本文選題：動力總成懸置系統(tǒng) + 解耦率��； 參考：《中北大學》2016年碩士論文

【摘要】：發(fā)動機動力總成是汽車最主要的振動源和噪聲源之一,隨著生活的日益改善,人們對汽車產(chǎn)品的安全性和舒適性要求越來越高。如何使動力總成懸置系統(tǒng)能更好地減振、隔振是非常有價值的問題,對汽車產(chǎn)業(yè)的發(fā)展和進步至關重要。合理的設置懸置系統(tǒng),優(yōu)化懸置性能,不但可以提高汽車行駛的平穩(wěn)性、減少能耗,而且可以增加汽車及其零部件的使用壽命,提高安全性能。本文致力于對動力總成懸置系統(tǒng)進行優(yōu)化,使車輛具有更好的NVH性能。具體做了以下工作:一、首先,介紹了動力總成懸置系統(tǒng)的基本功能,以及國內外發(fā)展現(xiàn)狀。隨后,對單缸曲柄連桿機構與直列六缸發(fā)動機的激勵力進行分析。在此基礎上,對現(xiàn)有機型的激勵力和力矩進行平衡分析,得到其不平衡力和力矩。二、建立了懸置系統(tǒng)的物理模型、數(shù)學模型。求解自由振動微分方程,得到系統(tǒng)的剛度矩陣、固有頻率等固有特性;求解強迫振動微分方程,得到系統(tǒng)在主慣性坐標系下的振動位移、速度等。分析系統(tǒng)固有特性和動態(tài)特性的不足之處,為進一步的優(yōu)化設計指明方向。三、對現(xiàn)有機型固有特性進行計算分析。應用Matlab平臺中的fgoalattain法對懸置系統(tǒng)解耦率進行優(yōu)化。優(yōu)化目的為使各自由度解耦率都達到90%以上,固有頻率合理配置,使得系統(tǒng)各模態(tài)運動互不干涉。四、對于懸置系統(tǒng)這樣的多自由度耦合振動系統(tǒng)來說,振動解耦是降低和控制系統(tǒng)振動最為行之有效的做法。解耦率是系統(tǒng)在不受激勵力的情況下的固有特性,但是在汽車行駛過程中,動力總成時刻受到激勵力的作用,這就需要對動力總成懸置系統(tǒng)的動態(tài)特性進行優(yōu)化。振動烈度是表征系統(tǒng)隔振性能的重要指標,而且振動烈度反映了包含各諧次波能量的總振動能量大小,能夠更加直觀地代表系統(tǒng)的振動強度,常用來表征系統(tǒng)的振動性能。本文以振動烈度作為優(yōu)化目標,將懸置剛度、安裝位置作為優(yōu)化參數(shù),對懸置系統(tǒng)再次進行優(yōu)化。優(yōu)化結果顯示,系統(tǒng)在各工況下的振動位移、速度、加速度都有所降低,并且振動烈度減小。例如,在轉速為2200r/min的額定工況下,優(yōu)化前后,系統(tǒng)的振動烈度從35.5542mm/s降到了28.9692mm/s。達到了降低振動烈度的優(yōu)化目標,振動性能明顯改善。
[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.
【學位授予單位】：中北大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：U464.13

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