Piston Accumulator

Abstract

The invention relates to a piston accumulator comprising an accumulator housing 10 and a separating piston 12 guided longitudinally movably in the accumulator housing 10 and separating two medium chambers 14, 16 from one another within the accumulator housing 10, in particular a medium chamber 14 with a working gas and another medium chamber 16 with a fluid, such as a hydraulic oil, characterized in that in the piston accumulator the separating piston 12 comprises two piston parts 13, 15 designed as disks with the same outer diameter, rigidly connected to one another and held at a distance from one another via an elastically flexible piston rod 17, the two piston parts being curved as a whole under the action of at least one external force F and starting from an initial state returning to their initial state when the respective at least one external force F is removed.

Description

[Technical field]

[0001] The invention relates to a piston accumulator having an accumulator housing and a separating piston guided longitudinally movably in the accumulator housing, which separates two medium chambers in the accumulator housing, in particular a medium chamber comprising a working gas, from a further medium chamber comprising a liquid, such as a working oil, from each other. [Background technology]

[0002] Piston accumulators of this type are commercially available. They are widely used in hydraulic systems, for example for energy storage, for emergency operation to damp mechanical or pressure shocks, for vehicle suspensions, etc.

[0003] DE 19701303 A1 discloses a piston accumulator with a first separating piston, which can move longitudinally in the accumulator housing and separate the liquid side of the accumulator from the gas side, a second separating piston, which is arranged on the liquid side of the accumulator, and an intermediate space arranged between the two separating pistons, which is filled with a sealing medium preloaded under the action of the two separating pistons, which can move towards each other via a force accumulator, usually in the form of a compression spring. For this purpose, the two separating pistons are pierced by a connecting rod, the compression spring abutting against one end on the first separating piston and against the other end on the connecting rod. In this way, the block-shaped first separated piston is stably guided longitudinally over a relatively long distance inside the rigidly designed accumulator housing using several seals and guide bands arranged on the periphery, while the first separated piston is axially held against the preload of a compression spring on the connecting rod, while the disk-shaped second separated piston is movably guided along the inside of the accumulator housing with only one sealing ring and is rigidly connected to the connecting rod. In this way, the two separated pistons, one designed as a solid block and the other as a disk-shaped body, are preloaded against each other under the action of a compression spring acting on the connecting rod, so that a kind of variable two-part separated piston is formed with a gas barrier arranged in the intermediate space between the separated pistons, which prevents small gas molecules, which would in the long term impair the functional reliability of the known piston accumulator, from passing through the gas-tight sealing system in the form of a sealing ring of the separated piston arranged on the periphery when the pressure on the oil side is relieved.

[0004] Due to the rigid structure of the accumulator housing and the separate piston arrangement, despite the ability of the two separate pistons to move relative to each other, known piston accumulator arrangements can only be used improperly if both the accumulator housing side and the separate piston arrangement are subjected to their associated bending forces. For example, Patent Document 2 (DE 102016003345 A1) describes: 1. A wind turbine comprising: a rotor blade having two piston accumulators extending along its longitudinal direction, the separate pistons being preloaded via a compressible medium and connected to each other in a medium-conveying manner via a fluid line using a non-compressible medium; a control valve for establishing a medium connection between or isolating two piston accumulators of a pair when the control valve is connected to a respective fluid line; An acceleration sensor; A rotor position sensor; The present invention relates to a control system for evaluating sensor data and actuating at least one pair of piston accumulators by controlling a control valve, the control system comprising: a piston accumulator bending force as part of a balancing device for compensating for an imbalance of a rotor of a wind turbine;

[0005] This balancing device makes it possible to balance each rotor of the wind turbine during operation, which is usually necessary since imbalances can occur especially during operation, e.g. due to the accumulation of dirt on the rotor blades or when turbulence occurs, e.g. during wind power operation.

[0006] The rotor blades are also usually subjected to deformations during the operation of the wind turbine. To account for these deformations, kinematic models are used that are able to account for the deformations of the rotor blades, for example based on the Euler-Bernoulli beam assumption. The theoretically determinable deformations on each rotor blade correspond to the acquisition of practical measurements, which are preferably based on a combination of photogrammetry and laser scanner measurements. In any case, in practice, the deformations of the rotor blades usually occur in the form of reversible deflections along the rotor's longitudinal axis, and according to the teaching of US Pat. No. 5,399,633, the piston accumulators hinged to the rotor blades must be able to follow these deformations, which are the result of constantly changing bending curves caused by changing wind currents and turbulences that change during operation. The piston accumulator solutions, which are usually made of solid steel material, change over time and can no longer follow the changing bending curves of the rotor blades, which often leads to failures of the connection points between the piston accumulators and the rotor blades and thus to the unusability of the balancing device as a whole.

[0007] Notwithstanding the initial conditions described above for wind turbines, piston accumulators may also be subjected to other changing and alternating bending forces, for example when the piston accumulators are subjected to strong vibrations during operation of the hydraulic system, such as when used in aircraft, rockets, military vehicles, agricultural machinery, etc. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] DE 19701303 A1 [Patent Document 2] DE 102016003345 A1 Summary of the Invention [Problem to be solved by the invention]

[0009] Based on this state of the art, the present invention is therefore based on the object of further improving a piston accumulator of the above-mentioned type in such a way that safe operation is guaranteed even in the event of strong bending forces, even in conjunction with third-party components. [Means for solving the problem]

[0010] A piston accumulator having the features of claim 1 solves this problem in its entirety.

[0011] According to the characterizing part of claim 1, the separated piston comprises two piston parts designed as disks with the same outer diameter and rigidly connected to each other and held at a distance via an elastically flexible piston rod, which piston parts as a whole allow bending starting from an initial state under the action of at least one external force and return to their initial state when the respective force is removed, so that a piston accumulator is created which ensures that even in the case of large deflections of the accumulator housing, the separated piston with its two piston parts can follow the deflections in question without hindrance and can return to its initial state without deformation when the load is removed, even in the case of said deflections of the accumulator housing. An important factor in this respect is the rigid connection of the two piston parts via the elastically flexible piston rod, which allows to realize a linear elastic behavior (Hooke's law) for the multi-part separated piston. Furthermore, the elastically flexible connection via the piston rod prevents the disk-shaped piston parts in the accumulator housing from being able to tilt relative to each other to such an extent that unhindered operation is no longer guaranteed.

[0012] Further advantageous embodiments of the piston accumulator according to the invention are the subject of the dependent claims. In particular, the flexibility of the separate piston with two piston parts allows, via an elastically flexible piston rod arranged between the two piston parts, the piston rod with its longitudinal axis to easily follow the line of the bending curve thus formed in the event of any bending of the accumulator housing along the central axis of the bending, and this also applies in the case of resetting when the curve changes again to a straight central axis. This is not comparable to the prior art.

[0013] In the following, the piston accumulator according to the invention is explained in more detail using an embodiment according to the drawings.

[0014] The drawings are schematic and not to scale. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 shows, in longitudinal section, an edge end region of an accumulator housing constructed in a sandwich structure as a composite liner. [Diagram 2] FIG. 2 shows a front view of the housing cover for the accumulator housing according to FIG. [Diagram 3] FIG. 3 shows an enlarged detail of the end section of the accumulator housing indicated by arrow X in FIG. [Figure 4] FIG. 4 shows a schematic diagram of a possible curvature of the accumulator housing according to FIG. 1 when a bending force is applied in the direction of the arrow. [Diagram 5] FIG. 5 shows a side view of a separation piston for the accumulator housing according to FIG. [Figure 6] FIG. 6 shows a front view of a separation piston for the accumulator housing according to FIG. [Figure 7] FIG. 7 shows the separation piston shown in FIG. 5, inserted into the accumulator housing according to FIG. [Figure 8]FIG. 8 illustrates the use of a piston accumulator according to the embodiment of FIG. 7 in a wind turbine having three rotating rotor blades. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] FIG. 1 shows a longitudinal section through an accumulator housing 10 of a piston accumulator, and FIG. 7 shows the accumulator housing 10 with a separating piston 12 arranged so as to be longitudinally movable, which separates two chambers 14, 16 from one another in the accumulator housing 10 and is shown in more detail in FIGS. 5 and 6. The chamber 14 can be used to contain a working gas in the form of nitrogen gas, for example, and the further chamber 16 is used to contain a working fluid, for example hydraulic oil. The accumulator housing 10 can have a correspondingly large overall length, for example of the order of 2 meters, so that, although the accumulator housing 10 is shown only in its end regions in FIGS. 1 and 7, in the central region the accumulator housing 10 also corresponds to an edge end region design as far as the liner structure of the accumulator housing 10 is concerned. Thus, the accumulator housing 10 is elastically constructed in a sandwich design from individual layers 18, 20, 22 and 24, some of which differ from one another, such that starting from an initial state as shown in Figures 1 and 7, it is capable of bending as a whole under the action of at least one external force F, and that, once the respective force F is removed, the accumulator housing 10 elastically returns to its initial state, according to the simplified representation according to Figure 4. In this respect, the sandwich structure allows for a linear elastic behavior for the accumulator housing 10.

[0017] With respect to the sandwich structure described above, the innermost layer 18 of the housing 10 is gas-impermeable and each of the subsequent outer layers 20, 22 and 24 is formed from a textile winding. The layer composite in question is shown in particular in FIG. 3, which is an enlarged copy of the detail marked with reference X in FIG. 1. The innermost layer 18 is designed as a thin steel tube with respect to wall thickness, which is preferably manufactured in one piece by flow-forming, as shown in FIG. 7, and forms on its inner circumference a smooth running surface 26 for the separating piston 12. The steel liner 18 extends over the entire length of the accumulator housing 10 up to its free front end. Each textile winding for the accumulator housing 10 has in each case a winding direction different from the textile winding preceding it in the winding sequence. Each fibre winding is preferably made of carbon fibre material, the fibre windings of the layer 20 being wound circumferentially on the steel layer 18 and therefore having a winding direction of less than 90° to the longitudinal direction 28 of the accumulator housing 10. On the other hand, the subsequent layers 22 may deviate from the abovementioned 90° winding direction by 0°-45°, but it is also possible to apply the relevant layer 22 to the winding 20 substantially parallel to the longitudinal direction 28 of the accumulator housing 10. Here, other winding directions are possible as well as the application of additional layers, depending on the respective application and the required stiffness of the accumulator housing 10 as a whole. The outermost layer 24 then consists of fibre windings having the same direction as the wound layer 20, i.e. a radial winding direction of 90° to the longitudinal direction 28.

[0018] As further shown in particular in FIG. 3, each end of the accumulator housing 10 is provided with an annular connecting part 30, which is in each case constructed as an identical part. The annular or tubular connecting part 30 is pierced at its inner circumference by the steel liner 18 and opens at the front side at the free end of the connecting part 30. Each connecting part 30 has at its outer circumference an annular receiving groove 32 for receiving the fiber layers of the two outermost windings 22 and 24. The receiving groove 32 is bounded on one side by a connecting flange 34 and on the inside by a fixed ramp 36. Both the connecting flange 34 and the fixed ramp 36 have contact surfaces 38, 40 extending obliquely on their adjacent sides, which form a cone with each other in an imaginary extension in the direction of the groove base 42. In this case, the fixed ramp 36 is overlapped by the third layer 22, which at this point is in direct contact with the groove base 42 of the receiving groove 32. The third layer 22 tapers to a point at its free front end and ends at the base of the obliquely extending contact surface 38. The leading end of the third layer 22 defines an obliquely extending wall 44 of this third layer 22, which together with the obliquely extending contact surface 38 of the connection part 30 forms a further V-shaped engagement groove 46, which is also designed as an annular groove, used to engage with the free end of the outer layer 24. In contrast, the second layer 20 following the steel layer 18 in the winding sequence nests against the inclined part 48 of the fixed inclined part 36, which in this area adjoins the innermost layer 18 at its foot end with a slight inclination angle. In this way, a solid layer or liner composite of the individual layers 18, 20, 22 and 24 is achieved as part of a sandwich structure in their free end face area via the connection flange 34 and the respective connection part 30 with the fixed inclined part 36.

[0019] At the transition point between the steeply extending contact surface 40 and the uniformly rising surface with the ramp 48, the fixed ramp 36 has a substantially horizontally extending circumferential or engagement surface 50, as shown in FIG. 3, through which serve for the passage of individual, preferably metallic, retaining pins 52, evenly distributed radially at discrete distances from one another around the accumulator housing 10, rigidly connecting the layer composite of the individual layers 18, 20, 22 and 24 to the connection 30 and thus ensuring a robust layer composite.

[0020] The free end face of each connection flange 34 of the connection part 30 has pin recesses 54 evenly distributed around the circumference of the connection flange 34. Each cover part 56 can be pinned to the associated connection part 30 via the corresponding pin recesses 54, the cover part 56 being present at each free end of the accumulator housing 10. The associated pin, not shown in detail in this respect, should be attached to the cover part 56 along an annular surface 58 provided for this purpose, the imaginary inner curve of which is shown by a dashed and dotted line 60. In addition, the annular surface 58 is used, on its inside facing the accumulator housing 10, to apply adhesive in order to create a media-tight connection between the two media chambers 14, 16 and the environment. Furthermore, within the scope of the embodiments not shown in detail, it is possible to connect the respective cover part 56 to the accumulator housing 10 in a media-tight and pressure-tight manner via a textile winding. In the central area of ​​each cover part 56 there is a connection opening 62 which can be closed tightly with the medium chamber 14 on the gas side of the accumulator housing 10 and which remains open on the liquid side to connect the further medium chamber 16 to a conventional hydraulic circuit (not shown). In order to separate the two medium chambers 14, 16, i.e. the gas side from the liquid side in a medium-tight manner, a separation piston 12 is inserted into the accumulator housing 10 as shown in more detail in figures 5 and 6 and as shown in figure 7, figure 6 showing a front view from the right side of the separation piston 12 according to figure 5. The separation piston 12 thus has two piston parts 13, 15 which are designed as disks with the same outer diameter and are held firmly at a distance from each other via an elastically flexible piston rod 17 which allows bending as a whole under the action of at least one external force F starting from an initial state and returning to the initial state when the respective force F is removed. In this way, the double disc piston configuration of the separation piston 12 is adapted to follow the curvature of the accumulator housing 10, as shown by way of example in FIG.Like the two piston parts 13, 15, the piston rod 17 is made of a suitable metallic material, the piston rod 17 being preferably configured to be more flexible in bending than the disks 13, 15. In particular, the piston rod 17 prevents the relatively thin disks for the two piston parts 13, 15 from tilting into the guide along the running surface 26 of the accumulator housing 10 and thus blocking the movement sequence of the separation piston 12.

[0021] One piston part 13 facing one medium chamber 14 has a guide band 19 on its outer circumference, while the other piston part 15 facing the further medium chamber 16 has a further guide band 21 and a ring seal 23 made of a conventional elastomeric material. The two annular guide bands 19, 21 are designed as one and the same part and consist of a material with good sliding properties, such as a PTFE material, which is preferably correspondingly heat-resistant. Both the guide bands 19, 21 and the ring seal 23 are inserted into an annular receiving groove of the corresponding piston part 13, 15 and slide along the inner circumferential side of the accumulator housing 10 in the form of a running surface 26. In this regard, according to the illustration of FIG. 5, the ring seal 23 is arranged between the two guide bands 19, 21 on the other piston part 15. Due to the disk-like arrangement of the two piston parts 13, 15, an annular space 25 is formed between them, which contains the medium of one medium chamber 14, in particular in the form of a working gas. In order to avoid the above-mentioned tilting of the disk-shaped piston parts 13, 15 and nevertheless ensure that the separated piston 12 as a whole is able to follow the curved course of the accumulator housing 10 subjected to bending forces, the distance between the two disk-shaped piston parts 13, 15 is greater than 1 / 3 of the diameter of the respective piston parts 13, 15, and in any case less than the diameter. Furthermore, in order to ensure a reliable displacement course, the disk thickness of the piston part 13 with the guide band 19 is selected to be smaller than the disk thickness of the other piston part 15 with the further guide band 21 and the sealing ring 23. For unhindered operation, it is further provided that the piston rod 17 with two opposing shoulders 27 merges flatly into the mutually facing free end faces 29, 31 of the two piston parts 13 and 15, respectively. The piston rod 17 thus engages the respective piston portion 13, 15 with its opposite end region and is secured along this end region to the associated piston portion 13, 15 via threads 33 by a conventional lock nut 35 which is only shown in FIG. 6.

[0022] As can be further seen from figures 5, 6 and 7, the disks of the two piston parts 13, 15 are provided with annular recesses 37, which serve on the one hand to save weight and also to increase the elasticity of the disks 13, 15. The recesses 37 are configured essentially identically on the opposing end faces of the two piston parts 13, 15 and are arranged concentrically with a central recess 39 which receives the associated threads 33 of the piston rod 17 and the locking nut 35, respectively. Furthermore, on the inner end wall of the piston part 15, in a concentric arrangement with these recesses 37, there is an annular recess 37 which extends both on the outer periphery and on the inner periphery. The separated piston 12 thus designed to be elastic can also be used for a "normal" accumulator housing 10, and the accumulator housing 10 of the presented type can also be used for a "conventional" separated piston. Instead of the locking nut 35, any other suitable connection can be used, such as bolting, bonding or the use of a locking pin.

[0023] Figure 4 now shows the accumulator housing 10 supported on two bearing blocks 64, with a compressive force F applied from above at a central entry point 66, such that the accumulator housing 10 bends as shown in Figure 4. The accumulator housing 10 is shown in Figure 4 in an idealized form, specifically without the two end cover parts 56. When the force F is removed, the accumulator or accumulator housing 10 returns to its original position, as shown in Figures 1 and 7. It will be appreciated that if the accumulator housing 10 is held at the entry point 66 and a force is applied from below through the bearing blocks 64, a deflection equivalent to that shown in Figure 4 will result.

[0024] If the piston accumulator is mounted as part of a balancing device for compensating rotor imbalances of a wind turbine, as shown by way of example in FIG. 8, the piston accumulator is fixed to one of the two blade sides of each rotor blade 68 along the two bearing blocks 64. In FIG. 8, a partially illustrated tower of a wind turbine is indicated with the reference number 70. As in a wind turbine, a machine house 72, also called a "nacelle", is arranged at the top end of the tower 70 and is rotatable around the vertical axis of the tower, so that it can rotate back and forth by two to three revolutions. The rotor hub for the three rotor blades 68 of the three-bladed rotor rotatably mounted in the nacelle 72 is not visible in the simplified representation according to FIG. 8. Within each rotor blade 68 there is a pair of piston accumulators, comprising an inner piston accumulator 74 and an outer piston accumulator 76. Each piston accumulator 74, 76 is essentially constructed as shown in FIG. 7 with corresponding end parts, such as the respective cover parts 56, at the ends. Each piston accumulator 74 , 76 is mounted to an associated rotor blade 68 via an associated bearing block 64 .

[0025] The inner piston accumulators 74 are in each case disposed in the region of the blade root adjacent the rotor hub, while the outer piston accumulators 76 are offset toward the respective blade tips by a distance extending along the longitudinal orientation of the respective rotor blade 68. Preferably, the outer piston accumulators 76 are dimensioned narrower than their counterpart inner piston accumulators 74 in response to the smaller installation space available within the respective rotor blade 68 near the blade tips.

[0026] In the inner piston accumulator 74, a medium or working chamber 14 carrying a compressible pressure medium, such as a working gas, preferably in the form of nitrogen gas, faces the blade root, and in the outer piston accumulator 76, a working chamber 14 carrying a compressible medium faces the blade tip. If necessary, the medium chamber 14 of the inner piston accumulator 74 can also carry ambient air and be kept decompressed. In the other medium chamber 16 of each of the piston accumulators 74 and 76, which are opposite each other in the rotor blade 68, an incompressible medium, such as a hydraulic fluid, is arranged as a mass that can be displaced in the respective rotor blade 68 for imbalance compensation. These fluid-carrying medium chambers 16 facing each other are connected to each other via fluid lines 78, for example in the form of pipes or hoses. A control valve 80, for example in the form of an electromagnetically operated switching valve that can be centrally controlled by a control system 82, is arranged in each fluid line 78 adjacent to each inner piston accumulator 74. In order to transmit values ​​of lateral accelerations acting on the support structure of the wind turbine transversely to the rotor shaft to the control system 82, an acceleration sensor 84 is arranged in the tower head or nacelle 72 and is connected to the control system 82 via corresponding measurement signal lines. Furthermore, a rotor position sensor 86 in the form of a rotor speed sensor or rotor rotational position sensor on the rotor shaft is provided, which determines the position of the rotor blades 68 and transmits it to the control system 82 via further measurement signal lines.

[0027] To perform the imbalance compensation process using the balancing device, the wind turbine is initialized by increasing the rotor speed by the motor to a speed at which the working fluid located in the fluid carrying medium chambers 16 of the piston accumulators 74, 76 and in the fluid lines 78 between them is displaced outward toward the blade tips under the action of centrifugal force when the control valve 80 is open, thereby compressing the working gas in the respective medium chambers 14 of the outer piston accumulators 76 so that the outer piston accumulators 76 are in a filled state. To detect the presence of an imbalance, the wind turbine must be operated at critical speeds, and if an imbalance exists, operation at these speeds will result in the generation of lateral tower vibrations and thus an acceleration signal from the acceleration sensor 84. The determination of which of the multiple rotor blades 68 have different mass moments of inertia is performed using a rotor rotational position sensor on the rotor shaft, which determines the exact position of the rotor blades 68 at any time. From the instantaneous value of the rotor position lateral acceleration, control system 82 determines which rotor blades 68 have different mass moments of inertia and provides control signals to control valves 80 to partially discharge the corresponding filled piston accumulators 76 to shift the mass of incompressible hydraulic fluid such that lateral acceleration is no longer measured. The rotor is then collectively balanced.

[0028] It will be appreciated that during operation of the rotor blades 68, deformations due to bending forces occur as a result of wind influences, leading to bending, especially in the longitudinal direction, of the respective rotor blade 68 during the occurrence of turbulence. Thanks to the above-mentioned piston accumulator solution with the accumulator housing 10 and / or the flexible separating piston 12, which are flexible against bending, the bending deformations of the respective rotor blades 68 can be absorbed in all directions, so that the piston accumulator pair 74, 76 can ensure the functional performance of mass balancing to compensate for the imbalance of the rotor blades 68 even in the event of the above-mentioned deflections.

Claims

1. A piston accumulator comprising an accumulator housing (10) and a separating piston (12) guided in a longitudinally movably manner in the accumulator housing (10) and separating two medium chambers (14, 16) in the accumulator housing (10), in particular a medium chamber (14) containing a working gas and another medium chamber (16) containing a fluid such as a working oil, 4. A piston accumulator comprising: a separating piston (12) having two piston parts (13, 15) designed as disks having the same outer diameter, rigidly connected to one another and held at a distance from one another via an elastically flexible piston rod (17), the two piston parts being curved as a whole under the action of at least one external force (F) and, starting from an initial state, returning to their initial state when the respective at least one external force (F) is removed.

2. 2. A piston accumulator according to claim 1, characterized in that one piston part (13) facing one of the medium chambers (14) has a guide band (19) on its outer periphery and that the further piston part (15) facing the further medium chamber (16) has a further guide band (21) and a ring seal (25) arranged on the outer periphery of the further piston part (15) adjacent to the guide band (19) of the one piston part (13).

3. 3. A piston accumulator according to claim 1 or 2, characterized in that the two piston parts (13, 15) define between them an intermediate annular space (25) which contains a medium of one medium chamber (14), in particular in the form of a working gas.

4. 4. A piston accumulator according to claim 1, characterized in that the distance between the two disk-shaped piston parts (13, 15) or the distance between the two guide bands (19, 21) is greater than ⅓ of the diameter of each of the two piston parts (13, 15) and less than said diameter.

5. 5. Piston accumulator according to any one of claims 1 to 4, characterized in that the disc thickness of the piston part (13) with the guide band (19) is smaller than the disc thickness of the further piston part with the further guide band (21) and the sealing ring (23).

6. 6. A piston accumulator according to claim 1, characterized in that the piston rod (17) with two opposing shoulders (27) merges flatly into the mutually facing free end faces (29, 31) of the two piston parts (13, 15).

7. 7. A piston accumulator according to any one of claims 1 to 6, characterised in that the piston rod (17) engages the respective piston portion (13, 15) with its mutually spaced end regions and is fixed to the associated piston portion (13, 15) along said end regions via a threaded portion (33) by means of a lock nut (35).

8. Piston accumulator according to any one of the preceding claims, characterised in that the discs of the two piston parts (13, 15) are provided with annular recesses (37).

9. 9. The piston accumulator according to claim 1, wherein the annular recess (37) extends concentrically to a central recess (39) through which the respectively allocable end regions of the piston rod (17) carrying the locking nut (35) pass.

10. 10. A piston accumulator according to claim 1, characterized in that the two guide bands (19, 21) are identically constructed and have, in the axial direction, a greater extension than the sealing ring (23), which is preferably made of an elastomer.

Images