Temperature sensor
A temperature sensor includes a plastic bottom shell, a plastic cap mating the plastic shell, and a temperature responsive element mounted to the plastic cap and received in a cavity of the plastic bottom shell. The temperature responsive element is positioned in the plastic bottom shell by the cap. An insulating coating is applied to the temperature responsive element. The insulating coating and the plastic bottom shell provide dual electrical insulation for the temperature responsive element.
1. A temperature sensor comprising:
a top connector made from a dielectric material and including a connector portion having an outer wall with a shoulder, and a hollow extension portion extending from the connector portion and comprising a proximal end open to an ambient environment and a distal end closed by a thin wall;
a bottom shell portion made from a dielectric material and including an upper surface having an aperture leading to a cavity and a ledge adjacent to the aperture and cavity;
a temperature responsive element attached to the top connector disposed in the cavity and abutting the distal end of the extension portion; and
a curable dielectric material disposed in the cavity and surrounding the temperature responsive element.
2. The temperature sensor of claim 1 , further comprising:
first and second leads located on opposite sides of the temperature responsive element that are connected, respectively, to first and second terminals;
the first and second terminals being received, respectively, in first and second slots in the top connector located adjacent to the extension portion; and
wherein the temperature responsive element is a temperature sensitive resistor.
3. The temperature sensor of claim 1 , wherein at least a portion of the wall thickness of the bottom shell is substantially 1 mm.
4. The temperature sensor of claim 1 , wherein the curable dielectric material is an epoxy having additives that increase a thermal conductivity of the epoxy.
5. The temperature sensor of claim 1 , wherein the distal end of the extension portion is operable to rupture upon a catastrophic failure of the temperature responsive element.
6. The temperature sensor of claim 1 , wherein the top connector and the bottom shell portion comprise a molded plastic.
7. The temperature sensor of claim 6 , wherein the plastic is polypropylene.
8. The temperature sensor of claim 1 , wherein the temperature responsive element is substantially centered in the cavity.
9. The temperature sensor of claim 8 , wherein the curable dielectric material substantially fills the space between the temperature responsive element and an inner wall of the cavity.
10. A temperature sensor comprising:
a housing comprising a top connector and a bottom shell, each extending along a longitudinal axis;
the top connector comprising a terminal connector portion, an extension portion, a cylindrical portion and a shoulder;
the terminal connector portion being located at an upper end of the top connector;
the extension portion projecting from a lower end of the terminal connector portion along the longitudinal axis and having a proximal end to a distal end, the proximal end being closest to the upper end and the distal end being furthest from the upper end, the extension portion comprising a hollow post closed at the distal end and open at the proximal end;
the cylindrical portion located adjacent to the terminal connector portion;
the shoulder being formed by an outer wall of the terminal connector portion and the cylindrical portion;
the bottom shell comprising a surface at an upper end of the bottom shell, a first aperture in the surface, a ledge adjacent to the first aperture on a side opposite the surface, and a second aperture adjacent to the ledge, and an interior cavity at a lower end of the bottom shell, the bottom shell having a generally uniform, thin-walled structure at the lower end of the bottom shell;
a terminal assembly comprising a temperature responsive element disposed within the cavity and a plurality of terminals received in respective slots located at the lower end of the in the terminal connector portion; and
a curable dielectric material disposed in the cavity and surrounding the temperature responsive element;
wherein the shoulder of the top connector is positioned to abut the ledge of the bottom shell;
wherein the temperature responsive element is positioned to abut the distal end of the extension portion.
11. The temperature sensor of claim 10 wherein the distal end of the extension portion is operable to rupture in the event of a catastrophic failure of the temperature responsive element.
12. The temperature sensor of claim 10 wherein the bottom shell further comprises an inner surface adjacent to the cylindrical portion of the top connector.
13. The temperature sensor of claim 10 wherein the slots are located adjacent to the extension portion; and
wherein the terminals pass through an open end of the cylindrical portion and are received in respective ones of the slots.
14. The temperature sensor of claim 10 wherein the distal end of the extension portion conforms to the shape of the temperature responsive element.
15. A temperature sensor comprising:
a housing comprising a top connector and a bottom shell, the bottom shell comprising a cavity having inner walls;
a terminal subassembly comprising a temperature responsive element and a pair of current conducting terminals electrically connected to the temperature responsive element by current conducting leads located on opposite sides of the temperature responsive element;
wherein the top connector and terminal subassembly comprise means for locating the temperature responsive element relative to the top connector; and
wherein the top connector and the bottom shell comprise means for locating the top connector relative to the bottom shell so that the temperature responsive element is located in the cavity a substantially equal distance from the inner walls of the cavity.
16. The temperature sensor of claim 15 wherein the top connector comprises an extension portion having a distal end that conforms to a shape of the temperature responsive element and abuts the temperature responsive element and is operable to rupture in the event of a catastrophic failure of the temperature responsive element to provide a venting path to the ambient environment through the extension portion.