Pressure control device for controlling the flow of a fluid medium

A pressure control device adapted for controlling the flow of a fluid medium and comprising:

• a housing:
• fluid inlet conduit means in said housing;
• fluid return conduit means in said housing, each of which conduit means comprises a valve seat;
• connecting means for link-up with a fluid consuming device;
• a movable valve member having two operating sides
• means mounting said movable valve member to said housing between the valve seats of said inlet and return conduit means so that one operating side of the movable valve member is associated with said inlet conduit means and the other operating side of the movable valve member is associated with said return conduit means;
• an inlet cavity operatively associated with said inlet conduit means and defined on said one operative side of said movable valve member;
• a return cavity, operatively associated with said return conduit means and said connecting means and defined on said other operative side of said movable valve member,
• said movable valve member being displaceable for controlling the cross sectional areas of flow through said inlet and said return conduit means, respectively, in an opposite sense;
• and
• biassing means for applying a resetting force to said movable valve member to reduce fluid influx,
• a solenoid including a magnetic core and an armature between which an excitor winding is disposed, said magnetic core and armature having opposite faces of frustoconical shape which extend substantially parallel to each other, said solenoid being disposed within the inlet cavity and about the inlet conduit sleeve
• means connected to the armature and the movable valve member for transmitting a force to the movable valve member generated by the solenoid, said force serving to adjust the resetting force to the hydraulic pressures prevailing in the device, said last mentioned means comprising an annular sleeve located coaxially within the magnetic core, said sleeve being resiliently supported by an annular membrane connected to the housing
• wherein said fluid inlet conduit means comprises a sleeve which projects into the inlet cavity and which bears one of the valve seats at its free end,
• wherein said fluid return conduit means comprises a sleeve which projects into the return cavity and which bears the other of the valve seats at its free end
• wherein the valve seat cross sectional area of said return conduit sleeve is smaller than that of said inlet conduit sleeve, whereby a force resulting from the inlet fluid pressure in said inlet cavity and the cross sectional flow area of said inlet conduit sleeve and acting on said one operative side of said movable valve member is opposed by said resetting force as well as by a force resulting from the fluid pressure in said return cavity and said connecting means and from the area difference between the valve seat cross sectional areas of said inlet and said return conduit sleeves and acting on said other operative side of said movable valve member thereby achieving a hydraulic resetting effect.