DE10035575A1 - Hydraulic control arrangement for supplying pressure medium to preferably several hydraulic consumers - Google Patents

Abstract

The invention is based on a hydraulic control arrangement, which serves to supply pressure medium to preferably several hydraulic consumers and which has a demand-flow-controlled (load-sensing-regulated) variable displacement pump, the setting of which can be changed as a hydraulic consumer, depending on the highest load pressure of the actuated hydraulic consumers annular first pressure chamber and a circular cylindrical second pressure chamber possessing a differential cylinder, a proportionally adjustable directional valve with which the pressure medium paths between an inlet line leading from the variable displacement pump, an outlet line leading to a tank and a first consumer line leading to the first pressure chamber of the differential cylinder and one to the second pressure chamber of the Differential cylinder leading second consumer line are controllable, a bias valve for generating a bias pressure in a section upstream of the bias valve d he drain line and a check valve arranged between this section of the drain line and the second consumer line and opening towards it. DOLLAR A In such a hydraulic control arrangement, the existing preload valve and the check valve serve the purpose of avoiding cavitation in the second pressure chamber of the differential cylinder. This risk is to be reduced further. DOLLAR A This is achieved in that valve means are provided, via the pressure medium from ...

Description

The invention relates to a hydraulic control arrangement, with which preferably several hydraulic consumers are supplied with pressure medium and which the Features from the preamble of claim 1.

In a hydraulic control arrangement according to the preamble of the patent Proposition 1 is one after the load-sensing Principle in which a variable pump depending on the highest load pressure actuated hydraulic consumer is set so that the pump Pendulum pressure around a certain, preferably in the range between 10 bar and 25 bar pressure difference Δp lies above the highest load pressure. The hydrauli For consumers, the pressure medium flows through adjustable, usually through Control orifices on the control pistons of the directional control valves, the between a feed line from the variable displacement pump and the hy drastic consumers are arranged. Assigned by the directional valves Individual pressure compensators is achieved that sufficient by the variable pump delivered pressure medium quantity independent of the load pressures of the hydraulic Consumers via the metering orifices a certain one, smaller than Δp Pressure difference exists, so that the flowing to a hydraulic consumer Pressure medium quantity only from the opening cross section of the respective metering orifice depends. If a metering orifice is opened further, more pressure medium must be added flow over them to produce the determined pressure difference. The variable displacement pump is adjusted so that it delivers the required amount of pressure medium. you therefore speaks of a demand flow control.

EP 0 566 449 A1 describes a load-sensing hydraulic control arrangement knows, in which the individual pressure compensators are downstream of the metering orifices.  

The pressure compensators are in the opening direction by the pressure after the respective Orifice plate and in the closing direction of one in a rear wheel applied control pressure, which is usually the highest Load pressure of all hydraulic consumers supplied by the same hydraulic pump equivalent. If with simultaneous actuation of several hydraulic Ver the metering orifices are opened so far that the from to The amount of pressure medium delivered to the adjusted hydraulic pump is smaller than that total amount of pressure medium required, the individual hydraulic Amounts of pressure medium flowing to consumers regardless of the respective Load pressure of the hydraulic consumers reduced proportionally. One speaks therefore from a control with load-independent flow distribution (LUDV- Control). Hydraulic consumers controlled in this way are called LUDV Called consumers. Because with a LUDV control, the highest load pressure sensed and by the hydraulic pump by varying the pressure delivered amount by a certain pressure difference Δp above the highest load pressure LUDV control is a special case of a load-sensing or load-sensing control (LS control).

For several hydraulic consumers, each of whom has a pressure medium metering orifice with an upstream individual pressure compensator that flows in the closing direction only from the pressure in front of the metering orifice and in the opening direction only from Load pressure of the respective hydraulic consumer and from a compression spring no load-independent flow distribution is obtained. One has a mere LS control and an LS consumer. Such control is z. B. known from DE 197 14 141 A1. With simultaneous actuation several hydraulic consumers and not enough of the variable pump The quantity of pressure medium supplied is only the one with the highest hydraulic pressure flow of pressure medium to the consumer is reduced.

An LUDV control arrangement with the features from the preamble of Pa claim 1 is known from the data sheet RD 64 284 / 05.99 of the applicant.  

In this, a so-called preload valve is arranged in the drain line, through that in the section of the drain line upstream of the bias valve , a preload pressure should be maintained that is in the range of 10 bar can lie. Between the mentioned section of the drain line and the Ver user line with the larger second pressure chamber of the differential cylinder ders is connected, a check valve is arranged to the consumer direction opens. The check valve can also be equipped with a pressure relief valve valve can be summarized.

The provision of the preload valve and the check valve ensures that that with a negative load acting on the differential cylinder, i.e. a load, which generates a force on the differential cylinder, which in the by the position of the Directional valve directed direction of movement of the differential cylinder is, the pressure medium displaced from the first pressure chamber in addition to that of pumped and given over the metering orifice of the directional valve and if necessary, an individual pressure compensator flowing the second pressure space of the differential cylinder is supplied. This is intended for the components harmful cavitation in the second pressure chamber of the controller, which complicates the control Differential cylinders can be avoided. However, it has been shown that the known control arrangement under special circumstances, e.g. B with piston rod conditions with a particularly large diameter in relation to the diameter of the Piston or cavitation can occur with particularly heavy loads.

The invention is therefore based on the objective of a hydraulic control arrangement that the features from the preamble of claim 1 instructs to develop so that the risk of cavitation is further reduced.

The desired goal is achieved in that at a gat hydraulic control arrangement according to the characteristic Part of claim 1 valve means are available via the pressure medium the supply line, i.e. pressure medium delivered by the variable displacement pump, into the section  the drain line in which a preload pressure is to be maintained, is feedable if in the section of the pressure to a below the front clamping value drops. In a hydraulic The control arrangement also comes from the first pressure chamber of the Diffe rial cylinder not only displaced one of the variable pump ge promoted additional amount of pressure medium through the opening cross section of the Orifice plate and the presence of an individual pressure compensator or in any case low signal of a load pressure to the variable pump is low ge pressure difference is determined via the orifice, to the second pressure chamber. Rather, further pressure medium delivered by the variable displacement pump flows through the Valve means between the inlet line and the outlet line and via the back impact valve to the second pressure chamber of the differential cylinder. The opening cross-section of the valve means and the check valve can be very large become. In addition, the full pump pressure is available without throttling by an indi vidual pressure compensator is available as a drive for the pressure medium flow.

Advantageous embodiments of a hydraulic control according to the invention arrangement can be found in the subclaims.

In a simple manner, the valve means according to claim 2 are closed In addition to the preload valve, an existing 2-way feed valve is formed.

An embodiment according to claim 3, according to which is particularly preferred the valve means comprise a pressure reducing valve with a valve piston which in the Meaning of closing the fluidic connection between the feed line and the section of the drain pipe from the pressure in this section and in the sense opening of the fluidic connection is acted upon by a spring. The Effort for the actuation of the valve means depending on that in the Ab The flow line upstream of the pressure prevailing valve is then special low.  

Basically, it is conceivable to use the preload valve and the one between the inlet device and the drain line arranged valve means to a be matched preload pressure set 3-way pressure control valve sen, at whose control output the section of the drain pipe to be prestressed, at its pressure connection, the inlet line and at its tank connection, the Tank leading section of the drain line is connected. However, it is one better adjustment to different flow rates and usage a preload valve that has already proven itself in practice is possible if, as in Pa indicated claim 2, a separate feed valve is used, the is then designed according to claim 4 as a 2-way pressure reducing valve. This is set to a pressure that is less than the preload pressure. Consequently It is ensured that pressure medium from the supply line is not in normal operation via the pressure reducing valve into the drain line and from there via the header valve flows to the tank. This would result in unnecessary energy losses. egg Adequate security against such losses appears guaranteed if the pressure reducing valve is set to a pressure which according to claim 5 is approximately 2 bar below the preload pressure.

Directional valve disks are from data sheet RD 64 282 / 10.99 from the applicant known from LS control blocks, in which two run parallel to each other the holes of the disk of the control piston of the directional valve, with which the Be direction of movement and the speed of a hydraulic consumer are controllable, and the control piston of an individual pressure compensator housed are. This control piston has a certain outer diameter, is in be right with piston collars, a piston neck and a stop pin and with one from the outer surface of the piston neck through it its end faces leading fluid path and is one of the An the surrounding compression spring, whose pressure equivalent at the given outer diameter of the control piston is about 10 bar. Advantageously, according to claim 6 for the 2-way Pressure reducing valve uses a piston and spring assembly that the in  proven in practice and of their design with regard to flow rate and Corresponding spring force suitable assembly.

An embodiment of a hydraulic control arrangement according to the invention tion as well as the constructive training of a use in the control arrangement Ren 2-way pressure reducing valve are shown in the drawings. Based these drawings, the invention will now be explained in more detail.

Show it

Fig. 1 shows the embodiment of the hydraulic control arrangement and

Fig. 2 shows a valve disk partially in section through the built-in 2-way pressure reducing valve.

In the hydraulic control arrangement according to FIG. 1, a control block 7 includes an input element 8 , an end plate 9 and in between two directional valve sections 10 and 11 , each of which has a directional valve 12 or 13 with an inlet chamber 14 , the pressure medium supplied by a hydraulic pump 18 can, a drain chamber 15 from which pressure medium can drain to a tank 19 , and has two consumer chambers 16 and 17 which are connected via consumer lines 20 , 21 to a double-acting hydraulic consumer, namely to a differential cylinder 22 and 23 , respectively. These have a rod-side, annular, first pressure chamber 24 , from which a consumer line 21 leads to a consumer chamber 17 , and a rod-side, circular cylindrical, second pressure chamber 25 , from which a consumer line 20 leads to a consumer chamber 16 .

The directional control valve 12 has a control piston 30 and the directional control valve 13 has a control piston 31 . Both control pistons 30 and 31 are adjustable in opposite directions in working positions from a central position in which the inlet chamber, the outlet chamber and the two consumer chambers are blocked off, in which one does not exist between the inlet chamber 14 and the consumer chamber 16 or the consumer chamber 17 shown in more detail in its opening cross-section of the size of the displacement of the control piston from its central position dependent orifice is open. When the control piston is adjusted in one direction, the consumer chamber 16 is connected to the drain chamber 15 in both directional valve sections via an opening cross section which is also dependent on the displacement path of the control piston. In a Verstel of the control piston 30 of the lung-way valve 12 in the opposite direction, the load chamber 17 is connected via a dependent on the displacement of the control piston 30 opening cross-section with the outlet chamber 15 °. The control piston 31 of the directional control valve 13, on the other hand, is a so-called regeneration piston, via which the consumer chamber 17 is connected to the consumer chamber 16 via a discharge orifice and the metering orifice when it is moved in the opposite direction. When the piston rod of the differential cylinder 23 is extended from its pressure chamber 24 , oil displaced does not reach the discharge chamber 15 of the directional control valve 13 , but rather the consumer chamber 16 and from there into the pressure chamber 25 of the differential cylinder 23 .

Upstream of the inlet chamber 14 of each directional control valve 12 and 13 is an individual pressure compensator 32 , on the control piston of which two control chambers 33 and 34 adjoin. The control chamber 33 is connected to a load reporting chamber 35 of the respective directional control valve 12 , 13 and the control chamber 34 is connected to the inlet chamber 14 . The load reporting chamber 35 is relieved in the middle position of the control piston 30 , 31 to the tank and in a lateral working position each connected to the consumer chamber, which is supplied via the metering oil. The Regelkol ben of the pressure compensator 32 is acted upon in the opening direction by a compression spring 36 and by the pressure prevailing in the control chamber 33 and in the closing direction by the pressure prevailing in the control chamber 34 .

A shuttle valve chain of shuttle valves 37, the respective highest pending in a control chamber 33 pressure, ie the respectively highest load pressure, optionally to an output LS in the entrance member 8 of the control block 7 and reported to a LS-pump regulator 39 through a load signal line 38 which Ver the adjusting pump 18 each adjusts so that in a section of an inlet line 40 extending from the adjusting pump 18 , via which the inlet chambers 14 of the directional control valves 12 and 13 hydraulic oil can be supplied, a pump pressure is set which is a certain pressure difference Δp above the reported maximum load pressure lies. The pressure difference is usually in the range between 10 bar and 25 bar. In the present case, a pressure difference of 20 bar may be set. If no load pressure is reported, a pressure (stand-by pressure) .DELTA.p of 20 bar is accordingly established in the inlet line 40 including the inlet channel 41 .

The inlet line 40 continues from an input P of the input element 8 from within the control block 7 as a straight inlet channel 41 , which goes through the directional valve sections 10 and 11 into the end plate 9 . The inputs of the individual pressure compensators 32 are connected to it.

Through the directional valve sections also passes through a drain channel 42 , which extends into the end plate 9 and into the input element 8 and is part of a drain flow path 43 , via which hydraulic oil can flow back from the drain chambers 15 of the directional control valves 12 and 13 to the tank 19 and in which a tank connection T of the input element 8 is located. In each directional valve section, in particular also in the directional valve section 11 with the directional valve 13 , the control piston of which is a so-called regeneration piston, there is a combined pressure-limiting and feed valve 45 , which is arranged between the consumer line 20 and the drain channel 42 . The pressure limiting function fulfills the valve 45 for the consumer line 20 , in which it limits the pressure to a value lying by a certain pressure difference above the pressure in the outlet channel. As long as the pressure in the consumer line 20 does not reach this value, the valve 45 acts as a check valve opening towards the consumer line, i.e. it allows pressure medium to flow from the outlet duct to the consumer line if the pressure in the consumer line is lower than in the outlet duct, and closes when the Pressure in the consumer line is higher than in the drain channel. Further pressure limiting and feed valves 46 are located between each consumer line 21 and the drain channel 42 .

The two directional control valves 12 and 13 can each be actuated electro-hydraulically, where two solenoid proportional control valves 50 are integrated into each directional control valve section 10 or 11 . In the rest position of a valve 50 , an associated control chamber on the control piston 30 of a directional control valve 11 , 12 is relieved to a leakage oil channel 51 , which leads through the directional control valve sections 10 and 11 . By energizing an electromagnet, a control chamber is connected to a control pressure line 52 which is also passed through the directional valve section 10 and 11 . The control oil is taken from a pressure reducing valve 53 , which is installed in the end plate 9 , through which the two directional valve sections 10 and 11 and into the end plate 9 lead channel 41 . The pressure reducing valve 53 is, for. B. is set to a control pressure of 30 bar. The leakage oil channel 51 is connected via a connection Y of the end plate 9 connected line 54 directly to the tank 19 such that the same pressure as in the tank 19 prevails in the leakage oil channel.

In the input element 8 , a pressure relief valve 60 is installed, to the sen input of the drain channel 42 and the output of which is connected to the tank connection T of the input element. Since the pressure relief valve must be designed for a large flow rate, it is preferably a pilot valve. The spring chamber, in which the pressure spring 61 producing the counterforce to the pressure force is located, is connected via a bore 62 of the input element to the leakage oil channel 51 , so that a constant tank pressure level is ensured in the spring chamber. The pressure relief valve 60 has the function of maintaining a pressure constant after setting in the upstream discharge channel 42 , which is also referred to as the biasing pressure. Therefore, the pressure relief valve can also be called a preload valve. The preload pressure is relatively low and is in the range of 5 bar to 10 bar for other applications, but can also be set to 15 bar. For example, a valve can be used as the preload valve, which is shown in more detail under the designation MHDBV in data sheet RE 64 642 / 12.97 by the applicant. In the present case, a preload pressure between 8 bar and 12 bar has proven to be favorable.

In the input element 8 , a 2-way pressure reducing valve 70 is also built, which is located at its pressure input on the inlet channel 41 and with its output, in which the valve seeks to maintain a certain pressure, upstream of the biasing valve 60 with the drain fluid path 43 , that is with the drain channel 42 is connected. The pressure reducing valve has a valve piston 71 , which is impacted by an compression spring 72 in the sense of an increase in the opening cross section of the valve and in the sense of a reduction in the opening cross section by the pressure prevailing at the outlet of the valve, ie by the pressure prevailing in the outlet channel 42 . The pressure set at the pressure reducing valve and to be maintained at the outlet is approximately 2 bar below the preload pressure set at the preload valve 60 .

Structural details of the pressure reducing valve 70 are shown in more detail in FIG. 2. Then a blind bore 74 is introduced into a disk-shaped housing 73 of the input element 8 from a narrow side, which is closed by a locking screw 75 . The blind bore 74 is expanded at two points to form axially spaced-apart annular chambers 76 and 77 , of which the annular chamber 76 passes through the inlet channel 41 and the annular chamber 77 is connected to the outlet channel 42 . Between the bottom of the blind bore and the locking screw 75 , the valve piston 71 located in the blind bore is axially displaceable. This has a first piston collar 78 , a second piston collar 79 and a piston neck 80 between the two piston collars, so that an annular groove 81 is formed between the two piston collars. This is located in the area of the two annular chambers 76 and 77 . On its annular groove 81 facing outer edge, which controls the opening cross section of the valve 70 as the control edge of the valve piston 71 with the inner edge of the annular chamber 76 close to the annular chamber 77, the piston collar 78 is provided with Feinsteuernu ten 82 .

The ring chamber 76 closer to the screw plug 75 of the two ring chambers 76 and 77 is at a distance from the inner end of the screw plug. In this area of the blind bore 74 , the valve piston 71 has a further piston collar 83 . This separates a pressure chamber 85 between the screw plug 75 and the face 86 of the valve piston facing it. The piston collar 83 is created by a further screwing 84 of the valve piston between it and the piston collar 78 . This rotation has nothing to do with the control function of the valve piston 71 , but only contributes to a large flow cross section for the pressure medium in the region of the annular chamber 76 . Without the indentation 84 , only a piston collar would then be present between the piston neck 80 and the end face 86 of the valve piston 71 .

The pressure chamber 85 between the valve piston 71 and the locking screw 75 is fluidly connected to the annular groove 81 via a bore in the valve piston, which includes a blind bore 87 axially introduced from the end face 86 and a continuous transverse bore 88 in the piston neck 80 .

From the side facing away from the annular groove 81 of the piston collar 79 , a stop pin 89 protrudes from it, which has a smaller diameter than the blind bore 74 and whose valve piston 71 , which bears against the locking screw 75, has the possible displacement of the valve piston before the clear distance from the bottom of the blind bore clarified. The space 90 between the bottom of the blind bore 74 and the piston collar 79 is fluidly separated from the annular chamber 77 by this and is connected to the leakage oil channel 51 via the bore 62 which also opens into the bottom of the blind bore. So there is 90 tank pressure in the room. From this space 90 , the compression spring 72 is taken, which is supported on the bottom of the blind bore 74 and, overlapping the stop pin and as a guide, on the piston collar 79 of the valve piston 71 . The preload of the compression spring 72 can be varied by means of washers 92 .

In Fig. 2 also protruding parts of the valves 60 and 65 and the tank connection T can be seen from the housing 73 .

When the pump 18 is switched off for a longer time, there is no pressure in the inlet channel 41 . If the pressure in the outlet channel 42 is lower than the pressure set on the pressure reducing valve, its valve piston 71 assumes the position shown in FIG. 2. If, however, the pressure in the outlet channel 42 is higher, the valve piston is displaced to the left in comparison to the position shown in FIG. 2 and separates the ring chamber 76 and thus the inlet channel 41 from the annular chamber 77 and thus from the outlet channel 42 .

If the differential cylinders 22 and 23 are operated when the directional control valves 12 or 13 are actuated with a pressing load in the sense of extending the piston rod, the pressure in the consumer line 20 located in the supply line is above the biasing pressure prevailing in the discharge line, so that the check function of the valves 45 does not respond and the preload pressure set on valve 60 is maintained in the drain line. The bias pressure is on the ring chamber 77 , the annular groove 81 and the bores 87 and 88 in the pressure chamber 85 and holds the valve piston in a position shifted to the left compared to the position shown in Fig. 2, in which the piston collar 78 the control edge has passed over the annular chamber 76 and keeps the outlet line 42 separate from the inlet line 41 . Due to the lower pressure setting of the pressure reducing valve 70 compared to the preload valve 60 , no pressure medium flows from the inlet channel 41 via the pressure reducing valve into the outlet channel 42 and from there via the preload valve 60 to the tank 19 . Such a pressure medium flow would be associated with unnecessary energy losses.

When the differential cylinders 22 and 23 are operated with pulling loads and in the sense of extending the piston rod, whether the directional control valve 12 is actuated with the control piston 30 or the directional control valve 13 with the control piston 31 designed as a regeneration piston, the pressure can occur in the consumer line 20 under the pressure set on the preload valve 60 and further drops below the pressure set on the pressure reducing valve 70 . In such a case, pressure medium flows from the outlet channel 42 into the corresponding consumer line 20 via the corresponding valve 45 acting as a check valve. The pressure reducing valve 70 opens and leads the drainage channel from the variable displacement pump, at least under the stand-by pressure, to pressure medium which, in addition to the return oil displaced from the pressure chambers 24 of the differential cylinders, reaches the consumer lines 20 and the pressure chambers 25 .

When the directional control valve 12 is actuated, this return oil passes through the drain chamber 15 into the drain channel 42 and from there, depending on which hydraulic consumers are operated under which operating conditions, via a valve 45 into one, the other or both consumer lines 20 . In one of the directional valve Actuate the supply 12 also flows through the pressure compensator 32 and the metering orifice to a particular cross-section through the opening amount of pressure medium from the inflow channel 41 to the pressure chamber 25 of the differential cylinder 22nd

When the directional control valve 13 is actuated with a regeneration piston, the return oil from the pressure chamber 24 of the differential cylinder 23 can only get into the pressure chamber 25 of this cylinder. Moreover, it may under certain ready for operation conditions for the differential cylinder 23 be that because of the Regenerationskol bens 31 corresponding to the directional control valve 13 closes associated pressure balance, so that the pressure chamber 25 of the cylinder 23 only with the return oil from the pressure chamber 24 of the cylinder 23 and from the pressure chamber 24 of the possibly actuated cylinder 22 and is filled with pressure medium flowing to the outlet channel via the pressure reducing valve 70 .

Claims (7)

1. Hydraulic control arrangement for supplying pressure medium, preferably several hydraulic consumers ( 22 , 23 )
with a demand-flow-controlled (load-sensing-regulated) variable pump ( 18 ), the setting of which can be changed as a function of the highest load pressure of the actuated hydraulic consumers ( 22 , 23 ),
with an annular first pressure chamber ( 24 ) and a circular cylindrical second pressure chamber ( 25 ) having differential cylinders ( 22 , 23 ) as hydraulic consumers,
With a proportionally adjustable directional valve ( 12 , 13 ), with which the pressure medium paths between an inlet line ( 40 ) coming from the variable pump ( 18 ), an outlet line ( 43 ) leading to a tank ( 19 ) and one to the first pressure chamber ( 24 ) the first consumer line ( 20 ) leading the differential cylinder ( 22 , 23 ) and a second consumer line ( 21 ) leading to the second pressure chamber ( 25 ) of the differential cylinder ( 22 , 23 ) are controllable,
with a preload valve ( 60 ) for generating a preload pressure in a section ( 42 ) of the outlet line ( 43 ) located upstream of the preload valve ( 60 ) and with one between the section ( 42 ) of the outlet line ( 43 ) and the second consumer line ( 21 ) and to this opening check valve ( 45 ),
characterized by valve means ( 70 ), via which pressure medium from the inlet line ( 41 ) can be fed into said section ( 42 ) of the outlet line ( 43 ), if in this section ( 42 ) the pressure drops to a value below the prestressing pressure. 2. Hydraulic control arrangement according to claim 1, characterized in that the valve means by an additional to the biasing valve ( 60 ) existing NES 2-way feed valve ( 70 ) are formed. 3. Hydraulic control arrangement according to claim 1 or 2, characterized in that the valve means comprise a pressure reducing valve ( 70 ) with a valve piston ( 71 ) which in the sense of closing the fluidic connection between the feed line ( 40 ) and the section ( 42 ) the drain line ( 43 ) is acted upon by the pressure in this section ( 42 ) and in the sense of opening the fluidic connection by a spring ( 72 ). 4. Hydraulic control arrangement according to claims 2 and 3, characterized in that the feed valve is a 2-way pressure reducing valve ( 70 ) which is set to a pressure which is less than the biasing pressure. 5. Hydraulic control arrangement according to claim 4, characterized in that the 2-way pressure reducing valve ( 70 ) is set to a pressure which is approximately 2 bar below the biasing pressure. 6. Hydraulic control arrangement according to claim 4 or 5, characterized in that the valve piston ( 71 ) of the 2-way pressure reducing valve ( 70 ) has two axially spaced piston collars ( 78 , 79 ), between which there is a piston shark ( 80 ) That the edge of the first piston collar ( 78 ) facing the annular groove ( 81 ) around the piston neck ( 80 ) forms a control edge which cooperates with a control edge of a housing ( 73 ) which is connected to an annular space ( 40 ) connected to the inlet line ( 40 ). 76 ) of the housing ( 73 ) rotates that through the valve piston ( 71 ) from the piston neck ( 80 ) to the, from the second piston collar ( 79 ) as seen, beyond the first piston collar ( 78 ) located end face ( 86 ) of the valve piston leads (71), a fluid path, and that benbund the second Kol (79) on the tang (80) side facing away from a compression spring (72) is supported, into which a projecting from the second piston collar (79) Anschlagzap fen (89) into protrudes. 7. Hydraulic control arrangement according to a preceding claim, characterized in that the directional control valve ( 12 , 13 ) is assigned an inlet pressure compensator ( 32 ).