Vibration Analysis And Software Development Of Powertrain Mounting System Of Internal Combustion Engine

The vibration of internal combustion engine is one of the main source of the vehicle vibration, which has an important effect of vehicle. NVH performance, By further analyzing the mechanism and influence factors of internal combustion engine vibration,which is helpful to promote the development of vibration theory of internal combustion engine and provide a suitable balance design plan at the stage of conceptual design of diesel engine and minimize the losses of the afterward remedy In traditional design. Not only it is conducive to further improve the reliability of products, but also can greatly shorten the cycle of design and manufacture and optimize the weight, materials and structure, increase the economic efficiency of enterprises. In this paper, the following research work has been carried out with a in-line four cylinder machine.(1)Through the dynamic analysis of the crank connecting rod mechanism of the internal combustion engine, a general calculation formula of unbalanced force at the center of mass is derived for a in-line internal combustion engine, which laid a foundation for the dynamic characteristic calculation.(2)A simplified model of six degree of freedom of the rigid body for the powertrain mounting system of internal combustion engine is established. By using the energy decoupling method, the natural frequency, mode shape and the decoupling rate of the system are obtained with MATLAB. Then frequency domain analysis is applied to analyze forced vibration by exerting unbalanced force. The displacement characteristics of the center of mass, transmission rate and vibration intensity of the mounting system are obtained.(3)From the angle of mounting design parameters, The first order sensitivity formula of the nature frequency and decoupling rate of the powertrain mounting system to the design parameters of mount, such as principal stiffness, position, h installation angle has been discussed theoretically; From the angle of design parameters of internal combustion engine, the influence of the length of the connecting rod and the crank radius on the dynamic response parameters of the mounting system-- the influence of the displacement at the center of mass, the vibration intensity and the transmission rate is studied when the mounting system is in forced vibration.(4)Based on the above work, the vibration analysis and optimization software of a powertrain mounting system is developed by using MATLB/GUI. The software not only can use the powertrain mounting system parameters to calculation modal characteristics and dynamic characteristics, but also can optimize vibration intensity of the powertrain.