Patent ID: 7686718
Filing Date: 2010-03-30
Classification: F01L,F16H

Abstract:
1. A timing drive in an internal combustion engine having a crankshaft and a valve-operating camshaft, the timing drive comprising; a crankshaft sprocket on the crankshaft, a camshaft sprocket on the camshaft, and an endless chain in mesh with said sprockets for transmitting torque from the crankshaft to the camshaft, the chain having a slack side which moves from the crankshaft sprocket toward the camshaft sprocket, and a tension side which moves from the camshaft sprocket toward the crankshaft sprocket, in which the tension in said tension side varies cyclically as a result of cyclic variations in the torque in the camshaft; a tensioner; a movable guide pressed by said tensioner against said slack side of the chain; a second guide slidably engageable with the tension side of the chain and pivoted about a pivot axis for movement approximately perpendicular to the direction of travel of said tension side of the chain in a first direction to increase tension in the tension side of the chain and in a second, opposite, direction to decrease tension in the tension side of the chain; and a cam, operated by one of said camshaft and said crankshaft, the cam being engageable with the second guide and configured to move the second guide in said first direction through at least two cycles with each rotation of the crankshaft, and being synchronized with the cyclic variations in torque in the camshaft so that the speed of movement of the second guide in said first direction reaches a maximum approximately when the tension in the chain is a minimum, and the speed of movement of the second guide in the second direction reaches a maximum approximately when the tension in the chain is a minimum.