Back to results
US 6,513,471 B1Granted
Cylinder deactivation engine with advanced exhaust cam timing and method
AssigneeGeneral Motors Corporation
InventorJames B. Hicks
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeGeneral Motors Corporation
InventorJames B. Hicks
Estimating the term…
An engine has switching valve actuators with positive valve lash for actuating or deactivating valves of deactivation cylinders and conventional valve actuators with negligible valve lash for actuating valves of conventional cylinders. Cams for the deactivation cylinders have increased opening and closing ramps relative to cams of the conventional cylinders. This can lead to poor combustion quality at idle and light loads and result in perceived engine roughness by an operator. To compensate for this, timing of exhaust cams of the deactivation cylinders is advanced relative to those of the conventional cylinders to reduce valve overlap of the deactivation cylinders to sufficiently near that of the conventional cylinders to provide stable combustion at idle in both conventional and deactivation cylinders with nearly equivalent power operation of all the cylinders.
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;
An engine having switching valve actuators with positive valve lash for actuating or deactivating valves of deactivation cylinders and conventional valve actuators with negligible valve lash for actuating valves of conventional cylinders, and cams for the deactivation cylinders having increased opening and closing ramps relative to cams of the conventional cylinders, wherein timing of exhaust cams of the deactivation cylinders relative to those of the conventional cylinders is advanced to reduce valve overlap of the deactivation cylinders to sufficiently near that of the conventional cylinders to provide stable combustion at idle in both conventional and deactivation cylinders with nearly equivalent power operation of all the cylinders.
A method of operating an engine having switching valve actuators with positive valve lash for actuating or deactivating valves of deactivation cylinders and conventional valve actuators with negligible valve lash for actuating valves of conventional cylinders, and cams for the deactivation cylinders having increased opening and closing ramps for the deactivation cylinders relative to cams of the conventional cylinders, the method comprising:
Dependencies are inferred from the claim text.