Catalyst monitoring in a diesel engine
First Claim
1. A method for monitoring a performance of a catalytic converter, comprising:
- determining a conversion efficiency of the catalytic converter based on an amount of a carbon and oxygen carrying component in an exhaust gas mixture entering the converter and on an amount of said carbon and oxygen carrying component in an exhaust gas mixture exiting the converter;
generating a first measure of the catalytic converter performance based on not less than two of said conversion efficiency calculations performed at different operating temperatures of the converter, such temperatures extending to a predetermined temperature, such predetermined temperature being a temperature where the conversion efficiency for an aged catalytic converter and a new catalytic converter are substantially the same; and
comparing said first measure to a second measure indicative of a threshold performance of the catalytic converter.
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Accused Products
Abstract
A carbon monoxide sensor placed downstream of the catalytic converter and a temperature sensor placed upstream of the converter in a diesel engine provide information to build a real time CO conversion efficiency versus catalyst temperature curve to determine whether a catalyst has deteriorated beyond a predetermined point with respect to On-Board Diagnostic (OBD) requirements. Pre catalyst CO concentration is inferred from the engine operating conditions, and catalyst temperature is determined using the temperature sensor output and the engine exhaust flow heat transfer model. The real time curve is compared to a reference curve to determine catalyst performance. Catalyst performance with respect to CO conversions can then be correlated to that for HC and NOx to meet OBD requirements.
46 Citations
18 Claims
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1. A method for monitoring a performance of a catalytic converter, comprising:
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determining a conversion efficiency of the catalytic converter based on an amount of a carbon and oxygen carrying component in an exhaust gas mixture entering the converter and on an amount of said carbon and oxygen carrying component in an exhaust gas mixture exiting the converter;
generating a first measure of the catalytic converter performance based on not less than two of said conversion efficiency calculations performed at different operating temperatures of the converter, such temperatures extending to a predetermined temperature, such predetermined temperature being a temperature where the conversion efficiency for an aged catalytic converter and a new catalytic converter are substantially the same; and
comparing said first measure to a second measure indicative of a threshold performance of the catalytic converter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for monitoring a performance of a catalytic converter, the system comprising:
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a diesel engine having the converter disposed in its exhaust passage;
a sensor coupled downstream of the converter, said sensor providing a signal indicative of an amount of carbon monoxide in an exhaust gas mixture exiting the catalytic converter; and
a controller estimating an amount of carbon monoxide in an exhaust gas mixture entering the catalytic converter, and performing at least two calculations of a catalytic converter efficiency based on said estimating and said sensor signal, said calculations performed at different operating temperatures of the converter, such temperatures extending to a predetermined temperature, such predetermined temperature being a temperature where the conversion efficiency for an aged catalytic converter and a new catalytic converter are substantially the same. - View Dependent Claims (13, 14, 15)
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16. A system for monitoring a performance of a catalytic converter, the system comprising:
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a diesel engine having the catalytic converter coupled downstream;
a sensor coupled upstream of the converter, said sensor providing a first signal indicative of a concentration of carbon monoxide in an exhaust gas mixture entering the catalytic converter;
a sensor coupled downstream of the converter, said sensor providing a second signal indicative of a concentration of carbon monoxide in an exhaust gas mixture exiting the catalytic converter; and
a controller for calculating a catalyst conversion efficiency based on said first and said second signals and;
wherein said controller further generates a measure of converter performance based on not less than two said efficiency calculations performed at different operating temperatures of the converter, such temperatures extending to a predetermined temperature, such predetermined temperature being a temperature where the conversion efficiency for an aged catalytic converter and a new catalytic converter are substantially the same. - View Dependent Claims (17, 18)
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Specification