Study On Dynamic Performances Of Timing Belt Drive System

Timing belt drive system(TBDS)is one of the common transmission forms.With a more precise transmission accuracy,a more transmitted power,a more compact layout and a smaller working noise,it is widely used in precision transmission occasions.A good design of belt drive system can improve the transmission efficiency,transmission accuracy,reduce vibration and extend the service life of the belt.It is important to predict and analyze the dynamic performances of belt drive system in the design stage.At present,the researchers have done lots of work on the modeling and analysis methods of belt drive system.However,there are still some deficiencies in model of system,such as the meshed teeth region between the teeth and the pulley is simplified as rigid,the hysteretic torque and the nonlinear damping of tensioner are not considered.Thus the modeling methods of TBDS are studied,and the experiments of dynamic performances of TBDS is carried out and analyzed in this paper.The major studies can be summarized as follows:(1)The testing methods for the dynamic responses of TBDS and the performance of componnents of system are presented.One timing belt drive system of engine is taken as an example.The steady speed and acceleration tests of crankshaft are carried out.The fluctuation of crankshaft speed,the oscillation of tensioner arm,the hubload of idler and the transmission error of system are analyzed.The testing methods of the hysteretic characteristics of tensioner and the longitudinal stiffness of timing belt are given.The paramters performance for the conponnents of system are investigated,which provides the foundation for the modeling and validation of TBDS.(2)The analytical model for describing the hysteretic behavior of an automatic tenisoner is established.The structure principle of a friction type tensioner is elaborated,and the formulas of the friction torques of tensoner is deduced.The methods for calculating the hysteretic behavior of tensioner in the sticking and sliping process are presented by the Duhem model and the Bilinear model.The analytical model of tensioner is validated by the tests of reaction torque versus angular displacement of tensioner arm under a dynamic and a quasi-static excitations.The influences of excitation frequency and the excitation amplitude on the hysteretic behavior of tensioner are investigated.Then the computational accuracy and the error between two models are compared.(3)The universal vibration model and solving method of TBDS are established considering with the meshed teeth between belt and pulley,and the hysteretic torque and the nonlinear damping of tensioner.In order to estimate the nonlinear damping of tensioner under a constant and a varying excitation frequency,an iterative method and a Piecewise interpolation method are presented.The established model and the calculation method are validated by experiments.The influence of acceleration excitation of driving pulley,damping of tenisoner,and meshed teeth model on the dynamic reponses of TBDS are investigated.Then the influence of iterative parameters on iterative efficiency and iterative accuracy are investigated.(4)From the perspectives of simplifying the hysteretic model parameters and improving the computational efficiency,the bilinear hysteretic model of tensioner is equivalent to a linear stiffness and a viscous damping based on the averaging energy method.A simpilified modeling and calculation method of TBDS are proposed.The presented method is validated by the measurements,and the vibration responses are compared with results which is obtained by the previous method.The computational error between these two methods is compared and studied.The developed models and analytical procedures proposed in this paper have guiding significance for the positive development of the TBDS.And it can be extended to the modeling and analysis of the belt drive system with a hysteretic tensioner.