Shaft seal assembly

Details Shaft seal assembly Shaft seal assembly

2000-03-23

2001-12-11

Knight, Anthony (Department: 3626)

Seal for a joint or juncture

Seal between relatively movable parts

Circumferential contact seal for other than piston

C277S916000, C384S484000, C384S486000

Reexamination Certificate

active

06328312

ABSTRACT:

FIELD OF THE INVENTION
The invention relates generally to a shaft seal assembly for sealing between a shaft and a machine housing and particularly to a shaft seal assembly comprising a casing for lip seal devices which follow any thermal or mechanical deformation of the shaft by virtue of ball bearings.
BACKGROUND OF THE INVENTION
A shaft seal assembly of this kind is known from DE 195 32 549 A1 and has a compensating device with a bridging portion made up of an elastomer which connects annular fastening members to one another with a certain flexibility and forms a bridge between the machine housing and the bearing casing. This elastomer bridging portion is a shaped part which has to be produced specifically for the shaft seal.
In the case of another known shaft seal assembly of the type refereed-to-above DE 44 44 719 A1, the compensation device or its bridging portion comprises a metal bellows or compensator. A device of this kind is expensive and requires large dead spaces in the region of the shaft exit from the machine housing.
A further shaft seal assembly is known (EP 0 268 730 A2) wherein a counter-ring for a sliding ring seal to which lubricant is supplied, is held by a radially inner annular collar and a radially outer holding flange. These members are provided with seat recesses for O-rings. These O-rings are fixed by an annular disk and another O-ring. The O-rings serve to seal off the lubricant supply. The sliding ring seal and the counter-ring formed by the inner annular collar rest against one another in the axial direction.
A further shaft seal assembly is known (U.S. Pat. No. 3,301,613) wherein a lubricated sliding-contact bearing uses an outer annular thrust bearing to supply lubricant, and sealing off the lubricant passage is by means of O-rings, via which bearing forces are also passed. A graphite ring is used to seal off the lubricant from conveyed material.
SUMMARY OF THE INVENTION
An object of the invention is to propose a shaft seal assembly of the type referred-to above comprising a compensation device and a bridging portion which can be constructed from inexpensive commercially available components. A further object of the invention is to largely avoid dead spaces in which material to be sealed off could collect.
With the invention, the shaft seal assembly has a compensating device and a bridging portion which seal any gap between machine housing and bearing casing yet allowing compensating movements between housing and casing.
More specifically, the bridging portion comprises two elastomer ring seals which are arranged at an axial distance from one another and allow mobility in one or the other direction by virtue of their elastic deformation and to the extent of this deformation.


REFERENCES:
patent: 3301613 (1967-01-01), DeClaire
patent: 4795128 (1989-01-01), Kransnov et al.
patent: 4971457 (1990-11-01), Carlson
patent: 5178400 (1993-01-01), Singh
patent: 5197807 (1993-03-01), Kuznar
patent: 5347801 (1994-09-01), McIlwain
patent: 5577847 (1996-11-01), Nakamura et al.
patent: 28 35 337 A1 (1978-08-01), None
patent: 44 44 719 A1 (1994-12-01), None
patent: 195 35 549 A1 (1995-09-01), None
patent: 0 268 730 A2 (1987-05-01), None

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