Patent EP-0043090-A1 (EP)
Inventor: LEIKAUF UDO
IPC: B30B15/14
Filed: 1981-06-23
Abstract: 1. Servo-controlled 3/2-way seated valve, preferably a press safety valve, with a control port (15) for the control medium, an inlet port (7) and at least one outlet port (8) for the through-flowing medium, a housing (3) accomodating these ports having displaceably mounted within it a tubular control piston (5), one end of which constitutes a first occluding member (20) which, at full pressure in the control port (15), bears on a first valve seat (20) and is subject to the pressure of the through-flowing medium, characterized in that the cavity (16) in the control piston (5) at its end which is towards the first valve seat (20) is occluded by means of a recessed end member (18) and is connected via first radial ports (50) to a first annular housing space (52) disposed on the back pressure side between the control piston (5) and the housing (3) and that displaceably mounted in the control piston (5) and loaded by a thrust spring (39) there is an auxiliary piston (6), the thrust spring (39) being inserted between the recessed end member (18) of the control piston (5) and the associated end of the auxiliary piston (6), recessed end member (18) constituting the first occluding member, the associated first valve seat (20) of which is disposed in the valve body (3) and in that furthermore the outer rim (45) of the control piston (5) constitutes a second occluding member (24) which co-operates with a second valve seat (25) of the valve body (3) and in that that end of the auxiliary piston (6) which bears on the thrust spring (39) forms a third occluding member (27) which co-operates with a third valve seat (28) which is disposed at the transition between the cavity (16) of the control piston (5) and the first radial ports (30) thereof and in that the auxiliary piston (6) has in the region of the third occluding member (27) first radial ports (32) which are connected to second radial ports (33) in the region of the rim (45) of the control piston (5) through an axial port (34), the first radial ports (32) of the auxiliary piston (6) connecting the axial port (34) thereof to the first radial ports (30) of the control piston (5) only when the third occluding member (27) is at least partially opened, the second radial ports (33) of the auxiliary piston (6) connecting the axial ports (34) thereof to a second annular housing space (46) adapted to be connected by the second valve seat (25) to the outlet port (8), the second housing space (46) being formed by the body (3), the thickened end (38) of the auxiliary piston (6) which is away from the thrust spring (39) and the rim (45) of the control piston (5), the second occluding member (24) being completely open while the first occluding member (19) is closed and in that furthermore an auxiliary control port (10) for control medium is connected to a third housing space (43) formed by the valve body (3) and the ends (38) of the auxiliary piston (6) which is remote from the thrust spring (39), and in that the second housing space (46) is connected to a venting space via a venting port (41) and in that furthermore the control pressure in the control port (15) acts on the control piston (5) against the thrust of the through-flowing medium, and in that a fourth valve seat (35) on the inner rim (45) of the control piston (5) cooperates with a fourth occluding member (36) on the auxiliary piston (6), pressure loading on the auxiliary control port (10) and the relief of pressure on the control port (15) resulting in the fourth occluding member (36) being closed against the resistance of the thrust spring (39), the discharge side of the fourth valve seat (35) being connected to the venting port (41), the inner mouth of the venting port (41), when viewed in the direction of displacement (4) of the auxiliary piston (6), being furthermore located between the control ports (10 and 15) and in that the second radial ports (33) of the auxiliary piston (5) are connected via a fourth annular housing space (48) to the fourth valve seat (35) which is dispoed between the control piston (5) and the auxiliary piston (6) in the region of the second radial ports (31) of the control piston (5).