US Patent No. 9,528,446

FIRING FRACTION MANAGEMENT IN SKIP FIRE ENGINE CONTROL


Patent No. 9,528,446
Issue Date December 27, 2016
Title Firing Fraction Management In Skip Fire Engine Control
Inventorship Mohammad R. Pirjaberi, San Jose, CA (US)
Adya S. Tripathi, San Jose, CA (US)
Assignee Tula Technology, Inc., San Jose, CA (US)

Claim of US Patent No. 9,528,446

1. A skip fire engine controller for determining which working cycles to skip and which working cycles to fire during skip
fire operation of an internal combustion engine having a plurality of working chambers, the skip fire engine controller comprising:
a firing fraction determining unit arranged to determine a firing fraction suitable for delivering a desired engine output,
wherein the firing fraction determining unit is arranged and constrained to determine an operational firing fraction that
has an associated repeating firing cycle length that is assured to repeat at least a designated number of times per second
at the current engine speed; and

a firing controller arranged to direct firings in a skip fire manner that delivers the operational firing fraction, the firing
controller being arranged to make firing decisions on a firing opportunity by firing opportunity basis; and

wherein the firing controller includes an accumulator that tracks a relative portion of a firing that has been requested but
not yet directed by the firing controller, whereby the accumulator helps smooth transitions between different firing fractions.