Patent ID: 7391035

Claim:
A method of monitoring the oxidation of a lubricant in real time, comprising the steps of: (a) irradiating a lubricant to be monitored with an ultraviolet light; (b) measuring a fluorescence emission intensity from the lubricant in red, green and blue wavelength bands; (c) determining a first value of fluorescence intensity measured in the green wavelength band of 470 nm to 550 nm and a second value of fluorescence intensity measured in the blue wavelength band of 430 nm to 470 nm among the fluorescence emission intensity measured in the red, green and blue wavelength bands; (d) calculating a fluorescence emission ratio by taking a ratio of the first value measured in the green wavelength band to the second value measured in the blue wavelength band; (e) monitoring a change in the fluorescence emission ratio in course of oxidation of the lubricant; (f) determining whether the fluorescence emission ratio reaches a predetermined critical magnitude; and (g) indicating the necessity of replacing the lubricant when the fluorescence emission ratio reaches the critical magnitude.