Apparatus for determining and/or monitoring at least one process variable of a medium

• US 10,641,736 B2
• Filed: 01/27/2016
• Issued: 05/05/2020
• Est. Priority Date: 02/10/2015
• Status: Active Grant

• Current Assignee: Endress+Hauser SE+Co. KG (Endress+Hauser AG)
• Original Assignee: Endress+Hauser SE+Co. KG (Endress+Hauser AG)
• Inventors: D'Angelico, Sascha, Schmitt, Christoph
• Primary Examiner(s): Schmitt, Benjamin R
• Application Number:
  US15/549,855
• Publication Number:
  US 20180024097A1
• Time in Patent Office: 1,560 Days
• Field of Search: 73 32 A, 73290 V
• CPC Class Codes: G01F 1/8436 signal processing
• CPC Class Codes: G01F 23/2967 for discrete levels
• CPC Class Codes: G01N 11/16 by measuring damping effect upon oscillatory body
• CPC Class Codes: G01N 2009/006 vibrating tube, tuning fork
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 29/022 Fluid sensors based on microsensors, e.g. quartz crystal-microbalance [QCM], surface acoustic wave [SAW] devices, tuning forks, cantilevers, flexural plate wave [FPW] devices microdevices per se B81B
• CPC Class Codes: G01N 29/024 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 9/002 using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis G01N9/34 takes precedence

Abstract

An apparatus for determining and/or monitoring at least a first process variable of a medium and method for operating the apparatus at least with an electronics unit and a sensor unit, wherein the electronics unit is embodied to supply the sensor unit with an excitation signal, which is composed of an excitation carrier signal with an excitation carrier frequency and an excitation modulation signal with an excitation modulation frequency, and to receive from the sensor unit a received signal, which is composed of a received carrier signal and a received modulation signal, and wherein the electronics unit is embodied to determine from the phase shift between the excitation modulation signal and the received modulation signal at least the first process variable.

Claims

1. An apparatus for determining and monitoring at least a first process variable of a medium, comprising:

an electronics unit; and

a mechanically oscillatable sensor unit,

wherein the electronics unit is embodied to supply the sensor unit with an excitation signal composed of an excitation carrier signal having an excitation carrier frequency and an excitation modulation signal having an excitation modulation frequency and to receive from the sensor unit a received signal composed of a received carrier signal and a received modulation signal,

and wherein the electronics unit is further embodied to measure a phase shift between the excitation modulation signal and the received modulation signal and to determine from the phase shift the first process variable.

2. The apparatus as claimed in claim 1, wherein the electronics unit is further embodied to determine from the received carrier signal at least a second process variable.

3. The apparatus as claimed in claim 1, wherein the sensor unit includes a mechanically oscillatable fork, a single rod, or a membrane.

4. The apparatus as claimed in claim 1, wherein the electronics unit is further embodied to determine and to monitor a predetermined fill level, a density or a viscosity of the medium.

5. The apparatus as claimed in claim 1, wherein the electronics unit is further embodied to control a phase shift between the excitation carrier signal and the received carrier signal to a predetermined value.

6. The apparatus as claimed in claim 1, wherein the electronics unit is further embodied to ascertain a damping from the phase shift between the excitation modulation signal and the received modulation signal.

7. The apparatus as claimed in claim 6, wherein the electronics unit is further embodied to ascertain from the damping at least a viscosity of the medium.

8. The apparatus as claimed in claim 1, wherein the electronics unit is further embodied to control the phase shift between the excitation modulation signal and received modulation signal to 45°

by adjusting the excitation modulation frequency.

9. A method for determining and monitoring a first process variable of a medium, comprising:

providing an electronics unit and a sensor unit;

supplying from the electronics unit to the sensor unit an excitation signal composed of an excitation carrier signal having an excitation carrier frequency and an excitation modulation signal having an excitation modulation frequency;

receiving by the electronics unit from the sensor unit a received signal composed of a received carrier signal and a received modulation signal; and

determining from a phase shift between the excitation modulation signal and the received modulation signal the first process variable.

10. The method as claimed in claim 9, further comprising:

determining from the received carrier signal at least a second process variable.

11. The method as claimed in claim 9, wherein the first process variable is a predetermined fill level, a density of the medium, or a viscosity of the medium.

12. The method as claimed in claim 9, further comprising:

controlling a phase shift between the excitation carrier signal and received carrier signal to a predetermined value.

13. The method as claimed in claim 9, further comprising:

determining a damping from the phase shift between the excitation modulation signal and the received modulation signal.

14. The method as claimed in claim 13, wherein at least a viscosity of the medium is ascertained from the damping.

15. The method as claimed in claim 9, further comprising:

controlling a phase shift between the excitation modulation signal and received modulation signal to 45°

by adjusting the excitation modulation frequency.