To provide a temperature raising system suppressing deterioration of exhaust emission when burning fuel added to exhaust gas flowing in an exhaust passage during a request for raising temperature of an exhaust emission control catalyst.
When the temperature rise of a DPNR (Diesel Particulate NOx Reduction) catalyst 4 is requested, fuel combustion control is performed so that fuel added by a fuel adding valve 5 is burnt by ignition of a glow plug 6. A small-diameter catalyst 7 is so disposed that combustion gas generated in the fuel combustion control and fuel contained in the combustion gas are introduced. Fuel is added by the fuel adding valve 5 so that when the fuel combustion control is performed, an air-fuel ratio of exhaust gas passing through the small-diameter catalyst 7 is made to be rich, and an air-fuel ratio of the whole exhaust gas led to flow into the DPNR catalyst 4 is made to be lean.
Mayuko Wakuda
Kazunobu Sera
Tsutomu Toyama
Takehiko Sekine
Koichiro Sakai
Fuminori Miyashita
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