Method and apparatus for emissions trap regeneration

Abstract

An apparatus comprises an emissions trap and a trap regenerator fluidly coupled to the emissions trap to advance a regenerative agent thereto to regenerate the emissions trap. The trap regenerator is configured to change a concentration of the regenerative agent advanced to the emissions trap from a first trap-regenerating level to a second trap-regenerating level different from the first trap-regenerating level. An associated method is disclosed.

1 . A method of regenerating an emissions trap, comprising the steps of: 
 advancing a regenerative agent to the emissions trap for a first predetermined period of time, and    changing a concentration of the regenerative agent advanced to the emissions trap in response to expiration of the first predetermined period of time, the concentration of the regenerative agent changing from a first trap-regenerating level to a second trap-regenerating level different from the first trap-regenerating level.    
   
   
       2 . The method of  claim 1 , wherein: 
 the regenerative agent has an air-to-fuel ratio, and    the changing step comprises changing the air-to-fuel ratio from the first trap-regenerating level to the second trap-regenerating level.    
   
   
       3 . The method of  claim 2 , wherein: 
 the first trap-regenerating level is fuel rich and the second trap-regenerating level is more fuel-rich than the first trap-regenerating level, and    the advancing step comprises advancing to the emissions trap the regenerative agent with the first trap-regenerating level for the first predetermined period of time and then advancing to the emissions trap the regenerative agent with the second trap-regenerating level for a second predetermined period of time.    
   
   
       4 . The method of  claim 1 , wherein the advancing step comprises advancing to the emissions trap the regenerative agent with the first trap-regenerating level for the first predetermined period of time and then advancing to the emissions trap the regenerative agent with the second trap-regenerating level for a second predetermined period of time, further comprising releasing emissions trapped by the emissions trap at a first release rate during the first predetermined period of time and releasing emissions trapped by the emissions trap at a second release rate faster than the first release rate during the second predetermined period of time.  
   
   
       5 . The method of  claim 1 , wherein: 
 the emissions trap is a NOx trap,    the advancing step comprises advancing the first regenerative agent to the NOx trap, and    the changing step comprises changing the concentration of the regenerative agent advanced to the NOx trap from the first trap-regenerating level to the second trap-regenerating level.    
   
   
       6 . The method of  claim 1 , wherein the changing step comprises varying the position of an exhaust valve.  
   
   
       7 . The method of  claim 1 , wherein the changing step comprises varying operation of a fuel reformer.  
   
   
       8 . The method of  claim 1 , wherein the changing step comprises varying flow of air or fuel to an engine.  
   
   
       9 . An apparatus, comprising; 
 a first emissions trap, and    a trap regenerator fluidly coupled to the first emissions trap to advance a regenerative agent thereto in response to expiration of a first predetermined amount of time to regenerate the first emissions trap, the trap regenerator configured to change a concentration of the regenerative agent advanced to the first emissions trap from a first trap-regenerating level to a second trap-regenerating level different from the first trap-regenerating level.    
   
   
       10 . The apparatus of  claim 9 , wherein: 
 the regenerative agent has an air-to-fuel ratio, and    the trap regenerator is configured to change the air-to-fuel ratio of the regenerative agent advanced to the first emissions trap from the first trap-regenerating level to the second trap-regenerating level.    
   
   
       11 . The apparatus of  claim 10 , wherein: 
 the first trap-regenerating level is fuel-rich and the second trap-regenerating level is more fuel-rich than the first trap-regenerating level, and    the trap regenerator is configured to provide the first trap-regenerating level to the first emissions trap during the first predetermined period of time and to provide the second trap-regenerating level to the first emissions trap during a second predetermined period of time subsequent to the first predetermined period of time.    
   
   
       12 . The apparatus of  claim 9 , further comprising a second emissions trap flow-parallel to the first emissions trap, wherein: 
 the trap regenerator is fluidly coupled to the second emissions trap to advance the regenerative agent thereto to regenerate the second emissions trap, and    the trap regenerator is configured to change the concentration of the regenerative agent advanced to the second emissions trap from the first trap-regenerating level to the second trap-regenerating level.    
   
   
       13 . The apparatus of  claim 9 , wherein: 
 the trap regenerator comprises (i) at least one component configured to provide at least a portion of the regenerative agent, and (ii) a controller electrically coupled to the at least one component, the controller comprising (i) a processor, and (ii) a memory device electrically coupled to the processor, the memory device having stored therein a plurality of instructions which, when executed by the processor, cause the processor to:    operate the at least one component in a first mode establishing the first trap-regenerating level, and    operate the at least one component in a second mode establishing the second trap-regenerating level.    
   
   
       14 . The apparatus of  claim 13 , wherein the at least one component comprises either (1) an air valve electrically coupled to the controller and configured to control flow of air to an exhaust gas producer, or (2) a fuel injector electrically coupled to the controller and configured to control flow of fuel to an exhaust gas producer.  
   
   
       15 . The apparatus of  claim 13 , wherein the at least one component comprises a fuel reformer electrically coupled to the controller.  
   
   
       16 . The apparatus of  claim 13 , wherein the at least one component comprises a first exhaust valve electrically coupled to the controller and configured to control flow of exhaust gas to the first emissions trap.  
   
   
       17 . The apparatus of  claim 16 , further comprising a second exhaust valve electrically coupled to the controller, wherein the first exhaust valve is positioned upstream from the first emissions trap and the second exhaust valve is positioned downstream from the first emissions trap.  
   
   
       18 . The apparatus of  claim 9 , wherein the first emissions trap is a NOx trap.  
   
   
       19 . The apparatus of  claim 9 , wherein the first emissions trap is a sulfur trap.  
   
   
       20 . The apparatus of  claim 9 , wherein the first emissions trap is an ammonia trap.