JP2000274340A - Plug installing structure of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the work to install a locker cover by preventing the damage of an oil seal, in the plug installing structure of an engine. SOLUTION: In the plug installing structure of an engine in which a cylindrical plug main body 10 installed to a cylinder head, and its front end 11 penetrates a locker cover 5; a screw (electrode) 16 projecting from the front end 11 of the plug main body 10, and an oil seal 40 provided between the locker cover 5 and the plug main body 10, are provided, a guide surface 20 whose diameter is contracted in a conical surface form from near a dust lip connecting part 43 where the oil seal 40 of the plug main body 10 is abutted, toward the front end 11, is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved plug mounting structure in which an oil seal is interposed between a rocker cover of an engine and a plug body.

[0002]

2. Description of the Related Art A conventional engine plug mounting structure is disclosed in, for example, Japanese Utility Model Laid-Open No. 5-38357,
No. 53773 discloses a structure in which a glow plug is attached to a cylinder head in a vortex chamber type diesel engine. Japanese Patent Application Laid-Open No. 7-293417 discloses a structure for improving the durability of a glow plug.

[0003] As a mounting structure of a glow plug in a direct injection diesel engine, the applicant of the present invention has filed Japanese Patent Application No. Hei.
There is one already filed as -266337. It has a cylindrical plug body attached to the cylinder head and the tip of which penetrates the rocker cover, an electrode protrudes from the tip of the plug body, and an oil seal is interposed between the rocker cover and the plug body. ing.

[0004]

However, in the above glow plug mounting structure, the tip end of the cylindrical plug body is chamfered, but the rocker cover to which the oil seal is mounted is not provided. When the front end edge of the plug body hits the lip of the oil seal when assembled to the cylinder head, there is a possibility that the oil seal may be damaged. Generally, a glow plug in a diesel engine is usually provided at an angle to the center of the cylinder, and when the glow plug is inserted into the oil seal by lowering the rocker cover during assembly of the engine,
It is difficult to attach the rocker cover so that the oil seal is not damaged by the tip of the glow plug. In particular, in a multi-cylinder engine, a plurality of glow plugs are provided side by side for each cylinder, and a plurality of oil seals are provided side by side for each cylinder. It is difficult to attach the rocker cover so that it does not hit the tip of the plug,
There is a problem that this operation requires skill and requires a long operation time.

The present invention has been made in view of the above problems, and has as its object to facilitate the work of attaching a rocker cover so as not to damage an oil seal in an engine plug attachment structure.

[0006]

According to a first aspect of the present invention, there is provided a rocker cover which defines a valve operating chamber between the engine block and a cylindrical plug which is attached to the engine block and whose leading end penetrates the rocker cover. The present invention is applied to an engine plug mounting structure including a main body, and an oil seal interposed between the rocker cover and the plug main body.

The guide surface is formed such that the diameter of the guide surface is reduced in a conical shape from the vicinity of the lip joint where the oil seal of the plug body comes into contact with the tip end.

According to a second aspect of the present invention, there is provided a rocker cover defining a valve operating chamber between the engine block, a cylindrical plug body attached to the engine block and having a tip portion penetrating the rocker cover, and a rocker cover. The present invention is applied to an engine plug mounting structure including an oil seal interposed between plug bodies.

A chamfer having an arc-shaped cross section is formed at the tip of the plug body.

A third aspect of the present invention provides a rocker cover that defines a valve operating chamber with an engine block, a cylindrical plug body attached to the engine block and having a tip portion penetrating the rocker cover, and a plug body. Applied to an engine plug mounting structure including an electrode protruding from the tip, a disk-shaped insulator interposed between the electrode and the plug main body, and an oil seal interposed between the rocker cover and the plug main body I do.

The outer peripheral surface of the insulator is formed in a conical shape whose diameter decreases from the plug body toward the electrode.

According to a fourth aspect of the present invention, there is provided a rocker cover for defining a valve operating chamber with an engine block, a cylindrical plug body attached to the engine block and having a tip portion penetrating the rocker cover, and a plug body. An electrode protruding from the tip, a disk-shaped insulator interposed between the electrode and the plug body, a nut screwed into a screw formed on the electrode to fasten the insulator, a rocker cover and a plug body The present invention is applied to an engine plug mounting structure including an oil seal interposed therebetween.

The outer peripheral surface of the nut is formed in a conical shape whose diameter is reduced from the insulator toward the electrode.

[0014]

According to the first aspect of the present invention, when the rocker cover is assembled to the engine block while the plug body is attached to the engine block and the oil seal is attached to the rocker cover, the rocker cover is assembled. When the oil seal is lowered toward the engine block and the glow plug is inserted into the oil seal, the oil seal is slidably brought into contact with the guide surface of the plug body to prevent the oil seal from being damaged by the plug body.

The conical guide surface is formed from the distal end of the plug body to the vicinity of the dust lip joint, so that the inclination angle of the cross section is minimized. There is no fear of damaging the seal lip or dust lip even if it hits the seal.

In the case of a multi-cylinder engine as well, the rocker cover is lowered onto the engine block while sliding the oil seals on the guide surfaces of the plug bodies, so that the assembling work does not require any skill and the rocker cover can be quickly moved. Can be assembled to the engine block, increasing productivity.

In the second aspect of the present invention, the chamfered portion having an arc-shaped cross section formed at the tip end portion of the plug main body has no fear of damaging the oil seal seal lip or dust lip even when the rocker cover is assembled. The work of attaching the rocker cover so as not to damage the oil seal is facilitated.

In the third aspect of the present invention, since the outer peripheral surface of the insulator has a conical shape whose diameter is reduced from the plug body toward the electrode, the seal lip, dust lip, etc. of each oil seal can be provided when the rocker cover is assembled. There is no fear of damaging these components even when hitting, and the work of attaching the rocker cover so as not to damage the oil seal is facilitated.

In the fourth aspect of the present invention, since the outer peripheral surface of the nut has a conical shape whose diameter is reduced from the insulator toward the electrode, even if the nut hits the seal lip or dust lip of each oil seal when the rocker cover is assembled. There is no need to worry about damaging them, and the work of attaching the rocker cover so as not to damage the oil seal is facilitated.

[0020]

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

FIG. 1 shows an example of a mounting structure of a glow plug 2 in a direct injection diesel engine to which the present invention can be applied. This itself is disclosed by the present applicant in Japanese Patent Application No.
No. 266337 has already been filed.

In FIG. 1, reference numeral 1 denotes a cylinder head (engine block). A rocker cover 5 that defines a valve operating chamber 4 is attached to an upper portion of the cylinder head 1. And the like, are accommodated.

A combustion chamber 3 is defined between a lower portion of the cylinder head 1 and a cylinder and a piston (not shown), and includes a fuel injection valve 6 and a glow plug 2 facing the combustion chamber 3. The glow plug 2 has a heat generating portion 15 facing the combustion chamber at a lower end thereof, and heat is supplied to a heat coil provided in the heat generating portion 15 when the engine is started to heat the intake air.

Four glow plugs 2 are attached to a cylinder head 1 provided in a four-cylinder engine for each cylinder. Each glow plug 2 is mounted to be inclined with respect to the cylinder center line, and the inside of the cylinder head 1 and the valve train
So that it does not interfere with the components.

As shown in FIG. 2, the glow plug 2 has a cylindrical plug housing 10 and the plug housing 1
A screw portion 18 screwed to the cylinder head 1 on the outer periphery of the cylinder head 1;
A cylinder head 1 having a hexagonal portion 19 for engaging with a tool.
It is screwed into and attached.

The plug body 10 has a tip 11 penetrating through the rocker cover 5, and a screw 16 constituting a positive electrode protrudes from the tip 11 of the plug body 10 via a fastener 17 screwed to the screw 16. The terminal 9 on the harness side is fastened.

A disk-shaped insulator 50 is interposed between the plug body 10 and the screw 16, and the insulator 50 is fastened via a nut 60 screwed to the screw 16. The insulator 50 insulates between the terminal 9 on the harness side and the plug body 10. A groove 61 for engaging with a tool is formed on the outer periphery of the nut 60.

As shown in FIGS. 3 and 4, an oil seal 40 is interposed between the plug housing 10 and the rocker cover 5 to seal the valve operating chamber 4. The oil seal 40 has a seal lip 41 with a spring and a dust lip 42 that are in contact with the outer periphery of the plug housing 10, and is attached to the rocker cover 5 via a ring 43.

A seal surface 14 for contacting the oil seal 40 is formed in a cylindrical shape on the outer periphery of the plug housing 10. On the sealing surface 14, a seal lip joint portion 12 for abutting the seal lip 41 and a dust lip joint portion 13 for abutting the dust lip 42 extend annularly.

As the gist of the present invention, a guide surface 20 is formed on the plug main body 10 so as to reduce the diameter of the conical surface from the vicinity of the dust lip joint portion 13 to the distal end portion 11 thereof.

The lower end 21 of the guide surface 20 is formed as close as possible to the dust lip joint 13 within a range not in contact with the dust lip 42. The guide surface 20 becomes gradually thinner from the lower end portion 21 to the upper end portion 22 of the guide surface 20, that is, to the tip end portion 11 of the plug body 10, so as to minimize the inclination angle of the glow plug 2 with respect to the central axis.

The guide surface 20 is formed such that the outer diameter of the upper end portion 22 thereof is substantially equal to the outer diameter of the insulator 50 and is continuous with the outer peripheral surface of the insulator 50 having a cylindrical shape without any step.

The operation is described below, with the above configuration.

When assembling the engine, the glow plug 2 is attached to the cylinder head 1 while the oil seal 40
The rocker cover 5 is assembled to the cylinder head 1 in a state where is attached to the rocker cover 5. The rocker cover 5 is lowered toward the cylinder head 1, and when each glow plug 2 is inserted into each oil seal 40,
Each oil seal 40 is connected to the guide surface 20 of each plug body 10.
The oil seals 40 are prevented from being damaged by the plug main body 10 by being brought into sliding contact with the plug seal 10.

The cylindrical guide surface 20 is formed from the distal end portion 11 to the vicinity of the dust lip joint portion 13 to minimize the inclination angle of the cross section. Therefore, when assembling the rocker cover 5, each oil seal 4
There is no fear of damaging the seal lip 41 or the dust lip 42 even if they hit the seal lip 41 or the dust lip 42.

In the case of a four-cylinder engine, the cylinder head 1
Four glow plugs 2 are mounted side by side for each cylinder, and four oil seals 4
0 are provided side by side for each cylinder, but the oil seal 40 is slidably brought into contact with the guide surface 20 of each glow plug 2 and the rocker cover 5 is lowered onto the cylinder head 1, so that this assembly work is accomplished. , The rocker cover 5 can be quickly assembled to the cylinder head 1, and productivity can be increased.

Next, another embodiment shown in FIG. 5 will be described. The same components as those in the above-described embodiment are denoted by the same reference numerals.

A chamfered portion 25 is formed at the tip end portion 11 of the plug body 10 in an arc-shaped cross section. The chamfered portion 25 has its upper end 27 in contact with the outer peripheral end of the insulator 50 to maximize the radius of curvature.

In this case, the rocker cover is lowered toward the cylinder head, and when each glow plug 2 is inserted into each oil seal, each oil seal is brought into sliding contact with the chamfered portion 25 of each plug body 10. In addition, each oil seal 40 is prevented from being damaged by the plug body 10.

Next, another embodiment shown in FIG. 6 will be described. The same components as those in the above-described embodiment are denoted by the same reference numerals.

The plug body 10 is formed with a guide surface 20 whose diameter is reduced in a conical shape from the vicinity of the dust lip joint portion 13 to the tip end portion 11 thereof.
The outer peripheral surface 65 of the nut 5 and the nut 60 are each formed in a conical surface continuous with the guide surface 20. That is, the guide surface 20
And outer peripheral surface 55 of insulator 50 and outer peripheral surface 6 of nut 60
5 continuously form one conical surface without any step.

In this case, the rocker cover is lowered toward the cylinder head, and when each glow plug 2 is inserted into each oil seal, each oil seal is fixed to the nut 60.
The oil seal 40 is prevented from being damaged by the nut 60, the insulator 50, or the plug body 10 by sliding the outer peripheral surface 65 of the oil seal 40 into contact with the outer circumferential surface 55 of the insulator 50 and the guide surface 20 of each plug body 10. You.

The present invention can be applied to a glow plug provided in a swirl chamber type diesel engine and a spark plug provided in a gasoline engine.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an engine showing an embodiment of the present invention.

FIG. 2 is a front view of the glow plug.

FIG. 3 is a sectional view around the glow plug.

FIG. 4 is a sectional view of a rocker cover and the like.

FIG. 5 is a front view of a glow plug showing another embodiment.

FIG. 6 is a cross-sectional view around a glow plug showing still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head (engine block) 2 Glow plug 4 Valve train chamber 5 Rocker cover 10 Plug end 13 Dustrip joint 14 Seal surface 16 Screw (electrode) 20 Guide surface 50 Insulator 55 Outer surface 60 Nut 65 Outer surface

Claims (4)

[Claims] A rocker cover defining a valve chamber between the engine block and the engine block; a cylindrical plug body attached to the engine block and having a tip portion penetrating through the rocker cover; An oil seal interposed between the plug bodies; and a guide for reducing the diameter of the plug body in a conical shape from the vicinity of the lip joint of the plug body with which the oil seal abuts to the tip end. An engine plug mounting structure characterized by forming a surface. A rocker cover defining a valve chamber between the engine block and the engine block; a cylindrical plug body attached to the engine block and having a distal end portion penetrating the rocker cover; An engine plug mounting structure comprising: an oil seal interposed between the plug bodies; and a chamfer having an arc-shaped cross section formed at the end of the plug body. 3. A rocker cover defining a valve operating chamber with the engine block, a cylindrical plug body attached to the engine block and having a tip portion penetrating the rocker cover, and a tip end of the plug body. An electrode protruding from the portion, a disk-shaped insulator interposed between the electrode and the plug main body, and an oil seal interposed between the rocker cover and the plug main body. In the structure, an outer peripheral surface of the insulator is formed in a conical surface shape whose diameter is reduced from the plug body toward the electrode. 4. A rocker cover defining a valve operating chamber with an engine block, a cylindrical plug body attached to the engine block and having a tip portion penetrating the rocker cover, and a tip end of the plug body. An electrode protruding from the portion, a disc-shaped insulator interposed between the electrode and the plug body, a nut screwed into a screw formed on the electrode to fasten the insulator, and the rocker cover. An oil seal interposed between the plug main bodies, wherein the outer peripheral surface of the nut is formed in a conical shape whose diameter is reduced from the plug main body toward the electrode. Engine plug mounting structure.