摘要:随着现代汽车行业的发展，城市道路的拓宽，交通法规及其车辆管制的严格化，一般城市公交汽车所配备的传统手动五档变速器不能很好的适应现在城市道路状况，达到发动机的最大输出功率。根据城市公交汽车市场的调查，城市公交汽车车速一般在40km～60km 之间，变速器主要在2、3、4 档工作，这三个档位的利用率达到90%以上。为了在保证城市公交汽车手动变速器机械效率与机械强度不变的情况下，通过改变变速器传动比和几何尺寸，对变速器主要参数选择与计算（档数、传动比、轴与齿轮和操纵机构设计方案的概述等）及同步器的设计等，使其减轻质量，降低制造成本，减少燃油的消耗，从而达到变速器的改进设计的目的。

该方案是在城市公交汽车的转速减少扭矩增加相匹配的条件下，提高城市公交汽车的动力性与燃油经济性。该方案是在城市公交汽车的转速减少扭矩增加相匹配的条件下，提高城市公交汽车的动力性与燃油经济性。适应道路的行驶状况，适应人们乘坐交通工具的习惯，从而减轻城市的交通、环境的压力，那我们的设计研究就存在着很大的社会意义了。

关键词：城市公交汽车；变速器；选择与计算；动力性；燃油经济性

Abstract:Along with the development of the modern automobile industry, the expansion of urban roads, traffic regulations and the strict control of vehicles, generally the urban public transportation equipped with tradition manual five-speed transmission can not well adapted to the current state of urban road condition, achieve the maximum output power of the engine. According to a survey of urban public transport automobile market, urban public transport car speed is generally between 40km and 60km, the transmission mainly work in 2,3,4 speed, the utilization of the three speeds up over 90%. In order to ensure that urban public transport automobile manual gearbox mechanical efficiency and mechanical strength do not reduce under the premise, by changing the gearbox’s ratio of transmission and geometric dimensions, about with the main parameters of selection and calculation of transmission (speed number, ratio of transmission, shaft and gear and the design program of manipulation mechanism of overview, etc.) and the design of synchronous devices to reduce the quality and reduce manufacturing costs, reduce fuel consumption, so as to achieve the purpose of transmission of the improved design. The design program in urban public transport automobile to reduce speed and increase torque to match conditions, improve the urban public transport automobile’s power performance and fuel of economy.

Keyword: urban public transport automobile; transmission; selection and calculation;power; fuel of economy