拖拉机动力输出双万向轴分析及优化设计

Analysis and optimization design of double universal joint of tractor PTO

作为轮式拖拉机的重要动力输出机构,动力输出轴能够为各种类型的配套农机具提供动力。针对动力输出轴在旋耕作业中易断裂的问题,对传动系统中影响输出轴受载的因素进行研究。首先对万向节传动结构进行分析,构建万向节Ⅲ轴的工作摆角与动力输出轴的阻力扭矩之间的解析关系,并利用MATLAB进行仿真分析。然后基于TRIZ理论,以减小摆角为目标,应用物-场模型设计出一种新型的旋耕机机构,并利用ADAMS和EDEM进行新机构与原机构的对比仿真试验,结果表明摆角极值由8.42°减小至3.29°,平均值由5.23°减小至1.62°,阻力扭矩放大系数的平均值由0.55减小至0.36,有效地减少动力输出轴上的载荷,提高动力输出轴的使用寿命。该研究结果能够为同类问题提供解决思路和技术支持。

Power take-off is an important part of the wheeled tractor. It can provide power for kinds of agricultural machinery. This paper presents the fatigue fracture of PTO in the operation of rotary tillage, and the corresponding factors that influence the output loads in the drive system. First of all, the structure of the cardan joint is discussed, and the working parameters affecting the resistance torque on PTO are analyzed. According to the transmission characteristics of double cross universal joint, the relationship between inclination angle of rotary tiller and resistance torque is established. After that, the proposed process is analyzed by means of MATLAB. Secondly, the structure optimization of the rotocultivator is carried on by using TRIZ which is a new theory and method in the process of innovative design. The inclination angle is selected as the optimization objective, and then the component function, harmful function and substance-field of rotocultivator work system are applied, respectively. Based on the analysis above and the standard solutions, a new rotocultivator structure is designed and discussed. Finally, a model of the rotocultivator system was established and analyzed by using ADAMS software. It shows that the extreme inclination angle of the new mechanism is reduced from 8.42° to 3.29°, the average inclination angle is reduced from 5.23° to 1.62°, and The average value of torque amplification coefficient of resistance decreases from 0.55 to 0.36. These evaluation indexes are optimized, and it proves that the new mechanism is reasonable. It demonstrates that the fatigue mode of PTO is optimized, and the proposed design can be applied to practical application. The research results can provide solutions and technical support for similar problems.