Particulate matter treatment system

Abstract

A particulate matter treatment system includes an electrode provided in an exhaust passage of an internal combustion engine, a power supply connected to the electrode and operable to apply a voltage to the electrode, a particle number detector that detects the number of particles of particulate matter downstream of the electrode, and a determining device that determines that the system is at fault when an absolute value of the amount of change in the number of particles of particulate matter detected by the particle number detector when the voltage applied from the power supply to the electrode is changed is smaller than a threshold value.

1 . A particulate matter treatment system, comprising:
 an electrode provided in an exhaust passage of an internal combustion engine;   a power supply connected to the electrode and operable to apply a voltage to the electrode;   a particle number detector that detects the number of particles of particulate matter downstream of the electrode; and   a determining device that determines that the particulate matter treatment system is at fault when an absolute value of an amount of change in the number of particles of particulate matter detected by the particle number detector when the voltage applied from the power supply to the electrode is changed is smaller than a threshold value.   
     
     
         2 . The particulate matter treatment system according to  claim 1 , wherein the threshold value is changed according to the number of particles detected by the particle number detector. 
     
     
         3 . The particulate matter treatment system according to  claim 2 , wherein the threshold value is set to a larger value as the number of particles detected by the particle number detector is larger. 
     
     
         4 . The particulate matter treatment system according to  claim 1 , further comprising an exhaust gas amount detector that detects or estimates an amount of exhaust gas emitted from the internal combustion engine,
 wherein the threshold value is changed according to the amount of exhaust gas detected by the exhaust gas amount detector.   
     
     
         5 . The particulate matter treatment system according to  claim 4 , wherein the threshold value is set to a larger value as the amount of exhaust gas detected by the exhaust gas amount detector is smaller. 
     
     
         6 . The particulate matter treatment system according to  claim 2 , further comprising an exhaust gas amount detector that detects or estimates an amount of exhaust gas emitted from the internal combustion engine,
 wherein the threshold value is changed according to the amount of exhaust gas detected by the exhaust gas amount detector.   
     
     
         7 . The particulate matter treatment system according to  claim 6 , wherein the threshold value is set to a larger value as the amount of exhaust gas detected by the exhaust gas amount detector is smaller.