Determining quality of lubricating oils in use
First Claim
1. A method of determining remaining useful life of a quantity of oil in use in fluid lubrication of an operating mechanism, the method comprising:
- repeatedly determining resistivity (ρ
) values of the oil at an predetermined oil temperature during operating time intervals of the mechanism;
recording a resistivity-time ρ
(t) history of the oil such that, as successive resistivity values starting with an initial value are accumulated with elapsed operating time, a continuous ρ
(t) linear curve is formulated that includes;
(1) a first portion with a slope of dρ
/dt>
0 up to a first time t1 during which values of ρ
increase and (2) a maxima at t1 where dρ
/dt=0 with a corresponding ρ
max;
comparing, from time to time, the then existing portion of the ρ
(t) curve with like predetermined data on a like or functionally comparable oil composition; and
using the comparison to predict the remaining useful life of the oil.
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Accused Products
Abstract
Resistivity ρ values of a lubricating oil are repeatedly determined at a predetermined temperature (range) as it is in use in a working mechanism such as a vehicle engine. Such accumulated properties over operating time of the working lubricant can be plotted graphically to display a curve with, for example, a first portion where dρ/dt>0, a maximum ρmax at a time t1 where dρ/dt=0, a second portion where dρ/dt<0, a minimum ρmin at a time t2 where dρ/dt again is zero, and a third portion where dρ/dt>0. Furthermore, there can exist another time t3, where dρ/dt exhibits a discontinuous change (increase) with time. Characteristics of the ρ vs. t curve, including, the values of t1, t2, t3, ρmax, ρmin, and the ratio ρmax/ρmin can be compared with like data on like lubricant oils in estimating the remaining useful life of the present operating lubricant oil.
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Citations
24 Claims
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1. A method of determining remaining useful life of a quantity of oil in use in fluid lubrication of an operating mechanism, the method comprising:
-
repeatedly determining resistivity (ρ
) values of the oil at an predetermined oil temperature during operating time intervals of the mechanism;
recording a resistivity-time ρ
(t) history of the oil such that, as successive resistivity values starting with an initial value are accumulated with elapsed operating time, a continuous ρ
(t) linear curve is formulated that includes;
(1) a first portion with a slope of dρ
/dt>
0 up to a first time t1 during which values of ρ
increase and (2) a maxima at t1 where dρ
/dt=0 with a corresponding ρ
max;
comparing, from time to time, the then existing portion of the ρ
(t) curve with like predetermined data on a like or functionally comparable oil composition; and
using the comparison to predict the remaining useful life of the oil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 23, 24)
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14. A method of determining remaining useful life of a quantity of oil in use in fluid lubrication of an operating mechanism, the method comprising:
-
repeatedly determining resistivity (ρ
) values of the oil at an predetermined oil temperature under a time-varying electric field during operating time intervals of the mechanism;
recording a resistivity-time ρ
(t) history of the oil such that, as successive resistivity values starting with an initial value are accumulated with elapsed operating time, a continuous ρ
(t) linear curve is formulated that includes;
(1) a first portion with a slope of dρ
/dt>
0 up to a first time t1 during which values of ρ
increase, (2) a maxima at t1 where dρ
/dt=0 with a corresponding ρ
max, (3) a second portion with a slope of dρ
/dt<
0 during which values of ρ
decrease up to a second time t2, (4) a minima at t2 where dρ
/dt=0 with a corresponding ρ
min, and (5) a third portion where dρ
/dt>
0;
comparing, from time to time, the then existing portions of the ρ
(t) curve with like predetermined data on a like or functionally comparable oil composition; and
repeatedly using the comparison to predict the remaining useful life of the oil. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification