Accumulator device

Abstract

An accumulator device, in particular bootstrap, at least consisting of an accumulator housing (10) and a separating device (12) which is movably arranged in said accumulator housing and which separates two low-pressure chambers (14, 16) from one another within the accumulator housing (10), and having a control housing (18) in which at least part of a control piston (20) is movably guided, which control piston interacts with the separating device (12) and separates a high-pressure chamber (22) from at least one (14) of the two low-pressure chambers (14, 16) in the accumulator housing (10), characterized in that the separating device (10) together with a flexible jacket (26) at least partially encloses the other (16) of the two low-pressure chambers (14, 16) in the accumulator housing (10).

Description

[0001] Storage device

[0002] The invention relates to a storage device, in particular a bootstrap, at least comprising a storage housing and a separating device movably arranged therein, which separates two low-pressure chambers from one another within the storage housing, and with a control housing in which a control piston is at least partially movably guided, which cooperates with the separating device and which separates a high-pressure chamber from at least one of the two low-pressure chambers in the storage housing.

[0003] Such accumulator devices, also known in technical terms as bootstrap accumulators, are integrated into hydraulic systems to ensure a sufficient fluid supply on the intake side of a hydraulic pump and to apply a low pressure to the associated suction line. Bootstrap accumulators automatically set themselves to a predefined fluid pressure and ensure an air-free fluid supply, particularly in closed hydraulic circuits. They operate smoothly and independently of ambient conditions such as temperature, air pressure, acceleration, and applied forces. Furthermore, a constant boost pressure is provided regardless of the system's fill level.Furthermore, such storage devices can be manufactured cost-effectively and are largely maintenance-free over longer periods of time, so that such storage devices have become established, particularly in the aviation sector, at least for larger aircraft.

[0004] EP 3 657 026 A1 discloses a generic accumulator device, in particular a bootstrap accumulator, which preloads the inlet pressure of a hydraulic supply pump on the intake side of the pump. A control housing with a control piston is fluidically connected to the output side of said hydraulic pump, and thus to its high-pressure side. This control housing controls a separating device in the form of a separating piston in an accumulator housing of the bootstrap accumulator. The separating device separates two low-pressure chambers, one of which preloads the intake side of the hydraulic pump with its output pressure. This prevents cavitation on the pump side.

[0005] Furthermore, at least one 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 rudder system and all types of flaps, such as brake and spoiler flaps, spoilers, landing gear and engine flaps, as well as the landing gear of the aircraft itself. This list is not exhaustive. On its output side, the hydraulic actuator used is in turn connected to the low-pressure side of the accumulator housing, from which the hydraulic pump is supplied with fluid at a preset preload pressure on the input side.

[0006] In the known solution, a hydraulic accumulator is also connected on the output side of the hydraulic pump into the high-pressure supply line to the high-pressure chamber of the control housing with the control piston, which, in the event of a failure of the overall energy supply, is able to continue to supply the respective actuator with fluid at a predeterminable working pressure in emergency operation for its operation.

[0007] In order to maintain the working pressure in the intake line of the hydraulic pump, the separating device in the form of the separating piston divides the accumulator housing into the two low-pressure chambers, whereby, depending on the travel position of the separating piston, one low-pressure chamber in the accumulator housing has the ambient pressure, and the other low-pressure chamber in the accumulator housing provides the preload pressure for the hydraulic supply, in particular in the form of the hydraulic pump.

[0008] The bootstrap accumulators regularly used in the state of the art have a longitudinally movable separating piston in the low-pressure segment of the accumulator housing, which preloads the corresponding low-pressure side of the accumulator by pulling on the large-area separating piston with the annular surface of a 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 (for example 85 psi) on the discharge side via the area transmission.A conventionally designed separating piston, as regularly used in hydraulics, has a circumferential seal on its outer circumference, opposite adjacent wall sections of the accumulator housing, usually in the form of at least one elastomeric sealing ring. During operation, however, this seal always leaves a thin film of fluid on the running surface, which is due to a leak between the two low-pressure chambers of the accumulator housing. Furthermore, if contaminants occur on the running surface of the accumulator housing, for example caused by normal abrasion, there is a risk of damage to the seal and / or the running surface. Based on this prior art, the invention is based on the object of improving known accumulator devices. This object is achieved by an accumulator device having the features of patent claim 1 in its entirety.

[0009] Because, according to the invention, the separating device at least partially encloses the other of the two low-pressure chambers in the accumulator housing, which regularly carries ambient pressure, with a flexible jacket, and further taking into account that the flexible jacket is fluid-tight, fluid losses on the prestressed low-pressure side of the accumulator housing, formed by the one low-pressure chamber, to the ambient side are avoided. Therefore, no leaks occur, and no damage can occur along the running surface of the accumulator housing due to any particle abrasion.

[0010] In a preferred embodiment of the storage device according to the invention, the flexible casing is formed from an elastic bellows, preferably a spring or folded bellows, which is particularly preferably made of a metal material. The bellows allows a secure, media-tight separation from the outside between the two mentioned low-pressure chambers in the storage housing of the storage device. The respective bellows, in particular metal bellows, is installed in such a way that the fluid, in particular in the form of a hydraulic fluid, is located between the bellows and the storage housing. In this way, damping can be achieved thanks to the bellows, in particular in the event of shock-like loads and / or vibration, since the fluid supports itself between the bellows folds from the outside.

[0011] Preferably, the bellows extends between a guide piston and an end wall of the accumulator housing. Since the guide piston is arranged with a flush, edge-side closure and is longitudinally movable inside the accumulator housing, the guide piston stabilizes the bellows with its individual bellows folds, thus reliably preventing any unintentional buckling or deformation of the bellows folds.

[0012] In a particularly preferred embodiment of the accumulator device according to the invention, the plate-like guide piston is fixedly connected to the control piston, which is preferably designed as a hollow piston and establishes the fluid-carrying connection at least between the one low-pressure chamber of the accumulator housing and a housing chamber of the control housing. In this way, internal pressure equalization occurs between the accumulator cylinder and the control cylinder, enabling unrestricted operation. Preferably, the other low-pressure chamber in the accumulator housing, which is surrounded or enclosed by the jacket- or bellows-shaped separating device, has the respective ambient pressure. In this way, the preload pressure in the adjacent, opposite low-pressure chamber in the accumulator housing can adapt directly to the pressure specifications from the control cylinder with its control piston.Preferably, this one low-pressure chamber in the accumulator housing has a suction connection for connection to a supply pump, in particular to ensure the pressure supply of an actuator, as well as a low-pressure side return connection, via which fluid originating from the respective actuator on the output side is returned to the low-pressure side of the accumulator housing with the fluid.

[0013] A particularly space-saving design is achieved when the high-pressure chamber with variable volume is enclosed between the control piston and the control housing. In particular, the control housing can be axially connected directly to the accumulator housing.

[0014] In a preferred embodiment of the accumulator device according to the invention, the control piston opens into one of the low-pressure chambers of the accumulator housing at one of its free end regions. In this way, a position measuring system can be accommodated in the control piston, particularly via the other free end region of the control housing, which serves to monitor the respective position of the separating device in the accumulator housing.

[0015] Particularly preferably, the accumulator housing is closed by a cover part with a plurality of receptacles for valves, filters, and sensors, as well as for various fluid connections. This allows the essential components of a fluid control system for a hydraulic supply pump, as well as a connected actuator, to be housed centrally in a single accumulator device.

[0016] The storage device according to the invention is explained in more detail below using an exemplary embodiment. In this case, the following are schematic and not to scale illustrations:

[0017] Figure 1 shows a longitudinal section through the essential components of the storage device;

[0018] Figure 2 shows an example of a cover structure as it can be used for a storage device according to Figure 1, whereby for the sake of simplicity Figure 1 does not show all components of the cover structure according to Figure 2; and

[0019] Figure 3 shows, in the form of a hydraulic circuit diagram, the essential components of an actuator control system including a storage device according to Figures 1 and 2.

[0020] Figure 1 shows the storage device as a whole, seen in a basic longitudinal section, whereby such storage devices are also technically referred to as bootstrap or bootstrap storage. The storage device has a pot-shaped storage housing 10 with a movably arranged separating device 12, which spatially separates two low-pressure chambers 14, 16 within the storage housing 10. These low-pressure chambers, when interacting with one another, can occupy different fluid volumes. Furthermore, there is a control housing 18, in which a control piston 20 is guided for longitudinal movement and which interacts with the separating device 12. In particular, the control piston 20 separates a high-pressure chamber 22 within the control housing 18 from another low-pressure chamber 24, which, according to the embodiment of Figure 1, is fluidly or media-connected to the one low-pressure chamber 14 in the storage housing 10.The separating device 12 has a fluid-impermeable, flexible casing 26, which at least partially encloses or encompasses the other 16 of the two low-pressure chambers 14, 16 in the accumulator housing. Thus, the casing 26 fluid-tightly seals the other fluid chamber 16 from a further fluid chamber 36, formed by the inner peripheral side of the accumulator housing 10 and the adjacent, opposite outer surface of the casing 26.

[0021] The flexible casing 26 consists of an elastic bellows in the form of a convoluted bellows 28, which is preferably made of a metal material commonly used for such a bellows. The convoluted bellows 28 extends between a guide piston 30 and a front end wall 32 of the accumulator housing 10. The bellows 28 is secured with its free, opposite ends to the guide piston 30 and to the end wall 32, in particular, it is firmly welded at these points. The end wall 32 has at least one opening 33, so that the interior of the bellows 28, or the other media or low-pressure chamber 16, is at ambient pressure. The opening 33 can also be provided with a venting device (not shown).The cylindrical guide piston 30 is plate-shaped and has a support and guide ring 34 on the outer circumference with individual interruptions not shown in detail, so that outside the casing 26 a fluid-carrying connection is established between the one low-pressure chamber 14 and the fluid chamber 36, which is delimited by the outer circumference of the bellows 28 and by the inner circumference 38 of the cylindrical accumulator housing 10.

[0022] If the guide piston 30 moves to the left as viewed in Figure 1, this movement is possible until the individual folds of the bellows 28 come to rest on top of one another, i.e., until they come to a complete stop. In the opposite direction of travel of the guide piston 30, i.e., in a direction to the right, the individual folds of the bellows 28 are pulled apart, and the other low-pressure chamber 16 in the accumulator housing 10 increases in volume accordingly, whereas the one low-pressure chamber 14 decreases in volume equally, which leads to an increase in the preload pressure.

[0023] The storage housing 10 is flush with a cover part 40, through which the hollow-cylindrical control housing 18 extends. The control housing 18 is fixedly secured to the cover part 40 by corresponding anchoring means, such as snap and locking rings. Furthermore, the hollow-cylindrical control housing 18 extends from a corresponding securing point 42 on the cover part 40 with a predeterminable projection away from the storage housing 10 toward the environment. Furthermore, the control housing 18 is hermetically sealed from the environment by a connecting part 44, which is shown from the outside in the illustration according to Figure 2 and is omitted from Figure 1 for the sake of simplicity.

[0024] The control piston 20, which is designed as a hollow piston, is guided for longitudinal movement in the control housing 18. Thus, a fluid-carrying connection is established between one low-pressure chamber 14 in the accumulator housing 10 and the other low-pressure chamber 24 in 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 closed at its other free end, for example, sealed with a plug 46. Furthermore, in this area of ​​the control piston 20, individual orifice openings 48 pass through the plug 46, which are preferably grouped diametrically opposite one another around the longitudinal or travel axis of the control piston 20.In this way, an internal fluid connection is created between the one low-pressure chamber 14 and the other low-pressure chamber 24 via the apertures 48 and the hollow piston-like control piston 20, so that a fluid exchange can take place between these chambers 14 and 24 in the manner of a pendulum volume. The corresponding exchange movement of the pendulum volume is dampened by the apertures 48.

[0025] The control piston 20, which is longitudinally movable within the control housing 18, has a seal package 50 (not shown in detail) on its outer circumference in the direction of the additional low-pressure chamber 24; likewise, the control piston 20 is guided in a sealed manner in the region of the fixing point 42 in the cover part 40 via an additional seal package 52. The high-pressure chamber 22 with a variable volume extends between the two seal packages 50, 52. If, for example, the high pressure influence in the high-pressure chamber 22 increases compared to the low-pressure areas in the chambers 14, 16, and 24, the volume of the high-pressure chamber 22 increases, and under the influence of pressure, the control piston 20 moves to the right from its position shown in Figure 1.When the high-pressure chamber 22 is depressurized, however, the control piston 20 is moved to the left (as viewed in Figure 1) under the influence of the low-pressure components 14, 16, 24, and the volume in the high-pressure chamber 22 decreases in a valve-controlled manner. The guide piston 30 of the separating device 12 is driven along with it. During the aforementioned movement to the right, the fluid volume in the low-pressure chamber 14 decreases, which leads to an increase in the preload pressure.

[0026] The following explains in more detail the integration of the storage device shown in Figure 1 into an overall hydraulic or supply system using the circuit diagram shown in Figure 3. The previous reference numerals relating to the storage device are also used for the same components shown in Figure 3, and the explanations given so far also apply to the supply solution shown in Figure 3.

[0027] Thus, one low-pressure chamber 14 in the accumulator housing W has a suction connection 54 for connecting a conventional supply or hydraulic pump 56, which is only symbolically shown in Figure 3. A so-called suction line 58, which may be very long, leads from the suction connection 54 to the inlet or intake side 60 of the hydraulic pump 56. The latter is connected with its pressure or output side 62 via a pump or high-pressure line 64 to the supply side 66 of an actuator 68, which may consist of one or more hydraulic working cylinders, each of which may be used to control the rudder system of an aircraft or other components, such as operable flaps or the landing gear. This list is not exhaustive.On the output or outlet side 70, the actuator 68 is connected to a system return line 72, which in turn opens into the one low-pressure chamber 14 in the accumulator housing 10 via a low-pressure side return connection 74. The actuator control, usually in the form of a valve control, for extending and retracting the respective actuator 68 or working cylinder is conventional, so it will not be discussed in more detail here. In this respect, the actuator 68 is only shown with its inlet and outlet sides 66, 70. As can also be seen from Figure 3, a supply line 78 opens into the pump or high-pressure line 64 at a branch point 76, which, like line 64, carries high pressure or pump pressure from the hydraulic pump 56 to its outlet side 62. This supply line 78 opens into the high-pressure chamber 22 in the control housing 18 via a connection point 79.Depending on the pressure in the high-pressure chamber 22, the control piston 20 is then positioned in a respective position, as is the guide piston 30 of the separating device 12 connected to it, depending on the force or pressure equilibrium between the high-pressure side and the low-pressure side of the storage device.

[0028] For the sake of simplicity, the bellows 28 is not shown in detail in Figure 3; instead, a position measuring system is symbolically designated 80, for example in the form of a so-called LVDT system, for the purpose of detecting the position of the guide piston 30 of the separating device 12. However, this LVDT system is preferably located in the free hollow cross-section of the control piston 20. Since such a construction is known (EP 3 657 026 A1), it will not be discussed further here. Via an intersection point 82, an unspecified system pressure 84 is also led to the high-pressure side with the high-pressure chamber 22, which, via a corresponding connecting line 86, forwards pressure components originating from a conventional hydraulic, unspecified supply circuit to the connection point 79 of the storage device.According to the illustration in Figure 3, the system and supply circuit would also function accordingly if the system pressure 84 were not introduced via the connecting line 86 to the connection point 79, especially if this were eliminated entirely. A pressure relief valve 88 is connected between the high-pressure side and the low-pressure side of the supply circuit. This valve connects the high-pressure side to the low-pressure side at a preset set pressure, i.e., for safety reasons, it establishes a pressure-equalizing connection between the fluid lines 72 and 78.

[0029] A check valve 90 is also connected to the supply or pump pressure line 78, which opens toward a high-pressure side fluid filter 92. A branch line is connected between the check valve 90 and the high-pressure side fluid filter 92, with a spring-loaded check valve 94 that opens toward the line 78 and seals a first fluid connection 114 in a fluid-tight manner in the position shown. A pressure sensor 96 is also connected to the clean side of the filter 92, which monitors the high-pressure side accordingly. Ground equipment (not shown in detail), for example for maintenance or inspection purposes, can be independently connected to the fluid connection point 114 with the spring-loaded check valve 94.Accordingly, a filter 98 with a bypass arrangement is located on the low-pressure side of the supply circuit in the system return line 72, which in turn is connected via a branch to another spring-loaded check valve 100 in a fluid-conducting manner, via which in turn a hydraulic fluid connection 116 for ground equipment is created for the purpose of carrying out maintenance and monitoring activities, comparable to the solution with the connection point 114.

[0030] Furthermore, a temperature sensor 102 is connected to the return line 72 in the direct low-pressure inlet to the accumulator housing 10. Two vent valves 106, 108 are connected to a further low-pressure line 104, which leads into the one low-pressure chamber 14. Of these, vent valve 108 can be manually operated.

[0031] Ultimately, the overall arrangement ensures that, regardless of the system state (pressure, temperature, acceleration, loads, installation situation, etc.) and even with any length of the suction line 58, the hydraulic pump 56 always has a preload pressure from the low-pressure area of ​​the accumulator housing 10 on its inlet or intake side 60 such that trouble-free, cavity-free operation of the hydraulic pump 56 is possible, even after starting up from a standstill. This operating behavior also applies to virtually any length of the suction line 58 and when the engine power is reduced or an engine fails completely due to a malfunction or emergency.

[0032] As can be seen in particular from Figure 2, all essential receptacles for valves, filters, and sensors, as well as the various fluid connections mentioned above, are integrated in the cover part 40 of the storage housing 10. Thus, the cover part 40, in the manner of a cast or injection-molded part, has a receptacle 110, 112 for the high-pressure filter 92 and the low-pressure filter 98 on both sides next to the cylindrical control housing 18. However, the cover part 40 can also be manufactured as a whole from a single block. The fluid connection 114, 116, to which the ground equipment (not shown) can be connected if necessary, is incorporated on the free end face of the respective receptacle 110, 112.

[0033] In the edge arc area of ​​the receiving chamber 110 is the connection point 79 for the pump supply line 78, into which the connecting line 86 with the system pressure 84 opens, if necessary, at the intersection point 82. On the opposite side, in the lateral edge arc of the second receptacle 112, the return connection 74 is provided, to which the system return line 72 can be connected (see Figure 3). Furthermore, on the top side of the cover part 40 and in a parallel arrangement to the control housing 18, there is the pressure relief valve 88 and the pressure sensor 96. For the sake of simplicity of illustration, the temperature sensor 102 has been omitted from Figure 2; this temperature sensor is otherwise placed on the cover part 40 at the connection point 118 and measures the fluid temperature in the one low-pressure chamber 14.The two relief valves 106, 108 further shown in Figure 3 can be connected to the cover part 40 via the further connection points 120 and vent the one low-pressure chamber 14 if necessary. On the flat upper side of the cover part 40 there is also the suction connection 54 which leads via the suction line 58 to the suction side 60 of the hydraulic pump 56. In addition to the aforementioned high-pressure filter 92 and the low-pressure filter 98, the spring-loaded check valve 94 or 100 is also accommodated in the receptacles 110 and 112 in the cover part 40 upstream of the respective fluid connection 114, 116 in the associated receptacle 110, 112.

[0034] Of the LVDT position measuring system 80, which runs within the accumulator housing 18 and the control piston 20 and interacts with the guide piston 30 to monitor the position of the separating device 12, only the outer end part 44, which closes the control housing 18, is visible in Figure 2. As can be seen in this context from Figure 1, a radially extending fluid channel 122 is incorporated into the cover part 40, which opens into the high-pressure chamber 22 via individual passage openings 124 in the control housing 18 and to which the pressure relief valve 88 and the pressure sensor 96 are connected in a radial extension; adjacent and opposite the second receptacle 112 shown in Figure 1.In this respect, the channel 122 opens outwards into the connection point 79 for the pump pressure in the supply line 78, wherein the relevant channel 122 is closed by a sealing plug 126, which must be removed before commissioning the storage device, i.e. for the purpose of connecting it to the supply circuit according to Figure 2.

[0035] This cover arrangement is merely exemplary. Additional components can be accommodated on the cover part 40 to save space, or individual components can also be part of the supply circuit shown in Figure 3, outside of the bootstrap memory.

Claims

Patent claims 1 . Storage device, in particular bootstrap, at least consisting of a storage housing (10) and a separating device (12) arranged movably therein, which separates two low-pressure chambers (14, 16) from one another within the storage housing (10), and with a control housing (18) in which a control piston (20) is at least partially movably guided, which cooperates with the separating device (12) and which separates a high-pressure chamber (22) from at least one (14) of the two low-pressure chambers (14, 16) in the storage housing (10), characterized in that the separating device (10) with a flexible jacket (26) at least partially encloses the other (16) of the two low-pressure chambers (14, 16) in the storage housing (10).

2. Storage device according to claim 1, characterized in that the flexible casing (26) is formed from an elastic bellows, preferably a spring or bellows (28), which particularly preferably consists of a metal material.

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

4. Storage device according to one of the preceding claims, characterized in that the guide piston (30) is firmly connected to the control piston (20), which is preferably designed as a hollow piston.

5. Storage device according to one of the preceding claims, characterized in that the other low-pressure chamber (16) in the Storage housing (10), which is surrounded by the separating device (12), has ambient pressure via at least one opening (33) opening into the environment.

6. Storage device according to one of the preceding claims, characterized in that the one low-pressure chamber (14) in the storage housing (10) has a suction connection (54) for connection to a supply pump (56) and a low-pressure side return connection (74).

7. Storage device according to one of the preceding claims, characterized in that the high-pressure chamber (22) with variable volume is enclosed between the control piston (20) and the control housing (18).

8. Storage device according to one of the preceding claims, characterized in that the control piston (20) is firmly connected at its one free end region to the separating device (12) and opens with its other free end region into a housing space (24) of the control housing (18).

9. Storage device according to one of the preceding claims, characterized in that the storage housing (10) is closed by a cover part (40) with a plurality of receptacles for valves, filters and sensors as well as for various fluid connections.

10. Control device according to one of the preceding claims, characterized in that a position measuring system (80) is accommodated in the control piston (20) for monitoring the respective position of the separating device (12).

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