Noise Distribution And Reduction Of Metro Cars Air Conditioning Systems

The development of the national economy and the increased process of city gradually with the increasing number of private cars and city population bring huge pressure to city traffic. The subway with the advantages of its large capacity, punctuality rate, safety and comfort, low energy consumption and less pollution become one of the most effective ways of solve the traffic congestion problem. At the same time the radiation noise of the subway is more serious. Running at30km/h～45km/h, metro has a low travel speed, at this time in addition to noise from the power system and the wheel-rail system of metro vehicle, the noise of the air conditioner system also accounted for a large proportion in the overall noise of vehicles. Known the distribution and the spectrum characteristics of the noise and the vibration of metro vehicles air conditioning system, it can provide the basis for the study of the vibration and noise reduction of metro vehicles and improving the ride comfort.After analyzing the composition and working principle of the air conditioning unit of subway vehicle, noise that air conditioning system is generally composed of the following parts:noise of the refrigeration compressor and fan running equipment in air conditioning; air dynamic noise when air through air duct and connection hose.Test the noise of the metro cars air conditioning using noise and vibration analysis system at different speed and conditions, and conduct a spectral analysis of the noise characteristics of its air-conditioning system, and get their distribution. Noise level distribution of air-conditioning systems are mainly concentrated in the frequency range of160Hz.2000Hz,and in this range, the frequency distribution curve is relatively smooth, and it has not obvious wave crests and troughs.Air conditioning system noise has little effect on passengers standing and sitting, about1.5～2dB (A), Vehicle air conditioning noise is obvious at low speed., and the speed is lower the the impact is greater. The research results have certain reference value for metro vehicle vibration and noise reduction design.