Two stage hermetic carbon dioxide compressor

A two stage hermetic compressor for compressing carbon dioxide refrigerant received therein substantially at a suction pressure and discharged therefrom substantially at a discharge pressure, comprising:

• a housing including at least two compartments, one of said compartments containing discharge pressure carbon dioxide gas and one of said compartments containing carbon dioxide gas at a pressure intermediate the suction and discharge pressures;
• a first compression mechanism located in said housing, suction pressure gas being compressed to pressure intermediate the suction and discharge pressures in said first compression mechanism;
• a motor disposed in said intermediate pressure gas compartment;
• a second compression mechanism disposed in said discharge pressure gas compartment, gas at a pressure intermediate the suction and discharge pressures being compressed to discharge pressure in said second compression mechanism;
• and
• a drive shaft operatively coupling said motor and said first and second compression mechanisms wherein said drive shaft comprises a first drive shaft and a second drive shaft, said first and second drive shafts being rotatably secured to one another, said first drive shaft operatively engaging said first compression mechanism, said second drive shaft operatively engaging said second compression mechanism.

A two stage hermetic compressor for compressing carbon dioxide refrigerant received therein comprising:

• a first module having a motor mounted therein, said first module having first and second ends;
• a second module having a compression mechanism mounted therein, said second module mounted to said first end of said first module, said motor and said second module compression mechanism operatively coupled via a drive shaft;
• and
• a third module having a compression mechanism mounted therein, said third module mounted to said second end of said first module, said motor and said third module compression mechanism operatively coupled by said drive shaft.

A method of compressing carbon dioxide refrigerant gas from a suction pressure to a discharge pressure in a two stage hermetic compressor comprising:

• drawing carbon dioxide refrigerant gas substantially at suction pressure into a first module having a compression mechanism mounted therein;
• compressing the carbon dioxide refrigerant gas to a pressure intermediate the suction and discharge pressures;
• cooling the carbon dioxide refrigerant gas at a pressure intermediate the suction and discharge pressures, collecting the intermediate pressure refrigerant gas in a second-module having a motor mounted therein;
• drawing the intermediate pressure carbon dioxide refrigerant gas from the second module into a compression mechanism mounted in a third module;
• separating oil entrained in the intermediate pressure refrigerant gas therefrom by a baffle mounted between the second and third modules;
• compressing the intermediate pressure carbon dioxide refrigerant gas to a discharge pressure and discharging the discharge pressure refrigerant gas into the third module;
• and
• discharging the high pressure carbon dioxide refrigerant to a refrigeration system.