JPS6466474A - Piston-type fluid machine - Google Patents

Abstract

PURPOSE:To obtain high efficiency of the captioned machine for super high pressure fluid as well by forming an annular space at the part except for the inner peripheral surface of a cylinder, which is situated on the opposite side of the piston-inserting-side, together with applying discharge pressure to this space. CONSTITUTION:A cylinder block 5 is firmly held by a casing 12 of a pump, while a plurality of cylinders 1 are inserted in this block 5. A piston 2 is inserted into the cylinder 1 in such a manner that the piston 2 slides freely. An annular space 14 is formed at the part except for the inner peripheral surface of the end surface of the cylinder, which is situated on the opposite side of the piston-inserting-side (fluid chamber side 9). The space 14 has a depth lin the axial direction of the piston 2 and is concentric with the inner peripheral surface of the cylinder. The diameter d of the annular space is formed on the outer peripheral side of the position of both a suction check valve 3 and a discharge check valve 4. Since a connecting passage 15, which acts the same pressure as that in the fluid chamber 9 on this space 14, is formed, the gap between the piston 2 and the cylinder 1 can be made small, while the amount of leak can largely be reduced.