Diagnostic systems and methods for engine knock sensors

• US 7,769,536 B2
• Filed: 02/24/2009
• Issued: 08/03/2010
• Est. Priority Date: 12/31/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Horner, Robert J., Hamama, Wajdi B., Sawdon, Craig M., Ferch, Eric, Esfahan, Hamid M.
• Primary Examiner(s): Huynh; Hai H
• Application Number:
  US12/391,479
• Publication Number:
  US 20100168991A1
• Time in Patent Office: 525 Days
• Field of Search: 701/111, 73/350.7, 731/140.2, 731/141.6, 123/435, 123/406.16, 123/406.21, 123/406.37, 123/406.39, 123/406.38
• US Class Current: 701/111
• CPC Class Codes: F02D 2041/288 for performing a transformation into the frequency domain, e.g. Fourier transformation
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An engine control system includes a digital signal processing (DSP) module that generates a fast Fourier transform (FFT) of an engine knock signal generated by an engine knock sensor. An intensity determination module determines an engine knock intensity based on one of a maximum of and an average of the FFT. A status determination module determines a status of the engine knock sensor based on the engine knock intensity, a plurality of predetermined knock intensity thresholds, and a rotational speed of an engine crankshaft.

Claims

1. An engine control system comprising:

a digital signal processing (DSP) module that generates a fast Fourier transform (FFT) of an engine knock signal generated by an engine knock sensor;

an intensity determination module that determines an engine knock intensity based on one of a maximum of and an average of the FFT; and

a status determination module that determines a status of the engine knock sensor based on the engine knock intensity, a plurality of predetermined knock intensity thresholds, and a rotational speed of an engine crankshaft.

2. The engine control system of claim 1, wherein the predetermined knock intensity thresholds are based on the rotational speed of the engine crankshaft.

3. The engine control system of claim 2, wherein the plurality of predetermined knock intensity thresholds includes a plurality of low intensity thresholds and a plurality of high intensity thresholds.

4. The engine control system of claim 3, wherein the status of the engine knock sensor is set to failure when the engine knock intensity is between one of the low intensity thresholds and one of the high intensity thresholds.

5. The engine control system of claim 4, wherein a failure count is incremented when the status of the engine knock sensor is set to failure during a predetermined time interval.

6. The engine control system of claim 5, wherein the failure count is output and reset to zero after the predetermined time interval.

7. The engine control system of claim 6, further comprising:

a knock control module that actuates one or more of a plurality of fuel injectors and a plurality of spark plugs based on the engine knock signal when the failure count is less than or equal to a predetermined failure count threshold.

8. The engine control of claim 1, wherein the FFT includes a plurality of subsets corresponding to a plurality of frequency ranges.

9. The engine control system of claim 8, wherein each of the subsets includes a plurality of intensities corresponding to a plurality of frequencies.

10. The engine control system of claim 9, wherein the intensity determination module determines the engine knock intensity based on one of a maximum of and an average of intensities corresponding to one of the subsets.

11. A method comprising:

generating a fast Fourier transform (FFT) of an engine knock signal generated by an engine knock sensor;

determining an engine knock intensity based on one of a maximum of and an average of the FFT; and

determining a status of the engine knock sensor based on the engine knock intensity, a plurality of predetermined knock intensity thresholds, and a rotational speed of an engine crankshaft.

12. The method of claim 11, wherein the predetermined knock intensity thresholds are based on the rotational speed of the engine crankshaft.

13. The method of claim 12, wherein the plurality of predetermined knock intensity thresholds includes a plurality of low intensity thresholds and a plurality of high intensity thresholds.

14. The method of claim 13, further comprising:

setting the status of the engine knock sensor to failure when the engine knock intensity is between one of the low intensity thresholds and one of the high intensity thresholds.

15. The method of claim 14, further comprising:

incrementing a failure count when the status of the engine knock sensor is set to failure during a predetermined time interval.

16. The method of claim 15, further comprising:

outputting the failure count after the predetermined time interval; and

resetting the failure count to zero after the predetermined time interval.

17. The method of claim 16, further comprising:

actuating one or more of a plurality of fuel injectors and a plurality of spark plugs based on the engine knock signal when the failure count is less than or equal to a predetermined failure count threshold.

18. The method of claim 11, wherein the FFT includes a plurality of subsets corresponding to a plurality of frequency ranges.

19. The method of claim 18, wherein each of the subsets includes a plurality of intensities corresponding to a plurality of frequencies.

20. The method of claim 19, further comprising:

determining the engine knock intensity based on one of a maximum of and an average of intensities corresponding to one of the subsets.