Internal combustion engine and method of controlling the same

Abstract

A method for controlling an exhaust system for an internal combustion engine of a vehicle includes flowing exhaust gas to a main catalyst converter provided in a main passage, flowing exhaust gas to a bypass catalyst converter provided in a bypass passage, detecting a predetermined condition related to a poisoning amount of the bypass catalyst converter, and blocking the main passage at least partially in response to the satisfaction of the predetermined condition, thereby causing more of the exhaust gas to flow to the bypass passage.

1 . A method for controlling an exhaust system for an internal combustion engine of a vehicle, comprising: 
 flowing exhaust gas to a main catalyst converter provided in a main passage;    flowing exhaust gas to a bypass catalyst converter provided in a bypass passage;    detecting a predetermined condition related to a poisoning amount of the bypass catalyst converter; and    blocking the main passage at least partially in response to the predetermined condition, thereby causing more of the exhaust gas to flow to the bypass passage.    
   
   
       2 . The method of  claim 1 , wherein the blocking is further in response to deceleration of the vehicle.  
   
   
       3 . The method of  claim 2 , wherein the blocking is further in response to detection of a decrease in a stepped amount of an accelerator pedal.  
   
   
       4 . The method of  claim 2 , wherein the blocking is further in response to a fuel cut-off of the internal combustion engine.  
   
   
       5 . The method of  claim 3 , wherein the blocking is further in response to a fuel cut-off of the internal combustion engine.  
   
   
       6 . The method of  claim 1 , wherein the predetermined condition of the poisoning amount is satisfied after at least one of a predetermined driving distance and a predetermined time is elapsed since the main passage is opened to start the flow of the exhaust gas to the main passage.  
   
   
       7 . The method of  claim 6 , wherein the predetermined time or predetermined driving distance is determined depending on an operating condition of the internal combustion engine after the main passage is opened.  
   
   
       8 . The method of  claim 6 , wherein the blocking is performed by a flow path switching valve for opening/closing the main passage, and 
 wherein the at least one of the predetermined time and the predetermined driving distance is determined depending on a valve opening degree of the flow path switching valve.    
   
   
       9 . The method of  claim 8 , wherein as the valve opening degree of the flow path switching valve becomes larger, at least one of the predetermined time and the predetermined driving distance is set to be longer.  
   
   
       10 . The method of  claim 7 , wherein as the engine speed and load of the internal combustion engine are greater, the at least one of the predetermined time and the predetermined driving distance is set to be shorter.  
   
   
       11 . An exhaust system for an internal combustion engine of a vehicle, comprising: 
 a main passage for an exhaust gas discharged from a cylinder;    a main catalyst converter provided in the main passage;    a bypass passage having a cross-sectional area smaller than the main passage, wherein the bypass passage branches from the main passage at a main catalyst converter upstream side and connects at the main catalyst converter upstream side;    a bypass catalyst converter provided in the bypass passage;    a main passage blocking means for at least partially closing the main passage so as to allow the exhaust gas discharged from the cylinder to flow to the bypass passage; and    a main passage opening/closing switching means for at least partially closing the main passage blocking means so as to allow the exhaust gas to flow to the bypass passage when a predetermined condition related to a poisoning amount of the bypass catalyst converter is satisfied.    
   
   
       12 . The internal combustion engine of  claim 11 , further comprising a main passage opening/closing switching means for closing the main passage blocking means when the predetermined condition of the poisoning amount is satisfied and the vehicle is decelerated.  
   
   
       13 . The internal combustion engine of  claim 11 , further comprising a means for detecting an accelerator pedal stepped amount, and 
 a main passage opening/closing switching means for closing the main passage blocking means when the predetermined condition of the poisoning amount is satisfied and the accelerator pedal stepped amount is decreased.    
   
   
       14 . The internal combustion engine of  claim 11 , wherein the bypass catalyst converter provided uses a tertiary catalyst.  
   
   
       15 . An exhaust system for an internal combustion engine of a vehicle, comprising: 
 a main passage for an exhaust gas discharged from a cylinder;    a main catalyst converter provided in the main passage;    a bypass passage having a cross-sectional area smaller than the main passage, wherein the bypass passage branches from the main passage at a main catalyst converter upstream side and connects at the main catalyst converter upstream side;    a bypass catalyst converter provided in the bypass passage;    a flow path switching valve disposed in the main passage downstream of where the bypass passage branches from the main passage; and    an actuator configured to at least partially close the flow path switching valve when a predetermined condition related to a poisoning amount of the bypass catalyst converter is satisfied.