| With the booming development of the automobile industry,passenger cars are gradually popularized in People’s Daily life.After the functional realization of passenger cars,people pay more and more attention to ride comfort.Automotive air conditioning compressor is the core of automobile refrigeration system.It improves people’s ride comfort while introducing the problem of vibration and noise.How to reduce vibration and noise of automobile air conditioning compressor is a problem that cannot be ignored.Combined with the horizontal topic "Development of Vibration and Noise Reduction Technology for Automotive Air Conditioning Compressor" kinematics and dynamics analysis of the main moving parts are carried out of a certain type of fixed displacement swash plate compressor.The piston elastic-plastic is simulated and tested.The abnormal noise in the cab is tested and simulated.The improved scheme is put forward and verified by test method.The main contents of this paper are as follows:(1)The function,classification and the research status of automobile air conditioning compressor by scholars at home and abroad are introduced.Based on the research status and the research progress of the project,the vibration and noise generation mechanism and control principle of swash plate compressor are analyzed,and some improvement measures of vibration and noise reduction are put forward.(2)The kinematics and dynamics theoretical analysis of the main moving parts of a certain type of fixed displacement swash plate compressor are carried out,and the theoretical analysis results are verified by the simulation of multi-body dynamics software.Piston clearance has a great influence on the vibration and noise performance of compressor.Four groups of different piston clearances are selected to carry out simulation analysis of the main moving parts.With the generation of clearance,the impact force will be generated between the piston and the hemisphere,and between the hemisphere and the swash plate.The larger the clearance is,the greater the impact force will be,and the greater the acceleration fluctuation of the piston will be when the compressor is running.(3)The elastic-plastic analysis of compressor piston is carried out.The 3D model of piston is built in CATIA,and then it is imported into Hypermesh to be meshed.In order to save calculation time,only half-piston model needs to be meshed,because the piston is symmetrical.Finally it is imported into ABAQUS,using the linear strengthening elasticplastic constitutive model to describe the mechanical properties of piston material.The simulation results show that the root is the weak part of the piston.It is optimized by thickening the piston and adopting fillet structure at the piston root.The bearing capacity of the compressor piston is increased by 14.1%,and the effect of improvement is obvious.(4)Turn on the air conditioner in the vehicle test.When the engine speed is around 1573r/min,the interior noise suddenly increases.In order to find out the cause of the problem,LMS equipment is used to conduct the vehicle test of the compressor.The test conditions include uniform speed mode and acceleration mode.Modal analysis of the compressor-support system is carried on and six lowest order modals of compressor-support system are obtained.Test and simulation results show that there exists a resonance frequency band near 688 Hz in the compressor-support system.The frequency modulation of compressor shaft frequency to its second-order operating frequency(compressor shaft frequency 21st-order)is similar to the third-order modal frequency of compressor-support,causing resonance and excessive vibration and noise.It is transmitted to the cab through the compressor refrigeration pipeline and expansion valve,resulting in abnormal noise in the cab.(5)According to the diagnosis results of vehicle test,an improvement plan is proposed that replacing the reed drive plate with rubber drive plate and cutting the joint surface of support between the compressor and the support by 5 mm.The results of vehicle test show that the abnormal noise inside the cab disappears and the trend of noise fluctuation tends to be gentle. |
