JP2006108632A - Ignition coil and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil in which an insulating sheet is made hard to separate, the winding condition of an insulating sheet on a center core is readily maintained, and increase in the winding number of the insulating sheet is inhibited. <P>SOLUTION: The ignition coil comprises a bar-shaped center core 3 and a cylindrical part, provided with a primary and secondary coils wound concentrically around the center core 3. The insulating sheet 4 is wound on the outer peripheral surface 301 of the center core 3, and the space between the insulating sheet 4 and the cylinder is filled with an insulating resin. The insulating sheet 4 comprises a resin film layer, made of synthetic resin and a bonding layer arranged on the rear surface of the resin film layer. The insulating sheet 4 has a sheet width w 0.8-1.2 times that of the length x in the axial direction of the center core 3, and a winding-finish end 42 is inclined with respect to the axial direction L of the center core 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ignition coil for generating a spark from a spark plug.

  In an ignition coil used for generating a spark in a spark plug in an engine of a vehicle or the like, thermal stress relaxation is applied to the outer peripheral surface of a central core disposed on the inner peripheral side of a coil portion including a primary coil and a secondary coil. An insulating sheet as a material is wound around. With this insulating sheet, the insulating resin filled between the coil portion and the central core is prevented from being damaged by the generation of thermal stress due to repeated heating and cooling cycles in the engine.

As an ignition coil formed by winding such an insulating sheet around a central core, for example, there are those disclosed in Patent Documents 1 to 3.
In Patent Document 1, an insulating sheet is interposed between a central iron core (central core) and a secondary winding core (spool around which a secondary coil is wound). Even if bubbles or the like are generated in the secondary winding core formed using the thermoplastic resin, the insulating sheet ensures electrical insulation between the central iron core and the secondary coil.
Moreover, in patent document 2, the thickness of the insulating sheet as a thermal stress relaxation member wound around the central core is set to an appropriate thickness. This prevents cracks and the like from occurring due to thermal stress in the resin insulating material filled between the central core and the cylindrical spool.

  Moreover, in patent document 3, a covering member (gel) etc. is applied to the full length of the winding end of the insulating sheet as a thermal stress relaxation member wound around the outer peripheral surface of the central core, and the winding end is the central core. To prevent it from peeling off and protruding in the diameter-enlarging direction. As a result, the winding end protrudes, stress concentration occurs at the winding end, and cracks or the like occur due to thermal stress in the resin insulating material filled between the central core and the coil portion. Is prevented.

  However, as shown in FIGS. 17 and 18, in the conventional ignition coil, a rectangular insulating sheet 94 is wound in parallel to the axial direction L of the central core 3, and the winding end 942 of the insulating sheet 94 is wound. Is formed in parallel with the axial direction L of the central core 3. Therefore, the insulating sheet 94 after winding is easily peeled off, and as shown in Patent Document 3, a covering member (gel) is applied to the entire length of the winding end (winding end) 942 of the insulating sheet 94. It becomes necessary to do.

JP-A-10-92670 JP 2004-14548 A JP 2004-111714 A

  The present invention has been made in view of such conventional problems, and it is possible to make it difficult to peel off the insulating sheet, to easily maintain the winding state of the insulating sheet around the central core, and to provide insulation. It is an object of the present invention to provide an ignition coil that can suppress an increase in the number of times of winding a sheet.

1st invention has a rod-shaped center core and the cylindrical part provided with the primary coil and the secondary coil which were wound concentrically around the center core, and the insulating sheet is provided on the outer peripheral surface of the center core. In an ignition coil formed by filling an insulating resin between the insulating sheet and the cylindrical portion,
The insulating sheet comprises a resin film layer made of a synthetic resin and an adhesive layer disposed on the back surface of the resin film layer, and has a sheet width 0.8 to 1.2 times the axial length of the central core. And an end of winding thereof has an inclined portion inclined with respect to the axial direction of the central core (claim 1).

The ignition coil of the present invention is devised to make it difficult to peel off the insulating sheet by providing an inclined portion at the winding end of the insulating sheet wound around the outer peripheral surface of the central core.
That is, when an insulating sheet having a sheet width 0.8 to 1.2 times the axial length of the central core is wrapped around and bonded to the outer peripheral surface of the central core, the winding end of the insulating sheet is The inclined portion is inclined with respect to the axial direction of the central core.

Therefore, in the insulating sheet wound around the central core, even if the force that tries to restore the elastic deformation when wound around the central core acts as the force that tries to peel off the winding end of the insulating sheet, this peeling The force to do so can be reduced. Thereby, it is possible to make it difficult to peel off the winding end of the insulating sheet.
In addition, since the insulating sheet can be made difficult to peel off, it is not necessary to perform fixing separately from the bonding of the insulating sheet over the entire length of the winding end of the insulating sheet, and the insulating sheet is wound around the central core. Can be easily maintained.

The sheet width of the insulating sheet is 0.8 to 1.2 times the axial length of the central core. Therefore, just aligning the width direction of the insulating sheet with the axial direction of the central core and winding the insulating sheet parallel to the circumferential direction of the central core can cover most of the outer peripheral surface of the central core. The increase can be suppressed.
In addition, when the sheet | seat width of an insulating sheet is shorter than the axial direction length of a center core, the part of the outer peripheral surface which is not winding an insulating sheet can be covered with another structural member, for example. Further, when the sheet width of the insulating sheet is longer than the axial length of the central core, the long axial surplus portion can be folded back to the axial end surface of the central core.

  Therefore, according to the ignition coil of the present invention, it is possible to make it difficult to peel off the insulating sheet, to easily maintain the winding state of the insulating sheet around the central core, and to reduce the number of times the insulating sheet is wound. The increase can be suppressed.

The second invention has a rod-shaped central core and a cylindrical portion having a primary coil and a secondary coil concentrically wound around the central core, and an insulating sheet is provided on the outer peripheral surface of the central core. In an ignition coil formed by filling an insulating resin between the insulating sheet and the cylindrical portion,
The insulating sheet includes a resin film layer made of a synthetic resin and an adhesive layer disposed on the back surface of the resin film layer, and the axial length of the central core is 0 before being wound around the central core. .8 to 1.2 times the sheet width, a pair of axial ends positioned in the width direction are parallel to each other, and the winding end when winding around the central core is the width direction The ignition coil has an inclined portion that is inclined with respect to the ignition coil.

The ignition coil of the present invention is also devised to make it difficult to peel off the insulating sheet by providing an inclined portion at the winding end of the insulating sheet wound around the outer peripheral surface of the central core.
In the insulating sheet according to the present invention, the pair of axial ends positioned in the width direction are parallel to each other in a state before being wound around the central core, and are inclined at the end portion positioned at the winding end when being wound around the central core. Has a part. Therefore, it is easy to wind the insulating sheet around the central core, and after winding the insulating sheet around the central core, it is easy to dispose the inclined portion at the end of the winding with respect to the axial direction of the central core. is there.
In addition, the operational effects of the present invention are the same as those of the first invention.

  Therefore, even with the ignition coil of the present invention, the insulating sheet can be made difficult to peel off, the state of winding the insulating sheet around the central core can be easily maintained, and the number of times the insulating sheet is wound is increased. This can be suppressed.

3rd invention has a cylindrical center part provided with the rod-shaped center core and the primary coil and the secondary coil which were wound concentrically around the center core, and the insulating sheet is provided on the outer peripheral surface of the center core. In the method of manufacturing an ignition coil, in which an insulating resin is filled between the insulating sheet and the cylindrical portion.
An inclined portion that has a sheet width that is 0.8 to 1.2 times the axial length of the central core and that is inclined with respect to the width direction at at least one end in the winding direction orthogonal to the width direction. A sheet forming step of forming the provided insulating sheet;
A winding step in which the width direction of the insulating sheet is aligned with the axial direction of the central core, the insulating sheet is wound around the outer peripheral surface of the central core, and an end portion provided with the inclined portion is positioned at the winding end; The present invention is directed to a method for manufacturing an ignition coil (claim 11).

The method for manufacturing an ignition coil according to the present invention is a method for manufacturing an ignition coil that exhibits the above-described excellent effects.
That is, in the present invention, in the sheet forming step, an insulating sheet having the predetermined sheet width and having an inclined portion inclined with respect to the width direction at at least one end in the winding direction is formed. To do.

And in the said winding process, when an insulating sheet is wound around the outer peripheral surface of a center core, the edge part which provided the said inclination part is located in the winding end end.
Therefore, the ignition coil manufactured by performing each of the above steps can exhibit excellent operational effects similar to those of the invention of the ignition coil.
Therefore, according to the manufacturing method of the present invention, the insulating sheet can be made difficult to peel off, the state of winding the insulating sheet around the central core can be easily maintained, and the number of times of winding the insulating sheet can be reduced. An ignition coil that can suppress the increase can be manufactured.

A preferred embodiment of the first to third inventions described above will be described.
In the first to third inventions, when the sheet width of the insulating sheet is less than 0.8 times the axial length of the central core, the portion of the outer peripheral surface of the central core around which the insulating sheet is not wound is It becomes wide and difficult to cover with another component member or the like. On the other hand, when the sheet width of the insulating sheet exceeds 1.2 times the axial length of the central core, the portion of the insulating sheet protruding from the axial end surface of the central core is used as the axial end surface of the central core. It becomes difficult to wrap.

  Moreover, it is most preferable that the inclined portion at the winding end of the insulating sheet is formed over the entire length of the winding end. In addition, the inclined portion at the winding end can be formed in an area of at least 50% or more in the width direction of the insulating sheet. That is, the insulating sheet can be made difficult to peel off from the central core by forming the inclined portion at the end of winding at a minimum in a region of 50% in the width direction of the insulating sheet.

In the second aspect of the invention, it is preferable that the insulating sheet is wound around the central core with its width direction parallel to the axial direction of the central core.
In this case, it is easy to stably wind the insulating sheet around the central core.

In the first to third inventions, the central core is preferably formed by laminating a plurality of steel plates in the radial direction (claims 4 and 12).
When the central core is formed by laminating a plurality of steel plates in the radial direction, a step space is formed in the axial direction of the central core along the axial direction of the portion where the steel plates and the steel plates overlap. At this time, if the winding end end of the insulating sheet is positioned along the step space, the winding end end is easily displaced in the radial direction via the step space, and is easily peeled off.
On the other hand, as described above, at least a part of the winding end of the insulating sheet is inclined with respect to the axial direction of the central core, so that at least a part of the winding end of the insulating sheet is relative to the step space. Can be tilted. Thereby, even when the central core is formed by laminating a plurality of steel plates in the radial direction, it is possible to make it difficult to peel off the winding end of the insulating sheet.

  In the first and second aspects of the invention, the winding end has an acute corner sheet corner, and the acute corner sheet corner is fixed to prevent peeling. (Claim 5). In the third aspect of the invention, after performing the winding step, it is preferable to perform a fixing step for fixing the sharp corners formed at the end of winding to prevent peeling ( Claim 13).

  The acute corner sheet corner has a small adhesion area and is more easily peeled off than the obtuse sheet corner. Therefore, the fixing can be performed to prevent peeling. Also in this case, the fixing for preventing peeling may be performed only on a part of the end of winding of the insulating sheet, and the state in which the insulating sheet is wound around the central core can be easily maintained.

  In the first and second inventions, the inclined portion at the winding end end preferably has an inclination angle of 5 to 60 ° with respect to the axial direction of the central core. . 3rd invention WHEREIN: In the said sheet | seat formation process, the inclination part of the one edge part in the said winding direction of the said insulating sheet is made to incline with the inclination angle of 5-60 degrees with respect to the width direction of the said insulating sheet. (Claim 14).

In these cases, the inclination angle of the inclined portion at the end of winding is appropriate, and the excellent operational effects of the ignition coil can be obtained more effectively.
Moreover, when the inclination angle of the seat inclined end portion is less than 5 °, the inclination angle is so loose that there is a possibility that the excellent effect of the ignition coil cannot be obtained. On the other hand, when the inclination angle of the sheet inclined end exceeds 60 °, the inclination angle becomes too steep, and the number of times of winding the insulating sheet may increase.

In the first and second inventions, it is preferable that the entire end of the winding end be inclined in the same direction. In the third aspect of the invention, in the sheet forming step, it is preferable that one end portion of the insulating sheet in the winding direction is inclined so that the entire inclined portion is directed in the same direction. .
In these cases, it is easy to form the winding end, and the winding end can be made difficult to peel off by a simple shape insulating sheet. Further, the inclined portion at the winding end end is not necessarily inclined linearly, and may be inclined in an arc shape. For example, the inclination angle of the winding end with respect to the axial direction of the central core can be made smaller as it goes toward the acute corner portion.

In the first and second aspects of the invention, it is preferable that the winding end end has a mountain shape or a valley shape, with the inclination direction of the inclined portion reversed in the middle. 3rd invention WHEREIN: In the said sheet | seat formation process, one edge part in the said winding direction of the said insulating sheet reverses the inclination direction of the inclination part in the middle, and forms in a mountain shape or a trough shape. (Claim 16).
The end of the winding may be inclined not only in the entire inclined part in the same direction but also in a mountain shape or a valley shape as in these cases. Also in these cases, the winding end can be made difficult to peel off.
Further, one or more inclined portions of the mountain shape or valley shape can be formed at the winding end.

In the first and second inventions, the insulating sheet preferably has an axial surplus portion in a wound state folded back to an axial end surface of the central core. In the third invention, in the winding step, the insulating sheet is wound so as to protrude from the axial end surface of the central core, and the axial surplus portion in the winding state is folded back to the axial end surface of the central core. (Claim 17).
In these cases, a part of the winding end end of the insulating sheet can be folded back to the axial end surface of the central core so that the winding end end of the insulating sheet is not peeled off.

In the first to third aspects of the invention, both end portions of the central core in the axial direction are formed by arranging magnets, and the insulating sheet includes the axial length of the pair of magnets. The sheet preferably has a sheet width 0.8 to 1.2 times the axial length of the central core.
In this case, it is possible to make it difficult to peel off the winding end of the insulating sheet with respect to the central core formed by disposing magnets at both ends in the axial direction.

Embodiments of the ignition coil and the manufacturing method thereof according to the present invention will be described below with reference to the drawings.
(Example 1)
As shown in FIG. 1, the ignition coil 1 of this example includes a rod-shaped central core 3, and a cylindrical portion 2 including a primary coil 21 and a secondary coil 22 that are concentrically wound around the central core 3. The insulating sheet 4 is wound around the outer peripheral surface 301 of the central core 3, and the insulating resin 5 is filled between the insulating sheet 4 and the cylindrical portion 2.

As shown in FIG. 5, the insulating sheet 4 includes a resin film layer 45 made of a synthetic resin and an adhesive layer (adhesive layer) 46 disposed on the back surface of the resin film layer 45. Moreover, the insulating sheet 4 has a sheet width w that is 0.8 to 1.2 times the axial length x of the central core 3 as shown in FIGS. Inclined with respect to the axial direction L of the central core 3.
This will be described in detail below.

As shown in FIG. 1, the ignition coil 1 of this example is of a stick type that is used by inserting the cylindrical portion 2 into a plug hole of an engine.
The cylindrical part 2 is formed by inserting an outer peripheral core 24, a primary coil 21, a secondary coil 22, and a central core 3 into a coil case 20. That is, the primary coil 21 is formed by winding a wire with an insulation coating in a cylindrical shape, and the secondary coil 22 is wound more on the outer peripheral surface of the cylindrical secondary spool 221 than the primary coil 21. It is made by winding a wire with insulation coating. The secondary coil 22 is inserted on the inner peripheral side of the primary coil 21, and a rod-shaped metal central core 3 is disposed on the inner peripheral side of the secondary coil 22. The primary coil 21 is inserted into a cylindrical outer core 24, and the outer core 24 is inserted into the coil case 20.

The magnetic flux generated by passing a current through the primary coil 21 can be increased by passing through the central core 3 and the outer core 24. In addition, elastic members 321 are disposed at both axial end portions 32 of the central core 3.
It should be noted that permanent magnets for further increasing the magnetic flux generated by the primary coil 21 may be disposed at both axial ends 32 of the central core 3 instead of the elastic member 321.

In addition, the primary coil 21 of this example was formed in a cylindrical shape by winding an insulation-coated wire in a cylindrical shape and then bonding the wound wires together with a fusing agent or the like. On the other hand, the primary coil 21 can also be formed by winding an insulating coated wire around the outer peripheral surface of a cylindrical primary spool.
Insulation resin 5 is filled in each gap 29 between the central core 3 and the secondary coil 22, between the secondary coil 22 and the primary coil 21, and between the primary coil 21 and the outer core 24. Has been.

  Moreover, the cylindrical part 2 has the plug attachment port 26 for attaching a spark plug to the axial direction front-end | tip part 201 inserted and arrange | positioned in the plug hole of an engine. A high voltage terminal 27 that is electrically connected to one end (high voltage side end) of the secondary coil 22 and a coil spring 28 that contacts the high voltage terminal 27 are disposed in the plug attachment port 26. Further, the cylindrical portion 2 has a flange portion 255 protruding radially outward at an axial base end portion 202 opposite to the axial tip portion 201, and the flange portion 255 is screwed into the engine. Bolt insertion holes 256 for inserting the bolts to be combined are formed.

  In addition, an igniter disposition recess 25 for disposing an igniter 251 that supplies power to the primary coil 21 is formed in the axial base end portion 202 of the coil case 20. The igniter arrangement recess 25 is filled with the same insulating resin 5 as the insulating resin 5 filled in the gaps 29 with the igniter 251 provided. The igniter 251 includes a power control circuit that uses a switching element or the like that operates in response to a signal from an ECU (electronic control unit).

  When a spark generation signal is transmitted from the ECU to the igniter 251, a switching element or the like in the igniter 251 operates to cause a current to flow through the primary coil 21, and accordingly, an induced electromotive force due to electromagnetic induction in the secondary coil 22. (Back electromotive force) is generated, and a spark can be generated from the spark plug.

As shown in FIGS. 4 and 5, the central core 3 of the present example has a plurality of steel plates 31 arranged in the radial direction in order to suppress the generation of eddy currents due to the formation of magnetic flux generated by passing a current through the primary coil 21. Laminated.
The resin film layer 45 in the insulating sheet 4 of this example is made of polyethylene terephthalate (PET), and the adhesive layer 46 in the insulating sheet 4 is made of an acrylic adhesive (pressure-sensitive adhesive).
The insulating resin 5 in this example is made of an epoxy resin.

As shown in FIGS. 2 and 4, the winding end 42 in the insulating sheet 4 of this example is formed to be inclined at a predetermined inclination angle θ with respect to the width direction W of the insulating sheet 4. The winding end 42 has an inclination angle θ of 5 to 60 ° with respect to the axial direction L of the central core 3.
Further, as shown in FIG. 6, the insulating sheet 4 of this example is obtained by mass-producing the same shape by repeatedly cutting a long insulating sheet material 40 wound in a roll shape at a predetermined length. Is.

As shown in FIG. 2, the four corners of the insulating sheet 4 are not right angles, but both end portions 40 in the winding direction (length direction) D of the insulating sheet 4, that is, the winding start end 41 and the winding end end 42. Have the same inclination angle θ.
Moreover, the insulating sheet 4 of this example has the same length of both end portions 43 in the width direction W, and the same length and inclination angle θ of both end portions 40 in the winding direction (length direction) D. , Has a parallelogram shape.

  As shown in FIG. 2, the winding start end 41 and the winding end end 42 of the insulating sheet 4 have acute corner sheet corner portions 411 and 421 and obtuse corner corner portions 412 and 422, respectively. The insulating sheet 4 starts to be wound around the central core 3 from the acute-angled sheet corner 411 at the winding start end 41 and ends at the acute-angled sheet corner 421 at the winding end 42. As shown in FIG. 3, the acute corner sheet corner 421 at the winding end 42 is welded, crimped, or heat-caulked, and fixed to prevent peeling 49.

The resin film layer 45 in the insulating sheet 4 is preferably made of a material having a linear expansion coefficient of 25 × 10 ⁻⁶ / ° C. or less. Moreover, it is preferable that the winding thickness t of the resin film layer 45 in the state wound around the outer peripheral surface 301 of the center core 3 is 0.1 mm or more.
The insulating sheet 4 is preferably wound twice or more at each winding position in the axial direction L of the central core 3.

  Further, for example, when the insulating sheet 4 having a material thickness of the resin film layer 45 before being wound around the outer peripheral surface 301 of the central core 3 is 25 μm, the insulating sheet 4 is formed on the outer peripheral surface 301 of the central core 3. It is possible to wind four or more times at each winding position. In addition, since assembly | attachment property will deteriorate when the number of winding increases, it is preferable that the number of winding of the insulating sheet 4 shall be 10 or less.

  As shown in FIG. 1, one axial end face 32 of the central core 3 of this example is inserted and disposed in a core holding recess 253 formed upright from a holder 252 in the igniter 251. Therefore, the insulating sheet 4 of this example is not wound around the outer peripheral surface 301 of the central core 3 in the vicinity of the one axial end surface 32. An elastic member 321 disposed on one axial end surface 32 of the central core 3 is also inserted and disposed in the core holding recess 253.

  In addition, the insulating sheet 4 is wound around the outer peripheral surface 301 of the central core 3 in a state where a cylindrical elastic member 321 or a permanent magnet is disposed on the axial end surface 32 of the central core 3 and also on the outer peripheral surface of the elastic member 321. Can be wound. The insulating sheet 4 of this example is wound around the outer peripheral surface 301 of the center core 3 and is wound around the elastic member 321 disposed on the other axial end surface 32 of the center core 3.

Next, a method for manufacturing the ignition coil 1 will be described.
In this example, the ignition coil 1 is manufactured by performing the following sheet forming process, winding process, fixing process, assembling process, and resin filling process.
First, as shown in FIG. 6, in the sheet forming step, the sheet has a sheet width w that is 0.8 to 1.2 times the axial length x of the central core 3, and is formed in a long shape wound in a roll shape. The insulating sheet material 40 is cut at a predetermined length to form the insulating sheet 4. Further, the insulating sheet material 40 is temporarily wound with a portion of the resin film layer 45 wound earlier and a portion of the adhesive layer 46 wound later, and is wound in a roll shape.

At this time, the insulating sheet material 40 is cut by the cutter 6 inclined with respect to the width direction W orthogonal to the winding direction D. Then, the cut end portions 40 on both sides of the insulating sheet 4 formed by cutting are formed so as to be inclined by 5 to 60 ° with respect to the width direction W of the insulating sheet material 40.
Thus, the insulating sheet 4 has a sheet width w that is 0.8 to 1.2 times the axial length x of the central core 3 and is inclined at both ends 40 in the winding direction D perpendicular to the width direction W. Is formed.

Next, as shown in FIG. 2, in the winding step, the insulating sheet 4 is wound around the outer peripheral surface 301 of the central core 3 with the width direction W of the insulating sheet 4 aligned with the axial direction L of the central core 3. At this time, the insulating sheet 4 is wound in parallel with the circumferential direction R of the central core 3 in a state where the width direction W thereof is parallel to the axial direction L of the central core 3.
Then, the insulating sheet 4 has the adhesive layer 46 facing the outer peripheral surface 301 of the central core 3, and one of the inclined cut end portions 40 is used as a winding start end 41, and the sheet has an acute angle at the winding start end 41. Winding around the central core 3 from the corner 411 starts.

And the acute sheet | seat corner | angular part 411 in the winding start end 41 is covered by the part of the insulating sheet 4 wound after. Further, the insulating sheet 4 is wound by being bonded to the resin film layer 45 of the part wound earlier with the adhesive layer 46 of the part wound later.
Thus, as shown in FIG. 3, the insulating sheet 4 finishes winding at the acute-angled sheet corner 421 at the winding end 42 with the inclined cut end 40 as the winding end 42.

Next, as shown in FIG. 3, in the fixing step, fixing 49 for preventing peeling is performed by welding, press-bonding, or heat caulking, etc., to the acute-angled sheet corner portion 421 formed at the winding end 42. . As a result, the insulating sheet 4 can be prevented from being peeled off only by fixing 49 to the acute-angled sheet corner 421 without performing fixing 49 over the entire length of the winding end 42.
Note that an obtuse angled sheet corner 422 is also located at the winding end 42 of the insulating sheet 4. However, the obtuse angled sheet angle 422 is considered to be difficult to peel off, and the fixing 49 for preventing the peeling is performed. Absent.

Next, in the assembly process, the primary coil 21, the secondary coil 22, the central core 3, the outer core 24, the igniter 251, and the like are assembled in the coil case 20.
Thereafter, in the resin filling step, the gap 29 in the cylindrical portion 2 and the igniter arrangement recess 25 are filled with an epoxy resin as the insulating resin 5, and the components are integrated to manufacture the ignition coil 1.
In this resin filling process, the insulating resin 5 is also filled between the insulating sheet 4 wound around the outer peripheral surface 301 of the central core 3 and the secondary spool 221 of the secondary coil 22 positioned on the outer peripheral side thereof. Is done.

In the ignition coil 1 of the present example, the winding end end 42 of the insulating sheet 4 wound around the outer peripheral surface 301 of the central core 3 is inclined with respect to the axial direction L of the central core 3 over the entire length.
For this reason, in the insulating sheet 4 wound around the central core 3, even if a force that tries to restore elastic deformation when wound around the central core 3 acts as a force that tries to peel off the insulating sheet 4, this insulation The force for peeling off the sheet 4 can be reduced.

Further, the force for peeling off the insulating sheet 4 concentrates on the acute sheet corner portion 421 at the winding end end 42. Therefore, the fixing 49 for preventing peeling is applied to the acute sheet corner portion 421 at the winding end 42 so that the whole winding end 42 can be prevented from peeling off.
Further, the fixing 49 does not need to be performed over the entire length of the winding end end 42 of the insulating sheet 4, and the state in which the insulating sheet 4 is wound around the central core 3 can be easily maintained.

In addition, the insulating sheet 4 (see FIG. 4) of the present example having the inclined winding end 42 is a conventional insulating sheet 94 having a winding end 942 parallel to the axial direction L of the central core 3 (see FIG. 18). The effect that is less likely to be peeled off can also be explained as follows.
That is, as shown in FIG. 5, the central core 3 is formed by laminating a plurality of steel plates 31 in the radial direction in order to suppress the generation of eddy currents. Therefore, a step space 311 formed between the steel plates 31 is formed on the outer peripheral surface 301 of the central core 3 in the axial direction L of the central core 3.

  As shown in FIGS. 17 and 18, when a conventional insulating sheet 94 having a winding end 942 parallel to the axial direction L of the central core 3 is wound around the central core 3, the axial direction of the central core 3. The formation direction of the step space 311 toward L and the formation direction of the winding end 42 of the insulating sheet 94 positioned in the axial direction L of the central core 3 often coincide. In this case, due to the coincidence between the formation direction of the step space 311 and the formation direction of the winding end end 42, the winding end end 42 is easily displaced in the radial direction via the step space 311 and the insulating sheet 4 is easily peeled off. End up.

  On the other hand, as shown in FIGS. 2 and 4, when the insulating sheet 4 having the inclined winding end 42 of this example is wound around the central core 3, the winding end 42 is in the step space 311. And can be tilted. Therefore, according to the insulating sheet 4 of this example, even when the central core 3 is formed by laminating a plurality of steel plates 31 in the radial direction, the winding end 42 of the insulating sheet 4 can be hardly peeled off.

Further, as shown in FIG. 5, the insulating resin 5 filled between the insulating sheet 4 wound around the outer peripheral surface 301 of the central core 3 and the secondary spool 221 of the secondary coil 22 is formed in a cylindrical shape. In addition, a resin step 51 is formed at a portion on the inner peripheral side adjacent to the winding end 42 of the insulating sheet 4.
When the conventional insulating sheet 94 is wound around the central core 3, the resin stepped portion 51 has a shaft end of the cylindrical insulating resin 5 by a winding end 942 parallel to the axial direction L of the central core 3. It is formed parallel to the direction L (see FIG. 18).

  In the ignition coil using the conventional insulating sheet 94, when the cylindrical insulating resin 5 contracts in the radial direction due to thermal stress when the ignition coil is cooled after heating the engine, the axial direction L Stress concentration occurs in the resin step portion 51 parallel to. That is, this stress concentration is concentrated at one place in the circumferential direction R of the central core 3. Therefore, in the conventional ignition coil, the cylindrical insulating resin 5 may be broken at the resin step portion 51.

On the other hand, when the insulating sheet 4 of the present example is wound around the central core 3, the resin stepped portion 51 is made to be the axis of the central core 3 by the winding end end 42 inclined in the axial direction L of the central core 3. Inclined in the direction L (see FIG. 4).
Therefore, in the ignition coil 1 using the insulating sheet 4 of this example, when the cylindrical insulating resin 5 contracts in the radial direction due to thermal stress when the ignition coil 1 is cooled after the engine is heated, the resin The stress concentration generated in the stepped portion 51 is not concentrated in one place in the circumferential direction R of the central core 3 but is distributed in the circumferential direction R of the central core 3. Therefore, according to the ignition coil 1 of this example, the cylindrical insulating resin 5 can be made difficult to break even if stress concentration acts on the resin step portion 51.

  Further, as described above, the sheet width w of the insulating sheet 4 is 0.8 to 1.2 times the axial length x of the central core 3. Therefore, the entire outer peripheral surface 301 of the central core 3 is covered only by aligning the width direction W of the insulating sheet 4 with the axial direction L of the central core 3 and winding the insulating sheet 4 in parallel with the circumferential direction R of the central core 3. It is possible to suppress the increase in the number of times the insulating sheet 4 is wound.

  Therefore, according to the ignition coil 1 of this example, the insulating sheet 4 can be made difficult to peel off, the state of winding of the insulating sheet 4 around the central core 3 can be easily maintained, and the insulating sheet It can suppress that the frequency | count of winding 4 is increased.

(Example 2)
In this example, as shown in FIGS. 7 and 8, the ignition coil 1 including the central core 3 around which the insulating sheet 4 having the winding end 42 inclined in a valley shape is wound is shown.
The valley-shaped winding end 42 in this example is formed by reversing the inclination direction halfway.
Moreover, the insulating sheet 4 of this example is mass-produced by repeatedly cutting the long insulating sheet material 40 with the cutter 6 in the same manner as shown in Example 1 above. And a mountain-shaped winding start end 41 along the shape of the valley-shaped winding end end 42.

The inclination angle θ of the valley-shaped winding end end 42 in this example with respect to the axial direction L of the central core 3 can be set to 5 to 60 °.
Further, the winding end end 42 in this example has a single valley shape, and has acute sheet corner portions 421 at both ends in the axial direction L of the central core 3. The insulating sheet 4 of this example is prevented from peeling by performing the above-described peeling preventing fixing 49 on two acute-angled sheet corners 421.

As shown in FIGS. 9 and 10, the insulating sheet 4 can also be formed by forming the winding end end 42 in an obtuse angle mountain shape and the winding start end 41 in an obtuse angle valley shape. In this case, it is necessary to start winding the insulating sheet 4 from the two acute-angled sheet corners 421, and this winding is difficult to start, while only the obtuse-angled sheet corner 422 is located at the winding end end 42. The fixing 49 can be omitted.
Also in this example, the other parts are the same as those in the first embodiment, and the same effects as those in the first embodiment can be obtained.

(Example 3)
In this example, as shown in FIGS. 11 to 13, in the insulating sheet 4 wound around the central core 3, the axial excess portion (protruding end) 44 protruding from the axial end surface 32 of the central core 3 is replaced with the central core 3. It is an example which shows the ignition coil 1 folded back by the axial direction end surface 32.
In this example, as shown in FIGS. 11 and 12, a folding jig 7 for folding the axial surplus portion 44 of the insulating sheet 4 to the axial end surface 32 of the central core 3 is used. The folding jig 7 includes a circular recess 71 having an inner diameter slightly larger than the outer diameter of the axial end surface 32 of the central core 3. The circular recess 71 has a bottom surface 711 and an inclined inner wall surface 712 formed to be inclined from the outer periphery of the bottom surface 711 in order to fold back the axial surplus portion 44 of the insulating sheet 4.

In this example, as shown in FIG. 11, when the insulating sheet 4 is wound around the central core 3, a part of the insulating sheet 4 protrudes from the axial end surface 32 of the central core 3 to form the axial surplus portion 44. . At this time, a part of the acute-angled sheet corner portion 421 at the winding end end 42 of the insulating sheet 4 protrudes from the axial end surface 32 of the central core 3.
In this example, the fixing 49 for preventing peeling of the acute-angle sheet corner 421 at the winding end 42 is used to fix the acute-angle sheet corner 421 to the axial end face 32 of the central core 3 by the folding jig 7. Do by wrapping.

That is, as shown in FIG. 11, after the insulating sheet 4 is wound around the central core 3, the folding jig is placed on the axial surplus portion 44 that protrudes from the axial end surface 32 of the central core 3. Move 7 closer. At this time, as shown in FIG. 12, the axial surplus portion 44 comes into contact with the inclined inner wall surface 712 in the circular recess 71 of the folding jig 7 and is bent toward the center side. As shown in FIG. 13, the axial surplus portion 44 abuts on the bottom surface 711 of the circular recess 71 and is bonded to the axial end surface 32 of the central core 3.
In this way, the axial surplus portion 44 of the insulating sheet 4 can be folded back to the axial end surface 32 of the central core 3 to fix the winding end 42 of the insulating sheet 4 49.
Also in this example, it is possible to prevent the winding end 42 of the insulating sheet 4 from peeling off.

In addition, it is preferable that the length x1 of the axial surplus portion 44 of the insulating sheet 4 protruding from the axial end surface 32 of the central core 3 is smaller than the radius of the central core 3. In this case, the axial surplus portions 44 folded back on the axial end surface 32 of the central core 3 are not overlapped and bonded more than necessary, and the axial surplus portion 44 folded back to the axial end surface 32 of the central core 3. Can be shaped.
Further, when the axial surplus portion 44 is bonded to the axial end surface 32 of the central core 3, the folding jig 7 performs ultrasonic welding or the like on the axial surplus portion 44 to further insulate. It is also possible to prevent the winding end 42 of the sheet 4 from peeling off.
Also in this example, the other parts are the same as in the first and second embodiments, and the same effects as those in the first and second embodiments can be obtained.

(Example 4)
In this example, as shown in FIG. 14, both end portions in the axial direction of the central core 3A are formed by arranging permanent magnets 33 respectively.
The insulating sheet 4 of this example has a sheet width w that is 0.8 to 1.2 times the axial length x of the central core 3A including the axial length of the pair of permanent magnets 33. Yes.

In this example, the winding end 42 of the insulating sheet 4 can be made difficult to peel off from the central core 3A in which the permanent magnets 33 are disposed at both ends in the axial direction.
Also in this example, the others are the same as those in Examples 1 to 3, and the same effects as those in Examples 1 to 3 can be obtained.

  Moreover, as shown in FIG. 15, in the said Examples 1-4, the inclination part in the winding end end 42 of the insulating sheet 4 does not necessarily need to form over the full length of the winding end end 42, for example, the said insulating sheet 4 can be formed in a region of 50% or more in the width direction W (a region of w / 2 or more in the figure). Even in this case, the insulating sheet 4 can be made difficult to peel off from the central core 3.

  Further, as shown in FIG. 16, in Examples 1 to 4, the winding start end 41 of the insulating tape 4 is formed at a right angle to the axial direction L of the central core 3 (the width direction W of the insulating sheet 4). On the other hand, the winding end 42 can be formed to be inclined with respect to the axial direction L of the central core 3 (the width direction W of the insulating sheet 4).

Moreover, in the said Examples 1-4, the inclination part in the winding end 42 of the insulating tape 4 does not necessarily incline and form in a linear form, but can also incline and form in a curvilinear form. In this case, the inclined portion at the winding end end 42 can be not only entirely curved, but also a part of the linear inclined portion can be curved.
Further, the inclined portion at the winding start end 41 can be similarly formed in a curved shape.

Sectional explanatory drawing which shows the ignition coil in Example 1. FIG. The perspective explanatory view which shows the state which winds the insulating sheet in the center core in Example 1. FIG. FIG. 3 is a perspective explanatory view showing a state in which the insulating sheet is wound around the central core in Example 1. The perspective explanatory view which expands and shows the winding end end of the insulation sheet in the state wound around the central core in Example 1. Sectional explanatory drawing which expands and shows the periphery of the center core arrange | positioned in the ignition coil in Example 1, and an insulating sheet. The perspective explanatory view which shows the state which cuts with the cutter in Example 1 and forms the insulating sheet. The perspective explanatory drawing which shows the state which winds an insulating sheet in center core in Example 2. FIG. The perspective explanatory drawing which shows the state which wound the insulating sheet in the center core in Example 2. FIG. The perspective explanatory view which shows the state which winds the other insulating sheet in Example 2 around a center core. The perspective explanatory view which shows the state which wound the other insulating sheet in Example 2 around the center core. The perspective explanatory drawing which shows the center core of the state which wound the insulating sheet in Example 3, and a folding jig | tool. Cross-sectional explanatory drawing which shows the state which is returning the protrusion edge part of an insulating sheet to the axial direction end surface of a center core with the folding jig | tool in Example 3. FIG. The perspective explanatory view which shows the state which turned the protrusion edge part of the insulating sheet in Example 3 in the axial direction end surface of the center core. Sectional explanatory drawing which shows the ignition coil in Example 4. FIG. The perspective explanatory view which shows the state which winds the other insulating sheet in Examples 1-4 in the center core. Explanatory perspective drawing which shows the state which winds the other insulating sheet in Examples 1-4 in the center core. The perspective explanatory view which shows the state which winds an insulating sheet in a center core in a prior art example. The perspective explanatory drawing which expands and shows the winding end end of the insulating sheet in the state wound around the central core in the conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 2 Cylindrical part 21 Primary coil 22 Secondary coil 29 Clearance 3 Center core 301 Outer peripheral surface 31 Steel plate 32 Axial end surface 4 Insulating sheet 41 Winding start end 42 Ending end 421 Acute angle sheet corner 44 Axial surplus Portion 49 Fixing to prevent peeling 5 Insulating resin x Length in the axial direction of the central core w Sheet width L Axial direction W Width direction D Winding direction θ Inclination angle

Claims (18)

A rod-shaped central core, and a cylindrical portion having a primary coil and a secondary coil wound concentrically around the central core, and an insulating sheet is wound around the outer peripheral surface of the central core, In the ignition coil formed by filling an insulating resin between the cylindrical portion and
The insulating sheet comprises a resin film layer made of a synthetic resin and an adhesive layer disposed on the back surface of the resin film layer, and has a sheet width 0.8 to 1.2 times the axial length of the central core. An ignition coil characterized in that the winding end has an inclined portion inclined with respect to the axial direction of the central core. A rod-shaped central core, and a cylindrical portion having a primary coil and a secondary coil wound concentrically around the central core, and an insulating sheet is wound around the outer peripheral surface of the central core, In the ignition coil formed by filling an insulating resin between the cylindrical portion and
The insulating sheet includes a resin film layer made of a synthetic resin and an adhesive layer disposed on the back surface of the resin film layer, and the axial length of the central core is 0 before being wound around the central core. .8 to 1.2 times the sheet width, a pair of axial ends positioned in the width direction are parallel to each other, and the winding end when winding around the central core is the width direction An ignition coil characterized by having an inclined portion inclined with respect to.   3. The ignition coil according to claim 2, wherein the insulating sheet is wound around the central core such that the width direction thereof is parallel to the axial direction of the central core.   4. The ignition coil according to claim 1, wherein the central core is formed by laminating a plurality of steel plates in the radial direction.   5. The winding end according to claim 1, wherein the winding end has an acute sheet corner, and the acute sheet corner is fixed to prevent peeling. An ignition coil characterized by.   6. The ignition coil according to claim 1, wherein the inclined portion at the winding end has an inclination angle of 5 to 60 [deg.] With respect to the axial direction of the central core.   The ignition coil according to any one of claims 1 to 6, wherein the entire end portion of the winding is inclined in the same direction.   The ignition coil according to any one of claims 1 to 6, wherein the winding end has a mountain shape or a valley shape, with the inclination direction of the inclined portion thereof being reversed in the middle.   9. The ignition coil according to claim 1, wherein the insulating sheet has an axially surplus portion folded back on an axial end surface of the central core.   10. The axial direction both ends of the central core according to claim 1, wherein magnets are respectively disposed and the insulating sheet includes an axial length of the pair of magnets. An ignition coil having a seat width of 0.8 to 1.2 times the axial length of the central core. A rod-shaped central core, and a cylindrical portion including a primary coil and a secondary coil wound concentrically around the central core, and an insulating sheet is wound around and adhered to the outer peripheral surface of the central core; In the manufacturing method of the ignition coil formed by filling an insulating resin between the insulating sheet and the cylindrical portion,
An inclined portion that has a sheet width that is 0.8 to 1.2 times the axial length of the central core and that is inclined with respect to the width direction at at least one end in the winding direction orthogonal to the width direction. A sheet forming step of forming the provided insulating sheet;
A winding step in which the width direction of the insulating sheet is aligned with the axial direction of the central core, the insulating sheet is wound around the outer peripheral surface of the central core, and an end portion provided with the inclined portion is positioned at the winding end; A method for manufacturing an ignition coil, characterized in that:   12. The method for manufacturing an ignition coil according to claim 11, wherein the central core is formed by laminating a plurality of steel plates in the radial direction.   13. The ignition according to claim 11 or 12, wherein after the winding step is performed, a fixing step is performed for fixing the sharp corners formed at the end of winding to prevent peeling. Coil manufacturing method.   In any 1 paragraph of Claims 11-13, in the above-mentioned sheet formation process, the inclined part of one end in the above-mentioned winding direction of the above-mentioned insulating sheet is 5-60 degrees to the width direction of the above-mentioned insulating sheet. A method of manufacturing an ignition coil, wherein the ignition coil is inclined at an inclination angle.   In any 1 paragraph of Claims 11-14, in the above-mentioned sheet formation process, one end part in the above-mentioned winding direction of the above-mentioned insulating sheet forms inclining the whole inclined part towards the same direction, A method for manufacturing an ignition coil.   In any 1 paragraph of Claims 11-14, in the above-mentioned sheet formation process, one end part in the above-mentioned winding direction of the above-mentioned insulating sheet reverses the inclination direction of the inclined portion on the way, and forms a mountain or valley A method for manufacturing an ignition coil, characterized in that the ignition coil is formed into a shape.   In any one of Claims 11-16, in the said winding process, the said insulating sheet is made to protrude from the axial direction end surface of the said center core, and is wound, The axial direction excess part in this winding state is the said core core. A method for producing an ignition coil, wherein the ignition coil is folded back to an end face in the axial direction.   The axial direction both ends of the central core according to any one of claims 11 to 17, wherein magnets are respectively disposed, and the insulating sheet includes an axial length of the pair of magnets. A method for manufacturing an ignition coil, characterized in that the seat width is 0.8 to 1.2 times the axial length of the central core.

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