System and method for regenerating a diesel particulate filter in a motor vehicle while parked

Abstract

A system and method for initiation and control of passive regeneration ( 38, 38 B) of a diesel particulate filter ( 34 ), and the integration of that regeneration strategy with an active regeneration strategy ( 36 ) and a strategy ( 40, 40 A, 40 B) for inhibiting passive regeneration. Passive regeneration can be initiated by driver actuation of an instrument panel switch while the vehicle is parked with the engine idling provided that certain conditions confirming that the vehicle is parked and the engine is at proper temperature are satisfied. Control of passive regeneration includes a timing function that sets minimum and maximum times.

1 . A diesel engine comprising:
 an exhaust system through which exhaust gases created by combustion in combustion chambers pass to atmosphere and which comprises an after-treatment device that treats the gases before leaving the exhaust system but that at times requires regeneration by elevation of temperature of the gases to a regeneration temperature range;   an engine control system for processing various data to control various aspects of engine operation for conditioning the gases to cause regeneration of the after-treatment device;   wherein the control system comprises a first regeneration strategy for conditioning the gases to cause oxygen-based regeneration of the after-treatment device and a second regeneration strategy for conditioning exhaust gases to cause nitrogen dioxide-based regeneration of the after-treatment device when the engine is operating at low idle speed in accordance with a low idle speed control strategy.   
   
   
       2 . A diesel engine as set forth in  claim 1  wherein the control system comprises a strategy for selectively inhibiting one of the regeneration strategies. 
   
   
       3 . A diesel engine as set forth in  claim 2  wherein the strategy for selectively inhibiting one of the regeneration strategies comprises a strategy for inhibiting the first regeneration strategy from being used when the after-treatment device is being regenerated by the second regeneration strategy. 
   
   
       4 . A diesel engine as set forth in  claim 1  comprising a regeneration-initiation input to the control system for initiating regeneration of the after-treatment device by the second regeneration strategy. 
   
   
       5 . A diesel engine as set forth in  claim 4  wherein the control system comprises a timing function that once regeneration of the after-treatment device by the second regeneration strategy has been initiated, provides for nitrogen dioxide-based regeneration of the after-treatment device to continue for at least as long as a selected minimum time limit. 
   
   
       6 . A diesel engine as set forth in  claim 5  wherein the control system comprises an additional control that is effective, once nitrogen dioxide-based regeneration of the after-treatment device has continued for at least the minimum time limit, to terminate the on-going regeneration upon the first to occur of a) disclosure that the after-treatment device has been regenerated sufficiently to no longer require regeneration and b) a selected maximum time limit. 
   
   
       7 . A diesel engine as set forth in  claim 4  comprising additional inputs to the control system that are used by the control system, once regeneration by the second regeneration strategy has been initiated, to condition nitrogen dioxide-based regeneration of the after-treatment device on satisfaction of certain conditions precedent to such initiation. 
   
   
       8 . A diesel engine as set forth in  claim 1  wherein the control system comprises a first set of data values for set-points of certain engine parameters used by the control system to cause oxygen-based regeneration of the after-treatment device, and a second set of data values for set-points of those certain engine parameters used by the control system to cause nitrogen dioxide-based regeneration of the after-treatment device. 
   
   
       9 . A diesel engine as set forth in  claim 8  wherein the certain engine parameters include one or more of engine idle speed, main fuel injection timing, EGR valve position, turbocharger vane position, intake throttle position, post-fuel injection quantity, and post-injection fuel timing. 
   
   
       10 . A diesel engine as set forth in  claim 1  further including a wheeled motor vehicle that is propelled by the engine, and comprising inputs to the control system that are used by the control system to condition initiation of nitrogen dioxide-based regeneration of the after-treatment device by a regeneration-initiation input to the control system on satisfaction of certain conditions precedent to such initiation, including a condition of a regeneration-initiation device being operated, a condition of the vehicle being stationary, and a condition of engine temperature sufficiently high to initiate nitrogen dioxide-based regeneration. 
   
   
       11 . A diesel engine as set forth in  claim 10  wherein the strategy for selectively inhibiting one of the regeneration strategies comprises inhibiting the first regeneration strategy from being used when the after-treatment device is being regenerated by the second regeneration strategy. 
   
   
       12 . A diesel engine as set forth in  claim 10  wherein the after-treatment device comprises a diesel particulate filter that requires regeneration to burn off trapped diesel particulate matter. 
   
   
       13 . A method for regenerating an exhaust after-treatment device in an exhaust system of a diesel engine, the method comprising:
 operating the engine to create exhaust gases for causing nitrogen dioxide-based regeneration of the after-treatment device upon concurrence of conditions precedent that include a regeneration-initiation device for initiating such a regeneration being in a condition for initiating such a regeneration, the engine operating at a low idle speed in accordance with a low idle speed control strategy, and engine temperature condition being sufficiently high to initiate nitrogen dioxide-based regeneration.   
   
   
       14 . A method as set forth in  claim 13  wherein the engine propels a wheeled motor vehicle, and the method comprises operating the engine to create exhaust gases for causing nitrogen dioxide-based regeneration of the after-treatment device upon the condition of the vehicle being stationary being a further condition precedent for causing nitrogen dioxide-based regeneration of the after-treatment device. 
   
   
       15 . A diesel engine comprising:
 an exhaust system through which exhaust gases created by combustion in combustion chambers pass to atmosphere and which comprises an after-treatment device that treats the gases before leaving the exhaust system but that at times requires regeneration by elevation of temperature of the gases to a regeneration temperature range;   an engine control system for processing various data to control various aspects of engine operation for conditioning the gases to cause regeneration of the after-treatment device;   wherein the control system comprises a regeneration strategy for conditioning exhaust gases to cause nitrogen dioxide-based regeneration of the after-treatment device when the engine is operating at low idle speed in accordance with a low idle speed control strategy.   
   
   
       16 . A diesel engine as set forth in  claim 15  further including a wheeled motor vehicle that is propelled by the engine, and comprising inputs to the control system that are used by the control system to condition initiation of nitrogen dioxide-based regeneration of the after-treatment device by a regeneration-initiation input to the control system on satisfaction of certain conditions precedent to such initiation, including a condition of a regeneration-initiation device being operated, a condition of the vehicle being stationary, and a condition of engine temperature sufficiently high to initiate nitrogen dioxide-based regeneration.