EP3002462A1 - Hydraulic control system - Google Patents

Abstract

To a hydraulic control system for a working hydraulics of a land or building economy vehicle in its rear and / or front an attachment can be coupled, which has a hydraulic actuator and / or drive system. In this case, a hydraulic system of the respective attachment by means of a hydraulic coupling system with a hydraulic circuit of the working hydraulics can be connected, and it is both within the hydraulic circuit and within the hydraulic system hydraulic consumers each associated with control devices functionally. In the hydraulic circuit, a variable displacement pump is provided whose delivery volume is controllable in dependence on a load pressure (p LS) of the hydraulic consumers of the hydraulic circuit and the hydraulic system associated with the attachment. In this case, at least one hydraulic load signal line (17) is provided as part of the regulation of the variable displacement pump, which is connected to the control units, and it is between a first line section (38) of the load signal line (17) which is connected to the control devices arranged within the hydraulic circuit , and a second line section (48) of the load signal line (17), which is connected to the control units of the hydraulic system, a control valve (37). By means of this control valve (37) is generated by one of the control units of the hydraulic system load pressure signal (p LS48) by means of an increase in pressure from a pressure line (10) amplified. To make the control valve structurally favorable and to arrange with simple means in the work hydraulics, the hydraulic consumers of the attachment are operated delay and at the desired operating speed, the control valve (37) has a load signal amplification valve unit (39), which serves as a directional control valve ( 41) is formed, wherein this Nutzanschlüsse for the pressure line (10), the first line section (38) and a return line (11) and on the one hand on the load pressure (p LS38) of the first line section (38) is controlled, and wherein the control valve (37) has an end face via a biasing spring (47) on a valve spool (45) of the directional control valve (41) engaging biasing stage (40) which is acted upon by a load pressure (p LS48) of the second line section (48) and the load signal amplifying valve unit (39) on the other hand controls.

Description

The invention relates to a hydraulic control system for a working hydraulics of a land or building economical vehicle to which vehicle in its rear and / or front area a hydraulic adjusting and / or drive system having attachments can be coupled, wherein a hydraulic system of the respective attachment by means of a hydraulic Coupling system with a hydraulic circuit of the working hydraulics can be connected and both within the hydraulic circuit and within the hydraulic system each hydraulic control units are assigned functionally, wherein in the hydraulic circuit, an adjustable hydraulic pump is provided whose delivery volume in response to a load pressure of the hydraulic load of the hydraulic circuit and the Anbaugerät associated hydraulic system is regulated, wherein in the context of the control of the hydraulic pump, at least one hydraulic load signal line is provided, which composites with the control units n, and wherein between a first line section of the load signal line, which is connected to the arranged within the hydraulic circuit controllers, and a second line section of the load signal line, which is connected to the control units of the hydraulic system, a control valve is arranged, which is one of the control units the hydraulic system generated load pressure signal amplified by means of a pressure increase from a pressure line.

Furthermore, the invention also relates to a control valve for a designed as a closed-center system working hydraulics of a land or building economics usable machine, which amplifies a one or more control units in a load signal line generated load pressure signal by means of a pressure increase from a pressure line.

In the past, a corresponding working hydraulics of a vehicle that can be used for agricultural or construction purposes has mostly been designed as an open-center system in which a constant-displacement pump, ie even if none of the hydraulic consumers is supplied with hydraulic power, has a constant volume flow with it promotes maximum power consumption. The consequence of this is that a high power loss and a correspondingly high heating of the pressure medium occur.

For this reason, closed-center systems with hydraulic pumps variable in their delivery volume are now mostly used, which supply only a demand-based volume flow. In this case, the hydraulic pump designed as a variable displacement pump is controlled by a so-called load-sensing system, which consists of a load signal line and a pressure compensator associated with the adjustment of the hydraulic pump. About the load signal line of each of the control valves, which are assigned to the individual consumers, the highest load pressure reported to the pressure compensator and the hydraulic pump only builds up the load pressure plus a low pressure surplus.

This will allow the variable displacement pump to be returned to a stand-by condition when the control valves are in their neutral position and do not demand a flow. The pump pressure settles so that the pressure difference Δp _LS between the load pressure p _{LS of} the pressure compensator and the delivery pressure of the pump p _p always remains the same. If one or more valves are actuated, the pressure is passed on via the load signal line to the pressure compensator, which determines the energy requirement of the system by comparing the load pressure p _LS and the pump pressure p _p . Pump pressure and pump flow are always automatically adapted to the respective requirements.

The respective highest load pressure p _LS is reported by the corresponding control valve to the hydraulic pump, whereupon the hydraulic pump builds up only the load pressure plus a low pressure surplus (rule - Δp). In a parallel operation of multiple consumers, the pump flow is divided by the use of so-called section pressure compensators regardless of the various load pressures on the consumer, as it corresponds to the ratio of the opening cross-sections of the control valves.

To the hydraulic circuit of the working hydraulics of the agricultural or building economy vehicle can be coupled via so-called remote terminals work equipment, which is at least two connections, namely for a Pressure line and a non-pressurized return line. In the case of agricultural vehicles, such remote connections are provided, for example, in their front and rear areas, in which there is also a three-point power lift for receiving the respective implement. The coupled implement may include hydraulic consumers in the form of hydraulic cylinders or hydraulic motors, each operating control valves associated therewith. The connection of the tools is also referred to as a power beyond connection.

If this power beyond connection is combined with a load sensing system, the power beyond connection system will be extended with a connection for a load signal line leading to the implements control units. This ensures that the variable displacement pump of the agricultural vehicle supplies the control valves of the attachment only with pressure medium when the corresponding hydraulic power is needed. Therefore, this system regulates the flow rate and pressure to meet the needs. In the load signal line, the load pressure increases when the operator of the implement retrieves one of its hydraulic functions. When using the load-sensing system for a device coupled to the vehicle, however, considerable pressure losses can occur in the connecting elements, so that the control variable for the hydraulic pump Δp _LS collapses. This has the consequence that the variable displacement pump can not provide sufficient volume flow.

A hydraulic control system for a land or building economy vehicle of the type specified in the preamble of claim 1 is known from the DE 11 2004 002 768 B4 known. In the FIGS. 3 to 8 This document discloses a hydraulic control system in which an implement is operated via power beyond ports. In this case, the respective load pressure of the load can be reported as a load-sensing signal via a load signal line to the control system. In addition, it is provided that the control system has means to influence at least one of the load-sensing signals.

In order to change the load-sensing signal so that the consumer or consumers receive a larger flow of oil, resulting in a quick effect of the consumer or the consumer should be one of a compensation valve and a Shut-off valve existing compensator provided. The compensation valve is intended to raise a load sensing pressure applied to it by a fixed amount Δp, the sum of the load sensing pressure and the fixed amount Δp representing the corrected load sensing pressure. The shut-off valve should shut off the compensator when the load-sensing pressure applied to the compensation valve goes against the return line pressure.

It is an object of the present invention to arrange structurally simple means within the hydraulic circuit, by means of which the hydraulic consumers of the attachment are operated without delay and with the desired operating speed. In this case, upon actuation of the control system provided in the hydraulic system of the attachment a precise pressure increase in the regulation of the variable displacement causing load signal line to be achieved.

This object is achieved on the basis of the respective preamble of claims 1 and 2 by their characterizing features. Advantageous embodiments are given in the dependent claims which, taken alone or in combination with each other, may constitute an aspect of the invention.

Thereafter, the control valve has a load signal amplifying valve unit, which is designed as a directional control valve, wherein this Nutzanschlüsse for the pressure line, the first line section and a return line, and is controlled by the load pressure of the first line section, and wherein the control valve is a front side via a biasing spring Having on a valve spool of the directional control valve biasing stage, which is acted upon by a load pressure of the second line section. The biasing stage, which is acted upon by the load pressure from the second line section, thus acts permanently on the biasing spring on the valve spool of the directional control valve. With an increase in the load pressure in the second line section, which signals an actuation of one or more of the control valves of the attachment, the biasing spring is tensioned by means of the applied with this load pressure biasing stage and moved over this, the valve spool of the directional control valve in a position in which from the pressure line Pressure medium is passed with the pump pressure p _p in the first line section of the signal line.

The consequence of this is that the load pressure in this first line section is increased by the amount of the biasing force. The pressure in the first line section is thus regulated via the regulating valve to the value set by the pretensioning spring, the load pressure correspondingly increased via the regulating valve being forwarded to a pressure compensator. This pressure compensator ensures that the pressure difference Δp _LS between the load pressure p _LS and the delivery pressure of the pump p _p always remains the same. In this way, the pressure balance determines the energy requirement of the system by comparing the load pressure p _LS and the pump pressure p _p .

In the present case, ie at an increase in pressure by the control valve in the first line section after a corresponding actuation of the control valve of the attachment, the variable is adjusted to a higher delivery volume due to the increase of the load pressure, so that in a corresponding manner pressure means for a delay-free operation of the corresponding modules of the attachment via hydraulic cylinders or hydraulic motors can be provided.

In contrast, after the DE 11 2004 002 768 B4 a compensator is provided which consists of a compensation valve and a shut-off valve. Neither the compensation valve nor the shut-off valve is arranged between a first line section and a second line section of the signal line. At this point there is only a shuttle valve. Furthermore, the compensation valve is acted upon at one end face with the pump pressure and at the other end side with the load pressure of the signal line. The application of the pump pressure takes place depending on the position of the shut-off valve. From its initial position, in which the compensation valve ensures no pressure increase in the signal line, it is first moved to a middle position in which pressure medium is throttled fed into the entire signal line. Finally, in a third position of the compensation valve, the pressure medium from the pressure line is only fed into the branch of the signal line which leads to the adjustment of the variable displacement pump.

In a further embodiment of the invention, it is provided that the valve slide is acted upon at its side remote from the biasing stage end face with the load pressure of the first line section. The in the first line section at a pressure increase increasing load pressure consequently acts against the force transmitted by the pretensioning stage. Therefore, the slider is moved back from its intended for a pressure increase position as soon as the force resulting from the pressure increase exceeds the force of the biasing spring.

It is further provided that the valve slide has a hydraulic actuation parallel to the pretensioning stage via the load pressure of the second line section. Thus, the valve spool of the directional control valve is piloted parallel to the biasing stage directly with the pressure of the second line section.

In addition, the biasing stage may comprise a longitudinally displaceable sleeve, which is acted upon at a first end side with a load pressure of the second line section and is supported via the biasing spring at an end face of the valve spool of the load signal amplifying unit. At its second line section facing the end of this control sleeve may be provided with a diaphragm, said diaphragm provides on the one hand for the displacement of the control sleeve and on the other hand via a corresponding throttle bore pressure means for direct hydraulic actuation of the valve spool available.

Also on the side facing away from the biasing end side next to the load pressure of the first line section further the valve spool in the direction of the biasing voltage exciting means may be provided. It may be an additional compression spring, via which the valve spool is biased relative to the valve housing. Preferably, a further compression spring is provided within the biasing stage, which is supported on the diaphragm and acts via a piston and a plunger frontally on the valve spool. About this two acting in opposite directions on the valve spool springs this spring centering is effected.

For the direct actuation of the valve spool from the side of the biasing stage, downstream of the diaphragm, a displaceable piston may be provided which acts directly or indirectly on the valve spool. In an indirect application of this piston can go out a plunger, surrounded by the biasing spring is. This plunger is supported at its other end on the facing him face of the valve spool.

In a further embodiment of the invention, it is provided that the load signal amplification valve unit has a 3/2-way valve. In a first position at low load pressure of the second line section and a higher load pressure of the first line section, this 3/2-way valve will shut off the useful connection of the pressure line and connect the first line section to the return line. In a second position of the 3/2-way valve, as it assumes after an increase in the load pressure in the second line section, the pressure line is connected to the first line section to increase their load pressure. The valve spool can also be in a position in which it blocks the first line section both with respect to the pressure line and to the return line.

The first line section can be arranged coaxially to a receiving bore of the valve slide, wherein a connecting piece receives the pressure spring acting on the valve slide. The valve slide in this case preferably has a longitudinal bore, are provided by the two transverse bores with radially outer, circumferential on the circumference of the valve slide grooves. These transverse bores or grooves in the two switch positions explained above must be connected to the pressure connection or to the tank connection of the return line in each case.

Furthermore, the biasing spring should abut with its ends on the first and second spring plates, wherein the first spring plate is slidably disposed together with the control sleeve, wherein the second spring plate engages the front end on the valve spool and is supported radially on the inside of the plunger and radially outward on the biasing spring and wherein second spring plate, facing away from the plunger, engages the valve spool. Thus, both the biasing force of the biasing spring and the hydraulic actuating force of the piston or the plunger is transmitted via the second valve disk. Overall, this results in a favorable spatial arrangement of the valve spool adjusting components.

The pressure increase in the first line section according to the invention adapt to the respective requirements that a biasing spring is used which has a certain spring constant. Accordingly, the adjustment can be made by replacing one bias spring with another having a lower or higher spring constant.

Finally, a housing of the load signal amplifying valve unit and a housing of the biasing stage to be bolted together, with their mounting holes for the valve spool on the one hand and for the biasing spring, the plunger and the control sleeve on the other hand coaxially. It follows that the load signal amplification valve unit and the biasing stage, as already explained, form a common structural unit.

The invention is not limited to the specified combination of the features of the independent claims 1 and 2 with the claims dependent thereon. It also results in ways to combine individual features, as far as they emerge from the claims, the advantages of the claims, the following description of the embodiment or at least from the drawings. The reference of the claims to the drawings by corresponding use of the reference number is not intended to limit the scope of the claims.

Figur 1

ein Hydraulikschema, bestehend aus einem Hydraulikkreis eines land-oder bauwirtschaftlich nutzbaren Fahrzeugs mit einem über Power-Beyond-Anschlüsse ankuppelbaren Hydrauliksystem eines Anbaugeräts,

Figur 2

einen vergrößerten Ausschnitt gemäß II in Figur 1 und

Figur 3

einen Längsschnitt durch ein Regelventil, das aus einer Lastsignal-Verstärkungsventileinheit und einer Vorspannstufe besteht.

For further explanation of the invention reference is made to the drawing, in which an embodiment is shown in simplified form. Show it:

FIG. 1

a hydraulic scheme, consisting of a hydraulic circuit of a land or construction vehicle usable with an attachable via power beyond ports hydraulic system of an attachment,

FIG. 2

an enlarged section according to II in FIG. 1 and

FIG. 3

a longitudinal section through a control valve, which consists of a load signal amplifying valve unit and a biasing stage.

In the FIG. 1 is denoted by 1 a hydraulic circuit, which may be, for example, a working hydraulics of an agricultural tractor or system vehicle. This hydraulic circuit 1 is designed as a closed-center system, wherein the pressure medium from a tank 2 via a variable displacement pump 3, which is preferably designed as axial piston unit according to the bent axis principle, two as a double-acting hydraulic cylinders 4 and 5 trained consumers 6 and 7 supplies. The hydraulic cylinders 4 and 5 are associated with control devices 8 and 9, which are designed as electromagnetically operated, provided with spring centering 4/4-way valves. The hydraulic cylinders 4 and 5 may be provided, for example, each for lifting devices of a front and a rear linkage.

The pressure medium is conveyed by the variable displacement pump 3 via a pressure line 10 to the control units 8 and 9, where it can enter into corresponding positions of these control units 8 and 9 in a return line 11 and thus back into the tank 2. In this position, the respective control units 8 and 9 whose working lines 12, 13, 14 and 15 are shut off.

As already stated, the delivery volume of the variable displacement pump 3 can be adjusted, for which purpose a single-acting adjusting cylinder 16 is provided. In this case, this adjusting cylinder 16 is connected to a load signal line 17 via a pressure compensator 18 and a pressure regulator 19. The load signal line 17 is connected to each of the control units 8 and 9 in such a way that a pressure on the pressure compensator 18 can be passed through it, if via the respective control unit 8 or 9, a pressure medium applied to the hydraulic cylinder 4 or 5.

After FIG. 1 is the variable displacement pump 3 in its standby mode, ie, in a variable displacement pump according to the bent axis principle, the corresponding axial piston unit is in a state with a small swing angle and thus low displacement volume. In this state, the variable displacement pump 3 promotes only a very small amount of hydraulic oil and only builds up a low pressure. The pump pressure p _p settles in such a way that the pressure difference Δp _LS between the load pressure p _{LS of} the pressure compensator 18 and the delivery pressure p _{p of} the variable displacement pump 3 always remains the same.

However, if, as already stated, one of the two or both control devices 8, 9 is actuated, the pressure in the load signal line 17 rises and this increased load pressure p _LS acts on the pressure compensator 18, via which the pressure regulator 19 is piloted. This load pressure p _LS acts in the same direction as a pressure spring 20 provided on the pressure compensator 18, so that the pressure compensator 18 can determine the energy requirement of the system by comparing the load pressure p _LS and the pump pressure p _p . The pump pressure p _p and the pump flow rate are automatically adjusted to the respective requirements. The respective highest load pressure p _LS is thus reported by the respective control unit 8 and / or 9 to the variable displacement pump 3, and this only builds up the load pressure plus a slight pressure surplus (rule - Δp).

Line sections 17a and 17b lead from the load signal line 17 to the respective control device 8 and 9, wherein a change-over valve 21 is arranged between the load signal line 17 and these line branches 17a and 17b. Furthermore, 10 section pressure compensators 22 and 23 are provided in the leading to the control units 8 and 9 sections of the pressure line. These are in a parallel operation of multiple consumers 6, 7 ensure that the pump flow independent of the various load pressures is distributed to the consumers 6, 7, as it corresponds to the ratio of the opening cross-sections of the control units 8 and 9.

Overall, this achieves that the power consumption of the variable displacement pump 3 is permanently adapted to the needs. The efficiency is considerably greater, especially in the fine control range, than in a so-called open center system. The actuating speeds of the consumers 6 and 7 is not influenced by changing load pressures, so that a countersteering is not required.

After FIG. 1 Furthermore, a so-called power beyond connection system 24 is provided which serves for the hydraulic connection of the hydraulic circuit 1 with a hydraulic system 25 of an attachment. For this purpose, the pressure line 10 has a remote terminal 26 labeled P, the load signal line 17 has a remote terminal 27 labeled LS, and the return pipe 11 has a remote terminal 28 labeled T. By coupling the hydraulic system 25 of the attachment corresponding lines with the aforementioned lines 10, 17, 11 are connected. These are in a similar way with 10 ', 17' and 11 ' designated and lead to control units 29 and 30, the consumers 31 and 32 are assigned. The consumer 31 is a double-acting hydraulic cylinder 33, while the consumer 32 is designed as a hydraulic motor 34.

Also in this case, the load pressure in the corresponding section 17 'of the load signal line 17 should be monitored, because even of these controllers 29 and 30 in the event of an adjustment to their working position on the variable displacement pump 3, a higher delivery volume and a higher pressure to be requested. Individual branches of the load signal line 17 'are also associated with shuttle valves 21. In the corresponding branches of the pressure line 10 'are also section pressure compensators 35 and 36th

According to the invention, in a region of the hydraulic circuit 1 adjacent to the power beyond connection system 24, a control valve 37 which, in the event of actuation of the control devices 29 and / or 30, has a load pressure p _LS38 in a first line section 38 of the load signal line 17 connected to the pressure _compensator 18 should increase. This pressure increase is necessary because the pressure losses between the variable displacement pump 3 and the hydraulic system 25 of the attachment due to the hydraulic couplings, hose lines, etc. may be greater than the control variable Δp _LS , so that a maximum flow for the supply of the load 31 and 32 not more can be provided. As continues from the FIG. 1 As can be seen, the control valve 37 consists of a load signal amplifying valve unit 39 and a biasing stage 40. For further explanation of the control valve 37 and its function is to the following Figures 2 and 3 directed.

The FIG. 2 shows an enlarged section of the hydraulic scheme of FIG. 1 , Thereafter, the load valve-boosting valve unit 39 should be designed as a 3/2-way valve 41. In the illustrated switching position, a pressure port 42 of the pressure line 10 is shut off via this 3/2-way valve 41, while a load pressure port 43 of the first line section 38 of the load signal line 17 is connected to a tank port 44 of the return line 11. It is thus a position of the 3/2-way valve 41, in which there is no increase in the load pressure p _LS38 . How continues the FIG. 2 can be removed, is a corresponding valve spool 45 of the 3/2-way valve 41 acted upon at one end face both via a line branch 38 'shown symbolically in the hydraulic diagram with a pressure from the first line section 38 and with the force of a compression spring 46. On the other end of the valve spool 45, the biasing stage 40 acts via a biasing spring 47th

This biasing stage 40 is thereby acted upon by a load pressure p _{LS48 of} a second line section 48 of the load signal line 17. In this second line section 48 there is a load pressure p _LS48 , which in the illustrated position of the valve _slide 45 coincides with the load pressure p _LS38 in the load signal line branch 38. In addition to the frontal loading of the valve spool 45 by means of the biasing stage 40 via the biasing spring 47 and an immediate pressurization of the second line section 48 of the load signal line 17 is provided.

If the 3/2-way valve 41 is transferred via the biasing stage 40 in its second switching position, the pressure port 42 communicates with the load pressure port 43, so that via the pump pressure of the pressure line 10, a pressure increase in the first line section 38 is effected. As already stated, this pressure acts together with the control spring 46 on the end face of the valve spool 45 in the sense of its provision. By the second conduit portion 48 due to an operation of the control devices 29 and / or 30 load caused signal p _LS48 thus leads directly as well as indirectly via the biasing stage 40 and the biasing spring 47 cause the lossy only with low pressure losses pump pressure P _P via the 3 / 2- Directional valve 41, the load pressure p _LS38 in the first line section 38 lifts.

As already stated, the valve spool 45 locks in its normal position the passage of the pressure medium from the pressure line 10 in the first line section 38 of the load signal line 17. With an increase in the load pressure p _LS48 in the biasing stage 40, the biasing _spring 47, the front side of the valve spool 45 is applied tense, whereby the valve spool opens the connection between the pressure port 42 and the load pressure port 43. The pressure p _LS38 in the first line section 38 of the load signal line 17 is thereby increased by the amount of the biasing force, with the result that the pressure p _{LS38 is controlled} at the load pressure _port 43 to the set value. About the first line section 38 of the thus increased load pressure p _{LS38 is forwarded} to the pressure compensator 18 as a control pressure p _LS . Thus, the total pressure level becomes raised by the amount of pressure increase. The pressure increase is adjustable by means of the control spring 46 and the biasing spring 47.

From the FIG. 3 the corresponding design of the control valve 37 shows. Thereafter, the 3/2-way valve 41 of the load signal amplifier unit 39, a housing 49, which is provided with a receiving bore 50 for the valve spool 45. This receiving bore 50 merges into an enlarged bore section 51 into which a housing 52 of the pretensioning stage 40 is screwed. This housing 52 is cylindrical and receives in its interior a control sleeve 53 which is _displaceable in the housing 52 via the load pressure p _LS48 in the direction of the housing 49 of the 3/2-way valve 41. The control sleeve 53 is provided with a diaphragm 54 at its end facing the second conduit section 48. At its other end, a first spring plate 55 is arranged on the control sleeve 53, on which the biasing spring 47 is guided with its one end. The other end of the biasing spring 47 is applied to a second spring plate 56, which is supported with an end facing away from the biasing spring 47 on an end face of the valve spool 45.

In addition to this actuation of the valve spool 45 via the biasing spring 47, an immediate pressure actuation of the valve spool 45 is provided, which is effected by a piston 57 and by a push rod 58 emanating therefrom. An actuating force is transmitted directly to the valve spool 45 via the second spring plate 56 via the piston 57 acted upon by the pressure p _LS48 and the push rod 58.

The valve spool 45 is acted upon on its side facing away from the second spring plate 56 front side with the pressure p _LS38 from the first conduit portion 38 and with the force of the compression spring 46th The valve spool 45 has a longitudinal bore 59, two mutually offset in the axial direction of the transverse bores 60 and 61 and radially outwardly provided on these annular grooves 62 and 63. In the FIG. 3 the valve spool 45 is in a position between its two positions, ie, the valve spool 45 is just moved over the biasing stage 40 in the direction of pressure increase, then then in this switching position of the pressure port 42 via the annular groove 62, the transverse bore 60 and the longitudinal bore 59 with the load pressure connection 43 is connected, so that the load pressure p _{LS38 is increased} according to the pressure line 10.

reference numeral

1

hydraulic circuit

2

tank

3

variable

4

hydraulic cylinders

5

hydraulic cylinders

6

consumer

7

consumer

8th

control unit

9

control unit

10

pressure line

10 '

pressure line

11

Return line

11 '

Return line

12

working line

13

working line

14

working line

15

working line

16

adjusting cylinder

17

Load signal line

17 '

Load signal line

17a

Line branch of 17

17b

Line branch of 17

18

pressure compensator

19

pressure regulator

20

Compression spring of 18

21

shuttle valve

22

Section pressure compensator

23

Section pressure compensator

24

Power beyond connection system

25

hydraulic system

26

Remote connection P

27

Remote connection LS

28

Remote connection T

29

control unit

30

control unit

31

consumer

32

consumer

33

double-acting hydraulic cylinder

34

hydraulic motor

35

Section pressure compensator

36

Section pressure compensator

37

control valve

38

first line section of 17

38 '

leg

39

Load signal amplification valve unit

40

bias stage

41

3/2-way valve

42

pressure connection

43

Load pressure port

44

tank connection

45

valve slide

46

compression spring

47

biasing spring

48

second line section of FIG. 17

49

Housing of 39

50

location hole

51

Extended bore section

52

Case of 40

53

control sleeve

54

cover

55

first spring plate

56

second spring plate

57

piston

58

pushrod

59

longitudinal bore

60

cross hole

61

cross hole

62

ring groove

63

ring groove

p _LS

Pressure in load signal line

p _LS38

Pressure in the line section 38

p _LS48

Pressure in the line section 48

p _p

Delivery pressure of the variable displacement pump 3

p _T

Pressure in the return line 11

Δp _LS

Pressure difference between delivery pressure and load pressure

Claims (13)

Hydraulic control system for a working hydraulics of a land or building usable vehicle to which vehicle in its rear and / or front area a hydraulic actuating and / or drive system having attachments are coupled, wherein a hydraulic system (25) of the respective attachment by means of a hydraulic coupling system (24) with a hydraulic circuit (1) of the working hydraulics is connectable and both within the hydraulic circuit (1) and within the hydraulic system (25) hydraulic consumers (6, 7, 31, 32) each control devices (8, 9, 29, 30 ) are assigned functionally, wherein in the hydraulic circuit (1) a variable displacement pump (3) is provided whose delivery volume in dependence on a load pressure (p _LS ) of the hydraulic consumers (6 and 7) of the hydraulic circuit (1) and of the attached implement associated hydraulic system ( 25) is controllable, wherein in the context of the regulation of the variable displacement pump (3) at least one hydraulic load signal line ( 17) is provided, which is connected to the control devices (8, 9, 29, 30), and wherein between a first line section (38) of the load signal line (17) with the within the hydraulic circuit (1) arranged control devices (8 and 9), and a second line section (48) of the load signal line (17) connected to the control devices (29 and 30) of the hydraulic system (25), a control valve (37) is arranged, one of the control devices ( 29 and 30) of the hydraulic system (25) generated load pressure _signal (p _LS48 ) _amplified by means of an increase in pressure from a pressure line (10), characterized in that the control valve (37) comprises a load signal amplifying valve unit (39) which serves as a directional control valve (41) is formed, said port connections for which the pressure line (10), the first conduit section (38) and a return line (11) and on the one hand on the load pressure (p _LS38) of the first line section (38) controlled is, and that the control valve (37) has a front side via a biasing spring (47) on a valve spool (45) of the directional control valve (41) engaging biasing stage (40) which _acts on a load pressure (p _LS48 ) of the second line section (48) on the other hand controls the load signal amplification valve unit (39). Control valve (37) for a working hydraulic system designed as a closed-center system of a farm or construction-economical work machine which has a load pressure signal (p _LS ) generated by one or more control devices (8, 9, 29, 30) in a load signal line (17). amplified by an increase in pressure from a pressure line (10), characterized in that the control valve (37) includes a load signal amplifying valve unit (39) as a directional control valve (41) is formed, said port connections for the discharge line (10), for a to an adjusting device of a variable displacement pump (3) leading first line section (38) of the load signal line (17) and a return line (11) and on the one hand on the load pressure (p _LS38 ) of the first line section (38) is controlled, and that the control valve ( 37) has a front side via a biasing spring (47) on a valve spool (45) of the directional control valve (41) engaging biasing stage (40), the mi t is applied to a load pressure (p _LS48 ) of the second line section (48) of the load signal line (17) and controls the load signal amplification valve unit (39) on the other hand. A hydraulic control system or regulating valve according to one of the claims 1 or 2, characterized in that the valve slide (45) front side facing away from of the biasing stage (40) is acted upon by the load pressure (p _LS38) of the first line section (38). Hydraulic control system or control valve according to one of the claims 1 or 2, characterized in that the valve slide (45) has a hydraulic actuation parallel to the pretensioning stage (40) over the load pressure (p _LS48 ) of the second line section (48). Hydraulic control system or control valve according to one of the claims 1 or 2, characterized in that the biasing stage (40) has a longitudinally displaceable control sleeve (53) which is acted upon at a first end face with the load pressure (p _LS48 ) of the second line section (48) and is supported via the biasing spring (47) at a front end of the valve spool (45) of the load signal amplifying unit (39). Hydraulic control system or control valve according to one of the claims 1 or 2, characterized in that the valve slide (45) at its from the biasing stage (40) facing away from the second end side parallel to the load pressure (p _LS38 ) of the first line section (38) via a compression spring (46 ) is acted upon. Hydraulic control system or control valve according to one of the claims 1 or 2, characterized in that a with the load pressure (p _LS48 ) of the second line section (48) acted upon piston (57) acts on the valve spool (45). A hydraulic control system or regulating valve according to claim 7, characterized in that facing by a second valve spool (45) face of the piston (57) a push rod (58) extends from said biasing spring (47) is surrounded. Hydraulic control system or control valve according to one of the claims 1 or 2, characterized in that the load signal amplification valve unit (39) has a 3/2-way valve (41). Hydraulic control system or control valve according to claim 9, characterized in that the 3/2-way valve (41) in a first position at low load pressure (p _LS48 ) of the second line section (48) shuts off the useful connection of the pressure line (10) and the first line section (38) connects to the return line (11) and that the 3/2-way valve (41) in a second position after an increase of the load pressure (p _LS48 ) in the second line section (48) the pressure line (10) with the first line section ( 38) to increase its load pressure (p _LS38) connects. Hydraulic control system or control valve according to claims 5 and 7, characterized in that the biasing spring (47) with its ends on first and second spring plates (55 and 56) is arranged, wherein the first spring plate (55) together with the control sleeve (53) slidably disposed, wherein the second spring plate (56) engages the end face on the valve slide (45) and is supported radially on the inside of the push rod (58) and radially on the outside of the biasing spring (47) and wherein the second spring plate (56), facing away from the push rod (58) engages the valve spool (45). Hydraulic control system or control valve according to one of the claims 1 or 2, characterized in that the pressure increase in the first line section (38) by an exchange of the biasing spring (47) is adjustable against a biasing spring with a different spring constant. Hydraulic control system or control valve according to one of the claims 1 or 2, characterized in that a housing (49) of the load signal amplifying valve unit (39) and a housing (52) of the biasing stage (40) are bolted together, wherein the receiving bores extend coaxially.

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