Burner With Air-Assisted Fuel Nozzle And Vaporizing Ignition System

Abstract

An exhaust aftertreatment system includes a burner in heat transfer relation with exhaust gas in an exhaust gas passageway. The burner includes a housing assembly and a nozzle assembly, the housing assembly at least partially defining a combustion chamber. The nozzle assembly is at least partially received in the housing assembly and includes a nozzle body and an electric heating element. The heating element is disposed within the nozzle body and operable to heat fuel flowing through the nozzle body. A control module is in communication with the heating element and controls the heating element in a first mode in which the heating element heats fuel for combustion in the combustion chamber, and a second mode in which the heating element burns deposits off of the nozzle body when fuel is not supplied to the nozzle body.

What is claimed is: 
     
         1 . An exhaust aftertreatment system comprising:
 a burner in heat transfer relation with exhaust gas in an exhaust gas passageway, the burner including a housing assembly and a nozzle assembly, the housing assembly at least partially defining a combustion chamber, the nozzle assembly being at least partially received in the housing assembly and including a nozzle body and an electric heating element, the heating element being disposed within the nozzle body and operable to heat fuel flowing through the nozzle body; and   a control module in communication with the heating element and controlling the heating element in a first mode in which the heating element heats fuel for combustion in the combustion chamber and a second mode in which the heating element burns deposits off of the nozzle body when fuel is not supplied to the nozzle body.   
     
     
         2 . The exhaust aftertreatment system of  claim 1 , wherein the control module controls the heating element in the first mode to heat the fuel to a temperature at or above a temperature at which the fuel will spontaneously ignite in response to exposure to air. 
     
     
         3 . The exhaust aftertreatment system of  claim 2 , wherein the control module controls the heating element in a third mode in which the heating element preheats the fuel in the first mode such that fuel discharged from the nozzle assembly in the first mode is passively vaporized in the combustion chamber. 
     
     
         4 . The exhaust aftertreatment system of  claim 1 , wherein the heating element preheats the fuel in the first mode such that fuel discharged from the nozzle assembly in the first mode is passively vaporized in the combustion chamber. 
     
     
         5 . The exhaust aftertreatment system of  claim 1 , wherein the control module monitors a temperature of the heating element and adjusts a pulse width modulation duty cycle applied to the heating element based on the temperature. 
     
     
         6 . The exhaust aftertreatment system of  claim 5 , wherein the control module monitors an electrical resistance of the heating element and determines the temperature of the heating element based on the electrical resistance. 
     
     
         7 . The exhaust aftertreatment system of  claim 1 , wherein the heating element includes a glow plug. 
     
     
         8 . The exhaust aftertreatment system of  claim 1 , wherein the body includes first and second cavities, a fuel inlet passage and an air inlet passage and extending into the interior volume, the first cavity receiving at least a portion of the heating element and being in fluid communication with the fuel inlet passage and a fuel discharge passage such that fuel from the fuel inlet passage is heated in the first cavity by the heating element and discharged from the first cavity through the fuel discharge passage, the second cavity being in fluid communication with the air inlet passage and an air discharge passage, the first and second cavities being fluidly isolated from each other and supplying fuel and air, respectively, to an exit aperture disposed downstream of the fuel discharge aperture and the air discharge aperture. 
     
     
         9 . The exhaust aftertreatment system of  claim 8 , wherein the second cavity is an annular cavity that surrounds at least a portion of the first cavity. 
     
     
         10 . The exhaust aftertreatment system of  claim 8 , wherein an inner surface of the first cavity cooperates with the heating element to form an annular fuel passageway therebetween. 
     
     
         11 . The exhaust aftertreatment system of  claim 8 , wherein the first cavity includes a tapered portion adjacent the fuel discharge aperture. 
     
     
         12 . The exhaust aftertreatment system of  claim 8 , wherein the second cavity is in fluid communication with a plurality of air discharge apertures arranged in a circular array. 
     
     
         13 . The exhaust aftertreatment system of  claim 8 , wherein the body of the nozzle assembly includes a main body portion, an outer nozzle body and an inner nozzle body, the main body portion including a central aperture and a recess, the heating element being fixedly received in the recess, the inner nozzle body being fixedly received in the central aperture, and wherein the first cavity is formed in the inner nozzle body and is in fluid communication with the recess. 
     
     
         14 . The exhaust aftertreatment system of  claim 13 , wherein the inner nozzle body is received in the outer nozzle body such that the inner nozzle body and the outer nozzle body cooperate to form the second cavity. 
     
     
         15 . The exhaust aftertreatment system of  claim 14 , wherein the fuel discharge aperture and the air discharge apertures are formed in a head portion of the inner nozzle body. 
     
     
         16 . The exhaust aftertreatment system of  claim 15 , wherein the nozzle assembly includes a cap member at least partially received in the outer nozzle body and retaining the inner nozzle body relative to the outer nozzle body, and wherein the exit aperture is formed in the cap member. 
     
     
         17 . The exhaust aftertreatment system of  claim 15 , wherein the fuel inlet passage and the air inlet passage are formed in the main body portion. 
     
     
         18 . The exhaust aftertreatment system of  claim 17 , wherein the outer nozzle body is received in another recess in the main body portion.