| Scroll compressors are widely used in air conditioning,power,medical,sanitary,food and many other fields because of their unique advantages compared to conventional compressors.The crankshaft rotor system of the scroll compressor acts as a transmission component,and its smooth running directly affects the leakage of the meshing clearance of the orbiting scroll and fixed scroll,the distribution of lubricating oil,vibration and noise,and thus affects the overall performance of the compressor.The gas force is the unavoidable used load in the working process of the scroll compressor.If it is not balanced,the drive bearing,the main and auxiliary bearings,the frame force and vibration noise will be increased,which will seriously damage the stable operation of the compressor and shorten its service life,but the traditional dynamic and static balance design of the scroll compressor rotor system ignores the influence of gas force.In this paper,the effe cts of gas force and inertial unbalanced force were considered comprehensively,and the dynamic balance optimization of the traditional rotor system was carried out.The dynamic characteristics,vibration shape,natural frequency and response to the harmonic gas load of the optimal rotor system were compared with the original rotor system.Firstly,on the basis of the existing prototype,the gas force,centrifugal inertial force,friction force,overturning moment and rotation torque received by the scroll compressor rotor system were analyzed and mechanically modeled,and balance mathematical expressions of the force balance and torque were derived.Secondly,based on the dynamic and static equilibrium theory of the rotor system,considering the influence of the gas force and the inertial force,the method of balancing the gas force by installing the main counterweight and the crank pin at a certain angle was studied.Based on interaction between the gas force and the inertial force,the mass of main counterweight and the counterweight installation angle were studied for the different speed condition,and compared with the rotor system which was un-optimized under the variable speed condition.The results show that under the action of gas force,the required counterweight mass and installation angle decrease with the increase of the rotational speed,and the decelerated speed becomes slower after the rotational speed is greater than 4000r/min.Therefore,4000r/min can be taken as the variable frequency scroll compressor.The installation angle can be set from 4° to 15°.When the design speed is 6000r/min,the optimized rotor system can significantly reduce the force of the main and auxiliary bearings and the frame at the same speed and improve the stability of the rotor system.Finally,the finite element model of optimal rotor system were compared with the original finite element model.and the static response analysis of static analysis,modal analysis and prestressed modal analysis was carried out.The research shows that the deformation distribution of the rotor system before optimization does not change with the increase of the rotational speed,only the numerical value increases.The maximum deformation position of the optimized rotor system changes from the pulley to the end of the scroll wrap with the increase of the rotational speed.Under rigid support conditions,the prestress has little effect on the vibration mode and natural frequency of the rotor system.The optimized natural frequency is 10 Hz higher than original natural frequency.Under the elastic support conditions,the prestress has significant effect on the vibration mode and natural frequency of the rotor system.The optimized natural frequency is 5Hz higher than original natural frequency;Under the gas force,and the three-dimensional deformation response occurs in the frequency range of 0~3000Hz.At the 1860 Hz,the deformation response of the rotor system are the largest between the optimized rotor system and the original rotor system,but after optimization,the ratio of deformation is 71% lower than original rotor system.The optimized response frequency of the rotor system is increased from 480 Hz to 500 Hz compared with the original response frequency,which effectively widens the working speed range of the compressor and ensures its stable operation. |
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