EP1996821B1 - Ludv (load-independent flow distribution system) valve arrangement - Google Patents

Abstract

An LIFD valve assembly has a pressure balance device a pressure balance slide of which is urged in the opening direction by a pressure downstream of a metering aperture and in the closing direction by a control pressure preferably corresponding to the highest load pressure of a plurality of consumers, and a load pressure downstream of the metering aperture is reportable to a line via the pressure balance device, and a load-maintaining device that can be put in a closing position, in which position a pressure medium flow path from a consumer to the metering aperture is blocked. The pressure balance slide is embodied in divided fashion, with an upper part and a lower part, wherein the latter is guided on the upper part, and determines the pressure balance device throttle cross section with a pressure balance control edge and embodies a closing body of the load-maintaining device.

Description

The invention relates to a LUDV valve assembly according to the preamble of claim 1 and a valve block having a plurality of such LUDV valve assemblies.

The basic structure of such LUDV valve arrangements is for example from EP 0 566 449 A1 or EP 0 566 449 B1 known. This is a hydraulic control arrangement according to the load-sensing principle, in which a variable displacement pump is adjusted in each case depending on the highest load pressure of the actuated hydraulic consumers so that the inlet pressure is above the highest load pressure by a certain pressure difference. The hydraulic consumers while the pressure medium flows through adjustable metering orifices, which are each arranged between an outgoing of the variable displacement pump line and the respective consumer. By each of the metering orifices downstream pressure compensators is achieved that there is a certain pressure difference across the metering orifices with sufficient pressure fluid supplied regardless of the load pressures of the hydraulic consumers, so that the hydraulic fluid inflowing pressure medium quantity only depends on the opening cross section of the respective metering orifice. If a metering orifice is opened further, more pressure medium must flow over it in order to generate the specific pressure difference. The variable displacement pump is adjusted in such a way that it supplies the required amount of pressure medium. Therefore, one speaks of a demand flow control.

The pressure compensators connected downstream of the metering orifices are acted upon in the opening direction by the pressure downstream of the respective metering orifice and in the closing direction by a control pressure prevailing in a rearward control chamber, which usually corresponds to the highest load pressure of all hydraulic consumers. If, in a simultaneous operation of several hydraulic consumers, the metering orifices are made so far on that the delivered by the stop adjusted hydraulic pump pressure medium is less than the total required pressure medium, the individual hydraulic consumers flowing pressure fluid quantities are independent of the respective load pressure of the hydraulic consumers proportionally reduced. This is why we speak of a controller with load-independent flow distribution (LUDV control).

In order to prevent the load from sagging when the pump pressure is insufficient, a load-holding valve is arranged in each case in the pressure medium flow path between the load and the pressure compensator associated therewith. This is usually carried out with a valve plug, which shuts off the pressure medium flow path substantially leak-free at a backflow of pressure medium from the consumer towards the metering orifice, so that the consumer can not sag at an unwanted reduction in the pump pressure. A disadvantage of this solution is that a considerable device-technical effort is required to integrate the one or more load-holding valves in the valve block. Furthermore, these load-holding valves require a complex ducting and take up considerable space, so that a compact design of the valve arrangement is difficult. Another disadvantage is that the load-holding valves have a high hydraulic resistance.

To overcome this disadvantage, is in the publications US 5,535,663 . EP 1 023 508 B1 and US 5,067,389 proposed to carry out the individual pressure compensators assigned to the respective consumer in two parts with an upper and a lower part, wherein the lower part acts as a load-holding valve. In all these known solutions, the two-part pressure compensator can only be produced with a high manufacturing outlay. Furthermore, the ducting for tapping the individual load pressure downstream of the metering orifice is made very complex.

In contrast, the invention has for its object to provide a LUDV valve assembly and a running with several such LUDV valve assemblies valve block, in which a sagging of the load with low device complexity and low hydraulic resistance can be prevented.

This object is achieved with regard to the LUDV valve arrangement by the feature combination of claim 1 and with respect to the valve block by the feature combination of claim 19.

According to the invention, starting from the closest prior art according to the EP 0 566 449 B1 the pressure compensator is formed in two parts with an upper part and a lower part, wherein the lower part is guided on the upper part. Thereby allows the pressure compensator receiving housing portion much easier than in the per se known two-part pressure compensators run in which the upper and the lower part are each guided in the housing. The lower part forms a closing body for load-holding and has a pressure compensator control edge, which determines the throttle cross-section of the pressure compensator.

In a preferred embodiment, the guide diameter between the top and the bottom is smaller than the valve seat diameter.

The upper part can either be guided directly in the housing or inside a valve bushing inserted into the housing. It is preferred if the outer diameter of the upper part is equal to or greater than the valve seat diameter.

The lower part of the two-part pressure compensator is preferably designed with a connecting channel, which opens into a space bounded by the upper part and the lower part, in which approximately the same pressure is applied as on the pressure compensator input.

The load report is particularly simple when the upper part is designed with a control edge, via which a connection to the LS line can be opened.

This control edge can be carried out in a preferred embodiment by a transverse bore in which an axial bore opens, which is connected to the space between the upper part and the lower part.

Between the upper and the lower part, a weak spring may be arranged, which the lower part in the closing direction, i. applied to the valve seat.

The valve cone of the load-holding function enabling valve member can be formed either on the lower part or the housing side.

In the former alternative, the valve seat side front face of the upper part is set back so that the part of the valve cone located downstream of the valve seat is pressure-balanced.

The control can be further improved if fine control notches are made on the lower part.

The lower part may be guided on an outer peripheral portion or an inner peripheral portion of the upper part.

During operation of the pressure compensator, the upper part and the lower part abut each other, while the lower part can accumulate on a Innenstimfläche or a Außenstimfläche the upper part.

An LUDV valve arrangement assigned to a consumer preferably has a continuously adjustable directional control valve with a speed part forming the inlet orifice plate and a directional part arranged downstream of the pressure compensator, via which a pressure medium flow path from the pressure compensator to a consumer connection and from another consumer connection to a tank can be opened.

In one embodiment of the invention, the two-part pressure compensator valve is assigned a damping device, so that high-frequency pressure fluctuations can be damped.

In a concrete solution, this damping device is formed by a nozzle bore, via which a rear space of the pressure compensator slide is connected to the LS line. This nozzle bore is opened regardless of whether the highest load pressure in the LS-line is reported via the pressure compensator valve or not.

To improve the function of the pressure compensator, the pressure compensator can be designed with a sliding seat.

The valve block, for example, a mobile implement, is preferably designed in disk construction with several such LUDV valve assemblies.

• Figur 1 eine Schnittdarstellung einer Ventilscheibe eines LUDV-Ventilblocks;
• Figur 2 eine Druckwaage für einen LUDV-Ventilblock gemäß Figur 1;
• Figur 3 die Druckwaage aus Figur 2 in einer Lasthalteposition;
• Figur 4 ein Ausführungsbeispiel einer Druckwaage mit Feinsteuerkerben;
• Figur 5 ein Ausführungsbeispiel einer vereinfachten Druckwaage;
• Figur 6 eine Druckwaage gemäß Figur 5 in einer Lasthalteposition;
• Figur 7 eine Variante einer Druckwaage gemäß Ausführungsbeispiel 5;
• Figur 8 ein weiteres Ausführungsbeispiel einer Druckwaage für eine LUDV-Ventilanordnung gemäß Figur 1 und
• Figur 9 eine Ausführungsform mit Dämpfung.

In the following preferred embodiments of the invention will be explained in more detail with reference to schematic drawings. Show it:

• FIG. 1 a sectional view of a valve disc of a LUDV valve block;
• FIG. 2 a pressure compensator for a LUDV valve block according to FIG. 1 ;
• FIG. 3 the pressure balance off FIG. 2 in a load holding position;
• FIG. 4 an embodiment of a pressure compensator with fine control notches;
• FIG. 5 an embodiment of a simplified pressure compensator;
• FIG. 6 a pressure compensator according to FIG. 5 in a load holding position;
• FIG. 7 a variant of a pressure compensator according to embodiment 5;
• FIG. 8 a further embodiment of a pressure compensator for a LUDV valve assembly according to FIG. 1 and
• FIG. 9 an embodiment with damping.

FIG. 1 shows a section through a valve disc 1 of a mobile control block of a mobile implement, such as a compact excavator, minibagger, backhoe or loader. Via the valve disc 1, a pressure chamber of a consumer, for example a hydraulic cylinder with a LS pump and another pressure chamber of this consumer can be connected to a tank in order to effect an extension or retraction movement of the hydraulic cylinder. According to the sectional view, the valve disc 1 has a housing 2, on which a working port A and a working port B are formed, to which the associated consumer is connected. In the housing 2, a continuously adjustable directional control valve 4 and a LUDV pressure compensator 6 are added.

The continuously adjustable directional control valve 4 has approximately the same basic structure as in the EP 0 566 449 B1 is described, so that only the components required for understanding are described here and reference is otherwise made to the prior art to LUDV valve assemblies. The directional control valve 4 has a valve slide 8, which is accommodated axially displaceably in a valve bore 10 and is biased by a centering spring arrangement 12 in its illustrated center position. Both end portions of the valve spool 8 project from the housing 2 and each dip in a control chamber 14 and 16, which is bounded in each case by the valve disc 2 flanged valve caps 18, 20, wherein the centering spring assembly 12 in the in FIG. 1 left control room 14 is added. The valve caps 18, 20 are each provided with a control port y, z, which are each connected to control lines, so that by applying a Control pressure difference of the valve slide 8 can be deflected against the force of Zentrierfederanordnung 12 from its illustrated center position.

The valve bore 10 is shown in the illustration FIG. 1 from left to right in the radial direction to a first tank space 22, a first flow space 24, a first pressure balance discharge space 26, an inlet space 28, a pressure chamber 30, a second pressure balance discharge space 32, a second flow space 34 and a second tank space 36 expanded. The tank spaces 22; 36 of all valve disks 1 of the valve block are connected to a tank connection T. The flow chamber 24 is connected via a working channel 38 to the working port A and the flow chamber 34 via a working channel 40 to the working port B. The two pressure compensator drain chambers 26, 32 are connected via a bow channel 42, which is connected to the output of the pressure compensator 6. Their input is connected via a pressure compensator duct 44 to the inlet chamber 28. The pressure chamber 30 is connected via a pump line to the pressure connection of said LS pump. The activation of this LS pump is dependent on the highest load pressure of all consumers connected to the valve block. This highest load pressure is tapped via a shuttle valve cascade from the consumer and is located in an LS channel 46 at. On the valve spool 8 are formed by a plurality of annular grooves a tank collar 48, an adjacent working collar 50, a middle Meßblendenbund 52, another Arbeitsbund 54 and another tank collar 58, wherein the two tank collars 48, 56 form the end portions of the valve spool 8, in the anchors 58, 60 are screwed, on which, for example, the centering device 12 is supported and immersed in the control chambers 14, 16.

The said collars are designed with a working edge 58, a working edge 60, orifice control edges 62, 64, another working edge 66 and another tank control edge 68, wherein the control edges 68, 64, 62 and 58 are executed with Feinsteuerkerben. In the illustrated basic position, the connection between the working ports A, B and the tank spaces 22, 36 and the pressure chamber 30 is shut off. By moving the valve spool 36 to the left (view after FIG. 1 ), a metering orifice cross section is opened via the metering orifice control edge 62 of the valve spool 8, which determines the pressure medium volume flow and thus the operating speed of the consumer. The pressure medium can then flow from the pressure chamber 30 via the controlled metering orifice into the inlet chamber 28 and is then throttled as far as the two-part pressure compensator 6, that at the pressure compensator output of the individual load pressure and the pressure compensator input a pressure approximately corresponding to the highest load pressure. The pressure medium can then flow through the controlled over the working control edge 66 cross section of a direction part of the arc channel 42 into the second Voriaufraum 34 and from there via the working channel 40 and the port B to the pressure chamber of the connected consumer. The displaced from the other pressure chamber of the consumer pressure fluid flows through the working port A, the working channel 38, the flow chamber 24 and the controlled over the tank control edge 58 of the direction of cross section in the first tank space 22 and from there via the tank port (not shown) from the tank , The pressure medium supply of the connected to the working port A pressure chamber is carried out in a corresponding manner by moving the valve spool 8 from its illustrated center position to the right.

The structure of the two-part pressure compensator 6 will be explained in detail with reference to the other figures.

FIG. 2 shows a first embodiment of a pressure compensator 6, which in a circuit according to FIG. 1 is usable. This pressure compensator 6 is inserted into a graduated pressure compensator bore 70 opening into the arcuate channel 52 and, in the illustrated embodiment, has a valve bushing 72 screwed into the pressure compensator bore 70, which is sealed via seals to the arc channel 42 and outwardly. A radially enlarged threaded head 74 is axially offset from an annular face of the pressure balance bore 70 to form an annular space 76 into which the LS passage 46 opens. The valve sleeve 72 has a blind hole designed as a guide bore 78 in which a pressure compensator 80 is guided in sections.

According to the invention, this pressure balance slide 80 is designed in two parts with an upper part 82 and a lower part 84. The approximately cup-shaped upper part 82 is guided along its outer circumference in the guide bore 78 and rests in the illustrated basic position with its end face 86 at the bottom of the guide bore 78 designed as a blind hole. Recesses 88 are arranged on this end face 86, so that the space between the end face 86 and the bottom of the guide bore 78 is connected to the LS channel 46 via fine grooves (not shown) on the outer circumference and a radial bore 90. Thus, the End face 86 of the upper part 82 always acted upon by the load in the LS channel 46 highest load pressure of all driven loads.

The cup-shaped upper part 82 has an inner space with a bottom 92 and a cylindrical inner peripheral wall 94, along which a guide projection 96 of the lower part 84 is guided. This has a relative to the guide projection 96 radially projecting, mushroom-shaped poppet 98 which is biased against a seat edge 100 in the housing 2. About this valve seat, the connection from the bow channel 42 to the pressure compensator channel 44 can be blocked, so that no pressure medium can flow from the connected to the pump load port. The lower part 84 is designed with an axial through bore 102 which is radially widened towards the upper part 82 and via which the pressure compensator channel 44 is connected to a space 104 formed between the lower part 84 and the upper part 82. This is in the illustrated basic position (no consumer driven pump not swung) via an axial bore 106 and a transverse bore 108 of the upper part 82 connected to the radial bore 90. That in this position of the upper part 82, the pressure applied in the pressure compensator channel 44 upstream of the pressure compensator 6 is reported in the LS channel 46 - such a position of the upper part will then set when the load pressure of the connected to the working ports A, B consumer of the highest load pressure of all consumers. As will be explained in more detail below, in this case, however, the lower part 84 is lifted by the pressure in the pressure compensator channel 44 from the seat edge 100 and the pressure compensator completely open, so that the pressure in the arc channel 42 is equal to the highest load pressure in the pressure compensator channel 44.

In the illustrated embodiment, a comparatively weak spring 110 is disposed between the upper part 82 and the lower part 84, which is supported on the one hand on the bottom 92 of the upper part and on the other hand on an annular end face of the through hole 102 of the lower part 84 and thus biases this in its closed position. The annular end face 112 is chamfered, so that it can not rest over its entire surface on the back of the valve cone 100 lifting off from the valve seat 100. In the illustrated embodiment, the valve seat diameter V is equal to the outer diameter D of the upper part 82, ie the diameter with which the upper part 82 is guided in the valve sleeve 72. Furthermore, the outer diameter d of the guide projection 96 of the lower part 84 is smaller than the valve seat diameter V. This partial feature is also fulfilled in all other embodiments described below.

If some of the connected to the mobile control block consumers are supplied with pressure medium, is in the LS-channel 46, the highest load pressure, so that the upper part 82 against the force of the comparatively weak spring and against the pressure in the space 104 from the position shown in FIG in the FIG. 3 shown investment position is shifted to the lower part. The radial bore 90 is controlled by a formed by the transverse bore 108 control edge 109 of the upper part 82 and the end face 86 is acted upon via the radial bore 90 with the pressure in the LS channel 46. The slight leakage from the transverse bore 108 in the limited by the end face 86 rear control chamber 113 (see FIG. 3 ) is negligible.

In the FIG. 3 shown position arises, for example, when the associated consumer is not supplied with pressure medium or - as described above - the pressure in the pressure compensator duct 44 drops below the individual load pressure in the arc duct 42. When driven consumer, ie when moving the valve spool 8 of the directional control valve 4 from his in FIG. 1 illustrated basic position, a corresponding to the highest load pressure or slightly higher pressure in the pressure compensator passage 44, so that the valve plug 98 is acted upon with its valve seat diameter V corresponding surface in the opening direction. The surface regions of the valve cone 98 arranged beyond the seat edge 100 are pressure-balanced by the chamfer 112. The end face 86 has the diameter D, which is equal to the valve seat diameter V in the illustrated embodiment. Due to the slightly larger acting in the opening direction pressure in the pressure compensator channel 44, the valve plug 98 is lifted from the seat edge 100, the upper part 82 remains approximately in its illustrated abutment position on the lower part 84, as long as the pressure difference between pressure in the pressure compensator channel 44 and the highest load pressure 46 is greater than the force of the spring 110 is.

When the pressure in the pressure compensator channel 44 drops, the load holding function becomes effective, wherein the valve cone 98 is moved by the force of the spring 110 into its closed position against the seat edge 100, so that a backflow from the arc channel 42 to the pressure compensator channel 44 is prevented.

In the case where the highest load pressure is applied to the associated load, the pressure compensator is fully open and the pressure in the arc duct corresponds to the highest load pressure. The upper part 82 and the lower part 84 are moved together against the pressure in the LS channel 46 up to the control edge 109 the Connection to the radial bore 90 aufsteuert so that the pressure corresponding to the highest load pressure in the pressure balance channel 44 via the through hole 102, the axial bore 106, the transverse bore 108 and the radial bore 90 is reported in the LS channel 46. In this case, the lower part 84 and the upper part 82 are not exactly adjacent to each other, but are spaced from one another by a region corresponding to the spring force 110.

In the control positions of the pressure compensator 6 whose throttle cross-section is determined by the annular gap between the seat edge 100 and the outer periphery of the valve cone. In order to improve the control behavior, according to FIG. 4 Fine control notches 114 are formed. In this embodiment, the valve plug 98 is compared to the embodiment according to FIG. 2 formed smaller axial length. Subsequent to the valve cone 98, a slide projection 116 is formed, which is provided with the fine control notches 114. This slide projection 116 lies with its outer periphery slidably against a seat slide surface 118 of the housing 2. Also in this embodiment, the valve seat diameter V is equal to the outer diameter D of the upper part 82 and thus the diameter of the guide bore 78. The lower part 84 is executed in this embodiment, therefore, as a valve spool. Incidentally, this embodiment corresponds to the above-described according to the Figures 2 and 3 , so that further explanations are dispensable.

FIG. 5 shows a simplified variant in which the valve sleeve 72 is omitted. In this variant, the upper part 82 is guided directly in the pressure balance bore 70, which is closed by a screw plug 120 whose geometry corresponds approximately to that of the head 74 of the valve sleeve, so that in turn an annular space 76 is formed. In this embodiment, the guided outer diameter D of the upper part 82 is made slightly larger than the valve seat diameter V, to allow the installation of the lower part with the poppet 98.

As FIG. 6 can be removed, in this embodiment, the upper part 82 is not in its stop position on the back of the mushroom-shaped valve cone 98, but an annular end face 121 of the guide projection 96 runs on the bottom 92nd
the blind hole of the upper part 82, so that the annular end face 112 is spaced to the rear of the valve cone 98. Incidentally, the function corresponds and the structure of the embodiment according to FIG. 6 from that one FIG. 2 , so that further explanations are dispensable.

In FIG. 7 is a variant of the in the Figures 5 and 6 shown embodiment, wherein the valve plug 98 is formed on the housing 2 and the seat edge 100 in kinematic reversal on the lower part 84, wherein the valve seat diameter V in this embodiment is equal to the guided outer diameter D of the upper part 82, so that the balance of power in about the same in the embodiment according to FIG. 2 are, while in the embodiment according to the Figures 5 and 6 due to the larger diameter D with respect to larger forces acting in the closing direction forces are increased, so that in this embodiment, the difference between the pressure in the pressure compensator channel 44 and in the LS channel 46 must be greater than in the other embodiments.

In the embodiments described above, the lower part 84 is always guided within the upper part 82. FIG. 8 shows an embodiment in which the lower part 84 is guided with its guide projection 96 on the outer circumference of a guide collar 122 of the upper part 82, which is radially opposite to a guided directly in the pressure balance bore 70 guide member 124. The guide projection 96 runs in this embodiment with its upper annular end face 121 on the radial shoulder between the guide collar 122 and the guide member 124. Also in this embodiment, the seat edge 100 is executed on the lower part 84 and the cone 98 on the housing side. Furthermore, the valve seat diameter V corresponds to the guide diameter of the upper part 82, ie, the outer diameter D of the guide part 124 or the diameter of the pressure balance bore 70. The transverse bore 108 in this embodiment runs perpendicular to the plane of the drawing, so that the LS channel is also not visible. The structure, however, otherwise substantially corresponds to the above-described embodiments, in particular the embodiment according to FIG. 7 ,

The guides for upper and lower parts 82, 84 are each made tight.

FIG. 9 shows an embodiment of a damped pressure compensator. The basic structure of this embodiment corresponds largely to that of the Figures 2 and 4 , so that only the essential differences will be explained below, with reference to the relevant comments below.

Also, the embodiment of a LUDV pressure compensator 6 according to FIG. 9 has a valve sleeve 72, along the guide bore 78, the upper part 82 of the pressure compensator slide 80 is guided axially displaceable. The lower part 84 dives with its guide projection 96 in the cup-shaped upper part 82 and carries on his in FIG. 9 underlying end portion of a valve body, which, as the embodiment according to FIG. 4 is executed with sliding seat. Accordingly, the closing body has, similar to the previously described embodiments, a valve cone 98, to which a slide projection 116 connects in the axial direction to the pressure compensator channel 44. The valve cone 98 cooperates with a seat 128, while the outer periphery of the slide portion 126 is guided along a seat slide surface of the pressure compensator channel 44, so that is determined by a control edge formed by a bevel 132 of the opening cross section of the pressure compensator. The control edge 132 may, like the embodiment according to FIG. 4 be executed with control notches, which determine the initial opening cross section of the pressure compensator. In the slide projection 116 open one or more diagonal bores 134, which via a central bore 136 with the space 104 between the upper part 82 and the lower part 84th

In an annular projection 138 of the upper part 82 which surrounds the guide projection 96, openings 140 are provided which open into an annular groove 142. This can be brought to report the highest load pressure in the LS channel 46 with the formed in the valve sleeve 72 radial bore 90 in coverage. In the illustration according to FIG. 9 This direct connection between the space 104 and the LS channel 46 is not opened or with a minimum opening cross-section.

Between the rear end face 86 and a Innenstimfläche 144 of the guide bore 78 a rear space 146 is limited, which is connected via a nozzle bore 148 with the LS channel 46. This connection is always open regardless of the axial position of the upper part 82.

In the illustration according to FIG. 9 the pressure compensator 6 is shown in a control position, in which via the control edge 132, a throttle cross-section is opened, while the LS pressure acts on the back and the pressure compensator valve 80 is acted upon in the opening direction by the pressure in the pressure balance channel 44. In the interior 104 acts via the bores 134, 136, the pressure in the arc channel 42, the also acts on the back of the valve cone 98 and the upper part 82 is acted upon in the opening direction.

In order to be able to connect both the nozzle bore 148 and the radial bore 90, which is arranged at an axial distance, to the LS channel 46, this is designed downwards, toward the radial bore 90 with a connecting chamber 150.

The damping of the pressure compensator valve 80 in its control positions takes place in that during an axial displacement of the upper part 82, pressure medium has to be displaced from the rear space 146 via the nozzle bore 148 to the LS channel or has to flow out of it.

Also in this embodiment, the valve seat diameter V is equal to the outer diameter D of the upper part and the diameter d of the guide projection 96 smaller than V and D executed.

Regarding the function of in FIG. 9 shown pressure compensator 6 can be made to the above embodiments.

Disclosed are a LUDV valve assembly and a valve block with a plurality of such LUDV valve assemblies with two-part pressure compensator. A lower part of a pressure compensator slide is guided on an upper part, wherein the lower part with a housing-fixed portion of the valve assembly forms a valve seat of a load-holding device.

Claims (19)

1. LUDV valve arrangement with a pressure balance (6), of which the pressure-balance slide (80) can be acted upon in the opening direction by a pressure downstream of a metering diaphragm and in the closing direction by a control pressure preferably corresponding to the highest load pressure of a plurality of consumers, a load pressure being communicatable downstream of the metering diaphragm, by the pressure balance (6), to an LS line (46), and with a load-holding device which can be brought into a closing position in which a pressure-medium flow path from a consumer to the metering diaphragm is shut off, characterized in that the pressure-balance slide (80) is designed to be split, with an upper part (82) and a lower part (84), the latter being guided on the upper part (82), determining the pressure-balance throttle cross section by means of a pressure-balance control edge, and forming a closing body (98) of the load-holding device.
2. Valve arrangement according to patent Claim 1, the guide diameter (d) between the upper part (82) and the lower part (84) being smaller than the valve-seat diameter (V).
3. Valve arrangement according to patent Claim 1 or 2, the outside guide diameter (D) of the upper part (82) being identical to or larger than the valve-seat diameter (V).
4. Valve arrangement according to one of the preceding patent claims, the lower part (84) being designed with a connecting duct (102) which issues in a space delimited by the upper part (82) and by the lower part (84).
5. Valve arrangement according to one of the preceding patent claims, the upper part (82) having a control edge (109), via which a connection to the LS line (46) can be opened.
6. Valve arrangement according to patent Claims 4 and 5, the control edge (109) being formed by a transverse bore (108) of the upper part (82), in which transverse bore an axial bore (106) connected hydraulically to the space (104) issues.
7. Valve arrangement according to one of the preceding patent claims, a spring (110) which acts upon the lower part (84) in the closing direction being arranged between the upper and the lower part (82, 84).
8. Valve arrangement according to one of the preceding patent claims, the upper part (82) being guided in a valve bush (72) or in a portion of a housing (2).
9. Valve arrangement according to one of the preceding patent claims, a valve cone (98) being formed on the lower part (82) or on the housing side.
10. Valve arrangement according to patent Claim 9, first alternative, the valve-seat-side annular end face (112) of the upper part (82) being set back in such a way that that part of the valve cone (98) which lies downstream of the valve seat (98, 100) is pressure-compensated.
11. Valve arrangement according to patent Claim 9 or 10, fine control notches (114) being formed in the region of the valve cone (98).
12. Valve arrangement according to one of the preceding patent claims, the lower part (84) being guided on an outer circumferential portion (122) or an inner circumferential portion (94) of the upper part (82).
13. Valve arrangement according to one of the preceding patent claims, the lower part (84), in an abutment position, running onto a bottom (92) or an outer end face (112) of the upper part (82).
14. Valve arrangement according to one of the preceding patent claims, with a continuously adjustable directional valve (4), with a velocity part forming the metering diaphragm and with a directional part which is arranged downstream of the pressure balance (6) and via which a pressure-medium flow path from the pressure balance (6) to one consumer connection (A, B) and from another consumer connection (B, A) to a tank can be opened.
15. Valve arrangement according to one of the preceding patent claims, with a damping device (148) for damping the movement of the pressure-balance slide (80; 82, 84).
16. Valve arrangement according to patent Claim 15, the damping device being a nozzle bore (148), via which a back space (146) delimited by a rear-side end face (86) of the upper part (82) is connected to the LS line (46).
17. Valve arrangement according to patent Claim 16, the nozzle bore (148) always being open towards the back space (146).
18. Valve arrangement according to one of the preceding patent claims, the closing cone (98) being designed with a sliding seat.
19. Valve block with a plurality of valve arrangements according to one of the preceding patent claims.

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