JP2000323338A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an output efficiency by forming a cut at the joint part between the first and second iron cores to reduce the joint area between them. SOLUTION: Related to an ignition coil, a center iron-core (first iron core) 18 is provided inside a primary coil bobbin 12 while a winding iron-core (second iron-core) 19 is provided at the outer peripheral part of an insulating case 11. The winding iron-core 11 is stamped from a silicon steel plate of relatively thin into an endless form. Related to the winding iron-core 19, a plurality of slots 19a are provided at such parts as facing each other. The slots 19a are longer than the end surface of the center iron-core 18 while extending in parallel each other. These slots 19a are stamped at the same time when a band material 19' is stamped, and provided at such position as agree each other when wound endless.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an ignition coil for an internal combustion engine which supplies a high voltage for generating spark discharge to, for example, a spark plug of an automobile engine.

[0002]

2. Description of the Related Art FIG. 5 shows such an ignition coil for an internal combustion engine. The ignition coil is of a mold type to be attached to an automobile engine, and includes a primary coil bobbin 2 and a secondary coil bobbin 3 inside an insulating case 1.

The bobbin 2 for the primary coil and the bobbin 3 for the secondary coil are each formed into a cylindrical shape with an electrically insulating material such as a synthetic resin, and are housed in the insulating case 1 in a state of being concentric with each other. Have been. The primary coil 4 has a primary coil 4 wound and held on the outer periphery thereof, and the secondary coil bobbin 3 has a secondary coil 5 wound and held on the outer periphery thereof. The primary coil 4 is connected to a battery (not shown) via a primary terminal 6. The secondary coil 5 is 1:70 to the number of turns of the primary coil 4.
1: 120, and is connected to a spark plug of an automobile engine (not shown) via the high voltage terminal 7 and a high tension cord (not shown).

In the above-mentioned ignition coil, a center core 8 is provided inside the cylinder of the primary coil bobbin 2, and a wound core 9 is provided on the outer periphery of the insulating case 1.
The center iron core 8 is formed by laminating strip-shaped silicon steel plates into a prismatic shape, and penetrates the bobbin 2 for the primary coil. The wound iron core 9 is formed in a ring shape by winding a band-shaped silicon steel plate a plurality of times, and surrounds the outer peripheral portion of the insulating case 1 so as to pass through both end surfaces of the center iron core 8. The wound core 9 is joined to both end surfaces of the center core 8 via its inner peripheral surface so as to form a closed magnetic path between the wound core 9 and the center core 8.

The above-mentioned various components are fixed at predetermined positions by an electrically insulating thermosetting resin 10 such as an epoxy resin filled and cured in the insulating case 1.

In the ignition coil configured as described above, the primary coil 4 and the secondary coil 5 have a mutual induction relationship by the center core 8 and the wound core 9. Therefore,
When a predetermined current is supplied from a battery (not shown) to the primary coil 4 and cut off, a high-voltage current generated in the secondary coil 5 is supplied to the spark plug, and a spark discharge is generated between the electrodes at the tip. Can be generated.

[0007]

By the way, in this type of ignition coil, the center iron core 8 is in operation.
Since a magnetic flux flows between the coil core 9 and the winding core 9, an eddy current is generated along with this, and heat is generated by eddy current loss.

In the above-described ignition coil, as shown in FIG. 6, the joint area between the center core 8 and the wound core 9 is large, that is, the area of the portion where the magnetic flux Y flows is large.
A large amount of eddy current Z is generated. As a result, a large amount of heat is generated due to the eddy current loss, and the output efficiency of the ignition coil is significantly reduced.

In view of the above, an object of the present invention is to provide an ignition coil for an internal combustion engine that can improve output efficiency.

[0010]

According to the first aspect of the present invention, a first iron core having a cylindrical shape and passing through the inside of a bobbin in which a coil is wound and held, and a first iron core passing through the outer periphery of the bobbin are provided. And a second core joined to an end of the first core to form a closed magnetic circuit between the first core and the first core. A notch is formed at the joint between the first and second cores in order to reduce the joint area between the core and the second core.

According to a second aspect of the present invention, in the first aspect of the present invention, the notch is a groove-shaped hole provided at a joint of the second iron core with the first iron core. There is a feature.

According to a third aspect of the present invention, in the first aspect of the present invention, the second iron core is formed by winding a band-shaped material punched and formed with the notch a plurality of times. It is characterized by being.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing one embodiment. FIG. 1 and FIG.
1 shows an ignition coil for an internal combustion engine according to the present invention, and illustrates a mold-type ignition coil attached to an automobile engine.

In this ignition coil, a bobbin 12 for a primary coil and a bobbin 13 for a secondary coil are disposed inside an insulating case 11.

The bobbin 12 for the primary coil and the bobbin 13 for the secondary coil are each formed into a cylindrical shape with an electrically insulating material such as a synthetic resin, and are housed in the insulating case 11 in a state of being concentric with each other. Have been. The lower end of the primary coil bobbin 12 is fitted into the fitting hole 11a of the insulating case 11, and the primary coil 14 is wound around the outer peripheral portion thereof. The secondary coil bobbin 13 is arranged on the outer peripheral portion of the primary coil bobbin 12, and has a plurality of flanges 13a on its outer peripheral surface. These collars 13a
The secondary coil bobbin 13 is formed integrally with the secondary coil bobbin 13 along the axial direction of the secondary coil bobbin 13 and at a predetermined distance from each other. Is held. The secondary coil 15
Is 1: 7 with respect to the number of turns of the primary coil 14, for example.
It is set to be 0 to 1: 120.

In this ignition coil, the primary coil 14 is connected to a battery (not shown) via a primary terminal 16, and the secondary coil 15 is shown via a high voltage terminal 17 and a high tension cord (not shown). Not connected to the spark plug of the car engine.

The ignition coil is provided with a center iron core (first iron core) 18 inside the cylinder of the primary coil bobbin 12 and a wound iron core 1 on the outer periphery of the insulating case 11.
9 (second iron core).

The center iron core 18 is formed by laminating strip-shaped silicon steel sheets into a prismatic shape.
2 through.

As shown in the drawing, the wound iron core 19 is formed by stamping and forming a band-shaped material 19 ′ from a relatively thin silicon steel plate, and then winding it a plurality of times to obtain a circle or an ellipse. Or an endless shape such as a square frame. The wound iron core 19 is provided with a plurality of slots 19a at portions opposing each other. Each slot 19a is longer than the end face of the center core 18 and extends so as to be parallel to each other. These slots 19a are
It is punched out at the same time as the above-mentioned strip-shaped material 19 ′ is punched and formed, and is provided at a position that matches each other when it is wound endlessly.

The wound iron core 19 surrounds the outer peripheral portion of the insulating case 11 in such a manner that the above-mentioned plurality of slots 19a face both end faces of the center iron core 18, respectively. In order to form a road, it is joined to both end surfaces of the center iron core 18 via its inner peripheral surface. In this case, as is apparent from FIG. 3, the wound core 19 and the center core 18 are mutually connected so that the joint surfaces with the center core 18 are separated from each other by the slots 19a formed in the wound core 19. To join. Adhesive,
Alternatively, appropriate joining means such as welding is applied.

The various components described above include an insulating case 11
Are filled with a thermosetting resin 20 having electrical insulation such as an epoxy resin, and are further cured to be fixed at predetermined positions.

In the ignition coil configured as described above, the primary coil 1 is formed by the center core 18 and the wound core 19.
4 and the secondary coil 15 have a mutual induction relationship. Therefore, when a predetermined current is supplied from a battery (not shown) to the primary coil 14 and then cut off, a high-voltage current generated in the secondary coil 15 is supplied to the ignition plug,
A spark discharge can be generated between the electrodes at the tip.

By the way, even in the above-described ignition coil, the magnetic flux Y 'flows between the center iron core 18 and the wound iron core 19 in the operating state, and accordingly, an eddy current Z' is generated. As a result, heat is generated due to eddy current loss.

However, in the above-mentioned ignition coil, the joint area with the center iron core 18, that is, the area where the magnetic flux Y 'flows, is reduced by the action of the slot 19a provided in the wound iron core 19 as compared with the conventional one. . Moreover, wound iron core 1
The joint between the core 9 and the center iron core 18 is separated from each other by the slot 19a.

Therefore, according to this ignition coil, the eddy current Z 'generated between the center iron core 18 and the wound iron core 19 is also reduced, and as a result, the amount of heat generated by the eddy current loss is reduced. As a result, in the above-described ignition coil, the output performance is sufficiently maintained in the operating state, and there is no fear that the efficiency of the ignition coil is significantly reduced.

Further, in the above-mentioned ignition coil, the slot 19a is formed at the same time when the strip 19 'is punched and formed from a relatively thin silicon steel sheet, and thereafter, the slot 19a is wound a plurality of times. The iron core 19 is constituted. Therefore, the manufacturing operation does not become complicated due to the formation of the slot 19a.

Further, at the time of stamping and forming, only the portion of the slot 19a is discarded, and the margin for removing the outer shape of the strip 19 'is not discarded as in the past. As a result, since there is almost no loss of material and the yield is good, there is no danger that the production cost will be greatly increased.

In the above-described embodiment, the slot 19a is exemplified as the notch. However, other notches may be used as long as the joint area between the center core 18 and the wound core 19 is reduced. It does not matter. In this case, it is not necessary to apply the closed notch,
A notch opened outside the iron core may be applied. Further, it is not necessary to cut off the joint between the wound core 19 and the center core 18 by the notch.

Further, the notch is formed only on the wound iron core 19 side, but it is also possible to form a notch only on the center iron core 18 side, or to form a notch on both sides.

[0030]

As described above, according to the present invention,
Since the notch is formed at the joint between the first iron core and the second iron core, the eddy current generated between these iron cores is also reduced, and the amount of heat generated by the eddy current loss is reduced. Therefore, it is possible to prevent a decrease in output performance due to heat generation,
The efficiency can be improved. Also,
When a notch is formed at the same time when the strip material is punched and formed, and then the wound core is formed by winding the notch a plurality of times, the manufacturing operation becomes complicated with the formation of the notch. It is possible to further improve the yield without causing a situation.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a perspective view showing a joined state of a first iron core and a second iron core of the ignition coil for an internal combustion engine shown in FIG. 1;

FIG. 4 is a perspective view showing a band-shaped member applied to the internal combustion engine ignition coil shown in FIG. 1;

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

6 is a perspective view showing a joint state of a center iron core and a wound iron core of the ignition coil for an internal combustion engine shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Insulation case 12 Primary coil bobbin 13 Secondary coil bobbin 14 Primary coil 15 Secondary coil 18 Center core 19 Winding core 19 'Strip 19a Slot

Claims (3)

[Claims] A first magnetic core passing through the inside of a bobbin having a cylindrical shape and wound with a coil, and a first magnetic core passing through the outer periphery of the bobbin and closing the first iron core; And a second iron core joined to an end of the first iron core to form a path, wherein the joint area between the first iron core and the second iron core is reduced. An ignition coil for an internal combustion engine, characterized in that a notch is formed in a joint between the first and second iron cores. 2. The ignition coil for an internal combustion engine according to claim 1, wherein the notch is a groove-shaped hole provided at a joint of the second iron core with the first iron core. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the second core is formed by winding a band-shaped material punched and formed with the notch a plurality of times.