Abstract: Forces between gears directly impact the reliability and life of internal-meshing rotary compressor, but there are few studies focusing on this aspect. After the ignorance of clearances between gears and friction forces, linear elastic theory is induced to set up a proper mathematical model to study the contact forces and contact moments between gears. The calculation of contact forces is simplified via the conjunction between the deformation magnitude and the contact force on each tooth. Additionally, the relationship among gas force, support force, driving moment and them is analyzed. A case of 1HP compressor in CO2 trans-critical refrigerating cycle is presented to solve the model. The calculating result shows the contact force is rather small compared with the gas force and the gas moment on the outer rotor is entirely balanced by the contact moment. Moreover, the driving moment of this compressor is smooth and its period is 2/Z2. The research can guide the design of this type of compressors.

Key words: Carbon dioxide, Compressor, Contact force, Refrigeration, Rotor, Trans-critical cycle