Temperature compensated electrical sensor system for measuring ferrous particles in a fluid using a series resonant oscillator and microprocessor

摘要

A magnetic sensor for the collection and measurement of ferrous particles through the use of an electronic tuned circuit is disclosed. The sensor contains an electrical inductance coil along with an integral magnet to attract ferrous particles suspended in the fluid. The ferrous particles collecting on the magnetic surface of the sensor causes a change in the inductance of the integral coil which is measured by an electronic circuit. The electronic circuit operating in conjunction with the sensor utilizes a series resonant circuit. A measurement of the voltage across the series resonant circuit is responsive to changes in temperature of the inductance coil. A microprocessor is used to determine the change in period of the resonant oscillation with change in inductance of the coil. The microprocessor uses the data on temperature variation to correct the observed change in oscillator period for the effects of temperature. The sensor may be located in environmental conditions which include a large variation in ambient temperature. The microprocessor may be interrogated to obtain information on the total debris accumulated, the presence of any rapid or large debris accumulation and the variation of the temperature in the probe.