JP2017059682A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for internal combustion engine capable of suppressing high frequency noise leakage to the outside.SOLUTION: An ignition coil 1 for internal combustion engine has a primary coil 21 and a secondary coil 22 coupled magnetically each other, a center core 3, an outer peripheral core 4, a sealing resin 5, a connector 6, a conductive path 7 and a high frequency noise suppression part 71. The center core 3 is placed on the inside of the primary coil 21 and secondary coil 22. The outer peripheral core 4 are placed on the outside of the primary coil 21 and secondary coil 22. The sealing resin 5 seals the primary coil 21, secondary coil 22, center core 3 and outer peripheral core 4. The connector 6 is connected with an external apparatus. The conductive path 7 electrically connects the outer peripheral core 4 and connector 6. The high frequency noise suppression part 71 is placed in the conductive path 7, and suppresses propagation of high frequency noise from the outer peripheral core 4 to the connector 6.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ignition coil for an internal combustion engine.

  As an ignition coil for an internal combustion engine, a primary coil and a secondary coil that are magnetically coupled to each other, a central core disposed inside the primary coil and the secondary coil, and disposed outside the primary coil and the secondary coil. And an outer peripheral core (Patent Document 1). In the ignition coil, the primary coil, the secondary coil, the center core, and the outer core are sealed in a sealing resin such as an epoxy resin. The ignition coil has a connector portion that is electrically connected to an external device. The connector portion is provided with a ground terminal member that is grounded (grounded) via a wire harness or the like connected to the connector portion.

  And the said ignition coil short-circuits an outer periphery core and the ground terminal member of a connector part. Thus, the outer peripheral core can be grounded to the outside of the ignition coil via the ground terminal member and the wire harness. By grounding the outer peripheral core, the output of the ignition coil and its rising characteristic can be stabilized. That is, by grounding the outer core, the stray capacitance between the outer core and the secondary coil can be stabilized, and performance variations due to stray capacitance variations are suppressed.

JP 2009-299614 A

However, the ignition coil described in Patent Document 1 has the following problems.
That is, due to the difference in linear expansion coefficient between the outer core and the sealing resin, the outer core and the sealing resin may be peeled off, and a gap may be generated between them. If a gap is generated between the outer core and the sealing resin, corona discharge may occur in the gap. When corona discharge occurs, high-frequency noise caused by corona discharge flows out from the outer core to the wire harness or the like by short-circuiting the outer core and the ground terminal member of the connector portion, and flows through the wire harness or the like. There is a possibility that the high frequency noise may become noise of peripheral devices of the ignition coil.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an ignition coil for an internal combustion engine that can suppress the outflow of high-frequency noise to the outside.

One aspect of the present invention includes a primary coil and a secondary coil that are magnetically coupled to each other;
A central core disposed inside the primary coil and the secondary coil;
An outer peripheral core disposed outside the primary coil and the secondary coil;
A sealing resin that seals the primary coil, the secondary coil, the central core, and the outer core;
A connector connected to an external device;
A conductive path for electrically connecting the outer peripheral core and the connector part;
A high-frequency noise suppression unit disposed in the conductive path and suppressing high-frequency noise from propagating from the outer peripheral core to the connector unit;
An ignition coil for an internal combustion engine having

  The ignition coil for an internal combustion engine includes a high-frequency noise suppression unit that is disposed in the conductive path and suppresses high-frequency noise from propagating from the outer core to the connector unit. Therefore, the high-frequency noise suppression unit can suppress high-frequency noise generated in the outer peripheral core from flowing out of the ignition coil through the conductive path.

  As described above, according to the above aspect, it is possible to provide an ignition coil for an internal combustion engine that can suppress outflow of high-frequency noise to the outside.

1 is a cross-sectional view of an ignition coil for an internal combustion engine in Embodiment 1. FIG. FIG. 2 is a top view of an ignition coil for an internal combustion engine in the first embodiment.

(Embodiment 1)
An embodiment relating to an ignition coil for an internal combustion engine will be described with reference to FIGS. 1 and 2.
The ignition coil 1 for an internal combustion engine of the present embodiment includes a primary coil 21 and a secondary coil 22 that are magnetically coupled to each other, a central core 3, an outer peripheral core 4, a sealing resin 5, a connector portion 6, and a conductive path 7. And a high frequency noise suppression unit 71. The central core 3 is disposed inside the primary coil 21 and the secondary coil 22. The outer core 4 is disposed outside the primary coil 21 and the secondary coil 22. The sealing resin 5 seals the primary coil 21, the secondary coil 22, the central core 3, and the outer core 4. The connector unit 6 is connected to an external device. The conductive path 7 electrically connects the outer peripheral core 4 and the connector portion 6. The high frequency noise suppression unit 71 is disposed in the conductive path 7 and suppresses the high frequency noise from propagating from the outer core 4 to the connector unit 6. In the present embodiment, the high frequency noise suppression unit 71 is an inductor. The outer peripheral core 4 is connected to the outside via a conductive path 7 in which a high-frequency noise suppression unit 71 is disposed and a connector unit 6 and is grounded.

  The ignition coil 1 is connected to a spark plug (not shown) installed in an internal combustion engine such as an automobile or a cogeneration system, and is used as means for applying a high voltage to the spark plug.

  As shown in FIG. 1, the primary coil 21 and the secondary coil 22 are concentrically arranged. As shown in FIGS. 1 and 2, the secondary coil 22 is disposed on the outer peripheral side of the primary coil 21, and is wound around a resin bobbin 11. The primary coil 21 is wound around the central core 3. The central core 3 is formed by laminating electromagnetic steel plates in a direction perpendicular to the winding axis direction of the primary coil 21 and the secondary coil 22 and has a substantially rectangular column shape as a whole.

  In the following, the winding axis direction of the primary coil 21 and the secondary coil 22 is simply referred to as the axial direction X, and the lamination direction of the electromagnetic steel sheets is simply referred to as the lamination direction Z.

  As shown in FIG. 2, the annular outer core 4 is arranged so as to surround the outer peripheral sides of the primary coil 21 and the secondary coil 22 from the direction orthogonal to the stacking direction Z. As with the central core 3, the outer peripheral core 4 is also formed by laminating electromagnetic steel sheets in the laminating direction Z.

  As shown in FIGS. 1 and 2, the connector portion 6 is disposed on the opposite side of the outer core 4 from the central core 3 in the axial direction X. The connector portion 6 includes a plate-like portion 601 whose thickness direction is the axial direction X, and a cylindrical protrusion 602 that protrudes from the plate-like portion 601 in one of the axial directions X. The connector part 6 has a plurality of terminal members penetrating the plate-like part 601 in the axial direction X. As shown in FIG. 2, the connector section 6 includes a ground terminal member 61 to be grounded, a signal terminal member 62 for transmitting a switching signal to an igniter 8 described later, and a power terminal member for connecting the external power source and the primary coil 21. 63. For convenience, the protruding side of the protruding portion 602 with respect to the plate-like portion 601 in the axial direction X is defined as the front side, and the opposite side is defined as the rear side.

  The ground terminal member 61 includes a ground terminal 611 protruding rearward from the plate-like portion 601, a front portion extending from the ground terminal 611, an embedded portion 612 embedded in the plate-like portion 601, and a front portion extending from the embedded portion 612. And an external connection terminal 613 projecting forward from the plate-like portion 601. As shown in FIG. 2, the ground terminal 611 is constituted by a first ground terminal 611 a and a second ground terminal 611 b that are bifurcated from the embedded portion 612.

The first ground terminal 611 a is connected to one end of the conductive path 7. The end of the conductive path 7 opposite to the side to which the first ground terminal 611 a is connected is connected to the outer core 4. Thereby, the outer peripheral core 4 is connected to the ground terminal 611 provided in the connector part 6 through the conductive path 7 in which the inductor 71 is arranged. The inductor 71 can be, for example, a ferrite bead inductor in which the periphery of a conducting wire is covered with a core made of ferrite, a coil formed by winding a conducting wire, or the like.
The second ground terminal 611b is connected to an igniter 8 described later.

  The ignition coil 1 has an igniter 8 for energizing the primary coil 21 and interrupting the energization. The igniter 8 is disposed in close contact with the outer core 4. The igniter 8 is disposed between the plate-like portion 601 of the connector portion 6 and the outer core 4 in the axial direction X. The rear surface of the igniter 8 is in close contact with the front surface of the outer core 4. The igniter 8 has a plurality of igniter terminals 81 protruding in the stacking direction Z. The igniter terminal 81 is connected to the power terminal member 63 of the connector section 6, the signal terminal member 62, and the second ground terminal 611 b of the ground terminal member 61.

  Parts constituting the ignition coil 1 such as the primary coil 21, the secondary coil 22, the center core 3, the outer core 4, and the igniter 8 are accommodated in the case 10. The case 10 is made of a resin having electrical insulation. The connector portion 6 is fitted to the case 10 at the plate-like portion 601.

The case 10 is filled with a sealing resin 5 made of an epoxy resin or the like.
FIG. 2 is a top view showing the sealing resin 5 omitted. FIGS. 1 and 2 are simplified diagrams, and there is a configuration in which illustration is omitted, for example, connection between the primary coil 21 and the igniter 8. Further, in FIG. 1, the inductor 71 is intentionally illustrated in order to show that the inductor 71 is connected to the connector portion 6 and the outer core 4.

Next, the effect of this embodiment is demonstrated.
The ignition coil 1 for an internal combustion engine includes a high frequency noise suppression unit 71 that is disposed in the conductive path 7 and suppresses high frequency noise from propagating from the outer core 4 to the connector unit 6. Therefore, the high frequency noise generated in the outer peripheral core 4 can be prevented from flowing out of the ignition coil 1 through the conductive path 7 by the high frequency noise suppression unit 71, and in terms of DC, The core 4 is grounded to the outside.

  Moreover, the high frequency noise suppression part 71 is an inductor. Therefore, it is possible to efficiently suppress the high-frequency noise generated in the outer peripheral core 4 due to corona discharge or the like from flowing out of the ignition coil 1 through the conductive path 7 by the inductor. That is, when high frequency noise is generated in the outer peripheral core 4 while the outer peripheral core 4 is grounded outside the ignition coil 1 in normal times, the high frequency noise from the outer core 4 via the conductive path 7 is caused by the inductance of the inductor 71. Can be prevented from flowing out of the ignition coil 1.

In this embodiment, since the outer core 4 is grounded (grounded), the igniter 8 can be brought into close contact with the outer core 4. That is, in the present embodiment, since the outer core 4 is grounded, it is possible to suppress an increase in potential difference between the outer core 4 and the igniter terminal 81. As a result, even if a crack that connects the outer core 4 and the igniter terminal 81 occurs in the filling resin 5 between the outer core 4 and the igniter terminal 81, the case where the high-frequency noise suppression unit 71 is not provided. Since the potential of the outer core 4 can be lowered, it is possible to prevent corona discharge from occurring between the outer core 4 and the igniter terminal 81.
Therefore, in this embodiment, the igniter 8 is disposed in close contact with the outer core 4. As a result, the ignition coil 1 can be reduced in size and the heat of the igniter 8 can be released to the outer core 4, so that the heat dissipation of the igniter 8 can be improved.

  The outer core 4 is connected to the ground terminal 611 through the conductive path 7 in which the inductor 71 is disposed. Therefore, the outer peripheral core 4 can be connected to an external ground via the grounding terminal 611 of the connector unit 6 and the wire harness connected to the connector unit 6. Since the inductor 71 is disposed in the conductive path 7, high-frequency noise generated in the outer core 4 does not propagate through the wire harness or the like. Therefore, it is possible to suppress the influence of the high-frequency noise generated in the outer peripheral core 4 on the electronic components arranged around the wire harness or the like.

  As described above, according to the present embodiment, an ignition coil for an internal combustion engine that can suppress the outflow of high-frequency noise to the outside can be provided.

In addition, this invention is not limited to the said embodiment, It is possible to apply to various embodiment in the range which does not deviate from the meaning.
For example, in the first embodiment, the high-frequency noise suppression unit is an inductor, but may be a resistor such as a ceramic resistor that does not generate inductance.
In the first embodiment, the conductive path is connected to the ground terminal of the connector unit, but may be connected to the power supply terminal member of the connector unit.

DESCRIPTION OF SYMBOLS 1 Ignition coil for internal combustion engines 21 Primary coil 22 Secondary coil 3 Central core 4 Outer core 5 Sealing resin 6 Connector part 7 Conductive path 71 High frequency noise suppression part

Claims (4)

A primary coil (21) and a secondary coil (22) magnetically coupled to each other;
A central core (3) disposed inside the primary coil (21) and the secondary coil (22);
An outer peripheral core (4) disposed outside the primary coil (21) and the secondary coil (22);
A sealing resin (5) for sealing the primary coil (21), the secondary coil (22), the central core (3), and the outer peripheral core (4);
A connector (6) connected to an external device;
A conductive path (7) for electrically connecting the outer core (4) and the connector (6);
A high-frequency noise suppression unit (71) disposed in the conductive path (7) and configured to suppress high-frequency noise from propagating from the outer peripheral core (4) to the connector unit (6);
An ignition coil (1) for an internal combustion engine having   The ignition coil (1) for an internal combustion engine according to claim 1, wherein the high-frequency noise suppression unit (71) is an inductor.   3. An igniter (8) for energizing and interrupting energization of the primary coil (21), the igniter (8) being disposed in close contact with the outer peripheral core (4). Ignition coil for internal combustion engine (1)   The outer peripheral core (4) is connected to a ground terminal (611) to be grounded provided on the connector part (6) via the conductive path (7) in which the high-frequency noise suppressing part (71) is arranged. The ignition coil (1) for internal combustion engines as described in any one of Claims 1-3.

Images