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US 7,036,483 B2Granted
Diesel engine with dual-lobed intake cam for compression ratio control
AssigneeGeneral Motors Corporation
InventorsSherif H. El Tahry, Roger B. Krieger
Life of this patent
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AssigneeGeneral Motors Corporation
InventorsSherif H. El Tahry, Roger B. Krieger
Estimating the term…
Dual-lobed cams mounted on the intake camshaft of a diesel engine selectively retard timing of the intake valve closure. The purpose of retarding timing of the intake valves is to retard valve closing sufficiently to shorten the effective compression strokes of the pistons and thus reduce the effective compression ratio. This occurs when the intake valves remain open past piston bottom dead center for a desired period into the normal compression stroke phase of engine operation. This reduces compression pressures so that combustion temperatures are reduced and exhaust emissions, primarily NOx, may be thus limited under conditions of warmed-up engine operation. Dual-lobed cams may also be employed to retard timing of the intake valve opening to throttle admitted air during cold running conditions to effect higher in-cylinder charge temperatures to reduce hydrocarbon and white smoke emissions due to poor ignition and incomplete combustion.
Diesel engine having cylinders and pistons defining expansible combustion chambers into which combustion supporting gas is compressed during compression strokes of the pistons for compression ignition and burning of injected fuel to drive a crankshaft, intake and exhaust valves actuated by crankshaft driven intake and exhaust camshafts for controlling the timed admission of air to and the discharge of exhaust from the combustion chambers, and for each cylinder the improvement comprising:
Method for operating a diesel engine comprising:
Diesel engine having cylinders and pistons defining expansible combustion chambers into which combustion supporting gas is compressed during compression strokes of the pistons for compression ignition and burning of injected fuel to drive a crankshaft, intake and exhaust valves actuated by crankshaft driven intake and exhaust camshafts for controlling the timed admission of air to and the discharge of exhaust from the combustion chambers, and for each cylinder the improvement comprising:
Dependencies are inferred from the claim text.