THERMAL SENSING DEVICE

• US 3,614,345 A
• Filed: 11/17/1969
• Issued: 10/19/1971
• Est. Priority Date: 11/17/1969
• Status: Expired due to Term

• Current Assignee: Frederic R. Quinn
• Original Assignee: Frederic R. Quinn
• Inventors: Quinn, Frederic R.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US04/877,379
• Time in Patent Office: 701 Days
• Field of Search: 200/2 337/107 338/22A,23L,24L,22R,22SD,23,24 219/210
• US Class Current: 200/2
• CPC Class Codes: H01H 61/02 wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively

Abstract

The device is adapted to be used with an external circuit for controlling the operation of associated equipment and comprises sensing means the impedance of which varies in proportion to the ambient temperature. The sensing means is provided with leads to connect the same to the control circuit. In energy exchanging relationship with the sensing means is the heat producing portion of a heater; said heater having terminals for connection to the associated equipment so that the temperature of the heater varies in proportion to a parameter of the associated equipment. An enclosure receives the heat producing portion of the heater and the sensing means therein to concentrate the heat generated by the heater. Additionally, a housing surrounds the enclosure to insulate the enclosure from the external temperature.

Claims

1. A thermal sensing device comprising sensing means having an impedance which varies in accordance with its temperature, temperature varying means for varying the temperature of said sensing means, said temperature varying means having means for connecting said temperature varying means with an external device to be monitored whereby the temperature of said temperature varying means varies in accordance with a selected parameter of the external device, an enclosure receiving said temperature varying means and said sensing means therein with said temperature varying means in energy-Exchanging relationship with said sensing means, said sensing means including lead means for connecting said sensing means in a control circuit, and a coating of a material having a low thermal conductivity on the interior wall of said enclosure.

2. A sensing device as in claim 1, and a low thermal conductivity housing receiving said enclosure therein.

3. A sensing device as in claim 1, and, electrical insulating means having a one face in intimate engagement with said temperature varying means, and the opposite face in intimate engagement with said sensing means.

4. A sensing device as in claim 3, in which said electrical insulating means is fabricated from a material having a high thermal conductivity.

5. A sensing device as in claim 1, in which said sensing means has a characteristic such that the impedance of said sensing means changes rapidly at a preselected temperature.

6. A thermal sensing device for use with an external control circuit for controlling the operation of associated equipment comprising sensing means which varies in impedance in accordance with variations in the ambient temperature, said sensing means having leads adapted to be connected to the control circuit, a heater having a heat producing portion in energy-exchanging relationship with said sensing means, said heater having terminals for connection with the associated equipment whereby the temperature of said heater varies in proportion to a parameter of said associated equipment, an enclosure receiving at least the heat producing portion of said heater and said sensing means therein, and an insulating jacket surrounding said enclosure.

7. A thermal sensing device as in claim 6, and an electrically insulating high thermal conductivity material between said heater and said sensing means.

8. A thermal sensing device as in claim 6, in which said jacket comprises a cylindrical section receiving said enclosure therein, said heater terminals extending beyond the ends of said cylindrical section, a bushing on each end of said cylindrical section, said bushings having axial apertures each receiving respective terminal therethrough, whereby said enclosure is substantially axially located within said jacket.

9. A thermal sensing device as in claim 8, in which at least one of said bushings is provided with a through bore which receives the sensing means lead therethrough.

10. A thermal sensing device as in claim 6, and an electrically insulative material covering the interior of said enclosure.

11. A thermal sensing device as in claim 11, in which said enclosure comprises a tube, said heater extending longitudinally through said tube with said heat producing portion received within said tube, said tube having an open portion, and said sensing means extending through said open portion of said tube.

12. A sensing device as in claim 6, in which the impedance of said sensing means changes at a rapid rate when the ambient temperature reaches a preselected cycle.

13. A sensing device as in claim 6, in which the parameter of the associated equipment being monitored is a current produced by said associated equipment, lead means for connecting said heater terminals with said associated equipment, said heat producing portion of said heater having a smaller cross-sectional area than said terminals whereby the heat produced by said heater is concentrated in said heat producing portion.