Managing engine firing patterns and pattern transitions during skip fire engine operation

摘要

Various methods and data structures for managing transition between different firing fractions during skip fire operation of an engine are described. In some embodiments, transitions are constrained to occur when firing sequence segments of a designated length are shared by the first and second firing fractions. In a separate aspect, a data structure that uses current firing fraction phase as a first index and a target firing fraction as a second index may be used to determine a phase of the target firing fraction to enter at a transition. Is some circumstances transitions between a current and target firing fraction may be conducted as a series of steps through intermediate firing fractions.

主权项

1. A method of managing a transition between a first operational firing fraction and a second operational firing fraction during operation of an engine in a skip fire operational mode, the first firing fraction having an associated first repeating firing sequence and the second firing fraction having an associated second repeating firing sequence, the method comprising:
identifying a firing sequence segment of a designated length that is shared by the first and second firing fractions, wherein the shared firing sequence segment is a set of individual working chamber firing decisions that is the same in the first and second repeating firing sequences, the first and second firing fractions being different; and transitioning from the first to the second firing fraction in conjunction with the execution of the shared firing sequence segment, whereby the firing fraction entering the shared firing sequence is the first firing fraction and the firing fraction exiting the shared sequence is the second firing fraction.