JP2008274815A - Ignition coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil of two-point ignition method, in which a distance between two plug holes is set to be small and the two plug holes are formed in appropriate positions. <P>SOLUTION: The ignition coil 1 has a coil part 11, in which a primary coil 21, secondary coils 22A, 22B wound in directions reverse to each other, and a soft magnetic core 4 are housed in a coil case 3. A first plug installation part 12A electrically connecting the first secondary coil 22A to a first spark plug 8A is disposed to one end side D1 in an axial direction of the coil part 11. A conduction cable 34 electrically connected to the second secondary coil 22B is drawn from the other end side D2 in the axial direction of the coil part 11, and a second plug installation part 12B electrically connecting the conduction cable 34 to a second spark plug 8B is disposed to a tip part of the conduction cable 34. The coil part 11 of the ignition coil 1 is vertically disposed to the outside of a first plug hole 911A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ignition coil used for generating a spark between a pair of electrodes in a spark plug in an internal combustion engine such as a vehicle engine.

  An ignition coil used for an internal combustion engine such as an engine for a vehicle is a primary coil that is energized by a command from an ECU (electronic control unit), and a high voltage for sparking due to a change in magnetic flux that is generated when the energization of the primary coil is interrupted And a secondary coil for generating (secondary voltage). Further, when a two-point ignition type engine that performs ignition at two locations in the combustion chamber is adopted, two plug holes are formed for each cylinder in the cylinder head, and ignition coils are respectively mounted in the two plug holes. Things have been done.

Further, for example, in the ignition device for an internal combustion engine disclosed in Patent Document 1, a spark plug is connected to one winding end and the other winding end of the secondary coil to cut off the energization to the primary coil. A change in magnetic flux sometimes occurs to simultaneously generate a spark between a pair of electrodes in the two spark plugs.
Further, for example, in the spark ignition device of Patent Document 2, two secondary windings (secondary coils) are integrated with one primary winding (primary coil), and the voltage applied to the two electrodes is integrated. Switching polarity is disclosed.

  However, the space for mounting the ignition coil in each cylinder of the engine is extremely limited. Therefore, when adopting a two-point ignition type engine, in order to mount two ignition coils for each cylinder, it is necessary to set a large distance between two plug holes provided in the cylinder head. In particular, when the engine has a small piston bore diameter, the distance between the plug holes becomes extremely small, making it difficult to mount two ignition coils for each cylinder.

Japanese Patent Laid-Open No. 11-230017 JP 2001-12337 A

  The present invention has been made in view of such conventional problems. In the engine cylinder, the distance between two plug holes can be set small, and the two plug holes can be formed at appropriate positions. It is an object of the present invention to provide a two-point ignition type ignition coil.

The present invention provides a magnetic flux generated by energizing the primary coil using the primary coil and the secondary coil having the same axial center and stacked on the inner and outer periphery, and the inner peripheral side of the primary coil and the secondary coil. A two-point ignition type ignition coil configured to ignite at two locations in an engine cylinder,
The secondary coil is configured such that a secondary wire formed by insulating coating is disposed on one end side in the axial direction from one end side in the axial direction toward the other end side in the axial direction on the outer peripheral portion on one end side in the axial direction of the secondary spool made of resin having an annular cross section. A first secondary coil wound around and an outer peripheral portion on the other axial end side of the secondary spool, the secondary electric wire continuous from the first secondary coil is pivoted from one axial end side. It consists of a second secondary coil wound in the direction opposite to the one direction toward the other end in the direction,
The first secondary coil is electrically connected to a first spark plug attached to a first plug hole provided in a cylinder of the engine, and the second secondary coil is provided in a cylinder of the engine. Configured to be electrically connected to a second spark plug attached to the second plug hole;
The primary coil, the secondary coil, and the soft magnetic core are housed in a resin coil case to form a coil portion,
A first plug mounting portion for electrically connecting the first secondary coil to the first spark plug is provided on one axial end side of the coil portion.
A conducting cable electrically connected to the second secondary coil is drawn out from the other axial end side of the coil portion, and the conducting cable is connected to the second spark plug at the tip of the conducting cable. A second plug mounting portion for electrical connection is provided;
In the first plug hole, in a state where the first plug mounting portion is mounted on the lever portion of the first spark plug, the coil portion is disposed upright outside the first plug hole. An ignition coil characterized by being configured as described above (claim 1).

In the present invention, when a two-point ignition type ignition coil is configured, a contrivance is made to reduce the distance between two plug holes provided in each cylinder of the engine.
Specifically, the ignition coil of the present invention includes a first secondary coil electrically connected to a first spark plug attached to a first plug hole provided in the engine cylinder, and a first secondary coil provided in the engine cylinder. And a second secondary coil that is electrically connected to a second spark plug attached to the second plug hole and wound in the opposite direction. The coil portion of the ignition coil of the present invention has a first plug mounting portion for electrically connecting the first secondary coil to the first spark plug on one axial end side thereof, and its axial direction. A leading end portion of the conducting cable drawn from the other end side has a second plug mounting portion for electrically connecting the second secondary coil to the second spark plug.

  Then, a first plug mounting portion and a second plug mounting are respectively mounted on a lever portion of the first spark plug attached to the first plug hole and a lever portion of the second spark plug attached to the second plug hole. When the portion is mounted, the coil portion of the ignition coil is disposed upright above the first plug hole, while only the conduction cable is disposed above the second plug hole.

  Therefore, according to the ignition coil of the two-point ignition system of the present invention, the space restriction outside the plug hole becomes extremely small, and the distance between the first plug hole and the second plug hole is set small. be able to. Also, two plug holes can be formed at appropriate positions in the engine cylinder.

A preferred embodiment of the present invention described above will be described.
In the present invention, the coil portion not only stands vertically with respect to the first plug hole outside the first plug hole but also slightly tilts with respect to the first plug hole. It can also be raised in a state.

In addition, when the secondary coil cuts off the current flowing to the primary coil, the winding end on one end side in the axial direction of the first secondary coil becomes a negative potential, and is electrically connected to the winding end. A negative discharge is performed from the center electrode of the first spark plug to the outer electrode at the ground potential, and the winding end on the other axial end side of the second secondary coil becomes a negative potential, It is preferable that a negative discharge be performed from the center electrode of the second spark plug electrically connected to the winding end to the outer electrode at the ground potential.
In this case, negative discharge is performed in the two secondary coils, and stable sparks can be generated at two locations in the cylinder of the engine.

In addition, a cable lead-out portion for drawing out the conductive cable is formed on the outer peripheral surface on the other axial end side of the coil case, and the winding end on the other axial end side of the second secondary coil. Is preferably electrically connected to the conductive cable via a lead fitting provided in the cable lead portion.
In this case, the drawing direction of the conductive cable can be stably maintained by the cable drawing portion.

Moreover, it is preferable to form a cable holding part for holding an intermediate part of the conducting cable drawn from the cable lead part on the outer peripheral surface of the coil case.
In this case, the middle portion of the conducting cable can be held by the cable holding portion, and the drawing direction of the conducting cable can be more stably maintained.

The soft magnetic core includes a core central portion disposed on the inner peripheral side of the primary coil and the secondary coil, and a core outer peripheral portion disposed on a part of the circumferential direction on the outer peripheral side of the primary coil and the secondary coil. Preferably, it has a ring shape with a pair of core relay portions that relay the core outer peripheral portion and the core central portion at both axial ends of the primary coil and the secondary coil.
In this case, a high secondary voltage generated by the two secondary coils can be obtained by using a change in magnetic flux generated in the ring-shaped soft magnetic core when the energization to the primary coil is interrupted. it can.

Hereinafter, embodiments of the ignition coil according to the present invention will be described with reference to the drawings.
As shown in FIG. 4, the ignition coil 1 of the present example uses the primary coil 21 and the secondary coil 22 that have the same axial center and are overlapped on the inner and outer circumferences, and the inner circumference side of the primary coil 21 and the secondary coil 22. And a soft magnetic core 4 for passing a magnetic flux generated by energizing the primary coil 21 and constituting an ignition coil 1 of a two-point ignition system that performs ignition at two locations in the cylinder 93 of the engine. ing.

As shown in FIG. 1 to FIG. 3, the secondary coil 22 is configured such that the secondary wire covered with insulation is disposed on one end side in the axial direction at the outer peripheral portion of the one end side D <b> 1 in the axial direction of the secondary spool 221 made of resin having an annular cross section. A first secondary coil 22A wound around one end from D1 toward the other axial end D2 and an outer peripheral portion of the other axial end D2 of the secondary spool 221 at the first secondary coil 22A Is formed of a second secondary coil 22B formed by winding the secondary electric wire from the one end side D1 in the axial direction toward the other end side D2 in the axial direction in the direction opposite to the one direction.
The winding state of the two secondary coils 22 means a state where the secondary coil 22 is completed. The two secondary coils 22 are wound from either the axial one end side D1 or the axial other end side D2. Times can also be started.

As shown in FIGS. 4 and 5, the first secondary coil 22A is electrically connected to the first spark plug 8A attached to the first plug hole 911A provided in the cylinder 93 of the cylinder head 91 of the engine. The second secondary coil 22B is configured to be electrically connected to a second spark plug 8B attached to a second plug hole 911B provided in the cylinder 93 of the cylinder head 91 of the engine.
The primary coil 21, the secondary coil 22, and the soft magnetic core 4 are accommodated in the resin coil case 3 to constitute the coil portion 11.

A first plug mounting portion 12A for electrically connecting the first secondary coil 22A to the first spark plug 8A is provided at one axial end D1 of the coil portion 11. Further, a conductive cable 34 electrically connected to the second secondary coil 22B is drawn out from the other axial end D2 of the coil portion 11, and the conductive cable 34 is connected to the distal end portion of the conductive cable 34. A second plug mounting portion 12B for electrical connection with the spark plug 8B is provided.
The ignition coil 1 of the present example has the first plug mounting portion 12A mounted on the lever portion 81 of the first spark plug 8A inside the first plug hole 911A. The first plug hole 911A is arranged to stand upright outside.

Hereinafter, the ignition coil 1 of this example will be described in detail with reference to FIGS.
As shown in FIG. 4, the ignition coil 1 of this example is of a two-point ignition type configured to perform ignition at two locations in each cylinder 93 of the engine.
In the cylinder head 91 of the engine to which the ignition coil 1 of this example is attached, a plurality of cylinders 93 are formed, and a first plug for attaching a first spark plug 8A to the upper portion of the combustion chamber 931 in each cylinder 93. A hole 911A and a second plug hole 911B for attaching the second spark plug 8B are formed.

As shown in FIG. 2, the primary coil 21 of this example is formed by winding an insulating-coated primary wire around the outer periphery of a primary spool 211 made of a resin having an annular cross section.
The axial direction D of the coil part 11 (axial direction D of the primary coil 21 and secondary coil 22) and the axial direction D of the first plug mounting part 12A (mounting direction of the first spark plug 8A) are parallel. The coil portion 11 is disposed so as to stand vertically with respect to the first plug hole 911A outside the first plug hole 911A. Further, the cylinder head 91 is provided with a cylinder head cover 92, and the coil portion 11 is fixed to the cylinder head cover 92 by a flange portion 31 that protrudes radially outward from the coil case 3.

  As shown in FIGS. 1 and 2, the first plug mounting portion 12A includes a resin tower portion 5A connected to the coil portion 11, a high-voltage side winding end of the first secondary coil 22A, and an electrical connection. The connected conducting metal 7A, the rubber plug cap 61A into which the insulator part 81 of the first spark plug 8A is press-fitted, and the terminal part 82 formed on the distal end side of the conducting metal 7A and the insulator part 81 are electrically connected. And a coil spring 62. Further, as shown in FIG. 4, the second plug mounting portion 12B includes a rubber plug cap 61B that holds the end portion of the conductive cable 34 and into which the insulator portion 81 of the second spark plug 8B is press-fitted, and a conductive cable. 34 is electrically connected to the terminal part 82 formed on the distal end side of the insulator part 81 and has a conducting metal fitting 7B.

  Moreover, the primary coil 21 of this example is arrange | positioned at the inner peripheral side of the two secondary coils 22, and the center part of the axial direction D of the primary coil 21 is the 1st secondary coil 22A and the 2nd secondary coil. It is located on the inner peripheral side of the intermediate portion in the axial direction D between the coil 22B. The two secondary coils 22 of this example are divided into a plurality of winding regions in the axial direction D by a plurality of flanges projecting radially outward from the outer peripheral surface of the secondary spool 221 to perform divided winding. Formed. On the other hand, as shown in FIG. 7, the two secondary coils 22 are formed by stacking a plurality of inclined winding layers of the secondary electric wire wound so that the winding diameter is reduced toward the high voltage side toward the high voltage side. It can also be an oblique winding. In this case, the outer diameter of the secondary coil 22 can be further reduced.

Further, the primary coil 21 of this example is wound in the same direction as the second secondary coil 22B (one direction from the axial one end D1 to the other axial end D2), The secondary coil 22A is wound in the reverse direction (in the reverse direction from the one axial end D1 toward the other axial end D2).
As shown in FIG. 5, in the ignition coil 1 of this example, when the current supplied to the primary coil 21 is interrupted, the winding end of the first secondary coil 22A on the one axial end side D1 becomes a negative potential. Then, negative discharge is performed from the center electrode 83A of the first spark plug 8A electrically connected to the winding end to the outer electrode 83B at the ground potential, and the other end side in the axial direction of the second secondary coil 22B. The winding end of D2 has a negative potential, and a negative discharge is performed from the center electrode 83A of the second spark plug 8B electrically connected to the winding end to the outer electrode 83B at the ground potential. .

The anode terminal of the diode 18 is connected to an intermediate point P between the first secondary coil 22A and the second secondary coil 22B, and the cathode terminal of the diode 18 is connected to the battery connection side of the primary coil 21. It is connected to the end (positive side end).
As shown in FIG. 6, the cathode terminal of the diode 18 can be connected to the ground.

  As shown in FIG. 1, the soft magnetic core 4 of this example includes a core central portion 41 disposed on the inner peripheral side of the primary coil 21 and the secondary coil 22, and a circumferential direction on the outer peripheral side of the primary coil 21 and the secondary coil 22. Core outer peripheral portion 42 disposed in a part of the core, and a pair of core relay portions 43 that relay the core outer peripheral portion 42 and the core central portion 41 at the axially opposite ends D1 and D2 of the primary coil 21 and the secondary coil 22. A square ring-shaped closed magnetic circuit core 4 is formed. The soft magnetic core 4 is formed by connecting two core members 4A and 4B from the axially opposite ends D1 and D2 of the primary coil 21 and the secondary coil 22. As shown in FIG. 3, the two core members 4 </ b> A and 4 </ b> B are formed by laminating a plurality of electromagnetic steel plates 40 made of a soft magnetic material in a second direction orthogonal to the first direction in which the core central portion 41 and the core outer peripheral portion 42 are arranged. Do it.

  As shown in FIG. 1, a core gap 44 in which a permanent magnet is disposed is formed in one of the two connecting portions 411 and 421 of the two core members 4A and 4B, and the other connecting portion. In 421, a coupling portion 45 in which the end faces of the two core members 4A and 4B are in contact with each other is formed. The core gap 44 of this example is formed in a state of being inclined with respect to the axial direction D of the coil part 11 in the core center part 41, and the coupling part 45 of this example is one of the two core members 4A and 4B. A convex portion 451 formed on one side is fitted to a concave portion 452 formed on the other side.

  As shown in FIG. 2, a connector portion 35 protruding outward in the radial direction is formed on the outer peripheral surface of the other end side D <b> 2 in the axial direction of the coil case 3. The connector portion 35 is provided with a conduction pin that is electrically connected to each winding end of the primary coil 21, and the primary coil 21 is connected to an igniter provided outside the ignition coil 1 by a harness drawn from the connector portion 35. The As shown in FIG. 5, the switching control circuit 19 in the igniter is configured to receive a signal from the ECU (electronic control unit) and to energize the primary coil 21 and cut off the energization.

As shown in FIGS. 1 and 3, a cable lead-out portion 32 for pulling out the conductive cable 34 is formed on the outer peripheral surface of the other end D2 in the axial direction of the coil case 3 so as to protrude radially outward. . The high voltage winding end of the second secondary coil 22B on the other end side D2 in the axial direction is electrically connected to the conductive cable 34 via a lead fitting 321 provided in the cable lead portion 32. In addition, a cable holding portion 33 is formed on the outer peripheral surface of the coil case 3 to hold a middle portion of the conductive cable 34 drawn from the cable lead portion 32.
By holding the conduction cable 34 by the cable drawing portion 32 and the cable holding portion 33, the drawing direction of the conduction cable 34 can be stably maintained.

  Further, as shown in FIGS. 1 to 3, a primary coil 21, a secondary coil 22, a soft magnetic core 4, and the like are arranged in a gap formed in the coil portion 11, that is, the coil case 3, and the coil case 3 and the tower are arranged. A gap formed by being surrounded by the portion 5A or the like is filled with a thermosetting insulating resin (epoxy resin or the like) 15.

In the ignition coil 1 of this example, a spark can be simultaneously generated between the electrodes 83A and 83B of the two spark plugs 8 as follows.
That is, as shown in FIG. 5, when the primary coil 21 is energized by the switching control circuit 19 of the igniter in response to a command from the ECU, a magnetic field passing through the soft magnetic core 4 is formed. Next, when the energization of the primary coil 21 is interrupted, a voltage is generated in the primary coil 21 by the self-induction action, and a high voltage induced electromotive force (secondary voltage) is generated in the two secondary coils 22 by the mutual induction action. Each electrode 83A in the first spark plug 8A generated and electrically connected to the first secondary coil 22A, between the electrodes 83A and B and in the second spark plug 8B electrically connected to the second secondary coil 22B, A spark can be generated between B.

In this example, when the ignition coil 1 of the two-point ignition system is configured, a device is devised that can reduce the distance between the two plug holes 911A, B provided in each cylinder 93 of the engine.
The first plug mounting portion is respectively connected to the insulator portion 81 of the first spark plug 8A attached to the first plug hole 911A and the insulator portion 81 of the second spark plug 8B attached to the second plug hole 911B. When the 12A and the second plug mounting portion 12B are mounted, the coil portion 11 of the ignition coil 1 is disposed upright above the first plug hole 911A, while the coil plug 11 is positioned above the second plug hole 911B. Only the conductive cable 34 is arranged.

Therefore, according to the ignition coil 1 of the two-point ignition method of this example, the space restriction outside the plug holes 911A and B becomes extremely small, and the first plug hole 911A and the second plug hole 911B The distance between them can be set small. Further, the two plug holes 911A, B can be formed at appropriate positions in the cylinder 93 of the engine.
Further, in this example, since the coil portion 11 stands upright outside the plug holes 911A and 911B, in a multi-cylinder 93 engine, the degree of freedom of the arrangement space of the ignition coil 1 between the cylinders 93 is also increased. Can be improved.

  FIG. 8 is a graph schematically showing that the distance between the plug holes 911A and B can be shortened by employing the ignition coil 1 of this example. As shown in the figure, when two ignition coils (comparative products) each having a coil portion are used, for example, when the total width of the two ignition coils is about 40 mm, the distance between the plug holes 911A and 911A Of 40 mm or more. On the other hand, when the ignition coil 1 (invention product) of this example is used, only one coil portion 11 exists on the plug hole 911A. For example, even if the width of the ignition coil is 40 mm, the plug hole It can be seen that the distance between 911A and B can be reduced to nearly 20 mm.

  FIG. 9 is a diagram schematically showing a state in which the ignition coil 1 of this example is mounted on a cylinder 93 in which four valves 94 are arranged. As shown in the figure, the two spark plugs 8A, B are arranged in the space between the intake portion of the two valves 94A and the exhaust portion of the two valves 94B. B are arranged in parallel to the direction in which they are arranged. The coil portion 11 of the ignition coil 1 stands upright above the first spark plug 8A. Thus, the space around the cylinder 93 on which the ignition coil 1 is mounted is limited, and it can be seen that the above-described excellent operational effects can be obtained by the ignition coil 1 of this example.

  Further, according to the ignition coil 1 of this example, in each cylinder 93 of the cylinder head 91, it is not necessary to arrange two ignition coils side by side, so that a sufficient space can be formed around the ignition coil 1. Thereby, the heat dissipation of the ignition coil 1 can be improved, the thermal stress acting on the ignition coil 1 is reduced, and the degree of freedom in strength design against this thermal stress can be increased. Moreover, according to the ignition coil 1 of this example, since it is not necessary to arrange | position two ignition coils side by side, the freedom degree of the layout design of a peripheral component can also be raised.

Cross-sectional explanatory drawing which shows the state in the Example which looked at the ignition coil from one direction. Cross-sectional explanatory drawing which shows the state in the Example which looked at the ignition coil from the direction orthogonal to FIG. Cross-sectional explanatory drawing shown in the state which looked at the ignition coil from the axial direction in an Example. Cross-sectional explanatory drawing which shows the state which mounted the ignition coil in the cylinder of the engine in an Example in the state seen from one direction. Explanatory drawing which shows the circuit structure of the ignition coil in an Example. Explanatory drawing which shows the other circuit structure of an ignition coil in an Example. Sectional explanatory drawing which shows the other secondary coil in an Example. In an Example, the horizontal axis | shaft takes the width | variety of an ignition coil and the vertical axis | shaft takes the distance between plug holes, and shows the relationship typically. Explanatory drawing which shows typically the state which mounts an ignition coil with respect to the cylinder which arrange | positioned four valves in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 11 Coil part 12A 1st plug mounting part 12B 2nd plug mounting part 21 Primary coil 22A 1st secondary coil 22B 2nd secondary coil 221 Secondary spool 3 Coil case 32 Cable extraction part 33 Cable Holding part 34 Conducting cable 4 Soft magnetic core 41 Core center part 42 Core outer peripheral part 43 Core relay part 44 Core gap 45 Coupling part 8A First spark plug 8B Second spark plug 81 Insulator part 82 Terminal part 91 Cylinder head 911 First 1 plug hole 911 2nd plug hole 93 cylinder D axial direction D1 axial one end D2 axial other end

Claims (5)

To pass the magnetic flux generated by energizing the primary coil by using the primary coil and the secondary coil having the same axis and stacked on the inner and outer circumferences, and the inner circumference side of the primary coil and the secondary coil. A two-point ignition type ignition coil configured to ignite at two locations in an engine cylinder,
The secondary coil is configured such that a secondary wire formed by insulating coating is disposed on one end side in the axial direction from one end side in the axial direction toward the other end side in the axial direction on the outer peripheral portion on one end side in the axial direction of the secondary spool made of resin having an annular cross section. A first secondary coil wound around and an outer peripheral portion on the other axial end side of the secondary spool, the secondary electric wire continuous from the first secondary coil is pivoted from one axial end side. It consists of a second secondary coil wound in the direction opposite to the one direction toward the other end in the direction,
The first secondary coil is electrically connected to a first spark plug attached to a first plug hole provided in a cylinder of the engine, and the second secondary coil is provided in a cylinder of the engine. Configured to be electrically connected to a second spark plug attached to the second plug hole;
The primary coil, the secondary coil, and the soft magnetic core are housed in a resin coil case to form a coil portion,
A first plug mounting portion for electrically connecting the first secondary coil to the first spark plug is provided on one axial end side of the coil portion.
A conducting cable electrically connected to the second secondary coil is drawn out from the other axial end side of the coil portion, and the conducting cable is connected to the second spark plug at the tip of the conducting cable. A second plug mounting portion for electrical connection is provided;
In the first plug hole, in a state where the first plug mounting portion is mounted on the lever portion of the first spark plug, the coil portion is disposed upright outside the first plug hole. An ignition coil characterized by being configured as described above.   In Claim 1, when the current flowing through the primary coil is cut off, the winding end on one end side in the axial direction of the first secondary coil becomes a negative potential, and is electrically connected to the end of the winding. A negative discharge is performed from the center electrode of the first spark plug to the outer electrode at the ground potential, and the winding end on the other axial end side of the second secondary coil becomes a negative potential, and the winding An ignition coil comprising: a negative discharge from a center electrode of the second spark plug electrically connected to an end to an outer electrode at a ground potential. In Claim 2, the cable lead-out part for drawing out the above-mentioned conduction cable is formed in the outer peripheral surface of the axial direction other end side in the above-mentioned coil case,
An ignition coil characterized in that the winding end on the other axial end side of the second secondary coil is electrically connected to the conductive cable via a lead fitting provided in the cable lead portion.   4. The ignition coil according to claim 3, wherein a cable holding portion for holding an intermediate portion of the conductive cable drawn from the cable lead portion is formed on the outer peripheral surface of the coil case.   5. The soft magnetic core according to claim 1, wherein the soft magnetic core includes a core central portion disposed on the inner peripheral side of the primary coil and the secondary coil, and a circumferential direction on the outer peripheral side of the primary coil and the secondary coil. A core outer peripheral portion disposed in a part of the core, and a pair of core relay portions that relay the core outer peripheral portion and the core central portion at both axial ends of the primary coil and the secondary coil. An ignition coil characterized by having

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