METHOD FOR ASCERTAINING A CHARACTERISTIC VARIABLE FOR EVALUATING A MEASURING ARRANGEMENT COMPRISING A CLAMP-ON, ULTRASONIC, FLOW MEASURING DEVICE AND A PIPE AND/OR FOR EVALUATING MEASUREMENT OPERATION OF SUCH A MEASURING ARRANGEMENT

Abstract

A method for ascertaining a characteristic variable for evaluating a measuring arrangement comprising a clamp-on, ultrasonic, flow measuring device and a pipe, on which the clamp-on, ultrasonic, flow measuring device is secured, and/or for evaluating measurement operation of such a measuring arrangement, characterized by the method steps as follows: A) providing characteristic values relative to an exciter signal produced by the clamp-on, ultrasonic, flow measuring device; B) providing sensor-specific data as regards acoustic properties of one or more ultrasonic transducers of the clamp-on, ultrasonic, flow measuring device C) inputting data relative to the pipe material and the pipe wall thickness, especially inputting such data by a user, and D) ascertaining the characteristic variable from the parameters and data of steps A-C based on a mathematical model, as well as a computer program product and a clamp-on, ultrasonic, flow measuring device.

Claims

1. A connector assembly (10, 110) comprising: a. a connector part (12) having a jack cavity (14); b. a cable manager part (20) conductively attached to the connector part (12), the cable manager part (20) having: i. a housing assembly (70, 170) having a central aperture (76, 176) through which a cable (4) having an exposed conductive element (5) can extend; ii. a grounding clamp assembly (80, 180) held within the housing assembly (70, 170), the grounding clamp assembly including a first clamp member (82, 182) and an oppositely arranged second clamp member (84, 184), the first and second clamp members (82, 182, 84, 184) defining a clamp opening (88, 188) concentrically aligned with the central aperture (76, 176); iii. a first biasing spring (60, 160) arranged to exert a force on one or both of the clamp members (82, 182, 84, 184) to urge at least one of the ground clamp members (82, 182, 84, 184) against the cable conductive element (5).

2. The connector assembly (10) of claim 1, wherein the first biasing spring (60) extends between the first housing part (72) and the first clamp member (82).

3. The connector assembly (10) of claim 2, further comprising a second biasing spring (62) extending between the first housing part (72) and the second clamp member (84).

4. The connector assembly (110) of claim 1, wherein the first biasing spring (160) extends between the first and second clamp members (182, 184).

5. The connector assembly (110) of claim 4, further comprising a second biasing spring (162) extending between the first and second clamp members (182, 184).

6. The connector assembly (10, 110) of claim 1, wherein the first biasing spring (60, 160) is a spring.

7. The connector assembly (10) of claim 3, wherein the first and second biasing springs (60, 62) are each formed as a spring.

8. The connector assembly (110) of claim 5, wherein the first and second biasing springs (160, 162) are each formed as a spring.

9. The connector assembly (10) of claim 3, wherein the housing assembly (70) includes a first housing part (72) and a second housing part (74) and wherein the grounding clamp assembly first and second clamp members (82, 84) are slidably disposed between the first and second housing parts (72, 74) or within the first housing part (72).

10. The connector assembly (10) of claim 9, wherein the first clamp member (82) is aligned along the same plane as the second clamp member (84).

11. The connector assembly (10) of claim 9, wherein the first clamp member (82) and the second clamp member (84) are aligned along different planes.

12. The connector assembly (110) of claim 5, wherein the grounding clamp assembly first and second clamp members (182, 184) are slidably disposed within the housing assembly (170).

13. The connector assembly (110) of claim 5, wherein the housing assembly (170) includes a first housing part (172) having a front wall (172a) and a rear wall (172b).

14. The connector assembly (110) of claim 11, wherein a clamp portion (82a) of the first clamp member (82) is aligned along a different plane than a clamp portion (84a) of the second clamp member (84) such that the first clamp portion (82a) can slide past the second clamp portion (84a).

15. A connector assembly (10) comprising: a. a connector part (12) having a jack cavity (14); b. a cable manager part (20) conductively attached to the connector part (12), the cable manager part (20) having: i. a housing assembly (70) having a first housing part (72) and a second housing part (74) connected to the first housing part (72), the housing assembly (70) including a central aperture (76) defined by the first and second housing parts (72, 74), the central aperture (76) having a first dimension (D1); ii. a grounding clamp assembly (80) including a first clamp member (82) and a second clamp member (84), each of the first and second clamp members (82, 84) being located at least partially between the first and second housing parts (72, 74), wherein the first grounding clamp (82) includes a clamp portion (82a) and a handle portion (82b) that are connected to each other by a support portion (82c), wherein the second grounding clamp (84) includes a clamp portion (84a) and a handle portion (84b) that are connected to each other by a support portion (84c); iii. wherein the clamp assembly is positionable in: 1. a compressed position in which the clamp portions (82a, 84a) of the respective first and second grounding clamps (82, 84) are moved against a spring biasing force such that the central aperture (76) is unblocked by the clamp portions (82a, 84a) to allow a cable (4) to be inserted through an opening (88) defined by the clamp portions (82a, 84a); and 2. a grounded position in which the clamp portions (82a, 84a) of the respective first and second grounding clamps (82, 84) are spring biased to engage against a conductive element (5) of the cable (4).

16. The connector assembly (10) of claim 13, further comprising a first biasing spring (60) extending between the first housing part (72) and the first clamp member (82).

17. The connector assembly (10) of claim 14, further comprising a second biasing spring (62) extending between the first housing part (72) and the second clamp member (84).

18. The connector assembly (10) of claim 13, wherein the first clamp member (82) and the second clamp member (84) are differently shaped.

19. The connector assembly (10) of claim 13, wherein the first clamp member (82) and the second clamp member (84) have an identical shape.

20. The connector assembly (10) of claim 13, wherein the first and second clamp members (82, 84) are formed from an electrical conductive material.

21. A connector assembly (110) comprising: a. a connector part (12) having a jack cavity (14); b. a cable manager part (120) conductively attached to the connector part (12), the cable manager part (120) having: i. a housing assembly (170) having a first housing part (172) and a second housing part (174) connected to the first housing part (172), the housing assembly (170) including a central aperture (176) defined by the first and second housing parts (172,174), the central aperture (76) having a first dimension (D1); ii. a grounding clamp assembly (180) including a first clamp member (182) and a second clamp member (184), each of the first and second clamp members (182, 184) being located within the first housing part (172), wherein the first grounding clamp (82) includes a ring-shaped clamp portion (82a) connected to a handle portion (82b), wherein the second grounding clamp (84) includes a ring-shaped clamp portion (84a) connected to a handle portion (84b); iii. wherein the clamp assembly is positionable in: 1. a compressed position in which the clamp portions (182a, 184a) of the respective first and second grounding clamps (182, 184) are moved against a spring biasing force such that the central aperture (176) is unblocked by the clamp portions (182a, 184a) to allow a cable (4) to be inserted through an opening (188) defined by the clamp portions (182a, 184a); and 2. a grounded position in which the clamp portions (182a, 184a) of the respective first and second grounding clamps (182, 184) are spring biased to engage against a conductive element (5) of the cable (4).

22. The connector assembly (110) of claim 18, further comprising a first biasing spring (160) extending between the first clamp member (182) and the second clamp member (184).

23. The connector assembly (110) of claim 19, further comprising a second biasing spring (162) extending between the first clamp member (182) and the second clamp member (184).

24. The connector assembly (110) of claim 18, wherein the first clamp member (182) and the second clamp member (184) have an identical shape.

25. The connector assembly (110) of claim 18, wherein the first and second clamp members (182, 184) are formed from an electrical conductive material.

26. The connector assembly (110) of claim 24, wherein the grounding clamp assembly first and second clamp members (182, 184) are slidably disposed between front and rear walls (172a, 172b) defined by the housing assembly (170).

27. The connector assembly (110) of claim 18, wherein the first clamp member (182) and the second clamp member (184) are differently shaped.

Description

[0046] The invention will now be explained in greater detail based on an example of an embodiment and based on the appended figures. The figures of the drawing show as follows:

[0047] FIG. 1 schematic representation of a clamp-on, ultrasonic, flow measuring device;

[0048] FIG. 2 by way of example, graph of measurement error versus frequency;

[0049] FIG. 3 by way of example, graph of relative measurement error versus angle error;

[0050] FIG. 4 example of an electrical exciter signal;

[0051] FIG. 5 graph of a normalized, one-sided, amplitude spectrum of an exciter signal; and

[0052] FIG. 6 by way of example, graph of a system response.

[0053] Clamp-on, ultrasonic, flow measuring devices are known per se. These measuring devices can be used to perform flow determination either based on the travel-time difference principle or according to the Doppler principle. The determination by means of the Doppler principle can be performed with only one ultrasonic transducer, while, in the case of the travel-time difference principle, at least two ultrasonic transducers are applied.

[0054] For the flow measurement, exciter signals with a certain excitation frequency are produced. The excitation frequency is most often selected by the flow measuring device itself from a predetermined frequency range and lies often in the region of the center frequency of the ultrasonic transducers being used.

[0055] FIG. 1 shows an arrangement with a clamp-on, ultrasonic, flow measuring device 1 in the installed state on a pipeline 2. Located in the pipeline 2 is a measured medium 3, which ideally flows through the pipeline 2 in the stream, or flow, direction S.

[0056] The schematically shown clamp-on, ultrasonic, flow measuring device 1 is composed preferably of two ultrasonic transducers 5a and 5b, which are placed externally on the measuring pipe and connected releasably or non-releasably with the pipeline 2. The illustrated variant concerns a two-traverse arrangement. However, other arrangements are possible, e.g. a one-traverse arrangement.

[0057] The ultrasonic transducer 5a shown in FIG. 1 is mounted by means of a holding element 11 for securing the ultrasonic transducer 5a on the pipeline 2. The holding element 11 and the ultrasonic transducer 5a are part of an ultrasonic transducer arrangement. The ultrasonic transducer 5a includes a housing 9, which is connectable with the holding element 11, e.g. frictionally held or by shape interlocking.

[0058] A corresponding ultrasonic transducer 5a includes an electromechanical transducer element 6, e.g. a piezoelement, connected via an electrical connection, e.g. a cable, with an evaluation unit (not shown). The corresponding connection is, in such case, led away from the electromechanical transducer element 6 through a cylindrical cable guide 10 having a longitudinal axis perpendicular to the pipeline 2.

[0059] Ultrasonic transducer 5a additionally includes between the electromechanical transducer element 6 and the pipeline 2 a coupling body 7, which has a bearing surface against the pipe of the pipeline 2 and an area tilted relative to this bearing surface for arrangement of the electromechanical transducer element 6.

[0060] For ascertaining a flow rate or a flow velocity during the measuring, the clamp-on, ultrasonic, flow measuring device, especially the electromechanical transducer element 6 of the ultrasonic transducer 5a, transmits an ultrasonic signal with dominant transmission frequency f.sub.ex and this signal is received by the ultrasonic transducer 5b.

[0061] The measuring occurs according to the travel-time difference principle. Therefore, ultrasonic signals are transmitted and received once inclined in, and once inclined counter to, the flow direction S.

[0062] For the choice of the excitation frequency fex of the electromagnetic transducer element 6, it is known to use the center frequency of the transducer element 6.

[0063] It has been found, however, that the center frequency as excitation frequency is not always the optimal choice for the operation of an ultrasonic, flow measuring device. FIG. 2 is a graph of how the measurement error changes in the frequency range of an ultrasonic transducer. The curve was ascertained for a rotary plant, e.g. a bottling plant, in the case of a volume flow of 20 l/s.

[0064] The two ultrasonic transducers of the clamp-on system were secured on a DN80 pipe of steel with a pipe wall thickness of 2 mm. The center frequency f.sub.c was 2 MHz. As can be seen, the relative measurement error in the region of the center frequency is relatively high in the case of this arrangement.

[0065] A total measurement error of the clamp-on measuring device includes, however, besides the frequency dependent measurement error, other components, which act to reduce a best possible measuring accuracy.

[0066] An appropriate process flow will now be described. First comes customer data.

[0067] This includes [0068] A1 pipe material [0069] B1 pipe wall thickness.

[0070] Additionally, there can be other customer data. This includes: [0071] A2 measuring arrangement data, especially the number of traverses.

[0072] This optional data can, however, also be furnished in a database in the measuring device for a particular mounting arrangement. Thus, it is e.g. possible that the device is always assembled in a two-traverse arrangement, such as shown in FIG. 1. Should this be the case, it needs no separate input. It can also be provided that the center frequency and/or the bandwidth of the exciter signal are also furnished in the device.

[0073] Also furnished in the database in the device is the electrical transfer function of the ultrasonic transducer, with its first bandwidth and its first center frequency. In the case of two ultrasonic transducers, at least two transfer functions are furnished. Also furnished in the database in the device for each ultrasonic transducer is at least one electrical transfer function with its first bandwidth and its first center frequency for at least one temperature of the respective ultrasonic transducer. However, also a plurality of electrical transfer functions can be furnished for each ultrasonic transducer for a plurality of temperature ranges or temperatures.

[0074] Also furnished in the database in the device is a mechanical transfer function of the pipe, or the pipeline, e.g. in the form of a transmission coefficient in the fluid dependent on frequency and angle. However, also a plurality of mechanical transfer functions can be furnished for the pipe for a plurality of temperature ranges or temperatures.

[0075] These electrical transfer functions of the one or more ultrasonic transducers are additionally supplemented by sensor-specific data, which are selected from the following group and which are furnished in the device or input by the user: [0076] A3 diameter of the piezoceramic, [0077] B3 wedge angle of the coupling body, [0078] C3 velocity of sound within the coupling body, [0079] D3 transfer function for one or more ultrasonic transducers, and/or [0080] E3 transfer function of the pipe, or pipeline

[0081] Furthermore, characteristic values relative to an exciter signal are furnished in the database or are input by the user. These characteristics values are selected from the following group: [0082] A4 excitation frequency of the exciter signal [0083] B4 bandwidth of the exciter signal [0084] C4 number of excitation cycles [0085] D4 signal type e.g. sine- or rectangular signal and/or [0086] E4 type of function window, e.g. rectangle-, von Hann- or Tukey window.

[0087] This information can be input or furnished individually or as parameters in a function.

[0088] FIG. 4 shows, by way of example, an exciter signal as a function of time. The excitation frequency amounts to 2 MHz. The signal type is a rectangular signal. The number of the so-called bipolar bursts amounts to three. Bipolar means that the signal extends in the positive and negative voltage ranges. FIG. 4 shows the value normalized to one, since the actual voltage for the operation of the device is irrelevant, since a so-called linear, time invariant (LTI) system is assumed. The shown signal lasts t.sub.burst=1.5 s. The excitation frequency and the number of bursts can be selected variably. The excitation frequency f.sub.ex is the reciprocal of the duration of a rectangle T.sub.ex.

[0089] Ascertained from the exciter signal FIG. 4 by calculating the Fourier-transformation, as a standard method of digital signal processing, can be the associated spectrum. This is divided typically into a phase spectrum and an amplitude spectrum. The normalized, one-sided, amplitude signal is shown in FIG. 5. Shown in the spectrum are the excitation frequency f.sub.ex and the strongest (dominant) frequency f.sub.ex,dom. The deviation is not intuitive and can be explained by the spectral leakage effect. The signal is characterized, furthermore, by the bandwidth, e.g. the width of the main lobe at 6 dB. A further characteristic is the attenuation of the strongest side lobe.

[0090] Additionally furnished in a data carrier in the measuring device is a mathematical model.

[0091] Fed to the model as input data can be the spectrum shown in FIG. 5 (magnitude and phase). The special feature of the model is that, supplementally to frequency information, also angle information is taken into consideration. Because of this, all components of the model are modeled as a two dimensional filter with dependence on frequency and phase velocity.

[0092] A typical model, which only takes frequency into consideration, can be described with the formula

[00001]$Y\left(f\right)=\underset{n}{.Math.}.Math.A_n\left(f\right).Math.X\left(f\right)$

[0093] wherein X(f) corresponds to the spectrum of the excitation and A.sub.n(f) to the transfer function of the n-th model-component. Y(f) is then the system response.

[0094] Corresponding mathematical models, which only take frequency into consideration are discussed in the following documents:

[0095] Ali, M.; Raouf Mohamed, A.: A simulation of pulse-echo amplitude scan signal formation in absorbing media. In: Ultrasonics, 30(5), 1992, pgs. 311-316, especially Equation 7,

[0096] and

[0097] Woeckel, S., Steinmann, U., Auge, J.: Signalanalyse fur Ultraschall-Clamp-on-Systeme (Signal analysis for ultrasonic, clamp-on systems). In: tmTechnisches Messen, 81(2), 2014, pgs. 86-92, especially Equation 2.

[0098] Additionally to the input of the values for the pipe material and the pipe wall thickness, the mathematical model draws on the values furnished in the data memory relative to the electrical transfer functions of the ultrasonic transducers, their geometry- and material data, as well as the characteristic values of the exciter signal.

[0099] From these data, the ascertaining of an actual angle .sub.f in the fluid can occur, with which angle the sound mainly propagates in the liquid located in the pipe. This angle .sub.f in the fluid is an embodiment variant of a measurement error factor in the sense of the present invention. With it, a measurement error can be ascertained and, in given cases, also compensated, such as described e.g. in the article Extraction of Spatial Ultrasonic Wave Packet Features by Exploiting a Modified Hough Transform by Plo, P., Rupitsch, S. J. and Lerch, R. (IEEE Sensor Journal, 14(7), 2014), to which comprehensive reference is taken in the context of the present invention

[0100] An expanded model takes into consideration also the angle in the fluid. It is expressed as follows:

Y(f, .sub.f)=.sub.nA.sub.n(f, .sub.f).Math.X(f, .sub.f),

[0101] thus as in the case of the aforementioned one-dimensional model, only that both the components as well as also the in/output depend both on frequency and on angle.

[0102] Mathematical models, which take the locational information, i.e. the angle, into consideration are presented in the following documents:

[0103] Pavlakovic, B. N.; Rose, J. L.: The Influence of Finite-Size Sources in Acousto-Ultrasonics/NASA. 1994 (195374).Research Report, especially pg. 70,

[0104] and

[0105] Funck, B.; Mitzkus, A.: Acoustic transfer function of the clamp-on flowmeter. In: IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 43(4), 1996, pgs. 569-575, especially Equations 27 and 33.

[0106] The angle information .sub.n of a medium n can be converted with the aid of the velocity of sound of the medium n into the phase velocity c.sub.p.sup.0:

[00002]$c_p^0=\frac{c_n}{\sin \left({}_n\right)}$

[0107] Shown in FIG. 6 is the two dimensional amplitude spectrum of the system response calculated with the model.

[0108] Reference character 101 refers to the electrical excitation frequency f.sub.ex=2 MHz

[0109] and

[0110] reference character 102 references the expected phase velocity c.sub.p.sup.0. The phase velocity is calculated via Snell's law of refraction and, transformed into angle information, it corresponds, for water with velocity of sound 1485 m/s, to the expected angle .sub.f.sup.0 in the fluid and amounts, for instance, to 22. That is the angle in the fluid, which angle is decisive for calculating the volume flow rate. If this angle deviates in water from the expected angle, then this leads to a measurement error of the volume flow rate.

[0111] The system response has the shape of an eye, whose pupil (the maximum) lies at a certain location of the two-dimensional coordinate system (frequency, phase velocity, or angle). If the pipe wall would not influence the sound propagation, then the maximum of the eye would lie at the intersection of the lines 101 and 102.

[0112] Since, however, the pipe wall has a significant influence on the sound propagation, the position of the eye is shifted significantly from the expected intersection. The system response can now be evaluated automaticallyand, indeed, in several ways.

[0113] The simplest option for evaluation is to determine the maximum and to extract the coordinates of the same (f.sub.rec,dom 103 and c.sub.p,rec,dom 104). The vertical shift (change of the phase velocity c.sub.p,rec,domc.sub.p.sup.0) is directly convertible into a change of the angle in the fluid. Additionally, a measurement error can be predicted. There are, however, also various other options for evaluating the system response.

[0114] In the case of ascertaining the measurement error factor, optionally also data for the measuring arrangement can be taken into consideration.

[0115] In addition to ascertaining, and, in given cases, compensating, a measurement error, the measurement error factor can also be used just to provide a failure warning, to the extent that this factor exceeds or subceeds a predetermined desired value. This failure warning can indicate to a user e.g. that a situation, or a configuration, is present, which can lead to a large measurement error. Thus, also in the context of a preliminary analysis, e.g. in an Internet sales site, after input of the pipe material and the pipe wall thickness, a measurement error factor can be ascertained for all offered clamp-on measuring devices and the most suitable product provided.

[0116] By comparison of the measurement error factor ascertained using the mathematical model with an actually measured measurement error factor, additionally, temperature influences, deposits or abrasion on the pipe wall can be identified during the measuring.

[0117] FIG. 3 shows the measured value error in percent versus the actual angle error in degrees. This angle error can only be determined with the aid of certain parameters, such as described above. The angle error permits a direct evaluation of the measured value error and enables a quantifying and even a compensation of the measured value error, so that a highly accurate measuring in the case of clamp-on, ultrasonic, flow measuring devices can be achieved.