WO2014056592A1

WO2014056592A1 - Open-centre valve block with two pump connections and associated auxiliary sliders on the main sliders

Info

Publication number: WO2014056592A1
Application number: PCT/EP2013/002988
Authority: WO
Inventors: Edwin Heemskerk; Wolfgang Hupp; Enrico Riegel; Waldemar Foth
Original assignee: Robert Bosch Gmbh
Priority date: 2012-10-10
Filing date: 2013-10-04
Publication date: 2014-04-17
Also published as: CN104704174A; DE102012218428A1; CN104704174B

Abstract

The invention relates to a valve block (10) comprising a plurality of main sliders (40), which are supplied in parallel with pressure fluid via a first and a second pump conduit (80; 81), the fluid stream, which flows in from the respective pump conduits (80; 81), being controllable by means of an associated first and second auxiliary slider (60; 61). All main sliders (40) are surrounded by a first and a second annular groove (46; 47) in the housing (20) so as to form an adjustable third main aperture (43) that connects the first annular groove to the second annular groove (46; 47), the first annular groove (46) of a first main slider being connected to the first pump connection, the first annular groove (46) of a second main slider being connected to the second pump connection, the second annular groove (47) of a third and of a fourth main slider being connected to a tank connection on the housing (20), furthermore, the first annular groove (46) of a main slider (40) being connected to the second annular groove (47) of an adjacent main slider (40), the third main aperture (43) becoming smaller when the first or the second main aperture (41; 42) of the same main slider (40) becomes larger.

Description

Open-center valve block with two pump connections and assigned auxiliary slides on the main slides

The invention relates to a valve block according to the preamble of claim 1, which is particularly intended for use in a hydraulic excavator.

From EP 791 754 B l a valve block is known, which is intended for use in a hydraulic excavator. The valve block comprises a housing in which for each consumer or each axis of movement of the hydraulic excavator a

Main slider is taken linearly movable in a transverse direction. In this case, the main slide with respect to a longitudinal direction which is perpendicular to the transverse direction, arranged side by side. In the housing, a first and a separate second pump channel are provided, each extending substantially over the entire length of the housing. The first and the second pump channel are connected via an associated first and second pump port to an associated first and second pump having an adjustable displacement volume.

Each main spool forms with the housing a first and a second main panel, each connected to an associated working port. At the two working ports, which are assigned to a main spool, is one each

Consumer of the hydraulic excavator connected. Through the first and the second main panel, the amount of pressure flowing under pressure to the consumer

Hydraulic fluid controlled. In this case, the first and the second main panel are each assigned opposite directions of movement of the consumer.

Accordingly, either the first or the second main panel is opened in each case.

Some main pushers are associated with a first and a second linearly movable auxiliary slide. The first auxiliary slider defines an adjustable first auxiliary panel, via the first pump channel is connected in parallel with the first and second main panels. The second auxiliary slider defines an adjustable second auxiliary orifice, via which the second pump channel is connected in parallel with the first and the second main panel. It can be determined via the first and the second auxiliary diaphragm which of the two pumps supplies the associated consumer with pressurized fluid, in particular hydraulic oil. By adjusting the cross-sectional area of the first and second auxiliary orifice, it can be determined which amount of fluid is conveyed by the first or the second pump to the relevant axis. The first and the second auxiliary diaphragm are preferably part of a

Proportional valve, as it is known for example from US 4,779,836 A I, so that a control of the volume flow can take place.

The disadvantage of the known control block is that pressure peaks can occur. These arise when a main slide is moved from an open position very quickly to the closed position, wherein an open position is to be understood a position in which the first or the second main panel is open. The control of the pumps reacts to the reduced volume flow requirement by reducing the respective

Displacement volume, but they need this for a certain time. In this short time, the delivery pressure of the pump increases very sharply, resulting in a significant mechanical load on the entire hydraulic system. The pressure peaks are clearly audible to the excavator driver and significantly reduce the life of the excavator. In EP 791 754 B l attempts to remedy this problem in that the first and the second pump line are connected via a respective relief valve to the tank. When closing a main spool, this unloading valve is opened to discharge the pumped excess quantities into the tank. But even this relief valve does not open fast enough to completely avoid pressure spikes. The object of the invention is to avoid such pressure peaks. Next, a valve block is to be specified, which is particularly compact and which can be flexibly adapted to different conditions of use with a particularly large number of identical parts.

According to the independent claim, this object is achieved in that all main spool are surrounded by a first and a second annular groove in the housing to form an adjustable third main aperture, which connects the first with the second annular groove, wherein the first annular groove of a first main spool with the first pump port is connected, wherein the first annular groove of a second main spool is connected to the second pump port, wherein the second annular groove of a third and a fourth main spool are connected to a tank port on the housing, wherein, moreover, the first annular groove of a main spool with the second annular groove an adjacent main slide is connected, wherein the third main aperture decreases when either the first or the second main aperture is increased at the same main spool. This ensures that the pressure fluid delivered by both pumps can flow to the tank connection during a fast closing movement of a main spool valve. It can no longer happen that the pressure fluid builds up on a main slide. Accordingly, pressure peaks are avoided. Preferably, the flow rate of the pumps is reduced as it flows through the first and second annular grooves to save energy. Due to the rigid mechanical connection between the first and second

Main shutter and the third main panel is a time delay between the opening and closing of said panels excluded.

The third main diaphragm is preferably formed by the series connection of two separate diaphragms, one of these diaphragms being reduced when the first or the second main diaphragm is enlarged. The main spools are preferably formed in one piece.

In the dependent claims advantageous refinements and improvements of the invention are given. The first and second main spools may be disposed immediately adjacent to each other, with the third and fourth main spools having only a single immediately adjacent main spool. This results in a particularly simple constructed valve block, the housing can be formed with many identical secondary bodies. If the first and second main spools are not directly adjacent, additional main spools must be connected to the tank port to allow the pressure fluid to drain into the tank. The third and fourth main pushers then have a single immediately adjacent main pusher when located at the two ends of the series of side-by-side main pushers.

Allen main slides may be associated with a substantially U-shaped channel in the housing having a first and a second leg and a base, wherein the first auxiliary slider at the free end of the first leg and the second auxiliary slider is connected to the free end of the second leg. Through the U-shaped channel, the parallel connection between the first and second main aperture and the first and second auxiliary aperture is established. The arrangement of the auxiliary slide at the free ends of the legs makes it possible to arrange the auxiliary slide on opposite sides of the housing, so that they can be mounted easily and space-saving. The auxiliary slides are preferably movable in the transverse direction.

The first main panel can be in the middle of the first leg and the second

Main panel in the middle of the second leg to be connected to the U-shaped channel to the parallel connection to the first and second

To make auxiliary panel. The base of the U-shaped channel is preferably arranged next to the associated main slide and extends in the transverse direction in order to save installation space. The main panel is then connected in the middle of the leg when it is located at least 20% of the length of the leg concerned away from its two ends. The first and second annular grooves may be disposed between the first and second legs of the U-shaped channel. As a result, a valve block is created, which takes up very little space in the transverse direction.

The first and second pump channels may be disposed between the first and second legs adjacent the main slides. Such a valve block is particularly space-saving in the transverse direction. Preferably, it is thought that

Auxiliary slide, which the connection between the pump channels and the

Make legs to arrange in the transverse direction to both sides next to the U-shaped channel, as these can be very easily mounted there.

From the base of the U-shaped channel, a side channel may branch off transversely, wherein the first and the second pump channel are arranged on both sides next to the side channel. This valve block is also particularly space-saving in the transverse direction.

A first and a second tank channel may be provided in the housing, each extending in the longitudinal direction substantially over the entire length of the housing, wherein they are connected to the tank connection, wherein the first and the second tank channel with respect to the transverse direction on opposite sides next the U-shaped channel are arranged, each main slide with the housing forms a fourth and a fifth adjustable main panel, wherein the fourth

Main panel connects the first tank channel with the working port, which is associated with the first main panel, wherein the fifth main panel connects the second tank channel with the working port, which is associated with the second main panel. Via the first and the second tank channel, the pressure fluid flowing back from the hydraulic consumers at the working connections should be led into the tank. With the fourth and the fifth main orifice, the back-flowing pressure fluid is throttled so that no cavitation occurs when pulling loads on the pressure side. The proposed arrangement of the tank lines results in a particularly space-saving in the transverse direction valve block, the housing can be easily produced by casting. Preferably, the third and the fourth are thought of Main slide to connect via the first and the second tank channel with the tank connection.

The housing may comprise a one-piece base body and at least two identical integral body parts abutting against each other at planar contact surfaces which are oriented perpendicular to the longitudinal direction, wherein a single main slider is received in each auxiliary body, wherein a first and a second auxiliary slider are installed in each secondary body can be. Such valve blocks in disc design are basically known. In excavator controls yet one-piece housings are used because the different axes are constructed very differently. In the valve block according to the invention, the different requirements of the individual consumers can be met simply by the fact that either the auxiliary slides are used or not. If not, a blind plug is installed in the mounting hole for the auxiliary slides, which either permanently blocks the fluid flow or releases it permanently. In this way, the vast majority of the excavator axles can be realized in the form of a secondary body, which is small and therefore can be produced inexpensively in the casting process. The main body is preferably provided with only two or three main slides, so that even this can be made small and inexpensive to produce in the casting process. It should be noted that a cast housing after casting must be cooled more slowly, the larger its volume. It is desirable that the temperature of the casting during cooling over the entire volume of the cast body is substantially constant, so that a voids formation is avoided. The costs of the casting process are the lower, the faster the casting can be cooled.

The first and the second main spool may be arranged in the base body, wherein the first and the second pump channel between the first and the second main spool are connected to the respectively associated first or second pump port. The base body must be formed differently from the secondary bodies anyway, so that there the connections of the first and the second

Main slide and the pump channels to the ■ pump connections easily realized can be. By including at least two main slide in the body, the lateral contact surfaces on the body can be identical to those formed on the secondary bodies, so that the secondary body can be easily grown on the body.

In the housing, preferably in the main body, a first and a second linearly movable pump slide are received, wherein the first annular groove of the first main spool via the first pump spool to the first pump port is connected, wherein the first annular groove of the second main spool via the second pump spool with the second Pump connection is connected. Preferably, the first and second pump spools respectively define a first and a second adjustable pump orifice over which said connection is made. With the pump slide can be achieved that the first and the second pump can each promote common to all main valves. For this purpose, the pump slide are controlled substantially proportional to the main slide over which the largest fluid flow to flow. As a result, the pressure fluid required by both pumps can no longer flow away into the tank via the first and second annular grooves, and a pressure builds up in both pump channels. With the appropriate proportionality factor, the desired behavior with regard to the pressure build-up can be adjusted. As soon as the third main orifice in question is sufficiently closed to maintain the pressure in the pump channel, the orifice on the pump slide is reopened a little, so that when the present main slide closes, the pressure fluid coming from the pump flows through the first and second annular grooves into the pump Tank can drain.

The invention will be explained in more detail below with reference to the accompanying drawings. It shows:

1 is a circuit diagram of a valve block according to the invention in the region of

Basic body of the housing; 2 is a circuit diagram of the valve block in the region of the secondary body of the housing, which are mounted on the left in FIG. 1 on the main body.

3 is a circuit diagram of the valve block in the region of the secondary body of the housing, which are mounted on the right in FIG. 1 to the main body; and a rough schematic cross section of the valve block according to a first embodiment, wherein the sectional plane through the center axis of a main slide.

Fig. 5 is a rough schematic cross section of the valve block according to a

second embodiment, wherein the cutting plane passes through the central axis of a main slide. Fig. 1 shows a circuit diagram of a valve block 10 in the region of the main body 21 of the housing 20. The main body 21 is integrally made of cast iron in one

Casting process made with lost cores. It has two opposite, planar contact surfaces 23, to which the with reference to FIGS. 2 and 3

described secondary body of the housing 20 are grown. The parallel

Touch surfaces 23 are aligned perpendicular to a longitudinal direction 12.

The main body 21 has a first and a second pump connection 25; 26 and a tank connection 7. To the pump ports 25; 26, a first and a second pump 16; 17 connected, each one adjustable

Have displacement volume. The pumps 16; 17 suck pressurized fluid,

in particular hydraulic oil from a tank 18, wherein pressurized fluid over the

Tank connection 27 flows back into the tank 18.

The displacement volume of the pumps 16; 17 can be adjusted hydraulically or electrically, preferably the control method "Positive Control" is used. In this case, the displacement volume is increased, for example, proportionally to the control signal of that main slide 40, the most open is. If a plurality of main spool 40 are open at the same time, but also the position of the less widely opened main spool 40 can be taken into account in the adjustment of the displacement volume. The reference numeral 40 is also the main slide with the reference numeral 40a; 40b; 40c; 40d addressed.

The tank connection 27 is via a check valve 93 with a first and a second tank channel 82; 83, which extend parallel to the longitudinal direction 12 substantially over the entire length of the housing 20. For this purpose, enforce the tank channels 82; 83 all contact surfaces 23 between the main body 21 and the secondary bodies. The first and second tank channels 82; 83 are over the

Connecting line 94 directly connected. At the two

opposite ends, the second tank channel 83 is closed by means of an associated separate end plate (Figures 2 and 3, no. The first tank channel 82 is connected to the second ring groove of the third and fourth main spools (FIGS. 2 and 3, Nos. 40c, 40d) via the end plate (FIGS. 2 and 3, No. 28).

The first pump port 25 is directly connected to a first pump channel 80, wherein the second pump port 26 is directly connected to a second pump channel 81. The pump channels 80; 81 extend parallel to the longitudinal direction 12 substantially over the entire length of the housing 20, wherein they at the two opposite ends with the already mentioned

End plates (Figures 2 and 3, No.28) are closed. The first and the second

Pump channel 80; 81 are each connected via an associated primary pressure relief valve 15 to the first tank channel 82. The primary pressure relief valves 15 are set, for example, to 400 bar, so that bursting of the valve block 10 by an excessive delivery pressure of the pump 16; 17 is excluded.

In the main body 21 are a first and a second main spool 40a; 40b taken linearly movable. The movement of the main slide 40 takes place in a transverse direction 1 1, which is aligned perpendicular to the longitudinal direction 12. The essentially rotationally symmetrical main slides 40 are in the longitudinal direction 12 arranged side by side, wherein the central axes are preferably in a common plane.

Between the first and second main spools 50a; 50b are first and second pump shifters 70; 71 arranged. The first pump spool 70 connects the first pump port 25 to the first annular groove of the first main spool 40a. The second pump spool 71 connects the second pump port 26 with the first annular groove of the second main spool 40b. The pump shifter 70; 71 each define an adjustable pump orifice, being pressed by a spring into a fully open position. By means of an electrical control both pump slide 70; 71 pressed into a closed position. In this case, the pump slide 70; 71, for example, proportional to the most widely opened main spool 40 is operated in the closing direction and that until its third main panel is almost completely closed. Thereafter, the aperture of the pump slide 70; 71 again slightly open so that the inventive

Prevention of pressure peaks can take place. This can be done by appropriate electrical control of the pump slide. But it can also be thought of pump slide 70; 71 to use with three switching positions, the aperture moves sequentially from a fully open to a closed and back to a slightly open position when the relevant pump slide 70; 71 is moved.

To the two working ports 24 of the first main spool 40a, for example, the boom of an excavator as a consumer 13 is connected. The two

Working ports 24 are secured by a pressure relief valve 14 against overpressure, which, if necessary, a connection to one of the tank channels 82; 84 produces.

The first main slide 40a is connected via a first auxiliary slide 60 to the first pump channel 80 and via a second auxiliary slide 61 to the second

Pump channel 81 connected. The auxiliary slide 60; 61 each define an adjustable auxiliary orifice, by means of which it is possible to control which fluid flow from the first or second pump channel 80; 81 to flow to the first main spool 40a. The auxiliary slide 60; 61 are preferably part of a proportional valve embodied, for example, in accordance with US 4 779 836 AI, the entire contents of which are incorporated herein by reference. The said proportional valve can also be designed as a slide valve. Said proportional valve is preferably controlled by a pilot valve which is electrically actuated.

The first main slide 40a is pressed by two opposing springs in a central position, wherein it can be moved out with a hydraulic drive from this central position to move the associated consumer 13 in motion.

The areas of the housing 20 immediately around all main spool 40 are identical. In particular, everywhere are the receiving bores for the pressure relief valves 14 and the first and second auxiliary slide 60; 61 provided. However, dummy plugs (Figures 2 and 3, Nos. 90, 91, 92) may be inserted in individual ones of these receiving bores. These blind plugs can interrupt the connection in question 90 completely open in one direction 91 or completely open in both directions 92. The main slide 40; 40a - 40d are in the

Essentially identical. Differences arise mainly with regard to the fine-control notches, which are adapted to the corresponding consumers.

Further, reference should be made to the connecting channels 84, which connect the first annular groove of a main slide 40 with the second annular groove of an adjacent Hautschiebers 40. The connecting channels 84 in each case enforce an associated contact surface 23 between the main body 21 and the secondary bodies.

FIG. 2 shows a circuit diagram of the valve block 10 in the area of the secondary body 22 of the housing 20, which are attached to the main body 21 on the left in FIG. The

one-piece sub-body 22 are each formed identically, wherein they rest with flat contact surfaces 23 on the adjacent base body 21 and sub-body 22. The contact surfaces 23 are aligned perpendicular to the longitudinal direction 12. At the contact surface of the last secondary body 22, the already mentioned end plate 28 is grown.

For the internal structure of the secondary bodies 23, reference is made to the above statements on the first main slide (Fig. 1, No. 40a) and the comments on Figs. The secondary body 22 are formed so far identical with the corresponding region of the body.

To the secondary body 22 shown in FIG. 2, for example, the spoon and one of the two traction drives of the excavator can be connected as a consumer 13. Another secondary body 22 is provided only when needed when the excavator has more consumers 13.

As far as a consumer 13 only from either the first or the second pump 25; 26 to be supplied, the first and the second auxiliary slide 60; 61 by two dummy plugs 90; 92 are replaced, of which one 92 a permanent one

Fluid passage allows, with the other 90 blocks the flow of fluid permanently.

FIG. 3 shows a circuit diagram of the valve block 10 in the region of the secondary bodies 22 of the housing 20, which are mounted on the main body 21 on the right in FIG. The one-piece sub-body 22 are again formed identical to the other sub-bodies 22 on the valve block 10, wherein they are installed rotated by 180 ° to the sub-bodies in Fig. 2, so that the annular grooves of the main slide 40 in the

are interconnected in the manner according to the invention. To the two shown in Fig. 3

Secondary body 22, for example, the other of the two travel drives and the rotary drive of the superstructure of the excavator as a consumer 13 is connected.

The right in Fig. 3 consumer 13 is connected only to the second pump channel 81. In the receiving bore, which is provided for the first auxiliary slide 60, therefore, a blind plug 90 has been used, which corresponds to the corresponding

Fluid passage permanently locks. In the receiving hole for the second Auxiliary plug was a blind plug 91 is used with a check valve, so that the pressurized fluid exclusively from the second pump to the assigned

Consumers 13 can flow.

4 shows a roughly schematic cross section of the valve block 10 according to a first embodiment, wherein the sectional plane extends through the central axis 50 of a main slide 40. Said central axis 50 defines a transverse direction 1 1, along which the skin slider 40 is linearly movable. The control device for moving the main spool 40 is not shown in FIG. 4.

The present sectional view is a total of mirror symmetry with respect to a plane of symmetry 19 which is aligned perpendicular to the transverse direction 1 1. Of the

Main slide 40 is shown in a middle position in which the associated consumer is stationary. If the said consumer is to be moved, the main slide 40 is moved to the left or right depending on the desired direction of movement. The longitudinal direction 12 is aligned perpendicular to the plane of the Fig. 4.

The skin slider 40 is made of steel and is formed substantially rotationally symmetrical with respect to its central axis 50. He lies with several circumferential ribs 51 on the housing 20 at. The gap between the webs 5 1 and the housing 20 is designed so small that there almost no pressure fluid can pass, while still the mobility of the main spool 40 is ensured. At the various lands 51, a plurality of fine control notches are provided to form the first, the second, the third, the fourth and the fifth main aperture 41-45. The free cross-sectional area of said main apertures 41-45 can be adjusted by displacement of the main slide 40 in the transverse direction 1 1.

In the middle of the housing 20, a first and a second annular groove 46; 47 provided in the housing 20, which rotate around the main slide 40. Farther out is a third and a fourth annular groove 48; 49 provided in the housing 20, which also rotates about the main slide 40. The mentioned annular grooves 46 - 48 form several Control edges, which together with the mentioned Feinsteuerkerben the main apertures 41 - 45 limit.

In the housing 20, a U-shaped channel 85 is provided, which has a base 88 and a first and a second leg 86; 87 has. The base 88 extends parallel to the transverse direction 1 1 and is disposed adjacent to the main slide 40. The legs 86; 87 intersect the main slide 40 between two webs 51 so that there is a connection between the U-shaped channel 85 and the first and second main aperture 41; 42 is given. The third and fourth annular grooves 48; 49 is in each case connected to an associated working port 24, to which in turn a

associated consumer can be connected.

Between the first and second legs 86; 87 of the U-shaped channel 85 are the first and the second pump channel 80; 81 arranged in

Longitudinal 12 extend substantially over the entire length of the housing 20. The first and second pump channels 80; 81 are viewed in cross section circular.

The free end of the first and second legs 86; 87 of the U-shaped channel 54 is respectively a first and a second auxiliary slide 60; 61 assigned, which is linearly movable in the transverse direction 1 1. The auxiliary slide 60; 61 are shown greatly simplified, in particular, was dispensed with the representation of the actuator. As already mentioned, the auxiliary slide 60; 61 may be formed in the form of a proportional valve which is actuated by a pilot valve. The auxiliary slide 60; 61, for example, each formed in the form of a poppet valve, so that in the region of the respective valve seats, a first and a second auxiliary orifice 62; 63 are present, the throttle cross-sectional area by movement of the relevant auxiliary slide 60; 61 can be adjusted. Instead of the seat valve and a slide valve can be used. By the

Auxiliary slide 60; 61 can thus be controlled, which fluid flow from the first and second pump channel 80; 81 flows into the U-shaped channel 85. With the first and second main aperture 41; 42 can then be controlled to which Work port 24 of this fluid flow to flow, said fluid flow can be further throttled. In each case, either the first or the second main panel 41; 42 open. In Fig. 4, when the main slider 40 is moved to the right, the first main panel 41 opens, leaving the second main panel 42 closed. In Fig. 4, when the main spool 40 is moved to the left, the second main shutter 42 opens, leaving the first main shutter 41 closed.

The first and second annular grooves 46; 47 are separate first and second fine control notches 43a; 43 b assigned, which are arranged on immediately adjacent webs 5 1, wherein they face each other. The third main shutter 43 is therefore ultimately formed by two separate serially connected shutters, each of the first and second fine control notches 43a; 43b are defined. In the present middle position, the connection from the first to the second annular groove 46; 47 maximum open. When the main spool 40 is displaced to the right, the shutter defined by the first fine control notches 43a closes and thus determines the effective throttle cross-sectional area of the third main shutter 43. If the main spool 40 is displaced leftward, it closes by the second

Fine control notches 43b defined aperture and thus determines the effective

Throttle cross-sectional area of the third main panel 43.

As already mentioned, the first annular groove 46 of a main spool 40 is connected to the second annular groove 47 of an adjacent main spool 40. If all the main slide 40 are in the middle position so that can be the first

Pump connection flowing pressurized fluid from the first (# 40a in Fig. 1) to the third main spool (# 40c in Fig. 2) and from there into the tank. The pressurized fluid flowing from the second pump port may flow from the second (# 40b in FIG. 1) to the fourth main spool (# 40d in FIG. 3) and thence into the tank.

If a main slide 40 is now opened, its third main aperture 43 and the first or the second main aperture 41 shrink; 42 increases, so the Pressure fluid to the relevant working port 24 flows. The pumped by the pumping pressure fluid can therefore always drain independent of the position of the main spool 40, so that it can not come to pressure peaks. Particularly critical here is the case in which a main spool 40 is wide open, the pump in question promotes high performance. Now, if the main spool 40 is closed, it would come without the third main panel 43 to significant pressure peaks.

The first and second tank channels 82; 83 intersect all main slide 40 between two webs 5 1, which are arranged completely outside the main spool 40. Accordingly, there is a connection from the first tank channel 81 to the fourth main panel 44 and from the second tank channel 82 to the fifth main panel 45. The first 41 and the fourth main panel 44 are connected to the same working port 24, wherein either the first 41 or the fourth main panel 44 is opened , The second 42 and fifth main panels 45 are connected to the same workport 24 with either the second 42 or fifth main panel 45 opened.

Between the first and the second tank channel 82; 83 and the respective associated working port 24 is in each case a symbolically represented

Pressure limiting valve 14 connected, which prevents the pressure on

Work connection exceeds a predetermined limit. The

Pressure relief valves 14 are preferably designed in a cartridge design, so that they can be easily installed in a matched receiving bore in the housing 20.

Fig. 5 shows a rough schematic cross section of the valve block according to a second embodiment, wherein the sectional plane extends through the central axis of a main slide. The second embodiment is identical to the first embodiment except for the differences described below, so that in this regard reference is made to the embodiment of FIG. 4. The same parts are provided with the same reference numerals. The base 88 of the U-shaped channel 85 is disposed on the side remote from the working ports 24 side of the main spool 40. From the base 88, a single side channel 89 branches off transversely, which is arranged in the plane of symmetry 19. Right and left of the side channel 89, the first and the second pump channel 80; 81 arranged. The first pump channel 80 is connected to the side channel 89 via the first auxiliary screen 62 on the first auxiliary slider 60. The second pump channel 81 is connected via the second auxiliary orifice 63 on the second auxiliary slide 61 to the side channel 89.

LIST OF REFERENCE NUMBERS

10 valve block

1 1 transverse direction

12 longitudinal direction

13 consumers

14 pressure relief valve

15 primary pressure relief valve

16 first pump

17 second pump

18 tank

19 symmetry plane

20 housing

21 basic body

22 secondary body

23 touch surface

24 work connection

25 first pump connection

26 second pump connection

27 tank connection

28 end plate

40 main slide

40a first main slide

40b second main slide

40c third main slide

40d fourth main slide 41 first main panel

42 second main panel

43 third main panel

43a first fine control score

43 b second fine control score

44 fourth main panel

45 fifth main panel

46 first annular groove

47 second annular groove

48 third annular groove

49 fourth annular groove

50 central axis of the main slide

51 web of the main slide 60 first auxiliary slide

61 second auxiliary slide

62 first auxiliary panel

63 second auxiliary shutter 70 first pump slide

71 second pump slide

80 first pump channel

81 second pump channel

82 first tank channel

83 second tank channel

84 connecting channel between the first and second annular groove of two main slide

85 U-shaped channel

86 first leg of the U-shaped channel

87 second leg of the U-shaped channel

88 base of the U-shaped channel 90 blind plugs, closed

91 blind plugs; check valve

92 blind plugs, open

94 Connecting channel between the first and second tank channels

Claims

claims

Valve block (10) having a housing (20) in which a plurality of in a transverse direction (1 1) linearly movable main slide (40) are taken along a perpendicular to the transverse direction (1 1) extending longitudinal direction (12) are arranged side by side, wherein the housing (20) a first (80) and a separate second pump channel (81) are provided, which extend in the longitudinal direction (12) substantially over the entire length of the housing (20), wherein the first pump channel (80) with a the first pump port (25) and the second pump channel (81) are connected to a second pump port (26) on the housing (20), each main pusher (40) having a first and a separate second main variable orifice (41; 42), wherein the first and the second main panel (41; 42) are each connected to an associated working port (24) on the housing, wherein at least two, preferably all main valves (40), a separate first and a separate second linearly movable auxiliary slide (60; 61), the first auxiliary slide (60) defining an adjustable first auxiliary orifice (62) via which the first pumping passage (80) is connected in parallel with the associated first and second main orifice (41; 42), the second auxiliary slide (62). 61) defines an adjustable second auxiliary orifice (63) via which the second pumping channel (81) is connected in parallel with the associated first and second main orifice (41; 42),

characterized in that all the main slides (40) are surrounded by a first and a second annular groove (46; 47) in the housing to form an adjustable third main aperture (43) connecting the first to the second annular groove (46; 47) wherein the first annular groove (46) of a first main spool (40a) is connected to the first pump port (25), the first annular groove (46) of a second main spool (40b) being connected to the second pump port (26), the second one Ring groove (47) of a third and a fourth (40c, 40d) with a tank connection (27) on the housing (20) are connected, wherein moreover the first annular groove (46) of a main slide (40) with the second annular groove (47) of a adjacent main slide (40) is connected, wherein the third main orifice (43) decreases when either the first or the second main orifice (41; 42) on the same main spool (40) is increased.

Valve block according to claim 1,

characterized in that the first and second main spools (40a; 40b) are disposed immediately adjacent to each other, the third and fourth main spools (40c; 40d) having only a single immediately adjacent main spool (40).

Valve block according to one of the preceding claims,

characterized in that all main slides (40) in the

A substantially U-shaped channel (85) is associated with the housing (20) having first and second legs (86, 87) and a base (88), the first auxiliary slider (60) being at the free end of the first leg (8). 86) and the second auxiliary slide (60) at the free end of the second leg (87)

connected.

Valve block according to claim 2,

characterized in that the first main panel (41) in the middle of the first leg (86) and the second main panel (42) in the middle of the second leg (87) to the U-shaped channel (85) is connected.

Valve block according to claim 3 or 4,

characterized in that the first and second annular grooves (46; 47) are disposed between the first and second legs (86; 87) of the U-shaped channel (85). Valve block according to one of claims 3 to 5,

characterized in that the first and second pump passages (80; 81) are located between the first and second legs (86; 87) adjacent to

Main slides (40) are arranged.

Valve block according to one of claims 3 to 5,

characterized in that a side channel (89) branches off transversely from the base (88) of the U-shaped channel (85), the first and the second

Pump channel (80; 81) are arranged on both sides next to the side channel (89).

8. Valve block according to one of claims 3 to 6,

characterized in that in the housing (20) a first and a second tank channel (82; 83) are provided, each extending in the longitudinal direction (12) substantially over the entire length of the housing (20), wherein it communicates with the tank connection (27), wherein the first and the second tank channel (82; 83) with respect to the transverse direction (1 1) at

each main slider (40) forms with the housing (20) a fourth and a fifth main variable orifice (44; 45), the fourth main orifice (44) defining the first tank channel (82) connects to the working port (24) associated with the first main panel (41), the fifth main panel (45) connecting the second tank channel (83) to the working port (24) associated with the second main panel (42) is.

9. Valve block according to one of the preceding claims,

characterized in that the housing (20) comprises an integral body (21) and at least two identical integral body parts (22) abutting against each other at planar contact surfaces (23) which are oriented perpendicular to the longitudinal direction (12) In addition to body

(22) a single main spool (40) is received, wherein in each

Secondary body (22), a first and a second auxiliary slide (60; 61) can be installed.

Valve block according to claim 9, referring back to claim 2,

characterized in that the first and second main spools (40a-40b) are disposed in the base body (20), the first and second pump channels (80; 81) interposed between the first and second main spools (40a; 40b) associated first or second pump port (26; 27) are connected.

Valve block according to one of the preceding claims,

characterized in that in the housing (20), preferably in the base body (21), a first and a second linearly movable pump slide (70; 71) are accommodated, wherein the first annular groove (46) of the first

Main slide (40a) via the first pump slide (70) to the first pump port (25) is connected, wherein the first annular groove (47) of the second main spool (40b) via the second pump spool (71) with the second pump port (26) is connected ,