SYSTEM AND METHODS FOR FUEL SYSTEM LEAK DETECTION

• US 20160069771A1
• Filed: 09/10/2014
• Published: 03/10/2016
• Est. Priority Date: 09/10/2014
• Status: Abandoned Application

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Makki, Imad Hassan, Tseng, Fling Finn, Dudar, Aed M., Jentz, Robert Roy, Kumar, Pankaj
• Application Number:
  US14/482,423
• Publication Number:
  US 20160069771A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system

Abstract

A method for a fuel system comprises indicating a leak in the fuel system based on a pressure change rate distribution during a first condition including a sealed fuel system and a pressure change rate within a threshold of zero. By indicating a leak based on a pressure change rate distribution rather than through simple thresholding, an engine-off natural vacuum test may be performed in a greater range of conditions. In this way, the execution rate of the test may be increased while maintaining or improving the leak detection rate and reducing the misclassification rate.

Claims

1. A method for a fuel system, comprising:

indicating a leak in the fuel system based on a pressure change rate distribution during a first condition including a sealed fuel system and a pressure change rate within a threshold of zero.

2. The method of claim 1, further comprising:

applying a low-pass filter to the pressure change rate distribution; and

then

indicating the leak in the fuel system based on the filtered pressure change rate distribution.

3. The method of claim 1, further comprising:

indicating the leak in the fuel system based on a minimum error between a measured fuel tank pressure and a predicted fuel tank pressure.

4. The method of claim 3, where the measured fuel tank pressure comprises an equilibrium fuel tank pressure.

5. The method of claim 3, where the predicted fuel tank pressure is based on a fuel tank temperature.

6. The method of claim 5, where the predicted fuel tank pressure is based on a fuel composition.

7. The method of claim 6, where the predicted fuel tank pressure is determined using an Antoine equation relationship.

8. The method of claim 3, further comprising:

classifying the pressure change rate distribution and minimum error using a linear classifier; and

indicating the leak in the fuel system based on an output of the linear classifier.

9. The method of claim 8, further comprising:

indicating an indeterminate result if the output of the linear classifier is within a threshold of a decision boundary.

10. A method for a fuel system, comprising:

sealing a fuel system; and

executing an evaporative emissions leak test only if a duration of a fuel system pressure increase event is greater than a threshold.

11. The method of claim 10, where executing an evaporative emissions leak test further comprises:

extracting one or more fuel system pressure features for classification via a linear classifier; and

indicating a fuel system leak based on the extracted fuel system pressure features.

12. The method of claim 11, where the one or more fuel system pressure features include a minimum error between a measured fuel tank pressure and a predicted fuel tank pressure.

13. The method of claim 12, where the measured fuel tank pressure comprises an equilibrium fuel tank pressure.

14. The method of claim 12, where the predicted fuel tank pressure is based on a fuel tank temperature.

15. The method of claim 14, where the predicted fuel tank pressure is based on a fuel composition.

16. The method of claim 15, where the predicted fuel tank pressure is determined using an Antoine equation relationship.

17. The method of claim 11, where the one or more fuel system pressure features include a pressure change rate distribution within the fuel system during a condition where a pressure change rate is within a threshold of zero.

18. The method of claim 17, where the pressure change rate distribution is filtered using a low-pass filter prior to classification by the linear classifier.

19. The method of claim 11, further comprising:

comparing an output of the linear classifier to a decision boundary; and

indicating an indeterminate result if the output of the linear classifier is within a threshold of a decision boundary.

20. A fuel system for a vehicle, comprising:

a fuel tank coupled to an evaporative emissions system;

a valve coupled between the fuel tank and atmosphere;

a pressure sensor coupled between the fuel tank and the valve; and

a controller holding executable instructions in non-transitory memory, that when executed, cause the controller to;

close the valve;

execute an evaporative emissions leak test responsive to a duration of a fuel system pressure increase event being greater than a threshold;

determine a minimum error between an equilibrium fuel tank pressure and a predicted fuel tank pressure;

determine a pressure change rate distribution within the fuel system during a condition where a pressure change rate is within a threshold of zero;

using a linear classifier, indicate a fuel system leak based on the determined minimum error and the determined pressure change rate distribution; and

indicate an indeterminate result if an output of the linear classifier is within a threshold of a decision boundary.