Ultrasonic transducer device for a clamp-on ultrasonic flow measurement point, a clamp-on ultrasonic flow measurement point, and a method for putting the clamp-on ultrasonic flow measurement point into operation

Abstract

The invention relates to an ultrasonic transducer device (10) for a clamp-on ultrasonic flow measurement point (1), the ultrasonic transducer device comprising a plurality of ultrasonic transducers (20), the ultrasonic transducers being designed to transmit ultrasonic signals into a measuring tube and / or to receive ultrasonic signals from the measuring tube, a first group of first ultrasonic transducers (G1) being located on a first side (2.11) of the measuring tube, a second group (G2) of second ultrasonic transducers being located on a second side (2.12) of the measuring tube, the second side being opposite to the first side, wherein at least one of the first ultrasonic transducers (G1) and the second ultrasonic transducers (G2) are located on a second side (2.12) of the measuring tube. The first / second ultrasonic transducer is designed to receive ultrasonic signals of at least one second / first ultrasonic transducer, characterized in that adjacent ultrasonic transducers in the first group are spaced apart by a first distance (A1), and adjacent ultrasonic transducers in the second group are spaced apart by a second distance (A2), the first distance and the second distance are different, wherein 2*A1>=A2>=1.125*A1, and in particular 1.75*A1>=A2>=1.16*A1, and preferably 1.6*A1>=A2>=1.25*A1.

Description

Technical Field Background Art

[0001] When it is cumbersome or impossible to install the measuring tube of an inline flow measuring point, clamp-on ultrasonic flow measuring points with ultrasonic transducers integrated in the measuring tube are used instead of the inline flow measuring point. Clamp-on ultrasonic flow measuring points are very easy to set up and can be installed on different measuring tubes. However, they have the disadvantage that the ultrasonic transducers of such measuring points can only be roughly adjusted to each other at best when leaving the factory.

[0002] The prior art shows an ultrasonic transducer arrangement for such a flow measurement point, in which case the ultrasonic transducers are mounted displaceably relative to each other in order to allow fine-tuning. However, this requires technical knowledge and also consumes a certain amount of time. A detour to circumvent this problem is proposed in DE102008029772A1, in which case two groups of multiple ultrasonic transducers are placed on the outside of the measuring tube, respectively, wherein the spacing between adjacent ultrasonic transducers in each group is small, wherein these spacings differ slightly between these groups. In this way, it can be achieved that, since there are multiple ultrasonic transducers in many cases, there are pairs of ultrasonic transducers connected by an ultrasonic signal path, and therefore, small changes in process parameters such as the speed of sound can be compensated by replacing the ultrasonic transducer pairs. Summary of the invention

[0003] The object of the invention is to provide an ultrasonic transducer arrangement for a clamp-on ultrasonic flow measuring point and a clamp-on ultrasonic flow measuring point, in which case the ultrasonic transducer arrangement is largely independent of the measuring tube diameter.

[0004] This object is achieved by an ultrasonic transducer arrangement according to the invention as well as by a clamp-on ultrasonic flow measuring point according to the invention and by a method according to the invention for putting an ultrasonic flow measuring point into operation.

[0005] The ultrasonic transducer device for clamping ultrasonic flow measurement point based on the propagation time difference principle of the present invention comprises:

[0006] a plurality of ultrasonic transducers adapted to be arranged on the outside of a measuring tube of a clamp-on flow measurement point,

[0007] wherein the ultrasonic transducer has in each case at least one transducer element for generating and / or receiving ultrasonic signals, and a coupling element, wherein the coupling element has a first contact area and a second contact area, wherein the transducer element is arranged on the first contact area, and wherein the ultrasonic transducer is suitable for contacting the measuring tube by means of the second contact area,

[0008] The ultrasonic transducer is suitable for radiating ultrasonic signals into the measuring tube and / or receiving ultrasonic signals emitted from the measuring tube.

[0009] wherein the second contact region has in each case a normal, wherein the normal defines a plane in which an ultrasound signal path of the ultrasound signal extends,

[0010] The first group of first ultrasonic transducers is arranged on a first side of the measuring tube relative to the longitudinal section of the measuring tube, and the second group of second ultrasonic transducers is arranged on a second side of the measuring tube opposite to the first side relative to the longitudinal section of the measuring tube.

[0011] wherein the coupling element of the first ultrasonic transducer and the coupling element of the second ultrasonic transducer in each case have a longitudinal axis, wherein the longitudinal axis in each case has an inner angle α at the respective second contact area, wherein the ultrasonic signal path extends in the coupling elements in the direction of the longitudinal axis,

[0012] wherein at least one first / second ultrasonic transducer is adapted to receive an ultrasonic signal of at least one second / first ultrasonic transducer,

[0013] It is characterized in that

[0014] adjacent ultrasonic transducers of the first group have in each case a first spacing from one another, and wherein adjacent ultrasonic transducers of the second group have in each case a second spacing from one another, wherein the first spacing and the second spacing are not equal,

[0015] Therein, 2*A1>=A2>=1.125*A1, and in particular 1.75*A1>=A2>=1.16*A1, and preferably 1.6*A1>=A2>=1.25*A1.

[0016] In an embodiment, the relationship between the first spacing and the second spacing corresponds to the following equation:

[0017] (a+1)*A1=a*A2, wherein b>a>1, a is a natural number, and b is the upper limit value of the range of a and is less than 9, and in particular less than 7, and preferably less than 5.

[0018] Advantageously, both the first number and the second number are equal to a+1.

[0019] In an embodiment, the first set of ultrasonic transducers has a first number of ultrasonic transducers and the second set of ultrasonic transducers has a second number of ultrasonic transducers,

[0020] in:

[0021] N1 is greater than or equal to a+1, and in particular greater than or equal to a+2,

[0022] N2 is greater than or equal to a+1, and in particular greater than or equal to a+2.

[0023] In an embodiment, the transducer element has a radial extension rA, wherein rA>3 / (4*a)*A1*cos(α),

[0024] And especially

[0025] rA>1 / (2*a)*A1*cos(α).

[0026] In an embodiment, the ultrasound transducer arrangement comprises at least a third ultrasound transducer having a signal path extending perpendicularly to the second contact area.

[0027] In an embodiment, the first group of ultrasound transducers and the second group of ultrasound transducers are in each case held by a support body, which is suitable for positioning and fixing the ultrasound transducers.

[0028] In an embodiment, the ultrasound transducers in the support body are each held individually.

[0029] The clamping type ultrasonic flow measurement point for measuring the flow velocity of a medium flowing through a measuring tube of the present invention comprises:

[0030] a measuring tube, which is used to convey the medium and has a measuring tube axis,

[0031] The ultrasonic transducer device of the invention according to one or more of the above definitions, wherein the ultrasonic transducer device is oriented parallel to the measuring tube axis,

[0032] Electronic measurement / operation circuitry for operating the ultrasonic transducer and for ascertaining and providing a measurement of flow velocity.

[0033] In an embodiment, the clamp-on ultrasonic flow measurement point comprises a curvature sensor for determining the outer diameter of the measuring tube,

[0034] The curvature sensor comprises a spacing sensor and a spacer.

[0035] wherein the spacer has a central region and two end portions adjacent to the central region, wherein the end portions are delimited from the central region by bends or angles,

[0036] wherein the spacer is adapted to be in contact with the measuring tube by means of the end portions, wherein the central region is adapted to be spaced apart from the measuring tube, and wherein a cross section or a longitudinal section through the spacer through the two end portions is adapted to extend parallel to the measuring tube cross section,

[0037] wherein the distance sensor is arranged on the spacer in the central area,

[0038] The electronic measuring / operating circuit is suitable for operating the distance sensor.

[0039] In an embodiment, the distance sensor is an optical or acoustic distance sensor.

[0040] In the method of the present invention for putting a clamp-on ultrasonic flow measuring point into operation,

[0041] the plurality of first ultrasonic transducers / the plurality of second ultrasonic transducers transmit, in each case simultaneously or offset in time, ultrasonic signals which are received by the second ultrasonic transducers / the first ultrasonic transducers,

[0042] Wherein the electronic measurement / operation circuit determines at least one ultrasonic transducer pair to be used for measurement operation based on the signal strength and / or signal-to-noise ratio of the received ultrasonic signal.

[0043] In an embodiment, the ultrasound signal is quasi-continuous and has different frequencies, or

[0044] The ultrasonic signal is pulsed and differs in the following characteristics:

[0045] The center frequency of the spectrum.

[0046] In an embodiment, the medium is conveyed through the measuring tube,

[0047] Wherein, in the case of a received ultrasonic signal, it is checked whether there is a propagation time difference in the ultrasonic signal part,

[0048] Therein, when determining the ultrasonic transducer pair to be used, ultrasonic signal portions having no propagation time difference are excluded.

[0049] In the case of the method according to the invention for putting into operation a clamp-on ultrasonic flow measuring point,

[0050] causing the third ultrasonic transducer to transmit and receive ultrasonic signals,

[0051] wherein the electronic measuring / operating circuit determines the outer diameter and / or the inner diameter based on at least one signal characteristic of the received ultrasound signal,

[0052] Among the available signal characteristics are, for example:

[0053] The propagation time of the signal reflection.

[0054] In the method according to the invention for commissioning a clamp-on ultrasonic flow measuring point, the electronic measuring / operating circuit determines the outer diameter by means of a curvature sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The invention will now be described based on examples of embodiments presented in the accompanying drawings, the figures of which are as follows:

[0056] Figure 1 Two ultrasound transducers of the arrangement of the invention are shown.

[0057] Figure 2 shows the geometrical relationships of the arrangement of the present invention for an ultrasonic transducer;

[0058] Figure 3 The arrangement of the invention for an ultrasonic transducer is shown by way of example;

[0059] Figure 4 The arrangement of the invention for an ultrasonic transducer is shown by way of example;

[0060] Figure 5 shows the arrangement in the support body;

[0061] Figure 6 Showing a flow measurement point with the arrangement of the present invention;

[0062] Figure 7 A curvature sensor is shown. DETAILED DESCRIPTION

[0063] Figure 1 A schematic construction of an example of an ultrasonic transducer 20 is shown, and part of an arrangement of the invention comprises two first ultrasonic transducers 20.1 and two second ultrasonic transducers 20.2, which are arranged on the outside of a measuring tube wall of a measuring tube 2. The ultrasonic transducer comprises in each case at least one transducer element 21, preferably a piezoelectric transducer element, and a coupling element 22, wherein the transducer element is arranged on a first contact area 22.1 of the coupling element, and wherein the coupling element is acoustically and mechanically coupled to the measuring tube via a second contact area 22.2. The coupling element has a longitudinal axis L, along which the ultrasonic signal generated by the transducer element 21 or received via the contact area 22.2 propagates. The transducer element is preferably disc-shaped and has a radial extension rA. The radial extension of the transducer element does not necessarily correspond to the radial extension of the coupling element, so that Figure 1 The illustration in only simplifies the drawing. The longitudinal axis has an angle γ with respect to the normal N of the second contact area, so that the ultrasonic signal is coupled into the measuring tube in an inclined manner. In the measuring tube, when the speed of sound in the coupling element differs from the speed of sound in the medium, the ultrasonic signal path makes an angle β with the normal, which angle β is usually different from the angle γ. Adjacent first ultrasonic transducers 20.1 have a first spacing A1 from one another, and correspondingly, adjacent second ultrasonic transducers have a second spacing A2 from one another.

[0064] Typical values ​​for the angle γ are 30° to 45°, depending on the materials used for the coupling element and the measuring tube and on the medium flowing through the measuring tube.

[0065] Figure 2 The geometric relationship for the arrangement of ultrasonic transducers according to the invention is shown, wherein a first group G1 of ultrasonic transducers 20 consisting of first ultrasonic transducers 20.1 is arranged on a first side 2.11 in the measuring tube longitudinal section of the measuring tube 2, and wherein a second group G2 of ultrasonic transducers 20 consisting of second ultrasonic transducers 20.2 is arranged on a second side 2.12 of the measuring tube 2 opposite to the first side. The number of five ultrasonic transducers per group in each case selected here is for illustrative purposes and is not to be understood as limiting.

[0066] The first ultrasonic transducer 20.1 has a first spacing A1 between adjacent transducers, and the second ultrasonic transducer 20.2 has a second spacing A2 between adjacent transducers, wherein the spacings A1 and A2 are different from each other. As a result, in the case where the ultrasonic signal path UP defined by the first ultrasonic transducer overlaps with the ultrasonic signal path UP defined by the second ultrasonic transducer, such as occurs for the first ultrasonic transducer and the second ultrasonic transducer on the left, there is no overlap in the ultrasonic signal paths of the other first ultrasonic transducers and the second ultrasonic transducers shown. For the second group of first ultrasonic transducers and second ultrasonic transducers on the left, this is indicated by the solid line of the first ultrasonic transducer and the offset dotted line of the second ultrasonic transducer. In the latter case, the signal amplitude of the received ultrasonic signal recorded by the receiving ultrasonic transducer is lower than in the case where the signal paths between the two ultrasonic transducers overlap.

[0067] Since the ultrasound signal has a spatial extension perpendicular to its propagation in the direction of the ultrasound signal path, an increased offset of the two ultrasound signal paths between the transmitting ultrasound transducer and the receiving ultrasound transducer results in an increased reduction in the amplitude of the received ultrasound signal.

[0068] Due to the different spacings A1 and A2, there are different measuring tube diameters, and the ultrasonic signal path of the first ultrasonic transducer 20.1 and the ultrasonic signal path of the second ultrasonic transducer 20.2 overlap at the measuring tube diameter. This is shown by the ultrasonic transducers U2 and U5. From this, the maximum relevant ultrasonic signal path deviation of the ultrasonic transducer arrangement can be derived. When the measuring tube diameter has a value that is exactly between the two measuring tube diameter values, at this value, the ultrasonic signal path of the first ultrasonic transducer 20.1 and the ultrasonic signal path of the second ultrasonic transducer 20.2 overlap.

[0069] Preferably, the transducer element has a radial extension rA, wherein rA>3 / (4*a)*A1*sin(α), in particular rA>1 / (2*a)*A1*sin(α), or wherein rA>3 / (4*a)*A1*cos(γ), in particular rA>1 / (2*a)*A1*cos(γ).

[0070] Ignoring the ultrasonic signal expansion results in a maximum relevant deviation of the ultrasonic signal path in a direction extending along the measuring tube axis of one third of the ultrasonic signal width parallel to the measuring tube axis, in this case an offset. It has been found that in this case the ultrasonic signal amplitude in the receiving ultrasonic transducer is still sufficient for good signal processing.

[0071] Thus, by providing different spacings A1 and A2, valuable ultrasonic flow measurements can be performed over a larger range of measuring tube diameters.

[0072] The wall thickness of the measuring tube 2 , which is neglected here, will influence the entry point of the sound into the medium relative to the coupling element. A person skilled in the art will take this into account in a given case.

[0073] Figure 3 An exemplary arrangement of ultrasonic transducers for use on a measuring tube 2 of the present invention is shown by way of example, wherein the parameter a is selected to be equal to 3. The inclined lines from the ultrasonic transducers U1 to U5 in the first group of ultrasonic transducers show the line of the ultrasonic signal path. The horizontal line shows the measuring tube diameter at which the ultrasonic signal paths from the ultrasonic transducers U6 to U10 in the second group of ultrasonic transducers coincide with the ultrasonic signal paths in the first group of ultrasonic transducers. In order to illustrate the influence of different measuring tube diameters, the second group of ultrasonic transducers is shown twice. In the case of a small measuring tube diameter, for example, ultrasonic transducers U4 and U6 can form a usable ultrasonic transducer pair. For large diameters, an external ultrasonic transducer, such as the ultrasonic transducer U5 shown here, may be required so that an ultrasonic transducer pair can be formed with the ultrasonic transducer U8 in the other group. Therefore, depending on the measuring tube diameter, different ultrasonic transducers in the two groups of ultrasonic transducers can be used.

[0074] For a first group of ultrasonic transducers having a first number N1 of ultrasonic transducers and for a second group of ultrasonic transducers having a second number N2 of ultrasonic transducers, preferably: N1 is greater than or equal to a+1, in particular greater than or equal to a+2, and N2 is greater than or equal to a+1, in particular greater than or equal to a+2. Figure 3 As shown in , N1 and N2 do not have to be 5 or equal.

[0075] The larger N1, N2 are, the larger the range of measuring tube diameters for ultrasonic transducers can be used with the arrangement of the present invention.

[0076] Those skilled in the art will form the ultrasonic transducer device according to their requirements.

[0077] Figure 4By way of example, an arrangement of the invention is shown for a first group G1 and a second group G2 of ultrasonic transducers and a third group G3 of a third ultrasonic transducer 20 . 3 .

[0078] The third ultrasonic transducer is adapted to radiate ultrasonic signals perpendicular to the measuring tube wall 2.3 into the measuring tube 2 and to receive ultrasonic signals reflected on the oppositely placed measuring tube side. Using the signal propagation time, the measuring tube diameter can be derived, so that an available ultrasonic transducer pair with a first set of ultrasonic transducers and a second set of ultrasonic transducers can be selected in order to put the clamp-on ultrasonic flow measurement point into operation. Thus, the testing of individual ultrasonic transducers in the first set and the second set can be limited or avoided.

[0079] The number and orientation of ultrasound transducers shown here are exemplary only and have illustrative purposes and should not be construed as limiting.

[0080] Figure 5 The ultrasonic transducers of the first group G1 or the second group G2 arranged in and held by the support body 30 are shown. The support body may have positioning elements, by means of which the ultrasonic transducers can be positioned in the desired position when the ultrasonic transducers are mounted in the support body. After positioning, the ultrasonic transducers can be poured into the support body. The ultrasonic transducers can be held individually in the support body, for example, so that they can be assembled on rough or uneven measuring tube surfaces, for example. This view is only an example with respect to the number and arrangement of ultrasonic transducers and should not be understood as limiting. Similarly, as shown here, the third ultrasonic transducer 20.3 can be arranged in such a support body.

[0081] Figure 6 By way of example, a clamp-on ultrasonic flow measurement point 1 is shown, which has a measuring tube 2, an ultrasonic transducer device 10 of the invention, a support body 30 for holding the ultrasonic transducer device, a curvature sensor 4 for determining the curvature of the measuring tube, and an electronic measuring / operating circuit for operating the ultrasonic transducer and the curvature sensor and for providing a flow measurement value. The clamp-on ultrasonic flow measurement point does not necessarily have to have a curvature sensor.

[0082] Figure 7The structure of a curvature sensor 4 is shown, with the aid of which the outer diameter of the measuring tube can be determined. With knowledge of the outer diameter of the measuring tube and the thickness of the measuring tube, the pair of ultrasonic transducers to be used can be predetermined. The curvature sensor comprises a distance sensor 4.1 and a spacer 4.2, which has a central region 4.21 and two ends 4.22 bent from the central region. The spacer is placed on the measuring tube 2 parallel to the cross section, wherein the central region has an outer diameter of the measuring tube that depends on the distance from the outer surface of the measuring tube. This distance is measured using the distance sensor 4.1 applied in the central region. Such a sensor can be, for example, an ultrasonic sensor or an optical sensor.

[0083] Putting the clamp-on ultrasonic flow measurement point into operation requires determining an ultrasonic transducer pair comprising a first ultrasonic transducer and a second ultrasonic transducer. To this end, as already mentioned, the inner diameter of the measuring tube and the thickness of the measuring tube can be determined by means of a third ultrasonic transducer, and thus the ultrasonic transducer pair can be determined. Alternatively or in addition, a curvature sensor can be applied, as already mentioned. Alternatively or in addition, a plurality of first ultrasonic transducers and / or second ultrasonic transducers can transmit ultrasonic signals simultaneously or offset in time. The selection of the ultrasonic transducer pair can then be determined, for example, based on the ultrasonic signal amplitude, which is measured by means of the ultrasonic transducer selected as the receiver. In order to clarify which transducers are involved, one or more features can be applied to the ultrasonic signals of different ultrasonic transducers used to transmit ultrasonic signals. For example, in the case of a pulsed ultrasonic signal, the center frequency can be characteristic. Alternatively or in addition, for example, the ultrasonic signal can have different signal linear frequency modulations.

[0084] At startup, it is also possible to convey a medium through the measuring tube and to perform a propagation time difference measurement of the ultrasonic signals. In this case, ultrasonic signals with no or small propagation time differences can be disregarded. Such signals are, for example, signals that are coupled from the original ultrasonic signal into the measuring tube without propagation through the medium. Thus, in the case of a receiving ultrasonic transducer, multiple ultrasonic signals caused by various reflections can arrive overlapping or offset in time from the original ultrasonic signal.

[0085] Reference Mark List

[0086] 1 Clamp-on ultrasonic flow measurement point

[0087] 2 Measuring tube

[0088] 2.11 First measuring tube side

[0089] 2.12 Second measuring tube side

[0090] 2.2 Measuring the pipe axis

[0091] 2.3 Measuring pipe wall

[0092] 3 Electronic measurement / operation circuits

[0093] 4 Curvature sensor

[0094] 4.1 Distance Sensor

[0095] 4.2 Spacers

[0096] 4.21 Central Area

[0097] 4.22 End

[0098] 10 Ultrasonic transducer device

[0099] 20 Ultrasonic transducer

[0100] 20.1 First Ultrasonic Transducer

[0101] 20.2 Second Ultrasonic Transducer

[0102] 20.3 The Third Ultrasonic Transducer

[0103] 21 Transducer element

[0104] 22 Coupling element

[0105] 22.1 First contact area

[0106] 22.2 Second contact area

[0107] 30 Support body

[0108] N1 First quantity

[0109] N2 Second quantity

[0110] A1 first spacing

[0111] A2 Second Spacing

[0112] UP Ultrasound Signal Path

[0113] N Normals

[0114] U1-U9 Ultrasonic Transducer

[0115] G1 Group 1

[0116] G2 Group 2

[0117] G3 Group 3

Claims

1. An ultrasonic transducer device (10) for a clamp-on ultrasonic flow measurement point (1) based on the propagation time difference principle, the ultrasonic transducer device comprising: a plurality of ultrasonic transducers (20), which are suitable for being arranged on the outer side of the measuring tube wall (2.3) of the measuring tube (2) of the clamp-on ultrasonic flow measurement point, wherein the ultrasonic transducer (20) has in each case at least one transducer element (21) for generating and / or receiving ultrasonic signals, and a coupling element (22), wherein the coupling element has a first contact area (22.1) and a second contact area (22.2), wherein the transducer element is arranged on the first contact area, and wherein the ultrasonic transducer is suitable for contacting the measuring tube by means of the second contact area, The ultrasonic transducer is adapted to radiate ultrasonic signals into the measuring tube and / or to receive ultrasonic signals emitted from the measuring tube. wherein the second contact area has in each case a normal (N), wherein the normal defines a plane in which an ultrasound signal path (UP) of the ultrasound signal extends, wherein a first group (G1) of first ultrasonic transducers is arranged on a first side (2.11) of the measuring tube relative to a longitudinal cross section of the measuring tube, and wherein a second group (G2) of second ultrasonic transducers is arranged on a second side of the measuring tube opposite to the first side relative to the longitudinal cross section of the measuring tube, wherein the coupling element of the first ultrasonic transducer and the second ultrasonic transducer has in each case a longitudinal axis (L), wherein the longitudinal axis has in each case an inner angle α at the respective second contact area, wherein the ultrasonic signal path extends in the coupling element in the direction of the longitudinal axis, wherein at least one first / second ultrasonic transducer is adapted to receive an ultrasonic signal of at least one second / first ultrasonic transducer, It is characterized in that adjacent first ultrasonic transducers of the first group have in each case a first spacing A1 from one another, and adjacent second ultrasonic transducers of the second group have in each case a second spacing A2 from one another, wherein the first spacing and the second spacing are unequal, Among them, 2*A1>=A2>=1.125*A1, The relationship between the first spacing A1 and the second spacing A2 corresponds to the following equation: (a+1)*A1=a*A2, where b>a>1, a is a natural number, and b is the upper limit of the range of a and is less than 7, wherein the first group of first ultrasonic transducers has a first number N1 of first ultrasonic transducers, and wherein the second group of second ultrasonic transducers has a second number N2 of second ultrasonic transducers, in: N1 is greater than or equal to a+1, N2 is greater than or equal to a+1.

2. The ultrasonic transducer device according to claim 1, in, 1.75*A1>=A2>=1.16*A1.

3. The ultrasonic transducer device according to claim 1, in, 1.6*A1>=A2>=1.25*A1.

4. The ultrasonic transducer device according to claim 1, in, b is less than 5.

5. The ultrasonic transducer device according to claim 1, in, N1 is greater than or equal to a+2.

6. The ultrasonic transducer device according to claim 1, in, N2 is greater than or equal to a+2.

7. The ultrasonic transducer device according to claim 1, in, The transducer element has a radial extension rA, wherein rA>3 / (4*a)*A1*sin(α).

8. The ultrasonic transducer device according to claim 7, in, rA>1 / (2*a)*A1*sin(α).

9. The ultrasonic transducer device according to any one of claims 1 to 6, Also included is a third group (G3) having at least a third ultrasonic transducer (20.3) having a signal path extending perpendicularly to the second contact area.

10. The ultrasonic transducer device according to any one of claims 1 to 6, in, The first set of ultrasonic transducers and the second set of ultrasonic transducers are in each case held by a support body which is suitable for positioning and fixing the ultrasonic transducers.

11. The ultrasonic transducer device according to claim 10, in, The ultrasonic transducers in the support body are each held separately.

12. A clamp-on ultrasonic flow measurement point (1), used for measuring the flow velocity of a medium flowing through a measuring tube (2), the clamp-on ultrasonic flow measurement point comprising: a measuring tube (2) for conveying a medium and having a measuring tube axis (2.1), The ultrasonic transducer device (10) according to any one of claims 1 to 11, wherein the ultrasonic transducer device is oriented parallel to the measuring tube axis, Electronic measurement / operation circuitry (3) for operating the ultrasonic transducer and for ascertaining and providing a measurement of flow velocity.

13. The clamp-on ultrasonic flow measurement point according to claim 12, It also comprises a curvature sensor (4) for determining the outer diameter of the measuring tube, in, The curvature sensor comprises a distance sensor (4.1) and a spacer (4.2), wherein the spacer has a central region (4.21) and two end portions (4.22) adjacent to the central region, wherein the end portions are delimited from the central region by bends or angles, wherein the spacer is adapted to be in contact with the measuring tube by means of the end portions, wherein the central region is adapted to be spaced apart from the measuring tube, and wherein a cross section or a longitudinal section through the spacer through the two end portions is adapted to extend parallel to the measuring tube cross section, wherein the distance sensor is arranged on a spacer in the central area, Therein, the electronic measuring / operating circuit (3) is suitable for operating the distance sensor.

14. The clamp-on ultrasonic flow measurement point according to claim 13, in, The distance sensor is an optical or acoustic distance sensor.

15. A method for putting into operation a clamp-on ultrasonic flow measuring point (1) according to any one of claims 12 to 14, in, a plurality of first ultrasonic transducers (20.1) / a plurality of second ultrasonic transducers (20.2) transmits in each case simultaneously or offset in time the ultrasonic signals received by the second ultrasonic transducers / first ultrasonic transducers, Therein, the electronic measurement / operation circuit (3) determines at least one ultrasonic transducer pair to be used for the measurement operation based on the signal strength and / or signal-to-noise ratio of the received ultrasonic signal.

16. The method according to claim 15, in, The ultrasonic signal is quasi-continuous and has different frequencies, or Wherein, the ultrasonic signal is pulsed and differs in the following characteristics: The center frequency of the spectrum.

17. The method according to claim 15 or 16, in, The medium is conveyed through the measuring tube (2), Wherein, when receiving the ultrasonic signal, checking whether there is a propagation time difference in the ultrasonic signal part, Therein, when determining the ultrasonic transducer pair to be used, ultrasonic signal portions having no propagation time difference are excluded.

18. A method for putting into operation a clamp-on ultrasonic flow measuring point according to any one of claims 15 to 17, depending on claim 9, in, enabling the third ultrasonic transducer (20.3) to send and receive ultrasonic signals, Therein, the electronic measurement / operation circuit (3) determines the outer diameter and / or the inner diameter based on at least one signal feature of the received ultrasound signal.

19. The method according to claim 18, in, The available signal characteristic is the propagation time of the signal reflections.

20. A method for putting into operation a clamp-on ultrasonic flow measuring point according to any one of claims 15 to 19, in, The electronic measuring / operating circuit (3) determines the outer diameter with the aid of a curvature sensor (4).

Images