Bearing cooling arrangement for air cycle machine

Claim 1

An air cycle machine comprising: a. an axially extending hollow shaft; b. a compressor mounted to a central portion of the shaft and having inlet means for receiving a pressurized fluid to be compressed therein; c. a turbine mounted to an first end portion of the shaft and having inlet means for receiving a pressurized fluid to be expanded therein, said turbine operatively connected to said compressor by a shaft extending therethrough whereby said compressor is driven through the shaft by said turbine; d. a fan mounted to a second end portion of the shaft; e. first hydrodynamic bearing means for supporting the shaft disposed about the shaft at a location between said compressor and said turbine; f. second hydrodynamic bearing means for supporting the shaft disposed about the shaft at a location between said compressor and said fan; and g. a bearing cooling circuit having an inlet for receiving a portion of the compressed fluid to be expanded from the inlet means of said turbine as a coolant, an outlet for discharging said coolant directly into the inlet means of said compressor means, and a coolant flowpath therebetween traversed by said coolant, the cooling flowpath having a first portion extending from the inlet to said cooling circuit through said first hydrodynamic bearing means, a second portion extending within the hollow shaft, and a third portion extending through said second hydrodynamic bearing means to the outlet of said cooling circuit, the coolant passing in series through the first portion, thence the second portion, and thence the third portion of the cooling flowpath of said cooling circuit.