Abstract: A method and apparatus for automatically detecting a lubricant type and the relative quantity of water present in a test sample of lubricating oil includes the use of an open grid capacitive sensor element that incorporates the lubricating oil as a dielectric medium. The sensor element grid is energized by a frequency variable oscillator that automatically responds to changes in the oil dielectric constant with corresponding frequency changes. As a reference, a sample of new or uncontaminated test oil is confined in wet surface contact with the energized, open grid sensor element. Oscillator frequency changes are measured and recorded, either continuously or at frequent intervals, over a standardized elapsed time interval to generate a reference characterization of the frequency-time relationship distinctive of the particular oil. The same is repeated for a sample of contaminated oil and a corresponding frequency-time relationship generated.

Abstract: A method and apparatus for detecting the degree of deterioration of a lubricating oil for an operating machine includes a grid-like capacitive sensor 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 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.

Abstract: A viscosity tester includes a free standing magnetic object disposed in fluid in a stationary receptacle. A magnetic force drives the object in an orbit and the magnetic force, the speed of the object and the lag angle between the magnetic field and the object are either measured or controlled and, based on at least one of these three parameters, the viscosity of the fluid is determined. In one embodiment, a magnetic ball is driven by four electromagnets, with proximity sensors detecting the presence of the ball and controlling the electromagnets. In another embodiment, a free standing magnet is driven in an orbital pattern by a rotating field that is coaxial with the orbital pattern and is produced by a rotating magnet or a stator.