EP1108895A1 - Hydraulic valve to control a consumer independent of the load - Google Patents

Abstract

The valve has a supply connector, a drain connector and two user connectors. An axially sliding control slide (12) in a slide bore of a valve casing controls the fluid connections. There are a blocking function position, two direction function positions and a float function position. The float function position is between the blocking function and one direction function position. In a blocking function position, the user connectors are blocked from the supply and drain connectors. In a float function position, the supply connector is blocked and the user connectors are connected with the drain connector. In two direction function positions, one user connector is connected with the supply connector and the other is connected to the drain connector. The float function position is between the blocking function and one direction function position.

Description

The invention is based on a hydraulic directional valve that is independent of the load Control of a hydraulic consumer, especially a hydraulic one Consumer of a mobile machine, in terms of direction and speed and serves the features from the preamble of the claim 1 has.

It is known to open the wheel motors of a hydraulic travel drive operate hydraulic circuit and the pressure medium paths between the Wheel motors, a hydraulic pump and a tank with the help of a directional valve Taxes. In a hydraulic travel drive known from DE-OS 1 901 762 the directional control valve is one with four connections, namely with one the inlet connection connected to the hydraulic pump, with one connected to the tank Drain connection and with two consumer connections, of which lines lead to the two sides of the wheel motors, and with three positions. In a The two consumer connections are in the middle position of the directional control valve and fluidly connected to the tank, the wheel motors are, so to speak switched off and can e.g. crank when towing the working machine. So in the middle position of the directional control valve you have a kind of swimming operation the wheel motors, which is why the corresponding position of a directional valve in the following is also referred to as a swimming function position. In the two side Positions of the directional control valve is the one connection of the wheel motors with the Hydraulic pump and the other connection connected to the tank. Depending on The wheel motors rotate which side position the directional valve assumes in a first direction or in the opposite, second direction.

A hydraulic travel drive is also known from DE-GM 92 046 646, the hydraulic wheel motors operated in open hydraulic circuits become. A proportional directional control valve is used to control two wheel motors on a first axis used, which in turn has four connections, namely an inlet connection, has a drain connection and two consumer connections, in whose middle position now blocked all four connections against each other are. This middle position is therefore called the locking function position. In her can neither flow pressure medium to the two wheel motors mentioned Flow pressure fluid away from the two wheel motors. In the middle position of the directional valve can the mobile work machine through the wheel motors on the Be held if the machine is on level ground or only has to be stopped briefly. Incidentally, is usually a mobile Working machine with a hydraulic travel drive with a parking brake equipped. The two wheel motors are not swimming here possible.

Hydraulic directional control valves are known which assume a total of four positions can. It is expressly pointed out here that with Position not a very specific position of the control spool, but stroke ranges of the control spool are meant, which are characterized by the hydraulic connections the connections of the valve from each other. For example, out DE 35 08 340 A1 a directional control valve with four switching positions known within a throttle control is used. In a spring-centered neutral position of the control spool, the two consumer connections are against each other as well as blocked against the inlet connection and the outlet connection. The neutral position has a locking function. From this blocking function position Control spools are moved in one direction to the first consumer connection with the tank connection and the second consumer connection with to connect the inlet connection. If the control spool moves in the other direction, this first comes into a position in which the first consumer connection with the inlet connection and the second consumer connection is connected to the drain connection. Beyond this position, the Control spool in a fourth position, in which the two consumer connections are connected to each other and to the drain connection. This fourth switching position is therefore a floating function position. It lies from seen from the spring-centered locking function position, beyond the one directional function position.

There are also hydraulic directional valves for load-independent, so-called Load sensing control of a hydraulic consumer with four switch positions known. These directional control valves have a spring-centered neutral position, in which in turn two consumer connections against each other and against the inlet connection and the tank connection are blocked. On this locking function position of the valve follows in both directions of actuation of the control spool immediately a directional function position in which the one consumer connection with the inlet connection and the other consumer connection with the Tank connection is connected. Beyond one directional function position finally there is a floating function position in which both consumer connections are connected to the tank connection. Here, too, in order to avoid the Lock function position to get into the swimming function position, a directional function position be run over. This is not a further disadvantage if the directional valve is used to e.g. the shovel of a wheel loader or the Floating fork of a forklift. Because before swimming the equipment has to be dumped on the floor here anyway if it is not already on the floor. However, in other applications uncontrolled movements by crossing a directional function position of the controlled hydraulic consumer take place, which can be dangerous can.

The well-known hydraulic directional valve for load-independent control of a hydraulic consumer is designed to operate in a special way load-independent control, namely a control with a load-independent Flow distribution of the amount of pressure medium to be used. Flows here the pressure medium first by moving the spool in her Flow cross section changeable orifice, then via one of the orifice downstream pressure compensator and only then via the direction control. The pressure compensator is determined in the opening direction by the pressure after the metering orifice and in the closing direction from the highest load pressure and from a weak one Pressurized spring applied.

From the data sheet RD 64 282 / 01.97 from the applicant is a hydraulic directional valve known for load-independent control of a hydraulic consumer, in which the pressure compensator is connected upstream of the metering orifice. Here is the Pressure compensator in the closing direction from the pressure upstream of the metering orifice in Closing direction and the individual load pressure of the respective consumer and by a spring, which determines the pressure difference across the metering orifice, in Closing direction applied.

The invention has for its object to provide a hydraulic directional valve load-independent control of a hydraulic consumer, which features from the preamble of claim 1, to further develop that certain hydraulic consumers in different operating modes can be controlled without dangerous movements occurring. This task is performed on a hydraulic directional valve with the features the preamble of claim 1 according to the invention solved in that according to the characterizing part of claim 1, the swimming function position of the control spool between the locking function position and one Directional function position. A hydraulic directional valve according to the invention is particularly suitable for use within a hydraulic travel drive, for controlling a bogie axis and for controlling hydraulic ones Rotary drives suitable for cranes. A bogie axis is an axis that carries two wheels arranged one behind the other in the longitudinal direction of the vehicle and is pivotable about itself.

Advantageous configurations of a directional valve according to the invention can be found in the subclaims.

Bogie axes are used especially in forestry machines. In the forest the wheels swing freely, i.e. the bogie axis can swim when driven becomes. When you start working with the forest machine crane, on the other hand, all pivot points should be locked so that the machine has a fixed Stand. In difficult terrain, e.g. however, when driving over a pit a bow wheel must be raised and held up. As a result, it is convenient if with a directional control valve that is used to control a bogie axis is, according to claim 4 predetermined by a spring arrangement Rest position of the control spool is the locking function position. The device is then firmly supported and you can work with the crane. As soon as one with the If the machine wants to drive off, the control spool is in from the rest position moved a floating function position in which the consumer connections with connected to the tank and the bogie axis can swing freely. Do you want one Raise the wheel so that the control spool is brought into a directional function position. The control for the bogie axis is also intrinsically safe. In the event of a failure due to the spring centering, the control slide reaches the locking function position, in which the bogie axis is blocked for movement and the stability of the Vehicle is guaranteed. Only the driving comfort deteriorates.

Advantageously, closes in a hydraulic directional valve according to claim 4 to the locking function position in both opposite directions towards a swimming function position.

With a travel drive, it is cheaper if the consumer connections and so that the wheel motors are relieved to the tank when the directional control valve is at rest become. The machine can then still run with the failed motors or be towed away. Accordingly, it is when using a Hydraulic directional control valve according to the invention within a travel drive favorable if the rest position that the control slide due to a spring arrangement takes, according to claim 2, the swimming function position. To with to drive a machine equipped with such a drive, the control slide from the floating function position over the locking function position brought into a directional function position. In the blocking function position are both consumer connections closed, so that in the further Moving the control spool the machine normally with one to deflect proportional speed of the spool can be driven. At the When the machine stops, the control spool returns to the locking function position. The wheel motors controlled with the directional control valve and thus the corresponding ones The wheels stop. If a larger holding torque is required the brake is still applied.

According to claim 3, the swimming function position follows as the rest position after each actuation direction of the control slide towards a locking function position. Here, too, the swimming function position is between a blocking function position and a directional function position if also not immediately next to the latter. However, it is also possible to use only one Side of the swimming function position to have a locking function position. In In this asymmetrical case, a larger part of the Slider strokes can be used to control the speed. At a Driving this can be of particular advantage since you usually drive forward drives faster than reverse and then in for speed control Forward stroke a large stroke is available.

When the direction of travel is reversed, the control spool moves at high speed driven over the spring-centered floating function position, so that this position is hardly noticeable in practice.

It is advantageous if according to claim 6 in a floating function position of the control spool throttled the two consumer connections with the Drain connection are fluidly connected. The advantage is that a throttled Connection can be designed so that the leakage in the blocking function position is only slightly increased. On the other hand, at least one hydraulic travel drive, for controlling a bogie axis or for rotary drives on cranes, the volume flows that are in the floating function position of the Control spool flow so low that the throttling prevents the hydraulic from floating or the hydraulic consumer is not impaired.

Advantageous structural designs of a directional valve according to the invention can be found in claims 7 to 14.

The control slide is slidable in a sliding hole, around which usually spaced apart control chambers run around, the fluidic Connections with each other can be controlled via the control slide. Usually there are two control chambers that are connected to the consumer connections are connected and are called consumer chambers in the following. As well there are usually two drainage chambers, which are the consumer chambers are adjacent and connected to the drain port of the directional valve are. So to fluid a consumer connection with the drain connection To connect, the spool must have a flow cross-section between one Open the consumer chamber and the neighboring drain chamber. According to claim 8 this is done in a particularly preferred manner in that the Control spool a radially open and axially extending in its longitudinal direction has connection groove limited on both sides, the length of which is greater than the clear distance between the consumer chamber and the drain chamber. This connecting groove can be easily inserted into a slide collar of the control slide. Depending on the cross-section of the connecting groove, the connection between the consumer chamber and drain chamber more or less throttled. The connection is interrupted as soon as one or the other end of the connecting groove from the web between the consumer chamber and the drain chamber of the valve housing is covered. A locking function position between one Floating function position and a directional function position is obtained one advantageously by means of a configuration according to claim 9. In a training according to claim 10, the swimming function position between the blocking function position and a directional function position.

For precise speed control of a hydraulic consumer it is advantageous if an outlet cross-section between the one consumer chamber and a drainage chamber can be opened from zero, if at the transition from a swimming function position to the neighboring directional function position the fluidic connection existing in the floating function position between the consumer chamber and the drain chamber initially is interrupted once. How this can be achieved cheaply is in claim 11 specified.

Through the training according to claims 13 and 14 you get on Control spool with respect to both a radial plane and a axial plane a symmetrical arrangement of the connecting grooves.

According to claim 15, the directional control valve is preferably electrical or electro-hydraulic actuatable. In this case, the electrical pilot control given control signals electrically processed and accordingly modified to be given to the electrical actuators. For example it is possible, the spool in an outside of the rest position Locking function position or swimming function position with a very specific one Hold as long as the electrical pilot signal within a certain Range.

Two embodiments of a hydraulic directional valve according to the invention are in the drawings as circuit diagrams and in their structural design shown. On the basis of the figures of these drawings, the invention will now be closer explained.

Show it

Figure 1

the circuit diagram of the first embodiment, the control slide a swimming function position as a middle position and after each Direction of actuation a locking function and a directional function position Has,

Figure 2

the circuit diagram of the second embodiment, the control slide a locking function position as the middle position and on both sides of this middle position one swimming function position and one directional function position Has,

Figure 3

2 shows a longitudinal section through the second exemplary embodiment,

Figure 4

a section along the line IV-IV of Figure 3 and

Figure 5

a partial longitudinal section in the area of the slide bore and the control slide of the first embodiment.

The two proportionally adjustable directional valves shown are intended to around together with a pressure compensator upstream of a metering orifice to control a hydraulic consumer independent of load pressure. Directional control valve and pressure compensator, as can be seen particularly clearly from FIG. 3, form one Directional valve disc combined with a valve housing 10. For the way functions and the function of the metering orifice passes through the valve housing 10 a slide bore 11 through which a control slide 12 is axially movable is. The length of the control slide 12 coincides with the length of the slide bore 11 from one end face 13 to the other end face 14 of the valve housing 10 match. The slide bore 11 is axially spaced from five Control chambers surround the inflow of pressure medium to and the outflow pressure medium from a hydraulic consumer, e.g. a wheel motor, one a cylinder actuating a bogie axis or a rotary drive on one Crane, serve and their fluidic connections to each other by the spool 12 can be controlled. The central control chamber 15 of the five control chambers is the inlet chamber. This flows pressure medium through a channel 16 from the pressure compensator 17. Is located on both sides of the inlet chamber a consumer chamber 18 or 19, each with one at the end of one Consumer channel lying consumer connection 20 or 21 of the valve disc connected is. An outlet chamber follows each consumer chamber 18 or 19 22 and 23, respectively, which become one of two passing through the valve housing 10 Tank channels 24 is open.

The control slide 12 takes due to two centering springs 34 which in the End faces 13 and 14 of the valve housing 10 attached and the slide hole 11 outwardly closing covers 35 are accommodated, a middle position a, from which it can be constantly adjusted in opposite directions can. At maximum stroke, it strikes an adjustable stroke limiter 36 at. The control slide 12 has a slide neck 37 which in the Center position to the inlet chamber 15 is centered. The two tax authorities 38 and 39 on both sides of the slider neck 37 are so long that in the middle position of the Control spool one end face at a distance from the inlet chamber 15 and its other end face is in the drain chamber 22 or 23. Both piston collars have control grooves 40 and 41 on one end face and on the other other end face are axially open. In the middle position of the control spool 12 are the control grooves 40 and 41 from those located between the control chambers Housing bars covered so that no open fluidic via the control grooves There is a connection between the individual control chambers. After a short Another neck follows the control collar 39, another slide collar 42, the seals the spring chamber in a cover 35 against the drain chamber 23.

The distance between the drain chamber 22 and the end face 13 of the valve housing 10 is greater than the distance between the drain chamber 23 and the End face 14. There are between the drain chamber 22 and the end face 13 in the slide bore 11 three axially spaced chambers 43, 44 and 45, the middle of these three chambers being referred to as load reporting chamber 44 be. The entrance to each of the two chambers 43 and 45 is one Pressure relief valve 46 connected. Each of these two pressure relief valves is installed in a bore of the valve housing 10. In the in the FIGS. 3 and 5 of the central position of the control slide 12 shown, a slide collar is sufficient 47 from the end face 13 of the valve housing 10 into the area of the housing web between the chamber 45 and the drain chamber 22. In this Slider collar is screwed into a flat annular groove 49, via that shown in FIG Middle position of the control slide 12 all three chambers 43, 44 and 45 with each other are connected. In addition, the slide collar 47 has on the drain chamber 22 facing outer edge a notch 50 through which the chamber 45 and the drain chamber 32 with a small opening cross-section to each other are open when the control slide 12 is in its central position. First after a certain way of the spool out of its central position in one direction this fluidic connection between the drain chamber 22 and the chamber 45 and thus the chamber 44 closed. A further notch 51 has the same function when the control slide is adjusted 12 in the opposite direction. Only after a certain stroke becomes the fluidic connection between the chamber 44 via the chamber 45 Drain chamber 22 interrupted. The control slide 12 from its central position moved out by the certain stroke, the load reporting chamber 44 each according to the direction of movement of the control slide from the chamber 43 or from the Chamber 45 separated.

From the outer end face on the slide collar 42 runs through the control slide 12 a closed blind bore 55 up to the area of the annular groove 49. The blind bore is crossed by two transverse bores 56, one of which one each in the piston collar 38 or in the piston collar 39 of the control slide 12 is located at such a point that it is in the central position of the spool is covered by the wall of the slide bore 11. With a movement of the control slide 12 from the central position in one direction a transverse bore 56 to the consumer chamber 18 and when the Control spool in the other direction, the other transverse bore 56 to the consumer chamber 19 open. Via a in a transverse bore 57 in the area of Annular groove 49 is introduced into the control slide 12 up to the blind bore 55 Nozzle 58 is the blind bore 55 with the load reporting chamber 44 fluid connected.

The pressure compensator 17 has a control piston 65, which is in a slide bore 11 running in parallel and from the end face 14 into the valve housing 10 introduced blind hole 66 is inserted. In the blind bore 66 are axial spaced apart from each other an inlet chamber 67 which is perpendicular to the one Cut plane according to Figures 3 and 5 extending inlet bore 68 cut is formed, and a drain chamber 69, which via the channel 16 with the inlet chamber 15 of the slide bore 11 is connected. The control piston 65 has an opening cross section with a control edge 70 which is provided with fine control grooves to influence between the two chambers 67 and 69. in the In order to enlarge this opening cross section, the control piston of the load pressure existing in the load reporting chamber 44 with the directional valve controlled hydraulic consumer and acted upon by a compression spring 71, whose pressure equivalent is in the range between 10 and 20 bar. For the purpose of a reduction in the flow cross section between the two chambers 67 and 69 becomes the control piston from the pressure in the outlet chamber 69 and in the inlet chamber 15 applied to the slide bore 11.

As already mentioned, the control grooves are in the central position of the control slide 12 40 and 41 covered on the tax authorities 38 and 39, so that none of them there is a fluidic connection between the control chambers. Becomes a spool 12 moved far enough out of its middle position, so the Control grooves 40 on a control collar 38 a flow cross section between the Inlet chamber 15 and the corresponding consumer chamber 38 and 39 opened, the opening cross-section changes with increasing stroke of the control slide enlarged. About the tax grooves 41 on the other tax authority 39, the rest are larger in cross section than the control grooves 40, a flow cross section between the other consumer chamber and the corresponding drain chamber 22 or 23 open. Due to the flow cross section at the control grooves 40 of the one control collar, a metering orifice is implemented, via which one Pressure difference drops, which is kept constant by the pressure compensator 17 and which corresponds to the force of the compression spring 71. The hydraulic consumer the amount of pressure medium flowing in depends only on the stroke of the spool 12, but not from the load or pump pressure.

A spring chamber is used to move the control slide 12 out of its central position acted upon by a control pressure in one of the two covers 35. To serve two electromagnetically actuated pilot valves 72 and 73, which in the a cover 35 are used and the proportionally adjustable pressure reducing valves are trained. At a maximum control pressure of e.g. 30 bar the two pilot valves 72 and 73 control oil is limited via a channel 74 in Valve housing 10 supplied, while control oil flow through a channel 75 can.

From the description so far it is clear that the two versions shown of directional control valves according to the invention on both sides of the spring-centered central position Have working positions in which a consumer connection Via the pressure compensator and the orifice plate pressure medium from a pressure medium source can flow, while from the other consumer port pressure medium in the Tank channel 24 and from there via a drain connection of the directional valve to one Tank flows. In both versions, the control slide 12 is in the control collars 38 and 39 with additional connecting grooves 80, 81 or 82 provided in The longitudinal direction of the control slide 12 run, limited at both axial ends are and only a small depth in the radial direction of the spool Have 12. In the embodiment according to Figures 2 and 4 are in each tax authority 38 and 39 two diametrically opposite connecting grooves 80 and two further connecting grooves offset from the connecting grooves 80 by 90 degrees 81 available. The connecting grooves 80 are such that in the central position of the control slide 12 those on the control collar 38 to the consumer chamber 18 and those on the tax office 39 to the consumer chamber 19 open are. The control grooves 80 are closed to the drain chamber 22 or 23. The Control grooves 81 are closer to the drain chambers 22 and 23 facing End faces of the tax authorities and are in the middle position shown Control spool 12 of the embodiment according to Figures 3 and 4 to the drain chamber 22 and 23 open and closed against the consumer chambers 18 and 19. Thus, in the shown central position of the control slide 12 3 and 4 also via the connecting grooves 80 and 81 no fluidic connection between a consumer chamber 18 or 19 and a drain chamber 22 or 23. All control chambers are shut off from each other. The central position of the control slide 12 is therefore the blocking function position.

The connecting grooves 80 and 81 of the embodiment according to Figures 3 and 4 and the connecting grooves 82 of the embodiment of Figure 5 are in the longitudinal direction of the Control spool 12 longer than the clear distance between a consumer chamber and the neighboring drain chamber.

It is now assumed that the control slide 12 according to the design FIGS. 3 and 4 by pressurizing the spring chamber in the cover 35 without the pilot valves being moved to the left. After a relatively short stroke Then the connecting grooves 80 in the control collar 38 open to the drain chamber 22 and the connecting grooves 81 in the control collar 39 to the consumer chamber 19th Thus, the consumer chambers 18 and 19 are throttled with after a short stroke connected to the drain chambers. It is a floating position of the spool 12 reached. The control grooves 40 and 41 are still covered. To The connecting grooves 80 become a further stroke of a predetermined size in the control collar 38 from the consumer chamber 18 and the connecting grooves 81 in the control collar 39 separated from the drain chamber 23. Open shortly after the control grooves 40 in the tax authority 38 towards the consumer chamber 18 and the Control grooves 41 in the tax body 39 to the consumer chamber 19. The one to the Consumer connections 20 and 21 connected hydraulic consumers can thus from the stroke position of the control slide 12 just reached, from the speed started zero, with increasing stroke with increasing Speed are operated. When the control slide 12 is adjusted from the middle position in the opposite direction Floating function position, the connecting grooves 80 on the control collar 39 and the Connection grooves 81 on the control collar 38 effective.

The control grooves 80 and 81 are arranged on the control collars 38 and 39 so that a control groove 80 on one piston collar and a control groove 80 on the other Piston collar and a control groove 81 on a piston collar with a control groove 81 are in alignment with each other on the other piston collar.

In the embodiment according to FIG. 5, a connecting groove 82 is aligned on the slide collar 38 with a connecting groove 82 on the slide collar 39 Location of the connecting grooves 82 with respect to the consumer and drainage chambers in the central position of the control slide 12 differently than in the embodiment according to the Figures 3 and 4. The location of the connecting grooves 82 on the control collars 38 and 39 is such that in the centered central position of the control slide 12, the connecting groove 82 of the tax authority 38 to both the consumer chamber 18 and Drain chamber 22 and the connecting groove 82 on the control collar 39 both to the consumer chamber 19 and the drain chamber 23 is open. Thus at 5 in the middle position of the control slide 12 the two Consumer chambers 18 and 19 fluidly with the drain connection of the directional valve connected. The central position of the control spool corresponds to that Floating function position. If the control slide is now considered, as shown in FIG. 5, moved to the left, the connecting groove 82 in the Control collar 38 to the consumer chamber 18 and the connecting groove 82 in Control collar 39 closed to the drain chamber 23. The spool 12 has then reaches the blocking function position on one side of the middle position. After a further stroke, the control grooves 41 of the control collar open 39 a connection between the consumer chamber 19 and the drain chamber 23 and the control grooves 40 in the control collar 38 a connection between the inlet chamber 15 and the consumer chamber 18. The control slide is located then in one directional function position, whereby by further displacement to the left the quantity of pressure medium supplied to a hydraulic consumer increases.

The circuit diagram of Figure 1 is in accordance with the embodiment of Figure 5 designed. It becomes clear once again that in the middle position of the control spool 12 the consumer chambers 18 and 19 and the chambers 43, 44 and 45 are connected to the drain chambers 22 and 23, and that the inlet chamber 15 is locked. The connection between a consumer chamber and the neighboring one Drain chamber is a throttled connection, which is shown in Figure 1 the chokes formed by the connecting grooves 82 is indicated. After both On the sides, the swimming function position is followed in the middle by one Lock function position and then a directional function position. In the schematic 2 shows clearly that in the embodiment according to FIGS. 3 and 4 in the middle position of the spool the consumer chambers 18 and 19 both shut off against the inlet chamber 15 and against the outlet chambers 22, 23 are. The locking function position in the middle is followed on both sides towards a floating function position in which the connecting grooves 80 and 81 a throttled fluidic connection between the consumer chambers and make the drain chambers. Every swimming function position follows a directional function position.

A directional control valve with the circuit diagram according to FIG. 1 is preferred for controlling a hydraulic travel drive, a directional control valve with the circuit diagram according to FIG. 2 preferably for controlling a bogie axis or a rotary drive for a crane or used a rotator at the free end of a crane.

Claims (16)

Hydraulic directional control valve for load-independent control of a hydraulic consumer, in particular of a mobile machine with regard to direction and speed, with an inlet connection (68), with an outlet connection (24) and with two consumer connections (20, 21), with one in a slide bore (11) of a valve housing (10) axially displaceable control slide (12) for controlling the fluidic connections between the connections (20, 21, 24, 68), with the consumer connections (20, 21) against the inlet connection (68) and are blocked off from the drain connection (24), the inlet connection (68) is blocked in a floating function position of the control slide (12) and the two consumer connections (20, 21) are fluidly connected to the drain connection (24) and in two directional function positions of the control slide (12) the one consumer connection (20, 21) with the inlet connection (68) and the other consumer connection (21, 20) is fluidly connected to the drain connection (24),
characterized,
that the floating function position of the control slide (12) lies between the blocking function position and a directional function position. Hydraulic directional valve according to claim 1, characterized in that the control slide (12) by a spring arrangement (34) in a rest position is centered and that the rest position is the swimming function position. Hydraulic directional valve according to claim 2, characterized in that the control slide (12) from the swimming function position out to the opposite Directions can be shifted into a locking function position is. Hydraulic directional valve according to claim 1, characterized in that the control slide (12) by a spring arrangement (34) in a rest position is centered and that the rest position is the locking function position. Hydraulic directional valve according to claim 4, characterized in that the control slide (12) from the locking function position out to the opposite Directions can be shifted into a floating function position is. Hydraulic directional valve according to any preceding claim, characterized characterized in that in a floating function position of the control slide (12) the two consumer connections (20, 21) throttled with the drain connection (24) are fluidly connected. Hydraulic directional valve according to any preceding claim, characterized characterized in that the control slide (12) has a control collar (38, 39) has, at least in the swimming and in the blocking function position over part of its length between one with a consumer connection (20, 21) connected consumer chamber (18, 19) and an adjacent one, with the drain connection (24) connected drain chamber (22, 23) of the slide bore (11), and that in the control collar (38, 39) a recess (80, 81; 82) is present, which in the blocking function position only applies to one of the two Chambers (18,22,19,23) and in the float position to both chambers (18,22,19,23) is open. Hydraulic directional valve according to claim 7, characterized in that the recess extends radially in the longitudinal direction of the control slide is open and axially limited on both sides connecting groove (80, 81, 82), the Length greater than the clear distance between the consumer chamber (18, 19) and the drain chamber (22, 23). Hydraulic directional valve according to claim 8, characterized in that the control collar (38) facing the drain chamber (22, 23) Front side is provided with control grooves (41) and that with a shift of the control spool (12) from the point at which the connecting groove (82) to Drain chamber (22, 23) is closed to the point where the control grooves (41) to the consumer chamber (18, 19) are opened, one of the blocking function position corresponding stroke distance. Hydraulic directional valve according to claim 8, characterized in that the control collar (38, 39) has a connecting groove (80) in the rest position of the control spool (12) only towards the consumer chamber (18, 19) and when the control spool (12) moves from the rest position out in a first direction initially in addition to the drain chamber (22, 23) is opened and after a further stroke distance to the consumer chamber (18, 19) is closed. Hydraulic directional valve according to claim 10, characterized in that the control slide (12) has a second slide collar (39, 38) which in the swimming and in the blocking function position at least over a part its length between one connected to the second consumer connection (21, 20), second consumer chamber (19, 18) and an adjacent one, with the drain connection (24) connected to the second drain chamber (23, 22) Slider bore (11) is that the second control collar (39, 38) of its end face facing the second outlet chamber (23, 22) with control grooves (41) is provided and that the second control collar (39, 38) has a connecting groove (81) has in the rest position of the control slide (12) only to the second drain chamber (23, 22) is open and when the control spool moves (12) from the rest position in addition to the second consumer chamber (19, 18) is opened and after a further stroke to the second drain chamber (23, 22) is closed at a point where the control grooves (41) of the second tax authority (39, 38) to the second consumer chamber (19, 18) open up. Hydraulic directional valve according to claim 11, characterized in that that the control grooves (41) of the second tax group (39, 38) to the second consumer chamber (23, 22) open shortly after the connecting groove (81) of the second control collar (39, 38) closed to the second drain chamber (23, 22) is. Hydraulic directional valve according to claim 11 or 12, characterized in that each control collar (38, 39) has a first connecting groove (80) which in the Rest position of the control slide (12) towards a consumer chamber (18, 19) is open, and a second connecting groove (81), which in the rest position to a Drain chamber (22, 23) is open, and that a first connecting groove (80) of the first control collar (38) to a first connecting groove (80) of the second control collar (39) and a second connecting groove (81) of the first control collar (38) and to a second connecting groove (81) of the second control collar (39) axially aligned. Hydraulic directional valve according to one of claims 8 to 13, characterized characterized in that each connecting groove (80, 81, 82) on a control collar (38, 39) exactly diametrically opposite another connecting groove (80, 81, 82). Hydraulic directional valve according to any preceding claim, characterized characterized in that it can be operated electrically or electrohydraulically. Use of a hydraulic directional valve after a previous one Claim within a hydraulic travel drive, within a hydraulic Control for a bogie axis or within a hydraulic one Rotary drive for a crane or a rotator at the free end of a crane.

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