Exhaust aftertreatement system injector and control

Abstract

In one aspect, an injector assembly for injecting a fluid into an exhaust aftertreatment system is provided. The injector assembly includes a housing having an outlet orifice and an inner wall defining a passageway, the passageway fluidly coupled to the outlet orifice and configured to supply the fluid to the outlet orifice, and a valve having a longitudinal axis. The valve is oriented within the passageway and configured to translate along the longitudinal axis between a first position and a second position. A downstream end of the valve includes a tapered wall oriented at a first angle with respect to the longitudinal axis, and the housing inner wall is oriented at a second angle with respect to the longitudinal axis.

What is claimed is: 
     
         1 . An injector assembly for injecting a fluid into an exhaust aftertreatment system, the injector assembly comprising:
 a housing having an outlet orifice and an inner wall defining a passageway, the passageway fluidly coupled to the outlet orifice and configured to supply the fluid to the outlet orifice; and   a valve having a longitudinal axis, the valve oriented within the passageway and configured to translate along the longitudinal axis between a first position and a second position, wherein a downstream end of the valve includes a tapered wall oriented at a first angle with respect to the longitudinal axis, and the housing inner wall is oriented at a second angle with respect to the longitudinal axis.   
     
     
         2 . The injector assembly of  claim 1 , wherein the second angle is larger than the first angle. 
     
     
         3 . The injector assembly of  claim 1 , wherein the first and second angles are acute angles. 
     
     
         4 . The injector assembly of  claim 1 , wherein the valve further includes an end surface and the housing further includes a bottom wall, and wherein in the first position the valve is oriented such that end surface is positioned within the outlet orifice and the valve end surface is substantially coplanar with the housing bottom surface. 
     
     
         5 . The injector assembly of  claim 4 , wherein in the second position the valve is oriented such that an annular opening is defined between the valve downstream end and the housing inner wall. 
     
     
         6 . The injector assembly of  claim 5 , wherein the valve is configured to translate to a third position between the first position and the second position, and wherein in the third position the valve is oriented such that a second annular opening is defined between the valve downstream end and the housing inner wall. 
     
     
         7 . The injector assembly of  claim 6 , wherein the second annular opening is smaller than the annular opening in the second position. 
     
     
         8 . The injector assembly of  claim 1 , wherein the fluid is at least one of ammonia, urea, and hydrocarbon. 
     
     
         9 . The injector assembly of  claim 1 , wherein the fluid is urea, and further comprising a urea reservoir fluidly coupled to the passageway to supply the urea thereto. 
     
     
         10 . An exhaust aftertreatment system for an internal combustion engine, the system comprising:
 an exhaust gas conduit configured to receive exhaust gas from the internal combustion engine;   a selective catalytic reduction device disposed within the exhaust gas conduit and configured to receive the exhaust gas; and   an injector assembly coupled to the exhaust conduit and configured to inject a fluid into the exhaust gas, the injector assembly comprising:
 a housing having an outlet orifice and an inner wall defining a passageway, the passageway fluidly coupled to the outlet orifice and configured to supply the fluid to the outlet orifice; and 
 a valve having a longitudinal axis, the valve oriented within the passageway and configured to translate along the longitudinal axis between a first position and a second position, wherein a downstream end of the valve includes a tapered wall oriented at a first angle with respect to the longitudinal axis, and the housing inner wall is oriented at a second angle with respect to the longitudinal axis. 
   
     
     
         11 . The system of  claim 10 , wherein the second angle is larger than the first angle. 
     
     
         12 . The system of  claim 10 , wherein the first and second angles are acute angles. 
     
     
         13 . The system of  claim 10 , wherein the valve further includes an end surface and the housing further includes a bottom wall, and wherein in the first position the valve is oriented such that end surface is positioned within the outlet orifice and the valve end surface is substantially coplanar with the housing bottom surface, and in the second position the valve is oriented such that an annular opening is defined between the valve downstream end and the housing inner wall. 
     
     
         14 . The system of  claim 10 , wherein the fluid is urea, and further comprising a urea reservoir fluidly coupled to the passageway to supply the urea thereto. 
     
     
         15 . A method of dosing a fluid into an exhaust aftertreatment system configured to receive exhaust gas from an internal combustion engine, the method comprising:
 providing an injector assembly having a housing and a valve translatable along a longitudinal axis within the housing, the valve having a tapered wall oriented at a first angle with respect to the longitudinal axis, and the housing having an outlet orifice and an inner wall defining a passageway, the passageway fluidly coupled to the outlet orifice, and the inner wall oriented at a second angle with respect to the longitudinal axis;   providing a controller in signal communication with the injector assembly, the controller programmed to translate the valve between a closed position, a first open position, and a second open position; and   selectively injecting the fluid through the outlet orifice and into the exhaust gas.   
     
     
         16 . The method of  claim 15 , further comprising providing the injector assembly with the second angle being larger than the first angle. 
     
     
         17 . The method of  claim 15 , further comprising:
 providing a selective catalyst reduction device in the exhaust aftertreatment system downstream of the injector assembly; and   supplying urea as the fluid to the injector assembly to selectively inject urea into the exhaust gas.   
     
     
         18 . The method of  claim 15 , further comprising:
 measuring a mass flow rate of the exhaust gas in the exhaust aftertreatment system; and   selectively injecting, with the injector assembly, a predetermined amount of fluid into the exhaust gas based on the measured mass flow rate of the exhaust gas.   
     
     
         19 . The method of  claim 15 , further comprising:
 measuring a mass flow rate of the exhaust gas in the exhaust aftertreatment system;   determining, with the controller, whether the measured mass flow rate is a low mass flow rate or a high mass flow rate;   moving the valve to the first open position if the measured mass flow rate is the low mass flow rate, the first open position defining a first annular opening between a downstream end of the valve tapered wall and the housing inner wall; and   moving the valve to the second open position if the measured mass flow rate is the high mass flow rate, the second open position defining a second annular opening between the downstream end of the valve tapered wall and the housing inner wall, wherein the second annular opening is larger than the first annular opening.