JP4345583B2 - Stick type ignition coil - Google Patents

Description

  The present invention relates to a stick-type ignition coil for an internal combustion engine, and particularly to an improved head case of a control unit.

  The stick-type ignition coil is configured by housing components at an upper end portion, an intermediate portion, and a lower end portion of a case. For example, the conventional ignition coil shown in FIG. 8 includes a central core, a secondary coil, a primary coil, and an outer peripheral core in order from the center to the radially outer side in a cylindrical body case 101 of the coil unit 100. Are arranged concentrically.

On the other hand, the head case 106 of the control unit 105 shown in FIG. 9 includes a rectangular tube-shaped storage unit 107, a connector unit 108, and the like. An igniter (not shown) is stored in the storage unit 107, and the connector unit 108 is connected to the outside. It is connected. The cylindrical portion 102 at the upper end of the trunk case 101 is fitted into the bottom wall 109 of the accommodating portion 107.
JP-A-9-289120

  The conventional ignition coil has room for improvement in the following points. First, it takes time to inject the epoxy resin into the gaps between the components in the coil unit 100 during assembly. The epoxy resin is supplied from the accommodating portion 107 of the head case 106 to a gap between the spool and the winding in the trunk case 101. Here, since the cross-sectional area of the trunk case 101 is smaller than the cross-sectional area of the accommodating portion 107 of the head case 106, the flow area is large when epoxy resin flows from the accommodating portion 107 into the cylindrical portion 102 of the trunk case 101. It decreases rapidly and becomes difficult to flow in. As a result, the time required for the epoxy resin to spread over the entire body case 101 becomes longer.

  Further, the insulating resin cured in the housing portion 107 after assembly may prevent the heat generated in the body case 101 (particularly the secondary coil and the primary coil) from being dissipated. The heat generated by both coils is dissipated upward while being transmitted to a cylindrical outer core or the like. However, the insulating resin filled in the housing portion 107 covers the entire cross section of the cylindrical portion 102 of the body case 101, and prevents upward heat dissipation.

  Furthermore, after the primary coil and the secondary coil are inserted into the coil unit 100 in the axial direction, there is no portion serving as a reference for positioning, and it takes time to confirm that the positioning has been reliably performed, and the positioning is accurate. It was difficult to do.

  In addition, the head case is large and not only the coil is not easily mounted on the engine, but also it is difficult for the operator to grasp the control unit 105 by hand when inserting or removing the ignition coil from the plug hole. . Further, since the head case 106 having a larger radial dimension than the body case 101 is heavy, the head case 106 is likely to vibrate when the engine is operated.

  The present invention has been made in view of the above circumstances, and can efficiently inject epoxy resin from the upper end of the case into the gaps in the middle and lower end of the case, and the heat dissipation in the body case is upward. It is an object of the present invention to provide a stick-type ignition coil that can be reliably positioned by a primary case and a secondary coil in a body case with little obstruction by the case.

  The inventor of the present application suddenly changes the transverse dimension at the boundary between the head case and the body case, in other words, forms a step portion extending radially inward between the body case and the head case. With this in mind, the present invention has been completed.

The invention according to claim 1 of the present application is directed to a coil portion composed of a primary coil and a secondary coil, a central core disposed inside the coil portion, a battery and the coil above a plug hole of an engine. A connector portion that electrically connects the portion, a case that accommodates the coil portion and the central core, and a cylindrical shape that is disposed outside the coil portion and inside or outside the case. A stick-shaped ignition coil attached to the plug hole, wherein the inner peripheral surface of the case is reduced in diameter radially inward from below in the axial direction of the plug hole. A downward contact surface is provided, and at least a part of the upper end of the coil portion is locked in the axial direction by the downward contact surface.

The invention according to claim 2 is characterized in that the coil portion is locked to the downward contact surface via a holder attached to the upper end of the central core and the coil portion.

According to a third aspect of the present invention, the case is formed with two downward contact surfaces spaced apart in the axial direction, the holder contacts the one downward contact surface, and the other downward contact surface. Is characterized in that the upper end surface of the outer peripheral core is in contact.

The invention described in claim 4 is characterized in that an igniter is disposed inside the case and above the downward contact surface.

The invention according to claim 5 is characterized in that the outer peripheral surface of the holder is in contact with the upper part of the inner peripheral surface of the outer peripheral core.

According to the present invention, the inner peripheral surface of the case is provided with the downward contact surface that is reduced in diameter radially inward from the lower side in the axial direction of the plug hole to at least one of the upper ends of the coil portions. Since the portion is locked in the axial direction by the downward contact surface, the primary coil and the secondary coil are reliably positioned in the axial direction.

<Overall>
The stick type ignition coil of the present invention (hereinafter abbreviated as “ignition coil” if necessary) includes a case and components housed therein. Specifically, the case includes a head case formed of an upper end portion in the axial direction and a trunk case formed of an intermediate portion and a lower end portion. In many cases, components such as a primary coil and a secondary coil are accommodated in the body case (first type), and components such as an igniter are accommodated in the head case.

  However, the outer peripheral core may be attached to the outer peripheral surface of the trunk case (second type), and the igniter may be disposed outside the head case. Further, there are cases where the body case and the head case are separate (a type) and integrated (b type).

<Body case>
Insulating body case corresponding to the middle and lower end of the case, a central core accommodated in the hollow hole, a primary coil and a secondary coil, and an outer peripheral core accommodated in or attached to the hollow hole And a coil part is comprised. Among these, the trunk case is made of an insulating material and has a cylindrical shape as a whole.

  The primary coil is formed by winding a primary winding on an insulating, cylindrical primary spool, and the secondary coil is formed by winding a secondary winding on an insulating, cylindrical secondary spool. In the radial direction of the ignition coil, the secondary coil may be on the inner peripheral side and the primary coil may be on the outer peripheral side, and conversely, the primary coil may be on the inner peripheral side and the secondary coil may be on the outer peripheral side.

  The outer peripheral core has a thin cylindrical shape, is disposed on the outer peripheral side of the primary coil and the secondary coil located on the outer peripheral side, and is attached to the inner peripheral surface or the outer peripheral surface of the trunk case.

<Head case>
A control part is comprised by the insulating head case (upper case) equivalent to the upper end part of a case, the igniter etc. which are arrange | positioned in the inside. However, the igniter may be provided outside the head case. The head case has a step portion extending radially inward at an intermediate portion in the height direction, and the step portion has a downward contact surface. In other words, the outer dimensions in the transverse direction (perpendicular to the axis) are suddenly changed between the stepped portion and the upper accommodating portion and the lower extending portion. The step portion will be described later.

The housing portion is a portion for housing the igniter and has a predetermined shape (cylindrical shape or square tube shape).
The extension is fitted to the outer peripheral surface of the cylindrical portion at the upper end of the trunk case in the a type (becomes a fitting portion), and is integrated with the cylindrical portion at the upper end of the barrel case in the b type (becomes a cylindrical portion). ).

<Dimensional relationship between head case and torso case>
(B) In the first type in which the outer peripheral core is accommodated in the body case, in the transverse direction, the minimum outer dimension of the upper end of the case, that is, the head case, is greater than the maximum outer dimension of the intermediate part and the lower end, that is, the body case (See claim 1). The minimum outer dimension of the head case may be smaller than the outer diameter of the outer core (see claim 2) or smaller than the inner diameter of the outer core (see claim 3).

  The head case has a square tube shape, the body case has a cylindrical shape, and the length of the short side of the head case is smaller than the outer diameter of the primary coil or the secondary coil located on the outer peripheral side. 4 and 5).

  (B) In the second type in which the outer peripheral core is mounted on the outer peripheral surface of the trunk case, the minimum outer dimension of the head case is smaller than the outer diameter of the outer core in the transverse direction (see claim 9). It may be smaller than the inner diameter (see claim 10). The head case has a rectangular tube shape, and the body case has a cylindrical shape (see claim 12).

   In the case of the first type or the second type, for example, when the fitting portion of the head case has a cylindrical shape and the accommodating portion has a rectangular tube shape, as shown in FIG. The minimum outer dimension (including the wall thickness) 1 of the housing part Xa of the head case X is smaller than the maximum outer dimension (the outer diameter including the wall thickness) d of the cylindrical part Ya of the body case Y. For example, in the transverse direction connecting the pair of long wall portions, the length between the outer wall surfaces of the long wall portion is smaller than the outer diameter of the upper end portion of the trunk case, and the length between the inner wall surfaces of the long wall portion is smaller than the inner diameter of the upper end portion. In particular, the length between the inner wall surfaces of the lower end portion of the long wall portion is smaller than the inner diameter of the upper end portion.

<Step part>
(A) In the first type case, a stepped portion extending inward in the radial direction and having a downward contact surface is formed near the upper end, that is, in the intermediate portion in the height direction of the head case (see claim 16). The holder attached to the upper ends of the central core, the primary coil, and the secondary coil is in contact with the downward contact surface of the stepped portion (see claim 17). The outer peripheral core may contact the lower contact surface of the stepped portion or the lower peripheral surface of the holder attached to the upper ends of the central core, the primary coil, and the secondary coil (see claim 18). The radial dimension of the step is greater than the thickness of the outer core (see claim 19), and the step can have a pair of crescent-shaped steps separated in the transverse direction (see claim 20).

(B) Second type The head case of the second type has a stepped portion extending inward in the radial direction and provided with a downward contact surface at the height direction intermediate portion (see claim 24). The holder attached to the upper ends of the central core, the primary coil, and the secondary coil is in contact with the downward contact surface of the stepped portion (see claim 25). The head case is formed with two step portions that are separated in the axial direction, and the holder attached to the upper end of the central core, the primary coil, and the secondary coil is in contact with the downward contact surface of the one step portion. The upper end of the outer peripheral core is in contact with the downward contact surface of the portion (see claim 26), and the radial dimension of the other step portion is larger than the thickness of the outer core (see claim 27).

  In both the first type and the second type, as shown in FIG. 6B, the head case X is inward in the radial direction between the rectangular cylindrical housing part Xa and the fitting part Xc in the bottom view. A pair of extending crescent-shaped steps Xa are formed. In addition, when a accommodating part is circular shape, a step part becomes a ring shape. For example, as shown in FIG. 7 (a), the thickness of the fitting portion Xc and the accommodating portion Xb is constant and the step portion Xa is formed, or as shown in FIG. 7 (b), the thickness of the fitting portion Xc. The step portion Xa is formed by increasing the thickness of the accommodating portion Xb, or, as shown in FIG. 7C, two step portions Xd1 and Xd2 are provided between the fitting portion Xc and the accommodating portion Xb. Can be formed. Note that the downward contact surface can extend in a direction perpendicular to the axis, or can form an acute angle or an obtuse angle with respect to a plane perpendicular to the axis.

<Separate and integrated head case and torso case>
(A) a type In both the first type and the second type, in the a type in which the head case and the body case are separated, the fitting portion extending below the head case is the cylindrical portion at the upper end of the body case. Is fitted (press-fit) to the outer peripheral surface of After the central core, primary coil, secondary coil and outer peripheral core are inserted into the trunk case, the head case is coupled to the trunk case (see claims 6 and 13). The case is composed of a lower case that houses the central core, primary coil, secondary coil, and outer peripheral core, and an upper case that is formed with a stepped portion and joined to the lower case. The upper end is in contact (see claims 22 and 28).

(B) b type In both the first type and the second type, in the b type in which the head case and the trunk case are integrated, the cylindrical portion extending below the head case and the cylindrical portion of the trunk case are integrated. Make it. The trunk case has an opening at the lower end, and the central core, the primary coil, the secondary coil, and the outer core are inserted from the opening at the lower end (see claims 7 and 14).

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

<First embodiment>
(Constitution)
The stick-type ignition coil shown in FIG. 1 includes an axially middle coil section 10, an upper end control section 30 and a lower end high pressure tower section 50.

a. Coil Part In the coil part 10, a central core 11, a secondary coil 13, a primary coil 17, and an outer peripheral core 21 are disposed in order in the trunk case 25 from the center toward the outer peripheral side. The body case 25 is insulative and has a cylindrical shape, and the outer diameter of the upper end portion 27 from the middle portion thereof is substantially uniform. The secondary coil 13 includes an insulating and cylindrical secondary spool 14 and a secondary winding 15 wound around the outer peripheral surface thereof. One end of the secondary winding 15 is connected to a spark plug (not shown). The primary coil 17 includes an insulating and cylindrical primary spool 18 and a primary winding 19 wound around the outer peripheral surface thereof. One end of the primary winding 19 is connected to an igniter 42 described below, and the other end is connected to a battery (not shown) via a connector 46.

  The outer peripheral core 21 is accommodated in the concave portion 26 in the middle portion of the trunk case 25 on the outer peripheral side of the primary winding 19 and faces the central core 11 in the radial direction with the secondary coil 13 and the primary coil 17 interposed therebetween. Yes. An insulating resin 51 is filled in a gap between the central core 11 and the secondary spool 14 or between the secondary winding 15 and the primary spool 18.

b. Control Unit In FIGS. 1 and 2, the head case 31 of the control unit 30 includes a housing part 32, a fitting part 35, a connector part 45, and a fixing part 48. The accommodating part 32 consists of a pair of long wall part 33 and a pair of short wall part 33b, and has a square cylinder shape. As shown in FIGS. 2 and 3, the interval between the long wall portions 33 a is larger than the outer diameter m of the upper end portion 27 of the trunk case 25, but the interval between the short wall portions 33 b is smaller than the outer diameter m. More specifically, the length x between the outer wall surfaces of the long wall portion 33 a is smaller than the outer diameter m of the upper end portion 27, and the length y between the inner wall surfaces is smaller than the inner diameter n of the upper end portion 27.

  The fitting portion 35 has a cylindrical shape and is coupled to the housing portion 32 by a step portion 37. The diameter of the fitting portion 35 is larger than the length x between the outer wall surfaces of the long wall portion 33a of the housing portion 32, and between the outer wall surfaces of the short wall portion 33b. Less than length. Further, the inner diameter of the fitting portion 35 is substantially equal to the outer diameter of the upper end portion 27 of the trunk case 25. As a result, the length or width in one transverse direction (the direction connecting both the long wall portions 33a, the up-down direction in FIG. 2) increases rapidly as it proceeds from the housing portion 32 to the upper end portion 27. As a result, a pair of crescent-shaped step portions 37 is formed between the accommodating portion 32 and the fitting portion 35.

  A holder 40 is disposed on the upper end surfaces of the central core 11, the secondary coil 13 and the primary coil 17. The holder 40 includes a disc-shaped main body portion 41a, a cylindrical portion 41b formed on the lower surface thereof, and an abutting portion 41c formed on the outer peripheral edge of the main body portion 41a. The cylindrical portion 41 b enters a gap between the central core 11 and the secondary spool 14, and the contact portion 41 c is engaged with the primary spool 18 and the downward contact surface 37 a of the stepped portion 37. As a result, the center core 11, the secondary coil 13, and the primary coil 17 are positioned by the holder 40 in the axial direction and the radial direction.

  Here, the upper end of the outer peripheral core 21 is in contact with the downward contact surface 37a of the stepped portion 37, but may be in contact with the lower surface of the outer peripheral edge 41c of the holder 40. That is, the outer peripheral edge 41 c may cover the upper end of the outer core 21 and also serve as positioning of the outer core 21.

  The small rectangular igniter 42 is placed on the upper end surface of the central core 11 via the magnet 43 and the holder 40. A terminal 46 installed on the connector 45 is connected to the igniter 40 and the end of the primary winding 19. The fixing unit 48 fixes the control unit 30 and thus the ignition coil to the cylinder head. The housing portion 32 is filled with an insulating resin 53 around the igniter 42.

c. Assembling When assembling the ignition coil, the coil unit 10 and the control unit 30 are assembled separately and then combined. First, when the coil portion 10 is assembled, a secondary winding 15 is formed by winding the secondary winding 15 around the secondary spool 14 on the inner peripheral side of the primary coil 17 formed by winding the primary winding 19 around the primary spool 18. The coil 13 and the central core 11 are inserted in the axial direction. That is, the primary coil 17, the secondary coil 13, and the central core 11 are inserted in the axial direction from the upper end opening toward the lower end in the body case 25 in which the outer peripheral core 21 is attached to the recess 26.

  When the controller 30 is assembled, the fitting portion 35 of the head case 31 is fitted to the upper end portion 27 of the trunk case 25. The igniter 42 is positioned on the upper surface of the holder 40, and the primary winding 19, the secondary winding 15, the igniter 42 and the terminal 46 are connected. Thereafter, an epoxy resin is injected from the housing portion 32 of the head case 31 toward the body case 25.

  As can be seen, magnetic components such as the central core 11, the outer core 21, the primary coil 17, and the secondary coil 13 are first inserted into the body case 25, and then a one-chip type ultra-small igniter 42 is mounted. The head case 31 is fitted and integrated with each other.

(Function)
The operation of this embodiment is as follows. The magnetic flux generated in the primary winding 19 flows through the central core 11 and the outer core 21, and the central core 11, the secondary coil 13, the primary coil 17, and the outer core 21 constitute a closed magnetic circuit. When the igniter 42 cuts off the current flowing through the primary coil 17 at a predetermined timing, a high voltage is generated in the secondary coil 13. When this high voltage is applied to a spark plug (not shown), a spark discharge is generated.

(effect)
According to this embodiment, the following effects can be obtained. First, the time required for injecting the epoxy resin into the gap between the components in the body case 25 of the coil unit 10 can be shortened. Since the length m between the outer wall surfaces of the long wall portion 33a is larger than the inner diameter y of the upper end portion 27, the cross-sectional area between the accommodating portion 32 and the upper end portion 27, that is, the fitting portion 35 increases rapidly, This is because negative pressure is generated. As a result, the action of drawing in the epoxy resin into the trunk case 25 occurs, and the epoxy resin easily flows into the trunk case 25, so that the time required for filling the entire coil portion 10 can be shortened.

  Second, the insulating resin in the housing portion 32 of the head case 31 is less likely to prevent upward heat dissipation from the central core 11. The plan view shape of the insulating resin is determined by the shape of the housing portion 32, but since the length x between the outer wall surfaces of the long wall portion 33a is smaller than the outer diameter n of the upper end portion 27, the short side of the rectangular insulating resin is short, A pair of crescent shaped steps 37 are formed. As a result, the area (region) of the insulating resin located above the coil portion 10 including the central core 11 is reduced, and the step portion 37 is located to promote upward heat dissipation.

  In this connection, since the outer core 21 has a high heat transfer rate, the heat generated in the primary coil 17 and the like is easily radiated when the upper end thereof is brought closer to the outside air side. If the head case width 31 is narrowed to the upper part of the primary coil 17, the heat dissipation effect is further increased. In addition, since the heat generated inside the primary coil 17 and the like is transmitted through the outer core 21, the heat radiation effect can be improved only by removing the epoxy resin at the upper end of the outer core 21.

  Third, when the head case 31 is fitted, the downward contact surface 37a of the stepped portion 37 abuts on the upper ends of the holder 40, the outer core 21 and the body case 25, so that the positioning of these is ensured. When the stepped portion 37 positions the holder 40, the central core 11, the secondary coil 13, and the primary coil 17 are positioned in the axial direction and the radial direction. Further, the downward contact surface 37 a of the stepped portion 37 is in contact with the upper end surface of the outer peripheral core 21 and the upper end surface of the upper end portion 27 of the trunk case 25 to position them.

  In addition, since the outer dimensions of the accommodating portion 32 of the head case 31 are reduced, it is easy to grasp by hand, and the plug hole can be easily inserted and removed from the plug hole. Further, the weight of the control unit 30 is reduced by the reduction in the outer dimension of the housing unit 32, and vibration (oscillation of the head) is difficult when the engine is operating.

<Second embodiment>
The second embodiment shown in FIG. 4 is different from the first embodiment in the positional relationship between the body case 60 and the outer core 63 of the coil portion 10 and the shape of the stepped portion 67 of the head case 65. ing. Since the other configuration is the same as that of the first embodiment, different configurations will be mainly described below. The body case 60 is disposed on the outer peripheral side of the primary coil 17, and the outer core 63 is disposed in a recess 64 formed on the outer peripheral side.

  A pair of stepped portions 70 formed between the housing portion 66 and the fitting portion 68 of the head case 65 are a first stepped portion 71 having a small diameter in the upper axial direction and a second stepped diameter in the lower axial direction. A step 74 is included. The first step portion 71 has a lower surface 72a extending in a direction orthogonal to the axis, and an upper surface 72b that forms an acute angle or an obtuse angle with respect to the axis, and the outer peripheral edge 41b of the holder 40 and the upper end of the body case 60 on the lower surface 72a. The upper end surface of the part 61 is in contact. The second step portion 74 has a lower surface 75a extending in a direction orthogonal to the axis and an upper surface 75b forming an acute angle or an obtuse angle with the axis, and the upper end surface of the outer core 63 is in contact with the lower surface 75a.

  According to the second embodiment, the outer peripheral core 63 can be mounted on the outer peripheral surface of the body case 61, and flexibility is provided in the location of the outer peripheral core 63. In addition, since the first step portion 71 and the second step portion 72 are formed in the head case 66, separate positioning portions and heat dissipation portions are formed by the primary coil 17, the body case 60, and the outer core 63. Can do. Further, the downward contact surfaces of the first step portion 71 and the second step portion 72 may be formed obliquely as long as the function of holding internal components such as the outer peripheral core 63 and the primary coil 17 is obtained. Absent.

<Third embodiment>
FIG. 5 shows a third embodiment. In the third embodiment, one case 70 includes a body case portion 73 and a head case portion 76. That is, a portion corresponding to the upper end portion 27 of the body case 25 of the first embodiment and a portion corresponding to the fitting portion 35 of the head case 31 are integrated into a cylindrical portion 72. The relationship between the cylindrical portion 72 and the central core 11, the secondary coil 14 and the primary coil 17 of the coil portion 80 and the relationship between the cylindrical portion 72 and the igniter 42 of the control portion 83 are the same as those in the first embodiment.

  A holder 40 is put on the upper ends of the central core 11, the secondary coil 13 and the primary coil 17. A pair of step portions 85 is formed between the cylindrical portion 72 and the housing portion of the head case portion 76, and the contact portion 41 c on the outer peripheral edge of the holder 40 is in contact with the downward contact surface 86 a of the step portion 85. . Further, the upper end portion of the outer peripheral core 21 disposed on the inner peripheral side of the body case portion 73 is in contact with the downward contact surface 86a. The upper end surface of the primary spool 18 is in contact with the contact portion 41c.

  A head case 76 having a smaller cross-sectional area is integrally formed at the upper end of the trunk case 73. Therefore, the holder 40, the central core 11, the secondary coil 13, and the primary coil 17 are inserted from the lower end opening of the body case portion 73 of the case 70 during assembly. At the time of insertion, the holder 40 is positioned by the step portion 85, and the center core 11, the secondary coil 13, and the primary coil 17 are positioned by the holder 40.

  According to the third embodiment, in addition to the effects of the first embodiment, since the single case 80 composed of the trunk case portion 73 and the head case portion 76 is adopted, the trunk case and the head case. As compared with the case where the two are separately molded and fitted, the cost required for molding and assembly can be reduced.

It is a longitudinal cross-sectional view which shows 1st Example of this invention. It is also a plan view. It is a principal part enlarged view of FIG. It is a principal part longitudinal cross-sectional view which shows 2nd Example. It is a principal part longitudinal cross-sectional view which shows 3rd Example. (A) And (b) is explanatory drawing which shows the best form. (A) (b) And (c) is explanatory drawing which shows the best form. It is a perspective view which shows the coil part of the conventional ignition coil. It is a perspective view which similarly shows a control part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Coil part 11: Central core 13: Secondary coil 17: Primary coil 21: Outer core 25: Trunk case 27: Upper end part 30: Control part 31: Head case 32: Storage part 35: Fitting part 37 : Step 40: Holder 42: Igniter

Claims (5)

A coil portion comprising a primary coil and a secondary coil;
A central core disposed inside the coil portion;
Above the plug hole of the engine, there is a connector part that electrically connects the battery and the coil part, and a case that houses the coil part and the central core;
An outer peripheral core disposed outside the coil portion and inside or outside the case and having a cylindrical shape;
In a stick-shaped ignition coil attached to the plug hole,
The inner peripheral surface of the case is provided with a downward contact surface having a diameter reduced radially inward from the lower side in the axial direction of the plug hole, and at least a part of the upper end of the coil portion is An ignition coil that is locked in the axial direction by a downward contact surface . The ignition coil according to claim 1, wherein the coil portion is locked to the downward contact surface via a holder attached to an upper end of the central core and the coil portion . The case is formed with two downward abutting surfaces spaced apart in the axial direction, the holder abuts on one downward abutting surface, and the upper end surface of the outer peripheral core on the other downward abutting surface The ignition coil according to claim 2, which is in contact with each other . The ignition coil according to any one of claims 1 to 3, wherein an igniter is disposed inside the case and above the downward contact surface . The ignition coil according to claim 2 or 4, wherein an outer peripheral surface of the holder is in contact with an upper part of an inner peripheral surface of the outer peripheral core .

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