| 摘要 |
<p>A method of operating, from a control post, a valve which is situated at a reception post a great distance from the control post, incorporates putting under pressure a hydraulic jack connected to the valve to open it. The jack acts against a spring tending to return the valve to the closed position, when the jack is under low pressure. The control post includes a source of hydraulic fluid under pressure from which the fluid is fed to the reception post through a single pipe of small section. A hydraulic switch mechanism is interposed on the pipe at the control station, allowing the pipe to be put selectively under pressure or purged. The process consists of stocking at the reception post a reserve of hydraulic energy accumulated from the fluid fed at low rate through the pipe, and controlling the switching of a feed-purge distributor interposed at the reception station between the reserve and the jack by a manostatic device which is sensitive to the pressure in the pipe at its entry to the reception station. The jack can thus be fed at high rate from the reserve so that it opens the valve rapidly, and can be put under low pressure so that it is relaxed and closes the valve rapidly, according to the pressure applied to the pipe at the control post and detected by the manostatic device. Problems associated with the provision of a connecting pipe of large flow area between the control post and the reception post are avoided. These arise in existing appts. because the pipe acts not only to transmit an instruction but also to transmit power by feeding the jack from the source at the control post. In the present process, the hydraulic energy is stored at the reception post and the connecting pipe is used only to transmit instructions and can therefore be of small section.</p> |
