| 摘要 |
PURPOSE:To realize smooth speed control by a simple constitution wherein a single variable delivery pump, which can control its delivery steplessly, and a plurality of constant delivery pumps are combined with each other. CONSTITUTION:When signal voltage is outputted from a control signal generator 14, a proportional control valve 4 is driven through an amplifier 14 so as to change the tilting angle of the swash plate of a variable delivery pump 1, resulting in controlling delivery in proportion to signal voltage. When input signals are respectively applied so as to excite solenoids 5A and 6A of solenoid valves 5 and 6, which are respectively provided on the delivery sides of pumps 2 and 3, fixed amount of oils are delivered from the pumps 2 and 3 and fed through non-return valves 8 and 9 to a pipe line L1. From the set value F, the value of input signal voltage to the pump 1 is determined and the excitation or demagnetization of the respective solenoids 5A and 6A of the solenoid valves 5 and 6 are judged. Thus, flow rate is controlled steplessly, freely and automatically, from small flow rate to large flow rate, within the range of the sum of the maximum deliveries of the respective pumps only by these pumps 1, 2 and 3. |
