Theoretical Modeling And Parameters Optimization Of Low Noise Automotive Rotary Vane Electronic Vacuum Pump

Rotary vane electronic vacuum pump is the power supply device of automobile brake booster.Because of its working principle and structural characteristics,the rotary vane pump will produce greater noise when it works.For new energy vehicles,because of the absence of engine background noise,the noise of rotary vane pump has become one of the main noise sources in the vehicle.With the continuous improvement of people's living standards,higher requirements have been put forward for the comfort of the vehicle.Reducing the noise of the rotary vane pump is of great significance to improve the comfort of the vehicle and the competitiveness of the vehicle enterprises.In this paper,the noise performance of automotive rotary vane electronic vacuum pump is studied.Firstly,the position and frequency characteristics of the main noise sources of the rotary vane pump are analyzed by identifying and locating the noise sources and testing the noise.The results show that the main noise of the pump is the flow fluctuating noise of periodic exhaust,and the peak frequency of the noise is the second harmonic frequency of exhaust frequency 900 Hz.Two noise reduction methods are proposed:noise source suppression based on optimizing the size parameters of rotary vane pump and noise propagation suppression based on noise elimination and noise insulation.Firstly,in order to reduce the flow fluctuation noise of periodic exhaust,the mathematical model of the working chamber of the rotary vane pump is established,and the relevant theoretical deduction and optimization model are completed.The size of the working chamber of the rotary vane pump is optimized by using sequential quadratic programming algorithm,and the size of the exhaust outlet of the working chamber is optimized to effectively reduce the flow fluctuation of the exhaust outlet of the pump chamber.Finally,the flow fluctuation of the pump chamber is validated by Compared with the original pump,the exhaust noise of the optimized pump decreased by 3.58dB(A).Then,starting from noise propagation suppression,two schemes of sound absorption and noise insulation are proposed.Firstly,based on the frequency characteristics of the noise of the rotary vane pump,a resistant muffler for the exhaust port of the rotary vane pump is designed,and the muffler's performance is verified by the acoustic simulation software,the maximum muffler's muffling capacity is 31.83dB(A)below 5000Hz,and the muffler's muffling capacity is more than 10dB(A)between 450 and 4750Hz.Secondly,the impedance characteristics of common viscoelastic materials such as black rubber,silica gel and butyl rubber under 1000Hz were studied by impedance tube experiment.The noise elimination cover of rotary vane pump was improved by using materials with larger impedance value.The overall noise of the improved rotary vane pump was reduced by 1.98dB(A).