PURPOSE: To improve the responsibility of a turbine and to reduce hydrocarbon in exhaust gas during a light load by providing a communicating passage to mutually connect secondary exhaust ports with a control valve opening during a heavy load.
CONSTITUTION: The primary exhaust ports 12a, 12b are established ealier than the secondary exhaust ports 13a, 13b in their opening and closing time, and connected to a turbine scroll 31a on a primary side of an exhaust turbosupercharger 30. The secondary exhaust ports 13a, 13b are mutually connected through a communicating passage 14, which is connected to the turbine scroll 31b on a secondary side through an exhaust gas conducting passage 15, which is provided with a control valve 16 opening during a heavy load. Thus blow- down of exhaust gas from the primary exhaust ports 12a, 12b can improve the responsibility of an exhaust turbosupercharger 30 and afterburn the exhaust gas containing a large quantities of unburnt component during a light load.
UCHIDA HIROYASU
YAMANE HISAYUKI
YAMAGATA NAOYUKI
