【摘要】：起升機構(gòu)是履帶起重機的關(guān)鍵部件,也是影響整機性能的重要因素,起升機構(gòu)的好壞直接決定著整機的壽命與可靠性,對于大噸位履帶起重機更是如此,因此起升回路往往是履帶起重機液壓系統(tǒng)的設(shè)計重點之一。閉式液壓系統(tǒng)具有結(jié)構(gòu)緊湊、動作平穩(wěn)、易于實現(xiàn)電氣控制、布置方便等諸多優(yōu)點,在國外大噸位的履帶起重機上有著廣泛應(yīng)用,但其在國內(nèi)產(chǎn)品上的應(yīng)用還不成熟,尤其是在起升機構(gòu),還有許多關(guān)鍵技術(shù)沒有解決,因此有必要對起升機構(gòu)閉式液壓系統(tǒng)進行深入研究,以推動我國起重機械向大型化和智能化方向發(fā)展。 本文基于大連理工大學(xué)的閉式液壓系統(tǒng)試驗平臺,分析超越負載工況下閉式液壓系統(tǒng)的特點與控制方法,并借助Simulink仿真軟件驗證控制方法的有效性。主要內(nèi)容如下： (1)總結(jié)履帶起重機起升機構(gòu)液壓系統(tǒng)的設(shè)計要求；對比分析了閉式液壓系統(tǒng)與開式液壓系統(tǒng)的異同。 (2)分析閉式液壓系統(tǒng)在超越負載工況下的特點,得到：下放重物時,泵和馬達的功能互換,馬達在重物的拖動下輸出高壓油；發(fā)動機對系統(tǒng)起制動作用；負載越大,發(fā)動機轉(zhuǎn)速和負載下降的速度就越大。針對這些特點,提出了負扭矩控制方法：在發(fā)動機被反拖超速時,通過減小泵排量或增大馬達排量限制發(fā)動機和馬達的轉(zhuǎn)速,防止轉(zhuǎn)速過快。 (3)介紹了閉式液壓系統(tǒng)試驗平臺及其參數(shù),并在Simulink中搭建超越負載工況下閉式液壓系統(tǒng)的仿真模型,通過對不同負載下系統(tǒng)的動態(tài)特性及其影響因素進行分析,得到如下結(jié)論：管路長度影響系統(tǒng)的阻尼比,管路越長,系統(tǒng)的阻尼比越小,超調(diào)量越大；泵和馬達的泄漏系數(shù)影響穩(wěn)態(tài)誤差,同時對系統(tǒng)的阻尼比也有影響。 (4)結(jié)合閉式液壓系統(tǒng)試驗平臺的具體應(yīng)用,提出了閉環(huán)負反饋控制,仿真結(jié)果顯示該控制方法在大負載和小負載時能起到較好的控制作用,但在中等負載時會出現(xiàn)等幅振蕩。在控制模塊中加入相位超前校正后,消除了中等負載時的振蕩,并達到了較好的控制效果。根據(jù)專家控制算法的思想對控制方法進行改進,使系統(tǒng)的響應(yīng)時間大為減小。
[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.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH213.7

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