EP1629207B1 - Hydraulic control arrangement - Google Patents

Abstract

A hydraulic control arrangement is disclosed for the load pressure independent control of a consumer, comprising a distribution valve forming an inlet metering orifice, a corresponding individual pressure compensator, a stop valve provided for each consumer connection which may be released by means of a pilot valve and an anti-cavitation valve by means of which pressure medium can be drawn from a reservoir to avoid cavitation. According to the invention, the distribution valve and the stop valves are arranged along two parallel axes, while the axes of the two pilot valves are arranged perpendicularly to these two axes. The anti-cavitation valves in turn extend perpendicularly to the axes of the distribution valves, the stop valves and the anti-cavitation valves.

Description

The invention relates to a hydraulic control arrangement for load pressure-independent control of a consumer according to the preamble of patent claim 1.

The basic structure of such a control arrangement is known, for example, from WO 95/32364 A1. In this LUDV system, each consumer is assigned an adjustable metering orifice with a downstream pressure compensator, the latter keeping the pressure drop across the metering orifice constant so that the quantity of fluid flowing to the corresponding hydraulic consumer depends solely on the opening cross section of the metering orifice and not on the load pressure of the consumer or on the pump pressure depends. Since a plurality of such valve arrangements are connected in parallel, for example, in the case of mobile implements, it is achieved by the pressure compensators of the system that, in the case in which a hydraulic pump of the system has been adjusted to the maximum stroke volume and the pressure medium flow is insufficient, by the predetermined pressure drop To maintain the metering orifices of each associated with a consumer valve assemblies, the pressure compensators of all actuated hydraulic consumers are adjusted in the closing direction, so that all pressure medium flows are reduced by the same percentage. Because of this load-pressure-independent flow distribution (LUDV), all actuated consumers then move at a speed that is reduced by the same amount. In the known solution, it may happen with prolonged support of a consumer that this drops due to a leakage flow through the directional control valve.

This disadvantage is eliminated in a solution according to the data sheet RD 64 284 / 06.00 (hydraulic valves for mobile applications) by a pilot operated check valve, which is connected in the pressure medium flow path between the directional control valve and a consumer port and ensures its leak oil-free barrier. In this known solution, a pressure / suction valve is further provided over which the consumer is protected from overload and cavitation phenomena in the case of a shortage of the associated load port with pressure medium.

In the solution known from FR 2,756,349, each consumer port is associated with an aspirating valve which is perpendicular to the plane of a valve disc receiving the valve assembly. However, this known solution lacks a check valve for leak-free shut-off of the consumer.

In contrast, the invention has for its object to provide a hydraulic control arrangement in which all components required for the control of the consumer in a compact manner in a valve housing section, preferably a valve disc are summarized.

This object is achieved by a hydraulic control arrangement with the features of claim 1.

According to the invention, the control arrangement is preferably integrated in a valve disc, wherein a directional control valve forming a LUDV orifice plate and two shut-off valves each associated with a consumer port are located in the valve disc plane and two pilot valves respectively assigned to the two shut-off valves are installed in such a way are that their axes are oriented perpendicular to the two axes of the directional control valve and the check valves. The pressure / suction valve associated with a consumer connection is arranged perpendicular to the axes of the above-described valve elements, ie perpendicular to the plane of the pane. A special feature of the invention further consists in that the pilot valves arranged perpendicularly to the axis of the directional control valve are actuated mechanically via a ram which can be displaced axially by a valve spool of the directional control valve in order to unlock the check valves and to allow a pressure medium discharge from the consumer.

The solution according to the invention is characterized by a special compactness, wherein all essential, required in a LUDV system components are taken up with minimal space.

Solutions in which an actuation of the pilot valve takes place mechanically via the valve slide of the directional control valve are known, for example, from DE 196 27 306 A1 or US Pat. No. 3,595,271 or US Pat. No. 3,125,120. However, these documents contain no reference to the inventive compact design of a valve disc for a LUDV system.

In a preferred embodiment of the invention, the directional control valve, the check valves and the pilot valves are arranged parallel to the disc plane (Figure 1) and the Nachsaugventil perpendicular to the disc plane, so that the valve disc can be made with minimal effort due to the simple channel guide.

In this variant, it is preferred if the axis of the measuring diaphragm of the directional valve downstream LUDV pressure compensator extends in the disc plane.

In a particularly compact embodiment, the axis of the individual pressure compensator is arranged centrally between the axes of the two pilot valves, so that the valve disc has a nearly axisymmetric structure.

In this variant, it is preferred that the axis of the two Nachsaugventile is arranged in the region which is encompassed by the axis of the two check valves, the two axes of the pilot valves and the axis of the directional control valve.

For actuating the pilot valve, the valve slide of the directional control valve has an actuation section, via which a plunger guided perpendicular to the directional control valve axis can be axially displaced to open the pilot valve. In a preferred embodiment of the invention, this plunger is guided in a portion of the valve disc or the valve housing.

In a particularly compact embodiment, the axis of the pilot valve crosses the axis of the respective associated check valve.

The installation of the Nachsaugventile is particularly simple when lying in the region of these Nachsaugventile to the load ports leading working channels in a plane which are arranged offset to a tank channel containing a plane of the valve disc.

Other advantageous developments of the invention are the subject of further subclaims.

• Figur 1 eine schematische Schnittdarstellung einer Ventilscheibe mit der erfindungsgemäßen Steueranordnung;
• Figur 2 eine Detaildarstellung eines Wegeventils der Ventilscheibe aus Figur 1;
• Figur 3 eine Detaildarstellung eines Sperrventils, eines Pilotventils und einer Druckwaage des Wegeventils aus Figur 1 und
• Figur 4 eine geschnittene Seitenansicht der Ventilscheibe aus Figur 1 mit einem Druck-/Nachsaugventil.

In the following a preferred embodiment of the invention will be explained in more detail with reference to schematic drawings. Show it:

• Figure 1 is a schematic sectional view of a valve disc with the control arrangement according to the invention;
• Figure 2 is a detail view of a directional valve of the valve disc of Figure 1;
• FIG. 3 shows a detail of a shut-off valve, a pilot valve and a pressure compensator of the directional control valve from FIGS. 1 and
• Figure 4 is a sectional side view of the valve disc of Figure 1 with a pressure / Nachsaugventil.

Figure 1 shows a section through a valve disc 1 of a control block of a mobile implement, such as a shovel, wherein the valve elements for each function (eg traction drive, lifting / lowering, bucket operate, etc.) are each combined in a valve disc. The valve disc 1 shown in Figure 1 has two consumer ports A, B and a pressure port P (not shown), a tank port T (not shown) and a plurality of control terminals (including an LS port). In the valve disc 1 is a continuously adjustable directional control valve 2 with a valve slide 4, which is guided axially displaceably in a valve disc 1 in the transverse direction passing through axial bore 6. As will be explained in more detail below, the valve slide 4 forms together with the axial bore 6 a speed part, also called orifice 8 and two directional parts 10, 12, via which the direction of the pressure fluid flow from and to the load ports A, B is determined.

Downstream of the metering orifice, an individual pressure compensator 14 (LUDV pressure compensator) is provided which is acted upon in the opening direction by the pressure downstream of the metering orifice 8 and in the closing direction by the force of a control spring (not shown) and the highest load pressure of the consumers. This load pressure is tapped via a load pressure signaling line 16 and reported in the spring chamber of the pressure compensator. Under certain circumstances, the control pen can be dispensed with.

In the valve disc 1 further two each a consumer port A, B associated shut-off valves 18, 20 are arranged, via which the consumer ports A, B are leak-tight lockable. To allow a backflow, each check valve 18, 20 by means of a pilot valve 22, 24 can be unlocked. The axes of these pilot valves 22, 24 extend in the embodiment shown in Figure 1 perpendicular to the axis of the directional control valve 2 and the common axis of the two check valves 18, 20, wherein the axis of the pilot valves 22, 24, the axis of the associated directional control valve 18 and 20 crosses , The actuation of the pilot valves 22, 24 takes place in each case via a plunger 30, 32, which is axially displaceable over the valve spool 4.

Perpendicular to the plane in Figure 1, two pressure / Nachsaugventile 26, 28 are used in the valve disc 1, which open a connection to the tank port T at a predetermined pressure at the consumer port A, B and in the case of a pressure medium undersupply, a suction of pressure medium allow the tank. According to Figure 1, the two axes of the pressure / Nachsaugventile 26, 28 are within that range, by the common axis of the two check valves 18, 20, the axis of the directional control valve second as well as the two axes of the pilot valves 22, 24 is clamped.

Both the individual pressure compensator 14 and the check valves 18, 20, the pilot valves 22, 24 and the pressure / Nachsaugventile 26, 28 are inserted into valve holes of the valve disc 1, which from the outside, i. are drilled from the end faces (pressure compensator, pilot valves, check valves) or from the large area of the valve disc 1 forth (pressure / Nachsaugventile) and are shut off after insertion of the respective valve body by screw plugs or the like.

Further details of the valve arrangement will be explained below with reference to the detailed representations.

FIG. 2 shows the directional control valve 2 of the valve disk 1.

The valve slide 4 has a multiplicity of annular grooves, by means of which it is subdivided into a central measuring diaphragm collar 34, two control collars 36, 38 arranged on both sides thereof, and two tank collars 40, 42 arranged laterally therefrom. The two end portions 44, 46 protrude from the valve disc 1. In this area, flanges are flanged to the valve disc, record the centering springs for the valve spool 4 or control elements.

The annular end faces of the two tank collars 40, 42 lying on the outside in FIG. 2 are each designed as inclined control surfaces 50, 52, against which the plunger 30 and 32 are not biased in the center position of the control slide. The other two annular end faces of the tank collar 40, 42 are provided with control notches 54, 56. Similarly, 34 fine control notches 58, 60 open in the annular surfaces of the central Meßblendenbundes.

The pressure port P, not shown, opens into a pressure chamber 62, which is formed by an annular groove of the axial bore 6. In addition to this pressure chamber 62, the axial bore is still extended to a connecting space 64, two annular spaces 66, 68, two drainage spaces 70, 72 and two outer tank spaces 74, 76. Between the above-described spaces each remain webs, which cooperate with the control edges of the valve spool 4.

According to FIG. 1 and FIG. 2, the connecting space 64 opens into a pressure compensator channel 78, which leads to the inlet of the individual pressure compensator 14. The output of the individual pressure compensator is connected via two channels 80, 82 to the annular spaces 66, 68. The two drainage spaces 70, 72 each open into a consumer channel 84, 86 which extends to the entrance of the check valves 18 and 20, respectively.

In each of the two tank chambers 74, 76 opens a tank channel 88, 90 (see FIG. 1), which leads to the respective associated pressure / suction valve 26, 28.

FIG. 3 shows that part of the valve disk 1 in which the check valve 20 and the pilot valve 24 as well as a part of the individual pressure compensator 14 are accommodated. The check valve 20 has a designed as a hollow piston locking piston 96 which is guided axially displaceably in a check valve bore 94. This is shut off with a screw plug 98, on which a spring 100 is supported, via which the locking piston 96 is biased against a valve seat 102. The locking piston 96 is designed with a seat difference. In the blocking position shown, the connection between the consumer channel 86 and connected to the consumer port B working channel 104 is closed. This working channel 104 extends from the consumer port B to the pressure / Nachsaugventil 28th

In the jacket of the locking piston 96, a nozzle 106 is provided, via which a spring 100 receiving spring chamber 108 is connected to the working channel 104. This spring chamber 108 can be relieved via the pilot valve 24 to the tank T out. The pilot valve has a seat bushing 110 inserted into a bore 112. In the valve sleeve 110, a pilot seat 114 is formed, against which a valve body 116 is biased by means of a pilot spring 118. This is supported on a locking ring 120 inserted into the socket 110. As can be seen in particular from FIG. 3, the bore 112 intersects the check valve bore 64, the valve bush 110 with the valve body 116 and the pilot control spring 118 being inserted into a region of the bore 112 which is disposed beyond the check valve bore 94 in the representation according to FIG. The mouth region of the bore 112 remote from the valve sleeve 110 is shut off by a closure screw 112. The axis of the bore 112 extends coaxially to the axis of the plunger 82, which is guided in a guide projection 124 of the valve disc 1. The bore 112 opens into the tank space 76, so that the end portion of the plunger 32 located at the top in FIG. 3 can dip into the opening encompassed by the pilot seat 114 and can be brought into contact with the valve body 116.

The pressure compensator piston 126 is biased by an axial projection 128 against a wall of the pressure compensator channel 78 and has on the adjacent annular end face control notches 130, which form a control edge over which the connection between the pressure compensator channel 78 and the channels 80, 82 aufsteuerbar.

The pressure relief valve is a unit. The compression spring presses on seat element 138 and disc 142, which is positively connected to 144 and 146.

The elements 144 and 146 are a part. The tapered end of 146 is pulled by the compression spring to the internal seat 138. The cone spring 200 pushes the assembled unit 138 into a seat in the housing.

FIG. 4 shows a sectional side view in the region of the pressure / after-suction valve 26. The consumer connection A opens into a working channel 132. This (corresponding to the working channel 104 of the working connection B) leads to a radial connection of the pressure / suction valve 18. This is in a Used Nachsaugbohrung 134 through which the working channel 132 is connected to the tank channel 88. Through the Nachsaugbohrung 134 a Nachsaugventilsitz 136 is formed, against which a Nachsaugkegel 138 is biased by a compression spring 140. This is supported on a spring plate 142, which in turn is fastened to a piston rod 144 of a guided in the Nachsaugkegel 138 pressure limiting piston 146. The piston rod 144 with the spring plate 142 is supported on a support screw 148, which is screwed from a large area of the valve disc 1 forth in the Nachsaugbohrung 134. In the Nachsaugkegel 138 a seat for the pressure limiting piston 146 is provided, against which it is biased by the force of the compression spring 140. The pressure in the spring chamber of the pressure / Nachsaugventils 26 is reported via pressure holes 150 of the Nachsaugkegels 138 to the seat for the pressure limiting piston 146. When a predetermined maximum pressure in the working channel 132 is exceeded, the pressure limiting piston 146 lifts against the force of the compression spring 140 and against the pressure acting on the pressure limiting piston 146 pressure in the tank channel 88 to the left (Figure 4) Seat off so that pressure fluid from the working channel 132 can flow into the tank channel 88 - the pressure in the working channel 132 is limited to the maximum value. In the event of an undersupply, a higher pressure arises in the tank channel 88 than in the working channel 132 so that the re-absorption cone 138 can lift off its suction valve seat 136 against the force of the compression spring so that pressure medium can flow from the tank into the working channel 132, ensuring a sufficient supply of pressure medium is and cavitation can not occur.

The structure according to the invention with a symmetrical in the representation of Figure 1 construction with respect to the axis of the individual pressure compensator 14 and with the intersecting axes of the check valve 18, 20 and the associated pilot valve 22, 24 and arranged perpendicular thereto pressure / Nachsaugventilen 26, 28 allows to combine all the hydraulic components required for LUDV control and leak-free support of a consumer in a minimum space.

For a better understanding of the invention, the function of the control arrangement 1 according to the invention is briefly explained below. It is assumed that the valve spool 4 of the directional control valve 2 is moved to the right in the illustration according to FIG. 1 in order to return pressure medium via the consumer connection A to the consumer and from this via the consumer connection B to the tank T. Due to the axial displacement of the valve spool 4 to the right, a metering orifice cross-section is opened via the control notches 58 of the metering orifice collar 34, so that pressure medium can flow from the pressure chamber 62 into the pressure compensator channel 78. The pressure compensator is brought into an open position with sufficient pump pressure by the effective pressure in the opening direction, so that the pressure medium via the channel 80 and the annular space 66 in the open Outflow space 70 can flow. With sufficient pressure in the consumer channel 84 of the locking piston 96 of the check valve 18 is lifted against the force of the spring 100 of its valve seat 102, so that the pressure medium to the consumer A is promoted , The load pressure building up at the consumer is reported via the LS channel 16 into the spring chamber of the individual pressure compensator 14. This adjusts to a control position in which the pressure drop across the inlet orifice is kept constant.

At the same time by the axial displacement of the valve spool 4 to the right of the plunger 32 via the control surface 52 in the axial direction upward (view of Figure 1) moved so that the valve body 116 is lifted from its pilot seat 114 and corresponding to the spring chamber 108 of the check valve to the tank space 76th is relieved. The pressure at the working port B is then sufficient to lift the locking piston 96 against the force of the spring 100 from its valve seat 102, so that the pressure fluid from the working port B via the consumer channel 86 and controlled by the tank collar 42 with the control notches 56 flow cross-section into the tank space 76 and from there to the tank can flow out.

In the case in which a pulling load occurs (for example, when dumping or lowering a load), it may happen that not enough pressure medium is supplied to the working port A, so that the pressure at this port drops below the pressure in the drain. In other words, the inlet pressure drops below the tank pressure, so that the pressure / Nachsaugventil opened in the manner described above and pressure medium from the tank channel 88 can flow into the working channel 132.

Disclosed is a hydraulic control arrangement for load pressure-independent control of a consumer, with a Zulaufmessblende forming a directional control valve, an associated individual pressure compensator, each one the consumer connections associated shut-off valve, which is unlocked by a pilot valve and a Nachsaugventil, via which to avoid cavitation pressure medium from a tank is nachsaugbar. According to the invention, the directional control valve and the check valves are arranged along two parallel axes, while the axes of the two pilot valves are arranged perpendicular to these two axes. The suction valves are again perpendicular to the axes of the directional control valves, the check valves and the Nachsaugventile.

LIST OF REFERENCE NUMBERS

1

valve disc

2

way valve

4

valve slide

6

axial bore

8th

metering orifice

10

direction part

12

direction part

14

Individual pressure compensator

16

LS-channel

18

check valve

20

check valve

22

pilot valve

24

pilot valve

26

Pressure / anti-cavitation valve

28

Pressure / anti-cavitation valve

30

tappet

32

tappet

34

Measuring orifice collar

36

control collar

38

control collar

40

tank Bund

42

tank Bund

44

end

46

end

50

control surface

52

control surface

54

control notch

56

control notch

58

Fine control notch

60

Fine control notch

62

pressure chamber

64

communication space

66

annulus

68

annulus

70

drain space

72

drain space

74

tankage

76

tankage

78

Pressure balance channel

80

channel

82

channel

84

consumer channel

86

consumer channel

88

tank channel

90

tank channel

94

Check valve bore

96

blocking piston

98

Screw

100

feather

102

valve seat

104

working channel

106

jet

108

spring chamber

110

valve sleeve

112

drilling

114

pilot seat

116

valve body

118

pilot spring

120

circlip

122

Screw

124

guide projection

126

Pressure regulator piston

128

axial projection

130

control notches

132

working channel

134

Nachsaugbohrung

136

Nachsaugventilsitz

138

Nachsaugkegel

140

compression spring

142

spring plate

144

piston rod

146

Pressure limiting piston

148

support screw

150

pressure bores

Claims (10)

1. A hydraulic control arrangement for the load pressure independent control of a consumer, comprising a housing portion, preferably a valve disk (1) in which a continuously variable distribution valve (2) controlling the pressure medium flow to the consumer is accommodated, to which distribution valve an individual pressure compensator (14) is allocated, and comprising at least one stop valve (18, 20) which is arranged in the pressure medium flow path between the distribution valve (2) and the consumer and can be released to permit a pressure medium flow from the corresponding consumer connection, and comprising an anti-cavitation valve (26, 28) via which pressure medium can be sucked from the reservoir in the case of a lacking supply of the consumer, characterized in that the stop valve (18, 20) is controlled by a pilot valve (22, 24) the axis of which extends perpendicularly to the axis of the distribution valve (2) and of the stop valve (18, 20) arranged axially parallel thereto, wherein the pilot valve (22, 24) can be controlled to be opened mechanically by a slide valve (4) of the distribution valve (2), and that the axis of the pressure-limiting and anti-cavitation valve (26, 28) extends perpendicularly to the axes of the distribution valve (2) and the pilot valve (22, 24).
2. A hydraulic control arrangement according to claim 1, wherein the control arrangement is accommodated in a valve disk (1) and the distribution valve (2), two stop valves (18, 20) and pilot valves (22, 24) are arranged in the disk plane and the pressure-limiting and anti-cavitation valves (26, 28) are arranged perpendicularly to the disk plane.
3. A control arrangement according to claim 1 or 2, wherein the axis of the individual pressure compensator (14) is arranged perpendicularly to the axis of the distribution valve in the disk plane.
4. A control arrangement according to claim 3, wherein the axis of the individual pressure compensator (14) is arranged centrally between the axes of the two pilot valves (22, 24).
5. A control arrangement according to any one of the preceding claims, wherein the axis of the pilot valves (22, 24) intersects the axis of the corresponding stop valve (18, 20) in the area of a spring chamber (108).
6. A control arrangement according to any one of the preceding claims, wherein the axis of the pressure-limiting and anti-cavitation valves (26, 28) is located in the area between a common axis of the stop valves (18, 20) and the axis of the distribution valve (2).
7. A control arrangement according to any one of the preceding claims, wherein the slide valve (4) includes a control surface (50, 52) via which a tappet (32) extending perpendicularly to the axis of the distribution valve is axially movable for opening the pilot valve (22, 24).
8. A control arrangement according to claim 7, wherein the tappet (30, 32) is guided in the valve disk (1).
9. A control arrangement according to any one of claims 2 to 8, wherein each of the stop valve (18, 20) and the pilot valve (22, 24) are accommodated in intersecting bores (94, 112) ending at the side faces of the valve disk (1).
10. A control arrangement according to any one of the preceding claims, wherein at least in the area of the pressure-limiting and anti-cavitation valves (26, 28) working passages (104, 132) leading to the consumer connections (A, B) are located in a plane of the valve disk (1) which is arranged offset with respect to a plane including reservoir passages (88, 90).

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