Vibratory digital temperature sensor

• US 4,459,042 A
• Filed: 08/26/1983
• Issued: 07/10/1984
• Est. Priority Date: 11/28/1980
• Status: Expired due to Fees

• Current Assignee: Weigh-Tronix, Inc. (Illinois Tool Works Inc.)
• Original Assignee: Novex Corp. (Thermo Fisher Scientific Incorporated)
• Inventors: Paros, Jerome M.
• Primary Examiner(s): YASICH, DANIEL
• Application Number:
  US06/526,594
• Time in Patent Office: 319 Days
• Field of Search: 374/117, 374/118, 374/188, 73/702, 73/703, 73/704, 73/32 A, 73/DIG. 1, 310/361, 310/341, 310/9.5
• US Class Current: 374/117
• CPC Class Codes: G01K 7/32 using change of resonant frequency of a crystal
• CPC Class Codes: Y10S 73/01 Vibration

Abstract

A temperature sensor is formed by mounting a force-sensitive resonator on a resilient or non-resilient base structure, preferably in an enclosure such that thermally induced expansions or contractions of the base structure apply a stress to the resonator. The resonant frequency of the resonator is measured to provide an indication of the temperature of the base structure and resonator.

Claims

1. A temperature sensor comprising a load-sensitive resonator having a pair of spaced-apart mounts which are secured to a base which isolates said resonator from external forces, said base having a coefficient of thermal expansion which is different from that of said resonator such that said base applies a thermally induced stress to said resonator, said resonator having a resonant frequency that is dependent on the elastic properties of said resonator and the compression or tension applied to said resonator through said mounts so that said resonator is compressed and tensioned in accordance with the temperature of said resonator and base, thereby changing the resonant frequency of said resonator solely in accordance with changes in the temperature of said resonator and base.

2. A temperature sensor according to claim 1 wherein the resonator is a flexurally vibrating single beam extending between said mounts.

3. A temperature sensor according to claim 1 wherein the resonator is a closed-end tuning fork having a pair of tines extending between said mounts.

4. A temperature sensor according to claim 1 wherein the resonator is fabricated from quartz crystal.

5. A method of measuring temperature change, comprising:

exposing a temperature sensor to the temperature to be measured, said temperature sensor including a load-sensitive resonator having a pair of spaced-apart mounts secured to a temperature sensing member, said sensing member having a coefficient of thermal expansion which is different from that of said resonator such that the thermally induced stress applied to said resonator by said sensing member changes in accordance with said temperature change, said resonator having a resonant frequency that is dependent on the elastic properties of said resonator and the compressional or tensional stress applied to said resonator through said mounts so that said resonator is compressed or tensioned in accordance with the temperature of said resonator and said temperature sensing member, and

measuring the change in resonant frequency of said resonator due solely to said thermally induced stress, thereby providing an indication of said temperature change.

6. The method of claim 5 wherein said temperature sensing member is a base on which said resonator is mounted.