Engine control to reduce emissions variability

• US 6,581,571 B2
• Filed: 06/12/2001
• Issued: 06/24/2003
• Est. Priority Date: 06/12/2001
• Status: Expired due to Fees

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Latusek, John Phillip, Kubesh, John Thomas, McCaw, Donald Lee, Podnar, Daniel James
• Primary Examiner(s): Gimie, Mahmoud
• Application Number:
  US09/879,641
• Publication Number:
  US 20020185107A1
• Time in Patent Office: 742 Days
• Field of Search: 123/406.44, 123/406.45, 123/688, 123/679, 123/672, 602/76
• 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 oxide of nitrogen (NOx) in exhaust gases produced by the engine with a single NOx sensor which has an output which is substantially proportional to concentration of NOx in said exhaust gases, and generating a sensed NOx value representative thereof;

generating a base NOx value;

calculating an NOx difference value by subtracting the base NOx value from the sensed NOx value; and

modifying an engine control system set point as a function of the NOx difference value in order to reduce an amount of NOx in the engine exhaust.

2. The method of claim 1, wherein:

the engine control system set points comprises spark timing.

3. The method of claim 1, 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.

4. The method of claim 1, further comprising:

sensing engine RPM;

calculating an engine air flow value; and

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

5. The method of claim 1, further comprising:

sensing humidity in engine intake air; and

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

6. The method of claim 1, further comprising:

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

7. The method of claim 6, further comprising:

sensing humidity in engine intake air; and

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

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

a single NOx concentration sensor in an exhaust of the engine generating a sensed NOx value representative thereof, NOx sensor having an output which is substantially proportional to concentration of NOx in said exhaust gases; 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.

9. The control system of claim 8, 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.

10. The control system of claim 8, 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.

11. The control system of claim 8, 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.

12. The method of claim 8, 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.