Managing engine firing fraction changes during gear shifts

A method of managing a powertrain having an internal combustion engine and a transmission during transmission gear changes, the method comprising:

• while operating the engine at a first effective firing fraction with the transmission in a first gear, determining a new desired operational gear, the desired operational gear being a second gear that is different than the first gear, the first effective firing fraction being a preferred operational firing fraction for operation in the first gear based on selected current operating parameters;
• responsive to the determination of the new desired operational gear, determining a target engine speed that is suitable for use in association with the new desired operational gear;
• determining a second effective firing fraction suitable for use in association with the new desired operational gear, wherein the second effective firing fraction is suitable for providing desired engine power output based on the target engine speed;
• transitioning from the first effective firing fraction to the second effective firing fraction, the second effective firing fraction being different than the first effective firing fraction;
• adjusting an engine speed to the target engine speed;
• shifting from the first gear to the second gear, wherein the transition from the first effective firing fraction to the second effective firing fraction and the adjustment to the target engine speed are completed before the shift to the second gear is completed.

A method of managing a powertrain having an internal combustion engine and a transmission during transmission gear changes, the method comprising:

• while operating the engine at a first effective firing fraction with the transmission in a first gear, determining a new desired operational gear, the desired operational gear being a second gear that is higher than the first gear, the first effective firing fraction being a preferred operational firing fraction for operation in the first gear based on selected current operating parameters;
• responsive to the determination of the new desired operational gear, determining a target engine speed that is suitable for use in association with the new desired operational gear;
• determining an induction ratio to decelerate an engine speed to the target engine speed;
• transitioning from the first effective firing fraction to the induction ratio;
• adjusting the engine speed to the target engine speed;
• shifting from the first gear to the second gear, wherein the transition from the first effective firing fraction to the induction ratio and the adjustment to the target engine speed are completed before the shift to the second gear is completed.

A powertrain control system for controlling the operation of a powertrain having an internal combustion engine and a transmission, the powertrain control system comprising:

• a transmission control unit that controls operation of the transmission including controlling gear shifts, the transmission control unit being configured to generate a proposed gear change signal indicative of an intent to shift from a first transmission gear to a second transmission gear and to cause the shift from the first transmission gear to the second transmission gear to occur, the first transmission gear being a current operational gear;
• and
• an engine control unit that controls operation of the engine, wherein,
• (i) in response to receiving the proposed gear change signal, the engine control unit determines a target engine speed appropriate for the second transmission gear and whether a first effective firing fraction that is a current operational effective firing fraction is suitable for use in association with the second transmission gear after the proposed gear change is completed, and
• (ii) when it is determined that the current operational effective firing fraction is not suitable for use after the gear change is completed, the engine control unit directs a change to a second effective firing fraction or an induction ratio that adjusts an engine speed to the target engine speed, the second effective firing fraction or induction ratio being different than the first effective firing fraction, the engine control unit causes the change to the second effective firing fraction or induction ratio to occur before the shift to the second transmission gear is completed, and the engine control unit adjusts the engine speed to the target engine speed.