EP2488764A1

EP2488764A1 - Valve assembly

Info

Publication number: EP2488764A1
Application number: EP10768695A
Authority: EP
Inventors: Philipp Hilzendegen; Peter Bruck; Hermann Albert
Original assignee: Hydac Fluidtechnik GmbH
Current assignee: Hydac Fluidtechnik GmbH
Priority date: 2009-10-16
Filing date: 2010-10-14
Publication date: 2012-08-22
Anticipated expiration: 2030-10-14
Also published as: DE102009049548A1; US20120199765A1; WO2011045063A1; EP2488764B1; US8973609B2

Abstract

The invention relates to a valve assembly for regulating the pressure of a pressure medium (2) of a pressure medium pump (3) to at least one first consumer (4), comprising a pilot-controlled pressure control valve (5), a main piston (6) acted on by the pressure medium (2), and a pilot piston (7), wherein a pressure chamber (8) between a piston back side (9) of the main piston (6) and the pilot piston (7) can be relieved, is characterized in that a relief valve (10) is connected in a fluid-conducting manner to the pressure chamber (8), which valve opens when pressure medium pressure is present at the load sensor (LS), which represents an out-of-operation mode of the consumer (4), and recirculates pressure medium (2) having a low pressure to a pressure medium reservoir (11) or to the pressure medium pump (3), and the relief valve (10) closes, when the pressure medium pressure at the load sensor (LS) represents an in-operation mode of the consumer (4).

Description

valve assembly

The invention relates to a valve arrangement for pressure control of a pressure medium from a pressure medium pump to at least a first consumer, with a pilot operated pressure control valve, acted upon by the pressure medium main piston and a pilot piston, wherein a pressure space between a piston rear side of the main piston and the pilot piston can be relieved.

If you want to keep the speed of a hydraulic cylinder or the speed of a hydraulic motor regardless of the prevailing at a flow valve pressure difference and regardless of temperature or viscosity of a pressure medium used for this purpose and further independent of the load to be moved, so-called. Pressure control valves are used regularly. In this case, the not controlled by the pressure control valve pressure medium flow is discharged under relatively large power and pressure losses for a pressure medium pump via a pressure relief valve.

To minimize such power losses, it is known, working as a pressure compensator pressure control valve with a load on a

Consumers, such as a hydraulic cylinder to link such that the so-called. LS (load-sensing) pressure from the load tap of the consumer is present in a pressure chamber after the pilot piston. In particular, the pump pressure can be essentially compared with the spring preload on the control piston plus the pressure at the load (LS) and at a decommissioning division of the consumer dissipate the pressure medium with less energy loss than when used with a pressure relief valve. However, the power loss of such known pilot-operated pressure control valves with pressure compensator function can not be completely avoided.

For example, DE 103 22 585 A1 describes a valve arrangement for regulating the pressure of a pressure medium from a pressure medium pump to a consumer, wherein a main control valve can be hydraulically actuated by a pilot valve. Specifically, the document describes a valve modular system with at least one valve housing having at its opposite ends both inside and outside the circumference and inside the housing standardized nominal sizes for attaching further valve components. Such valve components may be a valve piston, an energy store, a pilot valve and at least one fluid port for defining the valve assembly formed in the manner of a Einschraubpatrone in an environment.

DE 10 2005 059 240 A1 shows and describes a hydrostatic drive system with a variable-stroke pressure medium pump which supplies a consumer with pressure medium via control valves. In the idling mode of the hydrostatic drive system in which the control valves are not activated, serving as a recirculation pressure compensator is set to a minimum control pressure difference. The pressure medium pump is set to a minimum delivery volume, wherein the pressure medium flow coming from the pressure medium pump via the pressure compensator flows with low power losses to a pressure medium container.

The hydraulic drive system builds complex and has no minimized pressure losses. DE 689 08 31 7 12 describes a pressure control valve whose main valve is pilot-controlled by a pilot valve which is arranged in a common valve housing. Based on this prior art, the present invention seeks to provide a valve arrangement for pressure control of a pressure medium, which allows a further minimization of the pressure loss when no consumer is connected. This object is achieved with a valve arrangement having the features of patent claim 1 in its entirety.

According to the invention a valve arrangement for pressure control of a pressure medium is provided by a pressure medium pump to a consumer, which provides a pilot-operated pressure control valve with a spring-loaded main piston. A pilot piston, which controls a valve seat for a fluid-carrying connection to a back pressure chamber of the main piston, is part of the pressure control valve. The piston-back pressure chamber of the main piston is pressurized by the pump pressure via a first throttle in the main piston, so that the recirculation pressure compensator thus formed allows a comparison between the pump pressure and the pressure at the load tap plus the spring preloads of the main control piston and the pilot piston. A by the respective set spring voltages higher pressure of the pressure medium pump than the pressure at the load tap of the consumer turns it. According to the invention it is further provided to arrange a relief valve for the space between the main piston and the pilot piston.

The relief valve is formed as a poppet or poppet valve, wherein a valve element of the relief valve is arranged such that at no pressure of the load tap, which corresponds to a de-operation division of the consumer, a pressure medium flow from the space between main piston and pilot piston to a pressure medium tank, tank or in the LS-line allows. When operating in non-pressurized circulation, the relief valve is open and the main valve can also be opened. The pilot valve is closed.

However, if the pressure at the load tap rises above a set value at the relief valve, then the relief valve closes the bypass formed in this way and allows a load-sensing-controlled function of the pressure regulating valve according to the known prior art. Main and pilot valve are in control position.

The relief valve according to the invention thus enables a substantial reduction of the pressure losses of the valve assembly in comparison to the known circuits of circulation pressure compensators.

In a displacement position of the valve element of the relief valve pressure medium from Druckmittelanschi uss of the pressure control valve coming to be discharged via a first throttle and the relief valve to the pressure fluid reservoir. Pressure medium can be guided to the relief valve via a longitudinal channel between the pressure chamber of the main piston and a further second pressure chamber, which is durchfahrbar by the pilot piston. In a particularly preferred embodiment of the valve arrangement, the longitudinal channel has a further, second throttle. The second throttle divides the longitudinal channel into two channel sections. A first channel section is in this case the pressure chamber of the

Assigned to the main piston. A second channel portion of the longitudinal channel is fluidly associated with the second pressure chamber, which is durchfahrbar by the pilot piston. The second throttle can serve as an attenuator for the relief valve. In a particularly preferred embodiment, the relief valve is arranged in the housing of the pressure control valve. The valve element of the relief valve is axially movable in one Longitudinal bore out. Via at least one annular recess in the housing of the pressure regulating valve or in the valve element of the relief valve, a fluid-conducting connection to one or the other channel section of the longitudinal channel can be produced in at least one displacement position of the valve element.

The valve element of the relief valve is preferably biased by means of an energy accumulator (compression spring) in the direction of the second pressure chamber, which is passable by the pilot piston. The pilot piston of the pilot valve can in this case control a fluid-conducting connection between a load tap LS and a free, the energy storage opposite side of the valve element of the relief valve. In part-load or full load operation of a regulated by means of the pressure control valve load and a corresponding LS-pressure, the valve element of the relief valve blocks a fluid-conducting connection between the pressure chamber of the main piston and the pressure fluid reservoir. On the other hand, in the case of an out of order division of a consumer and an LS pressure going to zero, the valve element of the relief valve is brought under the action of the energy storage in a movement position in which a direct fluid-conducting connection between the pressure chamber of the main piston is opened via the relief valve to the pressure medium container. Pressure fluid flows through the annular recess on the relief valve. In a valve solution in which the annular recess in the housing or in the valve element opens into the second channel section of the longitudinal channel between the pressure control valve and the pilot valve, the annular recess is connected to the second pressure chamber of the pilot piston or of the pressure chamber through which the pilot piston can carry fluid. Instead of an integrated design of pilot valve, main valve and relief valve and a decentralized individual arrangement of said valves to a total valve arrangement according to the invention is possible. The relief valve can be arranged in parallel arrangement to the pressure regulating valve between a pressure medium pump and the pressure medium container. The relief valve may be directly piloted, but it may also be advantageous to form the relief valve as an electrically operable 2/2-way valve, which is controlled for example by a pressure signals of a pressure sensor processing control and / or regulating device.

The invention with reference to embodiments shown in the drawings will be explained in detail. It shows: NEN schematic, not to scale longitudinal section through a valve assembly according to the invention with a relief valve in the open position in a pressure control valve with connection to a constant flow pressure medium pump and two consumers;

Fig.l b is a detail I in Figure 1 a;

Fig.l c is a schematic, not to scale longitudinal section through a valve assembly according to the invention with a relief valve in the control position of the main valve and the pilot valve with closed switching position of the relief valve;

Fig.ld a detail I in Fig.lc; a further embodiment of a pressure regulating valve according to the invention with a relief valve;

Fig. T f is a detail I in Fig.1 e;

2 shows a hydraulic circuit diagram for a further embodiment of the valve arrangement according to the invention;

3 shows a further hydraulic circuit diagram of a further embodiment of the valve arrangement with a connection of a relief valve after a first throttle and before a second throttle between the main control valve and the pilot valve of the pressure regulating valve; 4 and 5 further embodiments in the manner of a hydraulic

Circuit diagram related to the valve arrangement according to the invention.

1 a shows a closed, hydraulic circuit of a valve arrangement 1, with a constant-pressure medium pump 3 for supplying a consumer 4 with pressure medium 2. The consumer 4 is shown as a hydraulic motor with two possible directions of flow. The consumer 4 is driven by an electrically operated 4/3-way valve 19. By means of a change valve 18 which is applied to the load 4 pressure is reported in an LS line. This valve control is preceded by a 2/2-way valve 20 with pressure limiting function in the open switching position. In the embodiment of a hydraulic system shown in Fig.la two consumers 4 are connected in parallel with each identical valve control technology, which can be supplied by the constant-pressure medium pump 3. At this point, the operation of the valve control block 4 thus formed for the consumer 4 will not be discussed in more detail, since this is sufficiently known from the prior art. The hydraulic system provides a constant-pressure fluid pump 3 as a cheaper alternative to a variable, but requires control of their flow to operate the consumer 4 with a predetermined speed can. It requires a flow control valve, in particular a pressure control valve, which overall represents a simpler overall solution, which incidentally is more cost-effective than that which results when using a variable displacement. As shown in FIG. 1 a further shows, is to represent a load-independent constant speed of both consumers 4, a single pressure control valve 5 with a feedforward control, taking into account a load tap LS for both consumers 4 is provided. In this case, the load tap LS is in each case initially separated at each changeover valve 18 for each consumer 4. In each of the control lines to be designated as "load-sensing" control lines 21, a check valve 22 is switched into the hydraulic circuit before each changeover valve 18. Each check valve 22 In this case, the same set opening pressure and opens in the direction of the pressure regulating valve 5, in particular in the direction of its load-sensing connection LS. By this way the parallel connection of the control lines 21 with respect to the pressure control valve 5 is a comparison of the two load pressures to the consumers 4, taking into account the higher of the two possible load pressures In the pressure control valve 5, which is also shown in Fig.lc and in another embodiment in Fig.le shown is a valve assembly 1 with an additional relief valve 10th provided that is an integral part of the inventive solution.

The operation of the pressure control valve 5 corresponds to a pilot-operated rotary pressure balance 1 7, wherein in a common housing 12 three different functionally different valves are summarized. The basic functional connection of the valves is also shown in Figure 2 in a schematic circuit diagram in dissolved construction. These are in detail:

a main valve 23 having a main piston 6 and a biasing compression spring 24,

a pilot valve 25 with a pilot piston 7 and this biasing compression spring 26, and

a relief valve 10 formed as a miniature valve with a valve element 27 or relief valve piston and an energy store 28 holding it in the direction of a closed position.

In the cartridge-like, designed as Einschraubventil housing 12 of the pressure control valve 5, the main piston 6 in a bore 29 of the housing 12 is longitudinally displaceably guided in a main valve control section. The main piston 6 controls a centrally and axially guided into the housing 12 pressure medium inlet 30. In this case, a possible fluid-conducting connection to a radially out of the housing 12 Druckmittelan- circuit 31, which optionally consists of several radially arranged passage holes in the housing 12 and is connected to a pressure medium container 1 1, from which the pressure medium pump 3 pressure means for the hydraulic circuit is removed, produced.

The main valve 23 is designed in terms of its effective cross-section such that the entire volume flow of pressure medium from the 2 _i con- stant pressure pump 3 are directed to the pressure fluid reservoir 1 1 can. In the main piston 6, a first throttle 13 is arranged in the form of a through hole or bore with a definable diameter in its piston crown. This makes it possible that the pressure on the pump side is reported to the piston rear side 9 of the main piston 6. The main piston 6 is formed substantially as a cylindrical sleeve with a piston crown as a fluid separation, so that on the piston rear side 9 a cup-shaped pressure chamber 8 is formed, which serves for centering and receiving the compression spring 24 and the further pressure medium 2 can accommodate. In the axial direction of the pressure control valve 5, a bore 32 with a diameter of about 1/5 of the guided in the valve housing 12 main piston 6 is centrally mounted. The bore 32 has a second, second throttle 14 approximately at its axial center. Through the second throttle 14, the bore 32 is divided into a first channel section 32 'and a second channel section 32'. As also shown in FIGS. 1 b, d and f in respective details I, the first channel section 32 'is the one Pressure chamber 8 of the main valve 23 associated, the second channel section 32 ", however, is a second pressure chamber 35, which is durchfahrbar by the pilot piston 7 assigned. The pilot piston 7 in turn is formed as a flat disc with a centering aid 33 in the form of a truncated cone for a compression spring 26. The pilot piston 7 is acted upon by the force of the compression spring 26, which is supported with radial play in a bore 34 for the pilot piston 7 and the compression spring 26. The piston front side, second pressure chamber 35 is the same pressure chamber as the space 34, in which the compression spring 26 is introduced. So far there is no need for poetry. In the space 34 of the pilot valve piston 7 opens a, the housing wall of the housing 12 traversing hole 36 for the load tap LS consumer 4. The flow pressure of the pilot valve 25 results from the pressure defined by the pressure spring 26 plus the pressure at the load tap LS , Is the pump pressure greater than the pressure in LS and that of the pressure set the 26 of the pilot piston 7 and set by the spring 24 of the main piston pressure, so the pilot valve 25 opens and due to the main valve 23 and pressure medium can flow through the main valve 23 to the pressure medium container 1 1.

As the Fig.la to 1 f further show the pressure control valve 5 is additionally the relief valve 10 with a valve element 27 which is arranged in an axial region A in a longitudinal bore 40 movable between the pilot valve 25 and the main valve 23, in particular in parallel. The relief valve 10, which is shown in its integration into the housing 12 in an enlarged view in Figures 1 b, d and f, is radially laterally offset from a longitudinal axis 37 of the valve housing 12 and has an approximately same diameter as through The bore 32 formed load bore above and below the second throttle 14. A valve element 27 or a relief valve piston is shown abutting an upper stop, to which it terminates approximately flush with the end of the bore 34 for receiving the pilot piston 7. The positions of the relief valve piston shown in FIGS. 1a, 1b, 1e and 1f correspond to an open switching position of the relief valve 10. The relief valve piston is of a smaller energy storage 28, a compression spring, for example, a flow pressure of 0.5 bar, spring-loaded at its opposite end in the sense of an open position. In axial proximity to the pressure spring-side end of the relief valve piston, an annular recess 41, which is formed as an annular groove 38 in the periphery of the relief valve piston, is provided. In the embodiment shown in Fig.la, 1 b, 1 c and 1 d of the valve assembly 1 communicates the annular recess 41 each with the first channel portion 32 'of the bore 32. Is now on the Lastabgriffseite the pilot valve piston 7 and thus on the the compression spring 28 side facing away no Pressure on the load tap LS more, the relief valve piston assumes the position shown in Fig.la, 1 e and I f. The annular groove 38 thereby comes into coincidence with an associated opening 39 of the bore 34. Pressure medium can thus be from the pressure chamber 8 on the piston rear side 9 of the main piston 6 via the bore 32, the opening 39 and a connection line 42 communicating with the opening Housing 12 via the annular groove 38 to an outlet 1 5 of the relief valve 10 are performed. The pressure medium 2 then flows without pressure in this respect without the pressure medium pump 3 having to pump against the set pressure at the pilot control valve 25. By this constructive measure results in a considerable energy saving in the operation of equipped with a valve assembly 1 according to the invention hydraulic system with de-operation division of consumers 4. If the pressure on the load tap LS at a restart of the consumer 4, then the relief valve piston moves against the spring force of his Compression spring 26 in the position shown in Figure 1 c and 1 d, in which there is no overlap of the opening 39, the connecting line 42 with the annular groove 38. The pressure control valve 5 is then in its above-described control operation without being influenced by the relief valve 10th

FIGS. 1e and 1f in turn show in a schematic, not to scale longitudinal section a comparison with the Fig.la, 1 b, 1 c and 1 d modified variant of a valve assembly 1, in turn, combined in a housing 12 of the pressure control valve 5 with an extent offset 39th in that it is ensured that the outflow of the pressure medium 2 from the pressure chamber 8 takes place in the LS line. In this exemplary embodiment, the opening 39 is assigned to the second channel section 32 ", so that the second throttle 14 has a damping effect on the entire operation of the valve arrangement 1, in particular on the main piston 6. 2 and 3 show the interconnection of the three valves 10, 23 and 25 with a pressure medium tap according to the solutions according to FIGS. 1 a and 1 c. In this way, the valve arrangement 1 according to the invention can be realized even in a dissolved valve design.

FIGS. 4 and 5 again show a circuit diagram comparable to that of FIG. 3, wherein the relief valve 10 can be formed as a 2/2-way valve 16, but designed for the entire volume flow of the pressure medium pump 3.

The relief valve can be integrated as a rule small constructive valve in an existing pressure control valve. It is advantageous in this respect to arrange the relief valve axially between the pilot valve and the main valve, wherein a valve piston of the relief valve can be inserted from the pilot control valve side into a housing of the pressure regulating valve. It can thereby also make the main bore for the relief valve from the same valve side as a throttle between the pressure chamber and the pilot valve.

Claims

Patent claims

1 . Valve arrangement for pressure control of a pressure medium (2) from a pressure medium pump (3) to at least a first consumer (4), with a pilot operated pressure control valve (5), with one of the pressure means (2) acted upon main piston (6) and a pilot piston (7 ), wherein a pressure chamber (8) between a piston rear side (9) of the main piston (6) and the pilot piston (7) can be relieved, characterized in that a relief valve (10) fluidly connected to the pressure chamber (8), which at a pressure medium pressure at the Lastabgriff (LS) opens, which depicts a shutdown division of the consumer (4) and pressure medium (2) at low pressure in a pressure medium tank (1 1) or to the pressure medium pump (3) and that the relief valve (10) closes when the pressure average pressure at the load tap (LS) represents a commissioning of the consumer (4).

2. Valve arrangement according to claim 1, characterized in that

Pressure medium from the pressure medium connection (30) of the valve assembly (1) coming, via a first throttle (13) and via the relief valve

(10), in one of its displacement position to the pressure medium container

(1 1) is dischargeable.

3. Valve arrangement according to one of the preceding claims, characterized in that in a longitudinal channel (32) between the pressure chamber (8) of the main piston (6) and a further second pressure chamber (35) which is traversable by the pilot piston (7), another , second throttle (14) is present.

4. Valve arrangement according to one of the preceding claims, characterized in that the second throttle (14) the longitudinal channel (32) in subdivides two channel sections, of which the one, first channel section (32 ') is associated with the pressure chamber (8) of the main piston (6) and the other, second channel section (32 ") with the second pressure chamber (35), which is separated from the pilot piston (7). is passable, is assigned.

Valve arrangement according to one of the preceding claims, characterized in that the valve element (27) of the relief valve (10) in a longitudinal bore (40) of the housing (12) of the pressure control valve (5) is guided, wherein at least one annular recess (41) in the housing (12) and / or in the valve element (27) a fluid-conducting connection to the one or the other channel portion (32 ', 32 ") in at least one Verfahrstellung the valve element (27) can be produced.

Valve arrangement according to one of the preceding claims, characterized in that the valve element (27) under the influence of an energy accumulator (compression spring) (28) in the direction of the second pressure chamber (35) is biased with the pilot piston (7) and that the pilot piston (7) a fluid-conducting connection between a load tap (LS) and a free the energy storage (28) opposite side of the valve element (27) controls.

Valve arrangement according to one of the preceding claims, characterized in that the valve element (27) blocks the fluid-carrying connection between the pressure chamber (8) of the main piston (6) and the pressure medium container (1 1) at least at full load with the LS pressure and otherwise releases ,

Valve arrangement according to one of the preceding claims, characterized in that in a valve solution, in which the annular recess (41) in the housing (12) or in the valve element (27) in the second channel portion (32 ") of the longitudinal channel (32) opens, via a connects Duct line (42), the annular recess (41) to the second pressure (35) of the pilot piston (7) is fluidly connected.