Exhaust Gas Purification System for Internal Combustion Engine

Abstract

An exhaust passageway of the internal combustion engine is formed of a single exhaust pipe 5 . A portion 11 b configuring a passageway through which the exhaust gas passes and a portion 11 c provided with a catalyst 11 e heating up the exhaust gas by emitting heat upon being supplied with a reducing agent, are provided in parallel so as to share a section of the single exhaust pipe with each other on an upstream side 11 of an exhaust gas purifying device 10 in the exhaust pipe 5 . In the exhaust gas flowing through the exhaust pipe 5 , allocation of a quantity of the exhaust gas passing through the catalyst 11 e and a quantity of the exhaust gas passing through the passageway 11 b , is set changeable.

1 . An exhaust gas purifying system of an internal combustion engine, comprising:
 an exhaust gas purifying device provided in an exhaust passageway of said internal combustion engine, purifying an exhaust gas passing through said exhaust passageway and with its temperature increased to a predetermined temperature or higher with the result that purifying capability thereof is improved;   exhaust gas temperature increasing unit provided on an upstream side of said exhaust gas purifying device in said exhaust passageway; and   reducing agent adding unit provided on the upstream side of said exhaust gas temperature increasing unit in said exhaust passageway and adding a reducing agent to the exhaust gas passing through said exhaust passageway,   wherein said exhaust gas temperature increasing unit includes:   an exhaust gas temperature increasing catalyst provided in a single exhaust pipe configuring said exhaust passageway so that an exhaust gas flow-through area trough which the exhaust gas should pass is left, supplied with the reducing agent added from said reducing agent adding unit and thereby emitting heat; and   an exhaust gas flow rate control device controlling, in the exhaust gas passing through said exhaust pipe, allocation of a quantity of the exhaust gas passing said exhaust gas flow-through area and a quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst.   
     
     
         2 . An exhaust gas purifying system of an internal combustion engine according to  claim 1 , wherein said exhaust gas flow-through area is disposed in a central portion in section perpendicular to an exhaust gas pass-through direction in said exhaust pipe, and
 said exhaust gas temperature increasing catalyst is disposed outside of said exhaust gas flow-through area within the section.   
     
     
         3 . An exhaust gas purifying system of an internal combustion engine according to  claim 1 , wherein said exhaust gas flow rate control device is capable of selecting, by controlling the allocation, a state where substantially an entire quantity of the exhaust gas flowing through said exhaust pipe passes through said exhaust gas flow-through area, a state where substantially the entire quantity of the exhaust gas flowing through said exhaust pipe passes through said exhaust gas temperature increasing catalyst, and a state where the exhaust gas flowing through the exhaust pipe passes through both of said exhaust gas flow-through area and said exhaust gas temperature increasing catalyst. 
     
     
         4 . An exhaust gas purifying system of an internal combustion engine according to  claim 1 , wherein when increasing the temperature of said exhaust gas purifying device,
 said reducing agent adding unit adds the reducing agent to the exhaust gas passing through said exhaust passageway, and said exhaust gas flow rate control device controls the allocation in order to make substantially the entire quantity of the exhaust gas flowing through said exhaust pipe pass through said exhaust gas temperature increasing catalyst, and   said exhaust gas flow rate control device, after the reducing agent added from said reducing agent adding unit has reached said exhaust gas temperature increasing catalyst, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst.   
     
     
         5 . An exhaust gas purifying system of an internal combustion engine according to  claim 1 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst. 
     
     
         6 . An exhaust gas purifying system of an internal combustion engine according to  claim 2 , wherein said exhaust gas flow rate control device is capable of selecting, by controlling the allocation, a state where substantially an entire quantity of the exhaust gas flowing through said exhaust pipe passes through said exhaust gas flow-through area, a state where substantially the entire quantity of the exhaust gas flowing through said exhaust pipe passes through said exhaust gas temperature increasing catalyst, and a state where the exhaust gas flowing through the exhaust pipe passes through both of said exhaust gas flow-through area and said exhaust gas temperature increasing catalyst. 
     
     
         7 . An exhaust gas purifying system of an internal combustion engine according to  claim 2 , wherein when increasing the temperature of said exhaust gas purifying device,
 said reducing agent adding unit adds the reducing agent to the exhaust gas passing through said exhaust passageway, and said exhaust gas flow rate control device controls the allocation in order to make substantially the entire quantity of the exhaust gas flowing through said exhaust pipe pass through said exhaust gas temperature increasing catalyst, and   said exhaust gas flow rate control device, after the reducing agent added from said reducing agent adding unit has reached said exhaust gas temperature increasing catalyst, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst.   
     
     
         8 . An exhaust gas purifying system of an internal combustion engine according to  claim 2 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst. 
     
     
         9 . An exhaust gas purifying system of an internal combustion engine according to  claim 3 , wherein when increasing the temperature of said exhaust gas purifying device,
 said reducing agent adding unit adds the reducing agent to the exhaust gas passing through said exhaust passageway, and said exhaust gas flow rate control device controls the allocation in order to make substantially the entire quantity of the exhaust gas flowing through said exhaust pipe pass through said exhaust gas temperature increasing catalyst, and   said exhaust gas flow rate control device, after the reducing agent added from said reducing agent adding unit has reached said exhaust gas temperature increasing catalyst, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst.   
     
     
         10 . An exhaust gas purifying system of an internal combustion engine according to  claim 3 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst. 
     
     
         11 . An exhaust gas purifying system of an internal combustion engine according to  claim 4 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst. 
     
     
         12 . An exhaust gas purifying system of an internal combustion engine according to  claim 6 , wherein when increasing the temperature of said exhaust gas purifying device,
 said reducing agent adding unit adds the reducing agent to the exhaust gas passing through said exhaust passageway, and said exhaust gas flow rate control device controls the allocation in order to make substantially the entire quantity of the exhaust gas flowing through said exhaust pipe pass through said exhaust gas temperature increasing catalyst, and   said exhaust gas flow rate control device, after the reducing agent added from said reducing agent adding unit has reached said exhaust gas temperature increasing catalyst, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst.   
     
     
         13 . An exhaust gas purifying system of an internal combustion engine according to  claim 6 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst. 
     
     
         14 . An exhaust gas purifying system of an internal combustion engine according to  claim 7 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst. 
     
     
         15 . An exhaust gas purifying system of an internal combustion engine according to  claim 9 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst. 
     
     
         16 . An exhaust gas purifying system of an internal combustion engine according to  claim 12 , wherein said exhaust gas flow rate control device, during a decelerating operation of a vehicle mounted with said internal combustion engine, controls the allocation in order to decrease, in the exhaust gas flowing through said exhaust pipe, the quantity of the exhaust gas passing through said exhaust gas temperature increasing catalyst.