OBD calorimetric sensor system with offset error correction
First Claim
1. An on-board diagnostic method for determining if the emissions of an internal combustion engine in a vehicle with a catalytic converter comply with regulatory standards comprising the steps of:
- a) providing a calorimetric sensor downstream of said catalytic converter developing electrical sensor signals indicative of the concentration of at least one, specific regulated gaseous emission in the vehicle'"'"'s exhaust gases;
b) cyclically operating said engine between a first operating condition producing exhaust gases having a first composition of gaseous emissions and a second operating condition producing exhaust gases having a second, composition of gaseous emissions with different concentrations of specific emissions than said first mixture;
c) determining a delta signal indicative of the difference between said calorimetric signals generated for said first and second gas mixtures in any given cycle; and
,d) comparing said delta signal to a stored value correlated to the efficiency of said catalytic converter to convert said specific gaseous emissions to harmless gaseous emissions to satisfy said regulatory standards whereby a relative sensor signal, independent of an absolute value, senses concentrations of specific regulated gaseous emissions to determine compliance with said regulatory standards.
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Accused Products
Abstract
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.
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Citations
102 Claims
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1. An on-board diagnostic method for determining if the emissions of an internal combustion engine in a vehicle with a catalytic converter comply with regulatory standards comprising the steps of:
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a) providing a calorimetric sensor downstream of said catalytic converter developing electrical sensor signals indicative of the concentration of at least one, specific regulated gaseous emission in the vehicle'"'"'s exhaust gases; b) cyclically operating said engine between a first operating condition producing exhaust gases having a first composition of gaseous emissions and a second operating condition producing exhaust gases having a second, composition of gaseous emissions with different concentrations of specific emissions than said first mixture; c) determining a delta signal indicative of the difference between said calorimetric signals generated for said first and second gas mixtures in any given cycle; and
,d) comparing said delta signal to a stored value correlated to the efficiency of said catalytic converter to convert said specific gaseous emissions to harmless gaseous emissions to satisfy said regulatory standards whereby a relative sensor signal, independent of an absolute value, senses concentrations of specific regulated gaseous emissions to determine compliance with said regulatory standards. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. An on-board monitoring system for detecting a failure of the catalytic converter in the exhaust system of a vehicle equipped with an internal combustion engine to control concentrations of certain gaseous emissions of said vehicle within regulatory standards, said system comprising:
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a calorimetric sensor downstream of said catalytic converter for generating, when activated, electrical sensor signals indicative of at least one regulated gaseous emission in said vehicle'"'"'s exhaust gas; means for cyclically operating said engine between a first operating condition producing a first exhaust gas composition of gaseous emissions within a first range of concentrations and a second operating condition producing a composition of gaseous emissions within a second range of concentrations, said first and second emissions concentration ranges being different from one another to produce different heat releases resulting from exothermic oxidation reactions of certain gaseous emissions sensed by said calorimetric sensor; means for generating a delta signal resulting from the difference between said calorimetric sensor signals of said first composition and said second composition sensed in the same cycle; means for comparing said delta signal to a stored signal, said stored signal correlated to said first and second operating conditions for determining the efficiency of said catalyst converter to convert said at least one regulated sensed emission to harmless emissions without reference to a specific value assigned the sensor signal at any specific condition; and
,means for actuating an alarm indicator should said stored value be exceeded. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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65. In an on-board monitoring method to determine if the catalytic converter has deteriorated to the extent that a vehicle equipped with an internal combustion engine exhausts certain gaseous emissions to the atmosphere in excess of regulatory standards, said vehicle having an ECU controlling the ratio of combustion air to fuel supplied said engine in accordance with a plurality of sensor signals including those generated by an exhaust gas sensor located upstream of said catalytic converter and by a plurality of systems utilizing any given sensor signal including an EGR system to meter and mix a portion of the exhaust gases with said combustion air, said ECU cycling said ratio of combustion air to fuel supplied to said engine between a first rich mixture and a second lean mixture during certain operating conditions of said vehicle, the improvement comprising the steps of:
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a) providing a calorimetric sensor downstream of said catalytic converter for generating electrical signals corresponding to the thermal energy in the concentration of at least one regulated, specific gaseous emission within said exhaust stream; b) recording said calorimetric sensor signal when said engine is operating at one of said air to fuel mixtures to produce a first sensor signal and immediately recording said calorimetric signal when said engine switches to and is operating at the other one of said air to fuel mixtures to produce a second sensor signal; and
,c) comparing the difference between said first and second recorded signals to a stored value indicative of the efficiency of said catalytic converter to determine whether said vehicle is in compliance with said regulatory standards. - View Dependent Claims (66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84)
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85. A system for controlling and monitoring the exhaust emissions produced by an internal combustion engine in a vehicle comprising:
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a) a light off catalytic converter having a wash cost substantially devoid of ceria and containing a precious metal coating; b) an exhaust gas sensor upstream of said catalytic converter developing electrical signals indicative of the oxygen content in exhaust gases produced by said vehicle; c) a sensor downstream of said catalytic converter developing signals indicative of specific gaseous emissions in said exhaust gases; d) ECU means for controlling the operation of said engine in response to said oxygen signals to cyclically produce an exhaust gas having first and second exhaust gas mixtures with different concentrations of gaseous emissions; e) said ECU means having means i) to record said emission sensor signals developed by said emission sensor for said first and second mixtures in each signal, ii) generate a delta signal indicative of the difference in said emission signals for said first and second mixtures and iii) compare said delta signal to a stored signal indicative of the efficiency of said catalytic converter. - View Dependent Claims (86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102)
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Specification