Coordination of vehicle actuators during firing fraction transitions

A method of controlling an engine to deliver a requested engine output, the method comprising:

• while the engine is operating at a first firing fraction having an associated first cam phase, determining a desired second firing fraction and an associated second cam phase, the second cam phase being different than the first cam phase;
• initiating a transition from the first cam phase to the second cam phase;
• after an actual cam phase is at or within a predetermined range of the second cam phase transitioning to the second firing fraction, wherein transition to the second firing fraction is initiated only after the actual cam phase is at or within the predetermined range of the second cam phase;
• and
• directing operation of the engine during the transitions to deliver the requested engine output, whereby an actual commanded firing fraction gradually changes over the course of the transition from the first firing fraction to the second firing fraction.

An engine controller arranged to direct skip fire operation of an engine, the engine controller being configured to:

• (a) direct operation of the engine at a first firing fraction and a first cam phase;
• (b) while the engine is operating at the first firing fraction and the first cam phase, determine a requested firing fraction that is different than the first firing fraction, the requested firing fraction being a second firing fraction having an associated second cam phase, the second cam phase being different than the first cam phase;
• (c) select an intermediate firing fraction that is between the first and second firing fractions, the intermediate firing fraction having an associated intermediate cam phase;
• (d) identify the selected intermediate firing fraction as a target firing fraction and the intermediate cam phase as a target cam phase;
• (e) initiate a transition from the first cam phase to one of the second cam phase or the target cam phase;
• (f) after an actual cam phase is at or within a predetermined range of the target cam phase transition to the target firing fraction;
• (g) when the target firing fraction is not the second firing fraction, select a next firing fraction having an associated next cam phase and set the target firing fraction to be the next firing fraction and set the target cam phase to be the next cam phase and cause the cam phase to transition towards the next cam phase or the second cam phase;
• and
• (h) iteratively repeat (f) and (g) until the second cam phase and second firing fraction are reached;
• and
• (i) direct operation of the engine during the transitions to deliver the requested engine output, whereby an actual commanded firing fraction changes over the course of the transition.

An engine controller arranged to direct skip fire operation of an engine, the engine controller being configured to:

• direct operation of the engine at a first firing fraction and a first cam phase;
• while the engine is operating at the first firing fraction and the first cam phase, determine a desired second firing fraction and an associated second cam phase, the second cam phase being different than the first cam phase;
• initiate a transition from the first cam phase to the second cam phase;
• after an actual cam phase is at or within a predetermined range of the second cam phase direct a transition to the second firing fraction, wherein the transition to the second firing fraction is initiated only after the actual cam phase is at or within the predetermined range of the second cam phase;
• and
• direct operation of the engine during the cam phase and firing fraction transitions to deliver the requested engine output, whereby an actual commanded firing fraction changes over the course of the transition from the first firing fraction to the second firing fraction.