| The scroll compressor has been widely used in the air conditioning system of electric vehicles due to its continuous compression process,small size and compact structure.The rotational speed of the scroll compressor is a key factor affecting the cooling capacity of the air conditioning system.At present,the rotational speed of the mainstream scroll compressors in the domestic and foreign markets is in the range of 6000 rpm to 7200 rpm,and the scroll compressors with the high speed of 10000 rpm or more are less.Therefore,Guizhou Quantum Power Technology Co.,Ltd.and Guizhou University have developed a scroll compressor with 36cc displacement(speed 12000rpm,cooling capacity 8Kw).Due to the increase in the rotational speed of the scroll compressor,the balance requirements of the rotor system of the scroll compressor are improved.Therefore,it is urgent to explore the analysis of the balance and dynamic characteristics of the scroll compressor rotor system.Therefore,this thesis mainly focuses on the 36cc displacement scroll compressor,focusing on the establishment of the rotor system balance calculation system,analyzing the dynamic characteristics of the rotor system,and providing theoretical guidance for the study of the rotor dynamic balance of the scroll compressor.The specific work is as follows:1.Based on the working principle and structural characteristics of the scroll compressor,the equivalent mechanical model of the scroll compressor rotor is considered without considering the gas force.Analyze the mechanical model and balance the design of the rotor’s key components.According to the rotor dynamics and finite element theory,the rotor model is simplified reasonably,and the rotor finite element analysis model and dynamics calculation model are obtained.2.The modal calculation and rotor dynamics analysis of the rotor simplified model are carried out,and the first six natural frequencies,mode shapes and critical speeds of the rotor are extracted.When the bearing stiffness is 1.0×10~6 N/m,the rotor has two temporary speed points of 176.23 rpm and 11712 rpm.In order to avoid resonance,the influence of bearing stiffness of 1.0×10~6~1.0×10~9N/m on the critical speed of the rotor is further studied.On this basis,the bearing stiffness range of 1.0×10~6~1.0×10~7N/m is optimized.The critical bearing stiffness value for avoiding rotor resonance is 4.6765×10~6 N/m.3.Based on the modal analysis,the rotor unbalance response analysis is carried out,the steady-state unbalance response characteristics of rotors and the transient unbalance response characteristics at variable speed with unbalanced masses of 0.0068kg,0.017kg,0.0425kg,0.106kg and 0.265kg were studied.The research shows that with the increase of unbalanced mass,the magnitude of the steady-state unbalanced response and the deformation of the transient unbalance response also increase,so the reasonable control of the rotor imbalance mass in actual production can effectively reduce or suppress the vibration of the scroll compressor rotor.4.The production and testing of the scroll compressor after dynamic balancing was carried out.Due to the limited test conditions,the free modal simulation of the rotor without the scroll assembly is compared with the experimental results.The error of the two results is about 5%.It is verified that the modal analysis and the unbalanced response analysis model are simplified and reasonable,and the simulation results are accurate and reliable.Through the performance test of the whole machine,it is verified that the rotor dynamic balance design of the scroll compressor is reasonable and the rotor speed has a significant influence on the working performance of the scroll compressor. |
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