Methods and systems for controlling the temperature stability of an inductor

Abstract

Methods and systems a method of assembling a proximity probe are provided. The method includes determining a coil wire dimension and coil geometry for the probe such that a resistance versus temperature profile of the coil is approximately constant when the coil is excited with an excitation frequency of approximately 150 kilohertz to approximately 350 kilohertz, and adjusting the coil geometry such that a resistance versus temperature profile of the coil is substantially constant.

Description

BACKGROUND OF THE INVENTION [0001] This invention relates generally to controlling the temperature stability of an inductor, and more particularly to methods and apparatus for controlling the temperature stability of a sensing coil of a proximity probe. [0002] At least some known rotating and reciprocating machinery use an eddy current or proximity probe to facilitate monitoring machine vibration or rotor position characteristics. The environment that the proximity probe operates may be relatively harsh. [0003] Typically, the proximity probe, outputs a signal correlative to a spacing between a target object such as, a rotating shaft of a machine or an outer ring of a rolling element bearing and a sensing coil of the proximity probe. The gap or spacing between the target and the sensing coil of the proximity probe needs to remain within the linear range of the proximity probe for providing accurate and reliable measurements of machine vibration characteristics. Accordingly, to provid...

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Problems solved by technology

The environment that the proximity probe operates may be relatively harsh.

Moreover, the sensing coil of the proximity probe usually contains sources of temperature drift error which are attempted to be compensated for in the final product.

A source of the temperature drift error in the sensing coil is due to a temperature dependent resistance of the coil and an inductance of the coil.

This temperature dependent resistance and inductance of the sensing coil effects a source of temperature drift error resulting in inaccurate proximity probe measurements as a consequence of the false appearance of a gap change between the target and sensing coil.

Such inconsistencies in temperature stability of the proximity probe result in unpredictable and unreliable measurements even when the proximity probe is functioning in its linear range of operation.

Compensation for such inconsistencies is usually only partially effective to facilitate temperature dependent errors.

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