An all-metal eddy current position sensor and its solution to temperature drift

Abstract

The invention provides an all-metal eddy current position sensor and a method for solving temperature drift. An eddy current position sensor is usually used as a proximity switch. When a tested objectmoves to the proximity switch and approaches a certain target detection position, the proximity switch operates. The precision of the proximity switch crucially depends on the precision of temperature drift at the target detection position, and a study finds that an output signal does not drift with the change of a temperature when an excitation frequency and position are constant, which is a temperature invariant point. According to the target detection position, by using temperature invariant point characteristics, the excitation frequency f is found, a circuit module is adjusted, and a sinusoidal signal of the excitation frequency f is generated to provide accurate excitation for two coils. According to the method, the temperature invariant point characteristics are used, the method for solving temperature drift of the all-metal eddy current position sensor is provided, thus the sensor is not affected by the change of an ambient temperature, and a detection result is accurate.

Description

technical field [0001] The invention relates to the field of measurement and control of an eddy current position sensor, in particular to an all-metal eddy current position sensor and a solution to temperature drift. Background technique [0002] Eddy current position detection technology is a non-destructive detection method based on the principle of electromagnetic induction, which is suitable for position detection of various conductive specimens. When the excitation signal is passed into the probe, the excitation magnetic field generated by the inner coil of the probe and the eddy current magnetic field induced in the tested object will be coupled, and the relative position signal between the probe and the measured object will be converted into the change of the induction coil signal. Corresponding position signals can be obtained through subsequent processing circuits. [0003] In the actual application process, the eddy current position sensor is greatly affected by t...

AI Technical Summary

Problems solved by technology

This method only considers the non-metallic package of the probe and the situation that there is no metal equipment near the installation environment. It fails to conduct research and analysis on the metal package of the sensor probe and the presence of metal around the installation, which has poor versatility.

2. Add a non-inductive non-inductive coil with the same resistance value to sense the temperature change to compensate. This method can only eliminate the temperature drift caused by the temperature change of the detection coil resistance itself, and fails to adjust the temperature of the shell and the resistivity of the detection body. drift compensation

However, this method only adds metal materials around the side ends of the surrounding coils, and is not suitable for detection when the probe is fully metal-packaged.

4. Use some expensive high-temperature-resistant alloy materials to wind the coil. The structure of this probe is the same as that of ordinary probes, but the cost is expensive. Although it can reduce the temperature drift of the detection coil itself, it still cannot solve the temperature caused by the metal packaging of the probe. drift

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