JP3229865B2 - Ignition coil for internal combustion engine - Google Patents

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 which supplies a high voltage to generate a spark discharge in a spark plug of an automobile engine, for example.

[0002]

2. Description of the Related Art FIG. 1 is a sectional view showing a schematic configuration of an ignition coil for an internal combustion engine, and FIG. 6 is an enlarged plan sectional view of a conventional ignition coil for an internal combustion engine corresponding to line XX of FIG. The ignition coil for an internal combustion engine shown in FIG. 6 is an example in which an iron core is formed from a grain-oriented silicon steel sheet capable of increasing magnetic flux density, and the rolling direction and the direction of magnetic flux are matched to reduce the size of the iron core. is there.

In FIG. 1 or FIG. 6, reference numeral 1 denotes an ignition coil for an internal combustion engine, which is a primary coil bobbin 2, a primary coil 3 wound around the outer periphery of the primary coil bobbin 2, and arranged on the outer periphery of the primary coil 3. Secondary coil bobbin 4
A secondary coil 5 wound around the outer periphery of the secondary coil bobbin 4, a center core 6 inserted into the primary coil bobbin 2, a permanent magnet 7 disposed at one end of the center core 6, and a center. A side core 8 composed of a side core part 8a divided into four parts so as to form a closed magnetic circuit with the iron core 6 so that the plane shape is annular, and an insulating case 9 for accommodating each part from the primary coil bobbin 2 to the side core 8. It is composed of

[0004] A primary terminal 10 and a secondary terminal 11 are provided in the insulating case 9, the primary coil 3 is connected to the primary terminal 10, and the secondary coil 5 is connected to the secondary terminal 11. In addition, the insulating case 9 in which each part is accommodated.
Although not shown, the inside is filled with a thermosetting resin that is an insulating material for performing high-voltage insulation between each other, and each part is fixed in the insulating case 9.

FIGS. 7A and 7B are explanatory views showing an example of a conventional side iron core and an assembling method. In FIG. 7, a fitting projection 8b is provided on one end surface in the circumferential direction of the side core part 8a, and a fitting recess 8c is provided on the other end surface in the circumferential direction.
Is provided.

[0006] The fitting projection 8b and the fitting recess 8c are formed by a fitting projection 8b provided on one side iron core part 8a.
(Fitting recess 8c) and fitting recess 8c (fitting projection 8b) provided on the other side iron core part 8a are shown in FIG.
As shown in FIG. 7A, the parts 8a for the side iron cores are relatively moved in the axial direction after they are separated from each other in the axial direction, so as to be orthogonal to the axial direction as shown in FIG. 7B. It is fitted so that it does not come off in the direction. Therefore, by fitting the fitting projection 8b and the fitting recess 8c of the four side core parts 8a, the annular side core 8 shown in FIG. 7B can be obtained.

FIGS. 8A and 8B are explanatory views showing another example of a conventional side iron core and an assembling method. 8, the side core part 8a is provided with an engagement projection 8d on one end surface in the circumferential direction, and an engagement recess 8e on the other end surface in the circumferential direction.
Is provided.

The engaging projection 8d and the engaging recess 8e are formed by the engaging projection 8d provided on the one side iron core part 8a.
(Engaging recess 8e) and the engaging recess 8e (engaging projection 8d) provided in the other side iron core part 8a are shown in FIG.
As shown in FIG. 8A, the parts 8a for the side iron cores are relatively moved in the direction orthogonal to the axial direction and engaged with each other, thereby engaging the parts as shown in FIG. 8B. .
Therefore, by engaging the engaging protrusion 8d and the engaging recess 8e of the four side iron core parts 8a, FIG.
The annular side iron core 8 shown in FIG.

[0009]

In the case of the conventional side iron core 8 shown in FIG. 7, it is necessary to assemble the fitting projection 8b and the fitting recess 8c of each side iron core part 8a. Since it is difficult to fit the fitting projection 8b and the fitting recess 8c, it is difficult to manufacture the side iron core 8, that is, the ignition coil 1 for the internal combustion engine with good workability. Further, in the case of the side cores 8 having the configuration shown in FIG. 8, a gap (air) is formed between the side core parts 8a due to insufficient press-fitting or displacement of the engaging projections 8d of the side core parts 8a into the engaging recesses 8e. Gaps), which may cause a reduction in performance of the ignition coil 1 for an internal combustion engine.

Further, several tens of plate pieces punched into a predetermined shape by a press die are stacked to form the center core 6 or the side core part 8a. To form the side core 8, four side core parts are required. Since the stamper 8a is required, the number of stampings of the stamping die for stamping the side core parts 8a is increased, and the life of the stamping die is shorter than the production number of the ignition coil 1 for the internal combustion engine. Moreover, since the plate pieces for the center core 6 and the plate pieces for the side cores 8 are formed by different press dies, at least two types of press dies are required, so that the manufacturing cost is considerably increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages, and can be manufactured with good workability, can reduce the manufacturing cost, and further improve the reliability as a product. An object of the present invention is to provide an ignition coil for an internal combustion engine that can be operated.

[0012]

SUMMARY OF THE INVENTION The present invention provides a primary coil and a secondary coil, a center core inserted inside each coil, and an outside of each coil for forming a closed magnetic circuit with the center core. In the ignition coil for an internal combustion engine having an annular side core disposed on the side, the side core is formed by stacking a single annular side core plate piece punched from an iron core plate, and the direction of the magnetic flux of the center iron is formed. And the rolling direction of the core sheet material are parallel to each other, and the cross-sectional area of the portion where the rolling direction of the side core and the direction of the magnetic flux are perpendicular to the cross-sectional area perpendicular to the direction of the magnetic flux of the center 0.6 to 1.2 times, and the cross-sectional area of the part where the rolling direction of the side core and the direction of the magnetic flux intersect at 45 degrees is 0.9 to 2.0 times the cross-sectional area of the center core. Rolling direction of And the cross-sectional area of the portion where the direction of the magnetic flux is parallel to the 0.3-fold to 0.6 times the cross-sectional area of the center core
Things.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is an enlarged plan sectional view of an ignition coil for an internal combustion engine according to an embodiment of the present invention, taken along line XX of FIG. 1, and FIG. 3 shows a single piece of side core and a piece of center iron. 1 and FIGS. 6 to 8 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 2 or FIG. 3, reference numeral 51 denotes a directional silicon steel sheet as a core sheet material, and the direction indicated by an arrow is a rolling direction. Reference numeral 51a denotes an inner extraction portion, which is an inner portion obtained by punching a side iron core plate piece 81 from the directional silicon steel plate 51. The side iron core 8 is made of a directional silicon steel plate 51.
Are formed by stacking side core plate pieces 81 punched in an annular shape from above. In addition, the center iron core 6 has an inner extraction portion 51.
The center core plate 61 punched out simultaneously with the side core plate 81 is formed from a. Therefore, the rolling direction of the center core 6 (the plate 61 for the center core) and the direction of the magnetic flux are parallel.

FIG. 4 is a principle diagram showing the relationship between the cross-sectional area of the center core and the cross-sectional area of the side core in the present invention. The direction of the arrow is the rolling direction of the center core 6 and the side cores 8. Here, the magnetic resistance according to the rolling direction and the direction of the magnetic flux of the grain-oriented silicon steel sheet 51 will be described. When the rolling direction and the direction of the magnetic flux are orthogonal, the magnetic resistance is obtained when the rolling direction and the direction of the magnetic flux are parallel. It is known that when the rolling direction and the direction of the magnetic flux intersect at 45 degrees, it becomes about three times that when the rolling direction and the direction of the magnetic flux are parallel. In general, the cross-sectional area of the core portion where the coil is not wound is about 80% of the cross-sectional area of the core portion where the coil is wound.

Next, the relationship between the cross-sectional area of the center iron core 6 and the cross-sectional area of the side iron core 8 will be described based on the rolling direction of the directional silicon steel sheet 51 with reference to FIG. When the center core 6 and the side cores 8 are formed (laminated) to have the same thickness (height), the ratio of the cross-sectional area perpendicular to the direction of the magnetic flux is determined by the width of the center core plate piece 61 (perpendicular to the magnetic flux). The length of the side iron core plate piece 81 (the length in the direction perpendicular to the magnetic flux) can be considered as a ratio between the length of the side iron core plate piece 81 and the width of the side core plate 81.

First, in the range of the portion a of the side core plate 81, since the rolling direction of the side core plate 81 and the direction of the magnetic flux are orthogonal to each other, the width of the side core plate 81 is set to the center core plate. It is sufficient to set the width of the piece 61 to 0.8 times. Next, in the range of the part b of the side core plate 81, the rolling direction of the side core plate 81 and the direction of the magnetic flux intersect at 45 degrees, so that the width of the side core plate 81 is That is, the width may be set to 1.2 times the width of the plate 61. Further, in the range of the portion c of the side core plate 81, the rolling direction of the side core plate 81 and the direction of the magnetic flux are parallel to each other, so that the width of the side core plate 81 is set to the width of the center core plate 61. That is, the width may be set to 0.4 times the width.

As described above, according to one embodiment of the present invention, the annular side core plate 81 is cut out from the grain-oriented silicon steel plate 51 and the side core 81 is stacked to form the side core 8. Is formed, it is not necessary to assemble the side iron core 8 by combining the side iron core parts 8a as in the related art, so that the ignition coil 1 for the internal combustion engine can be manufactured by assembling with good workability. Further, since it is not necessary to assemble the side cores 8 as in the prior art, performance degradation due to insufficient press-fitting or misalignment of each side core part 8a is eliminated, so that stable performance as the internal combustion engine ignition coil 1 is achieved. The expected performance can be secured.

Since the side core plate piece 81 forming one plane can be cut out by a single press, the side iron core plate 8 is formed from four conventional side core parts 8a. Since the number of presses for forming the plate piece 81 is only １ ／ of the number of presses in the related art, the life of the press die is prolonged, and the manufacturing cost can be reduced. Further, when the side core plate 81 is punched, the center core plate 61 is co-extracted from the inner extraction portion 51a, so that the press die for forming the center core plate 61 and the side core plate 81 is not provided. Since only one unit is required, the cost required for the press die can be reduced, and the manufacturing cost can be reduced.

Further, the cross-sectional area of the portion where the rolling direction of the side core 8 is perpendicular to the direction of the magnetic flux is 0.8 times the cross-sectional area of the center core 6 with respect to the cross-sectional area perpendicular to the direction of the magnetic flux of the center core 6. The cross-sectional area of the part where the rolling direction of the side core 8 and the direction of the magnetic flux intersect at 45 degrees is defined as the center core 6
And the cross-sectional area of the portion where the rolling direction of the side core 8 and the direction of the magnetic flux are parallel is set to 0.4 times the cross-sectional area of the center core 6. Becomes equal to the magnetic flux density of the center iron core 6. Therefore, the magnetic flux effectively flows through the side iron core 8, the expected performance can be expected without deteriorating the performance, and the planar projected area is reduced, so that the ignition coil 1 for the internal combustion engine is reduced. Can be reduced in size.

FIG. 5 is an explanatory view showing another arrangement relationship between the center core and the side cores according to the present invention. In addition,
The cross-sectional area of each part is set in the relationship shown in FIG.
Each arrow indicates the rolling direction of the center core 6 (the plate 61 for the center core) or the rolling direction of the side core 8 (the plate 81 for the side core).

As shown by a solid line in FIG.
At both ends of (center iron plate 61) side iron 8
The center core 6 may be opposed to the portion b of the (side core plate 81) or, as shown by a dashed line in FIG.
At both ends of (center iron plate 61) side iron 8
The relationship described with reference to FIG. 4 is obtained even when facing the portion c of the (side iron plate 81). Therefore, the same effect can be obtained even if the center core 6 and the side cores 8 are arranged in a positional relationship shown by a solid line or a dashed line in FIG. 5, or a positional relationship not shown in FIGS. it can.

In the above embodiment, the secondary coil 5 is provided outside the primary coil 3. However, the primary coil 3 may be provided outside the secondary coil 5, or the primary coil 3 and the secondary coil 5 may be connected to each other. May be arranged in the left-right direction. Also,
Although the permanent magnet 7 is provided between the center core 6 and the side core 8, the permanent magnet 7 may not be provided.

Further, although the iron core plate is made of the directional silicon steel plate 51, any other iron core plate may be used as long as it functions similarly. The cross-sectional area of the part a of the side core 8 is set to 0.6 to 1.2 times the cross-sectional area of the center core 6, and the cross-sectional area of the part b of the side core 8 is set to 0.9 times the cross-sectional area of the center core 6. The cross-sectional area of the portion c of the side iron core 8 is set to 0.3 to 0.1 times the cross-sectional area of the center iron core 6.
In the case of 6 times, as shown in FIG. 2 or 3, the other portions are sequentially increased from the smaller cross-sectional area to the larger one, and are sequentially reduced from the larger cross-sectional area to the smaller one. Is also good.

[0025]

As described above, according to the present invention, an annular side core plate is cut out of an iron core plate,
Since the side iron cores are stacked to form the side iron core, it is not necessary to assemble the side iron core by combining the side iron core parts as in the related art. Can be manufactured. In addition, since there is no need to assemble the side cores as in the past, performance degradation due to insufficient press-fitting or misalignment of parts for each side core is eliminated, resulting in stable performance as an internal combustion engine ignition coil, Performance can be ensured.

Since the side core plate piece forming one plane can be die-cut with a single press, the side iron plate piece can be cut in comparison with the conventional method of forming a side core from four side core parts. since the pressing times to form requires only 1/4 of the conventional number, life of the press mold is prolonged, Ru can reduce the manufacturing cost.

Further, with respect to the cross-sectional area orthogonal to the direction of the magnetic flux of the center core, the cross-sectional area of the portion where the rolling direction of the side core and the direction of the magnetic flux are orthogonal is 0.6 to 1 times the cross-sectional area of the center core. The cross-sectional area of the portion where the rolling direction of the side core and the direction of the magnetic flux intersect at 45 degrees is 0.9 to 2.0 times the cross-sectional area of the center core. Since the cross-sectional area of the part parallel to the direction is 0.3 to 0.6 times the cross-sectional area of the center core, the magnetic flux density of each part of the side core becomes equal to the magnetic flux density of the center core. Therefore, the magnetic flux flows effectively through the side iron core, and the expected performance can be expected without deteriorating the performance.In addition, since the plane projection area is reduced, the ignition coil for the internal combustion engine can be reduced in size. Can be

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an ignition coil for an internal combustion engine.

FIG. 2 is an enlarged plan sectional view of the ignition coil for an internal combustion engine, which is one embodiment of the present invention, corresponding to line XX in FIG. 1;

FIG. 3 is an explanatory view in which a plate piece for a center core and a plate piece for a side core are taken together from a single core plate material.

FIG. 4 is a principle diagram showing a relationship between a cross-sectional area of a center iron core and a cross-sectional area of a side iron core according to the present invention.

FIG. 5 is an explanatory diagram showing another arrangement relationship between a center iron core and a side iron core according to the present invention.

FIG. 6 is an enlarged plan sectional view of a conventional ignition coil for an internal combustion engine corresponding to line XX in FIG. 1;

FIGS. 7A and 7B are explanatory views showing an example of a conventional side iron core and an assembling method.

8 (a) and 8 (b) are explanatory views showing another example of a conventional side iron core and an assembling method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ignition coil for internal combustion engines 2 Primary coil bobbin 3 Primary coil 4 Secondary coil bobbin 5 Secondary coil 6 Center core 7 Permanent magnet 8 Side core 8a Side core parts 9 Insulation case 10 Primary terminal 11 Secondary terminal 51 Iron core plate (directionality) Silicon steel sheet) 51a Inner extraction part 61 Plate for center core 81 Plate for side core

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 1-257312 (JP, A) JP-A 7-263256 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 27 / 24,38 / 12 H01F 38 / 42,41 / 02 F02P 15/00

Claims (1)

(57) [Claims] 1. A primary coil and a secondary coil, a center core inserted inside each coil, and an annular ring disposed outside each coil to form a closed magnetic circuit with the center core. An internal combustion engine ignition coil including a side iron core, wherein the side iron core is formed by stacking a single annular side core plate piece punched from an iron core plate, and the direction of the magnetic flux of the center iron and the direction of the iron core plate Rolling method
With the direction parallel to the direction of the magnetic flux of the center core.
On the other hand, the rolling direction of the side core and the direction of the magnetic flux are
The cross-sectional area of the orthogonal part is the cross-sectional area of the center core.
0.6 to 1.2 times, and the rolling direction of the side iron core
The cross-sectional area of the part where the direction of the magnetic flux intersects at 45 degrees is
0.9 to 2.0 times the cross section of the center core
The rolling direction of the side iron core is parallel to the direction of the magnetic flux.
The cross-sectional area of the part is 0.3 times or more of the cross-sectional area of the center core.
An ignition coil for an internal combustion engine, which is 0.6 times as large .