4 CYCLE ENGINE

摘要

A 4 cycle engine comprises a blow down pressure wave supercharge mechanism (40) for pressure supplying exhaust gas into a second cylinder #1 by making a pressure wave (blow down pressure wave) from the combustion chamber when the exhaust valve of a first cylinder #4 is open act on the exhaust port (1e) of the second cylinder #1 during reopen period of the exhaust valve of the second cylinder #1, and a mask member (50) for suppressing mixture of exhaust gas (EGR gas) pressure supplied into the second cylinder #1 with fresh air flowing in from the intake port (1d) wherein a first temperature layer (T1) of high temperature containing a large quantity of EGR gas in fresh air, and a second temperature layer (T2) of lower temperature than the first temperature layer (T1) containing a smaller quantity of EGR gas in fresh air as compared with the first temperature layer (T1) are formed in the second cylinder #1.