Shaft seal for low and high pressures

Claim 1

A feed assembly adapted to deliver circumferentially of a revolving shaft a pressurized fluid mass intermittently to a chamber maintained under reduced pressure relative to the entering fluid mass, said assembly comprising: A. a substantially gas tight, fluid tight, generally elongated housing, 1. said housing having defined therewithin at successive adjacent adjoining regions generally along a Common axis extending therethrough a. a first radially symmetrical sealing chamber generally coaxial with said axis, b. a second radially symmetrical sealing chamber generally coaxial with said axis, c. a fluid input chamber generally coaxial with said axis, and d. a process chamber adapted to be maintained at a predetermined relatively low pressure, 2. said housing having defined therein a. a shaft input port axially located adjacent said first sealing chamber, and b. a fluid input port circumferentially located in said input chamber adjacent said second sealing chamber, 3. said housing in the region of said sealing chambers and said housing through said fluid input port and exiting therefrom into said process chamber, B. a revolvably mounted shaft generally coaxial with said axis and extending through said shaft input port, said sealing chambers, and said input chamber, and into said process chamber, said shaft in said input chamber defining in combination with said housing an annular space circumferentially thereof adapted for the flow of fluid therethrough and into said process chamber from said fluid input port, C. a first viscoseal-type sealing screw located in said first sealing chamber and associated with either said shaft or said housing, the circumferentially extending radially projecting ribs thereof being adapted to form in cooperation with fluid from the input chamber when said input chamber has pressurized fluid flowing therethrough and when said shaft is rotating at a predetermined speed a seal between said shaft and said housing, D. a second viscoseal-type sealing screw located in said second sealing chamber and associated with either said shaft or said housing, the circumferentially extending, radially projecting ribs thereof being 1. adapted to form in cooperation with fluid from said input chamber when said shaft is rotating at a predetermined speed and when said input chamber has been first pressurized with fluid and then depressurized up to an extent that no fluid flows therethrough a seal between said shaft and said housing, and 2. adapted to permit passage of fluid through said second sealing chamber to said first sealing chamber from said input chamber when said input chamber has pressurized fluid flowing therethrough and when said shaft is rotating at a predetermined speed.