JPH0963873A - Igniter for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable igniter for an internal combustion engine, excellent in heat shock resistance insulation and durability. SOLUTION: A center core 7, a low voltage side core 18 or a high voltage side core 9 is built in a resilient compositional member, e.g. a primary bobbin 1, a secondary bobbin 3 or a case 5, or the high voltage side core 9 is placed in a pocket part 3a made in the secondary bobbin 3, or the low voltage side core 18 is coated with a resilient member thus isolating them from insulating epoxy resin 6 in an igniter for the internal combustion engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine ignition device, and more particularly to a cylindrical ignition device housed in a plug hole.

[0002]

2. Description of the Related Art A conventional ignition device is disclosed in Japanese Patent Application Laid-Open No. 2-9291.
As disclosed in Japanese Patent No. 3, the open magnetic circuit core is housed inside a cylindrical case, and a primary coil and a secondary coil are fitted outside the core to form an insulating resin inside the case. Was an open magnetic circuit type igniter in which the side core was built in the cylindrical wall in the case.

[0003]

In the above prior art,
Since the periphery of the core is in direct contact with the filled insulating material and the difference in the coefficient of thermal expansion between the core and the filled insulating material is large, cracks may occur inside the filled insulating material due to thermal shock, etc. There is a problem that peeling occurs between the core and other components such as the core, and dielectric breakdown occurs at the portion where the peeling occurs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ignition device for an internal combustion engine, which prevents internal cracks and peeling between the insulating material and the constituent members and which has excellent insulation durability.

[0005]

SUMMARY OF THE INVENTION An ignition device for an internal combustion engine which achieves the above object is a cylindrical coil comprising a primary coil and a secondary coil wound around the primary coil via an electrically insulating layer. Layer, a center core disposed in the cylinder of the coil layer and extending in the axial direction, and low pressures respectively disposed on both ends of the center core and extended in the radial direction separately on the low voltage side and the high voltage side of the secondary coil. An inner core formed of a side core and a high-voltage side core to form a magnetically coupled inner closed magnetic path; a filling insulating material that electrically insulates between the coil layer and the inner core; A constituent member made of an elastic material that encloses the inner core so as to separate the core from the filling insulating material, the inner core filled with the filling insulating material, and fixed by the filling insulating material, the constituent member, and Accommodates coil layers A case that has a possible break of the spreading circumferentially extending axially, are disposed on the outer periphery of the case is intended to include a cylindrical outer core forming an outer closed magnetic circuit.

Further, the constituent member is also used as a primary bobbin for the primary coil, and the primary bobbin includes the center core and the low pressure side core, and the low pressure contained in the primary bobbin. The side core may be formed by covering the upper side of the low-voltage side core with an elastic member from the axially upper side and separating it from the filling insulating material.

In other words, the primary bobbin and the secondary bobbin are provided around the core so that the filling insulating material does not come into direct contact with the core.
The structure shall be such that it is enclosed by the next bobbin or case and other components, and is isolated from the filling insulating material. Furthermore, a structure such as a primary bobbin, a secondary bobbin, or a case that is difficult to be enclosed by a component such as a case is covered with an elastic member that absorbs thermal stress between the core and the filling insulating material so as to be isolated.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of an internal combustion engine ignition apparatus according to an embodiment of the present invention. Primary bobbin 1
Is molded from a thermoplastic synthetic resin as an elastic material such as polybutylene terephthalate (PBT) or polyphenylene sulfide (PPS), and the primary coil 2 is wound around the primary bobbin 1. A secondary coil 4 is wound on a secondary bobbin 3 formed of a thermoplastic synthetic resin as an elastic material such as modified polyphenylene oxide (modified PPO). A cylindrical coil layer is composed of at least the primary coil 2 and the secondary coil 4. That is, in the case of the coil layer having a structure without a bobbin, the secondary coil is simply wound around the primary coil via the electrically insulating layer. In addition, if specifically described, the primary coil 2
The enamel wire having a wire diameter of 0.3 to 1.0 mm is wound several tens of times per layer, for a total of 100 to 300 times over several layers. The secondary coil 4 has a wire diameter of 0.03 to 0.
Using an enameled wire of about 1 mm, a total of 5000 to 200
It is divided and wound around 00 times.

On the other hand, the case 5 is formed of a thermoplastic synthetic resin as an elastic material similar to that of the primary bobbin 1, and the case 5 and the connector portion 24 are integrally formed.

In the case of the cylindrical ignition device as in this embodiment, the axial dimension is long, so that a taper of 1 ° or less is required in molding. Therefore, only the coil accommodating portion inside the case 5 is provided with the withdrawal taper.
The center core 7, which forms the main core of the inner core, is formed by pressing and laminating silicon steel plates, and is arranged inside the primary bobbin 1 as a constituent member made of an elastic material. The side core 8 as an outer core is arranged on the outer periphery of the case 5 outside the secondary coil 4 and is formed by rolling a thin silicon steel plate into a cylindrical shape.

The side core 8 has a cut 8a extending in the axial direction and expanding in the circumferential direction, which will be described later. The side core 8 of this embodiment has a plate thickness of 0.3 to
It is composed of one 0.7 mm silicon steel plate. However, it is possible to reduce the eddy current loss of two or more sheets and increase the cross-sectional area of the side core 8 to improve the output.

Center core 7 forming a main inner closed magnetic circuit
And a side core 8 forming an outer closed magnetic path are magnetically coupled to each other so as to complete the closed magnetic path. 18 and the high voltage side core 9 on the high voltage side of the secondary coil 4 are separately arranged. The center core 7
The inner core formed of the high-voltage side core 9 and the low-voltage side core 18 forms an inner closed magnetic circuit.

In the present embodiment, the center core 7 and the low pressure side core 18 are integrally pressed into a T shape and housed inside the primary bobbin 1. And, the upper part of the low voltage side core 18 is
Elastic member 12 made of flexible epoxy resin or rubber material
Cover with. As a result, the insulating epoxy resin 6 serving as the filling insulating material is isolated from the center core 7 and the low voltage side core 18. Forming the T-shaped core integrally as described above reduces the loss of magnetic energy (magnetic loss), improves the workability of assembling the low pressure side core 18 and the primary bobbin 1, or This leads to reduction of mold cost.

The high voltage side core 9 is housed in a pocket 3a provided in the secondary bobbin 3 as a constituent member made of an elastic material, and is isolated from the insulating epoxy resin 6. The pocket 3a for housing the high-voltage side core 9 can be provided not only on the secondary bobbin 3 but also on the primary bobbin 1 and the case 5. That is, the pocket portion 3a can be integrally formed with any of the primary bobbin 1, the secondary bobbin 3 and the case 5. Further, only the pocket portion 3a can be press-fitted or adhesively fixed to the case 5 as a separate component.

There is a core gap in a part of the closed magnetic circuit core, and a magnet 10 for generating a magnetic flux in the magnetic path in a direction opposite to the magnetic flux formed by the primary coil 2 is fitted in the core gap. The magnet 10 is designed to be operated below the saturation point of the magnetization curve of the silicon steel sheet core by generating magnetic flux in opposite directions in the magnetic path. For example, if a magnet having a holding force of 5 kOe or more is used, demagnetization due to heat is small, so that it is possible to perform integral molding with the resin case. These coil component parts are
Press-fitted into case 5, Tg point is 115 ℃ -135 ℃
And the coefficient of thermal expansion is a value close to that of a copper heat sink having an average value of 10 to 50 × 10 ⁻⁶ / ° C. in a temperature range below the Tg point, for example, 25 × 10 ⁻⁶ / ° C. It is insulated from high voltage by an insulating layer made of resin 6.
The high voltage generated in the secondary coil 4 is arranged in a direction perpendicular to the longitudinal direction so as to reduce the length of the ignition device by a high voltage diode 17 for preventing pre-ignition, a high voltage terminal 13, a spring. It is supplied to the spark plug via 14. The portion where the spark plug is inserted is insulated by a rubber boot 15 such as silicon rubber. A seal rubber 16 for sealing is provided at a portion in contact with the cylinder head cover.

The igniter unit 20 located above the coil and housed in the case 5 is an electric circuit for generating a high voltage for ignition. The power transistor chip 21 and the hybrid IC circuit 28 are contained in a metal base 26 made of copper or aluminum which is press-molded in a box shape, and a silicon gel 29 is filled therein. The igniter unit 20 is provided with the positioning protrusions 53, 52 of the igniter unit 20 provided on the case 5.
(Not shown in FIG. 1). Also,
The igniter-side terminal 22 is bonded to the metal base 26 with a thermoplastic synthetic resin such as polybutylene terephthalate, and the integrally molded terminal block 27 is bonded with a silicone adhesive. The igniter side terminal 22 is a primary coil terminal 23.
It is electrically connected to the connector-side terminal 25 by welding.

Next, the structure of the present invention will be described in detail with reference to FIG. FIG. 2 is an exploded view of the main components of the embodiment of FIG. The center core 7 is pressed and laminated integrally with the low pressure side core 18, and is formed as a T-shaped core of an embodiment according to the present invention. The T-shaped core including the center core 7 and the low-voltage side core 18 after the magnet 10 is attached is housed inside the primary bobbin 1. In other words, the T-shaped core as one inner core is included in the primary bobbin 1. In the case of the cylindrical coil as in this embodiment, a T-shaped core is fixedly housed in the primary bobbin 1 in order to easily assemble the low pressure side core 18 from above the primary bobbin 1 in the axial direction. There is formed a T-shaped pocket portion 1a.
Therefore, the primary bobbin 1 made of an elastic material is also used as a constituent member made of an elastic material enclosing the inner core so as to separate one inner core composed of the center core 7 and the low-voltage side core 18 from the filling insulating material 6. Will be.

In this case, the closed magnetic circuit gap between the low-voltage side core and the side core in the portion where the low-voltage side core 18 is accommodated is, considering the wall thickness of the case 5 and the primary bobbin 1 and the magnetic loss. It will be limited to the range of 1.0 mm to 2.5 mm. The elastic member 12 made of flexible epoxy resin or the like for absorbing thermal stress is provided on the low-voltage side core 18.
The T-section height Hp of the T-shaped pocket portion 1a, which is provided for casting, is smaller than the T-section height Hc of the low pressure side core 18.
It is configured to be high. By the way, there are various embodiments of the T-shaped core. The embodiment shown in FIG.
The center core 7 and the low-voltage side core 18 are examples in which blocks formed by pressing and laminating the silicon steel plates are laminated separately in a polygonal shape. In addition, as shown in FIG. 4, there is also an example in which the width is sequentially increased and decreased in the pressing step of the silicon steel sheet to be laminated so as to approximate a cylindrical shape and the cross-sectional area is increased. Separately from FIGS. 3 and 4, the center core 7 and the low-pressure side core 18 may be integrally laminated by sequentially increasing and decreasing the press width to form a T-shaped core as shown in FIG.

Returning to FIG. 2, as shown in the figure, the primary bobbin 1 as one constituent member containing one inner core.
Is press-fitted into the secondary bobbin 3 via the press-fitting portion 1c. The secondary bobbin 3 as the other component has a pocket portion 3a for accommodating the high pressure side core 9 as the other inner core inserted in the radial direction, and the high pressure side core 9 is included in the pocket portion 3a. After that, it is press-fitted and fixed to the case 5 via the press-fitting portion 3c. Further, in this case, the closed magnetic circuit gap between the high voltage side core 9 and the side core 8 is equal to the thickness of the case 5 and 2
Considering the thickness of the next bobbin 3 and the magnetic loss, 1.0
It will be limited to the range of mm to 2.5 mm. The press-fitting structure of the primary bobbin 1 and the secondary bobbin 3, the secondary bobbin 3 and the case 5 also isolates the high voltage side core 9 from the insulating epoxy resin 6.

As described above, the inner core composed of the center core 7, the low voltage side core 18 and the high voltage side core 9 enclosed by the primary bobbin 1 and the secondary bobbin 3 as the constituent members made of the elastic material is filled and insulated. Since it is isolated from the insulating epoxy resin 6 as a material, thermal stress or thermal shock generated due to the difference in thermal expansion coefficient between the inner core and the filling insulating material is a primary component of the elastic material. The bobbin 1 and the secondary bobbin 3 absorb the cracks of the insulating epoxy resin 6 and the peeling of the insulating epoxy resin from other members due to the thermal stress and the like.

On the other hand, the cylindrical side core 8 as an outer core, which is arranged outside the case 5 and forms an outer closed magnetic circuit, has a cut 8a which extends in the axial direction and can be expanded in the circumferential direction. By expanding the cut 8a in the circumferential direction, an escape area for radial deformation or strain due to thermal expansion of the inner core or the filling insulating material can be provided. In other words, without the cut 8a, the deformation or the like pressed by the cylinder escapes in the axial direction, and the thermal stress in the axial direction increases. Therefore, by having the break 8a,
An increase in axial thermal stress is avoided, and cracks in the insulating epoxy resin 6 and peeling between the insulating epoxy resin 6 and other members due to the thermal stress are prevented.

Furthermore, after assembling the center core 7, the low pressure side core 18, the primary bobbin 1 and the secondary bobbin 3 which are the main components shown in FIG. 2 in the case 5, the T-shaped pocket portion of the primary bobbin 1 1a, that is, (Hp-H
Due to the dimensional difference of c), the elastic member 12 for mainly absorbing the thermal stress in the axial direction is cast, and the upper side of the low-voltage side core 18 is covered with the elastic member in the axial direction to form a filling insulating material. The low-voltage side core 18 or the center core 7 is isolated from the insulating epoxy resin 6. The elastic member 12 mainly absorbs the axial thermal stress (axial thermal stress that tends to increase as described above) generated due to the difference in thermal expansion coefficient between the inner core and the filling insulating material. The effect of preventing cracks and peeling can be further enhanced.

The above can be summarized as follows. That is,
Make sure that the filling insulation does not come into direct contact with the core,
A core bobbin such as a center core or a high-voltage side core is enclosed by a constituent member such as a primary bobbin, a secondary bobbin, or a case,
By adopting a structure that is isolated from the filling insulating material, occurrence of internal cracks and peeling between the filling insulating material and the constituent members can be prevented. Further, in the case of the cylindrical coil, in consideration of the assembling workability, the components are assembled from above in the axial direction, so that the low-voltage side core is housed in the primary bobbin from above in the axial direction of the primary bobbin. However, since the upper portion of the low-voltage side core cannot cover the low-pressure side core with a component such as a primary bobbin due to the workability of assembling the cylindrical coil, an elastic member for absorbing thermal stress is filled with the low-pressure side core. It is to be inserted between the insulating material.

That is, a structure such as a primary bobbin, a secondary bobbin, or a case which is difficult to be enclosed by a constituent member such as a case is covered with an elastic member that absorbs thermal stress between the core and the filling insulating material so as to be isolated. In addition, it is possible to prevent occurrence of internal cracks and peeling between the filled insulating material and the constituent members. As a result, a highly reliable cylindrical ignition device having excellent thermal shock resistance and insulating properties is provided.

FIG. 6 is a layout view of an igniter unit according to an embodiment of the present invention. As shown in FIG. 6, the igniter unit 20 is positioned by laterally fixing the igniter unit 20 by positioning projections 52 and 53 provided on the case 5 and vertically mounting it on the case 5. The positioning protrusions 52,
The protrusion 53 extends to the upper end surface of the case 5 so as to facilitate the workability of assembling the case 5 from above. The connector side terminal 25a is connected to the primary coil terminal 23b, and the other connector side terminals 25b, 2
5c is connected to the igniter side terminals 22c and 22b, respectively. Further, the igniter side terminal 22a and the primary coil terminal 23a are connected. Primary coil terminals 23a, 23
b is arranged on both sides of the igniter unit 20 because it is connected from the primary bobbin 1.

Next, FIG. 7 is a partial bird's-eye view showing the connection structure of FIG. 6, and the connection method with the primary coil will be described in detail with reference to the drawing. Primary coil terminal 2 on primary bobbin 1
A primary coil terminal press-fitting pocket portion 1b for fixing 3a is provided, and the primary coil terminal 23 is provided in the pocket portion 1b.
a is press-fitted and fixed. The primary coil winding portion 23a1 of the primary coil terminal 23a is bent from the primary bobbin 1 in an L-shape in the radial direction (vertical direction).
The terminal is configured to be easily wound. Further, on the side to be welded to the igniter side terminal 22a, the curved portion 23a is partially formed for the purpose of relaxing / absorbing the stress during welding and preventing the stress from being transmitted to the primary coil winding portion 23a1.
2 are provided. Igniter side terminals 22a, 22b, 2
2c and connector side terminals 25a, 25b, 25c are L
It is processed into a letter shape.

The welding points are arranged in a horizontal row. Therefore, the welding work is easy. further,
In the case of welding work, it is necessary to configure so that spatter does not scatter in the coil winding portion. In this embodiment, as shown in FIG.
Arrange to cover the next coil 2). However, it is necessary to dispose the insulating epoxy resin 6 within a range that does not adversely affect the castability of the insulating epoxy resin 6 and the workability of wiring with the primary coil 2.
Further, the welding position of each terminal is set to 1 mm or more from the coil accommodating portion 5c of the case 5 in order to keep the range where the spatter is scattered away from the coil winding portion. Further, the tip of the terminal to be welded is configured to come to a position 2 to 6 mm inward from the end surface of the case 5, and is always covered with the insulating epoxy resin 6 to ensure waterproof reliability.

After fixing the igniter unit 20 and casting and curing the insulating epoxy resin 6 as described above, the high pressure side core 9 is housed in the pocket 3a of the secondary bobbin 3.
After fixing with an adhesive, the cylindrical side core 8 is made into a case 5 by utilizing the spring action of the side core 8 made of a thin plate.
Attach to By the way, the cut 8a provided in at least one portion extending in the circumferential direction of the side core 8 makes it easy to use the above spring action, and is useful for improving the assembly workability when the side core 8 is inserted into the case 5. It is also a thing. Furthermore, the cut 8a is also useful for preventing a one-turn short circuit of the magnetic flux. At the same time, it is also useful for pressing the high pressure side core 9 by the spring action of the cylindrical wall surface of the side core 8 and fixing the high pressure side core 9 in the pocket portion 3a.

Here, the maximum outer diameters of the automobile engine and the cylindrical ignition device will be described. Specifically, in an automobile engine with an exhaust capacity of about 1000 to 3000 cc, for an elongated cylindrical ignition device housed in a plug hole drilled in a narrow cylinder block,
Strict size restrictions are imposed. Therefore, if the secondary energy generation value of the ignition device is limited to 30 (mJ), the maximum outer diameter of the coil portion of the ignition device is in the range of φ22 mm to φ24 (mm),
The total length of the coil portion is limited to an elongated cylindrical shape in the range of 130 to 150 (mm). Therefore, as described above, the closed magnetic circuit gap between the low-voltage side core 18 and the side core 8 and the closed magnetic circuit gap on the non-direct contact side between the high-voltage side core 9 and the side core 8 are 1.0 mm to 2.5 m.
It is limited to the range of m, in other words, to the thickness range of the elastic material that encapsulates the inner core to isolate it from the filling insulation.

FIG. 8 is a sectional view showing the structure of an internal combustion engine ignition apparatus according to another embodiment of the present invention. FIG. 9 corresponds to FIG.
FIG. 6 is a layout view of an igniter unit according to the embodiment of In this embodiment, the igniter unit 20 is a one-chip type igniter 42. 1-chip type igniter 42
Is fixed to the metal plate 41 for heat dissipation with screws or fixed with an adhesive having excellent thermal conductivity. The metal plate 41 is fixed by the positioning protrusions 52 and 54 provided on the case 5. The terminal connection method, configuration, etc. are the same as those of the embodiment shown in FIGS. 1, 6, and 7, and the description thereof will be omitted.

[0032]

According to the present invention, each core is encapsulated by a resin component having elasticity such as a primary bobbin, a secondary bobbin, or a case, or a part of the core is covered with an elastic member. Since it can be isolated from the insulating epoxy resin, it has the effect of preventing cracks due to thermal stress and peeling between constituent members, and improving the durability (insulation deterioration resistance, etc.) of the internal combustion engine ignition device. .

[Brief description of drawings]

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

FIG. 2 is an exploded view of main components of the embodiment shown in FIG.

FIG. 3 is a diagram showing a T-shaped core according to another embodiment of the present invention.

FIG. 4 shows a T-shaped core according to another embodiment of the present invention.

FIG. 5 is a view showing a T-shaped core according to another embodiment of the present invention.

FIG. 6 is a layout view of an igniter unit according to an embodiment of the present invention.

7 is a partial bird's-eye view showing the connection structure of FIG.

FIG. 8 is a cross-sectional view showing the configuration of an internal combustion engine ignition device according to another embodiment of the present invention.

9 is a layout view of the igniter unit of the embodiment of FIG.

[Explanation of symbols]

1 ... Primary bobbin, 1a ... T-shaped pocket portion, 1b ... Primary coil terminal press-fit pocket portion, 1c, 3c ... Press-fit portion, 2 ...
Primary coil, 3 ... Secondary bobbin, 3a ... Pocket part, 4 ...
Secondary coil, 5 ... Case, 5c ... Coil accommodating portion, 6 ... Insulating epoxy resin, 7 ... Center core, 8 ... Side core,
8a ... Break, 9 ... High-voltage side core, 10 ... Magnet, 1
2 ... Elastic member, 13 ... High voltage terminal, 14 ... Spring, 1
5 ... Rubber boot, 16 ... Seal rubber, 17 ... High voltage diode, 18 ... Low voltage side core, 20 ... Igniter unit,
21 ... Power transistor chip, 22, 22a, 22
b22c ... igniter side terminals, 23, 23a, 23b ...
Primary coil terminal, 23a1 ... Primary coil winding portion, 2
3a2 ... primary coil terminal curved portion, 24 ... connector, 2
5, 25a, 25b, 25c ... Connector-side terminals, 26 ...
Metallic base, 27 ... Terminal block, 28 ... Hybrid IC
Circuit, 29 ... Silicon gel, 41 ... Heat sink, 42 ... 1-chip igniter, 43 ... Screw, 52, 53, 54 ... Positioning protrusion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazutoshi Kobayashi 2520 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Ltd. Automotive Equipment Division, Hitachi, Ltd. (72) Hiroshi Watanabe 2520, Takaba, Hitachinaka City, Ibaraki Prefecture Company Hitachi, Ltd. Automotive Equipment Division (72) Inventor Hidetoshi Oishi 2520 Takaba, Hitachinaka City, Ibaraki Prefecture Stock Company Hitachi Ltd. Automotive Equipment Division (72) Inventor Kenichi Katakishi 2477 Takaba, Hitachinaka City, Ibaraki Stock Company Inside Hitachi Car Engineering (72) Inventor Eiichiro Kondo 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Car Engineering Co., Ltd.

Claims (6)

[Claims] 1. A cylindrical coil layer comprising a primary coil and a secondary coil wound around the primary coil with an electrical insulating layer interposed therebetween, and arranged in the cylinder of the coil layer and extending in the axial direction. And a low-voltage side core and a high-voltage side core, which are located at both ends of the center core and are respectively extended to the low-voltage side and the high-voltage side of the secondary coil and extended in the radial direction and arranged respectively, and are magnetically coupled. An inner closed magnetic path, a filling insulating material that electrically insulates the coil layer from the inner core, and an inner core that includes the inner core so as to separate the inner core from the filling insulating material. A member made of an elastic material, a case for accommodating the inner core filled with the filling insulating material and fixed by the filling insulating material, the constituent member, and the coil layer; Can be expanded in any direction Such has a break, the ignition apparatus for internal combustion engine which comprises a cylindrical outer core disposed on the outer periphery of the casing forming the outer closed magnetic circuit. 2. The ignition device for an internal combustion engine according to claim 1, wherein the constituent member has a pocket portion for accommodating the high pressure side core inserted in a radial direction. 3. The internal combustion engine according to claim 1, wherein the constituent member is also used as a primary bobbin for the primary coil, and the primary bobbin includes the center core and the low pressure side core. Ignition system for engines. 4. The low pressure side core contained in the primary bobbin according to claim 3, wherein an upper side of the low pressure side core is covered with an elastic member from an axial direction upper side, and is isolated from the filling insulating material. An ignition device for an internal combustion engine, comprising: 5. The closed magnetic path gap between the low-voltage side core and the side cores as the outer cores, or the closed magnetic path gap between the high-voltage side core and the side cores according to any one of claims 1 to 4. Is from 1.0 mm
An ignition device for an internal combustion engine, which is in the range of 2.5 mm. 6. The ignition device for an internal combustion engine according to any one of claims 1 to 5, wherein the case houses an igniter unit.