Exhaust-gas purifying device

Abstract

An exhaust-gas purifying device purifies an exhaust gas exhausted from a gasoline engine of a vehicle and flowing in an exhaust pipe, and has a purifying function part disposed in the exhaust pipe and a detector located downstream of the purifying part in the exhaust pipe. The purifying function part has a three-way catalyst that oxidizes and reduces a toxic substance and a filter that collects a particular matter included in the exhaust gas. The detector detects an amount of the particular matter based on electrical conductivity between the electrodes of the detector. The detector is located at a position that is one meter distanced from a downstream end of the purifying function part in a path length of the exhaust pipe or a position at which a temperature of the exhaust gas flowing after a warm-up operation of the gasoline engine is lower than or equal to 450° C.

1 . An exhaust-gas purifying device that purifies an exhaust gas exhausted from a gasoline engine of a vehicle and flowing in an exhaust pipe, the exhaust-gas purifying device comprising:
 a purifying function part that is disposed in the exhaust pipe and has a three-way catalyst and a filter, the three-way catalyst oxidizing and reducing a toxic substance included in the exhaust gas by a metal catalytic agent, the filter collecting a particular matter that is included in the exhaust gas flowing through the filter; and   a detector that is disposed in the exhaust pipe and located downstream of the purifying part in the exhaust pipe, the detector that has an electrical insulating portion to which the particular matter is attached and a plurality of electrodes arranged to be distanced from each other, the detector that detects an amount of the particular matter attached to the electrical insulating portion based on electrical conductivity between the plurality of electrodes, wherein   the detector is located at a position that is one meter distanced from a downstream end of the purifying function part in a path length of the exhaust pipe, or at a position at which a temperature of the exhaust gas flowing after a warm-up operation of the gasoline engine is lower than or equal to 450° C.   
     
     
         2 . The exhaust-gas purifying device according to  claim 1 , wherein
 the three-way catalyst is disposed in the exhaust pipe separately from the filter and located upstream of the filter, and   the filter is located at a position that is 0.5 meter distanced from the downstream end of the three-way catalyst in the path length of the exhaust pipe, or at a position at which a temperature of the exhaust gas flowing out of the downstream end of the three-way catalyst is lower than or equal to 50° C. after the warm-up operation of the gasoline engine and after an activation of the three-way catalyst.   
     
     
         3 . The exhaust-gas purifying device according to  claim 1 , wherein
 the metal catalytic agent is supported on a surface of the filter.   
     
     
         4 . The exhaust-gas purifying device according to  claim 1 , wherein
 a rotation speed of the gasoline engine is lower than or equal to 4,000 rpm in a normal operation range.   
     
     
         5 . The exhaust-gas purifying device according to  claim 1 , wherein
 the filter has
 a penetration cell that passes through the filter from an upstream end to a downstream end of the filter, the penetration cell in which the exhaust gas flows, and 
 an inlet-sealed cell that is located adjacent to the penetration cell and has an upstream opening being sealed and a downstream opening being opened, the exhaust gas that flows out of the downstream opening of the inlet-sealed cell.