Patent ID: 7344139

Claim:
A hydraulic shaft sealing arrangement for high-temperature applications between concentric high pressure and low pressure shafts of a gas turbine engine, to seal a high-pressure shaft bearing chamber located in a low-pressure zone against a high-pressure zone, comprising: an essentially U-shaped annulus arranged circumferentially on an inner circumference of the high-pressure shaft and containing a continuously exchanged sealing medium held within it by centrifugal forces, the annulus having, on an upstream side, a first annular disk extending radially inward to hold the sealing medium in the annulus, an annular sealing fin protruding into the sealing medium, and an annular heat protection ring positioned in the high pressure zone a certain distance upstream from the annulus, the heat protection ring extending radially inward toward the low-pressure shaft beyond a radially inner level of the centrifugally held sealing medium and ending immediately adjacent the low pressure shaft to create a minimal circumferential gap between the heat protection ring and the low-pressure shaft, the heat protection ring thereby acting as a heat shield between the high pressure gas and the annulus and also thereby forming a thermally insulating air chamber between the heat protection ring and the annulus, the air chamber being axially disposed between an axially outer surface of the first annular disk and an axially inner surface of the heat protection ring, the air chamber also extending radially outward beyond the sealing medium in the U-shaped annulus such that the entire radial depth of the sealing medium in the U-shaped annulus is protected from the high pressure zone by the thermally insulating air chamber.