Air/fuel control with on-board emission measurement
First Claim
1. An air/fuel control system for an engine having an exhaust coupled to a catalytic converter, comprising:
- a first sensor positioned downstream of the converter for providing a first electrical signal related to concentration of nitrogen oxide in the exhaust;
a second sensor positioned downstream of the converter for providing a second electrical signal related to concentration of at least one exhaust by-product other than nitrogen oxides;
a fuel controller delivering fuel to the engine in relation to a feedback variable derived from said first and second electrical signals; and
said fuel controller providing a measurement of engine emissions in response to a conversion of said first signal from concentration of nitrogen oxides to mass of nitrogen oxides emitted and a conversion of said second signal from concentration of said exhaust by-product to mass of said exhaust by-product emitted.
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Accused Products
Abstract
An engine air/fuel control system (8) and method for controlling an engine (28) coupled to a catalytic converter (50) and for providing a measurement of engine emissions (202-296). Nitrogen oxides concentration, hydrocarbon concentration, and carbon monoxide concentration of exhaust gases downstream of the converter are measured (46, 54, and 52). Each concentration measurement is averaged for the speed load cell in which such measurement occurred (244-256). Each concentration average measurement is converted to a measurement of mass emissions emitted during a test cycle (268-284). Fuel delivered to the engine is corrected by a feedback variable (104-134, 158-178) derived from both an exhaust gas oxygen sensor (44) positioned upstream of the converter and the three sensors positioned downstream of the converter (46, 52, 54). A measurement of emissions in response to the averaged mass measurements of emission concentration downstream of the converter is also provided (278-296).
134 Citations
20 Claims
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1. An air/fuel control system for an engine having an exhaust coupled to a catalytic converter, comprising:
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a first sensor positioned downstream of the converter for providing a first electrical signal related to concentration of nitrogen oxide in the exhaust; a second sensor positioned downstream of the converter for providing a second electrical signal related to concentration of at least one exhaust by-product other than nitrogen oxides; a fuel controller delivering fuel to the engine in relation to a feedback variable derived from said first and second electrical signals; and said fuel controller providing a measurement of engine emissions in response to a conversion of said first signal from concentration of nitrogen oxides to mass of nitrogen oxides emitted and a conversion of said second signal from concentration of said exhaust by-product to mass of said exhaust by-product emitted. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An engine air/fuel control method for controlling an engine coupled to a catalytic converter and for providing a measurement of engine emissions, comprising the steps of:
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measuring nitrogen oxide concentration of exhaust gases downstream of the converter; converting said nitrogen oxide concentration measurement to a measurement of mass of nitrogen oxide emitted to generate a first measurement signal; measuring hydrocarbon concentration of exhaust gases downstream of the converter; converting said hydrocarbon concentration measurement to a measurement of mass of hydrocarbon emitted to generate a second measurement signal; and correcting fuel delivered to the engine by a feedback variable derived from both said first measurement signal and said second measurement signal to maintain the engine air/fuel ratio at optimal converter efficiency and providing a measurement of emissions in response to said first measurement signal and said second measurement signal. - View Dependent Claims (12, 13, 14)
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15. An engine air/fuel control method for controlling an engine coupled to a catalytic converter and for providing a measurement of engine emissions, comprising the steps of:
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averaging samples of nitrogen oxide concentration measurements of exhaust gases downstream of the converter for each of a plurality of engine speed and load operating ranges; averaging samples of hydrocarbon concentration measurements of exhaust gases downstream of the converter for each of a plurality of engine speed and load operating ranges. converting said nitrogen oxide concentration averages to nitrogen oxide mass averages; converting said hydrocarbon concentration averages to hydrocarbon mass averages; and correcting fuel delivered to the engine by a feedback variable derived from said nitrogen oxide measurements and said hydrocarbon measurements to maintain engine air/fuel ratio at optimal converter efficiency and providing a measurement of mass emissions in response to said nitrogen oxide mass averages and said hydrocarbon mass averages. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification