JPH0332767Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sealing structure between a cylinder head cover and a plug tube of an internal combustion engine.

[Prior Art] A plug tube for mounting a spark plug facing the combustion chamber of an internal combustion engine is attached to a cylinder head and extends upward from the cylinder head mounting portion to a plug insertion hole portion of the cylinder head cover. A plug tube gasket is interposed between the upper end of the plug tube and the cylindrical wall forming the plug insertion hole of the cylinder head cover to seal the gap between the two (for example, Utility Model No. 60-58844).
issue).

As shown in FIG. 4, a conventional plug tube gasket 100 is interposed between a plug tube 102 and a cylindrical wall 106 formed around a plug insertion hole in a cylinder head cover 104, and is in contact with the plug tube 102. A main lip portion 108 in contact with the main lip portion 108;
Attachment part 11 fitted to the inner peripheral surface of cylindrical wall 106
0, and a bellows portion 112 that connects the main lip portion 108 and the attachment portion 110. The plug tube gasket 100 further includes a main lip portion 108.
It has a spring 114 to increase the contact force with the plug tube 102, and an L-shaped metal ring 116 to improve the stability of the mounting part 110, and the other parts are made of rubber. There is. The plug tube gasket 100 does not have a groove in its main lip portion 108 that forms an annular tongue on the inner circumferential side to improve sealing performance.

For example, in a seal mechanism where hydraulic pressure is applied, a groove is formed in the seal member to form an annular tongue, and by applying hydraulic pressure to the annular tongue and pressing it against the shaft, the shaft sealing effect is achieved. It is known that it can be increased (for example, Japanese Utility Model Application Publication No. 56-23756). However, such an annular tongue piece is applied to a shaft sealing structure where hydraulic pressure is applied, and is not applied to a sealing structure where no hydraulic pressure is applied, such as the plug tube gasket 100 described above.

[Problem that the invention attempts to solve]

However, it has been found that the sealing structure between the cylinder head cover 104 and the plug tube 102 using the plug tube gasket 100 as shown in FIG. 4 has the following problems.

(a) Due to manufacturing and assembly errors, the shaft center of the plug tube 102 and the cylinder head cover 10 may
If the axis of the cylindrical wall 106 of No. 4 is eccentric, the main lip portion 1 of the plug tube gasket 100
The contact between 08 and the plug tube 102 is uneven, and the absorption of assembly eccentricity is poor. This is because even though the main lip portion 108 is made of rubber, its flexibility is low.

(b) When the plug tube 102 is attached at an angle to the cylindrical wall 106 of the cylinder head cover 104 during assembly, the contact surface of the main lip portion 108 to the plug tube 102 will be on the outer peripheral surface of the plug tube 102. This results in poor absorption of the inclination, resulting in poor sealing performance.
This is also a problem caused by the low flexibility of the main lip portion 108.

(c) The area of the contact sealing surface between the main lip portion 108 of the plug tube gasket 100 and the outer peripheral surface of the plug tube 102 is small. This is because the main lip portion 108 is made of a lumpy rubber body without tongues, so that the amount of deformation caused by crushing is small and the sealing surface is not formed to be large.

(d) Also, attach the cylinder head cover 104 to which the plug tube gasket 100 is attached in advance to the main lip portion 1 of the plug tube gasket 100.
If the plug tube 102 is mounted on the cylinder head while sliding its inner peripheral surface onto the outer peripheral surface of the plug tube 102, the loading load is large and the ease of assembly is not necessarily good. This is also a problem caused by the low flexibility of the main lip.

[Means for solving problems]

All of the above problems are caused by the low flexibility of the main lip portion of the conventionally proposed plug tube gasket.

This problem could be solved by increasing the flexibility of the main lip. For example, it is considered effective to form a structure that can be flexibly deformed on the side of the main lip that comes into contact with the plug tube. For seals that are subject to hydraulic pressure, it is effective to apply an annular tongue as disclosed in the above-mentioned Japanese Utility Model Publication No. 56-23756; however, for the seal structure between the cylinder head cover and the plug tube, hydraulic Therefore, the idea of using hydraulic pressure to flexibly press the annular tongue against the plug tube does not work.

The present invention attempts to solve the above-mentioned problems by forming a groove in the main lip part to increase the flexibility of the part of the main lip part that contacts the plug tube.

More specifically, the above-mentioned problem is solved according to the present invention in the sealing structure between the cylinder head cover and the plug tube. A plug tube gasket is interposed between the plug tube gasket and the plug tube, and the plug tube gasket is connected to a main lip portion that contacts the plug tube, a mounting portion that is fitted to the inner circumferential surface of the cylinder head cover cylindrical wall, and the main lip portion that contacts the plug tube gasket. It is composed of a bellows part that connects a lip part and the mounting part, and a spring is attached to the main lip part, and an annular approximately V-shaped groove that opens upward is provided, and the shape of the groove is , the groove depth is h, the radius of the spring cross section is r,
When the angle between the inner and outer circumferential surfaces of the groove is α ₁ and the angle between the inner circumferential surface of the main lip and the axis of the plug tube gasket is α ₂ , between h, r, α ₁ , and α ₂ , The seal structure between the cylinder head cover and the plug tube is characterized by a groove shape that satisfies the relationship 0.3r≦h≦2.0r and α ₁ ≒ α ₂ in the free state.
resolved.

[Effect]

By providing the groove in the main lip portion and specifying the shape of the groove as described above, appropriate flexibility is provided to the plug tube abutting portion of the main lip portion. Regarding the shape of the groove, if h<0.3r or less, the part where the main lip contacts the plug tube will be too inflexible, and if h>2.0r, the tightening force of the spring will be too weak to contact the plug tube in the main lip. There may be cases where the contact area does not work sufficiently. In addition, if the condition α ₁ ≒ α ₂ is not satisfied, when the plug tube abutting part of the main lip part is pushed toward the outer periphery by the plug tube, the strength of the groove collapse will vary, and the sealing performance will be affected. may be damaged. In the case of the groove shape specified as above, good sealing performance can be obtained.

By forming the above groove, flexibility is given to the plug tube abutting part of the main lip part, and assembly eccentricity and relative inclination between the plug tube and cylinder head cover can be well absorbed, and the seal width is wide. Therefore, the charging load during assembly is also small.

〔Example〕

A preferred embodiment of the sealing structure between the cylinder head cover and the plug tube according to the present invention will be described below with reference to FIGS. 1 to 3.

Figure 1 shows an embodiment of the present invention, showing the state before assembly (free state of the plug tube gasket).
Figure 2 shows the state after assembly. FIG. 3 shows another embodiment of the invention in which the groove shape is changed.

In Figure 1, plug tube gasket 1
0 is attached to the inner surface of the cylindrical wall 16 around the plug insertion hole 14 of the cylinder head cover 12 of an internal combustion engine, and when the cylinder head cover 12 is attached to the cylinder head, as shown in FIG.
Its inner periphery abuts the plug tube 18 to seal between the cylinder head cover 12 and the upper end of the plug tube 18. The space above and below the plug tube gasket 10 is the atmosphere and the space inside the head cover, both of which are spaces at atmospheric pressure or near atmospheric pressure.

Plug tube gasket 10 generally includes a main lip portion 20 that abuts plug tube 18;
The cylinder head cover is comprised of a mounting portion 22 that is fitted onto the inner peripheral surface of the cylindrical wall 16, and a bellows portion 24 that connects the main lip portion 20 and the mounting portion 22. A metal spring 26 having an annular shape and a hollow circular cross section is embedded in the main lip portion 20, and the mounting portion 22 has a metal spring 26 embedded therein.
A substantially L-shaped metal ring 28 is embedded with a portion exposed. The parts of the plug tube gasket 10 other than the spring 26 and the metal ring 28 are made of an elastic material, preferably rubber.

The main lip portion 20 includes an outer circumferential surface 30 extending substantially parallel to the axis of the plug tube gasket 10, and an upper end surface 32 extending in a plane substantially orthogonal to the axis.
It has an inner circumferential surface 34 that extends linearly obliquely to the axis and whose diameter increases downwardly, and is integrally connected to the bellows portion 24 at the lower end. The main lip portion 20 is formed with an annular groove 36 that opens upward and has a substantially V-shaped cross section. The groove 36 is located at the upper end of the main lip portion 20 and is formed on the inner peripheral side of the center of the wall thickness of the upper end. Groove 36 is plug tube gasket 10
has an outer circumferential surface 38 extending substantially parallel to the axis of the axis, and an inner circumferential surface 40 extending linearly obliquely to the axis and increasing in diameter as it goes downward; and is defined in the radial direction. The spring 26 is located on the outer peripheral side of the groove 36. The upper end of the portion of the main lip portion 20 on the inner peripheral side than the groove 36 may protrude upward from the upper end of the portion where the spring 26 is embedded.

The cross-sectional shape of the groove 36 must meet the following conditions. That is, in the free state of the plug tube gasket 10, the groove depth (the distance in the vertical direction from the upper end surface of the part where the spring 26 is embedded in the main lip part 20 to the groove bottom) is h, and the cross section of the spring 26 is h. When the radius of the outer circumference is defined as r, the angle between the outer circumferential surfaces 40 and 38 of the groove 36 as α ₁ , and the angle between the inner circumferential surface 34 of the main lip portion 20 and the axis of the plug tube gasket as α ₂ To,
The following relationship is given between h, r, α ₁ and α ₂ in the free state of the plug tube gasket 10.

0.3r≦h≦2.0r α ₁ ≒α ₂ Also, does the upper end of the outer peripheral surface of the spring 26 vertically match the upper end surface 32 of the rubber portion of the main lip portion 20 where the spring 26 is embedded? Or nearly identical. Further, the outer circumferential end of the outer circumferential surface of the spring 28 radially coincides with or substantially coincides with the outer circumferential surface 30 of the rubber portion of the main lip portion 20 .

When the cylinder head cover 12 to which the plug tube gasket 10 is pre-installed is assembled to the cylinder head, the plug tube 18 fixed to the cylinder head cover side slides while rubbing against the inner periphery of the plug tube gasket 10 as shown in Fig. 2. The state will be as follows. At this time, if the axial center of the plug tube gasket 10 and the axial center of the plug tube 18 are aligned, the groove 36 should be just flattened.
The dimensional relationship between the outer peripheral surface 38 of the groove 36 and the outer peripheral surface of the plug tube 18 is given.

Next, the effect will be explained.

By forming the groove 36 with the determined dimensional relationship as described above in the main lip portion 20, the flexibility of the inner peripheral portion of the main lip portion 20 in contact with the plug tube 18 is improved compared to the conventional one. Improved.

After assembly, the state is shown in FIG. 2, and since the shape of the groove 36 is α ₁ ≒ α ₂ , the groove 36 is crushed, almost crushed, or crushed and compressed in the radial direction. It is in a state of being. In this state, since the height h of the groove 36 is 0.3≦h≦2.0r, the tensioning force of the spring 26 is applied to the portion of the main lip portion 20 that contacts the plug tube 18. Furthermore, because α ₁ ≒ α ₂ , when the groove 36 is collapsed, the inner circumferential surface of the contact portion of the main lip portion 20 to the plug tube 18 is essentially parallel to the outer circumferential surface of the plug tube 18 in the axial direction. Therefore, as shown in FIG. 2, the area of the contact surface has increased dramatically compared to the conventional one. Furthermore, due to the increased flexibility of the contact portion of the main lip portion 20 with the plug tube 18, even if the plug tube 18 and the plug tube gasket 10 are tilted during assembly, the tilt can be sufficiently absorbed.

FIG. 3 shows another embodiment of the invention. In FIG. 3, the groove 36 has a bottom surface 36a extending in a plane substantially perpendicular to the axis of the plug tube gasket 10. In FIG. It is shown that the groove 36 may be a substantially V-shaped groove having such a bottom surface 36a. Other configurations and functions are similar to the embodiments shown in FIGS. 1 and 2, so
The same reference numerals are given to the corresponding parts, and the explanation thereof will be omitted.

Comparing the function and action of the groove 36 with the groove of the sealing member of the shaft sealing structure of the above-mentioned Japanese Utility Model Publication No. 56-23756,
Groove 36 of plug tube gasket 36 of the present invention
This gives flexibility to the contact part of the main lip part 20 to the plug tube 18.
The groove of Japanese Patent Publication No. 23756 is very different in that it uses the laws of nature in the seal in that it applies hydraulic pressure to the lip formed by the groove.

[Effect of idea]

According to the sealing structure between the cylinder head cover and the plug tube of the present invention, the contact portion of the main lip portion with the plug tube becomes flexible, so that the following effects can be obtained.

(a) Better absorption of assembly eccentricity.

(b) Improves the ability to absorb tilt during assembly.

(c) Seal performance improves because the seal width becomes wider.

(d) The charging load during assembly is reduced and the ease of assembly is improved.

[Brief explanation of drawings]

Figure 1 is a partial cross-sectional view of an embodiment of the seal structure between the cylinder head cover and plug tube of the present invention in a free state, Figure 2 is a cross-sectional view of Figure 1 after assembly, and Figure 3 is the seal structure of the present invention. A partial cross-sectional view of another embodiment of
FIG. 4 is a partial sectional view of a conventional gasket. 10...Plug tube gasket, 16...
Cylindrical wall, 18... plug tube, 20... main lip portion, 26... spring, 36... groove.

Claims (1)

[Scope of utility model registration request] In the sealing structure between the cylinder head cover and the plug tube, a cylindrical wall is provided on the cylinder head cover parallel to the outer peripheral surface of the plug tube at a distance, and a plug tube gasket is interposed between the cylindrical wall and the plug tube. , consisting of a main lip part that brings the plug tube gasket into contact with the plug tube, a mounting part that fits into the inner peripheral surface of the cylindrical wall of the cylinder head cover, and a bellows part that connects the main lip part and the mounting part. A spring is attached to the main lip part, and an annular substantially V-shaped groove that opens upward is provided, and the shape of the groove is such that the depth of the groove is h, the radius of the cross section of the spring is r,
When the angle between the inner and outer circumferential surfaces of the groove is α ₁ and the angle between the inner circumferential surface of the main lip and the axis of the plug tube gasket is α ₂ , between h, r, α ₁ , and α ₂ , A seal structure between a cylinder head cover and a plug tube characterized by having a groove shape that satisfies the relationship 0.3r≦h≦2.0r and α ₁ ≒ α ₂ in a free state.