Control device
Patent Information
- Application Number
- EP2024702323
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-02-09
- Filing Date
- 2024-01-26
- Publication Date
- 2025-12-17
Smart Images
Figure EP2024051882_15082024_PF_FP
Abstract
Description
[0001] HYDAC MOBILHYDRAULIK GMBH
[0002] Industriestraße, 66280 Sulzbach / Saar, Germany
[0003] Control device
[0004] The invention relates to a control device for hydraulic consumers, in particular for controlling a controlled rundown of at least one hydraulic rotary drive, such as a vibration motor, after it has been shut down. The invention further relates to a valve, preferably for use in such a control device.
[0005] Hydraulic rotary drives are now braked or deliberately brought to a stop in a variety of ways. Such rotary drives are regularly used in conventional road rollers. To compact the subsoil, these road rollers have so-called vibrating drums containing a hydraulic motor with an eccentrically arranged mass. In technical terms, such devices are also referred to as a vibration motor. The vibration can be activated or deactivated by switching the pump supply, usually in the form of a conventional hydraulic pump, on and off. However, when the vibration is deactivated, the vibration motor continues to run for a certain time due to mass inertia. Since this overrun of the vibration motor is undesirable, the mass must be deliberately braked and the vibration motor brought to a controlled stop.
[0006] There are various hydraulic concepts for braking the motor, with Figure 1 of this patent showing an example of a concept that corresponds to the current state of the art. A 2 / 2-way seat valve is used which, when de-energised, serves to direct the oil supply from the hydraulic pump without pressure to the low-pressure side of the hydraulic supply circuit, usually in the form of a tank, or when energised, blocks the oil flow to the tank so that the oil flows overall to the vibration motor to drive it. Another 2 / 2-way seat valve behind the vibration motor serves to block the oil from flowing to the tank without power, or to direct the oil to the tank without power. In practice, this means that both seat valves must be permanently energised electrically during vibration operation, which is correspondingly energy-intensive.To switch off the vibration, both seat valves are then de-energized and the volume flow behind the vibration motor, which is generated by the inertia of the motor during run-down, can only be led to the tank via an orifice plate and a pressure relief valve.
[0007] For cost reasons, this well-known concept often uses a pressure relief valve with additional valves, such as two check valves, on the machine or road roller side. This means that the braking pressure is set via this machine-side pressure relief valve, and the run-down time can be determined via the orifice diameter. However, this well-known concept is highly temperature-dependent, and the braking process is difficult to predict. In particular, it results in a high braking torque at the beginning and a comparatively low braking torque at the end of the process.
[0008] Based on this state of the art, the invention is based on the object of improving the known solutions.
[0009] A control device having the features of patent claim 1 in its entirety solves this problem. Accordingly, it is provided that the control device according to the invention consists at least of the respective hydraulic consumer, a pressure compensator, and a pressure relief valve which acts on a control side of the pressure compensator, which releases a fluid flow present at its inlet connection in the direction of a low-pressure side, such as a tank, via an outlet connection as soon as a control pressure tapped via a control connection at the inlet connection, which acts on a further control side of the pressure compensator opposite the one control side, is greater than the control pressure prevailing on the one control side of the circulating pressure compensator.
[0010] In this way, the control device according to the invention can also be integrated into a single valve in a space-saving manner, which is also the subject of the invention according to independent patent claim 13. When the vibration drive is activated, with the oil flow to the tank blocked via a separate switching valve, a fluid pressure builds up on the inlet side of the vibration motor thanks to the pressure supply unit using a conventional hydraulic pump, which opens a main valve or motor outlet valve, thus enabling almost pressureless circulation to the tank. When fully open, the main valve has a very large opening cross-section, which leads to a very low circulation pressure (3 bar at 60 liters per minute). Since the pressure on the inlet side of the respective motor is always present during vibration operation, the main valve also remains constantly open.
[0011] Only when the vibration motor is deactivated, i.e., when the pressure supply device is switched off, does the pressure on the inlet side of the vibration motor decrease and the main or motor outlet valve closes. During this shutdown process, the pressure on the outlet side of the vibration motor increases until the pressure relief valve of the control device opens. As a result, the pressure in a control connection or control line, which carries the pressure on the inlet side of the pressure compensator, becomes greater than the pressure on the spring side of the pressure compensator, causing the pressure compensator to open toward the tank, thus connecting the outlet side of the vibration motor to the low-pressure or tank side of the device.
[0012] The combination of pressure compensator and pressure relief valve allows pressure control that maintains a constant pressure until the engine comes to a standstill. This pressure control generates a constant braking torque, which is freely adjustable within a range of 50 to 230 bar. The dynamics of the braking system can be adjusted using a preferred orifice combination with an orifice upstream and downstream of a branch to which a spring-side control line of the pressure compensator is connected. The pressure compensator is preferably designed as a circulation pressure compensator, meaning the flow rate can be kept constant regardless of pressure.
[0013] Both the pressure relief valve, the pressure compensator, and the main valve can be controlled purely hydraulically, ensuring reliable operation. Furthermore, compared to electrically operated switching valves, this hydraulic valve design saves energy during operation and is therefore energy-efficient.
[0014] The control unit can also be used for serial operation with multiple engines without mutual interference. This is achieved by a separate tank line, which is connected to the pressure relief valve on the output side. This allows, for example, a tandem roller with two vibratory drums (one at the front and one at the rear), thus two engines, to be controlled with a single control unit.
[0015] The brake pressure can be adjusted independently of the pressure relief valve, resulting in a material-saving braking process. Further advantageous embodiments of the control device and valve are the subject of the dependent claims.
[0016] In the following, the control device according to the invention and the valve are explained in more detail using an exemplary embodiment. In this case, the following are schematic and not to scale illustrations:
[0017] Figure 1 shows a control device according to the prior art in the form of a hydraulic circuit diagram;
[0018] Figure 2 shows a control device based on the hydraulic circuit diagram according to Figure 1, insofar as it differs from the solution in Figure 1 according to the invention; and
[0019] Figure 3 shows, in the form of a longitudinal section, a view of a valve which integrates the essential components of the control device according to Figure 2 in a valve housing.
[0020] The hydraulic circuit diagram in Figure 1 shows the essential components of a prior art control device. A hydraulic consumer in the form of a vibration motor 10 is connected to a hydraulic supply circuit 36. In the context of conventional road rollers for compacting the subsoil, the vibration motor 10 uses so-called vibration drums in which a hydraulic motor with an eccentrically arranged mass is located. The vibration can be activated or deactivated by switching a pressure supply device P on and off using a hydraulic pump 20 driven by a motor (not shown). When the vibration is deactivated, the vibration motor 10 continues to run due to mass inertia. To this extent, the vibration motor 10 is connected on its inlet side 22 via a hydraulic connecting line 11 to the fluid discharge side with the supply pressure of the hydraulic pump 20.On the outlet side 18 of the vibration motor 10, again as part of the hydraulic supply circuit 36, the motor 10 is connected to a valve device designated as a whole by 13. This valve device 13 has an electrically controllable 2 / 2-way seat valve 15, which, viewed in the direction of fluid flow, is arranged behind the vibration motor 10 and serves to block the return oil to tank T in the de-energized state shown, or to direct the oil to tank T without pressure in the other switching position when energized. Furthermore, another electrically actuated 2 / 2-way seat valve 17 is connected between the hydraulic connecting line 11 and a return line 19 to the tank, which leads to the outlet side of the first seat valve 15.
[0021] To switch off the vibration of the motor 10, both valves 15, 17 are not energized and thus assume their switching position shown in Figure 1. The volume flow on the outlet side 18 of the vibration motor 10, which is generated by the inertia of this motor, can then only be guided to the tank T via an orifice plate 21 and a main pressure relief valve 23. In addition to the orifice plate 21, two spring-loaded check valves 25 and 27 are used. The check valve 25 opens in the direction of the pressure relief valve 23 and the further check valve 27 is connected in a connecting line between the line 11 and the fluid-carrying connection between the check valve 25 and the pressure relief valve 23, the outlet of which opens in the direction of the tank T.The main pressure relief valve 23, in conjunction with the two check valves 25, 27, can also be part of a hydraulic working circuit (not shown) of a work machine, i.e., the road roller. In practice, this means that the brake pressure is specified via the main pressure relief valve 23, and the run-down time is determined by the orifice diameter of the orifice 21. The known solution in this regard is highly temperature-dependent, and the braking process proves to be inconsistent, with a high braking torque at the beginning and a low braking torque towards the end of the braking process. Based on this prior art, the control device according to the invention will now be explained in more detail using the circuit diagram shown in Figure 2. The statements made so far regarding the prior art also apply to the solution according to the invention, and one and the same components are accordingly provided with the same reference numerals.
[0022] The inventive solution of a control device for hydraulic consumers also serves in particular to control a controlled run-down of a hydraulic rotary drive, such as the vibration motor 10 shown of a road processing machine (not shown), such as a road roller. In addition to the respective hydraulic consumer, the control device has a pressure compensator DW and a pressure relief valve DB. The pressure relief valve DB acts on a control side c of the pressure compensator DW, which releases a fluid flow present at its inlet connection E towards a low-pressure side 3, such as a tank T, via an outlet connection A as soon as a control pressure tapped via a control connection 12 at the inlet connection E of the pressure compensator DW, which acts on another control side d of the pressure compensator DW opposite the one control side c, is greater than the control pressure prevailing on the one control side c.For this purpose, a branch 24 is provided in a fluid-carrying connection 54, which leads from the inlet port E of the pressure compensator DW to the inlet side of the pressure relief valve DB. From this branch, a control line 26 leads to one control side c of the pressure compensator DW. The pressure of an energy accumulator in the form of a compression spring Y also acts on the corresponding one control side c of the pressure compensator DW.
[0023] The vibration motor 10 is in turn connected to the pressure supply device P with the hydraulic pump 20 via a hydraulic connecting line 11. This forms the inlet side 22 for the vibration motor 10. On its outlet side 18, the vibration motor 10 is connected as part of the hydraulic supply circuit 36 to the return line 19, which preferably merges integrally into a connecting line 16, to which the inlet connection E of the pressure compensator DW is connected. For this purpose, the pressure compensator DW is connected to the connecting line 16 via a connection 2. Downstream of the branch as connection 2 of the pressure compensator DW to the connecting line 16, a main valve 14 is connected thereto, which is connected on its inlet side to the connecting line 16 and on its outlet side via a corresponding connecting line to the low-pressure side 3, which is designed as a tank connection and leads to tank T.Both the pressure compensator DW and the main valve 14 are shown in Figure 2 in their position blocking the fluid passage.
[0024] For hydraulic control of the main valve 14, one control side a of the latter is connected to the pressure supply device P, in which a control connection is connected to the pressure supply connection 1, which is located in the supply line 11. The other opposite control side b of the main valve 14, however, is fluidly connected via a control line 4 or control connection to the outlet of the pressure relief valve DB, wherein the respective outlet of the pressure relief valve DB is permanently connected via a suitable fluid-carrying tank line to the low-pressure side 3, which leads to the tank T. In this respect, the output pressure of the pressure relief valve DB acts via the control line 4 or the respective control line connection with an energy accumulator in the form of a compression spring X jointly on the other control side b of the main valve 14.
[0025] Furthermore, the output port A of the pressure compensator DW is connected downstream of the main valve 14 in the connecting line 16 toward the low-pressure side 3, viewed in the direction of fluid flow. On its opposite control sides e, f, the pressure relief valve DB is subjected to its inlet pressure on the one hand, and to its outlet pressure on the other, f, together with an energy accumulator in the form of a compression spring Z, the spring force of which is adjustable. The inlet side of the pressure relief valve DB is connected to the fluid-carrying connection 54, which leads to the inlet port E of the pressure compensator DW. On the output side, the pressure relief valve DB is connected, as already explained, to the control line 4 or the control line connection, which leads to the further control side b of the main valve 14, and, on the other hand, to the tank line 29.
[0026] As can be further seen from Figure 2, the pressure relief valve DB has an orifice B1 arranged in front of it on its inlet side and, viewed in the direction of fluid flow, a further orifice B2 is connected in front of the already mentioned branch 24 with the control line 26, namely in the fluid-carrying connection 54 between the inlet connection E of the pressure compensator DW and the branch 24.
[0027] In a particularly advantageous manner, a filter 30, preferably in the form of a slotted screen, can be connected between the further orifice B2 and the inlet connection E of the pressure compensator DW in the aforementioned fluid-carrying connection 54. Such slotted screen filter elements are common in valve technology, so they will not be discussed in detail here. As can also be seen from Figure 2, a shut-off valve 32 is connected downstream of the pressure supply device P in the fluid flow direction, as well as a further pressure relief valve 34 for securing the hydraulic supply circuit 36 for the respective hydraulic consumer in the form of the vibration motor 10. In the switching position of the valve 32 shown in Figure 2, this is in its open position and thus short-circuits the pressure supply device P in the direction of the low-pressure side 3, i.e.The vibration motor 10 is not supplied with fluid of a preset pressure by the hydraulic pump 20 and is therefore shut down. However, if the shut-off valve 32 moves into its further blocking position, the corresponding pressureless circulation is terminated and the vibration motor 10 is put into operation, with corresponding pressure fluid from source P being present on its inlet side 22.
[0028] If the hydraulic consumer in the form of the vibration motor 10 is shut down, for example because the hydraulic pump 20 is switched off, or the switching valve 32 reaches its short-circuit position shown in Figure 2, the vibration motor 10 runs down. In this way, however, the supply pressure in the hydraulic connecting line 11 to the vibration motor 10 is reduced upon switching off and thus the supply pressure at the pressure supply connection 1 is also eliminated, with the result that the main valve 14 or the motor outlet valve closes, which previously, in its open position, discharged the fluid return quantity on the outlet side 18 via the return line 19 and the connecting line 16 as well as the low-pressure side 3 to the storage tank T.
[0029] During the run-down process for the vibration motor 10, the pressure on the outlet side 18 continues to rise until the directly controlled pressure relief valve DB opens. As a result, the pressure in the control line 26, which leads to the control side c of the pressure compensator DW, drops. As a result, the fluid pressure in the control connection 12, which acts on the further control side d of the pressure compensator DW, becomes greater than the existing fluid pressure on the control side c of the pressure compensator DW, which leads to actuation of the pressure compensator DW, which then establishes a fluid connection between the inlet connection E and the outlet connection A, which leads to the low-pressure side 3. The pressure compensator DW is preferably designed as a circulation pressure compensator and is therefore a directly controlled, spring-loaded throttle or proportional valve in spool design and is closed in the normal position shown in Figure 2.The pressure compensator DW therefore has the task of regulating a flow-independent pressure setting at port E. The control pressure depends on the pressure at area c. Thus, a pressure limitation is achieved independent of the flow rate, thus keeping the braking torque constant when braking the vibration motor 10.
[0030] To control the pressure relief valve into one of its open positions, the control pressure required on the control side e is tapped at the point of the inlet connection E of the pressure compensator DW and is brought via the fluid-carrying connection 54, the filter 30, the orifice B2, via the branch 24 to the orifice B1 and further to the inlet side of the pressure relief valve DB.
[0031] The main or motor outlet valve 14 has its own pressure relief device, so that the brake pressure can be adjusted independently of the main pressure relief device. The adjusted brake pressure, i.e., the braking torque acting on the motor 10, can thus be kept constant throughout the entire braking process, which determines the deceleration time for the motor 10. The braking concept according to the invention is gentler on the vibration motor 10 because the brake pressure can be selected to be lower than the main pressure relief device. The separate tank line 29 shown in Figure 2, which leads on the output side to the low-pressure side 3 of the control device, also allows several motors (not shown) to be connected in series with the main or motor outlet valve 14 without them influencing each other.In this way, several vibration motors 10 (not shown) can be controlled with one control device, in particular with regard to the run-down of the respective motor 10. The essential valve components of the control device according to Figure 2, such as the pressure relief valve DB, pressure compensator DW, main valve 14 and the two orifices B1 and B2, can be combined in a single structural unit in a common valve housing 40 as shown in Figure 3. A filter 30 can also be integrated into the valve. Furthermore, all connections and control sides are designated in Figure 3 as in Figure 2. In this respect, both the main valve 14, the pressure compensator DW and the pressure relief valve DB are integrated in the valve housing 40.
[0032] The valve housing 40, which may consist of a type of valve block, has a main piston 44 of the main valve 14, which can be longitudinally displaced within a valve chamber 42 of the same, in which the pressure compensator DW and the pressure relief valve DB are integrated in series. The valve chamber 42 extends through the valve housing 40 along a common longitudinal axis 45, and the valve chamber 42 is closed off to the outside by a screw-in part 47, which is screwed into the valve housing 40 along a screw-in section 49. Furthermore, the interior of the valve housing 40 is sealed from the environment using a conventional ring seal 51 between the screw-in part 47 and an outer side of the valve housing 40.The length of the valve chamber 42 parallel to the longitudinal axis 45 is in any case dimensioned such that the main piston 44 can move from its lower position shown in Figure 3 into an upper position, in which the upper side of the main piston 44 can come into contact with an inner shoulder 53 on the inside of the screw-in part 47. In such an upper actuating position, the main piston 44 allows a fluid-carrying connection between the inlet port E and the outlet port A of the pressure compensator DW or between port 2 of the connecting line 16 and the low-pressure side 3, which in this respect also forms a tank port in the valve housing 40 leading to the tank T.For the possible travel movement of the main piston 44 in this regard, the valve housing 40 has a pressure supply connection 1 on the bottom side, which can be connected to the hydraulic connecting line 11 to the pressure supply device P and which opens into the valve chamber 42 at a point which is opposite the one free end face of the main piston 44 as the one control side a, wherein the main piston 44 is acted upon by an energy accumulator in the form of a compression spring X on a side facing away from the control side a as a further control side b. Furthermore, the valve housing 40 has the control line connection 4 at this point, which opens into the valve housing 40 as a radial passage in the valve housing 40 on the further control side b of the main piston 44.If the fluid pressure at the pressure supply connection 1 is accordingly greater than the combined counterpressure of compression spring X and fluid pressure at the control line connection 4, the main piston 44 of the main valve 14 lifts and, as already explained, connects the connection 2 with the connection 3 or the connection E with the connection A. In this respect, the main valve 14 then assumes its open position starting from its closed position shown in Figure 3.
[0033] The main piston 44 further has a piston chamber 46 in which a control piston 48 of the pressure compensator DW is guided for longitudinal movement. On one control side c, the control piston is acted upon by an energy accumulator in the form of a compression spring Y and, with its other control side d, is in fluid communication with the connection 2 for connecting the connecting line 16. When the control piston 48 moves against the action of the energy accumulator Y, the tank or return port 3 in the valve housing 40 comes into fluid communication via at least one throttle point DS in the main piston 44 with a circumferential groove 50 in the control piston 48, which in turn is in fluid communication with the connection 2 for the connecting line 16 via at least one inclined channel 55 in the main piston 44 during each movement of the control piston 48.It is understood that, as is usual in valve technology, several fluid connections or passage points can be present, for example in the form of throttle points DS or inclined channels 55. The respective inclined channel 55 is arranged in the direction of the common longitudinal axis 45 in the main piston 44, as shown in Figure 3, in any case below the throttle point DS.
[0034] As can be further seen from Figure 3, the lower end of the main piston 44 is closed off with a closure plug 57 which, in the valve position shown in Figure 3, adjoins the mouth of the pressure supply connection 1 in the valve housing 40 at a predeterminable axial distance parallel to the longitudinal axis 45.In the area of the upper end of the closure plug 57, the control connection 12, which in turn can consist of a plurality of transverse bores in the main piston 44, opens onto the inside of the valve chamber 42. In the position shown, the control piston 48 of the pressure compensator DW essentially covers the corresponding control connection 12, with the proviso that hump-like projections are arranged on the underside of the control piston 48, which can be supported on the upper side of the closure plug 57 and define fluid passages between them, so that a fluid pressure applied via the inlet connection E or connection 2 can act on the lower free end face of the control piston 48 of the pressure compensator DW. For a uniform fluid pressure distribution, the connections E, A and 2, 3 open into annular spaces in the valve housing 40, which uniformly surround the valve piston 44.Furthermore, the respective inclined channel 55 opens with its lower free connection side into an annular projection 59 in the valve housing 40, which merges into the underlying valve annular chamber of larger diameter, into which the connections E, 2 open. On the lower free end face, which corresponds to the further control side d of the pressure compensator DW, which in this respect borders on the connection 2 for the connecting line 16, a central recess 52 is made in the control piston 48 for receiving a filter 30 in the form of a slotted sieve, to which the orifice B2 is connected at the top, which in this respect opens into the spring chamber 56 with the compression spring Y in a fluid-conducting manner. In this way, a fluid-conducting connection 54 is permanently established in the control piston 48 between the connection 2 and the spring chamber 56 with the compression spring Y of the pressure compensator DW.
[0035] As viewed in the direction of Figure 3, above the pressure compensator DW in the main piston 44, a stepped control piston 58 of the pressure relief valve DB is guided concentrically to the longitudinal axis 45 and is longitudinally movable. On one control side f, said stepped control piston is acted upon by a compression spring Z as an energy store. Furthermore, the control piston 58 of the pressure relief valve DB projects along its underside with a valve tip 60, forming the orifice B1, into a fluid-carrying connection 62 between the spring chamber 56 of the pressure compensator DW and a piston chamber 64 of the control piston 58 of the pressure relief valve DB. The control side e of the pressure relief valve DB is realized where the valve tip 60 comes into contact with the associated internal channel on the inside of the main piston 44, which leads in the direction of the orifice B1.
[0036] The spring force of the compression spring Z of the pressure relief valve DB is adjustable by means of an adjustment drive 66, wherein an actuating part 63 which is longitudinally movable in the main piston 44 can be moved by means of a screw-in body 61 which can be screwed into the upper free end of the main piston 44, wherein the upper free end of the compression spring Z is supported on the actuating part 63, the lower, other free end of which is in contact with a valve plate 65 of the pressure relief valve DB. If the screw-in body is screwed further into the main piston 44, the actuating part 63 is moved downwards, which leads to an increase in the preload for the compression spring Z, which then exerts an increased spring force on the valve plate 65 of the control piston 58 of the pressure relief valve DB. While the compression spring Z is guided inside the main piston 44, the compression spring X is arranged concentrically to the compression spring Z and guided on the outer circumference of the main piston 44.The lower end of the compression spring X rests on a projection that is part of the further control side b of the main valve 14. The other upper end of the compression spring X rests on an inner shoulder of the screw-in part 47, which is delimited on the outer circumference by the screw-in section 49. To ensure a hermetic seal of the valve housing 40 to the outside, the screw-in part 47 can be provided with a sealing plug 67 on its upper side.
[0037] Furthermore, a connection point 68, again in the form of at least one transverse bore, is introduced into the main piston 44 of the main valve 14, which fluidically connects a spring chamber 70 of the pressure relief valve DB with the compression spring Z to the control line connection 4 in the valve housing 40. The contact surface of the compression spring Z on the valve plate 65 thus forms the further control side f of the pressure relief valve DB, which is fluidically connected via the connection point 68 in every travel position of the main piston 44 to the control line connection 4, which in turn opens into an annular space with a wider diameter in the valve housing 40. For improved longitudinal guidance of the valve plate 65, the latter has a guide pin 69 on its upper side, which sits loosely on the upper side of the control piston 58 or on the valve plate 65 and is guided for longitudinal movement in a longitudinal recess in the actuating part 63.All essential components of the control device according to Figure 2 are grouped in a coaxial arrangement along the longitudinal axis 45 in the valve housing 40, and it is surprising to a person of ordinary skill in the art in the field of such control devices that they can combine a plurality of individual valves according to the circuit diagram of Figure 2 into a valve construction according to Figure 3. This has no equivalent in the prior art.
Claims
Patent claims 1 . Control device for hydraulic consumers, in particular for controlling a controlled run-down of at least one hydraulic rotary drive, such as a vibration motor (10), after the latter has been switched off, at least comprising the respective hydraulic consumer, a pressure compensator (DW), and a pressure relief valve (DB) acting on a control side (c) of the pressure compensator (DW), which releases a fluid flow present at its inlet connection (E) in the direction of a low-pressure side (3), such as a tank (T), via an outlet connection (A), as soon as a control pressure tapped via a control connection (12) at the inlet connection (E), which acts on a further control side (d) of the pressure compensator (DW) opposite the one control side (c), is greater than the control pressure prevailing on the one control side (c).
2. Control device according to claim 1, characterized in that the pressure relief valve (DB) together with an energy storage device, such as a compression spring (Y), on which a control side (c) of the pressure compensator (DW) prevails.
3. Control device according to claim 1 or 2, characterized in that a hydraulically controllable main valve (14) is connected in a connecting line (16) to which the pressure compensator (DW) is connected with its input connection (E) and that with actuation of the main valve (14) the connecting line (16) is connected to the low-pressure side (3).
4. Control device according to one of the preceding claims, characterized in that the connecting line (16) is directed to the outlet side (18) of the respective hydraulic consumer, which is supplied with fluid of predeterminable pressure on its inlet side (22) by a pressure supply device (P), such as a hydraulic pump (20).
5. Control device according to one of the preceding claims, characterized in that for hydraulic control of the main valve (14), one control side (a) of which is connected to the pressure supply device (P) and the other control side (b) of which can be acted upon via a control line (4) with the output pressure of the pressure relief valve (DB), preferably together with an energy store, such as a compression spring (X).
6. Control device according to one of the preceding claims, characterized in that the output connection (A) of the pressure compensator (DW) is located behind the main valve in the fluid flow direction (14) is connected to the connecting line (16) in the direction of the low pressure side (3).
7. Control device according to one of the preceding claims, characterized in that the pressure relief valve (DB) is acted upon on its opposite control sides (e, f) on the one hand with its inlet pressure and on the other hand with its outlet pressure together with an energy storage device, such as a compression spring (Z), the spring force of which is preferably adjustable.
8. Control device according to one of the preceding claims, characterized in that the pressure relief valve (DB) has an orifice (B1) on its inlet side.
9. Control device according to one of the preceding claims, characterized in that, seen in the fluid flow direction, upstream of a branch (24) of a control line (26) to the one control side (c) of the Pressure compensator (DW) a further orifice plate (B2) is connected in a connection (28) to the input connection (E) of the pressure compensator (DW).
10. Control device according to one of the preceding claims, characterized in that a filter is connected between the further orifice (B2) and the input connection (E) of the pressure compensator (DW). 1 1. Control device according to one of the preceding claims, characterized in that, viewed in the direction of fluid flow, a shut-off valve (32) is connected downstream of the pressure supply device (P) and preferably a further pressure relief valve (34) for protecting a hydraulic supply circuit (36) for the respective hydraulic consumer.
12. Control device according to one of the preceding claims, characterized in that the pressure compensator (DW) is a circulating pressure compensator.
13. Valve, in particular for use in a control device according to one of the preceding claims, characterized in that a main valve (14), a pressure compensator (DW) and a pressure relief valve (DB) are integrated in a valve housing (40).
14. Valve according to claim 13, characterized in that the valve housing (40) accommodates a main piston (44) of the main valve (14) which is longitudinally displaceable in a valve chamber (42) thereof, in that the pressure compensator (DW) and the pressure relief valve (DB) are integrated in a successive sequence.
15. Valve according to claim 13 or 14, characterized in that the valve housing (40) has a pressure supply connection (1 ) which opens into the valve chamber (42) at a point which corresponds to the one free end face of the main piston (44) as the one control side (a), that the main piston (44) is acted upon by an energy store, in particular a compression spring (X), on a side facing away from the control side (a) as a further control side (b), and that the valve housing (40) has a control line connection (4) which opens into the valve housing (40) on the further control side (b) of the main piston (44).
16. Valve according to one of claims 13 to 15, characterized in that the main piston (44) has a piston chamber (46) in which a control piston (48) of the pressure compensator (DW) is guided for longitudinal movement, which control piston (48) is acted upon on its one control side (c) by an energy accumulator, preferably in the form of a compression spring (Y), and which is in fluid communication with its other control side (d) with a connection (2) for connecting a connecting line (16), and in that during a movement of the control piston (48) against the action of the energy accumulator (Y), a tank or return connection (3) in the valve housing (40) can be fluid-conductingly connected via at least one throttle point (DS) in the main piston (44) to a groove (50) in the control piston (48), which groove is in fluid communication with the connection (2) for the connecting line (16) during each movement of the control piston (48). 1 7. Valve according to one of claims 13 to 16, characterized in that on the free end face of the control piston (48) as the further control side (d) of the pressure compensator (DW), which adjoins the connection (2) for the connecting line (16), a recess (52) is introduced for receiving an orifice (B2) and preferably additionally for receiving a filter (30), such as a slotted sieve element, and that in the control piston (48) a fluid-carrying connection (54) between the connection (2) for the connecting line (16) and a spring chamber (56) with the compression spring (Y) of the pressure compensator (DW).
18. Valve according to one of claims 13 to 17, characterized in that a control piston (58) of the pressure relief valve (DB) is guided in the main piston (44) so as to be longitudinally displaceable, which control piston is acted upon on one of its control sides (f) by a compression spring (Z) as an energy store and in that the control piston (58) of the pressure relief valve (DB) engages with a valve tip (60) in a fluid-carrying connection (62) between the spring chamber (56) of the pressure compensator (DW) and a piston chamber (64) of the control piston (58) of the pressure relief valve (DB), in which an orifice (B1) is arranged.
19. Valve according to one of claims 13 to 18, characterized in that the spring force of the compression spring (Z) of the pressure relief valve (DB) is adjustable by means of an adjusting drive (66).
20. Valve according to one of claims 13 to 19, characterized in that a connection point (68) is introduced into the main piston (44) of the main valve (14), which connects a spring chamber (70) of the pressure relief valve (DB) with the compression spring (Z) to the control line connection (4) in the valve housing (40).