Noise Of Transmission Simulation And Optimization Research For Electric Bus

Pure electric vehicle has been spreading rapidly in the world wide with the situation of environmental protection getting more and more serious recently.Compared with traditional vehicles,electric vehicles have lower background noise,which makes the contribution of the noise of powertrain to whole vehicle noise more prominent.Consumers pay more and more attention to ride comfort when buying a vehicle,thus markets and firms put forward higher requirements for the NVH performance of powertrain for pure electric vehicle.The generation mechanism and control of the vibration and noise of transmission is studied,aiming at a domestic pure electric bus in this topic.Firstly,the generation mechanism of noise?excitation source?transfer path are analyzed and the results indicated that structural transfer is the main path.An experimental study on noise sources identification is taken based on order tracking technique.The results show that the noise of whine is caused by shifting gear.Moreover,the positions of housing vibrated seriously are selected.The multi-body dynamic model of transmission is built and is further tested by contact pattern test.Profile modification parameters are studied with orthogonal design and the influence on transmission error and tooth surface load distribution of profile crowning in tooth direction?slope modification in tooth direction?tooth profile crowning?tooth profile pressure angle is analyzed.The results showed that profile crowning in tooth direction has the most influence on transmission error and tooth profile pressure angle has the least.Finally,the best method of gear modification is given considering the accuracy of gear processing.The acoustic finite element model of transmission housing is built.The excitation load of the bearings from the dynamic model is used as the boundary condition.The forced vibration response of the housing is analyzed and the stiffness weak part is selected.The optimization scheme of housing is suggested with reference to the result of acoustic simulation.Trial production is taken according to the scheme of gear modification and housing and then the verification test of comprehensive optimization effect is conducted.The results showed that the whine noise of second gear is reduced by 3.59 dB and the whine noise of third gear is reduced by 4.63 dB.The NVH performance of powertrain is improved.Research methods of this paper have some guiding significance for improving the research on the NVH performance.