液压混合动力挖掘机回转装置控制方式的研究

为了降低挖掘机的燃油消耗,提高整机作业效率,提出了一种基于液压混合动力技术的挖掘机动力系统节能方案.该方案采用液压泵/马达独立驱动回转装置,可保证发动机工作于最佳燃油工作区,同时结合挖掘机回转装置的作业工况,通过分析液压混合动力系统的特点,对回转装置的控制方式进行了设计.针对回转系统参数的不确定性,设计了智能比例-积分-微分(PID)的分段变结构控制器,并通过仿真和模拟试验平台验证了控制器的有效性和适用性.研究结果表明,智能PID转矩控制方式更适合于回转装置的作业要求,相对于转速控制方式,系统响应速度快,回转装置运动控制平稳,能量回收率高,达到了理想的控制效果.     

Heat Transfer Process of Bubble during the Occurrence of Cavitation in Hydraulic System

Thermal characteristic of cavitation has great influence on the process of occurrence,development and collapse of bubble in hydraulic system. By choosing the stage of bubble growth as the research object,combining with the characteristic of the process of bubble occurrence and development in hydraulic system, and ignoring the impact of thermal radiation,the heat transfer situation of bubble growth was analyzed under appropriate assumptions of thermodynamic conditions in the bubble generation and development process. The mathematical expression of the temperature change of bubble was deduced using thermodynamic principle. Through combining the expression with classic Rayleigh-Plesset Equation,numerical calculation was carried out and the temperature variation over time（ or bubble radius） was obtained. The influences of convective heat transfer coefficient of bubble and polytropic exponent on the thermodynamic process of bubble were analyzed. Finally,the thermal characteristic of bubble growth after cavitation occurrence was summarized.     

一种混联式液压混合动力系统及控制策略

混合动力系统的拓扑结构和控制策略决定了整车的性能.文中提出了一种适合城市公交工况的基于地面扭矩耦合方式的混联式液压混合动力系统,以及以满足车辆瞬时动力需求为基础、以全局经济性最优为目标的整车能量管理策略;借鉴研究混杂系统的方法和思路,采用了分层递阶控制以简化系统的结构;基于Matlab/Simulink/Statflow联合仿真技术,建立整车前向模型,并选择ECE城市循环工况对整车的经济性和动力性进行分析.结果表明,文中所提出的液压混合动力系统及控制策略可明显改善发动机的输出特性,有效地提高整车的燃油经济性和瞬时动力性.     

Input Split Hydraulic Hybrid Bus and Control Strategy

Simple and efficient energy management strategy is the key to ensure hybrid vehicle performance. Based on hybrid dynamical system theory and the concept of finite state mechanism,power split hybrid connected structure hydraulic hybrid system was proposed and described. In order to meet the demand for driving,the layered advanced control strategy was proposed in this paper,which referred to vehicle driving experience. Using Matlab /Simulink /Stateflow hybrid modeling method, the economy performance and the acceleration performance of the vehicle under the typical city driving cycles were carried on the simulation analysis. The results show that the proposed topology and control strategy can obviously improve engine output characteristic,effectively enhance the vehicle＇s instantaneous power performance and economy,and also has a better adaptability in different traffic environments.