METHOD AND APPARATUS FOR PROVIDING FUEL TO AN AIRCRAFT ENGINE

• US 20090283080A1
• Filed: 05/15/2008
• Published: 11/19/2009
• Est. Priority Date: 05/15/2008
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Lycoming Engines
• Inventors: Schneider, Charles, Matas, Scott, Watson, Allan
• Granted Patent: US 7,658,184 B2
• Time in Patent Office: Days
• US Class Current: 123/676
• CPC Class Codes: F02D 41/1446 the characteristics being exhaust temperatures
• CPC Class Codes: F02D 41/1475 Regulating the air fuel ratio at a value other than stoichiometry

Abstract

An aircraft engine includes an aircraft engine controller configured to detect an actual peak exhaust gas temperature of a cylinder assembly. The aircraft engine controller detects an intersection between a first function representing a relationship between a set of rich exhaust gas temperature signals and a corresponding set of rich fuel-air ratio values and a second function representing a relationship between a set of lean exhaust gas temperature signals and a set of lean fuel-air ratio values. Based upon the intersection between the first and second functions, the engine controller detects an actual peak fuel-air ratio value for the cylinder assembly and can determine if a correction in the fuel-air ratio of a fuel-air mixture provided to the cylinder assembly is required. Accordingly, the engine controller provides each cylinder assembly of the aircraft engine with an accurate fuel-air mixture to allow for operation of the engine with optimal fuel economy.

Claims

1. A method for adjusting a fuel-air ratio for a fuel-air mixture provided to a cylinder assembly of an engine, comprising:

detecting a set of rich exhaust gas temperature signals corresponding to a set of rich fuel-air ratio values, each of the set of rich fuel-air ratio values having a fuel-air ratio value that is greater than a threshold fuel-air ratio value;

detecting a set of lean exhaust gas temperature signals corresponding to a set of lean fuel-air ratio values, each of the set of lean fuel-air ratio values having a fuel-air ratio value that is less than the threshold fuel-air ratio value;

detecting an intersection between the set of lean exhaust gas temperature signals and the set of rich exhaust gas temperature signals, the intersection associated with an actual peak fuel-air ratio value;

comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value; and

adjusting the fuel-air ratio in the fuel-air mixture provided to the cylinder assembly based upon the comparison of the actual peak fuel-air ratio value and threshold fuel-air ratio value.

2. The method of claim 1, wherein:

detecting the set of rich exhaust gas temperature signals comprises;

detecting a first rich exhaust gas temperature signal when the fuel-air mixture has a first rich fuel-air ratio value greater than the threshold fuel-air ratio value,

decreasing an amount of fuel in the fuel-air mixture, and

detecting a second rich exhaust gas temperature signal when the fuel-air mixture has a second rich fuel-air ratio value greater than the threshold fuel-air ratio value; and

detecting the set of lean exhaust gas temperature signals comprises;

detecting a first lean exhaust gas temperature signal when the fuel-air mixture has a first lean fuel-air ratio value less than the threshold fuel-air ratio value,

increasing an amount of fuel in the fuel-air mixture, and

detecting a second lean exhaust gas temperature signal when the fuel-air mixture has a second lean fuel-air ratio value greater than the threshold fuel-air ratio value.

3. The method of claim 1, wherein detecting an intersection between the set of lean exhaust gas temperature signals and the set of rich exhaust gas temperature signals, comprises:

generating a first function representing a relationship between the set of rich exhaust gas temperature signals and the set of rich fuel-air ratio values;

generating a second function representing a relationship between the set of lean exhaust gas temperature signals and the set of lean fuel-air ratio values; and

detecting an exhaust gas temperature value and an fuel-air ratio value common to both the first function and the second function.

4. The method of claim 3, wherein:

generating the first function comprises generating a linear regression relationship for the set of rich exhaust gas temperature signals and the set of rich fuel-air ratio values; and

generating the second function comprises generating a linear regression for the set of lean exhaust gas temperature signals and the set of lean fuel-air ratio values.

5. The method of claim 4, wherein comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value comprises comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a linear regression value for the linear regression relationship of the set of rich exhaust gas temperature signals and the set of rich fuel-air ratio values exceeds a threshold fit value.

6. The method of claim 4, wherein comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value comprises comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a linear regression value for the linear regression relationship of the set of lean exhaust gas temperature signals and the set of lean fuel-air ratio values falls exceeds a threshold fit value.

7. The method of claim 4, wherein comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value comprises comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a ratio between a change in rich exhaust gas temperature signal values and a change in rich fuel-air ratio values falls within a threshold slope range.

8. The method of claim 4, wherein comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value comprises comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a ratio between a change in lean exhaust gas temperature signal values and a change in lean fuel-air ratio values falls within a threshold slope range.

9. The method of claim 1, comprising adjusting a volume of the fuel-air mixture delivered to the cylinder assembly based upon a scaling factor.

10. The method of claim 1, comprising, after detecting the set of rich exhaust gas temperature signals corresponding to a set of rich fuel-air ratio values, decreasing the amount of fuel in the fuel-air mixture such that fuel-air ratio value is less than the threshold fuel-air ratio value.

11. An engine control system, comprising:

an exhaust gas temperature sensor, the exhaust gas temperature sensor configured to generate gas temperature signals associated with a cylinder assembly of an engine; and

an engine controller disposed in electrical communication with the exhaust gas temperature sensor, the engine controller being operable to adjust a fuel-air ratio for a fuel-air mixture provided to the cylinder assembly, the engine controller configured to;

detect a set of rich exhaust gas temperature signals corresponding to a set of rich fuel-air ratio values, each of the set of rich fuel-air ratio values having a fuel-air ratio value that is greater than a threshold fuel-air ratio value;

detect a set of lean exhaust gas temperature signals corresponding to a set of lean fuel-air ratio values, each of the set of lean fuel-air ratio values having a fuel-air ratio value that is less than the threshold fuel-air ratio value;

detect an intersection between the set of lean exhaust gas temperature signals and the set of rich exhaust gas temperature signals, the intersection associated with an actual peak fuel-air ratio value;

compare the actual peak fuel-air ratio value with the threshold fuel-air ratio value; and

adjust the fuel-air ratio in the fuel-air mixture provided to the cylinder assembly based upon the comparison of the actual peak fuel-air ratio value and threshold fuel-air ratio value.

12. The engine controller of claim 11, wherein:

when detecting the set of rich exhaust gas temperature signals, the engine controller is configured to;

detect a first rich exhaust gas temperature signal when the fuel-air mixture has a first rich fuel-air ratio value greater than the threshold fuel-air ratio value,

decrease an amount of fuel in the fuel-air mixture, and

detect a second rich exhaust gas temperature signal when the fuel-air mixture has a second rich fuel-air ratio value greater than the threshold fuel-air ratio value; and

when detecting the set of lean exhaust gas temperature signals, the engine controller is configured to;

detect a first lean exhaust gas temperature signal when the fuel-air mixture has a first lean fuel-air ratio value less than the threshold fuel-air ratio value,

increase an amount of fuel in the fuel-air mixture, and

detect a second lean exhaust gas temperature signal when the fuel-air mixture has a second lean fuel-air ratio value greater than the threshold fuel-air ratio value.

13. The engine controller of claim 12, wherein when detecting an intersection between the set of lean exhaust gas temperature signals and the set of rich exhaust gas temperature signals, the engine controller is configured to:

generate a first function representing a relationship between the set of rich exhaust gas temperature signals and the set of rich fuel-air ratio values;

generate a second function representing a relationship between the set of lean exhaust gas temperature signals and the set of lean fuel-air ratio values; and

detect an exhaust gas temperature value and an fuel-air ratio value common to both the first function and the second function.

14. The engine controller of claim 13, wherein the engine controller is configured to:

generate the first function comprises generating a linear regression relationship for the set of rich exhaust gas temperature signals and the set of rich fuel-air ratio values; and

generate the second function comprises generating a linear regression for the set of lean exhaust gas temperature signals and the set of lean fuel-air ratio values.

15. The engine controller of claim 14, wherein when comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value the engine controller is configured to compare the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a linear regression value for the linear regression relationship of the set of rich exhaust gas temperature signals and the set of rich fuel-air ratio values exceeds a threshold fit value.

16. The engine controller of claim 14, wherein when comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value the engine controller is configured to compare the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a linear regression value for the linear regression relationship of the set of lean exhaust gas temperature signals and the set of lean fuel-air ratio values falls exceeds a threshold fit value.

17. The engine controller of claim 14, wherein when comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value the engine controller is configured to compare the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a ratio between a change in rich exhaust gas temperature signal values and a change in rich fuel-air ratio values falls within a threshold slope value.

18. The engine controller of claim 14, wherein when comparing the actual peak fuel-air ratio value with the threshold fuel-air ratio value the engine controller is configured to compare the actual peak fuel-air ratio value with the threshold fuel-air ratio value when a ratio between a change in lean exhaust gas temperature signal values and a change in lean fuel-air ratio values falls within a threshold slope value.

19. The engine controller of claim 11, comprising adjusting a volume of the fuel-air mixture delivered to the cylinder assembly based upon a scaling factor.

20. The engine controller of claim 11, wherein, after detecting the set of rich exhaust gas temperature signals corresponding to a set of rich fuel-air ratio values, the engine controller is configured to decrease the amount of fuel in the fuel-air mixture such that fuel-air ratio value is less than the threshold fuel-air ratio value.