System, aircraft and method

Abstract

The present invention relates to a system with a pump (2) and an actuator (4), the system having a circuit selector (5), which is connected to the pump (2) and the actuator (4). Figure 1

Description

Title of the invention: System, aircraft and method

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

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

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

[0004] The electrohydrostatic actuator of [Fig. 14] has an electric motor 1 which can operate in both directions, i.e. can operate bidirectionally, which can drive a pump 2 which can operate in both directions, i.e. can operate bidirectionally, an actuator 4, two non-return valves 6, which can be used as anti-cavitation valves or suction side direction valves, and a reservoir 7. The elements of the electrohydrostatic actuator of [Fig. 14] are connected to each other by cables as can be seen from [Fig. 14]. The electric motor 1 and the pump 2 form an electric motor pump.

[0005] Systems with a unidirectional electric motor pump, an actuator and a switching valve are similarly known, which defines the actuator chamber into which the electric motor pump discharges.

[0006] During the operation of an electrohydrostatic actuator, three modes are distinguished.

[0007] An electrohydrostatic actuator can operate in a counter-load or "Opposing Load" mode. The load direction of an external load acting on the actuator and the direction of movement of the actuator are different and are, for example, opposite. In this context, a pressure is established between the actuator and the pump outlet or the pressure side of the pump, the pressure level being proportional to the external load. The pump inlet or the suction side of the pump is not subjected to the action of pressure in this context. The electrohydrostatic actuator converts electrical energy into hydraulic and mechanical energy in this context to overcome the external load.

[0008] [Fig. 15] illustrates states of the electrohydrostatic actuator of [Fig. 14] during operation of the electrohydrostatic actuator in a counter-load mode. The movement direction M of the actuator 4 and the load direction L of the external load are opposite, as illustrated by the thick arrows with reference letters M and L in [Fig. 15]. The pump 2 delivers fluid in the pumping direction P, as illustrated in [Fig. 15] by the thick arrow with reference number P. The cable sections illustrated in bold in [Fig. 15] are thus subjected to the action of pressure. The cable sections not illustrated in bold in [Fig. 15] are not subjected to the action of pressure.

[0009] An electrohydrostatic actuator can operate in a stop or "Halte Load" mode. An external load or several external loads are present on the actuator. However, the actuator does not move in this context and only maintains the position. A pressure is established in this context between the actuator and the pump outlet or the pressure side of the pump, the pressure level being proportional to the external load. The pump inlet or the suction side of the pump is not subjected to the action of a pressure in this context. The electrohydrostatic actuator converts electrical energy into hydraulic energy in this context to maintain the external load, the electric motor or the pump do not rotate however.

[0010] [Fig. 16] illustrates states of the electrohydrostatic actuator of [Fig. 14] during operation of the electrohydrostatic actuator in a stop mode. The load direction L of the external load acts in this context on the unmoved actuator 4 as illustrated by the thick arrow with the reference number L in [Fig. 16]. The pump 2 does not pump any liquid and does not rotate, however it acts against the external load. Thus, the cable sections shown in bold in [Fig. 16] are subject to the action of pressure. The cable sections not shown in bold in [Fig. 16] are not subject to the action of pressure.

[0011] The stop mode is particularly detrimental to the pump. Due to the rotational movement of the pump not being present, no lubricating film is formed between the moving parts of the pump so that there is metal-to-metal contact. The service life of the pump is thus impaired.

[0012] The electric motor also does not rotate in the stop mode. The electric motor is, however, supplied with current to generate a rotational torque in as it maintains the actuator position. In the stop mode, the electric motor can overheat very quickly due to a lack of heat dissipation.

[0013] An electrohydrostatic actuator may operate in an input load or "Aiding Load" mode. In this context, an external load or several external loads are applied to the actuator. The actuator moves in the same direction of movement as the load direction of the external load or external loads. A pressure is established in this context between the actuator and the pump inlet or the suction side of the pump, the pressure level being proportional to the external load. The pump outlet is not subjected to pressure in this context.

[0014] [Fig.17] illustrates states of the electrohydrostatic actuator of [Fig.14] when operating the electrohydrostatic actuator in an input load mode. The direction of movement M of the actuator 4 and the load direction L of the external load have the same direction as illustrated by the thick arrows with reference numbers M and L in [Fig. 17]. The pump 2 delivers fluid in the pumping direction P as illustrated in [Fig. 17] by the thick arrow with reference letter P. However, the pump 2 is not actively driven but is driven by the pressure applied to the fluid by the external load. The cable sections shown in bold in [Fig. 17] are subject to the action of pressure. The cable sections not shown in bold in [Fig. 17] are not subject to the action of pressure.

[0015] The electric motor pump operates in the input load mode in the regenerative mode, in other words the hydraulic energy is converted in the electric motor pump into electrical or thermal energy. The electric motor pump converts, for example, hydraulic energy into electrical energy by operating the electric motor pump in generator mode and this is then destroyed by resistors and is converted into heat.

[0016] When the actuation rate, i.e., the speed or acceleration of the actuator, is small, no lubricating film forms between the moving parts of the pump, so that there is metal-to-metal contact. The service life of the pump is thus impaired.

[0017] When the actuation rate of the actuator is large, the energy to be destroyed is very high, which has a great impact on the design of the chopper resistors.

[0018] Chopper resistors are electrical resistors, which are installed for the purpose of destroying electrical energy. Chopper resistors increase the weight of the system, which is disadvantageous in particular for aeronautical applications.

[0019] In the shutdown mode, wear between pump parts is greatly increased.

[0020] For operation of the system in an input load mode, the design electrical resistances in the electric motor pump are preferably of great importance.

[0021] Electrohydrostatic actuators are used according to the state of the art primarily for a backup solution. These are planned in future aircraft architectures by many aircraft manufacturers for primary operation. The endurance requirements for these future applications are correspondingly high. Solutions described in the state of the art are not suitable for these long-term uses and the optimization of the operating conditions is of great importance.

[0022] In this context, the present invention aims to improve an above-mentioned system, in particular with regard to wear resistance and / or long-term operational capability.

[0023] This objective is achieved by the system with a pump and an actuator, characterized in that the system has a circuit selector, which is connected to the pump and the actuator.

[0024] Consequently, it is provided according to the invention that the system has a circuit selector, which is connected to the pump and to the actuator.

[0025] The system is preferably intended for use in an aircraft.

[0026] Preferably, at least one connection of the pump is connected to at least one connection of the circuit selector and at least one connection of the actuator is connected to at least one connection of the circuit selector.

[0027] The circuit selector may be arranged in one unit or in several distributed units. For example, the circuit selector may comprise several valves and / or in particular adjustable throttle systems.

[0028] The system can be arranged in a unit, so for example can form an electrohydraulic or electrohydrostatic actuator or can be arranged in a distributed manner in different units.

[0029] The system preferably has a particularly adjustable throttle system, which allows pressure-dependent and / or adjustable throttle. The adjustable throttle system preferably makes an adjustable throttle function possible.

[0030] The pump is preferably a hydraulic pump and / or an electric motor pump. The actuator is preferably a single-acting or double-acting hydraulic cylinder. The circuit selector is preferably a hydraulic circuit selector.

[0031] Preferably, the system has one or more pumps, in particular electrohydrostatic electric motor pumps, which can actuate one or more consumers, in particular actuators.

[0032] Preferably, the pump is a bi-directional electric motor pump and / or can control the movement of the actuator by discharging fluid in one or the other direction.

[0033] It is preferably provided that the circuit selector has two or three connections and / or two or three switching positions.

[0034] The circuit selector is preferably a 3 / 3-way valve. It is also conceivable that the circuit selector is a 2 / 2-way valve, particularly for a system with a single-acting actuator.

[0035] It is preferably provided that the circuit selector has a switching position, in which a through flow is made possible between one connection of the actuator and the pump and / or a switching position, in which a through flow is made possible between another connection of the actuator and the pump, and / or a switching position, in which a through flow is prevented or hindered through the circuit selector.

[0036] It is preferably provided that the system has one or more adjustable throttle systems and / or that the circuit selector is designed in such a way that one, two or more switching positions of the circuit selector have an adjustable throttle system, by which in particular a volume flow and / or a pressure loss of a fluid flowing through the circuit selector can be adjusted.

[0037] Preferably, the acceleration and / or the speed or actuation rate of the actuator may be regulated by means of an adjustable throttling system, in particular for operation of the system in an input load mode.

[0038] The adjustable throttle system may preferably be set to a "zero" throttle, wherein no through flow occurs through the throttle system.

[0039] The adjustable throttle system can be set in a neutral position also other than "zero", so that a through flow can take place through the throttle system.

[0040] It is preferably provided that the circuit selector has an adjustable slider and / or the adjustable throttle system is made possible by means of the adjustable slider.

[0041] It is preferably provided that the slider is designed in such a way that a stroke of the slider can be adjusted by means of the pump, in particular by means of a pressure generated by the pump.

[0042] It is preferably provided that the circuit selector is designed in such a way that the circuit selector is controlled by means of a control device and / or by means of a pump, in particular by means of a pressure generated by the pump.

[0043] The amplitude of the throttling by the adjustable throttling system is preferably defined passively by a setting pressure of a pump.

[0044] Preferably, the amplitude of the throttle can also be actively adjusted by means of a control device, wherein a pump pressure and / or a direction of rotation of the pump can serve as an input variable for the control device.

[0045] It is preferably provided that the system has, in particular between the connections of the actuator, a circuit selector and / or a leakage system.

[0046] Preferably, the chambers of one or more actuators may be connected via a circuit selector.

[0047] Preferably, the system has, in particular between connections of the actuator, a throttle valve and / or a leakage system.

[0048] The system is provided to have lines, check valves and / or a reservoir.

[0049] It is preferably provided that the circuit selector has, in particular in a switching position, in which a through flow through the circuit selector is prevented or hindered, a negative overlap.

[0050] Preferably, "underlap" is provided in a switching position of the circuit selector, in which the circuit selector prevents or impedes throughflow through the circuit selector.

[0051] It is preferably provided that the system has cables, non-return valves and / or a reservoir.

[0052] The present invention also relates to an aircraft, in particular an airplane, with a system according to the invention.

[0053] It is preferably provided that the method has the following step: - the control of a circuit selector by means of a pump and / or a control device.

[0054] It is preferably provided that the method has the following steps: - the movement of an actuator with a direction of movement in a load direction of a load, - the control of a circuit selector by means of a control device and / or a pump and / or the throttling of a flow passing through the circuit selector.

[0055] It is preferably provided that the throttling is carried out as a function of a pressure or proportional to it, in particular of a pump.

[0056] Preferably, the electric motor pump of an electrohydrostatic actuator is unloaded during operation in a stop mode and / or in an input load mode. In the stop mode, the electric motor pump is preferably completely unloaded. In the input load mode, the suction side of the electric motor pump is preferably not subjected to the action of pressure and / or the electric motor pump is not operated in a regenerative mode.

[0057] Preferably, the present invention results in a positive impact on both the life and the design of the electric motor pump.

[0058] Preferably, the demands placed on an electric motor pump when operating in a stop mode and / or in an input load mode are reduced.

[0059] Preferably, the pressure and suction sides of the pump alternate depending on the direction of rotation of the pump.

[0060] Preferably, the pump is discharged during operation of the system in a stop mode, i.e. upon stopping a load by the actuator. Preferably, the pressure is locked following an external load.

[0061] Preferably, the pump does not operate during operation of the system in an input load mode, i.e., for example, in the case of "Aiding Loads" in a regenerative mode. Preferably, the hydraulic energy is destroyed during operation of the system in an input load mode in an adjustable throttle system and not exclusively in a "chopper" resistor of a power electronics of an electric drive, in particular of an electric motor. Preferably, the suction side of the pump is not subjected to the action of pressure during operation of the system in an input load mode.

[0062] Preferably the throttling is carried out independently of a pressure or proportionally thereto, in particular from a pump.

[0063] Other advantages, characteristics and effects of the present invention result from the following description of preferred embodiments with reference to the figures, in which identical or similar components are designated by the same reference number. It can be seen there: [Fig.l], [Fig.2], [Fig.3], [Fig.4] and [[Fig.5]]: schematic electrical plans of an embodiment of a system according to the invention; [Fig.6]: a schematic electrical plan of a circuit selector of an embodiment of a system according to the invention; [Fig.7], [Fig.8] and [Fig.9]: sections of a circuit selector of an embodiment of a system according to the invention; [Fig.10], [Fig.11], [Fig.12] and [Fig.13]: schematic electrical plans of an embodiment of a system according to the invention; [Fig.14], [Fig.15], [Fig.16] and [[Fig.17]]: schematic electrical plans of an embodiment of a system known from the state of the art.

[0064] Figures 1 to 5 respectively illustrate a system with an electric motor 1, a pump 2, which together form an electric motor pump, two non-return valves in the form of pressure directional valves 3, an actuator 4, a circuit selector 5, two non-return 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 cables.

[0065] When operating the system of Figures 1 and 2 in a counter-load or "opposing loads" mode, an external load acts on the actuator 4 in a load direction L, and the movement direction M of the actuator is opposite to the load direction L, as illustrated by the thick arrows with the reference letters M and L in Figures 1 and 2. The pump 2 delivers fluid in a pump direction P, as illustrated in Figures 1 and 2 by the thick arrow with the reference letter P. Thus, the cable sections illustrated in bold in Figures 1 and 2 are subjected to the action of pressure, in particular between the actuator 4 and the pump outlet or the pressure side of the pump 2. The cable sections not illustrated in bold in Figures 1 and 2 are not subjected to the action of pressure.The pressure generated by the pump 2 at the pump outlet is used to switch the circuit selector 5 into a switching position, in which medium can flow from the actuator 4 through the circuit selector 5 towards the respective suction side of the pump 2. Depending on the load direction L or the rotational direction of the pump 2, the circuit selector 5 is thus automatically switched by the pressure-applied cables into the appropriate switching position, as can be seen from Figures 1 and 2. The suction side of the pump 2 or the pump inlet is not / is not pressure-applied. The pump outlet is pressure-applied.

[0066] Figures 1 and 2 illustrate states during operation of the system in a counter-load mode, in which the actuator 4 or the pump 2 are moved in the movement direction M against a load direction L, Figures 1 and 2 being distinguished by the movement direction M and the load direction L.

[0067] Figures 3 and 4 illustrate states during operation of the system in a stop mode, in which the actuator 4 or the pump 2 are not moved, Figures 3 and 4 being distinguished by the load direction L.

[0068] When operating the system of Figures 3 and 4 in a stop mode, the circuit selector 5 is in a central position as the off position. switching, the actuator 4 being fluidically separated from the pump return or inlet or in which a through flow through the circuit selector is prevented or impeded. The pressure resulting from the external load is blocked between the actuator 4 and the circuit selector 5, and the pump 2 is unloaded.

[0069] Since the pump 2 is unloaded, there is no wear between the pump parts. The electric motor 1 is also not supplied with current, so that overheating problems are eliminated. This takes place independently of the load direction L, in which the external load is applied. The cable sections shown in bold in Figures 3 and 4 are subjected to the action of pressure. The cable sections not shown in bold in Figures 3 and 4 are not subjected to the action of pressure.

[0070] [Fig. 5] illustrates states during operation of the system in an input load mode, in which the actuator 4 is moved in a movement direction M that points in the same direction as the load direction L. The movement direction M of the actuator 4 and the load direction L of the external load have the same direction as represented by the thick arrows with the reference letters M and L in [Fig. 5]. The pump 2 delivers fluid in the pumping direction P as represented in [Fig. 5] by the thick arrow with the reference letter P. The cable sections shown in bold in [Fig. 5] are subject to the action of pressure. The cable sections not shown in bold in [Fig. 5] are not subject to the action of pressure.

[0071] An external load acts in the input load mode on the actuator 4 in a load direction L, and the displacement direction M of the actuator 4 is the same as the load direction L of the external load.

[0072] Preferably, however, no single circuit selector as in Figures 1 to 5 is used when operating the system in an input load mode. The pressure loss on the pressure-acting side leading to the return or leading to the pump inlet adapts to the external load and the actuation rate of the actuator 4 preferably to ensure that no pressure remains on the suction side of the pump 2 and that the latter does not operate in a regenerative mode.

[0073] In the presence of high external loads and low actuation rates of the actuator, the pressure loss is preferably large. In the case of low external loads and high actuation rates of the actuator, the pressure loss is preferably low.

[0074] [Fig. 6] shows a circuit selector that meets these requirements. The circuit selector of [Fig. 6] is preferably controlled by the pressure on the pump outlet PA defined according to the direction of rotation of the pump. One connection of the circuit selector leads to the pump inlet PE. The other two connections of the selector circuit leads to the AA actuator connections, one AA connection being provided for one chamber.

[0075] The upper and lower switching positions of the circuit selector switch of [Fig. 6], which are not the central position, in which the circuit selector switch of [Fig. 6] brings the system into a stop mode, are respectively designed in such a way that a volume flow and / or a pressure loss through the circuit selector switch are set in the respective switching position proportional to the pressure of the pump outlet PA, thus a throttle is respectively set.

[0076] For this purpose, the circuit selector preferably has a slider S prestressed by a slider spring F and a sliding sleeve H or a group of sliders, the stroke of the slider S being controlled by the pressure of the pump outlet PA as shown in Figures 7 to 9.

[0077] As can be seen from [Fig. 7], the circuit selector or slider S blocks, in cooperation with the sliding sleeve H, the through flow between an actuator connection AA and the pump suction side or a pump inlet PE to the extent that no pressure is applied to the pump outlet PA, which acts on the slider S, as suggested in [Fig. 7] by the dotted lines, which suggest the absence of pressure on the pump outlet PA and the absence of through flow between the actuator connection AA and the pump suction side or the pump inlet PE. [Fig. 7] shows a position of the slider S, for which no through flow through the connections AA and PE illustrated in [Fig. 7] takes place.

[0078] The stroke of the slider S relative to the sliding sleeve H defines the flow surface passing through from the connection of the actuator AA to the return or pump inlet PE.

[0079] The slider S is pre-stressed by means of the spring F. The pressure on the pump outlet PA acts on the slider S and then on the spring F. An increase in the pressure on the pump outlet PA actuates the slider S inside the sliding sleeve H and enlarges the through-flow area from the actuator connection AA to the return or pump inlet PE as shown in [Fig. 8]. The increased pressure on the pump outlet PA and the enlarged through-flow area, which leads to a through-flow between the actuator connection AA and the pump suction side or pump inlet PE, are suggested by the solid arrows in [Fig. 8]. A small through-flow area causes a high pressure drop. [Fig. 8] shows a stroke of the slider S in the presence of a high external load and / or a low actuator actuation rate.

[0080] The stroke of the slider S in the presence of an increased pressure compared to the state illustrated in [Fig. 8] on the pump outlet PA is shown in [Fig. 9]. The stroke of the slider S is thus greater than in [Fig. 8], which results in an enlarged through-flow area compared to [Fig. 8]. The again increased pressure on the pump outlet PA and the again enlarged through-flow area, which results in an increased through-flow between the actuator connection AA and the suction side of the pump or the pump inlet PE are suggested by the bold arrows in [Fig. 9]. A high through-flow area results in a lower pressure drop. [Fig. 9] shows a stroke of the slider S in the presence of a low external load and / or in particular a high actuation rate of the actuator.

[0081] [Fig. 10] essentially represents the system of [Fig. 5] with a differently configured circuit selector 5. The circuit selector 5 of [Fig. 10] has an adjustable throttle in the lower switching position of [Fig. 10]. This switching position is active in [Fig. 10].

[0082] [Fig. 10] illustrates states during operation of the system in an input load mode, in which the actuator 4 is moved in a movement direction M, which points in the same direction as the load direction L. The movement direction M of the actuator 4 and the load direction L of the external load have the same direction, as shown in [Fig. 10] by the thick arrows with the reference letters M and L. The pump 2 delivers fluid in the pumping direction P, as shown in [Fig. 10] by the thick arrow with the reference letter P. The cable sections shown in bold in [Fig. 10] are subjected to the action of pressure. The cable sections not shown in bold in [Fig. 10] are not subjected to the action of pressure. The cable sections shown in dotted lines in [Fig.10] are subjected to the action of a throttled pressure, which is generated by the switching position with the adjustable throttle system of the circuit selector 5 from the pressure, which is driven by the external load.

[0083] A state as in [Fig. 10] is entailed from a system unconstrained by an external load and at a standstill, in which the circuit selector 5 is in the central position, thus in a position in which a through flow through the circuit selector is prevented or impeded, as follows.

[0084] First, an external load is applied to the actuator 4. The pressure thus caused is enclosed in the cable section between the actuator 4, the non-return valve 3 and in the circuit selector 5 switched to the central position. The actuator 4 cannot move.

[0085] Then, a movement direction M of the actuator 4 in the same direction as the external load is applied, specified or commanded. The pump 2 discharges correspondingly in the pumping direction P.

[0086] Since the actuator 4 cannot move initially due to the central position of the circuit selector 5, a pressure builds up on the pump outlet, which enables the valve selector 5 to be actuated. The slide in the slide group of the circuit selector 5 begins to move and the circuit selector begins to move into the switching position with the adjustable throttle system. A fluid connection between the actuator 4 and the suction side of the pump or the pump inlet PE is produced, whereby a through flow is made possible through the circuit selector.

[0087] Thus, the actuator 4 can now move in the direction of movement M.

[0088] The rate at which the actuator 4 moves stabilizes for the same rate at which the pump 2 delivers.

[0089] If the actuator 4 were to move with a lower rate than the rate with which the pump 2 delivers, a higher pressure is built up on the pump outlet. The slider inside the slider group of the circuit selector 5 increases its stroke, the through flow area increases, the pressure is therefore less throttled by the active switching position on [Fig. 10] of the circuit selector, and the actuator 4 is accelerated due to the external load.

[0090] If the actuator 4 were to move with a higher rate than the rate with which the pump 2 delivers, the pressure drops at the pump outlet. The slider inside the slider group of the circuit selector 5 reduces its stroke, the through flow area is reduced, the pressure is therefore further throttled by the active switching position on [Fig. 10] of the circuit selector, and the actuator 4 is slowed down by the high pressure.

[0091] The pressure on the pump outlet controls the stroke of the slide or the throttle of the circuit selector 5 and can therefore be referred to as control pressure or setting pressure. The pressure on the pump outlet indirectly defines the pressure loss of the actuator 4 to return to the suction side of the pump 2.

[0092] The hydraulic energy following the external load is destroyed by the loss of pressure on the circuit selector 5. The suction side of the pump 2 is then not subjected to the action of a pressure so that the pump 2 or the electric motor 1 do not operate in a regenerative mode.

[0093] The pump 2 is preferably fully discharged in the input load mode. The lubricating film forming between the moving parts of the pump 2 spares the pump 2 and promotes longevity.

[0094] Since the pump 2 or the electric motor 1 do not operate in a regenerative mode, the hydraulic energy is not converted into electrical energy, which would have to be destroyed. This is positive for the design of the electric drive or the electric motor 1 and results in a lower weight of the electric motor 1 and / or the system.

[0095] The circuit selector with an adjustable throttle in at least one switching position allows for improved system operation in an input load mode.

[0096] [Fig. 11] shows a state during operation of the system in an input load mode, with the direction of movement M and the load direction L extending oppositely with respect to [Fig. 10]. The valve selector 5 of [Fig. 11] thus has an adjustable throttle in the upper switching position of [Fig. 11]. The states shown in [Fig. 11] in the system are provided that the direction of movement L and the load direction L are reversed, by analogy with the states shown in [Fig. 10].

[0097] The circuit selector 5 can have an adjustable throttle system only in the upper or lower switching position in FIGS. 10 and 11 or in both switching positions.

[0098] Operation in the input load mode preferably takes place completely passively without the need for a control device.

[0099] [Fig. 12] represents a system with an electrical control device 8, which controls the circuit selector 5.

[0100] The control or switching of the circuit selector 5 is not ensured passively by the pressure of the pump 2 in [Fig. 12], but actively by a control device 8. This can take place using an electronic or electrical unit with the aid of parameters such as a pressure in a line or a direction of rotation of the pump 2. A combination of control of the circuit selector by the pump 2 and a control device 8 is, however, also conceivable.

[0101] It can be imagined that in some applications a reduction of stiffness is necessary in the system. This can be implemented by providing a negative overlap or underlap in the circuit selector in the center position or in the nominal unswitched position. A small internal leakage between the actuator chambers can also be provided. In an operation of the system in a stop mode, the electric motor pump will have to discharge a little in due to underlap and / or leakage to hold the actuator in position. When operating the system in an input load mode, it is possible due to leakage depending on the size of the external load, that the pump and actuator move in opposite directions. However, pressure on the suction side of the pump does not build up so that the electric motor pump does not operate in a regenerative mode.

[0102] [Fig. 13] suggests the negative overlap in the central position of the circuit selector 5 by a dotted line. Similarly, the system has in [Fig. 13] a throttle valve 9, which acts as a leak, between the chambers of the actuator 4.

[0103] An advantage of the present invention is that when operating the system in a stop mode, the electric motor pump does not have to build up any pressure. The pressure resulting from the external load is trapped between the actuator, the non-return valve and the circuit selector. The pump is thus relieved, which has a positive impact on its service life.

[0104] An advantage of the present invention is that when operating the system in an input load mode, the electric motor pump does not operate in a regenerative mode. There is therefore no need to destroy the electrical energy from a generative operation of the electric motor pump into resistors, which has a positive impact on the design of the electric motor.

Claims

Claims

1. System with a pump (2) and an actuator (4), characterized in that the system has a circuit selector (5), which is connected to the pump (2) and to the actuator (4).

2. System according to claim 1, characterized in that the circuit selector (5) has two or three connections and / or two or three switching positions.

3. System according to claim 1 or 2, characterized in that the circuit selector (5) has a switching position, in which a through flow is made possible between one connection of the actuator (AA) and the pump (2), and / or a switching position, in which a through flow is made possible between another connection of the actuator (4) and the pump (2), and / or a switching position, in which a through flow is prevented or hindered by the circuit selector (5).

4. System according to any one of the preceding claims, characterized in that the system has one or more adjustable throttle systems, and / or the circuit selector is designed in such a way that one, two or more switching positions of the circuit selector have an adjustable throttle system, by which in particular a volume flow and / or a pressure loss of a fluid flowing through the circuit selector can be adjusted.

5. System according to claim 4, characterized in that the adjustable throttle systems are made possible by means of the adjustable slider.

6. System according to any one of the preceding claims, characterized in that the circuit selector has an adjustable slider (S).

7. System according to claim 6, characterized in that the slider (S) is designed in such a way that a stroke of the slider (S) can be adjusted by means of the pump (2), in particular by means of a pressure generated by the pump (2).

8. System according to any one of the preceding claims, characterized in that the circuit selector (5) is made so as to control the circuit selector (5) by means of a device control (8) and / or by means of the pump (2), in particular by means of a pressure generated by the pump (2).

9. System according to any one of the preceding claims, characterized in that the system has, in particular between connections of the actuator (4), a throttle valve (9) and / or a leakage system.

10. System according to any one of the preceding claims, characterized in that the circuit selector (5) has, in particular in a switching position, in which a through flow through the circuit selector (5) is prevented or hindered, a negative overlap.

11. System according to any one of the preceding claims, characterized in that the system has pipes, non-return valves and / or a reservoir.

12. Aircraft, in particular airplane, with a system according to any one of the preceding claims.

13. Method for operating a system according to any one of claims 1 to 11, characterized by the step of: - controlling a circuit selector (5) by means of a pump (2) and / or a control device (8).

14. Method according to claim 13, characterized by the steps of: - moving an actuator (4) with a direction of movement in a load direction of a load, - controlling a circuit selector (5) by means of a control device (8) and / or a pump (2) and / or throttling a flow through the circuit selector (5).

15. Method according to claim 14, characterized in that the throttling is carried out independently of a pressure or proportional to it, in particular of a pump (2).

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