ARRANGEMENT FOR TRANSMITTING AND/OR RECEIVING AN ULTRASONIC, WANTED SIGNAL AND ULTRASONIC, FLOW MEASURING DEVICE

Abstract

An arrangement for transmitting and/or receiving an ultrasonic, wanted signal in a measured medium, comprising a vibration decoupling element for securing at least one ultrasonic transducer in a containment, characterized in that the vibration decoupling element has a platform for securing the vibration decoupling element to a sensor nozzle or to the containment and a second interface for securing an ultrasonic transducer. Between the second interface and the platform a vibration decoupling structural element is arranged, which structural element is embodied as a solid body, which has one or more interfaces with other elements of the vibration decoupling element, especially with the second interface for securing the ultrasonic transducer and/or the platform, and wherein the structural element (11, 39, 55, 75) has an as much as possible spherical-, ellipsoidal-, toroidal- or polyhedral shape.

Claims

1-15. (canceled)

16. An arrangement for transmitting and/or receiving an ultrasonic, wanted signal in a measured medium, comprising: at least one ultrasonic transducer; and a vibration decoupling element for securing said at least one ultrasonic transducer in a containment, wherein: said vibration decoupling element or said at least one ultrasonic transducer via a coupling surface issues ultrasonic, wanted signals toward a measured medium; and wherein the said vibration decoupling element has a first interface, where said vibration decoupling element is connectable to the containment, especially to a measuring tube or to a tank, or to a sensor nozzle on the containment, which containment is partially or completely filled with measured medium; the amplitude of the wanted signal transmitted in the measured medium under reference conditions and in the frequency range of the wanted signal is more than 20 dB greater than the amplitude of the disturbance signal transferred via the interface and via the wall of the containment said vibration decoupling element has a platform for securing said vibration decoupling element to said sensor nozzle or to the containment and a second interface for securing said at least one ultrasonic transducer; between said second interface for securing said at least one ultrasonic transducer and said platform at least one vibration decoupling structural element is arranged, which structural element is embodied as a solid body, said solid body has one or more interfaces with other elements of said vibration decoupling element, especially with said second interface for securing the ultrasonic transducer and/or the platform; and said structural element has an as much as possible spherical-, ellipsoidal-, toroidal- or polyhedral shape.

17. The arrangement as claimed in claim 16, wherein: the amplitude of the wanted signal transmitted in the measured medium under reference conditions and in the frequency range of the wanted signal is more than 30 dB, especially more than 40 dB, greater than the amplitude of the disturbance signal transmitted via the first interface and via the wall of the containment.

18. The arrangement as claimed in claim 16, wherein: said vibration decoupling element is monolithically constructed.

19. The arrangement as claimed in claim 16, wherein: at least one connecting element is arranged between the structural element and other elements of said vibration decoupling element; and said connecting element is embodied as a rod-shaped connecting element.

20. The arrangement as claimed in claim 16, wherein: at least one connecting element is arranged between said structural element and other elements of said vibration decoupling element; and said connecting element is embodied as a membrane.

21. The arrangement as claimed in claim 16, wherein: the length of said rod-shaped connecting elements corresponds to greater than or equal to lambda/8, preferably greater than or equal to lambda/4, of the ultrasonic signal.

22. The arrangement as claimed in claim 16, wherein: said vibration decoupling element is a metal component and at least in certain regions is composed of one of the following materials: a) a steel, especially a stainless steel or tool steel; b) titanium or a titanium alloy; c) a nickel based alloy; d) aluminum or an aluminum alloy; e) a chromium-cobalt-molybdenum alloy; f) a bronze alloy; g) a noble metal alloy; h) a copper alloy.

23. The arrangement as claimed in claim 16, wherein: said vibration decoupling element is sectionally composed of a plurality of weldable metals and/or metal alloys, which are connected with one another seamlessly, especially without adhesive seam, weld seam, braze seam or solder seam.

24. The arrangement as claimed in claim 16, wherein: said vibration decoupling element has an integrally formed passageway for guiding an electrical current- and/or signal cable, which passageway extends through the structural element.

25. The arrangement as claimed in claim 16, wherein: between said seat and said platform an open structure is provided, wherein one or more structural elements are parts of said open support structure.

26. The arrangement as claimed in claim 16, wherein: said vibration decoupling element is produced by selective laser melting.

27. The arrangement as claimed in claim 16, wherein: said vibration decoupling element is insertable into a hole in the containment, especially without connection via a sensor nozzle.

28. The arrangement as claimed in claim 16, wherein: said one or more structural elements are essentially solid, wherein the mass of a structural element is at least 80%, for example, at least 90% and preferably at least 95% of the mass of an equally shaped, solid reference body composed of the same material as the structural element.

29. An ultrasonic, flow measuring device having a measuring tube and at least two arrangements as claimed in claim 16, mounted on said measuring tube.

30. An ultrasonic, fill-level measuring device having at least one arrangement as claimed in claim 16 mounted on a container wall.

Description

[0068] The invention will now be explained in greater detail based on some examples of embodiments presented in the drawing, the figures of which show as follows:

[0069] FIG. 1 schematic representation of an ultrasonic, flow measuring device;

[0070] FIG. 2 lateral, perspective view of a first embodiment of an arrangement of the invention;

[0071] FIG. 3 sectional view of the arrangement of FIG. 2;

[0072] FIG. 4 installed position of the arrangement of FIG. 2 in a sectioned measuring tube;

[0073] FIG. 5a model representation of a first defined structural element;

[0074] FIG. 5b model representation of a second defined structural element;

[0075] FIG. 5c model representation of a third defined structural element;

[0076] FIG. 6 lateral, perspective view of a second embodiment of an arrangement of the invention;

[0077] FIG. 7 sectional view of the arrangement of FIG. 6;

[0078] FIG. 8 installed position of the arrangement of FIG. 6 in a sectioned measuring tube;

[0079] FIG. 9 installed position of the arrangement of FIG. 6 in a sectioned measuring tube from another perspective;

[0080] FIG. 10 lateral, perspective view of a third embodiment of an arrangement of the invention;

[0081] FIG. 11 sectional view of the arrangement of FIG. 10

[0082] FIG. 12 installed position of the arrangement of FIG. 10 in a sectioned measuring tube;

[0083] FIG. 13 lateral, perspective view of a fourth embodiment of an arrangement of the invention;

[0084] FIG. 14 sectional view of the arrangement of FIG. 13;

[0085] FIG. 15 lateral, perspective view of the arrangement of FIG. 13, with a sensor cup instead of a resonator;

[0086] FIGS. 16a-f arrangement of FIGS. 13 and 14 supplemented by a membrane for protection against fouling;

[0087] FIG. 17 arrangement of FIGS. 13 and 14 supplemented by a membrane predominantly of spheres for protection against fouling;

[0088] FIG. 18 lateral, perspective view of the arrangement of FIG. 15, with a straight sensor cup instead of the inclined sensor cup.

[0089] FIG. 1 shows the general measuring principle of an ultrasonic, flow measuring device.

[0090] Ultrasonic, flow measuring devices are applied often in process and automation technology. They permit a relatively easy determination of volume flow and/or mass flow in a pipeline. Known ultrasonic, flow measuring devices work frequently according to the travel-time difference principle. In the case of the travel-time difference principle, the different travel times of ultrasonic waves, especially ultrasonic pulses, or so-called bursts, are evaluated relative to flow direction of the liquid. For this, ultrasonic pulses are sent, or transmitted, at a certain angle to the tube axis both with as well as also counter to the flow. From the travel-time difference, the average flow velocity can be determined along the ultrasound signal path and therewith, in the case of known flow state, and known diameter of the pipeline section, the volume flow.

[0091] The ultrasonic waves are produced and received with the assistance of so-called ultrasonic transducers 1. For this, the ultrasonic transducers 1 are mounted fixedly in the tube wall of the relevant pipeline section. Most often, the tube section is an integral unit of the flow measuring device and is referred to as measuring tube 2. Also clamp-on, ultrasonic, flow measuring systems are obtainable. The present invention concerns, however, ultrasonic, flow measuring devices, in the case of which the ultrasonic transducers are connected media contactingly with a media conveying measuring tube.

[0092] The ultrasonic transducers 1 include, normally, an electromechanical transducer element, e.g. a piezoelectric element. Furthermore, the ultrasonic transducers utilize a coupling layer for improved acoustic coupling and an adapting, or matching, layer, e.g. for gaseous media.

[0093] For reasons of stability under pressure, the measuring tube 2 is most often made of a metal, e.g. steel. In producing the one ultrasonic signal by an electromechanical transducer element of a first ultrasonic transducer 1a, a part of the ultrasonic signal can be transmitted to the measuring tube 2 and be transmitted as structure-borne sound to an electromechanical transducer element of a second ultrasonic transducer 1b. Such detects this structure-borne sound signal supplementally to the ultrasonic, wanted signal U that actually passed through the measured medium M, whereby a disturbance of the measuring occurs. Therefore, the ultrasonic transducer should as much as possible be decoupled from the structure-borne sound traveling in the measuring tube wall.

[0094] FIGS. 2-4 show a first arrangement 3 of the invention, which is arranged in a sensor nozzle 25 on a measuring tube 26 and which has an ultrasonic transducer 4. The ultrasonic transducer 4 is composed of a piezoelement 5 and a metal holding element 6, in which the piezoelement 5 is arranged. Holding element 6 includes a radiating plate 7 with a coupling surface E, from which the ultrasonic signal is emanated toward the measured medium. This radiating plate is connected via a pedestal 8 with a body 9, which holds the piezoelement 5.

[0095] Holding element 6 is connected with a vibration decoupling element 10. Vibration decoupling element 10 has a vibration decoupling geometry.

[0096] The vibration decoupling element 10 of FIGS. 2-4 includes a number of structural elements 11, which are embodied in this example partially as oscillatory masses. These structural elements 11 are solid bodies, respectively solid elements, each of which has one or more interfaces with other elements of the vibration decoupling element 10. The thickness of the material at the one or more interfaces is especially more than two times smaller than the thickness of the solid.

[0097] The vibration decoupling element is preferably monolithically constructed and includes in FIGS. 2-4 three toroids 12-14 connected with one another.

[0098] Additionally, there is a seat 17 having an interface, where the holding element 6 of the ultrasonic transducer is arranged. In such case, the interface is oriented for holding the ultrasonic transducer in such a manner that the ultrasonic signal is radiated from the holding element 6 arranged in the seat 17 at an angle not equal to 90° to the measuring tube axis A, especially at an angle α between 20-40° to a perpendicular T to the measuring tube axis A.

[0099] Each torus 12, 13 or 14 is connected with at least one adjoining torus by direct surface contact 15 or by a membrane 16. The ring thicknesses S of the tori 12-14 can be equally large or differently large. The same holds for the diameters D of the tori 12-14. In practice, in FIGS. 2-4, the torus 14, which adjoins the seat 17 with the interface for holding the ultrasonic transducer, has a smaller ring thickness S.sub.14 than the ring thicknesses S.sub.12 and S.sub.13 of the tori 12 and 13. Also, the diameter D.sub.14 of the torus 14 is smaller than the diameters D.sub.12 and D.sub.13 of the tori 12 and 13. The ring thicknesses and diameters of the tori 12 and 13 are, in contrast, equally large.

[0100] Especially advantageous is when the vibration decoupling element 10 additionally has a membrane 16 as structural element. The membrane 16 should be deflectable in the case of small pressure differences between the inner space 24 and the environment of the arrangement. A corresponding membrane is e.g. arranged in FIGS. 2-4 between the tori 12 and 13. It closes the inner space of the arrangement from the environment, and cares in the case of low pressure differences, due to its very small cross sectional area, for an ultimate acoustic decoupling between the tori 12 and 13. If the external pressure exceeds the interior pressure significantly, then torus 13 is pressed against torus 12. In this way, there arises a line-like, solid contact, which due to its very small bearing surface likewise cares for a good, structure-borne sound decoupling.

[0101] Torus 12 is connected by an areal contact region with a closure plate, or plate-shaped platform, 19. Closure plate 19 includes a flange-like edge region 20. This flange-like edge region 20 serves for mounting on or to a sensor nozzle flange 21.

[0102] The flange-like edge region 20 can additionally have a seal 22, which is arranged on the vibration decoupling element 10 and in the mounted state lies against the sensor nozzle flange 21. Closure plate 19 includes additionally a passageway 23 for feedthrough of electrical connections and signal cable to the ultrasonic transducer 1, i.e. to the piezoelement 5.

[0103] As evident in FIGS. 2-4, the illustrated vibration decoupling element 10 is a structure with three structural elements 11 having a closed outer contour. Located within the vibration decoupling element is a hollow space 24, which is filled or unfilled with a vibration damping medium (e.g. potting compound or metal powder).

[0104] The geometric totality of the vibration decoupling body and the toroidal oscillatory elements 12-14 in particular achieve a significant reduction or a complete canceling of the structure-borne sound. Therewith, the piezoelement can send US signals to the medium, without that a structure-borne sound signal is transmitted via the measuring tube to the receiver. In the case of the flow measurement of fluids, and especially in the case of the flow measurement of gases, the vibration decoupled seating of ultrasonic transducers is, consequently, especially advantageous.

[0105] The geometry shown in FIGS. 2-4 is only one of a large number of options for a special geometric construction of a vibration decoupling element, which is arranged between the actual ultrasonic transducer and the measuring tube nozzle.

[0106] Other structures of vibration decoupling elements will now be described.

[0107] Recently, the method of selective laser melting has been developed, with which such vibration decoupling elements are manufacturable. Also, other methods, modified compared with SLS, can be utilized, in the case of which e.g. a laser is not applied for the material buildup. These methods can be utilized for the manufacture of vibration decoupling bodies with the geometric relationships described in FIGS. 2-4 and below. Selective laser melting is known to those skilled in the art as a manufacturing method. Such method can be applied, in order to manufacture vibration decoupling bodies with complicated geometric elements. Bodies, which have been implemented by laser melting, have, due to the layered construction, a greater surface roughness than conventionally manufactured parts, for example, parts cast and then chip removal processed, i.e. machined. While the increased surface roughness can be lessened by subsequent working (e.g. grinding, sandblasting, shot peening or polishing), there is, due to the complex and partially back cut geometries within the vibration decoupling body, always a somewhat increased surface roughness of individual geometric elements to be found.

[0108] Manufacture by means of selective laser melting additionally permits manufacture of the holding element 6 as an integral component of the preferably monolithically-formed vibration decoupling element. It is possible also to combine a number of different materials with one another. Thus, e.g. the holding element can be manufactured of titanium and the vibration decoupling element of another metal. The transition between the materials can, in contrast to the case of conventional welding, brazing or soldering, be embodied seamlessly, i.e. without connecting seam or weld seam. It is, however, also possible to manufacture individual portions and to connect these with one another by some other method, e.g. by adhering, border crimping or screwing together. In this way, e.g. difficultly weldable locations can be handled otherwise.

[0109] Holding element 6 can also be embodied as a cup with a tubular lateral surface and a terminal, planar, radiation surface. The piezoelement is arranged in this cup. The lateral surface is connected with the vibration decoupling element 10. This variant is shown in FIGS. 15 and 18.

[0110] FIGS. 6-9 show another variant of an arrangement 46 of the invention with a vibration decoupling element 30. Arrangement 46 is arranged in an opening 45 of a measuring tube 42. This arrangement includes additionally an ultrasonic transducer 31 with a holding element 32 for seating and holding a piezoelement 33. Holding element 32 includes a radiating plate 34, which, analogously to FIGS. 2-4, is spaced from the platform 36 by a pedestal 35. Also in this embodiment, the holding element 32 can be otherwise embodied, such as e.g. in a cup-like embodiment 79, such as shown in FIG. 15. The piezoelement 53 is arranged in the cup-like holding element 79.

[0111] Holding element 32 of the ultrasonic transducer is secured in a seat 37, i.e. in a seat with an interface for holding the ultrasonic transducer and forming part of the vibration decoupling element 30. Seat 37 is held in a vibration decoupling manner. For this, the seat 37 is spaced from a dome-shaped platform 40 by a membrane 38 and by a structural element 39. Structural element 39 has, in such case, the shape of a sphere. Alternatively, the structural element can also be embodied shaped as an ellipsoid or a polyhedron.

[0112] In the case of the geometric character of the structural element 39, it can, analogously to FIG. 5, be a solid body, which has one or more interfaces with other elements of the vibration decoupling body, wherein the thickness of the material at the one or more interfaces is especially more than two times smaller than the thickness of the solid body.

[0113] In the example of an embodiment illustrated in FIGS. 6-9, the structural element 39 is connected by an areal contact region with the dome-shaped platform 40 and with the seat 37. Arranged on the edge of the seat 37 is the membrane 38, which extends radially from the seat 37 to the dome-shaped platform 40. Membrane 38 provides, due to its very small cross sectional area, for a good acoustic decoupling between seat 37 and dome-shaped platform 40.

[0114] The dome-shaped platform 40 serves for anchoring the vibration decoupling element to the measuring tube. Platform 40 is bounded by a conical edge 41. This serves for insertion of the vibration decoupling element 30 into a corresponding opening in a measuring tube 42. In this case, an outwardly extending measuring tube nozzle, such as in the case of the preceding variant, is not required. The membrane and the dome-shaped platform 40 bound a hollow space 43. This can either be filled with a special vibration damping medium, e.g. metal powder, or with a gas.

[0115] The opening within the measuring tube should, advantageously for the insertion of the vibration decoupling element with the platform 40, likewise be conically embodied. The connection between measuring tube and vibration decoupling element can be accomplished in this special example of an embodiment preferably by means of a laser- or electron beam welding method. In the case of the latter method, it is better to embody the interface not with conical but, instead, perpendicular walls, because the electron beam cannot be tilted relative to the component. However, the workpiece can also be inclined by a robot arm. In the case of each type of welding, it is to be noted that the introduced amount of heat should be as small as possible, in order to prevent damaging the piezoceramic by approaching the Curie temperature.

[0116] A passageway 44 extends through the dome-shaped platform 40, through the structural element 39 and through the seat 37. Within this passageway 44, a power supply cable and/or a signal transmission cable can be arranged, which is connected with the piezoelement 33.

[0117] Also the vibration decoupling element 30 shown in FIGS. 7-9 is preferably monolithically constructed. Also, the holding element 32 together with the vibration decoupling element can form a monolithic unit. The monolithic construction is, however, not absolutely required. Instead, individual elements of the vibration decoupling element can also be connected with one another by adhesive, welding, brazing, soldering or in other manner.

[0118] Also this vibration decoupling element is manufacturable by selective laser melting.

[0119] FIGS. 10-12 show a further example of an embodiment of an arrangement 49 of the invention having a vibration decoupling element 50, which is arranged in a sensor nozzle 58 on a measuring tube 59. An ultrasonic transducer 51 with a holding element 52 and a piezoelement 53 is constructed analogously as in FIGS. 2-4 and 7-9. The ultrasonic transducer 51 is arranged in a seat 54, i.e. a seat with an interface for holding, or setting, the ultrasonic transducer. The holding can be effected e.g. by adhering, soldering, brazing or welding the ultrasonic transducer to the interface of the seat 54. Known, however, are other options of holding, respectively setting. Such determines, due to its orientation, a certain angle, with which an ultrasonic signal is introduced into the measuring tube. Seat 54 is arranged on three structural elements 55, which, such as for the structural elements of FIGS. 2-4 and 7-9, are connected solidly with the seat 54. The structural elements 55 are, same as in FIGS. 2-4 and 7-9, solidly connected with a platform 56, which is embodied in this case as a plate shaped platform. The platform can, however, also have other embodiments.

[0120] The structural elements 55 are analogous to the structural element 39 of FIGS. 7-9 as regards their geometric character. In the concrete case, FIGS. 10-12 have sphere shaped, structural elements. They can, however, also be ellipsoidal elements or polyhedron shaped elements, which are connected by areal contact regions with the seat 54 and the platform 56. Platform 56 is embodied plate shaped with a central bulge. Arranged in the edge regions of the platform is a seal 57, which in the mounted state is arranged between the platform 56 and a sensor nozzle 58. The shown platform 56 is only one example of a series of other embodiments possible for this element of the vibration decoupling element 50. Thus, also in the case of this example, the platform can be embodied dome-shaped, analogously to FIGS. 7-9. In this case, then no sensor nozzle 58 is needed for connection of the vibration decoupling element but, instead, only a corresponding opening in the measuring tube 59.

[0121] The structural elements 55 are likewise another connected with one by areal contact regions. Furthermore, a structural element 55 as well as the platform 56 and the seat 54 include a passageway for an electrical current- and/or a signal cable. The structure of the vibration decoupling element 50 is an open structure. The means that between the individual elements, thus, among other things, also between the individual structural elements of the vibration decoupling element 50, free spaces are present. Thus, other than in the case of the preceding vibration decoupling elements, no closed hollow space is created, but, instead, the mentioned open structure. The open structure enables an especially preferred vibration decoupling, i.e. structure-borne sound decoupling, since oscillations are transmitted only via a very small amount of area.

[0122] In order to prevent fouling, the open structure can be surrounded with a membrane, thus e.g. a diaphragm, a thin sheet metal guard or a thin jacket of sheet metal, which e.g. is embodied cylindrical or conically. Such can, for example, be mounted to the platform 56, between platform 56 and measuring tube nozzle 58, to the measuring tube nozzle 58 or to the measuring tube 59.

[0123] In the case of an open structure without such a membrane, a contamination diagnosis of to what extent the open structure has contaminating deposits or the like can occur via an evaluation of the SNR ratio relative to a desired value.

[0124] Also this vibration decoupling element 50 can be produced by selective laser melting.

[0125] FIGS. 13-14 shows a further example of an embodiment for an arrangement 77 of the invention having a vibration decoupling element 70 for arrangement in a sensor nozzle, which can be embodied analogously to the sensor nozzle 58. In such case, the vibration decoupling is achieved by arranging between the seat 71 with an interface for holding the ultrasonic transducer 72 and the plate-shaped platform 73 an open structure 74. Open structure 74 is composed of individual, spherically shaped, structural elements and struts, i.e. rod-shaped connecting elements, 76. Located between these elements is a free space. A structural element in the form of an oscillatory body 75 is provided, which via the rod-shaped connecting elements 76 are connected with the seat 71 and the platform 73. One can see that the struts are bent.

[0126] This bending of the rod-shaped connecting elements 76 supplementally damps vibrations. The acoustic vibrations are absorbed by compression, stretching, bending and torsion of the bent, rod-shaped, connecting elements 76.

[0127] Furthermore, three oscillatory bodies 75 are provided. The oscillatory bodies 75 are structural elements of the vibration decoupling element 70 and are formed analogously to the structural elements 11 and 29. Thus, the oscillatory bodies 75 of FIGS. 13 and 14 are solid bodies, or solid elements, which have, in each case, one or more interfaces with other elements of the vibration decoupling element 70. The smallest cross section, or the smallest dimension, of these one or more interfaces can preferably be greater than two times less than the smallest cross section, or the smallest dimension, of an imaginary cuboid, which borders all-sides of the particular structural element. The thickness of the material at the one or more interfaces is especially more than two times smaller than the thickness of the solid bodies, or the smallest distance from the center of gravity of the solid body to its outer contour. For better representation of the dimensioning of the structural elements 11, the subject matter of FIGS. 5a-c can be taken into consideration.

[0128] The oscillatory bodies 75 are embodied sphere shaped in FIGS. 13 and 14. They can, however, also be ellipsoidal or polyhedron-shaped or as one encircling torus. Additionally, the oscillatory bodies 75 can during operation of the ultrasonic transducer oscillate between the seat 71 and the platform 73 relative to a straight connecting line both in the longitudinal direction, thus parallel to the connecting line, as well as also in a transverse direction, thus not parallel to the connecting line, whereby a vibration damping of various oscillation modes occurs. Provided in this element is additionally a passageway 78 for guiding a signal- and/or electrical current cable. This extends through the rod-shaped connecting elements 76 and the oscillatory body 75 and from the platform 73 to the seat 71.

[0129] As already provided in the case of the example of an embodiment of FIGS. 7-9, also the open structure of FIGS. 13-14 and generally all additional variants of open structures can be protected from fouling by an additional diaphragm or by a supplemental housing. In such case, this can be, among others, also a thin walled membrane, such as shown in FIGS. 16a-f.

[0130] FIG. 16a shows a thin walled membrane 80, in the form of a sheet structure with essentially uniform wall thickness, which prevents the penetration of particles into the open structure 74. Membrane 80 can have a preferred wall thickness of less than 2 mm and can preferably be of synthetic material, e.g. plastic, or especially preferably of metal. It extends between the platform 73 and the seat 71.

[0131] Open structure 74 is embodied as a support structure and can be understood functionally. The components of the open structure undertake essentially the support function of the ultrasonic transducer. In such case, the totality of the supporting components, thus e.g. only the structural elements 55 such as in FIGS. 10-12 or the structural elements 75 with the connecting elements 76 such as in FIGS. 13-15, forms no hollow space. The open support structure defines, thus, no closed hollow space. A membrane protecting against fouling does not, in such case, belong to the open support structure. There is no pressure difference present between media outside and within the open structure.

[0132] To the extent that the open structure is surrounded by a hollow membrane, the intermediate spaces of the open structure can be filled with another material. This material can be sound damping, potting material or quite especially preferably a metal powder, respectively metal dust. Also, although the open structure in the case of this variant is filled, it is, in spite of this, in effect, open structure. In contrast therewith, a free space in the form of a cavity, such as shown in FIGS. 2-4, is surrounded completely by structural and connecting elements. Such a structure is not effective as an open structure.

[0133] Although the membrane 80, thus, defines a hollow space, the open structure is retained.

[0134] FIG. 16b is a further development of FIG. 16a. In such case, there are arranged in the platform 73 two passageways 81, which connect the measuring tube interior with the hollow space formed by the membrane 80. This serves for pressure equalization. In an especially preferred, non-illustrated embodiment, a bellows or a filter is located on/in the holes, in order to protect the aforementioned hollow space against fouling and also plugging.

[0135] FIG. 16c is likewise a further development of FIG. 16a. In such case, the platform 73 includes two nozzles 82 with straight passageways, which extend from the underside of the platform to the edge of the nozzle. These are for filling or also emptying the hollow space formed by the membrane, e.g. with metal powder. At the same time, they could also be a mounting aid, for example, in order to mount a small circuit board.

[0136] In the further development shown in FIG. 16d, holes 83 are located in the membrane 80, so that the measured medium M can enter into the hollow space defined by the membrane and containing the open structure 74 arranged therein. Number, shape and size of the holes 83 are variable. These holes can also be e.g. somewhat smaller and also less in number. They serve also for pressure equalization and the membrane as a dirt barrier of the decoupling elements, i.e. the open structure.

[0137] As already mentioned above, as much as possible spherical-, electrical-, toroidal- and/or polyhedral structural elements have proved as especially suitable for sound decoupling. Shown in FIG. 16e is a further development of the membrane 80 with a sphere ring 84, thus a one ring arrangement of mutually adjoining, ordered spheres. The spheres can be connected with one another. This is, however, not absolutely necessary. Likewise an option, however, less preferably, is a ring of ellipsoids or a torus.

[0138] FIG. 16f shows a further development of FIG. 16e with a second sphere ring 85. This has preferably a size variance of the sphere radii relative to the first sphere ring 84. The sphere rings 84, 85 can be connected with one another, e.g. by means of thin, intermediate pieces of membrane. This is, however, not absolutely necessary.

[0139] FIG. 17 shows a further development of FIG. 16f, in the case of which the entire protective membrane/protective housing is composed essentially of spheres arranged adjoining one another. These have preferably a variety of sizes of sphere radii. The sphere rings can be connected with one another, e.g. by means of thin, intermediate pieces of membrane. This is, however, not absolutely necessary. The inner space is furthermore formed of the open structure illustrated in FIG. 16a, which is composed of different vibration decoupling- and connecting elements. In one of these elements, there is integrated, again, a cable passageway, which serves for guiding a signal- and/or an electrical current cable. Since, in this particular case, all spheres adjoin one another and support one another, an option here is to omit the central open structures.

[0140] FIG. 18 shows a further example of an embodiment of an arrangement of the invention analogous to FIG. 15. The sole difference is that, in the case of the variant of FIG. 15, the seat and the ultrasonic transducer are shown inclined, while in FIG. 18 the rotational axis of the seat and the ultrasonic transducer are oriented parallel to the longitudinal axis of the vibration decoupling system. In this way, a straight radiating of the ultrasonic signal into the containment is enabled. This is especially advantageous e.g. in the case of ascertaining fill level.

[0141] The vibration decoupling elements of FIGS. 13-14 are likewise manufacturable by selective laser melting. Additionally, in this way, also the membranes shown in FIG. 16 can be produced.

[0142] The dimensions of the examples of embodiments illustrated in FIGS. 1-4 and 6-18 hold, by way of example, for transducers with 200 kHz primary oscillation frequency and piezoelement dimensions of D=5 mm and h=1.5 mm.

[0143] Shown in FIGS. 1-4 and 6-17 are exclusively vibration decoupling elements, which provide an inclined position of the ultrasonic transducer unit, i.e. so-called angled transducers. Of course, also implementable with the described method are geometries, in the case of which the ultrasonic transducer is placed exactly perpendicularly for securement on the nozzle, and in the case of which the inclined position of the ultrasonic, measuring path is achieved by tilting of the measuring tube nozzles.

REFERENCE CHARACTERS

[0144] 1, 4, 31, 51, 72 ultrasonic transducer [0145] 2, 26, 42, 59 measuring tube [0146] 3, 46, 49, 77 arrangement [0147] 5, 33, 53 piezoelement [0148] 6, 32, 52 holding element [0149] 7, 34 radiating plate [0150] 8, 35 pedestal [0151] 9, 36 platform [0152] 10, 30, 50, 70 vibration decoupling element [0153] 11, 39, 55 structural element [0154] 12, 13, 14 torus [0155] 15 areal contact [0156] 16 membrane [0157] 17, 37, 54, 71 seat [0158] 19, 56, 73 plate shaped platform [0159] 20 flange-like edge region [0160] 21 sensor nozzle flange [0161] 22 seal [0162] 23 cable connection passageway [0163] 24 hollow space [0164] 25, 58 sensor nozzle [0165] 38 membrane [0166] 40 dome-shaped platform [0167] 41 conical edge [0168] 43 hollow space [0169] 44, 78 passageway [0170] 45 measuring tube wall opening [0171] 57 seal [0172] 74 open structure [0173] 76 rod-shaped connecting elements [0174] 75 oscillatory body, respectively structural element [0175] 79 cup-like holding element [0176] 80 membrane [0177] 81, 82 passageway [0178] 83 holes [0179] 84, 85 sphere ring [0180] 86 sphere membrane [0181] α angle [0182] T perpendicular [0183] A measuring tube axis [0184] S ring thickness [0185] D diameter [0186] U ultrasonic, wanted signal [0187] M measured medium [0188] E in-coupling surface