VALVE DEVICE

Abstract

The invention relates to a valve device having a valve housing, and comprising a main piston (4) that is arranged in an axially slidable manner in a piston bore of the valve housing (2), via which a first consumer connection (A) and a second consumer connection (B) can be alternately connected to a pressure connection (P) and a tank connection (T1, T2) by way of the action of a first magnetic actuating system (6) and a second magnetic actuating system (8) and comprising two pilot pistons (14, 16). The invention is characterized in that in an actuated state of the respective pilot piston (14, 16), the main piston (4) follows the movement of said pilot piston (14, 16) due to the force ratio adjusting itself thereon, thus actuating the fluid-carrying connection between the pilot chamber (10, 12) of said pilot piston (14,16) and the assignable tank connection (T1, T2) such that pilot oil flows.

Claims

1. A valve device having a valve housing, and comprising a main piston (4) that is arranged in an axially displaceable manner in a piston bore of the valve housing (2), via which a first consumer connection (A) and a second consumer connection (B) can be alternately connected to a pressure connection (P) and to a tank connection (T1, T2) by means of the action of a first magnet actuating system (6) and a second magnet actuating system (8), wherein the main piston (4) can be displaced out of a centered, preferably central rest position in a first direction for the connection of the first consumer connection (A) to the pressure connection (P) and of the second consumer connection (B) to the tank connection (T2) and can be displaced in an opposite direction for the converse fluid-conducting connection of the connections (A, B, P, T1, T2), with a first pilot control compartment (10) being provided, which applies a pressure to a first piston rear side of the main piston (4), and a second pilot control compartment (12) being provided, which applies a pressure to a second piston rear side, with the first (10) and the second (12) pilot control compartments being connected via a fluid-conducting connection to the pressure connection (P), and a first pilot control piston (14) and a second pilot control piston (16) being provided, and with these pilot control pistons (14, 16) each enabling or blocking a fluid-conducting connection between the pilot control compartments (10, 12) and the tank connection (T1, T2), characterized in that, in an actuated state of the respective pilot control piston (14, 16), the main piston (4) follows the movement of this pilot control piston (14, 16) due to the degree of force applied to said main piston and thereby activates the fluid-conducting connection between the pilot control compartment (10, 12) of this pilot control piston (14, 16) and the assignable tank connection (T1, T2) in such a way that pilot control oil flows (14, 16).

2. The valve device according to claim 1, characterized in that the respective fluid-conducting connection between the pilot control compartment (10, 12) of the respective pilot control piston (14, 16) and the assignable tank connection (T1, T2) is formed by at least one pilot control orifice (20) of the main piston (4) which, in the unactuated state of the pilot control piston and the main piston, is closed by the assignable pilot control piston.

3. The valve device according to claim 1, characterized in that at least one of the two pilot control pistons (14, 16) is guided with its outer circumference at least partially along the inner circumference of an assignable recess (22) in the main piston (4), into which recess the respective pilot control orifice (20) opens.

4. The valve device according to claim 1, characterized in that the respective pilot control piston (14, 16) has a projecting contact collar (26) outside of the recess (22) of the main piston (4), on which contact collar the main piston (4) can rest with its respective assignable free end face in at least one of its displacement positions.

5. The valve device according to claim 1, characterized in that the respective pilot control piston (14, 16) is designed as a hollow piston, which establishes in each of its displacement positions a permanent fluid-conducting connection (28) from the pressure connection (P) to the pilot control compartment (10, 12) of this pilot control piston (14, 16) and on the assignable piston rear side of the main piston (4).

6. The valve device according to claim 1, characterized in that an orifice (32) or throttle is connected in the permanent fluid-conducting connection between the pressure connection (P) and the interior space comprising the hollow piston as the pilot control piston.

7. The valve device according to claim 1, characterized in that the respective pilot control piston (14, 16) can be actuated by means of a keeper (34) of the magnet actuating system (6, 8) and is guided in a displaceable manner inside the interior space of the main piston (4) in the manner of a slide piston.

8. The valve device according to claim 1, characterized in that, in the neutral position, the main piston (4) is held in its unactuated neutral position by means of at least one main spring (36) of the magnet actuating system (6, 8) and at least one resetting spring (40), which surrounds the pilot control piston (14, 16).

9. The valve device according to claim 1, characterized in that, by means of an additional adjusting spring (38), the activation force of the magnet actuating system (6, 8) on the keeper (34) can also be specified.

10. The valve device according to claim 1, characterized in that the magnet actuating system (6, 8) and also the assignable pilot control stage (10, 12) with the pilot control piston (14, 16) are formed as identical parts and are arranged on both opposite sides of the main piston (4) with opposite actions.

Description

[0011] The valve device according to the invention is explained in greater detail below with reference to an exemplary embodiment according to the drawings. In said schematic and not to scale drawings,

[0012] FIG. 1 shows a schematic longitudinal section through the valve device according to the invention, wherein the two magnet actuating systems arranged at the ends are de-energized;

[0013] FIG. 2 shows a magnified depiction of a frame-type detail of the valve device according to FIG. 1; and

[0014] FIG. 3 shows a longitudinal section depiction corresponding to FIG. 1, in which, viewed in the viewing direction of FIG. 3, the magnet actuating system depicted on the left-hand side is energized.

[0015] FIG. 1 depicts, in a schematic, not to scale longitudinal section, the valve device according to the invention for controlling the flow of pressurizing medium, such as hydraulic oil, to a consumer which is not depicted in detail, for example in the form of a hydraulic working cylinder, which can be attached to the consumer connections A, B with its piston side and rod side and the two associated working spaces. The valve device has a valve housing 2, which is formed essentially block-like and in particular cylindrical. In addition, the valve housing 2 delimits towards the outside the fluid connection points A, B, P, T1, T2, which, in a conventional manner, open into annular channels inside the valve housing 2, which can be activated by a main piston or a valve piston 4. The two tank connections T1, T2 are brought together at a common tank connection T, so that a fluid discharge both from the tank connection T1 and via the connection T2 takes place in the common connection T.

[0016] For this purpose, a through-hole is introduced into the valve housing 2, which is formed as a piston bore or cylinder bore for accommodating the main piston 4 and which ensures the longitudinal displaceability thereof inside the valve housing 2. For the indirect actuation of the main piston 4, a first and a second magnet actuating system 6, 8 are arranged on both sides of the valve housing 2, which magnet actuating systems have a conventional design, with the respective energizable operating coils for the magnet actuating systems 6, 8 having been omitted from the drawing for the sake of simpler representation. Said magnet actuating systems 6, 8 together with their pole tube arrangements 9 can be fixed by means of screwing opposite one another on the free end faces of the valve housing 2.

[0017] The respective magnet actuating system 6, 8 is in particular formed as a so-called proportional magnet, and the main piston 4 depicted in FIG. 1 has radial projections on the outer circumference side, with the respective radial outer circumference of the respective projection being selected such that it can slide in a tight manner on the inner circumference side of the valve piston bore, in order to thus also allow the individual fluid connections to be separated from one another or alternatively connected to one another. A first pilot control compartment 10 and a second pilot control compartment 12 are connected to the two opposite sides of the valve housing 2, the respective volume of which pilot control compartments, or the pressure situation thereof, is able to be changed by means of a pilot control piston 14, 16. The respective pilot control compartments 10, 12 are connected in a fluid-conducting manner to the rear sides or free end faces of the valve piston or main piston 4.

[0018] Furthermore, the two pilot control compartments 10, 12 can be pressurized with the pressure connection P via a fluid-conducting connection 18, formed as a longitudinal bore in the main piston 4, with the control pressure or pump pressure of a pressure supply source, for example, in the form of a hydraulic pump, which pressure supply source is not shown in detail. For this purpose, the longitudinal channel 18 opens into a transverse channel 21, which penetrates the main piston 4 on both sides and opens into the annular space in the valve housing 2 which is connected to the pressure supply source via the pressure supply P. In an actuated state, as is depicted in an exemplary manner in FIG. 3 and as will be described in greater detail, of the respective pilot control piston, in this case the pilot control piston 14, the main piston 4 follows the movement of the pilot control piston 14, with the enabled, fluid-conducting connection between the assigned pilot control compartment 10 of this pilot control piston 14 and the assignable tank connection T1 being maintained for the flow of pilot control oil.

[0019] In particular, the respective fluid-conducting connection between the pilot control compartment, in this case, the pilot control compartment 10, of the respective pilot control piston, in this case, the pilot control piston 14, and the assignable tank connection or return connection T1 can be enabled by means of at least one pilot control orifice, which are preferably formed as two pilot control orifices 20 of the main piston 4. As is shown in FIGS. 1 and 2, the pilot control orifice 20 is in any case closed by the assigned pilot control piston 14 in the unactuated state of the pilot control piston 14 and of the main piston 4. The conditions described above also apply in the unactuated state of the system for the second pilot control compartment 12 together with the second pilot control piston 16 and the region of the main piston 4 at the appropriate location. In addition, the respective pilot control piston 14, 16 is guided with its outer circumference at least partially along the inner circumference of an assignable recess 22 (cf. FIG. 2) in the main piston 4, into which recess the respective pilot control orifice 20 opens. For this longitudinal guiding of the respective pilot control piston 14, 16 in said recess 20 in the main piston 4, said pistons have, on their outer circumference side and axially separated from one another, individual lubrication grooves and leakage grooves 24, which, appropriately filled with hydraulic medium, seal the respective pilot control compartment 10, 12 relative to the fluid-conducting connection 18 in the form of a longitudinal channel in the main piston 4.

[0020] As can also be seen from FIGS. 1 and 2, the respective pilot control piston 14, 16 has a projecting contact collar 26 outside of the recess 20 in the main piston 4, on which contact collar the main piston 4 can rest with its respective assignable free end face in one of its displacement positions, as is shown in FIG. 2, with contact occurring in particular in the neutral position of the piston 4 for both contact collars 26 of the pilot control pistons 14, 16. Furthermore, the respective pilot control piston 14, 16 is designed as a hollow piston, which establishes in each of its displacement positions a permanent fluid-conducting connection 28 from the pressure connection P to the pilot control compartment 10, 12 of this pilot control piston 14 or 16 and to this extent also on the assignable piston rear side of the main piston 4. Said connection 28 is in turn formed as a longitudinal channel and, viewed in the viewing direction of FIG. 2, it opens into the recess 22 on its right-hand side and, on the left-hand side, into a transverse channel section 30, which in turn opens at both sides into the here assignable pilot control compartment 10 for the first pilot control piston 14.

[0021] In addition, an orifice 32 or throttle is connected in the permanent fluid-conducting connection between the pressure connection P and the interior space in the form of the recess 22 comprising the hollow piston as the respective pilot control piston 14, 16 (cf. FIG. 2). Said permanent fluid-conducting connection thus extends firstly from the pressure supply source via the pressure connection P in the valve housing 2 and the assigned annular space section towards the valve piston or main piston 4. From there, via the transverse channel 21 and the respective longitudinal channel 18, the orifice 32, parts of the interior space, or of the recess 22 and of the fluid-conducting connection 28 in the respective hollow piston and transitioning into the transverse channel section 30, the permanent fluid-conducting connection is established to the respective pilot control compartment 10, 12 and thus to the respective assignable rear side of the main piston 4. As shown in FIG. 1, this permanent fluid-conducting connection applies to both the left-hand pilot control compartment 10 and to the right-hand pilot control compartment 12.

[0022] The respective pilot control piston 14, 16 is connected on its side facing away from the connecting channel or longitudinal channel 18 in the main piston 4 to a keeper 34 of the respective magnet actuating system 6, 8 in a conventional manner via a snap ring connection or the like and can be moved via the keeper 34 in a correspondingly guided manner in the recess 22 of the main piston in the longitudinal direction of the valve arrangement. The electrically energizable coil windings of the respective magnet actuating system 6, 8 were omitted from the drawings for the sake of simpler representation. Such a construction is, however, extremely common, so that it will not be discussed in further detail here. If, however, a magnet actuating system 6 or 8 is energized, the respective keeper 34 moves, viewed in the viewing direction of FIG. 1, to the left or the right (pulling magnet), with the respective other keeper 34 then travelling along with it due to the spring force of an adjusting spring 38 which is described below.

[0023] The keeper 34 is held in a position, as depicted in an exemplary manner in FIGS. 1 and 2, by means of the action of the adjusting spring 38, which pushes the keeper 34 back, in which position the main piston 4 abuts the contact shoulder 26 of the respective pilot control piston 14, 16 due to the action of the adjusting spring 38. A main spring 36 is not tensioned in this position. Accommodated inside the main spring 36 and likewise designed as a compression spring is the adjusting spring 38, by means of which the free travel of the respective keeper 34 can also be adjusted. Furthermore, a resetting spring 40 is also provided as a final energy storage device on each side of the valve arrangement, which is supported with its free end via a contact pot 42 on a shoulder of the housing-like pole tube arrangement 9 and with its other end on a contact plate 44, which is supported with its free projecting edge perimeter on an inwards-projecting annular collar of the valve housing 2. The plate 44 itself forms a contact surface fora projecting annular shoulder of the valve piston or main piston 4 in this region, so that, as shown in an exemplary manner in FIG. 2, in a displacement movement of the main piston 4 out of its neutral position shown there towards the left, the contact plate 44 lifts from the annular collar of the valve housing 2 and, with increasing pressure from the resetting spring 40, which is compressed correspondingly, then moves to the left.

[0024] At this point it should also be pointed out that the respective keeper 34 has a through-hole, so that in front of and behind the keeper 34 a pressure compensation is produced in the assignable displacement spaces inside the respective pole tube arrangement. Such a construction is likewise conventional such that it will not be discussed in further detail here. It should furthermore be noted that, as shown in FIGS. 1 and 3 in particular, all significant components of the valve device arrangement are constructed in a modular manner as an identical parts concept or have identical symmetry axes.

[0025] The functioning of the valve device according to the invention shall be explained in detail below with reference to the drawing of FIG. 3, wherein the valve housing 2 is, for the sake of simpler representation, only partially depicted with its side outer walls being indicated by dashed lines and also with its fluid connections A, B, P, T1 and T2. Otherwise, the statements made above also apply with respect to the actuated embodiment according to FIG. 3.

[0026] Pilot controlled directional valves, as described above, have the advantage compared with directly-controlled valves that they are independent of the magnetic forces and spring forces with respect to the actuating force or resetting force, i.e., an improvement in performance with simultaneous reduction in the design size is possible when pilot control is realized according to this principle, and this is equivalent to a decrease by a nominal size. It is thus possible to use smaller and more cost-efficient magnets of the actuating system which have a lesser capacity, which results in a reduction or optimization of energy consumption. In the de-energized state as shown in FIGS. 1 and 2, the directional valve is in the depicted neutral position. If the magnet actuating system 6 is now energized, i.e., if the not depicted coil winding of the operating coil has an electric current or a voltage applied to it, a magnetic force is produced at the left keeper 34, which counteracts the force of the main spring 36, which results in the first pilot control piston 14 together with the keeper 34 moving to the left when viewed in the viewing direction of the figures and thereby enabling an opening cross section in the form of the two pilot control orifices 20 which is arranged in the main piston 4. By means of this opening cross section, pilot control oil then flows to the tank via the tank connection or return connection T1, which causes a reduction in the pressure in the pilot control chamber, that is to say, in the first pilot control compartment 10, which allows the main piston 4 to follow the pilot control piston 14, with the pilot control orifice 20 not being closed, so that pilot control oil flows.

[0027] The pressure in the second pilot control chamber, or pilot control compartment 12, then remains at the supply pressure level P, which produces an imbalance of forces over the opposite end faces of the main piston 4 with the result that a resulting force in the direction of the actuating magnet system 6 is obtained. The main piston 4 meanwhile enables the connections between pressure supply P and consumer connection A and between consumer connection B and tank connection or return connection T2. In the pole tube arrangement 9 of the additional magnet actuating system 8, the associated second pilot control piston 16 is pressed by means of the adjusting spring 38 during the movement of the main piston 4 to the left on the associated stop by means of the contact collar 26 in order to prevent an opening of the associated drain orifices 20. Any disruptive influence on the main piston 4 caused by friction forces or flow forces is compensated for in that more pilot control oil flows, which results in a reduction in pressure in the respective pilot control chamber or pilot control compartment 10, 12 and an increased imbalance of forces. If the electric current or the electric voltage is reduced, the main piston 4 moves from its travelled position depicted in FIG. 3 and returns to its starting position according to FIGS. 1 and 2.

[0028] If a reversal of the movement direction is desired, the magnet actuating system 8 is energized, and the same procedure as described above is then produced, but in this case the connection of the pressure connection P with the consumer connection B and the connection of the consumer connection A with the tank connection or return connection T1 is established. For the sake of completeness, it is also noted that FIG. 3 shows by means of arrows the fluid flow from the pressure supply P to the consumer connection A as well as the return from the consumer connection B leading to the tank connection T2 for the travelled state of the main piston 4 towards the left. The figure also depicts at the tank connection or return connection T1 the fluid flow via the pilot control orifices 20 coming from the pressure supply P, to the extent that the hollow piston, formed as a control slide, of the first pilot control piston 14 enables these orifices 20, which can be closed again to the extent that the main piston 4 with its pilot control orifices 20 in this region “drives against” the outer circumference side of the first pilot control piston 14 in a movement to the left. The supply pressure for the respective pilot control can come either from a pressure supply device, for example in the form of a hydraulic pump, or it can be obtained from the respective consumer connection A, B. Furthermore, the respective highest pilot control pressure can be provided via shuttle valves or check valves. The design of solutions supplemented to this effect is shown in the prior art, for example for a pilot controlled valve as described in the publication DE 10 2010 005 229 A1. In the case of a current interruption of the magnet actuating systems 6, 8, the main piston 4 returns, by means of the springs 36, 38, to its spring-centered starting position or central position according to FIGS. 1 and 2.