Device for Cleaning Exhaust Gas of Internal Combustion Engine

Abstract

A device for cleaning exhaust gas of an internal combustion engine according to the present invention includes a device ( 30 ) for collecting particulate matter from exhaust gas in an exhaust gas passage ( 15 ), ozone feeding device ( 40 ) capable of feeding ozone to the device ( 30 ) for collecting particulate matter from upstream thereof, and an NOx catalyst ( 20 ) disposed upstream from the ozone feeding device ( 40 ), for cleaning NOx in the exhaust gas. Since NOx is preliminarily removed by the NOx catalyst ( 20 ) at apposition upstream from the ozone feeding device ( 40 ), the consumption of ozone due to the reaction with NOx is prevented, whereby it is possible to effectively use ozone for the purpose of oxidizing and removing PM in the device ( 30 ) for collecting particulate matter.

1 . A device for cleaning exhaust gas of an internal combustion engine, comprising
 a device for collecting particulate matter from exhaust gas in an exhaust gas passage,   ozone feeding means capable of feeding ozone to said device for collecting particulate matter from upstream thereof, and   an NOx catalyst disposed upstream from said ozone feeding means, for cleaning NOx in the exhaust gas.   
     
     
         2 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 1 , further comprising a separate ozone feeding means capable of feeding ozone to said NOx catalyst from upstream thereof. 
     
     
         3 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 2 , further comprising
 means for detecting the temperature of exhaust gas flowing into said NOx catalyst or that of a floor of the NOx catalyst, and   means for executing the feeding of ozone from the separate ozone feeding means if the detected temperature of the exhaust gas or that of the floor of said NOx catalyst is lower than a predetermined value.   
     
     
         4 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 2 , further comprising
 means disposed at a position upstream from said NOx catalyst or between said NOx catalyst and said ozone feeding means, for detecting the concentration of NOx in the exhaust gas, and   means for controlling an amount of ozone fed from said separate ozone feeding means in accordance with the detected concentration of NOx.   
     
     
         5 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 1 , further comprising an oxidation catalyst for oxidizing unburned component in the exhaust gas, disposed between said NOx catalyst and said ozone feeding means. 
     
     
         6 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 1 , further comprising an oxidation catalyst disposed at a position upstream from said NOx catalyst, for oxidizing unburned component in the exhaust gas. 
     
     
         7 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 1 , wherein said NOx catalyst is of a storage reduction type or a selective catalytic reduction type. 
     
     
         8 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 1 , further comprising means for generating ozone from gas outside said exhaust gas passage, wherein said ozone feeding means supplies ozone generated in said ozone generating means to said exhaust gas passage. 
     
     
         9 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 2 , further comprising means for generating ozone from gas outside said exhaust gas passage, and a flow rate control unit for dividing ozone delivered from said ozone generating means at a predetermined dividing ratio and feeding the same to said ozone feeding means and said separate ozone feeding means. 
     
     
         10 . The device for cleaning exhaust gas of the internal combustion engine as defined by  claim 1 , wherein said internal combustion engine is a compressive ignition type internal combustion engine or a direct injection and spark ignition type internal combustion engine.