Reductant Quality Sensor

Abstract

A control system for reducing nitrogen oxides in engine exhaust includes an emissions catalyst having an inlet adapted to receive an exhaust from the engine. A reductant tank is configured to store a reductant. An injector is in fluid communication with the reductant tank and is operable to inject the reductant into the exhaust upstream of the catalyst. A sensor is in fluid communication with the reductant and outputs a reductant quality signal based on the reductant. A controller determines a reductant quality of the reductant based on the reductant quality signal and outputs a dosing rate signal based on the reductant quality. The injector alters a dosing rate of the reductant based on the dosing signal.

1 . A control system for reducing nitrogen oxides in engine exhaust, the system comprising:
 an emissions catalyst having an inlet adapted to receive an exhaust from the engine;   a reductant tank to store a reductant;   an injector in fluid communication with the reductant tank and operable to inject the reductant into the exhaust upstream of the catalyst;   a sensor in fluid communication with the reductant and that outputs a reductant quality signal based on a composition of the reductant; and   a controller that determines a reductant quality of the reductant based on the reductant quality signal and that outputs a dosing rate signal based on the reductant quality;   wherein the injector injects the reductant at a dosing rate based on the dosing rate signal.   
     
     
         2 . The control system of  claim 1  wherein the reductant quality comprises an ethanol content of the reductant. 
     
     
         3 . The control system of  claim 2  wherein the controller outputs a signal to a driver information display based on a determined ethanol content that is outside of a predetermined range. 
     
     
         4 . The control system of  claim 2  wherein the dosing rate signal corresponds to an increased reductant dosing rate for a determined ethanol content that is below a predetermined value. 
     
     
         5 . The control system of  claim 2  wherein the dosing rate signal corresponds to a reduced reductant dosing rate for a determined ethanol content that is above a predetermined value. 
     
     
         6 . The control system of  claim 1  wherein the controller determines the reductant quality based on a reductant volume increase in the reductant tank. 
     
     
         7 . The control system of  claim 1  wherein the reductant comprises a fuel including one of E85, E95, B5, B10 and B20. 
     
     
         8 . A method for reducing nitrogen oxides in an exhaust stream of an engine, the method comprising:
 injecting a reductant through an injector and into an exhaust conduit that passes the exhaust stream;   determining a quality of the reductant;   determining a dosing rate based on the quality;   communicating a dosing signal to the injector based on the dosing rate; and   altering the dosing rate of the reductant based on the dosing signal.   
     
     
         9 . The method of  claim 8  wherein determining the quality of the reductant comprises:
 communicating a reductant quality signal from a sensor in fluid communication with the reductant to a controller; and 
 determining an ethanol content of the reductant based on the reductant quality signal. 
 
     
     
         10 . The method of  claim 9  wherein altering the dosing rate of the reductant comprises:
 communicating a dosing rate signal to an injector that is in fluid communication with the reductant and the exhaust conduit; and 
 injecting reductant into the exhaust conduit based on the dosing rate signal. 
 
     
     
         11 . The method of  claim 10  wherein altering the dosing rate of the reductant comprises:
 increasing the dosing rate in response to a determined ethanol content below a predetermined value. 
 
     
     
         12 . The method of  claim 10  wherein altering the dosing rate of the reductant comprises:
 decreasing the dosing rate in response to a determined ethanol content above a predetermined value. 
 
     
     
         13 . The method of  claim 9  further comprising:
 communicating a fault signal to a driver information display based on the determined ethanol content being outside of a predetermined range. 
 
     
     
         14 . The method of  claim 9 , further comprising:
 determining a volume of reductant in a reductant tank; and   determining the ethanol content of the reductant based on a determination of an increase in reductant volume above a threshold.   
     
     
         15 . The method of  claim 9 , further comprising:
 determining whether the engine has started; and   determining the ethanol content of the reductant based on a determination that the engine has started.   
     
     
         16 . The method of  claim 8  wherein injecting the reductant comprises:
 injecting a fuel including one of E85, E95, B5, B10 and B20. 
 
     
     
         17 . A method for reducing nitrogen oxides in an exhaust stream of an engine, the method comprising:
 determining an ethanol content of the reductant;   communicating a fault signal to a driver information display based on the determined ethanol content being outside of a predetermined range; and   injecting a reductant with an injector into an exhaust conduit that passes the exhaust stream based on the ethanol content being within the predetermined range;   communicating a dosing rate signal to the injector that is in fluid communication with the reductant and the exhaust conduit;   increasing the dosing rate of the reductant injected by the injector in response to a dosing rate signal corresponding to an ethanol content below a predetermined value; and   decreasing the dosing rate of the reductant injected by the injector in response to a dosing rate signal corresponding to an ethanol content above a predetermined value.   
     
     
         18 . The method of  claim 17 , further comprising:
 determining a volume of reductant in a reductant tank; and   determining the ethanol content of the reductant based on a determination of an increase in reductant volume above a threshold.   
     
     
         19 . The method of  claim 17 , further comprising:
 determining whether the engine has started; and   determining the ethanol content of the reductant based on a determination that the engine has started.   
     
     
         20 . The method of  claim 17  wherein injecting the reductant comprises:
 injecting a fuel including one of E85, E95, B5, B10 and B20.