Exhaust heating device for internal combustion engine and control method therefor

Abstract

An exhaust heating device for heating an exhaust gas led to an exhaust purifying device from an engine is disposed in a second exhaust passage that is located upstream of a confluent portion of a first exhaust passage connected through a turbine of a first turbocharger to the purifying device and the second passage connected to the purifying device through a turbine of a second turbocharger used primarily in a lower speed range of the engine than the first turbocharger in a state of bypassing the turbine of the first turbocharger and downstream of the turbine of the second turbocharger. A valve for regulating a flow of the exhaust gas in the second passage is disposed in the second passage that is located downstream of a branched portion of the first and second passages and upstream of the turbine of the second turbocharger.

1 - 7 . (canceled) 
     
     
         8 . An exhaust heating device for an internal combustion engine for heating an exhaust gas introduced in an exhaust purifying device from the internal combustion engine in which a first exhaust turbocharger and a second exhaust turbocharger used primarily in a lower-rotation region of the internal combustion engine than the first exhaust turbocharger are incorporated, wherein
 the exhaust heating device is provided in a second exhaust passage positioned upstream of a confluent portion of a first exhaust passage connected through an exhaust turbine of the first exhaust turbocharger to the exhaust purifying device and the second exhaust passage connected through an exhaust turbine of the second exhaust turbocharger to the exhaust purifying device in a state of bypassing the exhaust turbine of the first exhaust turbocharger and downstream of the exhaust turbine of the second exhaust turbocharger, and   a valve for regulating a flow of an exhaust gas in the second exhaust passage is provided in the second exhaust passage downstream of a branched portion of the first exhaust passage and the second exhaust passage and upstream of the exhaust turbine of the second exhaust turbocharger.   
     
     
         9 . The exhaust heating device for the internal combustion engine as claimed in  claim 8 , wherein an opening/closing valve for opening/closing the first exhaust passage is provided in the first exhaust passage downstream of the branched portion of the first exhaust passage and the second exhaust passage and upstream of the exhaust turbine of the first exhaust turbocharger. 
     
     
         10 . The exhaust heating device for the internal combustion engine as claimed in  claim 8 , wherein the exhaust heating device includes a fuel supply valve for supplying fuel to the second exhaust passage, and an igniting unit for igniting and conflagrating the fuel supplied from the fuel supply valve to the second exhaust passage. 
     
     
         11 . The exhaust heating device for the internal combustion engine as claimed in  claim 9 , wherein the exhaust heating device includes a fuel supply valve for supplying fuel to the second exhaust passage, and an igniting unit for igniting and conflagrating the fuel supplied from the fuel supply valve to the second exhaust passage. 
     
     
         12 . The exhaust heating device for the internal combustion engine as claimed in  claim 10 , wherein an oxidation catalytic converter is provided in the exhaust passage between the igniting unit and the exhaust purifying device. 
     
     
         13 . The exhaust heating device for the internal combustion engine as claimed in  claim 11 , wherein an oxidation catalytic converter is provided in the exhaust passage between the igniting unit and the exhaust purifying device. 
     
     
         14 . The exhaust heating device for the internal combustion engine as claimed in  claim 10 , wherein in a case of igniting the fuel using the igniting unit, an opening of the valve is regulated such that a flow of the exhaust gas in the second exhaust passage is less than a flow of the exhaust gas in the first exhaust passage. 
     
     
         15 . The exhaust heating device for the internal combustion engine as claimed in  claim 11 , wherein in a case of igniting the fuel using the igniting unit, an opening of the valve is regulated such that a flow of the exhaust gas in the second exhaust passage is less than a flow of the exhaust gas in the first exhaust passage. 
     
     
         16 . The exhaust heating device for the internal combustion engine as claimed in  claim 12 , wherein in a case of igniting the fuel using the igniting unit, an opening of the valve is regulated such that a flow of the exhaust gas in the second exhaust passage is less than a flow of the exhaust gas in the first exhaust passage. 
     
     
         17 . The exhaust heating device for the internal combustion engine as claimed in  claim 13 , wherein in a case of igniting the fuel using the igniting unit, an opening of the valve is regulated such that a flow of the exhaust gas in the second exhaust passage is less than a flow of the exhaust gas in the first exhaust passage. 
     
     
         18 . A control method of the exhaust heating device as claimed in  claim 10 , comprising the steps of:
 determining presence/absence of activation of the exhaust purifying device;   detecting a rotational speed of the internal combustion engine;   setting an opening of the valve based upon the detected rotational speed of the internal combustion engine; and   in a case where it is determined that the exhaust purifying device is not activated, driving the valve to open in the set opening for flowing the exhaust gas of a predetermined flow in the second exhaust passage, and operating the exhaust heating device.   
     
     
         19 . A control method of the exhaust heating device as claimed in  claim 11 , comprising the steps of:
 determining presence/absence of activation of the exhaust purifying device;   detecting a rotational speed of the internal combustion engine;   setting an opening of the valve based upon the detected rotational speed of the internal combustion engine; and   in a case where it is determined that the exhaust purifying device is not activated, driving the valve to open in the set opening for flowing the exhaust gas of a predetermined flow in the second exhaust passage, and operating the exhaust heating device.   
     
     
         20 . The control method of the exhaust heating device as claimed in  claim 18 , wherein in a case where it is determined that the exhaust purifying device is not activated, the step of driving the valve to open in the set opening for flowing the exhaust gas of a predetermined flow in the second exhaust passage and operating the exhaust heating device includes a step of driving the first opening/closing valve such that the first exhaust passage is in a fully opened state. 
     
     
         21 . The control method of the exhaust heating device as claimed in  claim 19 , wherein in a case where it is determined that the exhaust purifying device is not activated, the step of driving the valve to open in the set opening for flowing the exhaust gas of a predetermined flow in the second exhaust passage and operating the exhaust heating device includes a step of driving the first opening/closing valve such that the first exhaust passage is in a fully opened state.