EP2855946A1

EP2855946A1 - Valve for valve assembly

Info

Publication number: EP2855946A1
Application number: EP13722998.5A
Authority: EP
Inventors: Philipp Hilzendegen; Peter Bruck; Dominique DEHLINGER
Original assignee: Hydac Fluidtechnik GmbH
Current assignee: Hydac Fluidtechnik GmbH
Priority date: 2012-05-25
Filing date: 2013-05-15
Publication date: 2015-04-08
Anticipated expiration: 2033-05-15
Also published as: EP2855946B1; DE102012010522A1; WO2013174489A1; US20150107699A1; US9677575B2

Abstract

The invention relates to a valve (18) for a valve assembly (10) for regulating the pressure of a fluid guided in a hydraulic system for supplying pressure to at least one hydraulic consumer (12a, 12b), comprising a pilot control stage (48) and a main control stage (38) for at least partially clearing or blocking a fluid path from a supply connection (P) to an outflow connection (T), a relief stage (54) for pressure relief of a fluid chamber arranged between the pilot control stage (48) and the main control stage (38). The relief stage (54) compares the existing load pressure at a load terminal (LS) dedicated to the at least one hydraulic consumer (12a, 12b) with the outflow pressure at the outflow connection (T), clearing the pressure relief if both pressures are approximately the same or identical, which valve is characterized in that the relief stage (54) can be directly connected to the load terminal (LS) and can be charged with load pressure.

Description

Valve for valve arrangement

The invention relates to a valve for a valve arrangement for pressure control of a fluid in a hydraulic system for pressure supply at least one hydraulic consumer comprising a pilot stage and a main control stage for at least partially releasing or blocking a fluid path from a supply port to a drain port, a discharge stage for pressure relief between the pre-control and the main control stage arranged fluid space, wherein the relief stage compares the at one of the at least one hydraulic load associated load connection pending load pressure with the discharge pressure at the drain port and releases the pressure relief on approach or equality of both pressures.

Such a valve is known, for example, from WO 201 1/045063 A1 and is used to adapt the pumped fluid flow and the supply pressure to the requirements of the at least one hydraulic consumer. A hydraulic load-sensing system reports the load pressure, in the case of several hydraulic consumers the highest load pressure, back to the valve and takes it into account in the pressure control so that at a load pressure close to or equal to the discharge pressure via the discharge stage a so-called depressurized circulation is set. As far as supply pressure is required by the hydraulic consumer and the load pressure increases accordingly, the discharge stage closed again and the pre-tax and the main tax level take their respective control position. In this way, the power loss in the hydraulic system for pressure supply of the at least one hydraulic consumer can be reduced.

The present invention has the object to simplify the construction of the valve and to make the valve more functions accessible. This object is achieved by a valve having the features of claim 1 in its entirety.

Characterized in that according to the characterizing part of claim 1, the discharge stage can be connected directly to the load connection and load pressure, both the transfer of the load pressure to the discharge stage and the valve integrated pressure relief of Fluid idraums with a few, to be formed in a simple manner pressure - or Fl u idid connections be realized. Conveniently, the valve has a valve housing with at least one in this, preferably as a bore, formed connecting line from Lastanschuss to the discharge stage. Via the connecting line, the load pressure applied to the load connection can be led directly to the unloading stage, ie without the passage or passage of further fluid spaces. With further fluid spaces possibly associated delays or interference during 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 biased. The discharge chamber associated with the piston chamber is at one end with the load pressure, which is typically present in a load-sensing line, and at the other end acted upon by the discharge pressure or acted upon. The relief stage can be used as a slide or seat valve be formed, wherein the valve piston or the valve element is arranged and biased such that a fluid drain from the fluid chamber to the pressure relief at no or only a small load pressure can be released.

Furthermore, it is advantageous that the pump pressure can be transmitted to the fluid space via the main control stage, preferably via a through bore formed in the corresponding valve piston. The fluid space is fluidly connected to the controllable through the relief stage pressure relief, according to the ratio between the two pending at the relief stage pressures, the load pressure and the discharge pressure, this one releasing the pressure relief of the fluid space or assumes a blocking position. The fluid space can be subdivided into a first subspace assigned to the pilot stage and a second subspace assigned to the main control stage, wherein a throttle is preferably arranged between the two subspaces. A choke arranged between the second subspace and the first subspace of the fluid space can thus serve as an attenuator for the desolvation stage. In a preferred embodiment of the invention, the relief stage controls a connection from the fluid space, in particular from the second subspace, to a discharge line assigned to the discharge port. Further, it is advantageous that the pilot control and / or the main control stage can be acted upon by load pressure. Particularly preferably, a connecting line from the pilot stage to the discharge line is provided in a fluid-conducting manner. Via the connecting line, a pressure relief of a corresponding piston chamber of the pilot stage can take place. This connection line can be led from the second piston chamber to the relief line in the valve housing. If a further connecting line is provided from the fluid space, in particular from the first subspace, to the load connection, a further throttle is preferably arranged in the further connecting line. About the further throttle, a desired pressure level between the fluid chamber and the load port can be adjusted. Via the further connection line from the main control stage to the load connection, fluid, such as hydraulic oil, can flow out at the load connection, so that the valve according to the invention can regulate a corresponding load pressure when connecting the load connection to a hydraulic consumer. In this preferred embodiment of the invention, the relief stage releases a load-sensing line for load pick-off at the at least one hydraulic consumer.

Instead of an integrated design of the pilot stage, main control stage and discharge stage, a decentralized individual arrangement of said stages to a valve according to the invention is also possible. The relief stage can be arranged, for example, in parallel arrangement to the pilot control and main control stage between a pump and a container for fluid. The discharge stage can be directly piloted, but it is also conceivable to form the discharge stage as an electrically operable 2/2-way valve, which can be controlled, for example, by a control and / or regulating device processing the signals of a pressure sensor. The invention further comprises a valve arrangement for pressure regulation of a fluid supplied in a hydraulic system for supplying pressure to at least one hydraulic consumer, with at least one valve according to the invention. Further features and advantages of the invention will become apparent from the figures and the following description of the drawing. The above named and the further cited features can be inventively realized individually or in any combination with each other. The features shown in the figures are purely schematic and not to scale. It shows:

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

2a-2d each show a section through the valve of Figure 1 in different switching positions ..; and

Fig. 3 is an enlarged detail of Fig. 2b.

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 designed as a fixed displacement pump 14 from a reservoir 16 to the hydraulic consumers 12a, 12b, which are each designed as a hydraulic motor with two possible flow directions. By means of a valve 18 according to the invention, the hydraulic circuit from the pump 14 and the hydraulic consumers 12a, 12b is closed. The hydraulic consumers 12a, 12b are each controlled via an electrically operated 4/3-way valve 20a, 20b. By means of a shuttle valve 22a, 22b of the respective hydraulic consumers 12a, 12b applied load pressure in a load-sensing (LS) line 26a, 26b is reported. This valve control is preceded by a 2/2-way valve 24a, 24b with a pressure limiting function in the open switching position. In order to operate the hydraulic consumers 12a, 12b with a predeterminable speed, the volume flow of the fluid delivered by the pump 14 is regulated via the valve 18. This combination of a fixed displacement pump with the valve 18 for pressure control is a cost-effective alternative to a variable displacement pump.

In the load sensing on the respective hydraulic load 12a, 1 2b provided load sensing lines 26a, 26b, a check valve 28a, 28b is connected in the hydraulic circuit before each shuttle valve 22a, 22b, each check valve 28a, 28b has the same set opening pressure and in the direction of the valve 18, more precisely in the direction of the load-sensing connection LS opens. By means of this parallel connection of the load-sensing lines 26a, 26b with respect to the valve 18, a comparison of the two load pressures on the hydraulic consumers 12a, 1b is made possible, taking into account the higher of the two load pressures for regulating the pressure at the valve 18 ,

The valve 18 is connected via its Lastanschi uss LS with the load-sensing lines 26 a, 26 b and connectable. The valve 18 is connected with its supply connection P to the supply line 29 which is supplied with pressure by the pump 14 and leads to the hydraulic consumers 12a, 12b, and with its discharge connection T to a reservoir 16, which may be a pressure medium container or a tank or connectable. The valve 18 is an independent, tradeable unit and can be used as needed in the valve assembly 10.

The design of the valve 18 is shown in FIGS. 2a-2d, which in each case shows in section the valve 18 with a cartridge-like valve housing 30 designed as a screw-in valve. Coaxially to the axis of rotation R, in the valve housing 30, a first piston space 32, a fluid space 34, which is arranged in a first subspace 35b and a second subspace 35a. is divided, and a second piston chamber 36 is formed. Through in the respective piston chamber 32, 36 parallel to the axis of rotation R displaceable valve piston a main control stage 38 and in the second piston chamber 36, a pilot stage 48 are formed in the first piston chamber 32. By a first spring element 40 and a second spring element 50 of the respective valve piston is biased.

A third in the valve housing 30 formed piston chamber 52. Parallel to the fluid chamber 34 and with this, more precisely with the second subspace 35a, via a connection 60 fluidly or pressure-carrying connected. Slidably disposed in the third piston chamber 52 and biased by a third spring element 56 is a Valve piston of the relief stage 54. The third piston chamber 52 is connected via a connecting line 61 to the load port LS and via a discharge line 62 to the drain port T, so that at the discharge stage 54 the load pressure and the discharge pressure are present. 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 rail 34.

In the exemplary embodiment shown, the bypass is realized by a connection 60 between the fluid space 34 and the discharge line 62 leading to the discharge port T, the connection 60 being releasable by the valve piston of the relief stage 54, as shown in FIGS. 2 b and 2 c. or, as shown in Figs. 2a and 2d, is closable. In the releasing position of the valve piston of the relief stage 54, an annular groove 58 formed therein is arranged in the crossing region between the third piston chamber 52 directed parallel to the axis of rotation R and the connection 60 extending transversely to the third piston chamber 52 or to the axis of rotation R. In the open position, cf. 3, fluid from the fluid space 34 via the connection 60, at the annular groove 58 of the valve piston of the discharge stage 54 over, drain via the discharge line 62 to the drain port T.

In the illustration of FIG. 2 a, the valve piston assigned to the pilot stage 48, acted on by the second spring element 50, abuts against a valve seat formed at the corresponding end of the fluid chamber 54 or the first sub-chamber 35 b. The valve piston assigned to the main control stage 38, acted on by the first spring element 40, is arranged in the valve housing 30 such that a fluid path 40 from the supply port 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 discharge stage 54 is compressed and the bypass for pressure relief, here the connection 60, is closed, in other words closed ,

As soon as the load pressure drops and approaches the discharge pressure, the valve piston moves into the position releasing the connection 60 as shown in FIGS. 2b and 2c. 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 Fig. 2b is only partially released, the valve piston of the main control stage 38 is in the representation of Fig. 2c in its maximum fluid path releasing position and abuts a formed on the valve housing 30 valve seat. Via a further connection 60 ', which, designed as a bore, is guided from the second piston chamber 36 to the relief line 62 in the valve housing 60, fluid can also flow out of this fluid space to the outlet connection T. Via a through bore 44 formed centrally in the valve piston of the main control stage 38, ie along the radial axis R, the fluid pressure present at the main control stage 38 on the pump side can be transferred to the fluid space 34 between the main control stage 38 and the pilot stage 48. As soon as the load pressure rises again and exceeds the discharge pressure, the relief stage 54 and correspondingly the connection 60 are closed from the fluid space 34 to the discharge port T and the precursor stage 48 is opened by the increasing fluid pressure in the fluid space 34, as shown in FIG. 2d. In the subsequent step, the valve or switching position of FIG. 2 a, the blocking of the fluid path from the supply connection P to the discharge connection T, again occurs.

As particularly shown in FIG. 3, a further connection line 64 from the load connection LS to the fluid space 34, more precisely to the first subspace 35b leads. Via a further throttle 66, a pressure stage in the further connecting line 64 is specified. The valve 18 offers as another function, in other words option, an outflow of fluid, such as hydraulic oil, via the further connecting line 64. When connecting a hydraulic load 12a, 12b at the corresponding load port LS, the valve 18 controls the corresponding load pressure, which Relief level 54 can be reduced as needed.

Claims

P a n t a n s p r e c h e

Valve (1 8) for a Venti lanordnung (10) for pressure control in a hydraulic iksystem for supplying pressure to at least one hydraul ic consumer (12a, 12b) Fl uids out, comprising: a pilot stage (48) and a main control stage (38) for at least partially releasing or blocking a fluid path from a supply port (P) to a drain port (T) and

a relief stage (54) for pressure relief of a fluid space (34) arranged between the pilot control stage (48) and the main control stage (38), wherein the relief stage (54) controls the load connection (16) assigned to the at least one hydraulic consumer (12a, 1b). LS) compares the applied load pressure with the discharge pressure at the discharge connection (T) and releases the pressure relief when approaching or equalizing both pressures,

characterized in that the discharge stage (54) directly to the Lastanschl uss (LS) connectable and can be acted upon by load pressure.

Venti l according to claim 1, characterized in that the valve (18) has a valve housing (30) with at least one in this, preferably as a bore, ausgebi ldeten connecting line (61) from the load terminal (LS) to the discharge stage (54).

Valve according to claim 2, characterized in that at least one of the stages (38, 48, 54) comprises a valve piston, which in a respective piston chamber (32, 36, 52) in the Venti lgehäuse (30) slidably disposed and preferably biased. Valve according to one of the preceding claims, characterized in that the pump pressure via the main control stage (38), preferably via a through-hole formed in the corresponding valve piston (44), to the fluid space (34) can be transferred.

Valve according to one of the preceding claims, characterized in that the fluid space (34) in one of the pilot stage (48) associated first subspace (35b) and one of the main control stage (38) associated second subspace (35a) is divided, preferably between two subspaces (35a, 35b) a throttle or diaphragm (46) is arranged.

Valve according to one of the preceding claims, characterized in that the relief stage (54) controls a connection (60) from the fluid space (34), in particular from the second subspace (35a), to a discharge line (62) associated with the discharge port (T).

Valve according to one of the preceding claims, characterized in that the pilot control (48) - and / or the main control stage (38) can be acted upon by load pressure.

Valve according to one of the preceding claims, characterized in that a connecting line (60 ') from the pilot stage (48) to the discharge line (62) is provided.

Valve according to claim 8, characterized in that the connecting line (60 ') from the second piston chamber (36) to the discharge line (62) in the valve housing (60) is guided.

10. Valve according to one of the preceding claims, characterized in that a further connecting line (64) from the fluid space (34), in particular from the first subspace (35b), to the load port (LS) is provided, and in that in the further connecting line (64) preferably a further throttle (66) is arranged.

1 1 .Ventil according to one of the preceding claims, characterized in that the throttle or orifice (46) is arranged both before and after the departure to a preferably formed as an annular groove in the valve piston throttle body (58) or both before and behind the departure of a relief stage (54) serving as a valve piston is arranged.

12. Valve arrangement (10) for pressure control of a in a hydraulic system for pressure supply at least one hydraulic consumer (12 a, 12 b) guided fluid, comprising at least one valve (18) according to one of the preceding claims.