Cryogenic ferrofluid sealed rotary union
AssigneeVarian Semiconductor Equipment Associates, Inc.
InventorsRobert Mitchell, Roger B. Fish, Shardul S. Patel
Life of this patent
Estimating the term…
Abstract
A rotary union that includes a heated ferrofluid seal is disclosed. The rotary union includes an inner rotating shaft, an intermediate rotating shaft and an outer rotating shaft. The inner rotating shaft is hollow to allow the flow of cryogenic fluid in one direction. The inner rotating shaft and the intermediate shaft are spaced apart to create a channel for the return of the cryogenic fluid. The intermediate rotating shaft is separated from the outer rotating shaft by a gap so as to reduce thermal conductivity. In this way, the temperature of the outer rotating shaft is greater than the temperature of the cryogenic fluid. A heated ferrofluid seal is disposed between the outer rotating shaft and the housing.
Claims18
A rotary union for carrying a cryogenic fluid, comprising:
- a hollow inner rotating shaft;
- an intermediate rotating shaft surrounding the hollow inner rotating shaft, where a channel is created in a space between the hollow inner rotating shaft and the intermediate rotating shaft;
- an outer rotating shaft surrounding the intermediate rotating shaft, and separated from the intermediate rotating shaft by a gap;
- a housing surrounding the outer rotating shaft;
- a ferrofluid seal disposed between the outer rotating shaft and the housing;
- and
- a heater proximate the housing to warm the ferrofluid seal;
- wherein the hollow inner rotating shaft, the intermediate rotating shaft and the outer rotating shaft rotate about a common axis.
A workpiece processing system, comprising:
- a process chamber, maintained at near vacuum conditions;
- a rotating platen within the process chamber, on which a workpiece is disposed;
- a rotating shaft assembly having an upper hollow inner shaft and return path for cryogenic fluid, wherein the upper hollow inner shaft and the return path are in communication with a conduit in the rotating platen;
- an isolation box having an inlet and an outlet and maintained at near vacuum conditions;
- a rotary union disposed within the isolation box, the rotary union comprising:
- a lower hollow inner shaft to deliver cryogenic fluid to the rotating platen;
- and
- a lower intermediate shaft spaced apart from the lower hollow inner shaft defining a channel therebetween that is in communication with the return path;
- a base disposed in the isolation box, having an inlet conduit in communication with the inlet and the lower hollow inner shaft, and an outlet conduit in communication with the outlet and the channel, wherein the lower hollow inner shaft and the lower intermediate shaft rotate with respect to the base;
- and
- a heated ferrofluid seal to isolate the outlet conduit from the near vacuum conditions within the isolation box.
A rotary union for carrying a cryogenic fluid, comprising:
- a hollow inner rotating shaft;
- an intermediate rotating shaft surrounding the hollow inner rotating shaft, where a channel is created in a space between the hollow inner rotating shaft and the intermediate rotating shaft, where the channel terminates in a cavity;
- an outer rotating shaft surrounding the intermediate rotating shaft, and separated from the intermediate rotating shaft by a gap;
- a static seal to hermetically seal the gap from the cavity;
- a housing surrounding the outer rotating shaft;
- a ferrofluid seal disposed between the outer rotating shaft and the housing to seal the cavity;
- a heater proximate the housing to warm the ferrofluid seal;
- a base, having an inlet conduit in communication with the hollow inner rotating shaft, and an outlet conduit in communication with the cavity;
- and
- wherein the hollow inner rotating shaft, the intermediate rotating shaft and the outer rotating shaft rotate with respect to the base.
Dependencies are inferred from the claim text.