Patent ID: 8424339

Claim:
A vapor compression system comprising: a compressor, an evaporator and a condenser connected in a closed loop; a motor connected to the compressor to power the compressor; a motor coolant system configured to cool the compressor motor; the compressor comprising: a first compressor stage and a second compressor stage, the first compressor stage providing compressed vapor to an input of the second compressor stage; the motor coolant system comprising: a first connection in fluid communication with the condenser to deliver refrigerant into a motor cavity, and a second connection with the refrigerant loop to return refrigerant to an interstage connection having an intermediate pressure, the intermediate pressure greater than an evaporator operating pressure and less than a condenser operating pressure; and a first seal located between the motor cavity and the first compressor stage, and a second seal located between the motor cavity and the second compressor stage, the first and second seal configured to maintain the refrigerant at an intermediate pressure inside the motor cavity.