Exhaust gas purifying apparatus for international combustion

Abstract

An exhaust gas purifying apparatus for an internal combustion engine including an ammonia generating device and a NOx removing device. The ammonia generating device is provided in an exhaust system of the engine, and generates ammonia by a reaction of NOx and reducing components in exhaust gases when the exhaust gases are in a reducing state. The NOx removing device is provided downstream of the ammonia generating device, and adsorbs NOx in the exhaust gases when the exhaust gases are in an oxidizing state. The NOx removing device reduces the adsorbed NOx to generate ammonia and retains the generated ammonia when the exhaust gases are in the reducing state.

1 . An exhaust gas purifying apparatus for an internal combustion engine having fuel injection means for injecting fuel into at least one cylinder of said engine, said exhaust gas purifying apparatus comprising:
 ammonia generating means, provided in an exhaust system of said engine, for generating ammonia by a reaction of NOx and reducing components in exhaust gases when the exhaust gases are in a reducing state;   NOx removing means, provided downstream of said ammonia-generating means, for adsorbing NOx in the exhaust gases when the exhaust gases are in an oxidizing state, said NOx removing means reducing the adsorbed NOx to generate ammonia and retaining the generated ammonia when the exhaust gases are in the reducing state: and   reducing components supply means for supplying reducing components to an upstream side of said ammonia generating means by executing at least one post injection after a main injection through said fuel injection means.   
   
   
       2 . The exhaust gas purifying apparatus according to  claim 1 , wherein said ammonia generating means comprises a heat-resistant porous carrier and one or more of precious metals selected from the group of consisting of palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and iridium (Ir) carried by said carrier. 
   
   
       3 . An exhaust gas purifying apparatus for an internal combustion engine having at least one fuel injection valve for injection fuel into at least one cylinder of said engine, said exhaust gas purifying apparatus comprising:
 ammonia generating device, provided in an exhaust system of said engine, for generating ammonia by a reaction of NOx and reducing components in exhaust gases when the exhaust gases are in a reducing state; and   NOx removing device, provided downstream of said ammonia-generating device, for adsorbing NOx in the exhaust gases when the exhaust gases are in an oxidizing state, said NOx removing device reducing the adsorbed NOx to generate ammonia and retaining the generated ammonia when the exhaust gases are in the reducing state; and   reducing components supply device for supplying reducing components to an upstream side of said ammonia generating device by executing at least one post injection after a main injection through said at lest one fuel injection valve.   
   
   
       4 . The exhaust gas purifying apparatus according to  claim 3 , wherein said ammonia generating device comprises a heat-resistant porous carrier and one or more of precious metals selected from the group of consisting of palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), and iridium (Ir) carried by said carrier.