Exhaust heating apparatus for internal combustion engine and control method for the same

Abstract

An exhaust heating apparatus ( 37 ) according to the present invention, for heating exhaust being led to an exhaust emission purifier ( 30 ) from an internal combustion engine ( 10 ) in which a first exhaust turbocharger ( 28 ) and a second exhaust turbocharger ( 29 ) that is mainly used in a lower rotational speed range of the engine than the first turbocharger are incorporated, is arranged in a first exhaust passage ( 26 f ) that is located further upstream than a confluent portion ( 27 c ) of the first exhaust passage, which passes through an exhaust turbine ( 28 b ) of the first turbocharger and continues to the exhaust emission purifier, and a second exhaust passage ( 26 s ), which goes around the exhaust turbine of the first turbocharger and passes through an exhaust turbine ( 29 b ) of the second turbocharger and continues to the exhaust emission purifier, and further downstream than the exhaust turbine of the first turbocharger.

1 .- 10 . (canceled) 
     
     
         11 . An exhaust heating apparatus for heating exhaust being led to an exhaust emission purifier from an internal combustion engine in which includes a first exhaust passage passing through an exhaust turbine of a first turbocharger and continuing to the exhaust emission purifier, a second exhaust passage being arranged in parallel with the first exhaust passage, passing through an exhaust turbine of a second turbocharger and continuing to the exhaust emission purifier, the second turbocharger being mainly used in a lower rotational speed range of the engine than the first turbocharger, and a valve being capable of adjusting a flow of exhaust that flows in the first exhaust passage is arranged in the first exhaust passage further on the upstream side than the exhaust turbine of the first turbocharger, wherein
 the exhaust heating apparatus is arranged in the first exhaust passage that is located further upstream than a confluent portion of the first and second exhaust passages being arranged in parallel between the engine and the exhaust emission purifier, and further downstream than the exhaust turbine of the first turbocharger.   
     
     
         12 . The exhaust heating apparatus for the internal combustion engine as claimed in  claim 11 , wherein the exhaust heating apparatus comprises a fuel supply valve for supplying fuel to the first exhaust passage, and ignition means for igniting and burning fuel that was supplied from the fuel supply valve to the first exhaust passage. 
     
     
         13 . The exhaust heating apparatus for the internal combustion engine as claimed in  claim 12 , wherein an oxidation catalyst is arranged in the exhaust passage between the ignition means and the exhaust emission purifier. 
     
     
         14 . The exhaust heating apparatus for the internal combustion engine as claimed in  claim 11 , wherein when fuel is supplied to the first exhaust passage from the fuel supply valve, an opening of the valve is adjusted so that the flow of exhaust flowing in the first exhaust passage becomes less than a flow of exhaust that flows in the second exhaust passage. 
     
     
         15 . A control method for the exhaust heating apparatus as claimed in  claim 11 , comprising the steps of:
 detecting a rotational speed of the internal combustion engine; and   flowing a predetermined amount of exhaust in the first exhaust passage and actuating the exhaust heating apparatus when the detected rotational speed of the engine is equal to or less than a predetermined rotational speed, or when in an operating state where the first exhaust passage can be shut off.   
     
     
         16 . An exhaust heating apparatus for heating exhaust being led to an exhaust emission purifier from an internal combustion engine in which includes an exhaust passage passing through an exhaust turbine of the first turbocharger and continuing to the exhaust emission purifier, a first exhaust bypass going around the exhaust turbine of the first turbocharger and continuing to the exhaust passage, a first exhaust bypass valve being capable of adjusting a flow of exhaust that flows in the first exhaust bypass, a second exhaust bypass that is arranged in parallel with respect to the exhaust passage being located further upstream than the first exhaust bypass so that the second exhaust bypass goes around an exhaust turbine of a second turbocharger that is mainly used in a lower rotational speed range of the engine than the first turbocharger, the exhaust turbine of the second turbocharger being arranged in the exhaust passage further on the upstream side than the first exhaust bypass, and a second exhaust bypass valve being capable of adjusting a flow of exhaust that flows in the second exhaust bypass, wherein
 the exhaust heating apparatus is arranged in the exhaust passage that is located further upstream than a confluent portion of the exhaust passage and the first exhaust bypass, and further downstream than the exhaust turbine of the first turbocharger.   
     
     
         17 . The exhaust heating apparatus for the internal combustion engine as claimed in  claim 16 , wherein the exhaust heating apparatus comprises a fuel supply valve for supplying fuel to the exhaust passage, and ignition means for igniting and burning fuel that was supplied from the fuel supply valve to the exhaust passage. 
     
     
         18 . The exhaust heating apparatus for the internal combustion engine as claimed in  claim 16 , wherein an oxidation catalyst is arranged in the exhaust passage between the ignition means and the exhaust emission purifier. 
     
     
         19 . The exhaust heating apparatus for the internal combustion engine as claimed in  claim 16 , wherein when fuel is supplied to the exhaust passage from the fuel supply valve, the opening of the first exhaust bypass valve is adjusted so that the flow of exhaust that flows in the exhaust passage becomes less than the flow of exhaust that flows in the first exhaust bypass. 
     
     
         20 . A control method for the exhaust heating apparatus as claimed in  claim 16 , comprising the steps of:
 detecting a rotational speed of the internal combustion engine; and   flowing a predetermined amount of exhaust toward the exhaust turbine of the first turbocharger when the detected rotational speed of the engine is equal to or less than a predetermined rotational speed, or when in an operating state where the first exhaust bypass can be full opened.