The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 11, 2000
Filed:
Jan. 25, 1999
Yue Yun Wang, Columbus, IN (US);
Steven W Majors, Indianapolis, IN (US);
Other;
Abstract
A system and method for diagnosing EGR system and EGR cooler faults evaluates a temperature signal generated by a sensor at the EGR cooler, such as a coolant or gas temperature sensor. An engine control module includes an on-board EGR diagnosis unit and DSP that reads the EGR cooler temperature signals over a predetermined time period or sample points, and generates a symmetric signal. A discrete fast Fourier transform is applied to the symmetric signal to develop values for the spectral magnitude and phase angle of a primary frequency component of the signal. These values can be compared to respective predetermined threshold values to determine whether a fault condition has occurred in the EGR system or EGR cooler. In an alternative embodiment, the DSP operates in the time domain to determine a signal power value for the change in cooler temperature signal over a predetermined time period. This signal power value can be compared against one or more threshold values to determine the health of the EGR system and cooler. In a further alternative embodiment, a temperature difference between the coolant temperature measured by the EGR cooler temperature sensor when the EGR valve is opened is compared to a baseline EGR cooler temperature value. Over successive cycles, this temperature difference is compared to various threshold values indicative of an EGR fault, an EGR cooler fault or a cooler failure.