| 摘要 |
PURPOSE:To simplify a mechanism, reduce a level of noise and control an engine to optimum operation, by forming a fluid chamber from a working piston, providing an accumulator, communicated to the fluid chamber through a lead pipe, and interposing an accumulator control valve in the lead pipe. CONSTITUTION:Pressure of oil, delivered from a hydraulic pump 11 driven by a motor 10, is stored in an accumulator 12. If a hydraulic pressure control valve 14 is switched to a position II by action of a cam 15, the accumulator 12 and oil chamber 9 of an exhaust hole control cylinder 1 are communicated, and a working piston 7 is lowered, also an exhaust hole opening and closing piston 5 is lowered to close exhaust holes 4. While if the control valve 14 is returned to a positionIby action of the cam 15, pressure oil in the oil chamber 9 is returned to a tank 21, and oil pressure in the oil chamber 9 is equalized to the atmospheric pressure. Accordingly, the exhaust hole opening and closing piston 5 is moved upward to open the exhaust holes 4. |
