System and method for boosted direct injection engine

Abstract

An engine system, comprising of a combustion chamber selectively communicating with an intake manifold via at least an intake valve and an exhaust manifold via at least an exhaust valve, a turbocharger including a compressor operatively coupled to the intake manifold and a turbine operatively coupled to the exhaust manifold, wherein the turbocharger is configured to selectively boost intake manifold pressure greater than exhaust manifold pressure during at least one operating condition, a direct fuel injector configured to inject fuel directly into the combustion chamber, a spark plug configured to provide an ignition spark to the combustion chamber, a valve actuation system coupled to the intake valve and the exhaust valve configured to vary a relative timing of the intake valve and the exhaust valve and a control system communicatively coupled to the valve actuation system, the direct fuel injector, and the spark plug wherein during said at least one operating condition, the control system is configured to operate the valve actuation system to increase an overlap between exhaust valve opening and intake valve opening to increase an amount of air flowing through the combustion chamber from the intake manifold via the opened intake valve to the exhaust manifold via the opened exhaust valve, initiate an injection of fuel directly into the combustion chamber via the direct fuel injector after the exhaust valve has closed, and ignite said injected fuel by operating the spark plug to provide an ignition spark.