Research On The Multi-Object Optimization Of Engine Mount System Based On Vehicle Test

Powertrain is the one of the main sources of automotive vibration.Unbalanced forces and torques will arise obviously when the engine operates normally.With the development of automotive technology on light weighting,the coupled vibration between the engine and the vehicle body is gradually aggravated.And it ultimately lead to the deterioration in interior vibration and noise.As an important connection between the engine and the vehicle body,mount system can effectively reduce the vibration transmitted from the powertrain to the frame and body.The isolation characteristics of the powertrain have the significant and direct influence on the ride comfort and driving stability for the passengers.And it is a very important contributory factor for vehicle's NVH performance.Hence,rational design of the engine mount system plays a very critical role in interior vibration and noise reduction.It is of great importance to make a detailed research on the optimization of engine mount system in automobile design.In this paper,focused on the problem of the low performance of vibration isolation,a multi-object optimization method for engine mount system is proposed based on the modeling analysis.A 15-degree model considering coupled vibration between the vehicle body and the powertrain is modeled based on the mechanical vibration theory.The vibration equation of the coupled system is solved by using Lagrange's methodology.Combining the actual conditions of the vehicle,the excitation forces are identified as the actual force input based on the vehicle test.The vibrational response and overall transmitted force can be solved in frequency domain.The identification method is verified by comparison with the results of engine bench test.A multi-object optimization concurrently considering both decoupling rate in Torque Roll Axis coordinate system,overall transmitted force and acceleration response are defined as the objective function.And all of common driving conditions are considered.The particle swarm optimization(PSO)algorithm is used to optimize the mount stiffness parameters.Robust of the mount system is analyzed by considering the manufacturing error of the rubber mount.Finally,taking the optimization of idling condition as an example,the vehicle test is carried out by replacing the optimized mount.Taking vibrational level and sound pressure of the typical measurement point as the evaluation value,the vehicle test results show that interior vibration and noise decrease obviously.As shown in the research,the overall transmitted force and acceleration response can be reduced effectively by choosing proper parameters of the mount stiffness.And the TRA decoupling rate increases.The comfort of automobile can be improved.The availability and effectiveness of the method proposed can be verified by the analysis of vehicle test.This method can be used to optimize the design of general mount system and to improve its vibration isolation performance.