新型轴向双排柱塞泵的研究

轴向柱塞泵的自身结构决定了其工作过程中必然产生流量脉动现象.在液压泵相同的体积和流量条件下,改进轴向柱塞泵内部结构,即将轴向柱塞泵的单排柱塞改进成双排柱塞.通过改变液压泵内部结构和理论研究,研制出一种新型的柱塞泵--轴向双排柱塞泵,并以此新式机构为切入点对其工作性能进行了分析与研究.     

四配流窗口轴向柱塞泵仿真与分析

四配流窗口轴向柱塞泵可以实现单台泵同步闭式控制两台对称执行元件液压系统,也可以直接闭式控制差动缸回路。为分析其压力、流量特性,该文根据柱塞运动特征和配流面积变化原理,运用Simulation X软件对四配流窗口轴向柱塞泵进行了建模和仿真分析。通过设置斜盘角度或转速调节液压泵输出流量,考虑油液泄漏和黏性摩擦力的情况下,对加载和空载时液压泵柱塞腔和泵油口的压力、流量等特征响应曲线进行分析。仿真结果表明,流量脉动频率随泵转速增加而增大;压力脉动幅值随负载增加而增大,且压力脉动频率与负载无关。     

工作参数对斜柱塞轴向柱塞泵流量特性的影响

针对斜柱塞轴向柱塞泵流量特性随工况参数变化而变化的特点,以A4VSO40变量斜柱塞轴向柱塞泵为研究对象,依据其工作过程中柱塞的空间位置关系,建立了其运动学方程,阐明了其单柱塞位移、速度等变量与斜柱塞轴向柱塞泵结构参数之间的关系,再利用AMESim平台,搭建出斜柱塞轴向柱塞泵仿真模型,深入分析了斜盘倾角、主轴转速、工作压力对其流量脉动特性的影响,其结果表明,主轴转速与斜盘倾角增大,其平均流量和脉动幅值增大,但脉动率减小;工作压力增大,其平均流量、脉动幅值、脉动率都减低。     

流量均匀、液压力平衡的轴向柱塞泵理论研究

鉴于传统的斜盘式和斜轴式轴向柱塞泵存在流量脉动和由此产生的压力脉动,且存在轴向液压力(力矩)不平衡,该文提出一种理论流量均匀、液压力平衡的轴向柱塞泵,指出了实现轴向柱塞泵流量均匀的必要条件,同时对该柱塞泵的配流副情况进行了分析,从理论上证明是可以实现液压力(力矩)平衡的,完善其基本理论,同时也为该类轴向柱塞泵的设计提供理论基础.     

双排式轴向柱塞泵流量脉动特性研究

为了研究双排式轴向柱塞泵的流量脉动特性,对双排式轴向柱塞泵柱塞的排列方式进行了分类,列写流量方程并计算不同错位角下柱塞泵的流量不均匀系数,分析柱塞排列方式和错位角的变化对双排式轴向柱塞泵流量脉动特性的影响。研究发现内外排柱塞数相同且同为奇数时,改变错位角得到的最小流量不均匀系数小于同等柱塞数的单排式轴向柱塞泵的流量不均匀系数,双排式轴向柱塞泵的流量脉动特性得到显著改善。同时还发现内外排柱塞数均为5,且错位角为π/10的双排式轴向柱塞泵具有较小的流量脉动,是一种比较理想的选择。     

直线电机驱动水液压柱塞泵运动规划及仿真分析

水液压柱塞泵是水液压系统的关键元件,由于水介质的理化特性差异导致其泄漏、摩擦磨损、腐蚀、气蚀等现象比油压柱塞泵严重,为解决传统斜盘式水液压柱塞泵流量脉动大的问题,提出了一种新型的直线电机驱动水液压柱塞泵结构。通过研究恒流量直线电机驱动柱塞泵的可行运动规划,选取了直线电机以三角波间隔T/4相位差的运动方案,以实现双直线电机双作用水压柱塞泵实际输出较小的流量脉动。应用AMESim软件,构建了两种不同配流方式的双直线电机双作用柱塞泵系统的仿真模型。仿真发现,柱塞配流电机柱塞泵相比阀配流,其压力和流量脉动很小,其压力脉动幅度小于2%,流量脉动率仅为0.008。     

锥形缸体斜盘式轴向柱塞泵腔内压力特性研究

针对锥形缸体轴向柱塞泵工作时,柱塞腔内油液体积急剧变化,腔内产生的压力脉动和压力冲击会造成柱塞泵振动以及噪声的问题,采用了AMESim建立锥形缸体柱塞泵模型的方法,研究了斜盘倾斜角度和油液的可压缩性及粘性对柱塞腔内压力的影响特性.首先,分析了A4VSO锥形缸体柱塞泵的工作原理和运动学关系,以及柱塞腔内压力的理论分析;其...     

柱塞闭死容积对柱塞泵出口流量脉动的研究

针对某型号轴线柱塞泵,分别从封闭中空柱塞和空心柱塞的角度,建立了轴向柱塞泵AMESim和Simerics MP+配流副仿真模型,分析了两种不同闭死容积的柱塞对柱塞泵出口流量脉动的影响,得出封闭中空柱塞通过减小柱塞腔闭死容积,能有效降低柱塞泵出口流量脉动,对柱塞泵减振降噪具有重要的指导意义.     

双斜盘阀配流轴向柱塞式液压电机泵配流特性和变量原理的研究

提出一种有别于常规阀配流泵的"斜盘转动而缸体不动"而采用缸体和配流阀一起旋转的双斜盘阀配流轴向柱塞式液压电机泵。建立该泵配流机构的数学模型,研究各种结构参数和工作参数对配流特性的影响,尤其是配流阀芯所受离心力对配流特性的影响。以仿真模型和得出的单个柱塞腔的压力响应曲线和输出流量曲线为基础,研究该类型泵流量脉动和侧向力脉动的特点,得出随着泵的工作转速增加,流量脉动和侧向力脉动都增大,当柱塞数量足够多时,柱塞数量的奇偶性在影响流量脉动上没有明显的区别,偶数个柱塞比奇数个柱塞产生的侧向力脉动要大。提出一种新型的阀配流轴向柱塞泵的变量调节方式,并研究该变量方式的原理和调节特性。样机泵的试验结果表明该泵的工作原理可行,进而展望双斜盘阀配流轴向柱塞式液压电机泵的应用前景。     

单柱塞泵流量压力输出特性研究

现有的柱塞泵一般采用1个缸体同时集成多个柱塞,多个柱塞通过缸体耦合在一起,不能独立控制,多个柱塞只能按某特定规律运动,共同完成吸油和排油。在工作中,存在高效区域无法随负载动态调整和单液压泵不能同时输出多级压力匹配不同负载需求的缺点,为此提出一种矩阵式多单柱塞泵重组液压驱动系统。针对所提出新型液压驱动系统的前期探索研究,分析单柱塞泵流量压力输出特性,在详细阐述单柱塞泵结构特点的基础上,研究了单柱塞泵的工作原理。通过AMESim建立单柱塞泵的流量压力仿真模型,分析单柱塞泵的机电液的耦合特性和流量压力输出特性,讨论蓄能器和单柱塞泵的液压耦合特性,最后通过实验研究对单柱塞泵的特性进行验证。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.