| 摘要 |
PURPOSE:To improve performance, by a method wherein, in case of the captioned device having two pumps, the pumps are individually controlled into a constant-horsepower, and when the discharge pressure of one pump is reduced below a set value, a switch valve device is operated to enhance the discharge pressure-discharge volume properties of the other pump. CONSTITUTION:In case the discharge pressure of a second pump B is higher than the set pressure of a switch valve device D, the first pump A is controlled into a set horsepower by a control valve device E, and the discharge pressure- discharge volume properties thereof is not influenced by the discharge pressure of the second pump B. Thus, the first pump A reliably provides a desired output within a set output range. Besides, in case the discharge pressure of the second pump B becomes lower than the set pressure of the switch valve device D and there is some margin in a motive power source, the properties converting part of the control valve device E corresponding to the first pump A is actuated through operation of the switch valve device D, and the output of the first pump A is controlled into a constant-horsepower by means of a horsepower higher than the set horsepower. |
