Electro-hydrostatic actuator device with ventilation

Abstract

The present invention comprises an electro-hydrostatic actuator device (1) with a bidirectional pump (2) for transporting a fluid, connected to a movable actuator (3) via supply (4, 5; 8, 9) and return (5) lines. This device comprises two supply lines (4, 5), which conduct the fluid to the chambers (3A, 3B) of the actuator (3), and two return lines (8, 9), which conduct the fluid back to the pump (2). Non-return valves (6, 7, 10) in the supply and return lines prevent unwanted return of the fluid. A two-way valve (17) controls, depending on the pumping direction, the fluid connection between the chambers of the actuator (3) and a common return line section (16). Furthermore, a gas-fluid separator (18) is integrated, in order to separate the gas from the fluid.This configuration optimizes the control and efficiency of the actuator (3) by enabling precise movements and protecting the system from malfunctions. Figure 2.

Description

Title of the invention: Electro-hydrostatic actuator device with ventilation

[0001] The present invention relates to an electrohydrostatic actuator device with ventilation as well as to an aircraft with such an electrohydrostatic actuator device.

[0002] An electrohydrostatic actuator (EHA) is an advanced device that combines the strength and reliability of hydraulic systems with the precision and efficiency of electric drives. The heart of the electrohydrostatic actuator is an electric motor that typically drives a hydraulic pump. This pump pressurizes a fluid, normally a hydraulic liquid, which is then conducted to an actuator cylinder. In the cylinder, the pressurized liquid causes a piston to move, which performs the mechanical movement—either linear or rotary. A decisive aspect of the electrohydrostatic actuator is its ability to provide precise control and regulation. This capability allows for precise positioning as well as very good speed and force control.

[0003] Another advantage of the electro-hydrostatic actuator is its compactness and its design as a closed system, which makes it unlikely to leak and produces a lower environmental impact. These properties make the electro-hydrostatic actuator particularly suitable for applications in which high force and precise control are simultaneously required, such as in the aerospace field, the automotive industry and robotics.

[0004] The disadvantage of the electro-hydrostatic actuator devices known from the state of the art is that these can only be ventilated with considerable effort. More particularly, in an aircraft, more particularly an airplane, this can require particularly long downtimes, which cause enormous costs.

[0005] Thus, for ventilation, it is necessary to provide a place in the system at which air or gas can also accumulate. In electro-hydrostatic actuator devices in which the direction of rotation of the pump also determines the direction of actuation of the actuator, the high pressure side and the suction side of the pump alternate depending on the direction in which it discharges. The problem is that, on the high pressure side of the device, the air or gas dissolves in the fluid and ventilation is not possible.

[0006] In the prior art, this problem is solved by replacing the entire electro-hydrostatic actuator device so as to avoid long downtime of an aircraft or the like. The newly installed electro-hydrostatic actuator device is ventilated upon leaving the factory so that the entire exchange of the actuator device no longer requires the ventilating process.

[0007] Ventilation is generally carried out using a vacuum maintained for several hours on the actuator device. It is therefore clear here that this procedure is not relevant during the shortest possible interruption of the operation of an aircraft equipped with the actuator device.

[0008] The aim of the present invention is therefore to provide an electro-hydrostatic actuator device whose ventilation can be carried out more quickly and by which maintenance work is therefore shorter. With the actuator device according to the present invention, it is possible to enable the ventilation of an electro-hydrostatic actuator device on site with simple means. This is more particularly advantageous when using the actuator device according to the present invention in an aircraft, more particularly an airplane, since it is then no longer necessary, during a repair of the actuator device, to replace the entire actuator device with a recently ventilated actuator device.

[0009] The present invention therefore provides an electro-hydrostatic actuator device which comprises a bidirectional pump for dispensing a fluid via a first connection and for sucking a fluid via a second connection or vice versa, an actuator performing a reciprocating movement, which is connected with the two connections of the bidirectional pump, a first supply line for introducing a fluid from the first connection of the bidirectional pump to a first chamber of the actuator, a second supply line for introducing a fluid from the second connection of the bidirectional pump to a second chamber of the actuator, a first valve in the first supply line, in order to prevent a return of a fluid from the first chamber of the actuator to the first connection, a second valve in the second supply line,in order to prevent a return of a fluid from the second chamber of the actuator to the second connection of the pump via the second supply line, a first return line for the return of a fluid from the first chamber of the actuator to the first connection of the bidirectional pump, a second return line for the return of a fluid from the second chamber of the actuator to the second connection of the bidirectional pump, a third valve in the first return line, in order to prevent a flow of a fluid from the bidirectional pump to the actuator, via the first return line, a fourth valve in the second return line, in order to prevent a flow of a fluid from the bidirectional pump to the actuator via the second return line, a common return line portion, which branches off into the first return line and the second return line, a two-way valve which is switched depending on the discharge direction of the bidirectional pump, in order to fluidically connect the common return line portion either with the first chamber of the actuator or with the second chamber of the actuator and a gas-fluid separator which is arranged in the common return line portion. The first, second, third and / or fourth valves may each be a non-return valve.Alternatively, the valves can also be designed as automatic switching valves or other valves, which conduct fluid flows.

[0010] According to the present invention, a two-way valve ensures that, regardless of the direction of rotation of the two-way pump, a return flow of the hydraulic fluid from the actuator is conducted via a common return line portion. This means that, regardless of the direction in which the actuator is actuated, the two-way valve ensures that the connection (or chamber) of the actuator from which the hydraulic fluid flows out due to the movement of the actuator is connected with the common return line portion via the two-way valve and is conducted to the connection of the pump serving as the suction side.

[0011] According to the present invention, it is also provided that the electro-hydrostatic actuator device comprises a two-way valve which is switched depending on the discharge direction of the bidirectional pump, in order to join the first return line and the second return line at certain locations in order to obtain a common return line portion.

[0012] The advantage is that a segment is formed in the actuator device, in which all the fluid that is led to the suction line of the pump flows exclusively in one direction. Since this segment, due to the non-return valves arranged in the return lines, can never be pressurized, it is also not possible for all the air or gas bubbles to dissolve in the fluid. This ensures that all the air or gas bubbles that are in the actuator device, during normal actuation, pass through this segment, so as to reach the gas-fluid separator located there, accumulate there and can be removed from the circuit. The gas-fluid separator can be used for accumulation of the air, whereby targeted removal of the air is also possible using the separator. gas-air. The removal of air or gas that accumulates there can be carried out automatically.

[0013] The gas-fluid separator can be designed to allow the accumulation of a quantity of air or gas, so that it no longer has any negative influence on the performance of the actuator device. The gas separated in the gas-fluid separator then generally accumulates in an upper position of the separator, on the other hand an outlet connection for the outlet of a fluid from the gas-fluid separator is arranged in a lower portion, so that the gas accumulated in the upper region does not leave the gas-fluid separator via the outlet connection and is discharged to the suction side of the pump.

[0014] According to another development of the invention, it can be provided that the direction of rotation of the pump also determines the direction of movement of the actuator or actuators.

[0015] According to a further optional modification of the present invention, it may be provided that the actuator device further comprises a fluid filter which is arranged in the common return line portion.

[0016] In electrohydrostatic actuator devices of the prior art, in which reversing the pumping direction also causes a reversal of the actuator movement direction, filtering of the fluid flowing in the actuator device (usually hydraulic oil or the like) is only possible to a limited extent. The reason is that in electrohydrostatic actuator devices, the direction of rotation also determines the actuator movement direction. For this reason, a filter is usually not arranged in either of the two connecting lines from the bidirectional pump to the actuator, since, depending on the desired actuator movement direction, the hydraulic fluid flows in opposite directions.For effective filtering through a filter, however, it is necessary that the hydraulic fluid continuously flows towards the filter in one direction, otherwise the particles filtered by the filter are not retained, but are carried away from the filter in an opposite flow direction. In this advantageous design, it is ensured that a filter is arranged at a location allowing the hydraulic fluid to flow exclusively in one direction so that a filter can fully fulfill its function.

[0017] The arrangement of the fluid filter in the common return line portion is particularly effective, since all fluid flowing to a suction side of the bidirectional pump passes through it. For filtering, it is therefore no longer necessary to arrange a filter in a leak line evacuating internal leaks from the pump, as is customary according to the prior art.

[0018] It may preferably be provided that a return flow of a fluid from the actuator via the two-way valve, a common return line portion and the third or fourth non-return valve arranged in the return line flows to the connection serving as the suction side of the two-way pump.

[0019] According to a further development, it may be provided that the gas-fluid separator comprises a ventilation valve in order to evacuate the gas, more particularly the air, accumulated in the gas-fluid separator, preferably the ventilation valve is arranged, in the gas-fluid separator, at the location where gas or air accumulates during normal orientation of the actuator device. This is usually the case in the upper half, preferably the upper third and more particularly preferably in the upper quarter of the gas-fluid separator.

[0020] The ventilation valve allows air accumulated in the actuator device to be removed, this advantageously being able to be carried out automatically.

[0021] According to a further optional development of the present invention, it may be provided that the gas-fluid separator has, in addition to a supply connection for introducing a fluid flowing into the actuator device and a discharge connection for discharging the fluid from the gas-fluid separator, a connection for introducing a fluid from an external source, preferably the connection for introducing a fluid from an external source being designed to introduce a fluid into the gas-fluid separator in a first flow direction which is generally oriented towards the discharge connection.

[0022] During normal operation of the actuator device, a fluid is introduced into the gas-fluid separator via the supply connection, so that the removal of a gas can be carried out there. The discharge connection of the gas-fluid separator then leads the fluid accumulated in the gas-fluid separator to the connection of the pump serving as the suction side, so that the fluid circuit remains closed. In addition, there is also a connection for introducing a fluid from an external source, which is advantageously designed such that a fluid introduced via this connection has a flow direction which is generally oriented towards the discharge connection.Thus, when introducing a fluid from an external source, it is ensured that this fluid from outside is preferably housed in the circuit of the actuator device, this not being the case for the fluid introduced into the gas-fluid separator via the supply connection.

[0023] According to a further advantageous modification of the present invention, it may be provided that the supply connection is designed to introduce a fluid into the gas-fluid separator in a second flow direction which is oriented generally towards the ventilation valve, preferably the first flow direction and the second flow direction forming an angle between them and preferably being arranged orthogonally between them.

[0024] The orientation of the flow directions of the fluid introduced from the outside and of the fluid flowing from the two-way valve, via the supply connection, to the gas-fluid separator is therefore advantageous, since, upon opening of the ventilation valve and simultaneous introduction of an external fluid, an exchange of the fluid circulating in the actuator device can be carried out and the fluid previously circulating in the actuator device can be replaced by newly introduced fluid.

[0025] It is particularly advantageous if the first flow direction is orthogonal to the second flow direction, since then the probability of fluid from the outside flowing directly to the ventilation valve or fluid from the two-way valve flowing directly to the discharge connection is extremely low or even negligible.

[0026] According to an advantageous implementation of the present invention, it can be provided that the electro-hydrostatic actuator device further comprises a fluid reservoir for providing fluid at a suction side of the bidirectional pump, preferably the fluid reservoir being arranged in the return line upstream of the third or fourth non-return valve, which are arranged in the first or second return line.

[0027] The fluid reservoir enables the balancing of the fluid quantities that may occur during operation of the actuator device. The fluid reservoir is then arranged in the actuator device so that the latter can introduce fluid into a suction side of the bidirectional pump, so that a sufficient quantity of fluid can always be delivered to the pressure side of the pump.

[0028] Furthermore, it is provided that the two-way valve is designed to connect one of the two connections of the actuator with the common return portion, preferably the connection of the actuator being connected with the common return portion via the two-way valve from which a fluid emerges due to the movement of the actuator. This ensures that the fluid returning from the actuator is conducted, via the common return line portion, to the suction side of the pump.

[0029] Advantageously, it can be provided that the two-way valve has two inlets and one outlet, a respective inlet being connected to a respective connection of the actuator and the outlet being connected to the common return portion.

[0030] It may be provided that the two-way valve is a 3 / 2-way valve or a 3 / 3-way valve.

[0031] According to a development of the present invention, it can be provided that, when designing the two-way valve as a 3 / 2-way valve, a central position is a neutral position, in which the two inlets and the outlet of the valve are not connected to each other. The central position is useful, among other things, when external forces act on the actuator, which can cause fluid to escape from the actuator. In the central position, the lines connected to the actuator are closed so that fluid flow out of the actuator is not possible.

[0032] Furthermore, it can be provided that the two-way valve has a pilot control for switching the two-way valve, which operates depending on the pressure applied to both connections of the two-way pump. This passive control is therefore carried out on the basis of the pressure generated by the two-way pump. The pressure side of the two-way pump also ensures a movement of the two-way valve to a corresponding position, so that the fluid expelled from the actuator flows to the common return line portion. This design is particularly simple and robust and is therefore particularly suitable for use under difficult conditions.

[0033] According to a further optional development of the present invention, it can be provided that the two-way valve has an electrical control for switching the two-way valve, which operates depending on the pressure applied at the two connections of the two-way pump or the direction of rotation of the two-way pump, preferably, for determining the pressure at two connections of the two-way pump, at least one pressure sensor being provided for determining the pressure at one of the two connections, which is connected with the electronic control, or a direction of rotation sensor for detecting the direction of rotation of the two-way pump.

[0034] This active control for switching the two-way valve is based on a pressure measurement of at least one of the two connections of the two-way pump. If a pressure sensor detects that a first connection of the pump acts as a pressure side, an electrical control device causes the two-way valve to move to the corresponding position. It is naturally advantageous here if the two-way valve is an electromagnetic valve, because then the change in position of the valve can be carried out using electrical signals.

[0035] Furthermore, according to an advantageous modification of the present invention, it can be provided that the bidirectional pump is a motor pump which has an electric motor.

[0036] According to an advantageous modification of the present invention, it may be provided that the actuator is a double-acting cylinder. When the actuator is moved in one direction, this causes a first chamber of the double-acting cylinder to be narrowed and a second chamber of the double-acting cylinder to be enlarged. This is achieved by introducing a high-pressure fluid into the enlarging chamber and by causing a fluid to exit the narrowing chamber.

[0037] The invention further relates to an aircraft, more particularly an airplane with an actuator device according to one of the aspects discussed above.

[0038] Other characteristics, details and advantages of the invention will be visible with the aid of the description of the figures which show: [Fig.lA]: a schematic representation of an electrohydrostatic actuator device according to the state of the art, [Fig.lB]: another schematic representation of an electrohydrostatic actuator device according to the state of the art, [Fig.2]: a schematic representation of an electrohydrostatic actuator device according to the invention, [Fig.3]: a schematic representation of an electrohydrostatic actuator device according to the invention according to a second embodiment, [Fig.4]: a schematic representation of an electrohydrostatic actuator device according to the invention according to a third embodiment and [Fig.5A], [Fig.5B], [Fig.5C] and [Fig.5D]: a schematic representation of a gas-fluid separator in different states during fluid exchange.

[0039] Figure 1 represents an electro-hydrostatic actuator device 100 according to the state of the art.

[0040] A bidirectional pump 2 is recognized which is generally driven by an electric motor 19 and which constitutes with it what is called a motor pump. The pump 2 has two connections 2A, 2B, in which, depending on the direction of rotation of the electric motor 19, one of the connections 2A, 2B constitutes the pressure side and the other of the two connections 2A, 2B constitutes the suction side. If the direction of rotation of the electric motor 19 is changed, the pressure side is therefore correspondingly interchanged with the suction side at the connections 2A, 2B of the pump 2. The connections 2A, 2B of the bidirectional pump 2 are connected to an actuator 3 in the form of a double-acting cylinder, in which each of the connections 2A, 2B is fluidically connected to exactly one chamber 3A, 3B of the actuator 3. This ensures that, when a high-pressure fluid is introduced into one of the two chambers 3A, 3B of the actuator 3, this chamber 3A, 3B increases in volume, the other chamber 3A, 3B on the contrary decreases in volume and the fluid therein is expelled. The expelled fluid is conducted to the suction side of the pump 2, from where it is then pumped at the pressure side to the chamber 3A, 3B of the actuator 3 which increases in volume. If the direction of rotation of the electric motor 19 is then changed, the processes described above take place in reverse, so that the fluid is expelled from the chamber 3A, 3B of the actuator 3, the volume of which was previously increased, because, in the other chamber 3A, 3B, the high-pressure fluid is pumped, which causes the chamber 3A, 3B of the actuator 3, the volume of which was previously decreased, to now increase in volume.

[0041] Furthermore, a fluid reservoir 13 is also connected to each of the two connecting lines 4, 5, 8, 9, which allows variations in the amount of fluid to be compensated for and which provides the required fluid via a respective non-return valve 14, 15 on the suction side of the pump 2.

[0042] The connecting lines (which are at the same time the supply lines 4, 5 and the return lines 8, 9) between the actuator 3 and the bidirectional pump 2 are therefore traversed, depending on the direction of rotation of the electric motor 19 or the pumping direction of the pump 2, by the fluid in different directions. This makes the arrangement of a gas-fluid separator impossible in these lines, since a gas or gas or air bubbles located on the high-pressure side dissolve in the fluid under the effect of the high pressure, which makes ventilation impossible.

[0043] The only possibility of ventilating the actuator device according to the state of the art is therefore to stop the machine and carry out a vacuum for several hours. Since this would unacceptably increase the downtimes in the case of use of the actuator device in an aircraft, in the state of the art, the entire actuator device is usually replaced, the new actuator device having been previously ventilated.

[0044] [Fig. 2] shows a further schematic representation of an electro-hydrostatic actuator device 100 according to the state of the art, which shows, in contrast to the representation of the preceding FIG. 1, an actuator two-way valve 28 with which different actuators 3 can be actuated one after the other. In such an implementation, however, it may be necessary, when replacing one of the actuators 3, to vent the fluid circuit in order to be able to guarantee operation after a replacement of the actuator 3. Finally, the implementation can be designed so that, in such a case, the complete replacement of the actuator device as a whole is not possible, so that ventilation must be carried out at the final place of use of the actuator device, more particularly an airplane or similar. According to the state of the art, there is no other option here than to carry out a time-consuming vacuum for ventilation.

[0045] [Fig. 2] shows an actuator device 1 according to the invention with a gas-fluid separator 18. This actuator device also comprises a bidirectional pump 2 which can be driven by an electric motor 19 in different directions of rotation. The two connections 2A, 2B of the pump 2 can therefore serve, depending on the direction of rotation, either as a suction side or as a pressure side. Furthermore, the two pump connections 2A, 2B are connected with the respective connections 3A, 3B of the actuator 3, so that a direction of movement of the actuator 3 can take place depending on an introduction or an evacuation of the fluid by the pump 2.

[0046] Each of the two connections 2A, 2B of the pump 2 is connected, via a supply line 4, 5, with a respective chamber 3A, 3B of the actuator 3. In order to ensure that, in the supply line 4, 5, the fluid flows only in one flow direction, a respective non-return valve 6, 7 is arranged in the respective supply line 4, 5. This ensures that there is only one flow direction in both supply lines, which is directed from the pump connection 3A, 2B towards the actuator 3.

[0047] When the connection 2A, 2B of the pump 2 functions as a suction side, an introduction of fluid via the supply line 4, 5 towards the pump connection 3A, 3B cannot take place, because then the respective non-return valve 6, 7 prevents a flow of fluid in the blocking direction. In such a case, the fluid is conducted via the respective return line 8, 9 of the actuator 3 to a pump connection 2A, 2B of the pump 2 functioning as a suction side. In each of the two line portions serving as a return line 8, 9, a non-return valve 10, 11 is arranged in order to admit therein only a flow of the fluid which flows towards the pump connection 2A, 2B of the pump 2 functioning as a suction side. In the embodiment shown in [Fig.2] of the electrohydrostatic actuator device 1 according to the invention, a respective supply line 4, 5 extends parallel to a corresponding return line 8, 9 and to a common return line portion 16, wherein the non-return valves 10, 11 arranged respectively in the corresponding return line 8, 9 prevent an opposite flow which is directed from the pump connection 2A, 2B towards the actuator 3. .

[0048] The common return line portion 16 is fluidically connected by means of a two-way valve 17 with the chamber 3A, 3B of the actuator 3 from which a fluid flows. The two-way valve 17 must therefore adapt its position position depending on the direction of operation of the bidirectional pump 2, so that the chamber 3A, 3B of the actuator 3 which decreases in volume is always connected to the common return line portion 16. In order to achieve this, a pilot control is provided, which has two control lines 20, 21, which are coupled with a respective connection 2A, 2B of the bidirectional pump 2. The pump connection 2A, 2B, which serves as the pressure side, exerts pressure on the two-way valve 17 via the corresponding control line 20, 21, so that the two-way valve 17 is pushed out of a neutral position into a switching position in which the chamber 3A, 3B of the actuator 3 which decreases in volume is fluidically connected to the common return line portion 16.This ensures that all fluid that is conducted to the suction line of pump 2 is conducted via the common return line portion 16, so that the provision of a gas-fluid separator 18 collects all fluid flow flowing to pump 2.

[0049] The non-return valves 10, 11 thus ensure that, both in the supply line 4, 5 and in the return line 8, 9 and the common return line portion 16, the fluid circulating in the actuator device 1 flows only in exactly one flow direction and that a reversal of the flow direction does not occur. It is thus possible to arrange, in the common return line portion 16, a gas-fluid separator 18, since no reversal of the flow direction takes place there, which would cause dissolution of the gas or gas bubbles in the fluid due to the existence of high pressure.

[0050] The common return line portion 16 branches downstream of an arrangement position of a gas-fluid separator 18 into two lines 8, 9, of which a first return line 8 is connected to the first pump connection 2A and the second return line 9 is connected to the second pump connection 2B of the pump 2. In each of the two lines 8, 9, a non-return valve 10, 11 is arranged which ensures that the fluid can only exit from the common return line portion 16 and that the fluid does not flow from the pump connection 2A, 2B directly via the return lines 8, 9 to the common return line portion 16. This ensures that the fluid exiting via the common return line portion 16 is delivered to the pump connection 2A, 2B of the pump 2 which operates as a suction pump connection.When the direction of rotation of pump 2 changes, the line 8, 9 through which the fluid returns also changes.

[0051] In the embodiment shown in [Fig. 2], the gas-fluid separator 18 is arranged in the common return pipe portion 16, the fact of providing a gas-fluid separator 18 also in one of the two return pipes 8, 9 is provided in the idea of the invention. The isolated arrangement of a gas-fluid separator in only one of the two return lines 8, 9 would certainly have a disadvantage because the flow rate of the fluid is a little lower, nevertheless the advantages that can be obtained with the invention could also be obtained.

[0052] The two-way valve 17 can be a 3 / 2-way valve or a 3 / 3-way valve which, in its different switching positions, places one of the two inlets on the single outlet. The central position of the 3 / 3-way valve is a neutral position and closes all inlets and outlets so that the displacement position of the actuator 3 is maintained even without the pump 2 exerting a force, because the fluid cannot escape from either of the two chambers 3A, 3B of the actuator 3. Finally, each of the two supply lines 4, 5 is equipped with a corresponding non-return valve 6, 7, so that an exit of the fluid from one of the two chambers 3A, 3B of the actuator 3 is not possible. However, an outlet of the fluid from the chambers 3A, 3B of the actuator 3 is also not possible via the two-way valve 17, because in its neutral position the latter closes the two connections to the chambers 3A, 3B of the actuator 3.Maintaining the position of the actuator 3 is therefore possible in a simple manner and also relieves the pump connections 2A, 2B, on which the force transmitted by the fluid normally acts thanks to the maintenance of the actuator 3.

[0053] [Fig. 3] shows another embodiment of an electro-hydrostatic actuator device 1 in which, unlike [Fig. 3], the two-way valve 17 is not switched using a pilot control 20, 21, but by means of an electronic control unit 22. The two-way valve 17 is designed as a solenoid valve and can therefore adopt its different switching positions on the basis of a control signal from the electronic control unit 22. An electromagnet is either energized or de-energized, so that the two-way valve 17 can be moved into a desired position on the basis of the generated magnetic force.In order to ensure that the correct chamber 3A, 3B of the actuator 3 is connected with the common return line portion 16, the electronic control unit 22 detects either the direction of rotation of the electric motor 19 and / or determines a pressure at at least one of the two pump connections 2A, 2B of the bidirectional pump 2.

[0054] Depending on the information thus obtained, the two-way valve 17 is then moved into the corresponding switching position, so that the chamber 3A, 3B of the actuator 3 fluidically connected to the common return line portion 16 is the one from which the fluid is to be discharged. If the direction of rotation of the electric motor 19 changes and thus the direction of movement of the actuator 3 changes, the switching position of the two-way valve 17 also changes.

[0055] In an unpowered state of the two-way valve 17 designed as a solenoid valve, the 3 / 3-way valve again adopts a neutral position, in which both inlets and only the outlet of the two-way valve 17 are closed. There is therefore no fluid connection between the common return line portion 16 and one of the two chambers 3A, 3B of the actuator 3 via the two-way valve 17.

[0056] [Fig.4] shows another schematic representation of an embodiment of the invention, not only a gas-fluid separator 18 is arranged in the common return pipe portion 16, but also a filter 12.

[0057] The arrangement position of the filter 12 in the common return line portion 16 is also very advantageous, since the filter 12 can also only fully fulfill its function at a location at which no reversal of the flow direction of the fluid to be filtered takes place. This is precisely the case in the common return line portion 16, but it will theoretically also be possible in the first return line 8 or in the second return line 9, however in this case only a part of the fluid flowing in the actuator device 1 would be intercepted by the fluid 12.

[0058] [Fig.5A] represents a gas-fluid separator 18 according to a possible implementation of the invention, in schematic sectional view.

[0059] During operation of the actuator device 1 according to the invention, gas bubbles 27 may appear, which accumulate in the gas-fluid separator 18. As a rule, they accumulate in an upper part of the gas-fluid separator 18 near the ventilation valve 23, so that they can be removed from the circuit when the ventilation valve 23 is opened.

[0060] It is recognized that the supply connection 24 penetrates, via a tubular conduit, inside the gas-fluid separator 18, this tubular connection being, according to the embodiment shown, open at its front face and introduces the fluid to be introduced into the gas-fluid separator 18 in a flow direction which is oriented directly towards the ventilation valve 23.

[0061] Furthermore, an evacuation connection 25 is recognized which makes it possible to distribute the fluid introduced into the gas-fluid separator 18. This evacuation connection 25 is generally arranged in a lower part of the gas-fluid separator 18, so that the probability of entrainment of gas bubbles is very low.

[0062] In this lower part, there is also a connection 26 for the introduction of a fluid coming from an external source, this being able to be arranged in the gas-fluid separator 18 so that a fluid introduced via the external source has a flow direction which is oriented directly towards the discharge connection 25. It can also be provided that the connection 26 for the introduction of a fluid from an external source is arranged at the same height in the gas-fluid separator 18 as the discharge connection 25.

[0063] It is clear to the person skilled in the art that the concrete embodiment of the gas-fluid separator 18 is not fundamental to the basic principle of the present invention, so that other implementations than those shown are included in the invention.

[0064] In [Fig.5A], the state shown is that in which the ventilation valve 23 as well as the connection 26 for the external fluid source are in a closed state and the fluid circulating in the actuator device 1 is introduced via the supply connection 24 into the gas-fluid separator 18 and is discharged via the discharge connection 25. This results in an accumulation of gas or air bubbles 27 in an upper part of the gas-fluid separator 18 near the ventilation valve 23, isolated bubbles 27 also being able to be entrained via the discharge connection 25. More particularly, this occurs when a considerable number of gas bubbles 27 are already present in the gas-fluid separator 18 and ventilation of the circulating fluid would be advisable.

[0065] [Fig.5B] shows the state in which an external hydraulic source is connected to the connection 26 for introducing a fluid from the outside and supplies the actuator device 1 with fluid. At the same time, the ventilation valve 23 of the gas-fluid separator 18 is opened, which causes discharge of the gas bubbles or removal of the fluid containing the gas bubbles 27. It is particularly advantageous that the flow direction of the fluid introduced from the circuit into the gas-fluid separator 18 is oriented toward the opening opened by the ventilation valve 23, since the flow of fluid containing the air bubbles 27 or the gas bubbles from the actuator device 1 accumulating around the ventilation valve 23 can be separated extremely easily.

[0066] Due to the simultaneous introduction of fluid from the external source, a direct fluid flow from the supply connection 24 to the discharge connection 25 is attenuated or blocked, so that the fluid to be exchanged from the actuator device 1 is no longer introduced into the circuit, but leaves the actuator device 1 via the ventilation valve 23. This procedure allows a continuous flow that starts from the external source and extends, at the end of the fluid exchange, at least into the supply connection 24 of the gas-fluid separator 18.

[0067] [Fig.5C] shows a state in which the fluid of the actuator device 1 is entirely free of gas bubbles or the like and the already fresh fluid introduced via the external source leaves the ventilation valve 23. In this state, it can be certain that there has been a complete and safe exchange of the circulating fluid previously in the actuator device, in which there are no gas bubbles 27.

[0068] [Fig.5D] shows a state which is adopted in the connection in [Fig.5C] and in which the ventilation valve 23 as well as the connection 26 for the introduction of a fluid from an external source are closed again. It is recognized that the previously existing gas bubbles 27, as recognizable in [Fig.5A], are now no longer present, since a complete exchange of the fluid has taken place.

[0069] List of landmarks 1 - Electro-hydrostatic actuator device 2 - Bidirectional pump 2A - First pump connection 2B - Second pump connection 3 - Actuator 3A - First actuator chamber 3B - Second actuator chamber 4 - First supply line 5 - Second supply line 6 - First non-return valve 7 - Second non-return valve 8 - First return line 9 - Second return line 10 - Third non-return valve 11 - Fourth check valve 12 - Fluid filter 13 - Fluid reservoir 14 - Fifth non-return valve 15 - Sixth check valve 16 - Common return pipe section 17 - Two-way valve 18 - Gas-fluid separator 19 - Electric motor 20 - First control line of the two-way valve 21 - Second control line of the two-way valve 22 - Electronic control unit for switching the two-way valve 23 - Ventilation valve 24 - Power connection 25 - Drain connection 26 - Connection for the introduction of a fluid from an external source 27 - Gas bubbles 28 - Actuator Switching Valve

Claims

1. Claims Electro-hydrostatic actuator device (1) comprising: a bidirectional pump (2) for dispensing a fluid via a first connection (2A) and for sucking a fluid via a second connection (2B) or vice versa, an actuator (3) with a reciprocating movement, which is connected with the two connections (2A, 2B) of the bidirectional pump (2), a first supply line (4) for introducing a fluid from the first connection (2A) of the bidirectional pump (2) to a first chamber (3A) of the actuator (3), a second supply line (5) for introducing a fluid from the second connection (2B) of the bidirectional pump (2) to a second chamber (3B) of the actuator (3), a first valve (6), preferably a non-return valve (6), in the first supply line (4),in order to prevent a return flow of a fluid from the first chamber (3A) of the actuator (3) to the first connection (2A) of the pump (2) via the first supply line (4), a second valve (7), preferably a non-return valve (7), in the second supply line (5), in order to prevent a return flow of a fluid from the second chamber (3B) of the actuator (3) to the second connection (2B) of the pump (2) via the second supply line (5), a first return line (8) for the return of a fluid from the first chamber (3A) of the actuator (3) to the first connection (2A) of the bidirectional pump (2), a second return line (9) for the return of a fluid from the second chamber (3B) of the actuator (3) to the second connection (2B) of the bidirectional pump (2), a third valve (10), preferably a non-return valve (10),in the first return line (8), in order to prevent a flow of a fluid from the bidirectional pump (2) to the actuator (3) via the first return line (8), a fourth valve (11), preferably a non-return valve (11), in the second return line (9), in order to prevent a flow of a fluid from the bidirectional pump (2) to the actuator (3) via the second return line (9), a common return line portion (16) which branches off into the first return line (8) and the second return line (9), a two-way valve (17), which is switched depending on the discharge direction of the bidirectional pump (2), in order to fluidically connect the common return line portion (16) either with the first chamber (3A) of the actuator (3) or with the second chamber (3B) of the actuator (3) and a gas-fluid separator (18) which is arranged in the common return line portion (16) and / or one of the two return lines (8, 9).

2. An actuator device (1) according to claim 1, further comprising a fluid filter (12) which is disposed in the common return line portion (16).

3. Actuator device (1) according to one of the preceding claims, wherein a return flow of a fluid from the actuator (3) flows, via the two-way valve (17), the common return line portion (16) and a third or fourth non-return valve (10, 11), in the flow direction towards the connection (2A, 2B), serving as the suction side, of the bidirectional pump (2).

4. An actuator device (1) according to the preceding claim 3, wherein the gas-fluid separator (18) comprises a vent valve (23) for venting gas accumulated in the gas-fluid separator (18), preferably wherein the vent valve (23) is arranged in the gas-fluid separator (18) at the location where air or gas accumulates in a normal orientation of the actuator device (1).

5. Actuator device (1) according to one of the preceding claims, wherein the gas-fluid separator (18) comprises, in addition to a supply connection (24) for the introduction of a fluid circulating in the actuator device and an evacuation connection (25) for the evacuation of the fluid from the gas-fluid separator (18), a connection (26) for the introduction of a fluid from an external source, preferably wherein the connection (26) for introducing a fluid from an external source is adapted to introduce a fluid into the gas-fluid separator (18) in a first flow direction which is generally oriented towards the discharge connection (25).

6. Actuator device (1) according to the preceding claim, wherein the supply connection (24) is adapted to introduce a fluid into the gas-fluid separator (18) in a second flow direction which is oriented generally towards the ventilation valve (23), preferably in which the first flow direction and the second flow direction form an angle between them and are preferably arranged orthogonally to each other.

7. Actuator device (1) according to one of the preceding claims, further comprising a fluid reservoir (13) for providing a fluid at a suction side of the bidirectional pump (2), preferably wherein the fluid reservoir (13) is arranged in the return line (8, 9) upstream of a third or fourth non-return valve (10, 11).

8. Actuator device (1) according to one of the preceding claims, wherein the two-way valve (17) is adapted to connect respectively one of the two chambers (3A, 3B) of the actuator (3) with the common return portion (16), wherein preferably the chamber (3A, 3B) of the actuator (3) which is connected with the common return portion (16) via the two-way valve (17) is the one out of which a fluid flows due to a movement of the actuator (3).

9. Actuator device (1) according to one of the preceding claims, wherein the two-way valve (17) is provided with two inlets and one outlet, wherein a respective inlet is connected with a respective chamber (3A, 3B) of the actuator (3) and the outlet is connected with the common return portion (16).

10. Actuator device (1) according to one of the preceding claims, wherein the two-way valve (17) is a 3 / 2-way valve or a 3 / 3-way valve.

11. Actuator device (1) according to claim 9 or according to claims 9 and 10, wherein, when implementing the two-way valve (17) as a 3 / 2-way valve, a central position is a neutral position, in which the two inlets and the outlet are not connected to each other and are preferably closed.

12. Actuator device (1) according to one of the preceding claims, wherein the two-way valve (17) is provided with a pilot control (20, 21) for switching the two-way valve (17), which operates on the basis of the pressure applied at the two connections of the two-way pump (2).

13. Actuator device (1) according to one of the preceding claims, wherein the two-way valve (17) is provided with an electrical control (22) for switching the two-way valve (17), which operates on the basis of the pressure applied at the two connections (3A, 3B) of the two-way pump (2) or the direction of rotation of the two-way pump (2), preferably wherein, for determining the pressure at the two connections (3A, 3B) of the two-way pump (2), at least one pressure sensor is provided for determining the pressure at one of the two connections (3A, 3B), which is connected with the electronic control (22) or a direction of rotation sensor is provided for detecting the direction of rotation of the two-way pump (2).

14. Actuator device (1) according to one of the preceding claims, wherein the bidirectional pump (2) is a motor pump which is equipped with an electric motor (19) and / or the actuator (3) is a double-acting cylinder.

15. Aircraft, more particularly airplane, with an actuator device (1) according to one of the preceding claims.

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