Patent ID: 8155891

Claim:
An oil monitoring apparatus, comprising: a housing mounted to a member containing oil therein so as to be in contact therewith; a first sensor mounted to the housing, the first sensor including: an optical passing element with an interface in contact with the oil; a light-emitting means for emitting a light to the optical passing element; and a color-sensing means for measuring respective optical intensities at respective red, green and blue wavelength ranges of a light passing through the oil via the optical passing element and the interface and for outputting respective signals; a second sensor mounted to the housing for measuring water content of the oil and outputting a signal; a third sensor mounted to the housing for measuring temperature of the oil and outputting a signal; and a control unit including a processor, the processor being configured to calculate a ratio value and a variation value from the respective signals outputted from the color-sensing means, the ratio value being defined by a ratio of an optical intensity at the red wavelength range to an optical intensity at the green wavelength range, the variation value being defined by variations in optical intensity at the respective red, green and blue wavelength ranges between an initial condition and a current condition of the oil, the processor being configured to further calculate a relative saturation of the oil by water from the output signals of the second sensor and a temperature value of the oil from the output signals of the third sensor, the processor being configured to monitor the ratio value, the variation value, the relative saturation and the temperature value.