Valve adjustment unit for hydraulic proportional-response valve

A valve adjustment device adapted for attachment to an electronically controlled hydraulic proportional-response valve which has a valve body and a cooperating valve plunger defining a common longitudinal axis for said valve and the valve adjustment device, said device comprising in combination:

• a proportional-response magnet unit of the solenoid-type having a magnet coil which surrounds an axially movable armature and a magnet unit housing which encloses the magnet coil and the armature, while forming a sealed displacement cavity for the armature, the magnet unit housing having a forward axial side on which it is sealingly attachable to said body of the proportional-response valve, for a coaxial drive connection between the magnet armature and the valve plunger and for hydraulic communication between the armature displacement cavity and a fluid-filled interior space of the proportional-response valve;
• and
• an inductive displacement transducer arranged coaxially with the magnet unit, on its rearward axial side, the displacement transducer including a transducer coil which is fixedly mounted outside the magnet unit housing, in alignment with the unit axis, and a permanently magnetized transducer magnet which is movable in the central aperture of the transducer coil, being carried by a rod which extends axially rearwardly from the armature;
• and wherein
• the magnet unit housing has a tubular rearward extension which reaches through the aperture of the transducer coil, while forming an enclosed magnet displacement cavity around the transducer magnet;
• and
• the armature displacement cavity of the magnet unit communicates with the magnet displacement cavity of the displacement transducer via a gap around the magnet-carrying rod, with the result that the transducer magnet is, in effect, enclosed within the magnet unit housing and surrounded by the same hydraulic fluid which surrounds the armature.