JP2518587Y2 - Plug socket for spark plug - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a case where each ignition plug of an internal combustion engine for a vehicle is provided with a dedicated ignition coil, and the physical arrangement between the ignition coil and the ignition plug is used. The present invention relates to an improvement of a plug socket used for securely connecting the ignition coil and the spark plug mechanically and electrically when the distance is considerably long.

[0002]

2. Description of the Related Art Recently, as described above, an ignition mechanism called a so-called one-plug one-coil method or a low-voltage distribution method for an ignition coil is preferred. This is because, in principle, the high-voltage wiring on the secondary side of the ignition coil, which becomes an antenna for electromagnetic noise, can be omitted.
This is because the adverse effect on the electronic device can be avoided and the burden on the wiring system is reduced. On the other hand, on the other hand, particularly in the recent internal combustion engine that adopts the double overhead camshaft system, in order to achieve higher intake and exhaust efficiency for further fuel efficiency reduction, the valve holding angle of the engine head is reduced, The intake / exhaust valve should move closer to the same direction as the piston's moving direction to further reduce the intake / exhaust resistance, resulting in an increase in the thickness of the engine head, which should be attached directly to the spark plug. Increasingly, the physical distance between the ignition coil and the coil is considerably long.

Therefore, a plug socket 1 as shown in FIG. 3 has been conventionally made and used as an attachment in such a case. To explain, there is a suitable synthetic resin or rubber head 2, which is mounted on the surface of the internal combustion engine by covering and covering the opening of a blind hole for accommodating the spark plug. The ignition coil 5 is also attached to the head 2, which is usually called simply a cap. That is, in the illustrated case, there is a resin-made mounting member 7 that covers the periphery of the secondary-side high-voltage terminal member 6 of the ignition coil 5,
This penetrates into the axial through hole opened in the head 2,
It is designed to snap fit. Also on the head 2
One end of the resin-molded long bar-shaped trunk portion 3 is fixed by force fitting, snap fitting, or the like.
At the other end, a tip portion 4 made of rubber or resin is fixed by force fitting or snap fitting. The tip portion 4 is generally called a boot or the like, and has a function of engaging with a head portion of an ignition plug (not shown) in a through hole inside thereof, and particularly having a function of closely contacting and sealing the insulator portion. The trunk portion 3 has a long metal rod 8 in an axial through hole therein by a so-called insert molding technique, and a first coil spring is provided between one end side thereof and the high voltage terminal member 6 of the ignition coil 5. 9 is arranged, and the second coil spring 10 is arranged between the other end side and the high-voltage terminal (not shown) of the spark plug head coming into the tip portion 4 or the rubber boot 4. The high voltage generated in the high voltage terminal member 6 of the ignition coil 5 can be applied to the head of the ignition plug through the elongated metal rod 8. Of course, these coil springs 9 and 10 are used to allow dimensional errors as expected, and to prevent the electrical connection between the ignition coil and the ignition plug from being ambiguous even when subjected to vibration or the like. Has been.

[0004]

In the conventional plug socket 1 as described above, the length of the trunk portion 3 is adjusted according to the distance between the ignition coil 5 and the ignition plug. In other words, as it becomes longer, the length of the elongated metal rod 8 accommodated in the trunk portion 3 also becomes longer. For this reason, the weight of the plug socket 1 itself as a part may be considerably heavy, which is not preferable for a vehicle policy in which a drastic reduction in fuel consumption is recently required again.
Further, the long metal rod 8 itself is expensive, and the insert molding of the long metal rod 8 increases the manufacturing time and the cost. Furthermore, since the high-voltage secondary wiring can be omitted originally, one ignition coil 5 is provided for each ignition plug, but the length of the long metal rod 8 is increased. When it becomes longer, it becomes an antenna for electromagnetic noise radiation, and the effect of reducing electromagnetic noise radiation, which is one of the advantages of the low-voltage power distribution system, may be impaired. In view of this point, the present invention provides a lighter and cheaper plug socket, and further provides a plug socket that can be expected to suppress electromagnetic noise.

[0005]

In order to achieve the above object, the present invention replaces the long metal rod 8 and the pair of coil springs 9 and 10 which are conventionally used, and replaces the high voltage terminal member of the ignition coil and the ignition plug. In order to electrically connect between the head high voltage terminals, as a long conductive member provided in the trunk,
We propose to use only long metal coil springs over the entire length from one end to the other.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an embodiment of a plug socket 20 constructed according to the present invention. However, since the present invention is substantially an improvement in the conductive member provided in the plug socket of this kind, various structures and materials in the existing plug socket of this kind are arbitrarily used for other parts. I don't mind. Therefore, also in the drawings, only the portions improved by the present invention are denoted by the reference numerals different from those of the conventional example described above, and the other portions are denoted by the same reference numerals as those of the conventional example with respect to the corresponding components. Is attached.

Conventionally, as described above, the conductive member provided inside the trunk portion 3 is a long metal rod 8 and a pair of coil springs 9 and 1 provided at both ends thereof.
However, in the present invention, it is composed only of the elongated metal coil spring 21.
That is, in the axial through hole of the trunk portion 3, only one metal coil spring 21 is inserted so as to pass from the one end opening to the other end opening, and one end of the coil spring 21 is directly inserted. High voltage terminal member 6 of ignition coil 5
And the other end is also directly in pressure contact with the head high-voltage terminal of the spark plug (not shown).

Therefore, if the same length is compared,
Compared to the case where the conductive member with the built-in stem is composed of the elongated metal rod 8 and the pair of coil springs 9 and 10 as in the conventional example, the plug socket 2 constructed according to the present invention
0 significantly reduces the weight. In terms of cost, the coil spring 21 is much cheaper as a component than the case where the metal rod 8 is used, and the insert molding of the metal rod 8 into the trunk portion 3 is not necessary. Since the separately manufactured coil spring 21 may be pushed into the axial through hole formed in the trunk portion 3, it is also inexpensive in that sense.

Further, in order to prevent the coil spring 21 from falling off from the axial through hole of the trunk portion 3 inadequately, as shown in FIG. 1, both end portions of the coil spring 21 are Even if formed into a slightly smaller diameter, at least a part of the part that fits inside the trunk (in the case of the figure, especially the central part in the longitudinal direction) is about the same as the inner diameter of the axial through hole of the trunk, or slightly thicker. You can leave it as it is. If the tip is thin, the insertion work of the coil spring 21 into the trunk through hole becomes easy, and if at least a part in the middle in the length direction is thick, the inner wall surface of the trunk through hole and the coil spring 21 are Due to the contact frictional force, a temporary holding function of the coil spring 21 is generated, and it is possible to prevent the inconvenience of the coil spring 21 slipping off the trunk portion 3 in a bypass.

However, such a structural attachment method itself is not directly defined by the present invention, and is a problem that a mechanical mechanism design engineer of this kind is left to arbitrary design. . As a matter of course, a structural portion other than the portion directly targeted for improvement by the present invention, for example, a connection relationship or material between the head 2 and the trunk portion 3, a connection relationship between the trunk portion 3 and the tip portion 4 or a material, or a so-called cap. The shape itself of the head 2 and the tip 4 as a so-called boot is also an arbitrary problem. Depending on the case, as a combination relationship of each component,
The head portion 2 and the stem portion 3, or the stem portion 3 and the tip portion 4, or the head portion 2, the stem portion 3, and the tip portion 4 may all be integrally resin-molded. The fitting relationship between the ignition coil 5 and the head 2 may be appropriate.

However, according to the present invention, in addition to the above-mentioned structural simplicity and low cost, the physical distance between the ignition coil and the ignition plug is increased, and as a result, the length of the high voltage line is also increased. Even if the length becomes long, it is possible to obtain an electrical effect that the risk of electromagnetic radiation noise can be reduced. This can be explained as follows.

For example, when the conventional plug socket 1 shown in FIG. 3 is used, the equivalent circuit on the secondary side of the ignition coil is as shown in FIG. Here, assuming that the primary inductance of the ignition coil 5 is L ₁ , the secondary side inductance is L ₂ , the secondary side stray capacitance is C ₂ , and the ignition plug is an insulation resistance R _L and a stray capacitance C _L , this secondary side The resonance frequency f _{01 of the} closed loop is expressed by f ₀₁ = 1 / 2π {L ₂ · (C ₂ + C _L )} ^1/2 (1). On the other hand, in the plug socket 20 constructed according to the present invention, the long coil spring 2
1 is expected to have a sufficiently significant inductance L _P , the secondary side equivalent circuit of the ignition coil 5 is as shown in FIG. 2, and the ignition coil secondary side high voltage terminal and the high voltage terminal of the ignition plug head are shown. the inductance L _P is assumed interposed in series between. As a result, the resonance frequency f ₀₀ of this secondary side closed loop is f ₀₀ = 1 / 2π {(L _P + L ₂ ) · (C ₂ + C _L )} ^1/2 ... (2) Represented by

As is clear from the above equations (1) and (2),
If the other constant groups are the same, the resonance frequency f ₀₀ in the ignition coil secondary side equivalent circuit when the plug socket 20 constructed according to the present invention is used is the conventional plug socket using a metal rod. It becomes lower than the resonance frequency f ₀₁ when 1 is used. Therefore, considering the spread of the bottom of the resonance characteristic, the plug socket 2 according to the present invention
At 0, so to speak, an effect similar to that of providing a low-pass filter can be obtained, and the radiation of high-frequency electromagnetic noise is reduced accordingly. This effect is desirable because the longer the coil spring 21 is, the higher the effect is. In the conventional example, as a matter of course, as the length of the metal rod 8 becomes longer, the fear of electromagnetic noise radiation becomes proportionally higher. As the length of 21 increases, the inductance L _P
Is increased.

[0014]

According to the present invention, the weight of the plug socket can be greatly reduced, and the cost can be reduced by reducing the number of parts and the manufacturing process. Not only that, even if the distance between the ignition coil and the spark plug becomes long, the generation of high-frequency electromagnetic radiation noise can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a spark plug plug socket according to an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of an ignition coil secondary side when the plug socket shown in FIG. 1 is used.

FIG. 3 is a schematic cross-sectional view of a conventionally used spark plug plug socket.

FIG. 4 is an equivalent circuit diagram on the secondary side of the ignition coil when a conventional plug socket is used.

[Explanation of symbols]

 2 plug socket head, 3 plug socket trunk, 4 plug socket tip, 5 ignition coil, 6 high voltage terminal member of ignition coil, 20 overall plug socket according to the present invention, 21 metal coil spring as long conductive member ．

Claims (2)

(57) [Scope of utility model registration request] 1. A head made of resin or rubber that engages with a surface portion of an internal combustion engine and receives a high-voltage terminal member of an ignition coil, a tip made of resin or rubber that engages with an ignition plug, and the tip. And a long rod-shaped trunk made of resin for connecting between the head and the head, and inside the trunk, one end thereof electrically contacts the high-voltage terminal member of the ignition coil, and the other end Is a plug socket for an ignition plug, which is formed by axially accommodating a long conductive member that makes electrical contact with the head high-voltage terminal of the spark plug; the conductive member extending from the one end to the other end. A plug socket for an ignition plug, characterized in that it is constituted only by a long metal coil spring over the entire length. 2. The plug socket for an ignition plug according to claim 1, wherein the coil spring has a relatively small diameter in the vicinity of one end and the other end extending beyond the length of the trunk portion. However, at least a part of the portion that fits inside the trunk portion is about the same as or slightly thicker than the inner diameter of the axial through hole of the trunk portion through which the coil spring is passed; Plug socket.