Study On Identification Method Of Engine Inertia Properties

The engine is the most important source of vibration for the car,so reducing the transmission of engine vibration to the body has an important role in improving the NVH performance of the car.The inertial parameters of the engine,including mass,center of mass,inertia and inertial product,accurately identify the inertial parameters of the engine,are the premise and key to the dynamic analysis of the engine and vibration isolation.This paper aims to identify the inertial parameters of the engine accurately and efficiently.Based on the frequency response function mass line,some researches on the method and identification device of the inertial parameters of the engine are carried out.Firstly,the inertial parameter identification method of the engine with known and unknown masses is studied.A principle device of the inertial parameter identification of the engine is designed,and the influencing factors of inertial parameter identification accuracy analyzed by simulation.By constructing a recognition experiment device and using a standard block of known inertial parameters as the test object,inertial parameter identification experiments and calibration experiments are performed.Second,the inertial parameter identification method of the engine in the installation state is studied to realize the inertial parameter identification and suspension parameter identification.Factors affecting the identification accuracy have analyzed by simulation and inertial parameter identification experiments were performed on the engine of a passenger car.Finally,the method of identifying the excitation force based on the inertial parameters of the engine is studied.The multi-body dynamics software is used to establish the multi-body dynamics model of the engine.The correctness of the identification method of the engine excitation force and the influence of the inertial parameters of the engine on the identification accuracy is studied by simulation.On the basis of recognizing the inertial parameters of the engine,a certain passenger car engine is used as the test object,and the exciting force identification experiment under steady state conditions is performed.The research results show that the inertia parameter identification method and identification device can be used to identify the inertial parameters of the engine.In the inertial parameter identification methods with known and unknown masses,the coordinate errors of the excitation point and the response point have the most significant influence on the recognition accuracy.The experimental identification error of inertial parameter identification method whose mass is known is within 4.48%,and the other one is within 9.3%,and after inertial parameter calibration of the experimental device,they become 4% and 8.97% respectively.When inertial parameters of the engine in the installation state are identified,the effect of noise on the recognition accuracy of the inertial parameters of the engine is most obvious.And the experimental results of the inertial parameters meet the requirements of the engineering application.In the identification of engine excitation force,the influence of mass center on the identification accuracy of the excitation force is obvious,and the inertia and the product of inertia have a significant influence on the identification accuracy of the excitation torque,but have no effect on the excitation force.The results of excitation force identification experiments show that the second-order excitation force of the engine is dominated by the Z direction,and the torque around the Z-axis is very small,which is in accordance with the theoretical analysis.