Method of operating an internal combustion engine

Patent metadata

Field	Value
Publication number	US-10233861-B2
Application number	US-201715648069-A
Country	US
Kind code	B2
Filing date	Jul 12, 2017
Priority date	Jul 13, 2016
Publication date	Mar 19, 2019
Grant date	Mar 19, 2019

Abstract

A method and apparatus are disclosed for determining the fuel quantity that is actually injected by a fuel injector in an internal combustion engine. A fuel injector is operated to perform a fuel injection. The first discharge stroke of the fuel pump is deactivated following a start of the fuel injection for preventing the discharge stroke from delivering fuel into the fuel rail. A value of a pressure drop caused into the fuel rail by the fuel injection is calculated. A value of a fuel quantity injected by the fuel injection is calculated on the basis of the calculated value of the pressure drop.

First claim

What is claimed is:

1. A method of operating an internal combustion engine having a fuel rail in fluid communication with at least one fuel injector and a fuel pump configured to perform a discharge stroke after each fuel injection performed by the fuel injector, the method comprising:
performing a fuel injection with the fuel injector;
deactivating the fuel pump during a first discharge stroke following a start of the fuel injection to prevent said first discharge stroke from delivering fuel into the fuel rail;
calculating a pressure drop value in the fuel rail resulting from the fuel injection; and
calculating a quantity of fuel injected by said fuel injection based on the pressure drop value.

2. The method according to claim 1 further comprising:
calculating a difference between the calculated quantity of fuel injected and a predetermined target value thereof; and
adjusting a subsequent fuel injection using the calculated difference.

3. The method according to claim 2 , wherein calculating the pressure drop value comprises:
measuring a first value of a fuel rail pressure before the start of said fuel injection;
measuring a second value of the fuel rail pressure after the end of said fuel injection; and
calculating the pressure drop value as a difference between the first and the second measured values of the fuel rail pressure.

4. The method according to claim 3 , wherein measuring the first and second values of the fuel rail pressure comprises:
sampling a signal representative of the fuel rail pressure;
filtering the signal to obtain a filtered signal;
measuring a first value of the filtered signal before the start of said fuel injection;
measuring a second value of the filtered signal after the end of said fuel injection; and
calculating the first value and the second value of the fuel rail pressure on the basis of the first and the second value of the filtered signal respectively.

5. The method according to claim 4 , wherein the filtering of the signal is performed with a SINC filter.

6. The method according to claim 5 , wherein the SINC filter is tuned on a dominant frequency of a pressure oscillation in the fuel rail.

7. The method according to claim 2 , wherein calculating the pressure drop value comprises:
sampling a pressure signal representative of the fuel rail pressure during the fuel injection,
performing a first integral transform on the pressure signal to yield a first function value based on the fuel rail pressure drop caused by the fuel injection and a timing parameter indicative of an instant when the fuel injection started;
performing a second integral transform on the pressure signal to yield a second function value based on the fuel rail pressure drop caused by the fuel injection and the timing parameter indicative of the instant when the fuel injection started;
calculating the pressure drop value based on the first function value and the second function value.

8. The method according to claim 2 , further comprising activating a number of discharge strokes following the deactivated discharge stroke for delivering fuel into the fuel rail.

9. The method according to claim 8 , wherein the number of activated pump strokes is equal to the number of fuel injectors.

10. The method according to claim 9 , wherein the activation of each discharge strokes comprises delivering a volume of fuel into the fuel rail having a value Q* according to the following equation:

Q
*

=

n

n
-
1

·
Q

wherein n is the number of fuel injectors and Q is a value of a fuel volume that would have been delivered if all the discharge strokes had been activated.

11. The method according to claim 2 , wherein the internal combustion engine comprises a cylinder, a reciprocating piston which is accommodated inside the cylinder, an operating chamber and an inlet valve, the method further comprising:
reciprocally moving the piston in a first direction along a suction stroke to fill the operating chamber with fuel coming from a fuel source;
reciprocally moving the piston in a second direction opposite the first direction along a discharge stroke that delivers fuel to the fuel rail;
operating the inlet valve for controlling admission of fuel into the operating chamber; and
keeping the inlet valve open during the discharge stroke of the piston for deactivating the first discharge stroke.

12. A non-transitory computer readable medium comprising processor-executable instructions for reading data from a processor in communication with the fuel injector and the fuel pump, the processor-executable instructions when executed on the processor in a device configured to carry out the method according to claim 2 .

13. An internal combustion engine comprising:
a fuel rail in fluid communication with at least one fuel injectors and a fuel pump configured to perform a discharge stroke after each fuel injection performed by the fuel injectors; and
an electronic control unit configured to:
perform a fuel injection with the fuel injector;
deactivate the fuel pump during a first discharge stroke following a start of the fuel injection to prevent said first discharge stroke from delivering fuel into the fuel rail;
calculate a pressure drop value in the fuel rail resulting from the fuel injection; and
calculate a quantity of fuel injected by said fuel injection based on the pressure drop value.

14. A method of operating an internal combustion engine having a fuel pump supplying pressurized fuel to a fuel rail in fluid communication with at least one fuel injector, the method comprising:
operating a fuel pump inlet valve to control admission of fuel into the fuel pump;
reciprocally moving a fuel pump piston in a first direction during a suction stroke to fill a fuel pump operating chamber with fuel from a fuel source;
reciprocally moving the fuel pump piston in a second direction opposite the first direction during a discharge stroke to deliver pressurized fuel from the operating chamber to the fuel rail;
initiating an injection of pressurized fuel from the fuel rail through the fuel injector;
opening the fuel pump inlet valve during the first discharge stroke after initiating the injection to deactivate the fuel pump and cease delivery of pressurized fuel into the fuel rail;
calculating a pressure drop value in the fuel rail resulting from the injection;
calculating a quantity of fuel injected by the injection based on the pressure drop value.

Assignees

• Gm Global Tech Operations Llc
• Gm Global Tech Operatons Llc

Inventors

• Nieddu Stefano
• Mollar Andrea

Classifications

• F02D41/3872 Primary

  characterised by leakage flow in injectors · CPC title

• F02D41/3845

  by controlling the flow into the common rail, e.g. the amount of fuel pumped · CPC title

• F02D41/1401

  characterised by the control or regulation method (F02D41/1473, F02D41/1477 take precedence) · CPC title

• F02D41/401 Primary

  Controlling injection timing (F02D41/402 takes precedence) · CPC title

• F02D2200/0616

  determined by estimation · CPC title