic circuit core 3, and is dividedly wound around the outer circumference of the bobbin cylinder 4. Although the secondary coil 2 is wound, conversely, the secondary coil may be wound around the outer circumference of the bobbin 20 fitted in the open magnetic circuit core by split winding, and the primary coil may be wound around the outer circumference of the bobbin cylinder. .

In the embodiment of the ignition coil according to claim 2 shown in FIGS. 3 and 4, the heat resistant insulating sheet 21 is wound once or several times in the middle of the length of the open magnetic circuit core 3 to insulate the insulation. The primary coil 1 is wound on the sheet 21. As the heat resistant insulating sheet 21, it is preferable to use a sheet having a thickness of about 0.1 mm, for example, a glass fiber base material impregnated with an epoxy resin.

The secondary coil 2 is wound around the outer circumference of the bobbin cylinder 4 by split winding (not shown).

In order to assemble the ignition coil according to the second embodiment of the present invention shown in FIGS. 3 and 4, the front projection 5 of the bobbin cylinder is inserted into the receiving cylinder 10 of the front cylinder 8, and the high voltage end of the secondary coil is connected. It is necessary to electrically connect to the high voltage terminal 9 of the front cylinder and fit the front end of the inner / outer multi-wall hollow cylinder 16 also serving as the exterior iron core until it comes into contact with the annular stepped portion 8 ′ of the rear outer circumference of the front cylinder. Then glue and fix. Then, an insulating sheet is wound around the outer periphery, and the open magnetic circuit core 3 having the primary coil wound thereon is inserted into the bobbin cylinder 4 from the rear side, and the front end portion thereof is inserted into the recess 6 of the bobbin cylinder and is opened. The rear part of the magnetic core is provided with a rear support tube 14
While being put inside, the outer periphery of the rear portion of the inner-outer multi-wall hollow cylinder is fitted until it comes into contact with the annular stepped portion 11 'of the rear cylinder, and if necessary, adhered and fixed. As a result, the radial protruding piece 7 at the rear end of the bobbin cylinder 4 contacts the inner circumference of the hollow portion of the inner-outer multi-wall hollow cylinder. Then, the electric wire of the primary coil or the electric wire attached to the inner / outer multi-wall hollow cylinder is passed through the notch 15 provided in the rear cylinder to electrically connect to the primary terminal or the ground terminal 13.

In this way, the bobbin cylinder 4 and the secondary coil, the inner and outer multi-wall hollow cylinder 16 also serving as the outer core, the front cylinder 8 and the rear cylinder 1 with respect to the open magnetic circuit core 3 having the primary coil provided on the outer periphery thereof.
Since 1 is kept concentric, thermosetting insulating resin such as epoxy resin is vacuum-molded from the inside of the rear end of the rear tube 11.
As a result, the resin flows into the bobbin cylinder 4 later, and the inner circumference of the bobbin cylinder, the primary coil 1, the open magnetic circuit core 3, and the support cylinder 1
4 and solidify, and through the space between the radial projecting pieces 7, 7 at the rear end of the bobbin cylinder, the inside of the front cylinder 8, the inner circumference of the inner / outer multi-wall hollow cylinder 16 and the bobbin cylinder, the secondary coil. And the inside of the rear cylinder 11 are filled and solidified, and the resin layer 18 thus solidified serves as an open magnetic circuit core and a primary coil, a bobbin cylinder and a secondary coil, a front cylinder, a rear cylinder, and an outer core. The inner and outer multi-wall hollow cylinders are fixed concentrically.

In the embodiment of claim 2 of FIGS. 3 and 4 described above, the primary coil is wound on the heat-resistant insulating sheet 21 wound outside the open magnetic circuit core, and the secondary coil is provided on the outer circumference of the bobbin cylinder 4. Although it is wound, conversely, the secondary coil may be wound on the heat resistant insulating sheet 21 and the primary coil may be wound outside the bobbin cylinder 4 with the same effect.

In each of the illustrated embodiments, the front and rear ends of the inner-outer multi-wall hollow cylinder 16 also serving as the outer iron core are annular step portions provided on the rear outer circumference of the front cylinder, and the front inner circumference of the rear cylinder. Although it was fitted and fixed to the annular stepped portion of, the annular stepped portion on which the front and rear end portions of the inner-outer multi-wall hollow cylinder 16 are fitted and abutted on the rear inner circumference of the front cylinder and the front outer circumference of the rear cylinder. Alternatively, the front cylinder and the front end of the inner / outer multi-wall hollow cylinder, and the rear end of the inner / outer multi-wall hollow cylinder and the rear cylinder may be assembled.

In each of the illustrated embodiments, the thickness is 0.3.
One or several layers of silicon steel sheets on the inside including the innermost layer of the outer / inner multi-wall hollow cylinder 16 also serving as an exterior iron core in which silicon steel sheets of about 5 to 0.5 mm are closely wound and wound 2 to 4 times, and a thickness of 0 .Cylinders with different diameters of several inner silicon steel plates including the innermost layers of the inner and outer multi-wall hollow cylinders in which a silicon steel plate of about 1 mm is wound tightly and wound about 10 to 15 times. Rounded into shape,
In the case of an inner / outer multi-wall hollow cylinder that also serves as an outer core consisting of multiple cylinders that are fitted tightly inside and outside with a small diameter inside and a large diameter outside, the inner and middle layers other than the outermost layer As shown in FIG. 5A, holes having a diameter of about 2 to 3 mm are formed as openings 17 in a cylindrical body of a silicon steel plate by punching in advance at intervals of about 10 mm vertically and horizontally,
The cast thermosetting insulating resin penetrates into the space between the closely adhered silicon steel plates through the opening 17 and solidifies to fix the silicon steel plates, so that the inner and outer multi-wall hollow cylinders that are more solid and have excellent insulation properties and also serve as outer cores become. The opening 17 is not limited to a hole, and as shown in FIG. 5B, a slit having a width of about 0.5 to 1 mm and a length of about 90% of the length of a silicon steel plate is formed in the circumferential direction by 10 mm.
It may be opened at intervals of about mm.

This ignition coil, as shown in FIGS. 1 and 3, has a front-facing cylinder 22 which projects concentrically from the front end of the front cylinder 8.
An electrically insulating and elastic, for example, synthetic rubber tubular boot 23 is fitted and held in an extended shape, and the tubular boot is inserted into the plug hole 24 of the engine from the bottom of the plug hole. The high pressure terminal 9 is formed by elastically fitting the cylindrical boot outside the insulator of the spark plug 25 protruding.
Is used by electrically contacting the head terminal 26 of the spark plug.

[0025]

The ignition coil according to claim 1 of the present invention has an inner-outer multi-wall hollow cylinder having a plurality of layers of cylindrical silicon steel plates closely adhered to each other inside and outside. Being extremely large, the efficiency is increased and the spark energy of the spark plug is increased. During use, a high-pressure corona is generated in the gap between the outer core and the plug hole for each spark discharge.However, the outer core is a multi-wall hollow cylinder made of multiple layers of cylindrical silicon steel plates that are in close contact with each other. It does not deteriorate due to the generation of corona and has excellent durability.

When obtaining an ignition coil having an outer diameter of 24 mm,
A conventional ignition coil uses a cylindrical case made of synthetic resin with a wall thickness of 1 mm, and when an outer core made of a silicon steel plate with a thickness of 0.5 mm is wrapped around the inner case, the inner diameter of the outer core becomes Two
4 mm- (2 mm + 1 mm) = 21.0 mm. On the other hand, according to the second embodiment, in Example A in which the spiral inner and outer multi-wall hollow cylinder also used as the exterior core, which is closely wound three times with a silicon steel plate having a thickness of 0.35 mm, is used. The inner diameter of the cylinder is 24 mm- (0.35 × 6) = 21.9 mm, which is larger than the conventional 21.0 mm. Similarly, according to claim 2, a silicon steel plate having a thickness of 0.1 mm is used 10 times,
In Example B in which a spirally wound inner-outer multi-wall hollow cylinder also used as an exterior iron core closely wound, the inner diameter of the cylinder was 2
4 mm- (0.1 mm × 20) = 22 mm, and the inner diameter is larger than that of the conventional example.

When the diameter of the open magnetic circuit core is set to 8 mm and a bobbin made of synthetic resin having a thickness of 1 mm is put on the core, the outer diameter of the bobbin is 10 mm. On the other hand, the diameter of the open magnetic circuit core is set to 9.8 mm, and the outer circumference has a thickness of 0.
The outer diameter of the heat-resistant insulating sheet according to claim 2 in which the heat-resistant insulating sheet of 1 mm is wound twice is 10.0 mm. Even if the outer diameter is the same, the outer diameter of the open magnetic circuit core is the same as that of the conventional example. Therefore, the cross-sectional area of the open magnetic circuit core becomes 1.6 times, including the improvement of the substantial space factor.

That is, in the above-mentioned conventional example, the outer diameter is 10 mm.
When an ignition coil with an outer diameter of 24 mm is manufactured by an open magnetic circuit iron core fitted with a bobbin of No. 2, 21.0 mm generated between the outer iron core with an inner diameter of 21.0 mm and the bobbin with an outer diameter of 10 mm
-10 mm = 11.0 mm divided into two equal thickness 5.5 mm
The primary coil, the secondary coil bobbin having a wall thickness of 1 mm, and the secondary coil were concentrically arranged in the cylindrical space, and an insulating layer made of a thermosetting insulating resin had to be provided between them.

However, the primary coil, the bobbin cylinder having a wall thickness of 1 mm, and the secondary coil are the outer core having an inner diameter of 21.9 mm and the heat-resistant insulating sheet having an outer diameter of 10.0 mm in the embodiment A of claim 2. Between 21.9mm-10.0mm
= 11.9 mm is divided into two equal parts, and it may be arranged in a cylindrical space having a thickness of 5.95 mm.
22 mm-10.0 mm = 12.0 mm generated between the outer core of 10 mm and the heat-resistant insulating sheet having an outer diameter of 10.0 mm
May be placed in a cylindrical space having a thickness of 6.0 mm, which is divided into two equal parts.

Therefore, the ignition coil according to claim 2 has the paragraph 00.
In addition to having the effect of claim 1 described in 25,
The cross-sectional area of the open magnetic circuit core and the exterior core (the inner and outer multi-wall hollow cylinder 16) can be increased, and the number of turns of the primary coil and the secondary coil can be increased to increase the cross-sectional area. The amount of magnetic flux increases by increasing the cross-sectional area of the open magnetic circuit core or the outer core. The magnetic shield effect is further improved due to the increase in the cross-sectional area of the open magnetic circuit core. Also, because the cross-sectional area increases due to the increase in the number of windings of the primary coil and the secondary coil, the spark plug discharges much higher spark energy than the spark coil of the same outer diameter, resulting in a Linburn engine. And a high-performance ignition coil that can be used in alternative fuel engines.

For example, as compared with the conventional ignition coil having the same outer diameter, the diameter of the open magnetic circuit core is increased from 8 mm to 9.8 mm to increase the cross-sectional area by about 1.6 times, and the outer core (inner and outer multiwall hollow Even if the cross-sectional area of the cylinder 16) is wound three times in close contact with a silicon steel plate having a thickness of 0.35 mm, the winding area of the primary coil and the secondary coil is about Since it can be increased by 1.3 times, even if the primary current applied to the primary coil is the same as in the conventional example, the amount of magnetic flux formed in the open magnetic circuit iron core is about 1.7 times, and the primary coil, Since the number of turns of the secondary coil is about 1.2 times, the primary and secondary inductances are about twice, and the spark energy output of the spark plug can be increased about twice.

[Brief description of drawings]

FIG. 1 is a sectional view of an ignition coil according to an embodiment of claim 1 of the present invention in use.

2A is an enlarged sectional view taken along line II-II of FIG.
(B) is a similar enlarged sectional view of another embodiment.

FIG. 3 is a sectional view of an ignition coil according to a second embodiment of the present invention in use.

4A is an enlarged sectional view taken along line IV-IV in FIG.
(B) is a similar enlarged sectional view of another embodiment.

FIG. 5A is a cross-sectional view of an inner / outer multi-wall hollow cylinder having an opening as a hole and also serving as an exterior iron core, and FIG. 5B is a cross-sectional view of an inner / outer multi-wall hollow cylinder having an opening as a slit and also serving as an exterior iron core. is there.

FIG. 6A is a front view of the secondary bobbin as seen from the front,
(B) is a front view of the rear cylinder as seen from the front.

[Explanation of symbols]

1 Primary coil 1'Heat-resistant insulating sheet 2 Secondary coil 3 Open magnetic circuit iron core 3'Silicone steel plate 4 Bobbin cylinder 8 Front cylinder 9 High voltage terminal 11 Rear cylinder 13 Primary terminal (earth terminal) 16 Magnetic material that also serves as an outer core Inner / outer multi-wall hollow cylinder made of metal plate (silicon steel plate) 17 Opening in silicon steel plate of inner layer of inner / outer multi-wall hollow cylinder 18 Thermosetting insulating resin layer 20 Bobbin 21 fitted on outer circumference of open magnetic circuit core 21 Opening magnetism Heat-resistant insulating sheet wrapped around the outer circumference of the road core 23 Cylindrical boot 24 Plug hole 25 Spark plug

Claims (3)

[Claims] 1. A front cylinder made of resin having a high-voltage terminal at a closed front end, a rear cylinder made of resin having a primary terminal, and a plurality of layers of cylindrical magnetic metal plates inside and outside, which are also used as an outer core and serve as an outer core. It has a wall hollow cylinder and an open magnetic circuit core having a bobbin wound with either one of the primary coil and the secondary coil fitted on the outer periphery, and the front end portion of the inner-outer multi-wall hollow cylinder The rear end is fitted and fixed to each of the rear cylinders in the cylinder, and the open magnetic circuit core having the one coil on the outer circumference is arranged at the center of the inner / outer multi-wall hollow cylinder that also serves as the exterior iron core, and The other coil is concentrically provided with the secondary coil connected to the high-voltage terminal and the primary coil connected to the primary terminal, respectively, and surrounded by the inner and outer multi-wall hollow cylinders that also serve as inner and outer cores of the front cylinder. internal,
And an ignition coil for an internal combustion engine, characterized in that a thermosetting insulating resin is filled inside the rear cylinder, and an open magnetic circuit core, a primary coil and a secondary coil are fixed in the insulating resin layer. 2. A resin front cylinder having a high voltage terminal at a closed front end, a resin rear cylinder having a primary terminal, and a plurality of layers of cylindrical magnetic metal plates inside and outside, which also serve as an outer core and are used as an outer core. Wrap the wall hollow cylinder and a thin heat resistant insulation sheet around the outer circumference,
And an open magnetic circuit core around which either one of a primary coil or a secondary coil is wound, and the front end of the inner-outer multi-wall hollow cylinder is a front cylinder and the rear end is a rear cylinder. Are fitted and fixed respectively, and an open magnetic circuit iron core having the one coil on the outer periphery is arranged at the center of the inner and outer multi-wall hollow cylinder which also serves as the outer iron core, and the other coil is concentrically arranged outside the core. Provided,
The secondary coil is connected to the high-voltage terminal and the primary coil is connected to the primary terminal, respectively, and the inside of the front cylinder, the inside surrounded by the inner and outer multi-wall hollow cylinders that also serve as the exterior iron core, and the inside of the rear cylinder are thermosettable. An ignition coil for an internal combustion engine, characterized in that an insulating resin is filled and an open magnetic circuit core, a primary coil and a secondary coil are fixed in the insulating resin layer. 3. The ignition coil for an internal combustion engine according to claim 1, wherein a plurality of openings are provided in at least the innermost layer of the inner / outer multi-wall hollow cylinder that also serves as an exterior iron core and is made of a magnetic metal plate. An ignition coil for an internal combustion engine, which is provided with a portion.