Method of operating an internal combustion engine

• US 9,765,725 B2
• Filed: 02/17/2015
• Issued: 09/19/2017
• Est. Priority Date: 02/19/2014
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Nieddu, Stefano
• Primary Examiner(s): Cronin, Stephen K
• Assistant Examiner(s): BAILEY, JOHN D
• Application Number:
  US14/623,921
• Publication Number:
  US 20150233318A1
• Time in Patent Office: 945 Days
• Field of Search: 701101, 701103, 701104, 1234063, 12340632, 12340645, 12340647, 123445, 123446, 123457, 123510, 123511, 123514, 123515, 123530
• CPC Class Codes: F02D 2041/1433 using a model or simulation of the system
• CPC Class Codes: F02D 2041/224 Diagnosis of the fuel system
• CPC Class Codes: F02D 2041/225 Leakage detection
• CPC Class Codes: F02D 2041/288 for performing a transformation into the frequency domain, e.g. Fourier transformation
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02D 2200/0614 Actual fuel mass or fuel injection amount
• CPC Class Codes: F02D 2250/04 Fuel pressure pulsation in common rails
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02D 41/1401 characterised by the control or regulation method F02D41/1473, F02D41/1477 take precedence
• CPC Class Codes: F02D 41/3809 Common rail control systems common rail apparatus F02M55/025, F02M63/0225
• CPC Class Codes: F02D 41/3863 by controlling the flow out of the common rail, e.g. using pressure relief valves
• CPC Class Codes: F02D 41/401 Controlling injection timing F02D41/402 takes precedence
• CPC Class Codes: F02D 41/402 Multiple injections
• CPC Class Codes: F02M 63/0225 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 Class Codes: Y02T 10/40 Engine management systems

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.

Claims

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;

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:

8. The method according to claim 6, wherein the injection pattern performed by the fuel injectors is composed by a plurality of equal injection pulses and wherein the vector {right arrow over (Q)}_tot,k is expressed by the following equation:

9. The method according to claim 6, wherein the injection pattern performed by the fuel injectors is composed by a main injection pulse and at least one auxiliary injection pulse, wherein the at least one auxiliary injection pulse is smaller than the main injection pulse, and wherein the vector {right arrow over (Q)}_tot,k is expressed by the following equation:

10. The 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)}HP,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; and

_{{right arrow over (Q)}HP,k} is a vector representative of the k^th harmonic order of the fuel flow rate supplied by the fuel pump into the fuel rail.

11. The method according to claim 10, 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:

12. The method according to claim 10, wherein the injection pattern performed by the fuel injectors is composed by a plurality of equal injection pulses and wherein the vector {right arrow over (Q)}_tot,k is expressed by the following equation:

13. The method according to claim 10, wherein the injection pattern performed by the fuel injectors is composed by a main injection pulse and at least one auxiliary injection pulse, wherein the at least one auxiliary injection pulse is smaller than the main injection pulse, and wherein the vector {right arrow over (Q)}_tot,k is expressed by the following equation:

14. A computer program comprising a computer code suitable for performing the method according to claim 1, wherein the computer code is stored on a non-transitory computer readable medium.

15. A computer program product comprising a processor executing the computer program of claim 14 is stored.

16. A control apparatus for an internal combustion engine, comprising an Electronic Control Unit, a data carrier associated to the Electronic Control Unit and a computer program according to claim 15 stored in the data carrier.

17. A fuel injection system comprising:

a fuel pump;

a fuel rail in fluid communication with the pump;

a plurality of fuel injectors in fluid communication with the fuel rail; and

an electronic control unit programmed to;

operate each of the plurality of fuel injectors to perform a predetermined injection pattern per engine cycle;

sample a fuel rail pressure signal representative of a fuel pressure within the fuel rail during the operation of the fuel injectors;

perform a Fourier analysis of the fuel rail pressure signal to determine at least one harmonic components thereof;

calculate a dynamic fuel quantity that flows through a fuel injector during an injection pulse of the injection pattern using following relation;

18. The fuel injection system according to claim 17 wherein the electronic control unit is further configured to use 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 cut-off condition.

19. The fuel injection system according to claim 17 wherein the electronic control unit is further configured to use 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.