Hydromechanical linear converter

Abstract

A hydromechanical linear converter has a cylinder, a piston unit and a seat valve unit. The cylinder and a piston of the piston unit delimit a hydraulic working chamber, into which a working connection and a further fluid connection open, and has a supply connection 10. The valve unit switches between a first position connecting the supply connection to the fluid connection and a second position blocking the fluid connection from the supply connection. The linear converter includes a valve housing with a valve seat 16, a valve body with a valve head cooperating with the seat, a spring unit preloading the valve body into a position corresponding to the first position and an electromagnetic actuator 14 acting on the valve body 12 by purely mechanical action, to move the valve body against the force of the spring unit into a position corresponding to the second switching position.

Claims

1. A hydromechanical linear converter comprising: a cylinder; a piston unit movable relative to the cylinder and having a piston, the cylinder and the piston of the piston unit delimiting a hydraulic working chamber; a working connection and a further fluid connection opening into the hydraulic working chamber; a valve unit, the fluid connection communicating hydraulically with the valve unit, the valve unit configured as a seat valve unit having a supply connection, the valve unit being switchable between a first switching position connecting the supply connection to the fluid connection and a second switching position blocking fluid relative to the supply connection, the valve unit comprising; a valve housing having a valve seat; a valve body movable along a valve axis relative to the valve housing and having a valve head cooperating with the valve seat; a spring unit which preloads the valve body into a position corresponding to the first switching position of the valve unit, in which the valve head is lifted from the valve seat; and an electromagnetic actuator acting on the valve body via a purely mechanical action, the electromagnetic actuator operable to adjust the valve body against a force of the spring unit into a position corresponding to the second switching position of the valve unit, in which position the valve head rests sealingly on the valve seat; wherein the valve body is sealingly guided in the valve housing in such a way that the valve body together with the valve housing delimits a hydraulic operating chamber, the hydraulic operating chamber communicating hydraulically with the fluid connection via a compensation channel and a pressurization of the hydraulic operating chamber acts on the valve body in an opposite direction to the spring unit; and wherein in a projection along the valve axis, surface portions of the valve body delimiting the hydraulic operating chamber are larger than surface portions of the valve body which are exposed to a pressure prevailing in the fluid connection in the second switching position of the valve unit, the pressurization of the fluid connection in the second switching position acting on the valve body in a same direction as the spring unit.

2. The hydromechanical linear converter according to claim 1, wherein the valve housing comprises a base body and a pot-like insert, the pot-like insert forming the valve seat and having at least one peripheral opening.

3. The hydromechanical linear converter according to claim 2, wherein the base body is configured as a multi-part element with a base structure and a cover, the base structure comprising the fluid connection and the supply connection.

4. The hydromechanical linear converter according to claim 2, wherein the valve body is sealingly guided in the insert.

5. The hydromechanical linear converter according to claim 1, wherein the valve body comprises a valve pot and a valve stem fixedly connected to the valve pot, the electromagnetic actuator acting on the valve step, a bottom of the valve pot forming the valve head.

6. The hydromechanical linear converter according to claim 5, wherein a basket fixed to the housing protrudes into the valve pot, the spring unit being supported on the basket in the form of a pressure-loaded return spring surrounding the valve stem.

7. The hydromechanical linear converter according to claim 5, wherein the electromagnetic actuator is configured as a solenoid unit which is mounted on an outside of the valve housing and comprises an armature having an armature rod and an armature tube which receives the armature rod and is tightly closed on one side.

8. The hydromechanical linear converter according to claim 7, wherein an interior of the armature tube communicates with the hydraulic operating chamber as a continuous pressure compensation.

9. The hydromechanical linear converter according to claim 7, wherein the valve stem, the armature rod or a separate tappet arranged between the valve stem and the armature rod passes through an opening of the valve housing in an at least substantially sealing manner and the interior of the armature tube communicates with the supply connection via a relief line.

10. The hydromechanical linear converter according to claim 5, wherein the valve seat is arranged between the fluid connection and the valve head and the compensation channel is formed by an opening passing through the bottom of the valve pot.

11. The hydromechanical linear converter according to claim 5, wherein the valve seat is arranged between the supply connection and the valve head and the compensation channel is formed by an opening passing through the side wall of the valve pot.

12. The hydromechanical linear converter according to claim 1, wherein the electromagnetic actuator is disposed in the hydraulic operating chamber.

13. The hydromechanical linear converter according to claim 1, wherein the electromagnetic actuator is not energized in the first switching position of the valve unit.

14. The hydromechanical linear converter according to claim 1, wherein the hydraulic operating chamber communicates with the supply connection via a bypass line with a shut-off valve arranged therein.

15. The hydromechanical linear converter according to claim 1, wherein the valve body can be brought into at least one intermediate position by means of the electromagnetic actuator, the intermediate position being between the first and the second switching position of the valve unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the present invention is explained in more detail by means of two preferred exemplary embodiments illustrated in the drawing. Thereby

(2) FIG. 1 is a schematic view of a hydromechanical linear converter according to the invention;

(3) FIG. 2 is a detail of a valve unit in its first switching position which can be used with the linear converter according to FIG. 1; and

(4) FIG. 3 is a modified version of the valve unit according to FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

(5) The hydromechanical linear converter 1 illustrated in the drawing comprises, as known from the state of the art and therefore not explained in detail at this point, a cylinder 2, a piston unit 3 movable relative to it and a valve unit 4. The cylinder 2 and a piston 5 of the piston unit 3 define a hydraulic working chamber 6 into which a working connection 7 and a further fluid connection 8 open, the fluid connection communicating hydraulically with the valve unit 4. The valve unit 4 is configured as a seat valve unit 9 and comprises a supply connection 10 and can be switched between a first switching position connecting the supply connection 10 with the fluid connection 8 (shown in FIG. 2) and a second switching position shutting off the fluid connection 8 from the supply connection 10.

(6) The valve unit 4 comprises a valve housing 11, a valve body 12, a spring unit 13 and an electromagnetic actuator 14. The valve housing 11 comprises a pot-shaped insert 15 which forms the valve seat 16 and—in its peripheral wall—has several peripheral openings 17, and a two-part base body 18 with a base structure 19 having the supply connection 10 and the fluid connection 8 and a cover 20. Base structure 19 and cover 20 are firmly connected to each other with suitable (not shown) fastening means. They accommodate the insert 15 between them, whereby the insert 15 is sealed at the end face against the base structure 19 and the cover 20 by means of associated seals.

(7) The valve body 12 can be moved along a valve axis A relative to the valve body 11. It comprises a valve pot 21—having a substantially cylindrical circumferential wall and a bottom—and a valve stem 22 which is firmly connected to the bottom of the valve pot 21, the bottom of the valve pot 21 forming the valve head 23 which cooperates with the valve seat 16. The valve seat 16 is located between the fluid connection 8 and the valve head 23. The spring unit 13 pretensions the valve body 12 to a position corresponding to the first switching position of the valve unit, in which the valve head 23 is lifted from the valve seat 16.

(8) A compensation channel 24, configured as an opening 25, passes through the bottom of the valve pot 21, while the valve body 12 is sealingly guided in the valve housing 11—namely in its insert 15—in such a way that together with the latter it delimits a hydraulic operating chamber 26. In a projection along the valve axis A, the hydraulic operating chamber 26 is essentially limited by two surface portions of the valve pot 21, namely the surface of the bottom facing the interior of the valve pot (minus the surfaces of the opening 25 and the valve stem 22) and the annular end face of the circumferential wall. The sum of these surface portions, over which a force acting on the valve body 12 in the opposite direction to the operating direction of the spring unit 13 results when pressure is applied to the hydraulic operating chamber 26, is greater than the surface of the valve head 23 resting on the valve seat 16 being surrounded by the valve seat 16 and being exposed to the fluid connection 8. The hydraulic operating chamber 26 communicates hydraulically with the fluid connection 8 via the compensation channel 24, so that pressure compensation between the fluid connection 8 and the hydraulic operating chamber 26 is ensured.

(9) A hydraulic connection between the hydraulic operating chamber 26 and the supply connection 10 can be established via a bypass line 27 with a shut-off valve 28, which is also electromagnetically operated.

(10) A basket 29 fixed to the housing projects into the valve cup 21, on which is supported a helical return spring 30 surrounding the valve stem 22 and forming the spring unit 13. Its second end is supported by a collar of the valve stem 22.

(11) The electromagnetic actuator 14 acts on the valve body 12 via a purely mechanical actuation chain. It moves the valve body 12 against the force of the spring unit 13 into a position corresponding to the second switching position of the valve unit, in which the valve head 23 rests sealingly on the valve seat 16.

(12) The electromagnetic actuator 14 is configured as a solenoid unit 31, which comprises an armature with an armature stem 32 acting on the valve stem 22 and a pressure-tight armature tube which receives and guides the armature and is closed at one end. By means of an adapter 33 attached to the cover 20 of the valve housing, the solenoid unit 31 is firmly and tightly connected to the valve housing 11 in such a way that the interior of the armature tube is constantly exposed to the pressure prevailing in the hydraulic operating chamber 26. The corresponding constant pressure compensation takes place along the armature rod, which is guided with appropriate clearance.

(13) Other configurations of the electromagnetic actuator (e.g. as an electric linear actuator) are advantageously possible in the same way (see above), in particular to enable the valve body to be adjusted to several different intermediate positions. From FIG. 2, considering the explanations on this further embodiment, it is easy to derive the reverse functional design described above, in which the fluid connection 8 and the supply connection 10 are essentially interchanged and the opening 25 connecting the fluid connection 8 to the hydraulic operating chamber 26 does not penetrate the bottom of the valve pot 21, but rather its circumferential wall. In accordance with the change of the supply connection 10, the bypass line 27, which connects it to the hydraulically active chamber, would also have to be changed.

(14) The modified embodiment illustrated in FIG. 3 differs from that shown in FIG. 2 essentially in that it is not the interior of the armature tube that communicates with the hydraulic operating chamber in the sense of constant pressure compensation, but rather a tappet 36 arranged in a force-transmitting manner between the armature of the solenoid unit 31 and the valve stem 22, which passes at least essentially sealingly through an opening 34 in the cover 20 and the valve housing 11. The interior of the armature tube communicates constantly with the supply connection 10 via a relief line 35, so that leakage oil quantities that enter the armature tube along the armature rod 32′ through the opening 35 can flow constantly into the (unpressurised) supply connection 10, thus preventing a pressure build-up in the armature tube.