Method and device for controlling a motor-vehicle internal combustion engine fitted with a fuel injection system and an exhaust gas recirculation system

Patent metadata

Field	Value
Publication number	US-10202945-B2
Application number	US-201615243494-A
Country	US
Kind code	B2
Filing date	Aug 22, 2016
Priority date	Aug 24, 2015
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

Embodiments are provided herein for controlling a motor-vehicle internal combustion engine fitted with a fuel injection system and an exhaust gas recirculation system. In one example, in a deceleration phase a closed exhaust gas recirculation circuit is formed, a mass (mcirc) of an air quantity enclosed therein is determined, a first oxygen content (O2,exh1, O2,man1) of the air quantity is detected, a test injection is carried out with an injection valve, a second oxygen content (O2,exh2, O2,man2) of the air quantity is detected, and the fuel mass (mfuel) injected in the test injection is determined from the mass (mcirc) of the air quantity and the first and the second oxygen content (O2,exh1, O2,man1, O2,exh2, O2,man2). The disclosure also relates to a corresponding device for controlling a motor-vehicle internal combustion engine fitted with a fuel injection system and an exhaust gas recirculation system.

First claim

The invention claimed is:

1. A method for controlling a motor-vehicle internal combustion engine fitted with a fuel injection system and an exhaust gas recirculation system, comprising:
in a deceleration phase, forming a closed exhaust gas recirculation circuit;
determining a mass (m circ ) of an air quantity enclosed in the closed exhaust gas recirculation circuit;
detecting a first oxygen content of the air quantity;
carrying out a test injection with an injection valve;
detecting a second oxygen content of the air quantity; and
determining a fuel mass (m fuel ) injected in the test injection from the mass (m circ ) of the air quantity and the first and the second oxygen contents.

2. The method as claimed in claim 1 , wherein forming the closed exhaust gas recirculation circuit comprises activating an exhaust valve, an intake throttle valve, and an exhaust gas recirculation valve, or activating the exhaust valve and a three-way valve in an intake tract.

3. The method as claimed in claim 1 , wherein the mass (m circ ) of the air quantity is determined by at least one pressure sensor and at least one temperature sensor.

4. The method as claimed in claim 1 , further comprising observing a first waiting time t 1 after the formation of the closed exhaust gas recirculation circuit and before the detection of the first oxygen content, and/or observing a second waiting time t 2 after the test injection is carried out and before the second oxygen content is detected.

5. The method as claimed in claim 1 , wherein the first and second oxygen contents are measured by at least one oxygen sensor in the exhaust tract and/or at least one oxygen sensor in the intake tract.

6. The method as claimed in claim 5 , wherein a respective fuel mass (m fuel,exh , m fuel,man ) injected in the test injection is calculated from the first oxygen content and the second oxygen content each measured by the at least one oxygen sensor in the exhaust tract, and further from a third oxygen content and a fourth oxygen content each measured by the at least one oxygen sensor in the intake tract, and an average is formed in order to determine the fuel mass (m fuel ) injected in the test injection.

7. The method as claimed in claim 1 , wherein the internal combustion engine has a plurality of injection valves and wherein the fuel mass (m fuel ) injected in a respective test injection is determined for each injection valve.

8. The method as claimed in claim 1 , wherein an exhaust gas aftertreatment system of the internal combustion engine is controlled on a basis of the fuel mass (m fuel ) determined.

9. The method as claimed in claim 1 , wherein a correction of at least one injection parameter is determined from at least one injection parameter of the test injection and from the fuel mass (m fuel ) determined in order to adapt the injected fuel mass (m fuel ) to a setpoint fuel mass (m test,sol1 ) and wherein the injection valve is activated in at least one further injection in accordance with the correction determined.

10. The method as claimed in claim 9 , wherein at least one injection parameter is an injection duration (T inj ).

11. A method for controlling an internal combustion engine fitted with a fuel injection system and an exhaust gas recirculation system, comprising:
modifying an injection duration of at least one injection valve;
measuring a consumed oxygen fraction of exhaust gas, wherein the measuring occurs after a first waiting time t 1 after the formation of a closed exhaust gas recirculation circuit, wherein substantially an entire exhaust gas flow from the internal combustion engine is passed through the exhaust gas recirculation system into an intake tract of the internal combustion engine, and substantially no fresh air is supplied to the intake tract;
estimating a consumed oxygen fraction of the exhaust gas;
determining an optimum injection duration in accordance with a difference between the measured and estimated consumed oxygen fractions; and
activating at least one injection valve with an adapted injection duration dependent on the optimum injection duration.

12. The method as claimed in claim 11 , wherein the method is carried out during an operating phase of the internal combustion engine with approximately constant operating conditions.

13. The method as claimed in claim 11 , wherein the estimated consumed oxygen fraction is determined from a model dependent on an air mass flow and a setpoint injection duration.

14. The method as claimed in claim 13 , wherein the model is a dynamic model.

15. The method as claimed in claim 11 , wherein the estimated consumed oxygen fraction is determined on a basis of a consumed oxygen fraction of charge air.

16. The method as claimed in claim 15 , wherein the estimated consumed oxygen fraction is determined taking into account a setpoint injection duration and a measured pressure and a measured temperature of the charge air.

17. The method as claimed in claim 11 , wherein the optimum injection duration is determined in such a way that an absolute value of the difference between the measured and estimated consumed oxygen fractions in the exhaust gas reaches a minimum.

18. A method, comprising:
adjusting a fuel injection parameter for a fuel injection event to a cylinder of an engine based on a fuel injector correction factor, the fuel injector correction factor representing a difference between a first consumed oxygen fraction in a closed exhaust gas recirculation (EGR) circuit prior to a test fuel injection event and a second consumed oxygen fraction in the closed EGR circuit after the test fuel injection event, wherein, upon formation of the closed EGR circuit, substantially an entire exhaust gas flow from the engine is passed through an EGR system into an intake tract of the engine, and substantially no fresh air is supplied to the intake tract.

19. The method of claim 18 , wherein the fuel injector correction factor is determined responsive to a no-load condition of the engine where the engine is rotating, and wherein adjusting the fuel injection parameter comprises adjusting a fuel injection duration of the fuel injection event relative to a setpoint fuel injection duration.

20. The method of claim 19 , further comprising:
responsive to the no-load condition of the engine while the engine is rotating, closing an exhaust throttle valve and an intake throttle valve and opening an EGR valve to form the closed EGR circuit;
determining the first consumed oxygen fraction as a function of an estimated air mass in the closed EGR circuit and a first signal output from an oxygen sensor positioned in the closed EGR circuit;
performing the test fuel injection event;
after the test fuel injection event, determining the second consumed oxygen fraction as a function of the estimated air mass in the closed EGR circuit and a second signal output from the oxygen sensor;
calculating an actual fuel mass of the test fuel injection event from a difference between the first consumed oxygen fraction and the second consumed oxygen fraction; and
setting the fuel injector correction factor as a function of the actual fuel mass and a setpoint fuel mass of the test fuel injection event.

Assignees

• Ford Global Tech Llc

Inventors

• Vigild Christian Winge
• De Smet Frederik
• Roettger Daniel

Classifications

• F02M26/47

  the characteristics being temperatures, pressures or flow rates · CPC title

• F02D41/0055 Primary

  Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus · CPC title

• F02M26/71 Primary

  Multi-way valves · CPC title

• F02D41/008

  Controlling each cylinder individually · CPC title

• F02D41/12

  for deceleration {(F02D41/0005, F02D41/107 take precedence)} · CPC title