CRYOGENIC TEMPERATURE MEASURING RESISTOR ELEMENT

• US 20150211942A1
• Filed: 10/19/2012
• Published: 07/30/2015
• Est. Priority Date: 10/19/2012
• Status: Active Grant

• Current Assignee: Okazaki Manufacturing Company
• Original Assignee: Okazaki Manufacturing Company
• Inventors: Mihara, Takashi, Saraie, Shinichiro, Ito, Koichi
• Granted Patent: US 9,464,947 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C03B 19/09 by fusing powdered glass in a shaping mould
• CPC Class Codes: G01K 13/006 for cryogenic purposes
• CPC Class Codes: G01K 2203/00 Application of thermometers in cryogenics
• CPC Class Codes: G01K 7/06 the thermoelectric materials being arranged one within the other with the junction at one end exposed to the object, e.g. sheathed type
• CPC Class Codes: G01K 7/16 using resistive elements resistive elements per se H01C, H01L
• CPC Class Codes: G01K 7/183 characterised by the use of the resistive element
• CPC Class Codes: H01C 7/04 having negative temperature coefficient thermometers using resistive elements G01K7/16

Abstract

Provided is a cryogenic temperature measuring resistor element including a metallic temperature measuring resistor wire, an electric insulator made of a polycrystalline ceramic material, and a filler filled between the electric insulator and the temperature measuring resistor wire. The filler includes polycrystalline inorganic electric insulating powder, particles of the insulating powder being connected by glass. The glass has a lower softening point than respective melting points of the inorganic electric insulating powder, the temperature measuring resistor wire, and the electric insulator.

Claims

1. A cryogenic temperature measuring resistor element, comprising a temperature measuring resistor wire, a housing for accommodating the temperature measuring resistor wire in an interior thereof, and a filler filled between the housing and the temperature measuring resistor wire,

wherein the filler includes a mixture of polycrystalline inorganic electric insulating powder and glass powder of an amorphous electric insulating material having a lower softening point than respective melting temperatures of the inorganic electric insulating powder, the temperature measuring resistor wire, and the housing, and

the mixture having been filled between the housing and the temperature measuring resistor wire, and been heated at a temperature higher than the softening point of the glass powder and lower than the respective melting temperatures of the temperature measuring resistor wire, the housing, and the inorganic electric insulating powder so as to melt only the glass powder, and been cooled to thereby solidify the glass.

2. The cryogenic temperature measuring resistor element according to claim 1, wherein the temperature measuring resistor wire is made of an alloy of platinum and cobalt, and has the shape of a coil.

3. The cryogenic temperature measuring resistor element according to claim 2, wherein the alloy of platinum and cobalt contains 0.5 mol % of cobalt, and

the temperature at which the glass powder is melted is 460°

C. or higher and 520°

C. or lower, and 50°

C. or more higher than the softening point of the glass powder.

4. The cryogenic temperature measuring resistor element according to claim 3, wherein the inorganic electric insulating powder includes alumina powder,

the glass powder includes bismuth oxide as a main component, zinc oxide and boron oxide, and

a mixing ratio of the glass powder to the filler is within a range of 3.5 wt % to 10.0 wt %.

5. The cryogenic temperature measuring resistor element according to claim 1, further comprising a lead wire connected to the opposite ends of the temperature measuring resistor wire,

wherein the housing includes an electric insulator in the shape of a cylinder having a substantially circular cross-section, and including two through holes in an axial direction,

the temperature measuring resistor wire extends through the through holes, the opposite ends exposing from end portions of the through holes, the end portions being on the same side of the through holes, and

the filler is in a gap between the inner wall of the through holes and the temperature measuring resistor wire.

6. The cryogenic temperature measuring resistor element according to claim 5, further comprising a sealer of an electric insulating material for sealing the respective opposite end portions of the through holes.

7. A cryogenic temperature measuring resistor element, comprising a temperature measuring resistor wire, a housing for accommodating the temperature measuring resistor wire, and filler filled between the housing and the temperature measuring resistor wire,

the filler including polycrystalline inorganic electric insulating powder, particles of the polycrystalline inorganic electric insulating powder being connected with one another by glass.

8. The cryogenic temperature measuring resistor element according to claim 7, wherein the glass is made of an amorphous electric insulating material having a lower softening point than respective melting temperatures of the inorganic electric insulating powder, the temperature measuring resistor wire, and the housing.

9. The cryogenic temperature measuring resistor element according to claim 8, wherein the temperature measuring resistor wire is made of an alloy of platinum and cobalt, and has the shape of a coil.

10. The cryogenic temperature measuring resistor element according to claim 9, wherein the alloy of platinum and cobalt contains 0.5 mol % of cobalt, and the temperature at which the glass is melted is 460 C or higher and 520 C or lower, and 50 C or more higher than the softening point of the glass powder.

11. The cryogenic temperature measuring resistor element according to claim 10, wherein the inorganic electric insulating powder includes alumina powder, the glass includes bismuth oxide as a main component, zinc oxide and boron oxide, and a mixing ratio of the glass to the filler is within a range of 3.5 wt % to 10.0 wt %.

12. The cryogenic temperature measuring resistor element according to claim 7, further comprising a lead wire connected to the opposite ends of the temperature measuring resistor wire,

wherein the housing includes an electric insulator in the shape of a cylinder having a substantially circular cross-section, and including two through holes in an axial direction,

the temperature measuring resistor wire extends through the through holes, the opposite ends exposing from end portions of the through holes, the end portions being on the same side of the through holes, and

the filler is in a gap between the inner wall of the through holes and the temperature measuring resistor wire.

13. The cryogenic temperature measuring resistor element according to claim 12, further comprising a sealer of an electric insulating material for sealing the respective opposite end portions of the through holes.

14. A method for producing a cryogenic temperature measuring resistor element, comprising the steps of:

preparing a temperature measuring resistor wire and a housing for accommodating the temperature measuring resistor wire;

preparing a mixture of polycrystalline inorganic electric insulating powder and glass powder of an amorphous electric insulating material with each other, the glass powder having a lower softening point than respective melting temperatures of the inorganic electric insulating powder, the temperature measuring resistor wire, and the housing;

filling the mixture between the housing and the temperature measuring resistor wire;

heating the mixture at a temperature higher than the softening point of the glass powder and lower than the respective melting temperatures of the temperature measuring resistor wire, the housing, and the inorganic electric insulating powder so as to melt only the glass powder; and

cooling the mixture so as to solidify the melted glass to connect particles of the inorganic electric insulating powder with one another.

15. The method according to claim 14, wherein the temperature measuring resistor wire is made of an alloy of platinum and cobalt, and has the shape of a coil.

16. The method according to claim 15, wherein the alloy of platinum and cobalt contains 0.5 mol % of cobalt, and

the temperature at which the glass powder is melted is 460 C or higher and 520 C or lower, and 50 C or more higher than the softening point of the glass powder.

17. The method according to claim 16, wherein the inorganic electric insulating powder includes alumina powder,

the glass powder includes bismuth oxide as a main component, zinc oxide and boron oxide, and

a mixing ratio of the glass powder to the filler is within a range of 3.5 wt % to 10.0 wt %.

18. The method according to claim 14, wherein the opposite ends of the temperature measuring resistor wire are connected with a lead wire,

wherein the housing includes an electric insulator in the shape of a cylinder having a substantially circular cross-section, and including two through holes in an axial direction,

the temperature measuring resistor wire extends through the through holes, the opposite ends exposing from end portions of the through holes, the end portions being on the same side of the through holes, and

the mixture is in a gap between the inner wall of the through holes and the temperature measuring resistor wire.

19. The method according to claim 18, wherein the opposite end portions of the through holes are sealed by a sealer of an electric insulating material.