Purification device for decreasing particulate matter and nitrogen oxides in diesel engine

Abstract

A diesel exhaust purification device for decreasing the amount of particulate matter and nitrogen oxides includes a Catalyzed Diesel Particulate Filter (CDPF) disposed in an exhaust conduit to capture particulate matter (PM). A differential pressure sensor detects the amount of PM contained in the CDPF. A post-injection injector is in the exhaust conduit. A Diesel Fuel Decomposition Catalyst (DFC) forms a reducing agent by decomposing the fuel injected from the post-injection injector. A nitrogen oxide adsorbing catalyst reduces nitrogen oxides accumulated therein and removes them using the reducing agent. A nitrogen oxide sensor in the exhaust conduit detects the amount of nitrogen oxides in exhaust gases. A control unit determines the regeneration time of the CDPF from signals detected by the differential pressure sensor, controls the amount of the fuel post-injected, determines the regeneration time of the nitrogen oxide adsorbing catalyst from signals detected by the nitrogen oxide sensor, controls the fuel post-injected through the post-injection injector.

1 . A purification device for decreasing particulate matter and nitrogen oxides, comprising:
 a filter disposed in an exhaust conduit to capture particulate matter;   a differential pressure sensor for detecting an amount of the particulate matter contained in said filter;   a post-injection injector disposed in the exhaust conduit to post-inject fuel;   a first catalyst for forming a reducing agent by decomposing the fuel injected from the post-injection injector;   a second catalyst for reducing nitrogen oxides accumulated therein and thus removing them using the reducing agent formed by the catalyst;   a nitrogen oxide sensor disposed in the exhaust conduit to detect an amount of nitrogen oxides contained in exhaust gases; and   a control unit for determining a regeneration time of said filter from signals detected by the differential pressure sensor and controlling an amount of the fuel post-injected through injectors of a diesel engine, and determining a regeneration time of the second catalyst from signals detected by the nitrogen oxide sensor and controlling the amount of the fuel post-injected through the post-injection injector.   
   
   
       2 . The purification device as defined in  claim 1 , wherein:
 said filter is a catalyzed diesel particulate filter;   
   
   
       3 . The purification device as defined in  claim 2 , wherein the catalyzed diesel particulate filter is directly connected to an exhaust manifold and is a closed catalyst converter type catalytic device partially provided with a diesel oxidation catalyst. 
   
   
       4 . The purification device as defined in  claim 2 , wherein the nitrogen oxide adsorbing catalyst is a catalytic device partially provided with a reducing agent forming catalyst, which forms the reducing agent by decomposing fuel. 
   
   
       5 . The purification device as defined in  claim 2 , wherein the diesel fuel decomposition catalyst is located upstream of the nitrogen oxide adsorbing catalyst on a basis of an exhaust path, and the catalyzed diesel particulate filter is located upstream of the nitrogen oxide adsorbing catalyst on a basis of an exhaust path. 
   
   
       6 . The purification device as defined in  claim 5 , wherein the catalyzed diesel particulate filter is located upstream of the diesel fuel decomposition catalyst on a basis of an exhaust path. 
   
   
       7 . The purification device as defined in  claim 5 , wherein the diesel fuel decomposition catalyst is located upstream of the catalyzed diesel particulate filter on a basis of an exhaust path. 
   
   
       8 . The purification device as defined in any one of  claims 2  to  7 , wherein the post-injection injector is located in front of the diesel fuel decomposition catalyst in an exhaust conduit. 
   
   
       9 . The purification device as defined in  claims 8 , wherein the nitrogen oxide sensor is located in front of the nitrogen oxide adsorbing catalyst in an exhaust conduit.