Exhaust gas treatment apparatus

Abstract

An exhaust gas treatment apparatus 1 a of the present invention includes: a tubular body 10, a discharge electrode 12 disposed inside the tubular body 10, and a stick-shaped dust collection electrode 14. The number of the particulates 22 suspended in the exhaust gas 20 is decreased by charging the particulate matter 22 contained in the exhaust gas passing through the tubular body 10 by corona discharge 24 caused by the discharge electrode 12, collecting the charged particulate matter 22 a on the inner wall face 10 a of the tubular body 10 by the electric field 26 generated by the dust collection electrode 14 to agglomerate the particulate matter 22 a, and allowing the agglomerated particulate matter 22 b to scatter again.

What is claimed is: 
     
         1 . An exhaust gas treatment apparatus comprising:
 a tubular body functioning as a flow passage where exhaust gas passes,   a discharge electrode disposed in an central portion in a cross section perpendicular to a flow direction of the flow passage inside the tubular body and causing corona discharge in the vicinity thereof by applying a voltage, and   a stick-shaped dust collection electrode disposed over the range of a length of at least twice the inner diameter of the tubular body along the central axial direction of the flow passage on the downstream side of the discharge electrode in the flow passage and generating an electric field from the central axis of the flow passage to an inner wall face of the tubular body;   wherein the number of particulates suspended in the exhaust gas is decreased by charging the particulate matter contained in the exhaust gas passing through the tubular body by corona discharge caused by the discharge electrode, collecting the charged particulate matter on the inner wall face of the tubular body by the electric field generated by the dust collection electrode to agglomerate the plural particulates, and allowing the agglomerated particulates to scatter again.   
     
     
         2 . The exhaust gas treatment apparatus according to  claim 1 , wherein the length in the central axial direction of the flow passage of the dust collection electrode is within the range of twice to five times the inner diameter of the tubular body. 
     
     
         3 . The exhaust gas treatment apparatus according to  claim 1 , wherein the discharge electrode has a disc-like electrode support disposed perpendicularly to the flow direction of the flow passage and a needle-like discharger disposed perpendicularly to the electrode support. 
     
     
         4 . The exhaust gas treatment apparatus according to  claim 2 , wherein the discharge electrode has a disc-like electrode support disposed perpendicularly to the flow direction of the flow passage and a needle-like discharger disposed perpendicularly to the electrode support. 
     
     
         5 . The exhaust gas treatment apparatus according to  claim 1 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to one of the discharge electrode and the dust collection electrode to apply a voltage on each of the electrodes. 
     
     
         6 . The exhaust gas treatment apparatus according to  claim 2 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to one of the discharge electrode and the dust collection electrode to apply a voltage on each of the electrodes. 
     
     
         7 . The exhaust gas treatment apparatus according to  claim 3 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to one of the discharge electrode and the dust collection electrode to apply a voltage on each of the electrodes. 
     
     
         8 . The exhaust gas treatment apparatus according to  claim 4 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to one of the discharge electrode and the dust collection electrode to apply a voltage on each of the electrodes. 
     
     
         9 . The exhaust gas treatment apparatus according to  claim 1 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to each of the electrodes independently. 
     
     
         10 . The exhaust gas treatment apparatus according to  claim 2 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to each of the electrodes independently. 
     
     
         11 . The exhaust gas treatment apparatus according to  claim 3 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to each of the electrodes independently. 
     
     
         12 . The exhaust gas treatment apparatus according to  claim 4 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to each of the electrodes independently. 
     
     
         13 . The exhaust gas treatment apparatus according to  claim 5 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to each of the electrodes independently. 
     
     
         14 . The exhaust gas treatment apparatus according to  claim 6 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to each of the electrodes independently. 
     
     
         15 . The exhaust gas treatment apparatus according to  claim 7 , wherein the discharge electrode and the dust collection electrode are disposed in an electrically connected state, and a voltage is applied to each of the electrodes independently. 
     
     
         16 . The exhaust gas treatment apparatus according to  claim 1 , wherein the dust collection electrode is formed so that a diameter in a cross section perpendicular to the flow direction of the flow passage is 0.1 to 0.5 times the inner diameter of the tubular body. 
     
     
         17 . The exhaust gas treatment apparatus according to  claim 1 , which is further provided with a second discharge electrode disposed in the central portion in a cross section perpendicular to the flow direction of the flow passage on the downstream side of the tip on the flow passage upstream side of the dust collection electrode and causing corona discharge in the vicinity thereof by applying a voltage. 
     
     
         18 . The exhaust gas treatment apparatus according to  claim 1 , wherein at least one of the discharge electrode and the dust collection electrode is supported in the central portion of the fluid passage by a porcelain bushing passing through the wall face of the tubular body and being extended up to the central portion in a cross section perpendicular to the flow direction of the flow passage. 
     
     
         19 . The exhaust gas treatment apparatus according to  claim 18 , wherein the porcelain bushing has groove-shaped unevenness formed on the surface thereof. 
     
     
         20 . The exhaust gas treatment apparatus according to  claim 1 , which is disposed in an exhaust system of a vehicle provided with a gasoline engine as a drive mechanism.