阀—泵并联变结构调速系统研究

发布时间：2018-02-15 15:50

本文关键词： 补油式阀-泵并联控制泄油式阀-泵并联控制变结构调速系统阀-泵权重比综合性能虚拟仪器　出处：《中国矿业大学》2014年博士论文　论文类型：学位论文

【摘要】：传统的液压马达调速系统有两种基本形式：阀控和泵控。阀控响应快但效率低，适用于对快速性要求较高的中小功率场合；泵控效率高但响应慢，适用于大功率和对快速性要求不高的场合。近年来，阀-泵联合控制得到了迅速发展，其充分发挥了阀控与泵控各自的优势。论文提出了一种崭新的阀-泵并联控制系统，即阀-泵并联变结构调速系统，在调速过程中控制模式随控制要求而变，可实现大功率液压调速系统的综合性能，即低速平稳快速启停、快速调节负载干扰、全程高效率。论文的主要工作和研究成果如下：（1）总结和分析了国内外目前阀-泵联合控制系统的工作原理和特点，并指出目前的阀-泵联合控制方式难以实现上述综合性能。（2）设计了阀-泵并联变结构调速系统，其关键点有两点，一是阀可以根据控制要求处于补油或泄油两种状态，以使系统处于补油或泄油式阀-泵并联两种控制模式，二是可以通过改变Kvp，调节阀控与泵控在速度控制中的比重；建立了阀-泵并联变结构调速系统的数学模型，分析了系统的参数，并指出传统的泵控系统加入阀控后，液压固有频率不变，但总泄漏系数明显增大，导致系统阻尼比显著增大且随阀的工作点（阀开口及系统压力）而变化，同时导致系统刚度下降，易受负载干扰。（3）设计了开式以及闭式阀-泵并联变结构控制系统的结构，建立了补油式和泄油式阀-泵并联控制闭式系统的流量平衡方程，分析了各流量之间的关系，指出在闭式阀-泵并联变结构调速系统中，补油回路及冲洗回路是必需的，不能因有阀控补油就取消补油回路，同时冲洗回路除了有热交换的作用还有平衡系统流量的作用。建立了液压模拟系统与实际系统之间参数匹配的理论基础，指出为模拟实际系统的动态特性，应分别按照泵排量、马达排量、转动惯量三个参数来配置模拟系统，本实验系统是以煤矿液压提升机这种大功率大惯量液压系统为例而建立的模拟系统。（4）提出了阀控权重Kv和泵控权重Kp的概念，并依据不同的Kv和Kp，建立了传统泵控、阀控与阀-泵并联控制之间的联系；为了判别阀与泵在联合调速中的作用，建立了阀-泵权重比的概念，即Kvp=Kv:Kp，并通过该权重比以及阀控状态，判别系统处于何种控制模式。（5）提出了补油式和泄油式阀-泵并联两种控制模式，研究了不同权重比对控制特性的影响，并获得了阀-泵并联控制的规律：在不同的权重比（Kvp=1:0～0:1）下，系统响应速度呈金字塔形，两头慢（阀控和泵控），中间快（阀-泵并联控制），因此无论对于指令信号，还是负载干扰的快速响应，阀-泵并联控制比单独泵控或阀控响应都快；因阀控的开环增益大于泵控，对于相同的权重之和（Kv+Kp），，以阀控为主的系统响应快于以泵控为主；阀与泵的流量之比与阀-泵权重比成正比；补油式比泄油式阀-泵并联控制更具优势，因为前者使系统的阻尼比更稳定，这有利于系统的预测与控制，并且还可通过提高Ps，进一步提高响应速度和增大速度刚度，更适用于对负载干扰的快速调节，仿真与实验结果表明，此处取Kvp=1:0.2较合适。（6）研究了不同控制模式下大惯量系统的低速特性。泄油式阀控或泄油式并联阀控通过增加可控的泄漏，增大系统的阻尼比，以增强低速平稳性，而且由阀控泄漏引起的阻尼比的增加，可补偿因摩擦负斜率（Stribeck效应）引起的阻尼比的下降，进一步增强了系统的低速稳定性。阀初始电压对提高低速特性至关重要，建立了阀初始电压的理论公式，并研究了不同油温，不同开口对系统低速特性的影响，获得了泄油式阀控在启停低速阶段的控制规律，同时实验表明，只要阀初始电压设置在理论值附近，均能获得满意的低速特性，这使泄油式阀控具有操作性和实用性，且此处取Kvp=1:0.1较合适。（7）建立了阀-泵并联变结构调速系统的AMEsim仿真模型以及基于虚拟仪器技术的实验系统，研究了一个调速周期内的阀-泵并联变结构调速特性。仿真与实验结果表明，在调速过程中，不同控制模式之间切换平滑连续，阀和泵的工作状态符合预期；通过改变不同调速阶段的控制模式，实现了大功率液压马达调速系统的综合性能，即在低速段采用泄油式并联阀控，实现了大惯量的平稳快速启停，在高速段采用补油式并联阀控，实现了对负载干扰的快速调节，在加速和减速段泵提供主要流量，充分了发挥泵控的高效的优势。阀-泵并联变结构控制，利用阀控及泵控双通道，建立了控制结构(模式)依控制要求而变的灵活的控制机制，通过改变阀-泵权重比，使阀控与泵控协调工作，充分发挥了阀控、泵控各自的优势，丰富了液压系统的调速方式，使电液控制系统更具灵活性和适应性，可实现大功率液压调速系统的综合性能，如低速平稳快速启停、快速调节负载干扰、全程高效率。
[Abstract]:The traditional hydraulic motor speed regulation system has two basic forms : valve control and pump control , the valve control response is fast but the efficiency is low , it is suitable for occasions with high speed requirement . The main work and research results of the thesis are as follows : ( 1 ) The working principle and characteristics of the current valve - pump joint control system at home and abroad are summarized and analyzed , and it is pointed out that the current valve - pump joint control mode is difficult to achieve the above - mentioned comprehensive performance . ( 2 ) The valve - pump parallel variable structure speed regulating system is designed . The key points are two points . One is that the valve can be in the two states of oil filling or oil drain according to the control requirements , so as to make the system be in the two control modes of feeding oil or oil drain valve - pump in parallel . The parameters of the system are analyzed , and it is pointed out that the traditional pump control system is changed with the valve control , the damping ratio of the system is obviously increased and the system damping ratio changes with the working point of the valve ( valve opening and system pressure ) , and the system rigidity is reduced , and the load interference is easy . ( 3 ) The structure of the open and closed valve - pump parallel variable structure control system is designed , the flow balance equation of the closed system is established , and the relationship between the flow rates is analyzed . It is pointed out that in the closed valve - pump parallel variable structure speed regulation system , the oil feeding circuit and the flushing circuit are necessary , and the simulation system can be configured according to three parameters of the pump displacement , the motor displacement and the moment of inertia in the closed valve - pump parallel variable structure speed regulation system . ( 4 ) The concept of valve - controlled weighting and pump - control weights is put forward , and the relation between traditional pump control , valve - control and parallel control of valve - pump is established according to different kinds of KV and KP . In order to judge the function of valve and pump in joint speed regulation , the concept of valve - pump weight ratio is established , that is , Kvp = KV : KP , and the control mode of the system is discriminated by the weight ratio and the valve control state . ( 5 ) The effect of different weight ratios on the control characteristics is studied , the effect of different weight ratios on the control characteristics is studied , and the valve - pump parallel control is faster than that of the valve - pump control . ( 6 ) The low - speed characteristics of the large inertia system in different control modes are studied . By increasing the controllable leakage , the damping ratio of the system can be increased by increasing the damping ratio of the system , so that the low - speed stability of the system is enhanced . ( 7 ) The simulation model of valve - pump parallel variable structure speed control system is established and the experiment system based on virtual instrument technology is established . The simulation and experimental results show that the switching between different control modes is consistent with the expectation in the process of speed regulation . By changing the valve - pump weight ratio , the valve control and pump control coordination work is established , the valve control and the pump control coordination work are fully exerted , the speed regulation mode of the hydraulic system is fully exerted , the comprehensive performance of the high - power hydraulic speed regulation system can be realized , such as low - speed smooth start - stop , rapid adjustment of load interference and full - process efficiency .

【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH137.51

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