Estimation of soot and fuel invasion in diesel engine oils through a combination of dielectric constant sensor and viscosity sensor 2019-01-0302
In order to meet latest emission standards, more and more advanced technologies such as EGR, DPF and multiple injection strategy are being used in diesel engines. However, some of these complicated technologies could lead to the invasion of soot and fuel into engine oil during engine operation, possibly causing severe wear. Once soot and diesel content is beyond a certain level, the engine oil should be changed to guarantee the well lubrication. A proper way to monitor the oil state is necessary. It is well known that soot and fuel have influence on oil permittivity and viscosity. Thus, in this study, a combination of dielectric constant sensor and viscosity sensor was chosen to measure dielectric constant and viscosity. Black carbon was used as the substitute of soot and mixed with diesel at different ratios. Both dielectric constant and viscosity of oils increase as soot content increases. Fuel content has a certain effect on viscosity and slight effect on dielectric constant. Regression and artificial neural network were used to correlate the dielectric constant and viscosity with the oil deterioration and a prediction model was established. The predicted results show a good agreement with the experimental results. It is believed that with the developed algorithm, a combination of dielectric constant sensor and viscosity sensor could be potentially used for online estimation of lubricant oil soot and oil dilution conditions.
Yitao Shen, Ting Hu, Yanyan Wang
Harbin Institute of Technology (Weihai)