METHOD OF DEFINING OF OIL LUBRICITY Russian patent published in 2015 - IPC G01N3/56 

FIELD: machine building.

SUBSTANCE: method of defining of oil lubricity means that friction pair is operated upon lubricant presence, electric current is conducted through it, direct current is measured at fixed friction pair and stable friction mode, oil sample with permanent weight is heated at definite temperature for permanent time period. Then part of oxidized oil is sampled and photometric measured; coefficient of light flux absorption is determined; another part of the oxidized oil sample is tested on friction machine, and lubricity is determined according to current effect coefficient. At that the oxidized oil sample is tested on the friction machine at permanent friction parameters, direct current is conducted through the friction pair from the external stabilized voltage source, diagram of current changes during friction is plotted, it is used to determine start of the stable wear and current value. Then coefficient of electrical conductivity of the barrier layer is determined as ratio of current flowing through the barrier layer to the set current, wear sport diameter and ratio of coefficient of light flux absorption to the wear spot diameter are determined. The voltage drop, U_BL, of the barrier layer separating friction surfaces is determined at stable wear using the empirical formula: $$U_{BL}=\frac{{К}_A}{U}\cdot {К}_{BLE},$$ where K_A is coefficient of light flux absorption; U is wear spot diameter, mm; K_BLE is coefficient of barrier layer electrical conductivity. Diagram of barrier layer voltage drop vs. coefficient of light flux absorption is plotted, based on it the tested oil lubricity is determined. The higher barrier layer voltage drop is the higher lubricity is.

EFFECT: justified selection of oils for the internal combustion engines based on comprehensive estimation of the tested oil lubricity based on its optical properties, wear value and coefficient of electric conductivity of the friction contact representing resistance of the barrier lubricating layer.

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