| 摘要 |
PURPOSE:To improve startability by multipoint-connecting an exhaust treating device where an external combustor and catalyst are combined to an exhaust passage, controlling to conduct exhaust gas to the exhaust treating device when exhaust treatment is needed, and returning some of exhaust after exhaust treatment to the air charging side. CONSTITUTION:An exhaust passage 22 connected to a turbine inlet portion of an exhaust turbo charger 23 is divided into passages 30a, 30b, and an external combustor 32 comprising a burner 33 and catalyser 34 is multipoint-connected to the passage 30a. Partition valves 40, 41 for opening and closing the passages 30a, 30b are disposed in the vicinity of the upstream side of a portion of the exhaust passage 22 where the external combustor 32 is multi-point connected, and the respective valves 40, 41 are controlled by a control device 44 to close when an engine is stopped and at the time of low load when blue smoke is generated. An exhaust return passage 54 for returning purified exhaust gas subjected to exhaust gas treatment by catalyst 34 to an intake manifold is provided between the external combustor 32 and the intake manifold 27 and a switching valve 55 which is opened only at the time of starting operation is interposed in the midway of the passage 54. |
