JP2009123838A - Ignition coil and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition coil which can prevent an outer peripheral core from being rusted by making the diameter of the coil smaller, and also a method of manufacturing the ignition coil. <P>SOLUTION: An ignition coil 1 includes primary and secondary windings 21, 22 overlapped at inner outer periphery, a central core 23 of a soft magnetic material located at the inner periphery side of the primary and secondary windings 21, 22, a coil case 41 for accommodating the central core 23 and the primary and secondary windings 21, 22, and an outer peripheral core 3 of the soft magnetic material located at the outer peripheral side of the coil case 41. The outer peripheral core 3 includes such a shape as to have a notch-shaped slit 32 along its axial direction by processing a plate-like electromagnetic steel plate into an arc shape. A surface exposure area of the outer peripheral core 3 at its outer periphery including a slit formation area is covered with a coating film 6 made of a heat shrinkable film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

In an ignition coil used in an internal combustion engine such as an engine, a central core made of a magnetic material is arranged on the inner peripheral side of a primary coil and a secondary coil formed by winding an electric wire, and the outer peripheral side of the primary coil and the secondary coil Further, an outer peripheral core made of a magnetic material is disposed. And the magnetic circuit which allows the magnetic flux generated by the primary coil and the secondary coil to pass through is formed by the central core and the outer peripheral core.
For example, as disclosed in Patent Document 1, a cylindrical outer core (side core) is disposed on the outer periphery of a coil case (exterior case) that houses a primary coil, a secondary coil, and a center core (center core). Things have been done. The outer peripheral core is formed by rolling a magnetic steel sheet into a cylindrical shape and has a notch-like slit over the entire length in the axial direction.
Further, a protrusion is formed along the axial direction on the outer periphery of the coil case, and the protrusion is disposed in the slit to form a gap for improving magnetic performance.

  By the way, the outer peripheral core is manufactured by punching out into a predetermined size from a flat plate material of an electromagnetic steel sheet having insulating coatings on both surfaces and forming it into a cylindrical shape. Therefore, although insulating coatings are formed on both surfaces of the electrical steel sheet constituting the outer peripheral core, insulating coatings are not formed on the four end surfaces. Therefore, in particular, when the outer peripheral core is disposed on the outermost peripheral side of the ignition coil, rust is easily generated on both end surfaces in the circumferential direction forming the slit. Therefore, in order to prevent the generation of rust and reduce the diameter of the ignition coil, further contrivance is required.

In Patent Document 2, a cylindrical thin film tube having a thickness of 0.35 mm or less is disposed between a primary coil and a secondary coil that are arranged on the inner and outer circumferences, and an outer core that is arranged on the outer circumference side. A small-diameter ignition coil is disclosed. However, in Patent Document 2, no member is arranged on the outer peripheral side of the exterior core, and no contrivance is made to prevent rust from occurring on both end surfaces in the circumferential direction of the exterior core.
Patent Document 1 discloses an ignition coil in which an outer peripheral core is disposed on the inner peripheral side of a housing (coil case) formed by fixing an outer diameter by injection molding or the like. According to this, it can prevent that rust generate | occur | produces in an outer periphery core. However, if the housing is disposed on the outer peripheral side of the outer core, it is difficult to reduce the diameter of the ignition coil.

JP-A-11-111548 JP 2005-191533 A

  The present invention has been made in view of such conventional problems, and is intended to provide an ignition coil capable of reducing the diameter and preventing the outer core from being rusted and a method for manufacturing the same. is there.

A first invention includes a primary coil and a secondary coil stacked on the inner and outer circumferences, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, the central core, the primary coil, and the secondary coil. In an ignition coil having a coil case that houses a coil, and a soft magnetic outer core disposed on the outer peripheral side of the coil case,
The outer peripheral core is formed in a shape having a notch-shaped slit along the axial direction by processing a flat electromagnetic steel sheet into an arc shape,
In the ignition coil, the surface exposed portion on the outer periphery of the outer peripheral core including the slit forming portion is covered with a coating film made of resin or rubber.

The ignition coil of the present invention covers the surface exposed portion of the outer peripheral core with a cylindrical or sheet-shaped covering film. Therefore, in particular, it is possible to prevent both end faces in the circumferential direction of the outer peripheral core, which is a part forming the slit, from being exposed to the outside, and to prevent rust from being generated on both end faces in the circumferential direction.
Further, the covering film does not need to be molded in a state where the outer diameter dimension is fixed by resin molding or the like, and the molding is easy. Moreover, a coating film is easy to shape | mold and it is easy to make the thickness thin.

  Therefore, according to the ignition coil of the present invention, it is possible to reduce the diameter of the ignition coil and prevent the outer core from being rusted.

According to a second aspect of the present invention, there are provided a primary coil and a secondary coil overlaid on the inner and outer periphery, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, the central core, the primary coil and the secondary coil. A coil case that accommodates the coil, and a soft magnetic outer core disposed on the outer peripheral side of the coil case. In the method of manufacturing an ignition coil formed into a shape having a notch-shaped slit,
Cylindrical heat shrinkage of the primary coil, the secondary coil, the central core, the coil case, and the outer periphery of the assembled body made of resin or rubber and having a property of shrinking when heated. Put a film,
Next, the heat shrinkable film is heated and shrunk so that the heat shrinkable film is brought into close contact with the outer periphery of the outer peripheral core so as to cover the exposed surface portion of the outer periphery of the outer peripheral core. In the method (claim 10).

In the ignition coil manufacturing method of the present invention, the cylindrical heat-shrinkable film is placed on the outer periphery of the outer core that forms the outer periphery of the assembly. At this time, the inner diameter of the cylindrical heat-shrinkable film can be made larger than the outer diameter of the outer peripheral core, and it is easy to cover the heat-shrinkable film.
Next, the heat shrink film placed on the outer periphery of the outer core is heated to shrink. At this time, the heat-shrinkable film can be in close contact with the outer periphery of the outer peripheral core and cover the surface exposed portion on the outer periphery of the outer peripheral core. Therefore, in particular, it is possible to prevent both end faces in the circumferential direction of the outer peripheral core, which is a part forming the slit, from being exposed to the outside, and to prevent rust from being generated on both end faces in the circumferential direction.

  Further, the heat-shrinkable film does not need to be molded in a state where the outer diameter dimension is fixed by resin molding or the like, and the molding is easy. Moreover, a heat shrink film is easy to shape | mold and it is easy to make the thickness thin.

  Therefore, according to the ignition coil manufacturing method of the present invention, it is possible to easily manufacture an ignition coil capable of reducing the diameter and preventing the outer core from being rusted.

According to a third aspect of the present invention, there are provided a primary coil and a secondary coil stacked on the inner and outer peripheries, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, the central core, the primary coil and the secondary coil. A coil case that accommodates the coil, and a soft magnetic outer core disposed on the outer peripheral side of the coil case. In the method of manufacturing an ignition coil formed into a shape having a notch-shaped slit,
A sheet-shaped film made of resin or rubber is wound in the circumferential direction on the outer periphery of the assembly in which the primary coil, the secondary coil, the central core, the coil case, and the outer peripheral core are assembled.
In the method of manufacturing an ignition coil, the circumferential ends of the film are welded together to form a welded portion, and the welded portion is disposed in the slit in the outer peripheral core ( Claim 11).

In the ignition coil manufacturing method of the present invention, the sheet-shaped film is wound in the circumferential direction around the outer periphery of the outer core that forms the outer periphery of the assembly.
Next, the end portions in the circumferential direction of the film wound around the outer core are welded together to form a welded portion, thereby forming a coating film. With this covering film, the surface exposed portion on the outer periphery of the outer peripheral core can be covered. Therefore, in particular, it is possible to prevent both end faces in the circumferential direction of the outer peripheral core, which is a part forming the slit, from being exposed to the outside, and to prevent rust from being generated on both end faces in the circumferential direction.

Moreover, the said welding part is arrange | positioned in the slit in an outer periphery core. Therefore, it can prevent that the formation part of a welding part protrudes in a radial direction outer side rather than the outer periphery of a coating film. Thereby, it can prevent that the outer diameter of an ignition coil becomes large.
Further, the film does not need to be molded in a state where the outer diameter dimension is fixed by resin molding or the like, and the film is easy to mold. Moreover, a film is easy to shape | mold and it is easy to make the thickness thin.

  Therefore, also by the ignition coil manufacturing method of the present invention, it is possible to easily manufacture an ignition coil capable of reducing the diameter and preventing the outer core from being rusted.

A fourth invention includes a primary coil and a secondary coil stacked on the inner and outer periphery, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, the central core, the primary coil, and the secondary coil. A coil case that accommodates the coil, and a soft magnetic outer core disposed on the outer peripheral side of the coil case. In the method of manufacturing an ignition coil formed into a shape having a notch-shaped slit,
A cylindrical elastic film made of resin or rubber was expanded in diameter by applying a load to the outer periphery of the assembly including the primary coil, the secondary coil, the central core, the coil case, and the outer peripheral core. Put on condition,
Next, by removing the load, the diameter of the elastic film is reduced, the elastic film is brought into close contact with the outer periphery of the outer peripheral core, and the exposed surface portion of the outer periphery of the outer peripheral core is covered. It exists in a manufacturing method (Claim 12).

In the method for manufacturing an ignition coil according to the present invention, the cylindrical elastic film is placed on the outer periphery of the outer peripheral core forming the outer periphery of the assembly in a state where the diameter is increased by applying a load.
Next, the elastic film is reduced in diameter by removing the load. At this time, the elastic film can be in close contact with the outer periphery of the outer core and cover the exposed surface portion of the outer periphery of the outer core. Therefore, in particular, it is possible to prevent both end faces in the circumferential direction of the outer peripheral core, which is a part forming the slit, from being exposed to the outside, and to prevent rust from being generated on both end faces in the circumferential direction.

  Further, the elastic film does not need to be molded in a state where the outer diameter dimension is fixed by resin molding or the like, and the molding is easy. In addition, the elastic film can be easily molded and its thickness can be easily reduced.

  Therefore, also by the ignition coil manufacturing method of the present invention, it is possible to easily manufacture an ignition coil capable of reducing the diameter and preventing the outer core from being rusted.

A preferred embodiment in the first to fourth inventions described above will be described.
In the first to fourth inventions, a product number, a trademark, or the like can be attached to the covering film. In this case, the name plate attached to the ignition coil can be eliminated.
Polyethylene terephthalate, polyester, polystyrene, polypropylene, polyethylene, and the like can be used as the covering film, heat shrink film, and film in the first to third inventions. As the elastic film in the fourth invention, rubber such as silicon, fluorine, acrylic, TPE (thermoplastic elastomer), or the like can be used.

In the first invention, the film to be coated is formed of a heat-shrinkable film having a cylindrical shape, in close contact with the outer periphery of the outer peripheral core, and having a property of shrinking by heating. Preferred (claim 2).
In this case, it is easy to form the covering film, and the covering film can be easily put on the outer periphery of the outer peripheral core. This facilitates the manufacture of the ignition coil.

The film to be wrapped is wound around the outer periphery of the outer core in the circumferential direction, and has a welded portion that is welded by joining the ends in the circumferential direction. It is preferable to arrange | position in (Claim 3).
In this case, a sheet-shaped material can be used as the covering film. Further, by arranging the welded portion in the slit, it is possible to prevent the outer diameter of the ignition coil from increasing even if a sheet-shaped material is used.

Further, a resin connector case provided with a connector portion for electrically connecting the ignition coil to the outside is provided on the upper end side in the axial direction of the coil case, and on the lower end side in the axial direction of the coil case. Is provided with a plug mounting portion to be mounted on the spark plug, and both end portions in the axial direction of the covering film are spanned between the outer periphery of the connector case and the outer periphery of the plug mounting portion. ).
In this case, it is possible to make it difficult for moisture to enter the outer core from both ends in the axial direction of the coating film by spanning the both ends in the axial direction of the coating film between the outer periphery of the connector case and the outer periphery of the plug mounting portion. it can.

In addition, at least one of the outer periphery of the connector case and the outer periphery of the plug mounting portion is formed with an annular protrusion that protrudes on the entire periphery thereof, and at least one of both axial ends of the covering film is It is preferable that it is in close contact with the surface of the annular protrusion.
In this case, the annular protrusion can effectively prevent a gap from being generated between the outer periphery of the connector case or the outer periphery of the plug mounting portion and the covering film.

The axial upper end of the outer peripheral core is fitted into a fitting opening provided in the connector case, and a rubber seal rubber for closing the opening of the plug hole is provided on the outer periphery of the connector case. It is preferable that both end portions in the axial direction of the covering film are spanned between the outer periphery of the seal rubber and the outer periphery of the plug mounting portion.
In this case, both end portions in the axial direction of the covering film can be brought into close contact with the rubber parts by spanning both end portions in the axial direction of the covering film between the outer periphery of the seal rubber and the outer periphery of the plug mounting portion. it can. Therefore, it is possible to make it difficult for moisture to enter the outer peripheral core from both axial ends of the covering film.

In addition, at least one of the outer periphery of the seal rubber and the outer periphery of the plug mounting portion is formed with an annular protrusion that protrudes on the entire periphery thereof, and at least one of the axial end portions of the covering film is It is preferable that it is in close contact with the surface of the annular protrusion.
In this case, it is possible to effectively prevent the annular protrusion from generating a gap between the outer periphery of the seal rubber or the outer periphery of the plug mounting portion and the coating film.

Moreover, it is preferable that the said covering film consists of a film of the polyethylene terephthalate which has the thickness below the plate | board thickness of the said outer periphery core (Claim 8).
In this case, it becomes easy to form the coating film and to make the coating film thinner. In addition, the thickness of a coating film can also be made into below the board thickness of one electromagnetic steel plate which comprises an outer periphery core.

Moreover, it is preferable that at least one of the axial direction both ends of the said covering film is contacting the axial direction end surface of the said outer periphery core (Claim 9).
In this case, the rust prevention effect of the axial end surface of the outer peripheral core can be made remarkable.

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 FIGS. 1 and 2, the ignition coil 1 of the present example is composed of a primary coil 21 and a secondary coil 22 that are overlapped on the inner and outer circumferences, and a soft magnetic coil disposed on the inner circumference side of the primary coil 21 and the secondary coil 22. A central core 23, a coil case 41 that accommodates the central core 23, the primary coil 21 and the secondary coil 22, and a soft magnetic outer core 3 disposed on the outer peripheral side of the coil case 41 are provided. The outer peripheral core 3 is formed in a shape having a notch-shaped slit 32 along the axial direction by processing a flat electromagnetic steel sheet 31 into an arc shape. And the surface exposure part in the outer periphery of the outer periphery core 3 including the formation part of the slit 32 is covered with the coating film 6 which consists of resin or rubber | gum (refer FIG. 5).

Hereinafter, the ignition coil 1 of this example and the manufacturing method thereof will be described in detail with reference to FIGS.
As shown in FIG. 1, the ignition coil 1 of this example includes a coil portion 11 formed by a primary coil 21, a secondary coil 22, a central core 23, an outer peripheral core 3, and a coil case 41 as an engine cylinder head and a cylinder head cover. It is a stick type used by being inserted into a provided plug hole.
A resin part provided with a connector part 421 for electrically connecting the ignition coil 1 to an electronic control unit (ECU) of the engine is provided at the upper end part in the axial direction D of the coil part 11 (the axial upper end side in the coil case 41). A connector case 42 is provided. The plug mounting portion 5 for mounting on the lever portion 71 of the spark plug 7 screwed into the bottom portion of the plug hole of the cylinder head at the lower end portion in the axial direction D of the coil portion 11 (the lower end side in the axial direction of the coil case 41). Is provided.

  An igniter 43 having a switching control circuit is disposed in the connector case 42, and an insertion port 422 for inserting the coil unit 11 is formed. In the ignition coil 1 of this example, after the coil portion 11 is assembled, the outer peripheral core 3 of the coil portion 11 and the upper end portion in the axial direction D of the coil case 41 are inserted into the fitting inlet 422 in the connector case 42. And assembled. And the axial direction upper end part of the outer periphery core 3 is inserted in the insertion port 422. FIG.

Further, as shown in FIG. 1, a protruding cylindrical portion 424 for mounting the seal rubber 44 is provided on the lower end side in the axial direction of the connector case 42 so as to protrude downward in the axial direction. An annular seal rubber 44 that seals between the connector case 42 and the plug hole is attached to the outer periphery of the protruding cylindrical portion 424. The fitting opening 422 is provided continuously from the main body portion of the connector case 42 to the protruding cylindrical portion 424.
Further, an alignment portion 423 that holds the upper end portion of the central core 23 in the axial direction D is formed at the upper portion of the fitting opening 422 in the connector case 42, and the alignment portion 423 allows the central core 23 and the secondary spool to be aligned. The center positioning of 221 is performed.

  The primary coil 21 is formed by winding an insulating-coated primary winding around the outer periphery of a primary spool 211 made of resin having an annular cross section. The secondary coil 22 is formed by winding an insulating-coated secondary winding around the outer periphery of a secondary spool 221 made of resin having an annular cross section. Further, the secondary winding has a smaller diameter than the primary winding, and the secondary winding is wound around the secondary spool 221 more times than the primary winding.

As shown in FIG. 2, the central core 23 of this example is formed by laminating a plurality of flat electromagnetic steel plates (silicon steel plates or the like) in the radial direction R of the ignition coil 1 and having a substantially circular cross section.
The outer peripheral core 3 of this example is formed by laminating a plurality of electromagnetic steel plates 31 (silicon steel plates or the like) in the radial direction R thereof. The plurality of electromagnetic steel plates 31 are formed into a circular arc shape having slits 32 after being punched into a flat plate shape from a flat plate material having insulating coatings on both surfaces. Moreover, the some electromagnetic steel plate 31 is shape | molded in circular arc shape from the flat plate of the same shape, and shaping | molding is easy.
In addition, the circumferential direction end surface 33 and the axial direction end surface 34 of the electromagnetic steel plate 31 are in a state where an insulating coating is not formed.

Moreover, in the outer periphery core 3, as shown in FIG. 2, the position of the slit 32 in the circumferential direction C can be varied, and the electromagnetic steel plates 31 can be laminated. As shown in FIG. The electromagnetic steel plates 31 can also be laminated in alignment.
The outer peripheral core 3 can be formed by laminating, for example, 2 to 5 electromagnetic steel plates 31. The outer core 3 can also be formed from one electromagnetic steel plate 31.

  As shown in FIG. 1, the plug mounting portion 5 is connected to the coil case 41 (in this example, integrally formed at the lower end portion in the axial direction D of the coil case 41), and the cylindrical base portion 51. A rubber plug cap 52 for fitting the insulator portion 71 of the spark plug 7, a high voltage terminal 53 conducted to the end of the high voltage winding of the secondary coil 22, and a high voltage terminal 53 And a coil spring 54 that is conducted. The lower end portion of the coil spring 54 in the axial direction D is electrically connected to a terminal portion 72 formed at the tip of the lever portion 71 of the spark plug 7.

The coated film 6 of this example has a cylindrical shape, is in close contact with the outer periphery of the outer core 3, and includes a heat-shrinkable film 60 that has a property of contracting when heated. The covering film 6 is made of a polyethylene terephthalate (PET) film having a thickness equal to or less than the thickness of the outer peripheral core 3.
Further, both end portions 61 in the axial direction of the covering film 6 of this example are spanned between the outer periphery of the protruding cylindrical portion 424 in the connector case 42 and the outer periphery of the plug cap 52 in the plug mounting portion 5.

  Further, in the gap in the ignition coil 1 surrounded by the coil case 41, the connector case 42, and the cylindrical base portion 51, each component (primary coil 21, secondary coil 22, central core 23, etc.) is fixed and insulated. The thermosetting resin 15 (epoxy resin etc.) for performing is filled. The thermosetting resin 15 is assembled after the components of the ignition coil 1 are assembled, the gap in the ignition coil 1 is evacuated, and the vacuum gap is filled in a liquid state and then cured. Formed.

  In the ignition coil 1 of this example, when the primary coil 21 is energized by the switching control circuit of the igniter 43 in response to a command from the ECU, a magnetic field passing through the central core 23 and the outer core 3 is formed. Next, when the energization of the primary coil 21 is interrupted, a voltage is generated in the primary coil 21 by the self-induction action, and a high-voltage induced electromotive force is generated in the secondary coil 22 by the mutual induction action. A spark can be generated between a pair of electrodes in the mounted spark plug 7.

Next, the manufacturing method and operation effect of the ignition coil 1 of this example will be described.
When manufacturing the ignition coil 1 of this example, the primary coil 21, the secondary coil 22, the central core 23, the outer core 3, the coil case 41, the connector case 42, the igniter 43, the seal rubber 44, the plug cap 52, the high The voltage terminal 53 and the coil spring 54 are assembled. Then, the thermosetting resin 15 is filled in the gap surrounded by the coil case 41, the connector case 42, and the cylindrical base portion 51 to form the ignition coil assembly 10 as shown in FIG.
Next, as shown in the figure, a cylindrical heat-shrink film 60 is placed on the outer periphery of the outer core 3 that forms the outer periphery of the ignition coil assembly 10. At this time, the inner diameter of the cylindrical heat-shrink film 60 is larger than the outer diameter of the outer peripheral core 3, and it is easy to cover the heat-shrink film 60.

Next, as shown in FIG. 5, the heat shrinkable film 60 placed on the outer periphery of the outer core 3 is heated and shrunk. At this time, the heat shrink film 60 is in close contact with the outer periphery of the outer core 3 to form the covering film 6, and both axial end portions 61 of the covering film 6 are connected to the outer periphery of the protruding cylindrical portion 424 in the connector case 42 and the plug mounting portion 5. Is stretched over the outer periphery of the plug cap 52. Thereby, the surface exposure part in the outer periphery of the outer periphery core 3 can be covered with the coating film 6. Further, it is possible to make it difficult for moisture to enter the outer core 3 from both axial end portions 61 of the covering film 6.
Therefore, in particular, it is possible to prevent the circumferential end surfaces 33 of the outer peripheral core 3 that are the portions forming the slits 32 from being exposed to the outside, and to prevent the circumferential end surfaces 33 from being rusted. Can do.

Further, the heat shrink film 60 does not need to be molded in a state where the outer diameter dimension is fixed by resin molding or the like, and is easy to mold. Moreover, the heat shrink film 60 is easy to mold and it is easy to reduce its thickness.
Moreover, the heat-shrinkable film 60 of this example does not have an adhesive layer on its inner peripheral side. Therefore, the thickness of the heat shrink film 60 can be further reduced.

  Therefore, according to the ignition coil 1 and the manufacturing method thereof of the present example, the ignition coil 1 that can prevent the rust from being generated on the outer peripheral core 3 by reducing the diameter can be easily manufactured.

An adhesive can be provided on the axial end 61 of the covering film 6. In this case, moisture can be more difficult to enter from the axial end 61 of the covering film 6 to the surface of the outer peripheral core 3.
Further, as shown in FIG. 6, for example, in the ignition coil 1 of the type in which the seal rubber 44 is fitted into the step enlarged diameter portion 811 provided in the opening of the plug hole 81, both end portions 61 in the axial direction of the covering film 6 are The seal rubber 44 can be stretched over the outer periphery of the plug cap 52 in the plug mounting portion 5. In this case, both axial end portions 61 of the covering film 6 can be in close contact with the rubber component. Therefore, it is possible to make it difficult for moisture to enter the outer core 3 from both axial ends 61 of the covering film 6.

Further, as shown in FIG. 7, an annular protrusion 441 is formed on the outer periphery of the seal rubber 44 so as to protrude all around, and the axial end portion 61 of the covering film 6 is brought into close contact with the surface of the annular protrusion 441. Can do. In this case, the annular protrusion 441 can effectively prevent a gap from being generated between the outer periphery of the seal rubber 44 and the covering film 6.
Although not shown, the annular protrusion 441 can also be provided on the outer periphery of the connector case 42 or the plug cap 52, and effectively prevents a gap from being generated between the outer periphery and the covering film 6. You can also.

(Example 2)
In this example, the ignition coil 1 using a sheet-shaped film 60 </ b> A made of a resin as the film 6 to be coated is shown.
As shown in FIGS. 8 and 9, the film 6 of this example is wound in the circumferential direction C around the outer periphery of the outer core 3, and welded 63 in which the circumferential ends 62 are welded together. have. The welded portion 63 is disposed in the slit 32 in the outer peripheral core 3. The film 60 </ b> A of this example is made of a polyethylene terephthalate film having a thickness equal to or less than the thickness of the outer peripheral core 3.

The welded portion 63 can be formed by welding the circumferential end portions 62 of the covering film 6 with the following various shapes.
For example, as shown in FIGS. 8 to 10, the welded portion 63 is welded in a state where the other circumferential end 62 overlaps the outer circumferential side of one circumferential end 62 within the slit 32 of the outer core 3. Can be formed.
For example, as shown in FIG. 11, the welding portion 63 is wound in a state where one circumferential end 62 and the other circumferential end 62 are overlapped in the slit 32 of the outer core 3. It can also be formed by welding in a wet state.

  Further, for example, as shown in FIG. 12, the welding portion 63 folds back only one circumferential end 62 in the slit 32 of the outer core 3, and overlaps the folded portion with both circumferential ends 62. It can also be formed by welding in a combined state. Further, for example, as shown in FIG. 13, the welded portion 63 folds one circumferential end 62 and the other circumferential end 62 in the slit 32 of the outer core 3, and contacts the folded portions with each other. It can also be formed by welding. In addition, in FIGS. 11-13, the part to weld is shown by the arrow.

  Further, as shown in FIG. 8, when the positions of the slits 32 in the plurality of electromagnetic steel plates 31 constituting the outer core 3 are different from each other in the circumferential direction C, the welded portion 63 is a slit in the outermost electromagnetic steel plate 31A. 32. In this case, since the slit 32 in the electromagnetic steel sheet 31B located on the inner peripheral side is covered with the electromagnetic steel sheet 31A located on the outer peripheral side, the rust prevention effect can be made remarkable.

  Further, as shown in FIG. 9, when the positions in the circumferential direction C of the slits 32 in the plurality of electromagnetic steel plates 31 constituting the outer core 3 are aligned with each other, the welded portion 63 is aligned in the circumferential direction C. It can be arranged in the slit 32. In this case, it is easy to prevent the welded portion 63 from protruding outward in the radial direction from the coating film 6.

Further, as shown in FIG. 10, the outermost electromagnetic steel sheet 31 </ b> A can be formed with a recess 311 for disposing the welded portion 63 at a location different from the location where the slit 32 is formed in the circumferential direction. In this case, it is considered that the place where the welded portion 63 is formed is inferior in waterproofness compared to other portions. Therefore, it is possible to make it difficult for moisture to reach the circumferential end surface 33 of the outer core 3 by disposing the welded portion 63 in the recess 311 different from the slit 32.
In addition, the thickness of the coating film 6 can be made equal to or less than the thickness of the electromagnetic steel sheet 31 constituting the outer core 3.

When manufacturing the ignition coil 1 of this example, as shown in FIG. 8, a sheet-shaped film 60 </ b> A made of resin is wound around the outer periphery of the ignition coil assembly 10 in the circumferential direction.
Next, the end portions 62 in the circumferential direction of the film 60 </ b> A wound around the outer core 3 are welded together to form the welded portion 63, thereby forming the coating film 6. With this covering film 6, the surface exposed portion on the outer periphery of the outer peripheral core 3 can be covered. Therefore, in particular, it is possible to prevent the circumferential end surfaces 33 of the outer peripheral core 3 that are the portions forming the slits 32 from being exposed to the outside, and to prevent the circumferential end surfaces 33 from being rusted. Can do.

Further, the welded portion 63 is disposed in the slit 32 in the outer peripheral core 3. Therefore, the formation part of the welding part 63 can be prevented from projecting radially outward from the outer periphery of the covering film 6. Thereby, it can prevent that the outer diameter of the ignition coil 1 becomes large.
The film 60A does not need to be molded in a state where the outer diameter is fixed by resin molding or the like, and the film 60A is easy to mold. Further, the film 60A can be easily molded and its thickness can be easily reduced.

Therefore, also by the ignition coil 1 of this example and its manufacturing method, it is possible to easily manufacture the ignition coil 1 capable of reducing the diameter and preventing the outer core 3 from being rusted.
Also in this example, other configurations of the ignition coil 1 and other functions and effects are the same as those in the first embodiment.

(Example 3)
This example is an example of the ignition coil 1 using a cylindrical elastic film made of rubber as the film 6 to be coated.
The elastic film of this example is made of a rubber film such as silicon, fluorine, or acrylic having a thickness equal to or less than the thickness of the outer core 3. In this example, illustration is omitted.

When manufacturing the ignition coil 1 of this example, the outer periphery of the ignition coil assembly 10 is covered with a cylindrical elastic film made of rubber in a state where the diameter is increased by applying a load.
Next, the elastic film is reduced in diameter by removing the load. At this time, the elastic film can be brought into close contact with the outer periphery of the outer core 3 to cover the exposed portion of the outer periphery of the outer core 3. Therefore, in particular, it is possible to prevent the circumferential end surfaces 33 of the outer peripheral core 3 that are the portions forming the slits 32 from being exposed to the outside, and to prevent the circumferential end surfaces 33 from being rusted. Can do.
Also in this example, other configurations of the ignition coil 1 and other functions and effects are the same as those in the first embodiment.

Example 4
This example is an example shown about various structures which cover the axial direction end surface 34 of the outer periphery core 3 arrange | positioned on the outer periphery of the coil case 41 with the film 6 to be coated.
In the following drawings, the portion where the axial end portion 61 of the covering film 6 is in close contact may be any of the coil case 41, the connector case 42, the seal rubber 44, and the plug mounting portion 5 (plug cap 52). Shall. And the vicinity of the part which arrange | positions the outer periphery core 3, and the part which arrange | positions the axial direction end surface 34 of the outer periphery core 3 is called coil case 41 grade | etc., In the following description.

As shown in FIG. 14, the covering film 6 can cover the surface exposed portion of the outer peripheral core 3 while being in contact with the axial end surface 34 of the outer peripheral core 3. In this case, the rust prevention effect of the axial end surface 34 of the outer peripheral core 3 on which no insulating coating is formed can be made remarkable.
Moreover, as shown in FIGS. 15-17, the annular recessed part 411 for arrange | positioning the outer periphery core 3 can be formed in the perimeter of coil case 41 grade | etc.,. In this case, as shown in FIG. 15, the axial end portion 61 of the covering film 6 can be brought into close contact with the outer periphery of the end portion 412 that forms the axial end surface of the annular recess 411. In this case, as shown in FIG. 16, the outer peripheral core 3 is accommodated in the annular recess 411, and the axial end 61 of the covering film 6 is replaced with the outer periphery of the end 412 that forms the axial end surface of the annular recess 411. It can also be closely attached to. Further, in this case, as shown in FIG. 17, the axial end 61 of the covering film 6 can be brought into close contact with the surface of the annular recess 411.

  Further, as shown in FIG. 18, stepped portions 413 can be formed at both ends of the annular recess 411 in the axial direction, and the axial end 61 of the covering film 6 can be brought into close contact with the stepped portion 413. In the case of FIG.17 and FIG.18, the axial direction edge part of the coating film 6 enters into the clearance gap between the outer periphery core 3, coil case 41 grade | etc., And there also exists an effect which suppresses the position shift of the outer periphery core 3 in the axial direction.

  Further, as shown in FIGS. 19 and 20, an annular convex portion 414 projecting radially outward is provided on the entire circumference of the coil case 41 and the like at a position facing both end surfaces 34 in the axial direction of the outer core 3. Can do. In this case, the outer periphery core 3 can be arrange | positioned in the space 415 between cyclic | annular convex parts 414, and the axial direction edge part 61 of the coating film 6 can be closely_contact | adhered to the axial outer side surface of the cyclic | annular convex part 414. As shown in FIG. 19, a part of the outer core 3 may protrude radially outward from the space 415, or may be accommodated in the space 415 as shown in FIG. 20. Further, as shown in FIG. 21, the covering film 6 can also be brought into close contact with the surface located on the outer side in the axial direction from the formation position of the annular protrusion 414.

19 to 21, the outer peripheral core 3 can be positioned in the axial direction by the annular convex portion 414 provided on the coil case 41 or the like. Moreover, in FIGS. 19-21, since the coating film 6 has gone around to the axial direction outer side of the cyclic | annular convex part 414 provided in the coil case 41 grade | etc., The axial positioning of the coating film 6 can also be performed. .
Also in this example, other configurations of the ignition coil 1 and other functions and effects are the same as those in the first embodiment.

Explanatory drawing which shows the cross section of the axial direction of an ignition coil in Example 1. FIG. FIG. 3 is an explanatory diagram showing a cross section orthogonal to the axial direction of the ignition coil in the first embodiment. Explanatory drawing which shows the cross section orthogonal to the axial direction of the other ignition coil in Example 1. FIG. Explanatory drawing which shows the side surface of the axial direction of the ignition coil in the state which covered the heat-shrink film in Example 1. FIG. Explanatory drawing which shows the side surface of the axial direction of the ignition coil of the state which shrunk the heat-shrink film in Example 1. FIG. Explanatory drawing which shows the cross section of the axial direction of the other ignition coil in Example 1. FIG. Sectional explanatory drawing which expands and shows the periphery of the seal rubber which formed the cyclic | annular protrusion in Example 1. FIG. Explanatory drawing which shows the cross section orthogonal to the axial direction of an ignition coil in Example 2. FIG. Explanatory drawing which shows the cross section orthogonal to the axial direction of the other ignition coil in Example 2. FIG. Explanatory drawing which shows the cross section orthogonal to the axial direction of the other ignition coil in Example 2. FIG. Explanatory drawing which expands and shows the periphery of the welding part of a coating film in Example 2. FIG. Explanatory drawing which expands and shows the periphery of the other welding part of a coating film in Example 2. FIG. Explanatory drawing which expands and shows the periphery of the other welding part of a coating film in Example 2. FIG. Explanatory drawing which expands and shows the structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG. Explanatory drawing which expands and shows the other structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG. Explanatory drawing which expands and shows the other structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG. Explanatory drawing which expands and shows the other structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG. Explanatory drawing which expands and shows the other structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG. Explanatory drawing which expands and shows the other structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG. Explanatory drawing which expands and shows the other structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG. Explanatory drawing which expands and shows the other structure of the coating film which covers the surface exposure part of an outer periphery core in Example 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 10 Ignition coil assembly 21 Primary coil 22 Secondary coil 23 Central core 3 Outer core 31 Magnetic steel sheet 32 Slit 33 Circumferential end surface 41 Coil case 42 Connector case 421 Connector part 44 Seal rubber 5 Plug mounting part 52 Plug cap 6 coating film 60 heat shrink film 61 axial end 7 spark plug C circumferential direction D axial direction

Claims (12)

A primary coil and a secondary coil stacked on the inner and outer periphery, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, and a resin that accommodates the central core, the primary coil, and the secondary coil In an ignition coil having a coil case and a soft magnetic outer core disposed on the outer peripheral side of the coil case,
The outer peripheral core is formed in a shape having a notch-shaped slit along the axial direction by processing a flat electromagnetic steel sheet into an arc shape,
An ignition coil, wherein a surface exposed portion on the outer periphery of the outer peripheral core including the slit forming portion is covered with a coating film made of resin or rubber.   2. The film according to claim 1, wherein the multi-layered film has a cylindrical shape, is in close contact with the outer periphery of the outer peripheral core, and is made of a heat shrinkable film having a property of shrinking when heated. Ignition coil to play.   In Claim 1, the said film to be wrapped is wound around the outer periphery of the outer peripheral core in the circumferential direction, and has a welded portion that is welded by joining the ends in the circumferential direction. An ignition coil arranged in the slit. The resin connector case having a connector portion for electrically connecting the ignition coil to the outside is provided on the upper end side in the axial direction of the coil case according to any one of claims 1 to 3. The axial lower end side of the coil case is provided with a plug mounting portion to be mounted on the spark plug.
An ignition coil characterized in that both end portions in the axial direction of the covering film are stretched over the outer periphery of the connector case and the outer periphery of the plug mounting portion. In claim 4, at least one of the outer periphery of the connector case and the outer periphery of the plug mounting portion is formed with an annular protrusion that protrudes on the entire periphery thereof,
At least one of the axial direction both ends of the said covering film is closely_contact | adhered to the surface of the said cyclic | annular protrusion, The ignition coil characterized by the above-mentioned. In Claim 4, the axial direction upper end part of the above-mentioned peripheral core is inserted in the fitting entrance provided in the above-mentioned connector case,
On the outer periphery of the connector case, a rubber seal rubber for closing the opening of the plug hole is attached,
An ignition coil characterized in that both end portions in the axial direction of the covering film are stretched over the outer periphery of the seal rubber and the outer periphery of the plug mounting portion. In claim 6, at least one of the outer periphery of the seal rubber and the outer periphery of the plug mounting portion is formed with an annular protrusion that protrudes on the entire periphery thereof.
At least one of the axial direction both ends of the said covering film is closely_contact | adhered to the surface of the said cyclic | annular protrusion, The ignition coil characterized by the above-mentioned.   8. The ignition coil according to claim 1, wherein the covering film is made of a polyethylene terephthalate film having a thickness equal to or less than a plate thickness of the outer peripheral core. 9.   9. The ignition coil according to claim 1, wherein at least one of both axial end portions of the covering film is in contact with an axial end surface of the outer peripheral core. A primary coil and a secondary coil stacked on the inner and outer circumferences, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, and a coil that accommodates the central core and the primary coil and the secondary coil A case and a soft magnetic outer core disposed on the outer peripheral side of the coil case. The outer core is processed into a circular arc shape from a flat electromagnetic steel plate, and a notched slit along the axial direction is formed. In the manufacturing method of the ignition coil formed into a shape having,
Cylindrical heat shrinkage of the primary coil, the secondary coil, the central core, the coil case, and the outer periphery of the assembled body made of resin or rubber and having a property of shrinking when heated. Put a film,
Next, the heat shrinkable film is heated and shrunk so that the heat shrinkable film is brought into close contact with the outer periphery of the outer peripheral core so as to cover the exposed surface portion of the outer periphery of the outer peripheral core. Method. A primary coil and a secondary coil stacked on the inner and outer circumferences, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, and a coil that accommodates the central core and the primary coil and the secondary coil A case and a soft magnetic outer core disposed on the outer peripheral side of the coil case. The outer core is processed into a circular arc shape from a flat electromagnetic steel plate, and a notched slit along the axial direction is formed. In the manufacturing method of the ignition coil formed into a shape having,
A sheet-shaped film made of resin or rubber is wound in the circumferential direction on the outer periphery of the assembly in which the primary coil, the secondary coil, the central core, the coil case, and the outer peripheral core are assembled.
A method for manufacturing an ignition coil, wherein the circumferential ends of the film are welded together to form a welded portion, and the welded portion is disposed in the slit in the outer peripheral core. A primary coil and a secondary coil stacked on the inner and outer circumferences, a soft magnetic central core disposed on the inner peripheral side of the primary coil and the secondary coil, and a coil that accommodates the central core and the primary coil and the secondary coil A case and a soft magnetic outer core disposed on the outer peripheral side of the coil case. The outer core is processed into a circular arc shape from a flat electromagnetic steel plate, and a notched slit along the axial direction is formed. In the manufacturing method of the ignition coil formed into a shape having,
A cylindrical elastic film made of resin or rubber was expanded in diameter by applying a load to the outer periphery of the assembly including the primary coil, the secondary coil, the central core, the coil case, and the outer peripheral core. Put on condition,
Next, by removing the load, the diameter of the elastic film is reduced, the elastic film is brought into close contact with the outer periphery of the outer peripheral core, and the exposed surface portion of the outer periphery of the outer peripheral core is covered. Production method.

Images