Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
2001-08-30
2003-06-10
Swann, J. J. (Department: 3677)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal between parts of internal combustion engine
C277S594000, C277S595000, C277S598000
Reexamination Certificate
active
06575473
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metallic gasket such as cylinder-head gaskets and so on made therein with holes such as combustion holes, water holes, oil holes and so on and, more particularly, to a metallic gasket having a metallic sheet in which a recess formed around the hole is charged with an elastic sealing member to ensure sealing a joint between confronting members around the hole.
2. Description of the Prior Art
Conventionally, joints in high-pressure lines have been tightly connected with each other through gaskets interposed between flanges that are formed at pipe ends to be connected, one to each end. Among the gaskets ever used is an O-ring accommodated in recesses made in the mating surfaces of the flanges. Most O-rings have ever been considered and standardized as to design conditions such as the configuration of an O-ring itself, the configuration of a recess, the clearance into which the O-ring extends above the recess, and so on. With the metallic cylinder-head gaskets for engines, moreover, there has been used metallic plates that are provided on surfaces thereof with grooves in which elastic sealant of rubber, resinous material and so on is applied by, for example printing to seal around the holes made in the metallic plates for allowing coolant and the like to flow through there.
Recent trends in the automotive engine development are towards a lowering of the force needed to tighten head bolts, high-pressure combustion in engines, much wider use of aluminum alloys for major engine components, adoption of monolayer gaskets or reduction in number of metallic sheets to be overlaid to form the gasket, and so on. Nevertheless, the optimal design conditions for the cylinder-head gaskets to cope with the trends stated earlier do not yet come to light. Unlike the industrial fields where the O-ring has been ever used, most cylinder-head gaskets in the engine normally experience minor amounts of shrinkage and/or expansion during engine operation at not only areas limited around the water holes but also at other areas neighboring the head bolts tightened.
With the metallic gaskets, the elastic sealing member of rubber, resinous material and so on having the cross section in excess is preferable for ensuring a high statistic sealing stress when being squeezed. However, the excessive elastic sealant causes an occurrence of local bulge of the sealant between the mating surfaces to leave any clearance between the mating surfaces to be jointed tightly and further an occurrence of any strain and flowage of the sealant thereby hindering the elastic sealing member itself from following properly the shrinkage and/or expansion that might happen in the clearance between the mating surfaces of the cylinder head and the cylinder block, so that there is always a certain possibility that a fluid will leak through. Moreover, the elastic sealing member is apt to be much subject to premature degradation and any collapse due to stress loaded repeatedly. In contrast, the elastic sealing member sparse in cross section will have a strong possibility of failing in sealing effect. That is to say, the prior art has uncovered no critical condition to use the elastic sealing member of rubber, resinous material and so on within its elastic characteristic region.
Among prior sealing means around the bolt hole in the metallic gaskets is a monolayer metallic gasket in which there is provided a metallic sheet made with a folded flange around the bolt hole to allow tightening the gasket to the specified torque (refer to for example Japanese Patent Laid-Open No. 200506/1996, and Japanese Patent Application No. 2000-92021, a co-pending senior application of the present applicant). In the metallic gaskets recited just above, either the folded portion or the half bead chiefly provides the sealing construction around the bolt hole.
For example in another co-pending senior Japanese Patent Application No. 2000-83442, there has been also proposed an aluminum gasket provided with identical sealing constructions around the head-bolt holes. Even with the gasket recited earlier, however, there has not been followed any relation of the recess on the metallic sheet with the elastic sealant received in the recess.
Disclosed in, for example Japanese Utility Model Laid-Open No. 30628/1993 is another cylinder-head gasket in which a base sheet of the gasket is made on opposite sides thereof with grooves, one to each side, where printed sealing members are adhered to be raised above their associated sides. When the gasket is squeezed between the mating surfaces of the cylinder head and the cylinder block by tightening head bolts, the printed sealing members are allowed to make deformation to be embedded securely in the grooves on the opposite sides of the base sheet, thereby improving the sealing effect.
Japanese Patent Laid-Open No. 200503/1996 discloses a cylinder-head gasket in which a strip of sealant is equal in width to a groove in the metallic sheet so as to cover the overall bottom surface of the groove recessed below the associated side of the metallic sheet.
Moreover, the cylinder-head gaskets have been ever disclosed, in which the printed sealant is adhered in the groove to extend above the associated side of the base sheet. Nevertheless, such gaskets include only a recitation of any condition to raise the sealant above the side of the metallic sheet and, therefore they do not succeed to utilize well the elastic characteristics of the sealant itself for realizing the sealing means of high sealing reliability.
On the other hand, any multi-layered gasket especially for the engine construction with chain case is needed to provide seals simple in construction, with even high reliability. To cope with this, a three-layered gasket has been proposed as disclosed in, for example Japanese Patent Publication No. 20626/1991 and Japanese Patent Laid-Open No. 119836/1995. The three-layered gasket recited above has still a major problem of how to strengthen the seal on the lower metallic sheet at the chain case.
With the metallic gasket adapted for the cylinder-head gasket that is made therein with various holes such as combustion holes, water holes, oil holes, and bolt holes in which head bolts fit to joint together the cylinder head the cylinder block, it may be worthwhile providing an improved metallic gasket in which an elastic sealing member of rubber, resinous material and so on is placed in a recess or groove formed around the holes to ensure sealing effect around the holes, and in particular the elastic sealing member is kept in a specified relation with the recess or groove in their cross-sectioned configurations so as to utilize an elastic characteristic region inherent in the elastic sealing member itself for realizing the improvement in the sealing effect.
SUMMARY OF THE INVENTION
In a metallic gasket adaptable to a cylinder-head gasket interposed between the cylinder head and the cylinder block, a tri-face seal gasket interposed between the cylinder head and the cylinder block with chain case, and so on, a primary object of the present invention is to provide a metallic gasket of either monolayer type or multi-layered type, in which an elastic sealing member is placed in a recess formed around a combustion hole in a metallic sheet, and the elastic sealing member is kept in a specified relation with the recess or groove in their cross-sectioned configurations so as to use the elastic sealing member within an elastic characteristic region inherent in the elastic sealing member itself for realizing the improvement in the sealing effect, with even more inexpensive.
The present invention is concerned with a metallic gasket adapted to be disposed between mating surfaces of engine components, which is composed of a metallic sheet made with a hole and a recess surrounding around the hole, and an elastic sealing member installed in the recess, the improvement characterized in that the recess is defined by a bottom surface and side surfaces merging the bottom s
Hiramatsu Tsuyoshi
Sugimoto Kiyoshi
Yoshijima Kazuya
Browdy and Neimark , P.L.L.C.
Jackson André L.
Nippon Gasket Co. Ltd.
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