MAGNETIC ELEMENT TEMPERATURE SENSORS

• US 20070263699A1
• Filed: 01/02/2007
• Published: 11/15/2007
• Est. Priority Date: 05/09/2006
• Status: Active Grant

• Current Assignee: TSI SUB LLC
• Original Assignee: Thermal Solutions Incorporated (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Clothier, Brian L., Abbett, Edwin T.
• Granted Patent: US 7,794,142 B2
• Time in Patent Office: Days
• US Class Current: 374/163
• CPC Class Codes: G01K 7/36 using magnetic elements, e.g. magnets, coils magnetic elements per se H01F
• CPC Class Codes: H05B 2213/06 Cook-top or cookware capable of communicating with each other
• CPC Class Codes: H05B 6/062 for cooking plates or the like

Abstract

Small, low-cost wireless temperature sensors (26,64,96) are provided for sensing the temperature of an object (44). The temperature sensors (26,64,96) preferably include a plurality of individual, magnetically susceptible temperature sensor elements (28-34,66,92), as well as optional magnetic field-responsive data elements (38,40,20) adapted for attachment to object (44) or to a substrate (82) in turn attached to object (44). The temperature sensor elements (28-34,66,92) preferably have magnetic bodies (22,70) exhibiting a re-magnetization response under the influence of an applied alternating magnetic field, which is different below and above a set point temperature, normally the Curie temperature of the magnetic body (22) or an adjacent sheath (74,94). The temperature sensors (26,64,96) are used in conjunction with a detector (46) operable to generate a magnetic field of magnitude sufficient to cause re-magnetization responses of the temperature sensor elements (28-34,66,92) and optional data elements (38,40,20), to detect such responses, and to use the detected responses to determine the temperature of object (44) by means of a decoding algorithm. The temperature sensors (26,64,96) can be used in closed-loop heating systems (98) capable of controlling the heating of an object (114).

Claims

1. A temperature sensor configured to be placed in thermal contact with an object in order sense the temperature of the object, said sensor comprising at least one magnetically susceptible sensor element having a re-magnetization response under the influence of an applied alternating magnetic field, said re-magnetization response defined by at least one short, detectible pulse of magnetic field perturbation of defined duration and being different below and above at least one set point temperature below about 400°

C.

2. The sensor of claim 1, there being a plurality of said sensor elements, with at least certain of said sensor elements having a different set point temperature than other of the sensor elements.

3. The sensor of claim 1, said element set point temperature being the Curie temperature of the element.

4. The sensor of claim 1, said sensor element having different re-magnetization responses above and below a plurality of different set point temperatures.

5. The sensor of claim 4, said plurality of different set point temperatures being below the Curie temperature of the element.

6. The sensor of claim 1, said magnetic element comprising a metallic body.

7. The sensor of claim 6, said metallic body being amorphous.

8. The sensor of claim 6, said metallic body being nanocrystalline.

9. The sensor of claim 6, said metallic body being in the form of an elongated wire or thin strip having a maximum cross-sectional dimension of up to about 100 μ

m.

10. The sensor of claim 6, said metallic body formed of an alloy selected from the group consisting from Fe-based alloys, Co-based alloys, and mixtures thereof.

11. The sensor of claim 10, said alloy having chromium therein.

12. The sensor of claim 1, said element comprising a metallic body with a glass coating surrounding the body.

13. The sensor of claim 1, said element comprising a metallic body, there being a ferromagnetic sheath adjacent said metallic body.

14. The sensor of claim 13, said sheath surrounding said metallic body.

15. The sensor of claim 13, said sheath disposed at least partially about said metallic body in spaced relationship thereto.

16. The sensor of claim 1, said element comprising a metallic body having a coercivity less than 10 A/m, a relative magnetic permeability above 20,000, a magnetostriction substantially 0 or of slightly positive value, and a large Barkhausen discontinuity.

17. The sensor of claim 13, said element comprising a metallic body producing a characteristic re-magnetization pulse above the Curie temperature of said adjacent ferromagnetic sheath, and producing no re-magnetization pulse, or an altered re-magnetization pulse, at one or more temperatures below the Curie temperature of the adjacent ferromagnetic sheath.

18. A temperature sensor operable to sense the temperature of an object and comprising:

a plurality of individual microwires each including an elongated metallic body having a maximum cross-sectional dimension of up to about 100 μ

m and having a re-magnetization response under the influence of an applied alternating magnetic field, the re-magnetization response of each metallic body being different below and above the Curie temperature of the corresponding metallic body; and

at least one thermally conductive substrate supporting said microwires and configured to be placed in thermal contact with said object.

19. The sensor of claim 18, at least certain of said metallic bodies having different re-magnetization responses above and below a plurality of different set point temperatures below the Curie temperatures thereof.

20. The sensor of claim 18, including a magnetic field-responsive data element also supported on said substrate.

21. The sensor of claim 18, said plurality of microwires including an array of composite microwires, each of said composite microwires including a ferromagnetic sheath surrounding said metallic body.

22. The sensor of claim 18, said plurality of microwires including an array of combination microwires, each of said combination microwires including a ferromagnetic sheath disposed adjacent and in spaced relationship to said metallic body.

23. The sensor of claim 18, at least certain of said metallic bodies being amorphous.

24. The sensor of claim 18, at least of certain of said metallic bodies being nanocrystalline.

25. The sensor of claim 18, said metallic bodies being in the form of elongated wires or thin strips having a maximum cross-sectional dimension of up to about 100 μ

m.

26. The sensor of claim 18, said metallic bodies formed of an alloy selected from the group consisting from Fe-based alloys, Co-based alloys, and mixtures thereof.

27. The sensor of claim 25, said alloy having chromium therein.

28. The sensor of claim 18, said metallic bodies of said microwires having different Curie temperatures in successive order from lowest Curie temperature to highest Curie temperature.

29. An elongated microwire comprising an elongated amorphous or nanocrystalline metallic alloy body having a Curie temperature of up to about 400°

C. and a glass coating surrounding the metallic alloy body.

30. The microwire of claim 29, said metallic alloy body being in the form of an elongated wire or thin strip having a maximum cross-sectional dimension of up to about 100 μ

m.

31. The microwire of claim 29, said metallic alloy body formed of an alloy selected from the group consisting from Fe-based alloys, Co-based alloys, and mixtures thereof.

32. The microwire of claim 31, said alloy having chromium therein.

33. A method of sensing the temperature of an object, comprising the steps of:

placing a temperature sensor in thermal contact with said object, said sensor comprising at least one magnetically susceptible sensor element having a re-magnetization response under the influence of an applied alternating magnetic field, said re-magnetization response being different below and above at least one set point temperature below about 400°

C.;

generating an alternating magnetic field in the region of said sensor and of sufficient magnitude to cause said re-magnetization response of said sensor element; and

detecting the re-magnetization response of said sensor element, and using said detected response to at least in part determine whether the temperature of said object is above or below said set point temperature.

34. The method of claim 33, said sensor having a plurality of magnetically susceptible sensor elements each having a different re-magnetization response under the influence of an applied alternating magnetic field and each re-magnetization response being different below a different set point temperature, and using said different re-magnetization responses to determine the temperature of said object.

35. The method of claim 33, said detecting step comprising the steps of using a field receiving coil to detect said re-magnetization response and to generate output signal corresponding to said detected re-magnetization response.

36. The method of claim 35, including the step of using a signal processing unit operably coupled with said field receiving coil to receive said output signal and to determine therefrom at least the approximate temperature of said object.

37. The method of claim 34, said different set points being in sequence from a lowest set point or set point range to a highest set point or set point range.

38. The method of claim 33, said sensor element including a metallic body having a Curie temperature, said set point temperature being said Curie temperature.

39. The method of claim 33, said sensor element including a metallic body having a Curie temperature with a ferromagnetic sheath adjacent said metallic body, said ferromagnetic sheath having a Curie temperature below the Curie temperature of the adjacent metallic body, said method including the step of preventing said re-magnetization response of said body until said object reaches a temperature above said sheath Curie temperature, or some fixed temperature near said sheath Curie temperature.

40. The method of claim 33, said sensor element including a metallic body having a Curie temperature with a ferromagnetic sheath adjacent said metallic body, said ferromagnetic sheath having a Curie temperature below the Curie temperature of the adjacent metallic body, said method including the step of altering said re-magnetization response of said body when said object has a temperature below said sheath Curie temperature, or some temperature near said sheath Curie temperature.

41. The method of claim 33, said object comprising a pair of components designed to be placed in proximity to each other to for the object, with one of said components being heatable, said method comprising the steps of placing said temperature sensor in thermal contact with said heatable component, and associating with the other component a magnetic field-responsive data element correlated with said temperature sensor such that correct temperature of said temperature sensor can only be determined if both the temperature sensor and data element are simultaneously subjected to said generated alternating magnetic field.

42. The method of claim 41, said data component comprising at least one microwire including an elongated metallic body having a re-magnetization response under the influence of said generated alternating magnetic field, said method including the step of detecting the re-magnetization response of said data element along with the re-magnetization response of said temperature sensor.

43. The method of claim 33, said sensor element having re-magnetization responses above and below a plurality of different set point temperatures, said detecting step comprising the steps of detecting at least some of the re-magnetization responses, and using the detecting re-magnetization responses to determine the temperature of said body.

44. The method of claim 43, said plurality of different set point temperatures being below the Curie temperature of the element.

45. The method of claim 43, said step of determining the temperature of said body comprising the steps of determining said temperature within a range of temperatures.

46. The combination comprising:

a temperature sensor operable for sensing the temperature of an object and comprising at least one magnetically susceptible sensor element having a re-magnetization response under the influence of an applied alternating magnetic field, said re-magnetization response being different below and above a set point temperature; and

a detector including a device for generating an alternating magnetic field of sufficient magnitude to cause said re-magnetization response of said sensor element, and a device for detecting said re-magnetization response.

47. The combination of claim 46, said detecting device operable to generate on output signal correlated with said re-magnetization response, said detector including a signal processing unit operably coupled with said detecting device to receive said output signal and to determine therefrom at least the approximate temperature of said body.

48. A system for heating an object, comprising:

a temperature sensor designed for placement in thermal contact with said object and operable for sensing the temperature of said object, said sensor comprising at least one magnetically susceptible sensor element having a re-magnetization response under the influence of an applied alternating magnetic field, said re-magnetization response being different below and above a set point temperature;

apparatus for heating said object;

a detector including a device operable to generate said alternating magnetic field, and a device operable to detect said re-magnetization response and to generate an output signal correlated with said detected re-magnetization response; and

a controller coupled with said detector and said heating apparatus and operable to receive said output signal and to control the operation of said heating apparatus in response to the output signal.

49. The system of claim 48, said heating apparatus comprising an induction heating unit.

50. A temperature sensor configured to be placed in thermal contact with an object in order to sense the temperature of the object, said sensor comprising:

at least one metallic body having a re-magnetization response under the influence of an applied alternating magnetic field, said re-magnetization response defined by at least one short, detectible pulse of magnetic field perturbation of defined duration; and

a ferromagnetic sheath adjacent said metallic body and having a Curie temperature, said sheath operable to prevent or alter said re-magnetization response of said metallic body until said sheath reaches a temperature close to said Curie temperature thereof.

51. The temperature sensor of claim 50, said metallic body being a part of a microwire.

52. The temperature sensor of claim 50, said metallic body being amorphous or nanocrystalline.

53. The temperature sensor of claim 50, said sheath Curie temperature below about 400°

C.

54. The temperature sensor of claim 50, said ferromagnetic sheath surrounding said metallic body.

55. The temperature sensor of claim 50, said ferromagnetic sheath disposed at least partially about said metallic body and spaced therefrom.

56. The temperature sensor of claim 50, said metallic body being in the form of an elongated wire or thin strip having a maximum cross-sectional dimension of up to about 100 μ

m.

57. The sensor of claim 50, said metallic body formed of an alloy selected from the group consisting from Fe-based alloys, Co-based alloys, and mixtures thereof.

58. The sensor of claim 57, said alloy having chromium therein.

59. The sensor of claim 50, said metallic body having a coercivity less than 10 A/m, a relative magnetic permeability above 20,000, a magnetostriction substantially 0 or of slightly positive value, and a large Barkhausen discontinuity.

60. The sensor of claim 50, including a plurality of said temperature sensors and wherein the ferromagnetic sheath of each of said plurality of sensors has a different Curie temperature.

61. The sensor of claim 60, said ferromagnetic sheaths of said plural temperature sensors having different Curie temperature from in successive order from lowest Curie temperature to highest Curie temperature.