A method and apparatus for detecting the degree of deterioration of a lubricating oil for an operating machine includes a grid-like capacitive sensor (20) that uses the lubricating oil as a dielectric medium. A magnetic field is imposed upon the oil to attract ferromagnetic wear particles into the vicinity of the sensor. Preferably, the magnetic field is generated by at least two independently controlled electromagnet windings (26, 28) aligned such that the magnetic field produced by each winding acts upon the wear particles. A plurality of capacitance measurements are taken at periodic intervals at each of several magnet operational states for respective classification and analysis. All windings may be simultaneously de-energized for release of captured particles back in to an oil circulation stream and to clean the capacitative sensor grid of accumulated particulates.

In-situ oil analyzer and methods of using same, particularly for continuous on-board analysis of diesel engine lubrication systems

A method and apparatus for detecting the degree of deterioration in lubricating oil including a grid-like capacitive sensor, that uses the lubricating oil as a dielectric medium, and a magnetic field imposed upon the oil to attract ferromagnetic wear particles into the vicinity of the sensor. Preferably, the magnetic field is generated by a permanent magnet and an electromagnet aligned such that the magnetic field produced by each magnet acts upon the oil along the same axis. A plurality of capacitance measurements are taken at periodic intervals for one type of classification and analysis. Magnetically induced particle concentrations are analyzed visually under the aid of periodic magnetic flux reorientation and optical magnification.

Oil monitor with magnetic field

In one aspect of the present invention, an apparatus for detecting particles within a fluid is disclosed. A bobbin defines a debris collection chamber. Spaced apart first and second coils are wound about the bobbin in the proximity of the debris collection chamber, wherein the inductance of the coils are responsive to the particle accumulation within the collection chamber. An electromagnet is wound about the second coil to attract ferrous particles into the proximity of the second coil. A reference coil is wound about the bobbin to compensate for the changing temperature of the fluid. An oscillator is coupled to the first, second and reference coils for selectively producing an oscillating waveform at a frequency that induces eddy currents in the particles. The frequency of the oscillating waveform is indicative of the amount of accumulation of both the ferrous and non-ferrous particles.

Apparatus for detecting particles in a fluid and a method for operating same

A system for detecting spark in an igniter for a gas turbine engine. An igniter generates a plasma, or spark, somewhat similar to an automotive spark plug. In the invention, an inductive pick-up is positioned adjacent the igniter, to detect current pulses in the igniter, to thereby infer the presence of spark. The pick-up can take the form of a coil embedded in a mounting bracket which is used to fasten the igniter to the engine.

Integral spark detector in fitting which supports igniter in gas turbine engine

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.

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

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 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 parallel tuned resonant circuit and time variant frequency multiplying to eliminate undesired response changes of the tuned circuit due to the temperature change of the sensor. The sensor may be located in environmental conditions which include a large variation in ambient temperature. The disclosed invention provides for compensation of such undesired changes caused by temperature change so that the actual change of the inductance in the sensor can be monitored without interference. The signal output from the circuit disclosed is representative of the amount of ferrous debris accumulated on said sensor.

Electrical sensing system for measuring ferrous particles within a fluid with temperature compensation circuit

An electronic circuit utilizing a parallel tuned resonant circuit and time variant frequency multiplying to eliminate undesired response changes of the tuned circuit due to temperature is disclosed. The electronic circuit illustrated permits accurate measuring of the change of inductance in a parallel tuned circuit where such change of inductance is due to an input parameter to be measured. The inductive component being measured may be located in environmental conditions which include a large variation in ambient temperature. While normally such wide temperature variations may substantially interfere with the measurement of the value of the inductance in question, the disclosed invention provides for compensation of such undesired changes so that the actual change of the inductance can be monitored without interference. The invention utilizes a dual frequency clock oscillator and a time selective system to alternatively select a high or low frequency input to the parallel tuned resonant circuit, and includes two sample and hold components operating in conjunction with the time selected frequency input of the circuit.

Nicholas P. Maris

Papers

Electrical sensing system for measuring ferrous particles within a fluid with temperature compensation circuit

Time-frequency multiplexing system for correcting output amplitude of a tuned circuit due to impedance drift