Closed loop fuel injection timing control

Claim 1

A method for controlling cylinder fuel injection timing of a fuel-injected diesel engine with a control system having an engine speed sensor, a combustion sensor, a crankshaft angle sensor and a load signal generator, the method comprising the steps of: (a) setting an actual start of combustion timing value, SOCCA, representing the crank angle corresponding to a start of combustion in a cylinder sensed by the combustion sensor; (b) determining a desired start of combustion crank angle value, DCA, derived from sensed engine speed, the engine load signal and from a stored schedule; (c) determining a delay value, ADV, representing an expected time delay between application of a start injection signal to a fuel injector of the engine and start of combustion of the injected fuel; (d) deriving a combustion timing error value, E, by subtracting SOCCA from DCA; (e) setting a current accumulated error value, A(n), equal to the sum of a predetermined accumulated error value, A(n-1), plus the combustion timing error value, E, if the magnitude of E exceeds a predetermined threshold, Et; (f) deriving an injection start timing value, SOLON, from the delay value ADV and the current accumulated error value A(n); (g) starting fuel injection when the crank angle corresponds to SOLON; (h) resetting the SOCCA value to the crank angle corresponding to the time that the combustion sensor senses combustion of the fuel injected, as a result of step (g); and (i) repeating steps (b) through (h) for each operating cycle of the cylinder.

Claim 2

A method for controlling cylinder fuel injection timing of a fuel-injected diesel engine with a control system having an engine speed sensor, a combustion sensor, a crankshaft angle sensor and a load signal generator, the method comprising the steps of: (a) setting an actual start of combustion timing value, SOCCA, representing the crank angle corresponding to a start of combustion in a cylinder sensed by the combustion sensor; (b) determining a desired start of combustion crank angle value, DCA, derived from sensed engine speed, the engine load signal and from a stored schedule; (c) determining a delay value, ADV, representing an expected time delay between application of a start injection signal to a fuel injector of the engine and start of combustion of the injected fuel; (d) deriving a combustion timing error value, E, by subtracting SOCCA from DCA; (e) setting a current accumulated error value, A(n), equal to the sum of a predetermined accumulated error value, A(n-1), plus the combustion timing error value, E, if the magnitude of E exceeds a predetermined threshold, Et; (f) deriving an injection start timing value, SOLON, from the delay value ADV and the current accumulated error value A(n); (g) starting fuel injection when the crank angle corresponds to SOLON; (h) resetting the SOCCA value to the crank angle corresponding to the time that the combustion sensor senses combustion of the fuel injected, as a result of step (g); and (i) repeating steps (b) through (h) for each operating cycle of the cylinder.