Claims
- 1. A method of controlling an internal combustion engine when the engine is operating in an engine braking mode, the engine having at least one cylinder and an intake manifold that supplies a controllable airflow to the at least one cylinder, wherein when the engine is operating in the engine braking mode an exhaust valve for the cylinder is prematurely opened to dissipate power, the method comprising:
determining a desired mass airflow rate to the at least one cylinder when the engine is operating in the engine braking mode; determining an actual mass airflow rate to the at least one cylinder when the engine is operating in the engine braking mode; comparing the desired mass airflow rate to the actual mass airflow rate; and controlling the airflow based on the comparison such that the actual mass airflow rate tracks the desired mass airflow rate.
- 2. The method of claim 1 wherein determining the desired mass airflow rate further comprises:
determining a desired braking level; determining an engine speed; and determining the desired mass airflow rate based on the desired braking level, and the engine speed.
- 3. The method of claim 1 wherein determining the actual mass airflow rate further comprises:
determining an engine speed; determining an intake manifold air pressure; determining an intake manifold air temperature; and determining the actual mass airflow rate based on the engine speed, the intake manifold air pressure, and the intake manifold air temperature.
- 4. The method of claim 3 wherein determining the actual mass airflow rate further comprises:
determining a number of braking cylinders; determining a correction factor based on the number of braking cylinders; and determining the actual mass airflow rate based on the engine speed, the intake manifold air pressure, the intake manifold air temperature, and the correction factor.
- 5. The method of claim 1 wherein controlling the airflow further comprises:
determining a mass airflow rate error based on the comparison; determining a plurality of control terms; and controlling the airflow based on the mass airflow rate error and the plurality of control terms.
- 6. The method of claim 5 further comprising:
determining a desired braking level; determining an engine speed; determining a feed forward term based on the desired braking level, and the engine speed; and controlling the airflow based on the mass airflow rate error, the plurality of control terms, and the feed forward term.
- 7. The method of claim 1 wherein the engine includes a variable geometry turbocharger, and wherein controlling the airflow further comprises:
varying the geometry of the turbocharger based on the comparison.
- 8. The method of claim 7 wherein varying the geometry of the turbocharger further comprises:
determining a braking turbocharger geometry based on the comparison of the desired mass air flow rate to the actual mass air flow rate; determining a turbocharger actual speed; establishing a turbocharger maximum speed; comparing the turbocharger actual speed to the turbocharger maximum speed; determining a limit turbocharger geometry based on the comparison of the turbocharger actual speed to the turbocharger maximum speed; comparing the limit turbocharger geometry to the braking turbocharger geometry; and varying the geometry based on the comparison of the limit turbocharger geometry to the braking turbocharger geometry.
- 9. The method of claim 1 further comprising:
determining a plurality of braking levels based on engine operating conditions; selecting a desired braking level from the plurality of braking levels; determining an engine speed; and determining the desired mass air flow rate based on the desired braking level, and the engine speed.
- 10. The method of claim 9 wherein determining a plurality of braking levels further comprises:
determining a first braking level based on a position of a dash input switch.
- 11. The method of claim 10 wherein determining a plurality of braking levels further comprises:
determining a second braking level based on a status of a cruise control.
- 12. The method of claim 11 wherein determining a plurality of braking levels further comprises:
determining a third braking level based on engine operating conditions.
- 13. An internal combustion engine having an engine controller including a computer readable storage medium having instructions stored thereon that direct the engine controller to perform a method of controlling the internal combustion engine when the engine is operating in an engine braking mode, the engine having at least one cylinder and an intake manifold that supplies a controllable airflow to the at least one cylinder, wherein when the engine is operating in the engine braking mode an exhaust valve for the cylinder is prematurely opened to dissipate power, the medium further comprising:
instructions for determining a desired mass airflow rate to the at least one cylinder when the engine is operating in the engine braking mode; instructions for determining an actual mass airflow rate to the at least one cylinder when the engine is operating in the engine braking mode; instructions for comparing the desired mass airflow rate to the actual mass airflow rate; and instructions for controlling the airflow based on the comparison such that the actual mass airflow rate tracks the desired mass airflow rate.
- 14. The engine of claim 13 wherein the instructions for determining the desired mass airflow rate further comprise:
instructions for determining a desired braking level; instructions for determining an engine speed; and instructions for determining the desired mass airflow rate based on the desired braking level, and the engine speed.
- 15. The engine of claim 13 wherein the instructions for determining the actual mass airflow rate further comprise:
instructions for determining an engine speed; instructions for determining an intake manifold air pressure; instructions for determining an intake manifold air temperature; and instructions for determining the actual mass airflow rate based on the engine speed, the intake manifold air pressure, and the intake manifold air temperature.
- 16. The engine of claim 15 wherein the instructions for determining the actual mass airflow rate further comprise:
instructions for determining a number of braking cylinders; instructions for determining a correction factor based on the number of braking cylinders; and instructions for determining the actual mass airflow rate based on the engine speed, the intake manifold air pressure, the intake manifold air temperature, and the correction factor.
- 17. The engine of claim 13 wherein the instructions for controlling the airflow further comprise:
instructions for determining a mass airflow rate error based on the comparison; instructions for determining a plurality of control terms; and instructions for controlling the airflow based on the mass airflow rate error and the plurality of control terms.
- 18. The engine of claim 17 wherein the medium further comprises:
instructions for determining a desired braking level; instructions for determining an engine speed; instructions for determining a feed forward term based on the desired braking level and the engine speed; and instructions for controlling the airflow based on the mass airflow rate error, the plurality of control terms, and the feed forward term.
- 19. The engine of claim 13 wherein the engine includes a variable geometry turbocharger, and wherein the instructions for controlling the airflow further comprise:
instructions for varying the geometry of the turbocharger based on the comparison.
- 20. The engine of claim 19 wherein the instructions for varying the geometry of the turbocharger further comprise:
instructions for determining a braking turbocharger geometry based on the comparison of the desired mass air flow rate to the actual mass air flow rate; instructions for determining a turbocharger actual speed; instructions for establishing a turbocharger maximum speed; instructions for comparing the turbocharger actual speed to the turbocharger maximum speed; instructions for determining a limit turbocharger geometry based on the comparison of the turbocharger actual speed to the turbocharger maximum speed; instructions for comparing the limit turbocharger geometry to the braking turbocharger geometry; and instructions for varying the geometry based on the comparison of the limit turbocharger geometry to the braking turbocharger geometry.
- 21. The engine of claim 13 wherein the medium further comprises:
instructions for determining a plurality of braking levels based on engine operating conditions; instructions for selecting a desired braking level from the plurality of braking levels; instructions for determining an engine speed; and instructions for determining the desired mass air flow rate based on the desired braking level, and the engine speed.
- 22. The engine of claim 21 wherein the instructions for determining a plurality of braking levels further comprise:
instructions for determining a first braking level based on a position of a dash input switch.
- 23. The engine of claim 22 wherein the instructions for determining a plurality of braking levels further comprise:
instructions for determining a second braking level based on a status of a cruise control.
- 24. The engine of claim 23 wherein the instructions for determining a plurality of braking levels further comprise:
instructions for determining a third braking level based on engine operating conditions.
- 25. An engine controller for an internal combustion engine, the engine controller including a computer readable storage medium having instructions stored thereon that direct the engine controller to perform a method of controlling the internal combustion engine when the engine is operating in an engine braking mode, the engine having at least one cylinder and an intake manifold that supplies a controllable airflow to the at least one cylinder, wherein when the engine is operating in the engine braking mode an exhaust valve for the cylinder is prematurely opened to dissipate power, the medium further comprising:
instructions for determining a desired mass airflow rate to the at least one cylinder when the engine is operating in the engine braking mode; instructions for determining an actual mass airflow rate to the at least one cylinder when the engine is operating in the engine braking mode; instructions for comparing the desired mass airflow rate to the actual mass airflow rate; and instructions for controlling the airflow based on the comparison such that the actual mass airflow rate tracks the desired mass airflow rate.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional application Serial No. 60/398,737 filed Jul. 26, 2002.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60398737 |
Jul 2002 |
US |