Catalyst monitoring using a hydrocarbon sensor

Abstract

An on-board monitoring system for an automotive emission catalyst has (i) a test chamber remote from the automobile's engine exhaust gas stream; (ii) apparatus for supplying the chamber with sampled exhaust gases sequestered from the stream; (iii) a single hydrocarbon sensor exposed to the exhaust gas in the chamber to render a signal responsive to the concentration of hydrocarbon in the chamber; and (iv) apparatus for comparing the sensed signal with a reference signal, and, if a predetermined difference is exceeded, the catalyst is indicated as faulty. Apparatus (ii) has a supply channel interconnected between the chamber and the gas stream upstream of the catalytic converter, a supply channel independently interconnected between the chamber and the gas stream downstream of the catalytic converter, and valve apparatus for permitting flow-through of no more than one channel to the chamber at any one moment, preferably cycled at a certain frequency. Method steps carried out by the system comprise: (a) periodically transferring a sample quantity of gas from the stream into a test chamber at a predetermined flow rate; (b) exposing a hydrocarbon sensor to the sequestered gas to generate a signal in proportion to the content of hydrocarbon in such gas; and (c) comparing the signal with a reference signal to determine if a predetermined difference exists and thereby conclude the catalyst is sufficiently degraded.

Dependencies are inferred from the claim text.