Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for other than internal combustion engine – or...
Reexamination Certificate
1999-12-10
2002-03-12
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for other than internal combustion engine, or...
C277S642000, C277S312000, C464S906000, C464S143000
Reexamination Certificate
active
06354604
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a sealing assembly on a constant velocity universal joint which comprises an outer joint part with at least one aperture at an axial end, an inner joint part having a driveshaft connected thereto and being inserted into said outer joint part, and further comprising rolling members effective between the outer joint part and the inner joint part and serving the transmission of torque, wherein at least one sheet metal element, by means of an annular face, rests on an end face of the outer joint part, with the outer joint part and the sheet metal element being clamped to one another.
Constant velocity universal joints in the present sense can be constant velocity universal ball joints or tripod joints or similar joints serving the transmission of torque. Constant velocity universal joints of said type are normally supplied by the manufacturer as integral parts of complete drive shafts consisting of a shaft shank and two joints mounted at the driveshaft ends. The joints comprise a grease filling and the respective outer joint parts are ready to be mounted on counter flanges. The outer joint parts are sealed relative to the shaft shank by convoluted boots. Said boots can be secured especially to sheet metal rings which, in turn, form annular faces which are to be bolted to end faces of the outer joint part. In the case of joints which, as so-called disc joints, comprise a second aperture, there are provided further sheet metal parts in the form of sheet metal covers which seal the joints not only during transport but also permanently in operation. For this purpose, the sheet metal covers are clamped in between the outer joint part and the flange. For sealing purposes elastic sealing elements are provided between the metallic faces which rest on one another. This is because the inaccurately machined metallic surfaces cannot, without fail, prevent the grease from emerging during operation under the influence of centrifugal forces when the grease is thin. Grease thinning occurs due to an increase in temperature. However, such elastic sealing elements which are arranged between metallic parts bolted to one another and which are under pre-tension are subject to a settling process. From this the, tensioning bolts lose some of their tensioning force, so that, in the final analysis, they can become loose. However, for safety reasons, it is important that such loosening of the bolts be avoided. In view of today's standards/requirements, subsequent tensioning of the bolts after a running-in phase is no longer acceptable.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a sealing assembly of said type which safely fulfills its sealing function, but which eliminates any settling symptoms after the clamping operation and avoids said consequential damage.
This and other objects and advantages are achieved by a sealing assembly having a first face—the annular face or the end face—including a surface structure with planar contact faces and recesses or grooves machine-produced therein, and the respective other face—the annular face or the end face—forming a planar counter face, with plastic-elastic sealing material being inserted between the annular face and the end face and with the plastic-elastic sealing material—up to the point of contact between the planar contact faces and the planar counter face—being formed into the recesses or grooves of the surface structure. After an initially planar surface has been produced, the recesses or grooves are formed into the planar surface. The plastic-elastic consistency of the sealing material guarantees complete sealing while compensating for surface inaccuracies in the annular face or in the opposed end face. By carrying out a tensioning operation until there exists metallic contact between the planar contact faces and the opposed planar face, any settlement of the plastic-elastic material is impossible. At the same time, the design of the planar contact faces and of the recesses or grooves ensures that there remains a continuous sealing ring—even if the sealing ring is punctually interrupted—so that there cannot occur any escape routes for the grease due to a partial destruction of the sealing ring.
In a first embodiment, the surface structure is produced by cross-knurling, as a result of which the areas positioned between the grooves produce the metallic contact, but the network formed by the crossed grooves produces an annularly closed sealing structure. Such knurling can also be applied to the end face of the outer joint part.
It can be particularly advantageous if the plastic-elastic sealing material is displaced radially inwardly or radially outwardly into a region where there exists a gap between the sheet metal element and the outer joint part, which gap is no longer interrupted by contact faces, so that there is obtained a widened, uninterrupted sealing ring.
In a second embodiment, the surface structure consists of a circumferential groove which is stamped into a planar contact face and which ensures complete annular sealing when the planar contact face is in contact with the counter face. The circumferential groove can be particularly easily stamped into the sheet metal cover.
In a preferred embodiment, the surface structure is produced in the sheet metal element which is easier to handle and consists of a softer material, in which case the end face of the outer joint part is planar. However, the present invention also allows a reversal of said geometric conditions.
If the sheet metal element forms the sheet metal ring for fixing a convoluted boot, the metallic contact with the contact faces of the surface structure preferably takes place in the region of the bolt heads of the tensioning bolts in order to eliminate any settling symptoms. If in the regions between each two bolt heads the applied sealing material is displaced to a lesser extent, this does not adversely influence the sealing effect.
If the sheet metal element forms the sheet metal cap between the outer joint part and the flange for sealing the outer joint part at the second aperture, it is important, however, to ensure a fully circumferential metallic contact between the contact faces and the counter face, i.e., especially the planar face of the outer joint part.
An inventive method of producing a sealing assembly in accordance with the invention consists in that a continuous ring consisting of a plastic-elastic sealing material is placed on to the annular surface or on to the end face and that, while the cover and/or the annular member, and the outer joint part and the flange are being clamped together, the sealing material is displaced until a metallic contact is established between the planar contact faces of the surface structure and the planar counter face. The sealing material can consist of a conventional high-viscosity plastic material which is applied to the grid-like annular face/circumferential groove or to the planar counter face in an annularly closed worm. The sealing material can, optionally, be a pressed out bead member whose thickness should have only a slight over-dimension relative to the grid-like or grooved surface structure to be able to flow away under pressure in the indentations. Other objects and advantages of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.
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GKN Lobro GmbH
Patel Vishal
LandOfFree
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