JP7314596B2 - Ignition coil for internal combustion engine - Google Patents

Description

The present invention relates to ignition coils for internal combustion engines.

2. Description of the Related Art Some ignition coils for internal combustion engines have a primary coil and a secondary coil that are magnetically coupled to each other, and a magnetic core. These components are housed in a case, and gaps formed in the case are filled with filling resin.

In the ignition coil disclosed in Patent Document 1, the filling resin has a resin surface at the opening of the case. The case has a partition interposed between the secondary coil and the outer core. The partition wall is erected toward the resin surface.

JP-A-10-223463

However, the ignition coil described in Patent Document 1 has the following problems.
In the ignition coil disclosed in Patent Document 1, the corners of the outer core are in contact with the filling resin. Therefore, the thermal stress due to the difference in coefficient of linear expansion from that of the outer core tends to concentrate on the filling resin near the corners of the outer core. Therefore, there is a concern that cracks may occur in the filled resin at these locations. In the outer peripheral core of the ignition coil disclosed in Patent Document 1, the corners of the end on the side closer to the resin surface are in contact with the filling resin. If cracks start from the corners and reach the resin surface, the waterproofness of the filled resin may be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object of the present invention is to provide an ignition coil for an internal combustion engine that is excellent in waterproofness.

One aspect of the present invention is a coil section (4) consisting of a primary coil (41) and a secondary coil (42) magnetically coupled to each other;
an outer core (3) that forms a magnetic circuit and is disposed on the outer peripheral side of the coil portion;
a case (5) housing the coil portion and the outer core;
a filling resin (6) that is filled in the case and embeds the coil portion and the outer core inside;
The case has an opening (50) that opens in a direction perpendicular to the coil axial direction (X), and has a partition (51) that separates the outer core and the coil,
The filling resin has a resin surface (61) formed on the opening side,
The outer peripheral core has a corner (311) at a first end (31) that is the end near the resin surface, and at least a part of the corner at the first end is covered with an elastic body (7),
The outer surface (511) of the partition wall has a contact outer surface (512) that contacts the inner peripheral surface (32) of the outer core, an inner recessed surface (513) recessed inwardly on a side closer to the opening than the contact outer surface, and an inner stepped portion (514) formed between the contact outer surface and the inner recessed surface, and the first end is positioned closer to the opening than the inner stepped portion,
The elastic body is in an ignition coil (1) for an internal combustion engine, which is formed over the corner portion on the inner peripheral side and the inner step portion of the first end portion.

In the ignition coil for an internal combustion engine, the corner of the first end, which is the end of the outer core on the side closer to the resin surface, is covered with an elastic body. Therefore, thermal stress caused by the difference in coefficient of linear expansion between the filling resin and the outer core can be absorbed by deformation of the elastic body. Therefore, it is possible to suppress the occurrence of cracks in the filling resin originating from the corner of the first end. As a result, the waterproofness of the filling resin can be improved.

As described above, according to the above aspect, it is possible to provide an ignition coil for an internal combustion engine that is excellent in waterproofness.
It should be noted that the symbols in parentheses described in the claims and means for solving the problems indicate the correspondence with specific means described in the embodiments described later, and do not limit the technical scope of the present invention.

1 is a cross-sectional view of an ignition coil for an internal combustion engine in Embodiment 1; FIG. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1; FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2; FIG. 2 is a sectional view taken along line IV-IV in FIG. Sectional drawing of the ignition coil for internal combustion engines in Embodiment 2. FIG. A cross-sectional view taken along the line VI-VI in FIG. Sectional drawing of the ignition coil for internal combustion engines in Embodiment 3. FIG. A cross-sectional view taken along line VIII-VIII in FIG.

(Embodiment 1)
An embodiment of an ignition coil 1 for an internal combustion engine will be described with reference to FIGS. 1 to 4. FIG.
An ignition coil 1 for an internal combustion engine of this embodiment has a coil portion 4, an outer core 3, a case 5, and a filling resin 6 filled in the case 5, as shown in FIG. The coil section 4 is composed of a primary coil 41 and a secondary coil 42 that are magnetically coupled to each other. As shown in FIG. 2 , the outer core 3 forms a magnetic circuit and is arranged on the outer peripheral side of the coil portion 4 .

The case 5 accommodates the coil portion 4 and the outer core 3 . The filling resin 6 embeds the coil portion 4 and the outer core 3 inside. The case 5 has an opening 50 that opens in a direction orthogonal to the coil axial direction X, as shown in FIGS. Further, the case 5 has a partition wall 51 that separates the outer core 3 and the coil portion 4, as shown in FIG. As shown in FIGS. 1 and 3, the filling resin 6 has a resin surface 61 formed on the opening 50 side. The outer core 3 has a corner portion 311 at the first end portion 31 that is the end portion closer to the resin surface 61 . At least a part of the corners 311 of the first end 31 of the outer core 3 is covered with the elastic body 7 .

The primary coil 41 is formed by winding a primary winding around the outer circumference of the primary spool 411 . The secondary coil 42 is formed by winding a secondary winding around the outer circumference of the secondary spool 421 . The winding axis of the primary coil 41 is coaxial with the winding axis of the secondary coil 42 . Note that the coil axis direction X parallel to the winding axis C of the primary coil 41 and the secondary coil 42 is also referred to as the X direction as appropriate.

In this embodiment, as shown in FIG. 2 , the elastic body 7 covers at least a portion of the corner portion 311 on the outer peripheral side of the first end portion 31 . In addition, the elastic body 7 covers at least a portion of the corner portion 311 of the first end portion 31 located on at least one side in the coil axial direction X with respect to the coil portion 4 when viewed from the normal direction of the resin surface 61 .

Further, the case 5 is provided with a flange portion 57 projecting in one direction in the coil axial direction X, as shown in FIG. At least part of the corner portion 311 of the first end portion 31 located between the coil portion 4 and the flange portion 57 in the coil axial direction X is covered with the elastic body 7 . In the X direction, as shown in FIG. 1, the side where the connector portion 53 protrudes from the case 5 is called the front side, and the opposite side, the side where the flange portion 57 protrudes, is called the rear side. That is, as shown in FIG. 2 , at least a part of the corner 311 of the first end 31 located on the rear side in the X direction is covered with the elastic body 7 .

Inside the coil portion 4, as shown in FIGS. 1 and 2, the center core 2 is arranged. In other words, the central core 2 is arranged to pass through the primary coil 41 and the secondary coil 42 . A primary coil 41 is arranged on the outer peripheral side of the central core 2 . A secondary coil 42 is arranged on the outer peripheral side of the primary coil 41 . The winding axis C of the primary coil 41 and the secondary coil 42 and the central axis of the central core 2 are substantially coaxial. As shown in FIGS. 1 and 2, the central core 2 has a substantially quadrangular prism shape.

The outer core 3 has a rectangular annular shape, as shown in FIG. The outer core 3 is arranged on the outer peripheral side of the secondary coil 42 . A central core 2 is arranged inside the outer peripheral core 3 . The outer core 3 and the central core 2 are formed by laminating a plurality of flat magnetic steel plates made of a soft magnetic material in the thickness direction. The outer core 3 and the central core 2 form a magnetic circuit perpendicular to the stacking direction of the magnetic steel plates. The outer core 3 and the central core 2 form a closed magnetic circuit. The direction perpendicular to the X direction, which is the lamination direction of the plurality of magnetic steel plates that constitute the outer core 3 and the central core 2, is also referred to as the Z direction as appropriate. A direction orthogonal to both the X direction and the Z direction is also called the Y direction as appropriate. Further, as shown in FIG. 1, in the Z direction, the side on which the opening 50 of the case 5 is located is referred to as the upper side, and the opposite side thereof, on which the high-voltage tower section 54 is provided, is referred to as the lower side.

As shown in FIGS. 1 and 3, the outer core 3 has a first end 31 which is the end near the resin surface 61 and the upper end in the Z direction. The first end portion 31 has corner portions 311 on the inner peripheral side and the outer peripheral side, respectively. The outer core 3 also has a second end 34 that is the lower end in the Z direction.

As shown in FIGS. 1 and 2, a magnet 11 is arranged between the outer core 3 and the central core 2 in the magnetic circuit formed by the outer core 3 and the central core 2 . That is, the magnet bodies 11 are arranged so as to face both the inner peripheral surface 32 of the outer peripheral core 3 and the front end surface of the central core 2 in the X direction. Further, the rear end face of the center core 2 in the X direction is arranged so as to be in contact with the inner peripheral face 32 of the outer peripheral core 3 .

The magnets 11 are arranged so that the direction of the magnetic field generated by the magnets 11 is opposite to the direction of the magnetic field generated in the central core 2 when the primary coil 41 is energized. The magnet 11 magnetically biases the central core 2 so as to improve the output voltage of the ignition coil 1 . As a result, the voltage induced in the secondary coil 42 is increased by increasing the amount of change in the magnetic flux when the primary coil 41 is de-energized. The magnet body 11 is, for example, a permanent magnet such as a neodymium magnet or a rare earth cobalt magnet.

As shown in FIG. 1, the case 5 accommodates the coil portion 4, the central core 2, the outer core 3, and other parts inside. The case 5 has side walls 52 erected toward the opening 50 . The side wall 52 is erected along the Z direction, and as shown in FIG. 2, is formed in a substantially rectangular annular shape when viewed from the Z direction. Side wall 52 is provided along outer peripheral surface 33 of outer core 3 . When viewed from the Z direction, the case 5 is wider in the X direction than in the Y direction. The case 5 is made of, for example, an electrically insulating resin.

In addition, the case 5 is filled with a filling resin 6 so as to embed the above-described components housed therein. The filling resin 6 is, for example, an epoxy resin.

Further, as shown in FIG. 1, the case 5 is provided with a connector portion 53 for connecting the ignition coil 1 to the outside. The connector portion 53 protrudes forward in the X direction. The connector portion 53 has a connection terminal (not shown) for electrically connecting the primary coil 41 to an external power source, and a resin holding portion made of resin for holding the connection terminal. Further, the connector portion 53 is formed to protrude forward from the front side wall 52 of the case 5 .

1 and 2, the case 5 is provided with a flange portion 57 for fixing the ignition coil 1 to the internal combustion engine. The flange portion 57 is formed integrally with the case 5 . The flange portion 57 protrudes rearward of the case 5 in the X direction. That is, a flange portion 57 is formed to protrude rearward from the rear side wall 52 . The flange portion 57 has a bolt insertion hole 571 penetrating in the Z direction. The ignition coil 1 is fastened and fixed to the internal combustion engine by bolts inserted through the bolt insertion holes 571 of the flange portion 57 .

As shown in FIG. 1, the case 5 has a tubular high-voltage tower 54 formed on the lower side in the Z direction so as to protrude downward. The high voltage tower section 54 electrically connects the secondary coil 42 and a spark plug (not shown). A high voltage generated in the secondary coil 42 by electromagnetic induction is transmitted to the spark plug via the high voltage tower portion 54 . The generated high voltage causes spark discharge between the spark plug discharge gaps.

As shown in FIGS. 1 and 3, the case 5 has an outer peripheral bottom portion 55 formed inwardly from the lower end of the side wall 52 on the outer peripheral side of the case 5 . The case 5 has a lower concave portion 56 formed downward inside the outer peripheral bottom portion 55 . A high voltage tower portion 54 is formed below the lower concave portion 56 . A second end portion 34 , which is the lower end portion of the outer peripheral core 3 , is in contact with the inner surface of the outer peripheral bottom portion 55 .

The partition wall 51 is erected in the Z direction from the inner peripheral side of the outer peripheral bottom portion 55 toward the opening 50, as shown in FIG. The partition wall 51 is flush with the inner peripheral surface of the lower concave portion 56 . The partition wall 51 is formed along the inner peripheral surface 32 of the outer core 3, as shown in FIG. Moreover, the partition wall 51 is formed so as to surround the outer periphery of the coil portion 4 . Also, the upper end of the partition wall 51 is located below the upper end of the side wall 52 as shown in FIG.

As shown in FIG. 2, when the ignition coil 1 is viewed from the Z direction, the partition wall 51 is not formed in the vicinity of the location where the front and rear end surfaces of the center core 2 in the X direction come into contact with the magnet body 11 and the inner peripheral surface 32 of the outer peripheral core 3. The partition walls 51 are provided at two locations in total, one on each side of the center core 2 in the Y direction. The center core 2 faces the magnet body 11 and the inner peripheral surface 32 of the outer core 3 at both ends in the X direction without interposing the partition wall 51 therebetween.

The outer surface 511 of the partition wall 51 has a contact outer surface 512 that contacts the inner peripheral surface 32 of the outer core 3, as shown in FIGS. Further, the outer surface 511 has an inner receding surface 513 that recedes inward on the side closer to the opening 50 than the contact outer surface 512 . The outer surface 511 also has an inner step 514 formed between the contact outer surface 512 and the inner recessed surface 513 . The first end 31 is located closer to the opening 50 than the inner step 514 is. As shown in FIG. 4 , the elastic body 7 is formed over the inner peripheral corner portion 311 and the inner stepped portion 514 of the first end portion 31 .

A side wall 52 of the case 5 is erected toward the opening 50 as shown in FIGS. The inner surface 521 of the side wall 52 of the case 5 has a contact inner surface 522 that contacts the outer peripheral surface 33 of the outer core 3, as shown in FIGS. In addition, the inner surface 521 has an outer receding surface 523 that recedes outward on the side closer to the opening 50 than the contact inner surface 522 . The inner surface 521 also has an outer step 524 formed between the contact inner surface 522 and the outer recessed surface 523 . The first end 31 is located closer to the opening 50 than the outer stepped portion 524 is. As shown in FIG. 4 , the elastic body 7 is formed over the corner portion 311 on the outer peripheral side of the first end portion 31 and the outer stepped portion 524 .

In this embodiment, as shown in FIG. 2, the elastic body 7 partially covers the corners 311 located on both sides of the coil portion 4 in the X direction. The elastic bodies 7 are arranged along the outer and inner corners 311 of the outer core 3 . In addition, the elastic body 7 is not arranged at the corner portion 311 where the inner peripheral surface 32 on the front side of the outer core 3 and the magnet body 11 are in contact with each other. Also, the elastic body 7 is not arranged at the corner portion 311 where the inner peripheral surface 32 on the rear side of the outer peripheral core 3 and the end surface on the rear side of the central core 2 are in contact with each other. The first end portion 31 of the outer peripheral core 3 in these portions is flush with the upper surface of the magnet body 11 or the central core 2 as shown in FIG. Therefore, the corners 311 of the first end 31 at these portions do not protrude into the filling resin 6 .

Also, the elastic body 7 has an elastic modulus lower than that of the filling resin 6 . The elastic body 7 is, for example, silicone rubber, elastomer, adhesive, or single-cell sponge.

The elastic body 7 can be placed at the corner 311 of the first end 31 in various ways. For example, as the elastic body 7 , a silicone rubber or elastomer molding can be installed at the corner 311 of the first end 31 . The elastic body 7 can also be arranged by applying silicone rubber or adhesive to the corner portion 311 of the first end portion 31 . Also, as the elastic body 7 , a single-cell sponge can be installed at the corner portion 311 of the first end portion 31 .

Further, each component constituting the ignition coil 1 in this embodiment has a different coefficient of linear expansion. The filling resin 6 has a larger coefficient of linear expansion than the central core 2 and the peripheral core 3 . Further, the case 5 , the flange portion 57 and the connector portion 53 have larger coefficients of linear expansion than the filling resin 6 , the central core 2 , the outer core 3 , the secondary winding of the secondary coil 42 and the secondary spool 421 . The secondary winding of the secondary coil 42 has a higher coefficient of linear expansion than the secondary spool 421 , filling resin 6 , central core 2 and outer core 3 . The secondary spool 421 has a higher coefficient of linear expansion than the filled resin 6 , central core 2 and outer core 3 .

In this embodiment, for example, the filling resin 6 is 40 ppm/°C, the central core 2 and the outer core 3 are 11 ppm/°C, the secondary winding of the secondary coil 42 is 47 ppm/°C, the secondary spool 421 is 43 ppm/°C, and the connector portion 53, the flange portion 57, and the case 5 have a linear expansion coefficient of 60 ppm/°C. The connector portion 53, the flange portion 57, and the case 5 are made of the same material.

Next, the effects of this embodiment will be described.
In the ignition coil 1 for an internal combustion engine of this embodiment, the corner portion 311 of the first end portion 31 , which is the end portion of the outer core 3 on the side closer to the resin surface 61 , is covered with the elastic body 7 . Therefore, the thermal stress caused by the difference in coefficient of linear expansion between the filling resin 6 and the outer core 3 can be absorbed by the deformation of the elastic body 7 . Therefore, the occurrence of cracks in the filling resin 6 originating from the corner 311 of the first end 31 can be suppressed. As a result, the waterproofness of the filling resin 6 can be improved.

In the ignition coil 1 of this embodiment, a corner portion 311 on the outer peripheral side of the first end portion 31 is covered with the elastic body 7 . Therefore, the thermal stress of the filling resin 6 can be absorbed by the elastic body 7 in the vicinity of the corner portion 311 on the outer peripheral side of the first end portion 31 where the thermal stress is particularly likely to concentrate. As a result, it is possible to suppress the occurrence of cracks in the filling resin 6 originating from the corner portion 311 on the outer peripheral side of the first end portion 31 .

In the ignition coil 1 of this embodiment, a corner portion 311 of the first end portion 31 located on at least one side in the X direction with respect to the coil portion 4 is covered with the elastic body 7 . Therefore, the occurrence of cracks in the filling resin 6 originating from the corner 311 of the first end 31 can be suppressed. Therefore, the occurrence of cracks reaching the resin surface 61 can be effectively suppressed.

In the ignition coil 1 of this embodiment, the corner portion 311 of the first end portion 31 located between the coil portion 4 and the flange portion 57 is covered with the elastic body 7 . In the ignition coil 1 having the flange portion 57 projecting in the X direction, thermal contraction or thermal expansion of the flange portion 57 occurring in the X direction occurs together with thermal contraction or thermal expansion of the filling resin 6 . As a result, large thermal stress tends to concentrate in the vicinity of the corner portion 311 of the first end portion 31 near the flange portion 57 in the first end portion 31 . Therefore, by providing the elastic body 7 at this location, the occurrence of cracks in the filling resin 6 can be effectively suppressed.

Further, in the ignition coil 1 of this embodiment, the corners 311 of the first end portion 31 located on both sides of the coil portion 4 in the X direction are covered with the elastic body 7 . Therefore, the occurrence of cracks in the filled resin 6 reaching the resin surface 61 can be more effectively suppressed.

In the ignition coil 1 of this embodiment, the inner surface 521 of the side wall 52 has a contact inner surface 522 , an outer receding surface 523 and an outer stepped portion 524 . Also, the first end portion 31 is located closer to the opening portion 50 than the outer step portion 524 is. The elastic body 7 is formed over the corner portion 311 on the outer peripheral side of the first end portion 31 and the outer stepped portion 524 . Therefore, it is easy to reliably cover the corner portion 311 on the outer peripheral side of the first end portion 31 with the elastic body 7 . As a result, it is easy to reliably suppress the occurrence of cracks in the filling resin 6 originating from the corner portion 311 on the outer peripheral side of the first end portion 31 .

In the ignition coil 1 of this embodiment, the outer side surface 511 of the partition wall 51 has a contact outer surface 512 , an inner retreating surface 513 , and an inner step portion 514 . Also, the first end portion 31 is located closer to the opening portion 50 than the inner step portion 514 is. The elastic body 7 is formed over the corner portion 311 on the inner peripheral side of the first end portion 31 and the inner stepped portion 514 . Therefore, it is easy to reliably cover the corner 311 on the inner peripheral side of the first end 31 with the elastic body 7 . As a result, it is easy to reliably suppress the occurrence of cracks in the filling resin 6 originating from the corner portion 311 on the inner peripheral side of the first end portion 31 .

As described above, according to the above aspect, it is possible to provide the ignition coil 1 for an internal combustion engine that is excellent in waterproofness.

(Embodiment 2)
In the ignition coil 1 of this embodiment, the elastic body 7 covers the corners 311 of the first end 31 over the entire circumference of the outer core 3, as shown in FIGS. Corner portions 311 of the first end portion 31 located on both sides of the coil portion 4 in the Y direction are also covered with the elastic body 7 .

In this embodiment, the corner 311 on the outer peripheral side of the first end 31 is covered with the elastic body 7 all around as shown in FIG. The elastic body 7 covering the corner portion 311 on the outer peripheral side of the first end portion 31 has a rectangular annular shape.

Further, in the present embodiment, the corner portion 311 on the inner peripheral side of the first end portion 31 is also covered with the elastic body 7 except for a part thereof. An inner corner portion 311 of the first end portion 31 at the portion where the inner peripheral surface 32 of the outer peripheral core 3 and the rear end surface of the magnet body 11 or the central core 2 are in contact is not covered with the elastic body 7 . Further, the corner portion 311 at this portion does not protrude into the filling resin 6 . That is, the first end portion 31 of this portion and the upper surface of the magnet body 11 or the central core 2 are flush with each other.
Others are the same as those of the first embodiment.
Note that, of the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the previous embodiments represent the same constituent elements as those in the previous embodiments, unless otherwise specified.

In this embodiment, the elastic bodies 7 are also installed at the corners 311 of the first end portion 31 located on both sides of the coil portion 4 in the Y direction. Therefore, the thermal stress generated in the filling resin 6 near the corner 311 can also be absorbed by the deformation of the elastic body 7 . As a result, it is possible to suppress the occurrence of cracks in the filling resin 6 near the corner 311 as well.
In addition, it has the same effects as those of the first embodiment.

(Embodiment 3)
In the ignition coil 1 of this embodiment, the elastic body 7 entirely covers the first end portion 31 of the outer core 3, as shown in FIGS. In other words, the elastic body 7 also covers the portion of the first end portion 31 other than the corner portion 311 .
Others are the same as those of the second embodiment.

In this embodiment, the entire first end portion 31 of the outer core 3 is covered with the elastic body 7 . Therefore, the thermal stress generated in the filling resin 6 in the vicinity of the portion other than the corner portion 311 of the first end portion 31 can also be absorbed by the deformation of the elastic body 7 . As a result, it is possible to more effectively suppress the occurrence of cracks in the filling resin 6 near the first end portion 31 .
In addition, it has the same effects as those of the second embodiment.

The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention.

REFERENCE SIGNS LIST 1 ignition coil 3 outer core 31 first end portion 311 corner portion 4 coil portion 41 primary coil 42 secondary coil 5 case 50 opening portion 51 partition wall 6 filling resin 61 resin surface 7 elastic body X coil axis direction

Claims (6)

a coil section (4) consisting of a primary coil (41) and a secondary coil (42) magnetically coupled to each other;
an outer core (3) that forms a magnetic circuit and is disposed on the outer peripheral side of the coil portion;
a case (5) housing the coil portion and the outer core;
a filling resin (6) that is filled in the case and embeds the coil portion and the outer core inside;
The case has an opening (50) that opens in a direction perpendicular to the coil axial direction (X), and has a partition (51) that separates the outer core and the coil,
The filled resin has a resin surface (61) formed on the opening side,
The outer peripheral core has a corner (311) at a first end (31) that is the end near the resin surface, and at least a part of the corner at the first end is covered with an elastic body (7),
The outer surface (511) of the partition wall has a contact outer surface (512) that contacts the inner peripheral surface (32) of the outer core, an inner recessed surface (513) recessed inwardly on a side closer to the opening than the contact outer surface, and an inner stepped portion (514) formed between the contact outer surface and the inner recessed surface, and the first end is positioned closer to the opening than the inner stepped portion,
An ignition coil (1) for an internal combustion engine, wherein the elastic body is formed over the inner corner portion and the inner step portion of the first end portion. 2. The ignition coil for an internal combustion engine according to claim 1, wherein said elastic body covers at least part of said corner portion on the outer peripheral side of said first end portion. 3. The ignition coil for an internal combustion engine according to claim 1, wherein the elastic body covers at least a portion of the corner portion of the first end located on at least one side in the coil axial direction with respect to the coil portion when viewed from the normal direction of the resin surface. The case is provided with a flange portion (57) projecting to one side in the coil axial direction, and at least a portion of the corner portion of the first end portion located between the coil portion and the flange portion in the coil axial direction is covered with the elastic body. The ignition coil for an internal combustion engine according to any one of claims 1 to 3. 5. The ignition coil for an internal combustion engine according to claim 1, wherein said elastic body covers said corner of said first end over the entire circumference of said outer core. The inner surface (521) of the side wall (52) of the case, which is erected toward the opening, has an inner contact surface (522) that contacts the outer peripheral surface (33) of the outer core, an outer recessed surface (523) recessed outward on a side closer to the opening than the contact inner surface, and an outer stepped portion (524) formed between the contact inner surface and the outer recessed surface, and the first end is located closer to the opening than the outer stepped portion. cage,
The ignition coil for an internal combustion engine according to any one of claims 1 to 5, wherein the elastic body is formed over the corner portion on the outer peripheral side of the first end portion and the outer stepped portion.

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