Exhaust purification system of internal combustion engine

Abstract

An exhaust purification system provided with an exhaust manifold, a catalytic converter which is arranged at a downstream side of the exhaust manifold an angle with respect to the exhaust manifold and which houses an NO x storage and reduction catalyst, and a reducing agent feed system which feeds reducing agent into exhaust gas which passes through the inside of the exhaust manifold. The part of the inner wall surface of the casing of the catalytic converter which faces the exhaust manifold outlet is provided with a projecting part which projects out toward the diametrically outward direction of the casing. Part of the wall surface which defines the projecting part is formed so that a velocity component, in an axial direction of the casing, of at least part of the flow of exhaust gas which flows into the projecting part, is oriented in an opposite direction to the direction heading toward the NO x storage and reduction catalyst. The exhaust purification system of an internal combustion engine which suppresses an increase in pressure loss of the exhaust gas and causes the reducing agent which was fed from the reducing agent feed system to disperse in the exhaust gas is provided.

1 . An exhaust purification system of an internal combustion engine which is provided with an upstream side exhaust passage through which exhaust gas which is exhausted from the internal combustion engine passes, a downstream side exhaust passage which is arranged at a downstream side of said upstream side exhaust passage at an angle with respect to the upstream side exhaust passage, a reducing agent feeding device which feeds reducing agent into the exhaust gas which passes through the inside of the upstream side exhaust passage, and an exhaust purifying device which is provided inside the downstream side exhaust passage,
 wherein, the part of the inner wall surface, which defines the downstream side exhaust passage and faces the upstream side exhaust passage outlet, is provided with a flow deflection part, and said flow deflection part is positioned at the upstream side from the exhaust purifying device and is formed so that a velocity component, in an axial direction of a downstream side exhaust passage, of at least part of the flow of exhaust gas which flows into said flow deflection part is oriented in an opposite direction to the direction heading toward the exhaust purifying device, and wherein a cross-sectional area of the downstream side exhaust passage is constant from where the exhaust gas flows out from said flow deflection part to where it reaches the exhaust purifying device.   
     
     
         2 . An exhaust purification system of an internal combustion engine as set forth in  claim 1 , wherein the region of the wall surface which defines said flow deflection part at the exhaust purifying device side has a part which is slanted in a direction opposite to the direction heading toward the exhaust purifying device toward the diametrically outward direction of the downstream side exhaust passage. 
     
     
         3 . An exhaust purification system of an internal combustion engine which is provided with an upstream side exhaust passage through which exhaust gas which is exhausted from the internal combustion engine passes, a downstream side exhaust passage which is arranged at a downstream side of said upstream side exhaust passage at an angle with respect to the upstream side exhaust passage, a reducing agent feeding device which feeds reducing agent into the exhaust gas which passes through the inside of the upstream side exhaust passage, and an exhaust purifying device which is provided inside the downstream side exhaust passage,
 wherein, the part of the inner wall surface, which defines the downstream side exhaust passage and faces the upstream side exhaust passage outlet, is provided with a flow deflection part, said flow deflection part is positioned at the upstream side from the exhaust purifying device, and a wall surface of said flow deflection part is formed so that at least part of the exhaust gas which strikes part of the wall surface of said flow deflection part and is increased in velocity component in the direction heading toward an exhaust purifying device strikes another part of the wall of surface of said flow deflection part and is lowered in velocity component of the same direction of said exhaust gas, and wherein a cross-sectional area of the downstream side exhaust passage is constant from where the exhaust gas flows out from said flow deflection part to where it reaches the exhaust purifying device.   
     
     
         4 . An exhaust purification system of an internal combustion engine as set forth in  claim 3 , wherein a region of the wall surface which defines said flow deflection part at the side away from the exhaust purifying device has a part which is slanted in a direction heading toward the exhaust purifying device toward the diametrically outward direction of the downstream side exhaust passage. 
     
     
         5 . An exhaust purification system of an internal combustion engine as set forth in  claim 1 , wherein said flow deflection part is provided with a projecting part which is formed by the inner wall surface, which defines the downstream side exhaust passage, projecting out toward the diametrically outward direction of the downstream side exhaust passage. 
     
     
         6 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein the cross-section of said projecting part in the circumferential direction of the downstream side exhaust passage is substantially semi elliptical in shape. 
     
     
         7 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein an inlet area of said projecting part which faces said downstream side exhaust passage is larger than the cross-sectional area of the upstream side exhaust passage. 
     
     
         8 . An exhaust purification system of an internal combustion engine as set forth in  claim 7 , wherein a height, in the axial direction of the downstream side exhaust passage, of said projecting part is larger than a diameter of the upstream side exhaust passage. 
     
     
         9 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein said projecting part extends in the circumferential direction of said downstream side exhaust passage. 
     
     
         10 . An exhaust purification system of an internal combustion engine as set forth in  claim 9 , wherein a depth of said projecting part in the diametrical direction of the downstream side exhaust passage becomes smaller the further from the region which faces said upstream side exhaust passage outlet. 
     
     
         11 . An exhaust purification system of an internal combustion engine as set forth in  claim 9 , wherein said projecting part is formed so that the outer circumference becomes substantially semi elliptical in shape. 
     
     
         12 . An exhaust purification system of an internal combustion engine as set forth in  claim 9 , wherein said projecting part is slanted so as to be positioned more at the exhaust purifying device side the further away from the region facing said upstream side exhaust passage outlet in the circumferential direction of the downstream side exhaust passage. 
     
     
         13 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein said upstream side exhaust passage extends, near the outlet thereof, so that a center axis passes though the inside of the projecting part. 
     
     
         14 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein said upstream side exhaust passage extends, near the outlet thereof, at a slant with respect to a center axis of the downstream side exhaust passage. 
     
     
         15 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein said upstream side exhaust passage extends, near the outlet thereof, perpendicular to a center axis of the downstream side exhaust passage. 
     
     
         16 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein said upstream side exhaust passage extends so as to penetrate into the downstream side exhaust passage. 
     
     
         17 . An exhaust purification system of an internal combustion engine as set forth in  claim 5 , wherein said upstream side exhaust passage outlet penetrates into said projecting part. 
     
     
         18 . An exhaust purification system of an internal combustion engine as set forth in  claim 1 , wherein said flow deflection part is provided with a projecting part which is formed by the inner wall surface, which defines the downstream side exhaust passage, projecting out toward the diametrically outward direction of the downstream side exhaust passage and wherein a cross-section of said projecting part in a circumferential direction of the downstream side exhaust passage is substantially rectangular. 
     
     
         19 . An exhaust purification system of an internal combustion engine as set forth in  claim 1 , wherein said flow deflection part is provided with a protruding part which projects out from an inner wall surface, which defines the downstream side exhaust passage, toward the diametrically inward direction of the downstream side exhaust passage. 
     
     
         20 . An exhaust purification system of an internal combustion engine as set forth in  claim 1 , wherein said upstream side exhaust passage is defined by an exhaust manifold or an exhaust pipe which is directly connected to the exhaust manifold, and said downstream side exhaust passage is a corn provided at an upstream part of the catalytic converter which houses the exhaust purifying device. 
     
     
         21 . An exhaust purification system of an internal combustion engine as set forth in  claim 3 , wherein said flow deflection part is provided with a projecting part which is formed by the inner wall surface, which defines the downstream side exhaust passage, projecting out toward the diametrically outward direction of the downstream side exhaust passage. 
     
     
         22 . An exhaust purification system of an internal combustion engine as set forth in  claim 3 , wherein said flow deflection part is provided with a projecting part which is formed by the inner wall surface, which defines the downstream side exhaust passage, projecting out toward the diametrically outward direction of the downstream side exhaust passage and wherein a cross-section of said projecting part in a circumferential direction of the downstream side exhaust passage is substantially rectangular. 
     
     
         23 . An exhaust purification system of an internal combustion engine as set forth in  claim 3 , wherein said flow deflection part is provided with a protruding part which projects out from an inner wall surface, which defines the downstream side exhaust passage, toward the diametrically inward direction of the downstream side exhaust passage. 
     
     
         24 . An exhaust purification system of an internal combustion engine as set forth in  claim 3 , wherein said upstream side exhaust passage is defined by an exhaust manifold or an exhaust pipe which is directly connected to the exhaust manifold, and said downstream side exhaust passage is a corn provided at an upstream part of the catalytic converter which houses the exhaust purifying device.