JP2008277460A - Ignition coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil capable of obtaining a high secondary voltage which is generated simultaneously via two secondary coils by the change of a magnetic flux generated by interrupting energization to one primary coil. <P>SOLUTION: The ignition coil 1 includes: the primary coil 21; the secondary coils 22; and a closed magnetic path core 4. The secondary coils 22 include: a first secondary coil 22A wound around a secondary spool 221 in one direction; and a second secondary coil 22B wound around the secondary spool 221 in the reverse direction. The whole length H2 of the secondary coils 22 is longer than the axial direction length H1 of the primary coil 21 in the ignition coil 1. The primary coil 21 is not projected outward in the axial direction D of the two secondary coils 22 but is superimposed on both the first and second secondary coils 22A, 22B from the inner peripheral side. The axial direction length H1 of the primary coil 21 and the whole length H2 of the secondary coils 22 has relation to be expressed by 57≤H1/H2×100(%)≤86. <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). For example, as disclosed in Patent Document 1, in an ignition coil having one primary coil and one secondary coil, the winding width of the primary coil and the secondary coil are considered in consideration of energy efficiency for generating a spark. The winding width of the next coil is made substantially the same.
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, when two secondary coils coupled in series with one primary coil are used to simultaneously generate sparks at two locations, the axial length (winding width) of the primary coil and the two secondary coils If the relationship with the axial length (coil width, total length of the secondary coil) combined with the coil is not appropriate, the secondary voltage may be lowered. Specifically, in this case, when the magnetic path forming cores arranged on the inner and outer peripheral sides of the primary coil and the secondary coil are formed long in accordance with the entire length of the secondary coil, the magnetic path forming core There is a concern that the secondary resistance will decrease due to an increase in the magnetic resistance. When the axial length of the primary coil is adjusted to the total length of the secondary coil, the axial length of the primary coil is increased, the capacity is increased, and a synergistic effect with the increase of the magnetic resistance is caused. The secondary voltage may be reduced.

JP 2004-304199 A JP 2001-12337 A

  The present invention has been made in view of such a conventional problem, and a secondary voltage that is simultaneously generated in two secondary coils is obtained by a change in magnetic flux that is generated when energization of one primary coil is interrupted. It is intended to provide an ignition coil that can.

The present invention uses the primary coil and the secondary coil that have the same axial center and are overlapped on the inner and outer circumferences, and uses the inner circumference side, the outer circumference side, and both axial sides of the primary coil and the secondary coil to produce the primary coil. In an ignition coil having a closed magnetic circuit core for passing a magnetic flux generated by energizing the coil,
The closed magnetic path core includes a core central portion disposed on the inner peripheral side of the primary coil and the secondary coil, 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, It has a ring shape with a pair of core relay portions that relay the core outer peripheral portion and the core center portion at both axial ends of the primary coil and the secondary coil,
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 total length H2 of the secondary coil from one axial end of the first secondary coil to the other axial end of the second secondary coil is longer than the axial length H1 of the primary coil. The primary coil does not protrude outward in the axial direction from one axial end of the first secondary coil or the other axial end of the second secondary coil, and the first secondary coil and the first coil Overlaps both the second secondary coil from the inner or outer peripheral side,
The axial length H1 of the primary coil and the overall length H2 of the secondary coil are in an ignition coil characterized by having a relationship of 57 ≦ H1 / H2 × 100 (%) ≦ 86 ( Claim 1).

In the present invention, the secondary voltage is increased in the ignition coil that simultaneously generates the secondary voltage for generating sparks in the two secondary coils due to the change in magnetic flux generated when the energization of one primary coil is cut off. We are doing something for that.
Specifically, the ignition coil of the present invention has the above-mentioned ring-shaped closed magnetic circuit core and the above-mentioned two secondary coils wound in the opposite directions. Further, the overall length H2 of the secondary coil is longer than the axial length H1 of the primary coil, and the primary coil does not protrude outward in the axial direction of the two secondary coils. It overlaps with both the secondary coils from the inner peripheral side or the outer peripheral side. The axial length H1 of the primary coil is 57 to 86 (%) with respect to the entire secondary coil length H2.

Thereby, in the ignition coil of the present invention, the axial length H1 of the primary coil is appropriate with respect to the entire length H2 of the secondary coil, and the secondary voltage generated in the two secondary coils can be obtained high. Can do.
Therefore, according to the ignition coil of the present invention, it is possible to obtain a high secondary voltage that is simultaneously generated in the two secondary coils due to a change in magnetic flux generated when the energization of one primary coil is cut off.

A preferred embodiment of the present invention described above will be described.
In the present invention, when the axial length H1 of the primary coil relative to the total length H2 of the secondary coil is less than 57 (%) and exceeds 86 (%), the secondary obtained in the two secondary coils There is a risk that the voltage will drop.

In addition, the axial central portion of the primary coil may be located on the inner peripheral side or the outer peripheral side of the axial intermediate portion between the first secondary coil and the second secondary coil. Preferred (claim 2).
In this case, it is possible to obtain a high secondary voltage almost equally in the two secondary coils.

Further, when the inductance of the primary coil is L1, and the inductance of the primary coil when the first secondary coil and the second secondary coil are short-circuited is L1 ′, C = L1 ′ / L1 The coil leakage coefficient C represented by x100 (%) can be 31.7-35.7 (%) (Claim 3).
In this case, the primary coil and the two secondary coils are appropriately designed, and a high secondary voltage can be obtained in the two secondary coils.
In addition, when the said coil leakage coefficient C is less than 31.7 (%) and exceeds 35.7 (%), there exists a possibility that the secondary voltage obtained in two secondary coils may fall. .

Moreover, the cross-sectional area of the core central part in the closed magnetic path core is 270 to 290 (mm ² ), the number of turns of the primary coil is 150 to 170 (times), and the total length of the secondary coil H2 Is 45 to 95 (mm), and the number of turns of the first secondary coil and the second secondary coil is 12000 to 20000 (times), respectively, and the first secondary coil and the second secondary coil The outer diameter of the secondary coil 2 is preferably 20 to 23 (mm).
In this case, the primary coil and the two secondary coils are appropriately designed, and a high secondary voltage can be obtained in the two secondary coils.

The ignition coil is of a two-point ignition system configured to ignite at two locations in the engine cylinder, and the first secondary coil is a first plug hole provided in the engine cylinder. The second secondary coil is electrically connected to a second spark plug attached to a second plug hole provided in the cylinder of the engine. The primary coil, the secondary coil, and the closed magnetic circuit core are housed in a resin coil case to constitute a coil portion, and the first axial end side of the coil portion includes the first coil. A first plug mounting portion for mounting the spark plug is formed, and a conductive cable electrically connected to the second secondary coil is drawn out from the other axial end side of the coil portion, The distal end of the conductive cable, it is preferred that the second plug mount for mounting the second spark plug is provided (claim 5).
In this case, in the two-point ignition type ignition coil, a stable spark can be generated by the high secondary voltage obtained at two locations in the engine cylinder.

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.

Hereinafter, embodiments of the ignition coil according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, the ignition coil 1 of this example includes a primary coil 21 and a secondary coil 22 that have the same axis and are overlapped on the inner and outer circumferences, and the inner circumferences of the primary coil 21 and the secondary coil 22. The closed magnetic circuit core 4 for passing the magnetic flux generated by energizing the primary coil 21 using the side, the outer peripheral side, and the axial both ends D1 and D2 is provided.
The closed magnetic path core 4 includes a core central portion 41 disposed on the inner peripheral side of the primary coil 21 and the secondary coil 22, and a core outer periphery disposed on a part of the circumferential direction on the outer peripheral side of the primary coil 21 and the secondary coil 22. It has an annular shape by a portion 42 and a pair of core relay portions 43 that relay the core outer peripheral portion 42 and the core center portion 41 at both axial end sides D1 and D2 of the primary coil 21 and the secondary coil 22.

The secondary coil 22 has an insulating coated secondary wire from the axial one end D1 to the axial other end D2 at the outer peripheral portion of the axial one end D1 of the secondary spool 221 made of resin having an annular cross section. In the outer periphery of the first secondary coil 22A that is wound around one direction toward the other end D2 in the axial direction of the secondary spool 221, the secondary electric wire continuous from the first secondary coil 22A is axially The second secondary coil 22B is wound from the one end side D1 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.

  In the ignition coil 1, as shown in FIG. 1, the total length H2 of the secondary coil 22 from one end in the axial direction D of the first secondary coil 22A to the other end in the axial direction D of the second secondary coil 22B. Is longer than the axial length H1 of the primary coil 21. Further, the primary coil 21 does not protrude outward in the axial direction D from one end in the axial direction D of the first secondary coil 22A or the other end in the axial direction D of the second secondary coil 22B. Both the secondary coil 22A and the second secondary coil 22B overlap from the inner peripheral side. The axial length H1 of the primary coil 21 and the overall length H2 of the secondary coil 22 have a relationship of 57 ≦ H1 / H2 × 100 (%) ≦ 86.

The ignition coil 1 of this example will be described in detail below 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.

  The primary coil 21 in this example is formed by winding an insulating-coated primary electric wire around the outer periphery of a primary spool 211 made of a resin having an annular cross section. In the ignition coil 1 of this example, the two secondary coils 22A and 22B arranged in the axial direction D are arranged as described above, and the first secondary coil 22A is electrically connected to the first spark plug 8A. The second secondary coil 22B is configured to be electrically connected to the second spark plug 8B.

  As shown in FIGS. 1 and 2, the ignition coil 1 of this example includes a primary coil 21, a secondary coil 22, and a closed magnetic circuit core 4 in a resin coil case 3 to form a coil portion 11. A first plug mounting portion 12A for mounting the lever portion 81 of the first spark plug 8A is formed on one end D1 in the axial direction of the coil portion 11. The first plug mounting portion 12A includes a resin tower portion 5A connected to the coil portion 11, a conductive fitting 7A electrically connected to a high-voltage side winding end of the first secondary coil 22A, and a first A rubber plug cap 61A into which the lever portion 81 of the spark plug 8A is press-fitted, and a coil spring 62 for electrically connecting the conductive fitting 7A and the terminal portion 82 formed on the distal end side of the lever portion 81 are provided.

  Further, as shown in FIG. 4, 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 of this example. A second plug mounting portion 12B for mounting the second spark plug 8B is provided at the distal end portion of the conduction cable 34. The second plug mounting portion 12B is a terminal formed on the distal end side of the lever portion 81 by electrically connecting the rubber plug cap 61B into which the lever portion 81 of the second spark plug 8B is press-fitted and the conduction cable 34. It has a conducting metal fitting 7B that conducts to the part 82.

As shown in FIG. 2, the cylinder head 91 is provided with a cylinder head cover 92, and the ignition coil 1 is fixed to the cylinder head cover 92 by a flange portion 31 that protrudes radially outward from the coil case 3. It is configured to do.
When the ignition coil 1 is attached to the engine, the first plug attachment portion 12A is attached to the insulator portion 81 of the first spark plug 8A in the first plug hole 911A. Moreover, the coil part 11 is arrange | positioned outside the plug hole 911A.

  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, the secondary coil 22 is a slanted winding performed by stacking a plurality of inclined winding layers of the secondary electric wire wound toward the high voltage side so that the winding diameter is reduced toward the high voltage side. You can also.

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 FIGS. 4 and 5, when the ignition coil 1 of the present example cuts off the current flowing to the primary coil 21, the winding end on the axial one end side D <b> 1 of the first secondary coil 22 </ b> A is negative. A 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 axial direction of the second secondary coil 22B. The winding end of the other end 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. It is.

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 closed magnetic circuit core 4 of this example has a quadrangular ring shape, and connects the two core members 4A and 4B from the axially opposite ends D1 and D2 of the primary coil 21 and the secondary coil 22. Is formed. 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 4, a cable lead-out portion 32 for pulling out the conducting 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.
Further, as shown in FIGS. 1 to 3, a primary coil 21, a secondary coil 22, a closed magnetic circuit core 4, etc. are arranged in the gap formed in the coil portion 11, that is, the coil case 3, and the coil case 3 and the tower 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 closed magnetic circuit 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, a secondary voltage is generated in the ignition coil 1 that simultaneously generates secondary voltages for generating sparks in the two secondary coils 22 due to a change in magnetic flux generated when the energization of one primary coil 21 is interrupted. I am trying to get high.
Specifically, the ignition coil 1 of the present example includes the square ring-shaped closed magnetic circuit core 4 and the two secondary coils 22 wound in opposite directions. The overall length H2 of the secondary coil 22 is longer than the axial length H1 of the primary coil 21, and the primary coil 21 extends outward in the axial direction D of the two secondary coils 22. The two secondary coils 22 are overlapped from the inner peripheral side without protruding. The axial length H1 of the primary coil 21 is 57 to 86 (%) with respect to the overall length H2 of the secondary coil 22.

Thereby, in the ignition coil 1 of this example, the axial length H1 of the primary coil 21 is appropriate with respect to the entire length H2 of the secondary coil 22, and the secondary generated in the two secondary coils 22 is appropriate. High voltage can be obtained.
Therefore, according to the ignition coil 1 of this example, the secondary voltage generated simultaneously in the two secondary coils 22 can be obtained high due to the change in magnetic flux generated when the energization of one primary coil 21 is cut off. it can.

(Confirmation test)
In this confirmation test, the performance (magnitude of secondary voltage) of the ignition coil 1 described above was confirmed.
Specifically, the secondary voltage when the axial length H1 of the primary coil 21 with respect to the total length H2 (100 (%)) of the secondary coil 22 is changed within a range of 100 (%) or less. The value was measured.
The design dimensions and the like of each part in the ignition coil 1 were as follows. That is, the cross-sectional area of the core central portion 41 in the closed magnetic path core 4 is 280 (mm ² ), the number of turns of the primary coil 21 is 165 (turns), and the total length H2 of the secondary coil 22 is 91 (mm). ). The number of turns of the first secondary coil 22A and the second secondary coil 22B is 16000 (times), respectively, and the outer diameter of the first secondary coil 22A and the second secondary coil 22B is 21 ( mm).

The result of measuring the secondary voltage is shown in FIG. In the figure, H1 / H2 × 100 (%) is taken on the horizontal axis, and the secondary voltage (kV) is taken on the vertical axis, showing a change in the value of the secondary voltage.
As shown in the figure, when H1 / H2 × 100 (%) is in a range close to 100 (%) and when H1 / H2 × 100 (%) is less than 57 (%), the secondary voltage is 35. It was found that the secondary voltage exceeded 35 (kV) when H1 / H2 × 100 (%) was within the range of 57 to 86 (%), whereas it was (kV) or less. From this, it was found that a high secondary voltage can be obtained by setting H1 / H2 × 100 (%) within a range of 57 to 86 (%).
In addition, since the magnitude | size of the secondary voltage in 22 A of 1st secondary coils and the 2nd secondary coil 22B became substantially the same, secondary voltage was made into the average value of both.

The coil leakage coefficient C in the primary coil 21 when H1 / H2 × 100 (%) is 86 (%) is 31.7 (%), and H1 / H2 × 100 (%) is 57 (%). The coil leakage coefficient C in the primary coil 21 when set to 35.7 (%). Thereby, in order to obtain a high secondary voltage in the two secondary coils 22, it is preferable to determine the coil leakage coefficient C in the primary coil 21 within a range of 31.7 to 35.7 (%). I understood.
The coil leakage coefficient C is set such that the inductance of the primary coil 21 is L1, and the inductance of the primary coil 21 when the first secondary coil 22A and the second secondary coil 22B are short-circuited is L1 ′. C = L1 ′ / L1 × 100 (%).

In order to obtain a high secondary voltage in the two secondary coils 22, the cross-sectional area of the core central portion 41 in the closed magnetic circuit core 4 is 270 to 290 (mm ² ), and the number of turns of the primary coil 21 is 150. It was found that the total length H2 of the secondary coil 22 was preferably 45 to 95 (mm). For this purpose, the number of turns of the first secondary coil 22A and the second secondary coil 22B is 12000 to 20000 (times), respectively, and the first secondary coil 22A and the second secondary coil 22B. It was found that the outer diameter of is preferably 20 to 23 (mm).

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. The graph which shows the change of the value of a secondary voltage (kV) by taking H1 / H2x100 (%) on a horizontal axis and taking a secondary voltage on a vertical axis | shaft in a confirmation test.

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 Closed magnetic path 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 911A First 1 plug hole 911B second plug hole 93 cylinder D axial direction D1 axial one end side D2 axial other end side

Claims (6)

The primary coil is energized to the primary coil and the secondary coil having the same axial center and stacked on the inner and outer circumferences, and the inner and outer sides of the primary coil and the secondary coil, and the both ends in the axial direction. In an ignition coil having a closed magnetic path core for passing magnetic flux generated by
The closed magnetic path core includes a core central portion disposed on the inner peripheral side of the primary coil and the secondary coil, 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, It has a ring shape with a pair of core relay portions that relay the core outer peripheral portion and the core center portion at both axial ends of the primary coil and the secondary coil,
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 total length H2 of the secondary coil from one axial end of the first secondary coil to the other axial end of the second secondary coil is longer than the axial length H1 of the primary coil. The primary coil does not protrude outward in the axial direction from one axial end of the first secondary coil or the other axial end of the second secondary coil, and the first secondary coil and the first coil Overlaps both the second secondary coil from the inner or outer peripheral side,
The ignition coil characterized in that the axial length H1 of the primary coil and the overall length H2 of the secondary coil have a relationship of 57 ≦ H1 / H2 × 100 (%) ≦ 86.   2. The central portion of the primary coil in the axial direction according to claim 1 is located on an inner peripheral side or an outer peripheral side of an intermediate portion in the axial direction between the first secondary coil and the second secondary coil. An ignition coil characterized by having   In claim 1 or 2, when the inductance of the primary coil is L1, and the inductance of the primary coil when the first secondary coil and the second secondary coil are short-circuited is L1 ', C A coil leakage coefficient C expressed by = L1 ′ / L1 × 100 (%) is 31.7 to 35.7 (%). In any 1 item | term of Claims 1-3, the cross-sectional area of the said core center part in the said closed magnetic circuit core is 270-290 (mm < ² >), The winding | turns number of the said primary coil is 150-170 (times). Yes, the secondary coil overall length H2 is 45 to 95 (mm), and the number of turns of the first secondary coil and the second secondary coil is 12000 to 20000 (times), respectively. The ignition coil characterized in that outer diameters of the first secondary coil and the second secondary coil are 20 to 23 (mm). In any one of Claims 1-4, the said ignition coil is a thing of the 2 point ignition system comprised so that ignition might be performed in two places in the cylinder of an engine,
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 closed magnetic circuit core are housed in a resin coil case to constitute a coil portion,
A first plug mounting portion for mounting the first spark plug is formed on one end side in the axial direction of the coil portion,
A conducting cable electrically connected to the second secondary coil is drawn out from the other axial end of the coil part, and a second spark plug is attached to the tip of the conducting cable. An ignition coil having two plug mounting portions.   In Claim 5, when the current flowing through the primary coil is interrupted, the winding end on one end side in the axial direction of the first secondary coil has 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.

Images