JPH07320960A - Ignition coil for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the size of an ignition coil for internal combustion engine by reducing the used amount of a primary coil. CONSTITUTION:An ignition coil 1 for internal combustion engine is provided with a core 13, primary coil 21, secondary coil 23, and permanent magnet 27. The core 13 is composed of a pair of core components 11 and 12 having nearly U-shapes. The primary coil 21 is wound around a core 13 in the direction perpendicular to the axis L of the core 13 and, when an electric current is supplied to the coil 21, makes the core 13 to generate a magnetic flux along the axis L. The secondary coil 23 is wound around the core 13 and, when the supply of the electric current to the coil 21 is stopped, generates a voltage to ignite an internal combustion engine following the change of the magnetic flux caused by the stoppage of the current supply. The permanent magnet 28 has a platy shape and is put between the core components 11 and 12 in such a state that its magnetic poles 27alpha and 27beta obliquely cross the axis L. The magnet 27 generates another magnetic flux having a component opposite to that of the magnetic flux generated by the core 13. The side face of the magnet 27 is positioned near the side face of the core 13.

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 generating a high voltage for ignition in an internal combustion engine, and in particular, a permanent magnet is arranged in a core to increase the output voltage of a secondary coil. The present invention relates to an ignition coil for an internal combustion engine.

[0002]

2. Description of the Related Art A general ignition coil for an internal combustion engine is constructed by winding a primary coil and a secondary coil around a core (iron core). In this ignition coil, magnetic flux is generated in the core when current is supplied to the primary coil, and when current supply to the primary coil is stopped, the magnetic flux that has been generated up to that point is reduced or disappears. An electromotive force is generated in the secondary coil as the magnetic flux changes. At this time, the voltage output from the secondary coil (output voltage) is proportional to the amount of change in magnetic flux per unit time. Then, the output voltage of the secondary coil is supplied to the spark plug, spark discharge is performed at the plug, and the air-fuel mixture in the combustion chamber is ignited.

In such an ignition coil, it has been required to increase the output voltage of the secondary coil with the recent increase in output of the internal combustion engine. As a technique for dealing with this, it has been proposed to arrange a permanent magnet in the core that generates a magnetic flux in a direction opposite to the magnetic flux generated by the primary coil.

For example, in the ignition coil disclosed in Japanese Patent Laid-Open No. 4-370914, the core 51 has a square annular shape as shown in FIG. A primary coil 52 and a secondary coil 53 are wound around the outside of the core 51. A permanent magnet 54 is attached to a portion of the core 51 where the primary coil 52 is wound. Permanent magnet 5
4, the magnetic poles 54α, 54β are orthogonal to the axis L of the primary coil 52, and the direction of the magnetic flux generated from one magnetic pole 54α (the direction indicated by the arrow B in FIG. 11) is the direction of the magnetic flux by the primary coil 52 ( It is arranged so as to be the opposite direction to the direction indicated by arrow A in FIG.

According to the ignition coil 55, the change amount of the magnetic flux when the current supply to the primary coil 52 is stopped is
The magnetic flux is increased by the magnetic flux of the permanent magnet 54. Therefore, as compared with the case where the permanent magnet 54 is not used, the secondary coil 53
Output voltage increases.

Here, the performance of the ignition coil 55 in which the permanent magnet 54 is not arranged on the core 51 is generally
In Fig. 1, the saturation magnetic flux density is limited in a portion where the cross-sectional area orthogonal to the magnetic flux is smallest (where the secondary coil 53 is wound in Fig. 11). On the other hand, the performance of the ignition coil 55 in which the permanent magnet 54 is arranged in the core 51 is
Since the magnetic flux of the permanent magnet 54 is smaller than the magnetic flux of the primary coil 52, it is limited by the residual magnetic flux density of the permanent magnet 54. The residual magnetic flux density Br of the permanent magnet 54 is 0.5 to 1.0 tesla, while the saturation magnetic flux density Bs of the core 51 is approximately 1.5 tesla. Therefore, if the areas of the magnetic poles 54α and 54β of the permanent magnet 54 are set to 1.5 to 3 times the minimum value of the cross-sectional area of the core 51, a magnetic flux having a magnetic flux density close to the saturation magnetic flux density Bs of the core 51 is secured. The performance of the ignition coil 55 is improved.

[0007]

However, in the above-mentioned prior art, the magnetic poles 54α and 54β of the permanent magnet 54 are orthogonal to the axis L of the primary coil 52. Therefore, the magnetic pole 5
If the areas of 4α and 54β are to be increased, it is necessary to increase the cross-sectional area of the core 51 where the permanent magnets 54 are arranged. Then, not only the usage amount (winding length) of the primary coil 52 increases, but also
The ignition coil 55 becomes large.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to reduce the amount of the primary coil used,
An object of the present invention is to provide an ignition coil for an internal combustion engine that can be downsized.

[0009]

In order to achieve the above object, the first invention according to claim 1 is such that, as shown in FIG. 9A, an annular core M1 and an axis L are centered. The primary coil M2 is wound around the core M1 and generates a magnetic flux along the axis L in the core M1 when a current is supplied, and the primary coil M2 is wound around the core M1 and the current supply to the primary coil M2 is stopped. Then, a secondary coil M3 that generates a voltage for ignition in the internal combustion engine in accordance with a change in magnetic flux accompanying the stop is provided, and the primary coil is provided at a position where the primary coil M2 is wound in the core M1. The magnetic poles M5α and M5β of the plate-shaped permanent magnet M4 in which a magnetic flux having a component in the direction opposite to that of the magnetic flux generated by M2 is generated are the primary coils M2.
It is arranged so as to obliquely intersect the axis L of, and the side surface M4a of the permanent magnet M4 is located near the side surface M1a of the core M1.

According to a second aspect of the present invention, in addition to the structure of the first aspect, as shown in FIG. 10A, the direction of the magnetic flux generated from the magnetic pole M5α of the permanent magnet M4 is changed to the primary direction. It is set to be opposite to the direction of the magnetic flux generated by the coil M2.

A third aspect of the present invention is, in addition to the configuration of the first or second aspect of the present invention, the magnetic poles of the core M1 and the permanent magnet M4 as shown by the chain double-dashed line in FIG. M
An elastic member M6 made of a magnetic material is arranged between the elastic member M6 and 5α (M5β).

[0012]

In the first aspect of the present invention, as shown in FIG. 9A, when a current is supplied to the primary coil M2, a magnetic flux is generated along the axis L of the primary coil M2. Most of this magnetic flux passes through the core M1 and links with the secondary coil M3.
When the current supply to the primary coil M2 is stopped, the magnetic flux that has been generated in the core M1 until then is reduced or disappears. According to the change of the magnetic flux, an electromotive force is induced in the secondary coil M3 by the mutual induction action, and a high voltage is generated. The output voltage of the secondary coil M3 at this time is proportional to the amount of change of the magnetic flux per unit time. The voltage output from the secondary coil M3 (output voltage) is used for ignition in the internal combustion engine.

The permanent magnet M4 located in the core M1 where the primary coil M2 is wound generates a magnetic flux having a component in the direction opposite to that of the magnetic flux generated by the primary coil M2. For example, it is assumed that the magnetic flux is generated in the core M1 in the direction indicated by the arrow A by the current supply to the primary coil M2, and the magnetic flux indicated by the vector B is generated from the permanent magnet M4. This vector B has a component B _-A in the direction opposite to the magnetic flux generated by the primary coil M2. Due to the magnetic flux of the permanent magnet M4, the amount of change in the magnetic flux due to the supply and stop of the current in the primary coil M2 becomes larger than in the case without the permanent magnet M4, and the output voltage of the secondary coil M3 increases.

Further, in the permanent magnet M4 of the first invention, its magnetic poles M5α and M5β intersect obliquely with the axis L of the primary coil M2, and the side surface M4a thereof is the side surface M of the core M1.
It is arranged so as to be located near 1a. Therefore, as shown in FIG. 9B, the following points are superior to the case where the magnetic poles M5α and M5β are orthogonal to the axis L.

In the core M1, the size of the surface orthogonal to the axis L (the portion indicated by the broken line in FIGS. 9A and 9B) is defined as the cross-sectional areas Sa and Sb of the core M1. If these cross-sectional areas Sa and Sb are constant, the magnetic pole M5
The areas of α and M5β are larger when the magnetic poles M5α and M5β are obliquely intersected with the axis L than when they are orthogonal. Along with this, the former (when diagonally intersecting) has a larger amount of magnetic flux of the permanent magnet M4 than the latter (when orthogonally intersecting).

In other words, if the magnetic pole M of the permanent magnet M4 is assumed.
If the areas of 5α and M5β are constant, the magnetic pole M5
Cross-sectional area S when α and M5β intersect the axis L at an angle
a is smaller than the cross-sectional area Sb in the case of being orthogonal to the axis L. Therefore, as the cross-sectional area is reduced, the amount of the primary coil M2 wound around the core M1 can be reduced, and the ignition coil can be downsized.

In the second invention, when the direction of the magnetic flux of the permanent magnet M4 is not opposite to the direction of the magnetic flux of the primary coil M2 (for example, as shown in FIG. 10B, the direction of the magnetic flux of the permanent magnet M4). Is orthogonal to the magnetic pole M5α), the following points are excellent.

When a current is supplied to the primary coil M2, a magnetic flux in a direction microscopically different from that of the other portions is generated at the portion where the permanent magnet M4 is arranged in the core M1. That is, in general, the permanent magnet M4 has a smaller magnetic permeability (ability to pass the magnetic flux of a substance) than the core M1 similarly to air. Therefore, a magnetic flux is generated from one end surface M1α of the core M1 toward the other end surface M1β so that the distance between the both end surfaces M1α and M1β is minimized. Both end faces M1α, M1
When β is parallel to each other, this magnetic flux is orthogonal to the end face M1α as shown by the vector C. The vector C includes a component (demagnetization component C _A ) in a direction that cancels (demagnetizes) the magnetic flux of the permanent magnet M4. The demagnetization component C _A is the permanent magnet M
The magnetic flux of 4 is a magnetic flux traveling in the opposite direction.

As shown in FIG. 10B, the permanent magnet M4
If the magnetic flux is orthogonal to the magnetic pole M5arufa, all vectors C of the core M1 becomes reduced磁成content C _A, the component C _A is largest. On the other hand, as shown in FIG. 10A, when the magnetic flux direction of the permanent magnet M4 is opposite to the magnetic flux direction of the primary coil M2, part of the vector C becomes the demagnetization component C _A. . Therefore, as the demagnetization component C _A decreases, the amount of the demagnetization component C _A offset in the magnetic flux of the permanent magnet M4 decreases. Therefore, the substantial magnetic flux of the permanent magnet M4 is larger than that in FIG.
Is bigger.

If the end of the core M1 has a shape corresponding to the permanent magnet M4, the end has a sharper shape toward the tip. Therefore, the direction of the magnetic flux generated from the magnetic pole M5α is, for example, as shown in FIG.
If it is not in the completely opposite direction to the magnetic flux due to 2, there are the following problems. In the permanent magnet M4, at a portion corresponding to the sharpened portion M1γ of the core M1, a part of the magnetic flux generated from the magnetic pole M5α is a sharpened portion M1 as indicated by a vector Bb.
Passes through γ and leaks to the outside air. As a result, the amount of magnetic flux of the permanent magnet M4 is reduced by the amount of leakage.

On the other hand, in the second invention, FIG.
As indicated by a vector Ba in, the direction of the magnetic flux of the permanent magnet M4 is completely opposite to the direction of the magnetic flux of the primary coil M2. For this reason, in the permanent magnet M4, the vector Ba even at the location corresponding to the sharpened portion M1γ
The magnetic flux indicated by is unlikely to leak to the outside air after passing through the sharpened portion M1γ. Therefore, since the leakage of the magnetic flux to the outside air is suppressed, the magnetic flux in FIG. 10A becomes larger than that in FIG. 10B.

By the way, when the core M1 and the permanent magnet M4 have dimensional variations, the following problems can be considered. For example, when the core M1 and the permanent magnet M4 are larger than a predetermined size, excessive stress is applied to the permanent magnet M4 from the core M1. This stress may cause cracks or defects in the permanent magnet M4. Also, core M
When 1 or the permanent magnet M4 is smaller than a predetermined size and a gap is formed between the two, the permanent magnet M4 may move when an external force acts on the ignition coil and vibrates. This movement impairs the energy of the permanent magnet M4.

On the other hand, in the third invention, the elastic member M6 made of a magnetic material is arranged between the core M1 and the permanent magnet M4. The elastic member M6 is elastically deformed and the core M
1 and the permanent magnet M4. Therefore, even if the core M1 and the permanent magnet M4 have variations in size as described above, the variations are absorbed by the elastic member M6.
Therefore, even if excessive stress is applied to the permanent magnet M4 from the core M1, cracks and defects are less likely to occur, and the permanent magnet M4 is less likely to move from a predetermined position.

[0024]

【Example】

(First Embodiment) A first embodiment of the first invention will be described below with reference to FIGS.

FIG. 3 shows an ignition coil 1 assembled in an internal combustion engine. The ignition coil 1 includes a housing 2 whose one side surface (the left side surface in FIG. 3) is open. A case 3 with an open upper surface is attached to the upper part of the housing 2,
An igniter 4 made up of various electronic components is arranged inside thereof. The igniter 4 constitutes a part of an ignition device of an internal combustion engine, detects and amplifies an ignition signal from an engine control device (not shown), supplies a current to a primary coil described later, and supplies the current to the primary coil. To stop.

In the housing 2, a connector 5 is provided so as to project in the horizontal direction directly above the case 3, and a substantially L-shaped terminal 7 is press-fitted into a vertical wall 6 inside the connector 5. The terminal 7 hangs down into the case 3 and is electrically connected to the igniter 4 at its lower end.
In order to position the terminal 7 with respect to the igniter 4, a locking member 8 made of synthetic resin is fixed to the lower portion of the terminal 7. A groove 9 is formed on the lower surface of the locking member 8, and the upper end of the side wall 3a of the case 3 is engaged with the groove 9. By this engagement, the terminal 7 is positioned in the vertical direction and in the horizontal direction.

As shown in FIG. 1, the housing 2 includes:
A core 13 including a pair of core constituents 11 and 12 is attached. Each core structure 11, 12 has a first leg 11a, 12a and a second leg 11 extending parallel to each other.
b, 12b and both legs 11a, 11b or 12a, 12
It is composed of connecting portions 11c and 12c that connect b, and has a substantially U shape as a whole. A protrusion 14 is integrally formed on the second leg 12b, and a recess 15 is formed on the second leg 11b. Each core structure 11, 12 is provided with a mounting hole 16 through which a fastening member (bolt or the like) for fixing the ignition coil 1 to the internal combustion engine can be inserted.
Each of the core constituents 11 and 12 having such a shape is formed by punching a steel plate made of a magnetic material into a substantially U shape by pressing or the like.
It is formed by stacking a plurality of molded products obtained by the punching.

By arranging both core constituents 11 and 12 so as to face each other, a core 13 having a substantially square ring shape is formed. Both the first leg portions 11a and 12a are inserted into the housing 2, and the other portions (the both second leg portions 11b and 1a).
2b and both connecting portions 11c, 12c) are located outside the housing 2. Then, the protrusion 14 is fitted into the recess 15 so that the second leg portions 11b and 12b are connected to each other. In this state, the pair of stoppers 18 formed on both side surfaces of the housing 2 are provided in the core structure 1
The first and the second connecting portions 11c and 12c are in contact with each other.

As shown in FIGS. 1 and 3, on the outside of both the first leg portions 11a and 12a, there is disposed a substantially rectangular tubular primary bobbin 19 with both ends open. Primary bobbin 19
Is immovably locked to the housing 2. Collar portions 19a are formed at both ends of the primary bobbin 19, respectively, and a primary coil 21 is wound between the collar portions 19a. One end of the primary coil 21 is connected to a battery (not shown), and the other end is connected to the igniter 4. When an electric current is applied to the primary coil 21, both first legs 11
Magnetic flux is generated in a and 12a along the axis L of the primary coil 21 as shown by arrow A.

On the outer side of the primary bobbin 19, a substantially rectangular tubular secondary bobbin 22 having both ends open is attached.
The secondary bobbin 22 has a plurality of collar portions 22a in the length direction thereof.
Is formed, and the secondary coil 23 is wound between the two adjacent flange portions 22a. Both ends of the secondary coil 23 are respectively connected to two output terminals 24 on the upper part of the secondary bobbin 22 (only one output terminal is shown in FIG. 3). The output terminal 24 is a connector 25 extending in parallel with the connector 5.
A spark plug (not shown) is connected to the output terminal 24.

The space inside the housing 2 is filled with a thermosetting synthetic resin 26, for example, an epoxy resin, as shown by a dot (•), and hardened. The synthetic resin 26 impregnates the primary coil 21 and the secondary coil 23. And
The synthetic resin 26 ensures the insulation of the ignition coil 1 to withstand the output voltage of the secondary coil 23.

Further, as shown in FIGS. 1 and 2, in this embodiment, a permanent magnet 27 is provided between the first leg portions 11a and 12a.
Is intervening. More specifically, each first leg 11
The end faces 13α, 13β of the a, 12a are at a predetermined angle θ (where 0 ° <θ <90 with respect to the axis L of the primary coil 21.
°) crosses diagonally. Both end surfaces 13α and 13β are separated from each other in parallel.

The permanent magnet 27 is formed by magnetizing a thin plate-shaped magnetic body, and both sides of the permanent magnet 27 are magnetic poles 27.
It becomes α and 27β. Particularly, in the present embodiment, the magnetic flux is magnetized so as to be generated in the direction orthogonal to the magnetic pole 27α. The permanent magnet 27 has a substantially uniform thickness in any part, and the opposite side surfaces 27a are parallel to the magnetic flux direction.

The permanent magnet 27 is provided on both the first leg portions 11a and 12
Between a, it is arranged so as to generate a magnetic flux in a direction substantially opposite to the magnetic flux generated in the same leg 11a, 12a when the current is supplied to the primary coil 21. And the permanent magnet 27
One magnetic pole 27α is in contact with the end surface 13α of the first leg 11a, and the other magnetic pole 27β is in contact with the end surface 13β of the first leg 12a. The opposing side surfaces 27a of the permanent magnet 27 are located near the side surfaces 13a of both the first leg portions 11a and 12a.

Further, in the first leg portions 11a and 12a, assuming that the size of the plane orthogonal to the axis L of the primary coil 21 is the cross-sectional area S, each first leg portion 11 as shown in FIG.
The a and 12a are formed such that the cross-sectional area S gradually decreases toward the permanent magnet 27 side.

The ignition coil 1 is assembled as follows. First, the terminal 7 is locked to the case 3 in which the igniter 4 is arranged, and these are attached to the housing 2. In addition, the secondary bobbin 22 around which the secondary coil 23 is wound.
Then, the primary bobbin 19 around which the primary coil 21 is wound is inserted, and these are incorporated into the housing 2.

Subsequently, as shown in FIG. 4, the core structure 1
The first leg 11 a of No. 1 is inserted into the primary bobbin 19.
In addition, the end surface 13β of the first leg 12a of the core structure 12
With the permanent magnet 27 attracted to the first leg 1
2a is inserted into the primary bobbin 19. Here, since the cross-sectional area S of each of the first leg portions 11a and 12a is gradually reduced toward the permanent magnet 27 side, both the first leg portions 11 during the insertion.
a and 12a adhere to the inner surface of the primary bobbin 19. Both first
When the legs 11a and 12a of the are inserted to the predetermined positions,
As shown in FIG. 1, both the connecting portions 11c and 12c abut the stopper 18 of the housing 2 to prevent further insertion, and the projection 14 is fitted into the recess 15 so that both the second leg portions are engaged. 11b and 12b are connected. The permanent magnet 27 contacts the first leg portion 11a and is held obliquely between the two core constituent bodies 11 and 12.

Then, the housing 2 is filled with a molten synthetic resin and cured. At this time, since the first leg portions 11a and 12a are in close contact with the inner surface of the primary bobbin 19, it is possible to prevent the synthetic resin 26 from leaking into the same primary bobbin 19.

In the ignition coil device 1 thus obtained, the first bobbin 19 has the first leg portions 11a and 12a.
, The second leg portions 11b and 12b are connected to each other, the connecting portions 11c and 12c contact the stopper 18, and the core 13 is firmly attached to the housing 2. Therefore, the ignition coil 1 having sufficient mechanical strength
Can be obtained.

Next, the operation and effect of this embodiment will be described. When an electric current is supplied to the primary coil 21 via the igniter 4 along with the operation of the internal combustion engine, a magnetic flux along the axis L of the primary coil 21 is generated. Most of this magnetic flux passes through the core 13 and links with the secondary coil 23. When the current supply to the primary coil 21 is stopped, the magnetic flux that has been generated in the core 13 until then is reduced or disappears.
In accordance with the change in the magnetic flux, an electromotive force is induced in the secondary coil 23 by the mutual induction action, and a high voltage is generated. The output voltage of the secondary coil 23 at this time is proportional to the amount of change in magnetic flux. Voltage output from the secondary coil 23 (output voltage)
Are led to the spark plug via the output terminal 24.

A permanent magnet 27 between the two core structures 11 and 12
Generates a magnetic flux having a component in a direction opposite to that of the magnetic flux generated by the current supply to the primary coil 21. In the present embodiment, the magnetic flux is generated in the core 13 in the direction indicated by the arrow A by the current supply to the primary coil 21.
On the other hand, the magnetic flux indicated by the vector B is generated from the permanent magnet 27. This vector B includes a component B _-A in the direction opposite to the magnetic flux generated by the primary coil 21. Due to the magnetic flux of the permanent magnet 27, the amount of change in the magnetic flux due to the supply and stop of the current in the primary coil 21 becomes larger than that without the permanent magnet 27, and the output voltage of the secondary coil 23 increases.

Further, the magnetic poles 27α, 27 of the permanent magnet 27
β crosses the axis L of the primary coil 21 at an angle, and the side surface 27 a of the permanent magnet 27 has both first leg portions 11 a.
It is located in the vicinity of the side surface 13a of each of a and 12a. Therefore, as compared with the case where the magnetic poles 27α and 27β are orthogonal to the axis L (corresponding to the prior art) as shown in FIG.
It is excellent in the following points.

In the core 13, the size of the surface orthogonal to the axis L (the portion indicated by the broken line in FIGS. 5A and 5B) is defined as the cross-sectional areas Sa and Sb of the core 13. If the cross-sectional areas Sa and Sb are the same, the magnetic poles 27α and 27β
Of the same magnetic poles 27α, when crossing the axis L diagonally,
The area of 27β is larger than the area when it is orthogonal to the axis L. Then, since the amount of magnetic flux generated from the permanent magnet 27 is generally proportional to the area of the magnetic pole 27α,
The amount of magnetic flux generated from the permanent magnet 27 increases.

In other words, if the areas of the magnetic poles 27α are the same, the cross-sectional area Sa when the magnetic poles 27α and 27β intersect the axis L at an angle is larger than the cross-sectional area Sb when the magnetic poles 27α and 27β intersect the axis L at right angles. Also becomes smaller. Therefore, the smaller the cross-sectional area, the smaller the amount of the primary coil 21 used with respect to the core 13, and the smaller the overall size of the ignition coil 1.

As described above, according to this embodiment, the permanent magnet 2
7, the magnetic poles 27α and 27β thereof obliquely intersect the axis L of the primary coil 21 and the side surface 27a of the permanent magnet 27.
Are arranged so as to be located in the vicinity of the side surface 13a of the core 13, so that while maintaining the amount of magnetic flux of the permanent magnet 27,
The cross-sectional area Sa of the leg portions 11a and 12a can be reduced, and the ignition coil 1 can be downsized.

The present embodiment has the following features in addition to the matters described above. In the conventional general ignition coil,
The secondary coil is connected to the output terminal via a metal terminal component fixed to the secondary bobbin. In this configuration, if the terminal component has a sharp portion, the current generated in the secondary coil leaks from the sharp portion to the core. This leak causes insulation breakdown,
The output voltage of the secondary coil may not be guided to the spark plug. In order to solve such a problem, the sharp part of the terminal component needs to be sufficiently separated from the core, but on the other hand, it causes an increase in size of the secondary coil.

On the other hand, in the present embodiment, the secondary bobbin 22
The secondary coil 23 wound around is directly connected to the output terminal 24. Therefore, since the above-mentioned terminal parts are not used, it is possible to reduce the occurrence of leakage and prevent dielectric breakdown. As a result, the ignition coil 1 can be downsized.

Further, in the conventional general ignition coil, the connector and the igniter respectively have terminals, and both terminals are electrically connected directly or by separate members. This structure has a problem that there are many electrical connection points between the connector and the igniter.

On the other hand, in the present embodiment, the igniter 4
The terminal 7 locked in the case 3 is press-fitted into the connector 5, and the terminal 7 serves as the terminal of the connector 5 and the terminal of the igniter 4. Therefore, the number of electrical connection points between the connector 5 and the igniter 4 can be reduced. (Second Embodiment) Next, a second embodiment of the second invention will be described with reference to FIG.

In the second embodiment, the magnetic pole 27 of the permanent magnet 27 is used.
The direction of the magnetic flux generated from α is opposite to the direction of the magnetic flux generated by the primary coil 21. The side surface 27a of the permanent magnet 27 is parallel to the direction of its magnetic flux. The other points are the same as in the first embodiment.

According to this embodiment, the following points are superior to the case where the direction of the magnetic flux generated from the magnetic pole 27α is not completely opposite to the magnetic flux generated by the primary coil 21 (first embodiment). .

When a current is supplied to the primary coil 21, a magnetic flux in a direction microscopically different from other portions is generated near the end faces 13α and 13β of the core 13. That is, in general, the permanent magnet 27 has a magnetic permeability (capability of passing a magnetic flux of a substance) smaller than that of the core 13 like air. Therefore, magnetic flux is generated from the end surface 13α of the core 13 toward the opposite end surface 13β so that the distance between the both end surfaces 13α and 13β is minimized. When both end surfaces are parallel to each other as in the present embodiment, this magnetic flux is orthogonal to one end surface 13α as indicated by the vector C. The vector C includes a component (demagnetization component C _A ) in a direction that cancels (demagnetizes) the magnetic flux of the permanent magnet 27. The demagnetization component C _A is a magnetic flux traveling in a direction opposite to the magnetic flux of the permanent magnet 27.

[0053] As shown in FIG. 2, if the magnetic flux of the permanent magnet 27 is perpendicular to the magnetic pole 27Arufa, all of the vector C becomes reduced磁成content C _A, the component C _A is largest. On the other hand, as shown in FIG. 6, the magnetic pole 27α of the permanent magnet 27 is
When the direction of the magnetic flux generated from is opposite to the direction of the magnetic flux generated by the primary coil 21, a part of the vector C becomes the demagnetization component C _A. Therefore, as the demagnetization component C _A decreases, the amount of the demagnetization component C _A offset in the magnetic flux of the permanent magnet 27 decreases. Therefore, the permanent magnet 27
The substantial magnetic flux of is larger in the second embodiment than in the first embodiment.

Further, in this embodiment, the end surface 13 of the core 13 is
α and 13β intersect obliquely with the axis L of the primary coil 21, and the first legs 11a and 12a of both sides have a pointed shape toward the tip.

Therefore, when the direction of the magnetic flux generated from the magnetic pole 27α of the permanent magnet 27 is not completely opposite to the magnetic flux generated by the primary coil 21, as shown in FIG. 2 (first embodiment), for example, There is a defect of. In the permanent magnet 27, at a portion corresponding to the sharpened portion 13γ of the core 13, a part of the magnetic flux generated from the magnetic pole 27α passes through the sharpened portion 13γ as shown by a vector Bb in FIG. 2 and leaks to the outside air. . As a result, the permanent magnet 2
The amount of magnetic flux of 7 decreases.

On the other hand, in the second embodiment, as indicated by the vector B in FIG. 6, the direction of the magnetic flux of the permanent magnet 27 is completely opposite to the direction of the magnetic flux of the primary coil 21. Therefore, in the permanent magnet 27, the sharpened portion 1
Even at the location corresponding to 3γ, the magnetic flux indicated by the vector Ba is unlikely to leak to the outside air via the sharp portion 13γ of the core 13. Therefore, the leakage of the magnetic flux to the outside air is suppressed,
The magnetic flux in the second embodiment is larger than that in the first embodiment. (Third Embodiment) Next, a third embodiment of the third invention will be described with reference to FIGS.

In the third embodiment, the core 13 and the permanent magnet 27 are used.
The elastic member 28 made of a magnetic material is disposed between the magnetic pole 27α and the magnetic pole 27α. As the elastic member 28, for example, a silicone adhesive mixed with magnetic powder can be used. Further, a protrusion 29 having a triangular cross section is integrally formed on the inner surface of the primary bobbin 19. This protrusion 29 is
This is for arranging the permanent magnet 27 at a predetermined position. The other points are the same as in the first embodiment.

The elastic member 28 is added because if the core 13 or the permanent magnet 27 has dimensional variations, the following problems may occur. For example, when the core 13 and the permanent magnet 27 are larger than a predetermined size, excessive stress is applied to the permanent magnet 27 from both core constituent bodies 11 and 12. This stress may cause cracks or defects in the permanent magnet 27. Further, when the core 13 and the permanent magnet 27 are smaller than a predetermined size and a gap is formed between them, when the external force acts on the ignition coil 1 and the permanent magnet 27 vibrates, the permanent magnet 27 has a predetermined position. There is a risk of moving from. Due to this movement, frictional heat is generated, and the energy of the permanent magnet 27 is lost.

On the other hand, in the third embodiment, the elastic member 28 is used.
Elastically deforms and comes into close contact with the core 13 and the permanent magnet 27.
Therefore, even if the core 13 and the permanent magnet 27 have variations in size, the variations are absorbed by the elastic member 28. Therefore, even if an excessive stress is applied to the permanent magnet 27 from the core 13, the permanent magnet 27 can be prevented from being cracked or chipped. Further, it is possible to suppress the generation of frictional heat due to the movement of the permanent magnet 27 and prevent the loss of energy of the permanent magnet 27.

Further, the protrusion 29 is formed on the primary bobbin 19 by the first
When the leg portion 12a is inserted, it functions as follows. For example, at the time of this insertion, as shown in FIG.
Of the laminated permanent magnets 27 of the first leg 12a
It is assumed that the particles are adsorbed with a slight deviation from 3β. In this case, if the protrusion 29 is not provided, the permanent magnet 27 will be disposed inside the primary bobbin 19 while being displaced. But,
In the third embodiment, when the permanent magnet 27 comes into contact with the protrusion 29 as the first leg 12a is inserted, further insertion is restricted. Therefore, when the first leg portion 12a is inserted to the predetermined position, the permanent magnet 27 is arranged at the proper position.

The present invention can be embodied in another embodiment shown below. (1) The secondary bobbin 2 with the primary bobbin 19 and the primary coil 21 being arranged outside the first leg portions 11a and 12a.
The secondary coil 23 and the secondary coil 23 may be arranged outside the second leg portions 11b and 12b. Even in this case, the same operation and effect as those of the first to third embodiments can be obtained.

(2) The core structures 11 and 12 may be changed to a shape other than the U-shape. For example, one core structure is C-shaped and the other core structure is I-shaped,
The two may be combined to form an annular core. Further, an annular core may be formed by three or more core constituents.

(3) In the first to third embodiments, the igniter 4 is incorporated into the housing 2 together with the ignition coil 1,
Although these are one assembly, the igniter 4 may be configured separately from the ignition coil 1.

(4) The elastic member 28 in the third embodiment may be arranged between the first leg 12a and the permanent magnet 27. In addition, the permanent magnet 27 and the first leg portions 11a and 12a
The elastic member 28 may be disposed between and.

Although the respective embodiments of the present invention have been described above, technical ideas other than the claims which can be understood from the respective embodiments will be described below together with their effects. (A) In the ignition coil for an internal combustion engine according to claim 1, the core 13 has a pair of U-shaped core structures 11,
12 are formed by arranging 12 to face each other, and the leg portions 11a and 12a of each core structure 11 and 12 are inserted into the primary bobbin 19 around which the primary coil 21 is wound. An ignition coil for an internal combustion engine, in which a projection 29 for positioning the permanent magnet 27 is formed.

With such a structure, the permanent magnet 27 can be locked at an appropriate position in the primary bobbin 19.

[0067]

As described above in detail, in the first aspect of the present invention, a magnetic flux having a component in the direction opposite to the magnetic flux generated by the primary coil is generated at the portion where the primary coil is wound in the core. The permanent magnets are arranged so that their magnetic poles intersect the axis of the primary coil at an angle and the side surfaces of the permanent magnets are located near the side surfaces of the core. Therefore, the amount of the primary coil used can be reduced and the ignition coil can be downsized.

In the second invention, the direction of the magnetic flux generated from the magnetic pole of the permanent magnet is set to be opposite to the direction of the magnetic flux generated by the primary coil. Therefore, in addition to the effect of the first invention, the amount of magnetic flux of the permanent magnet reduced by the current supply to the primary coil can be reduced, a large amount of change in magnetic flux can be efficiently secured, and the output voltage of the secondary coil can be increased. Can be achieved.

Further, since the magnetic flux of the permanent magnet can be prevented from passing through the core and leaking to the outside air, a large amount of change in magnetic flux can be secured from this point as well. Therefore, it is advantageous in increasing the output voltage of the secondary coil.

In the third invention, the elastic member made of a magnetic material is arranged between the core and the magnetic pole of the permanent magnet. Therefore, in addition to the effects of the first or second invention, it is possible to prevent the permanent magnet from being cracked or chipped even if the core and the permanent magnet have variations in size. Further, it is possible to suppress the movement of the permanent magnet and reduce the energy loss of the permanent magnet.

[Brief description of drawings]

FIG. 1 is a plan sectional view of an ignition coil in a first embodiment embodying the first invention.

FIG. 2 is a partial plan sectional view showing an enlarged view of the permanent magnet and its peripheral portion in FIG.

3 is a sectional view taken along line XX of FIG.

FIG. 4 is a plan sectional view showing a state where the first leg portion of the core structure is inserted into the primary bobbin.

5A and 5B are partial plan sectional views for explaining the operation of the first embodiment.

FIG. 6 shows a second embodiment embodying the second invention,
It is a fragmentary plane sectional view which expands and shows a permanent magnet and its peripheral part.

FIG. 7 is a diagram showing a third embodiment of the third invention,
FIG. 7 is a partial plan cross-sectional view showing a state in which the first leg portion to which the permanent magnet is attracted is inserted into the primary bobbin.

FIG. 8 is a state in which the first leg is further inserted from the state of FIG.
It is a fragmentary plane sectional view showing the state where the permanent magnet was arranged in the proper position by the projection.

9 (a) and 9 (b) are explanatory views for explaining the operation of the first invention.

10 (a) and 10 (b) are explanatory views for explaining the operation of the second and third inventions.

FIG. 11 is a schematic configuration diagram showing a conventional ignition coil.

[Explanation of symbols]

13 ... Core, 13a ... Core side surface, 21 ... Primary coil,
23 ... Secondary coil, 27 ... Permanent magnet, 27a ... Side surface of permanent magnet, 27α, 27β ... Magnetic pole, 28 ... Elastic member, L ...
The axis of the primary coil.

Claims (3)

[Claims] 1. A core having an annular shape, a primary coil wound around the core about an axis, and generating a magnetic flux along the axis when a current is supplied, the primary coil wound around the core, When the supply of current to the primary coil is stopped, a secondary coil that generates a voltage for ignition in the internal combustion engine according to a change in magnetic flux accompanying the stop is provided, and the primary coil is wound in the core. Is a plate-shaped permanent magnet in which a magnetic flux having a component in the direction opposite to that of the magnetic flux generated by the primary coil is generated. An ignition coil for an internal combustion engine arranged so as to be located near a side surface. 2. The ignition coil for an internal combustion engine according to claim 1, wherein the direction of the magnetic flux generated from the magnetic pole of the permanent magnet is set to be opposite to the direction of the magnetic flux generated by the primary coil. 3. The ignition coil for an internal combustion engine according to claim 1, wherein an elastic member made of a magnetic material is arranged between the core and a magnetic pole of a permanent magnet.