Research And Control On Interior Noise Of Soft-sleeper EMU

China is the only country in the world that has EMUs of 350km/h speed with soft-sleeper.Due to the operation in a long distance at night,as well as the complicated railway line conditions,higher requirements for vehicle interior noise are put forward in order to provide passengers with a more comfortable nighttime sleeping environment.The high-grade soft sleeper EMU has a small compartment structure,which is not conducive to the propagation of local noise.It is much more difficult to control the noise in the compartment above the local sound source than in the seat carriages.More stringent noise control requirements and the layout of the car that is not conducive to noise control pose a great challenge to the design of the noise reduction for high-grade soft sleeper EMU.Aiming at solving the above problems,this paper firstly studies the structural difference between the high-grade soft sleeper car and the seat car.Though the noise simulation analysis,the differences of the interior noise distribution between the two kinds of cars when the local sound source under the car is opened are discussed.The results show that,due to the sealing effects of the small compartment,the local sound sources have a significant effect on the noise in the corresponding upper compartment of the sleeper car.Compared with the seat carriage,the noise is higher in the compartments above the sound sources of the soft sleeper car while lower in the other areas.In order to further improve the interior noise comfort of the high-grade soft sleeper EMU,the static and railway line operation tests of the existing high-grade EMU are carried out.The static test mainly measures the interior noise under the condition of opening the equipment separately or in combination while the railway line operation test mainly measures the interior noise under changing working conditions,for example,when the train passes the neutral zone,in and out the tunnels,small curves or when the equipment starts and stops.Test results show that the overall noise level of the upscale sleeper EMU is better than that of the existing seat EMU.In the relatively quiet environment,when the train passes the neutral zone,the noise change caused by the equipment starting and stop,the single frequency noise and the air supply noise when the equipment is working produce a certain degree of discomfort to the passengers.In accordance with the simulation results of simulating local sound sources,the noise of each device mainly affects the adjacent compartment.In addition,the noise at the end of the passenger room is greatly affected by the noise of the vestibule,and the noise of the end part of the passenger room is 3 dB(A)difference between the opening and closing state of the inner end door,while the noise of the vestibule is mainly derived from the junction of the car and the door of the car.In view of the problems found in the experimental study,the corresponding noise reduction scheme is put forward in this paper,and the ground test is carried out for verification.Compared with the original structure,the noise of the sound source is significantly reduced,the sound insulation performance of the structure is improved obviously.The implementation of these control measures will help to further reduce the interior noise of the high-grade soft sleeper EMU and improve ride comfort.