EP3093505B1 - Hydraulic control device and selector valve - Google Patents

Description

The invention relates to a hydraulic control according to the preamble of claim 1. In the EP 1 837 529 A1 known hydraulic control, the form pressure circuit includes a 3/2-way valve, which is pressure-controlled from a connected to the shuttle valve control line against a spring, which influences the predetermined form. In one position, the 3/2-way valve, under the force of the spring, connects the load pressure signal tap of the pressure line leading to the further proportional spool to the load pressure signal circuit, while the control line is shut off by the shuttle valve. The 3/2-way valve upstream pressure relief valve limits the maximum, can be fed into the load pressure signal pressure, so that the delivery control causes the pump to initially build only the predetermined form in the pressure line. In the other position of the 3/2-way valve, which is set when applying a coming from the shuttle valve control pressure, if this overcomes the force of the spring, the control line coming from the shuttle valve is connected to the load pressure signal circuit, while blocking the coming from the load pressure signal tap the pressure line control line and the pressure relief valve are inoperative. The admission pressure circuit is arranged either in a housing block of the selector valve, or in an intermediate block. Conveniently, the pressure relief valve and the 3/2-way valve are physically small and inexpensive, since they have to process only small amounts of control pressure medium. In any case, however, the incorporation of the 3/2-way valve with its connection channels inconveniently high effort.

At one off DE 10 2007 055 377 A1 known hydraulic control is actuated in its direction of rotation reversible hydraulic motor. The activatable via the selector valve form pressure circuit is associated with only one direction of rotation of the hydraulic consumer, while the opposite direction of rotation is controlled by the control of the variable. Further spool valves for further hydraulic consumers are to be connected upstream of the selector valve to the pressure line of the variable displacement pump.

At the EP 1 907 706 B1 known hydraulic control is the selector valve, a 4/2-way solenoid valve between the pump line and the pressure line to the other proportional slide and the return. The pressure line is additionally connected via a 2/2-way valve and a quantity-limiting throttle with the pressure relief valve of the form pressure circuit and the shuttle valve in the load pressure signal circuit. The 2/2-way valve is against a spring influencing the form of a leading to the shuttle valve control line z. B. from pressure-controlled another hydraulic consumer. Since the form pressure circuit for adjusting the form is fed directly from the pressure line, at least the 2/2-way valve is bulking and expensive. The structural complexity of the 2/2-way valve, its inclusion, and its connection channels is high.

Out DE 4230 185 C2 is a 4/3-way proportional spool with a supply regulator in the load pressure signal circuit known in which the direction detection of the respective deflection a only in a respective control position continuous control pressure connection is used. Despite this additional control function for the control pressure of the spool and the housing are optimally short.

The invention has for its object to provide a hydraulic control of the type mentioned with structurally simplified form pressure circuit and a low-cost selector valve.

The stated object is achieved with the features of claim 1.

Since in the hydraulic control the selector valve itself undertakes the task to control the load pressure signal to the pressure relief valve when form in the pressure line to the further proportional spool form, eliminating the need to provide a separate switching valve for this control function. This saving is also advantageous because omitted channels for an additional switching valve, which require high processing effort when training, for example, in a steel block housing and with multiple bends. The selector valve is useful for hydraulic controls that are operated with a form pressure circuit because the selector valve itself can take over the task to durchzusteuern to the pressure relief valve of the form pressure circuit as soon as form is to build, however, to make the pressure relief valve inoperative as soon as is independent of load to control.

The selector valve is a proportional control spool incorporated into the load pressure signal circuit, preferably a proportional proportional control spool with proportional solenoids and pressure pilot controls. The proportional spool is functionally associated with at least one hydraulic consumer and connects the pump in the first control position with this hydraulic consumer, whereas in a second control position the pump via the pressure line with each further proportional spool, while the hydraulic consumer is disconnected from the pump. This is useful in hydraulic controls such as hydraulic work vehicles with hydraulically extendable floor supports to extend and lock the supports in the second control position before further hydraulic consumers are controlled during the control of the floor supports are extended and must not be controlled. The
Control pressure connection in the proportional spool is only continuously controlled when the proportional spool is placed in the first control position. The others Consumers are then initially not load-independent, but controlled with the form until the tapped by these other consumers load pressure signal exceeds the pressure value of the form. From this point on, the control of the other hydraulic consumers is independent of the load. On the other hand, in the second control position, each hydraulic consumer can be controlled independently of the load from the beginning, since the admission pressure circuit remains passive.

Particularly useful is the load pressure signal circuit connected via a hydraulic damping device to the pump delivery control. This damping device dampens not only pressure fluctuations in the load pressure signal circuit, but may also prevent or mitigate undesirable lowering of the load pressure signal at the pump delivery control when switching the selector valve between its control positions. The hydraulic damping device includes, for example, two series-connected throttles and two opposing check valves and may be housed in an input block of the hydraulic control.

Production technology favorable is connected to the control pressure connection in the selector valve, a first control line to the return, which contains the pressure relief valve, which is acted upon by a pre-pressure adjusting spring. As soon as the response pressure of the pressure limiting valve is reached in this control line via the control pressure connection, this prevents a further increase in the load pressure signal. In this case, the pressure relief valve against the spring from a second, also connected to the control pressure connection control line is opened.

In one embodiment of the hydraulic control, the pump is a variable displacement pump with a control input belonging to the delivery control. Among other things, the variable-displacement pump is adjusted to build up the admission pressure in the pressure line via the control input. Part of the delivery control may also be a pressure compensator circulation circuit to the return.

In another embodiment, the pump is a fixed displacement pump, the conveyor side, preferably in an input block of the hydraulic control, to be connected to a conveyor-regulating pressure compensator circulation circuit. In this case, it is expedient if the load pressure signal circuit is connected to a feed side of the pressure compensator circulation circuit, preferably via a hydraulic damping device arranged in the load pressure signal circuit.

The control pressure connection could be accommodated in a conventional way in a spool because of the additional control function, but would then because of the additional Control function in an inappropriate extension of the piston valve and the housing result. Therefore, according to a particular important aspect of the invention in the selector valve, the control pressure connection between two axially adjacent SteuerleitungsEinstichen in a axially displaceable spool piston housing bore and at least one of a plurality of separated recesses in the spool circumference continuously switchable. The outlines of these recesses, preferably in each case two adjacent recesses, overlap one another in the longitudinal direction of the spool. By contrast, the depressions are spaced apart from one another transversely to the longitudinal direction and are provided in the first control position within an axial section delimited in the longitudinal direction of the slide piston at least approximately in accordance with the adjustment stroke of the slide piston. This limited axial section is longer than the longitudinal outline of each well. The wells can be placed in the spool circumference so that they do not overlap with all other other control functions associated control channels in the housing bore, but are separated from each other by positive overlaps, so that working pressure can lick neither to the punctures, nor to the return, while the Spool is adjusted. As a result, the length of the spool and the housing bore and thus of the housing is not extended by this design of the control pressure connection, but it remains the usual length of a multi-position multiway Wegeschiebers despite the control pressure connection.

Advantageously, the wells are blind holes in the spool circumference, which are preferably arranged along an imaginary thread line. This concept is favorable manufacturing technology.

The depressions can be equal to each other or different sizes. It is only necessary to ensure that they do not overlap with any working channels in the housing bore when the spool is adjusted. The outlines of the depressions can have any geometric shapes. Instead of blind holes control notches or the like could be formed.

Appropriately seen in the longitudinal direction of the spool distance between the two control line punctures in the housing bore is smaller than the contour of a depression. As a result, within a large stroke of the spool, in each case at least one indentation that precisely intersects the recesses connects the control line recesses with one another.

Suitably, the width of each control line recess in the housing bore seen in the longitudinal direction is smaller than the contour of a recess.

In an expedient embodiment, the pressure limiting valve and / or the shuttle valve are arranged in a housing block of the selector valve. This contributes to the compactness of the hydraulic control, which is created for example in the usual block design.

Alternatively, however, it is also possible to arrange the pressure relief valve and / or the shuttle valve in an attached with a housing block of the selector valve to an input block of the hydraulic control intermediate block. The latter measures result in minimal space in easy to be made connection channels to the pressure relief valve and / or shuttle valve.

Fig. 1

ein Blockschaltbild einer Hydrauliksteuerung in einer ersten Steuerstellung eines Wahlventils,

Fig. 2

ein Blockschaltbild einer weiteren Ausführungsform der Hydrauliksteuerung in einer ersten Steuerstellung eines Wahlventils,

Fig. 3

einen Teilschnitt durch ein Wahlventil, und zwar in der oberen Hälfte in einer Steuerstellung a bei Beginn einer Steuerfunktion, in der unteren Hälfte hingegen nach Beendigung der Steuerfunktion in einer beispielsweisen Nullstellung, und

Fig. 4

ein Detail zu Fig. 3.

Embodiments of the subject invention will be explained with reference to the drawing. Show it:

Fig. 1

FIG. 2 is a block diagram of a hydraulic control in a first control position of a selector valve. FIG.

Fig. 2

1 is a block diagram of another embodiment of the hydraulic control in a first control position of a selector valve,

Fig. 3

a partial section through a selector valve, in the upper half in a control position a at the beginning of a control function, in the lower half, however, after completion of the control function in an exemplary zero position, and

Fig. 4

a detail too Fig. 3 ,

Fig. 1 illustrates a hydraulic control S, for example, a hydraulic work vehicle such as a mobile concrete pump, a fire engine with aerial ladder, a forest crane or the like. To the hydraulic control S several hydraulic consumers 34, 34 'are connected. The hydraulic consumers 34 are associated with extendable floor supports, for example, while the hydraulic consumers 34 'can be mast or ladder cylinders. Allen hydraulic consumers 34, 34 'is associated with a common pump 15 which sucks from a reservoir R and in the embodiment in Fig. 1 a variable displacement pump 16 with a control input 17 is. From the control input 17, which belongs to a delivery control F, for example in an input block of the hydraulic controller S, performs a control line 18 to a hydraulic damping device 19 of a load pressure signal circuit 20, which in the embodiment shown two series-connected chokes 21, 22 and two opposing check valves 23, 24 includes.

On the delivery side, the pump 15 is connected to a pump line 25. A return line 26 leads to the reservoir R.

In the embodiment in FIG Fig. 1 is part of the delivery control F a arranged between the pump line 25 and the return line 26 2/2-way pressure compensator 27 which is pressure-controlled from the pump line 25 in Aufsteuervorrichtung, however, in Zusteuerrichtung via a control spring and z. B. leading to a pressure reducing valve 29, connected to a control pressure supply, not shown, control line for example Druckvorsteuerungen of valves in the hydraulic control S.

To the input block, a block with a selector valve W is connected, which is at least switchable between a first control position a and a second control position b (and here in a shut-off zero position), either by a hand lever or by proportional solenoids and Druckvorsteuerungen. The selector valve W is connected via a pressure line 32 to at least one further proportional spool 49, and via a working line 33 to the or the hydraulic consumer 34, and allows a function selection e.g. such that either only the consumers 34 'are controllable and connected to the pump 15, or the pressure line 32 is disconnected and the working line 33 is acted upon.

In the illustrated embodiment, the selector valve W has to prevent the other consumers 34 'are controlled as long as the extendable by the hydraulic consumers 34 floor supports are not properly extended, and also that the floor supports are not retracted, as long as further consumers 34' are controlled.

In such hydraulic controls S, it is expedient to control the further consumers 34 'initially with a predetermined admission pressure (higher than the circulation pressure but lower than the maximum working pressure) which is already being built up before, for example, the further proportional control valve 49 is out of zero Position is deflected. Without the in the pressure line 32 in the first control position a of the selector valve W controlled form would pass to the proper control of the other consumers 34 'too much time, since the load pressure signal circuit 20 is loaded with a load pressure signal only when the further proportional spool 49 far is sufficiently deflected, or would lack of sufficient pressure in the pressure line 32 at deflection of the further proportional spool 49 even the load under load hydraulic consumers 34 'sag or yield.

In order to avoid these disadvantages, the hydraulic control S is equipped with a pre-pressure circuit Y assigned here to the selector valve W, which builds up the admission pressure in the pressure line 32 before any further proportional control slide 49 is deflected.

The selector valve W could be a switchable between the two control positions a and b control spool, but is in the embodiment in Fig. 1 a 4/3-proportional control slide 31 with zero position, in which in a housing bore 1 adjustable spool K a Lastdruckabgriff 35 from the working line 33 and a Lastdruckabgriff 36 from the pressure line 32 are provided. In the first control position a of the Lastdruckabgriff 36 is connected via a channel 37 in the spool K with a control line 38 which includes a throttle 39 and leads to a control line 40 to a shuttle valve 47 in the load pressure signal circuit 20. The control line 38 is also connected downstream of the throttle 39 with a node 41, from which a control line 42 to a control line groove 12 (based on the 3 and 4 explained) in the housing bore 1 leads. This control line groove 12 is in the first control position a via a control pressure connection V, namely at least one recess 14 in the 3 and 4 , for example, connected to the further control line groove 13 in the housing bore 1, from which a control line 43 leads to a control side of a pressure relief valve 45 of the form pressure circuit Y, and a branching control line 44 to the return line 26. The pressure relief valve 45 is disposed in this control line 44 and is acted upon by a pre-pressure determining spring 46 in the direction of control.

The shuttle valve 47 is connected with a lateral connection to the control line 40 and with the second lateral connection to a control line 48 to a load pressure tap of the further proportional control slide 49, while its middle connection is connected to the load pressure signal circuit 20, so that the respective higher load pressure signal, either from the control line 40 or the control line 48, in the load pressure signal circuit 20 to the damping device 19 and the conveyor control F is transmitted.

The embodiment of the hydraulic control S in Fig. 2 is different from that of Fig. 1 in that the pump 15 is a constant-displacement pump 16 ', and the pump delivery control F contains the circulation pressure compensator 27 between the pump line 25 and the return line 26. The circulation pressure compensator 27 is on the control side from the pump line 25 druckvorgesteuert, and zusteuerseitig is acted upon by a control spring and from the control line 18, which leads here directly from the hydraulic damping device 19 to the circulation pressure compensator 27. The further construction of the embodiment in Fig. 2 corresponds to the Fig. 1 ,

Function:

Is in Fig. 1 set the selector valve W in the second control position b, then the pressure line 32 is depressurized and the working line 33 is pressurized in accordance with the load pressure signal, which rests on the load pressure tap 35 and is brought via the control line 40 and the shuttle valve 47 in the load pressure signal circuit 20 and by the hydraulic damping device 19 to the control input 17 of the variable displacement pump 16, the flow rate is adjusted accordingly. In Fig. 2 the delivery rate is set in the pump line 25 via the pressure compensator 27.

After, for example, the hydraulic consumers 34 have extended the floor supports, the selector valve W is switched to the first control position a, so that the working line 33 is relieved to the return line 26 and the pressure line 32 is pressurized. About the Lastdruckabgriff 36, the channel 37 and the control line 38 and the throttle 39 and the control line 40, the load pressure signal in the load pressure signal circuit 20 and through the damping device 19 to the control input 17 is brought to the flow rate, for. the Verstellpumpe 16 hochzuregeln accordingly. Namely, the delivery rate is so highly regulated that the predetermined form, adjusted at the pressure relief valve 45 by the spring 46, is reached. Because the prevailing in the control line 40 load pressure signal is limited by the node 41 via the control line 42 and the control pressure connection V and the control lines 43 and 44 of the pressure relief valve 45 accordingly. This means that the consumers 34 'can initially be controlled with the admission pressure as soon as the further proportional control slide 49 is deflected.

Since in the second control position b, the control pressure connection V is not continuous, the pressure relief valve 45 of the form pressure circuit Y is not applied, so that the hydraulic consumers 34 'are controlled independent of the load.

When the selector valve W is changed to the first control position a, the control pressure connection V is also continuous at the same time. Even if the further proportional spool 49 is still in the zero position, pressure builds up in the pressure line 32, which is not only controlled via the Lastdruckabgriff 36, the channel 37 and the continuous load pressure connection V in the control line 40, but also to the pressure relief valve 45, which limits the load pressure signal in the load pressure signal circuit 20 in such a way that the predetermined admission pressure in the pressure line 32 is established by means of the delivery control F, for example by the variable displacement pump 15. If the further proportional control slide 49 is then deflected, the further consumers 34 'are not controlled independently of the load until the load pressure signal in the control line 48 exceeds the load pressure signal in the control line 40 limited by the pressure relief valve 45 and the changeover valve 47 directly from the control line 48 Switches to the load pressure signal circuit 20. Thereafter, the other consumers are controlled 34 'load independent.

The function of the form pressure circuit Y in the embodiment of the hydraulic control S in Fig. 2 corresponds largely to the basis of Fig. 1 explained. One difference is that the constant-displacement pump 16 'has constant delivery rate, but the circulation pressure compensator 27 in the second control position b of the selector valve W provides the necessary quantity. In the first control position a of the selector valve W, however, is first controlled by the form and only later in accordance with the load pressure signal in the fed from the control line 48 load pressure signal circuit 20.

The selector valve W shown in section Fig. 3 is, for example, a way control slide for speed control of a hydraulic consumer, not shown. The selector valve contains in a housing bore 1 a linearly displaceable spool K, which by an operation not shown at least between a first control position a (upper half of Fig. 3 ) and a zero position 0 (lower half) is adjustable. To the housing bore 1, a working line A with its mouth 10 is connected, and a pump line 9 (corresponding to the pump line 25 in the Fig. 1 and 2 ) and a return line (corresponding to the return line 26 in the Fig. 1 and 2 ).

In the housing bore 1, two Steuerleitseinstiche 5, 6 (z., Circumferential) formed, which are run over during the sliding movement of the spool K by bridging channels C and produce a continuous control pressure connection V in the control position a when a recess 8 in the spool K the Mouths 9 and 10 (P, A) connects.

In the upper half of Fig. 3 is the spool K at the end of the control position a. The working channel 8 in the spool K connects the pump line P to the working line A. The control line recesses 5, 6 are connected via the bypass channel C.

The width of the working channel 8 corresponds to y '. The stroke of the spool K between the zero position 0 (lower half of the figure) and the control position a corresponds to s'. The stroke s 'is a measure Ü, a so-called Abdichtüberdeckung, greater than y'. The length of the bypass channel C is limited to an axial section y (or to an axial section s) of the spool K, where y approximately corresponds to y 'and s'.

If y is approximately y ', then the bridging channel C connects the control line recesses 5, 6 over the entire stroke of the spool K, within which the recess 8 establishes a flow connection between the pressure line 9 and the working line 10.

Corresponds to the length of the axial section s approximately s', then the Steuerleitungseinstiche 5, 6 are connected together until the working channel 8 in the zero position (lower half) arrives. The length of the axial section s, y, over which the bypass channel C extends in the spool K, can be tuned to the operating conditions, for. B. on the stroke of the spool K, via which the control line bites 5, 6, the control lines 12, 13 to be connected to each other.

The bridging channel C consists of a plurality of individual, in the circumferential direction of the spool K spaced recesses 14 in the spool circumference, z. B. blind or blind holes. The absolute distance between adjacent recesses 14 corresponds approximately to the Abdichtüberdeckung Ü. In the longitudinal direction of the spool K, the contours of adjacent recesses 14 overlap so far that (see Fig. 4 ) Each a subsequent recess 14, the flow connection between the control line punctures 5, 6 already opens before the previous recess 14 interrupts their flow connection.

In Fig. 4 are otherwise the dashed depressions 14 to illustrate the outline overlaps in the sectional plane of the left recess 14 shown in solid lines folded.

The axial distance between the mouth 9 and the nearest control line groove 6 is expediently d + Ü. d corresponds to the contour of a recess 14 seen in the longitudinal direction of the spool K. With average spool sizes, this distance can be about 4.5 to 6.0 mm, whereas previously this distance had to be between 8.0 and 10.0 mm for corresponding spool sizes. Optionally, the Steuerleitungseinstich 6 can be moved even closer to the mouth 9, as shown. Although only a small amount of control pressure fluid compared to the amount of the working pressure fluid flows for the control function, the control function of the control pressure medium in the housing bore and in the spool actually needed in addition the same length as the control function for the working pressure medium. This resulted in unusually large length of the spool and the housing bore or the housing. The embodiment of the selector valve W in the 3 and 4 However, despite the control pressure connection V for the control pressure medium characterized by short axial length, because the wells 14 are arranged in the same length portion of the spool K, as required for at least one other control function channels.

The recesses 14 are selectively distributed over the axial section s or Ü (as with 14 'in the lower half of FIG Fig. 4 indicated), but so that between the outlines of two in the longitudinal direction of the spool K successive recesses 14 'as large as possible and the mutual seal between these recesses on the wall of the housing bore. 1 ensuring absolute distances, while they overlap in a projection transverse to the longitudinal direction in the longitudinal direction of the spool K with their outlines. Manufacturing technology, it is expedient to arrange the recesses 14 along an imaginary thread line in the circumference of the spool K. Within the axial section s could be distributed over the circumference of the spool K several similar acting groups then even smaller recesses 14 or 14 'may be provided. The depressions may be the same or different from each other. The diameter or the outline d of each recess 14, 14 'is at least as large as the intermediate distance x between the control line grooves 5, 6 seen in the longitudinal direction, is preferably as large as x plus the axial widths w of the control line grooves 5, 6 the depressions 14, 14 'even more than two Steuerleitungseinstiche be assigned.

In the lower half of Fig. 3 the recess 8 in the spool K of the mouths 9, 10 is separated. The recesses 14 are moved out of the axial region of the control line grooves 5, 6. The Steuerleitungseinstiche 5, 6 are z. B. at the moment separated from each other, in which the outline of the rearmost in the direction of displacement recess 14, 14 'passes over the edge of the control line groove 5. Suitably, the length of the axial section s, y is chosen so that the control function begins as soon as the working channel recess 8 comes into contact with the openings 9, 10. The control function for the control pressure medium ends as soon as this connection is released. Alternatively, however, it would also be possible to start or end the control function either for the working pressure medium or the control pressure medium, or to terminate.

The contours of the recesses 14, 14 'need not be circular. It can, for. B. depending on the processing method in the production of the spool K any outline shape can be selected. Recesses on a peripheral side of the spool K can for example be connected to an inner channel of the spool K and / or through holes with recesses on the other peripheral side of the spool.

In the hydraulic controls S of Fig. 1 and 2 This principle of the control function for the control pressure medium for connecting the load pressure tap 36, 37, 38, 39, 41, 42 used with the control lines 43, 44 to the pressure relief valve 45 of the form pressure circuit Y. A separate switching valve in the form pressure circuit Y is thus saved.

Claims (13)

1. A hydraulic controller (S), particularly for hydraulic working vehicles, with a common pump (15) for supplying a plurality of hydraulic consumers (34, 34'), a selector valve (W) switchable between at least two control positions (a, b) and at least one further proportional slide control valve (49) connected to a pressure conduit (32) from the selector valve (W), a load pressure signal circuit (20), which is connected to an output controller (F) of the pump (15) and may be acted upon from load pressure tappings (35, 36), a primary pressure circuit (Y) including a pressure limiting valve (45) and at least one shuttle valve (47), which connects either the primary pressure circuit (Y) or a load pressure signal tapping of the further proportional control valve (49) to the output controller (F), characterised in that the pressure limiting valve (45) of the primary pressure circuit (Y) is connected directly to a load pressure signal tapping (36) of the pressure conduit (32) and the shuttle valve (47) via a control pressure connection (V) in the selector valve (W) itself, which is open only in a first control position (a) of the selector valve (W), that arranged between the load pressure signal tapping (36) of the pressure conduit (32) and the shuttle valve (47) and the control pressure connection (V) there is a control pressure throttle (39), and that the selector valve (W) is a proportional slide control valve (31) integrated into the load pressure signal circuit (20), which, in the first control position (a), connects the pump (15) to at least one hydraulic consumer (34) controllable by the proportional slide control valve (31) and simultaneously disconnects the pressure conduit (32) to the further proportional slide control valve (49) from the pump (15) and, in a second control position (b), disconnects the hydraulic consumer (34) from the pump (15) and connects the pump (15) to the further proportional slide control valve (49) via the pressure conduit (32).
2. A hydraulic controller as claimed in Claim 1, characterised in that the selector valve (W) is a four/three-way slide control valve for the hydraulic consumer (34) of at least one floor support.
3. A hydraulic controller as claimed in Claim 1, characterised in that the load pressure signal circuit (20) is connected to the output controller (F) via a hydraulic damping device (19), preferably a damping device, which includes two throttles (21, 22) in series and two parallel, oppositely directed non-return valves (24, 23), between the load pressure signal circuit (20) and a control conduit (18).
4. A hydraulic controller as claimed in Claim 1, characterised in that connected to the control pressure connection (V) there are a first control conduit (44) via the pressure limiting valve (45), including a spring (46) adjusting the primary pressure, to the return conduit (26) and a second control conduit (43) to a control open side, opposite to the spring (46), of the pressure limiting valve (45).
5. A hydraulic controller as claimed in Claim 1, characterised in that the pump (15) is a variable displacement pump (16) with a control input (17) forming part of the output controller (F).
6. A hydraulic controller as claimed in Claim 1, characterised in that the pump (15) is a constant output pump (16') and is connected on the output side, preferably in an inlet block of the hydraulic controller (S), to a pressure compensation circulation circuit (27) forming part of the output controller (F) and that a control conduit (18) leads from a hydraulic damping device (19) arranged in the load pressure signal circuit (20) to a control closed side of the pressure compensation circulation circuit (27).
7. A hydraulic controller as claimed in Claim 1, characterised in that in the selector valve (W) the control pressure connection (V) between at least two axially adjacent control conduit tappings (12, 13) in a housing bore (1) containing an axially slidable slide piston (K) and at least one of a plurality of separate recesses (14, 14') in the slide piston periphery is switchable to be open, wherein the outlines of the recesses, preferably each two adjacent recesses, overlap with one another in the longitudinal direction of the slide piston (K) but are spaced from one another transverse to the longitudinal direction and the recesses are provided within an axial section (s) defined in the longitudinal direction of the slide piston (K) at least approximately corresponding to the displacement stroke of the slide piston (K) in the first control position (b), which is longer than the width (d) of the outline of each recess (14, 14') viewed in the longitudinal direction.
8. A hydraulic controller as claimed in Claim 7, characterised in that the recesses (14, 14') are blind bores, which are preferably arranged in the slide piston periphery along a hypothetical screw thread line.
9. A hydraulic controller as claimed in Claim 7, characterised in that the recesses (14, 14') are of the same size as one another or of different sizes to one another.
10. A hydraulic controller as claimed in Claim 7, characterised in that the spacing of the control conduit tappings (12, 13) in the housing bore (1), seen in the longitudinal direction, is smaller than the width (d) of the outline of a recess (14, 14').
11. A hydraulic controller as claimed in Claim 7, characterised in that the width of each control conduit tapping (12, 13) in the housing bore (1), seen in the longitudinal direction, is smaller than the width (d) of the outline of a recess (14, 14').
12. A hydraulic control apparatus as claimed in at least one of the preceding claims, characterised in that the pressure limiting valve (45) and/or the shuttle valve (47) is or are arranged in a housing block (11) of the selector valve (W).
13. A hydraulic controller as claimed in at least one of Claims 1 to 11, characterised in that the pressure limiting valve (45) and/or the shuttle valve (47) is or are arranged in an intermediate block attached with a housing block (11) of the selector valve (W) to the inlet block.

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