Exhaust gas purification apparatus for an internal combustion engine

Abstract

First processing and second processing are carried out, wherein in the first processing, the electric power to be supplied to the heat generation element is set to a first electric power in a first period of time such that a temperature inside the heat generation element falls within an allowable temperature range, and in the second processing, at least one of setting the electric power to be supplied to said heat generation element from said power supply to a second electric power smaller than said first electric power, and/or setting the electric power to be supplied to said heat generation element from said power supply to zero, is performed in a second period of time such that the temperature difference inside the heat generation element falls within an allowable temperature difference range.

1 . An exhaust gas purification apparatus for an internal combustion engine comprising:
 an electrically heated catalyst that includes a heat generation element arranged in an exhaust passage of the internal combustion engine for generating heat by receiving supply of electric power, and a catalyst supported by said heat generation element;   a power supply that supplies electric power to said heat generation element; and   a controller configured to adjust the electric power to be supplied to said heat generation element from said power supply;   wherein in a first period of time and a second period of time in which said internal combustion engine is stopped and which are before starting said internal combustion engine, said second period of time being after said first period of time, said controller is configured to supply electric power such that a total amount of electric energy to be supplied to said heat generation element from said power supply becomes a required amount of electric energy; and   said controller is further configured to carry out first processing, in which the electric power to be supplied to said heat generation element from said power supply is set to a first electric power in said first period of time such that a temperature inside said heat generation element falls within an allowable temperature range, and second processing, in which at least one of setting the electric power to be supplied to said heat generation element from said power supply to a second electric power smaller than said first electric power, and/or setting the electric power to be supplied to said heat generation element from said power supply to zero, is performed in said second period of time such that a difference in temperature inside said heat generation element falls within an allowable temperature difference range.   
     
     
         2 . The exhaust gas purification apparatus for an internal combustion engine as set forth in  claim 1 , wherein
 said controller is configured to set the electric power to be supplied to said heat generation element from said power supply to 0 in a stop period of time before supply of the second electric power, which is included in said second period of time, and also set the electric power to be supplied to said heat generation element from said power supply to said second electric power in a second electric power supply period of time, which is included in said second period of time and which is after said stop period of time before supply of the second electric power.   
     
     
         3 . The exhaust gas purification apparatus for an internal combustion engine as set forth in  claim 1 , wherein
 said controller is configured to set the electric power to be supplied to said heat generation element from said power supply to said second electric power in a second electric power supply period of time which is included in said second period of time, and also set the electric power to be supplied to said heat generation element from said power supply to 0 in a stop period of time after the second electric power supply period of time, which is included in said second period of time and which is after said second electric power supply period of time.   
     
     
         4 . The exhaust gas purification apparatus for an internal combustion engine as set forth in  claim 1 , wherein
 said controller is configured to set said first electric power, said first period of time, said second electric power and said second period of time in such a manner that the amount of electric energy at an end point in time of said second period of time becomes the required amount of electric energy, and start said internal combustion engine at a point in time at which said second period of time expires.