device

Abstract

Device comprising at least a separating device (12) received in a device housing (10), which has a bellows body (14) with individual bellows folds (16) which fluid-tightly separates two media spaces (18, 20) from each other within the device housing (10), characterized in that a monitoring device (22) for determining the respective position of the bellows body (14) in the device housing (10) is provided, which has a displacement sensor (24) which is based on the physical principle of magnetostriction.

Description

The invention relates to a device, comprising at least one separating device accommodated in a device housing, which separating device has a bellows body with individual bellows folds, which separates two media spaces from one another in a fluid-tight manner within the device housing.In addition to wind boilers, weight and spring accumulators and membrane, bladder or piston accumulators, there are designs in which a bellows with individual connected bellows folds, such as a corrugated or bellows made of metal or plastic, is used as the separating element of a separating device. The advantage of bellows made of special plastics, such as PTFE, for example, lies in the better media and temperature resistance compared with conventional elastomer materials. The advantage of metal bellows generally includes a particular resistance to media and temperature and the possible field of application is extended by an extremely high tightness for media including gases, i.e. an absolute tightness in connection with liquids and a technical gas tightness is achieved. The last-mentioned advantage makes the metal bellows accumulator unique compared to all other accumulator types of construction and is particularly important when the loss of gas from a hydraulic accumulator is to be virtually eliminated and / or its operating media must not be contaminated with the smallest amounts of a working gas from the accumulator. The best possible media tightness for liquids and gases leads to metal bellows accumulators also being excellently suitable for being used as media separators.When corrugated and diaphragm bellows made of metal or plastic, referred to below for short as bellows bodies or bellows, are used, each with a separating element made of individual, coherent bellows folds between two media sides, in particular between a gas side and a liquid side, for example in hydropneumatic accumulators, their extended and compressed lengths must be taken into account in particular in conjunction with the prevailing operating pressures and temperatures. In addition, bellows can only withstand very specific differential pressures between the inner side of the bellows and the outer side of the bellows, depending on the design. If the respectively permissible differential pressures are exceeded, the bellows function may be lost due to a failure of the bellows wall, for example due to a crack, with the inclusion of a hydraulic supply circuit to which such bellows bodies are usually connected. In the case of an accumulator filled with nitrogen gas, this would lose the gas pre-filling pressure and thus the accumulator function in the event of a bellows breakage. If the system were to function as a media separator or as a conveying device for media, the media to be separated would unintentionally mix with one another in the event of failure. Even if a bellows body should not be destroyed immediately by an unacceptably high differential pressure, but rather is merely damaged beforehand, i.e. the separating function is initially maintained, the bellows wall still fails earlier or later, depending on the operating mode. Therefore, when designing bellows accumulators as one of the possible separating devices with the highest priority, it should be ensured that impermissible bellows lengths and differential pressures can not occur at any of the possible operating states (pressure and temperature). If it is stated that preferably no differential pressures prevail at the bellows, then, however, those differential pressures are excluded here which are caused by the spring properties of the bellows structure in conjunction with compression or stretching of the bellows folds. These bellows-specific differential pressures are generally dimensioned to be so small that they can be easily tolerated by the bellows.With regard to the above problems, it has already been proposed according to the teaching of DE 100 09 865 B4 in a hydropneumatic pressure accumulator, in particular in the form of a pulsation damper, to provide an accumulator housing which contains a gas space for receiving a gas filling generating a prestress pressure and an oil space, wherein a bellows or metal bellows separating the gas space and the oil space from one another is provided, which bellows is closed off at one end by an end plate and is connected at its other end to the accumulator housing in such a way that its interior space forms the oil space. Furthermore, an oil passage formed in the wall of the reservoir housing is introduced as a connection side, which opens into the oil chamber. By means of a stop device limiting the movement of the end plate of the bellows, which stop device has a first stop which is formed by a tubular body extending in the interior of the metal bellows along the inner side thereof from the mouth of the oil duct as far as the vicinity of the inner side of the end plate, and a second stop which is formed by a second tubular body extending concentrically with the tubular body and extending from the wall of the storage housing in the gas space as far as the vicinity of the outer side of the end plate of the metal bellows, a mechanical stroke limitation for the bellows is created on both sides, so that predeterminable minimum or maximum bellows lengths are not exceeded both for the contraction and for the extraction of the bellows. Since the free travel path is limited during stretching and compression of the bellows in this way, unacceptably high pressure differences cannot occur at the same time and, in this respect, the bellows is prevented from failure to the extent outlined above. Nevertheless, an additional mechanical stress on the one separating device designed as a bellows occurs, caused by the mechanical stop at the respective stroke limit, which can reduce the service life of the bellows.In view of these uncertainties in the operation of the bellows, it is expedient to monitor it in more detail. Thus, it is already known from EP 3 475 584 B1 to determine, in the case of a hydropneumatic piston accumulator, the respective piston position which the piston assumes at a given liquid pressure in the oil-side working chamber, so that in this way it is possible to determine about the level of the filling pressure of the working gas in the associated working chamber and thus to monitor the piston accumulator for proper functionality.For this purpose, a hydropneumatic piston accumulator is provided, having an accumulator housing defining a housing longitudinal axis, in which an accumulator housing can be moved longitudinally between two opposite housing covers, which in the housing separates a medium chamber for a compressible medium, such as a working gas, from a further medium chamber for an incompressible medium, such as hydraulic oil, and has at least part of a magnetostrictive measuring system of a displacement measuring device, which magnetostrictive measuring system continuously determines the respective position of the piston in the housing, wherein a rod-like guide is arranged in a stationary manner in the accumulator housing, which guide completely reaches through the piston in each of its displacement positions in the accumulator housing and along which the piston is guided displaceably until it abuts against one of the two housing covers in each case, wherein the piston, which has a permanent magnet as part of the measuring system, is sealed with respect to this guide by means of a sealing device, the two media spaces are separated from one another in a sealing manner, wherein a hollow rod forming the guide has a preferably pressure-tight, circular cladding tube, wherein the guide of the piston has a waveguide of the magnetostrictive measuring system, wherein the storage housing has a cylinder tube which is closed at both ends by the housing covers, wherein the cladding tube is fixed at one open end to one of the housing covers, and wherein the pulse transducer which is connected to the waveguide of the magnetostrictive measuring system and has a pulse transmitter / receiver is arranged on said cylinder tube.Magnetostrictive displacement transducers used for this purpose are basically used for measuring the distance between two points. The sensor used here has a fixed base, a waveguide, a movable permanent magnet and a transducer which converts a mechanical oscillation into an electrical signal. The measurement result of the displacement sensor is a position determined by magnetostriction. Such magnetostrictive sensor systems are described by way of example in EP 2 556 344 B1 and EP 2 549 242 B1.Proceeding from this prior art, the object of the invention is to improve the known solutions to the effect that unacceptably high compressive and tensile stresses for the bellows body as the separating device during operation of a device can be avoided.An object in this respect is achieved by a device having the features of claim 1 in its entirety. As a result of the fact that, according to the characterizing part of patent claim 1, a monitoring device for determining the respective position of the bellows body in the device housing is provided, which monitoring device has a displacement transducer which is based on the physical principle of magnetostriction, the retraction and extraction movements of the bellows body within the device housing which occur during operation of the device can be monitored without delay, so that undesired overstretching and compressions of the associated bellows folds in the direction of their respective maximum deflection within the scope of extraction or retraction of the bellows body are reliably avoided.Since the bellows body with its individual bellows folds is exposed to different fluid pressures on both media chambers in the device housing during operation of the device, the sensor data of the magnetostrictive displacement transducer can be used, for example using media conveying devices, such as feed pumps, to control the respective fluid pressure in the associable media chamber in any case such that the overloading described above does not occur at all at the bellows body. In this respect, the occurrence of undesired pressure differences on the bellows body, which can have a damaging influence on the latter, can be avoided.It has been shown to be particularly advantageous in the realization of the device according to the invention that the magnetostrictive displacement transducer can be integrated into the device housing in such a way that no further sealing device is necessary between the components of the displacement transducer system that can be moved relative to one another, so that this also cannot fail in this respect with the other consequence of leaks occurring. This thus does not correspond to the prior art.If, contrary to expectation, the device should fail and therefore an overall hydraulic installation to which such devices are connected fails, a fault can be detected in good time at any rate by means of the monitoring device in order to thus exclude subsequent damage.In a preferred embodiment of the device according to the invention, it is provided that the magnetostrictive displacement transducer has a waveguide in the form of a tube closed on the bottom side, in which tube a conductor is accommodated and which extends with its other free end from a fixed base and from a housing part in the direction of the bellows body. In this way, a slender monitoring device is provided which can be connected to the device with the separating device in a space-saving manner.In a further preferred embodiment of the device according to the invention, it is provided that the magnetostrictive displacement transducer further comprises a permanent magnet which, by means of a rod body which engages on the bellows body, is preferably firmly connected thereto, engages in the housing part of the waveguide in each insertion or extraction position of the bellows body. In this way, a continuous measurement value acquisition is made possible over the entire predefinable movement range of the bellows body with its individual bellows folds.In a particularly preferred embodiment of the device according to the invention, it is provided that the rod body is formed hollow and carries at its free end the permanent magnet which annularly surrounds the tube of the waveguide. Due to the hollow design of the rod body, only slight masses have to be moved during the displacement movement of the bellows body, which helps improve the quality of the measurement results.In a further particularly preferred embodiment of the device according to the invention, it is provided that the hollow rod body, held free of seals, is guided along the tube, which is movable back and forth in its longitudinal direction. Accordingly, no seals are necessary for the operation of the monitoring device, which could otherwise wear and, in particular if they are formed from an elastomer material, can lead to obstructions during the measurement value acquisition.In a further preferred embodiment of the device according to the invention, it is provided that the interior of the hollow rod body and the interior of the housing part for the waveguide are permanently connected in a fluid-conducting manner to one of the media spaces, which is separated from the other media space in the device housing by means of the bellows body. Due to this medium-carrying connection, pressure-compensated, non-inhibitory operation is made possible during operation of the device with the monitoring device, so that no corruption of the measurement results occurs.In a further particularly preferred embodiment of the device according to the invention, it is provided that the housing part of the waveguide is firmly connected as a hollow cylindrical connection body to the device housing, preferably via a screw-in section, and that the free length of the housing part is selected to be greater than the free travel path of the bellows body between a maximum inserted or pulled-out position in the device housing. In this way, the monitoring device can be easily replaced from the device housing and can also be mounted again, so that a simple replacement possibility is provided, for example if, in the event of failure of the monitoring device and / or of the device with the separating device, these are to be replaced with new components. The selected structural lengths also ensure that in each position of the bellows body within the device housing that the latter is captured in its movement or position.In a further preferred embodiment of the device according to the invention, it is provided that the waveguide is led out of the housing part at the free end of the tube, preferably for the purpose of electrically connecting a transducer of the magnetostrictive displacement transducer. In this way, the transducer, which converts a mechanical oscillation into an electrical signal, can be arranged outside the device, which can benefit the quality of the measurement value acquisition.In a further particularly preferred embodiment of the device according to the invention, it is provided that the bellows folds of the bellows body in the fully retracted state are accommodated in an annular space which extends between a closure body of the device housing and its cylindrical inner wall. In this way, the bellows body with its bellows folds in the fully retracted state is supported against an undesired bending when the folds are placed on one another in both directions outwards and inwards. In this way, a receiving space is also created, into which the bellows folds can be stacked or folded in in a space-saving manner.In a further preferred embodiment of the device according to the invention, it is provided that a further closing body is present, and that the two closing bodies of the device housing, which is of hollow cylindrical design, close off the latter towards the outside, and individual channels, in particular for the fluid guidance, are introduced into the closing parts, which open out in one of the attributable media spaces. In this way, a massively designed device housing can be formed which also satisfies high fluid pressure forces.Furthermore, the invention relates to the use of a magnetostrictive displacement transducer in a device as presented above for monitoring a bellows body which has individual bellows folds for the purpose of preventing material-damaging overstretching or compression of the bellows folds, during their expansion in the direction of a maximum pull-out position or during their contraction in the direction of a maximum pull-in position. The bellows body with its bellows folds can be designed such that a maximum pull-out position is reached when the bellows body with closing wall components ends at an opposite stop within the device housing or goes into a block in a maximum pull-in position, in which the individual bellows folds are in contact with one another lying one above the other. In order to avoid such material-requiring stop positions, however, the bellows body can be "moved" by means of the monitoring device in such a way that stop positions in this respect are not currently assumed during operation.The device according to the invention is explained in more detail below with reference to an exemplary embodiment. In this context, the figures show in schematic and not to scale FIG. 1 is a longitudinal section through the device as a whole; FIGS. 2 and 3 each in front view show the bottom- or head-side connection region of the device according to FIG. 1 in each case in front view.According to the illustration according to FIG. 1, the device has a device housing 10 with a separating device 12 accommodated therein. the separating device 12 has a bellows body 14 with individual bellows folds 16. In FIG. 1, the bellows body 16 is shown in its fully retracted position, in which the bellows folds 16 are blocked, i.e. lie one above the other in a sequence. In the extended state of the bellows body 14 or of the bellows, the folds 16 are pulled apart and form a zigzag-shaped bellows (not shown). The design in this respect is conventional, so that it will not be discussed here any more.The bellows body 14 separates two media spaces 18, 20 from one another in a fluid-tight manner within the device housing 10, wherein in the bellows position according to FIG. 1, the media space 18 assumes its maximum position and, in contrast, the media space 20 assumes its smallest volume.The device has a monitoring device 22 for determining the respective position of the bellows body 14 in the device housing 10. In this way, the magnetostrictive displacement transducer 24 has a waveguide 26 in the form of a tube 28 which is closed on the bottom side and in which a conductor (not shown) is accommodated. The tube 28 extends from its upper free end, as viewed in the direction of view of FIG. 1, starting from a fixed base 32 and comprises a jacket-shaped housing part 34 in the direction of the bellows body 14. Instead of a copper conductor, a nickel wire could also be used. A suitable magnetostrictive displacement transducer 24 is offered by the property right as a linear displacement transducer under the designation HLT 2100-R1.The magnetostrictive displacement transducer 24 further has an annular permanent magnet 36 which, by means of a rod body 38 which engages on the bellows body 14 and is preferably firmly connected thereto, engages in the hollow cylindrical housing part 34 of the waveguide 26 in each insertion or extraction position of the bellows body 14. The hollow rod body 38 carries on its free end 40 on the inside the annular permanent magnet 36, which comprises the rod-shaped waveguide 26 in each displacement position of the bellows body 14.As can be further seen from FIG. 1, the hollow rod body 38 is guided so as to be movable back and forth in the longitudinal direction of the tube 28, held free of any seals. The interior 42 of the hollow rod body 38 and the interior 44 of the housing part 34 for the waveguide 26 are permanently connected in a pressure-balanced manner in a fluid-conducting manner to one 18 of the media spaces 18, 20, which is separated by means of the bellows body 14 from the respective other media space 20 in the device housing 10. For the media connection in this regard, the hollow rod body 38 has at least one fluid passage 46 on the foot side and adjacent to the bellows body 14, for example in the form of a bore which passes through the wall of the hollow rod body 38.The housing part 34 of the waveguide 26 is firmly connected as a hollow cylindrical connection body to the device housing 10 along a screw-in section 48, wherein the free length of the housing part 34, in coaxial arrangement with the longitudinal axis 50 of the device, is as a whole greater than the free travel path of the bellows body 14 between a maximum insertion and extraction position in the device housing 10; likewise in coaxial arrangement with the longitudinal axis 50. The wire-shaped conductor of the waveguide 26 is led out of the housing part 34 at the upper free end 30 of the tube 28, so that a connection point 52 results for the connection of a transducer, not shown, of the magnetostrictive travel sensor 24.For the guidance of conductor components in this respect, the upper end of the jacket-shaped housing part 34 is hermetically sealed off by a hexagonal screw 54 which also forms the fixed point or base 32 for the tube 28. For a hermetic seal, an annular seal 56 can be provided on the free upper end of the housing part 34.The bellows folds 16 of the bellows body 14 are accommodated in the fully retracted state, as shown in FIG. 1, in an annular space 58 which extends between a closure body 60 of the device housing 10 and its cylindrical inner wall 62. A closure plate 64 of the bellows body 14, which extends transversely to the longitudinal axis 50 of the device as a whole, has a guide strip 66 on the circumferential side, which, as shown in FIG. 1, is provided with fluid-conducting interruptions and otherwise bears against the inner wall 62 of the device housing 10 for guiding the bellows body 14. On the opposite side, the bellows body 14 is fixed on the foot side to a receiving ring 68, in particular is firmly welded to the latter and is fixed in this way within the device housing 10. The annular chamber 58 is connected to the first medium chamber 18 so as to conduct medium to the outside, and in this respect the annular chamber 58 is arranged adjacent to and opposite the outer side of the bellows folds 16. The inside of the bellows folds 16 is in turn connected to the second media chamber 20 in a media-conducting manner towards the inside.The end plate 64 of the bellows body 14 carries, concentrically to the longitudinal axis 50, a receiving sleeve 70 in which the lower end of the rod body 38 engages. Specifically, the rod lower end of the rod body 38 may be screwed into a thread on the inner circumferential side of the receiving sleeve 70. The receiving sleeve 70 is an integral component of the cylindrical end plate 64 and, when the rod body 38 is fully inserted into the receiving sleeve 70, the bottom end of the rod body 38 sits on the top side of the end plate 64. The lower end body 60 is screwed as a solid screw-in body flush into the otherwise cylindrically designed device housing 10 and a circumferential ring seal 74 is inserted between the screw-in section 72 in this respect and the stationary receiving ring 68 for the bellows body 14, which ring seal seals the second media chamber 20 with respect to the environment.At the upper free end of the cylindrical device housing 10, a further end part 76, comparable to the first end body 60, is screwed in along a screw-in section 72' and is correspondingly sealed off by means of an associated annular seal 78, which now seals the interior of the first media chamber 18 with respect to the environment. According to the illustration according to FIG. 1, the housing part 34 is seated flush on the upper side of the further terminating body 76 via a shoulder 80. Furthermore, below the screwing-in section 48, a sealing ring 82 is introduced along the inner circumferential side of the further end part 76, which ring carries out a seal between the further end part 76 and the housing part 34 in this connection region.The housing part 34 narrows in steps in the direction of the bellows body 14 in the region of engagement with the further terminating body 76; however, it holds free in the direction of the underside of the further terminating body 76 a receptacle 84 of enlarged diameter, the geometry of which is determined in such a way that the outer periphery of the receptacle sleeve 70 can engage in the enlarged receptacle 84 in such a way that at least the upper side of the terminating plate 64 comes into contact with a circumferential stop surface 84 on the underside of the further terminating part 76. a further stop surface 86 which is annular in this respect is also present on the upper side of the terminating body 60, which forms a stop insofar as the terminating plate 64 assumes its lowermost position according to the illustration in FIG. 1. Between the respective annular stop surfaces 84, 86, a front-side fluid depression 88 is introduced in the respective attributable closure body 60, 76, which depression serves for improved filling of the respective media chamber 18, 20, provided that the closure plate 64 assumes a stop position on the respective closure body 60, 76 in its fully extended or fully retracted position.As FIG. 2 shows, the lower end body 60 has four fluid channels 90 which are diametrically opposite one another with respect to the longitudinal axis 50 and serve for the supply and discharge of a medium into and out of the second medium chamber 20. The channels 90 in this respect are introduced as continuous branch channels into the end body 60 parallel to the longitudinal axis 50 of the overall device. While one part of the channels 90 serves only for supplying fluid and the other part of the discharge, it may also suffice for the reason to provide only a single channel 90 for the supply and discharge of fluid. Otherwise, fluid channels 90 left free can also serve for the introduction of a sensor system, not shown, in order to be able to carry out temperature and / or pressure measurements in this way. Furthermore, the cover-like closing body 60 has on its underside two handles 92 diametrically opposite each other with respect to the longitudinal axis 50, which handles serve for the engagement of a tool, not shown in detail, with which the closing body 60 can be screwed into and out of the cylindrical device housing 10 via its screw-in section 72.The further closing body 76 shown in FIG. 3, which is likewise screwed flush into the cylindrical device housing 10, has, in addition to the monitoring device 22, a central fluid channel 94 which serves for the supply and discharge of a further fluid into the first media space 18 and which completely reaches through the further closing body 76 parallel to the longitudinal axis 50. In front of and behind the monitoring device 22, further channels 96 can be introduced into the closure body 76, preferably again for defining a sensor system, not shown in detail. In this respect, too, the further end body 76 has handles 92 diametrically opposite each other with respect to the longitudinal axis 50, for example in the form of engagement bores which serve for fixing an actuating tool, not shown.The apparatus shown in FIG. 1 can be operated, for example, within the scope of a conveying or compacting device. If fluid is supplied and discharged at intervals into the media chamber 18 via the additional fluid channel 94 from a pump or delivery device, not shown in detail, the fluid located in the second media chamber 20, for example in the form of gas, such as hydrogen gas, is compressed in the second media chamber 20 by means of the end plate 64, for which purpose the bellows body 14 is displaced from an extended position, not shown, into its lower stop position according to FIG. 1. Medium, such as hydrogen gas, previously located in the second medium chamber 20 is then pushed out of the device, optionally in compressed form, via the respective medium-carrying fluid channel 90. A new cycle then begins, in which the first medium chamber 18 is kept pressureless or is subjected to reduced pressure, so that, if appropriate, under an prevailing medium pressure in the lower fluid channels 90, the closure plate 64 again moves upward in the direction of view of FIG. 1, and the bellows body 14 with its bellows folds 16 is thereby drawn out. To this end, the first media chamber 18 then again decreases and the second media chamber 20 increases in size, to be precise as fluid is intended to be accommodated in the second media chamber 20. A new cycle then begins and the fluid is expelled from the device from the second media chamber 20.The bellows movements concerned are continuously monitored by the monitoring device 22 and corresponding position reports and reports on the functionality of the device are passed on to an evaluation electronics, not shown, the component of which is the transducer of the magnetostrictive displacement sensor 24. However, the described monitoring device 22 can also be used in a meaningful manner if the device according to FIG. 1 is to be operated as a conventional bellows accumulator in an overall hydraulic system.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 100 09 865 B4

[0004] EP 3 475 584 B1

[0005] EP 2 556 344 B1

[0007] EP 2 549 242 B1

[0007]

Claims

Device, comprising at least one separating device (12) accommodated in a device housing (10), which separating device has a bellows body (14) with individual bellows folds (16), which separates two media spaces (18, 20) from one another in a fluid-tight manner within the device housing (10), characterized in that a monitoring device (22) for determining the respective position of the bellows body (14) in the device housing (10) is provided, which monitoring device has a displacement transducer (24), which is based on the physical principle of magnetostriction.Device according to claim 1, characterised in that the magnetostrictive displacement transducer (24) has a waveguide (26) in the form of a tube (28) closed on the bottom side, in which tube a conductor is accommodated and which extends with its other free end (30) from a fixed base (32) and from a housing part (34) in the direction of the bellows body (14).Device according to claim 1 or 2, characterised in that the magnetostrictive displacement transducer (24) further comprises a permanent magnet (36), which engages in the housing part (34) of the waveguide (26) by means of a rod body (38), which engages on the bellows body (14), preferably is firmly connected thereto, in each insertion or extraction position of the bellows body (14).Device according to one of the preceding claims, characterized in that the rod body (38) is of hollow design and carries at its free end (40) the permanent magnet (36) which annularly surrounds the tube (28) of the waveguide (26).Device according to one of the preceding claims, characterized in that the hollow rod body (38), held free of seals, is guided along the tube (28), which is guided so as to be moveable back and forth in the longitudinal direction thereof.Device according to one of the preceding claims, characterized in that the interior (42) of the hollow rod body (38) and the interior (44) of the housing part (34) for the waveguide (26) are permanently connected in a fluid-conducting manner to one (18) of the media spaces (18, 20), which is separated from the other media space (20) in the device housing (10) by means of the bellows body (14).Device according to one of the preceding claims, characterized in that the housing part (34) of the waveguide (26) is fixedly connected to the device housing (10) as a hollow cylindrical connection body, preferably via a screw-in section (48), and in that the free length of the housing part (34) is selected to be greater than the free travel path of the bellows body (14) between a maximum pushed-in or pulled-out position in the device housing (10).Device according to one of the preceding claims, characterized in that the waveguide (26) is led out of the housing part (34) at the free end (30) of the tube (28), preferably for the purpose of electrically connecting a transducer of the magnetostrictive displacement transducer (24).Device according to one of the preceding claims, characterized in that the bellows folds (16) of the bellows body (14) in the fully retracted state are accommodated in an annular space (58) which extends between a terminating body (60) of the device housing (10) and the cylindrical inner wall (62) thereof.Device according to one of the preceding claims, characterized in that a further closing body (76) is present and in that the two closing bodies (60, 76) of the device housing (10), which is of hollow cylindrical design, close off the latter towards the outside and individual channels (90, 94), in particular for the fluid guidance, are introduced into the closing parts (60, 76), which open out in one of the attributable media spaces (18, 20).Use of a magnetostrictive displacement transducer (24) in a device, in particular according to one of Claims 1 to 10, for monitoring a bellows body (14) which has individual bellows folds (16) for the purpose of preventing material-damaging overstretching or compression of the bellows folds (16), during their expansion in the direction of a maximum pull-out position or during their contraction in the direction of a maximum pull-in position.

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