| Serpentine Belt Accessory Drive Systems (SBADS) are widely used in the automotive industry, escalators and paper tape since 1970s. They provide an efficient means of transmitting power to all accessories by a single multi-ribbed belt. The advantages of SBADS include simple structure, convenient maintenance, compact mounting space, the capability of automatic tension loss compensation, and so on.However, SBADS exhibit complex dynamic characteristics, including rotational vibrations of pulleys and tensioner, and transverse vibrations in the various belt spans. Therefore, it is of great interest to find an effective approach for modeling and predicting the dynamic response of SBADS.The main contents of the dissertation are summarized as follows.Firstly, the dynamic characteristics of tensioner and SBADS are investigated experimentally. The experimented procedures to test the quasi-static and dynamic characteristics of tensioner are proposed. The relation between the tensioner preload, excitation amplitude, excitation frequency and the dynamic stiffness, damping of tensioner are discussed. The effects on the vibration and belt slipping of the driving pulley speed and accessory loads are investigated experimentally.Secondly, a modeling method and simulating technologies of the dynamic characteristics for SBADS are presented. A rotational motion model for SBADS is established. In the model, belt damping is incorporated and the effects on belt tensions due to belt"creep"on the contact arc with pulley are considered. Taking a SBADS as a studying example, the dynamic characteristics are calculated and compared with experiment. The numerical simulations for a SBADS are performed to study the effects of the driving pulley speed, belt damping and tensioner preload on the slip factor. It helps effectively control belt slipping to adjust the preload and installed position of the tensioner.Thirdly, using the rotational-transverse coupling model for SBADS incorporating belt bending stiffness, the effects on equilibrium deflection in belt spans of the parameters of tensioner are investigated. An optimization method to minimizing the transverse deflections of the belt span and maximizing the tensioner effectiveness is presented for the tensioner. The calculated results show that the optimized tensioner suppresses effectively the transverse deflections of belt spans.Finally, a method of linearizing the non-linear equations for SBADS is proposed. The effects of belt damping and parameters of the tensioner on the natural frequencies of SBADS are investigated. The sensitivity analysis is carried out to study the natural frequencies'sensitivities to the parameters of the tensioner. Then, the first order natural frequency is adjusted through changing the tensioner parameter which the first order natural frequency of SBADS is most sensitive to. |
