System, apparatus, and methods for performing a quality diagnostic of an aqueous urea solution

Abstract

System, apparatus, and methods are disclosed for enabling a quality diagnostic of an aqueous urea solution (AUS) of an exhaust system when the AUS is outgassed. Systems, apparatus, and methods are also disclosed for disabling an output of a quality condition of the AUS in response at least in part to detecting that an AUS fill event of an AUS storage tank has occurred.

What is claimed is: 
     
         1 . A method, comprising:
 determining that an aqueous urea solution (AUS) confined in a storage tank that is connected to an exhaust system is outgassed;   in response to the determining the AUS is outgassed, performing an AUS diagnostic comprising operating a quality sensor to determine a urea concentration of the AUS;   wherein the operating the urea quality sensor comprises ultrasonically determining a fluid density of the AUS.   
     
     
         2 . The method of  claim 1 , further comprising, in response to determining the AUS is not outgassed, disabling the performing the AUS diagnostic. 
     
     
         3 . The method of  claim 2 , further comprising, in response to determining the AUS is not outgassed, operating a heater to increase a temperature of the AUS. 
     
     
         4 . The method of  claim 3 , wherein the operating the heater comprises heating the AUS according to at least one operation selected from the operations consisting of: heating the AUS for at least 30 minutes, heating the AUS to a temperature rise of at least 30° C., and heating the AUS to a temperature of at least 45° C. 
     
     
         5 . The method of  claim 3 , wherein the operating the heater comprises opening a heat exchange valve in a heat exchange system that receives heat from operation of an internal combustion engine. 
     
     
         6 . The method of  claim 1 , wherein the determining that the AUS confined in the storage tank is outgassed comprises determining whether the AUS has experienced a sufficient temperature rise since a most recent AUS fill event of the storage tank, wherein the sufficient temperature rise comprises at least one event selected from the events consisting of: being heated for at least 30 minutes, being heated to a temperature at least 30° C. above a fill temperature, and being heated to a temperature of at least 45° C. 
     
     
         7 . A method, comprising:
 detecting a fill event of a storage tank for storing an aqueous urea solution (AUS);   disabling a quality diagnostic of the AUS after detecting the fill event; and   outgassing the AUS before enabling the quality diagnostic.   
     
     
         8 . The method of  claim 7 , after outgassing the AUS, performing an AUS diagnostic comprising operating a quality sensor to determine a urea concentration of the AUS;
 wherein the operating the urea quality sensor comprises ultrasonically determining a fluid density of the AUS.   
     
     
         9 . The method of  claim 8 , wherein outgassing the AUS includes at least one operation selected from the operations consisting of: heating the AUS for at least 30 minutes, heating the AUS to a temperature rise of at least 30° C., and heating the AUS to a temperature of at least 45° C. 
     
     
         10 . The method of  claim 8 , wherein heating the AUS comprises opening a heat exchange valve of a heat exchange circuit to circulate a heat exchange fluid that is heated by operation of an internal combustion engine to the storage tank. 
     
     
         11 . The method of  claim 7 , wherein detecting the fill event comprises determining whether an AUS level in the storage tank has increased since a last known fill level detection. 
     
     
         12 . An apparatus, comprising:
 an electronic controller connected to an aqueous urea solution (AUS) storage tank level sensor and an AUS quality sensor associated with an AUS storage tank for providing AUS to an exhaust system, wherein the controller is further connected to a heating device and includes:   a storage tank level determination module configured to detect a fill event of AUS in the storage tank;   a quality determination module configured to determine a quality of the AUS in the storage tank and output a quality condition associated with the quality of the AUS; and   an AUS outgassing module configured to disable output of the quality condition by the quality determination module upon the detection of the fill event by the storage tank level determination module, where the AUS outgassing module is further configured to control the heating device to increase a temperature of the AUS a predetermined amount before enabling output of the quality condition by the quality determination module.   
     
     
         13 . The apparatus of  claim 12 , wherein the heating device includes a heat exchange circuit that provides a flow of heating fluid to the storage tank for heating of the AUS. 
     
     
         14 . The apparatus of  claim 12 , wherein the quality determination module is configured to output to a display an indication of the AUS quality. 
     
     
         15 . A system, comprising:
 an internal combustion engine including an exhaust system;   a dosing system connected to the exhaust system to provide an aqueous urea solution (AUS) to the exhaust system;   a storage tank for storing AUS connected to the dosing system, wherein the storage tank includes a level sensor operable to indicate a level of AUS in the storage tank, a quality sensor operable to indicate a quality condition of the AUS in the storage tank, and a temperature sensor operable to indicate a temperature of the AUS in the storage tank;   a heat exchange system configured to heat the AUS; and   a controller connected to the heat exchange system that is operable to control heating of the AUS in the storage tank, wherein the controller is configured to suspend an output of the indication of the quality condition of the AUS and increase a temperature of the AUS a predetermined amount in response at least in part to an indication from the level sensor that the level of AUS in the storage tank has increased.   
     
     
         16 . The system of  claim 15 , wherein the heat exchange system defines a flow path that is arranged to circulate a heat exchange fluid to thermally contact heated heat exchange fluid with the AUS in the storage tank, wherein the heat exchange system further includes a control valve in the flow path to control a flow of the heat exchange fluid in the flow path. 
     
     
         17 . The system of  claim 16 , wherein the controller is configured to initiate a circulation period of the heated heat exchange fluid in the flow path through the storage tank to increase the temperature of the AUS in the storage tank the predetermined amount. 
     
     
         18 . The system of  claim 17 , wherein the predetermined amount includes at least one of the AUS being heated to a temperature threshold, an increase in temperature of the AUS by a predetermined amount, and a heating the AUS at a predetermined temperature for a length of time.