Optimal Design And Control Strategy Research Of Automotive Powertrain Magneto-rheological Mount

With people‘s increasing requirement on riding comfort and the development of automobile lightweight and high-power engines, the vehicle NVH performance is confronted with higher challenges. However, the traditional rubber/hydraulic mounts with unchanged damping and stiffness characteristics can not fit in with complicated operation conditions of automotive engines, causing obvious vibration and noise problems. Therefore, it has been a vital issue of improving vehicle NVH performance to design a powertrain mounts system with excellent vibration-isolating performance, which is able to effectively restrain the vibration from powertrain to car body/frame and isolate the transmission of induced by the road excitation to the powertrain.In this paper, aiming to surpress the excessive low-frequency vibration of powertrain for some passenger car during operation conditions of start, flameout and crossing deceleration strips, which is produced by CHANG AN automotive company, some reseaches have been done from the aspects of optimal design and mechanics modeling of MR mounts, dynamical modeling of MR mount based on the whole vehicle model and vibration-isolation control strategies for powertrain. This will provide theoretical basis and technical support to completely solve the excessive vibration of powertrain caused by instantly changed torque of the engine, improve the vibration-isolating performance of the powertrain mount system and promote the riding comfort of the vehicle driven on bumpy roads.① The structure scheme of MR mount with flow mode is proposed. The rubber main spring is designed and effect of the rubber hardness on the static stiffness of MR mount is analyzed using finite element method. The adjustable coefficient and restoring force are formulated. The damping channel of MR mount is designed and the magnetic circuit is calcultated by the use of finite element method.② Based on analysis of the influence of mount structure parameters on the MR mount performance, multi-objectives optimization models of MR mount is developed. Multiple interval sensitivity analysis method is proposed to select the design variables and confirm the range of variables. The NSGA-II coded with APDL is employed to optimize the MR mount structure. The effectiveness of the method is verified by comparing the performance index of the MR mounts before and after optimization.③ The MR mount performance test is carried out, and the performance index obtained from the test is analyzed. It proves the effectiveness and validaty of the optimization method. The exponential damping model of MR mount is established with consideration of the fact that the elastic stiffness of the MR mount is not influenced by the change of the electric current. The MR model identification method combining genetic algorithm and BP neural network is proposed, and the direct/inverse model of MR mount is established using the proposed method.④ Considering the powertrain exciting force and the road excitation, the MR mounting system model combining with whole-vehicle model is developed, and the natural characteristics are calculated and analyzed. This model is verified by the real vehicle test and supplies a foundation for the design of the vibration-isolating control strategy.⑤ Taking the MR mounting system model combining with whole-vehicle model as the research object, the vertical fuzzy controller and variable universe fuzzy self-adaptive controller are designed to improve the riding comfort. As the results of numerical simulation, the variable universe fuzzy controller has better performance.