Simulation And Experimental Research On Gear Transmission Dynamics With Various Excitation Factors

This research is supported by “11thFive-Year National Key Technology R&DProgram”, named “Key technology for high-speed, heavy-duty, precision mechanicaltransmission system”(2006BAF01B07-01). The gear transmission is an extremelyimportant form of mechanical transmission, which is widely used in various fields ofmanufacturing equipment industry. Its dynamic characteristics and vibration noiselevels are important indicators for the performance evaluation, which directly impact onthe quality of related products. The gear dynamics, on the one hand, decided that theinherent characteristics of the system, on the other hand, in the complex dynamicresponse under different motivational factors. Focusing on different motivationalfactors, invesitgating relationship of dynamic excitation, system characteristics andresponse characteristics, finding out the essence of dynamics design for geartransmission system, are vital important to guide vibration and noise reduction for gearproduct development theoretically and practically. To conduct relavant research has apositive role in promoting the overall level of manufacturing equipment industry.The article emphasising on various motivating factor, applying in the actualengineering products, based on the tribological and mechanical dynamics theory and bymeans of theoretical analysis, numerical simulation, virtual prototyping andexperimental validation, carry out research for dynamic characteristics and noisereduction in the gear transmission. The research mainly include:①With consideration of gear tooth surface excitation factor, first to investigatevarying friction coefficient distribution based on the different gear friction model.Established the accurate6DOF dynamic model including effects of friction and timevarying mesh stiffness. Using Runge-Kutta method for the numerical simulation, effectof gear surface friction, under various tooth surface microscopic features, on systemdynamic excitation and transmission errror in line of action has been studied. Resultwas verified by experiment, which clearly shows the characteristics of gear dynamicsconsidering the effect from gear friction.②Focusing on the exciation from the transmission error in line of action,disscussed the “thin slice” theory to calculate transmission error (TE) which verified byfinite element method. Taking a manual transmission as research example, establishedcoupling dynamics model, found out inherent modal frequency and modal shape. Modal flexibility, as well as bearing dynamic load and acceleration response on housing, wereinvestigated under TE excitation for2ndspeed; Setting gear transmission error as target,optimized the gear profile modification by genetic algorithm method, and conductedsensitivity analysis of the the tooth profile with consideration of manufacturingtolerances. Fanally obtained a effective way to reduce noise and vibration from thetransmission error optimization.③Aiming at excitation from gear impact, studied dynamic characteristics of gearrattle formed by the gear backlash. Starting with single gear pair rattle, establishednonlinear torsional vibration dynamics model using lumped parameter method,considering the gear backlash, clutch multi-stiffness, drag torque and load fluctuations.Investigated rattle dynamic characteristics under the influence of multi-parameter, rattleintensity and rattle threshold value; Finally established a rattle simulation analysismodel for five-speed manual transmission. Evaluated the rattle intensity for all speedsand verified the result by experimental studies. This provides a useful reference forrattling control in gear tansmission.④Starting from the phase modulation of the multiple gear mesh excitation signal,the asymmetric sideband frequency characteristics and formation mechanism inplanetary gear train were investigated. Established a analysis model for modulationsideband frequency in automatic transmission with planetary gear train. Investigated theeffect of basic parameters, such as the number of teeth of the planetary gear train, themeshing phase, and meshing order on sideband frequency characteristics. Finallyobtained an universal method to estimate characteristics of sideband frequency inplanetary gear train. By carefully selecting the known parameters of planetary gear train,it is possible to reduce the asymmetric sideband frequency noise in design stage. Thecorrectness of the method was experimentally verify in the end.⑤Dynamic experimental study carried out for a manual gearbox. Test rig fortransmission error and dynamic characteristics measurement were setted up respectively.Transmission error result from simulation and test were compared to show the goodagreement. The inherent dynamic characteristics and response of the gearbox underdifferent conditions were achieved. Based on order tracking method, the maincomponents of the vibration were analyzed. Comparing the results of simulation andexperiment, as well as before and after optimization of transmission error, verified theeffectiveness to reduce the noise and vibration from the transmission error excitaion.