JPH0526380Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a metal gasket.

[Prior art]

For example, as a means of strongly sealing between the cylinder block and cylinder head of an internal combustion engine,
Traditionally, metal laminated gaskets have been used.
A bead portion is provided on the laminated metal plate surrounding the portion to be sealed, for example, the cylinder bore, thereby achieving sealing performance.

FIG. 4 shows an example of a conventionally used metal laminated gasket provided with the bead portion. The figure is a partially cutaway perspective view of the peripheral portion of the cylinder bore 2 of the metal laminated gasket 1. As shown in FIG. The metal laminated gasket 1 shown in the figure consists of an upper plate 3,
It is made by laminating four thin metal plates, middle plates 4 and 5 and a lower plate 6, and the bead part 7 is formed by surrounding the cylinder bore 2 and bulging the middle plate 5 to one side.
Also, in order to make the cylinder bore 2 side airtight, the lower plate 6 around the cylinder bore 2 is folded back so as to cover the ends of each plate 3, 4, and 5, and the upper plate 3 is folded back so that the bead portion 7 is covered. It was covered with

By the way, the metal laminated gasket 1 is sandwiched between a cylinder head and a cylinder block (not shown) and tightened with bolts to maintain airtightness, but the internal pressure increases due to improved performance of internal combustion engines.
Due to the thinning of the walls and use of lighter alloys for each of the above-mentioned members due to the demand for weight reduction of internal combustion engines, sufficient tightening force and uniformity of the force cannot be obtained, resulting in problems in maintaining airtightness.

As a means to solve the above problem, for example, Japanese Utility Model Application Publication No. 58-148247 discloses laminating face plates on both sides of two core materials, folding back one face plate on the cylinder hole side, and stacking the other face plate. This disclosure discloses a cylinder head gasket which is superimposed on the core material and has a bulge formed at the cylinder hole side end of the core material. The thickness of the bulge in a portion where surface pressure is insufficient, such as the middle portion of the head bolt, is made thicker than the thickness of the bulge in a portion near the head bolt where high surface pressure can be obtained.

It is explained that when a cylinder head gasket formed in this manner is tightened with a head bolt, a higher surface pressure is generated in the thicker bulge than in the thinner bulge. However, if the seal bead is too high, it will collapse when compressed, and if it is too low, sufficient contact pressure will not be generated, so it is difficult to reliably adjust the contact pressure by adjusting the seal bead height. There is a problem.

[Purpose of invention]

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a metal gasket in which beads act effectively even in areas where sufficient pressure contact force cannot be obtained, and sufficient airtightness can be obtained. It is an object.

[Structure of the idea]

The structure of the metal gasket of the present invention to achieve the above object is to provide a seal bead surrounding a sealing hole opened in a metal plate, and to attach a seal bead to the top of the bead where the surface pressure of the seal bead is low. A protrusion is provided along the longitudinal direction of the seal bead.

Since the protrusion increases the rigidity of the bead and the pressure contact point, it is possible to increase the surface pressure of the portion where the protrusion is provided.

The shape of the above-mentioned protrusion is that a normal bead has a cross-sectional shape in the direction perpendicular to the longitudinal direction of a circular arc or a shape close to this, but the curvature of the top part is larger than the curvature of the circular arc, and in some cases it is bent. This means that it has a similar shape.

The protrusions provided on the bead portion act to increase the stress per unit sealing surface by pressing into contact with each other, thereby improving the sealing performance of this portion.

The portion where the protrusion is provided is, for example, a portion such as the cylinder head in the middle of the tightening bolt where the pressure contact force is weakened by slight deformation, but in this device the protrusion can be formed over the entire circumference of the bead portion.

〔Example〕

Hereinafter, the present invention will be described in detail by way of an embodiment with reference to the accompanying drawings.

FIG. 1 is a partially broken perspective view of this embodiment, and FIG. 2 is a partial plan view of an intermediate plate provided with a bead portion. FIG. 1 illustrates parts corresponding to FIG. 4, and similar members are given the same numbers and their explanations will be omitted. Note that the cross section shown in FIG. 1 is a cross section taken along the - line in FIG. 2.

In the figure, the protrusion 10 provided on the seal bead portion (hereinafter simply referred to as bead portion) 7 of this embodiment is as follows:
As shown in FIG. 2, it is provided in the middle of the tightening bolt hole 11. Metal laminated gasket 1 in the figure
shows a case where the tightening force is unevenly distributed depending on the location. Therefore, the bead portion 7
The lengths l of the protrusions 10 provided in each part are different from each other. This is not essential to the present invention, and is merely a result of providing it in a portion where the pressure contact force decreases. Therefore, unless there is a condition that makes the tightening force of each part uneven, the above-mentioned lengths 1 can of course be made to be the same length.

The function of the metal laminated gasket 1 of this embodiment will be explained based on FIG. The lower diagram in Figure 3 corresponds to the cross section (shaded area) in Figure 1.
The upper diagram is a stress distribution diagram generated on the upper plate by the bead portion 7 and the protrusion portion 10. In the figure,
This is a schematic diagram showing a state in which a metal gasket 1 is sandwiched between a cylinder block 12 and a cylinder head 13 and pressed together by bolts (not shown).

The bead portion 7 and projection portion 10 shown in FIG. 1 are pressed by the cylinder block 12 and cylinder head 13, and are crushed to the thickness of the intermediate plate 4. The bead portion 7 and the protruding portion 10 connect the upper plate 3 to a, b, c in the figure, and the lower plate to d, e, f, respectively.
The stress shown in the upper part of FIG. 3 is generated in the upper plate 3 by pressing at the line or band-shaped portion (points in the figure) of g. Therefore, there are more press-contact parts b than in the conventional bead part 7 shown in FIG. 4, improving sealing performance.

[Effect of idea]

As explained above, since the metal gasket of the present invention is constructed, it is possible to improve the sealing performance of the part where the protrusion is provided. Therefore, when a high tightening force to press the bead part cannot be obtained, for example, a tightening bolt can be used. Even if there is a portion where the tightening force is insufficient in the middle portion of the bead portion, it is possible to achieve the effect that high sealing performance can be obtained in the entire bead portion.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of the main parts of a metal laminated gasket according to one embodiment, and FIG.
FIG. 3 is an explanatory view showing the usage state of FIG. 1, and FIG. 4 is a partially cutaway perspective view of the main part of a conventional metal laminated gasket. 1...Metal laminated gasket, 3...Top plate, 6...
...Lower plate, 7...Bead part, 10...Protrusion part.

Claims (1)

[Scope of utility model registration request] A metal gasket in which a seal bead is provided surrounding a sealing hole opened in a metal plate, and a protrusion is provided along the longitudinal direction of the seal bead at the top of the bead where the surface pressure of the seal bead is low.