Catalyst monitor based on a thermal power model
First Claim
1. An on-board monitoring system for a vehicle which includes a catalytic converter to process exhaust gas generated by an internal combustion engine comprising, in combination:
- means for initiating a catalytic converter diagnostic test;
means, responsive to the initiation of said diagnostic test and responsive to a plurality of temperature sensing devices positioned at spaced intervals upon said catalytic converter, for generating a plurality of temperature values, each of said temperature values being indicative of the temperature detected by a corresponding temperature sensing device;
means, responsive to at least one engine operating parameter, for determining if said engine is operating within a predetermined operating range;
means, responsive to said engine operating within said predetermined range, for storing said temperature values for a plurality of time intervals to generate a set of stored temperature values;
means responsive to the expiration of said time intervals for retrieving said set of stored temperature values and for generating a total power value indicative of the thermal-power generated by said catalytic converter during said time intervals;
means for comparing said total power value to a predetermined power value; and
means for providing an indication if the total power value deviates from the predetermined power value by more than a predetermined deviation amount.
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Accused Products
Abstract
An on-board monitoring system for estimating the hydrocarbon conversion efficiency of a vehicle catalytic converter receives temperature signals from a plurality of temperature sensors positioned to detect the temperature of exhaust gas entering the catalytic converter and to detect the temperature of the catalyst substrate in the catalytic converter at spaced positions along the direction of flow. Diagnostic routine initiation tests are performed to determine if the vehicle is operating within an acceptable range, and if so, then a plurality of sets of temperature values are measured and stored over a plurality of time intervals. During the time intervals, several engine operating parameters are checked to determine if the vehicle is operating within a range which conforms approximately to the range of operation encountered in the Federal Test Procedure (FTP). Upon expiration of the time intervals, a total energy value, indicative of the thermal energy developed in the catalytic converter over the plurality of intervals is generated and compared to a predetermined value. If the calculated energy value deviates from the predetermined value by more than a predetermined deviation amount, a malfunction indicator light is set to indicate excessive deterioration of the catalytic converter.
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Citations
10 Claims
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1. An on-board monitoring system for a vehicle which includes a catalytic converter to process exhaust gas generated by an internal combustion engine comprising, in combination:
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means for initiating a catalytic converter diagnostic test; means, responsive to the initiation of said diagnostic test and responsive to a plurality of temperature sensing devices positioned at spaced intervals upon said catalytic converter, for generating a plurality of temperature values, each of said temperature values being indicative of the temperature detected by a corresponding temperature sensing device; means, responsive to at least one engine operating parameter, for determining if said engine is operating within a predetermined operating range; means, responsive to said engine operating within said predetermined range, for storing said temperature values for a plurality of time intervals to generate a set of stored temperature values; means responsive to the expiration of said time intervals for retrieving said set of stored temperature values and for generating a total power value indicative of the thermal-power generated by said catalytic converter during said time intervals; means for comparing said total power value to a predetermined power value; and means for providing an indication if the total power value deviates from the predetermined power value by more than a predetermined deviation amount. - View Dependent Claims (2, 3)
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4. In a vehicle which includes a catalytic converter for processing regulated-exhaust gas emissions generated by an internal combustion engine of the vehicle, a method for detecting the hydrocarbon conversion efficiency of a catalytic converter comprising the steps of:
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sensing the operating temperature of the engine and comparing the operating temperatures to a predetermined operating temperature range; sensing the mass air flow rate into the engine and comparing the mass air flow rate to a predetermined air flow rate range; if said operating temperature is within said predetermined operating temperature range and said mass air flow rate is within said predetermined air flow rate range, then initiating a diagnostic test which comprises the steps of, periodically measuring at a plurality of time intervals, the temperature of exhaust gas entering the catalytic converter and periodically measuring the temperature of a catalyst substrate in said catalytic converter at a plurality of spaced intervals along said catalyst substrate to generate a plurality of sets of temperature values, each set containing temperature values measured within a particular time interval; generating from said sets of temperature values a total power value indicative of the thermal power generated by said catalytic converter during said time intervals; comparing said total power value to a predetermined power value; and providing an indication if the total power value deviates from the predetermined power value by more than a predetermined deviation amount.
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5. In a vehicle which utilizes a catalytic converter for processing regulated exhaust gas emissions generated by an internal combustion engine, a method for determining the HC conversion-efficiency of said catalytic converter comprising, in combination:
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checking at least a first engine operating parameter to determine if said engine is operating within a predetermined operating range; if said engine is operating within said predetermined operating range then, measuring the temperature of exhaust gas entering the catalytic converter and measuring the temperature of a catalyst substrate in the catalytic converter at spaced positions along the catalyst substrate for a predetermined number of time intervals; generating as a function of the measured temperature of the exhaust gas entering the catalytic converter and the measured temperature of the catalyst substrate, an energy value indicative of the total energy generated in the catalyst over said predetermined number of time intervals; comparing said total energy value to a predetermined total energy value; and providing an indication if the total energy value deviates from the predetermined power value by more than a predetermined deviation amount. - View Dependent Claims (6, 7, 8, 9, 10)
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Specification