Research On The Vibration Loss Efficiency Of AJR Engine

The engine is the main excitation source of vehicle vibration,which affects the power,comfort and economy of the vehicle.Under the background of the current development of the automotive industry towards low energy consumption and high efficiency,lightweight engines have become an emerging development trend.The analysis and control of engine vibration has become the focus of extensive attention and research in various countries around the world.The weight of the engine body after the use of new materials is lighter,and the proportion of the total mass of the engine is reduced,and its vibration will inevitably change.In order to accurately describe the vibration status of the lightweight engine and reflect the vibration loss efficiency of the engine under different operating conditions,this paper mainly conducts research from the following aspects:(1)Principle of engine dynamometer and test bench.Starting from the principle of how the dynamometer measures the power,the AJR engine dynamometer system was built.Based on the principle and composition of the engine dynamometer and the working principle of the eddy current dynamometer,based on the thermodynamic principles,a water cooling system suitable for the GW100 B eddy current dynamometer is designed.The water cooling system is simulated and verified in MATLAB/Simulink.Lay the foundation for deriving the engine vibration loss efficiency formula and carrying out vibration test.(2)Engine vibration isolation internal force model and vibration loss efficiency.Based on the analysis of the vibration causes of single-cylinder engines and in-line four-cylinder engines,the differential equations of engine dynamics are established through Lagrangian equations.The internal force model of engine vibration isolation is proposed to distinguish it from the traditional external force model of dynamic vibration isolation,and the errors of the two are analyzed.Based on the internal force model theory,define and derive the relevant formulas for the vibration loss efficiency of the engine with single degree of freedom,two degrees of freedom and six degrees of freedom,providing theoretical basis for subsequent simulations and tests.(3)Research on engine vibration simulation.Based on the dynamic vibration isolation internal force model and the engine single-degree-of-freedom vibration loss efficiency theory,the engine vibration simulation model is established through the MATLAB/Simscape platform to study the vibration of the engine body and moving parts,and calculate the time domain vibration loss efficiency of the engine under different operating conditions.(4)Engine vibration test and signal analysis.Based on the three-point support Santana 2000-AJR engine bench,combined with the DH5922 dynamic signal test and analysis system,a vibration test system was built.The engine vibration acceleration signal,torque signal,and speed signal under the engine starting condition and idling condition are collected through experiments,and the data is analyzed and processed by MATLAB software,and the actual vibration loss efficiency of the engine is calculated.Research indicates: There is an error in using the traditional vibration isolation external force model to describe the vibration of the lightweight engine;The proposed dynamic vibration isolation internal force model can describe engine vibration more accurately;The deduced vibration loss efficiency is used to describe the effective output power and vibration loss power of the engine;Using the MATLAB/Simscape simulation platform and the test bench,the vibration conditions of the engine under different operating conditions are obtained,and the corresponding vibration loss efficiency is calculated.The research results prove the accuracy of the dynamic vibration isolation internal force model,and provide a better theoretical method for studying the vibration of the lightweight engine.The research results can provide a new perspective on the quality design and vibration control of engines and other power machinery.