Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
2000-02-03
2001-11-27
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
C277S593000
Reexamination Certificate
active
06322084
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a metal gasket with a bore ring, in particular a metal cylinder head gasket with a bore ring to be installed between a cylinder head and a cylinder block of an internal combustion engine.
A cylinder head gasket installed between a cylinder head and a cylinder block of an engine is provided with a plurality of cylinder bores, water holes, oil holes, bolt holes and so on. In the engine, since high temperature and high pressure combustion gases are formed in the cylinder bores when the engine is actuated, sealings around the cylinder bores are important. Thus, the bolts for connecting the cylinder head and cylinder block with the gasket therebetween are arranged generally around the cylinder bores.
Also, sealing means, such as beads, are formed around the cylinder bores of the gasket. When the cylinder head and the cylinder block with the gasket therebetween are tightened, the sealing means are compressed to thereby form counter forces thereat, which generate sealing pressures to seal around the cylinder bores.
On the other hand, since the engine has been developed to provide high power and light in weight with small size, combustion gases with high pressures are formed. Thus, it is the tendency that the tightening pressure and the bead counter force are getting stronger.
Also, in the gasket, since the sealing means, such as bead, is exposed to high temperature and high pressure formed in the cylinder bore, there has been a problem that creep relaxation occurs in the bead, resulting in fatigue destruction of the bead.
As stated above, the engine is required to have light weight. Thus, the cylinder head and the cylinder block are formed of relatively light metal, such as aluminum or aluminum alloy. In this respect, since the gasket is formed of relatively hard metal, the gasket does not fit properly with the cylinder head and cylinder block formed of the light metal. Thus, the difference of heat expansion between the gasket and the engine parts, e.g. cylinder head and cylinder block, becomes greater. As a result, the rubbing occurs between the bead and the gasket attaching portions of the cylinder head and the cylinder block. Namely, the cylinder head and the cylinder block formed of relatively light metal are damaged by the expansion and contraction of the bead to thereby reduce the sealing ability around the cylinder bore.
In view of the above problems, U.S. Pat. No. 5,895,054 has been proposed, wherein a thick ring spacer or annular ring is situated in a cylinder bore of a metal plate for the gasket such that the annular ring does not come off or separate from the metal plate easily by press fitting at several portions.
In this gasket, the annular ring is formed accurately, and is assembled with the gasket. Thus, the surface pressure around the cylinder bore can be formed equally to securely seal around the cylinder bore. However, since the annular ring is very thin, it is very difficult to attach the annular ring to the metal plate with a press fitting. Also, since the annular ring is located inside the metal plate and the metal plate does not have a portion laminating with a different metal portion, the metal plate for the gasket does not have a cushioning mechanism with respect to the engine parts, i.e. cylinder head and cylinder block, so that the gasket does not fit so properly or closely with the engine parts. Especially, if a bead portion of the metal plate contacts the engine parts directly, the engine parts are likely to be damaged by the bead to cause gas leakage thereat.
The present invention has been made in view of the above conventional gaskets, and an object of the invention is to provide a metal gasket with a bore ring, which fits smoothly and closely with engine parts to securely seal around a hole to be sealed.
Another object of the invention is to provide a metal gasket with a bore ring as stated above, wherein a bead of the gasket is protected to prevent creep relaxation.
A further object of the invention is to provide a metal gasket with a bore ring as stated above, wherein a surface pressure for sealing can be accurately adjusted.
A still further object of the invention is to provide a metal gasket with a bore ring as stated above, wherein the gasket can be manufactured easily.
Further objects and advantages of the invention will be apparent from the following description of the invention.
SUMMARY OF THE INVENTION
A metal gasket for an internal combustion engine of the invention is basically formed of a main gasket portion extending substantially throughout an entire area to be sealed and formed of at least one metal plate. The main gasket portion has at least one hole to be sealed. In the invention, a bore ring is disposed inside the hole of the main gasket portion. The bore ring has a top portion and a bottom portion longer than the top portion to provide rigidity of the bore ring.
Preferably, the bore ring includes an annular portion disposed inside the hole, and a flange extending from the annular portion and disposed under the main gasket portion around the hole. In this structure, since the bore ring has an L-shape in cross section, the bore ring has a relatively high rigidity to resist deformation by the force applied thereto. When the annular portion is disposed inside the hole, the flange abuts against the main gasket portion, so that the bore ring can be easily positioned in the main gasket portion. Also, since the bore ring is not easily disengaged from the main gasket portion, the handling of the gasket in processing can be facilitated.
The main gasket portion may include a sealing device around the hole. In this case, the flange is disposed under the sealing device. The sealing device may be a bead in the form of a semicircular, mountain-like or trapezoidal shape. The sealing device may be an emboss or grommet already known in the art.
In the invention, the sealing pressure can be accurately adjusted by adjusting the thickness of the flange laminated with the sealing device. Thus, the sealing ability around the hole can be improved.
In case the sealing device of the main gasket portion is a bead, the flange may include a bead around the annular portion. In this case, the beads of the main gasket portion and the flange are laminated together. Since the resilient forces by the beads are increased by the two beads, high surface pressure is obtained by the beads around the hole to be sealed.
The main gasket portion may further include a second metal plate disposed under the metal plate and above the flange. The second metal plate may have a solid sealing portion between the sealing device and the annular portion of the bore ring to securely seal around the hole.
In the invention, the bore ring may have a trapezoidal shape in section, which has top and bottom portions parallel to each It other, an inner vertical portion and an outer inclined portion. The top portion has an outer diameter less than an inner diameter of the hole to be sealed, and the bottom portion has an outer diameter greater than the inner diameter of the hole. In this structure, the bore ring still has a sufficient rigidity, and when the bore ring is inserted into the hole of the main gasket portion, the inclined portion of the bore ring surely engages the main gasket portion. Thus, the bore ring can be easily and accurately assembled with the main gasket portion without precise arrangement.
Preferably, the bore ring is made of metal softer than the metal plate of the main gasket portion, such as aluminum or alloy thereof. The bore ring made of the soft metal fits the cylinder block and the cylinder head closely and properly, and does not hurt the cylinder block and the cylinder head. Thus, the sealing ability is improved. Also, when the bore ring and the main gasket portion are assembled by a press mechanism, they are properly fixed together to thereby improve the assembly.
In case the bore ring is made of aluminum or an alloy thereof, since the engine parts are generally formed of aluminum o
Kato Yutaka
Yamada Yoshio
Ishikawa Gasket Co. Ltd.
Kanesaka & Takeuchi
Knight Anthony
Rodgers Matthew E.
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