Patent ID: 8100116

Claim:
Method for controlling combustion in a direct-injection diesel engine including an intake valve, an exhaust valve, and a plurality of valve activation devices, and a variable volume combustion chamber defined by a piston reciprocating within a cylinder between top-dead center and bottom-dead center points, intake and exhaust passages, and intake and exhaust valves controlled during repetitive, sequential exhaust, intake, compression and expansion strokes of the piston, the method comprising: monitoring a crankshaft rotational position; monitoring an engine load; determining an intake stroke within the cylinder based upon the crankshaft rotational position; monitoring a desired exhaust residual amount based upon a calibrated effect to emissions; and only when the engine load is less than a threshold engine load defining a maximum load within a low load range, variably controlling an opening of the exhaust valve during a portion of the intake stroke to accomplish drawing exhaust gas residuals back into the cylinder to achieve the desired exhaust residual amount within the cylinder.