静液压传动拖拉机定速巡航控制系统设计与试验

Design and Experiment of Cruise Control System for Hydrostatic Transmission Tractor

针对现有农机速度调节策略功率匹配度不高、燃油经济性差的问题,以静液压传动拖拉机为平台,基于CAN总线设计了拖拉机定速巡航控制系统。该系统由拖拉机工况采集、负载检测、油门控制、变量泵排量调节、作业负载调节、通信等模块组成。设计了油门调节机构和负载调节装置,获取并解析了拖拉机工况数据,建立了静液压传动拖拉机油门开度、变量泵排量与速度对应的数学模型,制定了发动机转速与变量泵排量协同控制策略。分别在水泥路面空载、田间空载和平地作业3种工况下进行了协同控制策略试验,在平地作业工况下进行了定油门控制策略、油门排量耦合控制策略和油门排量协同控制策略试验。结果表明,3种工况下,协同控制策略的速度控制绝对误差分别为0.005、0.007、0.012 m/s;在达到相同目标速度的前提下油门排量协同控制策略降低了发动机转速。拖拉机定速巡航控制系统能够在保证速度控制精度的前提下,减小燃油消耗。

Aiming at the problems of low power matching degree and poor fuel economy of the existing agricultural machinery speed regulation strategy,taking hydrostatic tractor as the platform,the cruise control system of the tractor was designed based on CAN bus. The system was composed of a tractor working condition acquisition module, a throttle control module, a variable pump displacement adjustment module,a work tool lifting control module,and a communication module. Devices of throttle adjustment and load adjustment were developed. Tractor working condition data was analyzed.Mathematical model of throttle opening,variable pump displacement and tractor speed was established.A strategy for cooperative control of engine speed and variable pump displacement was developed. The cooperative control strategy experiments on empty cement roads, empty farmland and flat working conditions were conducted;and the experiment of the fixed throttle control strategy, the throttle displacement coupling control strategy and the throttle displacement cooperative control strategy was carried out under the flat operation conditions. The test results showed that the absolute error of speed control of the cooperative control strategy was 0. 005 m/s,0. 007 m/s and 0. 012 m/s under the three working conditions of cement pavement,field no-load and flat land operation;the cooperative control strategy reduced the engine speed under the premise of achieving the target speed. The control system can reduce fuel consumption while ensuring the accuracy of speed control.