Process for the removal of particulates from the exhaust gas of an internal combustion engine

Abstract

The process includes the operations of: arranging a particular filter (PT) in the exhaust duct (EP), generating, by indicator devices (S 1 -S 5 ), electrical signals indicative of the values of parameters (NQ) of the operation of the engine (ICE); performing filter regeneration phases of the filter (PT) by controlling the injectors (I 1 -I 4 ) of the engine (ICE) in such a way as to cause a controlled increase in the temperature of the exhaust gas so as to cause combination of the particulates accumulated in the filter (PT), identifying on the basis of signals provided by at least some of the indicator devices (S 1 -S 5 ) the type of journey or trip (MPi) currently being made by the motor vehicle form among a plurality of predefined types of journey or trip (MP 1 -MP 4 ); calculating, according to a predefined estimation function, and in dependence on the instantaneous type of journey or trip (MPi), the quantity (Q) of particulates gradually accumulated in the filter (PT); and starting a filter regenerating phase of the filter (PT) when the calculated quantity (Q) of particulates accumulated in the filer (PT) exceeds a predetermined threshold.

1 . A process for the removal of particulates from the exhaust gas of an internal combustion engine, in particular a diesel engine (ICE) of a motor vehicle provided with a plurality of fuel injectors (I 1 -I 4 ) the process comprising the operations of: 
 arranging a filter (PT) in the exhaust duct (EP) of the engine (ICE) operable to retain the particulates contained in the exhaust gas;    generating, by indicator means (S 1 -S 5 ), electrical signals indicative of the values of operating parameters (NQ) of the engine (ICE);    performing, by processor and control means (PCU, ECU) filter regeneration phases of the filter (PT) by controlling the injectors (I 1 -I 4 ) of the engine (ICE) in a predetermined manner as a function of the signals provided by the said indicator means (S 1 -S 5 ) in such a way as to cause an increase in the temperature of the exhaust gas so as to cause a combustion of the particulates accumulated in the filter (PT);    the process being characterized by the operations of:    identifying, by means of the said processor and control means, (PCU, ECU) and on the basis of signals provided by at least some of the said indicator means (S 1 -S 5 ) the type of journey or trip (MPi) currently being made by the motor vehicle from among a plurality of predefined types of journey or trip (MP 1 -MP 4 );    calculating by means of the said processor and control means (PCU, ECU) and according to a predefined estimation function in dependence on the instantaneous type of journey or trip (MPi) the quantity of particulates (Q) gradually accumulated in the filter (PT); and    starting a filter regeneration phase of the filter (PT) when the calculated quantity (Q) of particulates accumulated in the filter (PT) exceeds a predetermined threshold.    
   
   
       2 . A process according to  claim 1 , in which the said threshold is determined by predetermined values according to the instantaneous type of journey or trip (MPi) of the motor vehicle.  
   
   
       3 . A process according to  claim 1 , in which 
 the said indicator means (S 1 -S 5 ) are operable to provide to the processor and control means (PCU) and (ECU) electrical signals indicative of the instantaneous values of the speed of rotation (n) of the engine (ICE) and the quantity (q) of fuel injected into the engine (ICE); and    the processor and control means (PCU, EM) are arranged to recognize the type of journey or trip (MPi) of the motor vehicle on the basis of instantaneous values of the speed of rotation (n) of the engine (ICE) and the quantity (q) of fuel injected.    
   
   
       4 . A process according to  claim 1 , in which the said processor and control means (PCU, ECU) are arranged to calculate the quantity (Q) of particulates accumulated in the filter (PT) on the basis of a predetermined function (I) indicative of the rate of accumulation of the particulates (PT) memorized for the said types journey or trip (MPi) of the motor vehicle.  
   
   
       5 . A process according to  claim 4 , in which the said function (I) indicative of the rate of accumulation is a linear function in time which is different for each type of journey or trip (MPi) of the motor vehicle.  
   
   
       6 . A process according to  claim 1 , in which the said processor and control means (PCU, ECU) are arranged to terminate. a filter regeneration phase of the filter (PT) after a predetermined working time (t*) has elapsed since commencement, which time is variable in a predetermined manner as a function of the types of journey or trip (MPi) made by the motor vehicle during regeneration.  
   
   
       7 . A process according to  claim 4 , in which the said processor and control means (PCE, ECU) are arranged to calculate, at the end of a filter regeneration phase of the filter (PT) the residual quantity of unburnt particulates in the filter (PT) as a function of the type of journey or trip made during regeneration, and to assume this residual quantity as the initial value (Q 0 ) for the calculation of the quantity (Q) of particulates accumulated in the filter starting from the end of this regeneration phase.  
   
   
       8 . A process according to  claim 7 , in which the said processor and control means (PCU, ECU) are arranged to be able to calculate, by means of a predetermined estimation function, the residual quantity of unburnt particulates (QQ) in. the filter (PT) in the case of interruption of a filter regeneration phase (PT) or when the engine (ICE) is switched off during a filter regeneration phase (PT).