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

Patent metadata

Field	Value
Publication number	US-10247579-B2
Application number	US-201715446895-A
Country	US
Kind code	B2
Filing date	Mar 1, 2017
Priority date	Mar 1, 2017
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

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 linear variable differential transformer (LVDT) comprising:
an outer housing comprising one or more coils of wire, wherein the one or more coils of wire are arranged to form a plurality of transformers, and wherein each transformer of the plurality of transformers defines a channel;
a probe rod operable to fit within an opening in the outer housing and operable to move with respect to the outer housing;
a first moveable core and a second moveable core coupled to the probe rod, wherein the second moveable core is adjacent to an end spacer coupled to a first end of the probe rod; and
a probe fitting coupled to a second end of the probe rod, wherein the second end of the probe rod projects outward from the outer housing, wherein the first moveable core is coupled to the probe rod between the second moveable core and the probe fitting, and wherein the location of the second moveable core depends on the location of the probe fitting and the first moveable core.

2. The LVDT of claim 1 , wherein the LVDT comprises a first channel and a second channel, wherein the first moveable core is configured to achieve electrical zero with respect to the first channel, and wherein the second moveable core is configured to achieve electrical zero with respect to the second channel.

3. The LVDT of claim 1 , 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.

4. The LVDT of claim 3 , wherein the one or more spacers comprise a material compatible for welding to the probe rod, and wherein the one or more spacers comprise a friction element configured to form a friction fit to hold the two moveable cores to the probe rod.

5. The LVDT of claim 1 , wherein the probe fitting, the first moveable core, and the second moveable core are fixedly attached to the probe rod.

6. The LVDT of claim 5 , wherein the fixed attachment comprises at least one of: welding, brazing, crimping, adhesive, threading, or combinations thereof.

7. The LVDT of claim 1 , wherein the probe rod comprises a material with a coefficient of thermal expansion (CTE) matched to a CTE of the outer housing.

8. The LVDT of claim 1 , wherein at least one end of the first moveable core or the second moveable core is permanently attached to 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