| 摘要 |
PURPOSE:To improve the performance of an engine over the entire operational range of the same, by forming a volume-varied subsidiary chamber in the side wall of a combustion chamber consisting of a main combustion chamber of a recess formed in the top surface of a piston or the inner wall surface of a cylinder head and a remaining squish zone. CONSTITUTION:In an engine, in which a combustion chamber 5 consisting of a recess 4 formed partially in the inner wall of a cylinder head 2 and a small- gas squish zone 6 formed continuously with the recess 4 are defined between the top surface of a piston 3 and the inner wall surface of the cylinder head 2 when the piston 3 comes to the top dead point, a volume-varied subsidiary chamber 13 having a variable compression piston 14 fitted therein in a freely slidable manner is formed in the side wall of said recess 4 in which an intake port 7 is opened. The piston 14 is moved by a driving mechanism 15 including a diaphragm means 16 which is operated by the negative intake pressure developed in an intake passage 9. With such an arrangement, the compression ratio of the engine is increased by moving the piston 14 forward, for instance, at the time of low-load operation when the negative intake pressure is high, whereby it is enabled to obtain a high thermal efficiency and excellent combustion stability. |
