| 摘要 |
PURPOSE:To change compression ratio without causing the worsening of combustion performance, by inserting a subpiston into a subcylinder communicated to a combustion chamber and displacing the subpiston through operation of an oil pressure regulating spill ring further discharging leaked oil to the atmospheric side. CONSTITUTION:If a spill ring 17 is moved by an actuator 22 to a position as shown by a chain line in the drawing to close a spill port 16 provided to a stem 11 integrally formed with a subpiston 9, pressure of working fluid supplied into a pressure oil chamber 12 from a port 14 rises to displace the subpiston 9 downward. Then if the subpiston 9 is displaced to a position where the port 16 is opened, working fluid begins 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 subpiston 9 is stopped to change compression ratio. At an explosion stroke, the working fluid in the chamber 12 is leaked to a slide contact part between the subpiston 9 and a subcylinder 7, and this leaked oil flows out to the outside of the subcylinder 7 through an annular groove 19 and a through hole 20. |
