Leonid Matsiev

New Solid State Oil Condition Sensor for Real Time Engine Oil Condition Monitoring

Engine lubrication oil degrades at varying rates depending on the lubricant, engine type and application. Traditional maintenance programs are designed to change oil on predetermined intervals (such as run time/mileage), with more advanced algorithms taking into account load and operating temperature of the engine, or lab analysis. Conservative interval based maintenance programs spend too many resources changing oil and longer intervals may result in engine damage. Lab based oil condition approaches also have significant time lag and other logistical difficulties. Real time engine oil condition analysis offers a balance between oil life and maintenance cost. Real time oil analysis also allows for the implementation of active reliability-centered maintenance. When a fleet manager knows the actual maintenance condition of each vehicle in a fleet, it is possible to accurately prioritize and schedule appropriate maintenance. Real-time oil condition monitoring can help insure that a fleet utilizes the maximum useful life of the lubricants while protecting the performance of the engine Researchers at Symyx Technologies have developed a miniature, solid state oil condition sensor based on a crystal tuning fork. The sensor provides direct measurement of the critical physical properties of viscosity, density, dielectric permittivity, and AC conductance of lubricants [1, 2]. Simultaneous measurements of multiple parameters of lubricating oil in an engine can provide improved sensitivity for detection of changes, which may be the result of degradation or contamination. This paper investigates the response of the Symyx sensor to various diesel engine oil base stocks, additive packages, common oil contamination and real time engine oil monitoring. Results of the Symyx sensor output are compared to conventional lab oil analysis techniques. The suitability of the Symyx sensor as means of determining diesel engine oil condition and predicting remaining useful oil life is discussed.

High precision tuning fork sensor for liquid property measurements

Application of piezoelectric flexural mechanical resonators such as tuning forks to accurate measurements of liquid physical properties is discussed. It was shown earlier that liquid properties such as viscosity, density and dielectric constant can be obtained by measuring the resonator AC impedance within certain frequency range and fitting it to the resonator equivalent circuit model (1). Error sources for the liquid property measurements and their influence on the measured value are investigated. It is shown experimentally that the reproducibility of the viscosity and density measurements using this technique can meet and often exceed the one delivered by the well established analytical instrumentation. It is also demonstrated here that better performance is resulting from the use of the whole impedance curve over a frequency range, which produces better statistics and natural averaging of the noise.

Multiparameteric Oil Condition Sensor Based on the Tuning Fork Technology for Automotive Applications

The continuous improvement in engine technology in order to achieve new emission norms have led to an increased amounts of petrol, diesel and soot in the engine oil during engine operation. This dilution causes a fast decrease of the oil properties. Additional, the recommended oil change intervals for automotive engines have continuously been extended over the last few decades. In many cars, this interval is calculated using a set of certain characteristic engine parameters and driving behaviour (oil temperature, engine speed, number of engine ignitions). In order to prevent engine failures as a result of abnormally aged oil, or extreme driving conditions, it is necessary to monitor the oil condition continuously. This can only be reliably realized by means of a sensor directly located in the harsh oil environment of combustion engines. The developed sensor enables the measurement of viscosity, density, permittivity and temperature of the engine oil and provides therefore relevant data for sophisticated oil condition algorithms.