Shaft and like oil seals

Details Shaft and like oil seals Shaft and like oil seals

1987-04-20

1989-03-28

Watkins, Donald

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

277153, F16J 1532

Patent

active

048157490

DESCRIPTION:

BRIEF SUMMARY
This invention relates to shaft and like oil seals, for preventing liquid leakage between relatively rotatable members, such as a rotary shaft and its housing.
Usually the liquid to be sealed is lubricating oil, the seals therefore commonly being called "oil seals", the side of a seal to be installed facing towards the region to be sealed being called the "oil side" and the other side being called the "air side" because it is usually open to atmospheric pressure.
Shaft seals are usually mounted fluid tight fast in a shaft housing and have an inner peripheral lip to seal around a cylindrical surface of a rotary shaft. Such seals are known as "internal seals". Occasionally however shaft seals are designed to be mounted fluid tight on a rotary shaft to seal by an outer peripheral lip against a surrounding cylindrical surface of a housing and are then called "external seals". In general, the design and operating conditions of internal seals can, by simple inversion, be applied to external seals. Consequently, references in this specification to internal seals are to be treated as applicable to external seals, unless otherwise stated.
Usually the sealing lip or ring of a shaft seal is made of a resiliently deformable material, such as an oil-resistant synthetic rubber or elastomer.
During the last twenty years, "positive action" seals have been developed and these have helical ribs, or similar configurations, at the air side of the sealing or contact band of a sealing lip or ring for the purpose of returning leakage oil towards the oil side.
There have been proposals to provide ribs or other configurations at the oil side of a sealing or contact band of a sealing lip or ring but, so far as is known, these have not come into use and whether any positive action is achieved thereby has not been established.
The present invention provides a positive action oil seal which utilises relative rotation of sealed members to generate at a sealing contact band a pumping action to displace oil towards the oil side.
According to the invention, there is provided an oil seal to oppose leakage of oil from between relatively rotatable coaxial members, one of the relatively rotatable members having a sealed circular counter-surface of given diameter; the oil seal having an oil side and an air side and comprising: an elastomeric sealing member; a circular sealing contact band formed on said elastomeric sealing member and arranged to bear against the circular countersurface; said contact band being designed to diverge from the counter-surface, to define with the counter-surface an annular sealing region which enlarges in cross-sectional area toward the oil side of the seal; and a skirt provided at the oil side of said elastomeric sealing member, said skirt being constructed and arranged to have a continuous but non-constant annular clearance from said counter-surface and so as to be oscillatable by pulsations in the adjacent oil; the construction and arrangement being such that relative rotation between the counter-surface and said elastomeric sealing member produces pulsations in oil filling the annular clearance, the oil pulsations cause the contact band to osculate against the counter surface over at least part of said annular sealing region and the contact band osculations produce displacement pumping of oil from the annular sealing region toward the oil side of the seal.
The term "contact" is of course used to include nominal or effective contact, with an interposed oil film, to maintain a meniscus between the contact band and its counter-surface, as well understood in oil seal technology.
The osculation of the contact band against its counter-surface may comprise either or both deformation, of the elastomeric material of the sealing member, or oscillation of the contact band eccentrically to the counter-surface, thus varying cyclically the radial dimension of the annular sealing region to produce a pulsating pumping action towards the oil side.
The non-constant clearance of the skirt from the sealed member, usually a sealed s

REFERENCES:
patent: 4183543 (1980-01-01), Antonini
patent: 4350347 (1982-09-01), Heinrich
patent: 4441722 (1984-04-01), Pichter
patent: 4671519 (1987-06-01), Bras et al.

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