Patent ID: 7322895
Filing Date: 2008-01-29
Classification: F16H

Abstract:
1. An automotive accessory drive system comprising: a drive pulley connected to an engine output shaft; a plurality of driven pulleys each of which is operatively connected to one of a plurality of driven devices; a flexible drive belt connectively coupling said drive pulley and said plurality of driven pulleys and operable to transfer drive forces between said drive pulley and said plurality of driven pulleys; and a flexible drive belt tensioner operable to maintain frictional engagement between said flexible drive belt and said drive pulley and at least one of said plurality of driven pulleys, said flexible drive belt tensioner having a damper element including: a damper housing; a compressed gas charge sealed within an end portion of said damper housing, said charge being sufficient to expand and occupy space left vacant in the damper housing to improve dampening characteristics; a variable viscosity fluid disposed within said damper housing, said variable viscosity fluid being configured to provide a variable dampening rate and being selectively operable to lock said flexible drive belt tensioner; and a conductive coil configured to produce a magnetic field adapted to selectively alter the viscosity of said variable viscosity fluid.