JPH08170732A - Rubber gasket - Google Patents

Abstract

PURPOSE: To provide a rubber gasket which prevents deterioration of gasket bodies for shielding both sides of the gasket bodies which seal a portion between a casing and a cover member. CONSTITUTION: A rubber gasket 6 is arranged between a seat surface 3 of a cylinder head 1 and a seat surface 5 of a cylinder head cover 2, for sealing therebetween. The rubber gasket 6 is composed of a reinforcing core plate 9, gasket bodies 10, 11 arranged on upper and lower surfaces of the core plate 9, compressed between the seat surfaces 3 and 5 and sealing them, and lips 12, 13 integrated with the gasket bodies 10, 11 for shielding inside and outside of the gasket bodies 10, 11. The gasket bodies 10, 11 and the lips 12, 13 are made of elastic rubber. The lips 12, 13 each have an elastic coefficient smaller than those of the gasket bodies 10, 11, and easily flexed with small pressurizing force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber gasket that seals between a casing and a cover member that closes an opening of the casing.

[0002]

2. Description of the Related Art Generally, a rubber gasket made of a rubber O-ring is used as a seal structure for sealing between a casing and a cover member that closes an opening of the casing, and a rubber gasket made of a rubber O-ring is used. A seal structure is known in which an O-ring is compressed between itself and a provided flange. There is also a sealing structure in which a plate-shaped rubber plate or the like is punched into a shape corresponding to the contour of the cover member to seal between the members.

The rubber gasket used for such a seal structure blocks fluid inside the casing or air outside the casing, so that it directly deteriorates or cracks due to direct contact with the fluid or air inside the casing. There was such a problem. Here, as a specific example regarding the problem of deterioration of the rubber gasket, a seal structure for sealing between a cylinder head (corresponding to a casing) and a cylinder head cover (corresponding to a cover member) will be described.

In a cylinder head of an internal combustion engine, lubricating oil is supplied to each operating portion such as a valve operating mechanism having an intake valve and an exhaust valve, a cam shaft for operating each valve operating mechanism, and a bearing. Therefore, a rubber gasket that prevents oil leakage is interposed in a compressed state between the upper portion of the cylinder head and the flange portion formed on the peripheral edge of the cylinder head cover.

In such a seal structure, the oil supplied to the cylinder head directly adheres to the inner surface of the rubber gasket, so that various additives added to the oil permeation or oil (for example, an oil antioxidant). The rubber gasket may be softened or hardened and cracked due to deterioration due to heat treatment and engine heat change. In order to prevent such deterioration and cracking of the rubber gasket due to oil, a rubber gasket is interposed between the cylinder head and the flange of the cylinder head cover, as seen in Japanese Utility Model Laid-Open No. 58-163655. At the same time, a configuration is known in which a flange portion that protrudes downward is provided inside the flange of the cylinder head cover.

[0006]

However, in the structure of the above-mentioned publication, the oil that has been made to project from the flange of the cylinder head cover to the inside of the flange so that the oil that has scattered from each operating portion of the cylinder head will cause the cylinder head and the cylinder head cover to move. However, since there is a gap between the collar and the cylinder head,
Oil may enter this gap and adhere to the rubber gasket.

Therefore, even if the cylinder head cover is provided with the brim portion for shielding between the cylinder head and the cylinder head cover as described above, it is not possible to prevent oil from adhering to the rubber gasket, and the rubber gasket There is a problem that deterioration cannot be prevented. Also, since the outside of the rubber gasket is in contact with air, the outside surface of the rubber gasket is oxidized by oxygen in the air to promote deterioration and harden, or ozone in the air may cause ozone cracks. There is a problem that it will occur.

In view of the above problems, it is an object of the present invention to prevent deterioration of the gasket body by shielding both sides of the gasket body that seals between the casing and the cover member.

[0009]

SUMMARY OF THE INVENTION The present invention is interposed between a casing and a cover member that closes an opening of the casing,
In a rubber gasket that seals between both members, an auxiliary gasket formed so as to shield the gasket body is provided on at least one of the inside and the outside of the gasket body that seals between the casing and the cover member. The gasket has a smaller elastic modulus than the gasket body.

[0010]

According to the present invention, the gasket body for sealing between the casing and the cover member is provided with the auxiliary gasket formed so as to shield the gasket body, and
By making the elastic coefficient of the auxiliary gasket smaller than that of the gasket body, the auxiliary gasket can shield the inside and outside of the casing from the gasket body, so that the fluid or air inside the casing directly contacts the gasket body. Is prevented. As a result, the gasket body is prevented from being deteriorated or cracked by the fluid or air inside the casing, and the durability of the gasket body is improved.

[0011]

1 to 3 show a first embodiment of a rubber gasket according to the present invention and a seal structure for a cylinder head and a cylinder head cover to which the first embodiment of the rubber gasket is applied. Incidentally, FIG. 1 is a longitudinal sectional view showing a state in which a cylinder head cover is attached to a cylinder head of an internal combustion engine,
2 is a plan view of the cylinder head cover seen from above,
FIG. 3 is an enlarged vertical cross-sectional view of the rubber gasket.

In each figure, a cylinder head (casing) 1
A seat surface 3 that also functions as an attachment surface to which the cylinder head cover (cover member) 2 is attached is provided on the upper peripheral edge portion of the. A flange 4 fixed to the cylinder head 1 is provided on a lower peripheral edge portion of the cylinder head cover 2 that closes an upper opening of the cylinder head 1, and a seat surface 5 is formed on a lower surface of the flange 4.

The cylinder head cover 2 is fixed to the upper part of the cylinder head 1 with the seat surface 5 of the lower peripheral edge portion facing the seat surface 3 of the cylinder head 1. A rubber gasket 6 is interposed between the seat surface 3 of the cylinder head 1 and the seat surface 5 of the cylinder head cover 2. The rubber gasket 6 is molded in a shape corresponding to the contour shape of the flange 4 so as to seal the entire space between the cylinder head 1 and the cylinder head cover 2, and the oil inside the cylinder head 1 does not leak to the outside. Prevent.

In this embodiment, the cylinder head cover 2 is fixed to the cylinder head 1 by tightening three tightening bolts 7 which are screwed into the screw holes (not shown) of the cylinder head 1 from the upper portion of the cylinder head cover 2. To be done.
Then, the rubber gasket 6 is compressed in the vertical direction by tightening the tightening bolt 7 to seal between the seat surfaces 3 and 5.

A space between the insertion hole of the cylinder head cover 2 through which the tightening bolt 7 is inserted and the tightening bolt 7 are sealed by a seal washer 8 together with the tightening of the tightening bolt 7. Here, the cross-sectional shape of the rubber gasket 6 that constitutes the main part of the present invention will be described.

As shown in an enlarged view in FIG. 3, the rubber gasket 6 is provided with a reinforcing core plate 9 and upper and lower surfaces of the core plate 9 and is compressed between the seat surfaces 3 and 5 so that the space between both members is reduced. Gasket bodies 10 and 11 for sealing, and gasket body 1
Lip parts 12 and 13 integrally provided with the gasket bodies 10 and 11 so as to shield the inside and outside of 0 and 11 respectively.
And has a symmetrical shape in the left-right direction and the vertical direction.

The rubber gasket 6 has substantially semicircular gasket bodies 10 and 11 on the upper and lower surfaces of a metal core plate 9, and lip portions 12 and 13 as auxiliary gaskets on the inside and outside of the gasket bodies 10 and 11. Each has a core plate 9
It was made by being integrally molded with. The gasket bodies 10 and 11 and the lip portions 12 and 13 are made of elastic rubber, and the lip portions 12 and 13 are formed so as to project in the vertical direction more than the gasket bodies 10 and 11.

Further, the lip portions 12 and 13 are thin rubber pieces formed so as to become thinner toward the tips thereof, and have an elastic coefficient (also referred to as a spring constant) smaller than that of the gasket bodies 10 and 11. Further, each of the lip portions 12 and 13 has a base end portion 1
Only 2b and 13b are formed so as to be integrated with the gasket bodies 10 and 11, and the tip portions 12a and 13a are inclined toward the inside and the outside of the cylinder head 1.
It can be easily bent even with a relatively small pressing force.

When the rubber gasket 6 having the above structure is mounted and the cylinder head cover 2 is fixed to the cylinder head 1 by tightening the tightening bolts 7, the lip portions 12, 1
The tip portions 12a and 13a of 3 come into contact with the seat surface 3 of the cylinder head 1 and the seat surface 5 of the cylinder head cover 2 and are elastically deformed to a curved state before the gasket bodies 10 and 11. And the seat surface 3 and the seat surface 5
Comes into contact with the gasket bodies 10 and 11, and the gasket bodies 10 and 11 are held in an elastically deformed state.

Each lip portion 1 of the rubber gasket 6
Since the tip portions 12a and 13a of 2 and 13 are easily bent and inclined, the tip portions 12a and 13a can be bent in the pressing direction without being turned over during the mounting process of the cylinder head 1. Rubber gasket 6 compressed in Figure 4
The attached state of is shown enlarged. The gasket bodies 10 and 11 of the rubber gasket 6 come into close contact with the seat surfaces 3 and 5 by being compressed between the seat surfaces 3 and 5 in the vertical direction.
As a result, the cylinder head 1 and the cylinder head cover 2
The space between and is sealed.

Further, in the respective lip portions 12 and 13, the tip portions 12a and 13a of the respective lip portions 12 and 13 are seated on the seat surface 3 while the cylinder head cover 2 is fixed to the cylinder head 1.
It is pressed by 5 and bends in a bending direction in the pressing direction, and is held in that state. Then, the lip portions 12, 13 bent in a curved shape
Shuts off both sides of the gasket body 10, 11. In this way, both sides of the gasket bodies 10 and 11 are cut off from the inside of the cylinder head 1 and the outside of the cylinder head 1 by the lip portions 12 and 13, and the oil inside the cylinder head 1 and ozone in the air are prevented. , 11
Is prevented from coming into contact with. Therefore, it is possible to prevent deterioration and crack generation of the gasket bodies 10 and 11 due to oil permeation and an oil additive, and to prevent oxidation of the gasket bodies 10 and 11 due to air and ozone crack generation due to ozone in the air.

As a result, deterioration or cracking of the gasket bodies 10 and 11 for sealing between the seat surfaces 3 and 5 is effectively prevented, so that the gasket bodies 10 and 11 maintain elasticity as rubber for a long period of time. The sealing effect can be maintained for a long period of time. That is, the durability of the rubber gasket 6 itself can be improved. Also, the lip portions 12 and 13 are in contact with oil and air,
Since it has low rigidity and bends with a small load, cracks are less likely to occur. Therefore, the lip portions 12 and 13 themselves can also maintain the shielding effect for a long period of time, which also extends the life of the gasket bodies 10 and 11.

Although the engine heat is transmitted to the rubber gasket 6 through the cylinder head 1, the lip portion 12,
Oil and air are blocked by 13 and the gasket body 1
Since 0 and 11 are not affected by oil or air, acceleration of deterioration of the gasket bodies 10 and 11 due to engine heat is prevented. Furthermore, the cylinder head 1 and the cylinder head cover 2 are in a non-contact state with the rubber gasket 6 interposed between both members, so that the vibration of the cylinder head 1 is absorbed by the elastic rubber gasket 6 and the cylinder head cover 2 is absorbed. There is no direct transmission. Therefore, the rubber gasket 6 suppresses the noise caused by the vibration around the cylinder head 1 to a low level, so that the quietness of the engine can be enhanced.

Further, since the rubber gasket 6 is constructed such that the gasket bodies 10 and 11 are protected from oil and air by the lip portions 12 and 13 as described above, an expensive rubber material having weather resistance and oil resistance is used. Since it is not necessary to use it, the manufacturing cost can be kept low. Moreover,
A rubber material having weather resistance and oil resistance generally tends to deteriorate in low temperature characteristics, but it is possible to use a normal rubber material as in the present invention and maintain the cold resistance of the rubber gasket 6. it can. Therefore, it is advantageous when used in cold regions where the temperature is low.

Incidentally, the rubber gasket 6 of the first embodiment described above.
In the above, since the core plate 9 is not always necessary, the core plate 9 may be removed. The second aspect of the present invention is shown in FIGS.
An example will be described. FIG. 5 shows an enlarged cross section of the rubber gasket of the second embodiment, and FIG. 6 shows the mounted state of the rubber gasket of the second embodiment.

As shown in both figures, the rubber gasket 21 includes a gasket body 22 which is compressed between the seat surfaces 3 and 5 to seal between the two members, and a gasket body which shields the inside and the outside of the gasket body 22. The main body 22 and the lip portions 23 and 24 are integrally provided. The lip portions 23 and 24 are integrally formed with the gasket body 22 such that the upper end sides of the gasket body 22 having an elliptical cross section are the base end portions 23b and 24b and the tip portions 23a and 24a extend obliquely downward. To be done.

The lip portions 23 and 24 are thin rubber pieces that are formed so that they become thinner toward the tips, and have an elastic coefficient smaller than that of the gasket body 22. Therefore, the lip portions 23 and 24 are easily bent with a relatively small pressing force. In this embodiment, the seat surface 5 is provided with a groove 25 into which the upper portion of the gasket body 22 is fitted. The groove 25 has a substantially semi-circular cross section, and inside the groove 25, not only the upper portion of the gasket body 22 but also the lip portions 23, 2
The base end portions 23b and 24b of No. 4 are also fitted.

The upper part of the gasket body 22 is the groove 2
5 is in close contact with the inner surface and is compressed downward, and the lower portion is in contact with the seat surface 3 and compressed upward. In this way, the gasket body 22 is compressed between the cylinder head 1 and the cylinder head cover 2 and seals between the seat surfaces 3 and 5. Also, the tip portions 23a, 2 of the lip portions 23, 24
As shown in FIG. 6, 4a elastically deforms so as to spread laterally by contacting the seat surface 3. Therefore, the lower portion of the gasket body 22 protruding from the groove 25 is
Lip portion 2 that is in contact with seat surface 3 and is bent inward and outward
It is shielded by the tip portions 23a, 24a of the 3, 24.

In this way, both sides of the gasket body 22 are cut off from the inside of the cylinder head 1 and the outside of the cylinder head 1 by the lip portions 23 and 24, so that oil inside the cylinder head 1 and ozone in the air are removed. Contact with 22 is prevented. Therefore, similarly to the first embodiment described above, it is possible to prevent deterioration and cracking of the gasket body 22 due to oil permeation and an oil additive, and to prevent oxidation of the gasket body 22 by air and ozone cracking by ozone in the air. can do.

As a result, deterioration or cracking of the gasket body 22 that seals between the seat surfaces 3 and 5 is effectively prevented, so that the gasket body 22 can maintain elasticity as rubber for a long period of time. The sealing effect can be maintained for a long time. That is, the durability of the rubber gasket 21 itself can be improved. In the above embodiment, the seal structure that seals between the cylinder head 1 and the cylinder head cover 2 has been described as an example, but the seal structure is not limited to this, and may be a seal structure that seals between the crankcase and the oil pan, for example. Of course, it can be applied.
Further, the present invention can be applied as long as it is a structure that seals between the casing and the cover member that closes the opening of the casing, and thus can be applied to the seal structure of a portion that is not related to the internal combustion engine as in the above embodiment. Needless to say.

Further, in each of the above embodiments, the lip portions are provided on both sides of the gasket body, but the present invention is not limited to this, and the lip portions may be provided only on the inside of the gasket body depending on the seal structure, or the gaskets may be provided. You may make it provide a lip part only on the outer side of a main body.

[0032]

As described above, according to the present invention, the gasket body for sealing the casing and the cover member is provided with the auxiliary gasket formed so as to shield the gasket body, and the elastic coefficient of the auxiliary gasket is increased. Since it is smaller than the gasket body, the auxiliary gasket can block the inside or outside of the casing from the gasket body. Therefore, it is possible to prevent the fluid or air inside the casing from directly contacting the gasket body,
This can prevent the gasket body from being deteriorated or cracked by the fluid or air inside the casing. As a result, the sealing effect of the gasket body can be maintained for a long time, and the durability of the rubber gasket itself can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a cylinder head and a cylinder head cover to which a first embodiment of a rubber gasket according to the present invention is applied.

FIG. 2 is a plan view of a cylinder head cover.

FIG. 3 is a vertical sectional view showing an enlarged sectional shape of a rubber gasket.

FIG. 4 is a vertical cross-sectional view showing a mounted state in which a rubber gasket is compressed between a cylinder head and a cylinder head cover.

FIG. 5 is an enlarged vertical sectional view showing a sectional shape of a rubber gasket according to a second embodiment.

6 is a vertical cross-sectional view showing a mounted state in which the rubber gasket shown in FIG. 5 is compressed between a cylinder head and a cylinder head cover.

[Explanation of symbols]

 1 Cylinder Head 2 Cylinder Head Cover 3,5 Seat Surface 4 Flange 6,21 Rubber Gasket 9 Core Plate 10,11,21 Gasket Main Body 12,13,23,24 Lip Part

Claims (1)

[Claims] 1. A rubber gasket that is interposed between a casing and a cover member that closes an opening of the casing and seals between both members, the inside or outside of a gasket body that seals between the casing and the cover member. A rubber gasket, wherein an auxiliary gasket formed so as to shield the gasket main body is provided on at least one of the two, and the elastic coefficient of the auxiliary gasket is smaller than that of the gasket main body.