Radial lip seal having protected porous dust excluder

Details Radial lip seal having protected porous dust excluder Radial lip seal having protected porous dust excluder

1999-05-21

2001-07-10

Knight, Anthony (Department: 3626)

Seal for a joint or juncture

Process of dynamic sealing

Peripheral radially sealing flexible projection

C277S349000, C277S551000, C277S562000, C277S566000, C277S918000

Reexamination Certificate

active

06257587

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to shaft seals and more particularly to such seals having debris-excluding features.
2. Related Prior Art
Dynamic shaft seals are used in many automotive, machine, heavy equipment, construction, agricultural, industrial applications, etc., for sealing the opening in a case or housing through which a rotating shaft extends. The seal functions to contain a lubricant such as oil on one side of the seal and to exclude contaminants on the opposite atmosphere or air side of the seal.
Numerous prior seals are known wherein a primary lubricant-retention lip is used in combination with a plurality of debris-excluding features which may take the form of shaft-engaging lips, elastomeric excluders, labyrinth passages, and porous filter elements. The present invention provides a particular combination and arrangement of dust excluding features that cooperate with one another to protect the primary lubricant-retention seal from contaminants while permitting each feature to perform its debris-excluding task in an efficient manner.
SUMMARY OF THE INVENTION AND ADVANTAGES
The present invention is directed particularly to a dynamic shaft seal assembly particularly suitable for operation in severe debris-laden operating environments. The assembly comprises an outer annular carrier member, an inner member, a primary lubricant-retention seal fixed to the carrier, and a plurality of debris-excluding features, including a first debris-exclusion seal fixed to the carrier, a second debris-exclusion seal fixed on either the carrier or the inner member and sealingly engaging the other member in spaced relation to the first debris-exclusion seal defining a sealed space therebetween, and a porous filter disposed in the sealed space.
The various dust-exclusion features are arranged and cooperate in a way that allows each to perform efficiently to exclude debris from reaching the lubricant-retention seal. The second debris-retention seal is provided upstream of the debris path from the porous filter and operates to exclude the bulk of any debris from entering the seal assembly. The porous filter, then, operates in a cleaner environment and is more efficient at entrapping and filtering out any contaminants that do pass the second debris-exclusion lip over a prolonged period to protect to the first debris-exclusion seal from such contaminants. While little debris is expected to reach the first debris-exclusion seal, that which may is more readily excluded by the first debris-exclusion seal from reaching the primary lubricant retention lip.
This multi-stage debris-exclusion sealing approach has further advantages in that it enables the primary oil-retention seal as well as the first debris-exclusion seal to be fabricated of low friction PTFE material if preferred for improved seal performance and longer seal life.


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