Systems and methods for monitoring the health of a three-way catalyst

Abstract

A system includes a controller programmed to monitor an oxidation state of a three-way catalyst (TWC) assembly coupled to a combustion engine. The controller is programmed to receive signals representative of oxygen (O 2 ) concentration in a fluid both upstream of an inlet and downstream of an outlet of the TWC assembly, to receive a signal representative of the measured O 2 storage of the TWC assembly from at least one radio frequency (RF) probe disposed within the TWC assembly, to utilize a model to generate an estimated O 2 storage of the TWC assembly based at least on the O 2 concentration in the fluid both upstream and downstream of the TWC assembly, to compare the estimated O 2 storage to the measured O 2 storage, and to output a control action for the TWC assembly based at least on the comparison of the estimated O 2 storage to the measured O 2 storage.

1 . A system, comprising:
 an exhaust aftertreatment system configured to treat emissions from a combustion engine, wherein the exhaust aftertreatment system comprises:
 a three-way catalyst (TWC) assembly configured to receive a fluid from the combustion engine, wherein the TWC assembly has an inlet and an outlet; 
 a first oxygen (O 2 ) sensor disposed upstream of the inlet of the TWC assembly; 
 a second O 2  sensor disposed downstream of the outlet of the TWC assembly; and 
 at least one radio frequency (RF) probe disposed within the TWC assembly and configured to measure O 2  storage of the TWC assembly; and 
   a controller communicatively coupled to the exhaust aftertreatment system, wherein the controller is configured to receive a first signal representative of O 2  concentration in the fluid upstream of the TWC assembly from the first O 2  sensor, to receive a second signal representative of the O 2  concentration in the fluid downstream of the TWC assembly from the second O 2  sensor, to receive a third signal representative of the measured O 2  storage of the TWC assembly from the at least one RF probe, to utilize a model to generate an estimated O 2  storage of the TWC assembly based at least on the O 2  concentration in the fluid upstream of the TWC assembly and the O 2  concentration in the fluid downstream of the TWC assembly, to compare the estimated O 2  storage to the measured O 2  storage, and to output a control action for the exhaust aftertreatment system based at least on the comparison of the estimated O 2  storage to the measured O 2  storage.   
     
     
         2 . The system of  claim 1 , wherein the controller is configured to receive one or more operational parameters of the combustion engine, and to utilize the model to generate the estimated O 2  storage of the TWC assembly based on the one or more operational parameters, the O 2  concentration in the fluid upstream of the TWC assembly, and the O 2  concentration in the fluid downstream of the TWC assembly. 
     
     
         3 . The system of  claim 2 , wherein the controller is configured to utilize the model to generate both an estimated nitrogen oxides (NO X ) concentration and an estimated carbon monoxide (CO) concentration in the fluid exiting the TWC assembly based on the one or more operational parameters, the O 2  concentration in the fluid upstream of the TWC assembly, and the O 2  concentration in the fluid downstream of the TWC assembly. 
     
     
         4 . The system of  claim 3 , wherein the controller is configured to compare the estimated O 2  storage to the measured O 2  storage by determining a difference between the estimated O 2  storage and the measured O 2  storage, and determining if the difference is greater than a threshold difference. 
     
     
         5 . The system of  claim 4 , wherein the controller is configured to perform a diagnostics module for the TWC assembly if the difference is greater than the threshold difference. 
     
     
         6 . The system of  claim 5 , wherein the controller is configured to determine if the estimated NO X  concentration is within a NO X  concentration range or below a NO X  concentration threshold if the difference is less than or equal to the threshold difference. 
     
     
         7 . The system of  claim 6 , wherein the controller is configured to perform the diagnostics module for the TWC assembly if the estimated NO X  concentration is not within the NO X  concentration range or below the NO X  concentration threshold. 
     
     
         8 . The system of  claim 5 , wherein the controller is configured to determine if the estimated CO concentration is within a CO concentration range or below a CO concentration threshold if the difference is less than or equal to the threshold difference. 
     
     
         9 . The system of  claim 8 , wherein the controller is configured to perform the diagnostics module for the TWC assembly if the estimated CO concentration is not within the CO concentration range or below the CO concentration threshold. 
     
     
         10 . The system of  claim 1 , comprising the combustion engine coupled to the exhaust aftertreatment system. 
     
     
         11 . A system, comprising:
 a controller programmed to monitor an oxidation state of a three-way catalyst (TWC) assembly coupled to a combustion engine, wherein the controller is programmed to receive a first signal representative of O 2  concentration in a fluid upstream of an inlet of the TWC assembly from a first O 2  sensor, to receive a second signal representative of the O 2  concentration in the fluid downstream of an outlet of the TWC assembly from a second O 2  sensor, to receive a third signal representative of the measured O 2  storage of the TWC assembly from at least one radio frequency (RF) probe disposed within the TWC assembly, to utilize a model to generate an estimated O 2  storage of the TWC assembly based at least on the O 2  concentration in the fluid upstream of the TWC assembly and the O 2  concentration in the fluid downstream of the TWC assembly, to compare the estimated O 2  storage to the measured O 2  storage, and to output a control action for the TWC assembly based at least on the comparison of the estimated O 2  storage to the measured O 2  storage.   
     
     
         12 . The system of  claim 11 , wherein the controller is programmed to receive one or more operational parameters of the combustion engine, and to utilize the model to generate the estimated O 2  storage of the TWC assembly based on the one or more operational parameters, the O 2  concentration in the fluid upstream of the TWC assembly, and the O 2  concentration in the fluid downstream of the TWC assembly. 
     
     
         13 . The system of  claim 12 , wherein the controller is programmed to utilize the model to generate both an estimated nitrogen oxides (NO X ) concentration and an estimated carbon monoxide (CO) concentration in the fluid exiting the TWC assembly based on the one or more operational parameters, the O 2  concentration in the fluid upstream of the TWC assembly, and the O 2  concentration in the fluid downstream of the TWC assembly. 
     
     
         14 . The system of  claim 13 , wherein the controller is programmed to compare the estimated O 2  storage to the measured O 2  storage by determining a difference between the estimated O 2  storage and the measured O 2  storage, and to determine if the difference is greater than a threshold difference. 
     
     
         15 . The system of  claim 14 , wherein the controller is programmed to perform a diagnostics module for the TWC assembly if the difference is greater than the threshold difference. 
     
     
         16 . The system of  claim 15 , wherein the controller is programmed to determine if the estimated NO X  concentration is within a NO X  concentration range or below a NO X  concentration threshold if the difference is less than or equal to the threshold difference. 
     
     
         17 . The system of  claim 16 , wherein the controller is programmed to perform the diagnostics module for the TWC assembly if the estimated NO X  concentration is not within the NO X  concentration range or below the NO X  concentration threshold. 
     
     
         18 . The system of  claim 15 , wherein the controller is programmed to determine if the estimated CO concentration is within a CO concentration range or below a CO concentration threshold if the difference is less than or equal to the threshold difference. 
     
     
         19 . The system of  claim 18 , wherein the controller is programmed to perform the diagnostics module for the TWC assembly if the estimated CO concentration is not within the CO concentration range or below the CO concentration threshold. 
     
     
         20 . A method for monitoring an oxidation state of a three-way catalyst (TWC) assembly coupled to a combustion engine, comprising:
 receiving, at a controller, a first signal representative of oxygen (O 2 ) concentration in a fluid upstream of an inlet of the TWC assembly from a first O 2  sensor;   receiving, at the controller, a second signal representative of the O 2  concentration in the fluid downstream of an outlet of the TWC assembly from a second O 2  sensor;   receiving, at the controller, a third signal representative of the measured O 2  storage of the TWC assembly from at least one radio frequency (RF) probe disposed within the TWC assembly;   utilizing, via the controller, a model to generate an estimated O 2  storage of the TWC assembly based at least on the O 2  concentration in the fluid upstream of the TWC assembly and the O 2  concentration in the fluid downstream of the TWC assembly;   comparing, via the controller, the estimated O 2  storage to the measured O 2  storage; and   outputting, via the controller, a control action for the TWC assembly based at least on the comparison of the estimated O 2  storage to the measured O 2  storage.