JP4845854B2 - Ignition coil for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition coil for supplying a high voltage to generate a spark discharge in an ignition plug (not shown) attached to an engine head of an internal combustion engine, and more particularly to an ignition coil disposed in an ignition plug mounting hole of an engine head. The present invention relates to an ignition coil for an internal combustion engine of a type including a high-pressure conductor pipe that electrically and mechanically connects a terminal of an ignition coil body fixed to an inlet portion of a plug mounting hole and a terminal of an ignition plug inserted into an engine cylinder. .

  This type of internal combustion engine ignition coil, as disclosed in Japanese Patent Application Laid-Open No. 2001-221140 (particularly FIG. 5), has an ignition coil case, and an iron core is disposed in the ignition coil case, and the primary coil is The wound primary bobbin and the secondary bobbin around which the secondary coil is wound are arranged so as to surround the iron core, and are insulated with an insulating and cured resin filled in the coil case.

  The ignition coil case is provided with a high-voltage tower as a high-voltage output terminal, and this high-voltage tower is inserted into the coil-side connection terminal of the high-voltage conductor pipe inserted into the plug hole to electrically connect the two. In addition, the ignition coil case and the high-pressure conductor pipe are mechanically coupled.

  The other end of the high-voltage conductor pipe is provided with a plug-side connection terminal for electrical connection to a terminal of a plug attached to the cylinder head.

  In the case of an engine in which the distance between the ignition coil body and the ignition plug is different, the ignition coil body can be commonly used for a plurality of engines by connecting high-pressure conductor pipes having different lengths.

  The connection between the high-voltage conductor pipe and the high-voltage tower portion is configured such that the high-pressure conductor-side end portion of the high-pressure conductor pipe is connected to the other end portion of the connection rubber having one end inserted into the high-pressure tower portion.

JP 2001-221140 A

  In the conventional connection rubber, the stepped shape portion for retaining the high-pressure tower portion and the stepped shape portion for retaining the high-pressure conductor pipe are arranged in series in the axial direction on the inner peripheral surface of the connection rubber.

  With this configuration, the contact area in the axial direction of the connecting rubber and the high-voltage tower portion and the insertion portion of the connecting rubber and the high-pressure conductor pipe is insufficient, and it is difficult to obtain a sufficient retaining effect.

  It is an object of the present invention to sufficiently obtain the effect of preventing the connection rubber and the high-voltage tower portion and the insertion portion of the connection rubber and the high-pressure conductor pipe from coming off.

  More specific functions and effects will become apparent from the description of the embodiments.

  The present invention is configured such that the insertion coupling portion between the high-voltage tower portion and the high-voltage conductor pipe wraps in the radial direction, and the connecting rubber is provided in the radial wrapping portion of the insertion coupling portion between the high-voltage tower portion and the high-voltage conductor pipe. I intervened.

  In the ignition coil configured as described above, a sufficient contact area in the axial direction of the connecting portion between the high voltage tower of the ignition coil and the high voltage conductor pipe can be obtained, so that an ignition coil having a high retaining effect can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2 show an embodiment of an ignition coil for an internal combustion engine according to the present invention. FIG. 1 is a sectional view of an ignition coil for an internal combustion engine, and FIG. 2 is a sectional view of a connection rubber.

  In FIG. 1, an internal combustion engine ignition coil 1 is an independent ignition internal combustion engine ignition coil that is attached to a plug hole of each cylinder of an internal combustion engine and is directly connected to the ignition plug. The internal combustion engine ignition coil 1 has an iron core 6, which is formed in an EI shape and constitutes a magnetic circuit. This iron core 6 forms a magnetic path that forms a closed magnetic path by press-lamination of 0.2 to 0.7 mm silicon steel plates.

  The iron core 6 is housed in the primary bobbin 2 as shown in FIG. The primary bobbin 2 disposed on the outer peripheral side of the iron core 6 and containing the iron core 6 is formed of a thermoplastic synthetic resin. A primary coil 3 is wound on the primary bobbin 2 and stored on the primary bobbin 2. The primary coil 3 is formed by laminating and winding an enameled wire having a wire diameter of about 0.3 to 1.0 mm around the primary bobbin 2 several tens of times per layer, for a total of several hundred to three hundred times.

  A secondary bobbin 4 is disposed on the outer periphery of the primary bobbin 2 with a gap. The secondary bobbin 4 is formed of a thermoplastic synthetic resin in the same manner as the primary bobbin 2, and the secondary bobbin 4 is formed with a plurality of winding grooves. A secondary coil 5 is wound on the secondary bobbin 4 and stored on the primary bobbin 2. The secondary coil 5 is formed by being divided and wound around the secondary bobbin 4 by a total of about 5,000 to 30,000 times using an enameled wire having a wire diameter of about 0.03 to 0.1 mm. As described above, the primary bobbin 2 is inserted inside the secondary bobbin 4. The primary coil 3 wound around the primary bobbin 2 and the secondary coil 5 wound around the secondary bobbin 4 are housed in a coil case 7 formed of thermoplastic synthetic resin.

  Moreover, the electric power supplied to the primary coil 3 is supplied through the terminal 8, and a connector is connected to the terminal 8 although not shown. On the other hand, a high voltage terminal 9 is connected to the secondary coil 5. The secondary coil 5 is induced with a high voltage for generating a spark discharge in the spark plug when the primary coil 3 is energized. The high voltage induced in the secondary coil 5 is supplied to the spark plug via the high-voltage terminal 9, and the spark plug generates a spark discharge upon receiving the high voltage induced in the secondary coil 5.

  The coil case 7 in which the primary coil 3 wound around the primary bobbin 2 and the secondary coil 5 wound around the secondary bobbin 4 are housed is an insulating resin made of a thermosetting resin. (Specifically, epoxy resin) 10 is enclosed. This insulating resin (specifically, epoxy resin) 10 is formed between the inside of the coil case 7, the primary coil 3 wound around the primary bobbin 2, and the secondary coil 5 wound around the secondary bobbin 4. The gap is filled and the insulating resin (specifically, epoxy resin) 10 is cured to insulate the primary coil 3 and the secondary coil 5. Thus, in the coil case 7, the primary coil 3, the secondary coil 5, the primary bobbin 2, and the secondary bobbin 4 are insulated, fixed, and integrated by the insulating resin (specifically, epoxy resin) 10. Is housed.

  The coil case 7 has a high-voltage tower portion 7a for mechanically connecting the high-pressure conductor pipe 11. The high-pressure tower portion 7a has a cylindrical portion with a small diameter on the coil case 7 side, and has a cylindrical portion with a large diameter on the tip side. The small diameter part and the large diameter part form a stepped shape on the outer periphery thereof, and the connecting rubber 12 is hooked on the stepped part. Specifically, the stepped portion is a stepped portion that is enlarged by about 0.5 mm to 2 mm in diameter with respect to the diameter of the base of the high-pressure tower portion 7a (the diameter on the coil side).

  The connecting rubber 12 formed of an elastic body includes an inner peripheral cylindrical portion 12a having an inner peripheral surface having the same shape as the outer peripheral shape of the high-pressure tower portion 7a, and is fitted on the outer periphery of the high-pressure tower portion 7a.

  Further, the connecting rubber 12 is provided with a cylindrical groove 12b inserted outside the inner peripheral cylindrical portion 12a into which the insulating pipe 13 constituting the high-pressure conductor pipe 11 formed of thermoplastic synthetic resin is inserted. The groove 12b is deeper than the stepped portion of the high-pressure tower portion 7a so that the insulating pipe 13 can be inserted to a position surrounding the outer periphery of the small-diameter portion of the high-pressure tower portion on the coil case 7 side.

  The inner diameter of the cylindrical groove 12b is equal to or larger than the inner diameter of the insulating pipe 13, and when the insulating pipe 13 is inserted into the connecting rubber 12, the inside of the connecting rubber 12 is pressed against the high-pressure tower portion 7a. Yes.

  In this embodiment, the insulating pipe 13 is inserted into the connecting rubber 12 up to the upper part of the coil case side from the stepped part of the high pressure tower part 7a to the periphery of the narrow diameter part, so that the ignition coil as shown in FIG. Even if an external force is applied so that the main body and the high-voltage conductor pipe 11 are separated from each other, the insulating pipe 13 is located on the outer peripheral side where the connection rubber usually swells and the ignition coil main body and the high-voltage conductor pipe 11 come off. Since the insulating pipe 13 prevents the small diameter portion 12c of the connecting rubber 12 from expanding, the ignition coil body and the high-voltage conductor pipe 11 are difficult to come off. Further, since the insulating pipe 13 is inserted closer to the ignition coil side than the stepped shape of the connection rubber 12, there is no thick portion of the connection rubber 12, the amount of the elastic body used is reduced, and the weight and cost are reduced. . Furthermore, since a complicated shape is not provided in the inner peripheral cylindrical portion 12a of the connection rubber 12, the mold structure is simplified and the molding can be facilitated.

  Note that the inner cylindrical portion 12a and the outer cylindrical portion of the connection rubber 12 do not necessarily have to be integrally formed, and the coupling force (prevention force) between the insulating pipe 13 of the high-pressure conductor pipe 11 and the high-pressure tower portion 7a. If it is obtained, only the inner peripheral cylindrical portion 12a may be used.

  When it is necessary to seal the plug hole with the connecting rubber 12, the sealing function portion is formed integrally with the inner peripheral cylindrical portion 12a, and the sealing function of the connecting rubber 12 is provided between the outer periphery of the insulating pipe 13 and the plug hole. The part may be located.

  When attaching the high-voltage conductor pipe 11 to the ignition coil body, the connection rubber 12 is attached to the ignition coil body, and then the insulating pipe 13 is inserted into the cylindrical groove 12 b of the connection rubber 12. In FIG. 2, an annular groove 12d is provided in the cylindrical groove 12b of the connecting rubber 12, and when the insulating pipe 13 is inserted, the annular protrusion provided on the outer periphery of the insulating pipe 13 matches this to constitute a retaining structure. However, the connecting rubber 12 and the insulating pipe 13 may be bonded by an adhesive (for example, a silicone-based adhesive) without providing the annular groove 12d.

  As shown in FIG. 1, a spring 14 is installed in the high-pressure conductor pipe 11 to electrically connect the ignition coil body to the ignition plug. The spring 14 has a densely wound portion and a coarsely wound portion, and a high magnetic flux density material (for example, ferrite) 15 exists inside the spring 14. The main factor of noise generated by the ignition coil 1 is generated by a sudden change in current that flows when high-pressure discharge is performed by the spark plug. By making the spring 14 tightly wound and providing the high magnetic flux density material 15 on the inner periphery, the inductance of the spring 14 is increased, and the current that flows suddenly at the time of high-pressure discharge generated by the spark plug is prevented from being disturbed. The self-induction action of the spring 14 works, and a magnetic flux Φ is generated from the spring 14 as shown in FIG. 4 (Φ = −dI / dt). Thus, by the self-induction of the spring 14, it becomes possible to suppress the generation of a rapid high current, and it is possible to reduce the generation of noise. Furthermore, by making the spring 14 tightly wound, the resistance of the spring 14 can be increased, the current during high-voltage discharge can be reduced, and noise can be reduced. Further, the coarsely wound portion of the spring 14 is provided so that the ignition coil main body and the ignition plug are reliably electrically connected to vibration received from the engine.

  The mode of implementation of this example is summarized as follows.

Problems to be Solved by the Example The conventional connection rubber in the ignition coil for an internal combustion engine is mechanically connected to the case tower, so the case tower has a stepped shape, and the inner periphery of the connection rubber is The shape of the high-pressure tower is the same as that of the high-voltage tower, and the connecting rubber at the location that fits on the ignition coil side is thicker than the stepped shape of the high-voltage tower that is provided so that the ignition coil body is difficult to come out. The insulating pipe is inserted into a groove outside the inner periphery of the connecting rubber, and the depth of the groove extends from the stepped shape part of the high-pressure tower part to the spark plug side when the insulating pipe is connected to the connecting rubber. The depth of the.

  In other words, in a normal ignition coil, the position where the insulation pipe is inserted into the connection rubber exists on the ignition plug side of the stepped shape of the high pressure tower, so the connection rubber is located above the stepped shape of the high pressure tower. However, if an external force is applied that causes the ignition coil body and the high-pressure conductor pipe 11 to be separated, the connecting rubber may swell in the outer circumferential direction, and the ignition coil body and the high-voltage tower may come off. For this reason, the thickness of the upper side of the connecting rubber high-pressure tower stepped shape is formed to increase the rigidity of the connecting rubber so that the coil body and the high-voltage conductor pipe are difficult to come off.

  The connecting rubber structure as described above has a stepped shape on the inner peripheral side of the connecting rubber in accordance with the stepped shape of the high pressure tower, and the tip of the high pressure tower is thinner than the maximum outer shape of the stepped shape. Therefore, the mold structure when molding the connection rubber and the process of taking out the product after molding become complicated, and molding becomes difficult. In addition, the mold life is shortened because of the complicated mold structure. Furthermore, since the shape on the ignition coil side is thicker than the stepped shape, the material used for the elastic body is large, the weight is large, and the cost is high.

  Further, in order to mechanically connect the anti-noise resistor, a terminal or a portion for fixing the anti-noise resistor is required on both sides of the anti-noise resistor, which increases the number of parts and increases the cost.

  The problem to be solved by the present embodiment is to provide an ignition coil having a noise reduction structure in which the shape of the connecting rubber is simplified and the number of parts is reduced.

Embodiment 1
An iron core that forms a closed magnetic circuit with an air gap, a primary coil wound around the iron core, an ignition coil body including a secondary coil, and a high voltage supplied from the ignition coil body can be attached to the engine head. A high pressure conductor pipe for supplying to the spark plug, the high pressure conductor pipe is composed of a connecting rubber made of an elastic body, an insulating pipe made of a thermoplastic resin, and a boot connected to the spark plug. The ignition coil body and the high pressure conductor pipe Is an ignition coil for an internal combustion engine mechanically connected by a connection rubber,
The position of the high-pressure tower part and the insulation pipe mechanically connected to the connection rubber of the insulation case that houses the iron core, primary coil, and secondary coil connected to the connection rubber is higher than the stepped shape of the high-pressure tower part. An ignition coil for an internal combustion engine, wherein the connection rubber is inserted to the ignition coil side.

Embodiment 2
In the first embodiment, the spring for transmitting the high voltage generated by the ignition coil body in the high-pressure conductor pipe to the ignition plug is a material having a high magnetic flux density in which the surface of the spring is insulated on the inner periphery of the spring by combining dense winding and rough winding. For example, an ignition coil for an internal combustion engine in which ferrite or a silicon steel plate is disposed.

Embodiment 3
Further, as a method for reducing noise, not the structure as described above, but a resistor (for example, resin resistor and amorphous) having a freedom of shape is directly fixed to the insulating pipe 13 (for example, press-fit, screw structure) and the spring 14 is electrically connected. It may be a structure that is connected to each other.

Effects of the Examples The effects of the above examples are as follows.

  According to the present embodiment, since the connecting rubber shape can be simplified, it is possible to reduce the weight and cost of the ignition coil. Moreover, since it is possible to reduce noise with a small number of parts, it is possible to simplify the manufacturing process.

1 is a cross-sectional view showing one embodiment of an internal combustion engine ignition coil according to the present invention. Sectional drawing which shows one Example of the connection rubber which concerns on this invention. The figure which shows the state at the time of coil case removal. The figure which shows the magnetic flux which generate | occur | produces in a spring by a self-induction at the time of high voltage | pressure discharge generation | occurrence | production by an ignition plug.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ignition coil 2 Primary bobbin 3 Primary coil 4 Secondary bobbin 5 Secondary coil 6 Iron core 7 Coil case 7a High voltage tower part 8 Terminal 9 High voltage terminal 10 Insulation resin 11 High pressure conductor pipe 12 Connection rubber 12a Inner peripheral cylindrical part 12b Tube Groove 12c small diameter portion 12d annular groove 13 insulating pipe 14 spring 15 high magnetic flux density material 16 high voltage terminal (2)
17 Spring (2)
18 Boots

Claims (5)

Ignition coil case,
An iron core disposed in the ignition coil case,
A primary bobbin wound with a primary coil,
A secondary bobbin wound with a secondary coil,
Insulation hardening resin that insulates the primary bobbin and the secondary bobbin that are filled in the ignition coil case and arranged to surround the iron core,
High voltage tower part as a high voltage output terminal part provided in the ignition coil case,
A high-pressure conductor pipe inserted into the plug hole and having one end electrically and mechanically coupled to the plug and the other end electrically and mechanically coupled to the high-voltage tower portion;
In the one provided with a connecting rubber provided at the joint between the high-voltage conductor pipe and the high-pressure tower part,
The high voltage tower part and the coupling part of the ignition coil side end part of the insulation pipe part of the high voltage conductor pipe are configured to wrap in the radial direction,
The connecting rubber is configured to be interposed in the radially wrapped portion of the coupling portion between the high voltage tower portion and the ignition coil side end portion of the insulating pipe portion of the high pressure conductor pipe ,
The high-pressure tower portion has a cylindrical portion with a small diameter on the coil case side, a cylindrical portion with a large diameter on the tip side, and the small-diameter portion and the large-diameter portion are the same as the high-pressure tower portion. A stepped shape is formed on the outer periphery,
The connecting rubber formed by the elastic body has an inner circumference that is the same shape as the outer circumference of the high-pressure tower.
An inner peripheral cylindrical portion having a surface;
The connecting rubber has a cylindrical shape in which an insulating pipe portion formed of a thermoplastic synthetic resin constituting a part of the high-pressure conductor pipe is inserted between the inner peripheral cylindrical portion and the outer peripheral cylindrical portion. A groove is provided,
The cylindrical groove is formed to a depth at which the insulating pipe portion can be inserted to a position surrounding the outer periphery of the portion having a smaller diameter of the high-pressure tower portion than the stepped portion of the high-pressure tower portion,
When the insulating pipe portion is inserted into the cylindrical groove of the connection rubber, the inner peripheral cylindrical portion of the connection rubber is sandwiched between the stepped shape portion of the high-pressure tower portion and the insulating pipe portion. An internal combustion engine ignition coil configured as described above . What is claimed in claim 1
The connection rubber includes a portion that covers an outer periphery of a joint portion between the high-pressure conductor pipe and the high-pressure tower portion, and a connection rubber interposed in a radially wrapped portion of the joint portion between the high-voltage tower portion and the high-voltage conductor pipe; An internal combustion engine ignition coil in which a connecting rubber portion covering the outer periphery of a high-pressure conductor pipe is integrally formed. In what is described in claim 2,
An ignition coil for an internal combustion engine, wherein a connecting rubber portion covering the outer periphery of the high-pressure conductor pipe constitutes a seal between the plug hole and the high-pressure conductor pipe. The method of claim 1, further comprising:
A spring that transmits a high voltage generated by the ignition coil in the high-pressure conductor pipe to the spark plug is provided.
The spring is closely wound on the ignition coil side and the spark plug side, and has a coarsely wound portion in the middle.
An ignition coil for an internal combustion engine, in which a metal rod made of a magnetic material whose surface is insulated is disposed on the inner periphery of the spring. The method of claim 1, further comprising:
A spring that transmits a high voltage generated by the ignition coil in the high-pressure conductor pipe to the spark plug is provided.
An ignition coil for an internal combustion engine, wherein a resin resistance material or amorphous material is press-fitted or screwed into the high-pressure conductor pipe and electrically connected to the spring.

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