A pre-selection valve, a hydraulic valve assembly and a hydraulic control device

Abstract

The present invention relates to a pre-selection valve 1 for a hydraulic valve assembly 101, the hydraulic valve assembly 101 having a switching element 2, a pressure input line 3, a first pressure output line 4 and a first load pressure line 8, the first load pressure line 8 having at least one load pressure inlet 6 and at least one load pressure outlet 7. The switching element 2 can be switched from a neutral position N to a first switching position 1S, in which the pressure input line 3 is connected to the first pressure output line 4 in the first switching position 1S. The pre-selection valve 1 has a second load pressure line 9, a third load pressure line 10 and a load boosting device 11 for boosting the load pressure. The second load pressure line 9 branches off from the pressure input line 3 upstream of the switching element 2, and the load boosting device 11 is connected to the third load pressure line 10. The third load pressure line 10 connects the load boosting device to the first load pressure line 8, in which the second load pressure line 9 is connected to the load boosting device 11 in the first switching position 1S, and the second load pressure line 9 is blocked in the neutral position N. Furthermore, the present invention also relates to a hydraulic valve assembly 101 and a hydraulic control device.

Description

[0001] The present invention relates to a pre-selection valve for a hydraulic valve assembly, a hydraulic valve assembly including such a pre-selection valve, and a hydraulic control device including a hydraulic valve assembly provided according to the present invention.

[0002] Such pre-selection valves are known from the prior art, for example EP 3 093 505 A1. The known pre-selection valve has a switching element, a pressure input line, a first pressure output line, and a first load pressure line, the first load pressure line having at least one load pressure inlet and at least one load pressure outlet. The switching element can be switched from a neutral position to at least a first switching position, in which the pressure input line is connected to the first pressure output line in the first switching position of the pre-selection valve. A first group of hydraulic consumption devices or hydraulic elements (for example, control spools) are typically connected to the pressure output line. As an example, a hydraulic loading crane or a hydraulic arm can be controlled therewith.

[0003] Furthermore, the known pre-selection valve typically has another load pressure line that taps off a load pressure signal from the pressure output line downstream of the switching element, and the load pressure signal is sent to the load pressure outlet via a passage in the switching element at the corresponding switching position. The terms "upstream" and "downstream" as used herein refer to the flow direction from the pressure input line to the corresponding pressure output line. Typically, a spool valve is used as the pre-selection valve. However, a lift valve can also be used.

[0004] For example, if a fixed-displacement pump is used to provide pressure throughout the hydraulic control system, the load pressure signal is reported to a cycle controller, such as a cycle pressure compensator. Herein, the load pressure signal acts together with the preload pressure in the closing direction of the cycle pressure compensator on the pump pressure, and the pump pressure is typically signaled by a throttle valve in the opening direction. The preload pressure is typically provided by a spring. Therefore, in order to reduce the cycle volume, the load pressure signal must be combined with the preload pressure to ensure it is large enough. However, the preload pressure must have a certain magnitude such that there is sufficient basic pressure in the system, for example for hydraulically switching the switching element. Typically, a preload pressure greater than 4 bar, especially 9 bar, 14 bar or 24 bar is used.

[0005] In order to generate a sufficiently high load pressure signal, EP 3 093 505 A1 proposes to provide a throttle valve in the load pressure line downstream of the passage in the switching element. However, the disadvantage of doing so is that the passage itself also forms a hydraulic resistor, and thus the obtained load pressure signal is closely related to the quantity. In addition, a high preload pressure also means that in some cases, due to the back pressure generated in the system, the required quantity (l / min) cannot reach the control spool downstream of the pre-selection valve. This problem can be solved by using a larger valve assembly, but this will increase the cost and also increase the weight.

[0006] Furthermore, a relatively high preload pressure in a mobile hydraulic device is disadvantageous in terms of energy, especially in the case of a fixed-displacement pump. An example of a loading crane serves as a good illustration. The fixed-displacement pump is directly driven by the internal combustion engine of a vehicle equipped with the mobile hydraulic device. In the idle state, i.e., when the hydraulic consumption device is not activated, the fixed-displacement pump operates, and the delivered volume is directly fed into the storage tank through a circulating pressure compensator. For example, if the fixed-displacement pump delivers 140 l / min at a preload pressure of 14 bar in the idle state, this corresponds to an energy consumption of approximately 3.3 kW. Even if the preload pressure is reduced to 9 bar, the energy consumption can be reduced to approximately 2.1 kW for the same quantity. However, as described above, it is not possible to simply reduce the preload pressure.

[0007] Therefore, the object of the present invention is to disclose a pilot valve for a hydraulic valve assembly that is more energy-efficient in the idle state and at the same time enables a sufficient flow rate to be achieved.

[0008] This task can be solved by the features described in claim 1. Other advantageous embodiments are described in the dependent claims.

[0009] The pilot valve for a hydraulic valve assembly according to the present invention differs from the known pilot valves in the prior art in that the pilot valve has a second load pressure line, a third load pressure line, and a load boosting device for increasing the load pressure. The second load pressure line branches off from the pressure input line upstream of the switching element, and the load boosting device is connected to the third load pressure line. The third load pressure line connects the load boosting device to the first load pressure line, wherein the second load pressure line is connected to the load boosting device in a first switching position and is blocked in the mid position.

[0010] Differing from the prior art, the load pressure signal is tapped directly before the switching element and is not fed back through the switching element. Therefore, the load pressure signal is independent of the quantity. According to the present invention, the load boosting device only increases the load pressure signal when the switching element is not in the mid position. Therefore, a lower overall base pressure or preload pressure in the system can be selected, for example, 4 bar or a lower pressure. On the one hand, this saves energy, and on the other hand, the required quantity can be achieved at the control spool downstream of the pilot valve.

[0011] Preferably, the preselection valve includes a fourth load pressure line to which the load boosting device is connected, and the fourth load pressure line leads to the first load pressure line at the junction. Preferably, the load boosting device includes at least one first hydraulic resistor and a second hydraulic resistor, wherein the first hydraulic resistor is supplied with flow by a switching element, and wherein the second hydraulic resistor is supplied with flow by the third load pressure line. In this case, it is also conceivable that at least one first hydraulic resistor is adjustable, and / or the second hydraulic resistor is adjustable. Specifically, it is advantageous if at least one first hydraulic resistor is a nozzle, and / or if the second hydraulic resistor is a nozzle.

[0012] By this connection of the hydraulic resistors or by a nozzle chain, the load pressure in the load boosting device can be increased accordingly and forwarded through the first load pressure line. Therefore, an increased load pressure signal appears at the pressure outlet. Since the load pressure can be increased to the required magnitude as needed, the adjustability of the hydraulic resistors or nozzles provides particularly high flexibility. Thus, the load pressure tapping signal is increased in a reproducible manner and independent of the quantity in the load boosting device and reported to the load pressure outlet. By appropriately selecting the diameter of the hydraulic resistor, boosting between 5 bar and 40 bar can be easily achieved. In addition, the use of hydraulic resistors has the advantage that they can be provided at low cost.

[0013] Preferably, the second hydraulic resistor is arranged in the first load pressure line or the third load pressure line. This promotes the formation of a preselection valve with a particularly simple structure.

[0014] Alternatively, it is advantageous if the load boosting device has a profiling valve, and a barrier is provided in the first load pressure line between the load pressure inlet and the load pressure outlet, and the third load pressure line branches off from the first load pressure line between the load pressure inlet and the barrier. Specifically, it is advantageous if a proportional profiling valve is used in this context. The profiling valve "compares" the pump pressure reported through the second load pressure line with the load pressure reported through the third load pressure line and applied to the load pressure inlet, and accordingly increases the total load pressure, which is then specifically reported to the load pressure outlet through the fourth load pressure line.

[0015] Preferably, the preselection valve has a second pressure output line, in which the switching element can be switched from the neutral position to a second switching position, in which the pressure input line is connected to the second pressure output line in the second switching position of the preselection valve. The second load pressure line is blocked in the second switching position, and the second pressure output line is connected to the first load pressure line in the second switching position, such that the pressure present in the pressure input line is present at or reported to the load pressure outlet. This enables the second set of hydraulic consumer devices connected to the second pressure output line to be controlled via the preselection valve. In addition, it can be ensured that a signal of a sufficiently high load pressure is also issued in the second switching position.

[0016] The preferred embodiment provides a preselection valve, which includes a fifth load pressure line and a second pressure output line, wherein the fifth load pressure line branches off from the pressure input line upstream of the switching element. The switching element can be switched from the neutral position to a second switching position, in which the pressure input line is connected to the second pressure output line in the second switching position of the preselection valve. The fifth load pressure line is connected to the load boosting device in the second switching position, wherein the second load pressure line is blocked in the second switching position and the fifth load pressure line is blocked in the first switching position. This enables the second set of hydraulic consumer devices connected to the second pressure output line to be controlled via the preselection valve. Herein, as will be described below, it is necessary to selectively send the second load pressure signal (of the second set of hydraulic consumer devices) to the load pressure outlet via the load boosting device through the second load pressure inlet.

[0017] For example, the support of a vehicle equipped with a mobile hydraulic device can be controlled in the second switching position. This ensures that when the second pressure output line is activated via the preselection valve, the load pressure signal is also increased accordingly. In this case, the load pressure can also be increased individually for each switching position, for example, by forming a first hydraulic resistor with different control edges in the switching element between the two switching positions.

[0018] Preferably, the load pressure increased by the load boosting device depends on the amount and direction of deflection of the switching element from the neutral position. This can be achieved, for example, by integrating the first hydraulic resistor in the switching element and forming it, for example, by the control edge. According to the proportional deflection of the switching element, a correspondingly higher load pressure can be achieved. In addition to the first switching position and / or the second switching position, there can also be other switching positions for controlling the second set of hydraulic consumer devices. For example, a third switching position can be provided after the second switching position, which can provide a "boost" function, that is, when the switching element of the preselection valve is fully deflected, the overall load pressure increases by a greater amount than in the first switching position.

[0019] Preferably, the junction is a directional control valve. The directional control valve blocks the fourth load pressure line or the portion of the first load pressure line between the junction and the load pressure inlet, depending on the location where the higher load pressure is applied.

[0020] Furthermore, this task can be solved by the hydraulic valve assembly according to claim 11. The hydraulic valve assembly includes the above-mentioned pre-selection valve of the present invention and at least one control spool valve connected to the pre-selection valve.

[0021] If a second group of hydraulic consumption devices is to be controlled, the hydraulic valve assembly has a second load pressure inlet. The second load pressure inlet can be arranged, for example, on the end plate of the hydraulic valve assembly and can be connected to the first load pressure line or the load pressure line of at least one control spool valve by means of a directional control valve. Furthermore, it is also possible that the second load pressure inlet is connected to the second pressure output line, and the load boosting device is optionally connected to the second load pressure inlet or the third load pressure line, specifically by means of a directional control valve. Therefore, the load pressure signal of the subsequent valve assembly is reported through the second load pressure inlet, and this load pressure signal is less than the pressure applied to the corresponding pressure output line.

[0022] This task can also be solved by the hydraulic control device according to claim 14. The hydraulic control device includes the hydraulic valve assembly provided according to the present invention and at least one hydraulic pump. The hydraulic pump is connected to the pre-selection valve, for example, through an input block which has a supply regulator, and the pressure present at the load pressure outlet is sent to the supply regulator in a signal manner. Specifically, the hydraulic pump is designed as a fixed-displacement pump. Alternatively, the hydraulic pump is designed as a variable-displacement pump and is connected to the pre-selection valve, and the pressure present at the load pressure outlet is sent to the variable-displacement pump or the regulator of the variable-displacement pump in a signal manner.

[0023] The present invention will be described in more detail below with reference to the embodiments shown in the drawings. Herein, it is schematically shown that:

[0024] Figure 1 A hydraulic circuit diagram of a hydraulic control device having a hydraulic valve assembly according to a first embodiment of the present invention is shown;

[0025] Figure 2 A hydraulic circuit diagram of a hydraulic valve assembly according to a second embodiment of the present invention is shown;

[0026] Figure 3 A hydraulic circuit diagram of a hydraulic valve assembly according to a third embodiment of the present invention is shown;

[0027] Figure 4 A hydraulic circuit diagram of a hydraulic valve assembly according to a fourth embodiment of the present invention is shown;

[0028] Figure 5 Shows a hydraulic circuit diagram of a hydraulic valve assembly provided according to the fifth embodiment of the present invention;

[0029] Figure 6 Shows a hydraulic circuit diagram of a hydraulic valve assembly provided according to the sixth embodiment of the present invention;

[0030] Figure 7 Shows a hydraulic circuit diagram of a hydraulic valve assembly provided according to the seventh embodiment of the present invention;

[0031] Figure 8 Shows a hydraulic circuit diagram of a hydraulic valve assembly provided according to the eighth embodiment of the present invention.

[0032] Figure 1 Shows a hydraulic circuit diagram of a hydraulic control device 100 having a hydraulic valve assembly 101 provided according to the first embodiment of the present invention. In this embodiment, the hydraulic valve assembly 101 includes a preselection valve 1 and two control spool valves 102 connected downstream thereof. The preselection valve 1 is a proportional spool valve having a switching element 2 formed as a spool valve. In this embodiment, the spool valve 2 can be proportionally deflected from the neutral position N to the first switching position 1S(b) and the second switching position 2S(a). The preselection valve 1 has a pressure input line 3 and two pressure output lines 4, 5, wherein the pressure input line 3 is connected to the first pressure outlet 4 of the two pressure output lines in the first switching position 1S, and is connected to the second pressure outlet 5 of the two pressure output lines in the second switching position 2S. The pressure input line 3 and the two pressure output lines 4, 5 are blocked in the neutral position N. The first group of hydraulic consumption devices (for example, the loading crane or boom of a mobile hydraulic system) is controlled through the first pressure output line 4 (and thus through the control spool valve 102). The second group of hydraulic consumption devices (for example, the support of a vehicle equipped with a mobile hydraulic device) is controlled through the second pressure output line 5.

[0033] In addition, the preselection valve 1 includes a return line 18, which is connected to the second pressure output line 5 in the first switching position 1S, and is connected to the first pressure output line 4 in the second switching position 2S. The return line 18 leads to a common return duct 19, and the control spool valve 102 is also connected and released to the storage tank 107 through the common return duct 19 in a conventional manner.

[0034] The preselection valve 1 includes a first load pressure line 8, which is part of the load pressure signal circuit of the hydraulic valve assembly 101. The first load pressure line 8 includes a load pressure inlet 6 through which the load pressure applied to the control spool 102 can be signaled. The first load pressure line 8 also includes a load pressure outlet 7 through which the maximum load pressure of the hydraulic valve assembly 101 can be further reported to the supply regulator 105. In addition, the preselection valve includes a second load pressure line 9 and a third load pressure line 10. The second load pressure line 9 branches off from the pressure input line 3 upstream of the spool 2 and is connected to the load booster device 11 in the first switching position 1S. The load booster device 11 is connected to the third load pressure line 10, which connects the load booster device 11 to the first load pressure line 8. The second load pressure line 9 is blocked in the neutral position N of the spool 2. Similarly, the second load pressure line 9 is blocked in the second switching position 2S of the spool 2. In the second switching position 2S, the second pressure output line 5 is connected to the first load pressure line 8 by the spool through the joint 12 configured as a reversing valve.

[0035] In this embodiment, the load booster device 11 includes a first hydraulic resistor 14 and a second hydraulic resistor 15. The first hydraulic resistor 14 and the second hydraulic resistor 15 are formed as nozzles, where the first hydraulic resistor 14 is an adjustable nozzle. In the first switching position 1S, a flow rate is applied to the first nozzle by the spool 2, and a flow rate is applied to the second nozzle 15 through the third load pressure line 10. The second nozzle 15 is arranged in the first load pressure line 8 between the joint of the third load pressure line 10 and the load pressure inlet 7. This nozzle chain can be used to increase the load pressure in the system, thereby reducing the preload pressure. For example, the second nozzle 15 can have a (fixed) diameter of 0.6 mm. An increased load pressure signal can be generally generated, depending on how the first nozzle 14 is set. Specifically, by changing the diameter of the first nozzle 14 between, for example, 0.6 mm and 0.8 mm, a load pressure increase of approximately 5 bar to 40 bar can be achieved.

[0036] In addition, Figure 1The hydraulic control device 100 shown has an input block 103, an end plate 106, and a hydraulic pump 104 set as a fixed-displacement pump. The hydraulic pump 104 is connected to the pre-selection valve 1 through the input block 103. The load pressure applied to the load pressure outlet 7 of the pre-selection valve 1 is reported to a supply regulator 105 set as a circulating pressure compensator. The amount of the part delivered by the hydraulic pump 104 is thus directly fed back into the storage tank 107 according to the load pressure. To suppress possible vibrations, the input block 103 also has a damping unit 108, which is connected upstream of the circulating pressure compensator 105. Of course, a variable-displacement pump can also be used instead of the fixed-displacement pump. In this case, the load pressure is directly reported to the pump controller or regulator of the variable-displacement pump.

[0037] For the sake of clarity, only the structure of the hydraulic valve assembly and the end plate 106 will be described in the embodiments described below (where possible).

[0038] Figure 2 A hydraulic circuit diagram of a hydraulic valve assembly 101 provided according to a second embodiment of the present invention is shown. Figure 2 The shown hydraulic valve assembly 101 is different from Figure 1 the shown hydraulic valve assembly in that a fourth load pressure line 13 having a check valve 20 is provided. The fourth load pressure line 13 connects a load booster device 11 to the first load pressure line 8 through a change-over valve 12. The check valve 20 is provided upstream of the connection between the second pressure output line 4 and the change-over valve 12. The change-over valve 12 is in an active state at a second switching position 2S, as observed from the flow direction from the load booster device 11 to the change-over valve 12. The check valve 20 prevents the load pressure signal tapped from the second pressure output line 4 from flowing through the fourth load pressure line 13 to the load booster device 11 at the second switching position 2S. In addition, a second nozzle 15 is provided in the third load pressure line 10.

[0039] Figure 3 A hydraulic circuit diagram of a hydraulic valve assembly 101 provided according to a third embodiment of the present invention is shown. Figure 3 The shown hydraulic valve assembly 101 is different from Figure 2 the shown hydraulic valve assembly in that a change-over valve 21 is provided in the fourth load pressure line instead of the check valve. The change-over valve 21 also prevents the load pressure signal tapped from the second pressure output line 4 from flowing through the fourth load pressure line 13 to the load booster device 11 at the second switching position 2S.

[0040] Figure 4 A fourth embodiment of a hydraulic valve assembly 101 provided according to the present invention is shown. Figure 4 The shown hydraulic valve assembly 101 is compared with the reference Figure 3The hydraulic valve assembly described is different in that the first nozzle 14a of the load boosting device 11 is not arranged downstream of the spool valve 2, but forms part of the spool valve 2. The first nozzle 14a can be formed, for example, by the control edge of the spool valve 2, so as to achieve a higher load pressure as a function of the proportional deflection of the spool valve 2.

[0041] Figure 5 Fig. shows a hydraulic circuit diagram of a hydraulic valve assembly 101 according to a fifth embodiment of the present invention. Different from Figure 4 the hydraulic valve assembly shown, a third switching position 3S(bb) of the spool valve 2 is provided. The third switching position 3S is after the first switching position 1S and corresponds to the "boost" function. As shown in the figure, in the third switching position 3S, the load pressure signal reported through the second load pressure line 9 is increased in the load boosting device 11. For this purpose, the first nozzle 14b is active in the third switching position 3S. The first nozzle 14b is different from the first nozzle 14a that is active in the first switching position 1S in that it has a larger diameter. Therefore, compared with the first switching position 1S, the load pressure increased in the third switching position 3S is greater.

[0042] The following refers to Figure 6 a sixth embodiment of a hydraulic valve assembly 101 provided according to the present invention. This embodiment is different from Figures 1 to 5 the embodiment shown in the structure of the preselector valve 1'. Specifically, the difference lies in that the load boosting device 11' of the preselector valve 1' does not have a hydraulic resistor, but has a profiling valve 17. The profiling valve 17 is connected to the first load pressure line 8 through the third load pressure line 10', where the barrier 22 interrupts the first load pressure line 8 between the junction 12 and the branch of the third load pressure line 10'. Therefore, the load pressure reported through the load pressure inlet 6 is always transmitted through the profiling valve 17. As shown in the figure, in the first switching position 1S of the spool valve 2, the profiling valve 17 "compares" the pressure that dominates in the pressure input line 3 and is reported through the second load pressure line 9 with the load pressure applied to the load pressure inlet 6 and reported through the third load pressure line 10' with respect to the increased load pressure reported in the fourth load pressure line 13'. For this purpose, the profiling valve 17 has a spring device 24, which acts together with the load pressure applied in the third load pressure line 10'. Then, the increased load pressure is reported to the load pressure outlet 7 of the first load pressure line 8 through the fourth load pressure line 13' and the junction 12, depending on whether the increased load pressure is higher than the load pressure present at the load pressure inlet 6. A check valve 20 can be provided in the fourth load pressure line 13' between the profiling valve 17 and the inlet 12 to prevent backflow to the profiling valve 17 in the second switching position 2S.

[0043] In the second switching position 2S of the spool valve 2, the pressure input line 3 is directly connected to the third load pressure line 10, and the second load pressure line 9 is blocked. Therefore, the pump pressure is directly reported as the load pressure.

[0044] Figure 7 The seventh embodiment of the hydraulic valve assembly 101 provided according to the present invention is shown. In this embodiment, an increase in load pressure occurs at both switching positions 1S and 2S of the spool valve 2. The increase in load pressure at the first switching position 1S corresponds to the load pressure increase referred to in Figure 3 the reference. In addition, the preselector valve 1 has a fifth load pressure line 16, which also branches off from the pressure input line 3 upstream of the spool valve 2. The fifth load pressure line 16 is blocked at the first switching position 1S, and the fifth load pressure line 16 is connected to the load boosting device 11 at the second switching position 2S. In this case, the second load pressure line 9 is blocked. In addition, the hydraulic valve assembly 101 includes a second load pressure inlet 23, which is provided in the end plate 106 in this embodiment example. The load pressure of the second set of hydraulic consumption devices is sent in a signal manner through the second load pressure inlet 23, so that the load pressure applied to the load pressure inlet 6 of the preselector valve 1 is always the load pressure of the set of hydraulic consumption devices controlled by the spool valve 2. Therefore, the load pressure of the controlled set of hydraulic consumption devices is increased by the load boosting device 11. Of course, in this regard, it is also conceivable that the configuration of the load boosting device 11 is as Figure 4 or Figure 5 shown. In addition, it is also conceivable to provide a "boost" switching position for the second set of hydraulic consumption devices alternatively or additionally.

[0045] Figure 8 The eighth embodiment of the hydraulic valve assembly 101 provided according to the present invention is shown, in which an increase in load pressure at both switching positions 1S and 2S of the spool valve 2 is also added. In this embodiment, the load boosting device 11' also has a profiling valve 17, which is controlled through the third load pressure line 10', as referred to above in Figure 6Furthermore, the preselector valve 1’ has a fifth load pressure line 16, which branches off from the pressure input line 3 upstream of the spool valve 2. The fifth load pressure line 16 is blocked in the first switching position 1S and is connected to the load boosting device 11 or the profiling valve 17 respectively in the second switching position 2S, in which case the second load pressure line 9 is blocked. The second load pressure inlet 23’ is provided as a branch of the second pressure outlet line 4 and is connected to the third load pressure line 10’ via a reversing valve 25. Thus, the higher load pressure, i.e., the load pressure applied to the load pressure inlet 8 or the second load pressure inlet 23’, is signaled to the profiling valve 17 via the reversing valve 25. Of course, it is also conceivable that the second load pressure inlet is provided in the end plate 106, as referenced Figure 7 as described.

[0046] List of reference numerals

[0047] 1, 1’ Preselector valve

[0048] 2 Switching element / spool valve

[0049] 3 Pressure input line

[0050] 4 (First) pressure output line

[0051] 5 (Second) pressure output line

[0052] 6 Load pressure inlet

[0053] 7 Load pressure outlet

[0054] 8 First load pressure line

[0055] 9 Second load pressure line

[0056] 10, 10’ Third load pressure line

[0057] 11 Load boosting device

[0058] 12 Junction / reversing valve

[0059] 13, 13’ Fourth load pressure line

[0060] 14, 14a - 14d First hydraulic resistor / first nozzle

[0061] 15 Second hydraulic resistor / second nozzle

[0062] 16 Fifth load pressure line

[0063] 17 Profiling valve

[0064] 18 Return line

[0065] 19 Return pipeline

[0066] 20 Check valve

[0067] 21 Changeover valve

[0068] 22 Barrier

[0069] 23, 23’ Second load pressure inlet

[0070] 24 Spring device

[0071] 25 Changeover valve

[0072] 100 Hydraulic control device

[0073] 101 Hydraulic valve assembly

[0074] 102 Control spool valve

[0075] 103 Input block

[0076] 104 Hydraulic pump

[0077] 105 Supply regulator / circulating pressure compensator

[0078] 106 End plate

[0079] 107 Storage tank

[0080] 108 Damping unit

[0081] 1S First switching position

[0082] 2S Second switching position

[0083] 3S Third switching position

[0084] N Middle position

Claims

1. A pre-selection valve (1, 1') for a hydraulic valve assembly (101), said hydraulic valve assembly (101) having a switching element (2), a pressure input line (3), a first pressure output line (4) and a first load pressure line (8), said first load pressure line (8) having at least one load pressure inlet (6) and at least one load pressure outlet (7), wherein said switching element (2) can be switched from a neutral position (N) to a first switching position (1S), wherein said pressure input line (3) is connected to said first pressure output line (4) in said first switching position (1S) of said pre-selection valve (1), characterized in that said pre-selection valve (1) includes a second load pressure line (9), a third load pressure line (10, 10') and a load pressure boosting device (11, 11') for increasing the load pressure, wherein said second load pressure line (9) branches off from said pressure input line (3) upstream of said switching element (2), and said load pressure boosting device (11, 11') is connected to said third load pressure line (10, 10'), said third load pressure line (10, 10') connecting said load pressure boosting device (11, 11') to said first load pressure line (8), wherein said second load pressure line (9) is connected to said load pressure boosting device (11, 11') in said first switching position (1S), and said second load pressure line (9) is blocked in said neutral position (N).

2. The pre-selection valve (1, 1') according to claim 1, characterized in that said pre-selection valve (1, 1') has a fourth load pressure line (13, 13'), said load pressure boosting device (11, 11') being connected to said fourth load pressure line (13, 13'), said fourth load pressure line (13, 13') leading to said first load pressure line (8) at a junction (12).

3. The pre-selection valve (1) according to claim 2, characterized in that said load pressure boosting device (11) includes at least one first hydraulic resistor (14, 14a - 14d) and a second hydraulic resistor (15), said at least one first hydraulic resistor (14, 14a - 14d) having flow applied thereto by said switching element (2), and said second hydraulic resistor (15) having flow applied thereto by said third load pressure line (10).

4. The pre-selection valve (1) according to claim 3, characterized in that said at least one first hydraulic resistor (14, 14a - 14d) is adjustable, and / or said second hydraulic resistor (15) is adjustable.

5. The pre-selection valve (1) according to claim 3 or 4, characterized in that said at least one first hydraulic resistor (14, 14a - 14d) is a nozzle, and / or said second hydraulic resistor (15) is a nozzle.

6. The pre-selection valve (1) according to any one of claims 3 to 5, characterized in that The second hydraulic resistor (15) is arranged in the first load pressure pipeline (8) or the third load pressure pipeline (10).

7. The preselection valve (1’) according to claim 1 or 2, characterized in that the load boosting device (11’) has a profiling valve (17), a barrier (22) is provided in the first load pressure pipeline (8) between the load pressure inlet (6) and the load pressure outlet (7), the third load pressure pipeline (10’) branches off from the first load pressure pipeline (8) between the load pressure inlet (6) and the barrier (22), and the profiling valve (17) is a proportional profiling valve.

8. The preselection valve (1, 1’) according to claim 1, characterized in that the preselection valve (1, 1’) has a second pressure output pipeline (5), the switching element (2) can be switched from the neutral position (N) to a second switching position (2S), the pressure input pipeline (3) is connected to the second pressure output pipeline (5) in the second switching position (2S) of the preselection valve (1, 1’), the second load pressure pipeline (9) is blocked in the second switching position (2S), and the second pressure output pipeline (5) is connected to the first load pressure pipeline (8) in the second switching position (2S).

9. The preselection valve (1, 1’) according to any one of claims 2 to 7, characterized in that the preselection valve (1, 1’) has a fifth load pressure pipeline (16) and a second pressure output pipeline (5), the fifth load pressure pipeline (16) branches off from the pressure input pipeline (3) upstream of the switching element (2), the switching element (2) can be switched from the neutral position (N) to a second switching position (2S), the pressure input pipeline (3) is connected to the second pressure output pipeline (5) in the second switching position (2S) of the preselection valve (1, 1’), the fifth load pressure pipeline (16) is connected to the load boosting device (11, 11’) in the second switching position (2S), the second load pressure pipeline (9) is blocked in the second switching position (2S), and the fifth load pressure pipeline (16) is blocked in the first switching position (1S).

10. The preselection valve (1) according to claim 1, characterized in that the load pressure increased by the load boosting device (11) depends on the magnitude and direction of deflection of the switching element (2) from the neutral position (N).

11. A hydraulic valve assembly (101), characterized in that, Comprising a preselection valve (1, 1’) according to any one of claims 1 to 10 and at least one control spool valve (102) connected to the preselection valve (1, 1’).

12. The hydraulic valve assembly (101) according to claim 11, characterized in that, The hydraulic valve assembly (101) includes a second load pressure inlet (23, 23’).

13. A hydraulic valve assembly (101), characterized in that, Comprising a preselection valve (1, 1') according to claim 8 and at least one control spool valve (102) connected to said preselection valve (1, 1'); said hydraulic valve assembly (101) comprising a second load pressure inlet (23, 23'); said second load pressure inlet (23') being connected to said second pressure output line (5), and said load boosting device (11') being selectively connected to said second load pressure inlet (23') or said third load pressure line (10').

14. A hydraulic control device (100), characterized in that, Comprising a hydraulic valve assembly (101) according to any one of claims 11 to 13 and a hydraulic pump (104) connected to said preselection valve (1, 1').

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