Method for controlling fuel supply to an engine

Claim 1

A method for controlling fuel supplied to an internal combustion engine based upon determination of induced air mass per cylinder per cycle therethrough (IACC) without need for an air flow sensor, comprising the steps of: determining engine operating characteristics from tests conducted on a representative sample of a family of engines at ambient conditions and at selective elevated charge air temperatures (T CH ) while keeping all other conditions equal, repeating these tests at a series of engine speed and load combinations, taking measurements of charge temperature (T CM ), and developing therefrom look-up maps so that T CM and a selected load demand coefficient K LD can be looked up for any combination of engine speed and load; conducting further tests on said representative sample engine and taking measurements of at both wide open throttle (WOT) and over a range of engine speeds at ambient conditions and at induced exhaust back pressures respectively and, using these measurements and the previously developed look-up maps of T CM and K LD , developing look-up maps of cylinder displacement constant (K 1 ) and exhaust pressure coefficient (K 2 ) over said speed range; subsequent to said tests, operating engines of said family with sensors provided to obtain signals indicating respectively engine load, engine speed, charge air temperature (T CH ), ambient pressure (P AT ), and exhaust pressure (P EX ); calculating from sensor signals of T CH , P AT and P EX , and using values from look-up maps of K 1 , K 2 and T CM based on engine load and engine speed, a value for IACC WOT in accordance with the algorithm ##EQU5## wherein IACC WOT is induced air mass per cylinder per cycle at wide open throttle and D CM is a calibration coefficient previously determined experimentally; looking up a value of K LD based upon load and speed, and calculating a value of IACC LD for existing engine operating conditions according to IACC LD =IACC WOT ×K LD ; and controlling fuel supply to the engine based upon said calculated IACC LD .

Claim 2

A method for controlling fuel supplied to an internal combustion engine based upon determination of induced air mass per cylinder per cycle therethrough (IACC) without need for an air flow sensor, comprising the steps of: determining engine operating characteristics from tests conducted on a representative sample of a family of engines at ambient conditions and at selective elevated charge air temperatures (T CH ) while keeping all other conditions equal, repeating these tests at a series of engine speed and load combinations, taking measurements of charge temperature (T CM ), and developing therefrom look-up maps so that T CM and a selected load demand coefficient K LD can be looked up for any combination of engine speed and load; conducting further tests on said representative sample engine and taking measurements of at both wide open throttle (WOT) and over a range of engine speeds at ambient conditions and at induced exhaust back pressures respectively and, using these measurements and the previously developed look-up maps of T CM and K LD , developing look-up maps of cylinder displacement constant (K 1 ) and exhaust pressure coefficient (K 2 ) over said speed range; subsequent to said tests, operating engines of said family with sensors provided to obtain signals indicating respectively engine load, engine speed, charge air temperature (T CH ), ambient pressure (P AT ), and exhaust pressure (P EX ); calculating from sensor signals of T CH , P AT and P EX , and using values from look-up maps of K 1 , K 2 and T CM based on engine load and engine speed, a value for IACC WOT in accordance with the algorithm ##EQU5## wherein IACC WOT is induced air mass per cylinder per cycle at wide open throttle and D CM is a calibration coefficient previously determined experimentally; looking up a value of K LD based upon load and speed, and calculating a value of IACC LD for existing engine operating conditions according to IACC LD =IACC WOT ×K LD ; and controlling fuel supply to the engine based upon said calculated IACC LD .