Exhaust aftertreatment system with heated device

Abstract

An exhaust aftertreatment system ( 10 ) for a vehicle having an engine ( 14 ) includes a fluid passageway ( 20 ) extending from the engine to an ambient ( 18 ) for fluidly communicating exhaust gas (F), and a NOx reduction catalyst ( 28 ) disposed on the fluid passageway and downstream of the engine. An injector ( 34 ) is disposed downstream of the engine ( 14 ) and upstream of the NOx reduction catalyst ( 28 ) on the fluid passageway ( 20 ) for injecting a reductant ( 36 ) into the fluid passageway. A heated mesh device ( 44 ) is disposed on the fluid passageway downstream of the injector ( 34 ) and upstream of the NOx reduction catalyst ( 28 ). The reductant ( 36 ) that is injected from the injector ( 34 ) impinges on the heated mesh device ( 44 ).

1 ) An exhaust aftertreatment system for a vehicle having an engine, the aftertreatment system comprising:
 a fluid passageway extending from the engine to an ambient for fluidly communicating exhaust gas;   a NOx reduction catalyst disposed on the fluid passageway downstream of the engine;   an injector disposed downstream of the engine and upstream of the NOx reduction catalyst on the fluid passageway for injecting a reductant into the fluid passageway; and   a heated mesh device disposed on the fluid passageway downstream of the injector and upstream of the NOx reduction catalyst, wherein the reductant injected from the injector impinges on the heated mesh device.   
     
     
         2 ) The exhaust aftertreatment system of  claim 1  further comprising a heater that maintains a minimum temperature of the heated mesh device at a predetermined temperature. 
     
     
         3 ) The exhaust aftertreatment system of  claim 2  further comprising a sensor that senses the temperature of the heated mesh device and communicates the temperature to a control system. 
     
     
         4 ) The exhaust aftertreatment system of  claim 3  wherein when the temperature of the heated mesh device is below the predetermined temperature, the control system actuates the heater to heat the heated mesh device. 
     
     
         5 ) The exhaust aftertreatment system of  claim 2  wherein the predetermined temperature is about 200-degrees Celsius. 
     
     
         6 ) The exhaust aftertreatment system of  claim 2  wherein the heater electrically heats the heated mesh device. 
     
     
         7 ) The exhaust aftertreatment system of  claim 1  wherein the heated mesh device comprises a wire mesh portion that permits the flow of exhaust gas therethrough. 
     
     
         8 ) The exhaust aftertreatment system of  claim 7  wherein the heated mesh device further comprises a support ring that axially encloses the wire mesh portion. 
     
     
         9 ) The exhaust aftertreatment system of  claim 7  wherein the wire mesh is at least partially coated with a urea hydrolysis catalyst. 
     
     
         10 ) The exhaust aftertreatment system of  claim 1  wherein the fluid passageway is defined by a reductant pipe extending between a diesel oxidation catalyst and the NOx reduction catalyst, wherein the heated mesh device is attached to an interior surface of the reductant pipe. 
     
     
         11 ) A method of evaporating a reductant in an aftertreatment system of an engine, the method comprising:
 providing a fluid passageway from the engine to an ambient;   injecting a reductant into the fluid passageway with an injector;   impinging the reductant onto a mesh device downstream of the injector on the fluid passageway; and   heating the mesh device to a predetermined minimum temperature.   
     
     
         12 ) The method of  claim 11  further comprising the steps of sensing the temperature of the mesh device with a sensor. 
     
     
         13 ) The method of  claim 12  further comprising the steps of communicating the temperature to a control system, wherein if the temperature is below the predetermined minimum temperature, the control system actuates a heater to heat the mesh device. 
     
     
         14 ) The method of  claim 11  further comprising the step of at least partially coating the mesh device with a urea hydrolysis catalyst. 
     
     
         15 ) The method of  claim 11  wherein the fluid passageway is defined by a reductant pipe, and further comprising the step of brazing the mesh device to the reductant pipe. 
     
     
         16 ) A mesh device for an SCR system of an engine having a reductant pipe with an interior surface, the mesh device comprising:
 a wire mesh portion that permits a flow of exhaust gas therethrough;   a support ring that at least partially axially encloses the wire mesh portion, wherein the support ring is configured for attachment to the interior surface of the reductant pipe; and   a heater for heating the wire mesh portion.   
     
     
         17 ) The mesh device of  claim 16  wherein the wire mesh portion is at least partially coated with a urea hydrolysis catalyst. 
     
     
         18 ) The mesh device of  claim 16  wherein the mesh device is made of chromium, iron, nickel, and carbon. 
     
     
         19 ) The mesh device of  claim 16  wherein the wire mesh portion is a grid. 
     
     
         20 ) The mesh device of  claim 16  wherein the mesh device is heated electrically.