Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Patent
1999-01-25
2000-07-11
Wolfe, Willis R.
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
12356816, 731173, 701108, F02M 2507
Patent
active
060857323
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.
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Majors Steven W.
Wang Yue Yun
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