Patent ID: 8555772

Claim:
A directional control valve for controlling working cylinders, servomotors, or an actuating cylinder of a turbo-machine such as gas and steam turbines, the directional control valve comprising: a force-regulated magnet ( 1 . 9 ); and a hydraulic unit including: a pilot piston; and a control housing ( 2 ), in which said pilot piston ( 3 ) is situated so it is displaceable in an axial direction of the directional control valve, said control housing ( 2 ) having at least three hydraulic connections including a first pressure connection (P) configured for connection to a hydraulic pressure supply, at least one consumer connection (A, B) configured for connection to the working cylinder or the servomotor, and a tank connection (T) configured for connection to a hydraulic tank, a flow cross-section between the hydraulic connections (A, B, P, T) being variable by displacement of said pilot piston ( 3 ); an actuating unit ( 1 ) including: a control piston ( 1 . 1 ), displaceably located in the control housing ( 2 ) or in a flange ( 1 . 2 ) attached on the control housing ( 2 ), said control piston being displaceable using said force-regulated magnet ( 1 . 9 ), said control piston being configured to vary the flow cross-section between an actuating unit pressure connection (p), an actuating piston connection (a) and an actuating tank connection (t) by displacement; an actuating piston ( 1 . 5 ), which is non-positively and/or positively connected on said pilot piston ( 3 ) such that said actuating piston is displaceable in the axial direction of the directional control valve, said actuation piston divides a piston room ( 1 . 10 ) into a first piston room chamber and a second piston room chamber ( 1 . 11 , 1 . 12 ) which are sealed to one another, the first piston room chamber ( 1 . 11 ) being hydraulically connected to the actuating piston connection (a); a first elastic element configured to act against a hydraulic pressure force in the first piston room chamber ( 1 . 11 ), said actuating piston ( 1 . 5 ) being connected by way of said first elastic element to said control piston ( 1 . 1 ) or being supported thereon; a second elastic element configured to act against the hydraulic pressure force in the first piston room chamber ( 1 . 11 ), said actuating piston ( 1 . 5 ) being connected by said second elastic element to the control housing ( 2 ) or the flange ( 1 . 2 ) or being supported thereon; and a conductor for the exact positioning of said pilot piston ( 3 ), said conductor being situated in a magnetic field of said force-regulated magnet ( 1 . 9 ), said force-regulated magnet being an electromagnet configured for electrical activation, said conductor being electrically connected to one of said electromagnet ( 1 . 9 ) and a control unit for control of said electromagnet ( 1 . 9 ) such that the magnetic force and the position of said control piston ( 1 . 1 ), said actuating piston ( 1 . 5 ), and said pilot piston ( 3 ) are regulated by way of a Hall voltage generated in said conductor.