Motorola Corporation

Engelhard Corporation

David Richard Price

Jeffrey D Naber

Ronald Marshall Heck

Edward N Balko

Sanath V Kumar

Patrick W Blosser

Alan J Chewter

An on-board catalytic monitoring system uses an intrusive technique to cause the vehicle's engine to cycle between first and second operating conditions. The first and second operating conditions are chosen such that different concentrations of emissions with different chemistries are present at the first and second operating conditions. A calorimetric sensor with a selective catalyst senses exothermic oxidation reactions produced by the emissions in the exhaust gas passing over the sensor. By matching the catalyst activity with the emission concentrations occurring at the operating conditions, the difference between the heat release sensor signals detected between the first and second operating conditions is indicative of the actual concentration of specific emissions in the exhaust gas stream. The difference or delta signal, obtained without reference to a zero point, provides an excellent correlation to the efficiency of the vehicle's catalytic converter for converting the sensed emission, i.e., hydrocarbons.

OBD calorimetric sensor system with offset error correction

A method and apparatus converts time-resolved sensor signals into transfer functions and/or cumulative transfer function signals which can be attained by computation means such as by using Fast Fourier Transforms. A signal, as a means to assess catalyst performance such as a signal based on sensing oxygen concentration or air to fuel ratio or hydrocarbon concentration in motor vehicle exhaust in accordance with the present invention is in the time domain and has multiple components at different frequencies. The use of Fast Fourier Transforms isolates the various spectral densities which arise from different frequency components of the complex time domain signal. Cross spectral density function and power spectral density function are used to determine the transfer function. The analysis has been found to be substantially independent of operating conditions. The transfer function and cumulative transfer function have been found to be a precise indication of the catalyst performance. The catalyst performance can be signaled to the vehicle operator for on board diagnostics (OBD) of the catalyst.

Apparatus and method for diagnosis of catalyst performance

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Ann Arbor, MI, United States of America

David Richard Price