JPH11224824A - Ignition coil - Google Patents

Abstract

(57) Abstract: To improve the durability and reliability of an ignition coil by suppressing the occurrence of partial defects in an insulating resin due to heat shrinkage or thermosetting shrinkage of the resin. SOLUTION: An ignition coil 10 includes a case 11, an inner core 12, a secondary coil 13 accommodated in the case 11,
It includes a primary coil 14, an outer core 15, and the like. The gap between the members accommodated in the case 11 is sealed by an insulating layer 16 made of epoxy resin. Primary coil 14
Is composed of a winding body 35 and sleeves 37 and 38 arranged at both ends of the winding body 35. The inner peripheral surface of the winding body 35 is covered with a film 40. The film 40 includes a base layer 41 made of glass cloth and an insulating layer 1 made of silicon material.
6 and a three-layer structure including an adhesive layer 43 in contact with the inner peripheral surface of the winding body 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition coil, and more particularly, to a tubular case in which an inner core, an inner winding body and an outer winding body are concentrically housed and filled with an insulating resin. It relates to an ignition coil.

[0002]

2. Description of the Related Art As a conventional ignition coil, as shown in FIG. 16, an inner core 102 is provided at a center portion of a case 101, and a primary coil 103 and a secondary coil 103 are sequentially arranged so as to surround the outer periphery of the inner core 102. It is known that 104 are arranged concentrically (for example, "ignition device for internal combustion engine" described in JP-A-8-293418 and JP-A-9-167709).

In such an ignition coil 100, a high voltage for ignition is generated. Therefore, an insulating layer 105 is formed by filling and hardening an insulating resin in a case 101, and each member is formed by the insulating layer 105. The insulation between them is ensured.

[0004]

However, in the above-described ignition coil, each member disposed in the case 101 is formed of a different material such as a metal or a resin, and these members have different thermal expansion coefficients. When the temperature of the ignition coil decreases in accordance with the ambient temperature, thermal stress due to the difference in thermal contraction is generated in the insulating layer 105, and a minute crack, that is, a partial defect may be generated in the insulating layer 105. Further, such a partial defect is caused by the case 10 as well as the thermal stress caused by the difference in thermal contraction.
After the insulating resin is filled in the resin 1, the same occurs due to the residual stress generated when the insulating resin cures and contracts.

[0005] When such a partial defect occurs in the insulating layer 105 between the primary coil 103 and the secondary coil 104, the dielectric constant of the defective part increases, and the potential gradient in the same part increases. Increases locally. As a result, this defective part may be burned by discharge,
The durability and reliability of the ignition coil may be reduced.

[0006] In addition, cracks may also occur in the insulating layer 105 located on the outer peripheral side of the secondary coil 104 due to the thermal stress and the residual stress.
Gradually extend to the inner side of the two coils 104 and 105
Similarly, in the case where a partial defect occurs between them, the durability and reliability of the ignition coil may be reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the occurrence of partial defects in an insulating resin due to thermal shrinkage or thermosetting shrinkage of the insulating resin, thereby improving the durability of the ignition coil. The purpose is to improve reliability and reliability.

[0008]

To achieve the above object, according to the first aspect of the present invention, an inner winding body and an outer winding formed by laminating and winding an inner core and a winding in a cylindrical case are provided. An ignition coil in which a winding body is accommodated concentrically and an insulating resin is filled and hardened between both winding bodies and on the outer peripheral side of the outer winding body, comprising a film covering an outer peripheral portion of the outer winding body. Like that.

According to the above configuration, since the outer peripheral portion of the outer winding body is covered with the film, the insulating resin filled in the case is less likely to penetrate into the gaps between the winding layers in the outer winding body. For this reason, each layer of the winding of the outer winding body is not adhered by the insulating resin or becomes partial even if it is adhered, and the gap between the winding layers of the outer winding body can be enlarged. The expansion of the gap absorbs the heat shrinkage and the cure shrinkage of the insulating resin, and alleviates the thermal stress and residual stress generated in the insulating resin.

According to a second aspect of the present invention, in the ignition coil according to the first aspect, at least one surface of the film has releasability from an outer winding body or an insulating resin that comes into contact with the same surface.

According to the above construction, one surface of the film having releasability does not adhere to the outer winding body or the insulating resin, and an expandable gap is provided between the film and the outer winding body or the insulating resin. Will be present. Therefore, the heat shrinkage and the curing shrinkage generated in the insulating resin due to the expansion of the gap are absorbed. Therefore, even if the insulating resin enters the gap between the winding layers in the outer winding body and the winding layers are bonded by the insulating resin, the thermal stress and residual stress generated in the insulating resin are surely reduced. Is done.

According to the third aspect of the present invention, the inner winding and the outer winding formed by laminating and winding the inner core and the winding are accommodated concentrically in a cylindrical case. In an ignition coil in which the insulating resin is filled and hardened between the outer winding body and the outer peripheral side of the outer winding body, at least one surface of the ignition coil is provided with a film having releasability from the outer winding body and the insulating resin. To intervene.

According to the above construction, one surface of the releasable film does not adhere to the outer winding body, nor does it adhere to the insulating resin that has entered the inside of the outer winding body. Therefore, the thermal shrinkage and curing shrinkage generated in the insulating resin are absorbed by the expansion of the gap between the film and the outer winding body or the insulating resin, so that the thermal stress and the residual stress of the resin are reliably reduced. Become so. Further, since the film is interposed between the layers of the outer winding body, both the inner and outer peripheral portions of the outer winding body are covered with the insulating resin.

According to the fourth aspect of the present invention, the inner winding and the outer winding formed by laminating and winding the inner core and the winding are housed concentrically in a cylindrical case. In the ignition coil, the insulating resin is filled and hardened between the outer winding and the outer winding, and at least one of the outer windings contacting the same surface with the outer winding or a film having a peeling property against the insulating resin. The inner peripheral part of the winding body is covered.

According to the above construction, one surface of the releasable film does not adhere to the outer winding body or the insulating resin. Accordingly, the thermal shrinkage and curing shrinkage generated in the insulating resin are absorbed by the expansion of the gap between the film and the outer winding body or the insulating resin, so that the thermal stress and the residual stress of the resin are reduced. become.

According to the fifth aspect of the present invention, the inner core, the outer coil, and the cylindrical outer core formed by laminating and winding the inner core, the coil, and the cylindrical outer core are concentrically housed in the cylindrical case. In an ignition coil in which insulating resin is filled and hardened between the two winding bodies and on the outer peripheral side of the outer winding body, at least one surface thereof has a peeling property with respect to the outer core or the outer winding body that contacts the same surface. The inner peripheral portion of the outer core is covered with the film having the outer core.

According to the above construction, one surface of the film having releasability does not adhere to the outer core or the insulating resin, and an expandable gap exists between the film and the outer core or the insulating resin. Accordingly, the thermal shrinkage and the curing shrinkage generated in the insulating resin due to the expansion of the gap are absorbed, so that the thermal stress and the residual stress of the resin are reduced.

According to the present invention, the inner winding and the outer winding formed by laminating and winding the inner core and the winding are accommodated concentrically in a cylindrical case, and the two windings are provided. In the ignition coil in which the insulating resin is filled and hardened between the outer winding and the outer winding, at least one of the insulating resin positioned between the two windings and the insulating resin positioned on the outer circumference of the outer winding. A film having a releasability from an insulating resin is arranged concentrically on at least one surface of the inside of the substrate.

According to the above structure, one surface of the film having releasability does not adhere to the insulating resin, and an expandable gap exists between the film and the outer core or the insulating resin. Accordingly, the thermal shrinkage and the curing shrinkage generated in the insulating resin due to the expansion of the gap are absorbed, so that the thermal stress and the residual stress of the resin are reduced.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. This ignition coil does not require a distributor, so-called DLI ignition method (Distributor Less
Ignition system).

As shown in FIG. 1, the ignition coil 10 includes a case 11, an inner core 12 housed in the case 11,
Secondary coil 13, primary coil 14, and outer core 15
Etc. are provided. The case 11 has a primary coil 14.
Igniter 20 for intermittently controlling the primary current flowing through
Is built-in.

The gap between the members housed in the case 11 is sealed by the insulating layer 16 as described above. The insulating layer 16 is formed by filling a liquid epoxy resin in the case 11 and heating and curing the epoxy resin at a predetermined temperature. The insulation between the members in the case 11 is ensured by the insulating layer 16.

The case 11 is formed in a substantially cylindrical shape from a resin material such as PBT (polybutylene terephthalate) resin. A harness (not shown) from an engine control device (both not shown) is provided at the upper end of the case 11.
And an attachment portion 11b for bolting the ignition coil 10 to a cylinder head (not shown) of the engine are integrally formed.
A cylindrical member 18 made of a resin material such as T resin is fitted inside. Inside the cylindrical member 18 is a metal high-pressure member 2.
The upper end of a spring 22 that is electrically connected to a spark plug (not shown) is fixed to the high-pressure member 21. A cylindrical rubber boot 23 made of silicone rubber is fitted on the lower end of the cylindrical member 18.

The inner core 12 is formed in a column shape by laminating a plurality of silicon steel plates, and is disposed at the center of the case 11 so as to extend vertically. Magnets 25 and 26 are fixed to both upper and lower ends of the inner core 12, and the magnets 25 and 26 and the inner core 1 are fixed.
2 is entirely covered with a rubber layer 27.

A substantially cylindrical secondary bobbin 30 is externally fitted to the magnets 25 and 26 and the inner core 12 covered by the rubber layer 27 as described above. This secondary bobbin 3
Numeral 0 is made of PPE (polyphenylene ether) resin which is a thermoplastic resin, and a plurality of ribs 31 are formed on the outer periphery thereof at predetermined intervals in the axial direction. Each of these ribs 3
A secondary winding 32 made of an enameled wire having a wire diameter of 0.03 to 0.1 mm is laminated and wound between the two. A terminal 33 that is in contact with the high-voltage member 21 is fixed to a lower end of the secondary bobbin 30. A high-voltage side terminal (not shown) of the secondary winding 32 is connected to the terminal 33.
The secondary winding 13 and the secondary bobbin 30 constitute a secondary coil 13 that generates a high voltage for ignition.

A cylindrical primary coil 14 is fitted on the outer peripheral side of the secondary coil 13 at a predetermined interval in the radial direction. The primary coil 14 is a bobbin-less structure coil having no bobbin, unlike the secondary coil 13.
A winding body 3 formed by winding a primary winding 34 of an enameled wire having a wire diameter of 0.3 to 1.0 mm in two layers so as to form a cylindrical shape.
5 and a pair of sleeves 37 and 38 disposed at both ends of the winding body 35. Each of these sleeves 37, 38 has a function of holding the winding body 35 in a predetermined shape, and flanges 37a, 38a with which the upper and lower ends of the winding body 35 come into contact are formed on the outer periphery.

Further, as shown in FIG. 2, the inner peripheral surface of the winding body 35 is substantially entirely covered with a band-shaped film 40. The insulating layer 16 is formed between the film 40 and the secondary coil 13.

As shown in FIG. 5, the film 40 includes a base layer 41 made of glass cloth, a release layer 42 laminated on the inner peripheral surface of the base layer 41, and an adhesive layer 43 laminated on the outer peripheral surface of the base layer 41. And a three-layer structure consisting of Release layer 4
2 is a silicone material (silicone oil) known as a release material
Is applied to one surface of the base layer 41 and is in contact with the insulating layer 16. Since this silicon material has a weak affinity for the epoxy resin forming the insulating layer 16, the adhesive force between the peeling layer 42 and the insulating layer 16 is extremely weak. Further, the adhesive layer 43 is formed of a well-known silicone-based adhesive, and
Is in contact with a winding layer (hereinafter, abbreviated as “inner layer”) 35a on the inner peripheral side in FIG.

The outer circumferential side of the winding body 35 has a radial direction (FIG. 2).
Outer core 1 at a predetermined interval in the left-right direction
5 is fitted outside. The outer core 15 has a double pipe structure in which a cylindrical pipe made of a silicon steel plate is superimposed, and the outer peripheral surface thereof is in contact with the inner peripheral surface of the case 11.
An epoxy resin is also filled between the outer core 15 and a winding layer 35b (hereinafter, abbreviated as “outer layer”) of the winding body 35 to form an insulating layer 16.
Are formed, and the inner peripheral surface of the outer core 15 is in contact with the insulating layer 16.

The ignition coil 10 constructed as described above is inserted into a plug hole formed in a cylinder head (not shown) of the engine, and is bolted to the cylinder head at the mounting portion 11b. When the ignition coil 10 is fixed to the cylinder head in this manner, the spring 22 contacts an upper terminal (not shown) of the ignition plug, and the outer periphery of the upper end of the ignition plug is a rubber boot 23.
Covered by The ignition high voltage generated in the secondary coil 13 is supplied to the ignition plug via the high-pressure member 21 and the spring 22.

Next, a procedure for forming the above-mentioned winding body 35 will be described with reference to FIG. First, FIG.
As shown in (a), each sleeve 37, 38 is integrally rotated with respect to the rotation axis C1 of the winding machine so that the interval between the flanges 37a, 38a is equal to the axial length of the winding body 35. Fix as possible. Next, as shown in FIG. 3B, each flange 37 is rotated while rotating the rotation shaft C1.
a, the film 40 with respect to the rotation axis C1 between
Is spirally wound. At this time, the adhesive layer 4 of the film 40
3 is the outer peripheral surface. Further, as shown in FIG. 3C, the primary winding 34 is arranged and wound between the flanges 37a and 38a on the outer peripheral surface of the film 40, that is, on the adhesive layer 43, that is, the wires are in close contact with each other. The winding body 35 is formed by winding two layers in this state.

As described above, in the ignition coil 10 according to the present embodiment, the inner peripheral surface of the winding body 35 is
0, so that the release layer 42 of the film 40 is in contact with the insulating layer 16 located between the coils 13 and 14. As described above, this release layer 42
Has a weak affinity for the epoxy resin forming the insulating layer 16, the adhesive force between the film 40 and the insulating layer 16 is extremely weak.

Therefore, the insulating layer 16 located between the coils 13 and 14 and between the primary coil 14 and the outer core 15
When heat shrinkage or curing shrinkage occurs and a stress is applied to the contact portion between the insulating layer 16 and the film 40 so as to separate the two 16 and 40, a gap G is formed between the two 16 and 40 as shown in FIG. Will be done. And this gap G
Is formed, the thermal stress and the residual stress of the insulating layer 16 are released and reliably reduced.

The gap G is the same as a crack in that a portion having a large dielectric constant is formed, but differs in that the gap G is formed substantially uniformly over the entire axial and circumferential directions of the ignition coil 10. ing. That is, since the potential gradient does not locally increase as in the case of a crack, the gap G cannot be a partial defect causing partial discharge.

As described above, according to the present embodiment, the insulating layer 1
6, the thermal stress and residual stress of the ignition coil 10 are released and reliably reduced by the formation of the gap G. Therefore, it is possible to reliably suppress the occurrence of partial defects in the same layer 16 and improve the durability and reliability of the ignition coil 10. it can.

Since the ignition coil 10 is housed in the plug hole, the primary coil 14 having a bobbinless structure is employed to reduce the diameter.
When the primary coil 14 having the bobbinless structure is employed as described above, the winding of the primary winding 34 collapses, and the winding 35
There is a concern that it will be difficult to maintain the shape of the first shape.

In this respect, in this embodiment, the film 40 having the adhesive layer 43 is used, and the primary winding 3 is formed on the adhesive layer 43.
4 is wound. Therefore, the winding collapse of the primary winding 34 is suppressed by the adhesive force of the adhesive layer 43, and the shape of the winding body 35 and the winding density thereof can be stabilized.

In this embodiment, an adhesive layer 43 made of a silicon-based adhesive is laminated on the outer peripheral surface of the film 40. Therefore, thermal contraction and curing contraction generated in the insulating layer 16 due to the elastic deformation of the adhesive layer 43 can be absorbed. Therefore, the thermal stress and the residual stress of the insulating layer 16 are reduced, so that the occurrence of partial defects in the insulating layer 16 can be reliably suppressed.

Further, in this embodiment, the rotating shaft C1 of the winding machine is used.
Then, after winding the film 40, the primary winding 34 is wound on the film 40 to manufacture the winding body 35. Therefore, when the winding body 35 is removed from the rotating shaft C1, the inner peripheral surface thereof is protected by the film 40, so that the rotating shaft C1 and the primary winding 34 rub against each other. Can be avoided, and the reliability of the ignition coil 10 can be further improved.

In the present embodiment, the release layer 42 and the adhesive layer 43 are formed of a silicon-based material having excellent heat resistance.
There is almost no alteration of 43. Therefore, even when the ignition coil 10 is used for a long time at a high temperature, each of the layers 42, 4
The peelability or adhesiveness of No. 3 is maintained, and the action based on the above-described peelability and adhesiveness can be reliably achieved.

Further, as in the present embodiment, the ignition coil 10 housed in the plug hole has a limited shape, and the potential gradient in the case 11 is extremely large. Its durability and reliability tend to be significantly reduced. In this regard, the configuration according to the present embodiment can suppress the occurrence of partial defects in the insulating layer 16 due to thermal stress or residual stress, and is therefore suitable for an ignition coil having the above-described tendency.

[Second Embodiment] Next, a second embodiment will be described focusing on differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 6 shows an ignition coil 10 according to this embodiment.
Is shown in an enlarged manner. As shown in the figure, the ignition coil 10 differs from the first embodiment in the arrangement position of the film 40 in the case 11 and the structure of the film 40. That is, in the present embodiment, the outer peripheral surface of the winding body 35 is substantially entirely covered with the film 40, and the insulating layer 16 is formed between the film 40 and the outer core 15 by being filled with epoxy resin. ing.

The film 40 comprises a base layer 41 and an adhesive layer 43 laminated on the inner peripheral surface of the base layer 41, and has a two-layer structure in which the release layer 42 is omitted. The base layer 41 is made of a resin material such as polyphenylene sulfide (PPS) resin, polyethylene terephthalate (PET) resin, or polyethylene naphthalate (PEN) resin, and is in contact with the insulating layer 16 located on the inner peripheral side of the outer core 15. As in the first embodiment, the adhesive layer 43 is made of a silicon-based adhesive and is in contact with the outer peripheral portion of the outer peripheral layer 35a.

In the present embodiment, one winding machine is used.
After winding the secondary winding 34 into two layers to form a winding 35,
As in the first embodiment, a belt-like film 40 is wound around the outer peripheral layer 35b of the winding body 35.

In the ignition coil 10 according to the present embodiment having the above-described configuration, since the outer peripheral surface of the winding body 35 is covered with the film 40, the liquid epoxy resin filled in the case 11 is used for the winding body. There is no intrusion between the winding layers 35a and 35b from the outer peripheral side of 35. Also, 1
Since the secondary winding 34 is arranged and wound to form the winding body 35, the winding layer 35 of the winding body 35 is
Epoxy resin hardly permeates between a and 35b. As a result, the epoxy resin becomes the winding layer 35 of the winding body 35.
The inner layer 35a and the outer layer 35b are hardly adhered to each other by the epoxy resin.
Alternatively, even if they are adhered, they become partial. For this reason, the adhesive force between the winding layers 35a and 35b of the winding body 35 is extremely weak.

Therefore, heat shrinkage or hardening shrinkage occurs in the insulating layer 16 located between the coils 13 and 14 and between the film 40 and the outer core 15, and the inner peripheral layer 35 a of the winding body 35.
When a stress acting to separate the outer peripheral layer 35b acts, a gap G is formed between the two winding layers 35a and 35b as shown in FIG. By forming such a gap G, thermal stress and residual stress of the insulating layer 16 are released and reduced. Therefore, also in the present embodiment, it is possible to suppress the occurrence of partial defects in the insulating layer 16 and to improve the durability and reliability of the ignition coil 10.

In the present embodiment, the outer periphery of the winding body 35 is covered with the film 40, and the adhesive layer 43 of the film 40 is brought into contact with the outer peripheral layer 35b of the winding body 35. Therefore, the collapse of the primary winding 34 is suppressed by the adhesive force of the adhesive layer 43, and the shape of the winding body 35 can be stabilized.

[Third Embodiment] Next, a third embodiment will be described focusing on differences from the second embodiment. Note that the same components as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 8 shows an ignition coil 10 according to this embodiment.
Is shown in an enlarged manner. As shown in the figure, the ignition coil 10 differs from the second embodiment in the structure of the film 40 covering the outer periphery of the winding body 35. That is, in the present embodiment, the film 40 having a three-layer structure in which the release layer 42 is laminated on the outer peripheral surface of the base layer 41 made of a resin material is used, and the release layer 42 of the film 40 is formed inside the outer core 15. The insulating layer 16 located on the peripheral side is brought into contact. This release layer 42 is formed by applying silicon oil to one surface of the base layer 41, as in the second embodiment.

According to the present embodiment configured as described above, since the release layer 42 in contact with the insulating layer 16 has a low affinity for the insulating layer 16, the film 40 and the insulating layer 16
Is extremely weak.

Accordingly, heat shrinkage and curing shrinkage occur in the insulating layer 16 located between the coils 13 and 14 and between the film 40 and the outer core 15, and the insulating layer 16 and the film 4
When a stress acting to separate the two 16 and 40 acts on the contact portion of 0, a gap G is formed between the two 16 and 40 as shown in FIG. As a result, if the epoxy resin enters between the inner peripheral layer 35a and the outer peripheral layer 35b of the winding body 35 and the two layers 35a and 35b are bonded by the same resin, as described in the second embodiment, ,
Even if it is difficult to form the gap G between the two layers 35a and 35b, the gap G is formed between the film 40 and the insulating layer 16 as described above, so that the epoxy resin is formed. Thermal stress and residual stress are released and reliably reduced. Further, the inner peripheral layer 35 a and the outer peripheral layer 3
If a gap is also formed between the first and second members 5b, it is possible to further reduce the thermal stress and the like. For this reason, according to the present embodiment, the occurrence of partial defects in the insulating layer 16 can be suppressed more reliably, and the durability and reliability of the ignition coil 10 can be improved.

[Fourth Embodiment] Next, a fourth embodiment will be described focusing on differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 10 shows an ignition coil 1 according to this embodiment.
0 is shown enlarged. As shown in FIG.
Is different from that of the first embodiment. That is, in the present embodiment, the film 40 is interposed between the inner peripheral layer 35a and the outer peripheral layer 35b of the winding body 35 over the entire circumference. Therefore, the inner peripheral surface of the inner peripheral layer 35a and the outer peripheral surface of the outer peripheral layer 35b are both covered with the insulating layer 16.

As in the first embodiment, the film 40 includes a base layer 41 made of glass cloth, a release layer 42 laminated on the inner peripheral surface of the base layer 41, and an adhesive layer laminated on the outer peripheral surface of the base layer 41. 43 in a three-layer structure. Then, the release layer 42 is provided on the outer peripheral surface of the inner peripheral layer 35a by the adhesive layer 43.
Are in contact with the inner peripheral surface of the outer peripheral layer 35b.

When the winding body 35 is formed in the present embodiment, first, the primary winding 34 is wound around the rotation axis C1 (shown in FIG. 3) of the winding machine by a single layer. An inner peripheral layer 35a is formed. Then, similarly to the first embodiment, a band-shaped film 40 is wound around the outer periphery of the inner peripheral layer 35a. At this time, the adhesive layer 43 of the film 40 is set to be the outer peripheral surface. Then, on the outer peripheral surface of the film 40,
That is, the primary winding 34 is further wound on the adhesive layer 43 to form the outer peripheral layer 35b of the winding body 35.

As described above, in the present embodiment, the film 40 is interposed between the winding layers 35a and 35b of the winding body 35, and the release layer 42 is brought into contact with the inner peripheral layer 35a of the winding body 35. Therefore, the film 40 and the inner peripheral layer 35a do not adhere to each other. In addition, even if the epoxy resin invades from the inner peripheral portion of the winding body 35 to between the winding layers 35a and 35b, the resin comes into contact with the peeling layer 42 of the film 40. The resin and the film 40 are not bonded.

Accordingly, the insulating layer 16 located between the coils 13 and 14 and between the primary coil 14 and the outer core 15
Heat shrinkage and curing shrinkage occur in the inner circumferential layer 35 of the winding body 35.
When a stress acts to separate the outer layer 35a and the outer layer 35b, a gap G is formed between the film 40 and the inner layer 35a of the winding body 35 as shown in FIG. The formation of such a gap G releases and reduces the thermal stress and residual stress of the insulating layer 16. As a result, also in the present embodiment, the occurrence of partial defects in the insulating layer 16 can be suppressed, and the durability and reliability of the ignition coil 10 can be improved.

Further, in the present embodiment, the film 40 is interposed between the winding layers 35a and 35b of the winding body 35 instead of covering the inner and outer peripheral surfaces of the winding body 35 with the film 40. Therefore, the inner peripheral surface of the inner peripheral layer 35a and the outer peripheral surface of the outer peripheral layer 35b are both covered with the insulating layer 16. Accordingly, the mechanical strength of the winding body 35 can be substantially increased, the winding of the primary winding 34 can be prevented from being broken, and the shape of the winding body 35 can be stably maintained in the case 11. it can.

In this embodiment, since the primary winding 34 is wound on the adhesive layer 43 of the film 40 to form the outer peripheral layer 35b of the winding body 35, the same as in the first embodiment. The primary winding 3 by the adhesive force of the adhesive layer 43.
4 is suppressed, and the shape of the winding body 35 and the winding density thereof can be stabilized.

[Fifth Embodiment] Next, a fifth embodiment will be described focusing on differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 12 shows an ignition coil 1 according to this embodiment.
0 is shown enlarged. As shown in FIG.
And the structure of the film 40 are different from those of the first embodiment. That is, in the present embodiment, the inner peripheral surface of the outer core 15 is substantially entirely covered with the film 40, and the insulating layer 16 is formed by filling the space between the film 40 and the winding body 35 with epoxy resin. Have been.

The film 40 comprises a base layer 41 and a release layer 42 laminated on the outer peripheral surface of the base layer 41, and has a two-layer structure in which the adhesive layer 43 is omitted. Further, unlike the first embodiment, the film 40 formed in a cylindrical shape is fitted inside the outer core 15 so that the peeling layer 42 of the film 40 comes into contact with the inner peripheral surface of the core 15. The base layer 41 is formed of a resin material such as PPS resin, PET resin, or PEN resin, which has higher rigidity than glass cloth, in consideration of the shape stability when being formed into a cylindrical shape as described above. Is in contact with the insulating layer 16 located on the side. Further, the release layer 42 is formed by applying silicon oil to one surface of the base layer 41 as in the first embodiment.

As described above, in this embodiment, the inner peripheral surface of the outer core 15 is covered with the film 40, and the release layer 42 of the film 40 is brought into contact with the inner peripheral surface of the outer core 15.

Accordingly, the insulating layer 16 located between the coils 13 and 14 and between the primary coil 14 and the outer core 15
When heat shrinkage and curing shrinkage occur on the outer core 15 and a stress acting to separate the outer core 15 and the film 40 is applied, as shown in FIG.
A gap G is formed between the two 15 and 40 as shown in FIG. By forming such a gap G, the thermal stress and the residual stress of the insulating layer 16 are released and are reliably reduced. As a result, also in the present embodiment, the occurrence of partial defects in the insulating layer 16 can be reliably suppressed, and the durability and reliability of the ignition coil 10 can be improved.

In particular, since the outer core 15 made of an iron-based material has an extremely large elastic coefficient and is hardly deformed, the insulating layer 16 near the outer core 15 tends to generate excessive thermal stress or residual stress. According to the present embodiment, since the film 40 is arranged so as to be in contact with the inner peripheral surface of the outer core 15, the thermal stress and the residual stress of the insulating layer 16, which tends to be excessive, as described above, are surely reduced. Therefore, the occurrence of partial defects in the same layer 16 can be suppressed more reliably.

[Sixth Embodiment] Next, a sixth embodiment will be described focusing on differences from the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 14 shows an ignition coil 1 according to this embodiment.
0 is shown enlarged. As shown in FIG.
And the structure of the film 40 are different from those of the first embodiment. That is, in the present embodiment, the cylindrical film 40 is arranged concentrically with the coils 13 and 14 inside the insulating layer 16 located between the secondary coil 13 and the primary coil 14.

The film 40 is composed of the base layer 41 and the base layer 4.
1 and has a two-layer structure in which the adhesive layer 43 is omitted. After the secondary coil 13 and the primary coil 14 are accommodated in the case 11, the film 40 is inserted and arranged in a gap between the coils 13 and 14. The base layer 41 of the film 40 is made of a resin material such as PPS resin, PET resin, and PEN resin having higher rigidity than glass cloth in consideration of shape stability, and an insulating layer located between the coils 13 and 14. 16 is in contact. The peeling layer 42 is formed by applying silicon oil to one surface of the base layer 41, as in the first embodiment, and the insulating layer 16 located between the coils 13, 14 similarly to the base layer 41. Is in contact with

As described above, in the ignition coil 10 according to the present embodiment, the film 40 is disposed inside the insulating layer 16 located between the primary coil 14 and the secondary coil 13, Both surfaces are brought into contact with the insulating layer 16.

Accordingly, the insulating layer 16 located between the coils 13 and 14 and between the primary coil 14 and the outer core 15
When heat shrinkage or curing shrinkage occurs, a gap G is formed between the film 40 and the insulating layer 16 as shown in FIG. By forming such a gap G, the thermal stress and the residual stress of the insulating layer 16 are released and are reliably reduced. As a result, also in the present embodiment, the occurrence of partial defects in the insulating layer 16 can be reliably suppressed, and the durability and reliability of the ignition coil 10 can be improved.

The embodiment described above can be implemented by changing the configuration as follows. In the first and fourth embodiments, the film 40 may be constituted by the base layer 41 and the adhesive layer 43 by omitting the release layer 42. Even if the release layer 42 is omitted, the glass cloth forming the base layer 41 has a weak affinity for an enamel wire or an epoxy resin, so that the adhesive strength between the film 40 and the insulating layer 16 can be extremely weakened. Therefore, the film 40 and the insulating layer 16
Alternatively, the thermal stress and the residual stress of the insulating layer 16 can be reduced by the gap formed between the insulating layer 16 and the inner peripheral layer 35a, and the manufacturing cost can be reduced by omitting the release layer 42.

In the first embodiment, the release layer 42 laminated on the inner peripheral surface of the film 40 is brought into contact with the insulating layer 16, but the adhesive layer 43 is omitted and
A configuration may be adopted in which a release layer 42 is laminated on the outer peripheral surface of the film 40 on which the same layer 43 has been formed, and the release layer 42 is brought into contact with the inner peripheral layer 35 a of the winding body 35. According to such a configuration, the release layer 42 made of a silicon material is
Has a weak affinity for the enameled wire of
The adhesive force between the zero and the winding body 35 is extremely weak. Therefore, when thermal contraction or curing contraction occurs in the insulating layer 16, a gap is formed between the film 40 and the winding body 35, and the thermal stress and residual stress of the insulating layer 16 are released by the formation of the gap. Therefore, the generation of partial defects in the same layer 16 can be reliably suppressed.

In the first and fourth embodiments, the base layer 41 of the film 40 is formed of glass cloth. However, the base layer 41 is formed of PPS resin, PET resin, P
You may make it form with resin materials, such as EN resin.

In the second, third, fifth and sixth embodiments, the base layer 41 of the film 40 is made of PPS resin, PET resin, PE
Although the base layer 41 is formed of a resin material such as N resin, the base layer 41 may be formed of a glass cloth, for example, as in the first embodiment. In addition, the third, fifth, and sixth
When the base layer 41 is formed of a glass cloth in the embodiment described above, the glass cloth has a low affinity for the primary winding 34 and the epoxy resin.
2 can also be omitted.

In the third embodiment, the adhesive layer 43 laminated on the inner peripheral surface of the base layer 41 is omitted, and a release layer 42 is laminated instead of the same layer 43, and the release layer 42 is You may make it contact the outer peripheral layer 35b.

In the third, fifth, and sixth embodiments,
In particular, in a configuration in which the base layer 41 is formed of a PPS resin, the PPS resin is similar to a glass cloth.
Since the affinity for the epoxy resin is weak, the release layer 42 can be omitted.

In the above embodiments 1, 3 to 6, the release layer 4
Although the second layer 2 is formed of a silicon material, the release layer 42 may be formed by coating a fluorine resin, for example. Even if the release layer 42 is not separately formed, for example, if the film 40 is formed by a resin material to which a silicon material is added or a glass cloth impregnated with the silicon material, the film 40 is substantially the same as the film 40 having the release layer 42. Equivalent effects can be obtained.

The release layer 42 according to the fourth embodiment.
The peeling layer 42 may be laminated on the outer peripheral surface of the base layer 41 and the adhesive layer 43 may be laminated on the inner peripheral surface of the base layer 41 by reversing the arrangement positions of the adhesive layer 43 and the adhesive layer 43.

In the fifth embodiment, the release layer 42 is laminated on the outer peripheral surface of the base layer 41. However, the release layer 42 may be laminated on the inner peripheral surface of the base layer 41. In the sixth embodiment, the release layer 4 is formed on the inner peripheral surface of the base layer 41.
2, the release layer 42 may be laminated on the outer peripheral surface of the base layer 41. Also, primary coil 1
This film 40 may be arranged inside the insulating layer 16 located on the outer peripheral side of the film 4. Furthermore, outer core 1
Alternatively, a release layer made of a silicon material may be formed on the inner peripheral surface of 5.

In the second to fourth embodiments, the adhesive layer 43 may be omitted. In the above embodiments, the winding 35 is formed by winding the primary winding 34 in two layers, but the winding 35 may have three or more layers.

In each of the above embodiments, the film 40 in which the release layer 42 is laminated on both sides of the base layer 41 may be employed. In the above embodiments, the secondary coil 13 is arranged on the inner peripheral side and the primary coil 14 is arranged on the outer peripheral side in the case 11, but the arrangement positions of these coils 13 and 14 are reversed. You may.

In the above embodiments, the igniter 20 is built in the case 11 of the ignition coil 10.
The igniter 20 may be provided outside the ignition coil 10.

In each of the ignition coils in the above embodiments, the primary coil 14 has a bobbinless structure, but the primary coil 14 may have a bobbin. In the first to fourth and sixth embodiments, the outer core 1
5 may be fitted to the case 11 without being housed in the case 11.

In each of the above embodiments, the present invention is applied to the ignition coil 10 housed in the plug hole. However, the present invention is not housed in the plug hole, and is disposed on a cylinder head, for example. The present invention can also be applied to the ignition coil 10.

The technical ideas grasped from each of the above embodiments will be described below together with their effects. (1) In the ignition coil according to any one of claims 1 to 4, the outer winding body has a bobbin-less structure without a bobbin,
The film has an adhesive layer on a surface in contact with the outer winding body.

According to the above configuration, it is possible to prevent collapse of the outer winding body due to the adhesive force of the adhesive layer, and to stabilize the shape of the outer winding body. (2) In the ignition coil according to (1), the adhesive layer is made of a silicon-based material.

According to the above configuration, since the silicon-based material is excellent in heat resistance, deterioration of the adhesive layer due to heat is suppressed, and even if the ignition coil is used for a long time at a high temperature, the adhesive property in the same layer is reduced. Can be maintained.

(3) In the ignition coil according to the above (1), the adhesive layer is formed of an elastic material. According to the above configuration, thermal stress and residual stress generated in the insulating resin due to elastic deformation of the adhesive layer can be reduced.

(4) The ignition coil according to any one of claims 2 to 6, wherein the film has a release layer made of a silicon-based material. According to the above configuration, since the silicon material is excellent in heat resistance, deterioration of the peeling layer due to heat is suppressed, and even when the ignition coil is used for a long time at a high temperature, the peelability in the same layer can be maintained. it can.

(5) The ignition coil according to any one of claims 1 to 6, wherein the ignition coil is housed in a plug hole of the engine. Since the shape of the ignition coil housed in the plug hole is restricted and the internal potential gradient becomes extremely large, durability and reliability tend to be greatly reduced when a partial defect occurs. According to the above configuration, occurrence of partial defects in the insulating resin due to thermal stress and residual stress in such an ignition coil is suppressed, and durability and reliability of the ignition coil can be improved.

[0092]

According to the first aspect of the present invention, since the outer peripheral portion of the outer winding body is covered with the film, the insulating resin filled in the case fills the gap between the winding layers in the outer winding body. Difficult to penetrate. For this reason, each layer of the winding of the outer winding body is not adhered by the insulating resin or becomes partial even if it is adhered, and the gap between the winding layers of the outer winding body can be enlarged. The expansion of the gap absorbs the heat shrinkage and the cure shrinkage, and reduces the thermal stress and the residual stress generated in the insulating resin. As a result, the occurrence of partial defects in the insulating resin due to excessive thermal stress or residual stress is suppressed, and the durability and reliability of the ignition coil can be improved.

According to the second aspect of the present invention, at least one surface is formed of a film having releasability from an outer winding body or an insulating resin which is in contact with the same surface. Therefore, one surface of the film having releasability does not adhere to the outer winding body or the insulating resin, and the heat shrinkage generated in the insulating resin due to an increase in the gap between the film and the outer winding body or the insulating resin. And curing shrinkage becomes absorbed. Therefore, even if the insulating resin enters the gap between the winding layers in the outer winding body and the winding layers are bonded by the insulating resin, the thermal stress and residual stress generated in the insulating resin are surely reduced. Will be done. As a result, the occurrence of partial defects in the insulating resin caused by excessive thermal stress or residual stress is reliably suppressed, and the durability and reliability of the ignition coil can be improved.

According to the third aspect of the present invention, a film having releasability from the outer winding body and the insulating resin is interposed at least on one surface between the winding layers of the outer winding body. Therefore, one surface of the film having peelability does not adhere to the outer winding body or the insulating resin, and the heat shrinkage and curing shrinkage generated in the insulating resin causes the gap between the film and the outer winding body to increase. To be absorbed by
The thermal stress and residual stress of the resin are reduced. Further, since the film is interposed between the layers of the outer winding body, both the inner and outer peripheral portions of the outer winding body are covered with the insulating resin. As a result, the occurrence of partial defects in the insulating resin is suppressed, the durability and reliability of the ignition coil can be improved, and the mechanical strength of the outer winding body can be substantially increased.

According to the fourth aspect of the present invention, the inner peripheral portion of the outer winding body is covered with a film having at least one surface in contact with the same surface or a film having releasability from an insulating resin. Like that. Therefore, the releasability of the film does not adhere to one surface of the film and the outer winding body or the insulating resin, and an expandable gap exists between the film and the outer winding body or the insulating resin. Accordingly, the thermal shrinkage and the curing shrinkage generated in the insulating resin due to the expansion of the gap are absorbed, so that the thermal stress and the residual stress of the resin are reduced. As a result, the occurrence of partial defects in the insulating resin is suppressed, and the durability and reliability of the ignition coil can be improved.

In the invention described in claim 5, the inner peripheral portion of the outer core is covered with a film having releasability from at least one surface of the outer core or the outer winding body contacting the same surface. Therefore, the one surface of the film having the releasability does not adhere to the outer core or the insulating resin, and the heat shrinkage and the curing shrinkage generated in the insulating resin are absorbed by the expansion of the gap between the film and the outer core or the insulating resin. Therefore, the thermal stress and the residual stress of the resin are reduced. As a result, the occurrence of partial defects in the insulating resin is suppressed, and the durability and reliability of the ignition coil can be improved.

According to the present invention, at least one of the insulating resin positioned between the two winding bodies and the insulating resin positioned on the outer peripheral side of the outer winding body has at least one surface with respect to the insulating resin. The films having releasability are arranged concentrically. Therefore, one surface of the film having releasability does not adhere to the insulating resin, and heat shrinkage and curing shrinkage generated in the insulating resin are absorbed by the expansion of the gap between the film and the insulating resin. Thermal stress and residual stress of the resin are reduced. As a result, the occurrence of partial defects in the insulating resin is suppressed, and the durability and reliability of the ignition coil can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of an ignition coil according to a first embodiment.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a perspective view showing a procedure for forming a winding body.

FIG. 4 is a partially enlarged sectional view of an ignition coil.

FIG. 5 is a sectional view of a film.

FIG. 6 is a partially enlarged cross-sectional view of an ignition coil according to a second embodiment.

FIG. 7 is a partially enlarged cross-sectional view of the ignition coil.

FIG. 8 is a partially enlarged sectional view of an ignition coil according to a third embodiment.

FIG. 9 is a partially enlarged cross-sectional view of the ignition coil.

FIG. 10 is a partially enlarged cross-sectional view of an ignition coil according to a fourth embodiment.

FIG. 11 is a partially enlarged cross-sectional view of the ignition coil.

FIG. 12 is a partially enlarged cross-sectional view of an ignition coil according to a fifth embodiment.

FIG. 13 is a partially enlarged cross-sectional view of the ignition coil.

FIG. 14 is a partially enlarged sectional view of an ignition coil according to a sixth embodiment.

FIG. 15 is a partially enlarged cross-sectional view of the ignition coil.

FIG. 16 is a sectional view of a conventional ignition coil.

[Explanation of symbols]

10: ignition coil, 11: case, 12: inner core,
13 secondary coil, 14 primary coil, 15 outer core, 16 insulating layer, 30 secondary bobbin, 32 secondary winding, 34 primary winding, 35 winding body, 35a inside Surrounding layer,
35b: outer peripheral layer, 40: film, 41: base layer, 42:
Release layer, 43: adhesive layer, G: gap.

Claims (6)

[Claims] An inner winding and an outer winding formed by laminating and winding an inner core and a winding in a cylindrical case are accommodated concentrically, and between the two windings and the outer winding. An ignition coil in which an insulating resin is filled and hardened on an outer peripheral side of a wire body, comprising: a film covering an outer peripheral portion of the outer winding body. 2. The ignition coil according to claim 1, wherein at least one surface of the film has releasability from the outer winding body or the insulating resin that contacts the surface. 3. An inner winding and an outer winding formed by laminating and winding an inner core and a winding in a cylindrical case are accommodated concentrically, and between the two windings and the outer winding. In an ignition coil in which an insulating resin is filled and hardened on an outer peripheral side of a wire, at least one surface of the ignition coil has a film releasable from the outer winding and the insulating resin interposed between winding layers of the outer winding. An ignition coil, characterized in that: 4. An inner core and an outer coil formed by laminating and winding an inner core and a coil in a cylindrical case are accommodated concentrically, and between the two coils and the outer coil. In an ignition coil in which an insulating resin is filled and hardened on the outer peripheral side of a wire, at least one outer surface of the outer coil is in contact with the same surface or the outer coil is a film having a peeling property with respect to the insulating resin An inner peripheral portion of the ignition coil is coated. 5. An inner core and an outer coil formed by laminating and winding an inner core and a coil in a cylindrical case, and a cylindrical outer core are housed concentrically, and are provided between the two coils. And an outer periphery of the outer winding body which is filled with an insulating resin and cured, wherein at least one surface of the outer core is in contact with the same surface or the outer winding body is formed of a film having releasability from the outer winding body. An inner peripheral portion of the ignition coil is coated. 6. An inner core and an outer winding formed by laminating and winding an inner core and a winding in a cylindrical case are accommodated concentrically, and between the two windings and the outer winding. In the ignition coil in which the insulating resin is filled and hardened on the outer peripheral side of the wire, at least one of the insulating resin located between the two winding bodies and the insulating resin located on the outer peripheral side of the outer winding body is provided. An ignition coil, wherein a film releasable from the insulating resin is concentrically arranged on at least one surface thereof.