On-line monitoring system of vehicle lubricants quality based on the permittivity

High quality lubricants is necessary to keep the vehicle working normally. It´s essential to develop the low cost, convenient operation, better real-time online lubricants detecting devices. By using the modern physical theory on permittivity and the method of experimental analysis, the conformance of the change trend between the permittivity and acid value, iron content, moisture content which are three significant evaluation indexes of lubricants is discussed, the feasibility of regarding the permittivity as the comprehensive evaluation index to evaluate the lubricants quality is verified. A mathematical monitoring model on permittivity is established to evaluate lubricants quality; furthermore, the vehicle-bone capacitive transducer and the real-time PWM monitoring system for the quality of lubricants are designed. Detecting results of tested vehicles proved that the monitoring system can send out oil change alarm according to the lubricants deterioration status, thus avoid the premature replacement of good oil and the continued using of the inferior lubricants.