| 摘要 |
A piston (25) which is rigidly connected to a valve cone (24) is arranged in a cylinder (5, 8). The valve cone (24) co-operates with a valve seat (26) in a duct (38). By means of a hydraulic relay (70), either the higher pressure (P1) which prevails upstream of the valve seat (26) or the lower pressure (P2) which prevails downstream of the valve seat (26) can be applied to the side faces (42, 43) of the piston (25). Depending on the pressure applied, the piston (25) moves up or down. The control commands are transmitted to the pilot valve by means of magnetic currents. The control commands are in the form of positive or negative direct current pulses, which are sent to an electromagnet (1) which in turn generates a polarized magnetic flux by means of the current pulses. The magnetic current flows through a core (3) into the interior of the driving mechanism, where the various switching operations are then carried out by the displacement of a valve core (9) and a switching element (11). The piston (25) and the piston rod (26) are sealed from the internal surface of the cylinder by means of closed roll-type membranes (15, 19) the interior of which is connected to the higher pressure (P1), which thrusts the roll-type membrane against the cylinder wall. |
