Self-verifying temperature sensor

• US 5,713,668 A
• Filed: 08/23/1996
• Issued: 02/03/1998
• Est. Priority Date: 08/23/1996
• Status: Expired due to Term

• Current Assignee: Accutru International
• Original Assignee: Accutru International
• Inventors: Brannon, C. Tom, Transier, Lee, Cannon, Collins P., Lunghofer, James G., Conner, Bernard L.
• Primary Examiner(s): Dombroske, George M.
• Assistant Examiner(s): AMROZOWICZ, PAUL DOUGLAS
• Application Number:
  US08/702,373
• Time in Patent Office: 529 Days
• Field of Search: 374/163, 374/178, 374/179, 374/180, 374/181, 374/183, 374/184, 374/185
• US Class Current: 374/179
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 7/00 Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat giving results other than momentary value of temperature G01K3/00 ; Power supply therefor, e.g. using thermoelectric elements

Abstract

A self-verifying temperature sensor and method for measuring and verifying the true thermodynamic temperature of a system. The sensor is constructed of various combinations of the following temperature-dependent elements: thermoelements, resistive elements, capacitive elements and other inductive elements. In the preferred embodiment, the sensor is constructed of resistive element connected between four thermoelement wires. A fifth thermoelement wire is connected to the resistive element. The sensor produces a data signature from various voltage, resistance, inductance, and capacitance measurements. Measurement electronics collect and condition the data signature. A computer analyzes the data signature and provides the system operator with a verified sensor temperature, thus, allowing the system operator to recognize and account for drift or decalibration of the sensor. The self-verifying temperature sensor can also be recalibrated insitu, thereby eliminating the necessity of sensor removal to verify recalibration.

Claims

1. A self-verifying temperature sensor, comprising:

a temperature-dependent element having a first end and a second end;

a first thermocouple coupled to the first end;

a second thermocouple coupled to the second end; and

a thermoelement coupled to the temperature-dependent element between the first and second ends.

2. The sensor of claim 1, further comprising:

a protection tube surrounding the temperature-dependent element, the first and second thermocouples, and the thermoelement; and

a spacer element within the protection tube and holding the temperature-dependent element, the first and second thermocouples, and the thermoelement in a fixed position.

3. The sensor of claim 1, wherein the temperature-dependent element is an impedance device.

4. The sensor of claim 3, wherein the impedance device is selected from the group consisting of:

a resistor, a capacitor, an inductor, a diode, a crystal, and a semiconductor.

5. The sensor of claim 1, wherein the first and second thermocouples each comprise:

a first thermoelement made from a first temperature-dependent material; and

a second thermoelement made from a second temperature-dependent material, wherein the second temperature-dependent material is different than the first temperature-dependent material.

6. The sensor of claim 5, wherein the first thermoelement is made from a nickel-chromium alloy.

7. The sensor of claim 5, wherein the second thermoelement is made from a nickel alloy.

8. The sensor of claim 5, wherein the first and second thermoelements are joined at a junction point and the junction point is coupled to the temperature-dependent element.