| 摘要 |
PURPOSE:To most suitably change compression ratio, by inserting a hydraulically driven subpiston into a subcylinder communicated to a combustion chamber and adjusting pressure of oil in a pressure oil chamber in the subpiston through a spill ring interlocking to an operational condition of an engine. CONSTITUTION:If an engine load decreases to increase intake pipe negative pressure introduced to a negative pressure chamber 23 of a diaphragm mechanism 20, a diaphragm 22 is moved upward against a spring 24, and this causes a spill ring 17 to move to a position as shown by a chain line in the drawing through a rod 21 and lever 18, then a spill port 16 provided to a stem 11 integrally formed with a subpiston 9 is closed. Then pressure of working oil supplied into a pressure oil chamber 12 from a port 14 rises to displace the piston 9 downward. And if the piston 9 is displaced to a position where the port 16 is opened, working fluid beings to flow out from the port 16, at a point of time when this outflow amount and supply amount to the chamber 12 are balanced, the piston 9 is stopped to change compression ratio. |
