EP2722165A2 - Hydraulic circuit for a hydraulic axle and a hydraulic axle - Google Patents

Abstract

The circuit (6) has a reversible hydraulic machine (14) and control valves (58, 64) for switching between rapid motion and force motion of a piston (4). An outer return surface and an extending surface are switched into regeneration for the rapid motion by the valves. The outer return surface and an inner return surface are interconnected for the force motion by the valves. A shutoff valve (74) is provided in a pressurized agent flow path between the machine and the extending surface. A switching valve (70) is provided in the path between the machine and the inner return surface. The control valves are 2/2-way valves. The hydraulic machine is a hydraulic pump. An independent claim is also included for a hydraulic axle.

Description

The invention is based on a hydraulic circuit for a hydraulic axis and a hydraulic axis.

Under a hydraulic axis is in the context of this application, a hydraulic actuator, z. B. a hydraulic cylinder and the actuator with fluid-driving hydraulic or electro-hydraulic control arrangement or circuit understood. Such hydraulic axles are compact, powerful and powerful drives. These can be used in a variety of industrial automation applications, eg. For example, in presses, plastic machines, bending machines, etc. In particular, such drives are designed to at least two movements, namely a quick transfer movement - hereinafter referred to as rapid traverse or Eilhub - and a force-applying work movement - hereinafter as a power stroke, as a working stroke or as a press gear designated - to realize.

A known hydraulic axis shows the application DE 10 2009 043 034 the applicant. In a preloaded hydraulic system, a master cylinder, a rapid traverse cylinder and a reversible hydraulic machine are interconnected. About valves, the interconnection of Kanzponenten be changed so that one of several z. B. piston surfaces predetermined hydromechanical ratios is selected. Thus, the mentioned rapid strokes or strokes can be performed efficiently

The disadvantage of this solution is that the hydraulic axis is designed comparatively expensive device.

In contrast, the invention has for its object to provide a hydraulic circuit for a hydraulic axis, which leads to a device technology comparatively simple hydraulic axis. Another object of the invention is to provide a device engineering simply designed hydraulic axis.

This object is achieved with regard to the hydraulic circuit according to the features of patent claim 1 and with regard to the hydraulic axis according to the features of patent claim 11.

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

According to the invention, a hydraulic circuit is provided with a multi-surface cylinder. A piston of the multi-surface cylinder has two return surfaces and an extension surface, each defining a pressure chamber. A pressure fluid supply and - discharge of the pressure chambers via a reversible, especially variable speed, in particular durchschwenkbare hydraulic machine and control valves. These are provided for switching in particular between a rapid traverse and a force passage of the multi-surface cylinder. For the rapid traverse, a first retraction surface and the extension surface are preferably switched into regeneration by the control valves, that is to say the surfaces or their pressure chambers are substantially pressure-balanced. The regeneration of the retraction surface and the extension surface is in this case preferably possible in both directions of movement of the piston of the multi-surface cylinder. For the power gear both return surfaces or the pressure chambers are interconnected via the control valves.

This solution has the advantage that the piston of the multi-surface cylinder can be easily retracted and extended in rapid traverse. When extending the piston in rapid traverse pressure medium can then be discharged from the pressure chamber of the second return surface and fed to the pressure chamber of the extension surface via the hydraulic machine and by the control valves, wherein by the regeneration of the pressure chamber of the first Return surface displaced pressure medium is also led to the pressure chamber of the extension surface. Conversely, when the piston is retracted at high speed, the pressure chamber of the second retraction surface is charged with pressure medium, while pressure medium is released from the pressure chamber of the retraction surface, pressure medium released by the regeneration being supplied to the pressure chamber of the first retraction surface. In the power gear can be discharged from the two pressure chambers of the return surfaces advantageously by the control valves via the hydraulic machine when extending the piston and the pressure chamber of the Ausfahrfläche be supplied. When retracting the piston in the power gear can reverse discharged pressure medium from the pressure chamber of the extension surface via the hydraulic machine and the pressure chambers of the return surfaces by the control valves.

The circuit according to the invention thus makes it possible to move the piston of the multi-surface cylinder in both directions of movement at a high speed and a low force or at a low speed and a high force. Further, with the control valves, at least in the force passage upon extension of the piston, the pressure space of the extension surface can be shut off by a high-pressure side of the hydraulic machine to hold a force of the multi-surface cylinder, which makes further power supply via the hydraulic machine unnecessary.

Advantageously, a sum of the withdrawal surfaces corresponds approximately to the extension surface.

In a further embodiment of the invention, a first control valve in the pressure medium flow path between the hydraulic machine and the pressure chamber of the first return surface and a second control valve are provided as a control valve fluidly in series with the first control valve between the latter and the pressure chamber of the extension surface.

Advantageously, a shut-off valve is provided in addition to the control valves. This may be provided in the pressure medium flow path between the hydraulic machine and the pressure space of the extension surface. In the closed state of the shut-off valve can thereby advantageously not be discharged at the same time closed second control valve pressure medium from the pressure chamber of the Ausfahrfläche, whereby a pressure without the use of the hydraulic machine can be kept at the Ausfahrfläche substantially.

Preferably, a switching valve is provided in the pressure medium flow path between the hydraulic machine and the second return surface. Through the switching valve can be prevented together with the control valves a pressure medium discharge from the pressure chambers of the return surfaces. If all the valves are closed except for the second control valve, the pressure chambers of the return surfaces and the extension surface can be fluidly shut off by the hydraulic machine. Thus, by, preferably leakage-free locking of the pressure medium in the pressure chambers of the piston can be kept in any position without pressure medium must be supplied via the hydraulic machine. The shut-off can be done for example after reaching a desired pressing pressure. By shutting off the hydraulic axle is stiffened.

Preferably, a compensation memory, for example, a hydraulic accumulator with a bias voltage is provided. This may be connected via a first storage valve to a pressure medium flow path between the hydraulic machine and the shut-off valve and via a second storage valve to a pressure medium flow path between the hydraulic machine and the control valves. As bias for the balance memory, for example, about 1, about 2, about 3 or about 5 bar can be provided.

The balance memory can be used to compensate for differences and / or compression volume. For example, a fluid displacement amount of the pressure space of the extension surface minus a fluid displacement amount of the pressure space of the second return surface may be at least 70, 80, 90, 95, or 99% of a fluid intake amount of the pressure space of the first return surface. It is also conceivable that the fluid displacement amount of the pressure space of the extension surface minus the fluid displacement amount of the pressure chamber of the second return surface at least 101, 110, 115, 120 or 130% corresponds to the fluid receiving amount of the pressure chamber of the first return surface, wherein here the balance memory is provided for receiving the difference amount. Of course, it is conceivable that the difference amount can also be zero.

By the storage valves, the balance memory can be loaded by the hydraulic machine, in which, for example, the control valves, the shut-off valve and the Switching valve are closed so that the loading of the accumulator without influence on the multi-surface cylinder takes place. For example, if the switching valve and the control valves are opened and the shut-off valve is closed, the hydromachine, when a storage valve is opened, promote pressure fluid from the balance reservoir to the pressure spaces of the return surfaces and the extension surface, thereby biasing the multi-surface cylinder, resulting in a fixed position of its piston leads. A biasing of the multi-surface cylinder can thus be done without the supply of external pressure medium. Furthermore, it is possible to move the piston of the multi-surface cylinder under a certain bias, which greatly accelerates a power build-up at the end of a piston stroke. Advantageously, the balance memory can also be used in a decompression of the multi-surface cylinder, is promoted in the pressure fluid from the decompressed pressure chambers of the retreat surfaces or the Ausfahrfläche on the hydraulic machine in these.

Preferably, a check valve closing towards the reservoir can be provided fluidically parallel to a respective storage valve. The check valves can then serve as Nachsagventile. Furthermore, it is no longer necessary to open by biasing the valves when biasing the multi-surface cylinder of the storage valves.

In a further embodiment of the hydraulic circuit, a control valve is provided. With this, the pressure chamber of the first return surface with the first balance memory and the pressure chamber of the extension surface can be connected to a further second balance memory. Furthermore, with the control valve, the pressure chamber of the first return surface with the pressure chamber of the second reservoir and the pressure chamber of the extension surface can be connected to the first balance memory. The second compensating accumulator can also be, for example, a hydraulic accumulator with a bias voltage. With the control valve can be done a fine positioning of the piston of the multi-surface cylinder, wherein the hydraulic machine can be inactive.

It is conceivable that the second compensating accumulator can be fluidically connected to the hydraulic machine via a further accumulator valve, in particular for loading. Preferably, the second balance memory is connected in the pressure medium flow path between the shut-off valve and the hydraulic machine via its storage valve.

The control valve may be, for example, a pulse width modulated control valve, which in particular has no leakage.

Preferably, the switching valve is arranged fluidically parallel to the first control valve.

To avoid overpressure in the hydraulic circuit, at least one pressure relief valve is provided. It is conceivable to secure the pressure chambers of the multi-surface cylinder via one or more pressure relief valves.

In the hydraulic machine, the speed and / or a stroke volume is advantageously adjustable, which in turn makes it possible to set an extension and retraction speed of the piston of the multi-surface cylinder. The hydraulic machine is advantageously driven by a drive unit in the form of an electric servomotor.

Preferably, the control valves, the shut-off valve, the switching valve and the storage valves are designed as Wegesitzventile.

According to the invention, the hydraulic axis is designed as a structural unit. The assembly of the hydraulic axis in this case has in particular the inventive hydraulic circuit, the controllable via the circuit multi-surface cylinder and the valves - in particular the control valves, the shut-off valve, the switching valve and the storage valves - having control block. Furthermore, the structural unit of the hydraulic axis has the hydraulic machine and a drive unit, which may in particular be the electric servomotor. In addition, the compensation volume can be provided in the unit.

Due to the design of the hydraulic axis as a unit, this is extremely compact and can be used flexibly in a variety of installation positions. The arrangement of the hydraulic machine and the drive unit in the unit, it is not necessary for the unit external energy, except electrical energy to provide. The hydraulic axis can be designed as a unit with a closed hydraulic circuit, which can then be hermetically sealed against its environment.

Advantageously, at least two cylinder connections for the multi-surface cylinder are formed on the control block as connection surfaces or bores. This means that no pipes are necessary for these two cylinder connections. The multi-surface cylinder can then be flanged directly on the control block, which increases the compactness of the hydraulic axis.

Further, the balance memories may be mounted directly on the control block for increasing the compactness of the hydraulic axis.

In a further embodiment of the hydraulic axis of the control block serves as a machine housing for the hydraulic machine. This can thus be sunk into the control block, with an installation space for the hydraulic machine in the control block can be used as a leak oil collection.

A fluidic connection of the hydraulic machine in the control block is simply carried out preferably via pipe nipple or pipe insertion nipple.

It is conceivable that a displacement sensor for detecting a piston position of the piston of the multi-surface cylinder is provided for controlling the multi-surface cylinder, which is integrated, for example, in this. It would also be conceivable to arrange the displacement sensor outside the multi-surface cylinder. To control the pressures in the multi-surface cylinder pressure sensors may be provided for measuring these pressures.

• Figur 1 in einem hydraulischen Schaltplan eine erfindungsgemäße hydraulische Achse mit einer erfindungsgemäßen hydraulischen Schaltung gemäß einer ersten Ausführungsform,
• Figur 2 einen vergrößerten Ausschnitt aus Figur 1 im Bereich eines Mehrflächenzylinders und
• Figur 3 in einem hydraulischen Schaltplan die erfindungsgemäße hydraulische Achse mit der erfindungsgemäßen hydraulischen Schaltung gemäß einer zweiten Ausführungsform.

In the following, preferred embodiments of the invention are explained in more detail with reference to drawings. Show it:

• FIG. 1 3 a hydraulic circuit diagram of a hydraulic axis according to the invention with a hydraulic circuit according to the invention, according to a first embodiment,
• FIG. 2 an enlarged section FIG. 1 in the area of a multi-surface cylinder and
• FIG. 3 in a hydraulic circuit diagram, the hydraulic axis according to the invention with the hydraulic circuit according to the invention according to a second embodiment.

According to FIG. 1 the hydraulic axis 1 according to the invention is shown. This has a multi-surface cylinder 2, which is used in particular for hydraulic presses. For adjusting a piston 4 of the multi-surface cylinder 2, a hydraulic circuit 6 is provided. This is arranged in a control block 8 and forms together with the multi-surface cylinder 2 and a drive unit 10 in the form of an electric servomotor, a structural unit.

Via a drive shaft 12, the drive unit 10 is connected to a hydraulic machine 14. The hydraulic machine 14 is used in the hydraulic axis 1 as a hydraulic pump, which is pivotable, whereby its delivery volume is adjustable. Advantageously, the hydraulic machine 14 is formed within the control block 8 by forming a pump housing for the hydraulic machine 14. An installation space of the control block 8 for the hydraulic machine 14 then serves as a leak oil collection. For easy connection of the hydraulic machine 14 in the installation space of the control block 8 pipe nipples are provided to connect the hydraulic machine 14. The hydraulic machine 14 can be operated in both directions of rotation and driven by the drive unit 10 in both directions of rotation. The drive unit 10 is designed such that it can drive the hydraulic machine 14 with an adjustable speed. With the hydraulic machine 14, a first, second and third pressure chambers 16, 18 and 20 of the multi-surface cylinder 2 can be charged with pressure medium and pressure medium can be discharged via the hydraulic machine 14 from the pressure chambers 16, 18 and 20.

The piston 4 of the multi-surface cylinder 2 is slidably guided in a cylinder housing 24 of the multi-surface cylinder 2. Based on the enlarged view in FIG. 2 the multi-surface cylinder 2 will be explained in more detail below.

According to FIG. 2 the piston 4 of the multi-surface cylinder 2 has a piston portion 26 which separates the annular third pressure chamber 20 from an air space 28 in the cylinder housing 24. The air space 28 is preferably pressure-balanced via a cylinder vent 30 with an environment of the hydraulic axis 1. A rod portion 32 of the piston 4 passes through the cylinder housing 24 and thus the third pressure chamber 20 in a direction away from the air space 28. The piston 4 has a cylindrical interior into which a guide rod 34 projects. This extends approximately coaxially with the cylinder housing 24, starting from an air space 28 limiting bottom surface 36 of the cylinder housing 24, passes through the piston portion 26 via a through hole 38 and opens into the cylinder chamber of the piston 4. At its arranged in the cylinder chamber of the piston 4 end portion, the guide rod 34 has a radial collar 40 whose outer diameter corresponds approximately to the inner diameter of the cylinder space of the piston 4. With this, the guide rod 34 separates in the piston 22, the first pressure chamber 16 from the second annular pressure chamber 18. By the guide rod 34, the air space 28 is also annular. The guide rod 34 is slightly shorter in the axial direction than the cylinder housing 24 and ends approximately at the beginning of a through hole 42 in the cylinder housing 24 through which the rod portion 32 of the piston 22 is slidably guided.

The first pressure chamber 16 within the piston 22 is delimited by an extension surface A1 acting in the extension direction, which points in the direction of the guide rod 34. The third pressure chamber 20 is bounded by a first outer retraction surface A3, which is formed on the piston section 26 of the piston 22. The second pressure chamber 18 is delimited by a second inner retraction surface A2, which in turn is formed opposite the extension surface A1 within the piston 22. It extends annularly around the guide rod 34. The return surfaces A2 and A3 in this case act in a retraction direction of the piston 22, a sum of the return surfaces A2 and A3 corresponds approximately to the extension surface A1.

In the first pressure chamber 16 opens a guide rod 34 in the axial direction passing through the first pressure channel 42 which is connected to a first pressure line 44 of the control block 8. The second pressure chamber 18 is fluidly connected to a second pressure channel 46, which is also formed in the guide rod 34 and extending from the control block 8 toward the radial collar 40 and opens approximately radially in the second pressure chamber 18 before the radial collar 40. The second pressure channel 46 is connected to a second pressure line 48 of the control block 8. The third pressure chamber 20 is connected to a third pressure line 50 which is connected on the one hand to the cylinder housing 24 and the other to the control block 8. At the control block 8, the third pressure line 50 is connected to a pressure line 52 formed in the control block 8. The first and second pressure lines 44, 48 open into an outer surface of the control block 8. The mouth region serves for the multi-surface cylinder 2 as a cylinder connection and is designed as a connection surface 53.

To the hydraulic machine 14 is according to FIG. 1 at the first pump port A, a first pump line 54 and at the second pump port B, a second pump line 56 is connected. The first pump line 54 is connected to a pump port P of a first control valve 58. This has in addition to the pump port P a working port X which is connected to the pressure line 52, which in turn fluidly with the third pressure chamber 20 of the multi-surface cylinder 2 from FIG. 2 is in pressure medium connection. The first control valve 58 is designed as a 2/2-way valve. A valve piston of the first control valve 58 is acted upon via a valve spring 60 in the direction of a closed position with a spring force in which a pressure medium connection between the pump port P and the working port X is disconnected. In the direction of an open position, the valve slide of the control valve 58 can be acted upon by an actuator 62, which is, for example, an electric lifting magnet, with a force, in particular with a magnetic force. In the open position of the pump port P to the working port X is in fluid communication.

Fluidically in series with the first control valve 58, a second control valve 64 is provided, which also has a working port X and a pump port P. The working port X is in this case connected to the pressure line 52 via a branch line 66. The pump port P of the second control valve 64 is connected via a further branch line 68 to the first pressure line 44 and thus communicates with the first pressure chamber 16, see FIG. 2 , in pressure medium connection. The second control valve 64 is also a 2/2-way valve, wherein, in contrast to the first control valve 58 whose valve spool is movable via the valve spring 60 in an open position and the actuator 62 in a closed position. The valve spool of the second control valve 64 is thus in the de-energized state in the open position, in which the pump port P to the working port X and thus the third pressure chamber 20 is fluidly connected to the first pressure chamber 16.

The second pressure line 48, which is fluidically connected to the second pressure chamber 18, is connectable via a switching valve 70 to the first pump line 54. In this case, the switching valve 70 corresponds to the first control valve 58 and has a working port X and a pump port P. The second pressure line 48 is connected to the working port X and the pump port P is connected to the first pump line 54 via a branch line 72.

To the second pump line 56, the first pressure line 44 and thus also the branch line 68 is connected via a shut-off valve 74. This is formed according to the first control valve 58 and has a working port X, to which the first pressure line 44 is connected, and a pump port P, to which a branch line 76 is connected, which is connected to the second pump line 56.

The pump lines 54 and 56 connected to the hydraulic machine 14 can furthermore be connected to a compensating accumulator 78, which can be designed as a hydraulic accumulator and is preferably arranged or designed in the control block 8. It would also be conceivable to connect this to the control block 8. For fluidically connecting the equalizing reservoir 78, a first accumulator line 80 branches off from the first pump line 54 and a second accumulator line 82 branches off from the second pumping line 56. The first storage line 80 is connected to a pump port P of a first storage valve 84 and the second storage line 82 is connected to a pump port P of a second storage valve 86. The storage valves 84 and 86 are formed corresponding to the first control valve 58 and each have a storage port S on. These are connected to a common memory line 88, which in turn is connected to a memory terminal S of the balance memory 78. Hydraulically parallel to the first storage valve 84, a first Nachsaugleitung 90 is provided, which is arranged on the storage line 88 and the first pump line 54. In the first Nachsaugleitung 90 a first towards the balance memory 78 closing check valve 92 is arranged. The first Nachsaugleitung 90 with the first check valve 92 thus branches off in the pressure medium flow path between the first control valve 58 and the hydraulic machine 14 from the first pump line 54. A further second Nachsaugleitung 94 is fluidly arranged parallel to the second accumulator valve 86 between the balance memory 78 and the second pump line 56 and also has a toward the balance memory 78 closing second check valve 96. The second Nachsaugleitung 94 is thus connected to the second pump line 56 in the pressure medium flow path between the hydraulic machine 14 and the shut-off valve 74.

Due to the design of the hydraulic axle 1 as a unit, this is extremely compact. In the control block 8 are the hydraulic machine 14, the balance memory 78, the control valves 58, 64. the switching valve 70, the check valve 74 and the Nachsaugventile 92nd 96 arranged. The multi-surface cylinder 2 and the drive unit 10 are simply connected to the control block.

In the following, the operation of the hydraulic axis 1 will be explained in more detail.

Extend rapid traverse:

When the piston 4 is extended at rapid traverse, the valve spool of the switching valve 70 and of the shut-off valve 74 is in its open position. The other valves 58, 64, 84 and 86 are de-energized. The hydraulic machine 14 delivers pressure medium from its pump port A to its pump port B. It thus promotes pressure fluid from the second pressure chamber 18 via the switching valve 70, the first pump line 54 to the second pump line 56 and from there via the shut-off valve 74 into the first pressure chamber 16. Der Pressure chamber 16 is in this case fluidly connected via the second control valve 64 to the third pressure chamber 20 and pressure balanced. The extension surface A1 of the piston 4, see FIG. 2 , is thus acted upon via the first pressure chamber 16 with a higher pressure in the extension direction than the second return surface A2 of the piston 4 in the closing direction, which is why the piston 4 extends. The displaced from the third pressure chamber 20 pressure medium is supplied to the first pressure chamber 16 via the second control valve 64. By the connection of the first pressure chamber 16 with the third pressure chamber 20, the extension surface A1 and the first return surface A3 are connected in regeneration.

Extend power gear:

Extend in the power gear of the piston 4 of the hydraulic axis 1, the first control valve 58, the switching valve 70 and the shut-off valve 74 are energized via its actuator and thus its valve slide in its open position. Furthermore, the second control valve 64 is energized, whereby its valve spool is in the closed position. About the first control valve 58 and the switching valve 70, the second and third pressure chamber 18, 20 are interconnected. The hydraulic machine 14 in this case promotes pressure medium from its pump port A to its pump port B, whereby it discharges pressure medium from the second and third pressure chamber 18, 20 and the first pressure chamber 16 via the shut-off valve 74 so charged. The piston 4 thus moves out of power.

Extend decompression after power transmission:

During decompression, the hydraulic machine 14 delivers pressure fluid from its pump port B to its pump port A. The shut-off valve 74 and the first reservoir valve 84 are energized, whereby their valve spool is in its open position. The second control valve 64 is also energized, whereby the valve slide is in its closed position. The first control valve 58, the switching valve 70 and the second accumulator valve 86 are de-energized and their valve spool is in its closed position, the hydraulic machine 14 now promotes pressure medium from the first pressure chamber 16 via the shut-off valve 74 into the first pump line 54 and from there via the first Storage valve 84, the storage line 88 to the balance memory 78th

Retracting speed:

Retracting at the inlet, the hydraulic machine 14 conveys pressure fluid from its pump port B to its pump port A. The shut-off valve 74 and the switching valve 70 are energized, whereby their valve spool is in its open position. The first and second control valves 58, 64 and the first and second storage valves 84, 86 are de-energized. The valve spool of the second control valve 64 is thus in its open position. Via the second control valve 64, the extension surface A1 and the first withdrawal surface A3, see FIG. 2 , switched to regeneration, the hydraulic machine 14 now promotes pressure fluid from the first pressure chamber 16 via the shut-off valve 74 and the switching valve 70 to the second pressure chamber 18, whereby the piston 4 moves in the retraction direction. From the first pressure chamber 16 displaced pressure medium is additionally supplied to the third pressure chamber 20 through the regeneration via the second control valve 64.

Retract power gear:

The hydraulic machine in this case promotes pressure fluid from the pump port B to the pump port A. The first control valve 58, the second control valve 64, the switching valve 70 and the shut-off valve 74 are energized in this case. The valve spool of the second control valve 64 is thus in its closed position and the valve spools of the first control valve 58, the switching valve 70 and the shut-off valve 74 are in their open position. The storage valves 84 and 86 are de-energized, bringing their valve spool in the closed position. The hydraulic machine 14 then delivers pressure medium from the first pressure chamber 16 via the shut-off valve 74 into the first pump line 54 and from there on via the first control valve 58 to the third pressure chamber 20 and via the switching valve 70 to the second pressure chamber 18. Missing compression volume is via the second check valve 96 sucked from the balance memory 78. The piston 4 then enters the power gear.

Retract decompression after power transmission:

In this case, the hydraulic machine 14 conveys pressure medium from the pump connection A to the pump connection B. The first and second control valve 58, 64, the switching valve 70 and the second storage valve 86 are energized in this case. The valve spool of the second control valve 64 is thus in its closed position and the valve spool of the first control valve 58, the switching valve 70 and the second accumulator valve 86 are in their open position. The valve spool of the shut-off valve 74 and the first accumulator valve 84 is de-energized in its closed position. The hydraulic machine 14 thus conveys pressure fluid from the second and third pressure chambers 18, 20 into the second pumping power 56 and from there via the second storage valve 86 and the storage line 88 to the balance memory 78, whereby it is charged.

Pressure maintenance phase:

In the pressure holding phase, only the second control valve 64 is energized, whereby the valve spool of the control valves 58, 64, the switching valve 70, the Absperventils 74 and the storage valves 84, 86 are in their closed position. Due to the closed position of this valve slide the pressure chambers 16 to 20 are fluidically disconnected from the hydraulic machine 14 and the pressure medium can not escape from these. The piston 4 is thus clamped in its position so that it can neither extend nor retract.

Pressure build-up phase for preload:

Here, the first control valve 58 and the switching valve 70 are energized, whereby the valve slide are in their open position. All other valves 74, 84, 86 and 64 are de-energized. The valve spool of the second control valve 64 is thus also in his Open position. The hydraulic machine 14 delivers pressure medium from its pump port B to its pump port A. Pressure medium is thus conveyed from the balance memory 78 via the second check valve 96 in the first pump line 54 and passes from there via the switching valve 70, the first control valve 58 and the second control valve 64 in the pressure chambers 16 to 20. By the open valves 58, 64 and 70, these are pressure balanced. The return surfaces A2 and A3 and the extension surface A1, see FIG. 2 , are thus biased with a same pressure.

In FIG. 3 For example, according to a second embodiment, the hydraulic axis 98 additionally has a control valve 100 and a compensating accumulator 102 with a third accumulator valve 104.

The control valve 100 is designed as a 4/3-way valve and has a first storage port S1, a second storage port S2, a first working port X1 and a second working port X2, A valve spool of the control valve 100 is spring-centered via two valve springs 106 and 108 in its middle closed position in which the terminals S1, S2, X1 and X2 are separated from each other. In the direction of first open positions, the valve slide is displaceable via an electric actuator 110, in which the first working connection X1 is connected to the first storage connection S1 and the second working connection X2 is connected to the second storage connection S2. In the opposite direction, the valve slide is displaceable with another electric actuator 112 starting from its closed position in the direction of second open positions, in which the first working port X1 is connected to the second storage port S2 and the second working port X2 is connected to the first storage port S1. The first working port X1 is connected via a branch line 114 to the branch line 66 and thus to the pressure line 52 connected to the third pressure space 20. With a branch line 116 of the second working port X2 of the control valve 100 is connected to the first pressure line 44 and thus with the first pressure chamber 16 in fluid communication. The second storage port S2 is connected to the storage line 88 by a branch line 118 and is thus in fluid communication with the equalization memory 78. The first storage port S1 is connected to a storage line 120, which in turn is connected to a storage port S of the equalization memory 102.

Via the third storage valve 104, the storage line 120 is connected to the second pump line 56. The third accumulator valve 104 is designed in accordance with the first control valve 58 and thus has a pump port P and a working port X. The pump port P is connected via a branch line 122 to the second pump line 56 and the working port X via a branch line 124 to the storage line 120.

The control valve 100 is continuously adjustable and serves for fine positioning of the piston 4 of the multi-surface cylinder. 2

In the following, the operation of the hydraulic shaft 98 according to the second embodiment will be explained.

Storage charging mode:

With the hydraulic axis 98 off FIG. 3 can in addition to the hydraulic axis 1 off FIG. 1 a memory loading mode are executed. For charging the second accumulator 102, the third accumulator valve 104 is energized, whereby the valve slide is in its open position. All other valves are de-energized except for the second control valve 64, whereby the valve spool corresponding to the valve spool of the other valve 58, 70, 84, 86, 74, 100 is in its closed position. The hydraulic machine 14 conveys pressure fluid from the pump port A to the pump port B and thus from the first balance memory 78 via the first check valve 92 in the second pump line 56 and from there via the third storage valve 104 in the second balance memory 102. This takes place until the desired pressure is reached in the balance memory 102. After reaching the desired pressure, the energization of the third storage valve 104 is interrupted and the valve slide is moved to its closed position, whereby the pressure medium in the balance memory 102 remains.

Control mode:

During normal operation of the hydraulic axis 98, the switching valve 70 and the second control valve 64 are energized. As a result, the valve spool of the switching valve 70 is in its Open position and the valve spool of the control valve 64 in its closed position. The valve spools of the first control valve 58, the check valve 74 and the storage valves 84, 86 and 104 are also in their closed position. The hydraulic machine 14 is not driven in this case. Via the control valve 100, either the first pressure chamber 16 can then be connected to the compensation reservoir 102 or the third pressure chamber 20 can be connected to the compensation reservoir 120. If the first pressure chamber 16 is connected to the compensating accumulator 102, the valve slide of the control valve 100 is in the open positions in which the second working port X2 is connected to the first accumulator port S1. The third pressure chamber 20 is then via the control valve 100, the branch line 118, the first check valve 92, the switching valve 70 with the second pressure chamber 18 in fluid communication. Thus, pressure fluid from the third pressure chamber 20 to the second pressure chamber 28 to flow.

If the third pressure chamber 20 is in pressure medium connection with the second compensating accumulator 102, then the valve slide of the control valve 100 is in the open position, in which the first working port X1 is connected to the first accumulator port S1 and the second operational port X2 is connected to the second accumulator port S2. The first pressure chamber 16 is then via the control valve 100, the branch line 118, the first check valve 92 and the switching valve 70 with the second pressure chamber 18 in fluid communication, which then pressure medium from the first pressure chamber 16 in the second pressure chamber 18 can flow.

By the control valve thus a position control of the piston 4 by mutually connecting the pressure chambers 16 and 20 with the second balance memory 102 is possible.

Disclosed is a hydraulic circuit for a multi-surface cylinder. Its piston has two retraction surfaces and an extension surface. A swing-through hydraulic machine allows the piston of the multi-cylinder to be extended and retracted. For switching between a rapid traverse and a force passage of the piston control valves are provided. The control valves are arranged such that for the rapid traverse a first retraction surface and the extension surface in regeneration are switchable. Furthermore, the control valves are arranged such that both retraction surface can be interconnected for the power gear.

Furthermore, a hydraulic axle is disclosed, which is designed as a compact unit. Here, a control block is provided, in which a hydraulic circuit and the hydraulic machine are arranged. At the control block then the multi-surface cylinder and a drive unit for the hydraulic machine are flanged. The compact hydraulic unit can form a closed hydraulic circuit.

LIST OF REFERENCE NUMBERS

1

hydraulic axis

2

More surface cylinder

4

piston

6

hydraulic circuit

8th

control block

10

drive unit

12

drive shaft

14

hydromachine

16

first pressure chamber

18

second pressure chamber

20

third pressure chamber

24

cylinder housing

26

calf section

28

airspace

30

cylinder opening

32

slug

34

guide rod

36

floor area

38

Through opening

40

radial collar

42

first pressure channel

44

first pressure line

46

second pressure channel

48

second pressure line

50

third pressure line

52

pressure line

53

terminal area

54

first pump line

56

second pump line

58

first control valve

60

valve spring

62

actuator

64

second control valve

66

branch line

68

branch line

70

switching valve

72

branch line

74

shut-off valve

76

branch line

78

balancing tank

80

first storage line

82

second storage line

84

first storage valves

86

second storage valves

88

storage line

90

first suction line

92

first check valve

94

second suction line

96

second check valve

98

hydraulic axis

100

control valve

102

balancing tank

104

third storage valve

10G

valve spring

108

valve spring

110

actuator

112

actuator

114

branch line

116

branch line

118

branch line

120

storage line

122

branch line

124

branch line

A1

Ausfahrfläche

A2

second retreat area

A3

first retreat areas

A, B

pump connection

P

pump connection

X

working port

S

memory connector

S1

first storage port

S2

second storage port

X1

first work connection

X2

second work connection

Claims (14)

Hydraulic circuit for a multi-surface cylinder (2) having a piston (4) with two return surfaces (A2, A3) and an extension surface (A1), the circuit (6) comprising a reversible hydraulic machine (14) and control valves (58, 64) for switching between a rapid traverse and a power stroke of the piston (4), wherein with the control valves (58, 64) for the rapid traverse the return surface (A3) and the Ausfahrfläche (A1) in regeneration are switchable, and wherein with the control valves (58 , 64) for the power passage both return surfaces (A2, A3) are interconnected. The hydraulic circuit of claim 1, wherein the first control valve (58) in the fluid flow path between the hydraulic machine (14) and the return surface (A3) and the second control valve (64) fluidly in series with the first control valve (58) in the pressure fluid flow path between the latter and the extension surface (A1) is provided. A hydraulic circuit according to claim 1 or 2, wherein a check valve (74) is provided in the pressure medium flow path between the hydraulic machine (14) and the extension surface (A3). A hydraulic circuit according to any one of claims 1 to 3, wherein a switching valve (70) is provided in the pressure medium flow path between the hydraulic machine (14) and the return surface (A2). A hydraulic circuit according to claim 3 or 4, wherein a balance accumulator (78) is provided which communicates via a first accumulator valve (84) to a fluid flow path between the hydromachine (14) and the control valve (58) and via a second accumulator valve (86) Pressure fluid flow path between the hydraulic machine (14) and the shut-off valve (74) is connected. Hydraulic circuit according to claim 5, wherein a check valve (92, 94) closing towards the compensating accumulator (78) is provided fluidically parallel to a respective accumulator valve (84, 86). Hydraulic circuit according to claim 5 or 6, wherein a control valve (100) is provided, with which the return surface (A3) with the first balance memory (78) and the Ausfahrfläche (A1) with a second balance memory (102) is connectable and with the Return surface (A3) with the second balance memory (102) and the extension surface (A1) with the first balance memory (78) is connectable. Hydraulic circuit according to one of claims 4 to 7, wherein the switching valve (70) is arranged fluidically parallel to the first control valve (58). Hydraulic circuit according to one of the preceding claims, wherein a speed and / or a displacement of the hydraulic machine (14) is adjustable. Hydraulic axle comprising as assembly a hydraulic circuit (6), in particular according to one of the preceding claims, via the circuit (6) controllable multi-surface cylinder (2), the valves (58, 64, 70, 74, 84, 86, 100 ) comprising a control unit (8), a hydraulic machine (14) and a drive unit (10) for the hydraulic machine (14). Hydraulic axle according to claim 10, wherein at least two cylinder connections for the multi-surface cylinder (2) are formed on the control block (8) as connection surfaces (53) or bores. Hydraulic axle according to claim 10 or 11, wherein at least one compensating accumulator (78, 102) is mounted on the control block (8). Hydraulic axle according to one of claims 10 to 12, wherein the control block (8) is used as a machine housing for the hydraulic machine (14). Hydraulic axle according to claim 13, wherein the connection of the hydraulic machine (14) in the control block (8) takes place via pipe nipples.

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