JPH09306761A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil which is small-sized and enables generation of high spark energy. SOLUTION: This coil includes a coil body 1 which is formed by concentrically arranging a secondary coil 5 on the outer periphery of a primary coil 3 and integrally molding the coils by an insulating member 9, and closed magnetic circuit cores 10, 11 made of a magnetic metal. In this case, the coil body 1 is inserted into the closed magnetic circuit cores 10, 11, and a permanent magnet 12 is arranged in a magnetically serial manner with the closed magnetic circuit at a position on the closed magnetic circuit cores 10, 11 which is different from the position where the coil body 1 is arranged. In addition, the area of a surface of the permanent magnet 12 facing the magnetic circuit is made 1.4 times to twice the cross-sectional area of the closed magnetic circuit cores 10, 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded type internal combustion engine ignition coil for supplying a high voltage to generate a spark discharge in, for example, a spark plug of an automobile engine, and more particularly to an internal combustion engine which is required to be miniaturized. The present invention relates to an ignition coil.

[0002]

2. Description of the Related Art Conventionally, a molded ignition coil for an internal combustion engine having a permanent magnet in a magnetic circuit has been disclosed in, for example, FIG.
It had a schematic structure as shown in the sectional view of FIG.

In the figure, reference numeral 1 is an ignition coil body, which is a laminated iron core 1 made of a silicon steel plate having an approximately U-shape as an iron core.
The ends of 0 and 11 are joined to face each other to form a magnetic circuit forming a closed magnetic circuit.

In the magnetic circuit in the ignition coil body 1,
A plate-shaped permanent magnet 12 is attached to the iron cores 10 and 1 for magnetic reverse bias.
They are arranged so as to be sandwiched between the first coil bobbin and the first coil bobbin, and are bonded to each other in the primary coil bobbin described later by using an adhesive.

Further, one joint portion 11a of the iron cores 10 and 11 is formed.
Are joined by welding or the like (hereinafter, a permanent magnet arranged at this position is referred to as an inner magnet type).

Reference numeral 2 denotes a primary coil bobbin integrally formed of an electrically insulating material such as synthetic resin. The primary coil bobbin 2 is disposed in close contact with the outer periphery of the iron core and has a primary coil on the outer peripheral portion. 3 is wound.

A secondary coil bobbin 4 is concentrically arranged on the outer periphery of the primary coil 3 and is made of an electrically insulating material such as synthetic resin. A plurality of collars, which function as partitions for divided winding, are integrally molded. The secondary coil bobbin 4 has, for example, a winding ratio of the primary coil 3 of about 1: 1.
The secondary coil 5, which is No. 00, is wound in a divided winding with each collar portion as a partition.

Further, reference numeral 6 denotes an insulating case which is disposed further on the outer circumference of the secondary coil 5 and is molded with an insulating member such as synthetic resin. One end of the insulating case 6 is provided with a primary terminal 7. In addition, the high voltage terminal 8 is provided at the bottom of the insulating case 6. The inside of the insulating case 6 is filled with an insulating member 9 such as epoxy resin, and then the insulating member 9
Is hardened, and the members arranged inside the insulating case 6 are fixed in an insulated state.

The primary coil 3 and the primary terminal 7 are electrically connected to each other, and the secondary coil 5 and the high voltage terminal 8 are electrically connected to each other. When a predetermined current is applied to the primary coil 3 and then cut off, the secondary coil 5 is generated. A high voltage current is supplied from the high voltage terminal 8 to the spark plug via a high tension cord (not shown).

The internal magnet type ignition coil (so-called molded coil) of the internal magnet type configured as described above is a permanent magnet 12
By applying a magnetic reverse bias to the iron cores 10 and 11 by using, the change amount of the magnetic flux in the iron cores 10 and 11 when the primary coil current is cut off is increased, and the mold coil is downsized and the output is increased. .

[0011]

However, since the price of the above-mentioned permanent magnet is high, the price of the molded coil itself is also high.

The present invention solves such a drawback and relates to miniaturization and high output of an ignition coil for an internal combustion engine using a permanent magnet.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has a coil body in which a secondary coil is concentrically arranged on the outer peripheral side of a primary coil and integrally molded with an insulating member. , A closed magnetic circuit iron core made of magnetic metal,
An ignition coil for an internal combustion engine, wherein the coil body is arranged by inserting it into the closed magnetic circuit core, and a permanent magnet is provided in the closed magnetic circuit at a position of the closed magnetic circuit core different from a place where the coil body is arranged. An ignition coil for an internal combustion engine, which is magnetically arranged in series and has an area of a surface facing the magnetic path of the permanent magnet that is 1.4 to 2 times the cross-sectional area of the closed magnetic circuit core. is there.

The present invention also provides an ignition coil for an internal combustion engine, wherein the thickness of the permanent magnet is a value obtained by multiplying the area of the permanent magnet by 0.007 to 0.01.

Furthermore, the present invention provides an ignition coil for an internal combustion engine, wherein the magnetic metal forming the closed magnetic circuit core is a laminated body of grain-oriented silicon steel plates.

According to the present invention, the secondary coil is concentrically arranged on the outer peripheral side of the primary coil, and is composed of a coil body integrally molded with an insulating member and a closed magnetic circuit iron core made of magnetic metal. An ignition coil for an internal combustion engine in which a main body is inserted into the closed magnetic circuit core to be magnetically connected in series with a permanent magnet disposed in a part of the magnetic path of the closed magnetic circuit core to prevent magnetic saturation. Alternatively, the present invention provides an ignition coil for an internal combustion engine provided with a spacer made of a non-magnetic material.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of an ignition coil for an internal combustion engine according to an embodiment of the present invention, and the same members as those in the conventional example are designated by the same reference numerals.

The greatest feature of the present embodiment is that the permanent magnet 12 is provided not on the inside of the ignition coil body 1 but on the side opposite to one side of the closed magnetic circuit cores 10 and 11 in which the ignition coil body 1 is arranged (hereinafter, This is described as an outer magnet type).

Further, the permanent magnet 12 is a samarium-cobalt-based or neodymium-based plate-shaped magnet, which is arranged at an angle θ with respect to the magnetic path, and the closed magnetic circuit cores 10, 1 are provided.
A spacer 13 made of a non-magnetic material or a gap is provided adjacent to the permanent magnet 12 so that 1 does not cause magnetic saturation.

[0020]

EXAMPLE An example of the present invention will be shown below for comparison with a conventional example. First, 0.3 mm-thickness grain-oriented silicon steel plates are laminated to form substantially U-shaped iron cores 10 and 11 having a cross section of 9 mm × 9 mm. Then, the iron cores 10 and 11 are inserted into the primary coil bobbin 2 and the iron core fixing sheath 6 a provided on the insulating case 6. And the primary coil bobbin 2
Inside, the iron cores 10 and 11 are joined at the joining portion 11a.

On the other hand, in the iron core fixing sheath 6a, the end faces of the iron cores 10 and 11 are formed at an angle of θ = 40 degrees with respect to the magnetic path, and 1 mm when sandwiched between the end faces.
A thick samarium-cobalt-based permanent magnet 12 and a spacer 13 made of a non-magnetic material and having a thickness of about 0.2 to 0.4 mm.
Alternatively, a gap is provided to prevent the iron cores 10 and 11 from being magnetically saturated. The area of the permanent magnet 12 is 9 mm × 14 mm = 126 mm ² .

The primary coil 3 is a 0.45 mm diameter single wire wound 140 times, and the primary breaking current is 6 A.
The resulting magnetomotive force is 780 AT. Further, the secondary coil 5 has a winding number of 1: 100 with the winding ratio of the primary coil 3, and in order to secure the withstand voltage, the secondary coil 5 is divided into windings with a collar portion provided on the secondary coil bobbin 4, and is divided and wound. Has been done. The DC resistance value of the secondary coil 5 is 14 KΩ.

This embodiment (outer magnet type) under the above conditions
2 is compared with the conventional example (inner magnet type). In any case, the magnetomotive force of the primary coil 3 is set to 780 AT. As can be seen from this, the maximum value of the change amount of the magnetic flux interlinking with the primary coil 3 is 1.9 × 10 ⁻⁴ (Wb) in the case of the conventional example.
On the other hand, in this embodiment, 2.4 × 10 ⁻⁴ (W
It became b).

In the case of the outer magnet type, this is the primary coil 3
This is because the magnetic resistance of the iron core in the portion penetrating into is extremely small, so that when the magnetomotive force is the same, the amount of change in the magnetic flux linked to the primary coil 3 increases.

FIG. 3 shows the distribution of the amount of change in the magnetic flux linked to the primary coil 3 in this embodiment and the conventional example under the same measurement conditions. It should be noted that A, B, and C in the drawing all correspond to the positions of A, B, and C shown in FIGS. 1 and 5, respectively.

In the figure, in the case of the conventional inner magnet type, the position where the change amount of the magnetic flux is maximum is A, and at the position C where the permanent magnet 12 is mounted, the change amount of the magnetic flux is A Only 87%. This is because the permanent magnet 12 prevents the change of magnetic flux. The average value of A, B, and C is 94% at the position of A.

On the other hand, in the case of the outer magnet type as in this embodiment, the position where the amount of change in magnetic flux is maximum is B, and A,
The average value of B and C was 97% at the position of B. This is because the permanent magnet 12 is moved away from the primary coil 3,
The amount of change in the magnetic flux in the vicinity of the primary coil 3 is almost uniform, which maximizes the amount of change in the magnetic flux at the position B, which is the central portion.

Further, the effective primary inductances of the conventional example and this example are 4.2 mH and 5.4 mH, respectively, which is increased by about 29% in the case of this example. Also,
Coupling coefficients of the primary coil 3 and the secondary coil 5 in the conventional example and the present example are 0.92 to 0.94 and 0.95 to 0.97, respectively, which is considerably improved in the present example. I understand.

From the above, if the conditions of the secondary coil 5 in the conventional example and the present example are the same, the primary coil current is cut off by 6 A and the load on the secondary side is set to 50 PF.
In the case of the conventional example, the secondary voltage is 31.4 KV and the spark energy is 41 mJ, whereas in the case of this example, the secondary voltage is 36.0 KV and the spark energy is 55 mJ. However, the secondary voltage increases by 15%, and the spark energy increases by 34%.

On the contrary, in order to bring out the conventional performance with the structure of this embodiment, for example, the thickness of the permanent magnet 12 is 0.7 mm.
Then, the number of turns of the primary coil 3 and the secondary coil 5 is 20.
%, And it is possible to significantly reduce the cost. In addition, by taking the middle of the above specifications and designing to achieve both high output and cost reduction,
It is also possible to provide a high-power and inexpensive ignition coil.

In the above description, the permanent magnet 12 has an angle of 40 degrees with respect to the magnetic path, but the value of the angle θ may be another value. Therefore, FIG. 4 shows the amount of change in magnetic flux when the angle θ at which the permanent magnets 12 are arranged is changed. As you can see from the figure, when θ is less than 30 degrees, magnetic saturation occurs,
Practically, the magnetic flux change amount becomes maximum at 30 to 45 degrees.
If this is expressed by the area of the permanent magnet 12, 30 degrees is 2.0 times the cross-sectional area of the iron core, and 45 degrees is 1.4 times the cross-sectional area of the iron core.

Generally, the larger the area of the permanent magnet 12,
Although the amount of magnetic reverse bias with respect to the iron core can be increased, on the other hand, the permanent magnet 12 has a magnetic resistance equivalent to that of an air gap in the forward excitation by the primary coil 3, so that the area of the permanent magnet 12 is large. There is a contradiction that the larger the value, the smaller the magnetic resistance and the more easily the magnetic saturation occurs, and as a result, the ignition coil may not have a high output.

Therefore, it is effective to provide a magnetic saturation preventing gap or a spacer 13 in magnetic series with the permanent magnet 12 as required, as in this embodiment. Alternatively, the thickness can be selected so that the permanent magnet 12 has a sufficient magnetic resistance.

That is, it is ideal to select the thickness proportional to the area of the permanent magnet 12. The grain-oriented silicon steel sheet used in this example is magnetically saturated at a magnetic flux density of about 2.0 Tesla, so that it is practically 1.6 to 1.9 Tesl.
Efficiency is good when used at about a.

Therefore, when the optimum thickness of the permanent magnet 12 is obtained under the above conditions, the thickness of the permanent magnet having a magnetic flux density of 1.9 Tesla is 0.9 mm, and the numerical value of 0.9 is when the angle θ is 40 degrees. 12 which is the area of the permanent magnet 12.
It is a value obtained by multiplying the value of 126 of 6 mm ² by 0.0072. The thickness of the permanent magnet having a magnetic flux density of 1.6 Tesla is 1.2 mm, and the numerical value of 1.2 is the numerical value of 126 multiplied by 0.0096.
That is, substantially, the optimum thickness of the permanent magnet 12 is a value obtained by multiplying the numerical value of the area of the permanent magnet 12 by 0.007 to 0.010.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and may be implemented in any manner unless the structure described in the claims is changed. it can.

[0037]

As described above, the ignition coil for an internal combustion engine according to the present invention has a large size because it is provided with an outer magnet type closed magnetic circuit, so that it is possible to provide an ignition coil that is small in size and has high spark energy. Produce an effect.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram showing a magnetic flux change amount in a conventional ignition coil and an ignition coil of the present invention.

FIG. 3 A of a conventional ignition coil and an ignition coil of the present invention
It is a characteristic view which shows the distribution of the magnetic flux change amount in each position of -C.

FIG. 4 is a characteristic diagram showing a permanent magnet arrangement angle and a magnetic flux change amount in the ignition coil of the present invention.

FIG. 5 is a schematic cross-sectional view of a conventional ignition coil for an internal combustion engine.

[Explanation of symbols]

 1 Ignition coil main body 2 Primary coil bobbin 3 Primary coil 4 Secondary coil bobbin 5 Secondary coil 6 Insulation case 6a Iron core fixing sheath 7 Primary terminal 8 High voltage terminal 9 Insulating member 10, 11 Iron core 11a Joint 12 Permanent magnet 13 Spacer A, B, C Magnetic flux variation measurement point α Outer magnet type characteristic curve β Inner magnet type characteristic curve θ Permanent magnet arrangement angle

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[Procedure amendment]

[Submission date] April 1, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Title of Invention Ignition coil for internal combustion engine

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded type internal combustion engine ignition coil for supplying a high voltage to generate a spark discharge in, for example, a spark plug of an automobile engine, and more particularly to an internal combustion engine which is required to be miniaturized. The present invention relates to an ignition coil.

[0002]

2. Description of the Related Art Conventionally, a molded ignition coil for an internal combustion engine having a permanent magnet in a magnetic circuit has been disclosed in, for example, FIG.
It had a schematic structure as shown in the sectional view of FIG.

In the figure, reference numeral 1 is an ignition coil body, which is a laminated iron core 1 made of a silicon steel plate having an approximately U-shape as an iron core.
The ends of 0 and 11 are joined to face each other to form a magnetic circuit forming a closed magnetic circuit.

In the magnetic circuit in the ignition coil body 1,
A plate-shaped permanent magnet 12 is attached to the iron cores 10 and 1 for magnetic reverse bias.
They are arranged so as to be sandwiched between the first coil bobbin and the first coil bobbin, and are bonded to each other in the primary coil bobbin described later by using an adhesive.

Further, one joint portion 11a of the iron cores 10 and 11 is formed.
Are joined by welding or the like (hereinafter, a permanent magnet arranged at this position is referred to as an inner magnet type).

Reference numeral 2 denotes a primary coil bobbin integrally formed of an electrically insulating material such as synthetic resin. The primary coil bobbin 2 is disposed in close contact with the outer periphery of the iron core and has a primary coil on the outer peripheral portion. 3 is wound.

A secondary coil bobbin 4 is concentrically arranged on the outer periphery of the primary coil 3 and is made of an electrically insulating material such as synthetic resin. A plurality of collars, which function as partitions for divided winding, are integrally molded. The secondary coil bobbin 4 has, for example, a winding ratio of the primary coil 3 of about 1: 1.
The secondary coil 5, which is No. 00, is wound in a divided winding with each collar portion as a partition.

Further, reference numeral 6 denotes an insulating case which is disposed further on the outer circumference of the secondary coil 5 and is molded with an insulating member such as synthetic resin. One end of the insulating case 6 is provided with a primary terminal 7. In addition, the high voltage terminal 8 is provided at the bottom of the insulating case 6. The inside of the insulating case 6 is filled with an insulating member 9 such as epoxy resin, and then the insulating member 9
Is hardened, and the members arranged inside the insulating case 6 are fixed in an insulated state.

The primary coil 3 and the primary terminal 7 are electrically connected to each other, and the secondary coil 5 and the high voltage terminal 8 are electrically connected to each other. When a predetermined current is applied to the primary coil 3 and then cut off, the secondary coil 5 is generated. A high voltage current is supplied from the high voltage terminal 8 to the spark plug via a high tension cord (not shown).

The internal magnet type ignition coil (so-called molded coil) of the internal magnet type configured as described above is a permanent magnet 12
By applying a magnetic reverse bias to the iron cores 10 and 11 by using, the change amount of the magnetic flux in the iron cores 10 and 11 when the primary coil current is cut off is increased, and the mold coil is downsized and the output is increased. .

[0011]

However, since the price of the above-mentioned permanent magnet is high, the price of the molded coil itself is also high.

The present invention solves such a drawback and relates to miniaturization and high output of an ignition coil for an internal combustion engine using a permanent magnet.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has a coil body in which a secondary coil is concentrically arranged on the outer peripheral side of a primary coil and integrally molded with an insulating member. , A closed magnetic circuit iron core made of magnetic metal,
An ignition coil for an internal combustion engine, wherein the coil body is arranged by inserting it into the closed magnetic circuit core, and a permanent magnet is magnetically connected to the closed magnetic circuit on the iron core on the side facing the iron core on which the coil body is arranged. An ignition coil for an internal combustion engine, which is arranged in series and has an area of a surface facing the magnetic path of the permanent magnet that is 1.4 to 2 times the cross-sectional area of the closed magnetic circuit core.

The present invention also provides an ignition coil for an internal combustion engine, wherein the thickness of the permanent magnet is a value obtained by multiplying the area of the permanent magnet by 0.007 to 0.01.

Furthermore, the present invention provides an ignition coil for an internal combustion engine, wherein the magnetic metal forming the closed magnetic circuit core is a laminated body of grain-oriented silicon steel plates.

According to the present invention, the secondary coil is concentrically arranged on the outer peripheral side of the primary coil, and is composed of a coil body integrally molded with an insulating member and a closed magnetic circuit iron core made of magnetic metal. An ignition coil for an internal combustion engine in which a main body is inserted into the closed magnetic circuit core to be magnetically connected in series with a permanent magnet disposed in a part of the magnetic path of the closed magnetic circuit core to prevent magnetic saturation. Alternatively, the present invention provides an ignition coil for an internal combustion engine provided with a spacer made of a non-magnetic material.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of an ignition coil for an internal combustion engine according to an embodiment of the present invention, and the same members as those in the conventional example are designated by the same reference numerals.

The greatest feature of the present embodiment is that the permanent magnet 12 is provided not on the inside of the ignition coil body 1 but on the side opposite to one side of the closed magnetic circuit cores 10 and 11 in which the ignition coil body 1 is arranged (hereinafter, This is described as an outer magnet type).

Further, the permanent magnet 12 is a samarium-cobalt-based or neodymium-based plate-shaped magnet, which is arranged at an angle θ with respect to the magnetic path, and the closed magnetic circuit cores 10, 1 are provided.
A spacer 13 made of a non-magnetic material or a gap is provided adjacent to the permanent magnet 12 so that 1 does not cause magnetic saturation.

[0020]

EXAMPLE An example of the present invention will be shown below for comparison with a conventional example. First, 0.3 mm-thickness grain-oriented silicon steel plates are laminated to form substantially U-shaped iron cores 10 and 11 having a cross section of 9 mm × 9 mm. Then, the iron cores 10 and 11 are inserted into the primary coil bobbin 2 and the iron core fixing sheath 6 a provided on the insulating case 6. And the primary coil bobbin 2
Inside, the iron cores 10 and 11 are joined at the joining portion 11a.

On the other hand, in the iron core fixing sheath 6a, the end faces of the iron cores 10 and 11 are formed at an angle of θ = 40 degrees with respect to the magnetic path, and 1 mm when sandwiched between the end faces.
A thick samarium-cobalt-based permanent magnet 12 and a spacer 13 made of a non-magnetic material and having a thickness of about 0.2 to 0.4 mm.
Alternatively, a gap is provided to prevent the iron cores 10 and 11 from being magnetically saturated. The area of the permanent magnet 12 is 9 mm × 14 mm = 126 mm ² .

The primary coil 3 is a 0.45 mm diameter single wire wound 140 times, and the primary breaking current is 6 A.
The resulting magnetomotive force is 780 AT. Further, the secondary coil 5 has a winding number of 1: 100 with the winding ratio of the primary coil 3, and in order to secure the withstand voltage, the secondary coil 5 is divided into windings with a collar portion provided on the secondary coil bobbin 4, and is divided and wound. Has been done. The DC resistance value of the secondary coil 5 is 14 KΩ.

This embodiment (outer magnet type) under the above conditions
2 is compared with the conventional example (inner magnet type). In any case, the magnetomotive force of the primary coil 3 is set to 780 AT. As can be seen from this, the maximum value of the change amount of the magnetic flux interlinking with the primary coil 3 is 1.9 × 10 ⁻⁴ (Wb) in the case of the conventional example.
On the other hand, in this embodiment, 2.4 × 10 ⁻⁴ (W
It became b).

In the case of the outer magnet type, this is the primary coil 3
This is because the magnetic resistance of the iron core in the portion penetrating into is extremely small, so that when the magnetomotive force is the same, the amount of change in the magnetic flux linked to the primary coil 3 increases.

FIG. 3 shows the distribution of the amount of change in the magnetic flux linked to the primary coil 3 in this embodiment and the conventional example under the same measurement conditions. It should be noted that A, B, and C in the drawing all correspond to the positions of A, B, and C shown in FIGS. 1 and 5, respectively.

In the figure, in the case of the conventional inner magnet type, the position where the change amount of the magnetic flux is maximum is A, and at the position C where the permanent magnet 12 is mounted, the change amount of the magnetic flux is A Only 87%. This is because the permanent magnet 12 prevents the change of magnetic flux. The average value of A, B, and C is 94% at the position of A.

On the other hand, in the case of the outer magnet type as in this embodiment, the position where the amount of change in magnetic flux is maximum is B, and A,
The average value of B and C was 97% at the position of B. This is because the permanent magnet 12 is moved away from the primary coil 3,
The amount of change in the magnetic flux in the vicinity of the primary coil 3 is almost uniform, which maximizes the amount of change in the magnetic flux at the position B, which is the central portion.

Further, the effective primary inductances of the conventional example and this example are 4.2 mH and 5.4 mH, respectively, which is increased by about 29% in the case of this example. Also,
Coupling coefficients of the primary coil 3 and the secondary coil 5 in the conventional example and the present example are 0.92 to 0.94 and 0.95 to 0.97, respectively, which is considerably improved in the present example. I understand.

From the above, if the conditions of the secondary coil 5 in the conventional example and the present example are the same, the primary coil current is cut off by 6 A and the load on the secondary side is set to 50 PF.
In the case of the conventional example, the secondary voltage is 31.4 KV and the spark energy is 41 mJ, whereas in the case of this example, the secondary voltage is 36.0 KV and the spark energy is 55 mJ. However, the secondary voltage increases by 15%, and the spark energy increases by 34%.

On the contrary, in order to bring out the conventional performance with the structure of this embodiment, for example, the thickness of the permanent magnet 12 is 0.7 mm.
Then, the number of turns of the primary coil 3 and the secondary coil 5 is 20.
%, And it is possible to significantly reduce the cost. In addition, by taking the middle of the above specifications and designing to achieve both high output and cost reduction,
It is also possible to provide a high-power and inexpensive ignition coil.

In the above description, the permanent magnet 12 has an angle of 40 degrees with respect to the magnetic path, but the value of the angle θ may be another value. Therefore, FIG. 4 shows the amount of change in magnetic flux when the angle θ at which the permanent magnets 12 are arranged is changed. As you can see from the figure, when θ is less than 30 degrees, magnetic saturation occurs,
Practically, the magnetic flux change amount becomes maximum at 30 to 45 degrees.
If this is expressed by the area of the permanent magnet 12, 30 degrees is 2.0 times the cross-sectional area of the iron core, and 45 degrees is 1.4 times the cross-sectional area of the iron core.

Generally, the larger the area of the permanent magnet 12,
Although the amount of magnetic reverse bias with respect to the iron core can be increased, on the other hand, the permanent magnet 12 has a magnetic resistance equivalent to that of an air gap in the forward excitation by the primary coil 3, so that the area of the permanent magnet 12 is large. There is a contradiction that the larger the value, the smaller the magnetic resistance and the more easily the magnetic saturation occurs, and as a result, the ignition coil may not have a high output.

Therefore, it is effective to provide a magnetic saturation preventing gap or a spacer 13 in magnetic series with the permanent magnet 12 as required, as in this embodiment. Alternatively, the thickness can be selected so that the permanent magnet 12 has a sufficient magnetic resistance.

That is, it is ideal to select the thickness proportional to the area of the permanent magnet 12. The grain-oriented silicon steel sheet used in this example is magnetically saturated at a magnetic flux density of about 2.0 Tesla, so that it is practically 1.6 to 1.9 Tesl.
Efficiency is good when used at about a.

Therefore, when the optimum thickness of the permanent magnet 12 is obtained under the above conditions, the thickness of the permanent magnet having a magnetic flux density of 1.9 Tesla is 0.9 mm, and the numerical value of 0.9 is when the angle θ is 40 degrees. 12 which is the area of the permanent magnet 12.
It is a value obtained by multiplying the value of 126 of 6 mm ² by 0.0072. The thickness of the permanent magnet having a magnetic flux density of 1.6 Tesla is 1.2 mm, and the numerical value of 1.2 is the numerical value of 126 multiplied by 0.0096. That is, substantially, the optimum thickness of the permanent magnet 12 is a value obtained by multiplying the numerical value of the area of the permanent magnet 12 by 0.007 to 0.010.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and may be implemented in any manner unless the structure described in the claims is changed. it can.

[0037]

As described above, the ignition coil for an internal combustion engine according to the present invention has a large size because it is provided with an outer magnet type closed magnetic circuit, so that it is possible to provide an ignition coil that is small in size and has high spark energy. Produce an effect.

[Brief description of drawings]

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

FIG. 2 is a characteristic diagram showing a magnetic flux change amount in a conventional ignition coil and an ignition coil of the present invention.

FIG. 3 A of a conventional ignition coil and an ignition coil of the present invention
It is a characteristic view which shows the distribution of the magnetic flux change amount in each position of -C.

FIG. 4 is a characteristic diagram showing a permanent magnet arrangement angle and a magnetic flux change amount in the ignition coil of the present invention.

FIG. 5 is a schematic cross-sectional view of a conventional ignition coil for an internal combustion engine.

[Explanation of Codes] 1 Ignition coil body 2 Primary coil bobbin 3 Primary coil 4 Secondary coil bobbin 5 Secondary coil 6 Insulation case 6a Iron core fixing sheath 7 Primary terminal 8 High voltage terminal 9 Insulation member 10, 11 Iron core 11a Joint part 12 Permanent magnet 13 Spacer A, B, C Magnetic flux variation measurement point α Outer magnet type characteristic curve β Inner magnet type characteristic curve θ Permanent magnet installation angle

Claims (4)

[Claims] 1. A secondary coil is concentrically arranged on the outer peripheral side of the primary coil, and is composed of a coil body integrally molded with an insulating member, and a closed magnetic circuit core made of magnetic metal.
An ignition coil for an internal combustion engine, wherein the coil main body is inserted and arranged in the closed magnetic circuit core, and a permanent magnet is provided in the closed magnetic circuit at a position of the closed magnetic circuit core different from a place where the coil main body is arranged. An ignition coil for an internal combustion engine, which is magnetically arranged in series and has an area of a surface facing the magnetic path of the permanent magnet, which is 1.4 to 2 times the cross-sectional area of the closed magnetic circuit core. . 2. The ignition coil for an internal combustion engine according to claim 1, wherein the thickness of the permanent magnet is 0.0 to the area of the permanent magnet.
An ignition coil for an internal combustion engine, wherein the ignition coil has a thickness multiplied by 07 to 0.01. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the magnetic metal forming the closed magnetic circuit core is a laminated body of grain-oriented silicon steel sheets. 4. A secondary coil is concentrically arranged on the outer peripheral side of the primary coil, and is composed of a coil body integrally molded with an insulating member, and a closed magnetic circuit core made of magnetic metal.
An ignition coil for an internal combustion engine, in which the coil body is inserted into the closed magnetic circuit core to be magnetically connected in series with a permanent magnet disposed in a part of the magnetic path of the closed magnetic circuit core to prevent magnetic saturation. An ignition coil for an internal combustion engine, characterized in that it is provided with a void or a spacer made of a non-magnetic material.