Engine control to reduce emissions variability

• US 20020185107A1
• Filed: 06/12/2001
• Published: 12/12/2002
• Est. Priority Date: 06/12/2001
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Latusek, John Phillip, Kubesh, John Thomas, McCaw, Donald Lee, Podnar, Daniel James
• Granted Patent: US 6,581,571 B2
• Time in Patent Office: Days
• US Class Current: 123/406.44
• CPC Class Codes: F02D 2200/0418 Air humidity
• CPC Class Codes: F02D 41/146 the characteristics being an NOx content or concentration
• CPC Class Codes: F02P 5/1502 using one central computing unit
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A system and method of controlling an engine includes sensing a concentration of NOx in exhaust gases produced by the engine and generating a sensed NOx value representative thereof, and controlling an engine control set point as a function of the sensed NOx value. The system also calculates a NOx difference value by subtracting a base NOx value from the sensed NOx value, and if an absolute value of the difference value exceeds a threshold, modifying the set point as a function of the NOx difference value. The method also includes sensing engine RPM, sensing engine manifold absolute pressure (MAP), determining the NOx value as a function of sensed engine RPM and MAP.

Claims

1. A method of controlling an engine to reduce variability of engine exhaust emissions, comprising:

sensing a concentration of an emission species in exhaust gases produced by the engine and generating a sensed emission species value representative thereof; and

controlling an engine control system set point as a function of the sensed emission species value.

2. The method of claim 1, wherein:

the engine control system set points comprises spark timing.

3. The method of claim 1, further comprising:

generating a base emission species value;

calculating a emission species difference value by subtracting the base emission species value from the sensed emission species value;

modifying the set point as a function of the emission species difference value in order to reduce an amount of the emission species in the engine exhaust.

4. The method of claim 3, further comprising:

sensing engine RPM;

sensing engine manifold air pressure (MAP); and

determining the base emission species value as a function of sensed engine RPM and MAP.

5. The method of claim 3, further comprising:

sensing engine RPM;

calculating an engine air flow value; and

determining the base emission species value as a function of sensed engine RPM and calculated air flow.

6. The method of claim 3, further comprising:

sensing humidity in engine intake air; and

correcting the base emission species value as a function of the sensed humidity.

7. The method of claim 1, further comprising:

generating a base emission species value;

calculating a emission species difference value by subtracting the base emission species value from the sensed emission species value;

if an absolute value of the difference value exceeds a threshold, modifying the set point as a function of the emission species difference value in order to reduce an amount of the emission species in the engine exhaust.

8. The method of claim 7, further comprising:

sensing humidity in engine intake air; and

correcting the base emission species value as a function of the sensed humidity.

9. A method of controlling an engine to reduce variability of engine exhaust emissions, comprising:

sensing a concentration of NOx in exhaust gases produced by the engine and generating a sensed NOx value representative thereof; and

controlling an engine control system set point as a function of the sensed NOx value.

10. The method of claim 9, further comprising:

generating a base NOx value;

calculating a NOx difference value by subtracting the base NOx value from the sensed NOx value;

modifying the set point as a function of the NOx difference value in order to reduce variability of NOx in the engine exhaust.

11. The method of claim 10, further comprising:

sensing engine RPM;

sensing engine manifold air pressure (MAP); and

determining the base NOx value as a function of sensed engine RPM and MAP.

12. The method of claim 10, further comprising:

sensing engine RPM;

calculating an engine air flow value; and

determining the base emission species value as a function of sensed engine RPM and calculated air flow.

13. The method of claim 10, further comprising:

sensing humidity in engine intake air; and

correcting the base NOx value as a function of the sensed humidity.

14. The method of claim 9, further comprising:

generating a base NOx value;

calculating a NOx difference value by subtracting the base NOx value from the sensed NOx value;

if an absolute value of the NOx difference value exceeds a threshold, modifying the set point as a function of the NOx difference value in order to reduce variability of NOx in the engine exhaust.

15. The method of claim 14, further comprising:

sensing humidity in engine intake air; and

correcting the base NOx value as a function of the sensed humidity.

17. The control system of claim 16, further comprising:

an engine RPM sensor;

an engine manifold air pressure (MAP) sensor; and

the control unit determining the base NOx value as a function of sensed engine RPM and MAP.

18. The control system of claim 16, further comprising:

an engine RPM sensor;

an engine manifold air pressure (MAP) sensor; and

the control unit determining the base NOx value as a function of sensed engine RPM and MAP.

19. The control system of claim 16, further comprising:

a humidity sensor for sensing humidity in engine intake air; and

the control unit correcting the base NOx value as a function of the sensed humidity.

20. The method of claim 16, wherein:

the control unit, if an absolute value of the NOx difference value exceeds a threshold, modifies the set point as a function of the NOx difference value in order to reduce variability of NOx in the engine exhaust.

16. A system for controlling an engine to reduce variability of engine exhaust emissions, comprising:

a NOx concentration sensor in an exhaust of the engine generating a sensed NOx value representative thereof; and

a control unit which generates a base NOx value, calculates a NOx difference value by subtracting the base NOx value from the sensed NOx value, and modifies an engine control system set point as a function of the NOx difference value in order to reduce variability of NOx in the engine exhaust.