【作者】 邹慧；

【导师】 周云山；

【作者基本信息】 湖南大学 ， 车辆工程， 2010， 硕士

【摘要】 随着汽车自动变速技术的不断发展,各国都在研究开发适合本国国情的车辆自动变速器。双离合器自动变速器(Dual Clutch Transmission,简称DCT),是在手动变速器基础上发展起来的一种新型自动变速器,它既保持了电控机械式自动变速器(Automated Mechanical Transmission,简称AMT)结构简单、传动效率高等优点,又克服了AMT换挡时动力中断的缺点,能够实现在不切断动力的情况下转换传动比,从而缩短换档时间,有效提高换档品质。由于双离合器自动变速器综合了MT、AMT、AT等变速器的优点,使车辆性能得到了大幅度的提高,因此受到很多以手动变速器为主的国家的高度重视。本论文以6速湿式双离合器自动变速器为研究对象,对双离合器自动变速器的产生和应用前景进行了介绍,对双离合器自动变速器的结构特点、工作原理及其组成与功能进行了分析。双离合器自动变速器通过两个离合器联结两根输入轴,相邻各档的被动齿轮交错与两输入轴齿轮啮合,配合两个离合器的控制,可以实现换挡过程中通过离合器的交替切换使换挡过程无动力中断,从而达到动力起步和换挡的目的,有效地提高起步与换档品质。对湿式、干式双离合器的性能以及两种湿式双离合器的结构型式进行了比较,建立了湿式多片离合器接合过程的动力学模型。发动机是汽车动力的源泉,因而发动机模型是汽车传动系仿真的基础,因此建立了用于整车系统仿真的发动机模型。在对双离合器自动变速器起步和换档过程分析的基础上,根据不同离合器的工作状态确定了双离合器自动变速器的工作模式,建立了双离合器自动变速器起步和换档动力学模型。根据实际研究需要,建立了八自由度整车模型并对离合器接合过程的冲击度和滑摩功进行了分析。离合器起步要反应迅速,适应车辆载荷和外界坡度的变化,并能减小离合器的磨损率,因而离合器起步控制是一个难点问题。本文在建立双离合器自动变速系统起步动力学模型的基础上,通过对起步过程离合器接合规律的研究,提出采用Ⅰ、Ⅱ档同时参与起步过程,并根据不同的起步条件和驾驶员意图模糊控制两离合器分离、接合的程度及汽车起步挡位的起步控制策略,利用Matlab/Simulink软件对双离合器自动变速系统的起步过程进行建模仿真分析,并与电控机械自动变速器AMT的单离合器起步的结果进行了对比。结果表明,采用所设计的起步模糊控制策略能够有效地提高双离合器自动变速汽车的起步品质。在分析双离合器自动变速器换档重叠特性及升降档过程中双离合器控制策略的基础上,采用两参数综合换档控制规律对双离合器自动变速传动系统换档过程进行建模仿真,仿真结果表明,该换档控制策略能够实现两离合器快速、准确地分离和接合,并能够保证双离合器自动变速汽车换档时的平顺性和快速性的要求。双离合器自动变速器具有传动效率高、安装空间紧凑、重量轻等许多优点,并且它通过简单的平行轴式变速器结构实现了动力换档过程,既提高了车辆性能,又降低了生产成本,特别适合于在我国的推广普及,必将在自动变速器领域占有重要的地位。更多还原

【Abstract】 With the development of automobile automatic transmission, various of automatic transmissions suited to own national condition are researching and developing. Dual Clutch Transmission (DCT)is a new type of automatic transmission based on manual gearbox. It retains the advantages of the Automated Mechanical Transmission, for example, simple structure and high efficiency, at the same time it could overcome the shortcomings of the AMT shift at the power interruption and change the ratio under the power on, so it reduces the shift time and improves the shift quality. The DCT incorporates the merits of MT, AMT, and AT, so many manual gearbox to the countries attach great importance.This paper mainly studies on the following aspects based on the six-speed wet Dual Clutch Transmission.It introduces the production and the application prospect of DCT.Moreover, it analyzes the DCT on the structural features, working principle, the composition and function. Dual Clutch Transmission has two input shafts and two clutches, by right controlling the two clutches. DCT needn’t cut off the power when shifting, thus it can be achieved the purpose of power starting and shifting.At last,it could effectively improve the quality of starting and shifting.It contrasts the structrue of two types of wet dual clutch, and the characteristic of wet and dry clutch. It builds the clutch engagement model.The engine is the source of the car power, so it is the base of the powertrain simulation. And the engine model is built for the vehicle simulation system. Based on analyzing the starting and shifting process, it decides the work patterns of the DCT according to the different clutch friction modes.The Dual Clutch Transmission dynamic model for simulation is built.According to research,it established the eight-freedom vehicle model and analyzed the two important criteria of the clutch engagement process.The clutch must be start rapid and adapt to the change of the load and gradient, reduce the wear of the clutch. So it is a difficult problem.The paper is based on the establishment of the dual clutch transmission start dynamic model.Through analyzing the engagement rule of the clutch, the starting control strategy is put forward that 1st and 2nd gear are both applied in the process of vehicle startup simultaneously.And it could fuzzy control the two clutches engaging intensity and the startup gear according to strategy of the different startup conditions and driver’s intention. Using Matlab/ Simulink software, it sets up simulation model and analyzes the starting process of the DCT, The simulation results indicate that the adopted starting fuzzy control strategy can improve the startup quality of the Dual Clutch Transmission vehicle effectivelySet up simulation model for DCT shift process based on the overlap character-istic of the DCT and the control strategy for upshift and downshift of DCT. The resultsdedicate that the two clutches quickly separate and accurately joint,and the Dual Clutch Transmission vehicle ensures that the requirements of the smoothness and speed in shifting process.Dual clutch transmission has many advantages, such as high transmission efficiency, compact installation space and will have an important status in automatic transmission family.更多还原