초록 ▼

This invention determines the output timing of the injection command signal to each of the injectors so that the fuel injection timing agrees with the basic target injection timing even when there are variations in the fuel injection timing among the injectors, and thereby improves the exhaust emiss

This invention determines the output timing of the injection command signal to each of the injectors so that the fuel injection timing agrees with the basic target injection timing even when there are variations in the fuel injection timing among the injectors, and thereby improves the exhaust emission performance of the engine. The time T.sub.2 of an intersection between the straight line Lp representing an average Pa of the common rail pressure before it starts to fall and the first-degree approximation straight line Ld having a maximum inclination of fall of the common rail pressure is determined as the timing at which the common rail pressure starts to fall. Based on the time T.sub.2 and the average pressure Pa, the delay time .DELTA.Td which elapses from the output timing T.sub.0 of the injection command signal to each of the injectors to the actual fuel injection timing T.sub.1 is calculated. The output timing T.sub.0 for the injection command signal is determined as an instant the delay time .DELTA.Td before the basic target injection timing Tb, which is determined from the operating state.

대표청구항 ▼

[ What is claimed is:] [1.] A fuel injection method for engines comprising the steps of:storing fuel delivered by a fuel pump in a common rail;injecting the fuel from the common rail into combustion chambers through nozzle holes formed in injectors driven by an injection command signal;selecting a b

[ What is claimed is:] [1.] A fuel injection method for engines comprising the steps of:storing fuel delivered by a fuel pump in a common rail;injecting the fuel from the common rail into combustion chambers through nozzle holes formed in injectors driven by an injection command signal;selecting a basic target injection timing corresponding to a present engine operating state from among predetermined basic target injection timing data as related to engine operating states;determining, by using a predetermined function having as variables at least a timing after the start of fuel injection at which the common rail pressure starts to fall, an injection delay time that elapses from an output timing of the injection command signal to a fuel injection timing at which the fuel injection from each of the injectors is started; anddetermining the output timing of the injection command signal from the basic target injection timing and the injection delay time;wherein, using a graph with time and the common rail pressure as coordinate axes, the timing at which the common rail pressure starts to fall due to fuel injection is determined as a time coordinate of an intersection between a straight line approximating a common rail pressure falling curve before reaching a first minimal value and a straight line approximating the common rail pressure before the start of fuel injection.