FIRING FRACTION MANAGEMENT IN SKIP FIRE ENGINE CONTROL

Skip fire engine control using a first order sigma delta based firing controller is described. An engine controller determines a skip fire firing fraction and (as appropriate) associated engine settings that are suitable for delivering a requested output. The operational firing fraction is selected from a set of available firing fractions. The engine controller uses a first order sigma delta based converter to direct working cycle firings in a skip fire manner that delivers the selected firing fraction. The converter includes or functions substantially equivalent to a first order sigma delta converter and may be implemented any of: algorithmically using a processor; using digital, analog or hybrid components; using a lookup table; or using other appropriate techniques. In some embodiments firing decisions are made on a working cycle by working cycle basis. The described approach may be used in gasoline engines, diesel engines, turbocharged or supercharged engines, or others.