Exhaust gas purification device for internal combustion engine

Abstract

This invention is intended to ensure that an exhaust gas purification device with an NOx storage reduction catalyst and a particulate filter is able to fully utilize an original NOx storage capability of the NOx storage reduction catalyst. For this end, in addition to the filter 40 disposed upstream relative to the NOx storage reduction catalyst 22 , the purification device includes a fuel supply element 42 for supplying a fuel so that the fuel is mixed with exhaust gas that flows into the filter, and an ozone feeder 30 for supplying ozone so that the ozone is mixed with exhaust gas that flows into the NOx storage reduction catalyst at a downstream position relative to the filter 40.

1 .- 8 . (canceled) 
   
   
       9 . An exhaust gas purification device for an internal combustion engine, comprising:
 an NOx storage reduction catalyst disposed on an exhaust passage of the internal combustion engine;   a filter disposed upstream relative to the NOx storage reduction catalyst, the filter being used to capture particulates contained in exhaust gas;   means for supplying a fuel such that the fuel will be mixed with the exhaust gas flowing into the filter; and   means for supplying ozone downstream with respect to the filter such that the ozone will be mixed with the exhaust gas flowing into the NOx storage reduction catalyst.   
   
   
       10 . The exhaust gas purification device for the internal combustion engine according to  claim 9 , further comprising:
 second means for supplying the fuel downstream with respect to the filter such that the fuel will be mixed with the exhaust gas flowing into the NOx storage reduction catalyst.   
   
   
       11 . The exhaust gas purification device for the internal combustion engine according to  claim 9 , wherein the fuel supply means is adapted to:
 during regeneration of the filter, execute fuel supply while controlling a supply quantity of the fuel such that an air-fuel ratio of the exhaust gas flowing into the filter will be lean; and   after the regeneration of the filter, continue a predetermined period of fuel supply while controlling the supply quantity of the fuel such that the air-fuel ratio of the exhaust gas flowing into the filter will be rich.   
   
   
       12 . The exhaust gas purification device for the internal combustion engine according to  claim 10 , wherein:
 during regeneration of the filter, the fuel supply means executes fuel supply while controlling a supply quantity of the fuel such that an air-fuel ratio of the exhaust gas flowing into the filter will be lean; and   during the execution of fuel supply by the fuel supply means, the second means for supplying the fuel executes a predetermined period of fuel supply while controlling a supply quantity of the fuel such that the air-fuel ratio of the exhaust gas flowing into the NOx storage reduction catalyst will be rich.   
   
   
       13 . The exhaust gas purification device for the internal combustion engine according to  claim 9 , wherein the fuel supply means executes fuel supply during the execution of ozone supply by the ozone supply means. 
   
   
       14 . The exhaust gas purification device for the internal combustion engine according to  claim 9 , wherein the fuel supply means executes fuel supply during the stoppage of ozone supply by the ozone supply means. 
   
   
       15 . The exhaust gas purification device for the internal combustion engine according to  claim 14 , wherein the fuel supply means executes fuel supply while controlling a supply quantity of the fuel such that an air-fuel ratio of the exhaust gas will be rich. 
   
   
       16 . The exhaust gas purification device for the internal combustion engine according to  claim 9 , further comprising:
 means for measuring a differential pressure between an inlet and outlet of the filter during the execution of ozone supply by the ozone supply means,   wherein the fuel supply means executes fuel supply on the basis of the measuring result of the differential pressure by the differential pressure measuring means.   
   
   
       17 . An exhaust gas purification device for an internal combustion engine, comprising:
 an NOx storage reduction catalyst disposed on an exhaust passage of the internal combustion engine;   a filter disposed upstream relative to the NOx storage reduction catalyst, the filter being used to capture particulates contained in exhaust gas;   a fuel injector supplying a fuel such that the fuel will be mixed with the exhaust gas flowing into the filter; and   an ozone feeder supplying ozone downstream with respect to the filter such that the ozone will be mixed with the exhaust gas flowing into the NOx storage reduction catalyst.