Noise Source Analysis And Evaluation Of Vehicle Air-conditioning System

With the development of vehicle technology,all tiers of suppliers have strengthened their cooperation with the original car manufacturers.Thus the difference of a vehicle's performance and safety between different car brands is becoming minor.By contrast,a vehicle's sound quality is usually seen as an essential sign to judge the quality of a car brand.Therefore,original car manufacturers have paid great emphasis to noise vibration performance,and even use it to show the character of a new vehicle model.With the improvements on main noise sources like engine and transmission,the importance of upgrading the performance of minor noise vibration sources like vehicle air-conditioning system has kept increasing.This paper aims to study the noise vibration source of the vehicle air conditioning system,which concludes a series tests and emulations on the silencer of the compressor and air conditioning pipes,also the evaluations on the compressor's sound quality before and after the improvement,both subjective and objective,aiming to create a more practical way to improve the sound quality of the vehicle air conditioning system,which better meet the user's tastes.From the study on the noise vibration of wobble-plate compressor and other air conditioning compressors,it was discovered that the noise of a compressor is usually connected to the operation of its inner components.According to frequency analysis and dynamics analysis,it was proved that the over-louder noise is produced by its inside Gleason system arc gear,and the faster is rotates,the louder noise it produces.Considering the compressor's dominant frequency range,three kinds of vehicle air conditioning pipe silencers are designed.By theoretical and emulated analysis,their different characteristics are found,also were compared afterwards.Also a psychological parameter is written down before and after the compressor improvement.And a subjective evaluation test is used to verify the results,aimed to get a final evaluation that reflects user's feelings the best.The evaluations are presented in a numeral way,which helps describe the quality of the sample voice more straightforward.