Method and apparatus for in situ calibration of a thermometer

Patent metadata

Field	Value
Publication number	US-10794775-B2
Application number	US-201615748504-A
Country	US
Kind code	B2
Filing date	Jun 28, 2016
Priority date	Jul 29, 2015
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

An apparatus for determining and/or monitoring temperature of a medium, comprising at least one temperature sensor and at least two reference elements for in situ calibration and/or validation of the temperature sensor, wherein the first reference element is composed at least partially of a first material, in the case of which at least one phase transition of at least second order occurs at least a first predetermined phase transition temperature in the temperature range relevant for calibration of the temperature sensor, wherein the second reference element is composed at least partially of a second material, in the case of which at least one phase transition of at least second order occurs at least a second predetermined phase transition temperature in the range relevant for calibration of the temperature sensor, and wherein the at least two reference elements are contacted via exactly two connection wires.

First claim

The invention claimed is:

1. An apparatus for determining and/or monitoring a temperature of a medium, comprising:
at least one temperature sensor; and
at least two reference element for in situ calibration and/or validation of the at least one temperature sensor,
wherein a first reference element is composed at least partially of a first material having at least one phase transition of at least second order at at least a first predetermined phase transition temperature in a temperature range relevant for the calibration of the at least one temperature sensor, and
wherein a second reference element is composed at least partially of a second material having at least one phase transition of at least second order at at least a second predetermined phase transition temperature in the range relevant for calibration of the at least one temperature sensor, and
wherein the at least two reference elements are arranged along a horizontal axis, side-by-side in the form of a total reference element, wherein said total reference element is provided at least in part with an electrically conductive coating in the area of at least one lateral surface or in the area of two opposite lateral surfaces parallel to the imaginary horizontal axis such that the coating covers each of the at least two reference elements at least in part, and the total reference element is contacted via exactly two connecting wires.

2. The apparatus as claimed in claim 1 , wherein at least the first material or the second material is a ferroelectric material or a ferromagnetic material.

3. The apparatus as claimed in claim 1 , wherein at least one phase transition in the first material or the second material causes a change of crystal structure and/or a volume change and/or an abrupt change of dielectric or electrical properties of the material.

4. The apparatus as claimed in claim 2 , wherein at least one phase transition in the first material or the second material is accompanied by a change from a paramagnetic to a ferromagnetic, from a ferromagnetic to a paramagnetic, from a ferroelectric to a paraelectric and/or from a paraelectric to a ferroelectric state.

5. The apparatus as claimed in claim 1 , wherein the temperature sensor and the at least two reference elements are arranged in a single sensor head.

6. The apparatus as claimed in claim 1 , wherein the at least two reference elements are generally strip-shaped and are disposed along an imaginary horizontal axis next to one another, the at least two reference elements forming a total reference element, the apparatus further comprising:
a first electrically conductive, coating at least partially covering a first face of the total reference element that is parallel to the imaginary horizontal axis and contacting each of the at least two reference elements.

7. The apparatus as claimed in claim 1 , wherein the total reference element and temperature sensor are disposed directly next to one another or on top of one another,
wherein the first face of the total reference element is smaller than a first face of the temperature sensor facing the total reference element and bordering on the total reference element,
wherein a first connection wire for contacting the total reference element is attached in the region of the first face of the total reference element and a second connection wire is attached to the first face of the temperature sensor.

8. The apparatus as claimed in claim 1 , the apparatus further comprising a second electrically conductive coating at least partially covering the first face of the total reference element and contacting each of the at least two reference elements,
wherein the first electrically conductive coating and the second electrically conductive coating are insulated from one another by an electrically insulating dividing layer.

9. The apparatus as claimed in claim 1 , wherein at least the first predetermined phase transition temperature and the second predetermined phase transition temperature differ by at least 1K.

10. A method for in situ calibration of a temperature monitoring apparatus, comprising:
providing the temperature monitoring apparatus, including:
at least one temperature sensor; and
at least two reference elements for in situ calibration and/or validation of the at least

one temperature sensor,
wherein a first reference element is composed at least partially of a first material having at least one phase transition of at least second order at at least a first predetermined

phase transition temperature in a temperature range relevant for the calibration of the at least one temperature sensor, and
wherein a second reference element is composed at least partially of a second material having at least one phase transition of at least second order at at least a second predetermined phase transition temperature in the range relevant for calibration of the at least one temperature sensor, and

wherein the at least two reference elements are arranged along a horizontal axis, side-by-side in the form of a total reference element, wherein said total reference element is provided at least in part with an electrically conductive coating in the area of at least one lateral surface or in the area of two opposite lateral surfaces parallel to the imaginary horizontal axis such that the coating covers each of the at least two reference elements at least in part, and the total reference element is contacted via exactly two connecting wires,
ascertaining at least one phase transition point in time at which at least one phase transition temperature is achieved for at least one of the at least two reference elements;
ascertaining a temperature measured value measured using the temperature sensor at a measuring point in time which has the shortest time separation from the phase transition point in time; and
calibrating the temperature sensor based on a comparison of the at least one phase transition temperature with the temperature measured value.

11. The method as claimed in claim 10 , wherein the at least one phase transition point in time is ascertained based on a change of crystal structure and/or a volume change and/or a change of dielectric or electrical properties of at least one material of at least one of the at least two reference elements.

12. The method as claimed in claim 11 wherein the temperature measured values ascertained using the temperature sensor and/or the change of crystal structure and/or the volume change and/or the change of dielectric or electrical properties of the at least one material are recorded as a function of time.

13. The method as claimed in claim 12 , further comprising:
detecting which of the at least two reference elements passed through a phase transition based on a comparison of the phase transition temperature with a temperature measured value measured essentially at the same time.

14. The method as claimed in claim 10 , wherein the temperature sensor and the at least two reference elements are exposed to the same ambient temperature.

15. The method as claimed in claim 10 , further comprising:
heating or cooling the apparatus to induce the phase transition.

Assignees

• Endress Hauser Wetzer Gmbh Co Kg

Inventors

• Umkehrer Alfred
• Vrdoljak Pavo

Classifications

• G01K15/002

  Calibrated temperature sources, temperature standards therefor (arrangements with respect to the cold junction of thermo-electric elements G01K7/12) · CPC title

• G01K7/38

  the variations of temperature influencing the magnetic permeability · CPC title

• G01K15/005 Primary

  Calibration · CPC title

• G01K11/00

  Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 · CPC title