Exhaust sensor mounting structure

Abstract

The present invention provides an exhaust sensor mounting structure for mounting an exhaust sensor having a sensing element covered by an element cover formed with an exhaust inlet hole to an exhaust pipe of an internal combustion engine. The exhaust pipe includes a tapered section connected to a downstream end of an exhaust purifying device at an upstream end thereof, and a downstream section connected to a downstream end of the tapered section at an upstream end thereof. The exhaust sensor mounting structure includes a guide member, and a fixing member fixing the guide member in such a position within the exhaust pipe that water vapor contained in an exhaust gas of the internal combustion engine and condensed upstream of the guide member is guided to fly through an area in which the exhaust inlet hole of the element cover located inside the exhaust pipe is not located.

1 . An exhaust sensor mounting structure for mounting, to an exhaust pipe of an internal combustion engine provided with an exhaust purifying device in a midway portion of said exhaust pipe, an exhaust sensor having a sensing element covered by an element cover formed with an exhaust inlet hole, said exhaust pipe including a tapered section connected to a downstream end of said exhaust purifying device at an upstream end thereof, and a downstream section connected to a downstream end of said tapered section at an upstream end thereof, said tapered section having a diameter narrowing towards said downstream end thereof, said exhaust sensor being mounted to said downstream section, said exhaust sensor mounting structure comprising: 
 a guide member; and    a fixing member fixing said guide member in such a position within said exhaust pipe that water vapor contained in an exhaust gas of said internal combustion engine and condensed upstream of said guide member is guided to fly through an area in which said exhaust inlet hole of said element cover located inside said exhaust pipe is not located.    
   
   
       2 . The exhaust sensor mounting structure according to  claim 1 , wherein said guide member has a hollow cylindrical shape and is disposed in said downstream section coaxially with downstream section, an upstream end of said guide member being located upstream of an intersecting position at which a first plane extending from said downstream end of said tapered section at an angle of 30 degrees with an inner wall surface of said downstream section and an inner wall surface of said guide member intersect with each other, a downstream end of said guide member being located in such a position that said exhaust inlet hole of said element cover is located upstream of a second plane extending from said downstream end of said guide member at an angle of 30 degrees with an outer wall surface of said guide member.  
   
   
       3 . The exhaust sensor mounting structure according to  claim 2 , wherein said upstream end of said guide member is located upstream of said downstream end of said tapered section.  
   
   
       4 . The exhaust sensor mounting structure according to  claim 3 , wherein said downstream end of said guide member is located downstream of a mounting position of said exhaust sensor.  
   
   
       5 . The exhaust sensor mounting structure according to  claim 2 , further comprising a tapered guide member having a circular cross section and connected to said upstream end of said guide member at a downstream end thereof, and extending into said tapered section, said tapered guide member having a diameter expanding toward an upstream end thereof.  
   
   
       6 . The exhaust sensor mounting structure according to  claim 2 , wherein an outer edge of said upstream end of said guide member is chamfered.  
   
   
       7 . The exhaust sensor mounting structure according to  claim 5 , wherein an outer edge of said upstream end of said tapered guide member is chamfered.  
   
   
       8 . The exhaust sensor mounting structure according to  claim 1 , wherein said exhaust sensor is an oxygen concentration sensor including a zirconia solid electrolyte type sensing element, and an electric heater for heating said zirconia solid electrolyte type sensing element.  
   
   
       9 . The exhaust sensor mounting structure according to  claim 1  configured to be applied to an exhaust pipe of a diesel engine with an exhaust purifying device.  
   
   
       10 . The exhaust sensor mounting structure according to  claim 1 , wherein said exhaust purifying device is a diesel particulate filter.