EP2220379A1

EP2220379A1 - Hydraulic valve device

Info

Publication number: EP2220379A1
Application number: EP08849706A
Authority: EP
Inventors: Winfried RÜB
Original assignee: Hydac Fluidtechnik GmbH
Current assignee: Hydac Filtertechnik GmbH
Priority date: 2007-11-14
Filing date: 2008-11-13
Publication date: 2010-08-25
Anticipated expiration: 2028-11-13
Also published as: JP2011503483A; WO2009062707A1; DK2220379T3; EP2220379B8; US20110132476A1; EP2220379B1; DE102007054135A1

Abstract

The invention relates to a hydraulic valve device having a fluid connector arrangement (10) comprising at least one pressure supply connector P for providing a pump pressure, a return flow connector R, - a section load sensing connector LS, two control connectors P'A and P'B, and two utility connectors A, B for providing a utility connection pressure, and having a displaceable control device (18) for at least partially controlling the connector arrangement (10), wherein a pressure balance (14) is connected upstream of the control device (18), and wherein the pressure balance (14) comprises a check valve (56). Because a fluid-conducting connection to the reverse flow connector R may be produced by means of the pressure balance (14) and the pressure balance (14) interacts with the check valve (56) such that, at least during control processes of the pressure balance (14) relating to the pressure supply connector P, the check valve (56) is held in the open position thereof such that fluid flowing back from one of the control connectors P'A, P'B flows in the direction of the return flow connector R controlled by the pressure balance (14), the control options are broadened for the valve device according to the invention.

Description

Hydac Filtertechnik GmbH, industrial area, 66280 Sulzbach / Saar

Hydraulic valve device

The invention relates to a hydraulic valve device having a fluid connection arrangement comprising at least one pressure supply port P for providing a pump pressure, a return port R, a section load sensing port LS two control ports PΑ and P'B and two Nutzanschlüsse A, B to provide a Nutzanschlußdruckes and with a movable Control device for at least partially controlling individual terminals of the terminal arrangement, wherein the control device is preceded by a pressure compensator, and wherein the pressure compensator has a check valve.

By DE 603 04 663 T2 a hydraulic valve assembly is known with a supply connection arrangement having a high pressure port P and a low pressure port T, a working port arrangement having two working or Nutzanschlüsse A, B, which are connectable to a consumer, a directional valve and a see between the directional valve and the supply port assembly P, T arranged compensation valve whose pressure output is connected to a pressure input of the directional valve, the compensation valve having a discharge output, which is connected to the pressure output is connectable and a movable from a starting position in opposite directions valve element in the form of a slide which is acted upon on one side by the pressure in the load-sensing line and the force of a spring and on the opposite side of the pressure at the pressure output, wherein the valve element when moving in a Direction a pressure control function and when moving in the opposite direction, a pressure relief function, wherein the slide has a longitudinal channel which is connected via a transverse bore to the pressure output and terminates in a first pressure chamber, and wherein the longitudinal channel beyond the transverse bore and via a closable opening is connectable to a second pressure chamber in which a relief pressure prevails.

The movable control device is preceded by a pressure compensator with an independent leakage discharge, wherein the pertinent relief output is connected to a load-sensing line, which communicates with the directional valve.

With this known solution, it is possible to counteract so-called parasitic pressure propagations, which can occur in particular at higher pressures and which can lead to the lifting of loads in an unwanted and dangerous manner. However, safety valves which have already been used in this context may also be leaking and even contribute to the emergence of parasitic pressure propagation.

From EP 1 500 825 A2 a directional valve for controlling a consumer with two coaxially arranged spools is known, via the two connected to the consumer working ports A, B with a pressure supply port P or a return port R are connected and are biased in a normal position , in which between the spools a spring device is arranged with a spring element. Due to the fact that, in the known solution, the spring device has a limitation for defining a maximum effective length of the spring element, the control slides can only be removed from each other to a certain extent by the "binding" of the centrally arranged spring element, so that the control slides in the In the basic position, essentially the bias of their respective external spring force is applied and occupies a defined basic position, which correspondingly increases the functional reliability of the known solution, and in this solution too, the control device is preceded by a pressure compensator in the hydraulic fluid direction.

From DE 10 2005 033 222 AI a so-called. LUDV valve assembly is known in which a directional control valve forms a Zulaufmeßblende, which is followed by an individual pressure compensator. About the LUDV valve assembly, a hydraulic consumer is controlled, which is connected to two consumer or Nutzanschlüsse the control arrangement. To set a rapid traverse two pressure chambers of the consumer can be connected to each other and to a pressure medium source. In order to prevent a "sagging" of the consumer, this connection of the two consumer connections takes place via a pressure medium flow path in which a check valve is arranged and / or the first-mentioned consumer connection is possible at high speed only via the pressure medium flow path and the opened non-return valve, thus preventing inadvertent movement of a hydraulic consumer in a rapid traverse position of the valve arrangement.

By the generic DE 42 34 037 C2, a hydraulic valve device is known, in particular for mobile working equipment, with a Block with a directional control valve with a metering orifice, with a together with the orifice a pressure medium flow regulating pressure compensator with a control piston which is displaceable in a bore of the housing block and a pressure surface acted upon by the load pressure has up, and with a load signal valve whose valve body in one opposite the control piston of the pressure compensator separate load signal valve housing is located and can also be acted upon by the load pressure. The fact that according to the known solution, the load signal valve housing is inserted into the bore of the housing block and limited by the control piston of the pressure balance acted upon by the load pressure pressure chamber, the load signal valve used can be produced with little effort and its exchange is possible in a simple manner, so that a for so-called mono blocks well suited construction is realized.

The thus constructed control device is preceded by a conventional pressure compensator, wherein the pressure compensator has a check valve which allows a check function when the pressure compensator is opened so that the respective Nutzanschlußdruck can not drop below a briefly too low pump pressure, so as to ensure that when starting a hydraulic Consumer group against "standing loads" due to connected to the user terminals hydraulic consumers, a dangerous lowering of the load is avoided with certainty, especially if briefly the pump pressure for the control should prove too low while the check valve is permanently held in its closed position.

Based on this prior art, the present invention seeks to provide a hydraulic valve device solution having an upstream pressure compensator, which builds compact together with the overall valve construction, which otherwise fluctuates little in operation. susceptible and thus functionally reliable and increases the control options with the valve device. This object is achieved by a valve device with the features of claim 1 in its entirety.

Characterized in that according to the characterizing part of claim 1 by means of the pressure compensator a fluid-carrying connection to the return port R can be produced and that the pressure compensator cooperates with the check valve such that at least during control operations of the pressure balance concerning the pressure supply port P, the check valve in one of its open Positions is held that flows back from one of the control terminals P'A, P'B back flowing fluid from the pressure compensator to the return port R down, as shown in the closest prior art, on the one hand ensures that the Rückschlagfunk- tion with open pressure compensator used and thus the respective Nutzanschlußdruck can not drop below a short time to low pump pressure, so that when starting a hydraulic consumer circuit against "standing loads" due to connected to the user ports A, B hydraulic consumers, a hazardous Ie lowering the load is certainly avoided, especially if briefly the pump pressure for the control should prove too low.

On the other hand, with the pertinent inventive design not only in the frame outlined a regulation in the inflow to the respective Nutzanschluß A, B possible, but also a pressure control for the back flowing medium of one of the control terminals PΑ or P'B to the tank over the above Return connection R. In this way, for example, in the case of what is known as a contact pressure control, an undesired increase in pressure can be avoided, which increases the extent of the control application area with the valve device. With the pertinent contact pressure control can be a driven load, for example in the form of a mowing head or the like. Define a ground contour defined, with a defined ground contact force. The pertinent application is only one possible example of use and the solution according to the invention can be used wherever it is particularly important to keep the constant forces on work equipment constant.

The advantageous connection of the return port to avoid an unwanted increase in pressure when hydraulic fluid returns from the respective consumer Nutzanschluß contributes, that on the dahinge- coming design a sufficient flow area can be opened to the tank, which simplifies the scheme. If the fluid flows back, a check valve can be used even then, because the pressure compensator in the connecting line with the return connection advantageously prevents the closing stroke of the check valve. Due to the introduced non-return function within the

Pressure compensator proves to be very stable in operation and is therefore not susceptible to vibration, which allows a defined continuous control of the consumer in the hydraulic circuit in both directions. Moreover, the pressure compensator builds compact, which overall benefits a compact space-saving overall valve design.

Since by means of the check function certain fluid connection lines are controlled with, they need not be provided separately within the valve design, which helps further save space. Due to the desired modular system with modular individual components, the valve device according to the invention is also inexpensive to manufacture and otherwise reliable in use.

The upstream pressure compensator within the valve device is preferably part of a proportional load sensing directional control valve with pump and return ports on the way valve axis. By the Circuit logic of the slide axis conditionally there are always at least one pressure supply port P and two return ports R present or alternatively two pressure supply ports P, PST and a return port R. In the following description is because of further advantages in the valve and modular construction here variant with two pressure supply ports P, PST and a return port R explained in more detail. However, the corresponding conditions also apply accordingly to the other possible variant.

In the following the valve device according to the invention will be explained in more detail with reference to an embodiment of the drawing. This show in principle and not to scale representation of the

Figure 1 in the manner of a longitudinal section of an embodiment of the hydraulic valve device, wherein the simpler representation because of the non-return function for the pressure compensator in Figure 1 is not shown;

FIG. 2 shows an enlarged illustration relative to FIG. 1 exclusively relative to the pressure compensator with a drawn-back function using a non-return valve.

FIG. 1 shows a fluid connection arrangement designated as a whole by 10. The pertinent fluid connection arrangement 10 has a pressure supply connection P on, a return connection R, a section load-sensing connection LS, two control connections P'A and P'B and two utility connections A, B. The said fluid connections LS, P ' _A , R, P and P'B, A and B are housed in a control housing 12, as seen in the viewing direction on the Fig.1, the lower end of the control housing 12 is provided with a pressure compensator 14 which the terminals LS, P ' _A , R, P and P'B is connected upstream and controls this extent. With the thus upstream pressure compensator 14 is the so-called. Function Mengenabschneidung achieved by a LS-pressure limitation in the spring chamber 16 of the pressure compensator, the Mengenabschneidung example, makes sense if a non-illustrated steering cylinder of a hydraulic working group, connected to the Nutzanschlüsse A, B am Stop is and you want to cut off the inflow so far to avoid overloads.

A control device 18 of the valve device as such is actuated in a known and therefore not described in more detail manner of conventional pilot valves, which are shown for ease of illustration in Figure 1 only insofar as their respective assignable pilot housing 24,26 are addressed. On the output side, the two pilot valves for the control device 18 supply two counteracting control pressures XA and XB. Furthermore, a pump control pressure PST then acts on the respective pilot valve, which in each case forms a further P connection within the variant presented here. Furthermore, a tank connection line T _{0 is} also connected to the respective pilot valve.

Said control device 18 has a horizontally displaceable in the direction of view of Figure 1 control slide 28, which is shown in Figure 1 in its undeflected middle or neutral position. The pertinent neutral position of the spool 28 is supported by two spring memory, which are designed as compression springs 30 and are integrated in a respective assignable spring chamber in the pilot housings 24,26. Also, the pertinent structure is customary in pertinent hydraulic valve devices, so that in this respect will not be discussed in more detail here at this point. The control device 18 with spool 28 is provided with load-sensing terminals 32,34 and load-sensing terminals 36,38, which are interconnected in pairs carrying fluid. Namely, the first load-sensing terminal 32 is fluidly connected to the second load-sensing terminal 38, and the second load-indicating terminal 34 is in fluid communication with the first load-sensing terminal 36. Said reporting terminals and sense terminals are formed in the spool 28 in the form of radial cross-bores and, as the case may be, which axial displacement position of the control slide 28 assumes, the said connections 32, 34, 36 and 38 come into fluid-conducting or blocking connection with the respectively assignable connections of the fluid connection arrangement 10.

In order to establish the fluid-carrying connection between the pair-wise assignable load-sensing and load-sensing connections 32, 36, 34, 38, connecting channels 40, 42 arranged within the control slide 28 are used. In this case, one of the connecting channels 40 is designed as a so-called center channel which, in the neutral position of the control device 18 shown in FIG. 1, covers the region between the section load-sensing connection LS and the useful connection B with its axial length. In that regard, the center channel is seen in the direction of the Fig.1 on the left side of the spool 28 and extends in the manner of an attached blind bore along the longitudinal axis of the spool 28. In parallel arrangement for this purpose is provided as a further connecting channel 42 at least one annular longitudinal channel which in turn covers in the neutral position of the control device 18 with its axial length at least the region between the control connection PΑ and the useful connection A. The load-indicating and load-sensing connections 32, 36, 34, 38 are each designed as radially extending bores in the control slide 28.

The middle channel 40 is limited to generate the channel guide in this respect by an insert sleeve 44 which at least partially along its Außenumfan- ges arranged in a predetermined central region with the inner wall of the spool 28 in this area limits the annular longitudinal channel 42, which may also be formed from a plurality of concentric with the central channel 40 individual channels (not shown). The axial length of the insert sleeve 44 extends according to the illustration of Figure 1 between the first load reporting terminal 32 and a narrowed offset between the first Lastfühlanschluß 36 and second Lastfühlanschluß 38 in the height of the return port R. While the insert sleeve 44 with their one in the direction of the 1 seen right end is supported on said bottleneck within the longitudinal bore of the spool 28, the opposite other free end in the region of the first load-indicating connection 32 is based on a compression spring 45 which extends so far between a closure plug 46 and the free end of the sleeve and Insofar as the insert sleeve 44 holds in its position with a predefinable bias. About the pertinent arrangement can be optionally compensate for existing length tolerances in the system insert sleeve 44 to spool 28.

As further shown in Fig.1, the spool 28 along its outer periphery two longitudinal control channels 48,50, which open in the neutral position of the control device 18 respectively in the Nutzanschluß A and the Nutzanschluß B. In that regard, opens in the neutral position of the spool 28 shown, the load sensing bore 36 under the housing wall between the user port A and the return port R.

Overall, the hydraulic valve device shown forms a so-called. LS directional control valve with upstream pressure compensator 14. This valve devices are used basically to hedge parts of the hydraulic circuit, for which additionally a not-shown pressure relief valve may be provided and the load-sensing portion LS is compared to LS _ma χ preferably by means of a shuttle valve (not shown). The hydraulic valve device has the construction length of a short valve axis design with respect to known solutions fewer ring channels. With the upstream pressure compensator 14, the function already described quantity cut by LS pressure limitation in the spring chamber 16 of the pressure compensator 14 is possible.

In the following, the pressure compensator 14 will now be explained in more detail with reference to FIG. 2 of its inventive design, FIG. 2 also showing the non-return function of the pressure compensator 14, which was omitted in FIG. 1 for the sake of simpler presentation , Otherwise, the Fig.2 corresponds to the lower half of Figure 1, seen in the direction of Fig.1 below the control device 18, the pressure compensator 14, which is so far taken in the same control housing 12 of the overall valve device.

To realize the non-return function, the pressure compensator 14 has a check valve 56 whose non-return function is used with open pressure compensator and ensures that the respective Nutzanschlußdruck at the Nutzanschluß A or B can not drop below a briefly too low pump pressure, which will be explained in more detail below , According to the representation of Figure 2, the check valve 56 acts with its non-return function on the control terminal P'e; but there are also other configurations conceivable, for example, in which the check valve 56 then acts on the control terminal P'A or on both sides of both control terminals PΑ and P'B in reverse functional arrangement. The check valve 56 has a valve body 58, which is supported on a valve spring designed as a compression spring 60. Seen in the direction of FIG. 2, the valve spring 60 attempts to push the valve body 58 to the left, in order to hold it in such a manner in abutment with parts of a control piston 62 of the pressure compensator 14. The pertinent control piston 62 is supported at its other end against a likewise If the valve body 58 of the check valve 56 is in contact with the control piston 62 as shown in FIG opposite direction both the control spring 64 and the valve spring 60 a.

The control piston 62 has passage openings divided into individual functional groups, with the first group 66 being assigned to the control connection PΑ and the second group 68 being assigned to the control connection P ' _B. The third group 70 is assigned to the pressure supply connection P and the fourth group 72 is formed in the manner of relief holes, the return port R is assigned. Except for the fourth group 72, the other groups 66,68,70 are formed of two adjacent rows of passages with different bore diameters, which helps to facilitate the control function for the pressure compensator 14.

The control spring 62 is also supported with its other free end, which faces away from the check valve 56, on wall parts 74 of the pressure balance housing, which to this extent is part of the control housing 12. Moreover, the control spring 64 is received in the spring chamber 16 of the control housing 12 and the spring chamber 16 is so far in media connection with the section load-LS, which can be equipped with a pressure limiting function, not shown, for example, using a pressure relief valve, not shown.

2, in a control function of the control piston 62, the valve body 58 with its left free end at least partially releases the second group 68 at passage openings in the direction of the control port P'B. In the blocking position of the check valve 56, the pertinent second group 68 and thus the said fluid away blocked by the valve body 58, which is supported so far with its free end face on a shoulder 78 of the control piston 62. Further, the valve body 58 at its facing in the direction of the interior of the control piston 62 end face a recess 80, preferably in the form of an inwardly facing cone on. The maximum stroke shown in Figure 2 of the valve body 58 of the check valve 56 is so far limited in its closing direction by a limiting device 82 having a stop screw, which, as shown, engages with its free end 84 in a recess of the valve body 58 and the screw head 86th abuts a boundary wall 87 of a screw-in 90, which is screwed in a sealing manner in the pressure compensator housing and in the repair and assembly case after its removal allows access to the inner parts of the pressure compensator 14. Is the pressure compensator against the one shown in Figure 2 a control position in the unpressurized state, the control spring 64 pushes the control piston 62 in the direction of FIG. 2 seen to the right and the right free end 92 of the control piston 62 strikes against the adjacent end 94 of Then screw-in part 90.

The pressure compensator 14 has a first pressure outlet to PΑ and a second pressure outlet to P'B to supply the spool 28, the controller 18. In this respect, the two pressure outputs to PΑ and P'B without additional additional lines by the pressure compensator 14 itself pressure-equalizing connect, which helps save space. In that regard, the connection of the two mentioned pressure outputs to PΑ and P'B through the free center space in the control piston 62 and the first group 66 at fluid passages to the pressure outlet to PΑ and in the form of the second group 68 to the pressure outlet to P'B. The supply connection P of the pressure compensator 14 is seen in the longitudinal direction so seen between the two pressure outputs to PΑ and P'B formed by the already mentioned control connections. Furthermore, the Pressure compensator 14 via the additional return port R, which is located between the pressure supply port P and the control spring 64.

Upon movement of the control piston 62 against the control spring 64 of the pressure supply port P is first closed, by moving away the third group 70 at passage points, and on further movement to the left of the return port R is opened, through the fourth group 72 at passage openings. When the pressure compensator 14 is in its open position, it abuts the screw-in part 90, as already explained, so that the check valve 56 can assume its closed position. On the other hand, with rules of the pressure compensator 14 with a position close to the P control edge 96 or the R control edge 98, the check valve 56 can not close so that returning oil can flow away from the control connection P'B to the return connection R. If the valve body 58 has the depression 80, this results in a high momentum force in the jet deflection of the fluid within the hollow control piston 62, resulting in a large opening stroke for the check valve 56 resulting in a small pressure loss.

In the following, the pressure compensator solution according to the invention will be explained in more detail with reference to a functional description. As already stated, in the unpressurized state, the control spring 64 of the pressure compensator 14, the control piston 62 to the stop on the screw 90 of the control housing 12 at. The pressure supply port P is then fluidly connected to the third group 70 at passage openings, with the interior of the control piston 62 and in so far with the control terminals PΑ and P'B, which form the extent the pressure outputs. The return port R is shut off. Now, in the neutral position of the spool 28, the hydraulic supply pump (not shown) is turned on, pressure fluid flows into the control ports PΑ and P'B the pressure compensator 14. In this case, the pressure in the pressure compensator 14 increases and the resulting Compression force pushes the control piston 62 against the control spring 64 until the P - control edge 96 just closes. If pressure fluid under high pressure continues to enter the pressure compensator 14 due to gap leakage, then the control piston 62 continues to move against the control spring 64 until the R control edge opens and the undesired overpressure degrades to such an extent until the working pressure in the control connections PΑ and P'B just keeps the control pressure of the control spring 64 in balance.

Using the example of a not-shown slope mower with mowing head will now be described in more detail below a bearing pressure control with the hydraulic valve device. First, the spool 28, for example, brought in position "lifting" on the Nutzanschluß B and an unspecified LS-pressure relief valve set to its maximum value.The lifting cylinder then drives the mowing head up to the cylinder stop of a hydraulic working cylinder, not shown Assuming the lifting pressure is below 50 bar and the associated LS pressure relief valve is set to 80 bar, then the cutting head drops below its own weight, because the pressure compensator 14 at its control ports PΑ and P'B now only a value of 80 bar plus the spring force of the pressure compensator 14. The spool 28 is still in the "lifting" position and the hydraulic fluid flows from the working cylinder to the working port B and then to the control port P'B and from there to the open Rücklaufan- conclusion R, which in the control position 2 is shown.

The cutting head then sinks further down to the ground where it rests with a differential force (= ground contact force) of 150 bar less the 80 bar + spring force. At a spring force of 5 bar applied then acts a ground contact force corresponding to 65 bar. During mowing, the mowing head is pulled over the ground contour. Will he be informed of an pulled exercise, then the mowing head raises alike, with hydraulic fluid is removed from the control terminal P'B. Consequently, the pressure at the control port P'B decreases and the control piston 62 moves into an opening position and allows pressure fluid to flow in from the pressure supply port P until force balance on the pressure compensator 14 is reached again.

If the mowing head is pulled through a depression, then the cutting head sinks and presses hydraulic fluid into the control connection P ' _B. There, the pressure rises and the control piston 62 moves against the control spring 64. In this case, the return port R is opened and the hydraulic fluid flows off until again force balance on the control piston 62 has occurred. However, the valve body 58 of the check valve 56 can only prevent the reflux until the control piston 62 has closed approximately the P control edge 96. If the control piston 62 continues to move against the control spring 64, then the valve body 58 is held in its position by the limiting device 82 described, thus remaining in that respect, and a return flow cross-section opens.

The check valve 56 in the pressure compensator 14 thus prevents the load from falling back into the pressure supply connection P. If, for example, the mowing head continues to be raised from a stopped position with a weight load corresponding to 150 bar, the following functional situation takes place. From a neutral position of the pressure system, the spool 28 is deflected and the load of 150 bar is reported on the one hand to the pressure compensator 14 and on the other hand to a not shown in detail D ruck tively I system (pump regulator or circulation pressure compensator). Building up the pump pressure can take a few tenths of a second. During this short period of time, the control piston 62 has already run to its stop under the influence of the reported 150 bar on the spring side and has thus opened the supply port P to the maximum. net. Through the open spool 28 then the load pressure of 150 bar to the pressure output P ' _{B of} the pressure compensator 14 has prevailed. The control piston 62 remains but in the fully open position, because on both of its front sides, the same pressure acts and the spring force generates the excess of force to hold the open position. The check valve 56 is closed, namely until the pump pressure has increased to over 150 bar and the lifting - ride can begin. In that regard, is ruled out with certainty that the respective Nutzanschlußdruck can not fall below a briefly too low pump pressure with the result that the load unintentionally lowers and the displaced fluid quantity is pushed into the pressure supply port P in the reverse direction, which otherwise a high risk of danger with it would bring.

In summary, it can therefore be stated that with the valve solution according to the invention, no unacceptably high dynamic pressure (P ' _A and' B) can build up in the neutral position of the spool valve 28 in the return port R in the neutral position of the spool valve. Furthermore, a pressure control in both flow directions, ie front and to the consumer A or B, allows. Furthermore, a good radial Strahlfüh- tion at the respective control edge by radial transverse bores within the hollow control piston 62, realized by the groups 66,68,70 and 72 at Fluiddurchlaßöffnungen in the control piston 62. Thus, it comes only to small disturbing flow forces in axial direction parallel to the respective deflection direction of the control piston 62nd

An essential aspect of the solution according to the invention is also that the pressure compensator described has a connection to the tank return, which may be formed by the return port R. By virtue of this configuration, a sufficient cross-section to the tank can be opened with the result that medium flowing back into the tank can be passed (pressure regulation) and not only in the outflow direction to the working area. Conclusion a rule is possible. The integrated non-return valve saves installation space and in its optional version with maximum closing stroke (screw head), it guarantees a pressure regulation that allows a return flow from the respective working connection to the pressure compensator and the tank connection. In the solution according to the invention, the pressure compensator moves into the tank connection and the check valve seat is no longer accessible in this control position. Particular importance is attached to the fact that the return port R occupies a central central position within the indicated connection points of Figure 1.

Claims

Patent claims

Hydraulic valve device having a fluid connection arrangement (10) comprising at least - a pressure supply port P for providing a pump pressure, a return port R, a section load sensing port LS two control ports PΑ and P'B and - two Nutzanschlüsse A, B for providing a Nutzanschlußdruckes and a movable control device (18) for at least partially controlling individual terminals of the terminal assembly (10), wherein the control device (18) a pressure compensator (14) is connected upstream, and wherein the pressure compensator (14) has a check valve (56), characterized characterized in that by means of the pressure compensator (14) a fluid-carrying connection to the return port R can be produced and that the pressure compensator (14) cooperates with the check valve (56) such that at least during control operations of the pressure compensator (14) concerning the pressure supply port P, the check valve (56 ) so in one of his geöff Neten positions is maintained, that flows back from one of the control terminals P'A, P'B back flowing fluid from the pressure compensator (14) to the return port R.

2. Valve device according to claim 1, characterized in that the check valve (56) acts with its check function on the control terminal PΑ or P ' _B.

3. A valve device according to claim 1 or 2, characterized in that the check valve (56) with its valve body (58) is supported against a valve spring (60), the valve body (58) at a Re- gelkolben (62) of the pressure compensator (14) to keep looking, which is supported at the opposite end to the check valve (56) on a control spring (64).

4. A valve device according to claim 3, characterized in that when adjoining the valve body (58) on the control piston (62) of the pressure compensator (14) on this (62) in opposite directions, the valve spring (60) and the control spring (64) act.

5. A valve device according to claim 3 or 4, characterized in that the control piston (62) in functional groups (66,68,70,72) has divided passage openings, each of the pressure supply port P (76), the return port R (72) and the both control terminals P'A (66) and P'B (68) are assigned.

6. Valve device according to one of claims 3 to 5, characterized in that the control spring (64) at its the valve body (58) facing away from the end parts (74) of the pressure compensator housing is supported.

7. Valve device according to one of claims 3 to 6, characterized in that the valve body (58) on its in the direction of the interior of the control piston (62) facing the end face has a recess (80), preferably in the form of an inner cone.

8. Valve device according to one of claims 3 to 7, characterized in that in the unpressurized state of the pressure compensator (14) the control spring (64) the control piston (62) against the action of the control spring (64) against a stop (94) of the pressure compensator housing Plant brings.

9. Valve device according to one of claims 1 to 8, characterized in that the control spring (64) in a spring chamber (1 6) of the pressure balance housing into which the section load-sensing connection (LS) opens.

10. Valve device according to one of claims 3 to 9, characterized in that the maximum stroke of the valve body (58) of the check valve (56) is limited in its closing direction by a limiting device (82).