DE102022202288A1 - Working device with a valve which has at least one separate emptying position - Google Patents

Abstract

The invention relates to a working device (10), in particular a front loader of an agricultural tractor. According to the invention, the control slide (40) of the valve (30) has, in addition to the lowering area (52), at least one emptying position (53; 54), which causes the tool (71) to lower more quickly than the lowering area (52).

Description

The invention relates to a working device according to the preamble of claim 1.

From the WO 18/070920 A1 a working device in the form of a front loader for an agricultural tractor is known. This includes a boom which can be pivoted at a first end with respect to a first axis of rotation by means of a first cylinder. At the opposite second end, a tool can be fastened in a tool holder, the tool holder being pivotable with respect to a second axis of rotation by means of a second cylinder. Various hydraulic valves are provided with which various functions of the front loader can be controlled.

From the applicant's data sheet "Load-sensing directional control valves in disk design SB24-EHS4, SB34-EHS4" (order number RD66174, edition 2021-11-11) a valve block is known that is particularly adapted to use in an agricultural tractor. The valve block is composed of several separate valve disks, each of which includes a control slide and a pressure compensator, with all valve slides being supplied with pressurized fluid in parallel by a pump. The individual valve disks can, among other things, be equipped with an electro-hydraulic pilot control device, for further details refer to the DE 10 2019 204 246 A1 is referred. Each valve disk is typically assigned a single cylinder or two hydraulic cylinders connected in parallel, the movement of which is controlled by the valve disk in question.

An advantage of the present invention is that the valve disks known from the above data sheet only have to be changed comparatively slightly in order to implement additional functions that are typically present in a front loader, without the usual use of separate, additional hydraulic valves. The other functions include, in particular, the quick emptying of the tool. Optionally, the tool can also be hydraulically locked in the tool holder.

According to claim 1, it is proposed that the valve comprises a control slide which is biased into a neutral position by means of at least one spring, wherein, starting from the neutral position, it is continuously adjustable in a first and an opposite second direction by means of at least one adjustable actuator, wherein in In the first direction, a lifting area immediately adjoins the neutral position, wherein in the lifting area the first working connection is fluidly connected to the inlet connection, with a corresponding first free flow cross-sectional area increasing steadily and monotonically starting from the neutral position in the first direction, with the second working connection also in the lifting area is fluidly connected to the return connection, with a lowering area directly adjoining the neutral position in the second direction, the second working connection being fluidly connected to the inlet connection in the lowering area, a corresponding second free flow cross-sectional area starting from the neutral position being continuous and monotonous in the second direction increases, wherein in the lowering area the first working connection is connected to the return connection, with at least one emptying position adjoining the lowering area in the second direction, wherein in each emptying position at least the first and the second working connection are fluidly connected to one another.

The working device is preferably operated with a pressurized fluid, which is most preferably a liquid and in particular hydraulic oil. The first and/or the second cylinder can each be formed by a single hydraulic cylinder or by two hydraulic cylinders connected in parallel. In the latter case, the two hydraulic cylinders are preferably designed identically. The valve can be assigned a load compensation, which includes, for example, a pressure compensator. In this case, the inlet connection or one of the two working connections can be fluidly connected to a load signaling channel. Beyond the fluidic connections of the valve in its various positions described in the present patent application, there are preferably no further fluidic connections within the valve.

The stressed fluidic connection between the first and the second working connection means that the tool can move almost at any speed under the influence of its own weight. The lowering speed is no longer limited by the maximum volume flow of a pump, as is the case in the lowering position. By quickly lowering the tool, a particularly complete emptying of the tool can be achieved in a very short time.

Advantageous developments and improvements of the invention are specified in the dependent claims.

A positioner can be provided, with which at least one positioner can be adjusted Actuator an actual size can be adjusted to a target size, a position sensor being provided, by means of which a position of the control slide can be measured as an actual size, the positioner and / or the at least one actuator being designed so that the control slide, starting from the stroke range, at a sudden adjustment of the target size in less than 300 ms, preferably in less than 100 ms, moves across the lowering range into the emptying position assigned to the selected new target size. The desired rapid emptying only occurs when the control slide is moved very quickly from the neutral position or from the lifting range across the lowering range into the at least one emptying position. It would be conceivable to carry out this quick movement by hand. However, the difficulty arises that it is no longer possible to stop the control slide in the desired emptying position just as quickly. In principle, this problem can be countered with a known position control of the control slide. However, known position controls of the control slide have the disadvantage that the movement of the control slide does not take place quickly enough for the present invention, especially in the very far outer areas of the possible stroke path of the control slide. Only when the position control is optimized as required with regard to the adjustment speed does the desired rapid emptying of the tool actually occur.

It can be provided that in a first emptying position the first and the second working port are connected to the inlet port, with the second cylinder being installed in such a way that the tool or the tool holder lowers in the direction of gravity. This embodiment leads to particularly quick emptying. It is certainly impossible for a vacuum to develop in the rapidly expanding chamber of the second cylinder because it is filled from the inlet connection. In the case of a synchronous cylinder, this only involves small amounts of fluid due to small tolerances. If the second cylinder is designed as a differential cylinder, it is preferably installed in such a way that pressurization of the larger piston side of the second cylinder causes the tool to lower or empty. From the inlet connection, only the small difference between the volume flow on the piston side and the volume flow on the rod side is replaced.

It can be provided that in a second emptying position the first and the second working port are connected to the return port, with the second cylinder being installed in such a way that the tool or the tool holder lowers in the direction of gravity. This embodiment leads to particularly quick emptying if the second cylinder is designed as a synchronous cylinder. The aforementioned connection to the return connection also allows the use of a differential cylinder, whereby a vacuum can then arise on the piston side, which is only insufficiently filled by suction from the tank.

It can be provided that the second cylinder is designed as a synchronous cylinder, with the first working connection being fluidly connected exclusively to the second working connection in a third emptying position, the second cylinder being installed in such a way that the tool or the tool holder is in the direction of Gravity lowers. The first to third emptying positions can all be present. In the simplest case, there is only the emptying position that best suits the actual design of the second cylinder. In the interests of cost-effective series production, the first and second emptying positions are preferably present. It should be noted here that the second emptying position can also be usefully used as a release position for a cylinder of a lifting gear of an agricultural tractor.

It can be provided that the tool holder comprises a locking device that can be actuated by means of a third cylinder, wherein a separate tool, in particular a shovel or a fork, can be positively locked with the tool holder by means of the locking device, with the lifting area or in the first direction being located the second direction connects a locking and an unlocking position to the lowering area, the valve having a locking and an unlocking connection to which the third cylinder is fluidly connected, the third cylinder in the locking position being connected to the inlet and/or the Return connection is fluidly connected so that the locking device moves into the locked position, wherein the third cylinder in the unlocking position is fluidly connected to the inlet and/or the return connection so that the locking device moves into the unlocked position, wherein the third cylinder is hydraulically clamped in at least one other position of the control slide, preferably in all other positions of the control slide.

The third cylinder is preferably hydraulically clamped in the neutral position, in the lowering range and in all emptying positions. Accordingly, in these positions it is impossible for the locking device to switch over on its own; in particular, it does not switch from the locked to the unlocked position. It is conceivable that the lifting range is designed in such a way that switching from the unlocked to the locked position of the locking device can already take place there. However, this has proven to be disadvantageous as it makes it difficult to insert the tool holder into the tool using the second cylinder. It is therefore preferred if the third cylinder is also hydraulically clamped in the stroke range.

It can be provided that the third cylinder is installed in such a way that pressurization of the locking connection causes the locking device to move into the locked position, with at least one valve assembly being connected between the locking connection and the third cylinder, each of which has a pressure relief valve and a includes a parallel-connected check valve, wherein an opening direction of the pressure relief valve is equal to a closing direction of the associated check valve. The terms opening direction and closing direction refer to the direction of flow of the fluid in the valve in question. Both the check valve and the pressure relief valve are preferably each designed as a leak-free seat valve. The valve assembly described can be flowed through in one direction with little resistance because of the check valve. In the opposite direction it only opens when the trigger pressure of the pressure relief valve is exceeded. As long as the above-mentioned triggering pressure is undershot, both the check valve and the pressure relief valve are sealed in a fluid-tight manner, so that switching of the locking device due to leaks is excluded. The third cylinder is preferably designed as a differential cylinder, with the larger piston side being fluidly connected to the locking connection.

It can be provided that two valve assemblies are connected in series, with the opening directions of the two check valves being directed in opposite directions. One valve assembly, namely the one through which flow can flow with little resistance towards the third cylinder, prevents the locking device from unintentionally unlocking due to leaks. The other valve assembly prevents the unlocked locking device from being locked when quickly passing through the locking position, with the third cylinder not moving at all.

It can be provided that the unlocking position is arranged further away from the neutral position than the locking position. This means that the control slide does not have to move past the unlocking position when it is moved from the locking position to the lifting position, the neutral position, the lowering position or in one of the emptying positions. This ensures that the locking device is not unlocked unintentionally. The unlocking position is preferably a position that is maximally far outward with respect to the stroke path of the control slide.

It can be provided that the positioner and/or the at least one actuator are designed in such a way that, starting from the unlocking position, the control slide moves beyond the locking position in less than 300 ms, preferably in less than 100 ms, in the event of a sudden adjustment of the target value moved into the further position assigned to the selected new target size. This rapid adjustment of the control slide ensures that the unlocked locking device is not locked again while the control slide moves beyond the locking position.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or alone, without departing from the scope of the present invention.

• 1 eine erfindungsgemäße Arbeitsvorrichtung.

The invention is explained in more detail below with reference to the accompanying drawing. It shows:

• 1 a working device according to the invention.

1 shows a working device 10 according to the invention. The working device 10 shown is designed as a front loader, as is used, for example, in an agricultural tractor. The corresponding boom 20 can also be the arm of a hydraulic excavator, which then has more than the two axes of rotation 22 shown; 25 has.

The working device 10 has a base 27, which can be fixed to a vehicle or stationary. On the base 27, an arm 20 is pivotally mounted at its first end 21 with respect to a first axis of rotation 22. By means of the first cylinder 23, which in the present case is designed as a differential cylinder, the boom 20 can be pivoted with respect to the first axis of rotation 22. At the second end 24 of the boom 20, which is opposite the first end 21, a tool 71 is pivotally mounted with respect to a second axis of rotation 25. The first and second rotation axes 22; 25 run parallel to each other, in this case perpendicular to the plane of the drawing 1 are aligned.

The separate tool 71, which in the present case is designed as a shovel, is detachably held in a tool holder 70, the tool holder 70 being pivotable with respect to the second axis of rotation 25. However, it is just as possible for the tool 71 itself to be pivotally mounted on the boom 20 with respect to the second axis of rotation 25.

The tool holder 70 can be pivoted with respect to the second axis of rotation 25 by means of a second cylinder 26, for example in order to load and unload the shovel shown. The second cylinder 26 is designed here as a synchronous cylinder, with the synchronous cylinder being shown purely symbolically in its simplest design. In fact, for example, a folded synchronous cylinder is used, such as the one in DE 10 2012 012 142 A1 is shown.

The second cylinder 26 is assigned a mechanical compensation mechanism 28, which causes the rotational position of the tool 71 to remain unchanged relative to the direction of gravity 11 when the first cylinder 23 is moved. It is conceivable that the compensation device 28 is dispensed with, with a comparable function being achieved purely electronically by controlling the second cylinder 26 in a suitable manner when the first cylinder 23 moves. The second cylinder 26 'can alternatively also be designed as a differential cylinder, whereby in 1 the preferred installation direction is shown. The valve 30 according to the invention is preferably designed so that both variants of the second cylinder 26; 26 'can be used without changes to the valve 30 being necessary. As a result, the valve 30 can be manufactured cost-effectively in larger quantities.

The valve 30 is formed, for example, by a valve disk, which is part of a valve block, which is shown in the applicant's data sheet “Load-sensing directional control valves in disk design SB24-EHS4, SB34-EHS4” (order number RD66174, edition 2021-11-11). . Contrary to what is shown in 1 The pump 12 therefore supplies several valves or valve discs. Another valve disk is preferably used to control the first cylinder 23.

The present invention has the advantage that the known valve disk, which is basically suitable for actuating the second cylinder 26, has to be modified comparatively slightly in order to implement the additional functions that are usual in an agricultural front loader and which have previously been implemented with separate hydraulic valves.

One of these additional functions is the so-called quick emptying. For example, if the tool 71 is designed as a shovel, there is a desire to tip the shovel very quickly in the direction of gravity 11 so that it is emptied as completely as possible in one fell swoop. It is indeed conceivable to carry out a comparable movement with the lowering area 52 of the valve 30. Then the movement speed of the tool 71 is limited upwards by the maximum volume flow of the pump 12. In the first and second emptying positions 53; 54 this is not the case.

A further additional function is the locking and unlocking of the tool holder 70 using a third cylinder 73. Within the scope of the invention, both additional functions can be implemented in such a way that the external dimensions of the valve disk in question are essentially unchanged compared to the other valve disks of the valve block, for which a total of four additional positions 53; 54; 55, 56 of the control slide 40, a very small stroke path of the control slide 40 is available. A locking of these additional positions 53; 54; 55, 56, so that they could be adjusted by hand, is not necessary. Such a locking mechanism would also fundamentally contradict the desire for a largely unchanged valve disk.

Furthermore, the electro-hydraulic pilot control device of the valve disk, which is preferably according to the DE 10 2019 204 246 A1 executed, can be adopted largely unchanged. Essentially, only changes to the software with which the position control is implemented are required. These are aimed at achieving a very quick adjustment in the very far outer stroke range of the control slide, which is nevertheless precise enough to achieve the additional positions 53; 54; 55; 56 to approach safely.

The present valve 30 has a central neutral position 50, which is biased by at least one spring 43. Starting from the neutral position 50, it can move in a first and an opposite second direction 41 by means of an actuator 44; 42 can be adjusted. The actuator 44 preferably comprises a 4/3-way proportional valve, which can be adjusted in two opposite directions by means of two electromagnets starting from a spring-loaded central position, the position of the control slide 40 of the valve 30 being adjusted hydraulically by means of this actuator 44. It is conceivable that the actuator 44 is formed by an electric motor, for example on the DE 10 2014 224 505 A1 is referred.

In the present case, the neutral position 50 is designed as a blocking position in which the inlet connection 33, which is connected to the pump 12, is blocked. This is therefore called a closed center valve. However, the present invention can also be used for open center valves in which the pressure compensator 15 is typically not present.

The present control slide 40 has a single continuously adjustable main aperture 46, which is completely closed in the neutral position 50, whereby it opens continuously and monotonously the further it moves in the first or second direction 41; 42 is moved away from the neutral position 50. The main aperture 46 accordingly defines both the first and the second free flow cross-sectional area according to claim 1. However, the present invention can also be used for a control slide which is based on the basic concept of DE 196 31 803 B4 is executed. There is 41 for the two actuation directions; 42 a separate, continuously adjustable main aperture is provided, each of which defines an associated first or second free flow cross-sectional area.

In the first direction 41, the neutral position 50 is immediately followed by a lifting area 51, in which the tool 71 is raised against the effect of gravity 11. The term “area” is intended to mean that a larger area of the stroke of the control slide 40 is used to adjust the free flow cross-sectional area of the main aperture 46 so that the desired movement speed of the second cylinder 26 results. In the “positions” 53; 54; 55; 56, the constant adjustability of the main aperture 46 is not utilized. These are positions that are firmly defined within a small tolerance range.

In the stroke area 51, the pressure fluid sucked in by the pump 12 from the tank 13 flows first via a pressure compensator 15, further via the inlet connection 33, further via the main orifice 46, further via a load signaling channel 47 to the first working connection 31 and from there to the second cylinder 26. The pressure fluid flowing back from the second cylinder 26 flows to the second working port 32 via the valve slide 40 to the return port 34 and from there to the tank 13.

The pressure at the inlet connection 33 acts on the pressure compensator 15 in the closing direction. The pressure in the load signaling channel 47 and the force of a preloaded control spring 16 acts on the pressure compensator 15 in the opening direction. The pressure compensator 15 accordingly regulates the pressure drop at the main diaphragm 46 to the pressure equivalent of the preload of the control spring 16. The volume flow that flows through the main diaphragm 46 therefore only depends on its free flow cross-sectional area and no longer on the load acting on the second cylinder 26.

The pressure in the load signaling channel 47 is also used to form the setpoint of the pump controller 14. If several valves are supplied with pressure fluid by the pump in parallel, the highest pressure from the pressures in the relevant load signaling channels is used. This highest load pressure is determined, for example, using a shuttle valve cascade. The pump controller 14 is designed, for example, as a pressure controller, which regulates the delivery pressure 17 of the pump 12 by adjusting the displacement volume of the pump 12 to a pressure which is above the stated highest load pressure by a predetermined pressure difference. The pump 12 is designed, for example, as an axial piston pump in a swash plate design, the displacement volume of which can be adjusted by pivoting a swivel cradle.

In the second direction 42, immediately adjacent to the neutral position 50, a lowering area 52 is arranged, which works analogously to the lifting area 51, with the first and second working ports 31; 32 are swapped so that the second cylinder moves in the opposite direction. The tool 71 is therefore lowered in the direction of gravity 11.

A positioner 60 is assigned to the valve. Its actual size 61 is the position of the control slide 40 measured with the position sensor 45. The position sensor 45 works, for example, on the principle of the differential transformer (https://de.wikipedia.org/wiki/Differentialtransformator). The manipulated variable of the positioner 60 is the current that flows through the magnetic coil, which is required for the desired adjustment direction. The sign of the manipulated variable accordingly decides which of the two magnetic coils of the actuator 44 is supplied with current.

The actual value 62 is specified, for example, in the form of a digital value which corresponds to the desired position of the control slide 40. The positioner 60 is preferably a continuous linear controller, which is preferably implemented digitally and is calculated in discrete time. For example, it can be designed as a PID controller. In particular, by adjusting the P component of this positioner 60, the time that elapses until the actual variable 61 approaches the target variable 62 with sufficient accuracy can be influenced. Within the scope of the invention, it is conceivable that settings that cause very rapid adjustment are only used if the positions 53; 54; 55; 56 entered should be set or left. Especially in the lifting and lowering positions 51; 52, other settings of the positioner 60 can be used, which attach greater importance to the control accuracy.

In the second direction 42, the first and second emptying positions 53 adjoin the lowering area 52; 54 on. In the lowering area 52 and in the emptying positions 53; 54, the direction of movement of the tool 71 is the same, namely directed in the direction of gravity 11. The first and second emptying positions 53; 54 differ from the lowering area 52 in that the first and second working ports 31; 32 are fluidly connected to one another via the control slide 40. If the second cylinder 26 is designed as a synchronous cylinder, this leads to the tool 71 suddenly lowering under the influence of gravity 11. Theoretically, no pressurized fluid flows from the pump 12 or to the tank 13, so that this fluid connection could be shut off. In the first emptying position 53, however, the first and second working ports 31; 32 connected to the inlet connection 33 via the maximum open main panel 46. This ensures that both chambers of the second cylinder 26 are completely filled with pressurized fluid, regardless of how fast the tool 71 moves. If the second cylinder 26 'is designed as a differential cylinder, the required differential volume flow can be provided by the pump 12.

In the second emptying position 54, the first and second working ports 31; 32 fluidly connected to the return connection 34. The inlet connection 33 is blocked, with the pressure in the return connection 34 being present in the load signaling channel 47, so that the pump 12 can run essentially without pressure as long as no other valve disk requires pressurized fluid. The second emptying position 54 is primarily due to the desire that the valve 30 according to the invention should be suitable for other applications in addition to use in a front loader, in particular for cases in which a differential cylinder should move freely. In the case of a front loader, the second emptying position 54 can also be used to achieve an increased emptying speed compared to the lowered position, but this involves the risk that a vacuum will form in the rapidly increasing chamber of the second cylinder 26, which will result from suction the tank 13 is only insufficiently filled. This problem does not occur in the first emptying position 53.

The valve 30 also has a locking position 55 and an unlocking position 56, which are preferably only present if the working device 10 is also equipped with a locking device 72 for a tool 71 which can be detachably attached to a tool holder 70.

At this point it is important to point out a safety aspect that is of particular importance when designing the working device 10: Under no conceivable circumstance should the locking device unlock unintentionally. Unlocking may only take place if the valve 40 is deliberately placed in the unlocking position 56 by the operator. The case that the working device 10 with the locked tool 71 is not used for a long period of time should also be taken into account. Here it could happen that the third cylinder 73 slowly moves into the unlocked position under the influence of comparatively small external forces because leaks occur. For this reason, the locking device 72 includes the two valve assemblies 80.

First, the locking device 72 includes the third cylinder 73, which is preferably designed as a differential cylinder. Applying pressure to the larger piston side causes the locking device 72 to lock. With this installation direction of the third cylinder 73, it is conceivable to apply the same pressure to both cylinder sides in order to lock the locking device 72, with this option being possible 1 no use is made.

Compared to the valve disk known from the data sheet mentioned above, the valve 30 has an additional locking connection 35 and an additional unlocking connection 36, which are each fluidly connected to the third cylinder 73. The lock port 35 is connected to the piston side of the third cylinder 73, with the unlock port 36 connected to the rod side.

In the present case, the locking position 55 and the unlocking position 56 are arranged adjacent to the lifting region 51 in the first direction 41. This arrangement was chosen because the required installation space is available here. The locking position 55 and the unlocking position 56 could also be arranged at the opposite end of the control slide 40 purely in terms of their function. In both cases, however, it is preferred that the unlocking position 56 is further away from the neutral position 50 than the locking position 55. This takes into account the safety aspect mentioned above; unlocking only occurs when it is actually desired and not when the unlocking position 56 must be passed through for other reasons.

Between the locking port 35 and the second cylinder 26 are first and second valve assemblies 80a; 80b fluidically connected in series. Both valve assemblies 80 are preferably designed identically, differing only in terms of their installation direction or their flow direction. The valve assemblies 80 each include a pressure relief valve 81, to which a check valve 82 is fluidically connected in parallel, with both valves 81; 82 are each designed as a leak-free seat valve. In the opening direction of the pressure relief valve 81, the parallel check valve 82 is closed, so that a fluid flow can only flow when the opening pressure of the pressure relief valve 81 is exceeded. In the opposite direction of flow, the pressurized fluid can flow with little resistance via the check valve 82.

The first valve assembly 80a is installed in such a way that one would have to overcome the opening pressure of the associated pressure relief valve 81 if one wanted to move the third cylinder 73 from the locked to the unlocked position by an external force. The corresponding external force is so great that it is virtually impossible for this to occur accidentally.

The second valve assembly 80b acts in the opposite direction. It contributes to the fact that the locking device 72 is not locked when the control slide 40 is moved from the unlocking position 56 into the lifting area 51, whereby it briefly passes over the locking position 55.

In the neutral position 50, in the lifting area 51, in the lowering area 52 and in the first and second emptying positions 53; 54, the locking connection 55 and the unlocking connection 56 are blocked off, so that the third cylinder 73 is hydraulically firmly clamped. The locking device 72 accordingly maintains its setting when the control slide 40 is in the positions 50; 51; 52; 53; 54; 55 is located or is moved between them.

In the locking position 55, the pressurized fluid flowing in at the inlet connection 33 flows via the maximum open main aperture 46, further via the load signaling channel 47 via the control slide 40 to the locking connection 35, further via the pressure relief valve 81 of the second valve assembly 80b, further via the check valve 72 of the first valve assembly 80a to the piston side of the third cylinder 73. The pressure fluid flowing back from the rod side of the third cylinder 73 flows via the unlocking connection 36 via the control slide 40 to the return connection 33 and from there to the tank 13.

In the unlocking position 56, the pressure fluid flowing in at the inlet connection 33 flows via the control slide 40 to the unlocking connection 36 and from there on to the rod side of the third cylinder 73. The branch via the maximum open main panel 46 is blocked off at the end of the load signaling channel 47. This branched flow path is solely due to the concrete design implementation of the unlocking position on the control slide. An unbranched flow path analogous to the locking position 55 is theoretically also possible.

The pressure fluid flowing back from the piston side of the third cylinder 73 in the unlocking position 56 flows via the pressure relief valve 81 of the first valve assembly 80a via the check valve 82 of the second valve assembly 80b to the locking connection 35 and from there via the control slide 40 to the return connection 33 further into the tank 13 .

Reference symbols

10

Working device

11

Direction of gravity

12

pump

13

tank

14

Pump controller

15

Pressure compensator

16

Rule spring

20

boom

21

first ending

22

first axis of rotation

23

first cylinder

24

second ending

25

second axis of rotation

26

second cylinder

26'

second cylinder (alternative embodiment)

27

Base

28

balancing mechanism

30

Valve

31

first work connection

32

second working connection

33

Inlet connection

34

Return connection

35

Locking connection

36

Release port

40

control slide

41

first direction

42

second direction

43

Feather

44

Actor

45

Position sensor

46

Main aperture

47

Load reporting channel

50

Neutral position

51

Lifting range

52

sink area

53

first emptying position

54

second emptying position

55

Locking position

56

Unlocking position

60

Positioner

61

Actual size

62

Target size

63

Target/actual comparison

70

Tool holder

71

Tool

72

Locking device

73

third cylinder

80

Valve assembly

80a

first valve assembly

80b

second valve assembly

81

Pressure relief valve

82

check valve

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 18/070920 A1 [0002]
• DE 102019204246 A1 [0003, 0030]
• DE 102012012142 A1 [0024]
• DE 102014224505 A1 [0031]
• DE 19631803 B4 [0033]

Claims (10)

Working device (10), in particular a front loader, with a boom (20) which is pivotally mounted at a first end (21) with respect to a first axis of rotation (22), wherein it is pivoted relative to the first axis of rotation (22) by means of at least one first cylinder (23). ) is pivotable, with a tool (71) or a tool holder (70) being pivotally attached to a second end (24) of the boom (20) opposite the first, with respect to a second axis of rotation (25), the tool (71) or the tool holder (70) can be pivoted by means of a second cylinder (26; 26'), the second cylinder (26; 26') being connected to a first and a second working port (31; 32) of a valve (30), whereby the Valve (30) also has an inlet and a return connection (33; 34), the tool (71) or the tool holder (72) being movable against the effect of gravity (11) by pressurizing the first working connection (31), characterized in that the valve (30) comprises a control slide (40) which is biased into a neutral position (50) by means of at least one spring (43), starting from the neutral position (50) by means of at least one adjustable actuator (44). in a first and an opposite second direction (41; 42) is continuously adjustable, with a lifting region (51) directly adjoining the neutral position (50) in the first direction (41), the first working connection (31) being fluidly connected to the inlet connection (33) in the lifting region (51). , wherein a corresponding first free flow cross-sectional area increases steadily and monotonically starting from the neutral position (50) in the first direction (41), the second working connection (32) being fluidly connected to the return connection (34) in the lifting region (51), whereby in the second direction (42) a lowering region (52) directly adjoins the neutral position (50), wherein in the lowering region (52) the second working connection (32) is fluidly connected to the inlet connection (33), with a corresponding second free flow cross-sectional area starting from the neutral position (50) in the second direction (42) increases steadily and monotonically, with the first working end (31) being connected to the return connection (34) in the lowering area (52), with in the second direction (42) being connected to the Lowering area (52) has at least one emptying position (53; 54), wherein in each emptying position (53; 54) at least the first and second working ports (31; 32) are fluidly connected to one another. Working device (10). Claim 1 , wherein a positioner (60) is provided, with which an actual variable (61) can be adjusted to a target variable (62) by adjusting the at least one actuator (44), a position sensor (45) being provided, by means of which a position of the control slide (40) can be measured as an actual variable (61), the positioner (60) and/or the at least one actuator (44) being designed in such a way that the control slide (40), starting from the stroke range (51), moves in the event of a sudden adjustment of the Target variable (62) is moved in less than 300 ms, preferably in less than 100 ms, across the lowering range (52) into the emptying position (53; 54) assigned to the selected new target variable (62). Working device (10) according to one of the preceding claims, wherein in a first emptying position (53) the first and second working ports are connected to the inlet port (33), the second cylinder (16) being installed in such a way that the tool (71 ) or the tool holder (70) is lowered in the direction of gravity (11). Working device (10) according to one of the preceding claims, wherein in a second emptying position (54) the first and second working ports (31; 32) are connected to the return port (34), the second cylinder (26; 26 ') being installed in this way is that the tool (71) or the tool holder (70) lowers in the direction of gravity (11). Working device (10) according to one of the preceding claims, wherein the second cylinder (26) is designed as a synchronous cylinder, wherein in a third emptying position the first working connection (31) is fluidly connected exclusively to the second working connection (32), wherein the second cylinder ( 26) is installed in such a way that the tool or the tool holder lowers in the direction of gravity (11). Working device (10) according to one of the preceding claims, wherein the tool holder (70) comprises a locking device (72) which can be actuated by means of a third cylinder (73), wherein by means of the locking device (72) a separate tool (71), in particular a shovel or a Fork, with which the tool holder (70) can be locked in a form-fitting manner, with a locking and an unlocking position (55; 56), the valve (33) having a locking and an unlocking connection (35; 36), to which the third cylinder (73) is fluidly connected, the third cylinder (73) being in the locking position (55). is fluidly connected to the inlet and/or return connection (33; 34) so that the locking device (72) moves into the locked position, the third cylinder (73) in the unlocking position (56) being connected to the inlet and / or the return connection (33; 34) is fluidly connected so that the locking device (72) moves into the unlocked position, the third cylinder (73) being in at least one other position of the control slide (40), preferably in all other positions of the Control slide (40), is hydraulically clamped. Working device (10). Claim 6 , wherein the third cylinder (73) is installed such that pressurization of the locking port (35) causes the locking device (72) to move into the locked position, with at least between the locking port (35) and the third cylinder (73). a valve assembly (80) is connected, which each comprises a pressure relief valve (81) and a check valve (82) connected in parallel, an opening direction of the pressure relief valve (81) being equal to a closing direction of the associated check valve (82). Working device (10). Claim 7 , wherein two valve assemblies (80) are connected in series, with the opening directions of the two check valves (82) being directed in opposite directions. Working device (10) according to one of the Claims 6 until 8th , wherein the unlocking position (56) is arranged further away from the neutral position (50) than the locking position (55). Working device (10). Claim 9 , as far as this one Claim 2 is back-related, wherein the positioner (60) and/or the at least one actuator (44) are designed such that the control slide (40) moves from the unlocking position (56) in less than 300° when the target size (62) is adjusted abruptly ms, preferably in less than 100 ms, moves beyond the locking position (55) into the further position (50; 51; 52; 53; 54) assigned to the selected new target variable (62).

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