Method of detection of flow duct obstruction

• US 6,684,702 B2
• Filed: 03/28/2002
• Issued: 02/03/2004
• Est. Priority Date: 03/25/2002
• Status: Expired due to Fees

• Current Assignee: Mcmaster University
• Original Assignee: Mcmaster University
• Inventors: Ziada, Samir
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Saint-Surin, Jacques
• Application Number:
  US10/112,907
• Publication Number:
  US 20030183010A1
• Time in Patent Office: 677 Days
• Field of Search: 735/87, 73/37, 736/27, 73/405.A, 73/407, 73/18.2, 735/99, 736/00, 736/02
• US Class Current: 73/587
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• CPC Class Codes: F01N 13/00 Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
• CPC Class Codes: F01N 13/10 of exhaust manifolds with cooling jacket F01N3/046
• CPC Class Codes: F01N 13/1866 the channels or tubes thereof being made integrally with the housing

Abstract

A method for detecting an obstruction in a flow duct is provided. The method includes the steps of directing gas through at least one port of the flow duct, measuring a flow noise level of the gas directed through the at least one port, and comparing the noise level with a predetermined noise level. In the event that the flow noise level exceeds the predetermined noise level by at least a threshold amount, then the method includes the step of indicating the presence of an obstruction in the at least one port.

Claims

1. A method for detecting an obstruction in a flow duct comprising:

directing gas through at least one port of said flow duct to cause flow of said gas through said at least one port;

measuring a flow noise level of said flow of said gas through said at least one port;

comparing said noise level with a predetermined noise level; and

detecting when said flow noise level exceeds said predetermined noise level by at least a threshold amount, then indicating the presence of an obstruction in said at least one port.

2. The method according to claim 1 wherein said predetermined noise level is a predetermined average noise level representative of the noise level of an unobstructed part.

3. The method according to claim 1 wherein said flow duct is an exhaust manifold.

4. The method according to claim 3 wherein each of said steps of directing gas, measuring a flow noise level, comparing said noise level and determining if an obstruction is present are repeated for each port of said manifold for detecting if any one of the ports of said manifold are obstructed.

5. The method according to claim 1 further comprising:

obtaining an acoustic noise spectral analysis on known obstructed and know unobstructed flow ducts prior to measuring said flow noise level to identify a frequency range of interest; and

calculating said predetermined noise level by averaging noise levels over said frequency range for said known unobstructed flow ducts.

6. The method according to claim 5 wherein said threshold amount is calculated by determining the maximum difference between said known unobstructed flow ducts and said predetermined noise level.

7. The method according to claim 5 wherein said step of measuring a flow noise level includes filtering for discarding noise above and below said frequency range.

8. The method according to claim 1 wherein said gas is air.

9. The method according to claim 1 wherein said flow noise level is determined by measuring the root mean square amplitude of the noise.

10. The method according to claim 1 wherein said flow noise level is measured using a microphone.

11. The method according to claim 10 wherein said microphone is a pressure transducer.