JP2007214210A - Ignition coil and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil whose radiation property is improved and output performance is improved, and to provide a manufacturing method of the ignition coil. <P>SOLUTION: In the ignition coil 1, concentrically wound primary coil 21 and secondary coil 22 are stored in a coil case 4 formed of thermoplastics. In the ignition coil 1, a center core 23 formed of a magnetic material is inserted into the inner peripheral side of the primary coil 21 and the secondary coil 22. An outer peripheral core 3 formed of a magnetic material is arranged on the outer peripheral side of the coil case 4. A gap in the coil case 4 is filled with thermoplastics 11. A heat radiation material 5 which constitutes the coil case 4 and is softer than thermoplastics is arranged between the coil case 4 and the outer peripheral core 3. The heat radiation material 5 is formed of rubber or thermoplastics. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition coil used for generating a spark from a spark plug in an internal combustion engine and a method for manufacturing the same.

The ignition coil used for an internal combustion engine such as an engine is assembled with a primary coil and a secondary coil formed by winding an electric wire, and a central core made of a magnetic material disposed on the inner peripheral side of the primary coil and the secondary coil. The gap generated in the ignition coil is filled with a thermosetting resin such as an epoxy resin.
Moreover, as an ignition coil device that has improved output efficiency, safety, and durability, for example, there is one disclosed in Patent Document 1. In the ignition coil device of Patent Document 1, an assembly formed by inserting a rod-shaped core on the inner peripheral side of a primary coil and a secondary coil is arranged in a case, and a mold resin is injected into the case to integrally It is molded into. Further, the case is formed of a metal material having high magnetic permeability, an elastic member is provided inside the case, and a mold resin is interposed between the elastic member and the assembly. In Patent Document 1, the case is used as an outer peripheral core that forms a magnetic path together with a rod-shaped core.

By the way, in a conventional ignition coil, a primary coil, a secondary coil, a central core, and the like are arranged in a coil case made of a thermoplastic resin, and an outer circumference core made of a magnetic material is arranged on the outer circumference of the coil case. It has been broken. The coil case is filled with a thermosetting resin such as an epoxy resin to facilitate the filling of the thermosetting resin.
However, in the said patent document 1, when the outer periphery core which consists of magnetic bodies is arrange | positioned in the outer periphery of the coil case which consists of thermoplastic resins, the device for improving the heat dissipation of an ignition coil is not performed.

Japanese Patent Laid-Open No. 9-186031

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an ignition coil capable of improving heat dissipation and improving output performance, and a method for manufacturing the same.

According to a first aspect of the present invention, a primary coil and a secondary coil wound concentrically are accommodated in a coil case made of a thermoplastic resin, and a magnetic material is provided on the inner peripheral side of the primary coil and the secondary coil. In the ignition coil formed by inserting an outer core made of a magnetic material on the outer peripheral side of the coil case,
The gap in the coil case is filled with a thermosetting resin,
Between the coil case and the outer peripheral core, a heat dissipation material softer than the thermoplastic resin constituting the coil case is provided, and the heat dissipation material is made of rubber or a thermosetting resin. It exists in an ignition coil (Claim 1).

The ignition coil according to the present invention is an ignition coil in which an outer peripheral core made of a magnetic material is arranged on the outer peripheral side of a coil case that houses a primary coil and a secondary coil. ing.
Specifically, in the ignition coil of the present invention, a heat dissipating material made of the rubber or thermosetting resin is provided between the coil case and the outer core. For this reason, it is possible to effectively prevent a minute gap in which air or the like enters between the coil case and the outer core by the heat radiating material, and to effectively bring the coil case and the outer core into close contact with each other. be able to. Thereby, heat transfer between the coil case and the outer peripheral core can be promoted, and heat dissipation from the outer peripheral surface of the outer peripheral core constituting the outermost peripheral surface of the ignition coil can be improved.

And by improving the heat dissipation of the ignition coil, the temperature of the ignition coil can be made difficult to reach its use limit temperature. Thereby, the input amount of electric power to the ignition coil (primary coil) can be increased, and the output performance of the ignition coil can be improved.
Therefore, according to the ignition coil of the present invention, the heat dissipation can be improved and the output performance can be improved.

According to a second aspect of the present invention, a primary coil and a secondary coil wound concentrically are accommodated in a coil case made of a thermoplastic resin, and a magnetic material is provided on the inner peripheral side of the primary coil and the secondary coil. In a method of manufacturing an ignition coil, in which an outer core made of a magnetic material is disposed on the outer peripheral side of the coil case through a central core made of
An ignition coil manufacturing method is characterized in that after the liquid rubber or liquid thermosetting resin is applied to the outer peripheral surface of the coil case, the outer peripheral core is disposed.

In the method for manufacturing an ignition coil according to the present invention, a device for arranging the outer peripheral core on the outer peripheral surface of the coil case is devised.
That is, in the present invention, when manufacturing the ignition coil, when the outer peripheral core is disposed on the outer peripheral surface of the coil case, liquid rubber or liquid thermosetting resin is applied in advance to the outer peripheral surface of the coil case. . And an outer periphery core is arrange | positioned on the outer peripheral surface of the coil case which apply | coated liquid rubber or liquid thermosetting resin.

Thus, when the liquid rubber or the liquid thermosetting resin is cured, the minute gap between the coil case and the outer core can be easily filled with the rubber or the thermosetting resin as the heat dissipation material.
Therefore, according to the ignition coil manufacturing method of the present invention, it is possible to easily manufacture an ignition coil that can improve heat dissipation and improve output performance.

According to a third aspect of the present invention, a primary coil and a secondary coil wound concentrically are accommodated in a coil case made of a thermoplastic resin, and a magnetic material is provided on the inner peripheral side of the primary coil and the secondary coil. In a method of manufacturing an ignition coil, in which an outer core made of a magnetic material is disposed on the outer peripheral side of the coil case through a central core made of
A method for producing an ignition coil, wherein a sheet-like rubber or a sheet-like thermosetting resin is arranged in advance on the inner circumferential surface of the outer circumferential core, and the outer circumferential core is assembled to the outer circumferential surface of the coil case. (Claim 6).

Also in the ignition coil manufacturing method of the present invention, a device for arranging the outer peripheral core on the outer peripheral surface of the coil case is devised.
That is, in the present invention, when manufacturing the ignition coil, a sheet-like rubber or a sheet-like thermosetting resin is arranged in advance on the inner peripheral surface of the outer peripheral core. And the outer periphery core which has arrange | positioned sheet-like rubber or sheet-like thermosetting resin is arrange | positioned on the outer peripheral surface of a coil case.

Thereby, the minute gap between the coil case and the outer peripheral core can be easily filled with the rubber or the thermosetting resin as the heat dissipation material.
Therefore, the ignition coil manufacturing method of the present invention can easily manufacture an ignition coil that can improve heat dissipation and output performance.

A preferred embodiment of the first to third inventions described above will be described.
In the first to third inventions, various rubbers (elastomers) softer than the thermoplastic resin constituting the coil case can be used as the rubber constituting the heat dissipation material. As this rubber, for example, silicon-based, fluorine-based or acrylic-based rubber can be used.
Moreover, as a thermosetting resin which comprises the said heat radiating material, an epoxy resin or a phenol resin can be used.

In the first invention, the outer core is preferably formed by laminating a plurality of electromagnetic steel plates, and the heat dissipation material is preferably provided between the electromagnetic steel plates.
In this case, not only the heat dissipation material is provided between the coil case and the outer core, but also between the electromagnetic steel plates, thereby further improving the heat dissipation of the ignition coil and improving the output performance of the ignition coil. This can be further improved.

Moreover, it is preferable that the said heat radiating material solidifies liquid rubber or liquid thermosetting resin (Claim 3).
In this case, it is easy to dispose a heat dissipation material between the coil case and the outer core.
Moreover, liquid rubber or liquid thermosetting resin can have a use as what is called an adhesive agent.

Moreover, the said heat radiating material can also be made into a sheet-like rubber or a sheet-like thermosetting resin (Claim 4).
Also in this case, it is easy to dispose the heat dissipation material between the coil case and the outer core.

Embodiments of the ignition coil and the manufacturing method thereof according to the present invention will be described below with reference to the drawings.
As shown in FIGS. 1 and 2, the ignition coil 1 of this example includes a primary coil 21 and a secondary coil 22 wound concentrically in a coil case 4 made of a thermoplastic resin. Further, the ignition coil 1 has a central core 23 made of a magnetic material inserted on the inner peripheral side of the primary coil 21 and the secondary coil 22, and an outer peripheral core 3 made of a magnetic material on the outer peripheral side of the coil case 4. Arranged.

The gap in the coil case 4 is filled with a thermosetting resin 11. The thermosetting resin 11 is obtained by filling the ignition coil 1 and then filling the gap (space) formed after the assembly with a liquid thermosetting resin and curing it.
Further, between the coil case 4 and the outer peripheral core 3, a heat radiating material 5 softer than the thermoplastic resin constituting the coil case 4 is provided. The heat dissipating material 5 is made of rubber or thermosetting resin.

Hereinafter, the ignition coil 1 of this example and the manufacturing method thereof will be described in detail with reference to FIGS.
As shown in FIG. 1, the ignition coil 1 of the present example has a plug mounting portion 62 for mounting a spark plug on one axial side D1 thereof, and the primary coil 21 on the other axial side D2 thereof. And a connector head 61 for supplying electric power. The ignition coil 1 of the present example has the plug mounting portion 62, the primary coil 21 and the secondary coil 22 inserted into the plug hole of the engine, and the connector head 61 is fixed around the plug hole. The stick type used.

The connector head 61 of this example includes a connector portion 612 that is electrically connected to an engine control unit (ECU) or the like to a head case 611 made of thermoplastic resin, and the ignition coil 1 is connected to an engine cylinder. A flange portion 613 for fixing to the head is formed to protrude. In the head case 611, an igniter including a power supply circuit or the like can be disposed.
The central core 23 of this example is formed by laminating flat electromagnetic steel plates 231 (silicon steel plates or the like) in the radial direction of the ignition coil 1 and having a substantially circular cross section. As shown in FIG. 2, the outer peripheral core 3 of this example is formed by laminating electromagnetic steel plates 31 (silicon steel plates or the like) formed in a cylindrical shape along the shape of the outer peripheral surface of the coil case 4.

  As shown in FIGS. 1 and 2, the primary coil 21 of this example is formed by winding a primary wire with insulation coating on the outer peripheral surface of a primary spool 211 made of a thermoplastic resin having a circular cross section. The secondary coil 22 of this example has more secondary wires coated with an insulating coating having a smaller diameter than the primary wires on the outer peripheral surface of the secondary spool 221 made of a thermoplastic resin formed in an annular cross section. It is wound by the number of windings. The secondary coil 22 of this example is inserted through the inner peripheral side of the primary coil 21.

As shown in FIG. 1, the plug attachment portion 62 of this example is configured by attaching a rubber plug cap 63 to an attachment base portion 212 extended from the axial one end side D <b> 1 of the primary spool 211. A high voltage terminal 64 is disposed on one axial end D1 of the secondary spool 221, and a coil spring 65 for contacting the terminal portion of the spark plug is attached to the high voltage terminal 64. The winding end portion on the high voltage side of the secondary coil 22 is electrically connected to the terminal portion of the spark plug via the high voltage terminal 64 and the coil spring 65.
The spark plug is attached to the cylinder head of the engine with the lever portion engaged with the hollow hole formed in the plug cap 63 and the terminal portion formed at the tip of the lever portion in contact with the coil spring 65.

The coil case 4 of this example is a sheet of thermoplastic resin having an annular cross section, with one end engaged with the mounting base portion 212 of the primary spool 211 and the other end engaged with the connector head 61. Yes.
A gap in the coil case 4, that is, a gap between the central core 23 and the secondary coil 22, a gap between the secondary coil 22 and the primary coil 21, and a gap between the primary coil 21 and the coil case 4. The gap and the gap in the connector head 61 are continuously filled with the thermosetting resin 11 made of epoxy resin or the like.

As shown in FIG. 2, the outer peripheral core 3 of this example is formed by laminating a plurality of electromagnetic steel plates 31. Each electromagnetic steel sheet 31 is formed by rounding a flat plate material into a cylindrical shape, and is arranged along the axial direction D of the ignition coil 1 between the end portions of the material in a cylindrically formed state. A slit is formed as a cutout portion.
The heat dissipating material 5 is provided not only between the coil case 4 and the electromagnetic steel plate 31 for the outer peripheral core 3 located on the innermost peripheral side, but also between the electromagnetic steel plates 31 for the outer peripheral core 3. It is. The outer peripheral core 3 of this example is formed by laminating three electromagnetic steel plates 31, and the heat radiating material 5 is also provided between the electromagnetic steel plates 31.
As shown in FIG. 3, when the outer peripheral core 3 is formed from one electromagnetic steel plate 31, the heat dissipation material 5 can be provided only between the coil case 4 and the electromagnetic steel plate 31.

  In the ignition coil 1, when a current flows instantaneously through the primary coil 21 due to a pulsed spark generation signal from the ECU, a magnetic field passing through the central core 23 and the outer core 3 is formed. Thereafter, an induction magnetic field passing through the central core 23 and the outer core 3 is formed in a direction opposite to the magnetic field formation direction. Then, due to the formation of the induction magnetic field, high voltage induced electromotive force (back electromotive force) is generated in the secondary coil 22, and spark can be generated from the spark plug attached to the plug attachment portion 62 in the ignition coil 1. .

The heat dissipating material 5 of this example is formed by curing a liquid epoxy resin as a thermosetting resin.
In manufacturing the ignition coil 1 of this example, when the outer peripheral core 3 is disposed on the outer peripheral surface of the coil case 4, a liquid epoxy resin is applied to the outer peripheral surface of the coil case 4 in advance. And the outer periphery core 3 is arrange | positioned on the outer peripheral surface of the coil case 4 which apply | coated the liquid epoxy resin. As a result, when the liquid epoxy resin is cured, the minute gap between the coil case 4 and the outer core 3 can be easily filled with the epoxy resin as the heat dissipating material 5. Therefore, the ignition coil 1 can be manufactured easily.

In addition, as the heat dissipation material 5, instead of using a liquid epoxy resin or the like, a sheet-like rubber or a sheet-like thermosetting resin can also be used. In this case, the sheet-like heat dissipation material 5 can be used by being attached to the outer peripheral surface of the coil case 4. Further, the sheet-like heat dissipation material 5 can be used by being attached to the inner peripheral surface of the outer peripheral core 3.
Further, when the sheet-like heat radiating material 5 is provided on the outer peripheral core 3, the heat radiating material 5 can be provided by being laminated on a flat electromagnetic steel plate as a material for forming the outer peripheral core 3. And the magnetic steel sheet formed by laminating the heat dissipating material 5 can be bent into a cylindrical shape to form the outer peripheral core 3, and the outer peripheral core 3 can be disposed on the outer peripheral surface of the coil case 4.

  As described above, in the ignition coil 1 of this example, the heat dissipating material 5 made of the epoxy resin is provided between the coil case 4 and the outer peripheral core 3. Therefore, it is possible to effectively prevent the heat dissipation material 5 from forming a minute gap into which air or the like enters between the coil case 4 and the outer core 3. It can be effectively adhered. Thereby, heat transfer between the coil case 4 and the outer peripheral core 3 can be promoted, and heat dissipation from the outer peripheral surface of the outer peripheral core 3 constituting the outermost peripheral surface of the ignition coil 1 can be improved.

  Further, the heat dissipating material 5 made of a thermosetting resin (or rubber) is made of a material softer than the thermoplastic resin constituting the coil case 4 (the above-mentioned thermosetting resin (or rubber)). It is possible to flexibly follow minute irregularities on the surface of the coil case 4 or the outer core 3. Therefore, separation between the coil case 4 and the heat dissipating material 5 or between the heat dissipating material 5 and the outer core 3 is unlikely to occur, and the heat dissipating property of the ignition coil 1 can be improved.

And by improving the heat dissipation of the ignition coil 1, the temperature of the ignition coil 1 can be made difficult to reach its use limit temperature. Thereby, the amount of electric power supplied to the ignition coil 1 (primary coil 21) can be increased, and the output performance of the ignition coil 1 can be improved.
Therefore, according to the ignition coil 1 of this example, the heat dissipation can be improved and the output performance can be improved.

(Confirmation of output performance)
In this example, it was confirmed that the output performance of the ignition coil 1 (invention product) in which the heat dissipating material 5 is provided between the coil case 4 and the outer core 3 can be improved.
FIG. 4 shows the rise in the temperature of the ignition coil 1 when the rotational speed of the engine is increased by taking the rotational speed (rpm) of the engine on the horizontal axis and the temperature (° C.) of the ignition coil 1 on the vertical axis. It is a graph. In the figure, in the conventional ignition coil (comparative product) in which the heat dissipating material 5 is not provided between the coil case 4 and the outer core 3, the temperature of the ignition coil 1 rises to around 160 ° C. In the ignition coil 1 (invention product) provided with the heat dissipating material 5 of this example, it can be seen that the temperature rises only to around 145 ° C.
From this, it was confirmed that the temperature increase of the ignition coil 1 can be reduced by the ignition coil 1 provided with the heat dissipating material 5.

  FIG. 5 shows the change in the spark voltage with respect to the engine speed, with the horizontal axis representing the engine speed (rpm) and the vertical axis representing the spark voltage (V) generated in the spark plug by the secondary coil 22. It is a graph which shows the degree of. In the figure, for the comparative product, the spark voltage decreases when the engine speed increases, whereas for the invention product, the spark voltage does not decrease even if the engine speed increases. I understand. This is because in the comparative product, when the engine speed increases, the temperature of the ignition coil 1 rises, and it is necessary to limit the amount of power supplied to the ignition coil 1. From this, it was confirmed that the output performance of the ignition coil 1 can be improved by the ignition coil 1 provided with the heat dissipating material 5.

  Ideally, the heat dissipating material 5 is preferably provided on the entire portion where the coil case 4 and the outer core 3 face each other. On the other hand, in the manufacture of the ignition coil 1, it is not easy to provide the heat dissipating material 5 in the entire portion where the coil case 4 and the outer core 3 face each other. Therefore, the ratio of the surface area A2 of the portion where the heat radiating material 5 is provided to the surface area A1 of the entire portion where the outer peripheral surface of the coil case 4 and the inner peripheral surface of the outer peripheral core 3 face each other is the contact surface area A2 / A1 (%). Represent as

  Further, it is known that the degree of temperature rise of the ignition coil 1 is lower as the contact surface area is closer to 100%. The degree of temperature rise of the ignition coil 1 is determined by the temperature rise rate (T1- T0) / (T2−T0) × 100 (%). Here, T0 indicates the ambient temperature at which the ignition coil 1 is used (see T0 in FIG. 4), and T1 indicates a specific engine speed of the ignition coil 1 (invention product) provided with the heat dissipating material 5. Is the estimated temperature (see T1 in FIG. 4), and T2 is the estimated temperature (see T2 in FIG. 4) for a specific engine speed for the ignition coil 1 (comparative product) not provided with the heat dissipating material 5. Show. As an example, if T0 = 130 ° C., T1 = 145 ° C., and T2 = 160 ° C., the temperature increase rate is 50%.

In FIG. 6, the horizontal axis indicates the contact surface area A2 / A1 (%), and the vertical axis indicates the temperature increase rate (T1-T0) / (T2-T0) × 100 (%) of the ignition coil 1. It is a graph which shows the relationship between the temperature rise rate of the ignition coil 1, and. In the figure, when the contact surface area A2 / A1 is 100%, that is, when the heat dissipating material 5 is provided in the entire portion where the coil case 4 and the outer core 3 face each other, the temperature increase rate of the ignition coil 1 is about It is confirmed that 30% can be achieved. When the contact surface area A2 / A1 is 0%, that is, when the heat dissipating material 5 is not provided at the portion where the coil case 4 and the outer core 3 face each other, the temperature increase rate of the ignition coil 1 is 100%. .
And since the change of the temperature rise rate of the ignition coil 1 is small in the range where the contact surface area is 70 to 100%, the temperature rise of the ignition coil 1 can be effectively suppressed by making the contact surface area 70% or more. all right.

Cross-sectional explanatory drawing which shows the ignition coil in an Example. Cross-sectional explanatory drawing which expands and shows a part of ignition coil in an Example. Cross-sectional explanatory drawing which expands and shows a part of other ignition coil in an Example. The graph which shows the relationship between the rotational speed of an engine and the temperature of an ignition coil in an Example. The graph which shows the relationship between the rotational speed of an engine and a spark voltage in an Example. The graph which shows the relationship between the contact surface area and the temperature rise rate of an ignition coil in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 11 Thermosetting resin 21 Primary coil 22 Secondary coil 23 Central core 3 Outer core 31 Magnetic steel sheet 4 Coil case 5 Heat dissipation material

Claims (6)

A primary coil and a secondary coil wound concentrically are accommodated in a coil case made of a thermoplastic resin, and a central core made of a magnetic material is inserted into the inner peripheral side of the primary coil and the secondary coil. In the ignition coil formed by arranging an outer peripheral core made of a magnetic material on the outer peripheral side of the coil case,
The gap in the coil case is filled with a thermosetting resin,
Between the coil case and the outer peripheral core, a heat dissipation material softer than the thermoplastic resin constituting the coil case is provided, and the heat dissipation material is made of rubber or a thermosetting resin. Ignition coil. In Claim 1, the said outer periphery core laminates | stacks a some electromagnetic steel plate,
The ignition coil, wherein the heat dissipating material is also provided between the electromagnetic steel sheets.   3. The ignition coil according to claim 1, wherein the heat dissipating material is obtained by solidifying liquid rubber or liquid thermosetting resin.   3. The ignition coil according to claim 1, wherein the heat dissipating material is a sheet-like rubber or a sheet-like thermosetting resin. A primary coil and a secondary coil wound concentrically are accommodated in a coil case made of a thermoplastic resin, and a central core made of a magnetic material is inserted into the inner peripheral side of the primary coil and the secondary coil. In the method of manufacturing an ignition coil in which an outer peripheral core made of a magnetic material is disposed on the outer peripheral side of the coil case,
A method for producing an ignition coil, comprising: applying a liquid rubber or a liquid thermosetting resin to an outer peripheral surface of the coil case, and then disposing the outer peripheral core. A primary coil and a secondary coil wound concentrically are accommodated in a coil case made of a thermoplastic resin, and a central core made of a magnetic material is inserted into the inner peripheral side of the primary coil and the secondary coil. In the method of manufacturing an ignition coil in which an outer peripheral core made of a magnetic material is disposed on the outer peripheral side of the coil case,
A method for producing an ignition coil, wherein a sheet-like rubber or a sheet-like thermosetting resin is arranged in advance on the inner circumferential surface of the outer circumferential core, and the outer circumferential core is assembled to the outer circumferential surface of the coil case. .

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