Emission control system

Abstract

An emission control system, includes: an exhaust pipe portion, adapted to guide exhaust gas from an engine to outside; a catalyst, accommodated in the exhaust pipe portion; an additive injection valve, provided at the exhaust pipe portion located at upstream side of the catalyst, and configured to inject additives to be supplied to the catalyst toward a flow of the exhaust gas in the exhaust pipe portion. The exhaust pipe portion has a flow path section located at upstream side of the catalyst, which intersects an injection flow of the additives injected by the additive injection valve, and the flow path section is made to have substantially the same shape as an injection region of the injection flow which confronts the exhaust gas.

1 . An emission control system, comprising:
 an exhaust pipe portion, adapted to guide exhaust gas from an engine to outside;   a catalyst, accommodated in the exhaust pipe portion;   an additive injection valve, provided at the exhaust pipe portion located at upstream side of the catalyst, and configured to inject additives to be supplied to the catalyst toward a flow of the exhaust gas in the exhaust pipe portion, wherein   the exhaust pipe portion has a flow path section located at upstream side of the catalyst, which intersects an injection flow of the additives injected by the additive injection valve, and   the flow path section is made to have substantially the same shape as an injection region of the injection flow which confronts the exhaust gas.   
   
   
       2 . The emission control system as set forth in  claim 1 , wherein
 the flow path section is an exhaust gas induction portion that is formed at the exhaust pipe portion located at upstream side of the catalyst, which intersects the injection flow of the additives injected by the additive injection valve, and that has a shape being identical with an injection region of the injection flow as viewed from a direction which intersects the flow of the exhaust gas.   
   
   
       3 . The emission control system as set forth in  claim 2 , wherein
 the exhaust gas induction portion has a shape that expands towards a leading end of the injection flow and that is shaped in such a manner that an upstream side of the injection flow is thin and a downstream side of the injection flow is thick.   
   
   
       4 . The emission control system as set forth in  claim 3 , wherein
 the exhaust pipe portion located at upstream side of the catalyst is formed in such a manner as to intersect the injection flow of the additives at an acute angle and to confront the catalyst, and   the exhaust gas induction portion is formed from an upstream part of the exhaust pipe portion which intersects the injection flow of the additives.   
   
   
       5 . The emission control system as set forth in  claim 3 , wherein
 the exhaust pipe portion located at upstream side of the catalyst is formed in such a manner as to intersect the injection flow of the additives in a substantially normal direction and to confront the catalyst, and   the exhaust gas induction portion is formed from an upstream part of the exhaust pipe portion which intersects the injection flow of the additives.   
   
   
       6 . The emission control system as set forth in  claim 5 , wherein
 a release portion where a contact with the injection flow of the additives which is deflected as a result of collision with the exhaust gas is avoided, is formed at a downstream part of the exhaust pipe portion which intersects the injection flow of the additives.   
   
   
       7 . The emission control system as set forth in  claim 2 , wherein
 the exhaust gas induction portion is formed in such a manner as to keep an area of a flow path from an upstream side of the exhaust pipe portion constant.   
   
   
       8 . The emission control system as set forth in  claim 2 , wherein
 the exhaust pipe portion is provided with;
 a bent portions connected to an upstream side of the catalyst, and formed by bending the exhaust pipe portion; and 
 a projecting portion, one end of which is opened to a wall surface of the bent portion, and which projects to an opposite side of the catalyst in a direction of a central axis of the catalyst, and 
   the additive injection valve is provided at the other end of the projecting portion.   
   
   
       9 . The emission control system as set forth in  claim 1 , wherein
 an additive mixing portion is formed at the exhaust pipe portion located at upstream side of the catalyst, through which the injection flow of the additives injected by the additive injection valve passes, and has a shape being identical with a section of an injection region of the injection flow.   
   
   
       10 . The emission control system as set forth in  claim 9 , wherein
 the additive mixing portion is formed in such a manner as to keep an area of a flow path from an upstream side of the exhaust pipe portion constant.   
   
   
       11 . The emission control system as set forth in  claim 10 , wherein
 an outlet of the additive mixing portion is expanded into a bell mouth shape.   
   
   
       12 . The emission control system as set forth in  claim 10 , wherein
 the exhaust pipe portion is provided with:
 a bent portion, connected to an upstream side of the catalyst, and formed by bending the exhaust pipe portion; and 
 a projecting portion, one end of which is opened to a wall surface of the bent portion, and which projects to an opposite side of the catalyst in a direction of a central axis of the catalyst, and 
   the additive injection valve is provided at the other end of the projecting portion.