Electrical techniques for monitoring the condition of lubrication oil

Abstract

The lubricating oil used in engines for vehicle and other applications is renewed according to a schedule specified by the manufacturer. This timetable is, naturally, very conservative, and makes no allowance for the way in which the engine is operated. Constant-speed operation (such as motorway use) is much less harmful to the lubricant than variable-speed operation, such as urban driving, during which the oil experiences extreme variations of temperature and engine speed. The net result of the conservative lubricant replacement schedule is that most engine oil is discarded well before it has reached the end of its useful life.This paper reports a study in which changes to the dielectric and magnetic properties of the oil are assessed as methods of measuring the degradation of lubricating oil. The relationship between oil use (measured by the distance a vehicle has travelled) and oil viscosity is also measured.The conclusions from this work are that simple distance travelled (miles/kilometres) is not a good indicator of the state of an oil, as estimated by measuring its viscosity.The magnetic characteristics of lubricating oil (i.e. its magnetic permeability) do change as the oil degrades, but the measurements were poorly correlated with viscosity and do not seem to offer much promise as the basis of an oil monitoring system.The dielectric properties of lubricating oil are reasonably well correlated with viscosity, and it is proposed that this could form the basis of a useful sensing technique.

Experimental characterization of contaminants in engine lubricants using surface plasmon resonance sensing

“…As the SPR curve for a used lubricant is shifted to the right up with respect to a fresh lubricant's SPR curve and the R min and u SPR values are increased (Figure 6(a)), this indicated that the dielectric permittivity 1 d of a used lubricant is higher than for a fresh lubricant. This result obtained through the analysis of lubricant optical properties is clearly concurred with a dielectric constantviscosity-mileage correlation measured by a capacitive sensor (Turner and Austin, 2003). In order to analyze statistically the difference between SPR measurements of fresh and used lubricants presented by informational parameters u SPR and R min , classic pattern recognition analysis (Tou and Gonzalez, 1974) was applied due to the following reasons.…”

Real time oil control by surface plasmon resonance transduction methodology

“…In automotive, lubricating oils are replaced according to a schedule specified by cars manufacturers: this strategy of maintenance is independent of the real state of oil, because does not take into account the operative conditions [7]. In fact, properties of lubricant depend on both external (e.g.…”

Assessment of using unleaded fuel in the harsh environment of the United Arab Emirates

“…Contaminants can alter the viscosity of oil, preventing proper lubrication. Soot, dirt, sludge, and oxidation products can make the oil too thick; conversely, dilution with unburned fuel may make the oil too thin (Turner and Austin, 2003).…”

“…Then it multiplies these by the oil capacity, as a greater oil capacity means the work is spread over a greater volume, and multiplies these by ten times the virgin oil's TBN (representing the oil's ability to handle the stress loads) to arrive at the oil change interval. Carey and Hayzen (2001) and Turner and Austin (2003) showed that the dielectric constant is another important indicator of oil quality that is easy to measure on-site. This test can reflect the presence of contaminants, such as water or particles, or changes in oil chemistry due to additive depletion or oxidation.…”