Oil deterioration detection apparatus and apparatus for detecting particles in liquid

An apparatus for detecting a deterioration of oil, comprising:

• sensor means for detecting a condition of carbon particles in the oil and for outputting a signal representative that the concentration of the carbon particles is more than a predetermined level indicative of the deterioration of the oil performance or that the particle size of the carbon particles is more than a predetermined particle size indicative of the deterioration of the oil performance, said sensor means being an optical sensor for detecting the intensity of light reflected at a detection surface of the oil with Goos-Hanchen shift, the light intensity being changed in accordance with the concentration of the carbon particles in the oil,
• said sensor comprising:
• a light-emitting portion for emitting light toward the oil;
• a photosensor for receiving the reflected light and for outputting a signal corresponding to an amount of reflected light received;
• and
• cleaning members disposed in the oil which are moved throughout the oil by the flow of the oil and are capable contacting said detection surface;
• flow-out prevention members constructed and arranged to prevent said cleaning members from flowing away from a location near said detection surface while allowing the oil to flow in the vicinity of said detection surface, said cleaning members being movable within an area defined by said flow-out prevention members;
• and
• means for judging that the concentration of the carbon particles in the oil exceeds a predetermined concentration indicative of the deterioration of the oil performance when the output signal from said sensor means exceeds a predetermined value.