Method and system for operating an engine having a turbocharger with at least two discrete positions and exhaust gas recirculation (EGR)

A method for controlling an engine having a variable geometry turbocharger with at least two discrete positions and exhaust gas recirculation (EGR), such method comprising:

• modulating a position of an inlet flow control device of the turbocharger between the at least two discrete positions to provide, over time, a desired average pressure at an input of the EGR to enable a desired flow of exhaust gases from the exhaust of the engine through the EGR back to the intake of the engine.

A control system for controlling an engine having a turbocharger with at least two discrete positions and exhaust gas recirculation (EGR), such system comprising:

• an engine control unit for moving an inlet control device of turbocharger between at least two discrete positions, one of such at least two discrete positions providing a desired flow of air through the turbocharger to an intake of the engine and for modulating such inlet flow control device between such at least two discrete positions over time to provide, over time, a desired pressure at an input of the EGR to enable a desired flow of exhaust gases from the exhaust of the engine through the EGR back to the intake of the engine.

A control system for controlling an engine having a turbocharger having at least two discrete positions and exhaust gas recirculation (EGR), comprising:

• an engine control unit for producing a control signal for the turbocharger having two signal components, a first signal component having a level to drive the turbocharger to the either a desirable open or closed position selectively in accordance with engine operating condition, and a second signal component modulating the first signal, with such modulation being selected to control pressure across the EGR, such modulation having a bandwidth higher than the bandwidth of the turbocharger so that while the pressure at the EGR is changed substantially instantaneously wherein boost provided by the turbocharger is substantially invariant.

An engine control unit having a program stored therein for controlling an engine having a turbocharger, such turbocharger having a compressor and a turbine, such turbine having an inlet flow control device with at least two discrete positions, one of such positions being a relatively open position and another one of the positions being a relatively closed position, such engine having exhaust gas recirculation (EGR), such program causing the position of the inlet flow control device to move between the at least two discrete positions, one of such at least two discrete positions providing a desired flow of air through the turbocharger to an intake of the engine and for modulating such inlet flow control device between such at least two discrete positions over time to provide, over time, a desired pressure at an input of the EGR to enable a desired flow of exhaust gases from the exhaust of the engine through the EGR back to the intake of the engine.

An engine control unit having a program stored therein for controlling an engine having a turbocharger with at least two discrete positions and exhaust gas recirculation (EGR), such program causing an inlet flow control device of the turbocharger to move between at least two discrete positions to provide either a relatively high or relatively low flow of air, respectively, through the turbocharger to an intake of the engine and to modulate the inlet flow control device position between the at least two discrete to provide, over time, an average pressure at an input of the EGR to provide a desired flow of exhaust gases from the exhaust of the engine through the EGR back to the intake of the engine.