Method for operating an internal combustion engine using a corrected energizing time for fuel injections

摘要

Methods and apparatus for operating an internal combustion engine are provided. The engine has an engine block defining a cylinder accommodating a reciprocating piston coupled to rotate a crankshaft, a fuel injector for injecting fuel inside the cylinder, and a crank position sensor positioned proximal to the crankshaft. A method includes commanding the fuel injector to perform a test fuel injection with a predetermined energizing time and using the crank position sensor to determine a crankshaft acceleration signal during the test fuel injection. The crankshaft acceleration signal is filtered and a value of an amplitude of a fundamental frequency component of the filtered crankshaft acceleration signal is determined. A correction factor of the predetermined energizing time is determined based on a difference between the determined value of the amplitude and a preset value thereof. The correction factor is used to correct an energizing time of subsequent fuel injections.

主权项

1. A method for operating an internal combustion engine, the internal combustion engine comprising an engine block defining a cylinder accommodating a reciprocating piston coupled to rotate a crankshaft, a fuel injector for injecting fuel inside the cylinder, and a crank position sensor positioned proximal to the crankshaft, the method comprising the steps of:
commanding the fuel injector to perform a test fuel injection with a predetermined energizing time; using the crank position sensor to determine a crankshaft acceleration signal during the test fuel injection; filtering the crankshaft acceleration signal and obtaining a filtered crankshaft acceleration signal; determining a value of an amplitude of a fundamental frequency component of the filtered crankshaft acceleration signal and obtaining a determined value of the amplitude of the fundamental frequency component; determining a correction factor of the predetermined energizing time on a basis of a difference between the determined value of the amplitude of the fundamental frequency component and a preset value thereof; and using the correction factor to correct an energizing time of subsequent fuel injections performed by the fuel injector, wherein the filtering of the crankshaft acceleration signal comprises the steps of:
identifying a frequency (fn) of the crankshaft acceleration signal to be filtered by searching for a local maximum and a local minimum of the crankshaft acceleration signal in a predetermined time interval to determine a half period (T/2) of the crankshaft acceleration signal and consequently its frequency and assuming the frequency as a noise frequency (fn) of the crankshaft acceleration signal, andfiltering out the frequency (fn) from the crankshaft acceleration signal including:
identifying an optimal notch filter for filtering out the noise frequency (fn) from the crankshaft acceleration signal,calibrating a plurality of notch filters, each of the plurality of notch filters being suitable to filter out a different frequency centered around a typical frequency of a noise of the crankshaft acceleration signal,selecting a minimum integral value (F_int(j)) between all integral values (F_int(i)) and by choosing the notch filter that corresponds to the minimum integral value (F_int(i)), andchoosing, among the plurality of notch filters, a notch filter that minimizes a parameter proportional to an amplitude of the noise, wherein the parameter proportional to the amplitude of the noise is calculated by filtering the crankshaft acceleration signal with each of the plurality of notch filters in order to obtain an output crankshaft acceleration filtered signal (F_out(i)) for each of the plurality of notch filters, each output crankshaft acceleration filtered signal (F_out(i)) being compared to an average value of the crankshaft acceleration signal (CS_Avg) in order to calculate a deviation (F_out(i)−CS_Avg) from the average value of each output crankshaft acceleration filtered signal, and by integrating the deviation from the average value (F_out(i)−CS_Avg) of each output crankshaft acceleration filtered signal to calculate an integral value (F_int(i)) proportional to the amplitude of the noise for each output crankshaft acceleration filtered signal.