中型挖掘机正流量控制技术的研究

【作者】 仉志强；

【导师】 贾跃虎；

【作者基本信息】 太原科技大学 ， 机械电子工程， 2011， 硕士

【摘要】 国家基础建设推动了挖掘机行业的蓬勃发展,机电液基础技术和几十年挖掘机行业技术的积累为挖掘机技术的提高准备了条件,不断加剧的市场竞争和国家对节能减排的要求以及国家对重大装备业的资助直接推动了挖掘机新技术的研发。在该背景下,论文选取22T中型挖掘机为对象,对正流量控制进行了研究,主要内容如下:(1)简述了国内挖掘机行业的发展状态和液压控制研究意义。介绍国内外挖掘机重要发展时期和发展特点以及国内外目前的研究现状。介绍了挖掘机液压系统的发展内容、特点和趋势。对中型挖掘机正、负流量系统和负载敏感系统进行了对比分析,重点介绍了正流量控制系统的发展及特点。(2)简述了中型挖掘机的构成和复合动作等。介绍A8VO泵和M8阀等组成的液压系统的主要参数,液压件选型及其功能,并分析了三种典型回路(优先回路、合流回路和斗杆回路)。然后对挖掘机的主要耗能点进行了分析。(3)首次较全面地给出正流量系统控制的研究策略和具体方法。首先从快速性、可操作性和低能耗三个方面,提出并分析了六项评价目标(最大速度、可操作性、摆角速度比α、流量分配优先系数β、节流损失ω和势能回收率η)。确定了以双折线段式速度曲线作为整个系统稳态流量设计的基础。根据正流量控制原理和双泵双回路系统特点,建立了四大机构工作时系统流量供需表。建立了主泵和主阀实用控制模型。分析了机构和液压系统的动态响应速度并对液压系统内泵阀响应进行了分析,并提出了改进思路和措施。(4)从主阀节流调速和主泵的容积调速两个方面展开研究。研究了主阀的行程面积函数、中位回油阀控制原则和优先阀的设计。利用AMESIM分析软件,分析了泵—阀—缸单机构系统的正流量控制参数,然后对动臂下降机构运动与液压回路进行了详细建模和优化,得到了不同速度对应的双泵流量。以此为基础,计算得到四种机构(铲斗、斗杆、动臂和回转)任意复合速度对应的主泵流量。更多还原

【Abstract】 The nationwide infrastructure construction has contributed to the rapid development of the excavator industry. The mechanical, and hydro-electron technologies have laid the foundation for the upgrading of the excavator technology. And the increasingly fierce market competition and the requirement of the low carbon emission and the growing funding of the major equipment building on the part of the state have boosted the development of new technologies of excavators. Against this background, the 22T excavator is selected as the object of research, with special focus on the control of the positive flow. The contents of the thesis are as follows:(1) The state quo of the domestic excavator industry and the significance of the study of hydraulic control are briefed. The important stages of the development of the excavator industry, their features, and the present research state both home and abroad are analyzed The content, characteristics and trends of excavator hydraulic system development are also introduced. Three systems of medium-sized excavators (positive, negative flow system and the load sensing system) are analyzed comparatively, with special focus on the development and characteristics of the first .(2) The structure and compound actions of medium-sized excavators are outlined. Then the types and function of main hydraulic components are introduced and the main parameters of hydraulic system of M8 and A8VO are outlined. Then, three typical circuits (priority circuit, interfluent circuit and stick circuit) are analyzed. In the end, the main energy loss of the excavator system is analyzed.(3) The stragedy and methods for studying the positive system are presented. From the three aspects of rapidity, operability and low power consumption, six evaluating criteria (maximum speed, controlibility, angle and velocity valueαand the priority coefficientβ,throtting lossωand energy recovery ratioη) are put forward, establishing the double-slope line as the basis of the system flow control principle. Based on principles of positive flow control and characteristics of dual-pump-dual-loop system, the relation between flow requirement and demand is constructed. Then, the models of the main pump and main vavle are built. The dynamic response between mechanics and hydraulic system and that between the pump and valve are is analyzed and ways of improvement are suggested.(4) The study is carried out from throtting regulation of the main valve and the capacity regulation of the pump. The function of main vavle core movement and the principle of return oil valve and priority vavle are studied. In,the case of the single pump-valve-cylinder system, the positive flow parameters are analyzed by AMESIM. Then the boom falling movement is modeled and optimized in detail, the pump flow at different speeds of falling is obtained. On that basis, the pump flow at any speed of the four mechanisms (bucket, arm, boom and slewer) are calculated.更多还原