MEASURING SYSTEM FOR DETERMINING THE VOLUME FLOW AND / OR THE VOLUME FLOW RATE OF A MEDIUM FLOWING IN A PIPELINE

Description

[0001] The invention relates to a measuring system for determining a volume flow rate, namely a total volume flowing during a predeterminable or predetermined measuring interval, and / or a volume flow rate of a medium, in particular a liquid or a gas, flowing in a pipeline, especially at least temporarily with a mass flow rate of more than 100 t / h.

[0002] In process measurement and automation technology, measuring systems—mostly compact in-line measuring devices—are often used to measure physical parameters such as mass flow rate, volumetric flow rate, density, and / or viscosity of media flowing in pipelines. These systems utilize a vibration-type sensor through which the medium flows, connected to a measuring and driver circuit. They generate reaction forces in the medium, such as Coriolis forces corresponding to mass flow rate, inertial forces corresponding to density, and / or frictional forces corresponding to viscosity. From these forces, a measurement signal representing the respective mass flow rate, viscosity, and / or density of the medium is derived.Especially those designed as Coriolis mass flow meters or Coriolis mass flow / density meters, sensors or measuring systems formed therewith are, for example, in CN-A 10 18 58 765, EP-A 1 001 254, EP-A 816 807, EP-A 553 939, US-A 2002 / 0157479, US-A 2006 / 0150750, US-A 2006 / 0162468, US-A 2007 / 0151368, US-A 2008 / 0047361, US-A 2010 / 0242623, US-A 2011 / 0016991, US-A 2011 / 0146416, US-A 2011 / 0154914, US-A 2011 / 0265580, US-A 2011 / 0113896, US-A 2012 / 0048034, US-A 2012 / 0073384, US-A 2012 / 0079891, US-A 2012 / 0090407, US-A 2012 / 0109543, US-A 2012 / 0167697, US-A 47 77 833, US-A 47 93 191, US-A 48 01 897, US-A 48 23 614, US-A 48 79 911, US-A 50 09 109, US-A 50 24 104, US-A 50 50 439, US-A 53 70 002, US-A 56 61 232, US-A 57 96 011, US-A 58 04 741, US-A 63 11 136, US-B 63 08 580, US-B 63 11 136, US-B 64 15 668, US-B 67 11 958, US-B 69 20 798,US-B 71 34 347, US-B 73 92 709, US-B 79 92 452, WO-A 00 / 57141, WO-A 01 / 067052, WO-A 03 / 027616, WO-A 2008 / 039203, WO-A 2011 / 008307, WO-A 2011 / 008308, WO-A 2011 / 019344, WO-A 2011 / 068500, WO-A 2012 / 028425, WO-A 90 / 15309, WO-A 90 / 15310, WO-A 94 / 21999, WO-A 96 / 05484, WO-A 97 / 33150, WO-A 98 / 038479 or also the unpublished German patent application 102011089808.5 described in detail.

[0003] Each sensor has a housing, the first end of which, at the inlet end, is formed at least partially by a first flow divider having at least two spaced-apart circular cylindrical or conical flow openings, and the second end of which, at the outlet end, is formed at least partially by a second flow divider, also having at least two spaced-apart flow openings. In some of the sensors shown in US-A 5796011, US-B 7350421, US-A 2007 / 0151368, US-A 2011 / 0146416, US-A 2011 / 0146416, or, for example, US-A 2011 / 0265580, the housing comprises a relatively thick-walled circular cylindrical tube segment that forms at least a central segment of the housing.

[0004] To guide the medium, which flows at least intermittently and may be multiphase, the measuring sensors further comprise two – in the case of, for example, US-A 2011 / 0146416, US-A 2011 / 0146416 or US-A 2011 / 0265580, at least four – flow-technically parallel measuring tubes made of metal, especially steel or titanium, which are placed inside the housing and held in place – forming a vibration element, sometimes also referred to as an inner part – by means of the aforementioned flow divider so that they can vibrate.A first of the identical and parallel measuring tubes opens with its inlet end into a first flow opening of the inlet-side first flow divider and with its outlet end into a first flow opening of the outlet-side second flow divider; a second of the measuring tubes opens with its inlet end into a second flow opening of the first flow divider and with its outlet end into a second flow opening of the second flow divider. In the case of US-A 2011 / 0146416, US-A 2011 / 0146416, respectively.US-A 2011 / 0265580 further specifies that a third measuring tube opens with its inlet end into a third flow opening of the first flow divider and with its outlet end into a third flow opening of the second flow divider, and a fourth measuring tube opens with its inlet end into a fourth flow opening of the first flow divider and with its outlet end into a fourth flow opening of the second flow divider. Each flow divider also has a connection flange with a sealing surface for fluid-tight connection of the sensor to a pipeline segment used for supplying or removing medium from the sensor.

[0005] The measuring tubes, and thus the vibrating element formed by them, are vibrated during operation to generate the aforementioned reaction forces. This vibration is driven by at least one exciter that serves to generate or maintain mechanical vibrations, especially bending vibrations, of the measuring tubes in the so-called drive or operating mode. The vibrations in the operating mode (operating mode vibrations) are usually, especially when the sensor is used as a Coriolis mass flow meter and / or density meter, at least partially formed as lateral bending vibrations of each measuring tube around an imaginary axis of vibration. In the case of a medium flowing through the measuring tubes, these vibrations are superimposed by additional, frequency-matched vibrations in the so-called Coriolis mode due to Coriolis forces induced therein (Coriolis mode vibrations).Accordingly, the excitation arrangement – ​​mostly electrodynamic in this case – is designed in such a way that the at least two measuring tubes in the operating mode can be excited at least partially, and in particular predominantly, to opposite bending vibrations in a common plane of vibration differentially – i.e., by simultaneously applying excitation forces along a common line of action, but in opposite directions.

[0006] To detect vibrations of the vibration element, in particular bending vibrations of the measuring tubes excited by means of the excitation arrangement, and to generate vibration measurement signals representing vibrations of the vibration element, measuring transducers of the aforementioned type also each have a vibration sensor arrangement, usually also electrodynamic, that reacts to relative movements of one or more of the measuring tubes.Typically, the vibration sensor arrangement consists of an inlet-side vibration sensor that detects vibrations of the measuring tubes differentially—that is, only relative movements of the measuring tubes—and an outlet-side vibration sensor that also detects vibrations of the measuring tubes differentially. Each sensor generates a vibration signal dependent on the vibrations of the vibrating element, with a signal frequency corresponding to the instantaneous vibration frequency of the vibrating element. A relative phase difference, dependent on the instantaneous mass flow rate, exists between the vibration signal of the inlet-side vibration sensor and the vibration signal of the outlet-side vibration sensor. Each of the vibration sensors, which are usually identical in construction, consists of a permanent magnet mounted on the first measuring tube and a cylindrical coil mounted on the second measuring tube, through which the magnet's magnetic field passes.

[0007] During operation, the vibration element of the sensor, as described above and formed by at least two measuring tubes, is excited to mechanical vibrations at least temporarily in the operating mode by means of the electromechanical excitation arrangement, at least at least at one dominant operating frequency. The operating frequency for the vibrations in the operating mode is typically a natural instantaneous resonant frequency of the vibration element, which in turn depends essentially on both the natural frequency of the vibration element (determined, among other things, by its size, shape, and material) and the instantaneous density of the medium contacting the vibration element; this operating frequency may also be significantly influenced by the instantaneous viscosity of the medium.Due to fluctuating density of the medium being measured and / or medium changes during operation, the operating frequency of the sensor is naturally variable, at least within a calibrated and therefore predefined frequency band, which accordingly has a predefined lower and upper cutoff frequency. Based on the currently excited operating frequency, which corresponds to the instantaneous resonant frequency of the vibrating element, such measuring systems can determine the density of the medium. Alternatively, based on a combination of the operating frequency and the aforementioned phase difference between the vibration signals of the vibration sensors, a volumetric flow rate or volumetric flow rate can also be determined.To define a free oscillation length of the measuring tubes and thus to adjust the usable frequency band, sensors of the type described above typically include at least one inlet-side coupler element for forming inlet-side vibration nodes for opposing vibrations, especially bending vibrations, of both measuring tubes. This coupler element is fixed to both measuring tubes at a distance from both flow dividers. They also include at least one outlet-side coupler element for forming outlet-side vibration nodes for opposing vibrations, especially bending vibrations, of the measuring tubes. This outlet-side coupler element is fixed to both measuring tubes at a distance from both flow dividers and the inlet-side coupler element. The coupler elements can also be used to influence the vibration quality of the internal part as well as the overall sensitivity of the sensor.

[0008] The respective sensor is further connected to the measuring and operating electronics of the measuring system, which serve to evaluate the at least one vibration measurement signal and to generate corresponding measured values, for example, representing the mass flow rate, the volumetric flow rate, or the density. In modern measuring systems of the type in question, such measuring and operating electronics, as described, for example, in the aforementioned US-B 63 11 136, are usually implemented by means of one or more microprocessors, possibly also designed as digital signal processors (DSPs).In addition to evaluating the vibration measurement signal, the measurement and operating electronics also serve to generate at least one driver signal, for example, a harmonic and / or clocked signal, for the at least one vibration exciter acting on the vibrating element. This driver signal can be a broadband signal with a signal component whose frequency matches the resonant frequency of the vibrating body, or, for example, a narrower bandwidth or harmonic signal with a single dominant signal component of a suitable frequency. This signal component, or the driver signal as a whole, can also be controlled, for example, with respect to current and / or voltage. In measurement systems of this type, the measurement and operating electronics are usually housed within at least one relatively robust electronic enclosure, which is particularly impact-, pressure-, and / or weatherproof.The electronics housing can, for example, be located remotely from the sensor and connected to it only via a flexible cable; however, it can also be located directly on the sensor or in a sensor housing that separately encloses the sensor and thus its vibrating element, as shown, for example, in the aforementioned US-A 5796011. Furthermore, as shown, among others, in WO-A 01 / 29519 or US-A 5661232, it is also quite common to use modular electronics, possibly housed in two or more separate enclosure modules, to form measuring systems of the type in question.Typically, the respective measuring and operating electronics are also electrically connected via appropriate electrical lines to a higher-level electronic data processing system, which is usually located spatially remote from the respective measuring system and is also usually spatially distributed, to which the measured values ​​generated by the respective measuring system are transmitted in a timely manner by means of a corresponding measured value signal.Measuring systems of the type described are typically interconnected and / or linked to corresponding electronic process controllers via a data transmission network provided within the higher-level data processing system. These controllers may include, for example, locally installed programmable logic controllers (PLCs) or process control computers installed in a remote control room. The measured values ​​generated by the respective measuring system, appropriately digitized, and coded, are then transmitted to these process control computers. These process control computers can further process the transmitted measured values ​​and visualize them as measurement results, for example, on monitors, and / or convert them into control signals for field devices other than actuators, such as solenoid valves, electric motors, etc.Since modern measurement systems can usually be monitored and, if necessary, controlled and / or configured directly from such central computers, operating data assigned to the measurement system is transmitted accordingly via the aforementioned data transmission networks, which are typically hybrid in terms of transmission physics and / or transmission logic. Accordingly, the data processing system also usually serves to condition the measurement signal supplied by the measurement system according to the requirements of downstream data transmission networks, for example, to digitize it appropriately and, if necessary, convert it into a corresponding telegram, and / or to evaluate it locally. For this purpose, such data processing systems include electrically coupled evaluation circuits connected to the respective interfaces, which pre-process and / or further process the measurement values ​​received from the respective measurement system and, if necessary, convert them appropriately.In such industrial data processing systems, data transmission is carried out, at least in part, using fieldbuses, particularly serial ones, such as Foundation Fieldbus, Rackbus-RS 485, PROFIBUS, etc., or networks based on the Ethernet standard, as well as the corresponding, mostly standardized, transmission protocols. Alternatively or additionally, in modern measuring systems of this type, measured values ​​can also be transmitted wirelessly to the respective data processing system. Besides the evaluation circuits required for processing and converting the measured values ​​supplied by the connected measuring systems, such higher-level data processing systems usually also have electrical power supply circuits for providing the connected measuring systems with electrical energy, which may include a corresponding, possibly...The supply voltage, fed directly from the connected fieldbus, provides power to the respective measurement and operating electronics and drives the electrical currents flowing through the connected electrical lines and the respective measurement and operating electronics. A supply circuit can, for example, be assigned to exactly one measurement system or corresponding measurement and operating electronics unit and housed together with the evaluation circuit assigned to that measurement system – for example, combined into a corresponding fieldbus adapter – in a common electronics enclosure, such as a DIN rail module. However, it is also quite common to house the supply circuits and evaluation circuits in separate, possibly spatially separated, electronics enclosures and to wire them together via external lines.

[0009] Developments in the field of vibration-type flowmeters have progressed to the point where modern systems of this type can meet the highest demands for precision and reproducibility of measurement results across a very broad range of flow measurement applications. In practice, these flowmeters and the measurement systems they form are used for mass flow rates ranging from just a few g / h (grams per hour) to several t / min (tons per minute), at pressures up to 10 MPa (megapascals) for liquids or even over 30 MPa for gases. The resulting measurement accuracy is typically around 99.9% of the actual value or higher, with a measurement error of approximately 0.1%, although the lower limit of the guaranteed measuring range can be as low as 1% of the full-scale value.Due to their wide range of applications, industrial-grade measuring systems with vibration-type sensors are offered in nominal diameters (corresponding to the diameter of the pipeline to be connected to the sensor or the diameter of the sensor measured at the connection flange) ranging from 0.5 mm to 400 mm. These systems are specified for pressure losses of less than 0.1 MPa at maximum nominal mass flow rates, for example, even exceeding 3000 t / h. The diameter of each of the measuring tubes used can easily exceed 80 mm for larger nominal diameters.

[0010] Despite the availability of flow sensors for use in pipelines with very high mass flow rates and correspondingly large diameters well over 100 mm, there remains considerable interest in using high-precision, low-pressure-loss sensors for even larger pipeline diameters, approximately 450 mm or more, and mass flow rates of 3000 t / h or more. The flow sensors shown in the aforementioned US-A 2011 / 0265580, featuring a vibrating element with four curved measuring tubes, are undoubtedly suitable for meeting these requirements and can therefore be designed for large nominal diameters exceeding 450 mm. This is particularly relevant in applications where the volumetric flow rate is also high.The volumetric flow rate is of particular interest, for example for applications in the petrochemical industry or in the transport and handling of crude oil, natural gas, fuels, etc.

[0011] However, in industrial plants with pipelines, relatively small lateral clearances between the medium-carrying pipeline and adjacent plant components can sometimes significantly complicate or even completely preclude the use of sensors or measuring systems that, by design, have comparatively large lateral dimensions. In contrast, sensors with four straight measuring tubes, as described, for example, in the aforementioned WO-A 2012 / 028425, US-A 2011 / 0146416, US-A 2012 / 0073384, US-A 2012 / 0079891, and US-A 2012 / 0227512, can be dimensioned much more compactly than those with curved measuring tubes of the same nominal diameter, making their use particularly advisable for applications with limited space. Vibration-type sensors, in which the vibrating element has straight measuring tubes, as shown, among others, in US-A 56 61 232, demonstrate, among other things,Also mentioned in US-A 2012 / 0073384 and US-A 4823614, this type of vibrating element exhibits increased lateral sensitivity to mechanical stresses compared to those where the vibrating element is formed by two or more curved measuring tubes. This sensitivity stems from clamping forces introduced via the pipework—primarily axial, acting in the direction of the intended vibration or a parallel longitudinal axis of the measuring tube—and the resulting mechanical stresses in the vibrating element. This sensitivity can also be attributed to mechanical stresses in the vibrating element resulting from thermally induced elastic deformation of the measuring tubes. As discussed in US-A 2012 / 0073384, this also applies when the vibrating element is formed by four straight measuring tubes, each with a diameter greater than 60 mm.

[0012] Although clamping forces have only a minor influence on the measurement accuracy with which mass flow or mass flow rate is determined, or can be compensated for with minimal effort, for example by using temperature and / or strain sensors, the influence of clamping forces and the resulting mechanical stresses in the vibrating element on the measurement accuracy in density measurement is quite significant. Consequently, the volumetric flow rate and the derived volumetric flow rate can also exhibit correspondingly fluctuating measurement accuracy. To make matters worse, in measuring systems of the type in question, clamping forces are potentially greater the higher the nominal mass flow rate to be measured or the larger the nominal diameters are chosen. This is particularly problematic for applications where the precise determination of high volumetric flow rates is of primary interest.high volumetric flow rates, because the precise determination of mass flow rates is essential, can occasionally lead to measurement inaccuracies in measuring systems of the type in question that are no longer tolerable.

[0013] Based on the aforementioned prior art, one object of the invention is therefore to provide a measuring system for determining a volumetric flow rate and / or a volumetric flow rate of a medium in a pipeline, also based on vibrations of a vibrating element formed by means of at least one measuring tube, which exhibits as little or no cross-sensitivity as possible to any changes in stress states in the vibrating element, for example as a result of temperature changes or gradients within the vibrating element and / or as a result of external forces acting on the vibrating element, such as clamping forces introduced via the connected pipeline, or that enables an accurate measurement of volumetric flow rates or volumetric flow rates even in large pipelines with a nominal diameter of more than 100 mm and / or at mass flow rates of more than 100 t / h, in particular more than 1000 t / h.

[0014] To solve this problem, the invention comprises a measuring system for determining a volumetric flow rate, namely a total volume flowed during a measuring interval, and / or a volumetric flow rate of a medium flowing in a pipeline - for example a liquid or a gas, according to independent claim 1.

[0015] The measuring system according to the invention can also be manufactured, for example, using two conventional and / or individually usable vibration-type sensors, which only require minor modifications so that each of the two sensors in the completed measuring system can be both through which the medium to be measured flows and which can be connected to the measuring and operating electronics that ultimately deliver the desired measured values. Furthermore, the measuring system formed in the manner described above, namely by means of a sensor assembly comprising two vibration-type sensors, can also be provided in a very simple manner, for example, by connecting two otherwise independent measuring devices, namely a Coriolis mass flow meter and a vibronic density meter, accordingly in terms of flow and signal technology.

[0016] The invention and further advantageous embodiments thereof are explained in more detail below with reference to exemplary embodiments illustrated in the figures of the drawing. Identical parts are designated with the same reference numerals in all figures; where clarity requires it or it otherwise appears appropriate, previously mentioned reference numerals are omitted in subsequent figures. Further advantageous embodiments or developments, in particular combinations of aspects of the invention initially described only individually, will also become apparent from the figures of the drawing as well as from the dependent claims themselves.

[0017] Specifically, we show: Fig. 1, 2a, 2bein - here designed as a compact measuring device - measuring system of industrial measurement and automation technology for measuring a volumetric flow rate and / or a volumetric flow rate of a medium flowing in a pipeline in various side views; Fig. 3 schematically in the manner of a principle sketch of a measuring system according to Fig. 1 with two vibration elements housed within one and the same casing, each through which medium flows at least temporarily during operation of the measuring system; Fig. 4, 5 schematically according to a principle sketch, further embodiment variants for a measuring system according to Fig. 1 with two vibration elements housed within the same casing, each at least temporarily permeated by the medium during operation of the measuring system; Figs. 6, 7a, 7b schematically depict a further embodiment of a measuring system according to a principle sketch. Fig. 1 with two vibration elements housed within the same casing, each at least temporarily through which the medium flows during operation of the measuring system, one of which is formed by means of four flow-parallel measuring tubes; Fig. 8 schematically in the manner of a principle sketch of a further embodiment of a measuring system according to Fig. 1 with two vibration elements housed within the same casing, each at least temporarily permeated by the medium during operation of the measuring system, and with two separate electronic modules communicating with each other; and Fig. 9 schematically, in the manner of a principle sketch, a further embodiment of a measuring system according to Fig. 1 with a vibration element housed inside a casing, through which medium flows during operation of the measuring system, and with a further vibration element attached to the outside of the casing, which is also subjected to medium flow during operation of the measuring system.

[0018] In the Fig. 1-9 A measuring system for determining a volumetric flow rate v, i.e., the total volume flowed during a predefined or predetermined measurement interval, and / or a volumetric flow rate v of a medium flowing in a pipeline, in particular a liquid or gas, is schematically represented in different views and configurations. The measuring system comprises measuring and operating electronics ME, implemented in particular by means of at least one microprocessor and / or a digital signal processor (DSP), for generating measured values ​​representing the volumetric flow rate v or the volumetric flow rate v, or for outputting such a measured value as a currently valid measured value X of the measuring system at a corresponding measuring output of the measuring and operating electronics ME. The measuring and operating electronics ME can be configured as described in the Fig. 1 , 2a , 2b and 3As indicated, it can be housed in a single electronics enclosure (HE) of the measuring system. If necessary, the measuring and operating electronics (ME) can also be housed in other enclosures, as is the case, for example, in the Fig. 8 or as shown schematically in 9, it is formed by means of two communicating electronic modules ME 1, ME 2, each of which is housed in one of two or more separate electronic housings HE, HE' of the measuring system. The measured values ​​X generated by the measuring and operating electronics ME can, for example, be displayed locally. To visualize measured values ​​generated internally by the measuring system and / or, if applicable, system status messages generated internally by the measuring system, such as an error message or an alarm, the measuring system, as well as Fig. 1 As indicated, the measurement and operating electronics may include, for example, a display and control element (HMI) that communicates with the measurement and operating electronics and may be portable. This could be an LCD, OLED, or TFT display located in the HE electronics housing behind a correspondingly provided window, along with a corresponding keypad and / or touchscreen. Advantageously, the measurement and operating electronics, which may also be (re)programmable or remotely configurable, can be designed to exchange measurement and / or other operating data, such as current measured values, system diagnostic values, or settings used to control the measuring device, with a higher-level electronic data processing system, such as a programmable logic controller (PLC), a personal computer, and / or a workstation, via a data transmission system, such as a fieldbus system, and / or wirelessly via radio.Furthermore, the measurement and operating electronics (ME) can be designed to be powered by an external power supply, for example, via the aforementioned fieldbus system. If the measurement system is intended for connection to a fieldbus or other communication system, the measurement and operating electronics (ME), which can be (re)programmed locally and / or via a communication system, can have a corresponding communication interface for data communication, in particular one compliant with the relevant industry standards. This interface is used, for example, to send measurement and / or operating data, i.e., measured values ​​representing the volumetric flow rate (v) or volumetric flow rate (v), to the aforementioned programmable logic controller (PLC) or a higher-level process control system, and / or to receive setting data for the measurement system.Furthermore, the measurement and operating electronics (ME) can, for example, have an internal power supply circuit that, during operation, is powered by an external power supply provided in the aforementioned data processing system via the aforementioned fieldbus system. In this case, the measurement system can, for example, be designed as a so-called four-wire measuring device, in which the internal power supply circuit of the measurement and operating electronics (ME) is connected to an external power supply via a first pair of wires, and the internal communication circuit of the measurement and operating electronics (ME) is connected to an external data processing circuit or an external data transmission system via a second pair of wires.

[0019] In addition to the measuring and operating electronics ME, the measuring system according to the invention further comprises a first vibration element V1 having a lumen, which is configured to guide a portion of the medium flowing at a first mass flow rate m 1 in that lumen and to vibrate it during this time; in particular, the vibration element V1 is configured to be inserted into the course of the pipeline and connected to it, namely to a first pipeline segment L1 and a second pipeline segment L2, in such a way that the lumen of the vibration element V1 communicates with a respective lumen of each of the two pipeline segments L1, L2 and at least one flow path is formed which enables fluid flow from pipeline segment L1, further through the vibration element V1 to pipeline segment L2.Furthermore, the measuring system comprises at least one first vibration exciter E1, which is electrically connected to and controlled by the measuring and operating electronics, for example by means of a pair of connecting wires (not shown here for the sake of clarity), to excite vibrations of the vibration element V1, such that the vibration element V1 performs at least partially resonant vibrations, namely mechanical vibrations with a first resonant frequency f r1. In particular, such resonant vibrations are excited here – occasionally also referred to as operating mode or drive vibrations – whose resonant frequency is, firstly, highly dependent on the density ρ of the medium, and secondly, which exhibit the highest possible sensitivity to changes in density, thus enabling a high resolution of even slight density fluctuations.The measuring and operating electronics are further configured to generate, at least temporarily, an electrical first driver signal e1 for the vibration exciter E1 – for example, an electrodynamic one formed by means of a moving armature coil – which is regulated to a predetermined voltage level and / or current intensity. This signal serves to supply the vibration exciter E1 in a controlled manner with at least the electrical power required to excite or maintain the useful mode oscillations, and has a signal frequency corresponding to the (instantaneous) resonance frequency f r1 of the vibration element V1.

[0020] To detect vibrations of the vibration element V1, not least of resonant vibrations excited by means of the vibration exciter E1, the measuring system further comprises a first vibration sensor S1, which is electrically connected to the measuring and operating electronics, for example by means of another pair of connecting wires (not shown here for the sake of clarity), and a second vibration sensor S2, which is spaced apart from the first vibration sensor S1 and is electrically connected to the measuring and operating electronics in the same way as the first vibration sensor S1 and / or is identical in construction to the vibration sensor S1.The vibration sensor S1 is configured to generate a first vibration signal s1 dependent on vibrations of the vibration element 10, which has a signal frequency corresponding to the vibration frequency of the useful mode vibrations, i.e., the currently excited resonance frequency f r1 of the vibration element V1, while the vibration sensor S2 is configured to generate a second vibration signal s2 dependent on vibrations of the vibration element V1, such that the vibration signal s2 has a signal frequency equal to the signal frequency of the first vibration signal s1, i.e., corresponding to the same resonance frequency f r1 of the vibration element V1, and has a phase difference Δφ 12 relative to the first vibration signal that depends on the first mass flow rate m 1.

[0021] The vibration exciter E1, as well as the vibration sensors s1 and s2, are arranged, as is typical for such vibration elements, on the outside of the vibration element V1, specifically on the side that is not in contact with the medium being measured, even during operation. The vibration exciter E1 serves, in particular, to convert an electrical excitation power Pexc1, supplied by the electrical driver signal e1, into, for example, pulsating or harmonic, essentially sinusoidal, excitation forces Fexc1, which act accordingly on the vibration element and thus actively excite the desired resonant vibrations. For example, the at least one driver signal e1 can simultaneously contain a multitude of sinusoidal signal components with different signal frequencies, one of which—for instance, a signal component that is dominant at least temporarily with respect to signal power—has a signal frequency corresponding to the resonant frequency fr1.The excitation forces Fexc – ultimately generated by converting the electrical excitation power Pexc1 fed into the vibration exciter E1 – can be generated in a manner known to those skilled in the art, namely by means of a driver circuit provided in the measurement and operating electronics ME. This driver circuit receives the driver signal e1 based on the signal frequency and signal amplitude of at least one of the sensor signals s1, s2, and provides it via an output channel. For determining the instantaneous resonant frequency or for setting the corresponding signal frequency for the driver signal, a digital phase-locked loop (PLL) can, for example, be provided in the driver circuit, while the current of the driver signal, which determines the magnitude of the excitation forces Fexc1, can be appropriately adjusted, for example, by means of a corresponding current controller in the driver circuit. The measurement and operating electronics can be used here, for example, as a...B. also be designed to control the driver signal e1 in such a way that the resonant vibrations have a constant amplitude, and thus one that is largely independent of the density ρ or the viscosity η of the medium being measured. The design and use of the aforementioned phase-locked loops for actively exciting vibrational elements of the type in question at an instantaneous resonant frequency is described in detail, for example, in US Patent 4801,897. Of course, other driver circuits suitable for setting the excitation energy E exc1 or the excitation power P exc1, which are known to those skilled in the art, can also be used, for example, according to the aforementioned prior art, such as the aforementioned US-A 47 77 833, US-A 48 01 897, US-A 48 79 911, US-A 50 09 109, US-A 50 24 104, US-A 50 50 439, US-A 58 04 741, or US-A 63 11 136.Furthermore, with regard to the use of such driver circuits, reference should also be made to the measuring and operating electronics provided with measuring transducers (transmitters) of the series "PROMASS 100", "PROMASS 40", "PROMASS 80", "PROMASS 83" and "PROMASS 84", as offered by the applicant, among others, in conjunction with measuring transducers of the series "PROMASS E", "PROMASS F", "PROMASS H", "PROMASS I", "PROMASS P", "PROMASS S" and "PROMASS X", which also serve to measure mass flow rate and density, for example also via the internet at http: / / www.us.endress.com / #products / -flowmeasurment-flowmeter-coriolis-masss.

[0022] The measuring system further comprises at least one housing H with a lumen H' that is hermetically sealed, particularly from the surrounding atmosphere, and optionally also pressure- and / or explosion-proof, within which the first vibration element V1 is housed together with the at least one vibration exciter E1 and the two vibration sensors S1, S2. Compared to the vibration element V1, the housing H is significantly more rigid in terms of bending and torsion and also has a first housing end H1 that can be connected to the first pipe segment L11 of the pipeline, for example by means of a flange connection, and a second housing end H2 that can be connected to the second pipe segment L12 of the pipeline, for example by means of a flange connection. As can be seen from the overall view of the Fig. 1 , 2a , 2b and 3It is readily apparent that the housing end H1 therefore has at least one first flow opening O i,11 of the first kind – namely, a first flow opening communicating with the vibration element V1 – and the housing end H2 has at least one first flow opening O i,21 of the first kind – namely, a first flow opening communicating with the vibration element V1. Furthermore, each of the two housing ends has a corresponding connecting flange. Moreover, the housing H, as also in Fig. 1 The device, shown schematically, has a neck-like mounting sleeve to which at least one electronic housing HE is mounted, forming a compact measuring instrument. Within the mounting sleeve, a hermetically sealed and / or pressure-resistant feedthrough, for example made by means of glass and / or plastic potting, can be arranged for electrical connecting wires leading from the measuring and operating electronics into the lumen H' of the housing H.

[0023] The vibration element V1 of the measuring system according to the invention is, as can be seen from the overview of the Fig. 1 bis 3 It is readily apparent that the system is formed by means of at least one measuring tube 11 – for example, a straight, i.e., circular cylindrical – of a predefinable diameter (DN11), which is inserted into the pipeline during operation of the measuring system and, not least for the purpose of generating the aforementioned resonant vibrations (useful mode vibrations), is allowed to vibrate at least temporarily over a predefinite free oscillation length. The measuring tube 11 can – as is common with such vibration elements used in industrial measuring systems – be, for example, a metal tube made of stainless steel or also of a titanium, tantalum, and / or zirconium alloy and have a diameter of more than 20 mm (DN11 ≥ 20 mm). This measuring tube 11, as can be seen from the overall view of the Fig. 2a , 2b and 3It is readily apparent, not least for the purpose of providing the aforementioned at least one flow path, with a first pipe end in the flow opening O i,11 of the first type of the first housing end and with a second pipe end in the flow opening O i,21 of the first type of the first housing end. As actively excited resonant vibrations, for example, vibrations of a natural mode of the vibration element V1 excited at its instantaneous resonant frequency can serve as active excitation vibrations – as is quite common when using such vibration elements – in which the at least one measuring tube 11 performs at least partial bending vibrations about an imaginary axis of vibration connecting its two pipe ends, for example, such that these bending vibrations exhibit only a single antinode over the entire free oscillation length.In the case of a straight measuring tube, bending vibrations can also be superimposed with torsional vibrations around the axis of vibration, for example, vibrations of the same frequency as the bending vibrations and / or vibrations of another mode of the vibrating element, in which the torsional vibrations also exhibit only a single antinode over the entire free length of vibration.

[0024] According to one embodiment of the invention, the vibration element V1, as also in the Fig. 2a , 2b , 3 schematically represented, not by means of just one, but by means of at least two identical measuring tubes arranged parallel to each other, thus by means of a first measuring tube 11 and at least one further - second - measuring tube 12. This is particularly evident in that the vibration element V1, as can also be seen from the overall view of the Fig. 2a , 2b bis 3 It is evident that the vibration element is formed by means of at least two straight, parallel measuring tubes, which are mechanically coupled to each other only at specific points, forming free oscillation lengths of as much equal length as possible, for example by means of gusset plates N1, N2 fixed at the end regions of the measuring tubes, i.e., near one of the housing ends H1, H2. The vibration element V1 can also be designed such that it corresponds, for example, to one of the vibration elements shown in the aforementioned US-A 2006 / 0162468, US-A 2007 / 0151368, US-A 2008 / 0047361, US-A 2011 / 0154914, US-A 2011 / 0016991, or US-A 2012 / 0048034.

[0025] According to a further embodiment of the invention, measuring tubes 11, 12 are connected in parallel in terms of flow characteristics. For this purpose, each of the two housing ends H1, H2, as shown in the Fig. 2a or 2b schematically represented, each has at least one further - second - flow opening O i,12 or O i,22 of the first kind, of which - in order to form a further flow path parallel to the previously mentioned flow path - the flow opening O i,12 receives a first pipe end of the measuring tube 12 and the flow opening O i,22 of the housing end H2 receives a second pipe end of the measuring tube 12.

[0026] As can be seen from a synthesis of the Fig. 6 , 7a , 7b - especially in comparison with Fig. 1 , 2a , 2b- as can be seen, the first vibration element V1 can also be formed, for example, by means of four identical straight measuring tubes 11, 12, 13 and 14 that run parallel to each other, for example, corresponding to one of the vibration elements shown in the aforementioned US-A 2010 / 0050783, US-A 2010 / 0242623 or US-A 2012 / 0079891. This is achieved in particular by the fact that, in order to form four parallel flow paths, the housing end H1 has four flow openings O i,11 , O i,12 , O i,13 , O i,14 of the first kind, each of which receives exactly one first pipe end of one of the four measuring tubes 11, 12, 13 or 14, and the housing end H2 also has four flow openings O i,21 , O i,22 , O i,23 , O i,24 of the first kind, each of which receives exactly one second pipe end of the measuring tube 11, 12, 13 or 14 opening into the respective corresponding flow opening of the first kind of the housing end H1.This design variant of the vibration element V1, as also shown in US-A 2010 / 0050783, US-A 2010 / 0242623 or US-A 2012 / 0079891, is particularly suitable for measuring systems that have a nominal diameter of more than 100 mm, for example 250 mm, 350 mm, 450 mm or above, and / or are intended for applications in which the medium can flow at a mass flow rate of more than 100 t / h, in particular more than 1000 t / h.

[0027] As already mentioned, the measuring system according to the invention serves in particular to determine a volumetric flow rate and / or a volumetric flow rate of the medium flowing in the pipeline during operation. Although the volumetric flow rate, i.e., the volumetric flow rate as the integral value of the volumetric flow rate repeatedly determined in the aforementioned measuring interval, can in principle – and as is quite common with conventional measuring systems with vibration elements of the aforementioned type – also be determined solely on the basis of the vibration signals s1 and s2 supplied by the two vibration sensors S1 and S2, namely on the basis of the phase difference Δφ 12 existing between the vibration signals S1 and S2 and on the signal frequency corresponding to the resonance frequency f r1 of the vibration element V1 of at least one of the vibration signals s1 and S2.The measuring system according to the invention further comprises a second vibration element V2, which is held on the housing H and / or clamped in a frame rigid in bending and torsion to allow vibration, at least one second vibration exciter E2, which is in operative connection with the vibration element V2 and is electrically connected to the measuring and operating electronics ME, in particular an electrodynamic one, for exciting vibrations of the second vibration element V2, and at least one third vibration sensor S3, which is also electrically connected to the measuring and operating electronics, in particular an electrodynamic one, for detecting vibrations of the vibration element V2.The vibration element V2 of the measuring system according to the invention is further configured to be contacted, at least temporarily, by a portion of the medium and, during this time, to be vibrated by the vibration exciter E2, such that the vibration element V2 also performs, at least partially, resonant vibrations, namely mechanical vibrations with a second resonant frequency fr2, which is also determined by the density of the contacting medium. The vibration sensor S3, in turn, generates a third vibration signal s3, dependent on the vibrations of the vibration element V2, which has a signal frequency corresponding to the same resonant frequency fr2. The vibration signals supplied to the measuring and operating electronics are processed there in the usual manner, namely pre-amplified, filtered, and digitized, and subsequently further evaluated by computer using appropriately programmed algorithms.

[0028] By supplying the measuring and operating electronics with both the vibration signals s1, s2 representing the two vibrations of the first vibration element V1 and the vibration signal s3 representing at least one vibration of the second vibration element V2, information is initially available to it regarding both the mass flow rate m 1, namely in the form of the phase difference Δφ r1 existing between the vibration signals s1, s2, and regarding the instantaneous density ρ of the medium, namely in the form of the signal frequency of the vibration signal s3.The measuring and operating electronics of the measuring system according to the invention are further equipped to generate, or output as a valid measured value X (X v → X; XV → X), a measured value X v representing the volume flow rate and / or a measured value X v representing the volume flow rate, in particular also recurringly, by means of the first, second and third vibration signal s1, s2, s3, namely based on the phase difference Δφ 12 existing between the vibration signals s1, s2 and based on the signal frequency of the vibration signal s3 corresponding to the resonance frequency f r2 of the vibration element V2, or to use the first, second and third vibration signal s1, s2, s3, namely based on the phase difference Δφ 12 existing between the vibration signals s1, s2 and based on the signal frequency of the vibration signal s3 corresponding to the resonance frequency f r2 of the vibration element V2.In particular, the second vibration element V2 is excited with resonant vibrations whose resonant frequency correlates very well with the density of the medium to be determined and which also exhibit the highest possible sensitivity to any changes in density. Thus, in the measuring system according to the invention, such resonant vibrations of the vibration element V2 serve as the useful mode vibrations, enabling high resolution of even slight density fluctuations. Accordingly, in a further embodiment of the invention, the measuring and operating electronics are also configured to generate, at least temporarily, a second driver signal e2 for the second vibration exciter E2, which has a signal frequency corresponding to the (instantaneous) resonant frequency fr2 of the second vibration element V2. This signal frequency is also determined – analogously to the driver signal e1 – based on the sensor signal s3, in particular...The signal frequency is also repeatedly adjusted by the measurement and operating electronics to the instantaneous resonant frequency fr2 of the vibration element V2. For the purpose of generating the driver signal e2, the aforementioned driver circuit of the measurement and operating electronics can, for example, have, in addition to the aforementioned output channel for the driver signal e1, another, separate output channel for driver signal e2 – formed, for example, by means of a corresponding phase control loop for determining the instantaneous resonant frequency fr2 or for setting the corresponding signal frequency for the driver signal e2 and a current controller for setting a current level of the driver signal e2.

[0029] According to a further embodiment of the invention, the measuring and operating electronics are also configured to generate both driver signals e1, e2 at least temporarily simultaneously, such that the first driver signal e1 has the signal frequency corresponding to the resonance frequency f r1 of the first vibration element V1 and the second driver signal e2 has the signal frequency corresponding to the resonance frequency f r2 of the second vibration element V2, so that as a result both vibration elements V1, V2 vibrate simultaneously with their respective instantaneous resonance frequencies f r1 and f r2.Furthermore, the measuring and operating electronics can also be designed in such a way – for example, in the case that the density of the medium changes only very slowly and / or only to a very small extent, and / or in the case that the density can also be measured with sufficient accuracy temporarily on the basis of the first and / or second vibration signal s1, s2 – that it continuously generates the driver signal e1 for the first vibration exciter E1 over a certain period of time, thus allowing the vibration element V1 to vibrate continuously over the same period, and during this period only occasionally supplies the driver signal e2 for the second vibration exciter E2, thus allowing the vibration element V2 to vibrate only temporarily or to be at rest temporarily during the same period.

[0030] According to a further embodiment of the invention, the measuring and operating electronics are further configured to generate, or output as a valid measured value X (X ρ → X), a measured value representing the density ρ of the medium flowing in the pipeline, based on the signal frequency of the vibration signal s3 corresponding to the resonance frequency f r2 of the vibration element V2, in particular also recurringly, and / or to generate, or output as a valid measured value X (X ρ → X), a mass flow rate m 1 of the medium flowing through the vibration element V1 and / or a measured value X m representing a mass flow rate of the medium flowing in the pipeline, based on the phase difference Δφ 12 existing between the vibration signals s1, s2, and / or to output as a valid measured value X (X m → X) of the measuring system.The density-representing measurement X ρ can be determined using a frequency measurement X fr2 that currently represents the resonance frequency f r2 of the vibration element V2 and based on the calculation rule for determining density measurements that is known in and of itself: . X ρ = a 20 + a 21 ⋅ 1 X fr 2 2 The measurement and operating electronics determine the values ​​of the mass flow rates (a20, a21) repeatedly, where a20 and a21 are measurement system-specific coefficients determined by the specific mechanical structure of the vibration element V2. These coefficients a20 and a21 can be determined in a known manner by means of a prior (wet) calibration of the measurement system, such that the result mediates between the specified actual mass flow rates and the measured values ​​Xρ determined by the measurement and operating electronics with the smallest possible deviation. The frequency measurement Xfr2, in turn, can be determined, for example, from the signal frequency of the sensor signal s3 corresponding to the resonance frequency fr2, and thus derived directly from the sensor signal s3 or a corresponding digital signal. Alternatively or additionally, the frequency measurement Xfr2 can also be derived, for example, from the driver signal e2.by means of the driver circuit generating the driver signal e2, e.g. also based on corresponding output values ​​of the phase control loop used to set the signal frequency of the driver signal e2.

[0031] Analogous to the density-representing measured value X ρ, the mass flow rate-representing measured value X m can also be determined based on a frequency measured value X fr1, which is derived by means of the measuring and operating electronics equally from the vibration signal s1 and / or the vibration signal s2 and which momentarily represents the resonance frequency f r1 of the vibration element V1, a first phase measured value X Δφ12, which momentarily represents the phase difference Δφ 12 and is thus determined repeatedly, and based on the usual calculation procedure for determining mass flow values: X m = b 10 + b 11 ⋅ X Δ φ 12 X fr 1 The coefficients b10 and b11 contained in the aforementioned calculation method (2) are again measurement system-specific, namely determined by the specific mechanical design of the vibration element V1, and can also be determined by means of a prior (wet) calibration of the measurement system. The frequency measurement Xfr1 can in turn be determined from the sensor signal s1 or a corresponding digital signal and / or from the driver signal e1. The frequency measurement Xfr1 can also be generated, for example, by means of the phase-controlled loop used to set the signal frequency of the driver signal e1. Alternatively or additionally, the measurement and operating electronics can, as is quite common in measurement systems formed by means of vibration elements of the type in question, if necessary,It should also be designed and used to determine a viscosity measurement X η representing a viscosity η of the fluid, based on the electrical excitation power supplied to excite and maintain vibrations of at least one of the vibration elements, for example the resonance vibrations of at least one of the two vibration elements, possibly also taking into account at least one of the vibration signals.

[0032] Furthermore, the measuring and operating electronics can also be designed in such a way that they calculate the measured value Xv representing the volumetric flow rate or the measured value XV representing the volumetric flow rate based on the relationship Xm / Xρ or based on the calculation rule: X m X ρ = b 10 + b 11 ⋅ X Δ φ 12 X fr 1 a 20 + a 21 ⋅ 1 X fr 2 2 determined.

[0033] The program codes for evaluation programs used to generate measured values ​​or for control programs used to operate the vibration elements can, for example, be persistently stored in a non-volatile EEPROM of the measurement and operating electronics, as is common knowledge to those skilled in the art, and loaded into a volatile RAM, integrated, for example, in a microprocessor or a digital signal processor (DSP), when the measurement and operating electronics are started up. Likewise, measured values ​​generated during operation by the measurement and operating electronics can be loaded into such a volatile or non-volatile data memory, possibly even the same one, and stored accordingly for later processing.

[0034] Not least for the purpose of achieving a far-reaching, ideally complete, vibration-related decoupling of the two vibration elements V1, V2 from each other, such that both vibration elements, not least also in their respective operating modes, can be vibrated independently of each other, possibly even individually or intermittently, without transferring vibrational energy to the respective other vibration element, the vibration element V2, according to a further embodiment of the invention, has a resonance frequency f r2 which – especially for the regularly occurring case that both vibration elements V1, V2 are simultaneously contacted by the same medium, but also each have a steady-state temperature distribution – deviates by more than 10 Hz from the resonance frequency f r1 of the vibration element V1.Advantageously, the two vibration elements V1, V2 are tuned to each other in such a way that the resonance frequency f r2 is smaller than the resonance frequency f r1; in particular, this is also achieved in such a way that the resonance frequency f r2 of the vibration element V2 corresponds to less than 90% of the resonance frequency f r1 of the vibration element V1.To mechanically decouple the two vibration elements V1 and V2 in the aforementioned manner, they are further dimensioned such that – at least with a steady-state temperature distribution in the measuring system – the lowest mechanical natural frequency of the vibration element V1, corresponding to the lowest resonance frequency of the vibration element V1 not in contact with the medium, differs from the lowest mechanical natural frequency of the second vibration element V2, i.e., the lowest resonance frequency of the vibration element V2 not in contact with the medium; for example, such that the lowest mechanical natural frequency of the vibration element V1 is lower than the lowest mechanical natural frequency of the vibration element V2.In a corresponding manner, the measuring and operating electronics according to a further embodiment of the invention are also configured to generate both driver signals e1, e2 simultaneously, such that the signal frequency of the second driver signal e2 is smaller than the signal frequency of the first driver signal e1, for example, less than 90% of the signal frequency of the driver signal e1, and / or that the same signal frequency of the second driver signal e2 deviates from the signal frequency of the first driver signal e1 by more than 10 Hz.

[0035] As in the Fig. 3 , 4 , and 5As indicated, the second vibration element V2 also has a lumen for guiding a flowing medium, and the vibration element V2 can again be connected to the pipeline in such a way that its lumen communicates at least temporarily with a lumen of the pipeline. Accordingly, the second vibration element V2 can also be formed by means of at least one measuring tube 21 mounted on the housing H in a way that allows it to vibrate. During operation of the measuring system, this measuring tube communicates at least temporarily with the pipeline and is allowed to vibrate at least temporarily over a structurally predetermined free oscillation length to generate the aforementioned resonant vibrations, for example, simultaneously with the vibration element V1. According to a further embodiment of the invention, the measuring tube 11 is further provided to have a free oscillation length that is greater than the free oscillation length of the measuring tube 21.

[0036] The measuring tube 21, which forms the vibration element V2, can, for example, be curved and also have a tube shape commonly used for such measuring tubes, such as a circular arc, trapezoidal, V-shaped, U-shaped, S-shaped, Z-shaped, or helical silhouette. Furthermore, the measuring tube 21 can, for example, be made of the same material as the measuring tube 11, which forms the vibration element V1, or of a different material commonly used for such vibration elements, such as a metal tube made of stainless steel or a titanium, tantalum, and / or zirconium alloy.Accordingly, as with vibration element V1, actively excited resonant vibrations can also be vibrations of a natural mode of vibration element V2, in which at least one measuring tube 21 performs bending vibrations at least partially around an imaginary axis of vibration connecting its two tube ends. In particular, the measuring and operating electronics are configured to excite the driver signal e2 with one of the instantaneous resonant frequencies of the fundamental mode of bending vibration of vibration element V2, i.e., the mode in which the measuring tube 21 forming vibration element V2 performs such bending vibrations that exhibit only a single antinode over the entire free oscillation length.

[0037] According to a further embodiment of the invention, the vibration element V2, as also in the Fig. 2a , 2b , 3schematically represented, formed not by means of just one, but by means of at least two identical measuring tubes 21, 22, arranged parallel to each other at least sectionally, for example also connected in parallel to each other in terms of flow technology by means of a flow divider. This is also particularly the case that the vibration element V2, as also in Fig. 2a or as indicated in 2b, is formed by means of at least two curved measuring tubes 21, 22, which are mechanically coupled to each other only at specific points, forming free oscillation lengths of as much equal length as possible, for example, again by means of gusset plates fixed to the end regions of the measuring tubes. The second vibration element V2 can therefore also be designed such that it corresponds, for example, to one of the vibration elements shown in the aforementioned CN-A 10 18 58 765, US-A 57 96 011, US-B 67 11 958 or WO-A 00 / 57141. As a second vibration element V2, vibration elements manufactured in microsystems technology (MEMS) can also be used, not least in the case that the measuring system is intended for applications with gaseous or low-viscosity media of less than 60 mPa·s, but also, for example, vibration elements manufactured in microsystems technology, such as those described in US-A 2010 / 0043569, US-B 79 21 737, US-B 78 23 445, US-B 74 37 912, US-B 64 77 901, etc.As shown in WO-A 2007 / 147786, the vibrating element V2 can also be formed by means of a measuring tube with a caliber of less than 0.5 mm. At the same time, the vibrating element V1 can, for example, be formed by means of two or more measuring tubes, each of which has a caliber of more than 40 mm.

[0038] As can be seen from a synthesis of the Fig. 1 , 2a , 2b , 3 , 4 , 5 , 6 , 7a , 7bIt is readily apparent that both the first and the second vibration element V1, V2 can advantageously be housed within one and the same lumen of the casing H, namely within lumen H'. Furthermore, the two vibration elements V1, V2 are preferably dimensioned with respect to their installation dimensions such that the vibration element V2 is smaller than the vibration element V1 in all three spatial coordinates: x, y, z. The installation length (z-direction) of the vibration element V2 depends on the selected oscillation length when formed by means of at least one measuring tube.This is particularly true in that both vibration elements V1 and V2 can also be housed within a single housing, which has previously been used for conventional measuring systems, such as Coriolis mass flow meters, with only one vibration element corresponding to vibration element V1. According to a further embodiment of the invention, the at least one measuring tube 11, or each of the measuring tubes by which the vibration element V1 is formed, has a diameter (DN11) that is larger than the diameter (DN21) of the at least one measuring tube 21, or each of the measuring tubes by which the vibration element V2 is formed. This is particularly such that the same caliber of the measuring tube 11 is more than 5 times the caliber of the measuring tube 21 (DN11 > 5 DN21), in particular also more than 10 times the caliber of the measuring tube 21 (DN11 > 10 · DN21).

[0039] The second vibration element V2 is located in the Fig. 1 bis 7b The illustrated embodiments are further configured to guide, at least temporarily, a portion of the medium flowing at a second mass flow rate m2 into its lumen and to vibrate it, in particular at the resonance frequency f r2. This is achieved, in particular, by ensuring that the two vibrating elements V1 and V2 are each simultaneously permeated by the medium, at least temporarily.Considering that, on the one hand, the vibration element V2 primarily serves to provide the vibration signal s3 with a signal frequency corresponding to the resonance frequency f r2 of the vibration element V2, and thus correlated with the density of the medium, and on the other hand, the density usually changes only slowly, not least in comparison to the mass flow rate m 1, it is readily possible in the measuring system according to the invention to design the two vibration elements V1, V2 such that the mass flow rate m 2, at which the portion of the medium flows in the lumens of the vibration element V2, is smaller than the mass flow rate m 1, at which the portion of the medium flows in the lumens of the vibration element V1; this is particularly possible in such a way that a maximum possible or permissible mass flow rate in the vibration element V1 is more than 10 times, and especially more than 100 times, a maximum possible or permissible mass flow rate of the vibration element V1.The permissible mass flow rate in the vibrating element V2 corresponds to this. Therefore, according to a further embodiment of the invention, the first and second vibrating elements V1, V2, or their respective lumens, are further dimensioned such that the vibrating element V1 has a flow cross-section that is larger than that of the vibrating element V2, or that the vibrating element V2 has a flow resistance that is greater than that of the vibrating element V1. In the aforementioned case where both vibrating elements V1, V2 are housed within a single casing, it can also be advantageous to design the vibrating element V2 such that its flow resistance is as large as possible.whose flow cross-section is as small as possible, namely, to design the vibration element V2 such that, given a specified minimum value for the mass flow rate m1 and a specified maximum value for the viscosity of the medium, the mass flow rate m2 just barely reaches a specified minimum value, for example, less than 10% of the specified maximum value for the mass flow rate m1. As a result, a vibration element V2 whose installation dimensions best fit into the remaining installation space in the housing next to the vibration element V1 can also be used.From a number of potentially possible designs for the vibration element V2, one can easily be found which best utilizes the available installation space in the housing in order to achieve the best possible correlation between the density to be measured and the signal frequency of the vibration signal s3 representing it, and thus to achieve the highest possible accuracy in the density measurement.

[0040] According to a further embodiment of the invention, the vibration element V2, as shown in Fig. 3 or as schematically indicated in 4, furthermore designed to be inserted into the course of the pipeline and connected to it, namely to its pipeline segments L11, L12, in such a way that the lumen of the vibrating element V2 communicates with the respective lumen of each of the two pipeline segments L11, L12 and thus - parallel to the at least one flow path formed by means of the first vibrating element V1 - a flow path enabling fluid flow from pipeline segment L11, furthermore also through the vibrating element V2 up to pipeline segment L12, thus forming a bypass bridging the lumen of the vibrating element V1 or its lumen in terms of flow technology by means of the vibrating element V2 or its lumen.

[0041] Particularly in the aforementioned case, where the vibration element V2 is fluidically connected in parallel to the vibration element V1, it can also be advantageous to determine the mass flow rate m2 during operation of the measuring system. This is particularly relevant if the mass flow rate m2 assumes values ​​that, on average, exceed 0.5% of the mass flow rate m1 over a longer period of more than 10 s (seconds), and / or if neglecting the mass flow rate m2 when calculating the volumetric flow rate or volumetric flow rate solely based on the mass flow rate m1 would result in an unacceptable measurement error when determining the measured values ​​Xv or XV. Therefore, according to a further embodiment of the invention, the measuring system also includes at least one fourth vibration sensor S4, spaced apart from the third vibration sensor S3, for detecting vibrations of the second vibration element.The vibration sensor S4 is configured to generate a fourth vibration signal s4, which is dependent on the vibrations of the second vibration element V2, such that this vibration signal s4 has a signal frequency equal to the signal frequency of the vibration signal s3, and thus also corresponding to the second resonance frequency f r2, and a phase difference Δφ r34 relative to the third vibration signal s3 that depends on the mass flow rate m 2. Furthermore, the measurement and operating electronics are also configured to generate measured values ​​X v or X V using the vibration signal s4, namely based on the phase difference Δφ 34, or based on a recurring second phase measurement X Δφ34, which represents the phase difference Δφ 34 at the moment and is thus recurringly determined. This is done, for example, by applying the aforementioned calculation rule (3) for calculating the measured value X v or X V.The measured value XV is modified as follows: . X m X ρ = b 10 + b 11 ⋅ X Δ φ 12 X fr 1 + b 20 + b 21 ⋅ X Δ φ 34 X fr 2 a 20 + a 21 ⋅ 1 X fr 2 2

[0042] The coefficients b20 and b21 contained therein are, in turn, measurement system-specific, namely determined by the specific mechanical design of the vibration element V2, and can also be determined by means of a corresponding (wet) calibration of the measurement system, for example, simultaneously with the calibration already carried out to determine the other coefficients a20 and a21, or b10 and b11. Accordingly, the mass flow rate Xm for the total mass flow rate prevailing in the measurement system, or a corresponding total mass flow rate for the aforementioned measurement interval, can then be calculated even more precisely based on the following calculation procedure, taking into account the aforementioned formula (4): X m = b 10 + b 11 ⋅ X Δ φ 12 X fr 1 + b 20 + b 21 ⋅ X Δ φ 34 X fr 2

[0043] Alternatively or additionally, the two mass flow rates m1 and m2 can also be calculated individually, e.g. in the following way: X m 1 = b 10 + b 11 ⋅ X Δ φ 12 X fr 1 , X m 2 = b 20 + b 21 ⋅ X Δ φ 34 X fr 2 The values ​​are determined and output using corresponding measured values ​​X m1 or X m2, for example also displayed on site.

[0044] As an alternative to the variant described above, in which the vibration element V2 is fluidically connected in a bypass to the vibration element V1, the vibration element V2 can be, as in Fig. 5 The vibration element V2 is schematically indicated, but it is also connected to the pipeline in such a way that the mass flow rate of the flowing medium from pipeline segment L11 to pipeline segment L12 is essentially unchanged by the flow path formed by the vibration element V2. Thus, at least under steady-state flow, the initial mass flow rate m1 is essentially equal to the instantaneous mass flow rate of the medium in both pipeline segment L11 and L12, and the phase difference Δφ12 essentially corresponds to the same mass flow rate of the medium in pipeline segments L11 and L12. According to a further embodiment of the invention, the housing end H1 has at least one flow opening Oii,1 of the second type – namely, a flow opening communicating with the vibration element V2 – for connecting the vibration element V2 to the pipeline, and not least for providing the aforementioned flow path.This can be, for example, in the middle of the housing end H1 or as shown in . Fig. 2a The measuring system is shown to be arranged off-center in the housing end H1, in particular at a distance from the center of the housing end H1 corresponding to approximately 0.2 to 0.3 times the nominal diameter of the measuring system. Furthermore, the housing end H2, as shown in the overview of the Fig. 2a , 2b , 3 , 4 , 7a or 7b, it is readily apparent that at least one flow opening O ii,1 of the second kind – namely a flow opening communicating with the vibration element V2 – has, or that one of the two housing ends has, in the Fig. 5 In the illustrated embodiment, the housing end H1 comprises two separately spaced flow openings O ii,1 , O ii,2 of the second type. Furthermore, the at least one measuring tube 21, by means of which the vibration element V2 is formed, accordingly has a first tube end communicating with the flow opening O ii,1 , of the second type, and a second tube end communicating with the flow opening O ii,2 of the second type.

[0045] Not least to avoid interference potentially affecting its vibrations or its sensor signal S3, and / or to make the best possible use of the available installation space, it may be advantageous not to connect the vibration element V2 directly to both flow openings O ii,1 , O ii,2 of the second type, but rather, as shown in the Fig. 3 , 4or as shown schematically in Figure 5, by means of at least one, for example flexible and / or bent, flow-optimized connecting line. According to a further embodiment of the invention, the vibration element V2 is therefore also connected to the first flow opening O ii,1 of the second type by means of at least one, for example flexible and / or bent, first connecting line L21. In addition, the vibration element V2 can also be connected to the second flow opening O ii,2 of the second type by means of a second connecting line L22, for example flexible and / or bent, for example also such that the vibration element V2, connected to the pipeline via connecting lines L21, L22, is placed inside the housing H at a distance from both housing ends H1, H2.

[0046] According to a further embodiment of the invention, the measuring system further comprises a first temperature sensor T1 electrically connected to the measuring and operating electronics ME for detecting a temperature ϑ1 of the vibration element V1, which serves to generate, together with the measuring and operating electronics, a first temperature signal θ1 dependent on the same temperature ϑ1 of the vibration element V1, as well as a second temperature sensor T2 also electrically connected to the measuring and operating electronics for detecting a temperature ϑ2 of the vibration element V2, which is configured to generate, together with the measuring and operating electronics, a second temperature signal θ2 dependent on the same temperature ϑ2 of the vibration element V2, which two temperature signals θ1, θ2 are then further processed and evaluated by means of the measuring and operating electronics.The temperature sensor T1 can, for example – as is quite common with vibrating elements of the type in question – be arranged in the measuring system in contact with the vibrating element V1, for instance on a side or surface of the vibrating element V1 facing away from the lumen of the vibrating element V1, and thus not in contact with the medium. Similarly, the second temperature sensor T2 can also be arranged in the measuring system in contact with the vibrating element V2, for example also on a surface of the vibrating element V2 not in contact with the medium. The temperature sensor T1 and T2 can each be, for example, a sensor mounted on the respective vibrating element, if necessary.A platinum resistance element, also mounted on a suitable substrate, serves as a resistance thermometer, forming a Pt100 or Pt1000 resistance thermometer, and is electrically connected to the measuring and operating electronics, for example, by means of another pair of connecting wires (not shown here for clarity). The measuring and operating electronics are further configured to process and evaluate the temperature signals θ1 and θ2 in such a way that measured values ​​representing the volumetric flow rate v and the volumetric flow rate v are generated using the first temperature signal θ1 and / or the second temperature signal θ2, thus generating the temperature ϑ1 of the vibrating element V1 as measured by the temperature sensor T1.The temperature ϑ2 of the vibrating element V2, as measured by the temperature sensor T2, can be individually considered when determining the volumetric flow rate v or the volumetric flow rate v. For example, the accuracy with which the measured value X ρ, representing the density ρ of the medium guided in the vibrating element V2, corresponds to the same density ρ can be further improved very easily by modifying, for example, the above-mentioned calculation rule (1) for determining the measured value X ρ, taking into account a temperature measured value X ϑ2 obtained from the temperature signal θ 2 by means of the measuring and operating electronics, which currently represents the temperature ϑ 2, as well as a further measurement system-specific coefficient a 23, determined, for example, during the aforementioned (wet) calibration of the measuring system, as follows: . X ρ = a 20 + a 21 ⋅ 1 X fr 2 2 + a 23 ⋅ X ϑ 2 X fr 2 2 This at least partially compensates for the influence of the temperature ϑ2 on the resonance frequency f r2 of the vibration element V2. Similarly, based on the temperature signal θ 1, the accuracy with which the mass flow-representative measured values ​​X m are determined can also be further improved, thus at least partially compensating for the influence of the temperature ϑ1 on the phase difference Δφ 12, by also modifying the aforementioned calculation method (2) for determining the measured value X m by adding a temperature measured value X ϑ1, obtained from the temperature signal θ 1 by means of the measuring and operating electronics and representing the temperature ϑ1 at the moment, as well as a further measurement system-specific coefficient b 13, determined, for example, also during the aforementioned (wet) calibration of the measuring system, accordingly: X m = b 10 + b 11 1 + b 13 ⋅ X ϑ 1 ⋅ X Δ φ 12 X fr 1 is modified, or, taking into account both temperature signals θ 1 , θ 2 , the influence of the temperature ϑ1 on the phase difference Δφ 12 or the influence of the temperature ϑ2 on the phase difference Δφ 34 can be at least partially compensated by modifying the calculation rule (5) - taking into account two measurement system-specific coefficients b 13 , b 23 - as follows: X m = b 10 + b 11 1 + b 13 ⋅ X ϑ 1 ⋅ X Δ φ 12 X fr 1 + b 20 + b 21 1 + b 23 ⋅ X ϑ 2 ⋅ X Δ φ 34 X fr 2 is modified.

[0047] Based on the aforementioned calculation method (7) for the improved, namely temperature-compensated, calculation of the density measurement X ρ, as well as the calculation method (8) and (9), the influences of the temperatures ϑ 1 , ϑ 2 on the accuracy of the measurement of the volumetric flow rate or the volumetric flow rate when determining the measured values ​​X v or the measured values ​​XV can accordingly be taken into account or compensated, for example by one of the following modifications to the above-mentioned calculation method (3): X m X p = b 10 + b 11 1 + b 13 ⋅ X ϑ 1 ⋅ X Δ φ 12 X fr 1 a 20 + a 21 ⋅ 1 X fr 2 2 + a 23 ⋅ X ϑ 2 X fr 2 2 bzw . X m X p = b 10 + b 11 1 + b 13 ⋅ X ϑ 1 ⋅ X Δ φ 12 X fr 1 + b 20 + b 21 1 + b 23 ⋅ X ϑ 2 ⋅ X Δ φ 34 X fr 2 a 20 + a 21 ⋅ 1 X fr 2 2 + a 23 ⋅ X ϑ 2 X fr 2 2 , so that, as a result, the volumetric flow rates and volumetric flow rate measurements subsequently show no or only negligible dependencies on the temperatures ϑ1, ϑ2. Furthermore, based on the two temperature signals θ1, θ2 and the temperature measurements Xϑ1, Xϑ2 derived from them, even with differing temperatures ϑ1, ϑ2 – for example, due to an abruptly changing or widely fluctuating temperature of the medium flowing into the measuring system via line segment L11 and a concomitant unsteady temperature distribution within the measuring system –The resulting temperature gradient between the two vibration elements V1, V2 – the resonance frequency of the vibration element V2, measured using the vibration signal s3 and dependent on the instantaneous density of the medium currently contacting the vibration element V2 as well as on an instantaneous temperature ϑ2 of the vibration element V2 – can be converted into an assumed resonance frequency f r2 ' of the vibration element V2 corresponding to an instantaneous temperature ϑ1 of the vibration element V1. Alternatively, a provisional density measurement X ρ ', initially determined based on the vibration signal s3 and the temperature signal θ2 for the medium currently contacting the vibration element V2, can be converted into the density measurement X ρ for the instantaneous density of the medium currently guided in the vibration element V1, corresponding to the instantaneous temperature ϑ1 of the vibration element V1.

[0048] According to a further embodiment of the invention, the measuring system further comprises at least one deformation sensor D1 electrically connected to the measuring and operating electronics for detecting an elastic deformation of the first vibration element V1 – for example, caused by thermal factors and / or by a force applied to the measuring system via a pipeline. The deformation sensor D1 is specifically designed to generate, together with the measuring and operating electronics, a deformation signal d1 that depends on the aforementioned deformation of the vibration element V1 and to make this signal available to the measuring and operating electronics.The deformation sensor D1 can, for example, be formed by means of a strain gauge (SG) glued to the vibrating element V1, specifically on a side facing away from its lumen, and electrically connected to the measuring and operating electronics, for example by means of another pair of connecting wires – not shown here for the sake of clarity. The deformation signal d1 generated by the deformation sensor D1 can be used by the measuring and operating electronics, for example, to correct the effects of the aforementioned elastic deformations of the vibrating element V1 on its vibration characteristics or the associated distortions, such as of the phase difference Δφ 12.Therefore, according to a further embodiment of the invention, the measuring and operating electronics are configured to generate the measured value Xv representing the volumetric flow rate and / or the measured value XV representing the volumetric flow rate by means of the deformation signal, or to output them as valid measured values ​​X (XV → X, Xv → X) of the measuring system. Alternatively or additionally, the deformation signal d1 can also serve to detect, by means of the measuring and operating electronics, whether the vibrating element V1 currently exhibits no elastic deformation of the aforementioned type, so that its instantaneous resonance frequency fr1 is also well suited as an accurate measure of the density of the medium. Consequently, the measured values ​​Xv representing the volumetric flow rate and / or XV representing the volumetric flow rate can also be determined instantaneously based on the signal frequency of the first and / or second vibration signal, and if necessary,are valid measured values ​​X of the measuring system, or whether the vibration element V1 is deformed to such a high degree that its resonance frequency f r1 cannot currently be a sufficiently accurate measure of the instantaneous density of the medium, and thus the measured values ​​X v representing the volume flow rate or the measured values ​​XV representing the volume flow rate can reasonably be determined based on the signal frequency of the third vibration signal s3.

[0049] The measuring system according to the invention can furthermore also have at least two different operating modes for determining the volumetric flow rate or the volumetric flow rate of the medium flowing in the pipeline, which can be selectively activated, for example, by means of the aforementioned deformation signal d1. These modes are: a first operating mode in which the measuring and operating electronics determine the measured values ​​XV (XV → X) or Xv (Xv → X) serving as valid measured values ​​X of the measuring system based on both the phase difference Δφ 12 and the signal frequency of the third vibration signal s3 corresponding to the resonance frequency f r2 of the vibration element V2; and an alternative second operating mode in which the measuring and operating electronics determine the measured values ​​XV or Xv (Xv → X) serving as valid measured values ​​X of the measuring system.X v is determined based on both the phase difference Δφ 12 and the signal frequency of the first and / or second vibration signal corresponding to the resonance frequency f r1 of the vibration element V1, but not based on the resonance frequency f r2 of the vibration element V2 or the corresponding signal frequency of the vibration signal s3. Furthermore, the measurement and operating electronics can be configured such that it does not supply the driver signal e2, which serves to excite the vibration element V2, in the second operating mode of the measurement system, or only supplies it in the first operating mode, meaning that the vibration element V2 is not vibrated in the second operating mode, or only vibrates in the first operating mode. The activation of the first orThe second operating mode, in turn, can be based, for example, on the deformation signal d1, for instance by means of a recurring comparison in the measurement and operating electronics of an (instantaneous) amplitude of the deformation signal d1 with a measurement system-specific first deformation reference value, which serves as a switching threshold for deactivating the first and activating the second operating mode and represents a predetermined first degree of deformation of at least the vibration element V1, or by means of a recurring comparison in the measurement and operating electronics of the aforementioned amplitude of the deformation signal d1 with a measurement system-specific second deformation reference value, which serves as a switching threshold for deactivating the second and activating the first operating mode and represents a predetermined second degree of deformation of the vibration element V1, namely a smaller degree of deformation compared to the first degree of deformation.Alternatively or additionally, the activation of the first and / or second operating mode can each be carried out using the aforementioned first temperature signal θ1, for example in such a way that a comparison of an (instantaneous) amplitude of the temperature signal θ1 with a measurement system-specific first temperature reference value, which serves as a switching threshold for the deactivation of the first and the activation of the second operating mode, is repeatedly performed in the measuring and operating electronics, and which represents a first thermal voltage specified for the vibration element V1, orIn the measurement and operating electronics, a comparison of the aforementioned amplitude of the temperature signal θ1 with a measurement system-specific second temperature reference value is repeatedly performed. This second temperature reference value serves as a switching threshold for deactivating the second operating mode and activating the first operating mode. This second temperature reference value represents a predetermined second thermal voltage in the vibrating element V1, which is lower than the first thermal voltage. If the activation of the first operating mode is based on both the deformation signal d1 and the temperature signal θ1, the measurement and operating electronics are advantageously configured such that the first operating mode is also activated when the first deformation reference value is detected by the deformation signal d1, or even just the first temperature reference value by the temperature signal θ1.Conversely, if the activation of the second operating mode is based on both the deformation signal d1 and the temperature signal θ1, the measuring and operating electronics are advantageously configured such that this second operating mode is only activated when both the deformation signal d1 and the temperature signal θ1 detect that the second deformation reference value has been reached or fallen below. In addition to the selective activation / deactivation of the first operating mode based on the temperature signal θ1 described above, it is also possible, not least for achieving high measurement accuracy when determining the volumetric flow rate, to further optimize the operation.It can be advantageous to switch from the second to the first operating mode, and thus to activate the first operating mode, even when a phase difference-to-signal frequency ratio – namely a ratio of the currently measured phase difference Δφ 12 to the signal frequency corresponding to the current resonance frequency f r1 of at least one of the sensor signals s1, s2 – reaches or exceeds a predetermined reference value representing the measurement system-specific critical flow velocity.

[0050] In a further embodiment, the measuring system also has a third operating mode in which the measuring and operating electronics determine the measured values ​​XV (XV → X) and Xv (Xv → X), which serve as valid measured values ​​X of the measuring system, based on both the phase difference Δφ 12 and the signal frequency corresponding to the resonance frequency f r1 of the vibration element V1 of at least one of the vibration signals s1, s2, but in contrast to the second operating mode described above, the vibration element V2 is simultaneously contacted by the medium and is actively excited to resonance vibrations by means of the driver signal e2, which is also generated at least temporarily by the measuring and operating electronics in the third operating mode.The measurement and operating electronics are further configured to perform a (self-)verification of the measurement system based on both the signal frequency corresponding to the resonance frequency f r1 of at least one of the vibration signals s1, s2 received during the third operating mode and the signal frequency corresponding to the resonance frequency f r2 of at least one of the vibration signal s3 received during the third operating mode. This verification aims to determine whether the measurement system is still operating within its specified parameters and / or whether the measured values ​​X output by the measurement system can be considered valid. The verification of the measurement system can be carried out, for example, by repeatedly determining a relative or absolute deviation between the two resonance frequencies f r1, f r2 using the measurement and operating electronics, and then comparing this deviation with a predefined limit value that represents a maximum permissible deviation.The maximum expected deviation of both resonance frequencies fr1 and fr2 for an intact measuring system is represented. If this deviation reaches or exceeds the aforementioned limit, the measuring and operating electronics can, for example, generate an alarm signaling that irreversible damage has been detected to at least one of the two vibration elements V1 and V2, for instance, due to abrasion, corrosion, plastic deformation, or cracking.Alternatively or additionally, the measuring and operating electronics are further configured to perform the aforementioned check of the measuring system based on the driver signals e1, e2 generated during the third operating mode, for example, by determining an average electrical power for each of the two driver signals e1, e2 during the third operating mode, namely an average electrical power P exc1 of driver signal e1 and an average electrical power P exc2 of driver signal e2, and comparing any deviation – relative or absolute – of the two electrical powers P exc1, P exc2 from each other with a correspondingly predefined limit value. Here, too, the limit value can be set such that reaching or exceeding it indicates irreversible damage to at least one of the two vibration elements V1, V2, which may again trigger an alarm.Alternatively or in addition to the aforementioned verification of the measuring system using the vibration and / or driver signals generated in the third operating mode, the two mentioned temperature signals θ1, θ2 can also be used to verify the measuring system, for example, such that if both vibration elements V1, V2 are nominally in contact with the same medium or should be, and an unacceptably high and / or unacceptably long-lasting deviation of the two temperatures ϑ1, ϑ2 from each other is determined based on both temperature signals θ1, θ2, an alarm is generated by the measuring and operating electronics that signals the formation of a deposit on at least one of the two vibration elements V1, V2, and / or an alarm is generated that signals that at least one of the measuring tubes forming the vibration element V1 or the vibration element V2 is at least partially blocked.

[0051] To control the flow through the vibrating element V2 or the mass flow rate m2, possibly also for the purpose of temporarily preventing any flow through the vibrating element V2 and / or for the controlled conveyance of the partial volume flowing through the vibrating element V2, for example in the case of a highly viscous medium of more than 100 mPa·s (millipascal seconds) and / or an occasionally relatively low mass flow rate m1 of less than 50% of a measurement system-specific maximum value specified for the mass flow rate m1 and / or, for example, also to keep the flow cross-section of the vibrating element V2, and thus its installation dimensions, as small as possible, in particular.The measuring system, according to a further embodiment, also comprises a fluid control device FC, which is connected, for example, to one of the flow openings O ii,1 , O ii,2 of the second type and to the vibration element V2, and which is also so small that, as a result, both vibration elements V1, V2, fit into a housing that is otherwise also commonly used in conventional measuring systems with only a single vibration element, and / or to limit the mass flow rate m 2 to a predetermined maximum value, for example, also in the case of high mass flow rates m 1 of more than 80% of the predetermined measuring system-specific maximum value. The fluid control device FC can, for example, be operated by means of separate, possibly distributed within the housing and by means of corresponding fluidic or...The fluid control device can be formed from individual components connected by electrical connecting lines, or, for example, as a flow controller combining all individual components in one module. According to a further embodiment of the invention, the fluid control device is fluidically connected to one of the flow openings O ii,1, O ii,2 of the second type via one of the connecting lines L21, L22, and / or the fluid control device is fluidically connected to the vibration element V2 via one of the connecting lines L21, L22. The fluid control device FC, or the valves and / or pumps it contains, can also be electrically connected to the measuring and operating electronics, for example, by means of connecting wires, and can be directly controlled and supplied with electrical energy by the electronics during operation of the measuring system by means of corresponding electrical control signals fc1.Alternatively or additionally, the fluid control device FC itself can have its own internal control electronics, which include a separate power supply circuit powered by the measurement and operating electronics, and which is started, stopped, and / or parameterized by the measurement and operating electronics by means of corresponding control commands transmitted by a control signal fc1, for example, a binary one. According to a further embodiment of the invention, the fluid control device, or the measurement and operating electronics and the fluid control device FC together, are configured to allow the partial volume flowing through the vibrating element V2 to flow at a predefinable volumetric flow rate, or to regulate this volumetric flow rate to a predetermined constant value, for example, corresponding to an operating point particularly suitable for measuring the resonance frequency f r2 of the vibrating element V2.This allows, firstly, any inaccuracies in calculating the two mass flow rates m1 and m2 to be minimized. Secondly, it makes it very easy to set a mass flow rate m2 of the partial volume flowing through vibrating element V2, which is particularly suitable for determining highly accurate measured values ​​Xv and / or XV, i.e., for measuring the volumetric flow rate or volumetric flow rate, independently of other process parameters such as viscosity, temperature, pressure, and / or mass flow rate of the medium flowing in the pipeline. Alternatively or additionally, in the case described above, where the measuring system has at least two operating modes for determining the volumetric flow rate or volumetric flow rate, a different method can be used.of the volumetric flow rate of the medium flowing in the pipeline, the fluid control device FC is deactivated during the aforementioned second operating mode, such that any pump provided in the fluid control device is switched off and / or any valve provided in the fluid control device is closed, or that the fluid control device FC is only activated during the aforementioned first operating mode, such that any pump provided in the fluid control device is switched on and / or any valve provided in the fluid control device is at least partially open.

[0052] In the Fig. 9 A further embodiment of a measuring system not according to the invention is schematically illustrated. In the measuring system shown here, the second vibration element V2, unlike, for example, those described in the Fig. 3 , 4 or 5In each of the embodiments shown, the vibration element V2 is designed to be immersed in or subjected to a flow of medium and, during this time, actively excited by the vibration exciter E2, just as in the previously described embodiments with a flow-through vibration element V2. For this embodiment, the vibration element V2 can, for example, be a hollow body actively excited to vibrate in a bell mode by means of the vibration exciter, such as according to EP-A 564 682. Alternatively, the vibration element V2 can also be formed by means of at least one vibrating rod, for example paddle-shaped and / or hollow, which is actively excited to bending vibrations during operation.Accordingly, the vibration element V2 can, for example, also be formed by means of two mechanically coupled vibrating rods and be configured to be actively excited to resonant vibrations in the manner of a tuning fork by means of the vibration exciter E2 during operation. The vibration element V2 can therefore also correspond to such a vibration element, as shown, among others, in US-B 68,456,363. Furthermore, the vibration element V2 can also be, as in... Fig. 9 schematically depicted, it is provided by a vibronic (density) measuring device – which can otherwise also be operated independently. Accordingly, the vibration element V2 can, for example, also be a component of such a vibronic measuring device, such as the one manufactured by Endress+Hauser GmbH & Co. KG and offered under the name Liquiphant M FTL50 (http: / / www.us.endress.com / #product / FTL50), not least together with a density calculator FML621 (http: / / www.us.endress.com / #product / FML621). The vibration element V2 is used in the Fig. 9 In the embodiment shown, the vibration element V1 is mounted externally on the housing H, specifically outside its lumen that accommodates it, or arranged on the outer surface of the housing H, which is in contact with the medium during operation and here only has one or more flow openings of the first type. The vibration element V2 can be screwed into an installation opening near one of the flanges F1, F2 by means of a screw-in fitting with a corresponding external thread. This installation opening has an internal thread complementary to the external thread. One advantage of the embodiment shown is that Fig. 9The described design variant can be seen, among other things, in the fact that as an additional installation measure it only requires the installation opening with internal thread - which is not necessarily present in conventional Coriolis mass flow meters, but can nevertheless be produced without difficulty, not least also suitable for the aforementioned vibronic (density) measuring devices and / or subsequently, but otherwise flow openings of the second type can be dispensed with.

Claims

1. A measuring system for determining a volume flow, v, that is to say a total volume that has flowed during a measuring interval, and / or a volumetric flow rate, v̇, of a medium flowing in a pipeline, in particular a liquid or a gas, said measuring system comprising: - A housing (H) with a first housing end (H1) connected to a first line segment (L11) of the pipeline, in particular by means of a flange connection, and with a second housing end (H2) connected to a second line segment (L21) of the pipeline, in particular by means of a flange connection; - a first vibration element (V1) having a lumen, in particular formed by means of at least one measuring tube that is straight and / or can be inserted into the course of the pipeline, which is configured to conduct a flowing part of the medium with a first mass flow rate, m1, in said lumen and during this to be caused to vibrate, in particular at a resonant frequency; - at least one first vibration exciter (E1) for causing the first vibration element (V1) to vibrate in such a way that said vibration element (V1) performs resonant vibrations at least in part, that is to say mechanical vibrations with a first resonant frequency, fr1, in particular dependent on a density of the medium; - a first vibration sensor (S1) for detecting vibrations of the first vibration element (V1), in particular resonant vibrations initiated by the first vibration exciter, said first vibration sensor (S1) being configured to generate a first vibration signal (s1) dependent on vibrations of the first vibration element, which has a signal frequency corresponding to the first resonant frequency, fr1; - at least one second vibration sensor (S2) at a distance from the first vibration sensor (S1) for detecting vibrations of the first vibration element (V1), said second vibration sensor (S2) being configured to generate a second vibration signal (s2) dependent on vibrations of the first vibration element (V1) in such a way that said second vibration signal (s2) has a signal frequency which is the same as the signal frequency of the signal component of the first vibration signal (s1), therefore a signal frequency that corresponds to the first resonant frequency, fr1, as well as a phase difference, Δϕ12, which is dependent on the first mass flow rate, m1, relative to the first vibration signal (s1); - a second vibration element (V2) formed by means of at least one measuring tube, in particular one that is mounted such that it can vibrate, and / or by means of at least one vibrating rod, which is configured to be contacted at least occasionally by a part of the medium, in particular to have said medium flow through and / or around it, and during this to be caused to vibrate, in particular at a resonant frequency; - at least one second vibration exciter (E2) for initiating vibrations of the second vibration element (V2) in such a way that said vibration element (V2) performs resonant vibrations at least in part, said mechanical vibrations having a second resonant frequency, fr2, which differs from the first resonant frequency, fr1, by more than 10 Hz, in particular that is dependent on a density of the medium; - at least one third vibration sensor (S3) for detecting vibrations of the second vibration element (V2), said vibration sensor (S3) being configured to generate a third vibration signal (s3) dependent on vibrations of the second vibration element (V2), which has a signal frequency corresponding to the second resonant frequency, fr2; - and measuring and operating electronics (ME), in particular formed by two electronic modules communicating with each other; - wherein at least the first vibration element (V1) is housed inside a lumen (H') of the housing (H) and the second vibration element (V2) is mounted on the housing; -- wherein the measuring and operating electronics (ME) are configured --- to generate a first driver signal (e1) for the first vibration exciter (E1), which has a signal frequency corresponding to the first resonant frequency, fr1, --- and to generate a second driver signal (e2) for the second vibration exciter, in particular at least occasionally and / or at the same time as the first driver signal (e1), which has a signal frequency corresponding to the second resonant frequency, fr2, in such a way that said signal frequency of the second driver signal (e2) differs from the signal frequency of the first driver signal (e1) by more than 10 Hz; -- and wherein the measuring and operating electronics (ME) are configured --- to generate a measured value (XV) representing the volumetric flow rate using the first, second and third vibration signals (s1, s2, s3), that is to say based on the phase difference, Δϕ12, which exists between the first and second vibration signals, and based on the signal frequency of the third vibration signal (s3), and / or --- to generate a measured value (XV) representing the volume flow using the first, second and third vibration signals (s1, s2, s3), that is to say based on the phase difference, Δϕ12, which exists between the first and second vibration signals, and based on the signal frequency of the third vibration signal.

2. The measuring system as claimed in claim 1, wherein the second vibration element (V2) is configured to be immersed in the medium or to have the medium flow into it.

3. The measuring system as claimed in claim 1, wherein the second vibration element (V2) has a lumen for conducting the flowing medium and is configured to conduct in its lumen a part of the medium flowing at a second mass flow rate, m2, and during this to be caused to vibrate, in particular at the second resonant frequency, in particular in such a way the second mass flow rate,at which the part of the medium conducted in the lumen of the second vibration element (V2) is flowing is smaller than the first mass flow rate at which the part of the medium conducted in the lumen of the first vibration element (V1) is flowing.

4. The measuring system as claimed in the preceding claim, further comprising: At least one fourth vibration sensor (54) spaced apart from the third vibration sensor (S3) for detecting vibrations of the second vibration element (V2), said fourth vibration sensor (S4) being configure to generate a fourth vibration signal (s4) dependent on vibrations of the second vibration element (V2) in such a way that said fourth vibration signal (s4) has a signal frequency which is the same as the signal frequency of the third vibration signal (s3), therefore a signal frequency that corresponds to the second resonant frequency, fr2, as well as a phase difference, Δϕ34, which is dependent on the second mass flow rate, m2, relative to the third vibration signal (s3).

5. The measuring system as claimed in the preceding claim, - wherein the measuring and operating electronics (ME) are configured to generate the measured value (XV) representing the volumetric flow rate, also using the fourth vibration signal (s4), that is to say based on the phase difference, Δϕ34, which exists between the third and fourth vibration signals (s3, s4); and / or - wherein the measuring and operating electronics are configured to generate the measured value (XV) representing the volume flow, also using the fourth vibration signal, that is to say based on the phase difference, Δϕ34, which exists between the third and fourth vibration signals (s3, s4); and / or - wherein the measuring and operating electronics (ME) are configured to generate a measured value (Xm2) representing the second mass flow rate, m2, using the third and fourth vibration signals (s3, s4), that is to say based on the phase difference, Δϕ34, which exists between the third and fourth vibration signals.

6. The measuring system as claimed in one of claims 3 to 5, - wherein the first vibrating element (V1) has a flow cross-section which is larger than a flow cross-section of the second vibrating element (V2); and / or - wherein the second vibrating element (V2) has a flow resistance which is greater than a flow resistance of the first vibrating element (V1).

7. The measuring system as claimed in one of the preceding claims, wherein the measuring and operating electronics are configured to generate the first and second driver signals (e1, e2) simultaneously in such a way that the signal frequency of the second driver signal (e2) corresponding to the second resonant frequency, fr2, is lower than the signal frequency of the first driver signal (e1) corresponding to the first resonant frequency, fr1, in particular in such a way that said signal frequency of the second driver signal (e2) is less than 90% of the signal frequency of the first driver signal (e1).

8. The measuring system as claimed in one of the preceding claims, - wherein the measuring and operating electronics (ME) are configured to generate a measured value representing a density of the medium using the third vibration signal (s3), that is to say based on the signal frequency of the third vibration signal corresponding to the second resonant frequency, fr2; and / or - wherein the measuring and operating electronics (ME) are configured to generate a measured value (Xm; Xm1) representing the first mass flow rate, m1, using the first and second vibration signals (s1, s2), that is to say based on the phase difference that exists between the first vibration signal (s1) and the second vibration signal (s2); and / or - wherein the measuring and operating electronics (ME) are formed by two electronic modules (ME1, ME2) communicating with each other, each of which is housed in one of two or more separate electronics enclosures (HE, HE').

9. The measuring system as claimed in one of the preceding claims, further comprising: A first temperature sensor (T1), in particular one that contacts the first vibration element on a side facing away from its lumen, for detecting a temperature of the first vibration element (V1), which is configured to generate a first temperature signal dependent on said temperature of the first vibration element and a second temperature sensor (T2), in particular located on a side of the second vibration element that the medium cannot contact, for detecting a temperature of the second vibration element (V2), which is configured to generate a second temperature signal dependent on said temperature of the second vibration element; - wherein the measuring and operating electronics are configured to generate the measured value representing the volumetric flow rate using the first temperature signal and / or using the second temperature signal, and / or wherein the measuring and operating electronics are configured to generate the measured value representing the volume flow using the first temperature signal and / or using the second temperature signal.

10. The measuring system as claimed in the preceding claim, wherein the measuring and operating electronics are configured to perform a test of the measuring system using the first and second temperature signals (θ1, θ2).

11. The measuring system as claimed in one of the preceding claims, - wherein the second vibration element (V2) is formed by means of at least one measuring tube (21), in particular a measuring tube that is curved and / or connected in a bypass for the first vibration element (V1) in terms of flow and / or has a caliber of less than 50 mm), in particular in such a way that the at least one measuring tube (11) which is used to form the first vibration element (V1) has a caliber than is greater than a caliber of the at least one measuring tube (21) which is used to form the second vibration element (V2); and / or - wherein the second resonant frequency is lower than the first resonant frequency, in particular in such a way that the second resonant frequency is equal to less than 90% of the first resonant frequency; and / or - wherein the first and second vibration elements (V1, V2) are mechanically decoupled from each other in such a way that each of the two vibration elements can vibrate independently of the other vibration element, and / or in such a way that a lowest mechanical natural frequency of the first vibration element (V1) is different from a lowest mechanical natural frequency of the second vibration element (V2), in particular in such a way that said lowest mechanical natural frequency of the first vibration element is lower than said lowest mechanical natural frequency of the second vibration element; and / or - wherein the first vibration element (V1) is formed by means of at least two measuring tubes (11, 12), in particular measuring tubes that are straight and / or connected in parallel to each other in terms of flow and / or have an identical design; and / or - wherein the second vibrating element (V2) is formed by means of at least two curved measuring tubes (21, 22), in particular measuring tubes that are connected in parallel to each other in terms of flow, in particular in such a way that each of the at least two measuring tubes is connected in a bypass for the first vibration element (V1) in terms of flow; and / or - wherein the first vibration element (V1) can be connected to the pipeline, in particular can be inserted into its course, in such a way that the lumen of said vibration element communicates with a lumen of the pipeline; and / or - wherein the first and second vibration elements (V1, V2) are configured to have the medium flow through both of them at the same time.

12. The measuring system as claimed in one of the preceding claims, - wherein the first vibration element (V1) is formed by means of at least one measuring tube (11), in particular a measuring tube that is straight and / or can be inserted into the course of the pipeline and / or has a caliber of more than 20 mm; and / or - wherein a bypass that bridges the flow of the lumen of the first vibration element (V1) is formed using the second vibration element (V2).

13. The measuring system as claimed in one of the preceding claims, - wherein both the first and the second vibration elements are housed inside the lumen (H') of the housing (H); and / or - wherein each end of the housing has a connection flange.

14. The measuring system as claimed in one of the preceding claims, - wherein the measuring and operating electronics are configured, in order to actively cause resonant vibrations in the second vibration element (V2) contacted by the medium in an operating mode of the measuring system, to generate a second driver signal (e2) at least occasionally, and to determine a measured value (XV → X) serving as a valid measured value (X) for the measuring system, representing the volumetric flow rate, or to determine measured values (XV → X) representing the volume flow, based both of the first phase difference (Δϕ12) and on the signal frequency of at least one of the first and second vibration signals (s1, s2) corresponding to the first resonant frequency (fr1) of the first vibration element (V1); - and wherein the measuring and operating electronics are configured, based both on the signal frequency corresponding to the first resonant frequency fr1 of at least one of the first and second vibration signals (s1, s2) received during the operating mode and also on the signal frequency corresponding to the second resonant frequency (fr2) of at least the third vibration signal (s3) received during the operating mode, to perform a (self-)test of the measuring system, in particular with the aim of testing whether the measuring system continues to operate according to the specifications defined for this purpose, and / or whether the measured values (X) output by the measuring system can be considered valid.

15. The measuring system as claimed in the preceding claim, - wherein the measuring and operating electronics are configured to perform the test of measuring system by determining on a recurrent basis an, in particular relative or absolute, difference between the first and second resonant frequencies (fr1, fr2) using the measuring and operating electronics, and then comparing this with a corresponding limit value specified for this purpose, which represents a maximum permitted difference or a maximum difference between the first and second resonant frequencies (fr1, fr2) to be expected for an intact measuring system, in particular in such a way that the measuring and operating electronics are configured to generate an alarm in the event that said difference reaches or exceeds the aforementioned limit value, signaling that irreversible damage to at least one of the first and second vibration elements (V1, V2) has been detected, and / or in such a way that the measuring and operating electronics are configured to perform the test of the measuring system based on the first and second driver signals (e1, e2) generated during the operating mode; and / or - wherein the measuring and operating electronics are configured to perform the test of the measuring system based on the first and second driver signals (e1, e2) generated during the operating mode, in particular in such a way that the measuring and operating electronics determine for each of the first and second driver signals (e1, e2) an average electrical power, that is to say an average electrical power (Pexc1) of the first driver signal (e1) and an average electrical power (Pexc2) of the second driver signal (e2), and compare an, in particular relative or absolute, difference between the first and second electrical powers (Pexc1, Pexc2) with a corresponding limit value specified for this purpose.