【作者】 王颖颖；

【导师】 刘振军；

【作者基本信息】 重庆大学 ， 车辆工程， 2008， 硕士

【摘要】 双离合器自动变速器(DCT)是在电控机械式自动变速(AMT)技术基础上发展的一种新型自动变速器,它具备手动变速器结构简单、传动效率高的特点,并且克服了AMT换档过程动力中断的弱点,换档迅速,综合了AMT的优势和液力自动变速器AT动力换挡的优点,具备了很好的换挡品质和车辆动力性、经济性,已成为汽车自动变速器新的发展方向,具有广阔的市场前景。目前DCT采用的离合器有干式和湿式两种结构型式。干式双离合器与湿式双离合器相比具有结构简单、传动效率高、成本低的优点,但对于干式离合器换档时为避免动力中断,两个离合器切换过程中必然存在扭矩传递的重叠,从而导致离合器大量滑摩热量的产生。离合器摩擦片的磨损随压盘温度的升高而增大,当压盘工作表面温度超过180～200?C时,摩擦片磨损急剧增加,而温升取决于干式离合器的热容量和热量耗散能力,因此温升控制问题是影响干式双离合器承载能力和寿命的关键之一。本文针对装有干式双离合器自动变速器的车辆起步过程中离合器的滑摩温升问题进行了研究,主要内容如下:①在分析干式离合器的摩擦材料、摩擦类型、摩擦过程和失效形式的基础上,对干式离合器主要性能参数及摩擦过程中热负荷评价指标进行了计算;②制定了双离合器车辆起步控制策略,对DCT传动系统进行动力学分析,建立发动机、双离合器、整车数学模型和离合器滑摩功数值仿真模型。利用MATLAB/SIMULINK对采用干式双离合器自动变速汽车不同载荷普通路面起步和爬坡起步过程进行仿真,动态求解得到滑摩功曲线;③从传热学的基本理论出发,求解离合器摩擦副热分析边界条件,利用ANSYS软件对双离合器摩擦副瞬态温度场进行有限元建模和仿真;④通过对摩擦副温升过程的研究,分析了离合器摩擦副温升影响因素。提出了有利于降低温升,提高承载能力和使用寿命的干式双离合器结构设计方案和冷却系统与装置的设计方案;⑤对干式离合器温升测试方法和摩擦磨损性能进行了研究,设计了干式离合器模拟测试系统,并制定了实验测试方案和步骤。更多还原

【Abstract】 Dual-clutch Automatic Transmission (DCT) is a new automatic transmission developed on the basis of the electronically controlled Mechanical Automatic Transmission ( AMT) technology. DCT has simple, efficient transmission characteristics like Manual Transmission(MT) and can shift rapidly, which overcomes the AMT weakness of shifting power disrupts. DCT has become the new direction for the development of broad market prospects for a vehicle automatic transmission, because of the AMT advantages and the AT advantages of power shift, the good shift quality and dynamic and economic vehicle nature of the DCT.There are two kinds of clutches currently used in a DCT, wet and dry. Dry clutches have the advantages of simple structure, high transmission efficiency and low cost compared with wet clutches. But in order to avoid power interruption when dry clutch shift, the two clutchs switch unavoidably to produce the torque transmission overlap, then leading to a lot of sliding friction heat. The wear of the friction disk increases with the pressure-plate temperature-rise. When the work surface temperature of the pressure is over 180 ~ 200 ? C, friction-wears increases sharply. Temperature-rise depends on the heat capacity and heat dissipation capacity of dry clutch. So the heat dissipation is a key to DCT carrying capacity and working life.The paper studies the sliding friction process of clutch with temperature-rise issues, produced in dry dual clutch automatic transmission when vehicles start. The main contents are as followed:①Dry clutch friction materials, the type of friction and friction process were explained. Key performance parameters and the failure mode of dry clutch, evaluation parameters of heat load in the process of friction are calculated;②The start control strategy using two clutches is made. There is dynamic analysis for DCT transmission system. Mathematical models of the engine, double-clutch, and the slipping work are established. The car in different loads on ordinary road when doing climbing starting work is simulated under MATLAB / SIMULINK, then the slipping work curve produced under different work conditions;③Based on the heat transfer theory, boundary conditions for thermal analysis of clutch friction are acquired. The finite element models of clutch friction disk and the pressure plate are established. Temperature rising of them is acquired and their transient temperature field distribution is obtained using ANSYS software;④Through the front studies temperature rising of pairs, we determine the influence factors of temperature rise of clutch friction pairs. It is useful for reducing the temperature rising, carrying capacity and enhancing the service life of dry type structure of dual clutch design and cooling systems and equipment design;⑤Temperature-rise and wear testing system is studied.The dry clutch simulation test system is designed.The basic structure of test bench and the testing process are established.更多还原