超越负载工况下履带起重机闭式液压系统研究
发布时间：2018-11-24 19:30
【摘要】：起升机构是履带起重机的关键部件,也是影响整机性能的重要因素,起升机构的好坏直接决定着整机的寿命与可靠性,对于大吨位履带起重机更是如此,因此起升回路往往是履带起重机液压系统的设计重点之一。闭式液压系统具有结构紧凑、动作平稳、易于实现电气控制、布置方便等诸多优点,在国外大吨位的履带起重机上有着广泛应用,但其在国内产品上的应用还不成熟,尤其是在起升机构,还有许多关键技术没有解决,因此有必要对起升机构闭式液压系统进行深入研究,以推动我国起重机械向大型化和智能化方向发展。 本文基于大连理工大学的闭式液压系统试验平台,分析超越负载工况下闭式液压系统的特点与控制方法,并借助Simulink仿真软件验证控制方法的有效性。主要内容如下： (1)总结履带起重机起升机构液压系统的设计要求；对比分析了闭式液压系统与开式液压系统的异同。 (2)分析闭式液压系统在超越负载工况下的特点,得到：下放重物时,泵和马达的功能互换,马达在重物的拖动下输出高压油；发动机对系统起制动作用；负载越大,发动机转速和负载下降的速度就越大。针对这些特点,提出了负扭矩控制方法：在发动机被反拖超速时,通过减小泵排量或增大马达排量限制发动机和马达的转速,防止转速过快。 (3)介绍了闭式液压系统试验平台及其参数,并在Simulink中搭建超越负载工况下闭式液压系统的仿真模型,通过对不同负载下系统的动态特性及其影响因素进行分析,得到如下结论：管路长度影响系统的阻尼比,管路越长,系统的阻尼比越小,超调量越大；泵和马达的泄漏系数影响稳态误差,同时对系统的阻尼比也有影响。 (4)结合闭式液压系统试验平台的具体应用,提出了闭环负反馈控制,仿真结果显示该控制方法在大负载和小负载时能起到较好的控制作用,但在中等负载时会出现等幅振荡。在控制模块中加入相位超前校正后,消除了中等负载时的振荡,并达到了较好的控制效果。根据专家控制算法的思想对控制方法进行改进,使系统的响应时间大为减小。
[Abstract]:Hoisting mechanism is the key component of crawler crane and an important factor affecting the performance of the whole crane. The hoisting mechanism directly determines the life and reliability of the whole machine, especially for the large tonnage crawler crane. Therefore, hoisting circuit is often one of the key points in the design of crawler crane hydraulic system. The closed hydraulic system has many advantages, such as compact structure, stable movement, easy to realize electrical control, convenient arrangement and so on. It has been widely used in foreign crawler cranes with large tonnage, but its application in domestic products is still immature. Especially in the hoisting mechanism, there are still many key technologies that have not been solved, so it is necessary to study the closed hydraulic system of the hoisting mechanism in order to promote the development of the lifting machinery in our country towards the direction of large-scale and intelligent. Based on the closed hydraulic system test platform of Dalian University of Technology, this paper analyzes the characteristics and control methods of closed hydraulic system under overloading conditions, and verifies the effectiveness of the control method by means of Simulink simulation software. The main contents are as follows: (1) the design requirements of hydraulic system of crawler crane hoisting mechanism are summarized, and the similarities and differences between closed hydraulic system and open hydraulic system are compared and analyzed. (2) by analyzing the characteristics of closed hydraulic system under the condition of exceeding the load, the following conclusions are obtained: the function of pump and motor is interchangeable when the load is lowered, the motor outputs high pressure oil under the drag of heavy load, the engine plays a brake role on the system; The greater the load, the greater the engine speed and the speed at which the load drops. According to these characteristics, a negative torque control method is put forward: when the engine is overspeed, the speed of engine and motor is limited by reducing pump displacement or increasing motor displacement, so as to prevent the speed of engine and motor from being too fast. (3) the closed hydraulic system test platform and its parameters are introduced, and the simulation model of closed hydraulic system under the condition of overloading is built in Simulink. The dynamic characteristics of the system under different loads and its influencing factors are analyzed. The conclusions are as follows: the length of the pipeline affects the damping ratio of the system. The longer the pipeline is, the smaller the damping ratio of the system is and the larger the overshoot is. The leakage coefficient of pump and motor affects the steady-state error as well as the damping ratio of the system. (4) combined with the concrete application of the closed hydraulic system test platform, the closed-loop negative feedback control is proposed. The simulation results show that the control method can play a better control role in large load and small load. But there will be equal amplitude oscillation at medium load. After the phase leading correction is added to the control module, the oscillation of medium load is eliminated, and the better control effect is achieved. According to the idea of expert control algorithm, the control method is improved, and the response time of the system is greatly reduced.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH213.7
本文编号：2354773
[Abstract]:Hoisting mechanism is the key component of crawler crane and an important factor affecting the performance of the whole crane. The hoisting mechanism directly determines the life and reliability of the whole machine, especially for the large tonnage crawler crane. Therefore, hoisting circuit is often one of the key points in the design of crawler crane hydraulic system. The closed hydraulic system has many advantages, such as compact structure, stable movement, easy to realize electrical control, convenient arrangement and so on. It has been widely used in foreign crawler cranes with large tonnage, but its application in domestic products is still immature. Especially in the hoisting mechanism, there are still many key technologies that have not been solved, so it is necessary to study the closed hydraulic system of the hoisting mechanism in order to promote the development of the lifting machinery in our country towards the direction of large-scale and intelligent. Based on the closed hydraulic system test platform of Dalian University of Technology, this paper analyzes the characteristics and control methods of closed hydraulic system under overloading conditions, and verifies the effectiveness of the control method by means of Simulink simulation software. The main contents are as follows: (1) the design requirements of hydraulic system of crawler crane hoisting mechanism are summarized, and the similarities and differences between closed hydraulic system and open hydraulic system are compared and analyzed. (2) by analyzing the characteristics of closed hydraulic system under the condition of exceeding the load, the following conclusions are obtained: the function of pump and motor is interchangeable when the load is lowered, the motor outputs high pressure oil under the drag of heavy load, the engine plays a brake role on the system; The greater the load, the greater the engine speed and the speed at which the load drops. According to these characteristics, a negative torque control method is put forward: when the engine is overspeed, the speed of engine and motor is limited by reducing pump displacement or increasing motor displacement, so as to prevent the speed of engine and motor from being too fast. (3) the closed hydraulic system test platform and its parameters are introduced, and the simulation model of closed hydraulic system under the condition of overloading is built in Simulink. The dynamic characteristics of the system under different loads and its influencing factors are analyzed. The conclusions are as follows: the length of the pipeline affects the damping ratio of the system. The longer the pipeline is, the smaller the damping ratio of the system is and the larger the overshoot is. The leakage coefficient of pump and motor affects the steady-state error as well as the damping ratio of the system. (4) combined with the concrete application of the closed hydraulic system test platform, the closed-loop negative feedback control is proposed. The simulation results show that the control method can play a better control role in large load and small load. But there will be equal amplitude oscillation at medium load. After the phase leading correction is added to the control module, the oscillation of medium load is eliminated, and the better control effect is achieved. According to the idea of expert control algorithm, the control method is improved, and the response time of the system is greatly reduced.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH213.7
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