Patent ID: 6513471
Filing Date: 2003-02-04
Classification: F01L

Abstract:
A camshaft for an engine having switching valve actuators for switching the valves of selected engine cylinders between normally operating and closed non-operating conditions to deactivate the selected engine cylinders, the camshaft including at least one cam for each of the intake and exhaust valves operable by the camshaft, including both conventional and deactivation cylinders;the switching valve actuators for actuating the valves of the deactivation cylinders having lash adjusters with a positive valve lash and the valve actuators for the conventional cylinders having lash adjusters without significant valve lash so that camshafts having cams providing equivalent gas flow through the conventional and deactivation cylinders and having identical intake and exhaust valve timing have greater valve overlap in the deactivation cylinders than in the conventional cylinders due to increased opening and closing ramps on the cams of the deactivation cylinders needed to minimize opening and closing loading of the cams and valve actuators; the camshaft having timing for the exhaust cams of the deactivating cylinders advanced sufficiently to substantially reduce the difference in valve overlap between the conventional and deactivation cylinders without significantly unbalancing the performance of the various cylinders.