Research On The Design And Dynamic Characteristics Of External Driven Sliding Vane Compressor

The sliding vane compressor is a key component of air conditioning and refrigeration systems.It compresses and transfers the refrigerant vapor in the refrigeration system to ensure the normal operation of the refrigeration cycle.An excellent sliding vane compressor should have the characteristics of low friction,high gas displacement,and high efficiency.The performance of the compressor determines the performance of the air conditioning and refrigeration system to a certain extent.Therefore,the improved design of the sliding vane compressor and the research of its dynamic characteristics have always been important research topics.At the same time,the sliding vane,as a thin-walled component in the sliding vane compressor,is easily damaged under high speed and high load conditions.The friction loss of the sliding vane determines the working efficiency and service life of the compressor to a certain extent.Aiming at the existing problems of vane compressors,this paper proposes an externally driven vane compressor,and studies the dynamic characteristics of the compressor.This new type of compressor has the innovative points of reducing the friction of the sliding vane.It can withstand large gas pressure and working speed and is suitable for occasions with large eccentricity.The external drive device is easy to realize the operation of multiple compressors according to a given phase difference to increase the gas displacement.The main research work of the thesis is as follows:The transmission scheme of the externally driven sliding vane compressor is designed.A pair of circular gears and non-circular gears are used to drive the rotor and the cylinder,which can effectively eliminate the influence of the cylinder’s moment of inertia.Then the suction,compression,and discharge processes of the compressor are analyzed,and the change law of the volume and pressure of the working cavity under ideal working conditions is obtained.Finally,the pitch curve and tooth profile of the non-circular gear are designed.The radial range of the non-circular gear changes only by 13%,ensuring that the mechanical efficiency of the non-circular gear transmission can be close to the mechanical efficiency of the circular gear transmission.This can lay the foundation for the compressor dynamics analysis.Based on the dynamic analysis of the sliding vane,rotor and cylinder,the friction area of the externally driven sliding vane compressor including the sliding vane side,the sliding bearing,the top of the sliding vane,the friction loss between the rotor and the cylinder end surface is analyzed and calculated,and the main friction area is found at the sliding vane side and the sliding bearing,the average friction loss in one working cycle is 23.6 W and 27.4 W,respectively.At the same time,the power and mechanical efficiency of the whole machine are calculated.The adiabatic compression power is 1283.1 W,and it has an ideal mechanical efficiency of 88.3%,which verifies the feasibility of the design of the transmission scheme.Comparing the externally driven sliding vane compressor with the rotary vane compressor,it can be found from the comparison of friction and mechanical efficiency that although the mechanical efficiency of the externally driven sliding vane compressor is reduced by 5.1%,the friction loss on the sliding vane side is a reduction of 51%.By studying the friction loss of the sliding vanes of the two compressors,an optimized design plan was further proposed.The use of elastic couplings to transmit the power of the non-circular gear to the cylinder can further reduce the friction loss on the sliding vane side to 2.2 W.Based on ADAMS,a dynamic simulation model of the externally driven sliding vane compressor was established,and the gas load during the compressor’s working process was added to the simulation model.The displacement,speed,acceleration,contact force and other parameters of the key components of the compressor are simulated,and the maximum angular velocity of the non-circular gear is 346 rad/s,which is close to the theoretical analysis of 338rad/s,which verifies the rationality of the simulation model.At the same time,it is found that the vibration generated by the whole machine system is mainly caused by the impact of noncircular gear meshing.Through modal analysis,the natural frequencies and vibration modes of non-circular gears and cylinders are obtained.The first-order natural frequency of non-circular gears is 10108 Hz,which is far away from the compressor operating frequency 48 Hz;the first-order natural frequency of cylinder is 2381 Hz,which is far away from the cylinder excitation frequency range 42 ～ 54 Hz,effectively preventing system resonance.The simulation results of the cylinder in the free mode are verified through experiments.The maximum error between the experiment and simulation is within 8%,which effectively verifies the accuracy of the finite element model,and optimizes the design of the structure of the non-circular gear and the cylinder.The tooth width and inner hole radius of the non-circular gear can increase the natural frequency of the non-circular gear;reducing the cylinder radius and the axial length of the cavity can increase the natural frequency of the cylinder.