【作者】 时培成；

【导师】 陈无畏；

【作者基本信息】 合肥工业大学 ， 车辆工程， 2010， 博士

【摘要】 发动机是汽车的主要振动激励源之一,对汽车的乘坐舒适性和NVH(Noise,Vibration and Harshness,简称NVH)特性有很大的影响。汽车NVH性能是衡量汽车品质的一个综合性重要指标,是汽车精品化过程中必须解决的关键问题。设计合理的汽车动力总成悬置系统可以明显地降低汽车动力总成和车体的振动。这样不但可以改善汽车的乘坐舒适性,而且还可以延长发动机与其它部件的使用寿命。本文以某国产轿车为研究对象,对其动力总成悬置系统隔振性能进行了分析研究。主要的研究工作包括以下几个方面:首先,讨论了国内外对动力总成悬置元件、悬置系统优化设计方面的研究与进展;分析了汽车动力总成悬置系统设计的理论与方法;确定了系统所受的广义激振力,并运用拉格朗日方程,详细推导了6自由度动力总成悬置系统的动力学方程;采用机械与液压混合列平衡方程的方法,分别建立了橡胶悬置和液压悬置的非线性数学模型,基于“嵌入式”集成仿真技术,仿真分析了多种工况下采用不同悬置元件时悬置系统的振动特性,并结合试验对仿真结果进行了分析、对比。其次,从系统固有频率配置及振动解耦角度分析了悬置系统的振动特性;根据实际条件,以提高系统振动解耦率为目标,分别应用机械系统优化算法和基于灵敏度分析的优化算法对动力总成悬置系统隔振性能进行了优化设计,并采用蒙特卡罗方法分析比较了优化前后系统的固有特性、稳健性,结果表明:优化有效提高了系统固有频率配置合理性和系统振动解耦率,使系统的隔振特性有了较大提升,改善了系统的稳定性、可靠性;证明了论文所运用的蒙特卡罗稳健性分析和参数灵敏度分析方法对悬置系统的优化设计都具有一定的指导意义,有较大的工程应用价值。最后,建立了包含动力总成-整车环境的多体系统动力学模型,分析比较了整车模型条件下动力总成在主要激振方向上固有频率的差异。基于整车模型的仿真研究,讨论了悬置系统的振动传递率,结果表明:参数优化后的悬置系统能减小振动传递率,进一步验证了优化结果的正确性和可信性,所建立的整车模型可以作为验证悬置系统优化设计结果的一种手段,并为后继研究整车系统的NVH特性奠定基础。更多还原

【Abstract】 Engine vibration is one of the main sources of vehicle vibration which affecting vehicle’s comfort and NVH(Noise, Vibration and Harshness)performance. The NVH of a vehicle represents an overall evaluation of a vehicle’s quality and refinement, and it is also the key question which in the vehicle high-quality process must be solved.A rational design of a vehicle powertrain mounting system can significantly isolate vibration from being transmitted to the vehicle body. Effective isolation will increase a vehicle comfort and extend the durability and lifespan of the engine and other vehicle components.This paper studies the powertrain mounting system vibration isolation for a domestic vehicle. The primary work includes the following aspects.First, the paper examines the research and development progress of powertrain mount and mounting system design optimization world wide; studies the fundamental theory and design method of the powertrain mounting system; determines the powertrain mounting system excitation force; deduces dynamics equation of powertrain mounting system from LaGrange equation and constructs non-linear mathematic models by utilizing mechanical and hydro-elastic equations for both conventional rubber mounts and hydraulic mounts. Based on the combined simulation techniques, the paper simulates the mounting system’s vibration performance under different mounts and different working conditions. The results were analyzed and compared with the experimental data.Second, the paper analyzes vibration characteristics of the powertrain mounting system from system natural frequency collocating and vibration decoupling point of view; examines mechanical system and sensitivity design optimization methods to improve system modal decoupling and achieve optimal design for vehicle powertrain mounting system; uses Monte Carlo technique to compare the original design and the modified one for robustness. The result shows that the design optimization study for powertrain mounting system will improve the system vibration isolation, stability and reliability. The result also demonstrates the effectiveness in engineering applications of mount design by using Monte Carlo method and mount parameters sensitivity analysis.Finally, the paper constructs a MBD(Multi-Body Dynamics) simulation model with the powertrain and vehicle system; compares vehicle model in terms of final natural frequency changes for powertrain system in primary excitation directions. The vehicle simulation study demonstrates that the mounting system will reduce the transmissibility after the optimizing parameters of the system and verifies the correctness and reliability of the optimization results. It concludes the vehicle simulation model could be used as a method for powertrain mounting system design and optimization and guide vehicle NVH study in the future.更多还原