DE102005033222B4 - LUDV valve assembly - Google Patents

Abstract

LUDV valve arrangement for controlling a hydraulic consumer (18), with a continuously adjustable directional valve (4), which has at least one pressure connection (P) and one inlet connection (P '), between which a variable inlet metering orifice is arranged, downstream of the An individual pressure compensator (6) is provided, the output connection of which is connected to a flow connection (P '') of a directional part of the directional control valve (4), a consumer connection (B) with the flow connection (P '') and another consumer connection (A) with a return connection (T) and in rapid traverse positions (a) the consumer connection (A) with the flow connection (P '') and the further consumer connection (B) via a pressure medium flow path (78, 76, 80) is also connected to the flow connection (P ''), characterized in that a check valve opening in the direction of the flow connection (P '') opens in the pressure medium flow path (78, 76, 80) (72) is arranged.

Description

The invention relates to a LUDV valve arrangement for controlling a hydraulic consumer according to the preamble of patent claim 1.

LUDV valve arrangements are used, for example, in mobile hydraulics. For example, in wheel loaders, the blade movement is controlled by a differential cylinder, the piston rod is connected via a so-called P-kinematics with the blade to raise or lower this (tilting). The basic principle of such LUDV valve arrangements is for example in the WO 95/32364 A1 or DE 199 04 616 A1 the applicant described.

A LUDV control is a special case of a load-sensing control in which the highest load pressure of the hydraulic consumers is reported to a variable displacement pump and regulated so that in the pump line is applied to the pump pressure by a certain pressure difference .DELTA.p above the load pressure. In a LUDV control arrangement, the pressure medium volume flow is adjusted via adjustable metering orifices, to each of which an individual pressure balance is assigned, via which the pressure drop across the respective metering orifice can be kept constant. In LUDV control, these individual pressure compensators are arranged downstream of the metering orifices and throttle the fluid flow between the metering orifice and the load to such an extent that the pressure after all metering orifices is equal, or preferably slightly above, the highest load pressure. In front of all orifices, the pump pressure is applied in the same way, so that the pressure difference changes in the same way at all metering orifices, if the pump pressure becomes lower in the case of an undersupply. In this case, the pressure medium volume flow distribution between the metering orifices of the driven consumers is maintained (load pressure-independent flow distribution). In the known LUDV valve arrangements, the metering orifice is adjusted by a continuously adjustable directional control valve, via the direction of which the direction of the pressure medium flow from the pump to the consumer and from this to the tank (return) is controlled. Such a directional control valve can be adjusted to set a rapid traverse in working positions in which the two pressure chambers of the consumer, for example, in a differential cylinder bottom-side cylinder space and penetrated by the piston rod annulus are connected to each other and to the pump, so that displaced from the annulus Pressure medium summed to the pressure medium flow rate of the pump and is guided to the bottom-side cylinder chamber, so that the extension movement of the cylinder is faster.

This rapid traverse is not to be confused with a so-called regeneration, in which the floor space is connected to a prestressed tank channel from which via a feed valve pressure medium can flow together with the pumped by the pump pressure fluid to the cylinder chamber. Regeneration and rapid traverse are two completely different operating states, which are not comparable with respect to both the flow guidance and with regard to the required hydraulic components. With regard to a LUDV control with regeneration, reference is made to the data sheet RD 64,284 published by the Applicant.

The above-described rapid traverse circuit is used, for example, to up-load a wheel loader by lowering the blade in rapid traverse. In the rapid traverse position of the proportionally adjustable directional control valve, the same, comparatively high pressure arises in both pressure chambers of the differential cylinder. When jacked wheel loader, it may happen that, for example, the pressure in the annulus decreases due to leakage, so that correspondingly, the pressure in the bottom cylinder space is reduced, since the decrease in pressure in the annulus in the floor space no longer so high pressure is required to jack the wheel loader to keep. If, for example, the pressure in the annular space reaches tank pressure, then it is still sufficient to maintain a comparatively low pressure in the bottom-side cylinder space in order to keep the wheel loader jacked up. If the wheel loader is to be jacked up later, the pressure in the cylinder chamber must be increased again to the high initial value because of the rapid traverse gear. In the case in which the pump does not start up fast enough and provides a sufficient pressure medium volume flow, the wheel loader can sag because in the rapid traverse circuit pressure medium flows from the cylinder space into the annular space. By such a rapid sagging of the wheel loader this can be damaged on the one hand, on the other hand, there is a considerable risk of injury to the operator.

In contrast, the invention has for its object to provide a LUDV valve assembly, in which an unintentional movement of a hydraulic consumer in a rapid traverse position of the valve assembly can be prevented.

This object is achieved by a LUDV valve arrangement having the features of patent claim 1.

According to the invention the LUDV valve assembly is designed with a continuously adjustable directional control valve, via which a metering orifice and a directional part are formed. Downstream of the metering orifice an individual pressure compensator is provided, via which the pressure medium volume flow via the metering orifice is kept constant independent of the load. The pressure medium flows from an output of the individual pressure compensator to a flow connection of the directional control valve and from there via the controlled metering orifice to the consumer connection via the pressure medium to the consumer. According to the invention, this flow connection is connected via a pressure medium flow path to the other consumer connection, via which the pressure medium flows from the consumer. In this pressure fluid flow path, a check valve is arranged, which shuts off the pressure medium flow path when the pressure at that consumer port, via which the pressure fluid flows to the consumer, is greater than the pressure at the other consumer port through which the pressure fluid flows from the consumer. D. h., The rapid traverse position is only effective when the pressure at this load port is greater than or approximately equal to that at the located in the pressure medium flow consumer port. As soon as the pressure at this consumer connection is greater (jacking up the wheel loader), this pressure medium flow path is shut off and accordingly prevents undesired backflow of pressure medium. In the specific case, this means that a flow of pressure medium from the piston rod-side annular space to the bottom-side cylinder chamber is only permitted as long as the pressure in the latter is less than or approximately equal to the pressure on the piston rod side.

In a particularly preferred embodiment, the pressure fluid flow path is at least partially formed by a parallel to the valve bore of the directional control valve channel, which is connected on the one hand with the consumer port located in the return and on the other hand with the flow connection.

The channel guide for the directional control valve is particularly simple if the consumer connection located in the pressure medium feed (rapid traverse position) is arranged adjacent to the aforementioned flow control chamber. In this solution, it is preferred if, adjacent to a consumer control room connected to the other consumer connection, a further flow control space is formed which is connected via a flow channel to the first-mentioned flow control space. In this flow channel then opens the output of the individual pressure compensator.

With such a construction, the direct connection between the consumer port located in the return passage (in rapid traverse position) to the further flow control space is closed via a control edge of a valve slide of the continuously variable directional control valve. This control edge is preferably formed on a piston collar.

In a particularly simple embodiment, the rapid transit passage enabling passage opens in a valve housing end face, from which the check valve is inserted.

The consumer is preferably a differential cylinder whose annular space is connected to the consumer connection located in the return passage in the rapid return position and whose bottom-side cylinder space is connected to the other consumer connection.

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

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

1 a circuit diagram of an inventive LUDV valve assembly and

2 a switching symbol of a directional control valve of the LUDV valve assembly 1 ,

In the 1 illustrated LUDV valve assembly 1 is in a valve disc 2 integrated built in a disk design mobile control block over which the hydraulic loaders of a wheel loader can be controlled. The LUDV valve arrangement 1 consists essentially of a continuously adjustable directional control valve 4 , via which a speed and a directional part is formed. As will be explained later, the speed part is formed by an inlet orifice plate, which is an individual pressure balance 6 is downstream. A valve spool 8th of the directional valve 4 is biased by a centering spring assembly in a basic position (the figure does not show this basic position), the springs in the side of the valve disc 2 flanged pre-control housing 10 . 12 are included. The spring chambers of the directional control valve are either via control terminals (a, b (see 2 )), (hydraulic control) or internally pressurized by integrated pressure reducing valves or switching valves (electro-hydraulic control) with a control pressure, wherein the size of this control pressure in the spring chamber, the stroke of the valve spool 8th certainly. Two consumer ports A, B of the LUDV valve assembly are via consumer lines 14 . 16 with a differential cylinder 18 connected, the consumer line 14 to a bottom-side cylinder chamber 20 and the consumer leadership 16 to a piston rod side annulus 22 connected. About the differential cylinder 18 becomes one on a boom 24 via a P-kinematics 30 hinged shovel 26 raised or lowered (tilting), with a piston rod 28 of the differential cylinder 18 at the P-kinematics 30 attacks.

The valve spool 8th of the directional valve 4 is in one the valve disc 2 in transverse direction (view after 1 ) passing valve bore 32 slidably guided by the two pilot control housing 10 . 12 is completed on the front side. The valve bore 32 is extended in the radial direction to several control rooms, wherein in the illustration from left to right a tank control room 34 , a consumer control room assigned to the consumer connection B. 36 , a first flow control room 38 , a pump room connected to a pump or pressure port P. 40 , an inlet control room 42 , a second flow control room 44 , a consumer control room assigned to the working connection A. 46 and another tank control room 48 are formed. The valve spool 8th has several cam grooves through which a piston collar 50 with comparatively large axial length, two control frets 52 . 54 , an intermediate measuring diaphragm collar 56 and another piston collar 58 are formed. The measuring diaphragm collar 56 has two control edges with fine control notches 60 . 62 , depending on the axial displacement of the valve spool 8th an inlet measuring aperture is adjustable. At the other piston collar 58 are also formed two control edges, wherein a consumer control edge 64 the connection between the second flow control room 44 and the consumer control room 46 on or zuusteuert and a tank control edge 66 the connection between the tank control room 48 and the consumer control room 46 certainly. The long piston collar 50 has a consumer tax edge 68 about which the connection between the flow control room 38 and the consumer control room 36 is opened or closed. The two flow control rooms 38 . 44 are via an arcuate flow channel 70 connected to each other, in which an output port of the individual pressure compensator 6 opens. Their input connection is with the inlet control room 42 connected.

At the in 1 illustrated embodiment extends between the consumer control room 36 and the flow control room 44 a pressure medium flow path into which a check valve 72 is used. Its valve cone is via a spring, not shown, against a valve seat 74 biased by a shoulder of a parallel to the valve bore 34 extending channel section 76 is formed of said pressure medium flow path. The channel section 76 flows into the in the 1 right end face of the valve disc 2 , where in the mouth area a screw plug 78 is inserted at the non-return valve 72 is supported. Of course, the housing of the check valve 72 also for the axial shut-off of the channel section 76 be used. The left end of the channel section 76 (View after 1 ) flows through a connection channel 78 in the consumer control room 36 , the area between the valve seat 74 and the frontal mouth of the channel section 76 is via another connection channel 80 with the second flow control room 44 connected.

In the 1 shown LUDV valve assembly can be provided with further valve devices depending on the application, wherein in the section according to 1 a pressure / feed valve 82 To protect against overload and cavities visible. You can also see a float valve 84 , via which a floating position is adjustable. If necessary, the LUDV control arrangement can also be provided with valve means for facilitating regeneration and / or leak-free shut-off (pilot-operated check valves, load-holding valves). Such additional valve devices are known from the prior art, for example, the data sheet mentioned above, so that further explanations are unnecessary.

2 shows a switching symbol of the directional control valve 4 out 1 , Accordingly, the directional control valve 4 designed as a so-called 3-position valve, wherein in the spring-biased home position a pump port P, the two consumer ports A, B, two other pressure ports P 'and P''and two tank or return ports T and T _{1 are} shut off. The pump connection P is in the concrete solution according to 1 with the pump room 40 (Reference numeral in 2 in parenthesis), the two working ports A, B with the associated Verbrauchersteuerräumen 36 . 46 , the connection P 'with the inlet control room 42 , the connection P '' with the flow control chambers 38 . 40 , the tank connection T with the tank control room 48 and the further tank connection T ₁ with the tank control room 34 connected. Also indicated are two control connections a, b, via which a control pressure is applied to control surfaces of the directional control valve 4 can be applied to move this into its illustrated working positions (a) and (b).

When a control pressure is applied to the control port b, the valve spool of the directional control valve becomes 4 in the illustration according to 2 shifted to the left, in which case the connection from P to P 'is opened to adjust a pressure medium volume flow. The opening cross section of the metering orifice is shown in the illustration 1 through the control edge 60 certainly. The pressure medium then flows to the individual pressure compensator, which keeps constant the pressure drop across the inlet orifice in its control position and controls a pressure at the outlet of the metering orifice, which preferably corresponds approximately to the highest load pressure of all consumers of the wheel loader.

The pressure medium then flows from the outlet of the individual pressure compensator via the connection P '' to the consumer connection B and from there to the differential cylinder 18 , so that pressure medium into the annulus 22 to be led. That from the cylinder room 20 displaced pressure medium flows back via the consumer port A and the tank port T to the tank. The second tank connection T ₁ can be connected to the same tank. In principle, however, it is also possible to bias the pressure at this connection via a preload valve, so that this increased tank pressure then, for example during regeneration (see introductory statements) on the rod side of the differential cylinder 18 is applied. This additional tank connection T ₁ is always shut off in the illustrated embodiment.

To set a rapid traverse the directional control valve 4 moved to one of its positions shown by (a), whereby the valve spool 8th (please refer 1 ) is shifted from its spring-biased home position to the right. over the control edge 62 of the measuring diaphragm collar 56 then the metering orifice is opened, so that pressure medium from the pump room 40 via the controlled metering orifice in the inlet control room 42 flows. The pressure medium then flows through the adjusting in their control position individual pressure compensator 6 in the arcuate flow channel 40 that's about the consumer tax rate 68 is shut off to the consumer connection B. about the consumer tax edge 64 is the connection from the second flow control room 44 to the consumer control room 46 controlled, so that the pressure medium through the consumer port A and the consumer line 14 in the bottom-side cylinder chamber 20 flows. The check valve 72 is initially still in its locked position. By getting in the annulus 22 according to the pressurization in the cylinder chamber 20 building pressure is the check valve 72 brought into its open position, so that the pressure medium from the annulus 22 on the consumer line 16 , the consumer control room 36 , the connecting channel 78 , the canal section 76 , the other connecting channel 80 and the second flow control room 44 to the consumer control room 46 and thus can flow to the consumer port A. The one from the annulus 22 displaced pressure medium volume flow is thus summed to the pumped by the pump pressure medium flow, so that the differential cylinder 18 extends at a comparatively high speed and the bucket is moved down to the ground (tilt).

Now, for example, the shovel 26 loaded or blocked with a comparatively large load, the pressure in the cylinder chamber increases 20 opposite the pressure in the annulus 22 on, leaving the check valve 72 is brought into its blocking position, so that the pressure medium connection from the annulus 22 to the cylinder room 20 is interrupted and thus an outflow of pressure medium from the cylinder chamber 20 to the annulus 22 is prevented. The check valve 72 opens only when the pressure required to lift the load pressure chamber in the cylinder chamber 20 has built up.

As already mentioned above, the valve spool locks 8th the direct connection between the consumer control room 36 and the flow channel 70 when adjusting the rapid traverse, so that the summation only via the check valve 72 can be done.

Disclosed is a LUDV valve arrangement, in which a directional control valve forms an inlet orifice plate, which is followed by an individual pressure balance. About the LUDV valve assembly, a hydraulic consumer is controlled, which is connected to two consumer terminals of the control arrangement. To set a rapid traverse two pressure chambers of the consumer can be connected to each other and to a pressure medium source. In order to prevent the consumer from sagging, this connection of the two consumer connections takes place via a pressure medium flow path in which a check valve is arranged. Only the connection to one of the consumer connections is opened via the directional valve itself, the connection of the other consumer connection with the pressure medium source and / or the first-mentioned consumer connection is possible only at rapid speed via the pressure medium flow path and the open check valve.

LIST OF REFERENCE NUMBERS

1

LUDV valve assembly

2

valve disc

4

continuously adjustable directional valve

6

Individual pressure compensator

8th

valve slide

10

pilot housing

12

pilot housing

14

consumer line

16

consumer line

18

differential cylinder

20

cylinder space

22

annulus

24

boom

26

shovel

28

piston rod

30

P-kinematics

32

valve bore

34

Tank control room

36

Consumer control room

38

first flow control room

40

pump room

42

Inlet control room

44

second flow control room

46

Consumer control room

48

Tank control room

50

piston collar

52

control collar

54

control collar

56

Measuring orifice collar

58

further piston collar

60

control edge

62

control edge

64

Consumer control edge

66

Tank control edge

68

Consumer control edge

70

forward channel

72

check valve

74

valve seat

76

channel section

78

connecting channel

80

connecting channel

82

Printing / feed

84

Float valve

Claims (9)

LUDV valve arrangement for controlling a hydraulic consumer ( 18 ), with a continuously adjustable directional control valve ( 4 ), which has at least one pressure port (P) and an inflow port (P '), between which a variable inlet orifice plate is arranged, downstream of which an individual pressure compensator ( 6 ) is provided whose output terminal with a flow connection (P '') of a directional part of the directional control valve ( 4 ), wherein in working positions (b) a consumer connection (B) with the flow connection (P '') and a further consumer connection (A) with a return connection (T) and in rapid traverse positions (a) the consumer connection (A ) with the flow connection (P '') and the further consumer connection (B) via a pressure medium flow path ( 78 . 76 . 80 ) is also connected to the flow connection (P ''), characterized in that in the pressure medium flow path (P 78 . 76 . 80 ) a in the direction of the flow port (P '') opening check valve ( 72 ) is arranged. LUDV valve arrangement according to claim 1, wherein the pressure medium flow path in sections as parallel to a valve spool ( 8th ) of the directional valve ( 4 ) receiving valve bore ( 32 ) extending channel section ( 76 ) is formed, on the one hand in a consumer control room connected to the consumer connection (B) ( 36 ) and on the other hand in a flow control room connected to the flow connection (P '') ( 44 ) connected is. LUDV valve arrangement according to claim 2, wherein the flow control room ( 44 ) adjacent to a consumer terminal (A) associated further consumer control room ( 46 ). LUDV valve arrangement according to one of claims 2 or 3, wherein adjacently to a consumer terminal (B) associated with the consumer control room ( 36 ) another flow control room ( 38 ) is formed, which via a flow channel ( 70 ) with the first-mentioned flow control room ( 44 ), wherein in the flow channel ( 70 ) an output connection of the individual pressure balance ( 6 ). LUDV valve arrangement according to claim 4, wherein the connection from the consumer connection (B) to the further flow control room ( 38 ) in rapid traverse over a control edge ( 68 ) a valve spool ( 8th ) of the directional valve ( 4 ) closed is. LUDV valve arrangement according to claim 5, wherein the control edge ( 68 ) on a piston collar ( 50 ) is trained. LUDV valve arrangement according to one of claims 2 to 6, wherein the channel section ( 76 ) opens in a valve housing end, from which the check valve ( 72 ) is used. LUDV valve arrangement according to one of the preceding claims, wherein the consumer a differential cylinder ( 18 ), the piston rod-side annular space ( 22 ) with the consumer connection (B) and its bottom-side cylinder space ( 20 ) is connected to the consumer terminal (A). LUDV valve arrangement according to one of the preceding claims, wherein the pressure port (P) is connected to a variable displacement pump.

Images