Electrode for Magnetic Flow Sensor

• US 20070227248A1
• Filed: 06/30/2005
• Published: 10/04/2007
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: Sentec Ltd. (Xylem, Inc.)
• Original Assignee: Sentec Ltd. (Xylem, Inc.)
• Inventors: Glauser, Antony
• Granted Patent: US 7,735,379 B2
• Time in Patent Office: Days
• US Class Current: 73/514.390
• CPC Class Codes: G01F 1/584 constructions of electrodes, accessories therefor
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

There is described a fluid flow sensor (10) for sensing a flow (F) of a fluid (120) through a region. The sensor (10) comprises a magnetic circuit (50, 60a, 60b) for applying a magnetic field (70) to the region, and electrodes (40a, 40b) for sensing a potential (V) generated in operation between the electrodes (40a, 40b) in response to the fluid (120) flowing through the magnetic field (70). Each electrode (40) includes a metal element (130; 300; 400; 500), a metal halide element (110; 310, 320; 410; 520), and an electrically conductive porous element (100; 330; 420; 530). The porous element (100; 330; 420; 530) hinders progressive loss of the metal halide element (110; 310, 320; 410; 520) to the flow (F) and provides an electrically conductive path between the flow (F) and the metal halide element (110; 310, 320; 410; 520) and thereby to the metal element (130; 300; 400; 500). Inclusion of the porous element (100; 330; 420; 530) provides the sensor (10) with increased operating longevity without compromising its measurement noise performance.

Claims

1. A fluid flow sensor (10) for sensing a flow of a fluid (120) through a region, the sensor (10) comprising a magnetic circuit (30) for applying a magnetic field (70) to at least a part of the region, and a configuration of electrodes (40a, 40b) for sensing a potential generated in operation between the electrodes (40a, 40b) in response to the fluid (120) flowing through the magnetic field (120),

characterized in that each of the electrodes (40) includes a metal element (130;

300;

400;

500), a metal halide element (110;

310, 320;

410;

520), and an at least partially electrically conductive porous element (100;

330;

420;

530), said porous element (100;

330;

420;

530) being operable to at least partially hinder progressive loss of the metal halide element (110;

310, 320;

410;

520) to the flow of the fluid (120) and to provide an electrically conductive path between the flow of the fluid (120) and the metal halide element (110;

310, 320;

410, 520) and thereby to the metal element (130;

300;

400;

500).

2. A sensor (10) as claimed in claim 1, wherein the metal element (130;

300;

400;

500) includes silver and the metal halide element (110;

310, 320;

410;

520) includes silver chloride.

3. A sensor (10) as claimed in claim 1, wherein the porous element (100;

330;

420;

530) includes at least one of;

a metal wool, a metal foam, an at least partially electrically conductive porous polymer, at least partially electrically conductive porous graphite.

4. A sensor (10) as claimed in claim 1, wherein the porous element (100;

330;

420;

530) exhibits in operation a coefficient of electrical resistivity substantially at least an order of magnitude lower than that of the metal halide element (110;

310, 320;

410;

520).

5. A sensor (10) as claimed in claim 1, wherein the porous element (100;

330;

420;

530) exhibits in operation progressive dissolution or abrasion thereof into the flow of the fluid (120), thereby assisting to render pores (140) of the porous element (100;

330;

420;

530) providing porosity thereto accessible to the fluid (120).

6. A sensor (10) as claimed in claim 1, wherein the porous element (420) and the metal halide element (410) are substantially spatially coincident.

7. A sensor (10) as claimed in claim 1, wherein the metal halide element (110;

310, 320;

410;

520) is at least partially incorporated into the porous element (100;

330;

420;

530).

8. A sensor (10) as claimed in claim 1, wherein the porous element (100;

330;

420;

530) includes, or is pre-treated with, a wetting agent for rendering the porous element (100;

330;

420;

530) hydrophilic in respect of the fluid (120).

9. A sensor (10) as claimed in claim 1, wherein the metal element (130;

300;

400), the metal halide element (110;

310, 320;

410) and the porous element (100;

330;

420) are substantially mutually concentrically assembled together to form each corresponding electrode (40).

10. A sensor (10) as claimed in claim 1, wherein the metal element (500), the metal halide element (520) and the porous element (530) are implemented as elongate components, thereby rendering each electrode (40) substantially linear in shape.

11. A sensor (10) as claimed in claim 1, wherein at least one of the metal halide element (110;

310, 320;

410;

520) and the porous element (100;

330;

420;

530) are fabricated from particles bonded together so as to impart thereto porosity in respect of the fluid (120).

12. A sensor (10) as claimed in claim 10, wherein the particles are mutually bonded together by at least one of:

sintering, bonding by mechanical compression, bonding by way of an added bonding agent.

13. A sensor (10) as claimed in claim 1, wherein the metal element (300;

500) is spatially disposed to at least partially enclose the porous element (330;

530).

14. A sensor (10) as claimed in claim 1, wherein the porous element (420) is arranged to at least partially enclose the metal element (400).

15. A sensor (10) as claimed in claim 1, wherein the porous element (100;

330;

420;

530) is subjected during its manufacture to deposition of metal halide therein by way of electroplating and/or anodic deposition.

16. A sensor (10) as claimed in claim 15, wherein the anodic deposition involves a deposition of metal halide into the porous element (100;

330;

420;

530) by way of a treatment employing a salt including a metal present in the metal element (130;

300;

400;

500), and by way of a treatment employing an acid including a halide present in the metal halide element (110;

310, 320;

410;

530).

17. A sensor (10) as claimed in claim 16, wherein the salt includes silver nitrate and the acid includes hydrochloric acid.

18. A sensor (10) as claimed in claim 1 including a signal processing unit (90) for receiving from the configuration of electrodes (40a, 40b;

40) a signal corresponding to the potential generated between the electrodes (40a, 40b;

40) in operation, the signal processing unit (90) being operable to process the signal to generate at least one of a measure of the flow of the fluid (120), and a cumulative measure of the flow of the fluid, the sensor (10) in combination with the signal processing unit (90) thereby providing a fluid flow meter.

19. An electrode (40) for providing an electrical contact to a fluid (120), the electrode (40) comprising a metal element (130;

300;

400;

500),

characterized in that the electrode (40) further comprises a metal halide element (110;

310, 320;

410;

520) and an at least partially electrically conductive porous element (100;

330;

420;

530), said porous element (100;

320;

420;

530) being operable to at least partially hinder progressive loss of the metal halide element (110;

310, 320;

420;

520) to the fluid (120), and to provide an electrically conductive path between the fluid (120) and the metal halide element (110;

310, 320;

410;

520) and thereby to the metal element (130;

300;

400;

500).

20. An electrode (40) as claimed in claim 19, wherein the metal element (130;

300;

400;

500) includes silver, and the metal halide element (110;

310, 320;

410;

520) includes silver chloride.

21. An electrode (40) as claimed in claim 19, wherein the porous element (100;

330;

420;

530) includes at least one of;

a metal wool, a metal foam, an at least partially electrically conductive porous polymer, at least partially electrically conductive porous graphite.

22. An electrode (40) as claimed in claim 19, wherein the porous element (100;

330;

420;

530) exhibits in operation a coefficient of electrical resistivity substantially at least an order of magnitude lower than that of the metal halide element (110;

310, 320;

410;

520).

23. An electrode (40) as claimed in claim 19, wherein the porous element (100;

330;

420;

530) exhibits in operation progressive dissolution or abrasion thereof into the fluid (120), thereby assisting to render pores (140) of the porous element (100;

330;

420;

530) providing porosity thereto accessible to the fluid (120).

24. An electrode (40) as claimed in claim 19, wherein the porous element (420) and the metal halide element (410) are substantially spatially coincident.

25. An electrode (40) as claimed in claim 19, wherein the porous element (100;

330;

420;

530) includes, or is pre-treated with, a wetting agent for rendering the porous element (100;

330;

420;

530) hydrophilic in respect of the fluid (120).

26. An electrode (40) as claimed in claim 19, wherein the metal element (130;

300;

400), the metal halide element (110;

310, 320;

410) and the porous element (100;

330;

420) are substantially mutually concentrically assembled together to form the electrode (40).

27. An electrode (40) as claimed in claim 19, wherein the metal element (500), the metal halide element (520) and the porous element (530) are implemented as elongate components, thereby rendering the electrode (40) substantially linear in shape.

28. An electrode (40) as claimed in claim 19, wherein at least one of the metal halide element (110;

310, 320;

410;

520) and the porous element (100;

330;

420;

530) are fabricated from particles bonded together so as to impart thereto porosity in respect of the fluid (120).

29. An electrode (40) as claimed in claim 28, wherein the particles are mutually bonded together by at least one of:

sintering, bonding by mechanical compression, bonding by way of an added bonding agent.

30. An electrode (40) as claimed in claim 19, wherein the metal element (300;

500) is spatially disposed to at least partially enclose the porous element (330;

530).

31. An electrode (40) as claimed in claim 19, wherein the porous element (420) is arranged to at least partially enclose the metal element (400).

32. An electrode (40) as claimed in claim 19, wherein the porous element (100;

330;

420;

530) is subjected during its manufacture to deposition of metal halide therein by way of electroplating and/or anodic deposition.

33. An electrode (40) as claimed in claim 32, wherein the anodic deposition involves a deposition of metal halide into the porous element (100;

330;

420;

530) by way of treatment with a salt including a metal present in the metal element (130;

300;

400;

500), and of treatment with an acid including a halide present in the metal halide element (110;

310, 320;

410;

520).

34. An electrode (40) as claimed in claim 33, wherein the salt includes silver nitrate and the acid includes hydrochloric acid.

35. A method of fabricating an electrode (40) operable to enable an electrical contact to be made to a fluid (120), the method comprising steps of:

(a) providing a metal element (130;

300;

400;

500);

(b) providing a metal halide element (110;

310, 320;

410;

520);

(c) providing an at least partially electrically conductive porous element (100;

330;

420;

530) which is porous to the fluid (120); and

(d) mutually assembling the metal element (130;

310, 320;

410;

520), the metal halide element (110;

310, 320;

410;

520) and the porous element (100;

330;

420;

530) together such that the porous element (100;

330;

420;

530) is operable to hinder in use progressive loss of the metal halide element (110;

310, 320;

410;

520) to the fluid (120), and to provide an electrically conductive path between the fluid (120) and the metal halide element (110;

310, 320;

410;

520) and thereby to the metal element (130;

300;

400;

500).

36. A method of fabricating an electrode (40) as claimed in claim 35, the method comprising further steps of:

(e) including silver in the metal element (130;

300;

400;

500); and

(f) including silver chloride in the metal halide element (110;

310, 320;

410;

520).

37. A method of fabricating an electrode (40) as claimed in claim 35, the method comprising a further step of:

(g) fabricating the porous element (100;

330;

420;

530) to include at least one;

a metal wool, a metal foam, an at least partially electrically conductive porous polymer, at least partially electrically conductive porous graphite.

38. A method of fabricating an electrode (40) as claimed in claim 35, the method comprising a step of fabricating the metal halide element (410) and the porous element (420) so that they are substantially spatially coincident when included into the electrode (40).

39. A method of fabricating an electrode (40) as claimed in claim 35, the method including a further step of including within the porous element (100;

330;

420;

530), or pre-treating the porous element (100;

330;

420;

530) with, a wetting agent for rendering the porous element (100;

330;

420;

530) hydrophilic to the fluid (120).

40. A method of fabricating an electrode (40) as claimed in claim 35, the method comprising a further step of assembling the metal element (130;

300;

400), the metal halide element (110;

310, 320;

410) and the porous element (100;

330;

420) together in a mutually concentric arrangement to form the electrode (40).

41. A method of fabricating an electrode (40) as claimed in claim 35, the method comprising a further step of fabricating the metal element (500), the metal halide element (520) and the porous element (530) as elongate components for mutual assembly to fabricate the electrode, the electrode thereby being of substantially linear shape.

42. A method of fabricating an electrode (40) as claimed in claim 35, the method including a step of fabricating at least one of the metal halide element ((110;

310, 320;

410;

520) and the porous element (100;

330;

420;

530) from particles bonded together so as to thereto impart porosity in respect of the fluid (120).

43. A method of fabricating an electrode (40) as claimed in claim 42, wherein the particles are mutually bonded together by at least one of:

sintering, bonding by mechanical compression, bonding by way of an added bonding agent.

44. A method of fabricating an electrode (40) as claimed in claim 35, the method including a step of electroplating or anodically depositing metal halide into the porous element (100;

330;

420;

530) by treating the porous element (100;

330;

420;

530) with a salt including a metal present in the metal element (130;

300;

400;

500), and by treating the porous element (100;

330;

420;

530) with an acid including a halide present in the metal halide element (110;

310, 320;

410;

520).

45. A method of fabricating an electrode (40) as claimed in claim 44, the method being implemented such that the salt includes silver nitrate and the acid includes hydrochloric acid.