Ultrasonic transducer device for clamp-on ultrasonic flow measurement point, clamp-on ultrasonic flow measurement point, and 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) comprising a plurality of clamp-on ultrasonic transducers (20), wherein arrangements of measuring tubes (2) of different diameters can be used without having to reorient the ultrasonic transducers in the ultrasonic transducer device.

Description

Background Art

[0001] When the installation of the measuring tubes for in-line flow measuring points is cumbersome or impossible, clamp-on ultrasonic flow measuring points are used instead of in-line flow measuring points, in which the ultrasonic transducer is integrated in the measuring tube. 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 such an ultrasonic transducer arrangement for a flow measurement point, in which case the ultrasonic transducers are mounted displaceably relative to each other in order to allow fine adjustment. However, this requires technical knowledge and also consumes a certain amount of time. A detour to circumvent this problem is proposed in DE 10 2008 029 772 A1, in which case two groups of multiple ultrasonic transducers are respectively placed on the outside of the measuring tube, wherein the adjacent ultrasonic transducers in each group are spaced apart from each other at small intervals, wherein these intervals 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 via 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 device for a clamp-on ultrasonic flow measurement point and a clamp-on ultrasonic flow measurement point, in which case the ultrasonic transducer device 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 a clamp-on ultrasonic flow measuring point according to the invention and a method according to the invention for putting an ultrasonic flow measuring point into operation.

[0005] The ultrasonic transducer device for clamping an ultrasonic flow measurement point based on the travel 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 clamping a 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 area has in each case a normal, wherein the normal defines a plane in which an ultrasound signal path of the ultrasound signal extends,

[0010] wherein the first ultrasonic transducers define first ultrasonic signal paths extending parallel to each other, and wherein the second ultrasonic transducers define second ultrasonic signal paths extending parallel to each other, wherein the ultrasonic signal paths extend in a plane,

[0011] wherein the ultrasonic signal path of the first ultrasonic transducer and the ultrasonic signal path of the second ultrasonic transducer in the coupling element extend in each case obliquely with respect to the second contact region,

[0012] The direction of the first ultrasonic signal path and the direction of the second ultrasonic signal path are mirror-symmetric to the normal line.

[0013] wherein the first ultrasound signal path defines intersection points with the second ultrasound signal path in the plane, wherein the intersection points are located at parallel lines extending perpendicularly to the normal in the plane,

[0014] wherein the first group of associated ultrasonic transducers has exclusively a first number of first ultrasonic transducers, and wherein the second group of associated ultrasonic transducers has exclusively a second number of second ultrasonic transducers,

[0015] wherein adjacent ultrasonic transducers of the first group have in each case a first spacing A1 from one another in the direction of parallel lines, and wherein adjacent ultrasonic transducers of the second group have in each case a second spacing A2 from one another in the direction of parallel lines, wherein the first spacing and the second spacing are not equal,

[0016] It is characterized in that

[0017] 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.

[0018] “Associated” here means that no additional ultrasonic transducers are arranged between a group of ultrasonic transducers.

[0019] In an embodiment, the relationship between the first spacing A1 and the second spacing A2 meets or corresponds in particular to the following equation:

[0020] (a+1)*A1=a*A2, wherein b>a>1, a is a natural number, 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.

[0021] Advantageously, the first number and / or the second number is greater than a.

[0022] In an embodiment, the ultrasound transducer has in each case a longitudinal axis, wherein the longitudinal axis has in each case an inner angle α relative to the respective second contact area, wherein the ultrasound signal path extends in the coupling element in the direction of the longitudinal axis,

[0023] The transducer element has a radial extension (rA), wherein

[0024] rA>3 / (8*a)*A1*cos(α),

[0025] In particular,

[0026] rA>1 / (4*a)*A1*cos(α).

[0027] In an embodiment, the ultrasonic transducer arrangement comprises at least a third group of ultrasonic transducers having at least one first ultrasonic transducer and / or at least one second ultrasonic transducer,

[0028] Wherein at least one intersection point formed by the first ultrasonic transducer in the third group and / or the second ultrasonic transducer in the third group supplements a maximum cardinality of a first quantity of equidistant parallel lines.

[0029] The first quantity of maximum cardinality is characterized in that adjacent parallel lines belonging to the maximum cardinality quantity have in each case the same spacing from one another and in that the quantity has the greatest number of parallel lines compared to other quantities of equidistant parallel lines.

[0030] 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.

[0031] In an embodiment, the device comprises a support body for holding the ultrasound transducer.

[0032] In an embodiment, the ultrasound transducers are held in each case individually in a supporting body.

[0033] The clamped ultrasonic flow measurement point for measuring the flow velocity of a medium flowing through a measuring tube of the present invention comprises:

[0034] a measuring tube for conveying the medium and having a measuring tube axis,

[0035] The ultrasonic transducer device of the present invention is oriented parallel to the measuring tube axis.

[0036] Electronic measuring and operating circuitry for operating the ultrasonic transducer and for determining and providing a measurement of flow velocity.

[0037] In an embodiment, the clamp-on ultrasonic flow measurement point comprises a curvature sensor for determining the outer diameter of the measuring tube,

[0038] The curvature sensor comprises a spacing sensor and a spacer.

[0039] 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,

[0040] 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,

[0041] wherein the distance sensor is arranged on the spacer in the central region,

[0042] The electronic measuring / operating circuit is suitable for operating the distance sensor.

[0043] In an embodiment, the distance sensor is an optical or acoustic distance sensor.

[0044] In the method of the present invention for putting a clamp-on ultrasonic flow measurement point into operation,

[0045] a plurality of first ultrasonic transducers / a plurality of second ultrasonic transducers transmits in each case simultaneously or offset in time an ultrasonic signal which is received by the second ultrasonic transducer / the first ultrasonic transducer,

[0046] 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.

[0047] In an embodiment, the ultrasound signal is quasi-continuous and has different frequencies, or

[0048] The ultrasonic signal is pulsed and differs in the following characteristics:

[0049] The center frequency of the spectrum.

[0050] In an embodiment, the medium is conveyed through the measuring tube,

[0051] Wherein, in the case of a received ultrasonic signal, it is checked whether there is a propagation time difference in the ultrasonic signal part,

[0052] Therein, when determining the ultrasonic transducer pair to be used, ultrasonic signal portions having no propagation time difference are excluded.

[0053] In the method of the present invention, the third ultrasonic transducer is caused to send and receive ultrasonic signals,

[0054] 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,

[0055] Among the available signal characteristics are, for example:

[0056] Propagation time.

[0057] In the method according to the invention, the electronic measuring / operating circuit determines the outer diameter with the aid of a curvature sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The invention will now be described based on examples of embodiments presented in the accompanying drawings, the figures of which are as follows:

[0059] Figure 1 Two ultrasound transducers of the arrangement of the invention are shown.

[0060] Figure 2 shows the geometrical relationships of the arrangement of the present invention for an ultrasonic transducer;

[0061] Figure 3 shows the distribution of intersection points;

[0062] Figure 4 An option is shown for compensating for a maximum cardinality first amount of equidistant parallel lines;

[0063] Figure 5 shows different ultrasonic signal paths in a measuring tube depending on the diameter of the measuring tube;

[0064] Figure 6 The arrangement of the invention for an ultrasonic transducer is shown by way of example;

[0065] Figure 7 shows the arrangement in the support body;

[0066] Figure 8 Showing a flow measurement point with the arrangement of the present invention;

[0067] Fig. 9 A curvature sensor is shown. DETAILED DESCRIPTION

[0068] Figure 1A schematic construction of an example of an ultrasonic transducer 20 is shown, and a part of the device of the invention comprises two first ultrasonic transducers 20.1 and two second ultrasonic transducers 20.2, which are arranged on the outside of the 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 the 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 simplifies the drawing only. 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 is at 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.

[0069] 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.

[0070] Figure 2 A mutually parallel first ultrasonic signal path UP1 and a mutually parallel second ultrasonic signal path UP2 in the measuring tube 2 are shown, which are emitted from two first ultrasonic transducers 20.1 and two second ultrasonic transducers 20.2 and extend in a plane, wherein each pair of the first ultrasonic signal path and the second ultrasonic signal path extends mirror-symmetrically with respect to the normal N of the second contact area. The ultrasonic signal paths intersect and define a network of intersection points located in the plane. The intersection points on the first ultrasonic signal path UP1 have a spacing p2=d2 / (2*sin(β)) projected onto the normal N, wherein d2 is equal to the spacing of adjacent second ultrasonic signal paths UP2. Correspondingly, the intersection points on the second ultrasonic signal path UP2 have a spacing p1=d1 / (2*sin(β)) projected onto the normal N, wherein d1 is equal to the spacing of adjacent first ultrasonic signal paths UP1. The minimum spacing of two intersection points projected onto the normal is p2-p1.

[0071] The number of ultrasonic transducers, their arrangement relative to one another and the selected angles should not be understood as limiting and are shown only for illustrative purposes. The thickness of the measuring tube 2, which is neglected in this case, influences the sound entry point into the medium relative to the coupling element. A person skilled in the art will take this into account, as the case may be.

[0072] Figure 3 A network of intersection points is shown, which is created by a first group G1 of associated first ultrasonic transducers with three first ultrasonic transducers 20.1 and a second group G2 of associated second ultrasonic transducers with three second ultrasonic transducers 20.2. In the case of equal spacings A1 and A2, the network will have a diamond shape, in which some of the intersection points have equal spacings from the wall of the measuring tube 2. Due to the different spacings A1 and A2, the diamond shape is distorted, so that a parallelogram is formed, so that the intersection points that otherwise have equal spacings from the measuring tube wall are now arranged along lines inclined to the measuring tube wall, such as indicated by means of dashed lines. In the case of an equal number N1 of first ultrasonic transducers of the first group G1 and the number N2 of second ultrasonic transducers of the second group G2, a number of intersection points corresponding to the number of first ultrasonic transducers is placed on the central oblique line, and in each case one less intersection point is placed on the adjacent oblique line. For the spacings A1 and A2, the following relationship holds: (a+1)*A1=a*A2, where b>a>1, where a and b are natural numbers, and N1 and N2 are greater than or equal to a+1, then the intersection of the central inclined line and at least the adjacent inclined line is located on an equidistant parallel line to the measuring tube wall or the measuring tube axis, and a maximum cardinality first quantity M1 of equidistant parallel lines is defined. Other quantities of equidistant parallel lines are spaced further apart from quantity M1 than the spacing of adjacent equidistant parallel lines. A quantity of equidistant parallel lines may also include only one parallel line parallel to itself and equidistant therefrom.

[0073] The spacing of the parallel lines of the ultrasonic transducers depends on the spacing of the first group from the second group. Pushing the second group towards the first group results in a decrease in the spacing of the parallel lines of the ultrasonic transducers. This means that the device can be used for measuring tubes with small diameters.

[0074] The number of ultrasonic transducers, their arrangement relative to each other, and the angles selected should not be construed as limiting and are shown for illustration purposes only.

[0075] Figure 4 It is shown how to supplement the maximum base first quantity M1 by adding more ultrasonic transducers. A first group G1 of ultrasonic transducers including ultrasonic transducers U1 to U3 and a second group G2 of ultrasonic transducers including ultrasonic transducers U4 to U6 are shown. Figure 3A network of intersection points is defined as in , wherein the intersection points fall within a first quantity M1 of equidistant parallel lines P, and wherein the intersection points are located at parallel lines P that do not belong to quantity M1. The gap between a parallel line that does not belong to quantity M1 and a parallel line that belongs to quantity M1 is an integer multiple of adjacent parallel lines of quantity M1. Quantity M1 can be supplemented by means of at least a third group G3 of ultrasonic transducers, for example including ultrasonic transducer U7 and / or ultrasonic transducers U8 and U9, such as indicated by dashed parallel lines.

[0076] The supplementation can also be done with the ultrasonic transducer arrangement, in which case the first set of ultrasonic transducers and / or the second set of ultrasonic transducers has more than three ultrasonic transducers.

[0077] Figure 5 The ultrasonic signal path depending on the measuring tube diameter is shown. The ultrasonic signal radiated into the measuring tube at the first side of the measuring tube 2.11 is reflected on the inner side of the measuring tube wall on the second side of the measuring tube 2.12. For the case where the interior of the measuring tube on the second side coincides with the parallel line P1, the ultrasonic signal path output from the first ultrasonic transducer / second ultrasonic transducer overlaps the ultrasonic signal path of the second ultrasonic transducer / first ultrasonic transducer, so that the ultrasonic signal emitted from the first ultrasonic transducer / second ultrasonic transducer can be received by the second ultrasonic transducer / first ultrasonic transducer. This situation is shown by means of a solid line reflected at the parallel line P1 in the intersection K1 through the ultrasonic signal path between the ultrasonic transducer U2 and the ultrasonic transducer U4.

[0078] For the case where the interior of the measuring tube on the second side does not coincide with the parallel line P1, the ultrasonic signal paths of ultrasonic transducers U2 and U4 are offset from each other, which results in a reduction in the ultrasonic signal amplitude at the receiving ultrasonic transducer. This is shown with a thick dashed line for the ultrasonic signal emitted from U4.

[0079] For the case where the interior of the measuring tube coincides with the parallel line P2 on the second side, the ultrasonic signal paths of the ultrasonic transducers U1 and U3 overlap.

[0080] In the case where the interior of the second side of the measuring tube is between the parallel lines P1 and P2 and equally far from both parallel lines, there is a maximum relevant deviation of the inner wall relative to one of the parallel lines P1 and P2. In the case where the inner wall is closer to P1, this will mean that the ultrasonic signal paths of the ultrasonic transducers U2 and U4 are better aligned. In the case where the inner wall is closer to P2, this will mean that the ultrasonic signal paths of the ultrasonic transducers U1 and U3 are better aligned. This is demonstrated with the help of a thin dotted line starting from U3 to U1 and leading from U4 to U2, which can provide the ultrasonic signal width by ignoring the widening that actually occurs. In the case of reflection on the inner surface exactly halfway between P1 and P2, the ultrasonic signal no longer strikes the center on the corresponding receiving ultrasonic transducer but is offset, where the offset is equally large in the case of both ultrasonic signal paths.

[0081] Preferably, the transducer element has a radial extension rA (see Figure 1 ), where rA>3 / (8*a)*A1*cos(γ), and in particular, rA>1 / (4*a)*A1*cos(γ), or rA>3 / (8*a)*A1*sin(α), and in particular rA>1 / (4*a)*A1*sin(α), where (a+1)*A1=a*A2.

[0082] Neglecting the ultrasonic signal expansion results in a maximum relevant deviation, in this case an offset, of one third of the ultrasonic signal width parallel to the measuring tube axis in a direction extending along the measuring tube axis or along a parallel line P. It has been found that in this case the ultrasonic signal amplitude in the receiving ultrasonic transducer is still sufficient for good signal processing.

[0083] Figure 6 The arrangement of ultrasonic transducers for measuring the pipe 2 according to the present invention is shown by way of example, wherein the first group G1 of ultrasonic transducers and the second group G2 of ultrasonic transducers G2 each have three first ultrasonic transducers 20.1 and three second ultrasonic transducers 20.2. In addition, the arrangement comprises a third group G3 of ultrasonic transducers having first ultrasonic transducers 20.1 and second ultrasonic transducers 20.2, thereby supplementing the arrangement as shown in FIG. Figure 4The maximum cardinality of equidistant parallel lines shown. In addition, such as shown in this case, the ultrasonic transducer device can, for example, have a third ultrasonic transducer 20.3, which is suitable for radiating ultrasonic signals perpendicularly to the measuring tube axis and receiving these ultrasonic signals after they are reflected on the inner side of the measuring tube on the second side 2.12. With the help of at least one measured signal propagation time of the ultrasonic signal, the measuring tube diameter and the measuring tube thickness as well as the ultrasonic transducer pair to be used can be determined. In this case, the reflection occurring at each interface between two different media can be utilized. Therefore, the first reflection of the ultrasonic signal can be used for thickness determination, while the second reflection can be used for measuring tube diameter determination. A person skilled in the art can use known signal evaluation methods for this purpose.

[0084] Figure 7 The ultrasonic transducer is shown arranged in a support body 30 and held by the support body 30. The support body may have a positioning element, by means of which the ultrasonic transducer can be positioned in a desired position when the ultrasonic transducer is mounted in the support body. After positioning, the ultrasonic transducer can be poured into the support body. The ultrasonic transducer can be held individually in the support body, for example, so that it can be mounted on a rough or uneven measuring tube surface, 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.

[0085] Figure 8 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 present 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 flow measurement values. The clamp-on ultrasonic flow measurement point does not necessarily have to have a curvature sensor.

[0086] Fig. 9 The 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.

[0087] replace Figure 5The V-shaped ultrasonic signal path shown with one reflection on the second measuring tube side 2.12 can also be a W-shaped signal path with two reflections on the second measuring tube side and an intermediate reflection on the first measuring tube side 2.11. This is advantageous in the case of small measuring tube diameters or when the oscillations of the measuring tube caused by the coupled-in ultrasonic signal arrive close to the receiving ultrasonic transducer overlapping in time with the ultrasonic signal propagating along the V-shaped ultrasonic signal path.

[0088] The start-up of the clamped ultrasonic flow measurement point requires the determination of 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 the ultrasonic transducer pair can therefore be determined. Alternatively or in addition, a curvature sensor can also 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.

[0089] 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.

[0090] Reference Mark List

[0091] 1 Clamp-on ultrasonic flow measurement point

[0092] 2 Measuring tube

[0093] 2.11 First measuring tube side

[0094] 2.12 Second measuring tube side

[0095] 2.2 Measuring the pipe axis

[0096] 3 Electronic measurement / operation circuits

[0097] 4 Curvature sensor

[0098] 4.1 Distance Sensor

[0099] 4.2 Spacers

[0100] 4.21 Central Area

[0101] 4.22 End

[0102] 10 Ultrasonic transducer device

[0103] 20 Ultrasonic transducer

[0104] 20.1 First Ultrasonic Transducer

[0105] 20.2 Second Ultrasonic Transducer

[0106] 20.3 The Third Ultrasonic Transducer

[0107] 21 Transducer element

[0108] 22 Coupling element

[0109] 22.1 First contact area

[0110] 22.2 Second contact area

[0111] 30 Support body

[0112] N1 First quantity

[0113] N2 Second quantity

[0114] M1 First quantity

[0115] A1 first spacing

[0116] A2 Second Spacing

[0117] UP1 First ultrasonic signal path

[0118] UP2 Second ultrasonic signal path

[0119] K1,K2 intersection

[0120] N Normals

[0121] U1-U9 Ultrasonic Transducer

[0122] G1 Group 1

[0123] G2 Group 2

[0124] G3 Group 3

[0125] P Parallel Lines

Claims

1. An ultrasonic transducer device (10) for clamping an ultrasonic flow measurement point (1) based on the propagation time difference principle, the ultrasonic transducer device comprising: a plurality of ultrasonic transducers (20), the plurality of ultrasonic transducers (20) being adapted to be arranged on the outer side 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 suitable for radiating ultrasonic signals into the measuring tube and / or receiving ultrasonic signals emitted from the measuring tube. wherein the second contact area has in each case a normal (N), wherein the normal (N) defines a plane in which an ultrasound signal path of the ultrasound signal extends, wherein the first ultrasonic transducer (20.1) defines first ultrasonic signal paths (UP1) extending parallel to one another, and wherein the second ultrasonic transducer (20.2) defines second ultrasonic signal paths (UP2) extending parallel to one another, wherein the ultrasonic signal paths extend in the plane, wherein the ultrasonic signal path of the first ultrasonic transducer and the ultrasonic signal path of the second ultrasonic transducer in the coupling element in each case extend obliquely relative to the second contact region, wherein the direction of the first ultrasonic signal path and the direction of the second ultrasonic signal path are mirror-symmetrical to one of the normal lines, wherein the first ultrasonic signal path has an intersection point (K) with the second ultrasonic signal path in the plane, wherein the intersection point is located at a parallel line (P), and the parallel line (P) extends perpendicularly to the normal line in the plane, wherein the first group (G1) of associated ultrasonic transducers has exclusively a first number (N1) of first ultrasonic transducers, and wherein the second group (G2) of associated ultrasonic transducers has exclusively a second number (N2) of second ultrasonic transducers, wherein adjacent ultrasonic transducers in the first group have in each case a first spacing A1 from one another in the direction of the parallel lines, and wherein adjacent ultrasonic transducers in the second group have in each case a second spacing A2 from one another in the direction of the parallel lines, wherein the first spacing and the second spacing are not equal, It is characterized in that 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, 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.

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 7.

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

6. The ultrasonic transducer device according to any one of claims 1 to 5, in, the coupling element having in each case a longitudinal axis (L), wherein the longitudinal axis has in each case an inner angle α relative to the respective second contact area, wherein the ultrasound signal path extends in the coupling element in the direction of the longitudinal axis, wherein the transducer element has a radial extension rA, wherein rA>3 / (8*a)*A1*sin(α).

7. The ultrasonic transducer device according to claim 6, in, rA>1 / (4*a)*A1*sin(α).

8. The ultrasonic transducer device according to claim 1 or 7, in, The ultrasonic transducer device comprises at least a third group (G3) of ultrasonic transducers having at least one first ultrasonic transducer and / or at least one second ultrasonic transducer, Therein, at least one intersection point formed by the first ultrasonic transducer in the third group and / or the second ultrasonic transducer in the third group supplements a first maximum cardinality (M1) of equidistant parallel lines.

9. The ultrasonic transducer device according to any one of claims 1 to 5, At least a third ultrasonic transducer (20.3) is included, the 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 5, in, The device comprises a support body (30) adapted to position and hold the ultrasound transducer.

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

12. A clamp-on ultrasonic flow measurement point (1) 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 measuring / operating circuitry (3) for operating the ultrasonic transducer and for determining 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 the spacer in the central region, 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 measurement 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 ultrasonic signals in each case simultaneously or offset in time, which are 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 The ultrasonic signal is pulsed and has 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, in the case of a received ultrasonic signal, it is checked 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 measurement point according to any one of claims 12 to 14, 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 measurement point according to claim 13 or 14, in, The electronic measuring / operating circuit (3) determines the outer diameter with the aid of the curvature sensor (4).

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