Fluid measuring device

Patent metadata

Field	Value
Publication number	US-11852608-B2
Application number	US-202117558791-A
Country	US
Kind code	B2
Filing date	Dec 22, 2021
Priority date	Dec 23, 2020
Publication date	Dec 26, 2023
Grant date	Dec 26, 2023

Abstract

A fluid measuring device for determining at least one characteristic property of a fluid includes a measuring tube having a fluid duct and a measuring section in which an area of a measuring tube wall is configured as a waveguide for surface acoustic waves which forms an interface to the fluid. At least two piezoelectric transducers are arranged in direct contact with an outer surface of the waveguide and one of which serves as a transmitter for exciting acoustic waves and at least one as a receiver for receiving acoustic waves. Acoustic waves excited by the transmitter can propagate as a volume wave through the fluid, and the piezoelectric transducers are configured to be elastically flexible while retaining their function in that the piezoelectric transducers have strip-shaped piezoelectric elements arranged parallel to each other, are rigid per se and between which a respective layer of an elastic material is arranged.

First claim

The invention claimed is:

1. A fluid measuring device for determining at least one characteristic property of a fluid, comprising:
a measuring tube having a fluid duct through which the fluid can flow and which has a measuring section in which at least an area of a measuring tube wall is configured as a waveguide for surface acoustic waves which forms an interface to the fluid, the measuring tube being configured to be cylindrical on an inside, and
at least three piezoelectric transducers which are arranged in direct contact with an outer surface of the waveguide and one of which serves as a transmitter for exciting acoustic waves in the waveguide and at least two serve as receivers for receiving acoustic waves,
wherein the acoustic waves excited by the transmitter can propagate at least in sections as a volume wave through the fluid,
wherein the at least three piezoelectric transducers are configured to be elastically flexible while retaining their function in that the at least three transducers have a plurality of strip-shaped piezoelectric elements which are arranged parallel to each other, are rigid per se and between which a respective layer of an elastic material is arranged,
wherein the at least three piezoelectric transducers rest in a planar manner against the measuring tube wall, and
wherein the at least three piezoelectric transducers, with respect to a center line thereof, are each arranged at an acute angle to a longitudinal extension direction of the measuring tube and, in addition, are arranged offset from each other in a circumferential direction and in the longitudinal extension direction of the measuring tube.

2. The fluid measuring device according to claim 1 , wherein the at least three transducers are bonded to the measuring tube wall.

3. The fluid measuring device according to claim 1 , wherein the elastic material is an elastomer or casting compound.

4. The fluid measuring device according to claim 1 , wherein the strip-shaped rigid piezoelectric elements and the layers of the elastic material arranged therebetween substantially form a cuboid in a non-bent state, a length of the cuboid being at most ten times a width thereof, and a height being approximately one tenth of the width.

5. The fluid measuring device according to claim 4 , wherein the strip-shaped rigid piezoelectric elements and the layers of the elastic material arranged therebetween alternate as seen in a longitudinal direction of the cuboid and each of the strip-shaped rigid piezoelectric elements extends over an entire width of the cuboid.

6. The fluid measuring device according to claim 4 , wherein the strip-shaped rigid piezoelectric elements and the layers of the elastic material arranged therebetween alternate as seen both in a longitudinal direction and in a transverse direction of the cuboid.

7. The fluid measuring device according to claim 1 , wherein the at least three piezoelectric transducers have an elastic printed circuit board or printed circuit board foil to which the strip-shaped piezoelectric elements are fastened and electrically contacted.

8. The fluid measuring device according to claim 7 , wherein the at least three piezoelectric transducers each have two electrodes which are mounted on the elastic printed circuit board or the printed circuit board foil and are arranged such that the acoustic wave is coupled into the measuring tube or received therefrom via a longest side of the piezoelectric transducer.

9. The fluid measuring device according to claim 1 , wherein the measuring tube wall has a substantially constant wall thickness throughout the measuring section.

10. The fluid measuring device according to claim 1 , wherein the at least three piezoelectric transducers, with respect to the respective center line thereof, are arranged at different acute angles to a longitudinal extension direction of the measuring tube.

11. The fluid measuring device according to claim 1 , wherein a first receiver is arranged on the measuring tube wall so as to receive a signal of an acoustic wave transmitted directly via the measuring tube wall serving as a waveguide, and in that a second receiver is arranged on the measuring tube wall so as to receive the signal of an acoustic wave which has propagated in sections as a volume wave through the fluid without having been reflected at the measuring tube wall.

12. The fluid measuring device according to claim 11 , wherein at least one further receiver is provided and arranged on the measuring tube wall so as to receive the signal of an acoustic wave which has propagated in sections as a volume wave through the fluid and has been reflected at least once on the measuring tube wall.

13. The fluid measuring device according to claim 1 , wherein at least five piezoelectric transducers are provided.

14. The fluid measuring device according to claim 1 , wherein the at least three piezoelectric transducers are arranged along the measuring tube such that two successive reflection areas of the volume wave in the longitudinal extension direction of the measuring tube are arranged offset from each other by less than 180° in the circumferential direction.

15. The fluid measuring device according to claim 1 , wherein the at least three piezoelectric transducers are arranged along the measuring tube such that two successive reflection areas of the volume wave in the longitudinal extension direction of the measuring tube are arranged offset from each other by 125° to 130° in the circumferential direction.

16. The fluid measuring device according to claim 1 , wherein the measuring tube in the measuring section is substantially rectangular in cross-section and has flat sides to which the at least three piezoelectric transducers are attached.

17. The fluid measuring device according to claim 16 , wherein the at least three piezoelectric transducers extend over at least 90% of a width of the fluid duct.

18. The fluid measuring device according to claim 1 , wherein at least two of the at least three piezoelectric transducers can be operated both as transmitters and as receivers.

19. A fluid measuring device for determining at least one characteristic property of a fluid, comprising:
a measuring tube having a fluid duct through which the fluid can flow and which has a measuring section in which at least an area of a measuring tube wall is configured as a waveguide for surface acoustic waves which forms an interface to the fluid, and
at least two piezoelectric transducers which are arranged in direct contact with an outer surface of the waveguide and one of which serves as a transmitter for exciting acoustic waves in the waveguide and at least one as a receiver for receiving acoustic waves,
wherein the acoustic waves excited by the transmitter can propagate at least in sections as a volume wave through the fluid,
wherein the at least two piezoelectric transducers are configured to be elastically flexible white retaining their function in that the at least two piezoelectric transducers have a plurality of strip-shaped piezoelectric elements which are arranged parallel to each other, are rigid per se and between which a respective layer of an elastic material is arranged,
wherein each of the at least two piezoelectric transducers has at least two pairs of electrodes, a first electrode of a pair of electrodes being arranged on a side of the piezoelectric elements facing away from the measuring tube and a second electrode of the same pair of electrodes being arranged on a side of the piezoelectric elements facing the measuring tube

Assignees

• Buerkert Werke Gmbh & Co Kg
• Burkert S A S

Inventors

• Fuchs Yannick

Classifications

• G01N29/024 Primary

  by measuring propagation velocity or propagation time of acoustic waves · CPC title

• G01N29/221

  Arrangements for directing or focusing the acoustical waves (electronic orientation or focusing G01N29/262; sound directing or focusing G10K11/26; mechanical steering of sound transducers or their beams G10K11/35) · CPC title

• G01N29/34

  Generating the ultrasonic, sonic or infrasonic waves {, e.g. electronic circuits specially adapted therefor} · CPC title

• G01N29/36

  Detecting the response signal {, e.g. electronic circuits specially adapted therefor} · CPC title

• G01N2291/102

  one emitter, one receiver · CPC title