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.     

新型恒流量轴向柱塞泵的理论分析及数值仿真

轴向柱塞液压泵的流量脉动、振动和噪声一直是液压泵领域研究的热点问题。提出用正圆柱螺旋面替代斜面的方法,分别用左旋面和右旋面对应吸油窗口和压油窗口,在此基础上设计反向错位双联泵的结构,即两个泵的螺旋面相背或相对,封油区相差一定相位,目的是设计出一种恒流量输出的轴向柱塞泵。通过MATLAB数值仿真确定关键参数,得出采用8根柱塞为基础的轴向柱塞液压泵进行反向错位双联,错位角为22.5°,此新型恒流量轴向柱塞泵在工作时瞬时流量值不变,输出流量恒定且输出流量值显著提高。     

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。     

双排式轴向柱塞泵柱塞的受力与分析

柱塞的受力状况影响到双排式轴向柱塞泵的效率和寿命,是设计中的关键环节.柱塞随缸体旋转时受到离心力的作用,由于柱塞的质量中心与转动中心不重合,离心力引起柱塞的翻转.通过对柱塞的受力分析,确定了柱塞受力特性,该研究不仅对克服双排式轴向柱塞泵缸体所受的倾覆力矩和防止缸体倾斜提供了计算结果,而且为柱塞的选择给出了设计依据.     

双定子力平衡轴向柱塞泵及其流量波动性分析

为实现一泵多级流量输出且不用减压阀实现一泵多压,设计了双定子力平衡轴向柱塞泵。介绍了其结构特点与工作原理,推导出该泵在不同工况下的理论排量、理论瞬时流量及合流量不均系数,分析了不同柱塞数对泵输出特性的影响以及滞后角对输出合流量的影响。结果表明：该泵能实现两种不同流量的输出;随柱塞的增多,其瞬时流量脉动性递减;当两单泵的柱塞数相同且均为奇数时,输出流量品质最高;合理控制滞后角可有效改善泵的波动性。     

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.     

柱塞倾角对球面配流副轴向斜柱塞泵流体特性的影响

运用CFD技术对球面配流副轴向斜柱塞泵的单柱塞腔内压力脉动、输出流量脉动以及配流盘对缸体作用力矩等重要性能进行研究,分析柱塞倾角与上述流体特性的关系,得到柱塞倾角对柱塞泵流体特性的影响规律。     

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。     

基于虚拟样机的轴向柱塞泵动态特性仿真研究

为研究轴向柱塞泵的动态特性,理论分析了其运动特性和流量脉动特性,并基于ADAMS与AMESim软件建立了某型柱塞泵的虚拟样机模型。通过联合仿真得到了不同转速下的柱塞位移、速度、加速度曲线,不同转速、斜盘倾角下的流量脉动曲线,以及不同负载下的传动轴转矩、泵出口压力曲线。研究结果表明:为减小柱塞泵的振动与噪声,其转速应限制在一定范围内;适当提高转速、减小斜盘倾角可减小流量脉动。研究结果可为柱塞泵结构优化提供参考依据。     

正开口配流盘轴向柱塞变量泵输出特性预测

为了准确地预测正开口式斜盘轴向柱塞泵的流动特性,通过对单个柱塞的运动特性、过流面积、密封带、泄漏等重要影响因素进行分析。在此基础上,用MATLAB编程建立柱塞以及柱塞泵的流动特性方程,并且绘制过流面积曲线和密封带曲线。在输入结构参数后对柱塞泵流动特性进行仿真和分析,得到在不同转速以及压力条件下的泵的输出流量特性。通过比较分析可知,配流副之间的泄漏、滑靴副之间的泄漏、柱塞副之间的泄漏和三角槽的流量损失是影响柱塞泵容积效率的关键因素。当柱塞泵的出口压力增大时,泵的输出流量会有略微的下降,流量不均匀系数增加,容积效率下降,主要原因是由于出油口压力的增大使得摩擦副之间的泄漏量以及三角槽损失的流量增加。     

A study on the pressure ripple characteristics in a bent-axis type oil hydraulic piston pump

To improve the performance of a bent-axis type axial piston pump driven by tapered pistons, it is necessary to know the pressure ripple characteristics. The purpose of this paper is to understand the effect on the pressure ripple characteristics, and to predict by comparing experimental and theoretical analysis results. The simulation model of a bent-axis type axial piston pump is developed in the AMESim environment using the geometrical dimension, and the driving mechanism of the piston pump, such as the stroke of pump, the velocity of piston, the instantaneous volumetric flow, the overlap area of valve plate opening to cylinder bore, the angle of notch, and so on. The results show that theoretical analysis results of the bent-axis type axial piston pump by using the AMESim approximate the pressure ripple characteristic of the test pump, and through this, simulations can be obtained that predict the performance characteristics of a bentaxis type axial piston pump.     

变排量非对称轴向柱塞泵动态特性分析

为研制变排量非对称轴向柱塞泵,依据三配流窗口轴向柱塞泵的配流思想,提出基于斜盘摆角位置反馈的排量控制方案,建立变排量非对称轴向柱塞泵的数学模型,对其频率响应影响因素进行分析。通过AMESim对该泵的变排量特性进行研究,仿真结果表明：当配流窗口A吸油、配流窗口B和T排油时,柱塞对斜盘的合力作用点轨迹具有较长的作用力臂,若配流窗口B和T压差过大,则斜盘摆角减小时响应将显著降低;当配流窗口B和T吸油、配流窗口A排油时,柱塞对斜盘的合力作用点轨迹与对称式轴向柱塞泵相似,配流窗口A压力对斜盘响应影响较小。通过试验验证了仿真模型的正确性,同时试验表明该泵具有较好的动态特性。     

水介质液压泵锥形轴配流副轴承间隙的计算

以水介质轴向柱塞液压泵的锥形轴配流副为研究对象,对其在稳定工作状态下形成的滑动轴承的径向间隙计算方法进行了研究。采用等效结构参数法将配流副滑动轴承化为轴向推力轴承,根据柱塞轴向液压交变作用力引起轴承内水膜的变化特征推导出水膜厚度变化的速度,再依据锥顶体薄膜挤压效应公式计算出了轴承的径向间隙,结果表明径向间隙是柱塞泵工作压力和配流副结构参数的函数。     

Flow Ripple of Axial Piston Pump with Computational Fluid Dynamic Simulation Using Compressible Hydraulic Oil

The flow ripple, which is the source of noise in an axial piston pump, is widely studied today with the computational fluid dynamic(CFD) technology development. In the traditional CFD modeling, the fluid compressibility, which strongly influences the accuracy of the flow ripple simulation results, is often neglected. So a compressible sub-model was added with user defined function(UDF) in the CFD model to predict the flow ripple. At the same time, a test rig of flow ripple was built to study the validity of simulation. The flow ripple of pump was tested with different working parameters, including the rotation speed and the working pressure. The comparisons with experimental results show that the validity of the CFD model with compressible hydraulic oil is acceptable in analyzing the flow ripple characteristics. In this paper, the improved CFD model increases the accuracy of flow ripple rate to about one-magnitude order. Therefore, the compressible model of hydraulic oil is necessary in the flow ripple investigation of CFD simulation. The compressibility of hydraulic oil has significant effect on flow ripple, and the compression ripple takes about 88% of the total flow ripple of pump. Leakage ripple has the lowest proportion of about 4%, and geometrical ripple leakage ripple takes the remnant 8%. Besides, the influence of working parameters was investigated through the CFD simulations and experimental measurements. Comparison results show that the amplitude of flow ripple grows with the increasing of rotation speed and working pressure, and the flow ripple rate is independent of the rotation speed. However, flow ripple rate of piston pump grows with the increasing of working pressure, because the leakage ripple will increase with the pressure growing. The investigation on flow ripple of an axial piston pump using compressible hydraulic oil provides a more validity simulation model for the CFD analyzing and is beneficial to further understanding of the flow ripple characteristics in an axial piston pump.     

水压柱塞泵配流盘阻尼槽结构优化及试验研究

针对水压柱塞泵U形阻尼槽的结构参数进行研究,通过流场仿真对比不同阻尼槽结构参数下水压柱塞泵的流量特性,确定水压柱塞泵的压力、流量脉动率最优的阻尼槽结构参数,从而降低水压柱塞泵的流体振动。仿真结果表明,在现有结构参数下当水压柱塞泵阻尼槽宽度设置为2mm、深度为0.8mm、配流盘预升/泄闭死压角为11.8°时,柱塞泵的压力和流量脉动率最小。开展了水压柱塞泵的振动试验,对比了阻尼槽优化前后的试验数据,试验结果表明优化后的阻尼槽结构能够有效降低水压柱塞泵的振动。     

清洗机斜盘柱塞泵运动特性分析

选择普遍应用于清洗机产品的并联斜盘轴向柱塞泵为研究对象,根据其工作原理建立斜盘柱塞泵运动数学模型,并利用数值仿真软件对斜盘柱塞运动机构进行运动分析,得到柱塞轴向位移、速度、加速度的数值仿真结果。通过对比从单缸到五缸的并联斜盘轴向柱塞泵集成速度数值仿真结果,从运动学分析的角度定量验证了传统设计理论中奇数缸数并联速度脉动小于偶数缸数并联速度脉动的定性结论。     

Impact of Typical Steady-state Conditions and Transient Conditions on Flow Ripple and Its Test Accuracy for Axial Piston Pump

The current research about the flow ripple of axial piston pump mainly focuses on the effect of the structure of parts on the flow ripple. Therein, the structure of parts are usually designed and optimized at rated working conditions. However, the pump usually has to work in large-scale and time-variant working conditions. Therefore, the flow ripple characteristics of pump and analysis for its test accuracy with respect to variant steady-state conditions and transient conditions in a wide range of operating parameters are focused in this paper. First, a simulation model has been constructed, which takes the kinematics of oil film within friction pairs into account for higher accuracy. Afterwards, a test bed which adopts Secondary Source Method is built to verify the model. The simulation and tests results show that the angular position of the piston, corresponding to the position where the peak flow ripple is produced, varies with the different pressure. The pulsating amplitude and pulsation rate of flow ripple increase with the rise of pressure and the variation rate of pressure. For the pump working at a constant speed, the flow pulsation rate decreases dramatically with the increasing speed when the speed is less than 27.78% of the maximum speed, subsequently presents a small decrease tendency with the speed further increasing. With the rise of the variation rate of speed, the pulsating amplitude and pulsation rate of flow ripple increase. As the swash plate angle augments, the pulsating amplitude of flow ripple increases, nevertheless the flow pulsation rate decreases. In contrast with the effect of the variation of pressure, the test accuracy of flow ripple is more sensitive to the variation of speed. It makes the test accuracy above 96.20% available for the pulsating amplitude of pressure deviating within a range of ?6% from the mean pressure. However, with a variation of speed deviating within a range of ?2% from the mean speed, the attainable test accuracy of flow ripple is above 93.07%. The model constructed in this research proposes a method to determine the flow ripple characteristics of pump and its attainable test accuracy under the large-scale and time-variant working conditions. Meanwhile, a discussion about the variation of flow ripple and its obtainable test accuracy with the conditions of the pump working in wide operating ranges is given as well.