Filed: Oct 16, 1989

Published: Mar 26, 1991

Abstract

A variable camshaft timing arrangement for an internal combustion engine in which a camshaft, for example, an intake valve operating camshaft in a dual camshaft system, is advanced or retarded in its position relative to the crankshaft and to the exhaust valve operating camshaft in reaction to torque pulsations in such intake valve operating camshaft. The other camshaft of the dual camshaft engine has a sprocket oscillatingly mounted thereon. The other camshaft also has a bracket or another sprocket keyed thereto and the bracket or another sprocket is chain driven by the rotation of the crankshaft. A pair of single acting hydraulic cylinders interconnect the oscillating sprocket and the bracket or other sprocket, with the piston ends of the cylinders pivotably attached to the oscillating sprocket and with the body ends of the cylinders pivotably attached to the other sprocket or bracket. The cylinders act in opposite directions and are hydraulically interconnected so that one extends as the other retracts and vice versa. The hydraulic system includes a control valve which is controlled by an engine controller to selectively permit one of the cylinders to extend, and the other to retract, in reaction to torque pulsations in the camshaft which is being advanced or retarded to provide desired engine operating characteristics. The bracket or other sprocket whose position is phase adjustable in this manner is connected by a chain to a sprocket which is keyed to the intake valve operating camshaft. An adaptation of the system to the synchronous phase adjustment of the positions of both camshafts of a dual camshaft engine is also specifically disclosed.

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Classification Codes

F16D3/10, F02B75/02, F16D3/02, F01L1/344