The Investigation On Dynamic Characteristics Of Oil-free Scroll Compressor With Clearance

The scroll compressor is a new type of positive displacement compressor.Because of its simple structure,low vibration and noise,and high compression efficiency,professional scholars and enthusiasts around the world have begun to pay attention to and use scroll compressors.Because the structure of a scroll compressor is quite different from that of a conventional compressor,its design and manufacturing accuracy requirements are very high.The dynamic characteristics of a scroll compressor are highly correlated with its operating conditions and are related to its fundamental characteristics.This project uses an oil-free scroll compressor with a displacement of 0.6m~3/min.The dynamic characteristics are analyzed according to its working mode.The relevant results are as follows:(1)The plane meshing theory of the vortex line is briefly introduced.According to the prototype of the scroll compressor,the circular involute curve equation is obtained.The scroll compressor is divided into working chambers according to the line parameter theory.The volume of each working chamber is changed by the numerical analysis method.When the exhaust port is opened,the volume change rate shows a steadily rising trend.(2)The work flow of the scroll compressor and the force of the scroll are analyzed,and the gas force and torque received by the moving scroll are calculated by numerical analysis.The axial force has the greatest influence on the moving scroll and the operating conditions of the whole machine,and the influence of the radial force is the smallest.The overturning torque and the rotation torque have similar trends,but from the numerical analysis,the overturning torque has a greater influence on the dynamic characteristics of the whole machine than the rotation torque,so it should be paid more attention.(3)A simple analysis of the motion law of the main shaft and the small crank is carried out.The three-dimensional simulation model of the scroll compressor is constructed by SolidWorks and Adams software.Different motion clearance and scroll clearance were set up,and all models were compared by virtual prototype simulation.The results show that:The small crank has the same motion law as the main shaft.Centrifugal inertial force is one of the key forces generated during the movement of the whole machine,and acts on the main shaft and the small crank.Reasonable control of the motion clearance of the transmission system is beneficial to the dynamic balance of the scroll compressor and makes the movement of the scroll compressor more stable.The axial clearance has a greater influence on the dynamic balance of the scroll compressor than the radial clearance.To stabilize the working conditions,the axial clearance must be properly controlled.A certain amount of motion clearance helps to control the axial clearance,but it should not be too large.(4)The effects of the centroid offset of the moving scroll on the dynamic characteristics of the scroll compressor were studied by using 3D modeling and virtual prototyping software.The models of different centroid positions were analyzed and discussed.As the centroid offset increases,the force of the transmission system increases,and the acceleration of the moving scroll tends to be stable.(5)In order to study the scroll compressor more effectively,the oil-free scroll compressor prototype was tested.The test results show that the prototype meets the design requirements and has good performance.