Temperature calibration device having reconfigurable heating/cooling modules to provide wide temperature range

• US 20070289314A1
• Filed: 06/14/2006
• Published: 12/20/2007
• Est. Priority Date: 06/14/2006
• Status: Active Grant

• Current Assignee: Fluke Corporation (Fortive Corp.)
• Original Assignee: Fluke Corporation (Fortive Corp.)
• Inventors: Liebmann, Frank E., Farley, David W., Walker, Richard W., Hirst, Michael W., Sjogren, Allen E.
• Granted Patent: US 7,607,309 B2
• Time in Patent Office: Days
• US Class Current: 62/3.300
• CPC Class Codes: F25B 21/04 reversible
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 15/005 Calibration

Abstract

A temperature calibration device uses Peltier cells for heating and cooling. The Peltier cells are connected to a relay that connects the cells to each other in one configuration for heating and a different configuration for cooling. The Peltier cells also receive supply voltages having different magnitudes and polarities for heating and cooling. By changing the manner in which the Peltier cells are connected to each other and using different supply voltages for heating and cooling, the cells are able to operate closer to their specified maximum temperature differential without sacrificing the useful life of the cells.

Claims

1. A method of operating a temperature calibration device having a plurality of Peltier cells to heat or cool a device to be calibrated, the method comprising:

connecting the plurality of Peltier cells to each other in a first configuration when the Peltier cells are to cool the device to be calibrated;

applying a first voltage having a first polarity to the Peltier cells that are in the first configuration when the Peltier cells are to cool the device to be calibrated;

connecting the plurality of Peltier cells to each other in a second configuration when the Peltier cells are to heat the device to be calibrated, the second configuration being different from the first configuration; and

applying a second voltage having a second polarity to the Peltier cells that are in the second configuration when the Peltier cells are to heat the device to be calibrated.

2. The method of claim 1 wherein the magnitude of the first voltage is different from the magnitude of the second voltage.

3. The method of claim 1 wherein a current flows through at least a first of the Peltier cells responsive to the first voltage when the Peltier cells are in the first configuration, the current having a magnitude that is different from the magnitude of a current flowing through the first of the Peltier cells responsive to the second voltage when the Peltier cells are in the second configuration.

4. The method of claim 1 wherein the act of connecting the plurality of Peltier cells to each other in a first configuration comprises connecting at least two of the Peltier cells in parallel with each other in the first configuration.

5. The method of claim 4 wherein the act of connecting the plurality of Peltier cells to each other in a first configuration comprises connecting at least two of the Peltier cells in series with the at least two Peltier cells in parallel with each other.

6. The method of claim 1 wherein the act of connecting the plurality of Peltier cells to each other in a second configuration comprises connecting all of the Peltier cells in series with each other in the second configuration.

7. The method of claim 1 wherein the act of connecting the plurality of Peltier cells to each other in a first configuration comprises:

connecting some of the Peltier cells to each other in a third configuration, the first voltage being applied to the Peltier cells in the third configuration; and

connecting the remaining Peltier cells to each other in a fourth configuration.

8. The method of claim 7 wherein a third voltage is applied to the Peltier cells that are connected to each other in the fourth configuration.

9. The method of claim 7 wherein the act of connecting the plurality of Peltier cells to each other in the third configuration comprises:

connecting at least two of the Peltier cells in parallel with each other; and

connecting the Peltier cells that are connected to each other in parallel in series with at least two other of the Peltier cells.

10. The method of claim 7 wherein the Peltier cells in the fourth configuration are isolated from the Peltier cells that are in the third configuration.

11. The method of claim 1 wherein the act of connecting the plurality of Peltier cells to each other in the second configuration comprises:

connecting some of the Peltier cells to each other in a third configuration, the second voltage being applied to the Peltier cells in the third configuration; and

connecting the remaining Peltier cells to each other in a fourth configuration.

12. The method of claim 7 wherein the Peltier cells in the fourth configuration are isolated from the Peltier cells that are in the third configuration.

13. The method of claim 1 wherein at least some of the Peltier cells in the first and second configurations are stacked on each other.

14. A temperature calibration device, comprising:

a block of thermally conductive material that is structured to be placed in thermal communication with a device to be calibrated;

a plurality of Peltier cells in thermal contact with the block of thermally conductive material;

a configurable connection device coupled to the Peltier cells, the configurable connection device being structured to connect the Peltier cells to each other in a first configuration responsive to a first control signal and to connect the Peltier cells to each other in a second configuration responsive to a second control signal, the second configuration being different from the first configuration;

a power supply structured to apply a first voltage to the Peltier cells responsive to the first control signal and to apply a second voltage to the Peltier cells responsive to the second control signal, the second voltage having a polarity that is different from the polarity of the first voltage; and

a control circuit coupled to the configurable connection device and the power supply, the control circuit being structured to apply the first control signal to the configurable connection device and the power supply when the device to be calibrated is to be cooled and to apply the second control signal to the configurable connection device and the power supply when the device to be calibrated is to be heated.

15. The temperature calibration device of claim 14 wherein the configurable connection device comprises a relay coupled to the Peltier cells.

16. The temperature calibration device of claim 14 wherein the plurality of Peltier cells a placed on each other in at least one stack Peltier cells having an inner Peltier cell placed on the block of thermally conductive material, a middle Peltier cell placed on the inner Peltier cell, and an outer Peltier cell placed on the middle Peltier cell.

17. The temperature calibration device of claim 16 wherein a first stack of the Peltier cells are placed on one side of the block of thermally conductive material and a second stack of the Peltier cells are placed on a side of the block of thermally conductive material opposite the side where the first stack of Peltier cells are placed.

18. The temperature calibration device of claim 17 wherein the first configuration of the Peltier cells comprises:

a parallel combination of the middle Peltier cells;

a series combination of the inner Peltier cells and the parallel combination of the middle Peltier cells; and

a series combination of the inner Peltier cells.

19. The temperature calibration device of claim 18 wherein the power supply is operable responsive to the first control signal to apply the first voltage to the series combination of the inner Peltier cells and the parallel combination of the middle Peltier cells, and the power supply is operable responsive to the first control signal to apply a third voltage to the series combination of the inner Peltier cells.

20. The temperature calibration device of claim 17 wherein the second configuration of the Peltier cells comprises:

a series combination of the inner Peltier cells and the middle Peltier cells; and

a series combination of the inner Peltier cells.

21. The temperature calibration device of claim 20 wherein the power supply is operable responsive to the second control signal to apply the second voltage to the series combination of the inner Peltier cells and the middle Peltier cells, and the power supply is operable responsive to the second control signal to apply a third voltage to the series combination of the inner Peltier cells.

22. The temperature calibration device of claim 14 wherein the power supply comprises a relay having a first contact receiving the first voltage, a second contact receiving the second voltage and a third contact connected to the Peltier cells, the relay being operable to connect the first contact to the third contact responsive to the first control signal, and to connect the second contact to the third contact responsive to the second control signal.

23. The temperature calibration device of claim 14 wherein first voltage has a magnitude that is different from a magnitude of the second voltage.

24. A temperature calibration device, comprising:

a block of thermally conductive material that is structured to be placed in thermal communication with a device to be calibrated;

a plurality of Peltier cells in thermal contact with the block of thermally conductive material;

a power supply structured to apply a first voltage to the Peltier cells responsive to a first control signal and to apply a second voltage to the Peltier cells responsive to a second control signal, the second voltage having a magnitude and polarity that is different from the first voltage; and

a control circuit coupled to the power supply, the control circuit being structured to apply the first control signal to the power supply when the device to be calibrated is to be cooled and to apply the second control signal to the power supply when the device to be calibrated is to be heated.

25. The temperature calibration device of claim 24 wherein the power supply comprises a relay having a first contact receiving the first voltage, a second contact receiving the second voltage and a third contact connected to the Peltier cells, the relay being operable to connect the first contact to the third contact responsive to the first control signal, and to connect the second contact to the third contact responsive to the second control signal.