For the high working pressure, the two-stage compression method is adopted for the high working pressure. The compressor developed this time adopts the two-stage compression method of the double rotor. Since the two-stage compression is performed to reduce the pressure difference of the first and second stages, the pressure ratio is also reduced, so that the reduction in volumetric efficiency and the improvement of efficiency can be suppressed. In addition, the two-stage compression of the two rotors sets different displacements for the primary and secondary compression sections, forming a structure that compresses the refrigerant from a large displacement to a small displacement. The double-rotor mode is characterized by smooth torque variation, resulting in low vibration and low noise. Internal Intermediate Pressure Mode Volume Ratio and Internal Intermediate Pressure In order to reduce the casing design pressure, an internal intermediate pressure mode in which the primary compressed gas is discharged into the casing and the pressure in the casing is used as the intermediate pressure is employed. The volume of the gas that is compressed and discharged at the primary compression is the same as the volume of the gas that is sucked into the secondary compression. Therefore, the intermediate pressure is determined by the discharge volume ratio of the primary and secondary compression sections. The relationship between the intermediate pressure and the low pressure when the discharge volume ratio (hereinafter referred to as the volume) of the first and second compression sections is changed. The volume ratio is the ratio of the discharge volume of the secondary compression section to the discharge volume of the primary compression section, and is at the intake air temperature. 3 / hour, calculated according to the isentropic compression process. The data of this compressor is basically consistent with the calculation result, and it is confirmed that the intermediate pressure can be set by the volume ratio. According to this, by setting the intermediate pressure to be lower than the balance pressure at the time of stopping the operation, the design pressure of the casing can be reduced, and therefore, the pressure resistance design of the casing is easy. The volume ratio and the crankshaft torque are internal intermediate pressure. When setting the volume ratio, it is necessary to study the influence of the crankshaft torque variation. In the case of the rotor compressor, one of the reasons for the large vibration is the crankshaft torque variation. Reduced. Therefore, it is necessary to calculate the basic design of the closed compressor and the performance evaluation of the crankshaft torque in the relationship between the torque and the displacement volume ratio, and study the influence of the volume ratio variation. This torque is the sum of the torque formed by the compression of the gas and the torque formed by the blade force.