Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
1998-09-30
2001-10-09
DePumpo, Daniel G. (Department: 3611)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal between parts of internal combustion engine
C277S595000
Reexamination Certificate
active
06299175
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal gasket to be installed between the cylinder block and cylinder head of an engine.
2. Description of the Prior Art
It is common practice to install a metal gasket between the cylinder block and cylinder head of an engine to hermetically seal the combustion chamber.
As shown in attached reference
FIG. 16
, a metal gasket is sandwiched between a cylinder head and a cylinder block of an engine. Movement in the engine, chiefly in the transverse direction, imposes a large lateral stress onto a periphery of a folding part of a stopper so that a crack is often generated thereon. In practice, a. cylinder block is constructed from cast iron and a cylinder head is made from an aluminum alloy. However, the coefficients of thermal expansion of both materials differ significantly. As a result, movement of an annular pressure receiver attached to the cylinder block differs from that of a stopper attached to the cylinder head so that a large stress occurs on the periphery of the folding part during a temperature change of the engine. Particularly if the metal gasket consists of only a first gasket-constituting plate, the abovementioned difference is amplified and the stress acting on the periphery of the folding part is amplified.
The metal gasket for this purpose is usually constructed as follows: It is composed of a beaded plate (which is an elastic metal plate) and a stopper plate placed on top of the other. The beaded plate and stopper plate each has openings at the positions corresponding to the cylinder holes of the engine. The beaded plate has an annular bead (bulging toward the stopper plate) formed in the vicinity of the periphery of the opening. The stopper plate has a stopper (folded back toward the beaded plate) formed in the vicinity of the periphery of the opening. Thus, when the cylinder head is fixed to the cylinder block by means of a plurality of cylinder head tightening bolts, the stopper forms a space equal to its thickness in the vicinity of the bead so as to prevent the bead from being anomalously deformed.
It is also known that the beaded plate and stopper plate are provided with a coating layer of rubber (such as NBR rubber and fluororubber) so as to improve the metal gasket in sealing performance.
The above-mentioned metal gasket poses a problem associated with deformation. That is, the stopper formed on the stopper plate deforms the stopper plate surrounding the stopper convexly toward that side on which the stopper is formed. Likewise, the bead formed on the beaded plate deforms the beaded plate surrounding the bead convexly in the direction in which the bead bulges.
This deformation leads to an uneven rubber coating layer on the stopper plate and beaded plate, and the uneven coating layer results in poor sealing. In addition, the deformed stopper plate and beaded plate do not fit well to each other, resulting in the metal gasket deforming as a whole. Thus the deformed metal gasket is not snugly inserted between the cylinder block and cylinder head.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new metal gasket composed of a single plate or multiple plates which are almost free from warpage. The metal gasket composed of multiple plates is easy to assemble and install in the engine. The metal gasket composed of a single plate is easy to install in the engine.
The present invention is embodied in a metal gasket composed of an elastic metal plate, characterized in that the elastic metal plate has an opening corresponding to the cylinder hole of the engine, an annular stopper formed by folding back the periphery of the opening, and a stepped part formed along the outer periphery of the stopper, said stepped part projecting toward the side on which the stopper is formed.
According to a preferred embodiment, the metal gasket may have an annular bead (bulging toward the side on which the stopper is formed) formed along the outer periphery of the stopper on the gasket-constituting plate and a stepped part formed at the inner periphery of the bead.
According to a preferred embodiment, the gasket-constituting plate is one which is formed from precipitation hardened high-silicon duplex stainless steel by fabrication into a desired shape and age hardening, said stainless steel being composed of 0.05% and less carbon, 3-6% silicon, 5% and less manganese, 5-10% nickel, 6-12% (excluding 12%) chromium, 0.2-1% molybdenum, and 0.5-3% copper, with the remainder being iron (by weight).
According to a preferred embodiment, the gasket-constituting plate has a coating layer formed at least on the side opposite to that on which the stopper is formed.
According to a preferred embodiment, the gasket-constituting plate has a raised spacer layer formed by pattern printing with a heat-resistant, compression-resistant material, between the stopper and that part of the gasket-constituting plate which is opposite to the stopper.
According to a preferred embodiment, the metal gasket is composed of at least two kinds of gasket-constituting plates, one having a stopper formed thereon and the other having no stopper formed thereon, which are arranged such that the inner periphery of the folded part of the stopper of the former is inside the inner periphery of the opening of the latter.
According to a preferred embodiment, the metal gasket is composed of at least two kinds of gasket-constituting plates, one having a stopper formed thereon and the other having no stopper formed thereon, with the inner periphery of the folded part of the stopper of the former being of the same radius as that of the inner periphery of the opening of the latter.
REFERENCES:
patent: 3794333 (1974-02-01), Czernik et al.
patent: 4178983 (1979-12-01), Mochizuki et al.
patent: 4265679 (1981-05-01), Ohashi et al.
patent: 4836562 (1989-06-01), Yoshino
patent: 5240261 (1993-08-01), Udagawa et al.
patent: 5286039 (1994-02-01), Kawaguchi et al.
patent: 5348315 (1994-09-01), Kawaguchi et al.
patent: 5431418 (1995-07-01), Hagiwara et al.
Abe Yoshitaka
Maekawa Hisato
Mahigashi Reizi
Yamato Kazuhiko
Armstrong Westerman Hattori McLeland & Naughton LLP
DePumpo Daniel G.
Kokusan Parts Industry Co., Ltd.
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