Patent ID: 7779629

Claim:
A pressure accumulating apparatus provided with: a power source that generates power; a cylinder; a first cylindrical piston with a bottom that is accommodated in the cylinder in an airtight or liquid-tight and slidable manner and has one end closed and the other end opened in the axial direction; a second piston that slidably enters into the first cylindrical piston from the open end in an airtight or liquid-tight and slidable manner for forming a first chamber in the first cylindrical piston at the side of its closed end and forming a second chamber in the cylinder at the side of the open end of the first cylindrical piston; a piston rod that is connected to the second piston for causing the second piston to move in a reciprocating manner in the cylinder and in the first cylindrical piston in the axial direction by its reciprocating movement in the axial direction; a restricting rod that is connected to the second piston and projects from the closed end of the first cylindrical piston, the restricting rod allowing the reciprocating movement of the second piston to the first cylindrical piston within the predetermined range and displacing integral with the first cylindrical piston due to the engagement with the first cylindrical piston for restricting the displacement of the second piston to the first cylindrical piston outside the predetermined range; an intake valve that is connected to the first chamber for inspiring low-pressure fluid into the first chamber when the second piston is displaced toward the open end of the first cylindrical piston; a discharge valve that is connected to the first chamber for discharging the high-pressure fluid in the first chamber when the second piston is displaced toward the closed end of the first cylindrical piston; pressure accumulating means that accumulates the high-pressure fluid discharged by the discharge valve; power transmission means that causes the piston rod to move in a reciprocating manner in the axial direction with a predetermined range in accordance with the power from the power source; and the restricting means that cuts off the transmission of the power from the power source to the piston rod by the power transmission means, the restricting means being configured to direct the high-pressure fluid at the downstream side of the discharge valve into the second chamber and to urge the first cylindrical piston toward its closed end when the fluid pressure at the downstream side of the discharge valve becomes higher than the fluid pressure at the upstream side of the intake valve by a predetermined pressure.