Study On Vehicle Altornater Noise Testing And Noise Reduction Method

With the development of the society, cars have entered thousands of family and became an integral part of their daily life. People's requirements on car also ascend to a higher level from simple ride instead of walk. Vehicles riding comfort was proposed under this background. In which, the vibration and noise was one of the most important factors that affect the vehicles riding comfort.By taking a certain type vehicle alternator as the research object, this paper do some research on its noise problems using the method of combining theory, experimental and simulation.The main role of this paper included:First, Reference standards and the requirements of the automakers, a vehicle alternator special acoustic laboratory and a noise testing platform were designed and built with the help of the relevant units.Secondly, after repeated experiments and comparative analysis to the results, it was found that the noise characteristic of vehicle alternator has high stability and consistency in the same experiment scheme. But, if the experiment scheme was different, the vehicle alternator noise characteristics was possible changed. The major factors that affect are cold and hot condition and the speed change rate of the vehicle alternator.The third, according to the research results that our institute has obtained, this paper analyzed the noise problem that exited in 2000-4000r/min of type A vehicle alternator and presented improvement suggestions. Then, the improved products were tested again to make sure their noise level had reached automakers' requirements.The fourth, starting with the generation mechanism of noise, high speed electromagnetic noise at 11000r/min was mainly analyzed. Experimental comparison and theoretical analysis was used to produce the cause of the problem. Then improvement suggestions were presented and validated.Finally, Reference the "single order pseudo-rigid body model" of the engine, this paper put forward the composition formula of the vehicle alternator's ventilation noise. According to the formula, two kinds of optimization scheme were used to optimize the exhaust fan of vehicle alternators. Then, some experiments was done to check the correctly of the scheme.