Flexible averaging resistance temperature detector
A temperature sensor. The sensor comprises a wire comprising a resistance temperature detector (RTD) sensing material wrapped around a flexible insulated metal core wire to form an assembly. A first end of the sensing wire is electrically connected to a first end of the core wire. The second end of the core wire provides a first lead, and an insulated lead wire is electrically connected to a second end of the sensing wire to provide a second lead. Shrink tubing encapsulates the assembly.
1. A temperature sensor comprising:
a wire comprising a resistance temperature detector (RTD) sensing material wrapped in a plurality of adjacent windings around a flexible core wire to form distributed adjacent windings insulated from the core wire and including separation between adjacent windings to form a flexible assembly, the wire including a first end and a second end and the core wire including a first core end and a second core end, the first end electrically connected to the first core end, the second core end providing a first lead;
an insulated lead wire electrically connected to the second end of the wire to provide a second lead;
a first layer of heat shrinkable tubing encapsulating at least the first end and the first core end; and
a second layer of heat shrinkable tubing covering at least a portion of the first lead and second lead, wherein the first layer extends beyond the second layer.
2. The sensor of claim 1 , wherein the height of the sensor is about one-twentieth of an inch.
3. The temperature sensor of claim 2 , wherein the core wire includes braided strands of conductive metal.
4. The temperature sensor of claim 3 , wherein the core wire includes woven fiber glass insulation over the braided strands.
5. The temperature sensor of claim 4 , wherein the wire comprising a sensing material includes one, or a combination of platinum, nickel, a nickel-iron alloy, and copper.
6. The temperature sensor of claim 5 , wherein the electrical connections to the wires are made using soldering or brazing.
7. The temperature sensor of claim 6 , wherein the sensor further comprises a strain relieving banding strap over the core wire and the second lead wire.
8. The temperature sensor of claim 7 , wherein the banding strap includes brass.
9. The temperature sensor of claim 7 , wherein the banding strap includes steel.
10. The temperature sensor of claim 7 , wherein the banding strap is crimped around the core wire and the insulated lead wire.
11. The temperature sensor of claim 10 , wherein the first and second lead wires exit the sensor at the same end.
12. The temperature sensor of claim 11 , wherein an insulated lead wire is electrically connected to the second core end to provide the first lead.
13. The temperature sensor of claim 12 , wherein a second banding strap is placed around the first and second lead wires.
14. The temperature sensor of claim 12 , wherein the insulated wire leads withstand a five-pound pull force without separating from the assembly.
15. A temperature sensor produced by the method comprising:
wrapping a plurality of adjacent windings of a first wire comprising a resistance temperature detector (RTD) sensing material around a flexible core wire to form distributed adjacent windings insulated from the core wire and including separation between adjacent windings, creating a flexible wire wrapped assembly, the first wire including a first end and a second end and the core wire including a first core end and a second core end;
electrically connecting the first end to the first core end;
providing leads for the temperature sensor by electrically connecting a first insulated lead to the second end and using the second core end as a second lead of the temperature sensor;
placing the wire wrapped assembly into a heat shrinkable polymer material, including providing a first and second layer of heat shrinkable tubing, wherein the second layer extends beyond ends of the first layer; and
sealing at least the first end and the first core end of the temperature sensor by heating the polymer material.
16. The method of claim 15 , wherein providing leads includes electrically connecting a second insulated lead to the second core end.
17. The method of claim 16 , wherein the method further includes providing mechanical strain relief for the first and second leads.
18. The method of claim 15 , wherein the first layer is heated before the assembly is placed into the second layer.
19. The method of claim 15 , wherein electrically connecting to the sensing wire includes soldering or brazing.
20. A temperature sensor produced by the method comprising:
wrapping a first wire comprising a resistance temperature detector (RTD) sensing material around a flexible core wire, creating a wire wrapped assembly;
electrically connecting a first end to the first core end;
providing leads for the temperature sensor by electrically connecting a first insulated lead to the second end and using the second end as a second lead of the temperature sensor;
placing the wire wrapped assembly into a heat shrinkable polymer material, including providing a first and second layer of heat shrinkable tubing, wherein the second layer extends beyond ends of the first layer; and
sealing the temperature sensor by heating the polymer material.
21. The temperature sensor of claim 20 , wherein the first layer is heated before the assembly is placed into the second layer.