Control device for internal combustion engine

Abstract

A control device comprising a first exhaust temperature calculation part calculating a temperature of exhaust flowing into a PM trapping device as a first exhaust temperature, a second exhaust temperature calculation part calculating a temperature of exhaust flowing out from the PM trapping device as a second exhaust temperature, a rate of change over time calculation part calculating a rate of change over time of the first exhaust temperature and a rate of change over time of the second exhaust temperature, and a judgment part judging if the PM trapping device is in a removed state removed from the exhaust passage based on a difference between the rate of change over time of the first exhaust temperature and the rate of change over time of the second exhaust temperature.

1 . A control device for an internal combustion engine,
 the internal combustion engine comprising:
 an engine body; and 
 an exhaust after-treatment system installed in an exhaust passage of the engine body, wherein 
   the control device comprises:
 a first exhaust temperature calculation part configured to calculate a temperature of exhaust flowing into the exhaust after-treatment system as a first exhaust temperature; 
 a second exhaust temperature calculation part configured to calculate a temperature of exhaust flowing out from the exhaust after-treatment system as a second exhaust temperature; 
 a rate of change over time calculation part configured to calculate a rate of change over time of the first exhaust temperature and a rate of change over time of the second exhaust temperature; and 
 a judgment part configured to judge if the exhaust after-treatment system is in a removed state removed from the exhaust passage based on a difference between the rate of change over time of the first exhaust temperature and the rate of change over time of the second exhaust temperature, wherein 
   the first exhaust temperature calculation part comprises a drop calculation part configured to calculate an amount of drop of exhaust temperature falling in a process of flowing through the exhaust passage from a position where a first exhaust temperature sensor provided in the exhaust passage at an upstream side from the exhaust after-treatment system in an exhaust flow direction is attached to the exhaust after-treatment system, and   the first exhaust temperature calculation part calculates the detection value of the first exhaust temperature sensor minus the amount of drop as the first exhaust temperature.   
     
     
         2 . The control device for the internal combustion engine according to  claim 1 , wherein
 the drop calculation part calculates the amount of drop based on the flow rate of intake air and outside air temperature.   
     
     
         3 . The control device for the internal combustion engine according to  claim 1 , wherein
 the judgment part comprises:
 a differential value calculation part configured to calculate a differential value between an absolute value of the rate of change over time of the first exhaust temperature and an absolute value of the rate of change over time of the second exhaust temperature; and 
 an integrated value calculation part configured to calculate an integrated value obtained by integrating a certain number or more of values of the differential value, and 
   the judgment part is configured to judge a state is the removed state if the integrated value is less than a predetermined threshold value.   
     
     
         4 . The control device for the internal combustion engine according to  claim 3 , wherein
 the drop calculation part calculates the amount of drop based on the flow rate of intake air and outside air temperature.