Seal for a joint or juncture – Seal between relatively movable parts – Close proximity seal
Reexamination Certificate
1999-09-27
2001-09-18
Mah, Chuck Y. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Close proximity seal
C277S412000, C277S421000, C277S572000, C277S924000
Reexamination Certificate
active
06290234
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally concerns rotatable shaft assemblies such as gear reducers and pumps. More particularly, the invention relates to these assemblies and their sealing arrangements.
Rotatable shaft assemblies typically include a housing with at least one axial bore that extends through the housing and through which a driven or driving shaft may pass. Generally, a seal extends between the housing and the shaft to prevent passage of exterior contaminants to the housing's interior area and to prevent escape of lubricant. In this regard, a lip seal may attach to the housing and extend radially inward to abut the rotating shaft so that passage of material is prevented from either direction across the seal. Such seals are advantageous in that they may prevent escape of lubricant from the housing interior if the assembly is inadvertently shifted or tilted during shipping. The rotating shaft may, however, wear the lip seal and thereby limit its useful life.
Labyrinth seals typically have a longer life. The one or more seal elements that form the labyrinth stages do not fully contact the shaft, due to a clearance fit and/or to the passage of lubricant between the seal element(s) and the shaft. These seals may, however, permit leakage of lubricant during shipping.
SUMMARY OF THE INVENTION
The present invention recognizes and addresses disadvantages of prior art constructions and methods.
Accordingly, it is an object of the present invention to provide an improved shaft assembly.
This and other objects of the present invention are accomplished by a sealed, rotatable shaft assembly having a housing defining a bore that extends from an area exterior to the housing to an area interior to the housing. A shaft is rotatably disposed in the housing about an axis of the bore. The shaft extends through the bore between the interior area and the exterior area. An annular lip seal is disposed in the bore and is attached to one of the shaft and the housing. The lip seal extends from the one of the shaft and the housing to the other of the shaft and the housing in a contact seal so that rotation of the shaft with respect to the housing wears the lip seal to form a zero-clearance non-contacting seal. A labyrinth seal stage extends between the shaft and the housing. The labyrinth seal stage is disposed axially outward of the lip seal, with respect to the interior area, and in communication with the lip seal.
Other objects, features and aspects of the present invention are discussed in greater detail below.
REFERENCES:
patent: 3289953 (1966-12-01), Johnson et al.
patent: 3445121 (1969-05-01), Lineker
patent: 4189157 (1980-02-01), Mahan et al.
patent: 4832350 (1989-05-01), Orlowski
patent: 5387040 (1995-02-01), Firestone et al.
Eberle Frederick
Pizzichil William P.
Thompson Dennis
Farr Lloyd G.
Gerasimow Alexander M.
Mah Chuck Y.
Peavey Enoch E
Reliance Electric Technologies LLC
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