JPH0893918A - Metal gasket - Google Patents

Abstract

PURPOSE: To stabilize the seal performance by contracting a gap made between a cover and a main body after fastening bolts and changing a distance between the fastening bolt holes to the height and width of beads corresponding to the gap change between the cover and main body caused by the bolt fastening force. CONSTITUTION: A sealing bead 2 formed on a metal gasket 1 provides a full bead 5 in the intermediate part 4 between fastening bolts holes 3, 3. The outside shape of full beads 5 in the intermediate part 4 on the outer peripheral side of the metal gasket 1 is formed as it approaches the fastening bolts 3 from the intermediate part 4. In the inner peripheral side of the metal gasket 1 the inside shape of the full bead 5 of the intermediate part 4 is gradually changed and deformed into a half bead 6. The half bead 6 spanning the fastening bolt hole 3 and one side of the full bead 5 on the outer peripheral side of the metal gasket are integrally interconnected around the fastening bolt hole 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cover for a cylinder head, a valve chamber, a water hole, an oil hole, an air hole, etc. of an internal combustion engine, which is bolted to a main body. The present invention relates to a metal gasket in which a gap generated between the two is reduced toward the inside of the bolt fastening portion.

[0002]

2. Description of the Related Art Conventionally, a metal gasket interposed between a joint surface of a cylinder head and a cylinder block of an internal combustion engine and other joint surfaces of general parts has a bead formed to seal the joint surfaces, The cylinder head is elastically deformed by the bolt tightening force, and the elastic restoring force at the time of this deformation exerts a bead load on the joint surfaces to achieve a seal between the joint surfaces and to follow the distortion of the joint surfaces. I try to maintain the sealing effect.

[0003]

4 and 5 show a conventional example of the metal gasket as described above.

The metal gasket 23 shown in FIG. 4 is inserted between the joint surfaces of the cover 20 and the main body 21, and a full bead 25 having a semicircular cross section is formed inside the tightening bolt hole 24. In the metal gasket 23, the bead load inside the tightening bolt hole 24 is larger than the load outside the bead load. Therefore, the clearance θ1 inside the bolt hole 24 becomes larger than the clearance θ2 outside the bolt hole 24, resulting in a large amount of distortion inside the bolt hole 24, and the sealing performance becomes unstable.

Further, since the clearance inside the bolt hole 24 is large, the bead 25 provided inside the bolt hole 24 is easily bent, and as a result, the torque of the tightening bolt 26 is easily reduced.

This phenomenon occurs in the case of a metal gasket inserted between the cylinder head and the cylinder block.
Particularly, when the cylinder head is hit by the explosion in the combustion chamber hole, the bead 25 inside the bolt hole 24 is easily bent, and the torque of the tightening bolt 26 is significantly reduced.

Further, as shown in FIG. 5, when the metal gasket 27 is provided with the bead 28 formed in the same shape inside and outside the bolt hole 24, the total deformation amount θ3 is generated by the bolt fastening force of the cover 20. And cover 2
When 0 is bolted from four directions, the cover 20 is deformed so that the center is lifted, so that the gap between the cover 20 and the main body 21 inside the bolt hole 24 becomes larger than the gap on the outside, and the corresponding strain is generated. This occurs on the cover 20, and as a result, the sealing performance becomes unstable.

The gap between the cover 20 and the main body 21 is
Although it is small in the periphery of the tightening bolt hole 24, it increases as it goes from the bolt hole 24 to the middle of the adjacent bolt hole 24. Therefore, the bead 28 formed in the same shape inside and outside the bolt hole 24 has the same shape. However, the change cannot be dealt with and the sealing performance becomes unstable.

The present invention has been made in order to solve the above-mentioned conventional problems, and not only a head gasket inserted between a cylinder head and a cylinder block of an internal combustion engine, but also a cover between a general part and a main body. In the metal gasket that is inserted into the bolt, the gap between the cover and the body after bolt tightening has a bead shape that reduces toward the inner side of the bolt tightening part to ensure stable sealing and tightening. By preventing torque down of the bolt and changing the height and width of the bead corresponding to the gap change between the cover and the body between the tightening bolt holes by the bolt fastening force, the entire joint surface between the cover and the body It is an object of the present invention to provide a metal gasket that exerts an even sealing surface pressure and stabilizes the sealing performance.

[0010]

In order to achieve the above object, in the metal gasket of the present invention, the sealing bead formed on the metal gasket is a full bead at an intermediate portion between the tightening bolt holes. The outer shape of the middle bead is formed on the outer peripheral side of the metal gasket, and the inner shape of the middle bead is gradually formed on the inner peripheral side of the metal gasket, as it approaches the tightening bolt hole from the portion. The bead shape in which the half bead straddling the tightening bolt hole and one side of the full bead on the outer peripheral side of the metal gasket are integrally connected around the tightening bolt hole. Is characterized by. Further, the width and height of the intermediate bead between the tightening bolt holes and the full bead on the outer peripheral side of the metal gasket may be changed according to the gap generated between the cover and the main body when tightening the tightening bolt. .

[0011]

In general, when the cover is bolted from the periphery to the body, the center of the cover is deformed so as to be lifted, so that the distortion such that the inner clearance of the tightening bolt hole is larger than the outer clearance is applied to the cover. give.

In the above structure, the full bead is provided outside the tightening bolt hole and the half bead is provided inside the tightening bolt hole. When the tightening bolt hole is bolted, the full bead outside the tightening bolt hole serves as a stopper. Then, a surface pressure that causes the center of the cover to be recessed is generated in the cover, and the clearance inside the tightening bolt hole becomes smaller than the clearance outside.

Since the distortion of the cover by the metal gasket of the present invention acts as a distortion in the direction opposite to the tightening distortion of the cover in the general case (where the metal gasket of the present invention is not provided) described above, both of them are It is possible to cancel each other and bolt the joint surface between the cover and the main body with a gap having a constant width.

Further, since the full bead is formed between the tightening bolt holes, it becomes easy to change the width and height of the bead corresponding to the change in the gap between the cover and the main body due to the bolt fastening force.

[0015]

1 is a plan view of a metal gasket according to the present invention. 2 (a) is a sectional view taken along the line AA of FIG.
2B is a sectional view taken along the line BB of FIG. 1, and FIG. 2C is a sectional view taken along the line CC of FIG. FIG. 3 is a cross-sectional view around the tightening bolt hole showing a state where the metal gasket according to the present invention is mounted.

The metal gasket shown in FIG. 1 is a metal gasket which is interposed between the joint surfaces of the cover 7 and the body 8 such as water holes and oil holes. The present invention is not limited to the cylinder head and the cylinder block. It is possible to apply a metal gasket or the like, which is interposed between the joining surfaces of and, corresponding to the cover to the main body, to all the metal gaskets to be interposed when bolts are fastened at several places around the main body.

1 and 2 (a) to 2 (c), a metal gasket 1 surrounding an opening 10 such as a water hole or an oil hole.
Are formed, and tightening bolt holes 3 are respectively provided at the four corners.

A sealing bead 2 is formed around the metal gasket 1. The sealing bead 2 is beaten at an intermediate portion 4 between the tightening bolt holes 3 and 3, as shown in FIG. 2 (a). A full bead 5 having a height h1 and a bead division width L1 and a semicircular cross section is formed.

Then, as the tightening bolt hole 3 is approached from the intermediate portion 4, as shown in FIG. 2B, the beat formed on the intermediate portion 4 toward the outer peripheral side of the metal gasket 1. The outer shape 5a of the full bead 5 having the height h2 <h1 (the outer width L2 where the bead is divided L2> L1) is formed, and the intermediate portion 4 is formed on the inner peripheral side of the metal gasket 1.
Inner shape 5b of the full bead 5 (divided inner width L3>
L2) is gradually changed and transformed into a half bead 6.

In the vicinity of the tightening bolt hole 3, as shown in FIG.
As shown in (c), the tightening bolt hole 3 straddles the half bead 6 (the divided inner width L5> L3), and the outer shape 5a of the full bead 5 on the outer peripheral side of the half bead 6 and the metal gasket 1 (of the bead). Divided outer width L4>
L2) are integrally connected at a bead height h3 <h2.

In such a metal gasket 1,
As shown in FIG. 3, when the cover 7 is fastened to the main body 8 with bolts 9 from four directions, the outside of the tightening bolt hole 3 is the outer shape 5 a of the full bead 5, and the inside is the half bead 6, When the bolt 9 is inserted into the tightening bolt hole 3 and tightened, the bead load F1>F2> F
3, the full bead 5a outside the tightening bolt hole 3
Serves as a stopper, and a surface pressure that causes the center of the cover 7 to be recessed is generated in the cover 7, so that the clearance β1 inside the tightening bolt hole 9 becomes smaller than the clearance β2 outside.

Since the strain of the cover 7 due to the metal gasket of the present invention acts as a strain in the direction opposite to the tightening strain of the cover 7 when the metal gasket 1 of the present invention is not provided, they cancel each other out. , Cover 7 and body 8
It becomes possible to fasten the bolts with the joint surface with the gap having a constant width.

Since the full bead 5 is formed between the tightening bolt holes 3 and 3, the bead surface is defined as the width and height of the full bead 5 corresponding to the change in the gap between the cover 7 and the main body 8 due to the bolt fastening force. The pressure can be changed to ensure uniform sealing performance around the joint surface between the cover 7 and the main body 8.

[0024]

As described above, according to the metal gasket of the present invention, the full bead is provided outside the fastening bolt hole and the half bead is provided inside the fastening bolt hole. The full bead on the outside of the bolt hole plays the role of a stopper, and the surface pressure that causes the center of the reduction cover to be recessed toward the inside of the bolt fastening part is generated on the cover, and the gap inside the tightening bolt hole is more than the outside gap. Since it shrinks and acts as a strain in the opposite direction to the general tightening strain of the cover, they cancel each other out, and the joint surface between the cover and the main body can be bolted with a gap of a certain width, resulting in a sealing property. Can be prevented and the torque of the tightening bolt can be prevented from decreasing.

Further, the spring constant is changed by changing the height and width of the bead between the tightening bolt holes so as to correspond to the change in the gap between the cover and the body due to the bolt tightening force, thereby changing the spring constant and the joint surface between the cover and the body. The uniform sealing surface pressure can be exerted on the whole, and the stabilization of the sealing performance can be achieved.

[Brief description of drawings]

FIG. 1 is a plan view of a metal gasket according to the present invention.

2 (a) is a sectional view taken along the line AA of FIG.
2B is a sectional view taken along the line BB of FIG. 1, and FIG. 2C is a sectional view taken along the line CC of FIG.

FIG. 3 is a cross-sectional view around a tightening bolt hole showing a state in which a metal gasket according to the present invention is mounted.

FIG. 4 is a cross-sectional view around a tightening bolt hole of a conventional metal gasket.

FIG. 5 is a cross-sectional view around a tightening bolt hole of another conventional metal gasket.

[Explanation of sign]

DESCRIPTION OF SYMBOLS 1 ... Metal gasket, 2 ... Sealing bead, 3 ... Tightening bolt hole, 4 ... Intermediate part between fastening bolt holes, 5 ... Full bead, 5a ... Full bead outer shape, 5b ... Full bead inner shape, 6 ... Half bead, 7 … Cover, 8… main body.

Claims (2)

[Claims] 1. A sealing bead (2) formed on a metal gasket (1) is made into a full bead (5) at an intermediate portion (4) between tightening bolt holes (3, 3), and the intermediate portion (4). ) Closer to the tightening bolt hole (3), the outer shape of the full bead (5) of the intermediate portion (4) is formed on the outer peripheral side of the metal gasket (1), and the metal gasket (1) has an outer shape. On the inner peripheral side, the inner shape of the full bead (5) of the intermediate portion (4) is gradually changed and transformed into a half bead (6), and the tightening bolt hole (3) is surrounded by the tightening bolt hole (3). ), The half bead (6) and one side of the full bead (5) on the outer peripheral side of the metal gasket are integrally connected to each other to form a bead shape. 2. The cover (at the time of tightening the tightening bolt) such that the width (4) of the intermediate portion (4) between the tightening bolt holes (3, 3) and the full bead (5) on the outer peripheral side of the metal gasket (1) is the same. Metal gasket according to claim 1, characterized in that it has been modified according to the gap created between 7) and the body (8).