| 摘要 |
PROBLEM TO BE SOLVED: To improve efficiency by preventing generation of wasteful time necessary for only suction operation in a reciprocating piston pump. SOLUTION: A plurality of reciprocating piston pumps 3 are disposed side by side. In each of the piston pumps 3, a volume inside a cylinder 1 is repeatedly increased or decreased by a relative repetitive motion between the cylinder 1 and a piston 2, and suction/discharge of fluid through a pair of suction ports 1b, 1d and a pair of discharge ports 1a, 1c provided in the cylinder 1 are carried out in any processes of the relative repetitive motion between the cylinder 1 and a piston 2. In the plural piston pumps 3, a pressure area ratio between an outward route and a homeward route of one of the pistons 2 and that of the other piston 2 (A1:A2 and B1:B2) are approximately equal to each other, and the plural reciprocating piston pumps 3 are driven by at least a single motor 4 via a gear mechanism. By changing a gear ratio of the gear mechanism, a reciprocating speed ratio of the plural reciprocating piston pump 3 is changed, thereby determining a discharge ratio of the fluid.
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