Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
2000-05-30
2001-10-23
Browne, Lynne H. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S612000, C277S596000, C277S644000, C277S626000
Reexamination Certificate
active
06305695
ABSTRACT:
This invention is concerned with gaskets, for example of the type which are used to create seals between the blocks and the heads of internal combustion engines.
Gaskets for use in, for example, automotive applications often comprise a supporting sheet, eg of steel, on one or both surfaces of which elongated beads are adhered. Such beads are made, eg by extrusion, from resilient material, eg elastomeric material, and are arranged to be compressed to create a seal between the supporting sheet and a surface of an adjacent member, eg a block or a head. The beads extend around continuous closed paths around openings through the gasket, for example the closed path may extend around the periphery of the gasket or, in the case of a head gasket, around the engine cylinders, oil passages, coolant passages or bolt holes.
The elongated resilient beads used in gaskets have a constant transverse cross-sectional shape along the bead, when the bead is in an uncompressed state. This cross-sectional shape is designed to ensure a good seal. However, where the bead is adhered to an upper surface of the supporting sheet, compression of the bead can cause great deformation thereof. This great deformation can cause the bead to be damaged or a bottom surface thereof may be torn off the supporting sheet with the result that the bead may be moved from its intended position.
It is known to reduce the deformation of a bead by forming a trough (or track) in the supporting sheet. The trough opens through a surface of the sheet, ie the upper or the lower surface of the supporting sheet. The trough has a substantially constant transverse cross-section, which may be rectangular or have tapering sides. The trough extends around the continuous closed path and the bead is mounted in the trough with a projection thereof extending out of the trough beyond the upper surface of the sheet so that the projection can be compressed to form a continuous seal along said path, the projection being arranged centrally of the trough. An example is illustrated in FR 2,411,688 A. It is also known, eg from U.S. Pat. No. 3,930,656, to provide the bead with two recesses, one on either side of the central projection as shown in
FIGS. 1 and 2
described below. The recesses extend parallel to said projection and are formed within said trough. An example of such a gasket is also described below in relation to
FIGS. 1 and 2
. The recesses are provided so that the bead material can be displaced into the recesses during compression of the bead. However, it is found in practice that the displacement of the bead material in two opposite directions results in creases occurring in the material with a consequential risk of damage to the bead.
It is an object of the present invention to provide a gasket having a bead with a reduced risk of damage.
The invention provides a gasket comprising a generally planar supporting sheet, the supporting sheet having a trough formed therein, the trough opening through an upper surface of the sheet and having a substantially constant transverse cross-section, the trough extending around a continuous closed path around an opening through the gasket, the gasket also comprising an elongated bead made of resilient material and having a substantially constant transverse cross-section, the bead being mounted in said trough and extending around said path, the bead comprising a projection which, in an uncompressed state of the bead, projects out of the trough beyond the upper surface of the sheet so that the projection can be compressed to form a continuous seal along said path, characterised in that said bead has a transverse cross-section defined by lower and side surfaces which conform to and engage bounding surfaces of the trough, and also defined by an upper surface which, in an uncompressed state of the bead, defines said projection and a recess extending parallel to said projection, the recess being formed within said trough, said projection being positioned on one side of the longitudinal centre-line of the bead and said recess being positioned on the other side of said centre-line.
In a gasket in accordance with the invention, the material of the bead forming the projection is displaced in only one direction and this is found to reduce creasing and hence the risk of damage to the bead.
In a gasket according to the invention, the transverse cross-sectional area of the recess may be substantially equal to the transverse cross-sectional area of the projection. This ensures that there is sufficient space for the displaced material to occupy even if the bead is compressed to the level of the upper surface of the supporting sheet.
Preferably, the projection has a side surface which is continuous with a side surface of the recess, ie the recess merges with the projection and the recess is appropriately positioned to receive the displaced material.
Preferably, for ease of manufacture of the bead, the upper surface of the bead also has planar portions joining the projection to one edge of the opening of the trough and also joining the recess to the other edge of the opening.
REFERENCES:
patent: 2373443 (1945-02-01), Armington
patent: 2513178 (1950-06-01), Jackson
patent: 2995057 (1961-08-01), Nenzell
patent: 3930656 (1976-01-01), Jelinek
patent: 4321225 (1982-03-01), Jelinek
patent: 4635949 (1987-01-01), Lucas et al.
patent: 5390939 (1995-02-01), Terauchi et al.
patent: 0 330 126 (1989-08-01), None
Browne Lynne H.
Federal-Mogul Technology Limited
Peavey Enoch
Synnestvedt & Lechner LLP
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