Continuously regenerating particulate filter for internal combustion engine

Abstract

An internal combustion engine system having a non-catalyzed particulate filter receiving products of combustion at a temperature of frequently above 600° C. and an excess of oxygen of between 0.5 and 0.8% from a stoichiometric diesel engine. A NO x reduction catalyst is positioned downstream of the particulate filter. The engine system may include a turbocharger and the particulate filter and NO x reduction catalyst may be positioned either upstream of the turbine or downstream of the turbine or alternatively the particulate filter upstream of the turbine and the NO x reduction catalyst downstream of the turbine.

1 . An internal combustion engine system comprising:
 an internal combustion engine having an air intake and an exhaust for products of combustion, said products of combustion having an excess of oxygen and a temperature frequently greater than approximately 600° C.;   a non-catalyzed particulate filter receiving products of combustion from said exhaust; and   a NO x  reduction catalyst downstream from and receiving fluid from said particulate filter.   
   
   
       2 . An internal combustion engine system as claimed in  claim 1 , wherein said internal combustion engine is a stoichiometric diesel engine. 
   
   
       3 . An internal combustion engine system as claimed in  claim 2 , wherein said excess oxygen is up to approximately 0.8%. 
   
   
       4 . An internal combustion engine system as claimed in  claim 3 , wherein said excess oxygen is between approximately 0.5 and 0.8%. 
   
   
       5 . An internal combustion engine system as claimed in  claim 1 , further comprising a pressurizing device including a turbine receiving the exhaust products of combustion to drive a compressor. 
   
   
       6 . An internal combustion engine system as claimed in  claim 5 , wherein said particulate filter and NO x  reduction catalyst are positioned downstream from and receiving fluid from said turbine. 
   
   
       7 . An internal combustion engine system as claimed in  claim 5 , wherein said particulate filter is upstream of said turbine and said NO x  reduction catalyst is downstream of said turbine. 
   
   
       8 . An internal combustion engine system as claimed in  claim 5 , wherein said particulate filter and said NO x  reduction catalyst are positioned upstream of said turbine. 
   
   
       9 . An internal combustion engine system as claimed in  claim 1 , wherein said particulate filter is a ceramic filter. 
   
   
       10 . An internal combustion engine system as claimed in  claim 1 , wherein said NO x  reduction catalyst is a three-way catalyst. 
   
   
       11 . A method of operating an internal combustion engine system comprising the steps of:
 operating an air breathing, fuel consuming internal combustion engine to produce products of combustion on an exhaust with a temperature frequently greater than approximately 600° C. and an excess of oxygen;   passing said products of combustion through a non-catalyzed particulate filter; and subsequently passing said products of combustion over a NO x  reduction catalyst.   
   
   
       12 . A method as claimed in  claim 11 , wherein said internal combustion engine is a stoichiometric diesel. 
   
   
       13 . A method as claimed in  claim 11 , wherein said excess of oxygen is up to approximately 0.8%. 
   
   
       14 . A method as claimed in  claim 13 , wherein said excess oxygen is between approximately 0.5 and 0.8%. 
   
   
       15 . A method as claimed in  claim 11 , wherein said engine is operated with a pressurizing device including a turbine receiving the products of combustion from said engine to drive a pressurizing device. 
   
   
       16 . A method as claimed in  claim 15 , wherein said products of combustion are passed through said non-catalyzed particulate filter and said NO x  reduction catalyst downstream of said turbine. 
   
   
       17 . A method as claimed in  claim 15 , wherein said products of combustion are passed through said non-catalyzed particulate filter upstream of said turbine and said products of combustion are passed over said NO x  reduction catalyst downstream of said turbine. 
   
   
       18 . A method as claimed in  claim 15 , wherein said products of combustion are passed through said non-catalyzed particulate filter and said NO x  reduction catalyst downstream of said turbine. 
   
   
       19 . A method as claimed in  claim 15 , wherein said particulate filter is a ceramic filter. 
   
   
       20 . A method as claimed in  claim 15 , wherein said NO x  reduction catalyst is a three-way catalyst.