金属带功率分流无级变速拖拉机的牵引特性分析

Analysis of Traction Characteristics of Tractor Equipped with Metal Belt Power Split CVT

为了揭示金属带功率分流无级变速拖拉机的传动性能,对其牵引特性进行了研究。首先,对典型的Kress无级变速箱的传动原理进行了介绍;其次,构建了包括发动机、传动系统和牵引特性计算在内的拖拉机整机数学模型;最后,基于所构建的模型分别对变速箱的寄生功率特性和拖拉机的牵引特性进行了仿真分析。研究结果表明:金属带功率分流无级变速箱在RL段作业时存在寄生功率,应当避免拖拉机在极低速度下作业;较机械有级变速拖拉机,金属带功率分流无级变速拖拉机的负载驱动能力略大,在低速重载工况作业时的驱动轮滑转率略高,但总体上差异并不显著。考虑到无级变速拖拉机在燃油经济性控制上的潜力,其理论性能仍要优于传统拖拉机。研究所得结论可为我国中小功率无级变速拖拉机的研发提供参考。

In order to reveal the transmission performance of the tractor equipped with metal belt power split CVT,the traction characteristics of the tractor were studied in this paper.Firstly,the transmission principle of the typical Kress CVT was introduced.Secondly,the mathematical model of the tractor,including engine,transmission system and load,was constructed under SimulationX.Finally,based on the tractor model,the CVT parasitic power and the tractor traction characteristics were calculated.The results show that:parasitic power exists in range RL of the Kress CVT,so the tractor should be avoided to use at very low speed;the traction characteristics of the tractor is similar to that of the traditional tractor.Although the tractor has a slightly stronger driving capacity,the slip rate of the driving wheel is slightly higher under low speed and heavy load conditions.Considering the potential of CVT tractor in fuel economy control,its theoretical performance is still better than that of traditional tractors.The conclusions of this study can provide theoretical reference for the research and development of CVT tractors with small and medium power in China.