Inner wall profile of the cylinder in a rotary vane compressor (RVC), which influences the motion characteristics of vanes, suction volume, friction characteristic, etc., plays an important role in the performance of the compressor. This work mainly aims at the profile design of a new cylinder for a double-acting RVC with harmonic profile cylinder on the basis of not changing integrate size. According to the relation between cylinder profile and vane motion characteristics, a method for the cylinder profile design is proposed in this paper. With an assumed vane motion, equations of the cylinder profile, cell volume of the compressor as well as pressure angles between vanes and cylinder inner wall are constructed preliminarily. And then through adjusting parameters and optimization with an independently developed procedure, a new cylinder with the so-called combined profile is obtained. Theoretical analysis of the cell volume variations and the pressure angles between vanes and cylinder are conducted. The results show that there is neither rigid impulse nor soft impulse between vanes and cylinder due to the vane continuous motion including displacement, velocity and acceleration. And the pressure angles between vane and cylinder and working volume of the compressor with the new profile cylinder are superior to harmonic profile cylinder, which is useful for the reduction of friction power in the operation of compressor. Experiments show that the cooling capacity and COP of the test refrigeration cycle with the proposed combined profile cylinder is higher than the compressor with harmonic profile cylinder. And the volumetric efficiency and isentropic efficiency of the compressor with combined profile cylinder have better performance. This method can be applied to the design of the cylinder for multiple-acting rotary vane compressors, rotary vane expanders and vane pumps.
Multiple sets of spring, spring seat structures are uniformly arranged in circumferential short spring dual mass flywheel (DMF), which generally have a symmetrical structure. The internal springs and spring seats are constrained by the shape of the primary flywheel and the secondary flywheel. At different rotational speeds, the springs and spring seats have different centrifugal forces. To study the dynamic characteristics of the DMF including torque and stiffness with considering the influence of centrifugal force and friction, the discrete method is used to analyze the mechanical actions of the transmission parts in DMF. The torque action between the spring seat and the secondary flywheel is deduced. The dynamic characteristics of the DMF are obtained through analyzing and calculating. Due to the symmetry of the structure, the torque transmitted and the stiffness of the DMF also have specific symmetrical characteristics. Namely, at two relative rotational angles of the same magnitude and opposite direction, the magnitude of the transmitted torque is the same, the direction is opposite. The magnitude and direction of stiffness are the same. The influence of speed, friction coefficient, spring mass, and spring seat mass on the torque and stiffness characteristics are analyzed. Finally, the theoretical analysis is proved to be valid by the torque characteristics test of DMF.
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