EP2225470B1 - Valve arrangement - Google Patents

Description

The invention relates to a valve arrangement according to the preamble of claim 1.

Such a valve arrangement is used, for example, for controlling hydraulic consumers of a mobile working machine, for example a wheel loader, a bulldozer, a telescopic forklift or a downhole loader.

The data sheet RD 64 284 / 06.00 of Mannesmann Rexroth AG describes a LUDV mobile control block in which the pressure medium supply to the consumers is controlled via directional control valve sections, each with a continuously adjustable directional control valve. This is carried out with a speed part formed by a metering orifice and a pressure medium flow direction to and from the consumer-determining directional part. The metering orifice is assigned to a LUDV pressure compensator. In such a mobile control block, a load pressure independent flow distribution (LUDV) is given for simultaneously driven consumers. In such LUDV systems are - very simply said - in a shortage of the driven consumers, i. Then, when a pump can no longer meet the desired pressure medium requirement, the pressure differences across all open metering orifices smaller, so that the actuated consumers flowing pressure fluid quantities are reduced in ratio. In this way, an undesirable stoppage of individual consumers can be prevented. However, the invention is not limited to LUDV systems.

In the known solution, the continuously adjustable directional control valve can be adjusted from a neutral or middle position in the direction of first positions, in which, for example, a hydraulic cylinder is retracted. When adjusting in the other direction is extended according to the hydraulic cylinder. Furthermore, the directional valve section can be adjusted by switching a float valve and simultaneously driving the valve spool in the direction "lower" in a floating position in which both consumer ports and the pressure port are connected to the tank port, so that, for example, a dozer blade of a bulldozer only due to its own weight on the floor rests. The disadvantage of this solution is that a separate float valve is needed.

In the DE 103 36 684 A1 a valve arrangement is shown in which the directional control valve is equipped with four positions (neutral position, lifting, lowering, floating position) of a valve spool. The term "position" is to be understood in each case a plurality of intermediate positions, in each of which an opening cross section which is effective in the sense of the functions neutral, lifting, lowering and floating position can be changed.

The DE 196 08 758 A1 discloses a solution in which a valve spool of the directional control valve in five positions (floating position, lowering, neutral position, vibration damping and extension) is adjustable, wherein in the position "vibration damping" in the direction of retraction effective annulus of the hydraulic cylinder is connected to the tank.

In none of these solutions, it is possible to adjust by adjusting the valve piston in addition to the functions of neutral position, extension, retraction and float position a rapid traverse function in which the displaced from the decreasing pressure chamber of the consumer, such as the annulus of a hydraulic cylinder pressure medium to the summed to other pressure chamber of the consumer supplied pressure medium flow. In order to realize such a rapid traverse in the known solutions, a separate valve means must be provided, is summed over the when switching to the function "rapid traverse" of the decreasing pressure chamber effluent pressure medium flow when bypassing the directional control valve to the pressure chamber to increasing pressure medium flow.

In contrast, the present invention seeks to provide a valve assembly in which both a rapid traverse and a floating position operation is made possible with low device complexity.

This object is achieved by a valve arrangement having the features of patent claim 1.

According to the invention, the valve arrangement has a continuously adjustable directional control valve with a valve slide guided in a valve bore, which can be adjusted from a spring-biased neutral position into a first direction, in which a pressure medium flow path between a consumer connection and the inlet connection and another consumer connection is opened with a drain connection. When adjusting the valve spool in the other direction, a pressure medium flow path between the other consumer port and the inlet port and the first-mentioned consumer port and the drain port is turned on in a first position accordingly. Preferably, this is a position "extension" in which flows from the piston rod side pressure chamber of a differential cylinder pressure fluid and the piston rod downstream pressure chamber pressure fluid flows.

According to the invention, in a further adjustment of the valve spool in the other direction, the pressure medium volume flow flowing from one consumer connection is summed to that pressure medium volume flow which flows to the other consumer connection - the directional control valve is then set in a rapid traverse position.

When the valve spool is moved beyond the rapid traverse position, the two consumer ports and the inlet port are connected to the drain port, so that the directional control valve is adjusted to the floating position (float).

Accordingly, the valve assembly according to the invention is designed with a directional control valve, the valve spool is adjustable in five positions, the floating position is preferably achieved after passing through the rapid traverse position.

According to the inventive concept, the control of these functions by adjusting the directional control valve, so that in contrast to the above-described prior art no additional, manually or by means of a pilot control to be switched control valves or the like must be provided.

The inventive concept is not only in so-called LUDV directional control valves, but also in LS-way valves, where the pressures before and after a metering orifice on a pressure compensator, and in directional control valves for throttle control (6-way valves with circulation channel) applicable.

In a preferred embodiment of the invention, in the rapid traverse position of the directional valve, a residual cross section in the pressure medium flow path between the one consumer connection and the outlet connection is opened.

In a concrete solution, the valve spool is designed with a control edge over which an opening cross-section in Druckmittelströmungspfad between the one consumer connection and the drain port is openable in adjusting in the other direction, wherein at least one control or extension groove is formed at a distance from this control edge on the valve spool , on the adjustment in the other direction, an opening cross-section between the one consumer port and the drain port is aufsteuerbar and on the further adjustment of the valve spool in the direction of the rapid traverse this opening cross section is züstuerbar again. In a further adjustment in the direction of the floating position of said opening cross section is then controlled via the control edge.

That About this extension groove, the pressure medium connection of a consumer connection is first opened with the drain connection. This pressure medium connection is then closed during further adjustment in the direction of the rapid traverse and then opened again when moving the valve spool in the direction of its end position for adjusting the floating function on the control edge.

The formation of the extension groove is particularly simple if this is designed as a circumferentially closed pocket on the outer circumference of the valve spool.

In a preferred embodiment of the invention, a longitudinal groove defining the aforementioned residual cross-section is hydraulically parallel to the extension groove, via which a residual cross-section in the pressure medium flow path from the one consumer connection to the outlet connection is opened when the valve slide is moved into the rapid traverse function. This longitudinal groove has a smaller effective cross-section than the extension groove.

In a variant of the invention, the valve spool is biased by a centering spring assembly in its neutral position. This centering spring assembly is designed with a pressure point spring, which comes into operative engagement with adjustment of the valve spool in the direction of the floating position, so that the Bedienpersoh can adjust this floating position only deliberately by overcoming a resistance.

Such Zentrierfederanordnung usually has two the valve spool in both directions acting centering springs, one of these centering springs is supported on the pressure point spring, which acts on a larger bias voltage is, so that the pressure point spring is initially not compressed during the adjustment of the valve spool.

In a structurally very simple running solution, the pressure point spring is tied to a stop pin, which is biased against a housing fixed stop and on the valve slide directly or indirectly when adjusting in the direction of the floating position runs, so that the further displacement is made possible only by overcoming the Druckpunktfedervorspannung ,

The structure of the valve assembly is particularly simple when a rapid traverse channel is provided which connects when adjusting the valve spool in its rapid traverse position bypassing the directional control valve connected to the one consumer connection return line with a supply line connected to the inlet port, wherein the rapid traverse channel in the direction of the consumer connection locking check valve is provided. When controlling the opening cross-section between the one consumer connection and the drain connection via the extension groove, the pressure medium can then flow away from the consumer via the rapid passage to the other pressure chamber, so that the consumer is moved at high speed.

The directional control valve of the valve arrangement is preferably designed as LUDV directional control valve with a directional and a speed part, the latter being formed by a metering orifice. This is followed by an individual pressure balance, which is acted upon by the pressure downstream of the metering orifice in the sense of reducing the pressure compensator opening cross-section of the highest load pressure of all driven consumers and in the sense of increasing the pressure compensator opening cross-section.

Other advantageous developments of the invention are the subject of further subclaims.

• Figur 1 ein Schaltschema einer Wegeventilsektion eines Mobilsteuerblocks mit einer erfindungsgemäßen Ventilanordnung;
• Figur 2 eine konkrete Ausführung der Wegeventilsektion aus Figur 1 in Schnittdarstellung;
• Figur 3 eine vergrößerte Darstellung eines Wegeventils der Wegeventilsektion aus Figur 2 und
• Figuren 4a bis 4d die Wegeventilsektion aus Figur 2 in den Stellungen Einfahren, Ausfahren, Eilgang und Floaten.

In the following, a preferred embodiment of the invention is explained in more detail with reference to schematic drawings. Show it:

• FIG. 1 a circuit diagram of a directional control valve section of a mobile control block with a valve assembly according to the invention;
• FIG. 2 a concrete version of the directional control valve section FIG. 1 in sectional view;
• FIG. 3 an enlarged view of a directional control valve of the directional valve section FIG. 2 and
• FIGS. 4a to 4d the directional valve section off FIG. 2 in the positions retract, extend, rapid traverse and float.

FIG. 1 shows a schematic diagram of a directional control valve section 1 of a mobile control block of a mobile work machine, such as a bulldozer. Such a mobile control block has a plurality of directional valve sections, via which the individual hydraulic consumers of the working machine can be controlled. In the following statements it is assumed that the in FIG. 1 illustrated directional control valve section 1 is used to control a lifting cylinder of a dozer blade to hold this either in a predetermined position, lower, raise, lower in rapid traverse or operate in a floating position. In the illustration according to FIG. 1 only the components of the directional control valve section 1 which are essential for understanding the invention are shown. Further details will be apparent from the figures described below. The basic structure of the directional control valve section 1 is known from the data sheet RE 64 284 / 06.00 described above, so that only the elements essential for understanding the invention are described here.

The directional valve section 1 has according to the circuit diagram in FIG. 1 a pressure port P, two working ports A, B, tank ports T1, T, a control port pst, and a control oil drain port L. The pressure port P is connected to a pump line 2 connected to the pressure port of a not-shown pump via an LS pump regulator is controlled depending on the highest load pressure of all driven consumers of the machine. This load pressure is tapped by the consumers via the LS connection and a load reporting channel 4 as well as a switching valve cascade, not shown. The amount of pump is adjusted by the pump controller so that the pump pressure is a predetermined pressure difference above the highest load pressure.

The two consumer ports A, B of the directional control valve section are via consumer lines 6, 8 with a bottom-side cylinder chamber 10 and a piston rod side Annular space 12 of a lifting cylinder 14 is connected. The direction of movement and the speed of the lifting cylinder 14 are adjusted via a continuously adjustable directional control valve 16. This is carried out with a speed part formed by a metering orifice 18 and a directional part 20, wherein via the metering orifice 18 the pressure medium volume flow to the consumer 14 and via the directional part 20, the flow direction to or from the pressure chambers 10, 12 is determined.

According to the directional control valve 16 is designed with five positions, wherein a valve slide described in more detail below is biased via a centering spring assembly 22 in a middle position (0) in which the aforementioned connections are shut off. The adjustment of the valve spool via pilot valves 24, 26, which are designed for example as pressure control valves, the pressure port to the control line pst, the tank port is connected to L and the control output to a control chamber on the valve spool.

When moving the valve spool to the right (in the direction in FIG. 1 ), the valve spool is first brought into the (A) marked positions "extending" in which the hydraulic cylinder 14 extends and the dozer blade is lowered. In a further adjustment of the valve spool in the direction to the right the marked with (E) positions are reached, in which the hydraulic cylinder 14 is operated at rapid traverse. In this rapid traverse function, the pressure medium volume flow from the decreasing annular space 12 to the cylinder chamber 10 via the metering orifice 18 supplied pressure medium volume flow is summed. By moving the valve spool in the direction of its (F) marked positions a floating position is set, in which the dozer blade rests on the ground due to its weight and may possibly follow bumps.

In an adjustment of the valve spool from the center position (0) out in the opposite direction, ie in FIG. 1 to the left, the valve spool positions marked (H) are set, in which the hydraulic cylinder 14 retracts and the dozer blade is raised.

Downstream of the metering orifice 18, in the exemplary embodiment illustrated, an individual pressure compensator 28 is arranged, which in the sense of reducing the flow cross section through the pressure in the load signaling channel 4, ie a control pressure corresponding to the highest load pressure and in the sense of an enlargement the flow cross-section is acted upon by the pressure downstream of the metering orifice 18.

In this case, the inlet connection of the individual pressure compensator 28 is connected via a pressure compensator duct 30 to a pressure connection P 'and the outlet connection of the pressure compensator via a duct 32 to a connection P "of the directional control valve 16. Arranged in the duct 32 is a load-holding valve 34 for the leakage-free support of the load Working port A of the directional control valve 16 is connected to the consumer port A and the consumer port B of the directional valve section 1 via a return passage 38 to the working port B of the directional control valve 16. Two tank ports T, T1 of the directional control valve 16 are respectively via flow channels 40, 42 with connected to the tank ports T, T1 of the directional valve section 1. The pressure port P of the directional control valve 16 is connected via an inlet channel 44 to the pressure port P of the directional control valve section 1.

According to FIG. 1 the return passage 38 is connected via a rapid traverse passage 46 to the section of the arc passage 32 located between the pressure port P "and the load-holding valve 34. In the rapid traverse passage 46, a check valve 48 is provided which opens in the direction of the pressure port P". When setting the valve spool in the position (E) "rapid traverse" displaced pressure medium from the annular space 12 via the rapid traverse channel 46 and the opening check valve 48 to port P "of the directional control valve 16 so that this outflowing pressure medium volume flow to that of the metering orifice 18th summed to the cylinder chamber 10 flowing pressure medium flow.

As further FIG. 1 is removable, in the case in which the pressure downstream of the metering orifice 18 is greater than the instantaneous pressure in the Lastmeldekanal 4, the pressure compensator slide in the illustration according to FIG. 1 shifted to its left end position, so that according to this downstream of the metering orifice 18 pending pressure in the load reporting channel 4 is reported.

FIG. 2 shows a concrete embodiment of the directional control valve section 1 according to FIG. 1 in section. As mentioned, this directional valve section 1 is part of a mobile control block formed of a plurality of such directional valve sections as well as an input member and an end plate. The directional valve section 1 has a valve disc 50, in which a valve spool 52 receiving valve bore 54 is formed. According to FIG. 2 and the enlarged view in FIG. 3 is the valve bore 54 seen from left to right to a tank chamber 56, a Forward chamber 58, a pressure compensator output chamber 60, a pressure compensator input chamber 62, an inlet chamber 64, another pressure compensator output chamber 66, a return chamber 68 and another tank chamber 70 extended. The terms "flow ...", "return ..." etc. are chosen only for ease of description - depending on the switching position of the directional control valve 16 may, for example, the return chamber 68 are also in the flow. The tank chamber 56 is as in FIG. 2 indicated via the drain passage 40 to the tank port T, the flow chamber 58 via the flow channel 36 to the consumer port A, the pressure compensator output chamber 60 via the rapid traverse channel 46 and the check valve 48 to the return chamber 68, wherein the pressure compensator output chamber 60 in the illustration FIG. 1 corresponds to the port P ". The return chamber 68 is above the in FIG. 2 indicated return channel 38 connected to the consumer port B. Finally, the tank chamber 70 is in fluid communication with the tank connection T1 via the outlet channel 42.

The construction of the valve spool 52 will be described with reference to the enlarged view in FIG FIG. 3 explained. Accordingly, the valve spool 52 is divided by a plurality of mutually spaced annular grooves in two Endbunde 72, 74, a tank control collar 76, a Zulaufbund 78, the opening cross section of the metering orifice 18 determining control collar 80, an intermediate collar 82 and a Zulaufbund 84. At Tanksteuerbund 76 is a Tanksteuerkante 85, the Zulaufbund 78 an inlet control edge 86, the control collar 80 each end face a Meßblendensteuerkante 88, 90, the Zulaufbund 84 a Zulaufsteuerkante 92 and formed on the opposite annular end face of the Endbundes 74 a floating position control edge 94.

The aforementioned control edges 85, 86, 88, 90 92, 94 are each carried out in a known manner with control grooves or control windows 96, of which in FIG. 3 by way of example only one of the floating position control edge 94 associated control window is provided with a reference numeral.

At a distance from the control windows 96 of the floating position control edge 94 a parallel to the directional control valve axis 98 extending extension 100 is formed on the outer circumference of the valve spool 52, whose in FIG. 3 right end portion in the neutral position (0) of the annular web between the control chambers 68, 70 is covered. The in FIG. 3 left end portion of the Ausfahrnut 100 is not connected to the adjacent control windows 96 - as a result, this Ausfahrnut 100 is formed as a circumferentially closed pocket.

In the parallel distance to the Ausfahrnut 100 a longitudinal groove 102 is formed on the outer periphery of the Endbundes 74, the width (seen in the circumferential direction) and length (seen in the axial direction) is less than that of the Ausfahrnut 100. This longitudinal groove 102 opens as shown in FIG FIG. 3 in the lower control window 96 of the floating position control edge 94. In the illustrated neutral position (0), this longitudinal groove 102 is open to the return chamber 68 out. According to FIG. 2 the return chamber 68 is connected to the pressure compensator output chamber 60 via the rapid passage 46, which is designed as an angular bore, and the check valve 48 inserted therein, the check valve opening to the pressure compensator output chamber 60.

In the in the FIGS. 1 to 3 shown neutral position (0) of the valve spool 52 are in FIG. 1 visible ports P, A, B, P ', P ", T, T1 of the directional control valve 16. Accordingly, in the illustration according to FIG FIG. 3 via the tank control edge 85, the pressure medium connection between the chambers 56, 58, via the inlet control edge 86, the pressure medium connection between the chambers 58, 60, via the Meßblendensteuerkanten 88, 90, the pressure medium connection between the chambers 64 and 62, via the inlet control edge 92, the pressure medium connection between the chambers 66, 68 and via the Ausfahrnut 100, the pressure medium connection between the chambers 70, 68 shut off, so that the consumer is clamped in its illustrated position.

In the FIG. 1 shown individual pressure compensator 28 is inserted into a direction perpendicular to the directional valve axis 98 extending pressure compensator bore 104, wherein a pressure compensator piston 106 frontally, ie in the illustration according to FIG. 2 from bottom to top with the pressure in the pressure compensator input chamber 62 and the rear is acted upon by the tapped from the load detection channel 4 highest load pressure, which is present in a rear annular space 108 of the pressure compensator bore 104. When the pressure compensator cross section is fully open (pressure compensator piston 106 is displaced upward in the illustration), the pressure in the pressure compensator input chamber 62 is reported via internal bores 110 of the pressure compensator piston 106 into the annular space 108 and thus into the load reporting channel 4.

In the FIG. 1 indicated centering spring assembly 22 is according to FIG. 2 received in spring housings 112, 114, in which the two end portions of the valve spool 52 dip. In the in FIG. 2 left spring housing 112 is a centering spring 116th supported, which acts via a spring bushing 118 on the adjacent end face of the valve spool 52, wherein the stroke of the spring bushing 118 to the right in FIG. 2 is limited by a housing-fixed stop 120. The stroke of the valve spool 52 to the left in FIG. 2 is limited by a stroke limiter 122.

In the right spring housing 112, a centering spring 124 is also supported, which acts via a spring plate 126 on an annular end face of the valve spool 52, which dips into the centering spring 124 with a radially set back end portion 128.

Approximately in the extension of the centering spring 124, a pressure point spring 130 is provided in the spring housing 112, which is clamped to a stop pin 132 between a stop ring 134 and a support ring 136 of the stop pin 132. The two rings 134, 136 are supported in opposite directions on the stop pin 132. The centering spring 124 is supported on the support ring 136, wherein the spring bias of the pressure point spring 130 is greater than that of the centering spring 124. In the illustrated neutral position of the stop pin 132 is biased by the centering spring 124 with its stop ring 134 against a spring housing side stop 138, wherein the spring plate 126 in turn is supported on a housing-side stop. In the illustrated neutral position (0) is an in FIG. 2 left end face 142 of the stop pin 132 arranged at an axial distance from the adjacent end face of the end portion 128 of the valve spool 52. Upon movement of the valve spool to the right, the end portion 128 runs on the end face 142 of the stop pin 132, which is then taken along with shortening of the pressure point spring and then runs onto an end stop 144 of the spring housing 112.

At the in FIG. 2 illustrated directional control valve section is also the pressure control valve 24 to control the directional control valve recognizable.

The function of the above-described directional control valve section 1 is based on FIG. 4 in which the positions (A), (E), (F) and (H) according to FIG. 1 are shown.

In the illustration according to FIG. 4a the valve spool 52 is displaced by setting a suitable control pressure via the pressure control valve 26 to the left in its (H) marked positions in which on the Meßblendensteuerkante 90 a pressure medium connection between the inlet chamber 64 and the pressure compensator input chamber 62 is opened, this aufgesteuerte Cross section forms the flow cross section of the metering orifice 18. The pressure medium can then flow via the individual pressure compensator 28 and the arc channel 32 to the pressure compensator output chamber 66 and from there via the controlled by the floating position control edge 94 cross section in the return chamber 68, from there to the consumer port B and from there via the consumer line 8 to the annulus 12th the lifting cylinder 14 flows. The pressure medium displaced from the cylinder chamber 10 which is smaller in size occurs via the consumer line 6, the consumer port A, which now practically acts as a return channel, into the flow chamber 58, which is connected to the tank chamber 56 via the tank control edge 85, so that the pressure medium then flows through the drain passage 40 and the tank port T of the directional valve section 1 to the tank. That is, when adjusting the valve spool 52 in the positions (H) of the lifting cylinder 14 is retracted and raised accordingly the dozer blade.

To lower the dozer blade of the directional control valve 52 is FIG. 4b by setting a suitable control pressure via the pilot valve 24 from the illustration in accordance with FIGS. 1 to 3 shifted to the right, in which case the opening cross-section of the metering orifice 18 between the inlet chamber 64 and the pressure compensator inlet chamber 62 is determined via the metering orifice control edge 88. The pressure medium flowing away from the individual pressure compensator 28 flows via the arc channel 32 into the pressure compensator output chamber 60 and from there through the cross section controlled via the inlet control edge 86 into the inlet chamber 58 and then via the flow channel 36, the consumer port A and the consumer line 6 into the cylinder chamber 10. The displaced from the annular space 12 pressure fluid flows through the consumer port B, the return channel 38, the return chamber 68 and then opened by the Ausfahrnut 100 cross-section into the tank chamber 70 and from there to the tank. Parallel to the opening cross section determined by the extension groove 100, an opening cross section between the two chambers 68, 70 is also opened via the small longitudinal groove 102.

As a result, in the positions (A) of the valve spool, the lift cylinder 14 is extended to lower the dozer blade.

In a further shift of the valve spool 52 to the right according to Figure 4c in the in FIG. 1 with (E) marked rapid traverse positions arrives in the Figure 4c left end portion of the Ausfahrnut 100 in register with the annular web between the two chambers 68, 70, so that the pressure medium connection is shut off via the Ausfahrnut 100. There remains only the comparatively small Residual cross section over the longitudinal groove 102, which is further open both to the return chamber 68 and to the tank chamber 70 out. The floating position control edge 94 is also ineffective in this position. Over the longitudinal groove 102 thus flows a certain amount of pressure medium to the tank - this partial flow is lost to the actual rapid traverse volume flow. The main part of the pressure medium volume flow flows from the return chamber 68 via the rapid traverse channel 46 and the then opening non-return valve 48 in the pressure compensator output chamber 60 and is summed there to the pressure medium flow rate from the inlet chamber 64 via the controlled by the orifice control edge 88 orifice plate cross section to the individual pressure compensator 28 and this flows via the arc channel 32 in the pressure compensator output chamber 60. This comparatively large rapid traverse volume flow is then guided via the cross section opened by the feed control edge 86, the feed chamber 58 and the consumer port A to the cylinder chamber 10 of the lifting cylinder 14.

By forming the control edge 86 with control windows with respect to a full flow cross-section reduced flow cross-section is achieved that can build up in the annulus 12 such a pressure that the load does not fall uncontrollably, but the speed of the load is determined by the funded by the pump pressure medium , Via the control edge 86, the pressure decreases from the high pressure in the annular space 12 to the lower pressure in the cylinder space 10.

The non-usable during rapid traverse, flowing through the longitudinal groove 102 pressure medium quantity is dependent on the pressure in the cylinder chamber 12 of the lifting cylinder fourteenth

As further in Figure 4c is shown in this position (E), the end portion 128 of the directional control valve piston on the end face 142 of the stop pin 132, wherein this adjustment of the valve spool 52 initially takes place only against the force of the centering spring 124 - the pressure point spring 130 has not then shortened. Because it is biased to a greater force than it is exerted by the spring 124 in the position (E).

The further adjustment of the valve spool 52 in the direction of the floating position (F) is then possible only against the force of the pressure point spring 130. This floating position (F) is in FIG. 4d shown. In this position, the connection between the inlet chamber 64 and the pressure compensator input chamber 62 through the in FIG. 4d shut off the right end portion of the inlet collar 78. The inlet chamber 64 is however, throttled across orifice plate control edge 90 is connected to pressure compensator output chamber 66, which in turn is open to return chamber 68. The latter is connected via the floating position control edge 94 with the tank chamber 70, so that the pressure medium can flow from the inlet chamber 64 to the tank. Accordingly, the consumer port B via the return chamber 68, the floating position control edge 94 and the tank chamber 70 is connected to the tank. The other consumer port A is connected via the flow chamber 58 and thus opened via the annular groove between the coils 72, 76 connection to the tank chamber 56 also connected to the tank, so that the dozer blade in this floating position unevenness on the ground or can level due to its weight , As stated above, the floating position (F) can be achieved only by overcoming the bias of the pressure point spring 130, so that the operator has a clear feedback when the float position (F) is reached. When shortening the pressure point spring 130, the stop pin 132 is taken from the end portion 128 of the valve spool 52 until the in Figure 4c right end portion of the stop pin 132 runs onto the end stop 144. Another adjustment to the right is not possible.

In the above solution, the valve spool 52 is adjustable in five positions to extend the functions lift cylinder retract, rapid traverse of the lift cylinder and floating position of the lift cylinder and to allow adjustment to a neutral position.

Disclosed is a valve arrangement with a continuously adjustable directional valve, the valve spool is adjustable in the direction of five positions to drive a consumer in two directions, to move in rapid traverse, operate in floating position or shut off the pressure medium connection to the consumer (neutral position).

Claims (14)

1. Valve arrangement for actuating a hydraulic consumer (14), having a directional control valve (16) which has a valve slide (52) which is guided in a valve bore and is adjustable from a neutral position (0) in order to perform a pressure medium connection between two consumer connections (A, B) and an inflow connection (P) or an outflow connection (T, T1), into which neutral position (0) the valve slide (52) is prestressed by means of a centring spring arrangement (22), wherein the valve slide (52) can be adjusted in the direction of at least three further positions (H, A, F), wherein in the case of adjustment from the neutral position (0) in a direction into a first position (H) a pressure medium flow path between a consumer connection (B) and the inflow connection (P) as well as between the other consumer connection (A) to the outflow connection (T, T1) can be opened, and
   in the case of an adjustment from the neutral position (0) in the other direction into a second position (A) a pressure medium flow path between the other consumer connection (A) and the inflow connection (P) and between the one consumer connection (B) and the outflow connection (T, T1) can be initially correspondingly opened, and
   in the case of a further adjustment in the other direction into a floating position (F) the two consumer connections (A, B) are connected to the outflow connection (T, T1),
   characterized in that in the case of an adjustment from the neutral position (0) in the other direction the valve slide (52) can be moved into a rapid-motion position (E) in which the pressure medium volume flow flowing away from the consumer (14) via the one consumer connection (B) flows is summed to form the pressure medium volume flow which flows from the inflow connection (P) to the other consumer connection (A).
2. Valve arrangement according to Patent Claim 1, wherein the rapid-motion position (E) is between the second position (A) and the floating position (F).
3. Valve arrangement according to Patent Claim 1 or 2, wherein in the rapid-motion position (E) a residual cross section in the pressure medium flow path between the one consumer connection (B) and the outflow connection (T, T1) is opened.
4. Control arrangement according to one of the preceding patent claims, wherein the valve slide (52) is opened with a control edge (94) via which in the case of adjustment in the other direction an opening cross section in the pressure medium flow path between the one consumer connection (B) and the outflow connection (T, T1) can be opened, wherein an extension groove (100), via which an opening cross section between the one consumer (B) and the outflow connection (T, T1) can be opened in the case of adjustment of the valve slide (52) in the direction of the second position (A) and via which this opening cross section can be closed again in the case of further adjustment in the direction of the rapid motion (E), is formed on the valve slide at a distance from this control edge (94), wherein in the case of further adjustment the opening cross section in the pressure medium flow path between the one consumer connection (B) and the outflow connection (T, T1) can be opened by means of the first-mentioned control edge (94).
5. Control arrangement according to Patent Claim 4, wherein in the case of adjustment of the valve slide (1) into the first position (H) an opening cross section between the inflow connection (P) and the one consumer connection (B) can be opened by means of the control edge (94).
6. Valve arrangement according to Patent Claim 4 or 5, wherein the extension groove (100) is a pocket which is closed circumferentially in the external circumference of the valve slide.
7. Valve arrangement according to Patent Claim 3 and one of Patent Claims 4 to 6, wherein a longitudinal groove (102) which determines the residual cross section is formed in parallel with the extension groove (100).
8. Valve arrangement according to Patent Claim 6, wherein the longitudinal groove (102) opens in a control window (96) of the control edge (94).
9. Valve arrangement according to Patent Claim 7 or 8, wherein the effective flow cross section of the longitudinal groove (102) is smaller than that of the extension groove (100).
10. Valve arrangement according to one of the preceding patent claims, wherein the centring spring arrangement (22) has two centring springs (116, 124) which are each effective in an adjustment direction, wherein a pressure point spring (130) is assigned to the centring spring (124) which is effective counter to the other direction, said pressure point spring (130) moving into effective engagement when the valve slide (52) is moved into the floating position (F).
11. Valve arrangement according to Patent Claim 9, wherein the centring spring (124) is supported on the pressure point spring (130) to which a larger prestress is applied than to the centring spring (124).
12. Valve arrangement according to Patent Claim 11, wherein the pressure point spring (130) is tensioned on a stop bolt (132) which is mounted in an axially displaceable fashion and onto which the valve slide runs up indirectly or directly in the case of adjustment in the direction of the floating position (F).
13. Valve arrangement according to one of the preceding patent claims, having a rapid-motion duct (46), via which in the case of adjustment of the valve slide (52) into the rapid-motion position (E) a return flow duct (38) which is connected to the one consumer connection (B) is connected to an inflow-side inflow duct (32) while bypassing the directional control valve (16), wherein in the rapid-motion duct (46) a non-return valve (48) which blocks in the direction of the return flow duct (38) is provided.
14. Valve arrangement according to one of the preceding patent claims, wherein the directional control valve (16) has a directional part (20) and a speed part which is formed by a metering orifice (18), wherein an individual pressure balance (28) is connected downstream of the metering orifice (18), a control pressure which corresponds to the maximum load pressure of all the consumers being applied to said individual pressure balance (28) with the effect of reducing the pressure balance opening cross section, and a pressure being applied to said individual pressure balance (28) downstream of the metering orifice (18) with the effect of increasing the opening cross section.

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