考虑传动效率的HMT拖拉机经济性控制策略

    Economic control strategy of HMT tractor considering transmission efficiency

    • 摘要: 液压机械无级变速器(hydro-mechanical continuously variable transmission,HMT)的传动效率伴随输入输出状态的改变产生很大的变化幅度,是影响HMT拖拉机经济性的重要因素。该研究基于HMT效率探究目标函数的制定对拖拉机经济性的影响,提出以发动机效率最高及发动机与HMT整体效率最高为目标函数的发动机效率最优控制策略(engine efficiency optimal control strategy, EOCS)和整体效率最优控制策略(integral efficiency optimal control strategy, IOCS);建立发动机与HMT效率模型,采用改进的鱼群算法对控制参数进行寻优求解,得到两种控制策略下最优控制参数(发动机转速和HMT速比);建立HMT拖拉机仿真模型,根据实车道路/作业试验数据,提取常用工况数据片段,构建以车速和作业阻力为参数的循环工况,对两种控制策略进行对比仿真研究。仿真结果表明:在一个仿真循环工况下IOCS燃油消耗量为1.356 L,EOCS燃油消耗量为1.381 L,IOCS燃油消耗量较EOCS降低1.81%。对比分析仿真结果可知:IOCS能够有效提高发动机与HMT整体效率,经济性较EOCS好,但面对负载变化时发动机工作点变化较EOCS剧烈,加速性能较EOCS差;EOCS经济性略逊于IOCS,但面对负载变化时发动机工作点变化较IOCS平稳,加速性能较IOCS好。研究结果可为HMT拖拉机制定满足工程应用要求的控制策略奠定研究基础。

       

      Abstract: The transmission efficiency of hydraulic-mechanical continuously variable transmission varies significantly with changes in input and output conditions, which is a crucial factor impacting the operational economy of HMT tractors. Based on HMT efficiency, this study explores the influence of the formulation of objective function on tractor economy, this paper considers the efficiency of HMT and explore the influence of the influence of setting objective function on tractor economy.The integral efficiency optimal control strategy with the highest engine efficiency as the objective function and the integral efficiency optimal control strategy with the highest overall efficiency of engine and HMT as the objective function are proposed. The engine efficiency model and HMT efficiency model are established, The improved fish swarm algorithm is used to search and solve the control parameters, and the optimal control parameters under the two control strategies are obtained (engine speed and HMT speed ratio); The HMT tractor simulation model is established, according to the road/operation test data of real vehicles, the data fragments of common road/operation conditions were extracted, and the cycle conditions with speed and operation resistance as parameters were constructed, and the two control strategies were compared and simulated. The simulation results show that the fuel consumption of IOCS is 1.356L and that of EOCS is 1.381L in one simulation cycle, and the fuel consumption of IOCS is 1.81% lower than that of EOCS. Comparative analysis of simulation results shows that IOCS can effectively improve the overall efficiency of engine and HMT, and the economy is better than EOCS. However, in the face of load change, the engine and HMT operating point change more violently than EOCS, and the acceleration performance is worse than IOCS. In the face of load changes, the EOCS engine operating point changes more smoothly than IOCS, and the "reserve torque" is larger than EOCS. However, the instantaneous fuel consumption rate of HMT tractor of EOCS is slightly higher than that of IOCS, and the economy is slightly worse than that of IOCS. The research results can lay a research foundation for HMT tractors to formulate control strategies that meet the requirements of engineering applications.

       

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