Engine Condition Monitoring Based On On-line Wear Debris Monitoring Technology

Internal combustion engine is widely used in various industries as a power device that burns inside mechanical equipment to release energy and works externally.As one of the most typical friction pairs in the internal combustion engine,the cylinder liner piston system has extremely bad working conditions,and its friction loss accounts for more than half of friction loss of the internal combustion engine,which affects the overall performance and service life of the internal combustion engine.However,wear debris of friction pairs will enter into lubricating oil and lubrication system,and a lot of wear information of friction pairs can be found in the lubrication system.Therefore,it is necessary to put forward an effective condition monitoring method for the lubrication system of internal combustion engine,so as to find the abnormality in time and reduce the cost.In this paper,the cylinder liner piston system of typical friction pair of internal combustion engine was taken as the research object.Firstly,the state monitoring test-rig of cylinder liner piston system of internal combustion engine was designed and built.Then,the evolutionary model of dynamic concentration of wear debris in internal combustion engine lubrication system was studied,and state evaluation method for internal combustion engine based on wear debris monitoring was studied.Finally,the state monitoring test scheme of internal combustion engine cylinder liner piston system was designed to verify the theoretical model and algorithm,and the wear state of internal combustion engine cylinder liner piston system was analyzed,so that the online real time state monitoring for internal combustion engine cylinder liner piston system was realized.The following contents were studied.(1)According to the actual working conditions and monitoring requirements of internal combustion engine cylinder liner piston system,a state monitoring test-rig for internal combustion engine cylinder liner piston system was designed,manufactured and set up.The condition monitoring scheme of cylinder liner and piston system was designed.The monitoring and data processing methods of lubricating oil wear debris image,physical and chemical index,off-line wear debris information and wear surface morphology measurement were studied,which provides suitable technique support for the research of condition monitoring for internal combustion engine cylinder liner piston system.(2)Taking the cylinder liner and piston system of internal combustion engine as the research object,based on the theory of adhesive wear and abrasive wear,and considering the influence of wear debris deposition and non-stationary characteristics of wear,the dynamic concentration model of cylinder liner and piston ring lubrication system of internal combustion engine under different wear stages was established based on Archard wear model.The evolution law of wear debris concentration under different working conditions and at different time was analyzed.(3)The maximum entropy method of fractional moment was applied to the condition evaluation of internal combustion engine.To overcome the shortcoming of this method,the generalized minimum distance between the probability density function of wear debris monitoring data and the estimated value of probability density was studied as the objective function.The carnivorous plant optimization algorithm was used to optimize the key parameters.Combined with the diagnostic standard of wear debris monitoring,the experimental monitoring data were analyzed.The result shows that,the proposed method can effectively evaluate the wear state of internal combustion engine.(4)According to the proposed wear debris dynamic concentration model and state evaluation method of cylinder liner and piston ring lubrication system of internal combustion engine,based on the on-line monitoring information of wear debris,the wear health state and time-varying trend of cylinder liner and piston system were analyzed.The off-line collected wear debris and cylinder liner surface morphology were analyzed.The test result shows that,the trend of online wear debris monitoring was the same as that of offline wear debris analysis and surface morphology measurement,which verifies that the dynamic concentration model and state evaluation method of wear debris proposed in this study can predict the abnormal situation of internal combustion engine accurately.On this basis,the influence of physical and chemical index(viscosity and temperature)change of lubricating oil on the wear of cylinder liner piston system of internal combustion engine was analyzed.The on-line wear monitoring of the whole internal combustion engine was carried out,which further proves that the state evaluation method proposed in this paper can realize the wear state evaluation of internal combustion engine.