Patent ID: 6839620

Claim:
A method of monitoring during real time operation the soot accumulation in diesel engine lubricant comprising: (a) disposing a pair of electrodes in the engine lubricant and applying an alternating voltage to the electrode at different frequencies over a selected range and measuring the current magnitude and phase angle at each frequency and computing the resistive and reactive component of the impedance for each current measurement; (b) comparing the reactive component as a function of the resistive component of impedance and determining the location of the center of semicircular curvature between the origin and the low frequency minimum occurring value of reactive impedance; (c) delaying a specified time interval repeating steps a, b and c computing the angle of depression from the origin to the center of curvature; (d) determining the percentage of soot from one of (i) a comparison with known values of percentage soot versus depression angle (ii) a known relationship between percentage soot and depression angle; and, (e) providing an electrical signal indicative of soot reaching a selected level of concentration.