液压挖掘机多路阀内流阻分析与流道结构优化

发布时间：2018-02-28 03:51

本文关键词： 挖掘机液压系统负流量-恒功率控制多路阀流动阻力侧向力流道结构优化　出处：《兰州理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：整体式多路阀内部流道结构复杂,在挖掘机作业时存在阀口的节流损失和阀内部流道的阻力损失,造成了一定的能量消耗。本文根据液压挖掘机实际双泵合流和单泵供油工况,针对挖掘机快速提臂、动臂下降和铲斗内收动作,考虑多路阀节流口和内部流道结构,应用AM-ESim和FLUENT软件联合仿真,研究整体式多路阀内部流动阻力损失情况及其主要发生部位,分析双泵合流工况下动臂阀芯所受较大侧向力的原因,从减小阀内部流动阻力损失和阀芯侧向力不平衡的问题入手,对流道结构进行优化。本研究对于深入理解多路阀内部流动阻力损失和流道结构的优化具有普遍的指导意义。主要内容如下：第1章,阐述了本论文研究的背景和意义；简单介绍了液压挖掘机液压系统的几种流量控制方式；概括了本文的主要研究内容。第2章,结合变量泵压力流量特性曲线,分析液压挖掘机负流量—恒功率控制系统的原理以及动臂、铲斗动作的工作原理,并对六通多路阀—负流量控制泵系统的控制模型进行了分析。根据变量泵的压力—流量曲线数学表达式,利用AMESim中超级元件将数学表达式进行封装完成变量泵模型。将动臂阀和铲斗阀的阀口面积—阀芯位移曲线,通过文本形式导入到带有节流槽的滑阀基本模块中完成多路阀的AMESim模型。多路阀先导压力控制信号为系统输入信号,最后完成挖掘机动臂、铲斗回路液压系统模型,基于仿真模型分析挖掘机快速提臂、动臂下降、铲斗内收单独动作时的系统动态特性,以及得到各单独动作时多路阀相关的压力流量数值,为第三章多路阀内流阻计算分析提供数据依据。第3章,根据液压挖掘机实际双泵合流工况下的动臂快速提升动作和单泵供油工况下的动臂下降、铲斗内收动作,考虑多路阀节流口和内部流道结构,应用FLUENT软件,对多路阀内部流场进行解析,研究整体式多路阀内部流动阻力损失情况及其主要发生部位。结果表明：快速提臂双泵合流时多路阀内流动阻力达2.6MPa,阻力主要发生在合流窗口、节流口和直弯流道处；发现合流窗口处高速液流冲击其后阀芯及阀腔,高速液流交汇增大了流动阻力,改变了阀腔内压力分布使阀芯受到较大的侧向力。动臂下降和铲斗内收单泵供油时多路阀内流动阻力损失比较小,阻力损失主要发生在阀口部位。第4章,计算得到在单独动作时动臂阀和铲斗阀液压侧向力的大小。针对快速提臂双泵合流时侧向力产生的原因和阻力损失发生的部位,优化阀体流道结构,将优化后的流道进行流场计算分析,结果表明：优化后双泵合流时内部流动阻力损失为1.5MPa,比优化前阻力损失减小1.1MPa,动臂阀1存在的侧向力为96N,比优化前侧向力减小24N。最后,对本论文的研究工作和成果进行了总结,展望了下一步的研究工作。
[Abstract]:The internal flow channel structure of the monolithic multi-way valve is complex, the throttling loss of the valve and the resistance loss of the internal passage of the valve exist in the operation of the excavator, which results in a certain energy consumption. In this paper, according to the actual conditions of the double pump conjunct flow and the single pump oil supply of the hydraulic excavator, In view of the quick lifting arm of excavator, the drop of moving arm and the lifting action of bucket, considering the structure of throttle and internal flow channel of multi-way valve, the internal flow resistance loss and its main place of occurrence of integral multi-way valve are studied by using AM-ESim and FLUENT software. This paper analyzes the causes of the larger lateral force on the movable arm valve core under the combined flow condition of two pumps, and starts with the problems of reducing the loss of flow resistance inside the valve and the imbalance of the lateral force of the valve core. This study is of general significance for understanding the internal flow resistance loss and the optimization of the flow channel structure of the multi-channel valve. The main contents are as follows:. In chapter 1, the background and significance of this paper are described, several flow control methods of hydraulic system of hydraulic excavator are briefly introduced, and the main research contents of this paper are summarized. In chapter 2, the principle of negative flow-constant power control system of hydraulic excavator and the working principle of moving arm and bucket are analyzed in combination with the pressure and flow characteristic curve of variable pump. The control model of the six-way multi-way valve-negative flow control pump system is analyzed. According to the mathematical expression of the pressure-flow curve of the variable pump, The mathematical expression is encapsulated in AMESim to complete the variable pump model. The area of valve orifice and valve core displacement curve of arm valve and bucket valve are analyzed. The AMESim model of the multi-channel valve is completed by introducing the text form into the basic module of the slide valve with throttling slot. The pilot pressure control signal of the multi-channel valve is the input signal of the system. Finally, the hydraulic system model of the excavator arm and bucket loop is completed. Based on the simulation model, the system dynamic characteristics of the excavator with quick lifting arm, falling arm, and separate action of bucket are analyzed, and the pressure and flow values related to multi-way valves are obtained. It provides the data basis for the calculation and analysis of the internal flow resistance of the multi-way valve in chapter 3. In chapter 3, according to the quick lifting action of the moving arm under the actual double pump combined flow condition of hydraulic excavator and the drop of the moving arm under the condition of single pump oil supply, and the action of lifting the bucket, considering the structure of the multi-way valve throttle and the internal runner, the FLUENT software is used. The internal flow field of multi-way valve is analyzed, and the internal flow resistance loss and its main position are studied. The results show that the flow resistance in multi-way valve is 2.6 MPA when the quick lifting double pump flows together, and the resistance mainly occurs in the confluence window. It is found that the high speed liquid flow at the confluence window impinges on the valve core and the valve cavity, and the intersection of the high speed liquid flow increases the flow resistance. By changing the pressure distribution in the valve chamber, the valve core is subjected to a larger lateral force. The flow resistance loss in the multi-way valve is relatively small when the arm drops and the single pump in the bucket is fed, and the resistance loss mainly occurs at the valve orifice. In chapter 4, the hydraulic lateral force of the arm valve and bucket valve is calculated when the valve is acting alone. Aiming at the cause of the lateral force and the position of the resistance loss, the structure of the valve body passage is optimized in view of the cause of the side force and the position of the resistance loss in the close flow of the quick lift arm double pump. The flow field of the optimized flow channel is calculated and analyzed. The results show that the internal flow resistance loss is 1.5 MPA, which is 1.1 MPA lower than that before optimization, and the lateral force of arm valve 1 is 96 Ns, which is 24Ns less than that of optimized forward side force. Finally, the research work and results of this paper are summarized, and the next research work is prospected.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU621

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