EP3317088B1 - Electro-hydraulic drive unit - Google Patents

Description

The present invention relates to an electro-hydraulic drive unit, in particular for use on a machine press.

Electro-hydraulic drive units, such as are suitable and intended in particular for use on machine presses (namely for moving the respective tool up and down) are known in various designs and designs. Typically, the respective drive units are designed so that the piston (at least in one of the two directions of movement) can be moved at different speeds, namely on the one hand with a rapid traverse (with comparatively low achievable pressing force) and on the other hand with a power gear (with comparatively high achievable pressing force) , Two fundamentally different concepts of the electro-hydraulic drive of machine presses differ in that for the rapid downwards movement of the tool carrier / tool unit either an active loading of the sink working space of the cylinder-piston unit (s) from the (respective) hydraulic unit is required , Namely, because the permanently acting restoring force of a spring device is overcome, or the tool carrier / tool unit due to their own weight until the contact of the tool with the workpiece (braked) drops and only for the subsequent power stroke of the sink working space Cylinder-piston unit (s) from the (respective) hydraulic power unit is acted upon. For example, relevant to the prior art include the WO 2011/003506 A1 . US 2010/0212521 A1 . AT 8633 U1 . DE 102012013098 A1 . WO 2011/021986 A1 . EP 103727 A1 and DE 102013000725 A1 ,

The present invention is concerned with electro-hydraulic drive units, as are suitable for machine presses according to the second of the above-mentioned concepts (rapid downwards movement of the tool carrier / tool unit due to its own weight). Typical such electrohydraulic drive units include a cylinder-piston arrangement having a first hydraulic working space associated with a first direction of movement of the piston and a second hydraulic working space associated with an opposite second direction of movement of the piston, a hydraulic fluid storing tank, a hydraulic pump driven by an electric motor, one between the two Hydraulic pump and the cylinder-piston assembly switched, electrically controllable switching valves comprehensive valve assembly and acting on the switching valves and the electric motor machine control means of which the switching valves between acting on the first hydraulic working space and the second hydraulic working space of the cylinder-piston assembly in the pumping operation the hydraulic pump from the pressure port can be reversed.

Electro-hydraulic drive devices of the type in question here must in practice a number of Meet requirements that are partly in conflict with each other. Depending on the individual installation situation, more or less pronounced demands are demanded, in particular efficiency, compact dimensions, ease of maintenance, longevity, reliability, low production costs, high energy efficiency, operational safety, high dynamics, stable operating behavior even under strongly changing conditions and low noise emission.

The present invention has set itself the task of providing an electro-hydraulic drive unit, which forms a balanced, particularly practical compromise in terms of typical requirements, as they exist in particular in applications of machine presses.

This object is achieved according to the present invention by, as indicated in claim 1, in one of the features set forth above having electro-hydraulic drive unit, the hydraulic pump is designed as a 2-quadrant hydraulic pump, which by means of a (in particular designed as a servo motor) electric motor in pumping operation (For an active movement of the piston in both directions of movement, ie downwards for pressing in power and up to raise the tool carrier / tool unit) is driven variable speed in exactly one predetermined direction of rotation and a directly (ie typically without further controls) in the tank opening tank port and a pressure port, wherein the hydraulic pump further by means of the engine control in a braking operation with the Pump operation reverse rotational and flow direction is reversible. In this way, a powerful, reliable and reliable electro-hydraulic drive unit can be provided with comparatively low expenditure on equipment, which also meets the other requirements set out above to a high degree.

Particularly preferably, in the electro-hydraulic drive unit according to the invention, the cylinder-piston arrangement is oriented with at least substantially vertical movement axis, wherein the first direction of movement of a downward movement and the second direction of movement corresponds to an upward movement of the piston. And the hydraulic pump is both in a first movement phase (rapid-down), while (via the valve assembly) is a flow connection of the second hydraulic working space of the cylinder-piston assembly with the pressure port of the hydraulic pump, as well as in a second movement phase (decompression-up ), in which there is a flow connection of the first hydraulic working space of the cylinder-piston arrangement with the pressure connection of the hydraulic pump, in the braking operation uncontrollable.

Particularly preferred is a throttle (for example in the form of a nozzle) is provided, which is connected in braking mode in the second movement phase in series with the hydraulic pump. This relieves the hydraulic pump and limits its stress during braking operation during the second movement phase, so that possibly operating conditions (overspeeding) impairing process safety are avoided. In Alternative development that does not require such a throttle, takes place in the decompression phase, ie in the second phase of movement during braking operation, a pressure-dependent control of the speed of the hydraulic pump driving - or in this mode - braking electric motor. In that regard, a pressure sensor is provided in this case, which detects the pressure prevailing in the first hydraulic working space pressure and the signal is switched to the machine control.

According to another preferred embodiment of the invention, the hydraulic pump is disposed inside lying in the tank. This permits a course of the pressure line which follows the pressure outlet of the hydraulic pump, which is a considerable advantage from the point of view of operating safety and is furthermore favorable for minimizing the risk of external leaks. In addition, this is under aspects of low noise emission and a constant cooling of the hydraulic pump advantage.

Yet another preferred development of the electro-hydraulic drive unit according to the invention is characterized in that a flange and connection block is provided with a first flange for connection to a valve block housing the switching valves and a second flange surface for connection to the cylinder of the cylinder-piston arrangement. The flange and connection block can be arranged in particular to a predominant part of its volume in the tank and adjacent only with the two flange surfaces Edge areas more or less protrude from this. According to an alternative preferred development, however, the flange and connection block is arranged outside the tank, more preferably below its bottom. In the sense of the above embodiments, the hydraulic pump can be connected in particular via a pressure line extending inside the tank with a pressure connection provided on the flange and connection block, which in turn is connected via a channel to a pressure connection provided on the first flange surface; and on the first as well as the second flange surface may be provided in each case a hydraulic interface which comprises two communicating with the two working spaces of the cylinder-piston arrangement working ports.

According to yet another preferred embodiment of the invention, the valve block is housed in a lateral recess of the tank. In particular, such, the valve block receiving recess may be arranged in one of the corner regions of the tank.

Yet another preferred embodiment of the invention is characterized in that a hydraulically releasable Nachsaugventil is arranged in the tank. Particularly advantageous is the arrangement of the Nachsaugventils in a breakthrough of the above-described, arranged to a major part of its volume in the tank flange and terminal block; The suction valve can in turn a connection flange for direct connection with the cylinder of the cylinder-piston assembly respectively. In a preferred alternative development, the suction valve is completely integrated in the - arranged outside the tank - flange and connection block; only the latter is connected via its second flange directly with the cylinder of the cylinder-piston assembly. And the suction valve can be connected via a control line with a control output provided on the flange and connection block. The control output of the flange and connection block is connected via a channel with a control fluid interface to the first flange in connection.

It will be appreciated from the foregoing discussion that in application of the present invention, an electro-hydraulic drive unit having distinct advantages (particularly in the case of use as a machine press drive) can be provided. These include in particular: By factory pre-assembled and tested units, which are equipped with a mechanical interface to the respective cylinder-piston assembly and thus easy to connect to the latter, there are minimal assembly and commissioning times on the machine. The piping-reduced design and the consistent avoidance of external piping result in the greatest possible reliability and the reduction of the risk of external leaks. The drive unit uses a small amount of hydraulic fluid. It has a low temperature dependence on a very high energy efficiency, so that usually neither a designated oil cooling time is provided, nor an oil cooler is needed. So can the drive unit have particularly small dimensions. The noise is minimal. By means of the valve control a return stroke of the tool is possible at working speed. As a result, particularly short cycle times and a correspondingly high productivity are possible. Additional functions such as tool clamping and crowning can be integrated into the drive unit without any additional effort or connected to it. The drive unit requires no accumulator and no proportional directional control valves. Equally, it is absolutely not necessary to use any pressure sensors, although those may definitely be provided with advantage in certain embodiments of the drive unit according to the invention (see above). A variable displacement pump is not required. It is possible to realize highly dynamic machine presses (eg press brakes) with a rapid traverse speed of, for example, 200-230 mm / sec.

Fig. 1

in perspektivischer Ansicht eine elektrohydraulische Antriebseinheit nach einem ersten Ausführungsbeispiel der Erfindung ohne die zugehörige Maschinensteuerung,

Fig. 2

die elektrohydraulische Antriebseinheit nach Fig. 1 bei teilweise geschnittenen Seitenwänden des Tanks zur Veranschaulichung von dessen Einbauten, allerdings ohne die Zylinder-Kolben-Einheit,

Fig. 3

den Hydraulikschaltplan zu der elektrohydraulischen Antriebseinheit nach den Figuren 1 und 2,

Fig. 4

in Form eines Diagramms die Ansteuerung der Schaltventile und des Elektromotors der elektrohydraulischen Antriebseinheit nach den Figuren 1 bis 3 und die sich ergebende Bewegung des Kolbens,

Fig. 5

in perspektivischer Ansicht eine elektrohydraulische Antriebseinheit nach einem zweiten Ausführungsbeispiel der Erfindung ohne die zugehörige Maschinensteuerung,

Fig. 6

den Hydraulikschaltplan zu der elektrohydraulischen Antriebseinheit nach Fig. 5 (ohne die zugehörige Maschinensteuerung) und

Fig. 7

ein die Ansteuerung der Schaltventile und des Elektromotors der elektrohydraulischen Antriebseinheit nach den Figuren 5 und 6 und die sich ergebende Bewegung des Kolbens veranschaulichendes Funktionsdiagramm.

In the following, the present invention is explained in more detail with reference to two illustrated in the drawing preferred embodiments. It shows

Fig. 1

in a perspective view of an electro-hydraulic drive unit according to a first embodiment of the invention without the associated machine control,

Fig. 2

the electro-hydraulic drive unit after Fig. 1 with partially cut side walls of the tank to illustrate its internals, but without the cylinder-piston unit,

Fig. 3

the hydraulic circuit diagram to the electro-hydraulic drive unit after the FIGS. 1 and 2 .

Fig. 4

in the form of a diagram, the control of the switching valves and the electric motor of the electro-hydraulic drive unit according to the FIGS. 1 to 3 and the resulting movement of the piston,

Fig. 5

a perspective view of an electro-hydraulic drive unit according to a second embodiment of the invention without the associated machine control,

Fig. 6

the hydraulic circuit diagram to the electro-hydraulic drive unit according to Fig. 5 (without the associated machine control) and

Fig. 7

a control of the switching valves and the electric motor of the electro-hydraulic drive unit after the Figures 5 and 6 and the resulting movement of the piston illustrating functional diagram.

The in the FIGS. 1 and 2 shown electrohydraulic drive unit according to a first embodiment of the invention comprises as main components a cylinder-piston assembly 1 with vertical axis of movement Y, a hydraulic fluid-storing tank 2, a hydraulic unit 3 with an electric motor 4 and driven by this hydraulic pump 5 and a valve block 6 with a plurality arranged thereon or housed therein hydraulically active elements (in particular valves) and a change-oil filter 20. The cylinder-piston assembly 1 comprises in known manner such a linear in a cylinder 7 displaceable, with a piston rod 8 connected piston 9, through which the interior of the cylinder 7 is divided into two working spaces, namely a first hydraulic working space 10 which is so associated with a first movement direction Y1 of the piston, that during this increases its volume, and a second hydraulic working space 11, which is associated with a second movement direction Y2 of the piston, which is opposite to the first movement direction Y1, during which it increases its volume. In the existing installation position corresponds to the first direction of movement Y1 of the downward movement of the piston 9 and piston rod 8 and the second direction of movement Y2 their upward movement.

The tank 2, which is ventilated via a ventilation filter 12, so that ambient pressure prevails therein (so-called "open system"), has an L-shape. He thus has a lateral recess 13 in which the valve block 6 is housed. On one of the side walls of the tank 2, a level sensor 34 is arranged.

The hydraulic pump 5 is disposed inside the tank 2 ("under oil"). However, the drive 4 serving electric motor 4 is located outside of the tank 2, flanged to the bottom 14. Also in the tank 2 are a suction valve 15 and (with a major part of its volume) a flange and terminal block 16. However, the latter protrudes through corresponding openings in the side wall 17 and the bottom 14 of the tank 2 out of this. At the protruding through the side wall 17 of the tank portion 18 of the flange and terminal block 16 is a first flange 19 for Connection provided with the valve block 6; and on the protruding through the bottom 14 of the tank 2 portion of the flange and terminal block 16 is a second flange 21 for connection to the cylinder 7 of the cylinder-piston assembly 1. At the first and the second flange 19, 21 is respectively a hydraulic interface is provided, which comprises two with the two working spaces 10, 11 of the cylinder-piston assembly 1 communicating working ports A, B.

The flange and connection block 16 has an opening 22, in which the Nachsaugventil 15 is inserted. This has in turn a connection flange for direct connection with the cylinder 7 of the cylinder-piston assembly 1. The Nachsaugventil 15 is hydraulically unlocked, what it over a - within the tank 2 misplaced - control line 23 with a on the flange and terminal block 16th is provided, which in turn communicates via a - the flange and terminal block 16 passing through - channel and provided on the first flange 19 control fluid interface with a control output of the valve block 6.

At the tank side of the hydraulic pump 5, which forms the suction side in their pumping operation, a near-ground opening intake 24 is provided. In contrast, the pressure side of the hydraulic pump 5, at which the pumped hydraulic fluid exits in its pumping operation, is connected via a pressure hose 25, which is laid inside the tank 2, to a pressure connection provided on the flange and connection block 16. which, in turn, communicates with a pressurized fluid port of the valve block 6 via a channel passing through the flange and port block 16 and a pressure fluid interface provided on the first flange surface 19.

The arrangement and connection of the switching valves and other components (suction valve, throttle, pressure limiting valves, filters, etc.) of the hydraulic circuit is in Fig. 3 illustrated. (To avoid any misunderstanding, it should be noted that in Fig. 3 the valve block 6 symbolizing line the physical valve block 6 FIGS. 1 and 2 including the bodily flange and terminal block 16; these two after the FIGS. 1 and 2 structurally separate components could well be combined into a single component.) In a special way of importance for the control of the motion sequences of the drive unit, ie the downward and upward movement of piston 9 and piston rod 8 are the total of six controlled by the machine control 26 switching valves S1 to S6 as well as the electric motor 4 of the hydraulic unit 3, which is also controlled by the machine control 26 and designed as a servomotor 27. The actuation of the switching valves S1 to S6 and the servomotor 27 in the individual sections and phases of a complete cycle is shown in the diagram Fig. 4 illustrated.

Namely, while in the holding, the piston at the top dead center (phase I), the servomotor 27 at a standstill (operating state "0"); and none of the six switching valves S1 to S6 is activated, so that all switching valves the in Fig. 3 shown position (switch position "0") take. In this switching state, the piston 9 is held redundantly by the group of closed switching valve S2 and closed pressure limiting valve 30 as well as the likewise closed switching valve S3 in the sense that the weight of the components connected to the piston rod 8 (eg tool carrier and tool) the respective machine are held by the hydraulic fluid clamped in the second hydraulic working space 11. (The safety valve 28, which is set to the maximum permissible system pressure plus an additional charge, is always closed in normal operation anyway.)

For the movement Eil-down of piston 9 and piston rod 8 (phase II), all switching valves, ie the switching valves S1, S2, S3, S5 and S6 are activated (switching position "I") with the exception of the switching valve S4. The second working space 11 (lifting-working space) of the cylinder-piston unit 7 is connected to the pressure port 29 of the hydraulic pump 5 via the (opened) switching valves S2 and S3 and the open in accordance with bP switching valve S5. The servomotor 27 rotates counterclockwise (operating state L *), ie in its braking mode, in order to brake the downward movement of the piston 9 induced by the dead weight of the driven machine component driven by the drive unit and connected to the piston rod 8 (tool carrier plus tool). By the suction valve 15, the first working space 10 of the cylinder-piston assembly 7 is filled directly from the tank 2. This Phase II extends to a - stored in the machine control - switching point, the freely programmable and is suitably chosen near the touchdown of the tool on the workpiece.

In the load change phase III, the servomotor 27 is at a standstill. The switching valves S2, S4 and S5 are reversed, d. H. the switching valves S2 and S5 are deactivated (switch position "0"), and the switching valve S4 is activated (switch position "I"). In this way, the first working space 10 of the cylinder-piston arrangement 7 is brought into fluid communication with the pressure side 29 of the hydraulic pump 5 via the switching valve S4. On the other hand, the second working space 11 of the cylinder-piston arrangement 7 is brought into fluid communication with the tank side via the pressure-limiting valve 30, the switching valve S3, the flow path bT of the switching valve S5 and the oil filter 20.

For force pressing (phase IV), the servomotor 27 is set in operation with its direction of rotation corresponding to the pumping operation of the hydraulic pump 5 (clockwise rotation according to the operating state R *). This operating state of the switching valves S1 to S6 and the servomotor 27 is also maintained over the subsequent holding phase (phase V).

For decompressing the hydraulic fluid in the first working chamber 10 (phase VI), the servomotor 27 is reversed. It now rotates counterclockwise, ie in its braking mode L *, so that hydraulic fluid is conveyed from the first working chamber 10 via the switching valve S4 and the throttle 31 (designed as a nozzle) into the tank 2 in a controlled manner.

At the end of the decompression phase, the switching valves S4, S5 and S6 are reversed, d. H. the switching valves S4 and S6 are deactivated (switching state "0") and the switching valve S5 is activated (switching state "I"). As a result of its application of control pressure via the switching valve S6 (path Pb), the suction valve 15 is opened (unlocked). And the second working space 11 of the cylinder-piston arrangement 7 is connected to the pressure side 29 of the hydraulic pump 5 via the admission pressure valve 32 and the two switching valves S3 and S2 (in each case through the path protected by the check valve). By reversing the servomotor 27 in clockwise, d. H. Operation with its pumping operation of the hydraulic pump corresponding direction of rotation (operating state R *), the piston 9 is raised in the rapid-stroke (Phase VII). If necessary, the lifting of the piston 9 can be subdivided into two subphases, in which the rapid lifting is first preceded by a slow lifting. During this first partial phase, the hydraulic fluid displaced from the first working space 10 can flow into the tank 2 via the switching valve S4 (path aT) and the oil filter 20, with the suction valve 15 not yet unlocked.

Upon reaching the top dead center (TDC), the servomotor 27 goes to standstill; and the switching valves S1 and S5 are reversed, so that now again all switching valves are deactivated (holding phase VIII, analogous to the holding phase I at the beginning of the cycle ', see above).

In the holding phase I, VIII, the hydraulic pump 5 can, if necessary, be put into operation to hydraulic fluid via the (open) switching valve S1 through the oil filter 20 to promote. Optionally, an oil cooler 33 can be connected to the oil filter 20, connected in series therewith.

To the in the Figures 3 and 4 For the sake of completeness, in the context of the present invention, various variations, modifications and variations are apparent, without departing from the invention as defined by the claims. One such modification is, for example, the replacement of normally-open (NO) valves with normally-closed (NG) valves and / or vice versa.

In Fig. 3 is illustrated that the switching valves S1, S2, S3, S4 and S6 are equipped with a switch position monitoring 34. In the case of lower safety requirements, this can possibly be dispensed with, in which case the switching valve S3 can also be omitted.

Is, as mentioned above and in Fig. 3 illustrated, an optional oil cooler 33 is provided, this is preferably arranged directly outside on one of the side walls of the tank 2. The oil supply to the oil cooler 33 takes place via a - inside the tank 2 laid pipe, which is connected to a provided on the flange and terminal block 16 cooling power connection, which in turn via a - the flange and terminal block 16 passing through - channel and at the the first flange 19 provided cooling flow interface with a cooling flow connection of the valve block 6 communicates.

That by the FIGS. 5 to 7 documented second preferred embodiment of the invention is explained - due to the existing parallels - to a considerable extent by the above explanations to that of the FIGS. 1 to 4 affected first embodiment. To avoid repetition, reference is made to the latter. However, special attention should be drawn to the relevant deviations discussed below as follows:
The flange and port block 16 'is not located in the tank, but rather (completely) outside the tank 2'. It is located below the tank 2 ', ie below its bottom 14. Unlike in the first embodiment, in which a self-functional suction valve is inserted into a recess or an opening of the flange and connection block is in the second embodiment after the Figures 5-7 the Nachsaugventil 15 'in the sense in the flange and terminal block 16' integrated, as the latter itself forms the functionally necessary valve housing. This allows a particularly compact design. Furthermore, eliminates the required according to the first embodiment double flange connection (on the one hand of the flange and terminal block 16 and on the other hand of the Nachsaugventils 15) of components to the cylinder-piston assembly.

Furthermore, in Fig. 6 recognizable that in the first embodiment in the decompression phase effective, with the hydraulic pump functionally connected in series throttle is omitted. This is related to the (in the second embodiment provided) pressure-dependent control of the decompression by appropriate control of the hydraulic pump 5 in braking operation by the controller, for which purpose the signal of a hydraulic pressure in the first hydraulic working chamber detecting pressure sensor 34 is connected to the controller.

In the second embodiment, the filtering of the hydraulic fluid is designed differently. Here, a filter unit 35 is provided such that in the pumping operation of the hydraulic pump 5, the entire hydraulic fluid delivered by the latter is cleaned by the filter 20 '. Only when the filter 20 'is obstructed does the hydraulic fluid delivered by the hydraulic pump 5' flow via the "small" bypass 36, in which the check valve 37 acts as a pressure relief valve and opens when the filter 20 'is laden or clogged, in order to prevent filter breakage. During braking operation of the hydraulic pump 5 ', the hydraulic fluid flows past the filter unit 35 via the "large" bypass 38.

As a result of the above-described embodiment of the filtering of the hydraulic fluid, the function of the switching valve S1 provided in the first exemplary embodiment is also partially eliminated; because there is no pure circulation filter operation in the second embodiment. Thus, the second embodiment with a switching valve could make do less than the first embodiment. However, that's how Fig. 6 shows, for safety reasons, a shut-off valve S7 added. This locks in his non-energized Position the hydraulic pump 5 from the other valve assembly and prevents in this way an unintentional pressure build-up in the system.

Attention should finally be drawn to the omission of a separate oil cooler; because such is not required in the illustrated second embodiment.

Claims (16)

1. Electrohydraulic drive unit, in particular for use on a machine press, comprising

   - a cylinder-piston arrangement (1) having a first hydraulic working chamber (10) assigned to a first direction of movement (Y1) of the piston (9) and a second hydraulic working chamber (11) assigned to an opposite second direction of movement (Y2) of the piston (9),

   - a tank storing hydraulic fluid (2; 2'),

   - a 2-quadrant hydraulic pump (5) which is driven by means of an electric motor (4) in pumping operation in exactly one predetermined direction of rotation in variable rotational speed and which has a tank connection opening directly into the tank (2; 2') and a pressure connection (29),

   - a valve arrangement which is connected between the pressure connection (29) of the hydraulic pump (5) and the cylinder-piston arrangement (1) and which comprises a plurality of electrically controllable switching valves (S1- S6; S2' -S6', S7),

   - and a machine controller (26) which acts on the switching valves (S1 - S6; S2' - S6' ,S7) and the electric motor (4) and by means of which the switching valves (S1 - S6; S2' - S6', S7) are switchable between a loading of the first hydraulic working chamber (10) and the second hydraulic working chamber (11) of the cylinder-piston arrangement (1) during the pumping operation of the hydraulic pump (5) from the pressure connection (29),

   wherein the hydraulic pump (5) is switchable by means of the machine controller (26) into a braking operation with the direction of rotation and flow reverse to the pump operation.
2. Electrohydraulic drive unit according to claim 1, characterized in that the cylinder-piston arrangement (1) is oriented with an at least substantially perpendicular axis of movement (Y), the first direction of movement (Y1) corresponding to a downward movement and the second direction of movement (Y2) corresponding to an upward movement of the piston (9).
3. Electrohydraulic drive unit according to claim 1 or claim 2, characterized in that the hydraulic pump (5) can be switched over into braking operation both in a first movement phase, while a flow connection of the second hydraulic working chamber (11) of the cylinder-piston arrangement (1) with the pressure connection (29) of the hydraulic pump (5) exists, and in a second movement phase, in which a flow connection of the first hydraulic working chamber (10) of the cylinder-piston arrangement (1) with the pressure connection (29) of the hydraulic pump (5) exists, into braking operation.
4. Electrohydraulic drive unit according to claim 3, characterized in that a throttle (31) is provided which, in braking operation, is connected in series with the hydraulic pump (5) in the second movement phase.
5. Electrohydraulic drive unit according to one of claims 1 to 4, characterized in that the hydraulic pump (5) is disposed on the inside in the tank (2; 2').
6. Electrohydraulic drive unit according to one of claims 1 to 5, characterized in that a flange and connection block (16) is provided with a first flange surface (19) for connection to a valve block (6) accommodating the switching valves (S1 - S6; S2' - S6', S7) and a second flange surface (21) for connection to the cylinder (7) of the cylinder-piston arrangement (1).
7. Electrohydraulic drive unit according to claim 6, characterized in that the flange and connection block (16) is arranged in the tank (2) to a predominant part of its volume.
8. Electrohydraulic drive unit according to claim 6 or claim 7, characterized in that the valve block (6) is disposed in a lateral recess (13) of the tank (2; 2').
9. Electrohydraulic drive unit according to one of claims 6 to 8, characterized in that a hydraulic interface is provided on the second flange face (21), which comprises two working connections (A, B) communicating with the two working chambers (10, 11) of the cylinder-piston arrangement (1).
10. Electrohydraulic drive unit according to one of claims 6 to 9, characterized in that the hydraulic pump (5) is connected to the flange and connection block (16) via a pressure line (25) running inside the tank (2).
11. Electrohydraulic drive unit according to one of claims 1 to 10, characterized in that a suction valve (15) with a hydraulically unlockable non-return valve is arranged in the tank (2).
12. Electrohydraulic drive unit according to claim 11, characterized in that the suction valve (15) has a connecting flange for direct connection to the cylinder (7) of the cylinder-piston arrangement (1).
13. Electrohydraulic drive unit according to claim 11 or claim 12, characterized in that the suction valve (15) is connected via a control line (23) to a control output provided on the flange and connection block (16).
14. Electrohydraulic drive unit according to claim 6, characterized in that the flange and connection block (16') is arranged below the tank (2').
15. Electrohydraulic drive unit according to claim 14, characterized in that a suction valve (15') with a hydraulically unlockable non-return valve (15') is disposed into the flange and connection block (16').
16. Electrohydraulic drive unit according to one of claims 1 to 15, characterized in that it comprises a filter unit (35) with a filter (20') through which the entire hydraulic fluid conveyed by the hydraulic pump (5) flows during pumping operation of the hydraulic pump (5).

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