Linear variable differential transformer (LVDT) calibration mechanism for precision rigging with vibration and accuracy tracking robustness

Patent metadata

Field	Value
Publication number	US-10782156-B2
Application number	US-201916279773-A
Country	US
Kind code	B2
Filing date	Feb 19, 2019
Priority date	Mar 1, 2017
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

Embodiments generally relate to assembly and methods for precisely rigging a linear variable differential transformer (LVDT). For example, the probe rod assembly of a dual tandem LVDT may comprise two moveable cores, a probe fitting, and a probe rod. Generally, the first moveable core may be configured to achieve electrical zero with its respective transformer. Without adjusting the position of the probe rod with respect to the one or more coils of wire, the second moveable core may be configured to achieve electrical zero with its respective transformer. This may ensure that both moveable cores simultaneously achieve electrical zero in the null position. Typically, the probe fitting may be configured to fit at a first end of the probe rod projecting outward from the outer housing. The disclosed assembly and methods may be used to precisely rig dual tandem LVDTs, single channel LVDTs, and dual parallel LVDTs.

First claim

What is claimed is:

1. A method for calibrating a linear variable differential transformer (LVDT), the method comprising:
fixedly coupling a first moveable core on a probe rod;
inserting the probe rod with the first moveable core into a housing comprising one or more coils of wire, wherein the one or more coils of wire are arranged to form a plurality of transformers;
aligning a position of the first moveable core with respect to a first transformer of the plurality of transformers;
adjusting a position of a probe fitting on the probe rod with respect to the aligning of the position of the first moveable core to the first transformer of the plurality of transformers;
fixedly coupling the probe fitting to the probe rod; and
adjusting a second moveable core on the probe rod, wherein the second moveable core is adjacent to a spacer of one or more spacers coupled to a first end of the probe rod.

2. The method of claim 1 , further comprising aligning a position of the second moveable core with respect to a second transformer of the plurality of transformers.

3. The method of claim 2 , wherein aligning the position of the second moveable core is based on aligning of the position of the first moveable core with respect to the first transformer.

4. The method of claim 2 , wherein alignment of the second moveable core within the second transformer comprises sliding the second moveable core until electrical zero is achieved with respect to the second transformer.

5. The method of claim 2 , further comprising fixedly coupling the second moveable core to the probe rod after aligning the position of the second moveable core relative to a second transformer of the plurality of transformers.

6. The method of claim 2 , wherein when both the first moveable core and the second moveable core achieve electrical zero with respect to their respective transformers, a difference between an output signal of the first transformer and an output signal of the second transformer is less than an acceptable threshold level.

7. The method of claim 6 , further comprising:
calculating a deviation from the acceptable threshold level in case the difference between the output signal of the first transformer and the output signal of the second transformer is greater than the acceptable threshold level, and
adjusting the position of the first moveable core, the second moveable core, or the probe fitting based on the calculated deviation.

8. The method of claim 6 , wherein an average of an output signal from the first transformer and an average of an output signal from the second transformer is less than an acceptable deviation from electrical zero.

9. The method of claim 8 , further comprising adjusting the position of the first moveable core, the second moveable core, or the probe fitting in case the output signal from the first transformer and the output signal from the second transformer is greater than the acceptable deviation from electrical zero.

10. The method of claim 1 , wherein fixedly coupling the second moveable to the probe rod comprises at least one of: welding, brazing, crimping, adhesive, threading, or combinations thereof.

11. The method of claim 1 , wherein the LVDT comprises a dual tandem LVDT.

12. The method of claim 1 , wherein at least one end of the first moveable core and the second moveable core is permanently attached to the probe rod.

13. The method of claim 1 , wherein inserting the probe rod into the housing comprises moving the probe rod into the housing until a current clamp is met.

14. The method of claim 1 , wherein alignment of the first moveable core within the first transformer comprises sliding the first moveable core until electrical zero is achieved with respect to the first transformer.

15. The method of claim 1 , wherein the one or more spacers are configured to be disposed on the probe rod on either side of the first moveable core and the second moveable core.

16. A method for calibrating a linear variable differential transformer (LVDT), the method comprising:
fixedly coupling a first moveable core onto a probe rod,
inserting the probe rod with the first moveable core into a housing comprising one or more coils of wire, wherein the one or more coils of wire are arranged to form a plurality of transformers;
aligning a position of the first moveable core with respect to a first transformer of the plurality of transformers;
adjusting a position of a probe fitting on the probe rod with respect to the aligning of the position of the first moveable core to the first transformer of the plurality of transformers;
fixedly coupling the probe fitting to the probe rod;
adjusting a second moveable core on the probe rod;
aligning a position of the second moveable core with respect to a second transformer of the plurality of transformers based on the aligning of the position of the first moveable core to the first transformer; and
fixedly coupling the second moveable core to the probe rod after aligning the second moveable core relative to the second transformer.

17. The method of claim 16 , wherein fixedly coupling the first moveable core, the second moveable core, and the probe fitting to the probe rod comprises at least one of: welding, brazing, crimping, adhesive, threading, or combinations thereof.

18. The method of claim 16 , wherein alignment of the first moveable core within the first transformer and alignment of the second moveable core within the second transformer comprises sliding the first moveable core and the second moveable core until electrical zero is achieved with respect to the first transformer and the second transformer, respectively.

19. The method of claim 18 , wherein when both the first moveable core and the second moveable core achieve electrical zero with respect to their respective transformers, a difference between an output signal of the first transformer and an output signal of the second transformer is less than an acceptable threshold level.

20. The method of claim 19 , wherein when the difference between the output signal of the first transformer and the output signal of the second transformer is greater than the acceptable threshold level, a deviation from the acceptable threshold level is calculated, and the position of the first moveable core, the second moveable core, or the probe fitting is adjusted accordingly.

21. The method of claim 18 , wherein an average of the output signal from the first transformer and an average of the output signal from the second transformer is less than an acceptable deviation from electrical zero.

22. The method of claim 21 , wherein when the output signal from the first transformer and the output signal from the second transformer is greater than the acceptable deviation from electrical zero, the position of the first moveable core, the second moveable core, or the probe fitting is adjusted on the probe rod accordingly.

23. The method of claim 16 , further comprising one or more spacers, wherein the one or more spacers are configured to be disposed on the probe rod on either side of the first moveable core and the second moveable core.

24. The method of claim 23 , wherein one of the spacers is a threaded end spacer, wherein the threaded end spacer is located at opposite end of the probe rod from the probe fitting, and wherein the threaded end spacer comprises flats along half of the diameter to allow for adjustment along the length of the probe rod.

Assignees

• Honeywell Int Inc

Inventors

• Daniels Aaron
• Walling Joe
• Licata Charles

Classifications

• G01D18/00

  Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00 · CPC title

• G01D5/2291 Primary

  Linear or rotary variable differential transformers (LVDTs/RVDTs) having a single primary coil and two secondary coils · CPC title