Abstract: An electronically controlled accessory drive system for an automotive engine includes a drive pulley attached to an output shaft of the engine and a flexible drivebelt for connecting the drive pulley with driven pulleys. A tensioner maintains the drivebelt in contact with each of the drive and driven pulleys. The tensioner includes an arm which is rotatably mounted to the engine, and has a wheel for contacting the drivebelt. The wheel is urged into contact with the drivebelt by the arm, with the tensioner further including a governor for controlling rotational motion of the arm, with the arm being able to rotate freely in the direction toward the drivebelt, with the governor resisting motion of the arm in the direction in which tension in the drivebelt is decreased. Motion of the governor is controlled by an electronic controller which operates a magnetic coil disposed about a fluid passage through which a magnetorheological fluid must pass as the tensioner arm rotates.

Abstract: An accessory drive system for an automotive engine includes a drive pulley attached to an output shaft of the engine and a flexible drivebelt for connecting the drive pulley with driven pulleys. A tensioner maintains the drivebelt in contact with each of the drive and driven pulleys. The tensioner includes an arm which is rotatably mounted to the engine which has a wheel for contacting the drivebelt. Motion of the arm is controllably damped by a spool valve which controls the flow of hydraulic fluid in a hydrostatically lockable hydraulic cylinder incorporated in the tensioner.

Abstract: An accessory drive system for an automotive engine includes a drive pulley attached to an output shaft of the engine and a flexible drivebelt for connecting the drive pulley with driven pulleys. A tensioner maintains the drivebelt in contact with each of the drive and driven pulleys. The tensioner includes an arm which is rotatably mounted to the engine which has a wheel for contacting the drivebelt. The wheel is urged into contact with the drivebelt by the arm, with the tensioner further including a governor for controlling rotational motion of the arm with the arm being able to rotate freely in the direction in which tension of the drivebelt is increased, with the governor resisting motion of the arm in the direction in which tension in the drivebelt is decreased.

Abstract: An idler pulley and bearing assembly for handling the drive belt of a front end accessory drive system of an internal combustion engine includes a bearing having an outer race and an inner race with an aperture for extending therethrough, and a mounting structure for securing the outer race of the bearing such that the outer race will not rotate. A pulley mounted upon a shaft extending through the aperture in the inner bearing is attached to the inner race such that the shaft pulley and inner race rotate at the same speed. This construction greatly reduces the rotational speed of the anti-friction elements within the bearing and preserves the bearing's lubrication, so as to prolong the life of the bearing, while reducing noise generated by the bearing.