Late post-injection fueling strategy in a multi-cylinder diesel engine during regeneration of an exhaust after-treatment device

Abstract

A strategy for late post-injection fueling in a diesel engine ( 10 ) that can mitigate scuffing and wear due to cylinder wall washing by late post-injected fuel that is needed for regenerating an exhaust after-treatment device ( 38 ).

1 . A method of late post-injection of diesel fuel into cylinders of a multi-cylinder diesel engine for creating exhaust, which during passage through an exhaust system that includes an after-treatment device, is effective to regenerate the after-treatment device, the method comprising:
 during a series of main combustion events that occur in succession in a group of cylinders in a repetitive engine cycle for the cylinders, executing a late post-injection control strategy that causes a late post-injection of diesel fuel into at least one but fewer than all cylinders of the group.   
   
   
       2 . A method as set forth in  claim 1  wherein during a sequence of successive repetitions of the engine cycle equal in number to the number of cylinders in the group, a late post-injection of diesel fuel is made into only a single cylinder during each repetition of the engine cycle, and during the sequence no cylinder receives more than one late post-injection of diesel fuel. 
   
   
       3 . A method as set forth in  claim 2  wherein during the sequence, successive late post-fuel injections of diesel fuel are made into cylinders in the same order as the engine cycle. 
   
   
       4 . A method as set forth in  claim 1  wherein during a sequence of successive repetitions of the engine cycle equal in number to one-half the number of cylinders in the group, a late post-fuel injection of diesel fuel is made into each of multiple cylinders during each repetition of the engine cycle, and during the sequence no cylinder receives more than one late post-injection of diesel fuel. 
   
   
       5 . A method as set forth in  claim 1  wherein during a sequence of successive repetitions of the engine cycle equal in number to one-third the number of cylinders in the group, a late post-fuel injection of diesel fuel is made into each of multiple cylinders during each repetition of the engine cycle, and during the sequence no cylinder receives more than one late post-injection of diesel fuel. 
   
   
       6 . A method as set forth in  claim 1  wherein during a sequence of successive repetitions of the engine cycle equal in number to the number of cylinders in the group, a late post-injection of diesel fuel is made into each of more than one-half the number of cylinders in the group during each repetition. 
   
   
       7 . A method as set forth in  claim 6  wherein during each repetition of the engine cycle, the late post-injections of diesel fuel are made into respective cylinders in succession in the same order as the engine cycle. 
   
   
       8 . A diesel engine comprising:
 engine cylinders within which diesel fuel is combusted;   an exhaust system, including an after-treatment device, through which exhaust resulting from in-cylinder combustion passes;   a control system for controlling injection of diesel fuel into the cylinders, including main injections and late post-injections of diesel fuel, wherein the control system contains a strategy for late post-injections of diesel fuel to create exhaust suitable for regenerating the after-treatment device, and when executing the strategy, causes a late post-injection of diesel fuel into at least one but fewer than all cylinders of a group of cylinders during a series of main injections that occur in succession in the group of cylinders in a repetitive engine cycle.   
   
   
       9 . A diesel engine as set forth in  claim 8  wherein during a sequence of successive repetitions of the engine cycle equal in number to the number of cylinders in the group, execution of the strategy causes a late post-injection of diesel fuel to be made into only a single cylinder during each repetition of the engine cycle and no cylinder to receive more than one late post-injection of diesel fuel during the sequence. 
   
   
       10 . A diesel engine as set forth in  claim 9  wherein execution of the strategy during the sequence causes successive late post-fuel injections of diesel fuel to be made into respective cylinders in the same order as the engine cycle. 
   
   
       11 . A diesel engine as set forth in  claim 8  wherein during a sequence of successive repetitions of the engine cycle equal in number to one-half the number of cylinders in the group, execution of the strategy causes a late post-fuel injection of diesel fuel to be made into each of multiple cylinders during each repetition of the engine cycle and no cylinder to receive more than one late post-injection of diesel fuel. 
   
   
       12 . A diesel engine as set forth in  claim 8  wherein during a sequence of successive repetitions of the engine cycle equal in number to one-third the number of cylinders in the group, execution of the strategy causes a late post-fuel injection of diesel fuel to be made into each of multiple cylinders during each repetition of the engine cycle and during the sequence no cylinder to receive more than one late post-injection of diesel fuel. 
   
   
       13 . A diesel engine as set forth in  claim 8  wherein during a sequence of successive repetitions of the engine cycle equal in number to the number of cylinders in the group, execution of the strategy causes a late post-injection of diesel fuel to be made into each of more than one-half the number of cylinders in the group during each repetition. 
   
   
       14 . A diesel engine as set forth in  claim 13  wherein during each repetition of the engine cycle, execution of the strategy causes the late post-injections of diesel fuel to be made into respective cylinders in succession in the same order as the engine cycle.