| 摘要 |
PURPOSE:To reduce the equipment cost by providing a switching means which makes selective changeover on connections of two main pipe lines. to suction port and the discharge port of each of fixed-displacement pumps. CONSTITUTION:Pipe passages 5, 23, 10, 27, 9, 21, 25, 14 connect the intake ports and the discharge ports of fixed pumps 1 and 2 to two main pipe lines 3 and 4 and solenoid valves 22, 26, 20 and 24 each having two-position and three-port for selectively switching connections of said pipe passages are disposed in said pipe passages. The number of the fixed-displacement pumps 1 and 2 will then become a minimum and a variety of flow rates can be obtained so that the e equipment cost can be made smaller than that of the conventional one. |
