• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for determining the degree of filling of a vibrator tube of a bending oscillator with a fluid to be examined, in particular in connection with the density measurement of fluids with this bending vibrator. The invention 5 is provided - that with the aid of calibration or calibration standards for the fluid to be examined or, for fluids possessing different viscosities, the relationship between the damping and / or oscillation amplitude of the bending oscillator and the degree of filling of the oscillator tube is determined, and - that in the course of determining the degree of filling, a parameter relevant for the damping and / or oscillation amplitude of the flexible oscillator is measured and this measured value considered relevant for the degree of filling and functionally related and used for the evaluation or determination of the degree of filling.
    公开号:AT516281A4
    申请号:T50792/2014
    申请日:2014-11-03
    公开日:2016-04-15
    发明作者:Robert Breidler
    申请人:Anton Paar Gmbh；
    IPC主号:
    专利说明:

    Method for determining the degree of filling of a vibrating tube of a bending vibrator and bending vibrator
    The invention relates to a method for determining the degree of filling of a vibrator tube of a bending vibrator with a fluid to be examined, in particular in connection with the density measurement of fluids with said flexural vibrator.Furthermore, the invention relates to a flexural vibrator according to the preamble of patent claim 6.
    The measurement of the density of fluid media with a bending vibrator is based on the fact that the vibration of a hollow body filled with a sample to be examined depends on the filling of the hollow body, in particular on the mass or, if the volume is constant, on the density of the medium filled.
    A flexural vibrator is formed by a hollow, U-shaped, glass or metallic tube which is electronically excited to vibrate, particularly to resonant vibrations. The two legs of the U-shaped tube form the spring elements of the bending oscillator. The natural frequency of the U-shaped oscillator tube is affected by that part of the sample which actually participates in the vibration. The volume participating in the oscillation is limited by the resting oscillation nodes at the two clamping points of the tube. If the vibrator is completely filled with the sample at least up to the clamping points, the same volume of the vibrating part is always used, and the mass of the sample can therefore be assumed to be proportional to its density. Overfilling the vibrator beyond the clamping points is irrelevant to the measurement. For this reason, it is also possible to measure with the oscillator densities of media which flow through the oscillator or oscillator tube. However, problems arise if the oscillating tube is not completely filled.
    Fig. 1 and 2 show the basic principle of a present invention usable bending oscillator, here in the form of a Doppelbugschwingers with mass balance, however, all possibly used damping elements are not shown. This double-bow bending oscillator 60 comprises a rocker tube 9, bent in a U-shaped manner in a region 4, whose ends or limbs 10, 11 are each connected to an end connection 2, 3. To carry out a density measurement, the tube 9 is flowed through the end connections or carrier 2, 3 with fluid. In bending areas 5, 5 ', the longitudinal center region of the tube 9 with the base 4 is bent in the direction of the end connections 2, 3 and forms further legs 12, 13, as can be seen in FIG. In at least one of the bending regions 5 is a vibration exciter 7 and in each opposite bending region 5 'is a measuring unit 7' for at least one vibration parameter, preferably the vibration amplitude, is provided, which is taken into account for the excitation of a vibration. In practice, one or two vibration exciters 7 and one or two measuring units 7 'are thus provided. The tube 9 or the bending areas 5, 5 'are vibrated with the vibration exciter 7 signal-loaded by the measuring unit 7, the bending areas 5, 5' swinging towards and away from each other, as represented by the arrow 6. The decrease of the vibration parameter takes place with a measuring unit 7 'designed as a vibration detector. The oscillation excitation and the decrease of the oscillation parameters advantageously takes place in an electromagnetically controlled or supervised manner with a measuring or sensor electronics 40 or with an illustrated control unit which is in particular connected to the oscillation exciter 7 or to the oscillation detector 7 '. Depending on the measured value of the measuring unit 7 ', the vibration exciter 7 is activated in order to drive or to excite the vibrating tube at the given time.
    The clamping point of the oscillator tube is always to be considered as a so-called vibration node of the oscillating system, a filling of the oscillator tube beyond this holding and clamping point plays no role in the vibration and does not contribute to the measurement.
    In a "Y-oscillator", as shown schematically in Fig. 3, the U-shaped tube 1 oscillates perpendicular to the plane which is spanned by the two legs 2, 3 of the tube 1. In principle, vibrational modes can also be excited, in which the legs 2, 3 of the bent tube 9 oscillate in this plane against each other. There are certain resonance frequencies for the oscillator in which the oscillator or tube 9 oscillates almost unattenuated.
    In addition to apparatus constants, e.g. Like the material and dimensions of the vibrator, the density of the fluid to be tested determines the specific frequencies at which the U-tube resonates. Thus, always using the same tube, in particular glass tube or metal tube, the properties of the vibrator vary with the density of the liquid. The resonance frequencies are evaluated with respect to the excitation and decrease of the vibrations, and from the period duration the density of the filled fluid is determined. The transducer is calibrated with fluids of known density so that the readings become directly evaluable. For the period P of a bending vibrator in the fundamental mode:
    (1) this results in reshaping for the density:
    where m is the oscillating mass, p is the density of the fluid and V is the tube volume and R is a cost of the vibrator, including the material and vibrational shape of the vibrator used.
    The Justierkonstanten A and B are determined for the respective oscillator by measurements with fluids of known density and stored in the evaluation of the vibrator.
    In bending oscillators, therefore, the change in the natural frequency of a bending vibration mode and / or the period P of the same when the tube is filled with fluids is used to deduce the density of the medium.
    In addition to the laboratory oscillators with large countermass and Doppelbugschwingerbekannt are known, the use of two U-tubes that swing against each other, with good accuracy make the large counterweight dispensable and are therefore also available for light and small handheld instruments.
    Especially in most applications of these hand-held density gauges, largely aqueous solutions are investigated, e.g. Fermenting samples in the wine and beer industry, the Väskositätswert hardly deviates from the water value.
    Alternatively, special purpose diagonal gauges may already be formed by taking into account the viscosity value for the fluid of the particular application via the gage constants, and the output of the gimbal's gage value may already be corrected. The damping can thus be used to correct the viscosity. For special applications, however, a viscosity correction of the density measurement by means of damping measurement is not necessary.
    It is known that the viscosity of the medium to be investigated has an influence on the results of the density measurement. Different correction methods are known for this viscosity correction; they are based on the fact that the attenuation of the vibrator is functionally related to the viscosity and this relationship can be evaluated by measuring a parameter characteristic of the attenuation. This under the assumption that the oscillator tube is bubble-free or the filling shows no inhomogeneities.
    The object of the invention is to detect filling errors or to determine the degree of filling by measuring, in addition to a natural frequency of the bending oscillator, the damping of the bending oscillator and carrying out an evaluation with regard to filling inhomogeneity of the oscillating tube. The damping or a parameter relevant for damping is thus used for the detection of bubbles and / or inhomogeneities in the filling.
    This object is achieved in a method of the type mentioned above with the features indicated in the characterizing part of claim 1. It is envisaged that the relationship between the damping and / or oscillation amplitude of the bending oscillator and the degree of filling of the oscillator tube is determined with the aid of calibration standards for the fluid to be investigated or fluids having different viscosities, and that during the determination of the degree of filling measured for the attenuation and / or vibration amplitude of the bending oscillator relevant parameter and this measured value as relevant for the degree of filling and considered in functionally related and used for the evaluation or determination of the degree of filling. Surprisingly, it turns out that exact measurement values on the presence and extent of inhomogeneities, in particular glass bubbles, can be obtained in the fluid to be examined, even if the degree of filling of the two tube legs is different. Also, a different distribution of inhomogeneities or bubbles in the two tube legs does not affect the measurement results to an intolerable extent. The expected effects of irregularly distributed inhomogeneities play no significant role in the inventive procedure.
    Examining a bending oscillator in terms of amplitude over a wider frequency spectrum around its resonance frequency, in the present case: water, once with and once without gas bubbles in the liquid, one recognizes a clearly different behavior, as shown in Fig. 4.
    4 shows the different amplitudes of one and the same oscillator once with and once without air bubbles in the measurement of water. Clearly, the influence of bubbles on the attenuation of the oscillator is clearly recognized by the broader, more "blurred" amplitude peak in the frequency spectrum. The inhomogeneously filled oscillator shows more damping than the homogeneously filled one.
    According to the invention, in order to determine the parameter relevant for the attenuation, the bending oscillator is excited in its respective resonant frequency by two different phase angles and the resonant frequency associated with the respective phase position is determined and the degree of filling is deduced therefrom. The attenuation of such a waveform can be easily determined by exciting the flexural resonator in its resonant frequency through two different phase angles, measuring the associated frequencies, and calculating the attenuation therefrom. It is advantageous to detune the phase relationship between the start signal and the accept signal, which is usually 90 °, e.g. to a value of 45 °. This is done with a control unit fed with the acceptance signal, which adjusts the excitation accordingly.
    For this purpose, in the circuit of the control unit for exciting and decreasing the oscillator frequencies, an additional element or phase rotator is introduced, which can rotate or change the phase between excitation and decrease.
    In general, for the damping θ or for the quality of the oscillator: Q = f (f 1, f 2, < Pi, Ψ 2)
    The oscillator is thus alternately or for certain periods of time excited with signals of different phase to vibrate. For the oscillation in the dephased phase position, the exciter signal, with which the oscillator is excited to its resonant frequency, is time shifted, ie phase shifted, from the excitation time, resulting in a changed, detuned resonant frequency. In principle, the natural frequency of the oscillator remains the same, but the phase-shifted excitation detunes the oscillator and this results in a slightly changed frequency. This change will be larger if the transducer is not filled correctly.
    If one examines the changed behavior of an inhomogeneously filled oscillator in comparison to the homogeneously filled oscillator in the known Bode diagram, it can be seen in Fig. 5 from the broadening of the amplitude spectrum that the frequency shift in the phase-shifted signal or in the case of phase-shifted excitation also has to be larger for the inhomogeneously filled oscillator.
    For the difference Δf between the resonant frequencies f1 and f2 measured in the different phase positions in resonance and out of phase, the difference must be smaller for the homogeneously filled oscillator: λf (homogeneous) <= λf (inhomogeneous)
    With: ΔίΗ = f1 (cpi) H -f2 (cp2) Dog: Δί, = f1 (ψ!), -Ί2 (φ2).
    It is thus possible to define a criterion for the maximum tolerable difference between the two frequencies, in order to ensure the homogeneous filling of the oscillator and, if appropriate, to conclude a filling failure warning and / or the degree of filling.
    For this purpose, at least the element 32 which changes the phase position of the oscillator with respect to its excitation by the exciter amplifier is introduced into the circuit for excitation and signal decay of the oscillations. Between the "conventional" excitation signal φ1 and the excitation signal φ2 shifted by a certain phase angle, it is possible to switch back and forth by switching with an electronic switch 41.
    As a result, the oscillator can be examined in two different phases when excited with approximately the same or slightly different excitation frequency. If the oscillator is excited in phase with the deflection amplitude, the resonance frequency is set.
    If the phase angles of excitation and decay do not match, the result is a frequency f2 deviating somewhat from the resonance frequency, as can be seen in FIG.
    FIG. 7 shows a principle of a bending oscillator arrangement according to the invention. The
    Natural frequency of the medium-filled bending oscillator 60 or oscillator tube 9 is determined by the bending oscillator 60 is operated in a harmonic oscillator. The decrease signal of the bending oscillator is amplified by means of an amplifier 20.
    A phase rotator 31 rotates the phase of this signal so that the phase condition of the oscillation equation is satisfied. This signal is provided at 32, in a parallel branch 33 the phase of the decay signal is additionally shifted by a constant value. This signal is available at 33.
    By means of an electronic switch 41 is now between the two Phasendrehernbzw. Pointers 32, 33 switched. In principle, an additional phase rotator could be incorporated into the circuit. The resulting natural frequencies of the vibrating tube 9 are determined by means of a frequency measurement with the measuring or control electronics 40 or the unit 50.
    The excitation is here integrated into the phase rotator 31 in terms of circuit, in addition, a decrease or measurement of the resulting frequency in the unit 50 can additionally take place.
    The phase rotator 31 and amplifier 20 in combination form the so-called exciter amplifier. With such an exciting amplifier, the vibrator can be put in a state of resonance vibration. The period duration or frequency of the oscillation is measured by the frequency meter 50 and fed to the evaluation unit 40 for determining the density between the damping and / or oscillation amplitude of the bending oscillator 60 and the calibration unit by means of calibration or calibration standards for the fluid to be investigated or for different viscosities Filling degree of the oscillator tube 9 is stored in a storage unit 80 is present.
    The flexural vibrator 60 is operated with this excitation amplifier, which excites the vibrator in one of its resonant natural oscillations. The frequency or period of the oscillator is measured and can also be used in a known manner or with the aid of calibration or calibration data to determine the density of the fluid to be examined.
    The phase rotator in the simplest case is an RC low-pass, or more complex higher-order filters or so-called dead-time elements, generally a combination of resistor and capacitor, may be used. The phase rotator forms an oscillator with the amplifier and the oscillator, which oscillates itself into resonance by noise or another initial impulse.
    As a relevant parameter for the amplitude of oscillation, when the excitation or frequency shift is changed, the amount of energy required to keep the amplitude constant could be used, since in the presence of inhomogeneities or bubbles in the fluid, the amplitude decreases and additional energy for excitation is required to maintain a constant amplitude.
    An advantageous construction of the bending oscillator provides that a comparison unit 61 is provided, which compares the resonant frequencies determined to the two phase positions or forms their difference, and that depending on the comparison or the size of the difference, the degree of filling of the oscillating tube 9 is determined or as proper or is detected incorrectly.
    权利要求:
    Claims (10)
    [1]
    Claims 1. A method for determining the degree of filling of a vibrating tube of a bending vibrator with a fluid to be examined, in particular in connection with the density measurement of fluids with said bending vibrator, characterized in that - by means of calibration or calibration standards for the fluid to be investigated or for different viscosities Fluids the relationship between the damping and / or vibration amplitude of the bending oscillator (60) and the degree of filling of the oscillator tube (9) is determined, and - that in the course of determining the degree of filling a relevant for the damping and / or vibration amplitude of the bending oscillator measured parameter and this reading as for the Degree of filling relevant and considered functionally related and used for the evaluation or determination of the degree of filling.
    [2]
    2. The method according to claim 1, characterized in that for determining the parameter relevant to the attenuation of the bending vibrator is excited in its respective resonant frequency by two different phase angles and determines the resonant frequency associated with the respective phase position and is concluded therefrom on the degree of filling.
    [3]
    3. The method of claim 1 or 2, characterized in that - the resonant frequencies determined to the two phase positions are compared or their difference is formed, and - that recognized as a function of the comparison or the size of the difference of Befgradungsgradermittelt and possibly as correct or incorrect becomes.
    [4]
    Method according to one of claims 1 to 3, characterized in that the resonant frequencies are determined with a bending vibrator filled with the fluid to be examined by operating the bending oscillator in a harmonic oscillator.
    [5]
    5. The method according to any one of claims 1 to 4, characterized in that is used asrelevanten parameter for the vibration amplitude of the energy required for a Konstanthaltung the amplitude in the measurement of the degree of filling.
    [6]
    6. bending oscillator comprising a unit for determining the degree of filling of the oscillator tube (9) of the bending oscillator with a fluid to be examined, optionally in connection with the density measurement of fluids, in particular using the method according to one of claims 1 to 6, characterized in that the bending oscillator associated unit comprises a storage unit (80) for the determined by means of adjusting or calibration standards, in particular for different viscosities, determined relationship between the attenuation and / or the oscillation amplitude of the bending oscillator and the degree of filling of the oscillator tube (9), and - that the bending oscillator has an evaluation unit which, in the course of determining the degree of filling, evaluates the parameter relevant for the damping of the bending oscillator.
    [7]
    A flexural vibrator according to claim 6, characterized in that the bending oscillator for determining the attenuation relevant parameter comprises a vibration exciter which excites the vibrating tube (9) in its respective resonant frequency in two different phase positions and determines with the evaluating unit the resonant frequency associated with the respective phase position and therefrom the attenuation is determined or the associated attenuation value is calculated.
    [8]
    8. bending vibrator according to claim 6 or 7, characterized in that - a comparison unit (61) is provided which compares the resonant frequencies determined to the two phase positions with each other or forms their difference, and - that depending on the comparison or the size of the difference of the Befungsgradungsgraddes Swing tube (9) is detected or recognized as correct or faulty.
    [9]
    A flexural vibrator according to any one of claims 6 to 8, characterized in that the flexural vibrator is designed as a harmonic oscillator and thus determines the resonant frequencies of the flexure oscillator filled with the fluid to be examined.
    [10]
    10. bending vibrator according to one of claims 6 to 9, characterized in that inden the vibration exciter (7) and the vibration pickup (7 ') containing circuit, in particular in the control unit (40) switched on a phase rotator. is arranged.
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    引用文献:
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA50792/2014A|AT516281B1|2014-11-03|2014-11-03|Method for determining the degree of filling of a transducer tube of a bending vibrator and bending vibrator|ATA50792/2014A| AT516281B1|2014-11-03|2014-11-03|Method for determining the degree of filling of a transducer tube of a bending vibrator and bending vibrator|
    EP15189384.9A| EP3015846A1|2014-11-03|2015-10-12|Method for determining the filling level a vibrator pipe of an oscillator and oscillator|
    US14/929,834| US20160131565A1|2014-11-03|2015-11-02|Method of determining a fill level of an oscillator of an oscillator tube, and oscillator tube|
    CN201511035975.9A| CN105716994A|2014-11-03|2015-11-03|Method for determining the filling level a vibrator pipe of an oscillator and oscillator|
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