| 摘要 |
PURPOSE:To permit to cool the piston simply by a method wherein a guide plate, slanted obliquely and downwardly from the exhaust port side toward a scavenging port side, is provided in the piston to blow mixture against the exhaust port side inner surface of the piston in conjunction with the ascendance and descendance of the piston. CONSTITUTION:When the engine 1 is started, the mixture, supplied to the combustion chamber 7, is compressed and ignited by a spark plug 13 while a pressure in a crankcase is reduced. Then, the mixture, from a carburettor 8a, opens a non-return valve 4b and flows into the crankcase 3 when the air supplying port 5e of the piston is aligned with the suction port 4a of the cylinder 4. The guide plate 14 is provided in the piston 5 so as to be slanted downwardly and obliquely from the exhaust port side 5g toward the scavenging port side 5h and the lower rim thereof is extended to the lower side of the air supplying port 5e. Accordingly, the mixture ascends along the guide plate 14, collides against the inner surface of the piston at the exhaust port side 5g and cools the piston, thereafter, the mixture is turned and flows into the crankcase 3 through a gap 15. |
