Research And Realization Of Noise Reduction Of Cross-over Rearaxle During High-speed Coasting

Coasting performance has an influence on automotive dynamic and fueleconomy characteristic. Both the features of vibration and noise of vehicle during thecoasting process influence transmission system efficient and the whole car NVHperformances. As the key part that transmit the engine power in the automobile, therear axle is one of the main cause which affects vehicle NVH performances，so theresearch of noise-reduction for rear axle during the coasting process have some valuefor improvement of the whole vehicle performance. The researches fornoise-reduction of the rear axle mainly focus on controlling vibration sources andtransmission path. As one of the main excitation source, hypoid gears have a largeeffect on vibration and noise characteristics of rear axle, as a result,become the main research object for noise-reduction of rear axle.In response to the question proposed by a company that the rear axle larger noisegenerated, the hypoid gears was regarded as the research object for studying thevibration and noise、dynamic meshing characteristics of gears system. Analyzing theprimary source of gears vibration and noise and noise generating mechanism, andexploring the theory related to pressure angle and contact region distribution ofhypoid gears, which provided a theoretical foundation for the following simulationanalysis. Based on the spherical involutes formation and gear processing principle,the derivation of spherical involutes and cutter trajectory equations is accomplishedand the hypoid gears parametric solid model is built by UG. With the establishment ofthe finite model of gears the dynamic meshing characteristics which include toothcontact pattern and contact force distribution law、time domain characteristics ofangular velocity and angular acceleration of gears during the coasting process arestudied by finite software, on the basis, analyzing the influences of pressure angledistribution and axle offset distance of the pinion and ring gear on tooth contact forcedistribution and change trend、time domain characteristics of vibration acceleration inthe vertical direction. Through building the virtual model, hypoid gears dynamicproperties are researched when vehicle coast from110km/h to90km/h, a key researchis made about the influence that pressure angle distribution and axle offset distancehave on angular velocity、angular acceleration fluctuation and tooth contact force ofhypoid gears. which provides improvements related to improving vibration and noisecharacteristics of the hypoid gears.