EP2620657A2 - Valve assembly for a mobile work machine - Google Patents

Abstract

The valve arrangement has a control valve (1), over which a regenerative connection (C2) and another connection (C1) of a load are provided. A regeneration valve is provided with only two switched positions, over which pressurizing agent from the regenerative connection is derivable in a tank (6). The regeneration valve is opened between the connections above a predetermined pressure difference and is closed at the rest of the time. A control slide (14) of the control valve has a common regeneration- and working position (a).

Description

The invention relates to a valve arrangement for a consumer of a mobile machine with a regeneration position according to the preamble of patent claim 1.

In one application example, a differential cylinder of a handle of an excavator is supplied via such a valve arrangement. About a pressurization of a piston bottom side of the differential cylinder in a working position of the valve assembly, a lowering movement of the stem with a blade and thus a grave movement. By means of a reversal position of the valve arrangement, a pressure is applied to an annular surface side of the differential cylinder and thus a lifting of the stem.

When pulling or Vorsteilender load on the stem by the weight of oil is conveyed via a regeneration position of the valve assembly oil from the annular surface side of the differential cylinder directly to the piston surface side, so that the pump has to deliver less oil. The corresponding delivery pressure is generated by the load on the piston. In the working position (digging) with the same direction of movement, the oil is discharged from the ring surface side into the tank.

The pamphlets DE 10 2009 021 831 A1 and JP 2002-061605 A show a valve assembly in which a separate regeneration slide is provided for regeneration. This causes the switching between working and regeneration automatically and depending on the pressure on the piston surface side. The Regerationsschieber adjusted a continuously variable throttle point, so that a soft transition between working and regeneration position is given.

The DE 10 2006 002 920 A1 discloses a valve arrangement in which the working and the regeneration position are separate switching positions of a single spool, which must be actively switched from the outside.

The present invention aims to provide a valve assembly in which the switching between regeneration and working position is automatic and automatic. In this case, vibrations of the regeneration slide, in particular in the working position, should be avoided.

This object is achieved by a valve arrangement for a mobile work machine having the features of patent claim 1.

The valve arrangement according to the invention has a metering or control valve via which a regenerable connection and a further connection of a consumer - e.g. Working cylinder or engine - a mobile machine can be supplied. There is a - preferably separate - regeneration valve with only two switch positions (fully open, fully closed) provided over the pressure medium from the regenerable connection in a tank can be derived. Above a predetermined pressure difference between the terminals, the regeneration valve is open and otherwise closed. A main slide or control slide of the control valve has a common regeneration and working position. The spool thus has no along a displacement path of the spool from the regeneration position spaced working position. In the valve arrangement according to the invention, the switching between regeneration and working position is soft and automatic. In this case, vibrations of the spool are avoided by its common regeneration and working position.

The mobile working machine whose consumer is connected to the valve arrangement according to the invention may be a backhoe loader or a compact excavator or a mini-excavator or a telescopic loader. In these machines, regeneration of the limited energy reserves is particularly advantageous.

Further advantageous embodiments of the invention are described in the dependent claims.

In a particularly preferred embodiment of the valve arrangement according to the invention, the spool in the control valve - preferably hydraulically - continuously adjustable. This allows an operator of the mobile machine steplessly steer the consumer. This results in an area at a displacement of the control slide along its longitudinal axis with a plurality of working positions and thus common regeneration positions.

In a preferred embodiment, the Regerationsventil is a pilot-operated check valve, which is controlled directly with a tapped from the other terminal acting in the opening direction control pressure. This ensures that the check valve remains closed during regeneration operation and that no pressure medium flowing back from the regenerable connection can flow to the tank via the check valve. Thus, the entire pressure medium flowing back from the regenerable connection flows to the control valve for regeneration. As soon as the force pulling on the consumer changes into an opposing force, that is to say a change of direction of the external force takes place at the consumer, the working mode is detected and the check valve opens. Thus, the pressure flowing back from the regenerable port pressure medium via the check valve with minimal resistance to the tank flow.

In a preferred embodiment of the check valve whose closing spring has low spring stiffness, so that virtually no intermediate position can be set.

In a first and second application example, the consumer, which can be supplied by the valve arrangement according to the invention, a differential cylinder.

In this case, according to the first application example - e.g. in a stick cylinder of an excavator - the annulus of the differential cylinder to be connected to the regenerable port.

In this case, it is preferred if the regeneration valve has an opening area and a shooting area, wherein the closing area is smaller than the opening area. Preferably, the ratio closing surface / opening area corresponds approximately to the ratio ring surface / bottom surface of a piston of the differential cylinder.

According to the second application example - e.g. in a boom cylinder of an excavator - the bottom space of the differential cylinder may be connected to the regenerable port.

In this case, it is preferable if the regeneration valve has an opening area and a shooting area, wherein the closing area is greater than the opening area. Preferably, the ratio opening area / closing surface corresponds approximately to the ratio ring surface / bottom surface of a piston of the differential cylinder.

In a third application example, the consumer, which can be supplied by the valve arrangement according to the invention, is a synchronous cylinder.

It is preferred if the regeneration valve has an approximately equal opening area and shooting area.

The opening area and the shooting area may, in all the application examples, be arranged on two different valve bodies (for example closing bodies and opening pistons) of the regeneration valve, which can be brought into contact with one another.

In a particularly preferred development of the valve arrangement according to the invention, a regeneration line is opened in or in the common regeneration and working position (s), in which a non-return valve opening from the regenerable to the further connection is arranged.

In or on the Regerationsleitung can be arranged an adjustable throttle. Preferably, the throttle is adjustable via the displacement path or the position of the spool in the control valve.

Depending on the application example, it is advantageous if the regenerable connection is connected to the tank via the common regeneration and working position (s) of the spool valve via a throttled drain. This Restricted flow is important in a regeneration according to the second application example (eg boom cylinder) to dissipate the excess volume. The throttled sequence can discharge at a regeneration according to the first application example (eg stick cylinder) pressure medium, which should not be regenerated.

In a device-technically simple embodiment of the throttled drain or its throttle is formed on the spool of the control valve.

• Figur 1 das Ausführungsbeispiel der erfindungsgemäßen Ventilanordnung mit einem ersten Anwendungsbeispiel in einer schematischen Darstellung;
• Figur 2 das Regenerationsventil der Ventilanordnung gemäß Figur 1 in einer geschnittenen Darstellung;
• Figur 3 das Steuerventil der Ventilanordnung gemäß Figur 1 in einer geschnittenen Darstellung;
• Figur 4 das Steuerventil gemäß Figur 3 im Regenerationsbetrieb mit dem ersten und mit einem zweiten Anwendungsbeispiel; und
• Figur 5 das Steuerventil gemäß Figur 3 im Arbeitsbetrieb mit dem ersten und dem zweiten Anwendungsbeispiel.

In the following, an embodiment of the invention (with two application examples) will be described in detail with reference to FIGS. Show it:

• FIG. 1 the embodiment of the valve assembly according to the invention with a first application example in a schematic representation;
• FIG. 2 the regeneration valve of the valve assembly according to FIG. 1 in a sectional view;
• FIG. 3 the control valve of the valve assembly according to FIG. 1 in a sectional view;
• FIG. 4 the control valve according to FIG. 3 in the regeneration mode with the first and with a second application example; and
• FIG. 5 the control valve according to FIG. 3 in working mode with the first and the second application example.

FIG. 1 shows the embodiment of the valve assembly according to the invention. This consists essentially of a control valve 1 and designed as a releasable shut-off or check valve 2 regeneration valve. The valve arrangement 1, 2 is connected via a pump connection P to a variable displacement pump 4 and via a tank connection T to a tank 6. The valve assembly 1, 2 serves (according to the in FIG. 1 shown first application example) for supply a differential cylinder 8 and is connected via a regenerable port C2 to an annular space 10 and via a further connection C1 to a bottom space 12 of the differential cylinder 8. The differential cylinder 8 serves (in the in FIG. 1 shown application example) for actuating a (not shown) stem of an excavator. A pressurization of the floor space 12 leads to a lowering of the stem and a (also not shown) blade. This function is used in particular for digging. Pressurization or supply of the annular space 10 leads to a lifting of the stem and the blade. For the corresponding control and metering of a pressure medium flow from the variable displacement pump 4 to the respective port C1 or C2 is the control valve 1, which is designed as a continuously variable 4/3-way valve. In the (in FIG. 1 shown) spring-biased basic position 0 of a spool 14, the terminals A, B are shut off. In a working position a, which is at the same time a regeneration position, the pump port P is connected to the working port B and thus the further port C1 and thus the bottom chamber 12 is acted upon with pressure medium. In a further working position b, the pump port P is connected to the working port A and thus the port C2 and thus the annular space 10 is acted upon by pressure medium.

In the common regeneration and working position a of the spool 14, a pressure medium connection from port A to port B is provided, via which the regeneration takes place. In this pressure medium connection, a check valve 16 opening from the connection A to the connection B and a throttle 18 are provided whose opening cross-section can be adjusted via the position or position of the control slide 14.

The pilot-operated check valve 2 has a valve body 20 and a tank port T, wherein in a normal or working operation of the valve arrangement 1, 2 according to the invention, a connection from port C2 to tank port T is opened, while in regeneration operation, the connection from port C2 to tank port T through the valve body 20 is shut off. For this function, the check valve 2 has a control line 22 which is connected to a working line section 24 connecting the further connection C1 to a connection V1 of the check valve 2.

FIG. 2 shows the structural design of the trained as a releasable check valve 2 regeneration valve of the valve assembly according to FIG. 1 , It has an inlet which is connected to the regenerable connection C2, and a drain or tank connection T. Furthermore, the check valve 2 connects the further connection C1 and the connection V1, between which the working line section 24 is formed. Depending on the setting of the control valve 1 (see FIG. FIG. 1 ) Pressure medium from this to the bottom space 12 of the differential cylinder 8 (see. FIG. 1 ) or the other way around. The check valve 2 has a sleeve 26 which is screwed into a housing 28, and in which the valve body 20 is biased by a closing spring 30 in a closing direction. In the in FIG. 2 illustrated closed position of the valve body 20, a connection from the regenerable port C2 is shut off to the tank port T, so that a regeneration of the pressure medium displaced from the annular space 10 via the main valve 1 is possible. Also in the closing direction of the valve body 20 of prevailing at the regenerable port C2 pressure acts. In the opposite direction in an opening direction of the valve body 20, the prevailing at the other terminal C1 pressure. For this purpose, a control pressure chamber 31 acting in the opening direction is connected via the control line 22 and via the working line section 24 to the further connection C1. The control pressure chamber 31 is delimited by an opening surface 33 of an opening piston 32, which can be brought into contact with the valve body 20 and then acts on the valve body 20 with an opening force as a function of the working pressure at the further connection C1.

• ● ein erster Tankdruckraum 36;
• ● ein mit dem Arbeitsanschluss A verbundener Druckraum 38;
• ● ein erster mit einem Brückenkanal 40 verbundener Brücken-Druckraum 42;
• ● ein mit dem Pumpenanschluss P verbindbarer Zumess-Druckraum 44;
• ● ein mit dem Pumpenanschluss verbundener Pumpen-Druckraum 46;
• ● ein zweiter mit dem Brückenkanal 40 verbundener Brücken-Druckraum 48;
• ● ein mit dem Arbeitsanschluss B verbundener Druckraum 50; und
• ● ein zweiter Tank-Druckraum 52.

FIG. 3 shows the control valve 1 of the valve assembly according to FIG. 1 in a cut view. Its spool 14 is (as in FIG. 1 ) are shown in a central basic position 0, in which the two working ports A, B, the pump port P and the tank port T are shut off. The control valve has (in FIG. 3 from left to right) along a longitudinal axis 34 the following pressure chambers:

• ● a first tank pressure space 36;
• ● a pressure chamber 38 connected to the working connection A;
• ● a first bridge pressure chamber 42 connected to a bridge channel 40;
• ● a metering pressure chamber 44 which can be connected to the pump connection P;
• ● a pump pressure chamber 46 connected to the pump connection;
• ● a second bridge pressure chamber 48 connected to the bridge channel 40;
• ● a pressure chamber 50 connected to the working port B; and
• ● a second tank pressure chamber 52.

The bridge channel 40 connects the metering pressure chamber 44 via a load-holding valve 54 with the two bridge pressure chambers 42, 48. Inside the spool 14, the check valve 16 (see. FIG. 1 ) arranged. This has at least a first radial bore 58 and at least a second radial bore 62. The check valve 16 opens at a flow from the first radial bore 58 to the second radial bore 62, while inversely closes at a predominant pressurization via the second radial bore 62. For this purpose, a valve body or switching piston 60 of the check valve 16 is movably arranged in a longitudinal bore of the spool 14 and by a closing spring 64 in the (in FIG. 3 shown) biased closed position. The switching piston 60 has a radially stepped-back portion whereby an annular space 66 is formed with the longitudinal bore, which is always connected to the first radial bore 58. At the radially recessed portion of the switching piston 60, a sealing portion 68 is further fixed, in the (in FIG. 3 shown) closed position of the switching piston 60, a connection from the second radial bore 62 to the radial bore 58 shuts off. Upon movement of the switching piston 60 with the sealing portion 68 (in FIG. 3 ) to the right against the force of the closing spring 64, the connection from the first radial bore 58 to the second radial bore 62 is opened. The switching piston 60 of the check valve 16 is acted upon via a longitudinal bore 63 and a radial pressure detection bore 65 from the pressure at the working port B. This admission takes place when the pressure detection bore 65 is brought into communication with the pressure chamber 50. This is done by an adjustment of the spool 14 (in FIG. 3 ) to the left in the common regeneration and working position a. In this position a, which in the FIGS. 4 and 5 is shown closes the check valve 16 when the pressures at the working ports A and B are about the same.

The adjustable throttle 18 (see. FIG. 1 ) is formed by the second radial bore 62 and arranged on the first bridge pressure chamber 42 control edge 70.

In order to connect the working port A with the pump port P and the working port B with the tank port T, the spool 14 is in FIG. 3 to the right into working position b (cf. FIG. 1 ) postponed. As a result, a connection is made from the pump port P via the pump pressure chamber 46, via a metering orifice 56b, the metering pressure chamber 44, the load-holding valve 54, a section of the bridge channel 40, the first bridge pressure chamber 42, and the pressure chamber 38 to the working port A.

In the FIG. 1 shown common regeneration and working position a of the control valve 1 is by a shift of its spool 14 (in FIG. 3 to the left).

FIG. 4 shows the control valve 1 of the valve arrangement 1, 2 according to the invention according to FIG. 3 in regeneration mode. This is with the (in FIG. 4 shown) common regeneration and working position a of the spool 14 is reached. These are in FIG. 4 the first application example with the differential cylinder 8 and a second application example with a differential cylinder 108 shown. In the first application example 8 pressure medium for regeneration via the regenerable port C2 to the working port A is displaced from the annulus 10, while in the second application example pressure medium from a bottom space 112 of the differential cylinder 108 via the regenerable port C2 to the working port A is displaced.

In both application examples, the pressure medium flows through the first radial bore 58, in the arranged in the interior of the spool 14 annular space 66. The pressure medium continues to flow through the open check valve 16, via the adjustable throttle 18 and the bridge channel 40 to port B. It can during first application example with the differential cylinder 8 the entire displaced from its annulus 4 pressure medium can be regenerated. In contrast, in the second application example with the differential cylinder 108, not the entire pressure medium of the bottom space 112 can be regenerated, since the annular space 110 can not absorb the corresponding quantity of pressure medium. Therefore, a throttled drain ST to the tank T is provided between the pressure chamber 38 and the first tank pressure chamber 36. This has a groove formed by a valve 14 on the groove. The throttled drain ST serves to divert at least the excess pressure medium displaced from the floor space 112.

If in the in FIG. 4 shown position, the pressure on the regenerable port C2 decreases or if in the in FIG. 4 shown position of the pressure at the terminal C1 increases, and in particular when approximately balanced pressure conditions prevail at the check valve 16, then closes the check valve 16 via its closing spring 64. Thus, the regeneration is terminated.

FIG. 5 shows the control valve 1 of the valve arrangement 1, 2 according to the invention according to FIG. 3 in normal or working mode. This is also by the in FIG. 4 shown regeneration and working position a of the spool 14 achieved. In this case, the pressure medium flows from the pump pressure chamber 46, via the metering pressure chamber 44, via the (in FIG. 5 ) right section of the bridge channel 40 and the pressure chamber 50 to the working port B. The doing of the variable displacement pump 4 (see. FIG. 1 ) conveyed pressure medium continues to act on the (in FIG. 5 ) Left portion of the bridge channel 40 and the throttle 18, the check valve 16 formed in the interior of the spool 14, whereby it is closed.

The directional control valve or control valve 1 is equipped with a Regerations spool 14. The cross section of the throttled drain ST serves to relieve pressure at the moment of load reversal. The hydraulically controlled check valve 2 is arranged in the first application example with the regenerable annulus 10 between the rod side or the annular space 10 and the bottom side or the bottom space 12 of the differential cylinder 8. As long as the load of the equipment pulls on the rod of the differential cylinder 8, the check valve 2 remains closed. As soon as the tensile force acting on the differential cylinder 8 reverses into a compressive force and the pressure on the bottom side becomes greater than on the rod side, the check valve 2 opens the rod side to the tank T and the pressure force of the cylinder bottom is available as a working force.

A changeover switch is integrated in the spool valve 14 of the control valve 1. In neutral position 0 of the spool 14 of the therein incorporated switching piston 60 is not connected to the pump port P and the working ports A, B, he thus has no influence on the internal leakage, since it is connected downstream of the closed control edges.

In FIG. 4 with the first application example, the spool 14 is in the "cylinder extension" position a and the differential cylinder 8 acts due to the weight of the equipment a pulling load. The bar-side pressure thus results from the towing load plus the ground pressure increased by the area ratio. Thus, the prevailing at port A pressure is higher than the pressure in port B. The switching piston 60 is thus held against the closing spring 64 in the position shown and the entire displaced by the rod side flow is directed to the bottom side of the differential cylinder 8. For the same positioning speed less volume flow from the variable displacement pump 4 is required.

In FIG. 5 With the first application example, a digging position is shown in which the soil resistance increases and the pressure difference between the working ports A, B decreases. The smaller pressure difference leads to a reduction in the volume flow from the working port A to the working port B, the movement becomes slower the greater the grave resistance becomes. When the pressure difference reaches the value preset by the closing spring 64, it displaces the switching piston 60. In this second position of the switching piston 60, the regeneration connection from the working connection A to the working connection B is interrupted and the side of the rod is connected to tank T, ie no pressure is generated on the side of the rod Counterpressure produced more and the differential cylinder 8 can extend with maximum power against the ground resistance.

The boom of the compact excavator, the mast of the loader and the boom of the telescopic loader are of pressure cylinders according to the in FIG. 4 shown second application example operated. When lowering or retracting the differential cylinder 108 more oil is displaced on the bottom side than the rod side can accommodate. Also in this case, the regeneration circuit according to the invention can be applied to lower almost without hydraulic pump power. The excess volume flow, which corresponds to the rod volume is controlled via control notches of the throttled drain ST from the pressure chamber 38 via the first tank pressure chamber 36 to the tank 6.

With reference to FIG. 5 reached when lowering the differential cylinder 108 according to the second application example of the working equipment of the soil and the external load is no longer based on the differential cylinder 108 but on the ground. Since the pressure difference disappears due to the external load, the spring-loaded switching piston 60 interrupts the connection from A to B and connects the bottom-side working port A with tank 6. A limited volume flow from the pump port P via the metering orifice D to the working port B causes a reversal of the external load The work equipment presses on the ground and the machine can be lifted.

Notwithstanding the embodiment shown in the figures can be omitted in the first application example in which the annular space 10 of the differential cylinder 8 is connected to the regenerable port C2, provided in the spool valve 14 throttled drain ST to the tank 6. Instead of the throttled drain ST can be provided at the common regeneration and working position a of the spool 14 is a shut-off of the return from the port A to the tank port T of the control valve 1. Thus, in the regeneration, the entire pressure medium from the annulus 10 via the control valve 1 in the bottom space 12 is performed.

Instead of in the FIGS. 3 to 5 shown load-holding valve 54 may be provided in the bridge channel 40, a pressure compensator according to the principle of load-independent flow distribution (LUDV).

Disclosed is a valve arrangement for a mobile work machine with a metering or control valve, via which a regenerable connection and a further connection of a consumer - eg working cylinder or motor - the mobile working machine can be supplied. There is a - preferably separate - regeneration valve with only two switch positions (fully open, fully closed) provided over the pressure medium from the regenerable connection in a tank can be derived. Above a predetermined pressure difference between the terminals, the regeneration valve is open and otherwise closed. A main or spool of the control valve has a common regeneration and Working position. The spool thus has no along a displacement path of the spool from the regeneration position spaced working position, so that no active switching between working and Regernationsbetrieb is necessary.

LIST OF REFERENCE NUMBERS

1

control valve

2

check valve

4

variable

6

tank

8th; 108

differential cylinders

10; 110

annulus

12; 112

floor space

14

spool

16

check valve

18

throttle

20

valve body

22

control line

24

Working line section

26

Rifle

28

casing

30

closing spring

31

Control pressure chamber

32

opening piston

33

opening area

34

longitudinal axis

36

first tank pressure chamber

38

pressure chamber

40

bridge channel

42

first bridge pressure chamber

44

Zumess-pressure chamber

46

Pump pressure chamber

48

second bridge pressure chamber

50

pressure chamber

52

second tank pressure chamber

54

Load-holding valve

56a, 56b

metering orifice

58

first radial bore

60

switching piston

62

second radial bore

63

longitudinal bore

64

closing spring

65

Pressure signaling hole

66

annulus

68

sealing section

70

control edge

ST

throttled process

C1

further connection

C2

regenerable connection

V1

connection

A

working port

B

working port

D

metering orifice

P

pump connection

T

tank connection

0

initial position

a

Regeneration and working position

b

working position

Claims (16)

Valve arrangement (1, 2) for a mobile work machine with a control valve (1), via which a regenerable port (C2) and another port (C1) of a consumer (8; 108) can be supplied, wherein a regeneration valve (2) with only two switching positions is provided, via the pressure medium from the regenerable port (C2) in a tank (6) can be derived, and wherein the regeneration valve (2) above a predetermined pressure difference between the terminals (C1, C2) is open and otherwise closed, and wherein a spool (14) of the control valve (1) has a common regeneration and working position (a). Valve arrangement according to claim 1, wherein the spool (14) in the control valve (1) is continuously adjustable, and wherein a region at a displacement of the spool (14) is formed with common regeneration and working positions (a). Valve arrangement according to claim 1 or 2, wherein the Regerationsventil is a pilot operated check valve (2). Valve arrangement according to claim 3, wherein the check valve (2) with a tapped by the further terminal (C1) acting in the opening direction control pressure is directly controlled. Valve arrangement according to claim 3 or 4, wherein the check valve (2) has a closing spring (30) with low spring stiffness. Valve arrangement according to one of the preceding claims, wherein the consumer is a differential cylinder (8) whose annular space (10) is connected to the regenerable terminal (C2). A valve assembly according to claim 6, wherein the regeneration valve (2) has an opening area (33) and a shooting area, and wherein the closing area is smaller than the opening area. Valve arrangement according to claim 1 to 5, wherein the consumer is a differential cylinder (108) whose bottom space (112) is connected to the regenerable port (C2). The valve assembly of claim 8, wherein the regeneration valve has an opening area and a firing area, and wherein the closing area is greater than the opening area. Valve arrangement according to claim 1 to 5, wherein the consumer is a synchronous cylinder. Valve assembly according to claim 10, wherein the regeneration valve has an opening area and a shooting surface, which are about the same size. Valve arrangement according to one of the preceding claims, wherein in the common regeneration and working position (a) a Regerationsleitung is controlled, in which a from the regenerable terminal (C2) to the further terminal (C1) opening check valve (16) is arranged. Valve arrangement according to claim 12, wherein in or on the Regerationsleitung an adjustable throttle (18) is arranged. Valve arrangement according to claim 13, wherein the Regerationsleitung with the check valve (16) in the spool (14) is formed, and wherein the adjustable throttle (18) between the spool (14) and a housing of the control valve (1) is formed. Valve arrangement according to one of the preceding claims, wherein in the common regeneration and working position (a) of the regenerable Connection (C2) via a throttled drain (ST) to the tank (6) is connected. Valve arrangement according to claim 15, wherein the throttled drain (ST) on the spool (14) of the control valve (1) is formed.

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