摘    要
 
本设计针对目前社会上应用越来越广泛的自动变速器进行研究，完成了自动变速器的总体方案、控制系统以及行星齿轮机构的设计。选用微型汽车发动机排气量为0.94L，汽车最大总质量1800Kg，行驶最高时速200Km/h。
本设计论述了自动变速器的结构组成、工作原理并对主要零部件进行了参数设计和强度校核。自动变速器由液力变矩器、超速档行星齿轮机构、3速行星齿轮机构和液压控制系统等组成。其中行星齿轮由三部分组成：一个太阳轮、一个装有行星轮的支架和一个内齿圈齿轮。行驶速度的调节、节气门位置的移动以及发动机转速的控制均是通过齿轮之间的滑动来实现的。其中行星齿轮装置在传递能量和对发动机提供扭矩的调整过程中起了关键性的作用。使齿轮产生移动的作用力来源于液体压力。复杂的阀体被用在封闭的系统内控制和引导有压力的液体的流动。
所设计的变速器能够在适当的操作环境下实现超速档、倒档、前进档、空档和直接档之间的档位变换。实现了操控方便、省力、快捷的目的。
 
关键词：自动变速器；行星齿轮；液压控制系统；内齿圈齿轮；档位
 

ABSTRACT
Automatic Transmissions is widely used in the society in the recently years. This design is specially preparing for studying it . Automatic Transmissions whole set the control system and planetary gear set has been done. The output gas of the engine is 0.94L ,the quality of the whole car is 1800Kg ,the highest speed is 200Km/h.
In this design there are the consist set of the Automatic Transmissions, laws of planetary gear operation , the date of designed most important set and checking its strongthen. It has three parts ,there are the torque converter ,overdriver planetary gear systems ,three speed planetary gear systems and hydraulic control systems. A simple planetary gear set consists of three prats : a sun gear ,a carrier with planetary pinions mounted to it and an internally toothed ring gear or annulus.
Automatic Transmissions upshift and downshift with no direct assistance from the driver .Factors such as road speed , thottle position and governed engine speed control and triggr shifting between gears. The majority of automatic transmissions rely on planetary gear sets to transfer power and generate torque from the engine to the drive line. The shifting of planetary gears is actuated by the use of hydranlic force .An inticate system of valves is used to control and direct pressurized fluid in the closed system.Under proper sperating conditions it provides overdrive ,reverse,Forward reduction, neutral and direct drive.
 
Key Words：Automatic transmission; Planetary gear; Hydraulic control system; Internal gear; Driver