JP2002270444A - Ignition coil for internal engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure high electric insulation (insulation resistance) at the end in the axial direction of a coil. SOLUTION: A separation layer 142 is provided at a section corresponding to a position (extension section 123) where at least a thin film 122 is not provided out of an inner-periphery surface 141 of an outer-periphery core 140. As a result, although a gap due to the separation is generated at the inner- periphery surface 141 of the outer-periphery core 140, separation is made at the position for relaxing thermal stress, thus preventing cracks from being generated due to thermal stress even if a filled resin material is bonded to an end section in the axial direction of a primary spool 121 at the end section in the axial direction of the primary spool 121 near a lead-out wire, and hence securing high electric insulating properties not only at the end section in the axial direction of coils (120 and 130) where the lead-out wire is provided but also at the entire ignition coil, and at the same time preventing cracks from being generated due to thermal stress in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil for an internal combustion engine (hereinafter, abbreviated as an ignition coil).

[0002]

2. Description of the Related Art In an ignition coil described in Japanese Patent Application Laid-Open No. 11-111545, a primary coil (outer peripheral coil) and a secondary coil (inner peripheral coil) are arranged coaxially on the outer peripheral side of a rod-shaped central core. In order to prevent the occurrence of cracks (cracks) in the components due to the difference in the coefficient of linear expansion between the components constituting the ignition coil such as the cylindrical outer core and the like, the winding frame (spool, A thin film made of PET (polyethylene terephthalate) is arranged on the outer periphery of the bobbin) to prevent the winding frame for the primary coil from completely adhering to the molding resin (casting resin) (for the primary coil) The resin and the casting resin are peeled off).

[0003]

By the way, the high voltage generated in the secondary coil is output to the spark plug side from the lead wire (lead wire) provided at the axial end of the secondary coil. In the coil, a high output voltage (for example, 30
kV), it is necessary to ensure high electrical insulation (insulation resistance) especially around the lead wires.

On the other hand, as described in the above publication, if the casting resin and the components of the ignition coil are separated from each other, the thermal stress generated due to the difference in the coefficient of linear expansion can be reduced. Although generation of cracks (cracks) can be prevented, since the casting resin is separated from the component parts, minute voids are generated in the separated portions.

At this time, since the insulation resistance of the air gap is generally smaller than the insulation resistance of the resin, it is assumed that the casting resin and the components of the ignition coil are provided at the axial end of the secondary coil in which the lead wires are arranged. When a means for peeling off is applied, there is a possibility that electrical insulation (insulation resistance) may be reduced due to the existence of minute voids generated in the peeled off portion. Therefore, conventionally, on the axial end side of the secondary coil on which the lead wire is arranged, means for separating the casting resin and the components of the ignition coil have not been provided.

For this reason, at the axial end side of the coil, a decrease in insulation resistance due to the separation of the casting resin from the components of the ignition coil could be prevented, but it was caused by a difference in linear expansion coefficient. Since the thermal stress cannot be reduced, cracks (cracks) occur in the components (particularly, the winding frame), and the cracks may cause a decrease in insulation resistance.

[0007] In view of the above, it is an object of the present invention to secure high electrical insulation (insulation resistance) on the axial end side of a coil.

[0008]

According to the present invention, in order to achieve the above object, according to the first aspect of the present invention, a rod-shaped center core (110) made of a magnetic material and a center core (11) are provided.
0), which is disposed between the center core (110) and the inner peripheral coil (130), and is wound between the inner core coil (130) and the inner peripheral coil (130). An inner winding frame (131) made of an electrically insulating material for winding, and an outer winding (1) wound around the outer circumference of the inner winding (130).
20), the inner circumferential side coil (130) and the outer circumferential side coil (1).
20) and an outer winding frame (1) made of an electrically insulating material for winding the winding of the outer coil (120).
21) and a cylindrical outer core (140) made of a magnetic material and arranged on the outer circumferential side of the outer core (120). The outer core (140) is filled with a resin material having electrical insulation. An ignition coil for an internal combustion engine in which both coils (120, 130) are molded and fixed, and an outer peripheral core (140)
Of the inner peripheral surface (141) of at least the portion corresponding to the axial end of the outer peripheral winding frame (121) is prevented from adhering the outer core (140) to the resin material (175). It is characterized in that an adhesion suppressing layer (142) is provided.

As a result, the thermal stress generated due to the difference in the coefficient of linear expansion of the components constituting the ignition coil for the internal combustion engine is relieved, and cracks (cracks) occur in the components (particularly, the outer winding frame (121)). Can be prevented.

At this time, voids are generated on the inner peripheral surface (141) of the outer peripheral core (140) due to peeling.
Since the thermal stress is relieved by peeling at this portion, the filled resin material and the outer peripheral winding frame (12) are located at the axial end of the outer peripheral winding frame (121) near the lead wire.
No cracks occur due to thermal stress even if they are brought into close contact (adhesion) with the axial end portion of 1).

Therefore, according to the present invention, high electrical insulation (insulation resistance) is ensured on the axial end side of the coil (120, 130) provided with the lead wire.
Cracks can be prevented from occurring due to thermal stress.

According to the second aspect of the present invention, the rod-shaped central core (110) made of a magnetic material and the central core (110) are provided.
Is disposed between the center core (110) and the inner peripheral coil (130) and wound around the inner peripheral coil (130). And an outer coil (12) wound around the outer periphery of the inner coil (130).
0), the inner circumferential coil (130) and the outer circumferential coil (12).
0) and an outer winding frame (12) made of an electrically insulating material for winding the winding of the outer coil (120).
1) and a cylindrical outer core (140) disposed on the outer side of the outer core (120) and made of a magnetic material. The outer core (140) is filled with a resin material having electrical insulation. An ignition coil for an internal combustion engine in which both coils (120, 130) are molded and fixed, and an outer peripheral coil (12
0) and an outer peripheral side winding frame (121), a first adhesion suppressing layer (122) for preventing the outer peripheral side winding frame (121) from adhering to the resin material (175) is provided, Further, at least a portion of the inner peripheral surface (141) of the outer core (140) corresponding to a portion where the first adhesion suppressing layer (122) is not provided, the outer core (140) is formed of the resin material (175). And a second adhesion suppressing layer (142) for suppressing the adhesion of the second adhesion suppressing layer.

As a result, thermal stress generated due to a difference in linear expansion coefficient between components constituting the ignition coil for the internal combustion engine is relieved, and cracks (cracks) are generated in the components (particularly, the outer winding frame (121)). Can be prevented.

At this time, voids are generated on the inner peripheral surface (141) of the outer core (140) due to the separation.
Since the thermal stress is relieved by peeling at this portion, the filled resin material and the outer peripheral winding frame (12) are located at the axial end of the outer peripheral winding frame (121) near the lead wire.
No cracks occur due to thermal stress even if they are brought into close contact (adhesion) with the axial end portion of 1).

Therefore, according to the present invention, high electrical insulation (insulation resistance) is secured not only on the axial end side of the coil (120, 130) provided with the lead wire but also on the entire ignition coil. Cracks can be prevented from occurring due to thermal stress.

The number of turns of the inner peripheral coil (130) is the same as that of the third embodiment.
The number of turns may be larger than the number of turns in 20), and the inner circumferential side coil may be a secondary coil.

According to a fourth aspect of the present invention, there is provided the method of manufacturing an ignition coil for an internal combustion engine according to any one of the first to third aspects, wherein an outer peripheral core is provided on an inner peripheral side of the outer peripheral core. It is characterized in that the resin material is filled in a state in which an adhesion suppressing material for suppressing (140) from adhering to the resin material (175) is arranged.

Thus, the adhesion suppressing layer (142) can be easily provided on the inner peripheral side of the outer peripheral core (140).

Incidentally, the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, an ignition coil according to the present invention is used for supplying a high voltage (for example, 30 kV) to a spark plug (ignition device) of an engine for driving a vehicle (internal combustion engine). FIG. 1 is an axial cross-sectional view (an overall cross-sectional view) of an ignition coil 100 according to the present embodiment, and FIG. 2 is a cross-sectional view along AA in FIG.

Incidentally, the ignition coil 10 according to this embodiment is
No. 0 is integrated with the plug cap by making the outer shape a stick (stick).
0 is housed in a plug hole formed in a cylinder head (not shown) at the time of mounting. The plug cap is a cap-shaped connector that electrically connects the spark plug and the ignition coil.

In FIG. 1, reference numeral 110 denotes a rod-shaped center core made of a magnetic material (in this embodiment, a silicon steel plate). As shown in FIG. The lamination core is formed by laminating a plurality of thin strips extending in the direction (direction). Note that permanent magnets 112 and 113 having polarities opposite to the direction of the magnetic field induced by the primary coil 120 described later are disposed on both ends in the longitudinal direction of the central core 110.

On the outer peripheral side of the center core 110, a secondary coil (inner peripheral side coil) 130 which is electrically connected to the spark plug side is arranged. Outside the secondary coil 130, the secondary coil 130 A primary coil (outer circumference side coil) 120 to which a control signal from an igniter for controlling a high voltage generated in the coil is input is arranged.

Since the ignition coil 100 boosts the voltage input to the primary coil 120 and outputs the boosted voltage from the secondary coil 130, the number of turns of the secondary coil 130 is smaller than the number of turns of the primary coil 120. Since many secondary coils 130 are arranged inside the primary coil 120, the diameter of the winding of the secondary coil 130 is smaller than the diameter of the winding of the primary coil 120.

Reference numeral 121 denotes a primary spool (outer peripheral winding frame) for winding the winding of the primary coil 120 disposed between the secondary coil 130 and the primary coil 120. The primary spool 121 is made of resin. (In this embodiment, the PPE
It is formed in a substantially cylindrical shape with an electrically insulating material such as resin.

On the outer peripheral surface of the primary spool 121 (between the primary coil 120 and the primary spool 121), P
A thin film 122 made of ET (polyethylene terephthalate) is wound, and the first film 121 prevents the primary spool 121 from completely adhering to a molding resin (a casting resin) described later. It constitutes an adhesion suppressing layer.

Reference numeral 131 denotes a secondary spool (inner peripheral winding frame) for winding the winding of the secondary coil 130 disposed between the secondary coil 130 and the center core 110. The spool 131 is formed in an approximately cylindrical shape with an electrically insulating material such as a resin (in the present embodiment, a PPE resin).

As shown in FIG. 3, the thickness of the secondary coil 130 increases toward the high voltage side (in this embodiment, the spark plug side of the axial end of the secondary coil 130). (The number of winding steps of the coil).

Then, on the inner peripheral surface side of the secondary spool 131 (between the secondary spool 131 and the central core 110),
As shown in FIG. 1, a cushioning member (a rubber tube in the present embodiment) 1 for preventing an edge portion (corner portion) of the central core 110 from directly contacting the secondary spool 131.
11 are provided.

Incidentally, the cushioning member (shrinkable tube) 111
Is to reduce the diameter dimension by heating,
By heating the central core 110 in a state of being inserted into the buffer member (shrink tube) 111, the buffer member (shrink tube) 111 is brought into close contact with the central core 110.

A cylindrical outer core 140 made of a magnetic material (in this embodiment, a silicon steel plate) is provided on the outer peripheral side of the primary coil 120.
As shown in FIG. 3, three pipe members are laminated coaxially, and the entire inner peripheral surface (the surface on the side of the primary coil 120) 141 is provided with an outer core 140. A release layer (second adhesive) that is coated (coated) with an adhesion suppressor (in this embodiment, a fluororesin) for preventing the mold resin from completely adhering, thereby separating the outer core 140 and the casting resin. A suppression layer 142 is provided.

In FIG. 1, reference numeral 160 denotes a connector to which a cable (not shown) to which a control signal is distributed is connected, and 161 denotes a terminal for supplying a control signal to the primary coil 130. .

Reference numeral 170 denotes a housing of the ignition coil 100 made of resin (PPS resin in the present embodiment). The housing 170 fixes the connector 160 and the ignition coil 100 to a cam cover (not shown). First housing portion 17 with integrated bracket portion 162
1. The second housing part 172 that covers the outer peripheral side of the outer peripheral core 140 and protects the ignition coil main body (the part where the primary coil 120, the secondary coil 130, and the like are accommodated), and the axial end of the secondary coil. A first high-voltage terminal 181 to which the provided lead wire (not shown) is connected, and an electrical connection (relay) between the first high-voltage terminal 181 and a spring 182 made of a conductive material that contacts a terminal of the spark plug. ) Comprising three parts such as a third housing (high-pressure tower) 173 in which a second high-voltage terminal 183 and the like are stored.

The interior of the housing 170 (particularly, the interior of the outer core 140) is filled with an electrically insulative casting resin (in this embodiment, an epoxy resin) so that both the coils 120 and 130 and other components are filled. Are fixed in the mold. In FIGS. 1 to 3, reference numeral 174 denotes a resin layer made of a filled resin (cast resin).
175 is the second housing 172 and the third housing 1
This is a rubber packing for preventing the casting resin from leaking from the connection portion with the 73.

The release layer (second adhesion suppressing layer) 142
As described above, the adhesive is filled in a state where the adhesion suppressing material is arranged on the inner circumference 141 side of the outer core 140 by a coating process, a lamination process, or the like.

Next, the features (effects) of this embodiment will be described.

The primary spool 121 and the secondary spool 13
As shown in FIG. 3, a flange portion (collar portion) 121a for preventing the winding from collapsing,
131a, but as described in the section of "Problems to be Solved by the Invention", a lead wire (not shown) provided at an axial end (spark plug side) of the secondary coil 130. The primary spool 121 is extended from the flange portion 121a to the spark plug side in order to ensure the surrounding electrical insulation, and the primary spool 121 secures the electrical insulation and the portion where the thin film 122 is wound. Up to the flange portion 121a, at a portion of the primary spool 121 extending from the flange portion 121a to the spark plug side (hereinafter, this portion is referred to as an extension portion 123). ) 174
And the extension portion 123 are prevented from being separated from each other.

On the other hand, on the inner peripheral surface 141 of the outer core 140, at least a portion corresponding to the portion where the thin film 122 is not provided (extending portion 123),
2, the thermal stress generated due to the difference in linear expansion coefficient between the components constituting the ignition coil 100 is reduced to prevent the components (particularly, the primary spool 121) from being cracked. it can.

At this time, the inner peripheral surface 141 of the outer core 140
In this case, a void is generated due to the separation, but in the extension 123 near the lead line, the resin layer (filled casting resin) 174 and the extension 123 do not separate, so that the electrical insulation property is reduced. (Insulation resistance) does not significantly decrease.

As described above, according to the present embodiment, at the axial end portions of the coils 120 and 130 provided with the lead wires, while maintaining high electrical insulation (insulation resistance), thermal stress is maintained. Can be alleviated.

In this embodiment, as shown in FIG. 3, the release layer 142 is not provided over the entire area corresponding to the area where the thin film 122 is not provided (the extension 123). This is because the outer core 140 is not arranged in the entire region corresponding to the extension 123.

Therefore, the outer peripheral core 140 is
In a case where the release layer 142 is disposed over the entire region corresponding to the extension portion 123, it is desirable that the release layer 142 be provided over the entire region corresponding to the extension portion 123 of the outer peripheral core 140.

(Other Embodiments) In the above embodiment, the inner peripheral side is the secondary coil and the outer peripheral side is the primary coil. However, the present invention is not limited to this, and the outer peripheral side is the secondary coil. It is good also as a coil and an inner peripheral side may be a primary coil.

In the above-described embodiment, the release layer 142 is provided on the entire inner peripheral surface 141 of the outer core 140 in consideration of workability (productivity). Since the stress can be relieved by the thin film 122, the release layer 142 may be provided at least at a portion corresponding to a portion where the thin film 122 is not provided (the extension portion 123).

In the above-described embodiment, the adhesion suppressing material is applied to the outer core 1 by coating or laminating.
Although the inner peripheral surface 141 of the forty is coated, the means is not limited to this, and other means may be used.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ignition coil according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view of a portion B in FIG. 1;

[Explanation of symbols]

110: central core, 120: primary coil, 121: primary spool, 122: thin film, 130: secondary coil, 131: secondary spool, 140: outer peripheral core, 142
... release layer.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01F 31/00 501C (72) Inventor Masafuto Sano 1-1-1 Showa-cho, Kariya-shi, Aichi Pref. Inventor Masahiko Aoyama 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Corporation (reference) 3G019 KA23 KB09 KC01 KC04 KC05 KC07

Claims (4)

[Claims] 1. A rod-shaped central core (11) made of a magnetic material.
0), an inner peripheral coil (130) wound around the outer periphery of the central core (110), and the central core (110) and the inner peripheral coil (130).
And an inner winding frame (13) made of an electrically insulating material for winding the winding of the inner coil (130).
1), an outer peripheral coil (120) wound on the outer peripheral side of the inner peripheral coil (130), the inner peripheral coil (130), and the outer peripheral coil (12).
0), and an outer peripheral winding frame (121) made of an electrically insulating material for winding the winding of the outer peripheral coil (120); and an outer peripheral side of the outer peripheral core (120). And an outer peripheral core (140) made of a magnetic material, wherein the outer core (140) is filled with a resin material having electrical insulation and both coils (120, 130) are molded and fixed. An engine ignition coil, wherein at least a portion of the inner peripheral surface (141) of the outer peripheral core (140) corresponding to an axial end of the outer peripheral winding frame (121) is provided with the outer peripheral core (140). ) Is provided with an adhesion suppressing layer (142) for preventing the resin material (175) from adhering to the resin material (175). 2. A rod-shaped central core made of a magnetic material.
0), an inner peripheral coil (130) wound around the outer periphery of the central core (110), and the central core (110) and the inner peripheral coil (130).
And an inner winding frame (13) made of an electrically insulating material for winding the winding of the inner coil (130).
1), an outer peripheral coil (120) wound on the outer peripheral side of the inner peripheral coil (130), the inner peripheral coil (130), and the outer peripheral coil (12).
0), and an outer peripheral winding frame (121) made of an electrically insulating material for winding the winding of the outer peripheral coil (120); and an outer peripheral side of the outer peripheral core (120). And an outer peripheral core (140) made of a magnetic material, wherein the outer core (140) is filled with a resin material having electrical insulation and both coils (120, 130) are molded and fixed. An ignition coil for an engine, comprising: the outer peripheral coil (120) and the outer peripheral winding frame (12).
1), a first adhesion suppressing layer (122) for preventing the outer peripheral side winding frame (121) from adhering to the resin material (175) is provided. The outer core (140) adheres to the resin material (175) at least in a portion of the inner peripheral surface (141) of the (140) corresponding to the portion where the first adhesion suppressing layer (122) is not provided. An ignition coil for an internal combustion engine, comprising: a second adhesion suppressing layer (142) for suppressing the occurrence of such a situation. 3. The ignition coil according to claim 1, wherein the number of turns of the inner coil is greater than the number of turns of the outer coil. 4. The method for manufacturing an ignition coil for an internal combustion engine according to claim 1, wherein the outer peripheral core (1) is provided on an inner peripheral side of the outer peripheral core (140).
40) A method of manufacturing an ignition coil for an internal combustion engine, wherein the resin material is filled in a state where an adhesion suppressing material for suppressing adhesion of the resin material to the resin material (175) is arranged.