Patent EP-0100973-A1 (EP)
Inventor: KUMAR VIRARAGHAVEN SAMPATH
IPC: F15B13/043
Filed: 1983-07-29
Abstract: 1. Proportionally operating electrohydraulically pre-controlled two-way seat valve for hydraulic precision control systems, consisting of a housing (12) with an internal bore (14) having a fluid inlet (18) and a fluid outlet (20), one of which is associated with a front end and the other with a circumferential zone of the internalbore (14) ; a first valve element (30) movable in the internal bore (14) between an and position separating the fluid inlet (70) and the fluid outlet (20) in cooperation with a valve seat (36) at the and of the internal bore (14) and variable positions connecting the inlet and outlet ; a control pressure chamber (39) at the rear face (32) of the first valve element (30) and which is in communication through internal ducts (38, 40) of the first valve element (30) with its front end face (34), on the one hand, and the circumferential zone, respectively, at the level of the fluid opening (20) at the circumference, on the other hand ; a second valve element (52) arranged to be movable in axial alignment with the rear orifice of the duct (40) in communication in the first valve element (30) with the fluid outlet (20) between a position blocking this orifice and a position clearing this orifice ; and an electromagnetic actuating device (64) serving to move the second valve element (52) into its clearing position, the actuating device having an upper zone (62) of the second valve element (52) remote from the first valve element (30) as an armature whose end face (53) forms a working air gap (60) with the axially opposite end face of another axially movable magnetizable part (57) which can be moved axially at the same time by the first valve element (30) by way of a sleeve-shaped portion (56) having in one piece between two magnetizable zones (59, 57) a zone (58) of its length of non-magnetizable material surrounding the upper zone (62) of that second valve element (52) adjoining the working air gap (60), the sleeve-shaped portion (56) and the second valve element (52) being biased towards the blocking position of the two valve elements (30, 52) by springs (78 80) and the movement of the second valve element (52) producing a pressure difference between the control pressure chamber (39) and the inlet chamber (37) in such manner that the first valve element (30) movable in the opening direction by the faed pressure and in the closing direction by the control pressure in the control pressure chamber (39) lifts away from its seat (36), characterised in that the one end face (34) of the first valve element (30) is constantly exposed to the feed pressure (37) and has an effective surface area substantially equal to the surface area of the rear face (32) of the first valve element (30) exposed to the control pressure in the control pressure chamber (39), and the control pressure chamber (39) immediately surrounding the second valve element (52) is enclosed by the sleeve portion (56), which is formed in one piece with the part (57) defining the working air gap (60) and is pressed constantly at its open and against the rear face of the first valve element (30) by the biasing spring (38) in such manner that, with the cooperation of the two springs (78, 80), the two valve elements (30, 52) move practically speaking as one unit, keeping the working air gap (60) constant.