Magnetic core configuration for magnetic flowmeters having a plurality of layers of magnetically permeable material

Patent metadata

Field	Value
Publication number	US-9631962-B2
Application number	US-201414502519-A
Country	US
Kind code	B2
Filing date	Sep 30, 2014
Priority date	Mar 18, 2014
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A flowtube assembly for a magnetic flowmeter is provided. The flowtube assembly includes a flowtube configured to receive a flow of process fluid. A magnetic core is mounted relative to the flowtube and includes a plurality of layers of a magnetically permeable material. Each layer is substantially planar and is electrically insulated from others of the plurality of layers. A coil is disposed to generate a magnetic field having field lines that are substantially orthogonal to the plane of each layer.

First claim

What is claimed is:

1. A flowtube assembly for a magnetic flowmeter, the flowtube assembly comprising:
a flowtube having a longitudinal axis and being configured to receive a flow of process fluid therethrough;
a first magnetic core mounted relative to the flowtube, the first magnetic core including a plurality of layers of a magnetically permeable material, wherein each layer is substantially planar, wherein each respective plane is disposed substantially parallel to the longitudinal axis of the flowtube, and is electrically insulated from others of the plurality of layers; and
a first coil disposed to generate a magnetic field having field lines that are substantially orthogonal to the plane of each layer.

2. The flowtube assembly of claim 1 , wherein the plurality of layers are stacked.

3. The flowtube assembly of claim 1 , wherein each of the plurality of layers is coated in an insulating material.

4. The flowtube assembly of claim 3 , wherein the insulating material is varnish.

5. The flowtube assembly of claim 1 , wherein a physical parameter of the first magnetic core is selected based on a desired electrical characteristic of the first magnetic core.

6. The flowtube assembly of claim 5 , wherein the physical characteristic is a number of layers in the plurality of layers.

7. The flowtube assembly of claim 5 , wherein the physical characteristic is a thickness of each layer.

8. The flowtube assembly of claim 5 , wherein the physical characteristic is a material with which each layer is constructed.

9. The flowtube assembly of claim wherein the physical eristic is layer orientation.

10. The flowtube assembly of claim 5 , wherein the physical characteristic is a material used to insulate each layer from the others.

11. The flowtube assembly of claim 5 , wherein the physical characteristic is insulation thickness.

12. The flowtube assembly of claim 5 . wherein the desired electrical characteristic is inductance.

13. flowtube assembly of claim 5 , wherein the desired electrical characteristic is resistance.

14. The flowtube assembly of claim 1 , wherein a physical parameter of the first magnetic core is selected based on a desired magnetic characteristic of the first magnetic core.

15. The flowtube assembly of claim 14 , wherein the desired magnetic characteristic is reluctance.

16. The flowtube assembly of claim 1 , and further comprising a mounting stud affixed to the flowtube and mounting the first magnetic core and a spool to the flowtube.

17. The flowtube assembly of claim 1 , and further comprising a magnetic return assembly formed of a magnetically permeable material and coupled to the first magnetic core.

18. The flowtube assembly of claim 17 , wherein the magnetic return assembly and the first magnetic core are formed of the same magnetically permeable material.

19. The flowtube assembly of claim 18 , wherein the magnetically permeable material is silicon steel.

20. The flowtube assembly of claim 1 , and further comprising:
a second magnetic core mounted opposite the first magnetic core on the flowtube, the second magnetic core including a plurality of layers of a magnetically permeable material, wherein each layer is substantially planar and is electrically insulated from others of the plurality of layers; and
a second coil disposed to generate a magnetic field having field lines that are substantially orthogonal to the plane of each layer.

21. The flowtube assembly of claim 1 , and further comprising a pair of electrodes disposed to contact the process fluid.

22. A magnetic flowmeter for measuring a flow velocity of a process fluid, the magnetic flowmeter comprising:
a flowtube assembly including:
a flowtube having a longitudinal axis and being configured to receive a flow of process fluid therethrough;
a pair of magnetic cores mounted on opposite sides of the flowtube, each magnetic core including a plurality of layers of a magnetically permeable material, wherein each layer is substantially planar, and substantially parallel to the longitudinal axis, and is electrically insulated from others of the plurality of layers;
a pair of coils, each being disposed to generate a magnetic field having field lines that are substantially orthogonal to the plane of each layer;
a pair of electrodes disposed to contact process fluid flowing through the flowtube; and
flowmeter electronics coupled to the pair of electrodes and to the pair of coils, the flowmeter electronics being configured to generate a magnetic field via the pair of coils and measure an induced electromotive force (EMF) induced in the process fluid via the pair of electrodes.

23. The magnetic flowmeter of claim 22 , wherein the flowmeter includes circuitry for coupling to a wired process communication loop and wherein the magnetic flowmeter is wholly powered by the process communication loop.

24. The magnetic flowmeter of claim 22 , wherein the magnetic flowmeter is battery-powered.

25. The magnetic flowmeter of claim 22 , wherein the flowmeter electronics are configured to provide an excitation signal to the pair of coils, and wherein a frequency of the excitation signal is about 500 Hz.

26. The magnetic flowmeter of claim 22 , wherein the flowmeter electronics are configured to provide an excitation signal to the pair of coils that is sinusoidal.

Assignees

• Rosemount Inc

Inventors

• Rovner Bruce D
• Messenger Samuel E
• Dreier Jared J
• Beyl John C

Classifications

• G01F1/60 Primary

  Circuits therefor · CPC title

• G01F1/586

  constructions of coils, magnetic circuits, accessories therefor (G01F1/582 takes precedence; magnet; inductances; transformers; selection of materials for their magnetic properties per se H01F) · CPC title