Method and arrangement for cooling an exhaust system

Abstract

The present invention relates to an arrangement for cooling an exhaust system of a vehicle having an internal combustion engine. The arrangement includes a controller for detecting an elevated temperature condition of the exhaust system, such as a so called hot soak condition, as well as detecting a predetermined engine operating status, such as either of an engine shutdown, a stopped or an idling status. A secondary air injection system may then be actuated to inject ambient air into the exhaust system thereby cooling said exhaust system.

1 . An arrangement for cooling an exhaust system for an internal combustion engine, comprising:
 a secondary air injection system coupled to the exhaust system, said secondary air injection system comprising;
 a pump for introducing ambient air into the exhaust system via a supply channel; and 
 a valve for selectively allowing said ambient air to be injected into the exhaust system; and 
   a controller coupled to said engine and said secondary air injection system, said controller actuating said secondary air injection system to introduce ambient air into said exhaust system when an exhaust gas temperature is above a predetermined value and a predetermined engine condition is detected by said controller.   
   
   
       2 . The arrangement according to  claim 1 , wherein said predetermined engine condition is an engine shutdown. 
   
   
       3 . The arrangement according to  claim 1 , wherein said predetermined engine condition is a stopped engine. 
   
   
       4 . The arrangement according to  claim 1 , wherein said predetermined engine condition is an idling engine. 
   
   
       5 . The arrangement according to  claim 1 , wherein said supply channel is attached to one or more of: a cylinder head of the engine; an engine exhaust manifold. 
   
   
       6 . The arrangement according to  claim 1  wherein said controller controls said secondary air injection system to discontinue introduction of air into exhaust system once said exhaust gas temperature is at or below said predetermined value. 
   
   
       7 . A method for cooling an exhaust system for an internal combustion engine, comprising:
 detecting an elevated temperature condition of the engine exhaust system;   detecting an engine operating condition; and   in response to said detected elevated temperature condition during said detected predetermined engine status, injecting air into the engine exhaust system.   
   
   
       8 . The method according to  claim 7 , wherein said detecting of said engine operating condition of the exhaust system comprises detection of engine shut-down after heavy load operation of the engine. 
   
   
       9 . The method according to  claim 7 , wherein said detecting of said engine operating condition comprises detection of stopped or idling operation of the engine. 
   
   
       10 . The method according to  claim 7  further comprising discontinuing air injection into the engine exhaust system once said elevated temperature condition is no longer detected.