Patent ID: 7704056

Claim:
A two-stage vapor cycle compressor, comprising: a first stage impeller with a first stage impeller inlet receiving a refrigerant vapor for compression by the first stage impeller, the first stage impeller with a first stage impeller outlet providing a compressed refrigerant vapor; a second stage impeller with a second stage impeller inlet receiving the compressed refrigerant vapor from the first stage impeller outlet for compression by the second stage impeller, the second stage impeller further having a second stage impeller outlet; a motor having a rotor running on forward and aft foil journal bearings, the motor driving the first stage impeller and the second stage impeller; a thrust disk with a foil thrust bearing, the thrust disk attached to the rotor of the motor; and a compressor housing enclosing the first stage impeller, the second stage impeller, and the motor, the compressor housing with a compressor inlet receiving the refrigerant vapor and directing the refrigerant vapor to the first stage impeller inlet; a first cooling loop connecting a hollow interior of the rotor with an input of the second stage impeller so that a first portion of refrigerant vapor at a first stage of compression passes through the rotor to partially cool the rotor and the aft journal bearing; a second cooling loop connecting an output of the second stage impeller with the forward journal bearing so that a second portion of the refrigerant vapor passes through the forward journal bearing to partially cool the forward journal bearing; wherein the compressor housing further comprises: an inlet for liquid refrigerant, the inlet connected to a motor-stator cooling jacket, the motor-stator cooling jacket being configured to transfer heat from the stator to the liquid refrigerant and vaporize the liquid refrigerant into a third portion of cooling refrigerant vapor so that the stator is cooled; a passageway connecting the motor-stator cooling jacket with the journal bearings, the thrust bearing and the rotor so that the third portion of vaporized refrigerant combines with the first and second portions of the cooling refrigerant vapor to produce further cooling of the rotor, the journal bearings and the thrust bearing.