Method and apparatus for diagnosing exhaust gas aftertreatment component degradation
First Claim
1. A system for diagnosing operation of an exhaust gas aftertreatment component for an internal combustion engine, the system comprising:
- a NOx sensor producing a NOx signal indicative of NOx content of exhaust gas exiting the aftertreatment component, anda control circuit estimating as a function of a number of engine operating conditions a NOx inlet content corresponding to a NOx content of exhaust gas produced by the engine and entering the aftertreatment component, the control circuit determining a lean NOx conversion efficiency of the aftertreatment component as a function of the NOx signal and of the NOx inlet content and determining that the aftertreatment component is not saturated if the lean NOx conversion efficiency is greater than a first minimum efficiency value and the lean NOx conversion efficiency does not drop below a second minimum efficiency value for more than a first predefined time period, the control circuit responsive to an indicator indicating that regeneration of the aftertreatment component is occurring to determine a NOx conversion efficiency of the aftertreatment component as a function of the NOx signal and of the NOx inlet content and to determine that the aftertreatment component is degraded if the NOx conversion efficiency is below a threshold value, only if the aftertreatment component is not saturated.
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Abstract
A system is provided for diagnosing operation of an exhaust gas aftertreatment component for an internal combustion engine. The system includes a NOx sensor producing a NOx signal indicative of NOx content of exhaust gas exiting the aftertreatment component, and a control circuit configured to estimate as a function of a number of engine operating conditions a NOx inlet content corresponding to a NOx content of exhaust gas produced by the engine and entering the aftertreatment component. The control circuit is configured to determine a NOx conversion efficiency of the aftertreatment component as a function of the NOx signal and of the NOx inlet content, and to determine that the aftertreatment component is degraded if the NOx conversion efficiency is below a threshold value for at least a first predefined time period.
45 Citations
20 Claims
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1. A system for diagnosing operation of an exhaust gas aftertreatment component for an internal combustion engine, the system comprising:
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a NOx sensor producing a NOx signal indicative of NOx content of exhaust gas exiting the aftertreatment component, and a control circuit estimating as a function of a number of engine operating conditions a NOx inlet content corresponding to a NOx content of exhaust gas produced by the engine and entering the aftertreatment component, the control circuit determining a lean NOx conversion efficiency of the aftertreatment component as a function of the NOx signal and of the NOx inlet content and determining that the aftertreatment component is not saturated if the lean NOx conversion efficiency is greater than a first minimum efficiency value and the lean NOx conversion efficiency does not drop below a second minimum efficiency value for more than a first predefined time period, the control circuit responsive to an indicator indicating that regeneration of the aftertreatment component is occurring to determine a NOx conversion efficiency of the aftertreatment component as a function of the NOx signal and of the NOx inlet content and to determine that the aftertreatment component is degraded if the NOx conversion efficiency is below a threshold value, only if the aftertreatment component is not saturated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15)
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12. A system for diagnosing operation of an exhaust gas aftertreatment component for an internal combustion engine, the system comprising:
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a NOx sensor producing a NOx signal indicative of NOx content of exhaust gas exiting the aftertreatment component, an aftertreatment component inlet temperature sensor producing an inlet temperature signal indicative of a temperature of exhaust gas entering the aftertreatment component, an aftertreatment component outlet temperature sensor producing an outlet temperature signal indicative of a temperature of exhaust gas exiting the aftertreatment component, and a control circuit estimating as a function of a number of engine operating conditions a NOx inlet content corresponding to a NOx content of exhaust gas produced by the engine and entering the aftertreatment component, the control circuit determining a bed temperature of the aftertreatment component as a function of the temperature inlet signal and of the temperature outlet signal, determining a threshold value as a function of the bed temperature of the aftertreatment component and of a flow rate of exhaust gas entering the aftertreatment component, determining a NOx conversion efficiency of the aftertreatment component as a function of the NOx signal and of the NOx inlet content and determining that the aftertreatment component is degraded if the NOx conversion efficiency is below the threshold value. - View Dependent Claims (13)
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16. A system for diagnosing operation of an exhaust gas aftertreatment component for an internal combustion engine, the system comprising:
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a NOx sensor producing a NOx signal indicative of NOx content of exhaust gas exiting the aftertreatment component, and a control circuit including a memory having stored therein instructions executable by the control circuit to estimate as a function of a first set of engine operating conditions a NOx inlet content corresponding to a NOx content of exhaust gas produced by the engine and entering the aftertreatment component, to estimate as a function of a second set of engine operating conditions an exhaust flow rate corresponding to a flow rate of exhaust gas produced by the engine and flowing through the aftertreatment component, to compute as a function of the NOx inlet content and the exhaust flow rate over a first time period an accumulated inlet NOx value corresponding to an amount of NOx accumulated at the inlet of the aftertreatment component during the first time period, to compute as a function of the NOx signal and the exhaust flow rate over the first time period an accumulated outlet NOx value corresponding to an amount of NOx accumulated at the outlet of the aftertreatment component during the first time period, to determine a NOx conversion efficiency of the aftertreatment component as a function of a ratio of the accumulated outlet NOx value and the accumulated inlet NOx value, and to determine that the aftertreatment component is degraded if the NOx conversion efficiency is below a threshold value. - View Dependent Claims (17, 18, 19, 20)
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Specification