| 摘要 |
PURPOSE:To reduce a compressing pressure so as to provide easier starting operation for an engine by forming a small port in communication with the inside of a valve body positioned recess, in the upper part of an exhaust port of a cylinder and opening the port at the side of said valve positioned recess when the valve body is turned backward from the exhaust passage. CONSTITUTION:When an engine is demanded to be started, a valve body 5 is turned on the position shown by a solid line to open a small port 7. Even after a piston 3 closes an exhaust port 2a during the elevating stroke of said piston 3, part of mixture remaining on the upper face of the piston 3 is released through said small port 7 from a combustion chamber 1 into a valve positioned recess 6 which is communicated with an exhaust passage 4 to restrict boost in pressure which acts on the upper face of the piston 3, whereby providing smooth starting operation. Once the engine is started, the valve body 5 is turned to the most projecting position shown by a two-dotted line and then turned reversely in the reopening direction for the port, (namely, in the upward direction in the drawing) in association with increase in power or speed of the engine, setting the characteristic of the engine for high speed run mode. |
