EP2855946B1 - Valve for valve assembly - Google Patents

Description

The invention relates to a valve for a valve arrangement for regulating the pressure of a fluid carried in a hydraulic system for supplying pressure to at least one hydraulic consumer, with a valve housing comprising a pilot control stage and a main control stage for at least partial release or blocking of a fluid path from a supply connection to a drain connection, a relief stage for pressure relief of a fluid space arranged between the pilot control stage and the main control stage, the relief stage comparing the load pressure present at a load connection assigned to the at least one hydraulic consumer with the discharge pressure at the discharge connection and releasing the pressure relief when the two pressures approach or equal, the relief stage having a connection controls from the fluid space to a relief line assigned to the drain port, the relief stage being connectable directly to the load port and with load pressure b can be billed.

Such a valve is off, for example WO 2011/045063 A1 known and is used to adapt the fluid flow and the supply pressure to the needs of the at least one hydraulic consumer. The Load pressure, with several hydraulic consumers the highest load pressure, reported back to the valve and taken into account in the pressure control to the effect that a so-called pressureless circulation is set at a load pressure close to or equal to the discharge pressure via the relief stage. If supply pressure is required by the hydraulic consumer and the load pressure rises accordingly, the relief stage is closed again and the pilot control and main control stage assume their respective control positions. In this way, the power loss in the hydraulic system for supplying pressure to the at least one hydraulic consumer can be reduced.

The present invention aims to simplify the structure of the valve and to make the valve accessible to further functions. This object is achieved by a valve with the features of claim 1 in its entirety.

According to the characterizing part of claim 1, it is provided that a connecting line is provided from the pilot stage to the relief line and that the connecting line is routed from a piston chamber (36) of the pilot stage (48) to the relief line in the valve housing.

Load pressure can be applied to the pilot control and / or the main control stage. A connecting line from the pilot stage to the relief line is provided in a fluid-carrying manner. The pressure in a corresponding piston chamber of the pilot stage can be relieved of pressure via the connecting line.

Because the relief stage can be directly connected to the load connection and can be subjected to load pressure, both the transfer of the load pressure to the relief stage and the pressure relief of the fluid space integrated in the valve can be implemented with a few pressure or fluid connections that are easy to create. Appropriately the valve has at least one connecting line, preferably designed as a bore, in the valve housing from the load connection to the relief stage. The load pressure at the load connection can be conveyed directly to the relief stage via the connecting line, ie without the passage or flow of further fluid spaces. Delays or influences possibly associated with further fluid spaces in the operation of the valve according to the invention are avoided.

A particularly compact design of the valve is achieved if at least one of the stages comprises a valve piston which is arranged displaceably in a respective piston chamber in the valve housing and is preferably pretensioned. The piston chamber assigned to the relief stage can be acted upon or acted upon by the load pressure, which is typically present in a load-sensing line, at one end, and the discharge pressure at the other end. The relief stage can be designed as a slide valve or seat valve, the valve piston or the valve element being arranged and preloaded in such a way that a fluid outflow from the fluid chamber can be released for pressure relief at no or only a low load pressure.

It is also advantageous that the pump pressure can be transferred to the fluid space via the main control stage, preferably via a through-hole formed in the corresponding valve piston. The fluid chamber is connected in a fluid-conducting manner to the pressure relief controllable by the relief stage, whereby, depending on the ratio between the two pressures present at the relief stage, the load pressure and the discharge pressure, the latter assumes a pressure relief of the fluid chamber or a blocking position.

The fluid chamber can be subdivided into a first subchamber assigned to the pilot control stage and a second subchamber assigned to the main control stage be, wherein a throttle is preferably arranged between the two subspaces. A throttle arranged between the second subchamber and the first subchamber of the fluid chamber can thus serve as a damping element for the relief stage. In a preferred embodiment of the invention, the relief stage controls a connection from the fluid space, in particular from the second subchamber, to a relief line assigned to the drain connection.

If another connection line is provided from the fluid space, in particular from the first subchamber, to the load connection, a further throttle is preferably arranged in the further connection line. A desired pressure level between the fluid space and the load connection can be set via the further throttle. Fluid, such as hydraulic oil, can flow off at the load connection via the further connecting line from the main control stage to the load connection, so that the valve according to the invention can regulate a corresponding load pressure when the load connection is connected to a hydraulic consumer. In this preferred embodiment of the invention, the relief stage releases a load sensing line for picking up loads on at least one hydraulic consumer.

The invention further comprises a valve arrangement for regulating the pressure of a fluid carried in a hydraulic system for supplying pressure to at least one hydraulic consumer, with at least one valve according to the invention.

Fig. 1

eine Ventilanordnung zur Druckregelung eines in einem Hydrauliksystem zur Druckversorgung zweier hydraulischer Verbraucher geführten Fluids, mit einem im Schnitt gezeigten erfindungsgemäßen Ventil;

Fig. 2a-2d

jeweils einen Schnitt durch das Ventil aus Fig. 1 in unterschiedlichen Schaltstellungen; und

Fig. 3

einen vergrößerten Ausschnitt aus Fig. 2b.

Further features and advantages of the invention emerge from the figures and the following description of the drawing. The features mentioned above and those listed further can be implemented according to the invention individually or in any combination with one another. The features shown in the figures are purely schematic and should not be understood to be true to scale. It shows:

Fig. 1

a valve arrangement for regulating the pressure of a fluid guided in a hydraulic system for supplying pressure to two hydraulic consumers, with a valve according to the invention shown in section;

Figures 2a-2d

each cut a section through the valve Fig. 1 in different switch positions; and

Fig. 3

an enlarged section Figure 2b .

Fig. 1 shows a valve arrangement 10 with a closed hydraulic circuit for supplying two hydraulic consumers 12a, 12b with fluid. Fluid is conveyed with a pump 14 designed as a fixed displacement pump from a reservoir 16 to the hydraulic consumers 12a, 12b, which are each designed as a hydraulic motor with two possible flow directions. The hydraulic circuit comprising the pump 14 and the hydraulic consumers 12a, 12b is closed via a valve 18 according to the invention. The hydraulic consumers 12a, 12b are each controlled via an electrically operated 4/3-way valve 20a, 20b. Means of a shuttle valve 22a, 22b, the load pressure applied to the respective hydraulic consumer 12a, 12b is reported to a load sensing (LS) line 26a, 26b. A 2/2-way valve 24a, 24b with a pressure limiting function in the open switching position is upstream of this valve control.

In order to operate the hydraulic consumers 12a, 12b at a predeterminable speed, the volume flow of the fluid conveyed by the pump 14 is regulated via the valve 18. This combination of a fixed displacement pump with the valve 18 for pressure regulation is a cost-effective alternative to a variable displacement pump.

A check valve 28a, 28b is connected to the hydraulic circuit in front of each shuttle valve 22a, 22b in the load sensing lines 26a, 26b provided for load tapping on the respective hydraulic consumer 12a, 12b, with each check valve 28a, 28b having the same set opening pressure and in the direction of the valve 18, more precisely in the direction of its load-sensing connection LS, opens. This parallel connection of the load sensing lines 26a, 26b with respect to the valve 18 enables the two load pressures at the hydraulic consumers 12a, 12b to be compared, the higher of the two load pressures being taken into account for pressure control at the valve 18.

The valve 18 is connected or can be connected to the load sensing lines 26a, 26b via its load connection LS. The valve 18 is connected with its supply connection P to the supply line 29 supplied with pressure by the pump 14 and leading to the hydraulic consumers 12a, 12b and with its outlet connection T to a reservoir 16, which can be a pressure medium container or a tank. connectable. The valve 18 is an independent, tradable unit and can be inserted into the valve arrangement 10 as required.

The design of the valve 18 is the Figures 2a-2d can be removed, each showing in section the valve 18 with a cartridge-like valve housing 30 designed as a screw-in valve. A first piston chamber 32, a fluid chamber 34, which is divided into a first subchamber 35b and a second subchamber 35a, and a second piston chamber 36 are formed in the valve housing 30 coaxially to the axis of rotation R. By means of valve pistons displaceable in the respective piston chamber 32, 36 parallel to the axis of rotation R, a main control stage 38 is formed in the first piston chamber 32 and a pilot stage 48 is formed in the second piston chamber 36. The respective valve piston is pretensioned by a first spring element 40 and a second spring element 50.

A third piston chamber 52 formed in the valve housing 30 is connected in parallel to the fluid chamber 34 and with this, more precisely with the second subchamber 35a, via a connection 60 in a fluid or pressure-carrying manner Valve piston of the relief stage 54. The third piston chamber 52 is connected to the load connection LS via a connecting line 61 and to the drain port T via a relief line 62, so that the load pressure and the drain pressure are present at the relief stage 54. The relief stage 54 compares the load pressure with the discharge pressure and, as soon as the load pressure at the load connection LS is close to or equal to the discharge pressure at the discharge connection T, opens a bypass for pressure relief of the fluid space 34.

In the exemplary embodiment shown, the bypass is implemented by a connection 60 between the fluid space 34 and the relief line 62 leading to the drain port T, the connection 60 being formed by the valve piston of the relief stage 54, as in FIG Figure 2b and 2c shown, releasable, or, as in the Fig. 2a and 2d shown is lockable. In the releasing position of the valve piston of the relief stage 54 is an in This formed annular groove 58 is arranged in the intersection area between the third piston chamber 52 directed parallel to the axis of rotation R and the connection 60 running transversely to the third piston chamber 52 or to the axis of rotation R. In the open position, cf. Fig. 3 , fluid can flow away from the fluid chamber 34 via the connection 60, past the annular groove 58 of the valve piston of the relief stage 54, via the relief line 62 to the drain port T.

In the representation of the Fig. 2a if the valve piston assigned to the pilot stage 48, acted upon by the second spring element 50, rests against a valve seat formed at the corresponding end of the fluid space 54 or the first sub-space 35b. The valve piston assigned to the main control stage 38, acted upon by the first spring element 40, is arranged in the valve housing 30 in such a way that a fluid path 40 from the supply connection P is blocked via radial passage openings 42 which are formed in a section of the valve housing 30. The load pressure present at the load connection LS exceeds the discharge pressure or tank pressure present at the discharge connection T, so that the third spring element 56 acting on the valve piston of the relief stage 54 is compressed and the bypass for pressure relief, here the connection 60, is blocked, in other words closed .

As soon as the load pressure drops and approaches the discharge pressure, the valve piston moves into the Figure 2b and 2c shown, the connection 60 releasing position. In accordance with the pressure drop in the fluid space 34 associated with the pressure relief, a fluid path from the supply connection P or pump connection to the drain connection T or tank connection is released. While the fluid path in Figure 2b is only partially released, the valve piston of the main control stage 38 is shown in FIG Figure 2c in its position that maximally releases the fluid path and rests against a valve seat formed on the valve housing 30. Via a further connection 60 ', which, designed as a bore, from second piston chamber 36 is guided to the relief line 62 in the valve housing 60, fluid can also flow from this fluid chamber to the drain port T.

The fluid pressure present on the pump side at the main control stage 38 can be transferred to the fluid space 34 between the main control stage 38 and the pilot control stage 48 via a through bore 44 formed centrally in the valve piston of the main control stage 38, ie along the radial axis R. As soon as the load pressure rises again and exceeds the discharge pressure, the relief stage 54 and, accordingly, the connection 60 from the fluid chamber 34 to the discharge port T are closed and the pilot stage 48 is opened by the increasing fluid pressure in the fluid chamber 34, as in FIG Fig. 2d shown. In the next step, the valve or switch position of the Fig. 2a , the blocking of the fluid path from the supply port P to the drain port T.

How in particular Fig. 3 shows, a further connecting line 64 is led from the load connection LS to the fluid chamber 34, more precisely to the first subchamber 35b. A pressure stage in the further connecting line 64 is specified via a further throttle 66. The valve 18 offers a further function, in other words an option, an outflow of fluid, such as hydraulic oil, via the further connecting line 64. When a hydraulic consumer 12a, 12b is connected to the corresponding load connection LS, the valve 18 regulates the corresponding load pressure, which is caused by the relief stage 54 can be reduced as required.

Claims (7)

1. Valve (1) for a valve assembly (10) for regulating the pressure of a fluid guided in a hydraulic system to supply pressure to at least one hydraulic load (12a, 12b), with a valve housing (30) comprising:

   - a pilot control stage (48) and a main control stage (38) to at least partially release or block a fluid path from a supply port (P) to a discharge port (T); and

   - a relief stage (54) for relieving the pressure in a fluid chamber (34) arranged between the pilot control stage (48) and the main control stage (38), the relief stage (54) comparing the load pressure present at a load port (LS) assigned to the at least one hydraulic load (12a, 12b) with the discharge pressure at the discharge port (T) and, if the two pressures are approximately similar or equal, releasing the pressure relief, the relief stage (54) controlling a connection (60) between the fluid chamber (34) and a pressure relief pipe (62) assigned to the discharge port (T), the relief stage (54) being able to be connected directly to the load port (LS) and load pressure being able to be applied to said relief stage, characterised in that a connecting pipe (60') is provided from the pilot control stage (48) to the pressure relief pipe (62) and in that the connecting pipe (60') is guided from a piston chamber (36) in the pilot control stage (48) to the relief pipe (62) in the valve housing (30).
2. Valve according to claim 1, characterised in that the valve (18) comprises at least one connecting pipe (61) formed in the valve housing (30), preferably as a drilled hole, from the load port (LS) to the relief stage (54).
3. Valve according to claim 2, characterised in that at least one of the stages (38, 48, 54) comprises a valve piston, which is slideably arranged and preferably preloaded in a respective piston chamber (32, 36, 52) in the valve housing (30).
4. Valve according to any one of the preceding claims, characterised in that the pump pressure can be transferred to the fluid chamber (34) via the main control stage (38), preferably via a through hole (44) formed in the corresponding valve piston.
5. Valve according to any one of the preceding claims, characterised in that the fluid chamber (34) is subdivided into a first partial chamber (35b) assigned to the pilot control stage (48) and a second partial chamber (35a) assigned to the main control stage (38), a throttle or orifice plate (46) preferably being arranged between the two partial chambers (35a, 35b).
6. Valve according to any one of the preceding claims, characterised in that load pressure can be applied to the pilot control stage (48) and/or the main control stage (38).
7. Valve assembly (10) to regulate the pressure of a fluid conducted in a hydraulic system to supply pressure to at least one hydraulic load (12a, 12b), with at least one valve (18) according to any one of the preceding claims.

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