Automotive on-board monitoring system for catalytic converter evaluation

A method for on-board monitoring of the gaseous pollutant emissions produced by a computer controlled internal combustion engine of a vehicle, said method comprising the steps of:

• a) producing emission signals only from an emission sensor downstream of the vehicle's catalytic converter;
• b) producing at least a first vehicle operative condition signal used by said computer to control the operation of said vehicle's internal combustion engine;
• c) matching and storing simultaneously generated operative condition signals and emission signals in a plurality of histograms under the control of said computer, each histogram corresponding to a range of values sensed by said operative condition sensor and each emission signal stored in a histogram corresponding to a specific range of operative condition signals determined by the value of said operative condition signal sensed when said emission signal was generated;
• d) sampling each histogram once a set number of emission signals have been stored therein by factoring said emission signals in each histogram to determine a statistically validated emission level for each range of sensed operative conditions;
• e) comparing each validated emission level with a regulatory threshold emission value corresponding to said operative condition range;
• and
• f) activating a fault detecting alarm in the vehicle when a set number of validated emission levels exceed their corresponding threshold emission level.

An on-board vehicular catalytic converter monitoring system for determining failure of a vehicle to meet emission regulatory standards comprising:

• a) a hydrocarbon sensor downstream of the catalytic converter generating emission signals during vehicle operation indicative of the gaseous pollutants produced by said vehicle's internal combustion engine;
• b) a speed sensor on the vehicle generating operating speed signals indicative of the speed of said vehicle during its operation;
• and
• c) computer means with memory for simultaneously processing said emission signals and said speed signals to determine when and if said emission signals have exceeded regulatory standards, said computer means including:
• i) matching means for matching each emission signal with a simultaneously generated speed signal;
• ii) storing means for storing each emission signal in memory to build a plurality of histograms of emission signals, each histogram correlated to a range of speed values such that any given emission signal is stored in a given histogram corresponding to a speed range determined by said speed signal simultaneously generated and matched with any given emission signal;
• iii) sampling means activated when a set number of emission signals have been stored in said histograms for factoring said emission signals in each histogram to determine a factored emission state of said vehicle at given vehicle speeds indicative of the actual pollutants emitted by said vehicle;
• iv) comparing means for comparing only said factored emission state to a stored threshold emission level corresponding to a regulatory emission standard for any given vehicle speed;
• and
• d) fault indicating means in said vehicle activated to alert the vehicle operator of an emission failure when said comparing means has sensed a factored emission state exceeding said threshold level for a preset number of histograms.