内燃机动力总成悬置系统的优化设计研究

发布时间：2018-06-20 19:09

本文选题：动力总成悬置系统 + 解耦率　；参考：《中北大学》2016年硕士论文

【摘要】：发动机动力总成是汽车最主要的振动源和噪声源之一,随着生活的日益改善,人们对汽车产品的安全性和舒适性要求越来越高。如何使动力总成悬置系统能更好地减振、隔振是非常有价值的问题,对汽车产业的发展和进步至关重要。合理的设置悬置系统,优化悬置性能,不但可以提高汽车行驶的平稳性、减少能耗,而且可以增加汽车及其零部件的使用寿命,提高安全性能。本文致力于对动力总成悬置系统进行优化,使车辆具有更好的NVH性能。具体做了以下工作:一、首先,介绍了动力总成悬置系统的基本功能,以及国内外发展现状。随后,对单缸曲柄连杆机构与直列六缸发动机的激励力进行分析。在此基础上,对现有机型的激励力和力矩进行平衡分析,得到其不平衡力和力矩。二、建立了悬置系统的物理模型、数学模型。求解自由振动微分方程,得到系统的刚度矩阵、固有频率等固有特性;求解强迫振动微分方程,得到系统在主惯性坐标系下的振动位移、速度等。分析系统固有特性和动态特性的不足之处,为进一步的优化设计指明方向。三、对现有机型固有特性进行计算分析。应用Matlab平台中的fgoalattain法对悬置系统解耦率进行优化。优化目的为使各自由度解耦率都达到90%以上,固有频率合理配置,使得系统各模态运动互不干涉。四、对于悬置系统这样的多自由度耦合振动系统来说,振动解耦是降低和控制系统振动最为行之有效的做法。解耦率是系统在不受激励力的情况下的固有特性,但是在汽车行驶过程中,动力总成时刻受到激励力的作用,这就需要对动力总成悬置系统的动态特性进行优化。振动烈度是表征系统隔振性能的重要指标,而且振动烈度反映了包含各谐次波能量的总振动能量大小,能够更加直观地代表系统的振动强度,常用来表征系统的振动性能。本文以振动烈度作为优化目标,将悬置刚度、安装位置作为优化参数,对悬置系统再次进行优化。优化结果显示,系统在各工况下的振动位移、速度、加速度都有所降低,并且振动烈度减小。例如,在转速为2200r/min的额定工况下,优化前后,系统的振动烈度从35.5542mm/s降到了28.9692mm/s。达到了降低振动烈度的优化目标,振动性能明显改善。
[Abstract]:Engine powertrain is one of the most important vibration and noise sources of automobile. With the improvement of life, people demand more and more safety and comfort of automobile products. How to make the powertrain mount system better reduce vibration, vibration isolation is a very valuable problem, is very important to the development and progress of the automobile industry. Setting up the mount system reasonably and optimizing the mounting performance can not only improve the ride stability and reduce the energy consumption, but also increase the service life and safety performance of the automobile and its parts. This paper focuses on the optimization of the powertrain mount system to make the vehicle have better NVH performance. The main contents are as follows: firstly, the basic functions of powertrain mount system and the development status at home and abroad are introduced. Then, the excitation force of single-cylinder crank-connecting rod mechanism and linear six-cylinder engine is analyzed. On this basis, the excitation force and torque of the existing aircraft are analyzed, and the unbalanced force and torque are obtained. Secondly, the physical model and mathematical model of the mount system are established. The stiffness matrix and natural frequency of the system are obtained by solving the free vibration differential equation, and the vibration displacement and velocity of the system in the main inertial coordinate system are obtained by solving the forced vibration differential equation. The shortcomings of the inherent and dynamic characteristics of the system are analyzed, and the direction of further optimization design is pointed out. Third, the inherent characteristics of the existing models are calculated and analyzed. The decoupling rate of mount system is optimized by using fgoalattain method in Matlab platform. The aim of the optimization is to make the decoupling rate of each degree of freedom more than 90%, and the natural frequency is allocated reasonably, which makes the motion of each mode of the system non-interference. Fourthly, the vibration decoupling is the most effective way to reduce and control the vibration of the multi-degree-of-freedom coupling vibration system such as the mount system. Decoupling rate is the inherent characteristic of the system without excitation force, but in the driving process of the vehicle, the dynamic characteristics of the powertrain mount system need to be optimized. Vibration intensity is an important index to characterize the vibration isolation performance of the system, and the vibration intensity reflects the total vibration energy which contains the energy of each harmonic wave. It can represent the vibration intensity of the system more intuitively and is often used to characterize the vibration performance of the system. In this paper, the vibration intensity is taken as the optimization objective, and the mounting stiffness and the installation position are taken as the optimization parameters to optimize the mounting system again. The optimization results show that the vibration displacement, velocity and acceleration of the system are decreased and the vibration intensity is decreased. For example, the vibration intensity of the system decreases from 35.5542mm/s to 28.9692mm / s before and after optimization under rated 2200r/min speed. The optimization goal of reducing the vibration intensity is achieved and the vibration performance is obviously improved.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.13

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