Method for regenerating an exhaust gas filtering device for diesel engine and device therefor

Abstract

The invention concerns a method for regenerating a device filtering exhaust gases produced by a diesel engine, said method being of the type wherein particles, retained on a filtering means ( 22 ) of the filtering device, are burnt by the action of a combustion catalyst system. Said method consists essentially in retaining the hot exhaust gases around the filtering means ( 22 ) so as to feed to the particles, at least part of the heat energy required for their combustion and in burning said particles to regenerate the filtering device. The invention also concerns a device for implementing the method, comprising a means for producing a combustion catalyst ( 20 ), a filtering means ( 22 ) of exhaust gases and a diesel oil injecting means, the means for producing a combustion catalyst and filtering means being contained in a reaction chamber ( 18 ).

1 - 19 . (Canceled)  
   
   
       20 . A method for regeneration of a device for filtering the exhaust gases produced by a diesel engine in which particles retained on a filtration means of said filtration device are burnt through the action of a combustion catalyst, comprising retaining the hot exhaust gases around the filtration means in order to provide the particles with at least some of the heat energy necessary for their combustion, and burning said particles with at least some of the heat energy necessary for their combustion, so as to regenerate the filtration device.  
   
   
       21 . The method of  claim 20 , further comprising: 
 employing a combustion catalyst production means in the filtration device,    measuring a temperature θ m  in the vicinity of the combustion catalyst production means,    comparing θ m  with a temperature θ r  corresponding to the temperature at which the combustion of diesel fuel in the presence of the combustion catalyst is complete,    if θ m  is greater than or equal to θ r , initiating post-injection of diesel fuel through an injection means into the filtration device for a determined period of time, so as to cause a temperature rise of the particles in order to permit their combustion.    
   
   
       22 . The method of  claim 21 , further comprising: 
 measuring a pressure P m  in the vicinity of the combustion catalyst production means, said pressure P m  reflecting the degree of obstruction of the filtration means by the particles,    measuring the temperature θ m ,    comparing said pressure P m  with a reference pressure P r  corresponding to the maximum acceptable degree of obstruction,    comparing θ m  with θ r  if P m  is greater than or equal to the pressure P r ,    initiating the post-injection of diesel fuel if θ m  is greater than or equal to θ r .    
   
   
       23 . A device for carrying out the regeneration method of  claim 20 , comprising a combustion catalyst production means, a means for filtration of said exhaust gases downstream of said combustion catalyst production means, and a means for injection of diesel fuel upstream of said combustion catalyst production means, said combustion catalyst production means and filtration means being contained in a reaction enclosure along the flow path of the exhaust gases produced by an engine.  
   
   
       24 . The device of  claim 23 , wherein said filtration means, comprising a set of filtering units and is exposed in a chamber for receiving the exhaust gases, with said exhaust gases heating said filtering units.  
   
   
       25 . The devise of  claim 24 , wherein said filtration means comprises at least two particle filters having a body, formed by the filtering units which are connected together by a joint, and a metal casing.  
   
   
       26 . The device of  claim 23 , wherein said means for injection of diesel fuel communicates with a line for discharging the exhaust gases.  
   
   
       27 . The device of  claim 23 , wherein said means for injection comprises a diesel fuel reservoir and a chamber for injecting the diesel fuel contained in said reservoir into the discharge line.  
   
   
       28 . The device of  claim 27 , wherein said chamber is supplied, on the one hand, with diesel fuel through a first line connecting it to said reservoir and, on the other hand, with compressed air through a second line connecting it to the engine, said chamber having an orifice through which the diesel fuel is injected into said filtration device.  
   
   
       29 . The device of  claim 23 , further comprising an electroinc control module.  
   
   
       30 . The device of  claim 23 , further comprising at least one temperature sensor, placed inside said enclosure and adapted to measure the temperature θ m  in its interior.  
   
   
       31 . The device of  claim 23 , further comprising at least one pressure sensor, placed inside said enclosure and adapted to measure the pressure P m  in its interior.  
   
   
       32 . The device of  claim 30 , wherein the electronic control module is connected to a temperature sensor and to a pressure sensor, and compares the respectively measured values of θ m  and optionally P m  with the reference values θ r  and optionally P r , and initiates the injection of diesel fuel into the discharge line through said injection system when the measurements θ m  and optionally P m  are greater than or equal to the reference values θ r  and optionally P r .  
   
   
       33 . The device of  claim 32 , wherein the lines supplying the chamber of the injection system with diesel fuel and compressed air each have a solenoid valve controlled by the electronic control module, opening of the solenoid valves leading to the intake of diesel fuel and compressed air into the chamber and therefore to the injection of diesel fuel into the exhaust gas discharge line.  
   
   
       34 . The device of  claim 28 , wherein the chamber of the injection system is provided with a nozzle in front of the orifice, making it possible to inject the diesel fuel in a nebulized form into the gas discharge line.  
   
   
       35 . The device of  claim 24 , wherein the filtering units preferably consist of silicon carbide or any other equivalent material whose structure is of a honeycomb type.  
   
   
       36 . The device of  claim 23 , wherein the combustion catalyst production means comprises at least one cartridge based on platinum or any equivalent material that catalyzes the conversion of the nitrogen monoxide (NO) contained in the exhaust gases into nitrogen dioxide (NO 2 ), the NO 2  which is produced catalyzing the combustion reaction of the particle clogging the filter.  
   
   
       37 . The device of  claim 23 , wherein the capacity of the second reservoir is preferably equivalent to the maximum volume of diesel fuel injected during the post-injection.  
   
   
       38 . The device of  claim 25 , wherein the particle filters are placed in parallel in the enclosure.