Design optimization and active control of serpentine belt drive systems with two-pulley tensioners

Severe vibration in serpentine belt drive systems, caused by dynamic excitation from the crankshaft, has several negative effects such as belt fatigue and belt slippage on pulleys. This thesis is devoted to design optimization and active vibration control of serpentine belt drive systems to reduce the undesired vibration.;Design optimization of the new two-pulley tensioner drive systems is performed with the objective of minimizing the tension variation in the belt spans of the belt drive system. The method of sequential quadratic programming is utilized to obtain the optimum tensioner pivot's damping coefficient and the optimum tensioner arm's orientation. Undesired tension variation in the belt spans of the serpentine belt drive system is reduced substantially in the optimum design.;Active vibration control of tensioner in serpentine belt drive systems with a two-pulley tensioner is also studied with the goal of minimizing tension variation in belt spans in different working conditions of the engine. Four different control schemes are developed and applied to control the tensioner arm's orientation in the system. These methods are lead-lag compensation control, linear quadratic optimal control, model matching Hinfinity control, and sliding mode control.;Vibration behavior of the belt drive system is improved significantly by application of each of the four control methods. However, the sliding mode control system demonstrates the highest level of robustness towards changes in the model and modeling errors, and is chosen as the most suitable technique for the control of the two-pulley tensioner in serpentine belt drive systems.;A recent trend in serpentine belt drive systems is to replace the single-pulley tensioner with a new two-pulley tensioner. The new design makes basis for the future developments of such systems. Dynamic analysis of serpentine belt drive systems with the new two-pulley tensioners is carried out for the first time in this thesis. A closed form analytical solution is provided when the excitation is sinusoidal. The response of the system under a general input from crankshaft is also obtained by solving equations of motion numerically, using Runge-Kutta method.