JP4262930B2 - Ignition coil for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of an ignition coil for an internal combustion engine that supplies a high voltage to an ignition plug, and particularly accommodated in a plug hole of an engine head.
[0002]
[Prior art]
The ignition coil used in a recent automobile internal combustion engine has conflicting demands for miniaturization and high output to cope with a lean combustion engine considering the environment.
[0003]
Among them, the cylindrical ignition coil for an internal combustion engine that directly supplies a high voltage to the ignition plug of the engine accommodates a part or most of it in the plug hole of the engine head, so that the space on the engine head can be reduced, In order to supply high voltage directly to the spark plug, there is no need for a conducting wire to the spark plug such as a high tension cable, so there is less noise during ignition that adversely affects the electrical components, and the ignition energy to the spark plug It is used in many engines because of its advantages such as low propagation loss.
[0004]
FIG. 4 shows a longitudinal sectional view of a cylindrical ignition coil for an internal combustion engine to which the conventional technique as described above is applied. FIG. 5 is a view showing the assembling direction of the tower portion and the case of the cylindrical ignition coil for the internal combustion engine to which the conventional technique is applied. FIG. 6 is an enlarged cross-sectional view showing a fitting state of the protrusions of the tower part after the tower part and the case of FIG. 5 are assembled. 2. Description of the Related Art Conventionally, a cylindrical ignition coil for an internal combustion engine that directly supplies a high voltage to an ignition plug includes an outer case and a tower portion that is mounted in the outer case and assembles a primary coil and a secondary coil. This structure will be described in detail with reference to FIGS. 4 to 6. The case 11 has a large opening in the upper part made of resin and an opening in the lower part of the cylindrical shape, and polyphenylene sulfide (“PPS”) having good electrical insulation characteristics. ) Or polybutylene terephthalate ("PBT") or other flame-retardant insulating resin material. Similarly to the case, the tower portion 14 includes a primary coil 15 formed by molding a resin material such as PPS or PBT, and winding a primary copper wire around the outer peripheral surface 14u of the tower portion. Is provided with a plurality of sections from one end to one end, and a secondary coil 17 in which a secondary copper wire is wound around a secondary bobbin 16 in which each section is laminated and a central iron core formed of a silicon steel plate or the like 18 are arranged. Further, a primary voltage input unit 12 for supplying a power supply voltage to the primary coil 15 is attached to the upper housing part 11b of the case 11, and an igniter 13 for turning on and off the primary current is housed in the upper housing part 11b. To do. At the tip of the cylindrical portion of the case 11 is provided a hole 11d that fits into an engaging projection 14t of a tower portion described later.
[0005]
Further, the central iron core 18 and the secondary coil 17 coaxially with the central iron core 18 are arranged in the primary coil 15 and are formed in a cylindrical shape outside of the primary coil 15 and part of the circumference thereof. In some cases, two outer iron cores 19 having notches are usually arranged. At this time, the cutout portions of the outer iron core 19 are alternately arranged at intervals of 180 °. At both ends of the central iron core 18, there are magnetic flux generated in the primary coil 15 in order to suppress saturation of the magnetic flux of the iron core in the secondary coil 17 in which the secondary copper wire is wound around the secondary bobbin 16. In some cases, the ignition energy is increased by attaching magnets 21 that generate magnetic fluxes in opposite directions to both ends. These are referred to as the primary coil assembly 10.
[0006]
In addition, the bottom of the tower 14 is provided with a secondary high voltage terminal 22 on the inner bottom of the tower 14 in order to supply a high voltage generated by the secondary coil 17 to a spark plug (not shown). An O-ring 41 for preventing leakage of the insulating casting material is mounted, and two key-like engagements projecting radially outward at equal intervals of 180 ° are attached to the tip of the outer peripheral surface 14u of the tower. A protrusion 14t is formed.
[0007]
Next, when the above-described primary coil assembly 10 is assembled to the case 11, the two engaging protrusions 14 t that are inserted from the upper opening of the case 11 and are provided around the bottom portion of the tower portion 14 and the case 11. At the same time that the hole 11d is fitted, the primary voltage input portion 21 and the primary coil assembly 10 are electrically connected. Further, the secondary high-voltage terminal 22 is electrically connected to a conductive spring 23, and rubber or the like having excellent electrical insulation so that a high voltage does not leak to a metal part such as a plug hole (not shown) at the bottom of the tower part 14. The protector 25 molded in the above is attached and the spring 23 is covered. Further, an insulating casting material is injected and filled from the opening at the top of the case 11 and cured, and then insulated and sealed.
[0008]
When the ignition coil is operated, the primary current is supplied to the primary coil 15 from the primary voltage input unit 12 by the ON operation of the igniter 13, and the primary current is supplied by the OFF operation of the igniter 13 at the timing of ignition. , The magnetic energy generated in the primary coil 15 propagates through the central iron core 18 and the outer iron core 19, and a high voltage corresponding to the turn ratio of the primary coil 15 and the secondary coil 17 is 2. It occurs in the next coil 17. The generated high voltage is sent from the secondary coil to the ignition plug (not shown) connected to the spring 23 through the secondary high voltage terminal 22 and the spring 23.
[0009]
[Problems to be solved by the invention]
In the conventional ignition coil as described above, most of the main body portions of the case 11 and the tower portion 14 are made of resin, and it is difficult to release the heat of the ignition coil generated during the operation of the automobile. Loss causes performance degradation. In addition, since such an ignition coil is used under severe conditions such as heat and vibration, measures such as increasing the thickness of the resin are necessary to ensure sufficient strength. In the plug hole insertion type ignition coil, a primary coil, a secondary coil, an iron core or the like must be embedded in a narrow space, and the resin is required to be thin. However, as described above, when the case 11 and the tower portion 14 are formed of resin, it is difficult to make the engine 11 conform to the complex shape of the engine in recent times as well as insufficient strength when thin. In addition, once the ignition coil made of resin molding is completed, it is difficult to easily deform the outside of the ignition coil. Has occurred.
[0010]
Accordingly, in view of the above problems, the present invention is a cylindrical ignition coil for an internal combustion engine that is mounted in a plug hole of an engine and supplies a high voltage to the spark plug, and is excellent in heat dissipation, and excellent in assembly and durability. An object is to provide an ignition coil.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is configured as follows. That is, according to the first aspect of the present invention, a cylindrical case, a central iron core, a secondary coil, a primary coil, and an exterior iron core are accommodated coaxially with respect to the central iron core in the case, and the primary coil Is formed by winding a primary copper wire around the outer peripheral surface of the tower portion, and in the ignition coil formed by assembling the tower so as to penetrate the case, at least the body portion of the case is a metal body, An ignition coil for an internal combustion engine, wherein the lower end of the case portion is drawn .
[0012]
[Action]
As described in the above solution, an ignition coil excellent in heat dissipation and durability can be provided by making the case made of a conventional resin metal. Further, by drawing the case, it is possible to easily form the ignition coil and reduce the energy loss without requiring a complicated metal processing step. In addition, due to the drawing process, the tolerance is easily adjusted when the case and the tower portion are fitted, and both the case and the tower portion can be integrated with a sealing property without using an O-ring. -Since the ring can be eliminated, the assembly process can be simplified and the cost can be reduced.
[0013]
【Example】
An embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of a cylindrical ignition coil for an internal combustion engine showing an embodiment in which the end of a case to which the technique of the present invention is applied is drawn. FIG. 2 is a diagram before the tower portion of the cylindrical ignition coil for the internal combustion engine representing the embodiment to which the technology of the present invention is applied and the tower portion indicating the assembly direction of the case penetrate the case . FIG. 3 is an enlarged cross-sectional view illustrating a fitting state of the protrusions of the tower portion after the tower portion and the case of FIG. 2 are assembled.
[0014]
1 to 3, the embodiment of the present invention includes an outer case and a tower part that is mounted in the outer case and assembles a primary coil and a secondary coil. This configuration will be described in detail with reference to FIGS. 1 to 3. The case 111 is formed of a metal material such as aluminum, iron, or stainless steel, and has a cylindrical shape with a large opening at the top and an opening at the bottom of the cylinder. Is formed. Further, the tower portion 114 is formed by molding a metal material in the same manner as the case 11, and includes a primary coil 115 in which a primary copper wire is wound around the outer peripheral surface 114u of the tower portion. A plurality of sections are provided from one end to one end, and a secondary coil 117 in which a secondary copper wire is wound around a secondary bobbin 116 in which each section is laminated and a central iron core 118 formed of a silicon steel plate or the like. And are arranged. In addition, a primary voltage input unit 112 that supplies a power supply voltage to the primary coil 115 is mounted in the upper storage unit 111b of the case 111, and an igniter 113 that turns on and off the primary current is stored in the upper storage unit 111b. To do. Further, a portion 141 obtained by drawing the case 111 is provided at the lower end of the cylindrical portion of the case 111 so that the case 111 and the tower portion 114 can be sealed. Further, the drawing process may be performed on one or both of the upper end and the lower end of the case 111. Thereby, the case 111 and the tower part 114 can be more reliably sealed.
[0015]
As described in the prior art, the cylindrical portion of the case 111 may be provided with a positioning portion such as an engagement protrusion of the tower portion or a hole that fits into the hole. In this case, at least one pair of concave bosses or convex boss-like protrusions may be formed on at least one end of the case 111 at a circumferentially-corresponding position so as to be positioned and fitted with the tower 114 and the bobbin assembled. .
[0016]
Whether the case 111 is made of non-ferrous material such as aluminum or stainless steel or steel such as iron is determined by the required specifications of the engine, but if non-ferrous metal is used, the weight can be reduced. It is possible, and the use of steel-based magnetic metal can reduce the exterior iron core, and at the same time, there is little change in performance after installation in the plug hole of the engine, and it can be designed to have a smaller diameter. There is.
[0017]
Further, the central iron core 118 and the secondary coil 117 coaxially with the central iron core 118 are disposed in the primary coil 115, and secondary bobbins 1116 are secondary to both ends of the central iron core 118. In order to suppress the saturation of the magnetic flux of the iron core in the secondary coil 117 wound around the copper wire, permanent magnets 121 that generate a magnetic flux in the opposite direction to the magnetic flux generated in the primary coil 115 are attached to both ends, and ignition energy is supplied. In some cases, it may be increased. These are referred to as a primary coil assembly 110.
[0018]
The bottom of the tower 114 is provided with a secondary high voltage terminal 122 on the inner bottom of the tower 114 in order to supply a high voltage generated by the secondary coil 117 to a spark plug (not shown).
[0019]
Next, when assembling the above-described primary coil assembly 110 to the case 111, the case 111 and the tower portion are inserted by drawing processing 141 that is inserted from the upper opening of the case 111 and provided at the lower end of the cylindrical portion of the case 111. At the same time, the primary voltage input unit 112 and the primary coil assembly 110 are electrically connected. Further, the secondary high voltage terminal 122 is electrically connected to a conductive spring 123, and rubber or the like having excellent electrical insulation so that a high voltage does not leak to a metal part such as a plug hole (not shown) at the bottom of the tower part 114. The protector 125 molded in step 1 is attached to cover the spring 123. Further, by injecting and filling an insulating casting material from the opening in the upper portion of the case 111 and curing and insulatingly sealing, the joining by assembling the case 111 and the tower portion 114 can be fixed and integrated by the insulating casting material. . Such integration of the case 111 and the tower portion 114 may be integrated by caulking.
[0020]
In the above configuration, the drawing 141 provided at the lower end of the case 111 may be performed by a drawing process such as drawing or caulking after the tower 114 is assembled. In this case, a conventional seal such as an O-ring is used. Although the material can be omitted, a simple sealing material may be provided for the convenience of the manufacturing process. The cylindrical case 111 may be processed by stepwise pressing from a flat plate or drawing from a cylindrical cutting material.
[0021]
During the ignition coil operation, the primary current is supplied to the primary coil 115 from the primary voltage input unit 112 by the ON operation of the igniter 113, and the primary current that has been supplied by the OFF operation of the igniter 113 at the ignition timing. , The magnetic energy generated in the primary coil 115 propagates through the central iron core 118 and the outer iron core 119, and a high voltage corresponding to the turn ratio of the primary coil 115 and the secondary coil 117 is 2. It occurs in the next coil 117. The generated high voltage is sent from the secondary coil to the ignition plug (not shown) connected to the spring 123 through the secondary high voltage terminal 122 and the spring 1123.
[0022]
In the above embodiment, the primary coil 115 is wound around the outer peripheral surface 114u of the tower portion. However, this configuration can be applied to a coil assembly structure in which the primary bobbin is an individual configuration. In other words, any other configuration can be used as long as the coil portion and the case portion are formed in different configurations and the ignition coil is assembled and resin-molded by mounting the components. In addition, the case is made of a metal material and is formed by drawing that is easy to deform, so it can be joined to the shape of engine blocks, heads, and plug holes with complex shapes in recent times. An easy case is obtained.
[0023]
【The invention's effect】
As described above, as in the present invention, the case or tower portion made of a conventional resin or both of them are made of metal, thereby providing a small-diameter ignition coil excellent in heat dissipation and durability. Further, by drawing the case, it is possible to easily form the ignition coil and reduce the energy loss without requiring a complicated metal processing step. In addition, due to the drawing process, the tolerance is easily adjusted when the case and the tower part are fitted.
[0024]
In addition, due to the recent complication of the engine head shape, the metal material can be easily drawn even if the plug hole is not a straight shape. Therefore, the case 111 can be deformed according to the shape of the plug hole and the engine head. An ignition coil that can be easily molded and has excellent versatility can be provided.
[0025]
Furthermore, the ignition coil is not easily affected by the material of the engine head, and has a higher strength than the resin case 111 and the tower portion 114, and can provide a product with a small diameter along the shape of a plug hole or the like. In addition, by performing drawing processing and caulking processing after forming the ignition coil itself, it is not necessary to use a special sealing material such as an O-ring. The assembly process can be simplified and the cost can be reduced. Also, drawing and caulking can be done by assembling the product once and then pressing, etc., so it is possible to easily deform the outer shape, which was not possible after molding the resin in the past, and match the desired shape An ignition coil can be easily produced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a cylindrical ignition coil for an internal combustion engine showing an embodiment in which an end of a case to which the technology of the present invention is applied is drawn.
FIG. 2 is a diagram showing an assembling direction of a tower portion and a case of a cylindrical ignition coil for an internal combustion engine that represents an embodiment to which the technology of the present invention is applied.
FIG. 3 is an enlarged cross-sectional view illustrating a fitting state of protrusions of the tower portion after the tower portion and the case of FIG. 2 are assembled.
FIG. 4 is a longitudinal sectional view of a cylindrical ignition coil for an internal combustion engine to which a conventional technique is applied.
FIG. 5 is a view showing an assembling direction of a tower portion and a case of a cylindrical ignition coil for an internal combustion engine to which a conventional technique is applied.
6 is an enlarged cross-sectional view illustrating a fitting state of a protruding portion of the tower portion after the tower portion and the case of FIG. 5 are assembled.
[Explanation of symbols]
In the drawings, the same reference numerals indicate the same or corresponding parts.
DESCRIPTION OF SYMBOLS 10 Primary coil assembly 11 Case 11b Upper accommodating part 11d Hole 21 Primary voltage input part 13 Igniter 14 Tower part 14u Tower part outer peripheral surface 14t Engagement protrusion 15 Primary coil 16 Secondary bobbin 17 Secondary coil 18 Central iron core 19 Exterior iron core 21 Permanent magnet 22 Secondary high voltage terminal 23 Spring 25 Protector part 41 O-ring 110 Primary coil assembly 111 Case 111b Upper storage part 112 Primary voltage input part 113 Igniter 114 Tower part 114u Tower part outer peripheral surface 115 Primary Coil 116 Secondary bobbin 117 Secondary coil 118 Center iron core 119 Exterior iron core 121 Permanent magnet 122 Secondary high voltage terminal 123 Spring 125 Protector part 141 Part subjected to drawing processing

Claims (1)

A cylindrical case, and a secondary coil, a primary coil, and an exterior iron core are accommodated coaxially with respect to the central iron core and the central iron core in the case, and the primary coil towers the primary copper wire In the ignition coil formed by winding around the outer peripheral surface of the part and the tower being assembled so as to penetrate the case, at least the body part of the case is made of a metal body, and the lower end of the case part is drawn. ignition coil, characterized in that subjected to.

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