Exhaust particulate matter measuring apparatus

Abstract

A PM sensor for measuring particle matter in exhaust gas is disposed between a three-way catalyst and a muffler in an exhaust pipe, and has an oxidation catalyst and an electrical heater that are stacked together, and a temperature sensor that measures a temperature of the oxidation catalyst interposed between the oxidation catalyst and the electrical heater. The oxidation catalyst carries a ceria as an oxygen-storing agent that occludes oxygen in the exhaust gas, and a ECU calculates a sediment amount of the exhaust particulate matter based on an amount of temperature rise when the electrical heater heats the oxidation catalyst and an accumulated value of an intake air amount.

1 - 11 . (canceled) 
   
   
       12 . An exhaust particulate matter measuring apparatus, wherein comprising:
 an oxidation catalyst that carries an oxygen-storing agent, disposed in an exhaust passage of an internal combustion engine;   a heating device that heats the oxidation catalyst;   a temperature sensor that detects a temperature of the oxidation catalyst; and   a sediment amount calculation device that calculates a sediment amount of exhaust particulate matter based on the amount by which the temperature of the oxidation catalyst increases when the heating device heats the oxidation catalyst,   wherein the oxidation catalyst is disposed downstream in an exhaust gas flow direction from a three-way catalyst disposed in the exhaust passage and upstream from a muffler disposed in the exhaust passage.   
   
   
       13 . The exhaust particulate matter measuring apparatus according to  claim 12 , wherein:
 the sediment amount calculation device estimates an amount of oxygen occluded by the oxygen-storing agent based on a duration time of a fuel cut control executed by the internal combustion engine and an intake air amount; and   when the amount of occluded oxygen reaches or exceeds a prescribed value, the heating device heats the oxidation catalyst to calculate the sediment amount of exhaust particulate matter.   
   
   
       14 . The exhaust particulate matter measuring apparatus according to  claim 12 , wherein:
 an oxygen sensor is disposed in the vicinity of the oxidation catalyst in the exhaust passage;   the sediment amount calculation device estimates an amount of oxygen occluded by the oxygen-storing agent based on a detected result of the oxygen sensor; and   when the amount of oxygen occluded reaches or exceeds a prescribed value, the heating device heats the oxidation catalyst to calculate the sediment amount of exhaust particulate matter.   
   
   
       15 . An exhaust particulate matter measuring apparatus according to  claim 12 , wherein the sediment amount calculation device heats the oxidation catalyst by the heating device to calculate the sediment amount of the exhaust particulate matter when the internal combustion engine executes a fuel cut control. 
   
   
       16 . The exhaust particulate matter measuring apparatus according to  claim 12 , wherein the sediment amount calculation device heats the oxidation catalyst using the heating device to combust the exhaust particle matter when the temperature of the oxidation catalyst is at or below than a temperature at which the exhaust particulate matter cannot be combusted, and accumulation of the intake air amount is started,
 wherein when the accumulated amount of intake air exceeds a prescribed value, the sediment amount calculation device heats the oxidation catalyst using the heating device to calculate the sediment amount of the exhaust particulate matter.   
   
   
       17 . The exhaust particulate matter measuring apparatus according to  claim 16 , further comprising an exhaust temperature sensor disposed in a vicinity of the oxidation catalyst,
 wherein the sediment amount calculation device cancels the accumulated value of intake air amount and restarts the calculation of the intake air amount when the exhaust gas temperature reaches the combustion temperature of the exhaust particulate matter.   
   
   
       18 . The exhaust particulate matter measuring apparatus according to  claim 12 , wherein the sediment amount calculation device prohibits rich operation of the internal combustion engine when the heating device heats the oxidation catalyst to calculate the sediment amount of the exhaust particulate matter. 
   
   
       19 . The exhaust particulate matter measuring apparatus according to  claim 14 , wherein the sediment amount calculation device determines whether the exhaust gas is in a lean condition, based on a detection result of the oxygen sensor and, if it is determined that the exhaust gas has been a lean condition for at least a prescribed period of time, heats the oxidation catalyst by the heating device and calculates the sediment amount of the exhaust particulate matter. 
   
   
       20 . The exhaust particulate matter measuring apparatus according to  claim 16 ,
 further comprising an air flow sensor disposed in the intake passage of the internal combustion engine that detects the intake air amount.   
   
   
       21 . An exhaust particulate matter measuring apparatus, characterized by comprising:
 an oxidation catalyst that carries an oxygen-storing agent, disposed in an exhaust passage of an internal combustion engine;   heating device that heats the oxidation catalyst;   a temperature sensor that detects a temperature of the oxidation catalyst: and   sediment amount calculation device that calculates a sediment amount of exhaust particulate matter based on the amount by which the temperature of the oxidation catalyst increases when the heating device heats the oxidation catalyst,   wherein the sediment amount calculation device heats the oxidation catalyst by the heating device to calculate the sediment amount of the exhaust particulate matter only when the internal combustion engine executes a fuel cut control.