Automotive accessory drive system
The apparatus of the present invention provides an improved automotive accessory drive system. The automotive accessory drive system including a drive pulley operatively connected to an engine, and a plurality of driven pulleys operatively connected to one of a plurality of driven devices. A flexible drive belt connectively couples the drive pulley and the plurality of driven pulleys, and is operable to transfer drive forces therebetween. The automotive accessory drive system also includes a flexible drive belt tensioner operable to maintain frictional engagement between the flexible drive belt and the drive pulley and at least one of the driven pulleys. The flexible drive belt tensioner has a damper element that preferably includes a damper housing, and a variable viscosity fluid disposed within the damper housing. The variable viscosity fluid is configured to provide a variable dampening rate and is selectively operable to lock the flexible drive belt tensioner.
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.
2. The automotive accessory drive system of claim 1 , wherein one of said plurality of driven pulleys is connected to a combined alternator/starter motor.
3. The automotive accessory drive system of claim 2 , wherein said variable viscosity fluid is a magneto-rheological fluid.
4. The automotive accessory drive system of claim 3 , wherein said damper element includes a piston disposed within said damper housing, said piston having a groove configured to retain said conductive coil.
5. The automotive accessory drive system of claim 4 , further comprising a controller electronically connected to said conductive coil, said controller configured to facilitate the selective transfer of electricity to the conductive coil to alter the viscosity of said magneto-rheological fluid.
6. An automotive accessory drive system comprising:
a drive pulley connected to an engine output shaft;
a plurality of driven pulleys each of which is connected to one of said plurality of driven devices, one of said plurality of driven devices being a combined alternator/starter motor;
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 variable viscosity fluid disposed within said damper housing, wherein said variable viscosity fluid is a magneto-rheological fluid;
a conductive coil disposed within said damper housing and in close proximity to said variable viscosity fluid, said conductive coil configured to produce a magnetic field adapted to selectively alter the viscosity of said variable viscosity fluid;
a piston disposed within said damper housing, said piston having a groove configured to retain said conductive coil, said piston being sized to be reciprocally movable within the damper housing and adapted to define a passage in cooperation with the piston and an inner wall of the damper housing, said passage permitting selectively controlled flow of variable viscosity fluid in a region between the piston, conductive coil and damper housing inner wall regulating dampening rate of the piston within the damper housing, wherein the dampening rate is controlled by the magnetic field selectively altering viscosity of fluid in the passage, wherein the magnetic field can be controlled to increase the viscosity of said fluid to a point where flow in the passage is no longer possible, thereby locking the damper element in position within the damper housing, locking said flexible drive belt tensioner; and
a controller electronically connected to said conductive coil, said controller configured to facilitate the selective transfer of electricity to the conductive coil to alter the viscosity of said magneto-rheological fluid;
wherein said damper element includes 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.