METHOD FOR OPERATING AN INTERNAL COMBUSTION ENGINE

• US 20130144508A1
• Filed: 10/22/2012
• Published: 06/06/2013
• Est. Priority Date: 10/20/2011
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: DENTICI, Ignazio, BASTIANELLI, Michele
• Granted Patent: US 9,404,436 B2
• Time in Patent Office: Days
• US Class Current: 701/103
• CPC Class Codes: F02D 2041/1432 the system including a filter, e.g. a low pass or high pass filter
• CPC Class Codes: F02D 2041/286 comprising means for signal processing
• CPC Class Codes: F02D 2041/288 for performing a transformation into the frequency domain, e.g. Fourier transformation
• CPC Class Codes: F02D 41/0097 using means for generating speed signals
• CPC Class Codes: F02D 45/00 Electrical control not provided for in groups F02D41/00 - F02D43/00

Abstract

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.

Claims

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 (f_n) of the crankshaft acceleration signal to be filtered, and

filtering out the frequency (f_n) from the crankshaft acceleration signal.

2. The method according to claim 1, wherein the step of identifying the frequency (f_n) of the crankshaft acceleration signal comprises 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 (f_n) of the crankshaft acceleration signal.

3. The method according to claim 2, wherein the step of filtering out the noise frequency (f_n) from the crankshaft acceleration signal comprises using a notch filter calibrated on the noise frequency (f_n) of the crankshaft acceleration signal.

4. The method according to claim 2, wherein the step of filtering out comprises identifying an optimal notch filter for filtering out the noise frequency (f_n) from the crankshaft acceleration signal.

5. The method according to claim 4, wherein the step of identifying the optimal notch filter comprises 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 and choosing, among the plurality of notch filters, a notch filter that minimizes a parameter proportional to an amplitude of the noise.

6. The method according to claim 5, 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.

7. The method according to claim 6, wherein the step of choosing the notch filter is performed by 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(j)).

8. An apparatus 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 apparatus comprising:

means for commanding the fuel injector to perform a test fuel injection with a predetermined energizing time;

means for using the crank position sensor to determine a crankshaft acceleration signal during the test fuel injection and obtain a determined crankshaft acceleration signal;

means for filtering the determined crankshaft acceleration signal and obtaining a filtered crankshaft acceleration signal;

means for determining a value of an amplitude of a fundamental frequency component of the filtered crankshaft acceleration signal;

means for determining a correction factor of the predetermined energizing time on a basis of a difference between the value of the amplitude of the fundamental frequency component and a preset value thereof, and

means for using the correction factor to correct an energizing time of subsequent fuel injections performed by the fuel injector,

wherein the means for filtering the determined crankshaft acceleration signal comprises;

means for identifying a frequency (f_n) of the crankshaft acceleration signal to be filtered and obtaining an identified frequency (f_n), and

means for filtering out the identified frequency (f_n) from the crankshaft acceleration signal.

9. An automotive system comprising 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 crank position sensor being suitable to send crankshaft signals to an Electronic Control Unit of the internal combustion engine, wherein the Electronic Control Unit is configured to:

command the fuel injector to perform a test fuel injection with a predetermined energizing time;

use the crank position sensor to determine a crankshaft acceleration signal during the test fuel injection and obtain a determined crankshaft acceleration signal;

filter the determined crankshaft acceleration signal and obtain a filtered crankshaft acceleration signal;

determine a value of an amplitude of a fundamental frequency component of the filtered crankshaft acceleration signal and obtain a determined value of an amplitude of the fundamental frequency component;

determine 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

use the correction factor to correct an energizing time of subsequent fuel injections performed by the fuel injector,

wherein the filtering of the determined crankshaft acceleration signal comprises the steps of;

identifying a frequency (f_n) of the crankshaft acceleration signal to be filtered and obtaining an identified frequency (f_n), and

filtering out the identified frequency (f_n) from the crankshaft acceleration signal.

10. A computer readable medium embodying a computer program product, the computer program product comprising:

a computer program 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 computer program configured to;

command the fuel injector to perform a test fuel injection with a predetermined energizing time;

use the crank position sensor to determine a crankshaft acceleration signal during the test fuel injection;

filter the crankshaft acceleration signal and obtain a filtered crankshaft acceleration signal;

determine a value of an amplitude of a fundamental frequency component of the filtered crankshaft acceleration signal and obtain a determined value of the amplitude of the fundamental frequency component;

determine 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

use the correction factor to correct an energizing time of subsequent fuel injections performed by the fuel injector,

wherein during the filtering of the crankshaft acceleration signal the computer program is configured to;

identify a frequency (f_n) of the crankshaft acceleration signal to be filtered, and

filter out the frequency (f_n) from the crankshaft acceleration signal.