Hydrolux S.a.r.l.

Hans Schwelm

A position controlled proportional directional control valve has a main control piston for controlling flow between passages to a pump, a tank, and to passages which may be connected to an operative device, such as a hydraulic motor. The main control piston may be moved in one direction by an operating piston slidably disposed in a centring flange which serves as a mechanical stop for movement of the main control piston in the opposite direction. Acting on the end of the main control piston opposite the operating piston is a centring piston having one end in a pilot control chamber, and which may urge the main control piston against the centring flange either by pressure fluid in the chamber, or upon failure of pressure, by the spring in the chamber. A pilot control valve, under the control of an electrical magnet, moves proportionally to the current in the electrical magnet, to admit fluid under pressure from a pump passage into the pilot control chamber.

Position-controlled proportional directional valve

A proportional valve comprises two electrically actuated proportional throttle valves, each having an outlet connected to a non-return valve, to each of which a seat valve is connected, each seat valve being pilot-controlled by one of the proportional throttle valves; the electric actuation of the proportional throttle valves proportionally controls and regulates the functions of a hydraulic cylinder. The two throttle valves and the two seat valves are mounted on a housing block which has a planar face at which are connections to a pressure line, a tank line and working lines.

Proportional seat-type 4-way valve

The throttle-part of the valve comprises a two-way seat valve with a follow-up throttle valve (8), which is driven by a differential guide piston (12) and an edge control system (20). The guide piston is pressurized via a pressure-spring (16) in a pressure-spring compartment in the direction of the closed position of the edge control system. The drive is effected via a pilot line A which pressurizes or depressurizes the pressure-spring compartment (18) via a proportional directional control valve (6), while the position of the guide piston (12) is determined by an inductive displacement transducer.

Adjustable proportional throttle-valve with feedback

The main control piston (8) is controlled hydraulically by pilot control slide valves, operated in each case via two control magnets (4, 6) with force build-up proportional to the control current. In the case of failure of the electrical activation, the valve is always positioned in the center position by pressure centering and in the case of failure of the pilot control pressure it is positioned in the center position by spring centering.

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Luxembourg-Domeldange, Luxembourg

Hans Schwelm