毕业设计_工程车辆液压无级变速器设计.doc

工程车辆液压无级变速器设计 摘要：液压无级变速传动是一种新型传动形式,近几年在国内外有了较快的发展,代表了当今车辆传动技术的先进水平,它采用液压、机械双功率流传动,输出功率大,无级变速控制灵活方便,合理的传动设计液压功率分流比小,系统的效率高，与有级机械传动、液力机械自动变速传动相比,动力性、经济性及排放性能均有较大的提高。为此,论文对液压机械无级变速传动进行了较系统的理论分析和结构尺寸计算。 结合工程车辆的实际工作要求，确定了车辆液压机械无级变速器传动方案，通过优化设计给出了其结构参数，并对其无级调速特性、转矩特性、功率分流特性、功率流特性、效率特性、牵引特性进行了分析，并对装有液压机械无级变速器的拖拉机与原拖拉机的牵引性能进行了分析比较。 本文的研究工作表明,有较高性能价格比的新型车用功率分流式无级变速系统相对于常规的多挡机械变速器具有较强的竞争力,作为一种更新换代产品,具有良好的应用前景。 关键字：功率分流比；传动比；传动轴转速 Abstract：Hydro mechanical variable-speed drive is a new type of transmission mode, which develops quickly in our country and represents the advanced level of today’s vehicle transmission technology. It adopts hydraulic and mechanical double power flows. The output power is high and the variable-speed drive can be controlled flexibly and conveniently. The proper transmission design makes the hydraulic power dividing ratio small and the system efficiency high. It is of high power, economy and high exhaust capability compared with the step speed change mechanical transmission and hydraulic machine auto-transmission. Therefore, this paper presents a systematic theory analysis and size calculation. Combine to the actual working demand of Engineering Vehicles, the general drive scheme for HMCVT is decided. The structural parameters of HMCVT are obtained by optimization design method. The step less speed regulation characteristic, torque characteristic, power split characteristic, power flow characteristic, efficiency characteristic and tractive characteristic of HMCVT are analyzed. The tractive performance of original tractor and improved tractor are compared. The analysis results show that the tractor assembled with HMCVT can gain a continuously variable speed. Additionally, in any traction force, the engine works near full load. As a result, the tractor with the HMCVT demonstrates greatly improved productivity and fuel economy. The research indicated that HMCVT for vehicles, which has high performance-cost-ratio, has strong competition advantage