JPH11297452A - Deterioration priventive structure for high pressure connection part for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deterioration priventive structure of a high pressure connection part for an internal combustion engine capable of preventing deterioration of a plug cap itself. SOLUTION: A sheet-type discharge shielding member 40 is detachably installed on an insulator part Pg of a spark plug P, so that a lower end part of a plug cap 20 is parted from a nut part P1 as a grounding part of the spark plug P. The discharge shielding member 4 is formed as a sheet having an installation hole part at a center part, and the insulator part P is detachably inserted into the installation hole part. The discharge shielding member 40 is formed like a container, having a bottom provided with the installation hole part to cover the plug cap 20 from a lower end surface to a lower outer circumferential surface, and it is engaged with the lower end part of the plug cap 20 as the insulator part is inserted into the installation hole part, so that it is detachably attached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing deterioration of a high-pressure connection for an internal combustion engine for connecting a spark plug and a high tension cable in an internal combustion engine of an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, there is a structure shown in FIG. 5 as a structure of a high voltage connecting portion for connecting an ignition plug and a high tension cable in an internal combustion engine of an automobile or the like.

In the structure of this high-pressure connection portion, a plug hole Ha is formed in a cylinder head H of an internal combustion engine, and a mounting screw hole Hb for mounting a spark plug P is formed at the bottom of the plug hole Ha.

[0004] The spark plug P is connected to a grounding part Pe.
A center electrode Pa and a ground electrode Pb are provided on the lower side of the insulator Pg.
Is provided.

The grounding portion Pe includes a mounting screw portion Pn, a large diameter portion Pm, and a nut-like portion Pl in order from the lower side to the upper side. Then, by rotating the nut-shaped portion Pl with a known fastener, the mounting screw portion Pn is screwed into the mounting screw hole Hb of the cylinder head H, and the ignition plug P is mounted on the cylinder head H.
At this time, the large diameter portion Pm and the mounting screw portion Pn come into contact with the cylinder head H, and the ground electrode Pb is connected to the large diameter portion Pm,
The cylinder head H is configured to be grounded via the mounting screw portion Pn.

[0006] In addition, an insulator portion Pg is provided at the upper end of the insulator portion Pg.
g and the center electrode Pa through the center axis of the earth grounding part Pe.
Is provided with a terminal Pt which is electrically connected to the terminal Pt.

The terminal Pt is connected to a high-voltage terminal 110 attached to the end of the high tension cable, and a plug cap 100 is provided to cover the connection.

The plug cap 100 is made of rubber and is formed in a substantially cylindrical shape, and is configured so that the high-voltage terminal 110 can be housed therein. The lower end is externally fitted from above the insulator portion Pg, so that the high-voltage terminal 110 is connected to the terminal Pt.

In the structure of this high-voltage connection, the terminal P
In order to prevent creeping discharge occurring along the surface of the insulator portion Pg between the t and the nut-shaped portion Pl, which is a grounded portion, the lower end of the plug cap 100 is fixed to the nut-shaped portion. It is finished in a shape that reaches near Pl.

[0010]

However, in the structure of the high-voltage connecting portion as described above, as shown in FIG. 6, the nut-like portion P1 between the terminal Pt and the nut-like portion P1 is not provided.
Since the potential gradient becomes large near the upper side of 1, corona discharge occurs here, and there is a problem that the lower end surface of the plug cap 100 is deteriorated by this corona discharge, causing whitening or cracking. In addition, if this deterioration progresses, sufficient insulation between the terminal Pt and the nut-shaped portion Pl cannot be obtained, so that it is necessary to replace the plug cap 100 itself with the entire assembly, resulting in a large expense for the replacement cost. Problems had arisen.

If the lower end of the plug cap 100 is extended to a position where it comes into contact with the nut-like portion Pl, the above-described corona discharge can be prevented. However, in order to connect the high-voltage terminal 110 and the terminal Pt, it is necessary to provide a so-called play between the end portion of the plug cap 100 and the nut-like portion Pl in consideration of their tolerance and the like. Can not be adopted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a structure for preventing deterioration of a high-pressure connection for an internal combustion engine, which can prevent deterioration of a plug cap due to corona discharge. With the goal.

[0013]

According to a first aspect of the present invention, there is provided a structure for preventing deterioration of a high-voltage connecting portion for an internal combustion engine, the terminal being provided on an upper side of a grounding portion via an insulator portion. The ignition plug provided with is attached to the internal combustion engine body, and the lower end of the plug cap formed in a substantially cylindrical shape is housed and held in the inside thereof with the high-voltage terminal attached to the end of the high tension cable. A structure for preventing deterioration of a high-voltage connecting portion for an internal combustion engine, wherein the plug cap is fitted to the insulator portion to connect the terminal to the high-voltage terminal, wherein the plug cap surrounds an outer periphery of the insulator portion. A discharge shielding member is removably mounted between the lower end of the base and the grounding part.

According to a second aspect of the present invention, the discharge shielding member is formed in a sheet shape having a mounting hole formed in a central portion, and the insulator is removably inserted into the mounting hole. You may.

According to a third aspect of the present invention, the discharge shielding member is formed in a bottomed shape with a mounting hole covering from a lower end surface to a lower outer peripheral surface of the plug cap,
The insulator may be detachably attached to the lower end of the plug cap by inserting the insulator into the mounting hole.

Further, as set forth in claim 4, a skirt-shaped portion for covering a grounded portion of the ignition plug may be formed on an outer peripheral portion of a bottom portion of the discharge shielding member.

Further, the discharge shielding member may be detachably attached to a lower end portion of the plug cap by screwing.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A structure for preventing deterioration of a high-pressure connection for an internal combustion engine according to one embodiment of the present invention will be described below.

As shown in FIG. 1, the structure for preventing deterioration of the high-pressure connection portion for an internal combustion engine uses a spark plug P mounted on an internal combustion engine such as an automobile to connect a high tension cable K housed in a plug cap 20. The high-voltage terminal 10 is connected, and a discharge shielding member 40 is detachably provided between the lower end of the plug cap 20 and the upper part Pl of the nut of the ignition plug P.

A plug hole Ha is formed in the cylinder head H of the internal combustion engine, and a mounting screw hole Hb for mounting a spark plug P is formed at the bottom of the plug hole Ha. On the inner peripheral surface of the mounting screw hole Hb, a screw groove into which a mounting screw portion Pn of the ignition plug P described later can be screwed is formed.

The spark plug P is connected to a grounding part Pe.
A central electrode Pa and a ground electrode Pb are provided at a predetermined interval on the lower side of the ground electrode, and an insulator portion Pg is provided on the upper end side of the grounded ground portion Pe.

The grounding portion Pe includes a mounting screw portion Pn, a large-diameter portion Pm, and a nut-like portion Pl in order from the lower side to the upper side. The mounting screw portion Pn is formed with a screw groove that can be screwed into the screw hole of the mounting screw hole Hb. The ignition plug P is inserted into the plug hole Ha, and the nut-shaped portion Pl is connected to a well-known fastening tool. , The mounting screw portion Pn is screwed into the mounting screw hole Hb of the cylinder head H, and the ignition plug P is mounted on the cylinder head H. At this time, the large diameter portion Pm and the mounting screw portion Pn are
Then, the ground electrode Pb is grounded to the cylinder head H via the large diameter portion Pm and the mounting screw portion Pn.

On the upper side of the insulator Pg, an insulator P
g and the center electrode Pa through the center axis of the earth grounding part Pe.
Is provided with a terminal Pt which is electrically connected to the terminal Pt.

The plug cap 20 is entirely formed of rubber, and has an extended portion 24 extending obliquely upward from the upper end of the main body 22.

The main body 22 is formed in a substantially cylindrical shape whose upper end is closed, and a fitting hole 26 is formed at the lower end of the body so as to be externally fitted to the insulator Pg. Above the hole 26, a terminal holding hole 28 for accommodating and holding the high-voltage terminal 10 is formed. Further, a cable holding hole 30 is formed from the terminal holding hole 28 to communicate with the outside through the inside of the extending portion 24.

The high-voltage terminal 10 at the end of the high tension cable K is housed and held in the terminal holding hole 28. At this time, the high tension cable K is drawn out through the cable holding hole 30, and is connected to a distributor or the like (not shown).

Further, with the high-voltage terminal 10 housed and held therein, the fitting hole 26 of the plug cap 20 is provided.
Is externally fitted to the insulator portion Pg of the ignition plug P from above, whereby the high voltage terminal 10 inside the plug cap 20 and the terminal Pt on the upper portion of the ignition plug P are electrically connected.

As described above, the ground electrode Pb is connected to the mounting screw portion Pn.
And the ground electrode P is grounded to the cylinder head H via the large diameter portion Pm, and the center electrode Pa is electrically connected to the distributor via the terminal Pt, the high voltage terminal 10 and the high tension cable K from the center axis of the ignition plug P. As a result, a high voltage is applied between the center electrode Pa and the ground electrode Pb.

As shown in FIG. 2, the discharge shielding member 40 is formed of rubber or the like into a substantially square or disk-shaped sheet in a plan view, and has a central portion in which the insulator portion Pg can be inserted and removed. A hole 42 is formed.

Then, the insulator portion Pg is inserted into the mounting hole portion 42 in advance, the discharge shielding member 40 is attached to the ignition plug P, and then the plug cap 20 attached to the high tension cable K is attached. By fitting to the insulator portion Pg, the discharge shielding member 40 is connected between the lower end portion of the plug cap 20 and the nut-shaped portion Pl, and the lower end portion of the plug cap 20 and the grounded nut-shaped portion Pl of the ignition plug P are connected. It is configured to partition between.

When the plug cap 20 is attached to the insulator portion Pg, play is provided between the lower end portion of the plug cap 20 and the nut-like portion Pl.
0 The thickness of the discharge shielding member 40 is made smaller than the distance between the lower end and the nut-shaped portion Pl. Thereby, when the plug cap 20 is fitted to the insulator portion Pg, the connection between the high-voltage terminal 10 and the terminal Pt is performed without any trouble.

According to the structure for preventing the deterioration of the high-pressure connecting portion for an internal combustion engine configured as described above, the lower end of the plug cap 20 and the grounding portion Pe are located near the boundary between the insulator portion Pg and the nut-shaped portion Pl. Since the discharge shielding member 40 for partitioning from a certain nut-shaped part Pl is provided, the nut-shaped part Pl
Accordingly, the deterioration of the plug cap 20 due to the corona discharge can be effectively prevented without the corona discharge generated from the discharge blocking member 40 being blocked by the discharge prevention member 40 and reaching the lower end of the plug cap 20.

As a specific effect, the plug cap 2
It is possible to extend the product life of zero or more twice.

The discharge shielding member 40 is provided by corona discharge.
Is deteriorated, the deteriorated discharge shielding member 40 can be removed from the insulator portion Pg and replaced with a new discharge shielding member 40. Therefore, it is necessary to replace the plug cap 100 itself as in the conventional example shown in FIG. Therefore, the maintenance cost of the high-voltage connection is reduced.

Further, as shown in FIG.
As 0B, a container-shaped main body 50B that covers from the lower end to the lower outer peripheral surface of the plug cap 20 is formed, and a hole 54B for inserting the insulator Pg into the bottom 52B of the main body 50B is used. Is also good.

In this case, the thickness of the bottom 52B is
The distance between the plug cap 20 and the nut-shaped portion Pl is set to be smaller than the distance between the plug cap 20 and the nut-shaped portion Pl.

The connection work is performed with the discharge shielding member 40B detachably fitted to the lower end of the plug cap 20.
If the insulator portion Pg of the ignition plug P is inserted into the plug cap 20 through the hole 54B of the bottom portion 52B of the discharge shielding member 40B, the high-voltage terminal 10 is connected to the terminal Pt as in the prior art.
Connected to.

According to this structure, the discharge shielding member 40
B completely covers the lower end surface of the plug cap 20 from the lower peripheral surface to the lower outer peripheral surface, so that deterioration of the lower end of the plug cap 20 due to corona discharge can be more effectively prevented.

Further, as shown in FIG. 4, as a discharge shielding member 40C, a container-like main body 50C covering from the lower end surface of the plug cap 20 to the lower outer peripheral surface is formed, and a bottom 52C of the main body 50C is formed. A hole 54C for inserting the insulator portion Pg is formed.
It is also possible to use a 2C in which a hakama-shaped portion 56C is formed to cover the nut-shaped portion P1 from the outer peripheral edge on the lower surface side.

Also in this case, the thickness of the bottom portion 52C is made smaller than the distance between the plug cap 20 and the nut-like portion Pl so that there is play between the plug cap 20 and the nut-like portion Pl. Set.

The connection work is performed with the discharge shielding member 40C detachably fitted to the lower end of the plug cap 20.
If the insulator portion Pg of the ignition plug P is inserted into the plug cap 20 from the skirt portion 56C of the discharge shielding member 40C through the hole 54C of the bottom portion 52C, the high-voltage terminal 10
Is connected to the terminal Pt.

According to this structure, the discharge shielding member 40
The bottom portion 52C of C and the main body portion 50C completely cover the lower outer peripheral surface from the lower end surface of the plug cap 20, and the nut-shaped portion Pl, which is a source of corona discharge, is covered by the hakama-shaped portion 56C. Further, deterioration of the lower end of the plug cap 20 due to the corona discharge is prevented.

In the example shown in FIG. 3 or FIG. 4, a screw groove is formed on the outer peripheral surface of the lower end portion of the plug cap 20, and a screw screwed with the screw groove is formed on the inner peripheral surface of the main body 50B, 50C. A groove may be formed, and both may be detachable by screwing.

The deterioration preventing members 40, 40B, 40C
In addition to the above rubber, an insulating material such as a plus chip, ceramic, or laminated mica can be used as a material for forming the above.

[0045]

As described above, claims 1 to 5 of the present invention.
According to the described structure for preventing deterioration of the high-pressure connection for an internal combustion engine,
Since the discharge shielding member is removably mounted between the lower end of the plug cap and the grounding part so as to surround the outer periphery of the insulator part of the ignition plug, the discharge shielding member generates the grounding part at the grounding part. The deterioration of the plug cap due to corona discharge can be prevented.

When the discharge shielding member has deteriorated, the discharge shielding member may be replaced instead of replacing the plug cap itself as in the prior art, so that the maintenance cost of the high-voltage connection portion is low. It will be.

According to a third aspect of the present invention, the discharge shielding member is formed in a bottomed shape with a mounting hole covering from a lower end surface of the plug cap to a lower outer peripheral surface, and the insulator is provided in the mounting hole portion. If the plug cap is detachable by being externally fitted to the lower end of the plug cap with the part inserted, the lower end of the plug cap is more completely covered by the discharge shielding member, so that the deterioration of the end of the plug cap is more reduced. It can be effectively prevented.

Further, when a skirt-like portion covering the grounding portion of the spark plug is formed around the bottom of the discharge shielding member, the surrounding portion may be formed by corona discharge generated at the grounding portion. The effects are more effectively prevented.

[Brief description of the drawings]

FIG. 1 is a partially cutaway view showing a structure for preventing deterioration of a high-pressure connection portion for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a discharge shielding member.

FIG. 3 is a partially cutaway view showing a modification.

FIG. 4 is a partially cutaway view showing another modification.

FIG. 5 is a partially cutaway view showing a conventional example.

FIG. 6 is a diagram showing a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 High voltage terminal 20 Plug cap 40 Discharge shielding member K High tension cable P Spark plug Pe Grounding part Pg Insulator part Pt terminal

Claims (5)

[Claims] An ignition plug having a terminal provided on an upper side of a grounded earth portion via an insulator portion is mounted on an internal combustion engine main body, and a plug cap formed in a substantially cylindrical shape has a high tension cable end therein. The high-voltage terminal attached to the portion is housed and held, and the lower end thereof is fitted to the insulator portion to prevent deterioration of the internal-combustion-engine high-voltage connection portion that connects the terminal and the high-voltage terminal. A structure for preventing a deterioration of a high-voltage connecting portion for an internal combustion engine, wherein a discharge shielding member is detachably mounted between a lower end portion of the plug cap and the grounding portion so as to surround an outer periphery of the insulator portion. 2. The internal combustion engine according to claim 1, wherein the discharge shielding member is formed in a sheet shape having a mounting hole formed in a central portion, and the insulator is removably inserted into the mounting hole. For preventing deterioration of the high voltage connection part for 3. The discharge shielding member is formed in a bottomed container shape with a mounting hole covering from a lower end surface to a lower outer peripheral surface of the plug cap, and in a state where the insulator portion is inserted into the mounting hole. 2. The structure for preventing deterioration of a high-voltage connecting portion for an internal combustion engine according to claim 1, wherein the structure is detachable by being externally fitted to a lower end portion of the plug cap. 4. The structure for preventing deterioration of a high-pressure connection portion for an internal combustion engine according to claim 3, wherein a skirt-like portion for covering a grounding portion of the ignition plug is formed on an outer peripheral portion of a bottom portion of the discharge shielding member. 5. The structure for preventing deterioration of a high-pressure connection for an internal combustion engine according to claim 3, wherein the discharge shielding member is detachably attached to a lower end of the plug cap by screwing.