Patent ID: 6844745
Filing Date: 2005-01-18
Classification: G01N

Abstract:
1. A method of monitoring the conditions of engine lubricant in real time during operation comprising: (A) immersing a probe with a pair of spaced parallel conductors in the fluid to be monitored; (B) exciting of said pair of electrodes with an alternating voltage at a first relatively high frequency and exciting said one conductor at a second relatively low frequency and measuring the current at said first and second frequencies; (C) computing the bulk fluid impedance at said first frequency and the fluid-electrode interface (surface) impedance at the said second frequency and computing the impedance difference (dZ) therefrom; (D) delaying for a selected time interval and repeating steps (A)-(C) and computing another value of dZ; (E) computing the rate of change of dZ (ΔdZ) for a selected time interval (Δt) and determining the value of the remaining useful life (RUL) of the lubricant from the following: (F) repeating steps (B)-(E) after a selected time delay Δt and determining a second value of X (X  and, (G) computing the remaining useful life (RUL) expressed as a percentage by dividing the difference in X from a known X