Fast torque response for boosted engines

An engine controller for controlling a boosted engine including a turbocharger having a turbine and a compressor and configured to direct operation of the engine in a cylinder output level modulation mode, the engine controller being further configured to:

• in response to a selected torque request, determine that a transition from a first engine state to a target engine state is desired, the first engine state having an associated first engine torque output, an associated first effective firing density and an associated first compressor pressure ratio, and the target engine state having an associated target engine torque output, an associated target effective firing density and an associated target compressor pressure ratio that is higher than the first compressor pressure ratio;
• in response to the determination that the transition from the first engine state to a target engine state is desired, direct the engine to transition to a second effective firing density that is higher than the first effective firing density and higher than the target effective firing density thereby increasing a flow of gases through the engine and the turbocharger;
• and
• after reaching the second effective firing density and producing the target torque at the second effective firing density, gradually reducing an operational effective firing density from the second effective firing density to the target effective firing density while increasing an operational compressor pressure ratio to the target compressor ratio.

An engine controller for controlling a boosted engine including a turbocharger having a turbine and a compressor and configured to direct operation of the engine in a cylinder output level modulation mode, the engine controller being further configured to:

• in response to a selected torque request, determine that a transition from a first engine state to a target engine state is desired, the first engine state having an associated first engine torque output, an associated first effective firing density an associated first compressor pressure ratio and a first mass airflow rate, and the target engine state having an associated target engine torque output, an associated target effective firing density, a target mass airflow rate and an associated target compressor pressure ratio that is higher than the first compressor pressure ratio;
• in response to the determination that the transition from the first engine state to a target engine state is desired, direct the engine to transition to a second engine state while maintaining the first compressor pressure ratio, the second engine state having second mass airflow rate that is higher than the first mass airflow and higher than the target effective mass airflow rate;
• and
• after reaching the second engine state and producing the target torque at the second engine state, gradually reducing an operational mass airflow rate to the target effective mass airflow rate while increasing an operational compressor pressure ratio to the target compressor ratio.

A method of managing a transition from a first engine state to a target engine state in a boosted engine configured to operate in a cylinder output level modulation mode, the boosted engine including a turbocharger having a turbine and a compressor, the first engine state having an associated first torque output, an associated first effective firing density and an associated first compressor pressure ratio, and the target engine state having an associated target torque output, an associated target effective firing density and an associated target compressor pressure ratio that is higher than the first compressor pressure ratio, the method comprising:

• in response to a request to transition to the target operating state, causing the engine to transition to a second effective firing density that is higher than the first effective firing density and higher than the target effective firing density while substantially maintaining the first compressor pressure ratio;
• after the target torque has been achieved operating at the second effective firing density and the first compressor pressure ratio, gradually reducing an operational effective firing density from the second effective firing density to the target effective firing density while gradually increasing an operational compressor pressure ratio from the first compressor pressure ratio to the target compressor pressure ratio and continuing to output substantially the target torque.