Device

Abstract

1. Device 2. The invention relates to a device for providing a liquid, which is under a discharge pressure, to a consumer (12) which can be connected to the device via a connection (10), at least consisting of a retractable and extendable bellows (16) which separates two fluid chambers (18, 20) from one another within a device housing (22), of which at least the one fluid chamber (18) is designed as a liquid chamber and, arranged in the interior of the bellows (16), is connected in a liquid-conducting manner to the connection (10) for the consumer (12).

Description

[0001] device

[0002] The invention relates to a device for supplying a liquid under a delivery pressure to a consumer that can be connected to the device via a connection.

[0003] EP 3 657 026 A1 discloses a storage device, in particular in the form of a so-called bootstrap accumulator, which is connected to the suction side of a hydraulic supply pump or hydraulic pump, where the pump's inlet pressure is pre-charged. A control housing with a control piston is fluid-carrying and connected to the outlet side of the hydraulic pump, and thus to its high-pressure side. This control piston actuates a separating device in the form of a separating piston within a storage housing of the bootstrap accumulator, which separates two low-pressure chambers. One of these low-pressure chambers pre-charges the suction side of the hydraulic pump with its outlet pressure. In this way, cavitation on the hydraulic pump side is avoided.Furthermore, a hydraulic actuator is connected to the high-pressure or output side of the hydraulic pump. In aircraft, this actuator is used to control aircraft components such as parts of the control system, as well as various types of flaps, including airbrakes, spoilers, landing gear and engine flaps, and the aircraft's landing gear itself. This list is not exhaustive. On its output side, the hydraulic actuator is connected to the low-pressure side of the accumulator housing, from which the hydraulic pump is supplied with fluid at a preset pre-charge pressure.

[0004] Bootstrap accumulators regularly used in the prior art have a longitudinally movable separating piston in the low-pressure segment of the accumulator housing, which preloads the low-pressure side of the accumulator by pulling on the large-area separating piston with the annular area of ​​a comparatively smaller control piston of a control cylinder and very high system pressures, for example 3000 psi, on the high-pressure side and achieving a preload of, for example, 85 psi on the discharge side via the area transmission.

[0005] From the subsequently published DE 10 2023 001 778.7, a storage device, in particular a bootstrap, is known, comprising at least a storage housing and a separating device movably arranged therein, which separates two low-pressure chambers from each other within the storage housing, and a control housing in which at least partially a control piston is movably guided, which interacts with the separating device and separates a high-pressure chamber from at least one of the two low-pressure chambers in the storage housing.By having the separating device with a flexible jacket at least partially enclose the other of the two low-pressure chambers in the storage housing, the flexible jacket being formed by a retractable spring or bellows that is fluid-tight, fluid losses on the pre-stressed low-pressure side of the storage housing, formed by one of the low-pressure chambers, to the ambient side are prevented, thus eliminating the possibility of leaks. The fluid chamber enclosed by the bellows forms a gas side of the storage device and contains ambient air at ambient pressure.

[0006] Based on this prior art, the invention aims to further improve such storage devices while retaining their advantages. A storage device comprising all the features of claim 1 solves this problem.

[0007] The device according to claim 1 consists at least of a retractable bellows which separates two fluid spaces within a device housing, at least one of which is designed as a liquid space and is arranged inside the bellows and is connected to the connection for the consumer in a fluid-carrying manner.

[0008] Since the bellows, particularly in the form of a bellows, is arranged on the discharge side of the device housing (which is designed like a storage housing) facing the consumer, it is possible to operate the pre-tensioning device in at least two different operating modes. The pre-tensioning pressure can be set internally on the discharge side of the device via the other fluid chamber within the device housing, the pressure of which defines the discharge or pre-tensioning pressure in one fluid chamber accordingly. Alternatively, external pressure can be applied to the bellows from the outside in such a way that the discharge or pre-tensioning pressure it generates enables at least low-cavitation operation of a connected consumer, such as a hydraulic pump, which, depending on the application, can reach very high speeds, for example, in the range of 8000 rpm and more.Without the support provided by the predetermined discharge or pre-tension pressure of the device, such hydraulic pumps could not be put into operation without problems, especially not over long periods of operation.

[0009] In a preferred embodiment of the device according to the invention, the bellows, particularly in the form of a bellows, is sealed on one free end face by a control plate in a media-tight manner and on its other free end face in a media-tight manner by parts of the device housing. Preferably, the control plate is further guided longitudinally within the device housing via a guide, which has at least one passage for a permanent fluid connection between the additional fluid chamber and the outer circumferential side of the bellows. In this way, the possibility of transferring thermal energy between the two fluid chambers, particularly in the form of two fluid chambers, is created, similar to a heat exchanger.

[0010] It is preferably provided that the additional fluid chamber has an inlet and an outlet for a further fluid, in particular in the form of a liquid cooling medium, which flows through the additional fluid chamber at a predefinable velocity. During pre-tensioning operation for a consumer connected to the device, relevant waste heat is generated within it, which can be dissipated from the device by means of a cooling medium in the additional fluid chamber, particularly if the cooling fluid or cooling medium continuously traverses the additional fluid chamber from the inlet to the outlet of the device housing at a predefinable flow velocity and thus carries away the waste heat generated during the operation of the device.In this way, the waste heat from the device can also be used to heat the cooling medium, which can be particularly advantageous for aircraft whose kerosene fuel, especially at high altitudes, requires warming to ensure smooth engine operation. In a further preferred embodiment of the device according to the invention, a rod section extends longitudinally through the device housing, adjacent to and centrally located along a central axis, on an end wall of the device housing. When the bellows passes through, the rod section is pivotally connected at one end to the control plate, and in particular, rigidly connected to it.Preferably, the rod section is designed as a hollow rod and guided longitudinally within a housing casing, which incorporates at least parts of a length measuring system for determining the position of the control plate or bellows. In this way, the respective operating state of the device can be detected via the bellows position using a central control unit (CPU), preferably enabling control of the pressure and flow rate of the fluid in the wider fluid chamber of the device.

[0011] In a further preferred embodiment of the device according to the invention, the rod section, in the form of a hollow rod, forms a pressure-effective surface which, controlled by an external control pressure, causes the hollow rod to move within its associated housing casing in order to actively move the control plate along with the bellows. In this way, the discharge preload can be predetermined externally via the bellows over the fluid chamber, regardless of the pressure and fluid conditions in the rest of the fluid chamber, for example by connecting the device to an independent pressure supply unit.

[0012] In a further preferred embodiment of the device according to the invention, it is provided that, in a section viewed transversely to the longitudinal extent of components such as the device housing including the bellows and associated control plate, all components are non-circular, preferably oval or rectangular. In this way, the device can also be accommodated within confined spaces, such as those regularly found inside the wings of aircraft, which, in view of increasingly higher speeds, have a greater aspect ratio and a correspondingly reduced wing thickness.

[0013] The invention also relates to a method for operating a device as described above, wherein the additional fluid chamber is supplied with the cooling medium, such as kerosene, via a separate supply circuit. In this way, the cooling medium can continuously dissipate the heat generated during operation of the device and simultaneously heat the cooling medium, such as kerosene. Alternatively, the additional fluid chamber can also be closed and, for example, contain a working gas, such as nitrogen gas, at a predetermined pressure.

[0014] In a further embodiment of the method, it is preferably provided that one fluid chamber is connected via the connection in the device housing to the suction side of a hydraulic pump, which is the fluid-carrying consumer. In this way, particularly at very high hydraulic pump speeds, such as those regularly encountered in the operation of aircraft for their hydraulic supply, cavities in the hydraulic pump, which in the worst case can lead to its failure, can be avoided. In this respect, the fluid chamber carries a hydraulic fluid of the type used in aviation, particularly in aircraft.

[0015] The device according to the invention, along with the method for its operation, will now be explained in more detail with reference to two exemplary embodiments shown in the drawing. The drawings are shown in a general and not to-scale representation.

[0016] Figures 1 and 2 each show, in the form of a longitudinal section view, the essential components of the supply device with oval and rectangular housing cross-sections, respectively.

[0017] Figure 1 shows a device for supplying a liquid at a discharge pressure to a consumer 12, which can be connected to the device via a connection, typically in the form of a conventional hydraulic pump 14, which is shown in Figure 1 as a black box. The device according to Figure 1 has a retractable bellows, in particular in the form of a bellows 16, which separates two fluid chambers 18, 20 from each other within a device housing 22, at least one of which, 18, is designed as a liquid chamber and is arranged inside the bellows 16 and is in permanent fluid-carrying communication with the connection 10 for the consumer 12 via a fluid line, in particular in the form of a hydraulic line 24.Between the connection 10 of the device housing 22 and the consumer 12, usually in the form of the hydraulic pump 14, a fluid supply line 28 is connected in a branch 26, which supplies the hydraulic pump 14 with fluid, such as hydraulic medium from a storage tank (not shown) on the inlet side, which is fed into a hydraulic supply circuit 30 on the outlet side of the hydraulic pump 14 at a predefinable discharge pressure, which is only partially shown at the beginning in Figure 1 and to which hydraulic consumers, such as actuators and the like, are connected in the usual way.

[0018] Hydraulic pumps 14 of this type sometimes operate at very high speeds, for example 8000 rpm and more, so that cavitation frequently occurs on the suction side of such pumps 14. To prevent this, the device shown in Figure 1 is provided, which pre-charges the fluid pressure on the inlet side of the hydraulic pump 14 in such a way that no cavitation occurs even when the pump 14 starts up dry from a standstill or unactuated state, and in particular, the hydraulic pump 14 immediately fulfills its task of feeding fluid at a predefined pressure into the supply circuit 30. In this respect, the device shown in Figure 1 functions as a so-called bootstrap. It is understood that instead of the hydraulic pump 14, another hydraulic fluid consumer 12, not shown in further detail, can also be used, which preferably requires a fluid with a predefined pre-charge pressure on its inlet side.

[0019] The bellows 16 is sealed on one free end face by a control plate 32 in a media-tight manner, and on its other free end face by parts 34 of the device housing 22, which form a cover part 36 for closing a pot-shaped container receptacle 38 with a thin-walled housing wall 40 along the inside of which the control plate 32 is longitudinally guided. In the opposite direction to the cover part 36, the container receptacle 38 is integrally bounded by a closing wall 42, the wall thickness of which is significantly greater than that of the housing wall 40. A central closing opening 44 provided in the closing wall 42 is sealed media-tight by a closure part (not shown).The control plate 32 is longitudinally movably guided within the device housing 22 via an oval annular guide 46. This guide is bounded by passages (not shown) on the outer circumference, which can also allow for leakage flow. These passages provide a permanent fluid connection between the second fluid chamber 20 and the outer circumferential side 48 of the bellows 16, formed by the outer surface of the individual bellows folds of the bellows 16. Depending on the extension or retraction position of the bellows 16, a second fluid chamber 50 is created, the capacity of which varies. This second fluid chamber 50 is bounded radially on the outside by the inner surface of the housing wall 40 and at one end by the cover part 36. As can be seen from Figure 1, the second fluid chamber 20 has an inlet 52 and an outlet 54 for a further fluid, in particular a cooling medium, which flows through the second fluid chamber 20 at a predetermined velocity.In this specific case, the cooling medium is to consist of kerosene, which is intended as fuel for aircraft engines. The kerosene is drawn from an aircraft fuel tank 58, located at least partially within the aircraft wings, by means of a conventional fuel pump 56 provided for this purpose. Via a conventional fuel line 60, the kerosene, at a predetermined delivery pressure provided by the fuel pump 56, flows through the inlet 52 into the further fluid chamber 20 and from there via the outlet 54 on the housing side into a return line 64 equipped with an adjustable throttle 62, back into the fuel tank 58.The discharge process in the return line 64 can be monitored by means of a conventional pressure sensor 66, which forwards its measured values ​​to a central control unit (CPU) not shown, which in turn controls a drive (not shown) of the fuel pump 56 in such a way that its discharge pressure can be adjusted within a predefinable range and thus the prevailing pressure in the second or further fluid chamber 20.

[0020] The resulting fuel delivery pressure is then transmitted via the control plate 32 to the first fluid chamber 18, or fluid chamber containing the hydraulic medium. Thus, by means of the bellows 16, the control plate 32, and the fluid chambers 18 and 20 defined by them, a kind of pressure intensifier is realized within the device housing 22. This means that, depending on the kerosene pressure in the second fluid chamber 20, a delivery or pre-charge pressure is inevitably established in the first fluid chamber 18, which is transmitted via the connection 10 to the supply side of the consumer 12, or to the suction side of the hydraulic pump 14. Any minor fluctuations in the pressure curve that may occur due to the operation of the fuel pump 56 are dampened by the bellows 16, so that an essentially constant delivery pressure is achieved on the pre-charge side of the device.

[0021] During operation of the device, the provision of the pre-charge pressure for the receiver 12 results in heating, particularly in the form of the hydraulic fluid within the bellows 16. This allows heat energy to be transferred via the bellows wall to the third fluid chamber 50 containing the kerosene. Since this third fluid chamber 50 is in fluid-carrying communication with the second fluid chamber 20, the heat input is transferred to the kerosene, which continuously flows from the inlet 52 to the outlet 54 through the second fluid chamber 20. In this way, "cold" kerosene can be warmed before injection into the aircraft's engines, which is generally desirable as it helps to improve engine performance.

[0022] As can be further seen from Figure 1, a central opening 68, which has a guide bushing 70 with corresponding seals, is penetrated by a hollow cylindrical rod section 72. This rod section is cut open on one free end face and is closed on the other free end face by the control plate 32, to which it is firmly connected. In this respect, the hollow cylindrical rod section 72 forms a protective element and a guide for a length measuring system 74, for example in the form of an LVDT system, the design of which is common, so that it will not be discussed in more detail here.In this case, parts of the LVDT measuring system are housed in a cover 76 of a hollow cylindrical housing 78, which is placed on the free end face of the cover part 36 and firmly connected to it, encompasses the hollow cylindrical rod part 72 with a predefinable radial distance, which is arranged longitudinally movable in the guide bushing 70 and transmits the respective extension and retraction positions of the bellows 16 to the LVDT length measuring system 74 via the control plate 32. If the position of the bellows 16, whether extended or retracted, results in a preload pressure for the receiver 12 at the connection 10 that is too low or too high, the fuel pump 56 is increased or its output is reduced, so that the preload output pressure can be readjusted via the pressure control in the second or further fluid chamber 20 and kept constant as required via the first fluid chamber 18.This has no equivalent in the state of the art.

[0023] Instead of supplying fuel, it is also possible, in principle, to introduce a working gas, such as nitrogen gas, at a predetermined pressure into the further fluid chamber 20 as a reservoir by closing off the inlet 52 and outlet 54. This can be done, for example, via the closable central middle or end opening 44, so that the delivery or pre-charge pressure at the consumer 12 can be predetermined via the gas-side supply pressure. However, in this case, the pre-charge pressure at the connection 10 for the consumer 12 can only be adjusted to a limited extent, so the continuous flow variant with kerosene according to Figure 1 is preferable.

[0024] A special feature of the solution according to the invention, as shown in Figure 1, is that the device housing 22 is non-circular in cross-section, in particular oval, so that it can be easily installed in confined spaces, such as those found, for example, in aircraft wings. To match the oval cross-section of the housing, the control plate 32 and the bellows 16 are also adapted to the inner contour of the housing and, in particular, are likewise oval in shape. The embodiment shown in Figure 2 largely corresponds to the embodiment shown in Figure 1, so that the corresponding components are represented with the same reference numerals as for the first embodiment shown in Figure 1, and the modified embodiment shown in Figure 2 is only explained insofar as it differs substantially from the preceding embodiment.Accordingly, a different housing shape has been chosen for the device according to Figure 2, this time in the form of a rectangular cross-section. This opens up another possibility, depending on the available space, of accommodating the device according to Figure 2 with a correspondingly adapted cross-sectional shape – rectangular instead of oval. Otherwise, the descriptions given for Figure 1 also apply to the device according to Figure 2.

[0025] Instead of the fluid-kerosene inlet 80 shown in Figure 1, the second fluid chamber 20 is connected to the environment via the two openings 80, so that the fluid chamber 20 is largely at ambient pressure at all times. A further modification, as shown in Figure 2, is that an annular widening 82 with sealing and guide bands 84 is provided at the free end of the hollow rod section 72. This widening seals the environment against a cylindrical cavity 86, which is formed by the radial distance between the outer circumference of the hollow cylindrical rod section 72 and the inner surface of the hollow cylindrical housing 78. Viewed from Figure 2, the housing 78 is sealed on its right end face by a lid (not shown), creating a media-tight seal.The rod section 72 is in turn centrally articulated to the now rectangularly shaped control plate 32 and has at least one continuous transverse opening 88 in the area of ​​the articulation, which connects the interior of the bellows 16 with the received fluid chamber 18 to a further cavity 87, which is essentially formed from the respective inner volume of housing casing 78 and hollow cylindrical rod section 72.

[0026] The annular widening 82 of the rod section 72 forms a pressure-effective surface facing the interior of the cavity 86 and thus sealing off the cavity 86 at its outer edge in this area. Furthermore, an axial longitudinal bore 90 is provided in the plate-shaped cover section 36, the free end of which opens into a transverse bore 92 in the cover section 36. This transverse bore 92 is closed externally by a sealing screw 94. The transverse bore 92, which is channel-like, allows for the simple manufacturing of the media-carrying connection between the longitudinal bore 90 and the cavity 86. Opposite the widening 82, and thus on the other side, the cavity 86 is sealed by the sealing elements of the guide bushing 68 in a media-tight manner towards the first fluid chamber 18.The longitudinal bore 90 is connected to a pressure supply source (another hydraulic pump) not shown for a fluid supply under pressure, for example as part of a hydraulic supply circuit that introduces fluid at a predeterminable pressure via the longitudinal bore 90 into the cavity 86, which in this respect forms another pressure chamber with fluid.

[0027] The fluid introduced under pressure via the longitudinal bore 90 acts on the widening or pressure surface 82, causing the control plate 32 to settle into actuation positions, contrary to the inherent elasticity of the bellows 16 and the consumer pressure present in the first fluid chamber 18 via the connection 10 from the side of the receiver 12. This inevitably preloads the fluid chamber 18, which in turn transmits the preload pressure permanently to the receiver 12 via the connection 10. The receiver 12 is not shown again in Figure 2 for the sake of simplicity. In this way, the preload pressure at the receiver 12 can be regulated via an external pressure supply source at the longitudinal bore 90 of the device.Otherwise, pressure equalization between the fluid chamber 18 and the further cavity 87 on the inner circumferential side of the housing casing 78 is created via the continuous transverse openings 88 in the rod section 72, acting like a pendulum volume. The solution according to Figure 2 can also be equipped or retrofitted with a length measuring system according to Figure 1, for which purpose a measuring rod section 98 is already arranged centrally on the bottom side inside the hollow cylindrical rod section 72.

[0028] If necessary, both functional principles can be combined according to Figures 1 and 2, so that the preload pressure for the consumer 12 can be specified both via a fluid pressure in the further fluid space 20 and via the external pressure in the cavity 86 of the rod guide 72, 78.

Claims

1. Patent claims 1. Device for supplying a liquid under a discharge pressure to a consumer (12) which can be connected to the device via a connection (10), at least consisting of a retractable bellows (16) which separates two fluid spaces (18, 20) within a device housing (22) from each other, at least one of which fluid space (18) is designed as a liquid space and is arranged inside the bellows (16) and is in fluid-carrying contact with the connection (10) for the consumer (12).

2. Device according to claim 1, characterized in that the bellows (16), in particular in the form of a bellows, is sealed media-tight on one free end face by a control plate (32) and on its other free end face by parts (34) of the device housing (22).

3. Device according to claim 1 or 2, characterized in that the control plate (32) is guided longitudinally via a guide (46) within the device housing (22), which has at least one passage for a permanent fluid connection of the further fluid space (20) with the outer circumferential side (48) of the bellows (16).

4. Device according to one of the preceding claims, characterized in that the further fluid chamber (46) has an inlet (52) and an outlet (54) for a further fluid, in particular in the form of a cooling medium, which flows through the further fluid chamber (20) at a predeterminable speed.

5. Device according to one of the preceding claims, characterized in that a rod part (72) extends longitudinally through the device housing (22) on an end wall of the device housing (22) which is penetrated by the connection (10) for the receiver (12) and is located centrally along a central axis, and is pivotally connected to the control plate (32) at one end when passing through the bellows (16), in particular fixedly connected to it.

6. Device according to one of the preceding claims, characterized in that the rod part (72) is designed as a hollow rod and is guided longitudinally in a hollow cylindrical housing casing (78) which has at least parts of a length measuring system (74) for determining the position of the control plate (32) or the bellows (16).

7. Device according to one of the preceding claims, characterized in that the rod part (72) in the form of the hollow rod forms a pressure-effective surface (82) which, when controlled from the outside by a control pressure, leads to a movement of the hollow rod (72) in its associated housing casing (78) for the purpose of actively moving the control plate (32) together with the bellows (16).

8. Device according to one of the preceding claims, characterized in that in a section transverse to the longitudinal extent of components, such as the device housing (22) together with the bellows (16) and associated control plate (32), all components are non-circular, preferably oval or rectangular.

9. A method for operating a device according to one of the preceding claims, characterized in that the additional fluid chamber (20) is supplied with the cooling medium, such as kerosene, via its own supply circuit (56, 58, 60).

10. A method for operating a device according to one of the preceding claims, characterized in that the fluid chamber (18) inside the bellows (16), designed as a liquid chamber, is connected via the connection (10) in the device housing (22) to an intake side (24) of a hydraulic pump (14) as the consumer (12).

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