Internal combustion engine control for improved fuel efficiency

An internal combustion engine comprising:

• a plurality of working chambers each arranged to operate in a succession of working cycles;
• a fuel delivery system arranged to facilitate the delivery of fuel into the working chambers;
• and
• a fuel delivery control unit that includes a sigma delta control circuit, a synchronizer, and a sequencer, the fuel delivery control unit enabling a variable displacement mode in which the fuel injection system is controlled to selectively deliver fuel to the working chambers during a first selected set of active working cycles and to skip delivery of fuel to the working chambers during a second selected set of passive working cycles, wherein,
• the sigma delta control circuit receives an analog input signal indicative of a desired engine output and outputs a feedback modified digital signal representation of the analog input signal,
• the synchronizer receives the digital signal representation of the analog signal, and outputs a drive pulse signal that is synchronized with the engine speed, wherein the drive pulse signal generally indicates when active working cycles are appropriate to deliver the desired engine output,
• the sequencer receives the drive pulse signal and determines the first and second sets of working cycles on a working cycle by working cycle basis based at least in part on the received drive pulse signal, and
• the air delivered to the working chambers during the first set of active working cycles is unthrottled or at a fixed throttle position.

A method of controlling the operation of an internal combustion engine having a plurality of working chambers, each working chamber being generally arranged to operate in a succession of working cycles, the method comprising operating the engine in a variable displacement mode that includes:

• delivering air to the working chambers during the active working cycles, wherein the air delivered to the working chambers is either unthrottled or delivered at a first set air throttle position;
• delivering fuel to the working chambers in a fuel delivery pattern dynamically determined on a working cycle by working cycle basis during operation of the engine that skips delivery of fuel during selected skipped working cycles and delivers fuel during selected active working cycles;
• wherein an amount of fuel delivered to the working chambers during a first set of the active working cycles is substantially optimized for the amount of air delivered to the working chambers during the first set of the active working cycles;
• and
• wherein the fuel delivery pattern is determined at least in part using predictive adaptive control to provide a desired engine output, and wherein the predictive adaptive control includes feedback indicative of at least one of requested and actual working cycle firings.