重型拖拉机全动力换挡变速箱自动换挡策略研究

Automatic Shift Strategy of Full Power Shift Transmission for Heavy Duty Tractors

摘要:

以一种用于220 kW拖拉机全动力换挡变速箱为研究对象，基于经济性、动力性为控制核心制定了道路运输和田间作业（犁耕）模式的标准型自动换挡策略，在全动力换挡变速箱基础上实现全自动换挡。为进一步提升不同工况下自动换挡策略的工况适应性，制定了智能型自动换挡策略，在道路运输自动换挡策略中，以燃油消耗总量为优化目标，换挡点车速和换挡延迟时间作为设计变量，对控制策略进行优化;在犁耕作业自动换挡策略中，引入滑转率变化量和车速变化量2个修正参数，通过模糊控制规则实时修正换挡点车速。基于AMESim和Matlab/Simulink建立了拖拉机仿真模型，开展自动换挡策略仿真。仿真结果表明，相较于标准型自动换挡策略，道路运输工况下，拖拉机燃油消耗总量下降6.71%;犁耕作业工况下，换挡次数降低36.5%，燃油消耗总量下降2.85%。通过台架试验验证了道路运输模式自动换挡略的有效性。

Abstract:

In response to the current lack of full power shift transmissions for heavy duty tractors and the issues of complex shifting operations, high fuel consumption, and poor adaptability in traditional tractors in China, a fully automated shifting transmission was designed for 220 kW tractors. Standard automatic shifting strategies for road transportation mode and plowing operation mode were developed based on the control core of economy and power for different working modes of tractors. These strategies enabled fully automatic shifting on the foundation of a full power shift transmission. To further enhance the adaptability of automatic shifting strategies under different working conditions, intelligent automatic shifting strategies were formulated. In the road transportation automatic shifting strategy, the total fuel consumption was taken as the optimization objective, with shifting point speed and shifting delay time serving as design variables. A genetic algorithm was employed to optimize the control strategy. In the plowing operation automatic shifting strategy, two corrective parameters, namely, slip rate variation and vehicle speed variation, were introduced to dynamically adjust the downshifting point speed by using fuzzy control rules. A tractor simulation model was built by using AMESim and Matlab/Simulink, and simulations of automatic shifting strategies under different working conditions were conducted. The simulation results demonstrated that compared with the standard automatic shifting strategy, the total fuel consumption of the tractor under the road transportation condition was decreased by 6.71%, while the number of shifts was decreased by 36.5% and the total fuel consumption was decreased by 2.85% under plowing operation conditions. Finally, the effectiveness of the road transportation mode automatic shifting strategy was validated through bench tests.