Valve

Abstract

The utility model relates to a valve, in particular to a proportional valve, which is provided with a main piston (10) for controlling the volume flow of a main body and a pilot control piston (12) for controlling the volume flow of pilot control, the main piston (10) and the pilot control piston (12) can be guided in a valve shell (14) in a longitudinal movement manner, and the pilot control piston (12) can be controlled by means of a magnet device (16). The utility model is characterized in that the position of the main piston (10) can be controlled by means of a pilot control piston (12), the pilot control piston transmits a fluid pressure acting on the main piston (10) via a fluid connection (18) into the pilot control chamber (20) or interrupts the fluid connection (18) and connects the pilot control chamber (20) to the tank side or the low-pressure side (T) via a further fluid connection (19) as a function of the displacement position thereof, a valve mechanism (21) is introduced into the further fluid connection (18), which valve mechanism closes in a valve-sealed manner as soon as the fluid connection (18) is established between the main piston (10) and the pilot control chamber (20).

Description

Technical Field

[0001] The utility model relates to a valve, in particular a proportional valve, which has a main piston for controlling a main volume flow and a pilot control piston for controlling a pilot control volume flow, wherein the main piston and the pilot control piston are guided in a longitudinally movable manner in a valve housing, and the pilot control piston can be controlled by means of a magnet device. Background Art

[0002] DE10323595A1 discloses a valve, in particular a valve in the form of a proportional seat valve or a sliding valve, which has a valve housing and at least three fluid interfaces passing through the valve housing, as well as a main piston guided in the valve housing and a pilot control piston for pilot control, the pilot control piston being controllable by means of an energizable magnet device, wherein, when the pilot control device is opened, the fluid passes from one of the two interfaces controllable by the main piston via a cross-sectional contraction in the main piston and the pilot control device to a third interface controllable by the pilot control piston, and, due to the resulting pressure drop, the main piston reaches a corresponding control position in which the two fluid interfaces can be controlled by the fluid quantity.

[0003] EP2880315B1 discloses a valve, in particular a pilot-controlled proportional directional seat valve, which comprises a valve housing having a fluid inlet and a fluid outlet, wherein the fluid flow between the inlet and the outlet can be adjusted by a main piston, a pilot-controlled valve chamber is arranged on the back side of the main piston, the pilot-controlled valve chamber has a pilot-controlled valve closure member movable by an operating device, the fluid flow between the pilot-controlled valve chamber and the fluid outlet can be adjusted by means of the pilot-controlled valve closure member, an inlet throttle plate is arranged between the fluid inlet and the pilot-controlled valve chamber, the opening cross section of the inlet throttle plate can be reduced by a control element, the inlet throttle plate has a plurality of throttle holes, the opening cross section of at least one of the throttle holes can be reduced by a control element, and dividing the inlet throttle plate into a plurality of throttle holes can realize switching the inlet throttle plate to a plurality of opening levels.

[0004] Such pilot-controlled directional valves utilize electrohydraulic actuation to control the start, stop and direction of the volume flow as well as the speed, acceleration and deceleration of the hydraulic consumer connected to the valve, for example in the form of a hydraulic working cylinder. Pilot-controlled directional valves are used in principle where large volume flows are controlled under small flow losses. However, small flow losses under large volume flows mean large opening cross-sections and therefore large strokes of the main piston. The disturbances that affect the valve function are flow forces and friction forces that react on the switching motion, which depend on the volume flow and pressure difference, that is, the valve power. In particular, in the case of mechanical actuation by a spring that is usually in the form of a return spring, the measured value of the spring force relative to the friction force may be too small for returning the piston slide valve. In order to meet the requirements of the magnet system in terms of stroke and force, the magnet system must either be dimensioned accordingly or hydraulically pilot-controlled valves. As shown above, the following valves are known in the prior art for such applications, and these valves must therefore have hydraulic pilot control devices. Utility Model Content

[0005] Starting from the prior art, the object of the invention is to further improve the known valve with regard to its functional properties.

[0006] Due to the characteristic features of the valve according to the invention, the position of the main piston can be controlled by means of a pilot control piston, which, depending on its displacement position, transmits the fluid pressure acting on the main piston via a fluid connection to a pilot control chamber or interrupts the fluid connection and connects the pilot control chamber to the tank side or the low-pressure side via a further fluid connection, into which a valve mechanism is introduced, which closes in a seat-tight manner as soon as the fluid connection is established between the main piston and the pilot control chamber, so that within the valve, the pilot control stage is sealed in a seat-tight manner by means of the pilot control piston in one of its possible operating positions or displacement positions. Due to the above-described seat seal for the pilot control chamber with the pilot control piston, the valve according to the invention can be used particularly advantageously as a so-called load valve, which can maintain its predeterminable, adjustable position without leakage even under high loads, thereby ensuring that the load acting on the valve in a fluid manner cannot be accidentally reduced, which could otherwise entail a significant safety risk. In the closed position, the valve is leak-free, whereas in the open position, the valve conducts a regulated volume flow.

[0007] In a preferred embodiment of the valve according to the invention, it is provided that the valve mechanism is formed by a valve seat, which is formed by mutually contactable sealing surfaces of an outer circumference of the pilot control piston and an inner circumference of an adjacent wall portion of the valve housing. The contactable sealing surfaces can in particular consist of inclined surfaces of different inclinations, so that within the scope of the valve seat to be produced, a linear sealing contact or sealing edge is generated between the pilot control piston and the valve housing, which is accompanied by an increased sealing pressure during operation, and the increased sealing pressure improves the valve seat tightness.

[0008] In a further preferred embodiment of the valve according to the invention, it is provided that the sealing surface of the pilot control piston is located at the transition between two different diameters of the pilot control piston, wherein the larger diameter defines an annular recess in the pilot control piston, while the smaller diameter is formed by an annular groove which, in the closed state of the valve seat, at least partially overlaps the annular recess in the valve housing from the inside. In this way, the valve seat can be produced in a manner that is advantageous in terms of production technology.

[0009] In another preferred embodiment of the valve according to the invention, it is provided that a channel section engages in the recess on the pilot control piston, the channel section transitioning into a fluid-conducting channel of the pilot control piston, the fluid-conducting channel opening out on one side into the pilot control chamber. This connects the pilot control chamber to the movable part of the valve in a particularly flow-friendly manner.

[0010] In another preferred embodiment of the valve according to the invention, it is provided that during the displacement movement of the pilot control piston, the fluid guide via the recess and the annular groove into the groove-shaped annular channel on the outer circumference of the pilot control piston is released, while simultaneously interrupting the fluid connection from the main piston via the valve seat released in this way into the pilot control chamber, into which the tank-side tank connection for permanent fluid guidance opens. It is also preferably provided that between the annular groove and the annular channel, a guide section of the pilot control piston widened in diameter is guided along an assignable inner circumference of the valve housing in each displacement position of the pilot control piston. This makes it possible to reliably guide the pilot control piston inside the valve housing and to achieve a very compact design for the movable parts inside the valve housing.

[0011] In another particularly preferred embodiment of the valve according to the invention, it is provided that on the side of the valve housing in the direction of the magnet arrangement, at a predeterminable distance from the closed valve seat, there is a moving seal, which surrounds the outer circumference of the pilot control piston with a predeterminable preload force. With this moving seal, a complete sealing of the pilot control piston in the valve housing is achieved, and a leak-free sealing is achieved in both directions, namely in the direction of the pilot control chamber and in the direction of the magnet arrangement (which corresponds to the pilot control pressure), by means of the valve seat or by means of the moving seal.

[0012] If annular pressure relief grooves are introduced, preferably along predeterminable distances, on the outer circumference of the pilot control piston, a pressure-free and therefore trouble-free operation of the pilot control piston in the valve housing results.

[0013] It is particularly preferred that, in the valve according to the present invention, an additional valve seat is provided between the main piston and the valve housing as an additional valve seat sealing mechanism, and a third valve seat is provided as a third valve seat sealing valve mechanism, the third valve seat being formed by a closing ball and an adjacent wall portion of the main piston. In this way, the main stage of the valve, in particular the main stage formed by the main piston, is also designed to be valve seat sealed, which is particularly advantageous when the valve is designed as a load valve. The use of different valve seat sealing valve mechanisms in combination with moving seals ensures that no leakage volume flow occurs. The valve according to the present invention is designed to be pressure closed, that is, from the basic structure, the valve is automatically closed, which in turn makes it particularly suitable for use as a load valve. If the spring force acting on the main piston is balanced with the magnetic force generated by the operating magnet, the main piston of the valve is controlled to remain in its preset position and thus controls the main volume flow between the two fluid connection parts in the valve housing. This control behavior is advantageous if the pilot control valve as a whole has a negative overlap and forms a control edge between the pilot control piston and the valve housing by means of the first valve element, which controls the actuation of the main piston in a particularly fine-tuned manner during operation of the valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The valve according to the present invention is described in detail below with the aid of embodiments according to the accompanying drawings. Here, it is shown in a principled and not to scale longitudinal section:

[0015] Figure 1 shows the main components of the valve in the energized state;

[0016] Figure 2 The closed valve position is shown according to Figure 1 The front portion of the valve;

[0017] Figure 3 The valve is open when Figure 2 a view of

[0018] Figure 4 Shown in Figure 1 and Figure 2 The enlarged view of the part of the picture indicated by X. DETAILED DESCRIPTION

[0019] The valve shown in the drawing is a so-called proportional valve and has a main piston 10 for controlling the main volume flow. In addition, there is a pilot control piston 12 for controlling the pilot control volume flow, the main piston 10 and the pilot control piston 12 are guided together in a longitudinally movable manner in a valve housing 14. Figure 1 It turns out that the pilot control piston 12 can be actuated displaceably in the valve housing 14 by means of the magnet arrangement 16 .

[0020] The position of the main piston 10 can be adjusted by means of the pilot control piston 12 by transmitting the fluid pressure acting on the main piston 10 via the fluid connection structure 18 to the pilot control chamber 20 having the pilot control piston 12, which, when the magnet device 16 is actuated and energized, holds the main piston 10 in its closed position that blocks the main volume flow (e.g. Figure 2 As shown), when the magnet device 16 is not operated and there is no current, the pilot control piston 12 is Figure 2 Starting from the energized operating position shown in FIG. , the current is moved to the left in the viewing direction of the drawing according to Figure 3 In the initial position of the pilot control chamber 20, the fluid pressure, which is essentially decoupled from the pressure supply provided by the main piston 10, continues to decrease until the main piston 10 reaches the open position for regulating the main volume flow, as in Figure 3 As shown by way of example in one of the possible opening positions. Whenever the directions "right" and "left" are mentioned, this means the directions seen in the viewing direction of the accompanying drawings.

[0021] The position of the main piston 10 is therefore adjusted by means of the pilot control piston 12. In this context, the force balance on the pilot control piston 12 must be taken into account, which, apart from any manufacturing tolerances, is guided almost pressure-balanced and therefore does not generate any pressure. This results in the following formula relationship:

[0022] F 致动器 –F 弹簧 –F 摩擦 =F 致动器 –(F1 弹簧 +x*c)-F 摩擦 =0, where

[0023] in

[0024] F致动器 =F 磁体弹簧 -F 磁 ,in

[0025] F 摩擦 = friction due to the movement of the pilot control piston 12,

[0026] c = average spring rate of the springs used,

[0027] F 弹簧 = the force of the pressure spring 22 acting on the pilot control piston 12 at the end, and

[0028] F 磁体弹簧 =Compression spring 23 a acting on the actuating magnet 17 and acting in the direction of the initial position of the pilot control piston 12 .

[0029] An additional compression spring (not shown) can act on the actuating magnet 17 with its magnet armature in the direction of action opposite to its tensioning actuation direction, which serves to overcome the so-called dead current, i.e. to provide such a current until the actuating magnet 17 has completely overcome the spring force and has begun to move. This can prevent possible obstructions in the operation of the valve.

[0030] Below, in Figure 1 The force arrows in FIG. 1 indicate the individual forces occurring, in particular the spring forces, together with their directions of action. Here, the spring force F acting on the pilot control piston 12 at the end side is 弹簧 The magnetic force for the actuating magnet 17 is indicated by arrow 23 b, the magnetic force for the actuating magnet 17 is indicated by arrow 28 , and the spring force F acting on the actuating magnet 17 磁体弹簧 This is indicated by arrow 29a.

[0031] Furthermore, as can be seen from the figures, the pilot control piston 12 is designed as a hollow piston which has a first recess 30 in the form of an annular shoulder on its outer circumference, which first recess is formed when the magnet arrangement 16 is actuated or energized (depending on the Figure 2 In the actuated position, a fluid-carrying connection 18 is established with the primary piston 10 and the magnet arrangement 16 remains de-energized (according to Figure 3 The pilot control piston 12, which is constructed as a hollow piston, has a fluid-conducting channel 32 along its inner circumference, which opens with its free end into the pilot control chamber 20 and through a radially extending channel section 36 of the axially extending channel 32 into an annular second recess 38 on the outer circumference of the hollow or pilot control piston 12, which, when the magnet device 16 is not actuated (according to Figure 33 (view) into the fluid-conducting connection to the tank connection 40, at which point the connection of the first recess 30 is disconnected from the fluid-conducting connection to the primary piston 10. All so-called fluid-conducting structures, such as the channel section 36 and the tank connection 40, can be present in multiples as shown, wherein for a simpler and clearer representation, generally only one fluid-conducting structure is provided with a reference numeral. In addition to the compression spring 23a (wherein for a simplified view, only the spring chamber between the magnet armature 17 and the fixed closed housing part of the valve housing 14 is shown), other energy storage devices of the same orientation, such as compression springs, can also be used.

[0032] A seat-sealed switching valve 42 is connected to the fluid-conducting connection between the main piston 10 and the pilot control chamber 20 and, when the valve is “energized” and closed, transmits the respectively higher pressure of the two fluid connections 44, 46 in the valve housing 14 as a transmission pressure into the pilot control chamber 20, via which the main volume flow to be regulated is conducted. If the fluid pressure at the axial fluid connection 44 at the end side is greater than the fluid pressure at the radial fluid connection 46 arranged transversely thereto, the fluid with this higher pressure reaches the switching valve 42 with its closing ball 48 via the fluid connection 44 and the longitudinal channel 50 in the front region of the main piston 10, which is designed in this way to seal the valve seat. Such a closing ball 48 moves to the right in this respect, as viewed in the viewing direction of the drawing, and hereby closes in a seat-sealed manner a radial channel 52 with an inclined course introduced into the main piston 10, which opens into the fluid connection 46 in the valve housing 14.

[0033] A further longitudinal channel 56 is connected to the valve chamber 54 of the switching valve 42, which in turn is introduced into the main piston 10 and opens with its free end-side end into a fluid chamber 58 in the main piston 10. The fluid chamber 58 is connected to a further fluid chamber 62, which is designed as an annular chamber and is arranged between the valve housing 14 and the main piston 10, via at least two connecting channels 60 arranged at right angles to the longitudinal axis of the valve in the main piston 10. The further fluid chamber 62 transitions fluidically into an annular chamber 64 arranged in the valve housing 14 with a widened diameter, and from there a longitudinal channel section 66 designed as a high-pressure channel is guided into a sickle-shaped annular chamber 67, which is closed at the free end by means of a plug 69 and which is introduced into a part of the lower section of the valve housing 14 in an arc-shaped and fluid-guiding manner.

[0034] Especially Figure 4As shown, the sickle-shaped annular chamber 67 here permanently transitions in a fluid-conducting manner into a transverse channel portion 68 arranged radially in the valve housing 14, which widens in a groove-shaped manner in cross section at its inner free end toward the pilot control piston 12 and which (according to Figure 2 ) partially overlaps with the annular first recess 30 at the outer periphery of the pilot control piston 12, once the pilot control piston 12 is moved from its non-energized initial position (according to Figure 3 ) starts from the left to the right when the magnet device 16 is energized, and reaches the right operating position (according to Figure 1 and 2 ), the connection of the above-mentioned guiding fluid is realized. Subsequently, the valve is in its closed position of the fluid path between the interface parts 44, 46.

[0035] It will be appreciated that, as previously described, corresponding channels and other connections may be provided as shown in the valve as needed in multiples to ensure reliable fluid guidance. Figure 1 , 2 and 4), then in any case the components 50, 52, 54, 56, 58, 60, 62, 64, 66, 67, 68 and 30 form a possible fluid connection 18 between the fluid connection 44, 46 at the main piston 10 and the pilot control chamber 20 between the main control piston 10 and the pilot control piston 12. Otherwise, in the non-actuated, current-free open position of the magnet arrangement 16, the above-mentioned fluid-conducting connection 18 between the first recess 30 and the transverse channel portion 68 is interrupted in that the pilot control piston 12 occupies its position in the open position. Figure 3 In this regard, in the closed valve position of the main piston 10, the correspondingly higher pressure at the fluid connection 44 or 46 is thus conducted or transmitted further into the pilot control chamber 20, more precisely via the internal fluid-conducting channel 32 of the pilot control piston 12, as long as the pilot control piston 12 occupies its position in the closed valve position. Figure 1 , 2 Otherwise, in the non-actuated, current-free position of the magnet arrangement 16, the above-mentioned fluid-conducting connection 18 between the first recess 30 and the transverse channel portion 68 is interrupted by the pilot control piston 12 occupying its Figure 3 However, the pressure in the pilot control chamber 20 is connected to the essentially pressure-free tank side T via the tank connection 40 and the further fluid-conducting connection 19, so that the main piston 10 can assume its open position (according to Figure 3), in which open position a main fluid connection is established between the fluid ports 44 and 46 in two possible fluid directions, as will be explained in greater detail below.

[0036] If the pressure at the radial connection 46 as the further fluid connection in the valve housing 14 is greater than the pressure at the fluid connection 44, the switching valve 42 is switched in the viewing direction of the drawing in such a way that the closing ball 48 now occupies its left closed position, which closes the channel 50. The fluid with a predeterminable pressure thus passes via the fluid connection 46 and the radial channel 52 and the valve chamber 54 into the further longitudinal channel 56, so that in this respect the pilot control piston 12 occupies its position in the radial channel 52. Figure 2 , the remaining part of the fluid connection 18 to the pilot control chamber 20 is now released via such a path in the right actuation position shown in FIG. 4 , which is energized. Usually, the fluid pressure from a pressure supply device, such as a hydraulic pump, should be present at the fluid connection 44, and a hydraulic consumer, such as a hydraulic cylinder, should be connected to the fluid connection 46. Other arrangements of the fluid connections 44, 46 when using such a proportional valve are conceivable. In particular, when the actuating magnet device 16 interacts in this way with an electronic open-loop control device or closed-loop control device, which is not shown in detail, the valve is suitable as a so-called load valve due to its valve seat tightness, with which the load can also be reduced in a controlled manner.

[0037] As can be further seen from the figures, the main piston 10 consists of two parts 70, 72, wherein the parts 70, 72 with their free ends facing each other delimit the fluid chamber 58 in the axial displacement direction of the valve pistons 10, 12. A second compression spring 74 acts as a further energy accumulator on the free end of the second part 72 facing the magnet arrangement 16, which second compression spring is supported with its other free end on the stationary part of the valve housing 14 and is designed as a compression spring that exerts a prestress on the main piston 10 in its closing direction. Extending on the inner circumference facing the second compression spring 74 and arranged coaxially therewith is a compression spring 22, which is supported with its one free end on a shoulder-shaped shoulder in the interior of the first part 70 and with its other free end on an annular projection 76 on the pilot control piston 12. In this way, both the main piston 10 and the pilot control piston 12 are prestressed by the two compression springs 74 or 22 with their respective spring forces.

[0038] From now on, it will be described below how the movement of the main piston 10 is regulated. Figure 2 From the observation direction, the main piston 10 moves to the left as shown in FIG. Figure 3In the state preset in the embodiment, the following is done here. The pressure applied to the corresponding fluid connection 44 or 46 in front of the main piston 10 (which is transmitted to the pilot control piston 12 via the switching valve 42 and the fluid connection structure 18) is controlled by the pressure in the pilot control chamber 20 (according to the pressure in the pilot control chamber 20) when the magnet device 16 is energized. Figure 2 The main piston 10 is first held by the surface difference formed by the opposite end sides of the main piston 10. In this case, in particular according to Figure 2 and Figure 4 , the pilot control piston 12 rests via the annular valve seat 23 against the valve housing 14 in a valve seat-tight manner, so that in the closed state of the valve no unintentional leakage flow can occur from the pilot control chamber 20 in the direction of the tank connection 40 .

[0039] If the force generated by the magnet arrangement 16 is now eliminated (opening without current), the pilot control piston 12 is moved from its left-hand starting position (according to the pressure spring 23a acting at least between the magnet housing 14 of the magnet arrangement 16 and the actuating magnet 17) as viewed in the direction of observation of the drawing to its left-hand starting position. Figure 3 ). In the left initial position, the recess 30 on the outer circumference of the pilot control piston 12 is closed by the associated housing part of the valve housing 14 and is separated from the high-pressure-conducting chamber 67. Likewise, the corresponding transverse channel 68, which can be connected to the fluid chamber 58 in a fluid-conducting manner and thus to the corresponding pressure inlet side of the main piston 10, is closed by the adjacent outer circumference of the pilot control piston 12 (preferably in a fluid-tight manner). In addition, the main piston 10 is held in the direction of its closed position by an external second pressure spring 74.

[0040] However, since the fluid pressure in the pilot control chamber 20 necessarily drops, the pilot control chamber 20, which has been disconnected from the pressure supply from the main piston 10 as described above, can now be held pressure-free via the fluid-conducting channel 32 inside the pilot control piston 12 in the direction of the tank connection 40. In this way, a fluid connection is established from the pilot control chamber 20 via the fluid-conducting channel 32 to the transversely extending channel section 36 of the corresponding channel 32. Since the pilot control piston 20 is in its open initial position without current (according to Figure 3), so that the second recess 38 in the valve housing 14 is opened to the left by means of the compression spring 23a acting on the pilot control piston 12, and the fluid can overflow from there via the released valve seat 23 and via the annular groove 31 into the annular recess 33 in the valve housing 14, into the pressure relief chamber or into the tank-side groove-shaped annular channel 78, which is formed by the axially widened annular recess in the valve housing 14. In this way, the pilot control piston 12 carries the annular channel 78 installed therein, so that the front end engages in the fluid-conducting annular recess 33, while the rear end of the annular channel 78 is still in the fluid conduction with the corresponding tank connection 40, at least with a reduced degree of overlap. Thus, when the valve seat 23 is released, the fluid under pressure on the pilot control chamber 20 side then flows out of the pressure relief chamber or annular channel 78 into the annular channel 78, which is recessed into the pilot control piston 12 with a predeterminable length, so that in every possible displacement position of the pilot control piston 12, the annular channel 78 at least partially still coincides with the tank connection 40 in a fluid-conducting manner. The fluid in the annular channel 78 is then placed on the tank side T of the valve device via the corresponding tank connection 40, so that the pilot control chamber 20 is completely depressurized in this respect. Then, depending on the fluid pressure exerted on the main piston 10, the main piston is opened against the spring action of the compression springs 22 and 74, and a new equilibrium is thus established on the opened valve. In particular, the corresponding tank connection 40 opens into the enlarged annular chamber 73, which is guided through the valve housing 14 in the longitudinal direction via the connecting channel 77 on the low-pressure side, and a fluid connection to the tank side T is established.

[0041] On the other hand, if the actuating magnet 17 of the magnet arrangement 16 is energized again, the associated actuating magnet 17 or magnet armature is Figure 1 In the viewing direction of the magnet arrangement 16, the magnet arrangement 16 is moved to its right displacement position or stop position against the effect of the magnet spring 23a. For this purpose, the magnet arrangement 16 has a coil 81 which can be energized, and when energized, the actuating magnet 17 or the magnet armature is moved from its position in the Figure 1 If the coil 81 is powered off via the common plug connection 82 on the magnet device 16, at least the compression spring 23a is allowed to return to the initial position shown without hindrance, which corresponds to Figure 3 The position of the pilot control piston 12 in is "open without current".

[0042] In this initial position of the magnet arrangement 16, according to Figure 3, the pilot control piston 12 is also in its left initial position and, as already explained, the pilot control chamber 20 is then no longer supplied with fluid at a pre-settable pressure from the main piston 10 side. The fluid pressure in the pilot control chamber 20 also acts on the rear side of the main piston 10 in principle, so that as long as the pilot control piston 12 occupies the position according to Figure 2 The position of the pilot control piston 12 is reliably maintained due to the surface conversion. Therefore, the actuated position or the energized position corresponds to a reliable closed position for the main piston 10. In addition, the fluid reaches the back of the pilot control piston through the fluid-conducting channel 32 of the pilot control piston 12, so as to thereby establish a pressure balance for the movable parts; only according to Figure 2 and Figure 4 In the view of FIG. 1 , a valve seat-tight closure of the fluid path from the pilot control chamber 20 in the direction of the tank connection 40 is now achieved via the valve seat 23, wherein the closure of the fluid path is leak-proof.

[0043] The first valve member 21 formed by the valve seat 23 is formed by the sealing surfaces 24, 25 of the outer circumference 35 of the pilot control piston 12 and the inner circumference 27 of the adjacent wall part 27 of the valve housing 14, which can be abutted against each other. Figure 4 is derived from the view.

[0044] The sealing surface 24 of the pilot control piston 12 is located at a transition point 29 between two different diameters D1, D2 of the pilot control piston 12, wherein the larger diameter D1 defines an annular recess 38 in the pilot control piston 12, while the smaller diameter D2 is formed by an annular groove 31 which, in the closed state of the valve seat 23, at least partially overlaps the annular recess 33 in the valve housing 14 from the inside. For the closed position of the valve seat 23, the pilot control piston 12 is moved from its initial position (according to Figure 3 ) moves to the right to the stop position relative to the valve housing 14 (according to Figure 2 and Figure 4 In this way, the sealing surface 24 of the pilot control piston 12 is in contact with the corresponding inclined sealing surface 25 of the valve housing 14. In order to release the valve seat 23, that is to say to establish a fluid connection between the spaces 38, 31, 33 and 78, the pilot control piston 12 is moved in the opposite direction until it occupies, for example, the position according to Figure 3 "No current open" position.

[0045] If Figure 4It further turns out that a diametrically widened guide section 41 of the pilot control piston 12 is present between the annular groove 31 and the annular channel 78, wherein the guide section 41 is guided in each displacement position thereof along an assignable inner circumferential section 27 of the valve housing 14. Thus, a valve seat-tight and thus fluid-tight seal is achieved in each case between the pilot control chamber 20 and the rear region 83 of the valve with the magnet arrangement 16 by means of the closed valve seat 23.

[0046] As can be further seen from the figures, on the side of the valve housing 14 in the direction of the magnet arrangement 16, at a predeterminable distance from the valve seat 23, there is a moving seal 43 which is arranged stationary in the valve housing 14 and preferably surrounds the outer circumference 39 of the pilot control piston 12 with a predeterminable preload. Since the fluid under pressure on the main piston 10 can reach the other side with the magnet arrangement 16, that is, into the rear region 83, via the fluid channel 32 in the pilot control piston 12, the pilot control piston 12 is sealed by means of the moving seal 43, in particular with respect to the tank connection 40 and thus with respect to the tank side T. In the rear region 83, in particular, an actuating rod 84 of the magnet arrangement 16 acts on the one free end side of the movable pilot control piston 12 to actuate it.

[0047] The moving seal 43 preferably consists of a sliding ring seal 85, for example in the form of a segmented Teflon ring, which is prestressed by means of an elastomeric O-ring 87, which is prestressed relative to the outer periphery 39 of the pilot control piston 12 with a predeterminable prestressing force. Preferably, the relevant moving seal 43 is accommodated in the form of a slide seal in an associated groove-shaped recess in the valve housing 14, which can also be assembled in multiple parts as shown in the drawings, which is common in valve technology. The spacing between the annular recess 33 and the moving seal 43 is always less than four times the diameter of the pilot control piston 12 in this area and greater than twice the diameter. In particular, the spacing dimension should be 2.7 times the above-mentioned diameter. Due to this spacing, an overlap is formed between the transition to the annular recess 33 and the beginning of the moving seal 43. If no seal is installed, this overlap is necessary to keep leakage at a low level. In particular, for trouble-free operation and to further improve the seal, a separate annular pressure relief groove 45 is introduced in this region in the outer circumference of the pilot control piston 12. Since, as already described, a further valve seat 49 is provided between the main piston 10 and the valve housing 14 as a further valve seat-sealing valve member 47, and a third valve seat 53 is provided as a third valve seat-sealing valve member 51, which is formed by the closing ball 48 together with an adjacent wall section of the main piston 10, a particularly advantageous load-carrying valve is achieved due to the three installed valve seat-sealing valve members 21, 47 and 51 arranged at different locations.

[0048] Furthermore, the primary piston 10 has a convex spherical end face 98 on its free left side, which is formed by a predeterminable radius for establishing a linear relationship between the stroke of the primary piston 10 and the opening area formed at the fluid connection 44 or 46. Otherwise, the primary piston 10 is guided movably on the inner circumference of the valve housing 14 via a stepped annular surface, wherein the above-mentioned inclined surface forms a further valve seat 49 and thus a second valve seat-sealing valve mechanism 47 is obtained. As soon as the primary piston 10 assumes its position Figure 1 , 2 4, thus achieving overall seat-tight closure between the fluid connections 44, 46. Individual sealing ring systems, usually in the form of conventional O-rings, not described in detail, ensure, as previously given, the fluid-tight delimitation of the individual fluid chambers and fluid paths with respect to one another.

[0049] Especially from Figure 1 It is shown that a measuring rod 92 is fixedly arranged on the second part 72 of the main piston 10, which passes through the pilot control piston 12 and the actuating magnet system 16 in order to pass out with its other free end region into a displacement measuring device, which is generally indicated by 94, and which is provided with two measuring coils 96, so that the displacement movement of the main piston 10 can be detected in two directions in terms of measurement technology. Such a displacement measuring system is known, for example, from DE 10 2012 014 250 A1 for a pressure balance.

Claims

1. A valve having a main piston (10) for controlling a main volume flow and a pilot control piston (12) for controlling a pilot control volume flow, the main piston (10) and the pilot control piston (12) being guided in a longitudinally displaceable manner in a valve housing (14) and the pilot control piston (12) being controllable by means of a magnet arrangement (16), It is characterized in that The position of the main piston (10) can be controlled by means of the pilot control piston (12). The pilot control piston transmits the fluid pressure acting on the main piston (10) to the pilot control chamber (20) via the fluid connection structure (18) according to its movement position, or interrupts the fluid connection structure (18) and connects the pilot control chamber (20) to the tank side or the low-pressure side (T) via another fluid connection structure (19). A valve mechanism (21) is introduced into the other fluid connection structure. Once the fluid connection structure (18) is established between the main piston (10) and the pilot control chamber (20), the valve mechanism is closed in a valve seat sealing manner.

2. The valve according to claim 1, It is characterized in that The valve member (21) is formed by a valve seat (23) which is formed by mutually abuttable sealing surfaces of an outer peripheral part (35) of the pilot control piston (12) and an inner peripheral part (27) of an adjacent wall part (27) of the valve housing (14).

3. The valve according to claim 2, It is characterized in that The sealing surface (24) of the pilot control piston (12) is located at a transition point (29) between two different diameters of the pilot control piston (12), wherein the larger diameter (D1) defines an annular recess (38) in the pilot control piston (12), while the smaller diameter (D2) is formed by an annular groove (31) which, in the closed state of the valve seat (23), at least partially overlaps the annular recess (33) in the valve housing (14) from the inside.

4. The valve according to claim 3, It is characterized in that A channel section (36) engages in the annular recess (38) on the pilot control piston (12), said channel section transitioning into a fluid-conducting channel (32) of the pilot control piston (12) which opens on one side into the pilot control chamber (20).

5. The valve according to claim 3, It is characterized in that When the pilot control piston (12) moves, the fluid connection structure (18) from the main piston (10) via the released valve seat (23) to the pilot control chamber (20) is simultaneously interrupted, and the fluid guide structure in the groove-shaped annular channel (78) on the outer circumference (39) of the pilot control piston (12) via the annular recess (38) and the annular groove (31) is released, and the tank interface (40) on the tank side (T) that permanently guides the fluid flows into the annular channel (78).

6. The valve according to claim 3, It is characterized in that Between the annular groove (31) and the annular channel (78), a guide section (41) of the pilot control piston (12) which is widened in diameter is guided along an assignable inner circumference (27) of the valve housing (14) in each displacement position of the pilot control piston (12).

7. The valve according to claim 1 or 2, It is characterized in that On the side of the valve housing (14) in the direction of the magnet arrangement (16), at a predeterminable distance from the closed valve seat (23), there is a moving seal (43), which surrounds the outer circumference (39) of the pilot control piston (12) with a predeterminable preload force.

8. The valve according to claim 7, It is characterized in that An annular pressure relief groove (45) is introduced along the predeterminable distance on the outer circumference (39) of the pilot control piston (12).

9. The valve according to claim 1 or 2, It is characterized in that A further valve seat (49) is arranged between the main piston (10) and the valve housing (14) as a further valve member (47) in the form of a valve seat seal.

10. The valve according to claim 1 or 2, It is characterized in that A third valve seat (53) is provided as a third valve seat sealing type valve mechanism (51), wherein the third valve seat is formed by a closing ball (48) and an adjacent wall portion of the main piston (10).

11. The valve according to claim 1, It is characterized in that The valve is a proportional valve.

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