JP2007214415A - Ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To delay the deterioration of an insulating resin by efficiently transferring the heat of a primary coil to a metal core and discharging it from an insulating case, and thereby to provide a longer life ignition coil for internal combustion engine. <P>SOLUTION: The ignition coil for internal combustion engine 11 comprises the insulating case 21 that contains at least a primary coil 26, a secondary coil 28, and a metal core 29 for coupling the primary coil 26 and secondary coil 28 on a closed path having an air gap 29c. A thermosetting resin 32 is filled into the insulating case 21 to insulate between the coils 26 and 28, between the coil 26 and the metal core 29, and between the coil 28 and the metal core 29, and to the fix the coils 26, 28 and the metal core 29 in the insulating case 21. Moreover, an aluminum board 30 coated with an insulator is inserted into the air gap 29c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition coil for an internal combustion engine that supplies a high voltage for generating spark discharge to an ignition plug of an internal combustion engine such as an automobile engine.

  FIG. 6 is a cross-sectional view showing a schematic configuration of an example of a conventional ignition coil for an internal combustion engine, and FIG. 7 is a plan view of the coil / iron core assembly shown in FIG.

In these drawings, an ignition coil 11 for an internal combustion engine includes an insulating case 21 and a plurality of low-voltage terminals (primary terminals) provided in a socket portion (not shown) provided integrally with a side surface portion of the insulating case 21. ), A high-voltage terminal (secondary terminal) 23 press-fitted into a high-voltage tower portion 21 t provided integrally with the lower end portion of the insulating case 21, and a coil / iron core assembly housed in the insulating case 21. The three-dimensional body 24 and a thermosetting resin 32 as an insulating resin that fills the insulating case 21 and performs high-voltage insulation between the components are configured.
The plurality of low-voltage terminals are inserted, for example, when the insulating case 21 is molded.

The coil / iron core assembly 24 includes a primary coil bobbin 25, a primary coil 26 formed by winding a winding around the outer periphery of the primary coil bobbin 25, and a secondary coil disposed on the outer periphery of the primary coil 26. A coil bobbin 27, a secondary coil 28 formed by winding and winding the outer periphery of the secondary coil bobbin 27, and the primary coil 26 and the secondary coil 28 are magnetically connected by a closed magnetic circuit having an air gap 29c. It is comprised with the iron core 29 to couple | bond.
The iron core 29 is disposed outside the secondary coil 28 so that the center iron core 29a passing through the primary coil bobbin 25 (primary coil 26) and the center iron core 29a are disposed inside and form a closed magnetic circuit together with the center iron core 29a. It is comprised by the cyclic | annular side iron core 29b arrange | positioned.
An air gap 29c set at a predetermined interval is provided between one end of the center iron core 29a and the side iron core 29b.
A plurality of low voltage terminals, both ends of the primary coil 26, and one end of the secondary coil 28 are connected to form a predetermined circuit, and the other end of the secondary coil 28 is attached to the end of the secondary coil bobbin 27. It is connected to the high voltage terminal 23 via a terminal pin (not shown).

  The internal combustion engine ignition coil 11 energizes the primary coil 26 based on a signal supplied from an engine control unit (ECU), and interrupts the energization of the primary coil 26, thereby generating magnetic flux in the iron core 29. As a result, a high voltage is generated in the secondary coil 28 and the high voltage is supplied to the high-voltage terminal 23 (see, for example, Patent Document 1).

When this magnetic flux change occurs in the iron core 29, an eddy current that causes a loss is generated in a direction that prevents the magnetic flux change.
Therefore, in order to suppress the generation of eddy currents that cause losses in the iron core 29, the iron core 29 is configured by laminating silicon steel plates of a predetermined shape (see, for example, Patent Document 1) or coated with an insulator. An iron core 29 is configured by laminating silicon steel plates having a predetermined shape (for example, see Patent Document 2).

JP 2004-169619 A JP 2005-236263 A

The heat generated in the primary coil 26 by the operation of the internal combustion engine ignition coil 11 is released from the insulating case 21 through the thermosetting resin 32, the iron core 29, and the like.
However, when the heat of the primary coil 26 is released from the insulating case 21 through the iron core 29, the air gap 29c provided in the iron core 29 becomes a large heat conduction resistance, so that the heat of the primary coil 26 is efficiently obtained. It cannot be conducted to the iron core 29 and released from the insulating case 21.
As described above, when the heat of the primary coil 26 is efficiently conducted to the iron core 29 and cannot be discharged from the insulating case 21, the temperature of the thermosetting resin 32 becomes high, so that the thermosetting resin 32 is deteriorated. The life of the ignition coil 11 for the internal combustion engine is shortened.

  This invention has been made to eliminate the above-mentioned disadvantages, and improves the life by delaying the deterioration of the insulating resin by efficiently conducting the heat of the primary coil to the iron core and releasing it from the insulating case. An ignition coil for an internal combustion engine that can be made to provide is provided.

The present invention is as follows.
(1) At least a primary coil, a secondary coil, and an iron core that magnetically couples the primary coil and the secondary coil with a closed magnetic circuit having an air gap are housed in an insulation case, In the internal combustion engine ignition coil in which the insulating resin is filled to insulate the coils, the coils and the iron core are insulated, and the coils and the iron core are fixed in the insulation case. A non-magnetic metal plate coated with an insulator is inserted.
(2) The ignition coil for an internal combustion engine according to (1), wherein a slit is provided in the nonmagnetic metal plate.

According to this invention, since the nonmagnetic metal plate coated with an insulator is inserted into the air gap, the heat conduction resistance of the air gap is reduced, so that the heat of the primary coil is efficiently conducted to the iron core for insulation. Can be released from the case.
In this way, the heat of the primary coil can be efficiently conducted to the iron core and released from the insulating case, so that the temperature rise of the insulating resin can be kept low, so that the deterioration of the insulating resin is delayed, and the ignition coil for the internal combustion engine The lifetime of
And since the non-magnetic metal plate is coated with an insulator, even if the end surface of the silicon steel plate laminated to form the iron core is not coated with the insulator, a one-turn current flows between the laminated silicon steel plates. Short circuit can be prevented.
Furthermore, since the slits are provided in the nonmagnetic metal plate, generation of eddy currents in the nonmagnetic metal plate itself can be suppressed, and loss can be reduced.

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

  1 is a sectional view showing a schematic configuration of an internal combustion engine ignition coil according to an embodiment of the present invention, FIG. 2 is a plan view of the coil / iron core assembly shown in FIG. 1, and FIG. 3 is a coil shown in FIG. -It is explanatory drawing which shows an example of the aluminum plate which comprises an iron core assembly, attaches | subjects the same code | symbol to the same or equivalent part as FIG. 6 or FIG. 7, and abbreviate | omits the description.

This embodiment is different from the conventional example in that an aluminum plate 30 as a nonmagnetic metal plate coated with an insulator is inserted into the air gap 29c of the iron core 29.
And in order to suppress generation | occurrence | production of an eddy current, the aluminum plate 30 is provided with one slit 30a extending from one side of a pair of opposing sides of the rectangle to the other side.
As the insulator coated on the aluminum plate 30, for example, fluorine, polyimide, or aluminum oxide having heat resistance of 130 ° C. or higher can be used.
And since the thickness of the insulator to coat should just ensure insulation, it should just be 3 micrometers-50 micrometers, for example.

Since the aluminum plate 30 coated with an insulator is inserted into the air gap 29c of the iron core 29 as in this embodiment, the heat conduction resistance of the air gap 29c is reduced, so that the heat of the primary coil 26 is efficiently obtained. It can be well conducted to the iron core 29 and discharged from the insulating case 21.
As described above, the heat of the primary coil 26 can be efficiently conducted to the iron core 29 and released from the insulating case 21, so that the temperature rise of the thermosetting resin 32 is low, for example, lower by several degrees Celsius than the conventional case. As a result, the deterioration of the thermosetting resin 32 is delayed, and the life of the ignition coil 11 for the internal combustion engine is prolonged.
Since the aluminum plate 30 is coated with an insulator, a one-turn short circuit in which a current flows between the laminated silicon steel plates even if the end surfaces of the silicon steel plates laminated to constitute the iron core 29 are not coated with an insulator. Can be prevented.
Furthermore, since the slit 30a is provided in the aluminum plate 30, it is possible to suppress the generation of eddy current in the aluminum plate 30 itself and reduce the loss.
Further, when the aluminum plate 30 is used as the non-magnetic metal plate, an aluminum oxide film that is an insulator is formed on the surface of the aluminum plate 30, so that it is not necessary to coat the insulator on the aluminum plate 30. .

  FIG. 4 is an explanatory view showing another example of an aluminum plate constituting the coil / iron core assembly shown in FIG. 2, and the same reference numerals are given to the same or corresponding parts as FIG.

In FIG. 4, two slits 30 b are provided in an aluminum plate 30 coated with an insulator on the entire surface in order to suppress the generation of eddy currents.
The two slits 30b extend so as not to overlap from one of a pair of opposing sides of the rectangular aluminum plate 30 and overlap each other in a direction orthogonal to the extending direction.

  FIG. 5 is an explanatory view showing still another example of an aluminum plate constituting the coil / iron core assembly shown in FIG. 2, and the same reference numerals are given to the same or corresponding parts as FIG.

In FIG. 5, the aluminum plate 30 coated with an insulator on the entire surface is provided with four slits 30c in order to suppress the generation of eddy currents.
The four slits 30c extend from each corner of the rectangular aluminum plate 30 toward the center.

  As shown in FIG. 4 or 5, even if the aluminum plate 30 is provided with slits 30b and 30c, the same effect as that of the aluminum plate 30 shown in FIG. 3 can be obtained.

In the above-described embodiment, the example in which the slit is provided in the aluminum plate is shown, but the life of the ignition coil for the internal combustion engine can be improved without providing the slit in the aluminum plate.
In addition, although an example in which an insulator is coated on the entire surface of the aluminum plate has been shown, the same effect can be obtained without coating the insulator on the surface of the aluminum plate that faces or does not contact the iron core (center iron core, side iron core). Obtainable.
And although the example which used the nonmagnetic metal plate as the aluminum plate was shown, copper alloy plates, such as copper or brass, a magnesium plate, etc. can also be used.

1 is a cross-sectional view showing a schematic configuration of an ignition coil for an internal combustion engine according to an embodiment of the present invention. It is a top view of the coil and iron core assembly shown in FIG. It is explanatory drawing which shows an example of the aluminum plate which comprises the coil and iron core assembly shown in FIG. It is explanatory drawing which shows the other example of the aluminum plate which comprises the coil and iron core assembly shown in FIG. It is explanatory drawing which shows the further another example of the aluminum plate which comprises the coil and iron core assembly shown in FIG. It is sectional drawing which shows schematic structure of an example of the conventional ignition coil for internal combustion engines. It is a top view of the coil and iron core assembly shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Ignition coil for internal combustion engines 21 Insulating case 21t High voltage tower part 23 High voltage terminal (secondary terminal)
24 Coil and iron core assembly 25 Primary coil bobbin 26 Primary coil 27 Secondary coil bobbin 28 Secondary coil 29 Iron core 29a Center iron core 29b Side iron core 29c Air gap 30 Aluminum plate (non-magnetic metal plate)
30a slit 30b slit 30c slit 32 thermosetting resin (insulating resin)

Claims (2)

At least a primary coil, a secondary coil, and an iron core that magnetically couples the primary coil and the secondary coil with a closed magnetic circuit having an air gap are housed in an insulating case, and an insulating resin is contained in the insulating case. In the internal combustion engine ignition coil in which the coils are insulated from each other and between the coils and the iron core, the coils and the iron core are fixed in the insulation case,
A non-magnetic metal plate coated with an insulator was inserted into the air gap.
An ignition coil for an internal combustion engine. The ignition coil for an internal combustion engine according to claim 1,
A slit was provided in the non-magnetic metal plate,
An ignition coil for an internal combustion engine.

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