Accumulator device

Abstract

Accumulator device, particularly bootstrap, the accumulator device comprising at least an accumulator housing 10 and a separator 12 movably disposed within the accumulator housing 10 and separating two low-pressure chambers 14, 16 within the accumulator housing 10, wherein the accumulator device comprises a control housing 18 in which a control piston 20 is guided at least partially movably, the control piston 20 cooperating with the separator 12 to separate a high-pressure chamber 22 from at least one of the two low-pressure chambers 14, 16 within the accumulator housing 10, wherein the separator 12 at least partially surrounds the other low-pressure chamber 16 of the two low-pressure chambers 14, 16 within the accumulator housing 10 with a flexible casing 26.

Description

Technical Field

[0001] The present invention relates to an accumulator device, particularly a bootstrap accumulator, which consists of at least an accumulator housing and a separating device that is movably arranged within the accumulator housing and separates two low-pressure chambers within the accumulator housing. The accumulator device includes a control housing in which a control piston is at least partially movably guided. The control piston cooperates with the separating device to separate a high-pressure chamber from at least one of the two low-pressure chambers within the accumulator housing.

Background Art

[0002] An accumulator device, also known as a bootstrap accumulator in technical terms, is integrated into a hydraulic system to ensure a sufficient fluid supply to the suction side of a hydraulic pump and apply a low pressure to the associated suction pipe. The bootstrap accumulator is automatically set under a predefined fluid pressure and ensures a fluid supply without air, particularly in a closed hydraulic circuit. The bootstrap accumulator operates smoothly regardless of environmental conditions such as temperature, atmospheric pressure, acceleration force, and load. Furthermore, it keeps the boost pressure constant regardless of the filling status of the system. Moreover, such an accumulator device can be manufactured cost-effectively and requires little maintenance over a long period, so it has become established in the aviation field, especially for at least larger aircraft.

[0003] Thus, Patent Document 1 (European Patent Application Publication No. 3657026) discloses a general accumulator device, particularly a bootstrap accumulator, which preloads the input pressure of a hydraulic supply pump on its suction side, and a control housing with a control piston is connected in a fluid transport manner to the outlet side of the hydraulic pump, and therefore to its high-pressure side, and operates a separation device in the form of a separation piston within the accumulator housing of the bootstrap accumulator, which separates two low-pressure chambers from each other, one of which preloads the suction side of the hydraulic pump with its output pressure. This prevents cavitation on the pump side.

[0004] Furthermore, at least one hydraulic actuator is connected to the high-pressure or output side of the hydraulic pump, which the aircraft uses to actuate aircraft components such as steering gear parts, air brakes, wing flaps, spoilers, gear doors, engine doors, and all kinds of flaps such as landing gear. However, this list is not exhaustive. The hydraulic actuators used are alternately connected on their output side to the low-pressure side of the accumulator housing, from which fluid is supplied to the hydraulic pump at a preset pre-pressure on the input side.

[0005] In known solutions, a hydraulic accumulator is connected at the output side of the hydraulic pump to a high-pressure supply pipe leading to a high-pressure chamber in a control housing equipped with a control piston, which allows each actuator to continue to receive fluid at a predetermined operating pressure for emergency operation in the event of an overall energy supply failure.

[0006] To maintain the operating pressure in the intake pipe of a hydraulic pump, the accumulator housing is divided into two low-pressure chambers by a separation device in the form of a separation piston, so that, depending on the position of the separation piston, the first low-pressure chamber in the accumulator housing has ambient pressure, and the other low-pressure chamber in the accumulator housing provides a preload pressure for the hydraulic supply source, particularly in the form of a hydraulic pump.

[0007] Bootstrap accumulators routinely used in the art have a separation piston in the low-pressure segment of the accumulator housing, which is positioned to be longitudinally movable within the accumulator housing and pre-pressures the low-pressure side of the separation piston. This large-area separation piston is pulled by the annular surface of the relatively small control piston of the control cylinder, resulting in a very high system pressure (e.g., about 20.7 MPa (3000 psi)) on the high-pressure side and pre-pressure (e.g., about 0.6 MPa (85 psi)) on the discharge side via area ratio. A standardly configured separation piston, as routinely used under hydraulic pressure, has a circumferential seal, usually in the form of at least one elastomer seal ring, on its outer circumference in relation to the opposing adjacent wall portions of the accumulator housing, which always leaves a thin film of liquid on the running surface during operation, due to leakage between the two low-pressure chambers of the accumulator housing. Furthermore, if dirt accumulates on the running surface of the accumulator housing due to normal wear, for example, there is a risk of damaging the seals and / or the running surface. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] European Patent Application Publication No. 3657026 [Overview of the project] [Problems that the invention aims to solve]

[0009] Based on this prior art, the present invention aims to improve known accumulator devices. [Means for solving the problem]

[0010] This problem is solved by an accumulator device having the features of claim 1 in whole. According to the present invention, the separation device at least partially encloses the other of two low-pressure chambers in an accumulator housing that generally has ambient pressure with a flexible casing, and further considering that the flexible casing is designed to be fluid-sealed, fluid loss to the periphery on the pre-pressurized low-pressure side of the accumulator housing formed by one of the low-pressure chambers is avoided. In this respect, no leakage occurs, and no damage occurs along the running surface of the accumulator housing by any possible particle abrasion.

[0011] In an accumulator device according to a preferred embodiment of the present invention, the flexible casing is provided to be formed from elastic bellows, preferably spring bellows or folded bellows, and particularly preferably from a metallic material. These bellows allow for a firm, medium-tight separation from the outside between the two low-pressure chambers within the accumulator housing of the accumulator device. Each bellows, particularly the metallic bellows, is positioned such that a fluid, particularly in the form of hydraulic fluid, is located between the bellows and the accumulator housing. This allows damping to be achieved by the bellows, as the fluid acts as a support between the folds of the bellows from the outside, especially in the event of shock loads and / or fluctuations.

[0012] The bellows section preferably extends between the guide piston and the end wall of the accumulator housing. The guide piston is positioned to move longitudinally to a flush edge end inside the accumulator housing, so that the guide piston stabilizes the bellows section at each of its folds, thus ensuring that unintended expansion or deformation of the bellows section is avoided.

[0013] In a particularly preferred embodiment of the accumulator device according to the present invention, a plate-shaped guide piston is firmly connected to a control piston, preferably designed as a tubular piston, which establishes at least fluid transport between the first low-pressure chamber of the accumulator housing and the housing chamber of the control housing. This equalizes the internal pressure between the storage cylinder and the control cylinder, enabling smooth operation. Preferably, other low-pressure chambers within the accumulator housing, surrounded or enclosed by a casing-like or bellows-like separator, have their own ambient pressures. In this way, the pre-pressure of adjacent and opposite first low-pressure chambers within the accumulator housing can be directly adjusted according to the pressure specifications from the control cylinder having its control piston. Preferably, this first low-pressure chamber within the accumulator housing has an intake connection point for connection to a supply pump to ensure pressure supply to the actuators, and a low-pressure return connection point to which the fluid generated from the output side of each actuator is returned to the low-pressure side of the accumulator housing containing the fluid.

[0014] Space-saving design is particularly achieved when a variable-capacity high-pressure chamber is sealed between the control piston and the control housing. In particular, the control housing can be directly connected axially to the accumulator housing.

[0015] In a preferred embodiment of the accumulator device according to the present invention, a control piston is provided to be connected to a first low-pressure chamber of the accumulator housing, with one of its several free-end regions being connected. In this way, a position measuring system can be housed within the control piston, particularly through the other free-end region of the control housing, and this position measuring system is used to monitor the position of each of the separators within the accumulator housing.

[0016] The accumulator housing is more preferably closed by a cover portion equipped with multiple valve seats for multiple valves, multiple filters, multiple sensors, and various fluid connection points. In this way, the essential components of the fluid control system for the hydraulic supply pump and the actuators connected thereto can be centrally housed in a single accumulator device.

[0017] The accumulator device according to the present invention will be described in more detail below using exemplary embodiments. The figures are for illustrative purposes only and are not to scale. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 shows a longitudinal section passing through the essential components of the accumulator device. [Figure 2] Figure 2 shows an example of a cover design that can be used for the accumulator device according to Figure 1. However, for simplicity, Figure 1 does not show all the components of the cover structure according to Figure 2. [Figure 3] Figure 3 shows the essential components of the actuator control system, including the accumulator device shown in Figures 1 and 2, in the form of a hydraulic circuit diagram. [Modes for carrying out the invention]

[0019] Figure 1 shows an accumulator device, also technically called a bootstrap or bootstrap accumulator, in a substantially longitudinal cross-section. This accumulator device has a cup-shaped accumulator housing 10 in which a separator 12 is movably disposed, the separator 12 spatially separating two low-pressure chambers 14, 16 within the accumulator housing 10, these low-pressure chambers 14, 16 can interact with each other to occupy different fluid volumes. Furthermore, a control housing 18 is provided, in which a control piston 20 is guided to move longitudinally and interact with the separator 12. In particular, the control piston 20 in the control housing 18 separates a high-pressure chamber 22 from a further low-pressure chamber 24 which, in the embodiment of Figure 1, is fluidically or medially connected to the first low-pressure chamber 14 within the accumulator housing 10. The separation device 12 has a fluid-impermeable, flexible casing 26 that at least partially encloses or surrounds one of the two low-pressure chambers 14, 16 within the accumulator housing. In this way, the casing 26 seals off the other fluid chamber 16 in a fluid-seal manner from another fluid chamber 36 formed from the inner circumference of the accumulator housing 10 and the adjacent opposite outer surface of the casing 26.

[0020] The flexible casing 26 consists of an elastic bellows in the form of a bellows with folds, and such a bellows is preferably made of a conventional metallic material. The bellows with folds 28 extends between the guide piston 30 and the front end wall 32 of the accumulator housing 10. The bellows with folds 28 is fixed at its free ends, on one side to the guide piston 30 and on the other side to the end wall 32, and is particularly firmly welded at these points. The end wall 32 has at least one opening 33, as a result of which the interior of the bellows 28 or another medium chamber or low-pressure chamber 16 has the ambient pressure. Also, a ventilation device (not shown) can be provided in the opening 33. The cylindrical guide piston 30 is plate-shaped and has on its outer circumference support and guide rings 34 with individual interruptions (details not shown), as a result of which, outside the casing 26, a fluid conveyance connection point is established between one of the low-pressure chambers 14 and the fluid chamber 36, and this connection point is delimited by the outer circumference of the bellows with folds 28 and the inner circumference 38 of the cylindrical accumulator housing 10.

[0021] As can be seen in FIG. 1, when the guide piston 30 moves in the left direction, this movement is possible until the individual folds of the bellows with folds 28 abut against each other, i.e., until they are in a collapsed state. In the opposite direction of the guide piston 30, i.e., in the advancing direction to the right, the individual folds of the bellows with folds 28 are separated, and accordingly, the volume of the other low-pressure chamber 16 in the accumulator housing 10 increases, while the volume of one of the low-pressure chambers 14 decreases equally, which leads to an increase in the pre-pressure.

[0022] The accumulator housing 10 is flush-closed with a cover part 40 through which a hollow cylindrical control housing 18 passes. The control housing 18 is fixed in a stationary state to the cover part 40 by means of corresponding fixing means such as snap and retaining rings. Further, the hollow cylindrical control housing 18 extends in the direction of the environment from a corresponding fixing point 42 on the cover part 40 having a pre-determinable projection remote from the accumulator housing 10. Further, the control housing 18 is hermetically sealed from the environment by a connection point 44, which is shown from the outside in the illustration according to FIG. 2 and is omitted in FIG. 1 for the sake of simplicity.

[0023] A control piston 20 designed as a tubular piston is guided longitudinally within the control housing 18. In this way, a fluid conveyance connection point is established between a first low-pressure chamber 14 within the accumulator housing 10 and a further low-pressure chamber 24 within the control housing 18 via the hollow cylindrical control piston 20. For this purpose, the control piston 20 is open in the direction of the pressure chamber 24 and is closed at its other free end, for example, by a plug 46. Further, in the region provided with this plug 46, the control piston 20 is penetrated by individual apertures 48, and these apertures are preferably grouped diametrically opposite one another around the longitudinal axis or the movement axis of the control piston 20. In this way, an internal fluid connection is created between the first low-pressure chamber 14 and the further low-pressure chamber 24 via the apertures 48 and the tubular piston-shaped control piston 20, and as a result, fluid exchange can be carried out between these chambers 14 and 24 in a variable volume manner. The exchange movement of the variable volume is damped by the apertures 48.

[0024] A control piston 20, which is longitudinally movable within the control housing 18, has a sealed package 50 (details not shown) on its outer circumference in the direction of a further low-pressure chamber 24, and similarly, the control piston 20 is guided in a sealed manner in the area of ​​a fixed point 42 within the cover portion 40 via a further sealed package 52. A high-pressure chamber 22 with variable volume extends between the two sealed packages 50, 52. For example, if the high-pressure action in the high-pressure chamber 22 increases compared to the low-pressure areas in chambers 14, 16, and 24, the volume of the high-pressure chamber 22 increases, and the control piston 20 moves to the right from the position shown in Figure 1 under the action of the pressure. However, when the pressure in the high-pressure chamber 22 is reduced, under the action of the low-pressure components 14, 16, and 24, the control piston 20 moves to the left as viewed from the direction in Figure 1, and the volume in the high-pressure chamber 22 decreases in a valve-controlled manner. In this case, the guide piston 30 of the separator 12 is carried along it. During movement to the right, the fluid volume in the low-pressure chamber 14 decreases, which results in an increase in pre-pressure.

[0025] The following section will describe in more detail the integration of the accumulator device shown in Figure 1 into the overall hydraulic or supply system, using the circuit diagram in Figure 3. The previous reference numbers related to the accumulator device are also used for the same components according to Figure 3, and the descriptions made so far also apply to the supply solution according to Figure 3.

[0026] Accordingly, the first low-pressure chamber 14 within the accumulator housing 10 has a suction connection point 54 for connecting a standard supply pump or hydraulic pump 56, which is shown symbolically only in Figure 3. For this purpose, a so-called suction pipe 58, which may have a very long length, is led from the suction connection point 54 to the inlet or suction side 60 of the hydraulic pump 56. This hydraulic pump is connected to the supply side 66 of an actuator 68 via its pressure or output side 62 and the pump or high-pressure pipe 64, and this actuator may consist of one or more hydraulically actuated cylinders, each of which can be used to control other components such as the aircraft's steering gear or actuated flaps or landing gear. This list is not exhaustive. On the output or outlet side 70, the actuator 68 is connected to a system return pipe 72, which leads to the first low-pressure chamber 14 within the accumulator housing 10 via a low-pressure side return connection point 74. Actuator control, usually in the form of a valve control device, for extending and retracting each actuator 68 or operating cylinder is common and will not be discussed in further detail here. In this regard, the actuator 68 is shown only at its inlet side 66 and outlet side 70.

[0027] As can be seen in Figure 3, the supply pipe 78, at branching point 76, leads into the pump or high-pressure pipe 64 and, like pipe 64, transports the high pressure or pump pressure of the hydraulic pump 56 to its output side 62. The corresponding supply pipe 78 leads into the high-pressure chamber 22 in the control housing 18 via connection point 79. Then, depending on the pressure in the high-pressure chamber 22 and the force or pressure balance between the high-pressure and low-pressure sides of the accumulator device, the control piston 20 is positioned in its respective position, as is the guide piston 30 connected to the control piston 20 in the separator device 12.

[0028] For simplicity of explanation, the folded bellows section 28 is not shown in detail in Figure 3; instead, for the purpose of detecting the position of the guide piston 30 of the separator 12, the position measuring system is symbolically represented by reference no. 80 in the form of a so-called LVDT system. However, it is preferable that the LVDT system be located within the free, hollow cross section of the control piston 20. Such a structure is known (Patent Document 1 (European Patent Application Publication No. 3657026)) and will not be discussed further here. Through intersection 82, an unspecified system pressure 84 is also led to the high-pressure side with the high-pressure chamber 22, which, through the corresponding connecting pipe 86, leads the pressure component to the connection point 79 of the accumulator device, where the pressure component originates from a standard hydraulic unspecified supply circuit. However, as shown in the illustration of Figure 3, if the introduction of the system pressure 84 to the connection point 79 via the connecting pipe 86 is omitted, in particular, the system and supply circuit will function accordingly. A pressure relief valve 88 is connected between the high-pressure side and the low-pressure side of the supply circuit, connecting the high-pressure side and the low-pressure side to a predetermined set pressure; in other words, for safety reasons, a pressure equalization connection is formed between the fluid pipe 72 and the fluid pipe 78.

[0029] A check valve 90 is also connected to a supply pipe or pump pressure pipe 78, which leads to the high-pressure side fluid filter 92. A branch pipe with a spring-loaded check valve 94, which opens in the direction of this pipe 78 and closes the first fluid connection point 114 in a fluid-sealing manner at the illustrated position, is connected between the check valve 90 and the high-pressure side fluid filter 92. Furthermore, a pressure sensor 96 is connected to the clean side of the filter 92 to monitor the high-pressure side. For example, for maintenance or inspection purposes, several grounding devices, not shown in detail, can be independently connected at the fluid connection point 114 having the spring-loaded check valve 94. Thus, a filter 98 having a bypass configuration is located on the low-pressure side of the supply circuit in the system return pipe 72, and this filter is connected via a branch to another spring-loaded check valve 100 in a manner that transports fluid, and this check valve forms a hydraulic fluid connection point 116 for grounding devices for the purpose of performing maintenance and monitoring activities, comparable to the solution having connection point 114.

[0030] Furthermore, a temperature sensor 102 is connected to a return pipe 72 leading directly to the low-pressure side inlet to the accumulator housing 10. Two vent valves 106 and 108 are connected to a further low-pressure pipe 104 leading to the first low-pressure chamber 14, of which vent valve 108 may have manual operation.

[0031] Ultimately, the overall configuration ensures that, regardless of the system conditions (pressure, temperature, acceleration, load, installation, etc.) and the length of the suction pipe 58, the hydraulic pump 56 always maintains a pre-pressure at its inlet or suction side 60. This pre-pressure from the low-pressure region of the accumulator housing 10 allows for the cavity-free and problem-free operation of the hydraulic pump 56, even after starting from a stopped state. This operating behavior applies to almost the entire length of the suction pipe 58 and also applies in cases of reduced engine power or complete engine failure due to malfunction or emergency.

[0032] As can be seen particularly in Figure 2, the valve seats for several valves, several filters, and all of the various fluid connection points for several sensors, as well as the various fluid connection points described above, are integrated within the cover portion 40 of the accumulator housing 10. Thus, the cover portion 40 has housing chambers 110, 112 for the high-pressure filter 92 and the low-pressure filter 98 on either side of the cylindrical control housing 18, respectively, as a cast or injection-molded part. The cover portion 40 can also be manufactured as a whole from a single block. Fluid connection points 114, 116, to which a grounding device (not shown) can be connected as needed, are provided on the free end faces of the respective valve seats 110, 112.

[0033] In the arc-shaped region of the housing chamber 110, there is a connection point 79 for the pump supply pipe 78, to which a connecting pipe 86 having a system pressure 84 leads to an intersection 82. A return connection point 74, to which the system return pipe 72 can be connected, is incorporated on the opposite side into the side arc of the second valve seat 112 (see Figure 3). Furthermore, the pressure relief valve 88 and pressure sensor 96 are located on the top side of the cover portion 40 and are arranged in parallel with the control housing 18. For simplicity of explanation, the temperature sensor 102 is omitted in Figure 2, which would otherwise be located on the cover portion 40 at connection point 118 and measure the fluid temperature in the first low-pressure chamber 14. Two more pressure relief valves 106, 108, shown further in Figure 3, are connected to the cover portion 40 via a further connection point 120 and can vent the first low-pressure chamber 14 as needed. The flat upper side of the cover portion 40 also has an intake connection point 54, which leads to the intake side 60 of the hydraulic pump 56 via an intake pipe 58. In addition to the high-pressure filter 92 and low-pressure filter 98 described above, a spring-loaded check valve 94 or 100 is also housed in the valve seat 110 or 112 within the cover portion 40 upstream of the respective fluid connection points 114 and 116 in the associated valve seats 110 and 112.

[0034] Of the LVDT position measuring system 80, which monitors the position of the separator 12 and travels within the accumulator housing 18 and control piston 20 and cooperates with the guide piston 30, only the outer end 44 that closes the control housing 18 is visible in Figure 2. As can be seen in Figure 1, a radially extending fluid channel 122 is introduced into the cover portion 40, which leads into the high-pressure chamber 22 via individual passage openings 124 within the control housing 18, to which a pressure relief valve 88 and a pressure sensor 96 are connected in radial continuity, adjacent to and opposite the second valve seat 112 shown in Figure 1. In this regard, the channel 122 leads outward to a connection point 79 for the pump pressure in the supply pipe 78, where the relevant channel 122 is closed by a sealing plug 126, which must be removed before starting the accumulator device, i.e., for the purpose of connecting it to the supply circuit according to Figure 2.

[0035] The arrangement of the corresponding covers is merely an example. Therefore, further components can be accommodated on the cover portion 40 in a space-saving manner, or individual components can also be subject to the supply circuit shown in Figure 3 outside the bootstrap accumulator.

Claims

1. Accumulator devices, particularly bootstraps, The accumulator device comprises at least, Accumulator housing (10) and It consists of a separation device (12) which is movably arranged within the accumulator housing (10) and separates two low-pressure chambers (14, 16) within the accumulator housing (10), The accumulator device comprises a control housing (18) in which a control piston (20) is guided to be at least partially movable, and the control piston (20) cooperates with the separation device (12) to separate the high-pressure chamber (22) from at least one of the two low-pressure chambers (14, 16) in the accumulator housing (10), The separation device (12) is characterized in that the other low-pressure chamber (16) of the two low-pressure chambers (14, 16) in the accumulator housing (10) is at least partially surrounded by a flexible casing (26).

2. The accumulator device according to claim 1, characterized in that the flexible casing (26) is formed from an elastic bellows section, preferably a spring bellows section or a folded bellows section (28), and is particularly preferably made of a metal material.

3. The accumulator device according to claim 1 or 2, characterized in that the bellows portion (28) extends between the guide piston (30) and the end wall (32) of the accumulator housing (10).

4. The accumulator device according to any one of claims 1 to 3, characterized in that the guide piston (30) is firmly connected to a control piston (20), which is preferably designed as a tubular piston.

5. The accumulator device according to any one of claims 1 to 4, characterized in that the other low-pressure chamber (16) within the accumulator housing (10) is surrounded by the separation device (12) and is the ambient pressure through at least one opening (33) that is open to the environment.

6. The accumulator device according to any one of claims 1 to 5, characterized in that the first low-pressure chamber (14) in the accumulator housing (10) has an intake connection point (54) for connecting to a supply pump (56) and a low-pressure side return connection point (74).

7. The accumulator device according to any one of claims 1 to 6, characterized in that the high-pressure chamber (22) having a variable volume is sealed between the control piston (20) and the control housing (18).

8. The accumulator device according to any one of claims 1 to 7, characterized in that the control piston (20) is firmly connected to the separator (12) at one of its free end regions and is connected to the housing chamber (24) of the control housing (18) at the other free end region.

9. The accumulator device according to any one of claims 1 to 8, characterized in that the accumulator housing (10) is closed by a cover portion (40) having a plurality of seats for a plurality of valves, a plurality of filters, a plurality of sensors, and various fluid connection points.

10. The control device according to any one of claims 1 to 9, characterized in that a position measuring system (80) for monitoring a specific position of the separation device (12) is housed in the control piston (20).

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