Density Measuring Device

Patent metadata

Field	Value
Publication number	US-2016349091-A1
Application number	US-201415102626-A
Country	US
Kind code	A1
Filing date	Nov 3, 2014
Priority date	Dec 9, 2013
Publication date	Dec 1, 2016
Grant date	—

Abstract

The density measuring device serves for measuring density, ρ, of a flowable medium and comprises a measuring device electronics (ME) as well as a measuring transducer (MT) electrically connected therewith. The measuring transducer includes a measuring tube ( 10 ), an oscillation exciter ( 41 ) for exciting and maintaining oscillations and an oscillation sensor ( 51 ) for registering oscillations of the at least one measuring tube. The measuring device electronics is adapted by means of an oscillation measurement signal (s 1 ) as well as an exciter signal (e 1 ) to adjust a drive force effecting wanted oscillations (namely oscillations with a predetermined wanted frequency, f N ) of the measuring tube. The drive force is adjusted in such a manner that during a predetermined phase control interval a phase shift angle, φ N , by which a velocity response, V N , of the measuring tube Is phase shifted relative to a wanted force component, F N , of the drive force, is less than −20° and greater than −80°, and/or the wanted frequency has a frequency value, which corresponds to greater than 1.00001 times, equally as well less than 1.001 times, a frequency value of an instantaneous resonant frequency of the measuring tube. Moreover, the measuring device electronics is adapted based on the oscillation measurement signal (s 1 ) present during the phase control interval to ascertain at least one frequency measured value, X f , which represents the wanted frequency for the phase control interval, as well as also with application of the frequency measured value, X f , to generate a density measured value, X ρ , representing a density, ρ.

First claim

1 - 25 . (canceled)

26 . A density measuring device, and/or a density/viscosity measuring device for measuring density of a flowable medium, especially a gas or a liquid, said measuring device comprising:
measuring device electronics; and a measuring transducer electrically connected with said measuring device electronics, said measuring transducer including: at least one measuring tube, especially an at least sectionally straight and/or at least sectionally curved, measuring tube; an oscillation exciter, especially an electrodynamic, electrostatic or piezoelectric oscillation exciter, for exciting and maintaining oscillations, especially wanted oscillations, of said at least one measuring tube; and a first oscillation sensor, especially an electrodynamic or electrostatic first oscillation sensor, for registering oscillations of said least one measuring tube, wherein: said at least one measuring tube exhibits a lumen surrounded by a tube wall and is adapted to guide medium in its lumen and during such guidance to be caused to vibrate in such a manner that said at least one measuring tube executes wanted oscillations, namely mechanical oscillations, especially bending oscillations, about a resting position with a wanted frequency, especially a wanted frequency codetermine by the density of the medium; said first oscillation sensor, especially a first oscillation sensor spaced from said oscillation exciter along said at least one measuring tube, is adapted to register oscillatory movements of said at least one measuring tube and to transduce such into a first oscillation measurement signal representing such; said measuring device electronics is adapted to transduce, by means of said exciter signal, supplied electrical power into a drive force acting on a point of engagement of said at least one measuring tube formed by means of said oscillation exciter; said drive force includes a wanted force component introduced into said at least one measuring tube, namely a periodic force component changing with an excitation frequency corresponding to the wanted frequency and effecting the wanted oscillations; said measuring device electronics is further adapted to adjust, by means of said first oscillation measurement signal as well as said exciter signal, said drive force, namely the wanted force component, respectively its excitation frequency, in such a manner that during a predetermined phase control interval, especially a predetermined phase control interval not less than 10 ms: a phase shift angle, especially a constant phase shift angle, by which a velocity response of said at least one measuring tube, especially a velocity of the oscillatory movements of said at least one measuring tube at the point of engagement changing with the wanted frequency as a function of time, is phase shifted from said wanted force component of said drive force, amounts less than −20° and more than −80°, especially less than −30° and/or more than −70°, and/or the wanted frequency exhibits a frequency value, which corresponds to greater than 1.00001 times, equal as well less than 1.001 times of a frequency value of an, especially lowest, instantaneous resonant frequency of said at least one measuring tube; and said measuring device electronics is further adapted to ascertain, based on said first oscillation measurement signal present during the phase control interval, at least one frequency measured value, which represents the wanted frequency for the phase control interval and to generate with application of the frequency measured value a density measured value representing the density.

27 . The density measuring device as claimed in claim 26 , wherein:
said first oscillation measurement signal has a signal frequency corresponding to the wanted frequency.

28 . The density measuring device as claimed in claim 26 , wherein:
said exciter signal has a signal frequency corresponding to the wanted frequency.

29 . The density measuring device as claimed in claim 26 , wherein:
said measuring device electronics is adapted to adjust the drive force, especially its wanted force component, by changing a signal frequency of said exciter signal.

30 . The density measuring device as claimed in claim 26 , wherein:
said measuring device electronics is adapted to bring the phase shift angle, during the total phase control interval and/or for a duration of greater than 10 ms to a predetermined desired phase value; especially in such a manner that the phase shift angle, in the case of constant density fluctuates by less than ±1% of the desired phase value, and/or by less than ±2° around the desired phase value.

31 . The density measuring device as claimed in claim 30 , wherein:
said measuring device electronics has a phase locked loop, especially a digital phase locked loop, for setting said phase shift angle.

32 . The density measuring device as claimed in claim 26 , wherein:
said measuring device electronics is adapted to change a signal frequency of said exciter signal until the phase shift angle, has achieved a predetermined desired phase value, especially namely in such a manner that said measuring device electronics in the case of a too small phase shift angle, namely a phase shift angle, set less than the desired phase value, lessens the signal frequency, and in such a manner that said measuring device electronics in the case of a too large phase shift angle, namely a phase shift angle, set greater than the desired phase value, increases the signal frequency.

33 . The density measuring device as claimed in claim 26 , wherein:
said measuring tube is adapted to be flowed through by the medium with a mass flow rate, during execution of the wanted oscillations, especially namely in order to induce in the flowing medium Coriolis forces dependent on its mass flow rate, which Coriolis forces are suitable to bring about Coriolis oscillations superimposed on the wanted oscillations and of equal frequency thereto.

34 . The density measuring device as claimed in claim 26 , wherein:
said measuring transducer has a second oscillation sensor spaced along said measuring tube from said first oscillation sensor, especially said second oscillation sensor constructed equally to said first oscillation sensor, for registering oscillations, especially outlet-side oscillations, of said at least one measuring tube; and said second oscillation sensor is adapted to register oscillatory movements of said at least one measuring tube and to transduce such into a second oscillation measurement signal representing such.

35 . The density measuring device as claimed in claim 34 , wherein:
said second oscillation measurement signal has a signal frequency corresponding to the wanted frequency.

36 . The density measuring device as claimed in claim 34 , wherein:
said measuring device electronics is adapted to ascertain the frequency measured value, based on both said first oscillation measurement signal as well as also said second oscillation measurement signal; and/or said measuring device electronics is adapted to adjust the wanted force component also by means of the second oscillation measurement signal.

37 . The density measuring device as claimed in claim 34 , wherein:
said measuring tube is adapted to be flowed through by the medium with a mass flow rate, during execution of the wanted oscillations, in order to induce in the flowing medium Coriolis forces dependent on its mass flow rate, which Coriolis forces are suitable to bring about Coriolis oscillations superimposed on the wanted oscillations and of frequency equal thereto, in such a manner that between said first oscillation measur

Assignees

• Endress & Hauser Flowtec Ag

Inventors

• Huber Christof
• Kumar Vivek
• Montsko Philipp
• Schwer Tobias

Classifications

• G01N11/16

  by measuring damping effect upon oscillatory body · CPC title

• G01N9/002 Primary

  using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis (G01N9/34 takes precedence) · CPC title

• G01F1/8468

  vibrating measuring conduits · CPC title

• G01F1/8472 Primary

  having curved measuring conduits, i.e. whereby the measuring conduits' curved center line lies within a plane (G01F1/8481 takes precedence) · CPC title

• G01N2009/006

  vibrating tube, tuning fork · CPC title