JP4036284B2 - Metal gasket - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal gasket that is interposed between joint surfaces of a cylinder block and a cylinder head constituting an internal combustion engine and seals between the joint surfaces, and in particular, at least one of the cylinder block and the cylinder head is made of aluminum. The present invention relates to a metal gasket suitable in some cases.
[0002]
[Prior art]
As a conventional metal gasket of this type, for example, a full bead is provided around the combustion chamber hole, and a step-shaped half bead is provided on the outer peripheral portion. The fastening bolt is interposed between the joint surfaces of the cylinder head and the cylinder block. There is known one in which the joint surface is sealed by tightening with a screw.
[0003]
[Problems to be solved by the invention]
By the way, in recent years, an engine in which at least one of a cylinder block and a cylinder head is made of aluminum has been used due to a demand for weight reduction or the like. Therefore, it is necessary to seal well for the cast hole.
However, in the conventional metal gasket, since there is one step-shaped half bead that is a surface pressure generating portion arranged on the outer peripheral portion, the contact with the joint surface on the casting hole generating side is about 1 mm wide. As a result, there is a problem in that only the casting hole can be sealed within a narrow range (when the bead straddles a hole having a width of 1 mm or more), sufficient sealing performance of the casting hole cannot be exhibited.
[0004]
The present invention has been made in order to eliminate such inconveniences, and a metal gasket capable of widening the seal surface (line) with respect to the joint surface on the casting hole generating side to improve the sealing performance of the casting hole. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 has a bead around the combustion chamber hole and a step-shaped half bead on the outer periphery, and is interposed between the joint surfaces of the cylinder head and the cylinder block. It is a metal gasket that seals between the joint surfaces by tightening with fastening bolts,
At least two half beads are arranged, a convex flat portion is provided between the adjacent half beads, and at least one of the half beads constituting the convex flat portion between the adjacent half beads is the fastening bolt. In the vicinity of the bolt insertion hole, the height is gradually lowered as it approaches the bolt insertion hole, and the cutting is performed in the middle, and the remaining half beads are continued in the circumferential direction.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. 1 is a plan view for explaining a metal gasket as an example of an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a sectional view taken along line BB in FIG. 4 and 5 are explanatory cross-sectional views for explaining a metal gasket according to another embodiment of the present invention. In this embodiment, a case where one of the cylinder block and the cylinder head is made of aluminum and applied to an engine having a casting hole generating portion on the joint surface is taken as an example.
[0007]
As shown in FIG. 1, the metal gasket 10 includes a substrate 11 made of a metal plate. A combustion chamber hole 12 is formed in the substrate 11 corresponding to the end of the cylinder bore. Around the combustion chamber hole 12, a full bead 13 is formed by curving the substrate 11, and bolt insertion holes 14 for fastening bolts are provided at a plurality of positions at substantially equal intervals in the circumferential direction of the substrate 11 outside the full bead 13. Is formed. Further, a step-like half bead 15 is formed on the outer peripheral portion of the substrate 11 by molding the substrate 11.
[0008]
Here, in this embodiment, two half beads 15 are arranged to provide a convex flat portion 16 (see FIG. 2) between the adjacent half beads 15, and one half bead 15 on the outer side. As shown in FIG. 3, in the vicinity of the bolt insertion hole 14 of the fastening bolt, the height is gradually lowered and cut in the middle, and the inner half bead 15 is made to continue in the circumferential direction on the combustion chamber hole 12 side of the bolt insertion hole 14. ing. In the figure, reference numeral 17 denotes a surface coating.
[0009]
Then, the metal gasket 10 having such a configuration is interposed between the joint surfaces of the cylinder block and the cylinder head with the convex side of the flat portion 16 facing the joint surface on the casting hole generating side, and is tightened with a fastening bolt. The full beads 13 and the half beads 15 are compressed and deformed in the plate thickness direction to generate a surface pressure, whereby a seal between the joint surfaces is achieved.
At this time, the two half beads 15 are compressed and deformed in the plate thickness direction with a low tightening force, and have less sag. Further, the flat portion 16 between the half beads 15 has a relatively small tightening force. In the vicinity of a fastening bolt with a relatively large tightening force, a high surface pressure is generated by the tightening force of the fastening bolt. As a result, the sealing performance of the cast hole can be improved.
[0010]
Further, one of the two half beads 15 is gradually lowered in the vicinity of the bolt insertion hole 14 and is cut in the middle, so that the fastening load of the fastening bolt is reduced to the combustion chamber hole 12 side (full bead 13 side). As a result, the sealing performance around the combustion chamber hole 12 can be improved without deteriorating.
In addition, by adjusting the distance between the two half beads 15 and changing the width of the flat portion 16, it is possible to adjust the generated surface pressure width against the cast hole, so that the sealing performance according to the size of the cast hole is achieved. It can be secured easily.
[0011]
In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.
For example, in the above embodiment, the case where the outer half bead 15 of the two half beads 15 is cut in the vicinity of the bolt insertion hole 14 and the inner half bead 15 is continued in the circumferential direction is taken as an example. Instead, the inner half bead 15 may be cut in the vicinity of the bolt insertion hole 14 and the outer half bead 15 may be continued in the circumferential direction.
[0012]
In the above embodiment, the case where two half beads 15 are arranged on the outer periphery of the substrate 11 is taken as an example. However, the present invention is not limited to this, and three or three or more half beads 15 are arranged. You may make it make at least 1 of these continue.
Furthermore, in the above embodiment, the case where one of the cylinder block and the cylinder head is applied to an engine made of aluminum is taken as an example. However, the present invention is not limited to this, and both the cylinder block and the cylinder head are used. Is made of aluminum and there is a casting hole occurrence site on each joint surface, for example, two metal gaskets 10 are arranged symmetrically up and down so that the convex side of the flat portion 16 is arranged up and down, Alternatively, as shown by a two-dot chain line in FIG. 2, it is possible to easily cope with the problem by arranging three half beads 15 and arranging the convex side of the flat portion 16 vertically.
[0013]
Further, as shown in FIGS. 4 and 5, a seal material 20 may be provided on the convex surface side and the concave surface side of the flat portion 16 to further increase the generated surface pressure of the flat portion 16. In this case, it is possible to cope with an engine in which both the cylinder block and the cylinder head are made of aluminum.
[0014]
【The invention's effect】
As is apparent from the above description, according to the present invention, since the sealing surface with respect to the joint surface on the casting hole generating side can be widened, the effect of improving the sealing property of the casting hole can be obtained. .
[Brief description of the drawings]
FIG. 1 is a plan view for explaining a metal gasket as an example of an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a cross-sectional view taken along line BB in FIG.
FIG. 4 is an explanatory cross-sectional view for explaining a metal gasket according to another embodiment of the present invention.
FIG. 5 is an explanatory sectional view for explaining a metal gasket according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Metal gasket 12 ... Combustion chamber hole 13 ... Full bead 14 ... Bolt insertion hole 15 ... Half bead 16 ... Flat part

Claims (1)

In addition to having a bead around the combustion chamber hole and a stepped half bead on the outer periphery, the space between the joint surfaces is sealed by tightening with a fastening bolt interposed between the joint surfaces of the cylinder head and the cylinder block. A metal gasket,
At least two half beads are arranged, a convex flat portion is provided between the adjacent half beads, and at least one of the half beads constituting the convex flat portion between the adjacent half beads is the fastening bolt. A metal gasket, characterized in that the height is gradually lowered as it approaches the bolt insertion hole in the vicinity of the bolt insertion hole and cut in the middle, and the remaining half beads are continued in the circumferential direction.

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