Internal combustion engine

Abstract

An internal combustion engine according to the present invention includes an exhaust treatment apparatus provided in an exhaust passage, and a burner apparatus provided upstream of the exhaust treatment apparatus to increase an exhaust temperature. The burner apparatus includes at least a fuel addition valve that allows fuel to be added into exhaust and ignition means for igniting the fuel added via the fuel addition valve. The fuel addition valve is driven open when fuel is added via the fuel addition valve. The amount of fuel added via the fuel addition valve per unit time is increased beyond a predetermined reference amount when the detected amount of intake air exceeds a predetermined threshold value. The probability of successful ignition by the ignition apparatus is increased, and a flame is prevented from being blown out. Thus, the burner apparatus can demonstrate sufficient ignition performance and sufficient combustion performance.

1 . An internal combustion engine comprising:
 an exhaust treatment apparatus provided in an exhaust passage;   a burner apparatus provided upstream of the exhaust treatment apparatus to increase an exhaust temperature and comprising at least a fuel addition valve that allows fuel to be added into exhaust and an ignition apparatus for igniting the fuel added via the fuel addition valve;   a detection unit for detecting an amount of intake air in the internal combustion engine; and   a control unit programmed for driving the fuel addition valve open when fuel is added via the fuel addition valve, the control unit increasing an amount of fuel added via the fuel addition valve per unit time beyond a predetermined reference amount when the amount of intake air detected by the detection unit exceeds a predetermined threshold value,   wherein the control unit intermittently drives the fuel addition valve open to intermittently add fuel via the fuel addition valve, with a constant fuel injection rate during the fuel addition valve opening and a constant duration when the fuel addition valve is kept closed, and when the amount of intake air exceeds the threshold value, the control unit carries out set driving comprising a set of a plurality of valve open drive operations, and sets a drive duration for an Nth (N is an integer of at least one) valve open drive operation in the set longer than a predetermined reference duration.   
     
     
         2 . (canceled) 
     
     
         3 . The internal combustion engine according to  claim 1 , wherein the threshold value comprises a plurality of threshold values that increase step by step, and
 the control unit gradually increases a total drive duration for one set every time the amount of intake air increases beyond each of the plurality of threshold values.   
     
     
         4 . The internal combustion engine according to  claim 3 , wherein the control unit increases the drive duration for the Nth valve open drive operation when the amount of intake air exceeds at least one of the plurality of threshold values. 
     
     
         5 . The internal combustion engine according to  claim 3 , wherein the control unit increases the drive duration not only for the Nth valve open drive operation in the set but also for an Mth (M is an integer of at least one) valve open drive operation in the set which is different from the Nth valve open drive operation when the amount of intake air exceeds at least one of the plurality of threshold values. 
     
     
         6 . The internal combustion engine according to  claim 5 , wherein the control unit makes the drive duration for the Nth valve open drive operation be different from the drive duration for the Mth valve open drive operation. 
     
     
         7 . The internal combustion engine according to  claim 1 , wherein the burner apparatus further comprises a pretreatment catalytic converter that oxidizes the fuel added via the fuel addition valve.