| 摘要 |
PROBLEM TO BE SOLVED: To steadily improve deterioration of fuel consumption in a light load range, and also to further improve charging efficiency in a heavy load range without increasing its size and cost, when an exhaust turbo-supercharger 10 having a compressor 10b directly connected to an exhaust gas turbine 10a is applied to a uniflow type 2-stroke internal combustion engine having an exhaust valve 6 at the top of a cylinder 2 containing a piston 3 therein and a scavenging port 8 at the lower part of the cylinder. SOLUTION: A main exhaust passage 15 from the exhaust valve 6 communicates with an exhaust gas inlet of the exhaust gas turbine 10a by means of a change-over valve 20 in an early period L3 in an open period L2 of the exhaust valve 6, and an atmospheric air inlet side of the compressor 10b in a late period L4 in the open period L2 of the exhaust valve 6. At that time, in the heavy load range, the communication is shut off, and part of the compressed air compressed by the compressor 10b is pushed into the cylinder 2 from the exhaust valve 6 via a by-pass passage 21 and changing-over means 22.
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