ELECTRO-HYDROSTATIC ACTUATOR SYSTEM

Abstract

The electrohydrostatic actuator system according to the invention comprises a volume-variable and/or rotational-speed-variable hydro machine, which is driven by an electric motor, for providing a volume flow of a hydraulic fluid, and a main shaft which is movable by the hydraulic fluid and which has at least one first chamber, wherein the first chamber, with at least one first main hydraulic line and a first main valve, is hydraulically connected to the hydro machine via a connection line. The actuator system according to the invention further comprises a secondary shaft which is movable by the hydraulic fluid and which has at least one first chamber, wherein the first chamber, with at least one first secondary hydraulic line and a first secondary valve, is hydraulically connected to the hydro machine via a connection line. Furthermore, according to the invention, a hydraulic accumulator is hydraulically connected to the first secondary hydraulic line in the area between the first chamber of the secondary shaft and the first secondary valve.

Claims

1. An electrohydrostatic actuator system having at least two movable shafts, comprising: a volume-variable and/or rotational-speed-variable hydro machine, which is driven by an electric motor and comprises two connections, with two connection lines for providing a volume flow of a hydraulic fluid; a main shaft which is movable by the hydraulic fluid and which has at least one first chamber, wherein the first chamber, with at least one first main hydraulic line and a first main valve, is hydraulically connected to a first connection of the hydro machine via a first connection line; a secondary shaft which is movable by the hydraulic fluid and which has at least one first chamber, wherein the first chamber, with at least one first secondary hydraulic line and a first secondary valve, is hydraulically connected to the first connection of the hydro machine via the first connection line or to a second connection of the hydro machine via a second connection line; a hydraulic accumulator hydraulically connected to the first secondary hydraulic line in an the area between the first chamber of the secondary shaft and the first secondary valve; and the main shaft having at least one second chamber, wherein the second chamber, with at least one second main hydraulic line and a second main valve, is hydraulically connected to the second connection of the hydro machine via the second connection line.

2. The electrohydrostatic actuator system according to claim 1, wherein the hydraulic fluid is preloaded in the connection lines.

3. The electrohydrostatic actuator system according to claim 1, comprising another hydraulic accumulator hydraulically connected to the first main hydraulic line in an area between the first chamber of the main shaft and the first main valve.

4. The electrohydrostatic actuator system according to claim 1, wherein the first secondary hydraulic line and/or the first main hydraulic line are hydraulically connected to a drain line and a safety valve and/or a 2-way valve.

5. The electrohydrostatic actuator system according to claim 1, wherein the first chamber of the main shaft and the first chamber of the secondary shaft are hydraulically connected to the same connection line of the hydro machine.

6. The electrohydrostatic actuator system according to claim 1, wherein the first main valve and/or the first secondary valve are controlled valves.

7. The electrohydrostatic actuator system according to claim 1, wherein the main shaft and/or the secondary shaft is preloaded mechanically.

8. (canceled)

9. The electrohydrostatic actuator system according to claim 1, wherein the secondary shaft has at least one second chamber, wherein the second chamber, with at least one second secondary hydraulic line and a second secondary valve, is hydraulically connected to the hydro machine via a connection line.

10. The electrohydrostatic actuator system according to claim 9, wherein the second chamber of the main shaft and the second chamber of the secondary shaft are hydraulically connected to the same connection line of the hydro machine, wherein the connection line is different from the connection line of the first chamber of the main shaft and the first chamber of the secondary shaft.

11. The electrohydrostatic actuator system according to claim 9, wherein the second main valve and/or the second secondary valve are controlled valves.

12. The electrohydrostatic actuator system according to claim 11, wherein at least one of the controlled valves can be released by means of a control valve.

13. The electrohydrostatic actuator system according to claim 12, wherein at least one of the control valves is hydraulically connected to at least one of the connection lines of the hydro machine by means of non-return valves.

14. The electrohydrostatic actuator system according to claim 1, wherein the main shaft is a reshaping shaft and the secondary shaft is a clamping shaft.

15. A method for operating the electrohydrostatic actuator system according to claim 1, wherein the main shaft and the secondary shaft are operated in parallel or sequentially by the same hydro machine.

16. The method for operating an electrohydrostatic actuator system according to claim 15, wherein the hydraulic fluid in the hydraulic accumulator is loaded when the secondary shaft is clamped.

17. The method for operating an electrohydrostatic actuator system according to claim 15, comprising the step of reshaping molded parts or deep-drawing molded parts.

18. The electrohydrostatic actuator system according to claim 4, wherein the safety valve and/or the 2-way valve comprises a drain valve.

19. The electrohydrostatic actuator system according to claim 7, wherein the main shaft and/or the secondary shaft is preloaded mechanically with a spring system or a weight system.

Description

[0049] The invention is explained below on the basis of various exemplary embodiments, wherein it is pointed out that these examples encompass modifications or additions as they immediately arise for the person skilled in the art.

[0050] Shown are:

[0051] FIG. 1: a schematic general representation of a system according to the invention;

[0052] FIG. 2: a schematic representation of an exemplary embodiment of the system according to the invention according to FIG. 1;

[0053] FIG. 2: a schematic representation of an exemplary embodiment of the system according to the invention according to FIG. 2;

[0054] FIG. 4: a schematic representation of a further exemplary embodiment of the system according to the invention according to FIG. 1;

[0055] FIG. 5: a schematic representation of a further exemplary embodiment, wherein the secondary shaft is preloaded;

[0056] FIG. 6: a schematic representation of a further exemplary embodiment of the system according to the invention according to FIG. 5;

[0057] FIG. 1 shows a general arrangement of an exemplary embodiment of the actuator system 1 according to the invention with two movable shafts.

[0058] The exemplary embodiment of the actuator system 1 according to the invention has a volume-variable and/or rotational-speed-variable hydro machine 11, which is driven by an electric motor 10, for providing a volume flow of a hydraulic fluid.

[0059] The system 1 further comprises a main shaft 20 which is designed as a differential cylinder with a first chamber 22 and a second chamber 24, wherein the first chamber 22 is hydraulically connected by a first main hydraulic line 52 and by a first connection line 12, and the second chamber 24 is connected by a second main hydraulic line 54 and by a second connection line 14, to a connection of the hydro machine 11 in each case.

[0060] A first and a second main valve 23 and 25 are arranged between the hydro machine and the first and second chambers 22, 24 of the main shaft 20, respectively. These main valves are shown in FIG. 1 as a controlled 2/2-way valve with a flow and a shut position.

[0061] Furthermore, as can be seen in FIG. 1, the exemplary embodiment of the actuator system 1 according to the invention comprises a secondary shaft 30 which also has a first chamber 32 and a second chamber 34, wherein the first chamber 32 is hydraulically connected by a first secondary hydraulic line 62 and by the first connection line 12, and the second chamber 34 is connected by a second secondary hydraulic line 64 and by the second connection line 14, to a connection of the hydro machine 11 in each case.

[0062] In the present exemplary embodiment according to the invention, a valve assembly 90 and a hydraulic accumulator 40 are hydraulically connected to the secondary shaft 30. Some embodiments of how the valve assembly 90 is designed are illustrated in the next figures.

[0063] In general, the arrangement should be such that it is possible to operate both the main shaft 20 and the secondary shaft 30 sequentially and/or in parallel by means of a single hydro machine 11. It is, for example, important that, by means of the valve assembly 90, a hydraulic fluid flow from the first and/or second chambers 32, 34 of the secondary shaft 30 toward or from the hydro machine 11 can be shut off as desired so that the hydro machine 11 acts mainly on the main shaft 20. The valve assembly 90 should further be designed to allow the first and/or second chambers 32, 34 of the secondary shaft 30 to be relieved.

[0064] Furthermore, the system 1 has a source 80 and a preloading source 82, which serve to preload the connection lines 12 and 14 of the hydro machine 11. The hydro machine 11 is furthermore hydraulically connected to a tank 84 from which the hydro machine 11 extracts hydraulic fluid and feeds it into the system.

[0065] In this exemplary embodiment according to the invention, when one of the two first chambers 22 or 32 of the primary or secondary shaft 20, 30 is relieved, the hydraulic fluid flows into the preloading source 82 or the tank 84. This can be done, for example, by means of the hydro machine 11 and/or, as shown in FIG. 1, by an additional line 98a which is connected to the tank 84 or the preloading source 82 by a releasable valve 92, in this case a releasable non-return valve.

[0066] A further line 98b with a further releasable valve 94 serves both for hydraulically connecting the source 80 and the preloading source 82 to the hydro machine 11 and for relieving the second chamber 24, 34 of the main and/or secondary shaft 20, 30.

[0067] Alternatively or additionally, a drain line 42 may be hydraulically connected to the tank 84 and to a releasable valve 43 at the connection of the hydraulic accumulator. According to further exemplary embodiments according to the invention, the hydraulic accumulator 40 may be relieved by means of the additional line 42 and the releasable valve 43.

[0068] FIG. 2 shows an exemplary embodiment of the system according to the invention from FIG. 1. The general structure of the system 1 is unchanged.

[0069] The arrangement of the valves on the secondary shaft 30 is different. In particular, as can be seen in FIG. 2, the secondary shaft 30 is shown as a differential cylinder, wherein the arrangement of a synchronous cylinder is also conceivable. The secondary shaft 30 has a first chamber 32 and a hydraulic accumulator 40, which is connected to the first chamber 32 by the first secondary hydraulic line 62, and a second chamber 34.

[0070] The valve assembly 90 comprises a secondary valve 33, wherein the first chamber 32 and the second chamber 34 of the secondary shaft are hydraulically connected by the common secondary valve 33 to the hydro machine by the first secondary hydraulic line 62 or the second secondary hydraulic line 64.

[0071] In the exemplary embodiment according to the invention of FIG. 2, the first secondary valve 33 is a 4/2-way valve 33 having a flow position and a shut position so that both the first secondary hydraulic line 62 and the second secondary hydraulic lines 64 are either open at the same time or shut off simultaneously. In the first case, the hydro machine 11 can operate directly in the two chambers 32, 34 of the secondary shaft 30 and in the hydraulic accumulator 40. For example, the hydro machine 11 may provide a hydraulic fluid flow into the first chamber 32 of the secondary shaft 30 and into the hydraulic accumulator 40 so that the secondary shaft 30 is loaded as hydraulic fluid is withdrawn from the second chamber 34.

[0072] In the second case, that is to say when the secondary valve 33 is brought into the shut position, the hydraulic connection of the secondary shaft 30 to the hydro machine 11 is interrupted by the valve 33, wherein the secondary shaft 30 remains in a loaded state by the hydraulic accumulator 40. The hydro machine 11 can accordingly act in this case in the primary shaft 20 while the secondary shaft remains in a loaded state.

[0073] If relieving the first and/or second chambers of the secondary shaft 30 is intended, the secondary valve 33 can be adjusted to flow and the valves 92 and/or 94 are released so that hydraulic fluid can flow into the preloading source 82.

[0074] As in the exemplary embodiment of FIG. 1, the hydraulic accumulator 40 can be directly relieved into the tank 84 by means of a valve 43 and a drain line 42.

[0075] FIG. 3 shows a similar exemplary embodiment according to the invention of the actuator system as FIG. 2, wherein the valve assembly 90 comprises, instead of a single secondary valve, a first secondary valve 33 arranged in the first secondary hydraulic line 62 and a second secondary valve 35 arranged in the second secondary hydraulic line 64.

[0076] In this exemplary embodiment according to the invention, both the first and second secondary valves 33, 35 are controlled 2/2-way valves, each having a flow and a shut position. Thus, the loading and relieving of the first and/or second chambers 32, 34 of the secondary shaft can be controlled individually.

[0077] FIG. 4 shows an exemplary alternative embodiment of the system 1 according to the invention in accordance with one of the previous figures.

[0078] In this exemplary embodiment according to the invention of the actuator system 1, the valve assembly 90 comprises a 4/3-way valve 33 which has a flow, cross-flow and shut position and which is arranged in both the first secondary hydraulic line 62 and the second secondary hydraulic line 64, and a 2/2-way valve 35 which has a flow and shut position and which is arranged in a line connecting the hydraulic accumulator 40 and the secondary shaft 30 to the connection line 12.

[0079] In particular, a drain line 94 is connected to the 4/3-way valve 33 so that, in the respective flow positions, either the first chamber 32 or the second chamber 34 of the secondary shaft 30 is connected to the drain line 94. Furthermore, the drain line 94 is hydraulically connected to the tank 84 so that when the hydraulic fluid from one of the two chambers 32, 34 is relieved, it can flow directly into the tank 84.

[0080] The second secondary valve 35 blocks the connection of the secondary shaft 30 and the hydraulic accumulator 40 to the connection line 12 and accordingly to the rest of the system 1.

[0081] The hydraulic accumulator 40 can be relieved, for example, by means of the second secondary valve 35, through the line 12, 98a and by releasing the valve 92 or, as shown in the previous figures, through an alternative line 42.

[0082] As shown in FIG. 5, according to a further exemplary embodiment, the secondary shaft 30 may also be a preloaded cylinder instead of a differential cylinder.

[0083] The cylinder can be preloaded by means of a spring or also by means of a weight system, wherein the cylinder has at least one venting device in its preloaded chamber 34 so that the air can escape during the pressing process.

[0084] In this exemplary embodiment according to the invention, the valve assembly 90 comprises a 2-way valve 33 with a flow and a shut position; in this case, the first chamber 32 of the secondary shaft 30 is hydraulically connected to the connection line 12 and to the hydro machine 11 through the first hydraulic line 62 and the secondary valve 33, respectively.

[0085] Furthermore, the pressure accumulator 40 is also hydraulically connected both to the secondary hydraulic line 62 and to the secondary valve 33. For example, in order to relieve the first chamber 32 and the hydraulic accumulator 40, the secondary valve 33 and the controlled valve 92 may be released so that the relieved hydraulic fluid flows into the preloading source 82. Alternatively, in this exemplary embodiment according to the invention, the hydraulic accumulator 40 may also be hydraulically connected by a drain line 42 to a drain valve 43 in the tank 84. In this embodiment, however, it is only possible to relieve the first chamber 32 at the same time as the hydraulic accumulator 40.

[0086] In the exemplary embodiment according to the invention shown in FIG. 6 by contrast, the first chamber 32 of the secondary shaft 30 and the hydraulic accumulator 40 can each be relieved individually or together by means of the selected valve assembly 90.

[0087] In this case, the valve assembly 90 comprises a 3-way valve connected to the secondary hydraulic line, with a flow, a cross-flow and a shut position. Furthermore, the valve assembly comprises a second secondary valve 35 which, as in the previous example, is designed as a 2-way valve and connects the connection line 12 to the secondary shaft 30 and/or the hydraulic accumulator 40.

[0088] When the second secondary valve 35 is shut and the first secondary valve 33 is switched to the cross-flow position, a connection between the first chamber of the secondary shaft and the tank 84 is established by means of a line 94. In this case as well, the hydraulic accumulator 40 can be hydraulically connected to the tank 84 by a drain line 42 having a drain valve 43; thus, by shutting the first secondary valve 33 and opening the drain valve 43, just the relieving of the hydraulic accumulator 40 can be achieved.

TABLE-US-00001 List of reference signs 1 Actuator system 10 Electric motor 11 Hydro machine 12 First connection line 14 Second connection line 20 Main shaft 22 First chamber of the main shaft 23 First main valve 24 Second chamber of the main shaft 25 Second main valve 30 Secondary shaft 32 First chamber of the secondary shaft 33 First secondary valve 34 Second chamber of the secondary shaft 35 Second secondary valve 40 Hydraulic accumulator 42 Drain line 43 2-way drain valve 52 First main hydraulic line 54 Second main hydraulic line 62 First secondary hydraulic line 64 Second secondary hydraulic line 80 Source 82 Preloading source 84 Tank 90 Valve assembly 94 Drain line 98a, 98b Drain lines