System, aircraft and procedures

Abstract

The present invention relates to a system comprising a pump and an actuator, the system comprising a shuttle valve connected to the pump and the actuator.

Description

[0001] The present invention relates to a system comprising a pump and an actuator.

[0002] Electrohydraulic systems with a speed-controlled pump in the form of an electric motor pump, which can usually pump bidirectionally, and one or more actuators in the form of hydraulic cylinders are known from the prior art. An electrohydrostatic actuator, for example, forms such a system. The chambers of the actuator are connected to the pump connections, so that the direction of rotation of the pump determines the direction of movement of the actuator. A reservoir in the form of a hydraulic accumulator is usually also present, in particular to preload the pressure on the suction side of the pump and / or to compensate for volume compensation resulting from temperature fluctuations in the fluid and from different positions of one or more actuators. The pressure at the pump connections, i.e., at the pump inlet and pump outlet, is determined by the external loads applied to the actuator.

[0003] A schematic representation of a system in the form of an electrohydrostatic actuator from the state of the art is shown in Fig. 14 shown.

[0004] The electrohydrostatic actuator in Fig. 14 comprises an electric motor 1 which can be operated bidirectionally and which can drive a pump 2 which can be operated bidirectionally, an actuator 4, two check valves 6 which can be used as anti-cavitation valves or suction side directional valves, and a reservoir 7. The elements of the electrohydrostatic actuator from Fig. 14 are connected by cables, as can be seen from Fig. 14. The electric motor 1 and the pump 2 form an electric motor pump.

[0005] Also known are systems with a unidirectional electric motor pump, an actuator and a switching valve, which defines into which chamber of the actuator the electric motor pump delivers.

[0006] When operating an electrohydrostatic actuator, a distinction is made between three modes.

[0007] An electrohydrostatic actuator can be operated in an opposing load mode. The direction of an external load acting on the actuator and the direction of movement of the actuator differ, for example, being opposite. Pressure builds up between the actuator and the pump outlet or pressure side of the pump, with the pressure level being proportional to the external load. The pump inlet or suction side of the pump is not pressurized. The electrohydrostatic actuator converts electrical energy into hydraulic and mechanical energy to overcome the external load.

[0008] In Fig. 15 are states of the electrohydrostatic actuator from Fig. 14 when operating the electrohydrostatic actuator in a counterload mode. The direction of movement M of the actuator 4 and the load direction L of the external load are opposite, as indicated by the thick arrows with the reference symbols M and L in Fig. 15. The pump 2 delivers fluid in pumping direction P, as shown in Fig. 15 is shown by the thick arrow with the reference symbol P. This means that the Fig. 15 pipe sections shown in bold are pressurized. Fig. 15 pipe sections not shown in bold are not pressurized.

[0009] An electrohydrostatic actuator can be operated in a hold or "hold load" mode. In this mode, one or more external loads are applied to the actuator. The actuator does not move and merely holds its position. A pressure builds up between the actuator and the pump outlet or pressure side of the pump, with the pressure level proportional to the external load. The pump inlet or suction side of the pump is not pressurized. The electrohydrostatic actuator converts electrical energy into hydraulic energy to hold the external load, but the electric motor or pump does not rotate.

[0010] In Fig. 16 are states of the electrohydrostatic actuator from Fig. 14 when operating the electrohydrostatic actuator in a holding mode. The load direction L of the external load acts on the stationary actuator 4, as indicated by the thick arrow with the reference symbol L in Fig. 16. Pump 2 does not pump fluid and does not rotate, but counteracts the external load. As a result, the Fig. 16 pipe sections shown in bold are pressurized. Fig. 16 pipe sections not shown in bold are not pressurized.

[0011] Hold mode is particularly damaging to the pump. Because the pump is not rotating, no lubricating film forms between the moving parts, resulting in metal-to-metal contact. This shortens the pump's service life.

[0012] The electric motor also doesn't rotate in hold mode. However, the electric motor is energized to generate torque, as it maintains the position of the actuator. In hold mode, the electric motor can overheat very quickly due to a lack of heat dissipation.

[0013] An electrohydrostatic actuator can be operated in a load-following or "aiding load" mode. In this mode, one or more external loads are applied to the actuator. The actuator moves in the same direction as the external load. Pressure builds up between the actuator and the pump inlet or suction side of the pump, with the pressure level proportional to the external load. The pump outlet is not pressurized.

[0014] In Fig. 17 are states of the electrohydrostatic actuator from Fig. 14 when operating the electrohydrostatic actuator in a load following mode. The direction of movement M of the actuator 4 and the load direction L of the external load have the same direction, as indicated by the thick arrows with the reference symbols M and L in Fig. 17. The pump 2 delivers fluid in pumping direction P, as shown in Fig. 17 is represented by the thick arrow with the reference symbol P. However, the pump 2 is not actively driven, but is driven by the pressure applied to the fluid by the external load. Fig. 17 pipe sections shown in bold are pressurized. Fig. 17 pipe sections not shown in bold are not pressurized.

[0015] In load-following mode, the electric motor pump operates in regenerative mode, meaning hydraulic energy is converted into electrical or thermal energy in the electric motor pump. The electric motor pump converts hydraulic energy into electrical energy by operating the electric motor pump as a generator, which is then dissipated by resistance and converted into heat.

[0016] If the actuator's actuation rate, such as speed or acceleration, is low, no lubricating film forms between the pump's moving parts, resulting in metal-to-metal contact. This shortens the pump's service life.

[0017] When the actuator's actuation rate is high, the energy to be dissipated is very high, which has a significant impact on the design of the chopper resistors. Chopper resistors are electrical resistances installed for the purpose of dissipating electrical energy. Chopper resistors increase the weight of the system, which is particularly disadvantageous for aerospace applications.

[0018] In holding mode, wear between the pump parts is greatly increased.

[0019] For operating the system in a load following mode, the design of the electrical resistances in the electric motor pump is preferably of great importance.

[0020] According to the current state of the art, electrohydrostatic actuators are primarily used as backup solutions. In future aircraft architectures, many aircraft manufacturers will envision them for primary operation. The endurance requirements for these future applications are correspondingly high. Solutions described in the current state of the art are not suitable for these continuous applications, and optimizing operating conditions is of great importance.

[0021] Against this background, the present invention is based on the object of improving an above-mentioned system, in particular with regard to wear resistance and / or continuous operation capability.

[0022] This object is achieved by the system having the features of independent claim 1. Advantageous developments of the invention are the subject of the dependent claims.

[0023] Accordingly, the invention provides that the system has a shuttle valve connected to the pump and the actuator.

[0024] The system is preferably intended for use in an aircraft.

[0025] Preferably, at least one connection of the pump is connected to at least one connection of the shuttle valve and at least one connection of the actuator is connected to at least one connection of the shuttle valve.

[0026] The shuttle valve can be arranged in a single unit or in several distributed units. For example, the shuttle valve can comprise several valves and / or, in particular, adjustable, throttles.

[0027] The system can be arranged in one unit, for example forming an electro-hydraulic or electro-hydrostatic actuator, or it can be arranged in different units.

[0028] The system preferably comprises a throttle, in particular an adjustable one, that enables pressure-dependent and / or adjustable throttling. The adjustable throttle preferably enables an adjustable throttling function.

[0029] The pump is preferably a hydraulic pump and / or an electric motor pump. The actuator is preferably a single- or double-acting hydraulic cylinder. The shuttle valve is preferably a hydraulic shuttle valve.

[0030] Preferably, the system comprises one or more pumps, in particular redundant electrohydrostatic electric motor pumps, which can actuate one or more consumers, in particular actuators.

[0031] Preferably, the pump is a bidirectional electric motor pump and / or can control the movement of the actuator by conveying a fluid in one or the other direction.

[0032] It is preferably provided that the shuttle valve has two or three connections and / or two or three switching positions.

[0033] The shuttle valve is preferably a 3 / 3-way valve. It is also conceivable that the shuttle valve is a 2 / 2-way valve, especially in a system with a single-acting actuator.

[0034] It is preferably provided that the shuttle valve has a switching position in which a flow between one connection of the actuator and the pump and / or a switching position in which a flow between another connection of the actuator and the pump is enabled and / or a switching position in which a flow through the shuttle valve is prevented or impeded.

[0035] It is preferably provided that the system has one or more adjustable throttles and / or that the shuttle valve is designed such that one, two or more switching positions of the shuttle valve have an adjustable throttle, by means of which in particular a volume flow and / or a pressure loss of a fluid flowing through the shuttle valve can be adjusted.

[0036] Preferably, the acceleration and / or the speed or the actuation rate of the actuator can be controlled by means of an adjustable throttle, in particular when the system is operated in a load following mode.

[0037] The adjustable throttle can preferably be set to a throttling of “zero”, i.e. no flow through the throttle.

[0038] The adjustable throttle can also be set in a neutral position other than “zero”, i.e. so that a flow can occur through the throttle.

[0039] It is preferably provided that the shuttle valve has an adjustable slide and / or the adjustable throttle is made possible by means of the adjustable slide.

[0040] It is preferably provided that the slide is designed such that a stroke of the slide can be adjusted by means of the pump, in particular by means of a pressure generated by the pump.

[0041] It is preferably provided that the shuttle valve is designed in such a way as to control the shuttle valve by means of a controller and / or by means of the pump, in particular by means of a pressure generated by the pump.

[0042] The level of throttling by the adjustable throttle is preferably passively defined by a control pressure of a pump.

[0043] Preferably, the level of throttling can also be actively adjusted by means of a control, whereby a pressure of the pump and / or a direction of rotation of the pump can serve as input variables for the control.

[0044] It is preferably provided that the system has a throttle valve and / or a leak, in particular between connections of the actuator.

[0045] Preferably, the chambers of one actuator or several actuators can be connected via a throttle valve.

[0046] It is preferably provided that the shuttle valve has a negative overlap, in particular in a switching position in which a flow through the shuttle valve is prevented or impeded.

[0047] Preferably, an “underlap” is provided in a switching position of the shuttle valve in which the shuttle valve prevents or obstructs a flow through the shuttle valve.

[0048] Preferably, the system comprises lines, check valves and / or a reservoir.

[0049] The invention also relates to an aircraft, in particular an airplane, with a system according to the invention.

[0050] Preferably, the method comprises the following step: - Controlling a shuttle valve using a pump and / or a controller.

[0051] Preferably, the method comprises the following steps: - Moving an actuator with a direction of movement in a load direction of a load; - Controlling a shuttle valve by means of a controller and / or a pump and / or throttling a flow through the shuttle valve.

[0052] It is preferably provided that the throttling takes place depending on or proportional to a pressure, in particular a pump.

[0053] Preferably, the electric motor pump of an electrohydrostatic actuator is unloaded during operation in a holding mode and / or a load-following mode. In the holding mode, the electric motor pump is preferably completely unloaded. In the load-following mode, the suction side of the electric motor pump is preferably not pressurized and / or the electric motor pump is not operated in a regenerative mode.

[0054] Preferably, the invention has a positive influence on both the service life and the design of the electric motor pump.

[0055] Preferably, the requirements of an electric motor pump are reduced when operating in a holding mode and / or load following mode.

[0056] Preferably, the pressure and suction sides of the pump alternate depending on the direction of rotation of the pump.

[0057] Preferably, the pump is unloaded when the system is operating in a holding mode, i.e., when the actuator is holding a load. Preferably, the pressure is locked in response to an external load.

[0058] When the system is operated in a load-following mode, for example, in the case of "aiding loads," the pump is preferably not operated in a regenerative mode. When the system is operated in a load-following mode, the hydraulic energy is preferably dissipated in an adjustable throttle and not exclusively in a "chopper" resistor of the power electronics of an electric drive, in particular an electric motor. When the system is operated in a load-following mode, the suction side of the pump is preferably not pressurized.

[0059] It should be noted that the terms "a" and "an" do not necessarily refer to exactly one of the elements, although this represents a possible embodiment, but can also refer to a plurality of the elements. Likewise, the use of the plural also includes the presence of the element in question in the singular, and conversely, the singular also encompasses several of the elements in question. Furthermore, all features of the invention described herein can be combined with one another as desired or claimed in isolation from one another.

[0060] Further advantages, features, and effects of the present invention will become apparent from the following description of preferred embodiments with reference to the figures, in which identical or similar components are designated by the same reference numerals. Herein: Fig. 1 to 5: schematic circuit diagrams of an embodiment of a system according to the invention. Fig. 6: a schematic circuit diagram of a shuttle valve of an embodiment of a system according to the invention. Fig. 7 to 9: Sectional views through a shuttle valve of an embodiment of a system according to the invention. Fig. 10 to 13: schematic circuit diagrams of an embodiment of a system according to the invention. Fig. 14 to 17: schematic circuit diagrams of an embodiment of a system known from the prior art.

[0061] In the Fig. Figures 1 to 5 each depict a system comprising an electric motor 1, a pump 2, which together form an electric motor pump, two check valves in the form of pressure directional valves 3, an actuator 4, a shuttle valve 5, two check valves 6, which can be used as anti-cavitation valves or suction side directional valves, and a reservoir 7. The elements of the system are connected by lines.

[0062] When operating the system from the Fig. 1 and Fig. 2 in an opposing load mode, an external load acts on the actuator 4 in a load direction L, and the direction of movement M of the actuator is opposite to the load direction L, as indicated by the thick arrows with the reference symbols M and L in the Fig. 1 and Fig. 2. The pump 2 delivers fluid in pumping direction P, as shown in Fig. 1 and Fig. 2 is represented by the thick arrow with the reference symbol P. This means that the Fig. 1 and Fig. 2 The line sections shown in bold are pressurized, particularly between the actuator 4 and the pump outlet or the pressure side of the pump 2. The Fig. 1 and Fig. 2 The line sections not shown in bold are not pressurized. The pressure generated by the pump 2 at the pump outlet is used to switch the shuttle valve 5 into a switching position in which fluid can flow from the actuator 4 through the shuttle valve 5 towards the respective suction side of the pump 2. Depending on the load direction L or the direction of rotation of the pump 2, the shuttle valve 5 is thus automatically switched to the appropriate switching position through the pressurized lines, as can be seen from the Fig. 1 and Fig. 2. The suction side of pump 2, or the pump inlet, is therefore not pressurized. The pump outlet is pressurized.

[0063] Fig. 1 and Fig. 2 show states when operating the system in a counterload mode, in which the actuator 4 or the pump 2 is moved in the direction of movement M against a load direction L, whereby the Fig. 1 and Fig. 2 can be distinguished by the direction of movement M and the load direction L.

[0064] Fig. 3 and Fig. 4 show states when operating the system in a hold mode, in which the actuator 4 or the pump 2 is not moved, whereby the Fig. 3 and Fig. 4 differ by the load direction L.

[0065] When operating the system from the Fig. 3 and Fig. 4 In a holding mode, the shuttle valve 5 is in a center position as a switching position, whereby the actuator 4 is fluidically separated from the return line or the pump inlet, or in which flow through the shuttle valve is prevented or impeded. The pressure resulting from the external load is blocked between the actuator 4 and the shuttle valve 5, and the pump 2 is relieved.

[0066] Since pump 2 is unloaded, there is no wear between the pump parts. The electric motor 1 is also not energized, thus eliminating overheating problems. This occurs regardless of the load direction L in which the external load is applied. The Fig. 3 and Fig. 4 pipe sections shown in bold are pressurized. The Fig. 3 and Fig. 4 pipe sections not shown in bold are not pressurized.

[0067] Fig. Figure 5 shows states when operating the system in a load following mode, in which the actuator 4 is moved in a direction of movement M which points in the same direction as the load direction L. The direction of movement M of the actuator 4 and the load direction L of the external load have the same direction, as indicated by the thick arrows with the reference symbols M and L in Fig. 5. The pump 2 delivers fluid in pumping direction P, as shown in Fig. 5 is represented by the thick arrow with the reference symbol P. The Fig. 5 pipe sections shown in bold are pressurized. The Fig. 5 Pipe sections not shown in bold are not pressurized.

[0068] In the load following mode, an external load acts on the actuator 4 in a load direction L, and the movement direction M of the actuator 4 is the same as the load direction L of the external load.

[0069] However, it is preferable not to use a simple shuttle valve as in the Fig. 1 to 5 are used when operating the system in a load-following mode. The pressure drop from the pressurized side to the return or pump inlet preferably adapts to the external load and the actuation rate of actuator 4 to ensure that no pressure is applied to the suction side of pump 2 and that it is not operated in a regenerative mode.

[0070] At high external loads and low actuator actuation rates, the pressure drop is preferably large. At low external loads and high actuator actuation rates, the pressure drop is preferably small.

[0071] In Fig. 6 shows a shuttle valve that meets these requirements. The shuttle valve from Fig. 6 is preferably controlled by the pressure at the pump outlet PA, which is defined depending on the direction of rotation of the pump. One port of the shuttle valve leads to the pump inlet PE. The other two ports of the shuttle valve lead to the ports of the actuator AA, with one port AA being provided for a chamber.

[0072] The upper and lower switching position of the shuttle valve from Fig. 6, which is not the middle position in which the shuttle valve Fig. 6 brings the system into a holding mode, are each designed in such a way that a volume flow and / or pressure loss through the shuttle valve is set in the respective switching position proportional to the pressure of the pump outlet PA, thus setting a throttling in each case.

[0073] For this purpose, the shuttle valve preferably has a slide S pre-tensioned by a slide spring F and a slide sleeve H or a slide group, wherein the stroke of the slide S is controlled by the pressure of the pump outlet PA, as can be seen from the Fig. 7 to 9.

[0074] How this Fig. 7, the shuttle valve or slide S in conjunction with the slide sleeve H blocks the flow between a connection of the actuator AA and the suction side of the pump or the pump inlet PE, provided that there is no pressure at the pump outlet PA acting on the slide S, as indicated by the dashed lines, which indicate the lack of pressure at the pump outlet PA and the lack of flow between the connection of the actuator AA and the suction side of the pump or the pump inlet PE, in Fig. 7 is indicated. In Fig. 7 is a position of the slide S in which no flow through the Fig. 7 shown connections AA and PE.

[0075] The stroke of the slide S relative to the slide sleeve H defines the flow area from the connection of the actuator AA back to the return or pump inlet PE.

[0076] The spool S is preloaded by the spring F. The pressure at the pump outlet PA acts on the spool S and then on the spring F. An increase in the pressure at the pump outlet PA actuates the spool S within the spool sleeve H and expands the flow area from the connection of the actuator AA to the return line or to the pump inlet PE, as shown in Fig. 8. The increased pressure at the pump outlet PA and the increased flow area, which leads to a flow between the connection of the actuator AA and the suction side of the pump or the pump inlet PE, is shown in Fig. 8 indicated by the solid arrows. A small flow area causes a high pressure drop. In Fig. Figure 8 shows a stroke of the slide S at a high external load and / or a low actuation rate of the actuator.

[0077] In Fig. 9 is the stroke of the slide S at a value different from that in Fig. 8 shows the increased pressure at the pump outlet PA. The stroke of the slide S is thus greater than in Fig. 8, which leads to a Fig. 8 increased flow area. The further increased pressure at the pump outlet PA and the further increased flow area, which leads to an increased flow between the connection of the actuator AA and the suction side of the pump or the pump inlet PE, is in Fig. 9 indicated by the bold arrows. A large flow area causes a low pressure drop. In Fig. 9 shows a stroke of the slide S at a low external load and / or in particular a high actuation rate of the actuator.

[0078] In Fig. 10 is essentially the system of Fig. 5 with a differently designed shuttle valve 5. The shuttle valve 5 in Fig. 10 shows in the Fig. 10 lower switching position has an adjustable throttle. This switching position is in Fig. 10 active.

[0079] Fig. 10 shows states when operating the system in a load following mode, in which the actuator 4 is moved in a direction of movement M which points in the same direction as the load direction L. The direction of movement M of the actuator 4 and the load direction L of the external load have the same direction, as indicated by the thick arrows with the reference symbols M and L in Fig. 10. The pump 2 delivers fluid in pumping direction P, as shown in Fig. 10 is represented by the thick arrow with the reference symbol P. The Fig. 10 pipe sections shown in bold are pressurized. The Fig. 10 The pipe sections not shown in bold are not pressurized. Fig. 10 The line sections shown in dashed lines are with throttled pressure, which is generated by the switching position with the adjustable throttle of the shuttle valve 5 from the pressure caused by the external load.

[0080] A condition like in Fig. 10 is produced as follows from a system which is not subjected to an external load and is at a standstill, in which the shuttle valve 5 is in the middle position, i.e. in a position in which flow through the shuttle valve is prevented or impeded.

[0081] First, an external load is applied to actuator 4. The resulting pressure is trapped in the line section between actuator 4, check valve 3, and shuttle valve 5, which is switched to the center position. Actuator 4 cannot move.

[0082] Subsequently, a movement direction M of actuator 4 is specified or commanded in the same direction as the external load is applied. Pump 2 delivers accordingly in the pumping direction P.

[0083] Since actuator 4 cannot initially move due to the center position of shuttle valve 5, pressure builds up at the pump outlet, which activates shuttle valve 5. The spool in the spool group of shuttle valve 5 begins to move, and the shuttle valve begins to move into the switching position with the adjustable throttle. A fluidic connection is established between actuator 4 and the suction side of the pump or the pump inlet PE, enabling flow through the shuttle valve.

[0084] This allows actuator 4 to now move in the direction of movement M.

[0085] The rate at which actuator 4 moves stabilizes at the same rate at which pump 2 delivers.

[0086] If actuator 4 moves at a lower rate than the rate at which pump 2 delivers, more pressure builds up at the pump outlet. The spool within the spool group of shuttle valve 5 increases its stroke, the flow area increases, and the pressure is Fig. 10 active switching position of the shuttle valve is therefore less throttled and the actuator 4 is accelerated due to the external load.

[0087] If actuator 4 moves at a higher rate than the rate at which pump 2 delivers, the pressure at the pump outlet drops. The spool within the spool group of shuttle valve 5 reduces its stroke, the flow area decreases, and the pressure is reduced by the Fig. 10 active switching position of the shuttle valve is therefore more throttled and the actuator 4 is braked by the increased pressure.

[0088] The pressure at the pump outlet controls the stroke of the slide or the throttling of the shuttle valve 5 and can therefore be referred to as control pressure or actuating pressure. The pressure at the pump outlet indirectly defines the pressure loss from the actuator 4 back to the suction side of pump 2.

[0089] The hydraulic energy resulting from the external load is dissipated by the pressure loss at the shuttle valve 5. The suction side of pump 2 is then not pressurized, so that pump 2 or electric motor 1 are not operated in a regenerative mode.

[0090] Pump 2 is preferably completely unloaded in load-following mode. The lubricating film that forms between the moving parts of pump 2 protects the pump 2 and promotes its longevity.

[0091] Since pump 2 or electric motor 1 are not operated in a regenerative mode, the hydraulic energy is not converted into electrical energy, which would otherwise be dissipated. This is beneficial for the design of the electric drive or electric motor 1 and results in a lower weight of the electric motor 1 and / or the system.

[0092] The shuttle valve with adjustable throttle in at least one switching position improves the operation of the system in a load following mode.

[0093] In Fig. 11 shows a state during operation of the system in a load following mode, where the direction of movement M and the load direction L are opposite Fig. 10 run in opposite directions. The shuttle valve 5 in Fig. 11 thus shows in the Fig. 11 upper switching position has an adjustable throttle. Fig. 11 are, under the condition that the direction of movement M and the load direction L are reversed, analogous to the states in Fig. 10 states shown.

[0094] The shuttle valve 5 can only be used in the Fig. 10 and Fig. 11 upper or lower switching position or in both switching positions have an adjustable throttle.

[0095] Operation in load following mode is preferably carried out in a fully passive manner, without the need for control.

[0096] In Fig. 12 shows a system with an electrical control 8 which controls the shuttle valve 5.

[0097] The control or switching of the shuttle valve 5 is in Fig. 12 is not ensured passively by the pressure of pump 2, but actively by a controller 8. This can be done using an electronic or electrical unit based on parameters such as a pressure in a line or a direction of rotation of pump 2. However, a combination of controlling the shuttle valve by pump 2 and a controller 8 is also conceivable.

[0098] It is conceivable that in certain applications a reduction in the stiffness of the system is necessary. This can be achieved by providing a negative overlap or an "underlap" in the shuttle valve in the center position or in the nominal non-switched position. A small internal leakage between the chambers of the actuator can also be provided. When the system is operated in a holding mode, the "underlap" and / or leakage will require the electric motor pump to deliver a small amount of flow to hold the actuator in position. When the system is operated in a load-following mode, the leakage may cause the pump and actuator to move in opposite directions, depending on the external load. However, pressure on the suction side of the pump does not build up, so the electric motor pump is not operating in a regenerative mode.

[0099] In Fig. 13, the negative overlap in the middle position of the shuttle valve 5 is indicated by a dashed line. Likewise, the system in Fig. 13 a throttle valve 9, which acts as a leak, between the chambers of the actuator 4.

[0100] One advantage of the invention is that when the system is operating in hold mode, the electric motor pump does not have to build up pressure. The pressure resulting from the external load is trapped between the actuator, check valve, and shuttle valve. The pump is thus relieved of pressure, which has a positive impact on its service life.

[0101] An advantage of the invention is that when the system is operated in a load-following mode, the electric motor pump is not operated in a regenerative mode. There is then no need to dissipate electrical energy from the electric motor pump's regenerative operation in resistors, which has a positive impact on the design of the electric motor.

Claims

[1] System with one pump and one actuator, characterized by that the system has a shuttle valve connected to the pump and the actuator. [2] System according to claim 1, characterized by that the shuttle valve has two or three connections and / or two or three switching positions. [3] System according to claim 1 or 2, characterized by that the shuttle valve has a switching position in which a flow between one connection of the actuator and the pump and / or a switching position in which a flow between another connection of the actuator and the pump is enabled and / or a switching position in which a flow through the shuttle valve is prevented or impeded. [4] System according to one of the preceding claims, characterized bythat the system has one or more adjustable throttles and / or that the shuttle valve is designed such that one, two or more switching positions of the shuttle valve have an adjustable throttle, by means of which in particular a volume flow and / or a pressure loss of a fluid flowing through the shuttle valve can be adjusted. [5] System according to one of the preceding claims, characterized by that the shuttle valve has an adjustable slide and / or the adjustable throttle is made possible by means of the adjustable slide. [6] System according to one of the preceding claims, characterized by that the slide is designed such that a stroke of the slide can be adjusted by means of the pump, in particular by means of a pressure generated by the pump. [7] System according to one of the preceding claims, characterized bythat the shuttle valve is designed in such a way as to control the shuttle valve by means of a controller and / or by means of the pump, in particular by means of a pressure generated by the pump. [8] System according to one of the preceding claims, characterized by that the system has a throttle valve and / or a leak, particularly between connections of the actuator. [9] System according to one of the preceding claims, characterized by that the shuttle valve has a negative overlap, particularly in a switching position in which flow through the shuttle valve is prevented or impeded. [10] System according to one of the preceding claims, characterized by that the system has pipes, check valves and / or a reservoir. [11] Aircraft, in particular an airplane, with a system according to one of the preceding claims. [12] Method for operating a system, in particular according to one of claims 1 to 10, characterized by the step: - Controlling a shuttle valve using a pump and / or a controller. [13] Method according to claim 12, characterized by the steps: - Moving an actuator with a direction of movement in a load direction of a load; - Controlling a shuttle valve by means of a controller and / or a pump and / or throttling a flow through the shuttle valve. [14] Method according to claim 13, characterized by that the throttling is dependent on or proportional to a pressure, in particular a pump.

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