Patent ID: 6810866
Filing Date: 2004-11-02
Classification: F02D,F02M,Y02T

Abstract:
An engine including cams for actuating intake and exhaust valves controlling transport of air and combustion products to and from a combustion chamber of the engine, the cams having valve opening and closing curves capable of being timed so that the intake valve opening curve partially overlaps the exhaust valve closing curve, allowing retention of some combustion products in the combustion chamber with an incoming air charge, at least one of the cams having variable timing to vary the valve overlap for controlling the amount of exhaust gas retention, wherein:overlapping portions of the cam opening and closing curves provide a relatively linear change in valve overlap area over an extended range of duration of cam variable timing and the timing of the intake valve is variable and the opening curve of the intake cam provides the extended overlap area; whereby variation of exhaust gas retention in the combustion chamber is a relatively constant function of the variation in duration of valve overlap in each engine cycle.