Variable friction secondary seal for face seals
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorEliseo DiRusso
Life of this patent
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Abstract
Vibration and stability of a primary seal ring 18 is controlled by a secondary seal system 24. An inflatable bladder 26 which forms a portion of secondary seal varies the damping applied to this seal ring. The amplitude of vibration of the primary seal ring 18 is sensed with a proximity probe 34 that is connected to a microprocessor in a control system 32. The bladder pressure is changed by the control system 32 to mitigate any sensed instability or vibration.
Claims14
In apparatus for sealing a rotatable shaft extending into a container of fluid of the type having a seat member mounted on said shaft for rotation therewith and an annular member mounted on a tubular carrier member extending around said shaft in spaced relationship thereto and mounted on said container for a reciprocating movement toward and away from said seat along the axis of rotation of said shaft with means for biasing said annular member into engagement with said seat thereby forming a primary seal, the improvement comprising
- a secondary seal in said container in frictional engagement with said carrier member to accomodate the reciprocating movement thereof while preventing leakage of the fluid therebetween, and
- means for selectively varying the friction between said secondary seal and said carrier thereby controlling the stability of said primary seal.
In combination with a radial face seal of the type wherein a seat on a rotating shaft is separated from a non-rotating annular member on a carrier reciprocably mounted in a container by a film of fluid enclosed by said container, the improvement comprising
- means for selectively limiting the amplitudes of vibrations of said annular member when said seal film becomes unstable.
A secondary seal for use in combination with a primary seal of the type having a seat and an annular plate on a carrier member mounted on a container for reciprocating movement toward and away from said seat, said secondary seal comprising,
- a sealing member in engagement with said carrier member,
- an inflatable bladder in engagement with said sealing member and said container, and
- means for selectively controlling the pressure within said bladder thereby varying the friction between the carrier member and the container.
Dependencies are inferred from the claim text.