A Study of Drying-Up Friction and Noise of Automotive Accessory Belt 2013-01-1701

Multiple-ribbed V belts have been widely used in automotive accessory drive systems to transmit power from crankshaft to power steering pump, alternator, and air conditioning (A/C) compressor. Overload under severe environmental conditions can lead to excessive slippage in the belt pulley interface in poorly designed accessory drive systems. This can lead to undesirable noise that increases warranty cost substantially. The mechanisms of this tribology phenomenon, noise features and system response are of utmost interest to the accessory drive system engineers. As accessory belt systems are usually used in ambient condition, the presence of water or moisture on belt is unavoidable under rainy or highly humid conditions. It has been found that the wet friction with negative coefficient of friction (cof)-velocity slope can lead to self-excited vibrations and squeal noise. In this study, the comprehensive drying-up process of wet belt interface is investigated by using belt-pulley interface test rig and commercially available belts. It is found that after the wet friction corresponding to negative COF-velocity slope and belt self-excited vibrations, the belt exhibits dry friction again during the drying-up process due to its continuous running. But the belt friction is different from the original dry friction. The coefficient of friction of the dried up belt is higher than that of the original belt, which is associated with higher intermittent slip noise. The investigation is expected to give some insight on how to shift the occurrence condition of the slippage and noise out of the operating angular speed range (rpm) of an engine frontend system.