Exhaust purification device

Abstract

Provided are gas dispersion portion 7 C covering entry end face of selective reduction catalyst 4 (aftertreatment device) and introducing exhaust gas 1 through exhaust feed port 11 from direction substantially perpendicular to axis of aftertreatment device and mixing pipe 7 B (exhaust conduit) curved from exhaust feed port 11 in the gas dispersion portion 7 C toward exit side of the selective reduction catalyst 4 to extend axially of aftertreatment device. Gas dispersion portion 7 C is of crushingly deformed shape to ensure area from exhaust feed port 11 to vicinity of extension of axis of the selective reduction catalyst 4 as fan-likely spreading flow guide space 12, remaining area being flat throttling space 13 close to entry end face of selective reduction catalyst 4. Boundary between throttling and flow guide spaces 13 and 12 in crushing deformed shape is formed as arc-like taper slope 14.

1 . An exhaust emission control device with an exhaust system including an aftertreatment device for purifying exhaust gas passing therethrough and with an adopted layout for turnabout introduction of the exhaust gas into said aftertreatment device, characterized in that it comprises a gas dispersion portion for covering an entry end face of said aftertreatment device and for introducing the exhaust gas thereinto through an exhaust feed port from a direction substantially perpendicular to an axis of said aftertreatment device and an exhaust conduit curved from the exhaust feed port in said gas dispersion portion toward an exit side of said aftertreatment device to extend axially of said aftertreatment device, said gas dispersion portion being of a crushingly deformed shape to ensure an area from said exhaust feed port in said gas dispersion portion to a vicinity of an extension of the axis of said aftertreatment device as a fan-likely spreading flow guide space, a remaining area being a flat throttling space close to the entry end face of said aftertreatment device, a boundary between said throttling and flow guide spaces in the crushingly deformed shape being formed as an arc-like taper slope. 
     
     
         2 . The exhaust emission control device as claimed in  claim 1 , wherein a step is formed midway on a gradient of the taper slope, the step being arcuate concentrically of an arc shape of said taper slope and projecting toward the entry end face of the aftertreatment device. 
     
     
         3 . The exhaust emission control device as claimed in  claim 1 , wherein the exhaust conduit has a flow passage cross section upstream of the exhaust feed port in the form of a rhombus with one of diagonals thereof being aligned with the curved direction of said exhaust conduit. 
     
     
         4 . The exhaust emission control device as claimed in  claim 2 , wherein the exhaust conduit has a flow passage cross section upstream of the exhaust feed port in the form of a rhombus with one of diagonals thereof being aligned with the curved direction of said exhaust conduit. 
     
     
         5 . The exhaust emission control device as claimed in  claim 1 , wherein a guide depression is formed on the gas dispersion portion, said guide depression projecting into the throttling space in position corresponding to a bisectrix of a fan shape of the flow guide space to suppress and direct a main flow of the exhaust gas centrally of the entry end face of the aftertreatment device. 
     
     
         6 . The exhaust emission control device as claimed in  claim 2 , wherein a guide depression is formed on the gas dispersion portion, said guide depression projecting into the throttling space in position corresponding to a bisectrix of a fan shape of the flow guide space to suppress and direct a main flow of the exhaust gas centrally of the entry end face of the aftertreatment device. 
     
     
         7 . The exhaust emission control device as claimed in  claim 3 , wherein a guide depression is formed on the gas dispersion portion, said guide depression projecting into the throttling space in position corresponding to a bisectrix of a fan-shape of the flow guide space to suppress and direct a main flow of the exhaust gas centrally of the entry end face of the aftertreatment device. 
     
     
         8 . The exhaust emission control device as claimed in  claim 4 , wherein a guide depression is formed on the gas dispersion portion, said guide depression projecting into the throttling space in position corresponding to a bisectrix of a fan-shape of the flow guide space to suppress and direct a main flow of the exhaust gas centrally of the entry end face of the aftertreatment device. 
     
     
         9 . The exhaust emission control device as claimed in  claim 5 , wherein a sensor boss is formed on the bisectrix of the fan shape of the flow guide space between the guide depression and the taper slope. 
     
     
         10 . The exhaust emission control device as claimed in  claim 6 , wherein a sensor boss is formed on the bisectrix of the fan shape of the flow guide space between the guide depression and the taper slope. 
     
     
         11 . The exhaust emission control device as claimed in  claim 7 , wherein a sensor boss is formed on the bisectrix of the fan shape of the flow guide space between the guide depression and the taper slope. 
     
     
         12 . The exhaust emission control device as claimed in  claim 8 , wherein a sensor boss is formed on the bisectrix of the fan shape of the flow guide space between the guide depression and the taper slope.