JP3180007B2 - Plug cap for spark plug - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plug cap for a spark plug mounted on an engine for a vehicle, and more particularly to a plug cap for a spark plug used in an engine in which a spark plug is mounted deep inside an engine head cover. .

[0002]

2. Description of the Related Art In a so-called twin cam engine which has been widely used in recent years to cope with higher output and lower fuel consumption of the engine, a spark plug mounting hole provided in an engine body of the engine is provided. It can be installed deep inside. Therefore, as a plug cap for an ignition plug attached to such a twin cam engine, for example, there is one shown in FIG.

A plug cap 21 for an ignition plug covers a plug cap pipe 2 wrapping a high-voltage resistance wire 5 for noise prevention, and a connector (not shown) connected to the ignition plug 9 at the lower end of the plug cap pipe 2. Bushing 3 and hole 1 for mounting a spark plug at its upper end
And a rain cover 24 that covers the upper end opening of the “0”.
The plug cap pipe 2 is configured such that a connector portion can be freely inserted into and removed from an ignition plug 9 which is deeply mounted in an ignition plug mounting hole 10 formed by combining cylindrical openings formed in a cylinder head 17 and a cylinder head cover 16, respectively. The rain cover 24 is a cylindrical body made of hard resin to be inserted into the ignition plug mounting hole 1.
This is a rubber lid for sealing the upper end opening so that dust, water droplets and the like do not enter the inside of the housing from outside.

Further, the plug cap 2 for the ignition plug
Reference numeral 1 denotes a cover for covering the upper end of the spark plug mounting hole 10 with a flange-shaped sealing piece 28 of the rain cover 24, and a plug cap pipe such as a plug cap disclosed in Japanese Utility Model Laid-Open No. 4-135195. An O-ring 27, which is a rubber annular seal member having required heat resistance and pressure contact characteristics, is held in a holding groove 29 formed by a pair of annular flanges 32 and 33 provided above the O-ring 2.
The sealing surface 27a formed on the outer peripheral end of the ring 27 is in close contact with the inner peripheral surface of the spark plug mounting hole 10, thereby preventing the plug cap 21 from floating, preventing intrusion of water droplets and the like and half-fitting of terminals. Some sealing means are constructed.

That is, the outer diameter of the O-ring 27 is formed to be larger than the inner diameter D ₁ of the spark plug mounting hole 10, and the plug cap 21 is mounted in the spark plug mounting hole 10. At this time, the O-ring 27 is press-fitted into the spark plug mounting hole 10, and the thickness in the radial direction is uniformly reduced along the circumferential direction by an amount corresponding to the crushing.

[0006]

The noise preventing high-voltage resistance wire 5 in which the core wire is covered with a shield member or an insulating coating has high rigidity and is difficult to bend. Therefore, the noise-prevention high-voltage resistance wire 5 whose other end is connected to a distributor (not shown) and routed in the engine room,
A lateral load F (pressing or pulling) may act on the upper part of the plug cap 21 fitted in the spark plug mounting hole 10.

Therefore, in the case of the plug cap 21 in which the rubber annular sealing member as described above is fitted in the ignition plug mounting hole 10, when a load F is applied to the upper part of the plug cap 21 from the side. as shown in FIG. 6, the center line C ₂ of the plug cap 21 is tilted to the left side in the drawing with respect to the center line C ₁ of the spark plug mounting hole 10, a direction inclined opposite side (the right side in the drawing) A gap 30 may be formed between the sealing surface 27a of the O-ring 27 and the inner peripheral surface of the spark plug mounting hole 10.

That is, if the center line C ₂ of the plug cap 21 is inclined more than the overshooting amount, which is the amount of decrease in the radial thickness when the O-ring 27 is mounted in the spark plug mounting hole 10, A gap 30 is formed between the seal surface 27a of the O-ring 27 and the inner peripheral surface of the spark plug mounting hole 10, making it difficult to maintain good waterproofness. Accordingly, an object of the present invention is to solve the above-mentioned problem, and a gap is generated between the sealing means and the inner peripheral surface of the ignition plug mounting hole even when a load is applied to the upper portion of the plug cap from the side. It is an object of the present invention to provide a good spark plug plug cap which prevents the occurrence of water from entering from outside.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spark plug plug cap which is mounted in a spark plug mounting hole, wherein the sealing means fitted into the spark plug mounting hole comprises: O which is crimped to the inner peripheral surface of the mounting hole
Ring and, position projecting from the plug cap pipe to be formed between the inner peripheral surface of the crushed white smaller gap of the O-ring mounted in said mounting hole said spark plug mounting hole A regulating projection, and the position regulation
The projection for the plug cap pie
The O-ring holding annular flange protruding from the outer peripheral surface
This is achieved by a plug cap for an ignition plug, which is characterized by comprising: In addition, the above-mentioned margin of the O-ring is
This is the amount of decrease in radial thickness when the O-ring is mounted in the spark plug mounting hole.

According to the above configuration, the plug cap pipe
From the O-ring holding annular flange protruding from the outer peripheral surface
Since the position regulating projection abuts on the inner peripheral surface of the spark plug mounting hole to restrict the inclination of the spark plug plug cap, the plug cap is positioned within the spark plug mounting hole more than the O-ring is crushed. There is no deviation,
There is no gap between the O-ring and the inner peripheral surface of the spark plug mounting hole. Therefore, even if a load F is applied to the upper part of the plug cap from the side, good waterproofness can be maintained.

Preferably, the annular flange has a tapered outer peripheral surface narrowed toward the spark plug.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same portions as those of a conventional spark plug plug cap. The plug cap 1 for a spark plug shown in FIG. 1 covers a plug cap pipe 2 wrapped with a high-voltage resistance wire 5 for preventing noise and a connector (not shown) connected to a spark plug 8 at a lower end of the plug cap pipe 2. The bush 3 and a rain cover 4 that covers an upper end opening of the ignition plug mounting hole 10 at an upper end thereof.

The plug cap pipe 2 is provided with a spark plug 9 deeply mounted in a spark plug mounting hole 10 formed by combining cylindrical openings formed in a cylinder head 17 and a cylinder head cover 16, respectively.
The rain cover 4 seals the upper end opening so that dust or water droplets do not enter the ignition plug mounting hole 7 from the outside from the outside. It is a rubber lid for the.

As shown in FIG. 2, the spark plug plug cap 1 has a flange-shaped sealing piece 8 of the rain cover 4.
Cover the upper end opening of the spark plug mounting hole 10 and prevent the plug cap 1 from floating up by the sealing means 6 provided above the plug cap pipe 2, thereby preventing invasion of water droplets and the like and half-fitting of the terminals. I do. The sealing means 6 includes an O-ring 7 having a circular cross section which constitutes an elastic seal portion made of a rubber-made annular sealing member having required heat resistance and pressure contact characteristics, and a holding groove 14 for holding the O-ring 7.
A pair of O-ring holding annular flanges 11 protruding from the outer peripheral surface of the plug cap pipe 2 to form
The sealing surface 7 a formed on the outer peripheral end of the O-ring 7 is in close contact with the inner peripheral surface of the spark plug mounting hole 10.

The annular flanges 11 and 12 have tapered outer peripheral surfaces 11 a and 1 narrowed toward the spark plug 9, respectively.
2a, which reliably holds the O-ring 7 and prevents interference with the upper end opening when the spark plug plug cap 1 is inserted into the spark plug mounting hole 10,
The insertion workability is prevented from lowering. The upper end edge 15 of the annular flange 11 serving as a position regulating projection in the present embodiment has a gap t smaller than the squeeze T of the O-ring 7 mounted in the ignition plug mounting hole 10.
₁ protrudes from the plug cap pipe 2 so as to be formed between the spark plug mounting hole 10 and the inner peripheral surface of the spark plug mounting hole 10.

The annular flange 11 has an outer diameter D ₂ of an upper end edge 15 smaller than an inner diameter D _{1 of the} spark plug mounting hole 10, and is mounted in the spark plug mounting hole 10 as shown in FIG. The plug cap pipe 2 has a height having a gap t ₁ between the plug cap pipe 2 and the inner peripheral surface. The outer diameter d ₁ of the O-ring 7 has been formed to be larger than the inner diameter D ₁ of the spark plug mounting hole 10, the plug cap 1 is attached to the spark plug mounting hole 10 Outer diameter d ₂ of O-ring 7
Is press-fitted into the spark plug mounting hole 10 to be equal to the inner diameter D ₁ of the spark plug mounting hole 10, and the radial thickness W of the O-ring 7 is reduced along the circumferential direction by the crushing margin T. It is in a uniformly reduced state.

As shown in FIG. 3, the O-ring 7 in this state has a thickness W in a normal state between the outer peripheral surface of the holding groove 14 and the inner peripheral surface of the ignition plug mounting hole 10. It is crushed until it becomes equal to the gap S. Therefore,
When the O-ring 7 is mounted in the spark plug mounting hole 10, the reduction amount T in the radial direction when the O-ring 7 is mounted in the spark plug mounting hole 10 is:
It can be obtained from the difference between the thickness W and the gap S in the normal state. Therefore, the annular flange 1 which is a position regulating projection is provided.
The height of the upper end edge 15 is set so that the gap t ₁ formed between the upper end edge 15 and the inner peripheral surface of the spark plug mounting hole 10 is smaller than the above-mentioned crushing margin T.

[0018] That is, in the case of such the above spark plug plug cap 1, applied load F from the side to the top of the plug cap 1, as shown in FIG. 4, the center line C ₁ of the spark plug mounting hole 10 wherein the center line C ₂ of the plug cap 1 is inclined to the left side in the figure, the upper edge 15 of the plug cap pipe 2 annular flange 11 projecting from the can on the inner peripheral surface of the spark plug mounting hole 10 with respect to those This restricts the deviation of the spark plug plug cap 1.

At this time, on the opposite side (right side in the figure) to the inclination direction
The upper edge 15 of the located annular flange 11 and the spark plug
Clearance t between inner peripheral surface of attachment hole 10_TwoIs a normal time gap
Interval t ₁Is almost double. Also, located on the opposite side to the tilt direction
The outer peripheral surface of the holding groove 14 for mounting the spark plug
A gap S formed between the hole 10 and the inner peripheral surface thereof_TwoIs the initial gap
S₁The gap t₁Is approximately equal to the sum of
Then, the O-ring 7 located on the opposite side to the tilt direction
The margin T is almost the gap t₁It is reduced by the minute, but the crushing T
Is the gap t₁Since it is set to be larger, the gap S
_TwoIs larger than the thickness W of the O-ring 7 in the normal state.
There is nothing.

Therefore, even when a lateral load F is applied to the upper portion of the spark plug plug cap 1, the sealing surface 7 a of the O-ring 7 located on the side opposite to the inclined direction is kept in contact with the spark plug mounting hole 10. Since it adheres to the inner peripheral surface without forming a gap, intrusion of water droplets and the like can be reliably prevented, and the spark plug plug cap 1 can maintain good waterproofness.

It should be noted that the present invention is not limited to the above-described embodiment, but can take various forms based on the gist of the present invention. For example, it is needless to say that the rain cover is not limited to the shape as described above, and may take various shapes used by those skilled in the art. Also,
The elastic seal part constituting the sealing means of the present invention is not limited to the O-ring 7 having a circular cross section in the above embodiment, but may be a square,
O-rings having various cross-sectional shapes such as a mold and an ellipse can be used.

Further, the position regulating projections constituting the sealing means of the present invention do not consist of the annular flange for holding the O-ring as in the above embodiment, but are separately provided on the outer peripheral surface of the plug cap pipe. Is also good. Further, the shape of the position regulating projection is not limited to the above-described shape, and it goes without saying that various shapes can be adopted as long as the shape can regulate the inclination of the plug cap pipe. For example, the position regulating protrusion may be constituted by a plurality of rib protrusions protruding from the outer peripheral surface of the plug cap pipe.

[0023]

That is, the plug cap for an ignition plug according to the present invention has an O-ring protruding from the outer peripheral surface of the plug cap pipe.
Positioning projection consisting of an annular flange for holding
Since the inclination of the plug cap for the spark plug is restricted by contacting the inner peripheral surface of the hole for mounting the ignition plug, the plug cap does not deviate in the hole for mounting the ignition plug beyond the gap of the O-ring. There is no gap between the O-ring located on the opposite side to the direction and the inner peripheral surface of the spark plug mounting hole. Therefore, even when a lateral load is applied to the upper portion of the plug cap, it is possible to prevent a gap from being formed between the sealing means and the inner peripheral surface of the ignition plug mounting hole, and to prevent water from entering from outside. It is possible to provide a good plug cap for an ignition plug without any problem.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a plug cap for an ignition plug according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing a mounted state of the spark plug plug cap shown in FIG. 1;

FIG. 3 is an enlarged sectional view of a main part of the plug cap for an ignition plug shown in FIG. 2;

FIG. 4 is a partially enlarged sectional view showing an inclined state of the spark plug plug cap shown in FIG. 2;

FIG. 5 is a partial cross-sectional view showing a mounted state of a conventional spark plug plug cap.

FIG. 6 is a partial sectional view showing an inclined state of the spark plug plug cap shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plug cap for spark plugs 2 Plug cap pipe 3 Bush 4 Rain cover 5 High-voltage resistance wire for noise prevention 6 Sealing means 7 O-ring 7a Seal face 8 Sealing piece 9 Spark plug 10 Hole for mounting spark plug 11 Ring flange 12 Ring flange 14 Holding groove 15 Upper edge

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01T 13/04 F02P 1/00-17/00 H02G 3/22-3/28 F16L 5/02 F16J 15 / 00-15/52

Claims (2)

(57) [Claims] 1. A plug cap for an ignition plug mounted in a hole for mounting an ignition plug, wherein sealing means fitted in the hole for mounting an ignition plug comprises:
A gap is formed between the O-ring that is crimped to the inner peripheral surface of the mounting hole and the inner peripheral surface of the ignition plug mounting hole that is smaller than the squeeze of the O-ring mounted in the mounting hole. plug to be the way and a position regulating projection projecting from the plug cap pipe, said position restricting projection holds the O-ring
O-ring holding ring protruding from the outer surface of the cap pipe
A plug cap for a spark plug, comprising a flange . 2. An annular flange narrows toward a spark plug.
Characterized by having a tapered outer peripheral surface
The plug cap for an ignition plug according to claim 1.