Method of operating an internal combustion engine

Patent metadata

Field	Value
Publication number	US-9765725-B2
Application number	US-201514623921-A
Country	US
Kind code	B2
Filing date	Feb 17, 2015
Priority date	Feb 19, 2014
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

An apparatus and method for controlling a fuel injection system of an internal combustion engine is disclosed. Each fuel injector in the system is operated to perform a predetermined injection pattern per engine cycle. A signal representative of a fuel pressure within the fuel rail during the operation of the fuel injectors is sampled. A Fourier analysis of the fuel rail pressure signal is performed to determine one or more harmonic components thereof. The determined harmonic components of the fuel rail pressure signal are used to calculate a dynamic fuel quantity that flows through a fuel injector during an injection pulse of the injection pattern. A fuel quantity actually injected by the fuel injector during the injection pulse as a function of the dynamic fuel quantity is calculated.

First claim

What is claimed is:

1. A method of operating an internal combustion engine having a fuel rail in fluid communication with the fuel pump and a plurality of fuel injectors in fluid communication with the fuel rail, wherein the method comprises:
operating each fuel injector to perform a predetermined injection pattern per engine cycle;
sampling a fuel rail pressure signal representative of a fuel pressure within the fuel rail during the operation of the fuel injectors;
performing a Fourier analysis of the fuel rail pressure signal to determine at least one harmonic components thereof;
calculating a dynamic fuel quantity that flows through a fuel injector during an injection pulse of the injection pattern using the following relation:

→

P
k

⁢

=

P
k
a

+

j
⁢

⁢

P
k
β

=

-

1

k
·

C
h

·
j

⁢

→
Q

rail
,
k

wherein:
{right arrow over (p)} k is a vector representative of the k th harmonic order of the fuel rail pressure signal;
P k α is the real part of the vector {right arrow over (p)} k ;
C h is the hydrodynamic capacitance of the fuel rail;
j is the imaginary unit; and
{right arrow over (Q)} rail,k is a vector representative of the k th harmonic of the fuel flow rate through the fuel rail;
determining a calculated fuel quantity actually injected by the fuel injector during the injection pulse as a function of the dynamic fuel quantity; and
adjusting an energizing time actually needed for each of the plurality of fuel injectors to inject a desired quantity of fuel with each of the plurality of the fuel injectors based on the calculate fuel quantity actually injected.

2. The method according to claim 1 further comprising using the calculated fuel quantity actually injected in a closed loop control of the fuel injected quantity when the internal combustion engine is running under cut-off condition.

3. The method according to claim 1 further comprising using the calculated fuel quantity actually injected is used in a closed loop control of the fuel injected quantity when the internal combustion engine is running under a normal operating condition.

4. The method according to claim 1 , further comprising sampling the fuel rail pressure signal in a crankshaft angular domain.

5. The method according to claim 1 , further comprising sampling the fuel rail pressure signal with a sampling frequency that is higher than the frequency of the predetermined injection patterns.

6. A method according to claim 1 wherein the vector {right arrow over (Q)} rail,k is expressed by the following equation:
{right arrow over (Q)} rail,k =− {right arrow over (Q)} tot,k

Wherein {right arrow over (Q)} tot,k is a vector representative of the k th harmonic order of the fuel flow rate that exits the fuel rail through all the fuel injectors.

7. The method according to claim 6 , wherein the predetermined injection pattern performed by the fuel injectors is composed by a single injection pulse, and wherein the vector {right arrow over (Q)} tot,k is expressed by the following equation:

Q
→

tot
,
k

=

∑

l
=
1

n

⁢

⁢

q
→

l
,
k

=

∑

l
=
1

n

⁢

⁢

q
l

π

⁢

e

j
⁢

⁢
k
⁢

⁢
2
⁢

π
/
n

·

(

l
-
1

)

Wherein:
n is the number of fuel injectors;
{right arrow over (q)} l,k is a vector representative of the k th harmonic order of the dynamic fuel quantity that flows through the l th fuel injector during the injection pulse; and
q l is the dynamic fuel quantity flowing through the l th fuel injector during the injection pulse.

8. The method according to claim 6 , wherein the injection pat

Assignees

• Gm Global Tech Operations Llc

Inventors

• Nieddu Stefano

Classifications

• F02D41/3809 Primary

  Common rail control systems (common rail apparatus F02M55/025, F02M63/0225) · CPC title

• F02D2041/225

  Leakage detection · CPC title

• F02D2041/224

  Diagnosis of the fuel system · CPC title

• F02D41/3863

  by controlling the flow out of the common rail, e.g. using pressure relief valves · CPC title

• F02M63/0225

  Fuel-injection apparatus having a common rail feeding several injectors (F02M63/0003 takes precedence); Means for varying pressure in common rails; Pumps feeding common rails · CPC title