Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
1998-12-04
2001-02-13
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal between parts of internal combustion engine
59
Reexamination Certificate
active
06186513
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a method of forming gasket with an annular sealing projection and a sealing groove formed around a hole to be sealed.
In a conventional gasket, in order to seal around a hole, such as a cylinder bore, water hole, oil hole and so on, various sealing devices have been used. A bead is often formed around the hole to provide a surface pressure thereat. However, if only a bead is formed around the hole, a fluid in the hole may pass over the bead due to change of the surface pressure at the bead.
Therefore, in addition to or separately from the bead, a plate for the gasket may be turned around a hole to be sealed to provide a surface pressure around the hole. However, since a part of the metal plate is turned, the thickness of the gasket is increased at the turned portion. This is not preferable when a thin gasket is required. Especially, in case a gasket is formed of one metal plate, the turned portion is not preferable.
Also, a shim may be formed on a metal plate around a hole to be sealed, such as disclosed in U.S. Pat. No. 4,776,073. In this case, the shim with a proper thickness is selected, and attached onto the metal plate by welding and so on. Therefore, it takes time and labor when the shim is used. Also, it is difficult to attach a thin shim on the metal plate.
In Japanese Patent Publication (KOKAI) No. 7-91548, a gasket has a thick portion and a groove around a hole to be sealed.
However, the thick portion is not ideally arranged to properly seal around the hole. Also, when the thick portion is formed, the metal plate is excessively processed, so that the plate to be used is limited.
In view of the above, the present invention has been made, and an object of the invention is to provide a method of forming a thin metal gasket, which can provide a non-resilient surface pressure around a hole to be sealed.
Another object of the invention is to provide a method of forming a thin metal gasket as stated above, wherein the surface pressure around the hole can be selected as desired.
A further object of the invention is to provide a method of forming a thin metal gasket as stated above, which can be manufactured easily without substantial limitation for the metal plate.
Further objects and advantages of the invention will be apparent from the following description of the invention.
SUMMARY OF THE INVENTION
A metal gasket of the invention is basically formed of one metal plate. If desired, however, one or more metal plates may be laminated on the one metal plate to form a metal laminate gasket. The gasket is preferably used for an internal combustion engine, such as cylinder head gasket, but the gasket may be used for other purposes.
The metal plate includes a hole, an edge portion around the hole, and a base portion extending substantially throughout an entire area of the gasket outside the edge portion. At least one annular projection and at least one annular groove are integrally formed on at least one side of the edge portion of the metal plate as one unit. The annular groove is located between the annular projection and the base portion.
The metal plate has a thickness greater than a thickness at the annular groove and less than a thickness at the annular projection. Therefore, when the gasket is installed between the parts to be sealed and is tightened, the annular projection is non-resiliently compressed to provide a surface pressure thereat to thereby securely seal around the hole.
Since the annular projection is integrally formed with the metal plate for forming the gasket, the gasket with the projection can be formed easily. Also, the thickness of the projection can be adjusted easily as required. Further, since the surface pressure is concentrated at the annular projection when the gasket is tightened, the hole can be sealed securely and reliably.
The annular projection and annular groove may be formed on two sides of the edge portion of the metal plate, respectively. The annular projections and the annular grooves formed on both sides of the metal plate may be symmetrically arranged relative to a center plane of the metal plate. On the other hand, the annular projections formed on both sides of the metal plate may be located at a side opposite to the annular grooves, respectively. Namely, the annular projections and the grooves on both sides of the metal plate are arranged in a staggered relation.
The metal plate may further include a bead formed on the base portion to surround the hole. The bead projects outwardly beyond the upper surface of the projection. Thus, when the gasket is tightened, the bead is compressed to the height of the annular projection without being completely flattened. Therefore, creep relaxation of the bead is prevented or reduced by the annular projection.
The metal plate with the annular projection and the annular groove may be laminated on another metal plate, or may be formed in a clad metal plate. In this case, the another metal plate is laminated on the metal plate at a side where the annular projection and annular groove are not formed. Preferably, the metal plate is formed of a soft metal plate or layer, and the another metal plate is formed of a hard metal plate harder than the soft metal plate.
When the metal gasket is formed, a metal plate is prepared to have a hole, an edge portion around the hole, and a base portion extending substantially throughout an entire area of the gasket and located outside the edge portion. Then, at least two annular grooves substantially parallel to each other are formed on at least one side of the edge portion of the first metal plate by coining process to thereby form an annular projection between the two annular grooves. The base portion has a thickness greater than a thickness at the annular grooves and less than a thickness at the annular projection. The edge portion along the annular projection at a side of the hole, i.e. inner groove portion, may be cut to remove the groove adjacent the hole.
REFERENCES:
patent: 4836158 (1989-06-01), Panzica
patent: 5879012 (1999-03-01), Udagawa
patent: 5895054 (1999-04-01), Miyaoh et al.
patent: 5944095 (1999-08-01), Fukuoka et al.
patent: 5988651 (1999-11-01), Miyach
patent: 94 17 046 (1994-12-01), None
patent: 44 21 219 (1995-08-01), None
patent: 196 25 491 (1997-10-01), None
patent: 1 054 690 (1954-02-01), None
patent: 7-91548 (1995-04-01), None
Ishikawa Gasket Co. Ltd.
Kanesaka & Takeuchi
Knight Anthony
Peavey Enoch E
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