A supercharged engine includes an engine body, an electric supercharger, a turbocharger, an EGR passage establishing communication between an exhaust passage downstream from a turbine of the turbocharger and an intake passage upstream from a compressor of the turbocharger, a fuel supply unit configured to supply fuel into a cylinder, and a controller configured to open the EGR passage and output a control signal to the electric supercharger to increase a boost pressure of the electric supercharger during acceleration of the vehicle in which an amount of the fuel supplied by the fuel supply unit is increased in response to an acceleration request signal.

A supercharged engine includes an engine body, an electric supercharger, a turbocharger, an EGR passage establishing communication between an exhaust passage downstream from a turbine of the turbocharger and an intake passage upstream from a compressor of the turbocharger, a fuel supply unit configured to supply fuel into a cylinder, and a controller configured to open the EGR passage and output a control signal to the electric supercharger to increase a boost pressure of the electric supercharger during acceleration of the vehicle in which an amount of the fuel supplied by the fuel supply unit is increased in response to an acceleration request signal.

During execution of a purge, a purge concentration-related value is learned based on an air-fuel ratio deviation that is a deviation of an air-fuel ratio detected by an air-fuel ratio sensor from a required air-fuel ratio. In this case, the purge concentration-related value is updated using an update amount with a smaller absolute value when the purge is a second purge of supplying evaporated fuel gas to an intake pipe through a second purge passage than when the purge is a first purge of supplying the evaporated fuel gas to the intake pipe through a first purge passage.

During execution of a purge, a purge concentration-related value is learned based on an air-fuel ratio deviation that is a deviation of an air-fuel ratio detected by an air-fuel ratio sensor from a required air-fuel ratio. In this case, the purge concentration-related value is updated using an update amount with a smaller absolute value when the purge is a second purge of supplying evaporated fuel gas to an intake pipe through a second purge passage than when the purge is a first purge of supplying the evaporated fuel gas to the intake pipe through a first purge passage.

A method is provided for measuring exhaust gas recirculation (EGR) flow in. an engine system wherein turbo speed of a turbocharger, inlet pressure upstream of a compressor, boost pressure upstream of an engine, and engine intake temperature upstream of the engine are measured. Air mass flow into the engine system is calculated as a function of the turbo speed, inlet pressure, and boost pressure, exhaust mass flow is calculated as a function of the boost pressure, the engine intake temperature, volumetric efficiency of the engine, and engine size, and EGR flow is determined, by subtracting air mass flow from exhaust mass flow. A method for controlling emissions from an engine system, and an. engine system are also provided.

A method is provided for measuring exhaust gas recirculation (EGR) flow in. an engine system wherein turbo speed of a turbocharger, inlet pressure upstream of a compressor, boost pressure upstream of an engine, and engine intake temperature upstream of the engine are measured. Air mass flow into the engine system is calculated as a function of the turbo speed, inlet pressure, and boost pressure, exhaust mass flow is calculated as a function of the boost pressure, the engine intake temperature, volumetric efficiency of the engine, and engine size, and EGR flow is determined, by subtracting air mass flow from exhaust mass flow. A method for controlling emissions from an engine system, and an. engine system are also provided.

An engine control system includes: a target air mass module configured to determine a target mass of air within a cylinder of an engine based on a torque request; a boost control module configured to control boost provided by a turbocharger based on the torque request; an exhaust gas recirculation (EGR) control module configured to selectively: set a target opening of an EGR valve based on the target mass of air; set the target opening of the EGR valve to a predetermined minimum opening, where the predetermined minimum opening is greater than zero percent open; and control opening of the EGR valve based on the target opening of the EGR valve.

An engine control system includes: a target air mass module configured to determine a target mass of air within a cylinder of an engine based on a torque request; a boost control module configured to control boost provided by a turbocharger based on the torque request; an exhaust gas recirculation (EGR) control module configured to selectively: set a target opening of an EGR valve based on the target mass of air; set the target opening of the EGR valve to a predetermined minimum opening, where the predetermined minimum opening is greater than zero percent open; and control opening of the EGR valve based on the target opening of the EGR valve.

In an exemplary embodiment, an internal combustion engine, in which a valve is opened and closed when a piston reciprocates in a cylinder, has a configuration to perform repeatedly the following combined strokes: an intake stroke.fwdarw.a compression stroke.fwdarw.a combustion stroke.fwdarw.an exhaust stroke in a four-cycle internal combustion engine are combined with an intake and compression stroke.fwdarw.a combustion and exhaust stroke in a two-cycle internal combustion engine. The internal combustion engine can reduce pumping loss in a six-cycle internal combustion engine and increase the output.

Methods and systems for operating an engine with an electrically heated catalyst and an electrically driven compressor are described. In one example, the electrically driven compressor and the electrically heated catalyst are activated before an engine start so that vehicle emissions may be reduced more efficiently at engine starting and thereafter.