Dynamic Modeling of Floating Valve Plate Motion in an Axial Piston Pump

The objectives of this study were to analytically and experimentally investigate the motion of the floating valve plate in an axial piston pump under various operating conditions. To achieve the objectives of the analytical investigation, the equations of motion for the valve plate were coupled with a time-dependent lubrication model. The balance pistons that support the floating valve plate were represented by equivalent spring and dashpot systems. The system of equations was then solved using the Runge-Kutta and the control volume finite difference methods to determine the pressure, film thickness, and motion of the valve plate for various operating conditions. To achieve the experimental objectives, a previously developed axial piston pump test rig was instrumented with proximity probes to measure the motion of the valve plate. The stiffness and damping of the balance pistons supporting the floating valve plate were determined using the impact and frequency response methods. Using the experimentally determined stiffness and damping coefficients in the coupled dynamic lubrication model, the analytical and experimental results of the valve plate motions were compared. The model was then used to conduct a parametric study to determine the overall system stiffness and damping coefficients during pump operation. Using the stiffness and damping coefficients from the parametric study in the dynamic lubrication model, the pressure, film thickness, and motion of the valve plate were calculated for various operating conditions. The experimental and analytical displacements of the valve plate were then corroborated and found to be in good agreement.     

轴向柱塞泵配流副润滑特性的研究进展

介绍了国内外有关轴向柱塞泵配流副润滑特性方面的研究成果，并进行了综合分析和比较。指出需借鉴国外现有的关于轴向柱塞泵配流副压力分布规律的理论，确定最佳剩余压紧系数，现有的配流副结构设计方法和理论依据需进一步完善。建立了轴向柱塞泵配流副润滑特性试验平台，可在不同压力、温度、转速、结构下测试配流副间隙并得出配流副润滑膜的形成及变化规律。通过润滑特性测试平台还可以确定最佳水液压柱塞泵配流副润滑结构和材料配对，为研制出性能良好的轴向柱塞式水液压泵奠定实验基础。     

Relation between pressure variations and noise in axial type oil piston pumps

Pressure variation is one of the major sources on noise emission in the axial type oil piston pumps. Therefore, it is necessary that the pressure variation characteristics of the oil hydraulic piston pumps be clarified to reduce the pump noise. Pressure variations in a cylinder at the discharge region and the pump noise were simultaneously measured with discharge pressures and rotational speeds during the pump working. To investigate the effects of the pre-compres-sion and the V-notch in the valve plate, we used the three types of valve plates. In this research, it is clear that the pressure variation characteristics of axial type oil piston pumps is deeply related to the pre-compression and to the V-notch design in valve plate. Therefore, we could reduce the pump noise by using the appropriate pre-compression angle and the notch design that are between the suction port and the discharge port in valve plate.     

Measurement of fluid film thickness on the valve plate in oil hydraulic axial piston pumps (I)-bearing pad effects-

The tribological mechanism between the valve plate and the cylinder block in oil hydraulic axial piston pumps plays an important role on high power density. In this study, the fluid film thickness between the valve plate and the cylinder block was measured with discharge pressure and rotational speed by use of a gap sensor, and a slip ring system in the operating period. To investigate the effect of the valve plate shapes, we designed two valve plates with different shapes : the first valve plate was without a bearing pad, while the second valve plate had a bearing pad. It was found that both valve plates behaved differently with respect to the fluid film thickness characteristics. The leakage flow rates and the shaft torque were also experimented in order to clarify the performance difference between the valve plate without a bearing pad and the valve plate with a bearing pad. From the results of this study, we found out that in the oil hydraulic axial piston pumps, the valve plate with a bearing pad showed better film thickness contours than the valve plate without a bearing pad.     

Measurment of fluid film thickness on the valve plate in oil hydraulic axial piston pumps (Part II: Spherical design effects)

Tribologtcal characteristics in the sliding parts of oil hydraulic piston pumps are very important in increasing overall efficiency In this study, the fluid film between the valve plate and the cylinder block was measured by using a gap sensor and the mercury-cell slip ring unit under real working conditions To investigate the effect of the valve shape, we designed three valve plates each having a different shape One of the valve plates was without bearing pad, another valve plate had bearing pad and the last valve plate was a spherical valve plate It was noted that these three valve plates observed different aspects of the fluid film characteristics between the cylinder block and the valve plate The leakage flow rates and the shaft torque were also investigated in order to clarify the performance difference between these three types of valve plates From the results of this study, we found that the spherical valve plate estimated good fluid film patterns and good performance more than the other valve plates in oil hydraulic axial piston pumps     

浮杯原理及其在液压系统中的应用研究

浮杯原理是继斜盘式和斜轴式之后一种新的轴向柱塞概念,将现有泵原理的优点结合在了一起。最显著特征是结构镜像对称设计以及柱塞固接在转子上,且每个活塞对应一个独立的杯状缸筒,它可以沿旋转斜盘面自由浮动。浮杯泵具有结构紧凑、质量小、泄漏小、受力平衡、力矩损失小、波动小、噪声小、效率高、生产成本低等优点。浮杯原理将被广泛应用在液压定量和变量泵、液压变压器和液压马达等方面。该文针对浮杯泵的研发现状、结构特点、优点等方面进行了详细的分析和梳理,对浮杯原理在定量/变量泵、液压变压器、液压马达的应用发展状况进行了介绍。该文将为浮杯泵的进一步研发及浮杯原理更广泛应用提供参考。     

超高压轴向柱塞泵缸体结构强度分析

液压泵是超高压液压传动系统的核心动力元件,其性能的好坏直接影响超高压液压系统的性能.以ANSYS软件为平台,针对超高压轴向柱塞泵缸体的结构强度分析,建立超高压轴向柱塞泵缸体的有限元模型,将轴向柱塞泵加压至120 MPa,进行缸体强度校核,发现缸体结构强度不达标,并通过试验验证了仿真的正确性;同时将缸体结构进行优化,得到...     

一种十字摆盘驱动式轴向柱塞泵结构设计

 轴向柱塞泵作为液压系统的核心动力元件,具有额定压力高、流量大、功重比高等优点,传统斜盘式柱塞泵结构复杂,易导致滑靴磨损,且柱塞与缸体之间具有较大的侧向力易造成柱塞卡死,影响柱塞泵的可靠性及寿命。提出了一种新型十字摆盘驱动式轴向柱塞泵结构,斜盘轴旋转驱动十字摆盘摆动回程,实现柱塞的往复运动,同时高低压配液阀实现流体介质的配流,完成柱塞吸排油动作。通过模型受力分析验证,该柱塞泵具有回程结构性能稳定、侧向力小等优点,应用前景广泛。     

斜盘轴向柱塞泵配流副流固耦合润滑机理研究

当斜盘轴向柱塞泵处于高压工况时，其配流盘会产生翘曲变形。基于弹性流体动力润滑理论，建立斜盘轴向柱塞泵配流副流固耦合模型，求解配流副润滑控制方程，分析了斜盘轴向柱塞泵缸体转速、缸体倾角、液压油黏度、配流副油膜厚度、配流副密封带宽度等工况与结构参数对其配流盘发生翘曲变形的影响。研究显示：斜盘轴向柱塞泵配流盘变形云图以腰形槽中心连线为轴线呈现一定的对称分布；配流盘高压侧外密封带区域变形最大，配流盘低压侧外密封带区域变形最小；在相同工况下，配流盘的材料与结构影响配流副油膜厚度与形状。     

Output characteristics of a series three-port axial piston pump

Driving a hydraulic cylinder directly by a closed-loop hydraulic pump is currently a key research area in the field of electro-hydraulic control technology,and it is the most direct means to improve the energy efficiency of an electro-hydraulic control system.So far,this technology has been well applied to the pump-controlled symmetric hydraulic cylinder.However,for the differential cylinder that is widely used in hydraulic technology,satisfactory results have not yet been achieved,due to the asymmetric flow constraint.Therefore,based on the principle of the asymmetric valve controlled asymmetric cylinder in valve controlled cylinder technology,an innovative idea for an asymmetric pump controlled asymmetric cylinder is put forward to address this problem.The scheme proposes to transform the oil suction window of the existing axial piston pump into two series windows.When in use,one window is connected to the rod chamber of the hydraulic cylinder and the other is linked with a low-pressure oil tank.This allows the differential cylinders to be directly controlled by changing the displacement or rotation speed of the pumps.Compared with the loop principle of offsetting the area difference of the differential cylinder through hydraulic valve using existing technology,this method may simplify the circuits and increase the energy efficiency of the system.With the software SimulationX,a hydraulic pump simulation model is set up,which examines the movement characteristics of an individual piston and the compressibility of oil,as well as the flow distribution area as it changes with the rotation angle.The pump structure parameters,especially the size of the unloading groove of the valve plate,are determined through digital simulation.All of the components of the series arranged three distribution-window axial piston pump are designed,based on the simulation analysis of the flow pulse characteristics of the pump,and then the prototype pump is made.The basic characteristics,such as the pressure,flow and noise of the pumps under different rotation speeds,are measured on the test bench.The test results verify the correctness of the principle.The proposed research lays a theoretical foundation for the further development of a new pump-controlled cylinder system.     

轴向柱塞泵缸体位姿机液一体化联合仿真

轴向柱塞泵在实际工作过程中会发生缸体倾覆现象,影响轴向柱塞泵的可靠性和寿命.为揭示缸体倾覆的原因,运用1D-3D联合仿真模型进行研究.分析了缸体x,y,z3个方向上的受力情况及动力学方程.搭建轴向柱塞泵1D液压系统模型以及3D多体动力学模型,并通过接口实现仿真模型间的数据交互,得到完整的机液一体化仿真模型.对于不同工况...     

基于SimulationX的斜盘柱塞泵的模拟仿真

该篇文章主要阐述了如何利用多学科仿真软件SimulationX建立斜盘柱塞泵,斜盘柱塞泵可以拆分为活塞,斜盘,配油盘吸油口及排油口,压力控制阀等。该模型集一维力学(包括流体力学)和三维力学于一体,在模型中可以考虑到象斜盘轴向力,柱塞离心力等现象。该文比较典型的显示了多学科仿真软件SimulationX的独特强大1D和3D一体的仿真功能。     

Analysis on the friction losses of a bent-axis type hydraulic piston pump

The design of an axial piston pump for electro-hydrostatic transmission systems requires accurate information where and how much the internal friction and flow losses are produced. This study is particularly focused on the friction losses of a bent-axis type hydraulic piston pump, aiming at finding out which design factors influence its torque efficiency most significantly. To this end, the friction coefficients of the pump parts such as piston heads, spherical joints, shaft bearings, and valve plate were experimentally identified by a specially constructed tribometer. Applying the experimental data to the equations of motion for pistons as well as to the theoretical friction models for the pump parts, the friction torques produced by them were computed. The accuracy of the computed results was confirmed by the comparison with the practical input torque of the pump. In this paper, it is shown that the viscous friction forces on the valve plate and input shaft bearing are the primary source of the friction losses of the bent-axis type pump, while the friction forces and moments on the piston are of little significance.     

球面配流对轴向柱塞泵性能影响的研究

为了对比分析球面配流与传统平面配流对轴向柱塞泵性能的影响,运用曲面造型技术建立基于球面配流的柱塞泵整体流域几何模型。在此基础上,采用动网格模拟缸体柱塞腔的轴向往复运动及旋转运动,利用计算流体动力学技术基于全空化模型对柱塞泵整体流域进行分析,分析了球面配流与平面配流对柱塞泵的压力流量脉动、空化现象等方面的影响。分析结果得出:在柱塞泵空化程度的影响方面二者差异很小,在配流过程中球面配流更加稳定,其压力、流量脉动率均优于平面配流。     

变排量非对称轴向柱塞泵控制性能分析

变排量非对称轴向柱塞泵直接控制非对称液压缸闭式系统具有能效高、结构紧凑等优势.针对变排量三配流窗口轴向柱塞泵存在变量阻力矩脉动大、斜盘倾角振荡频率高等问题,提出在变排量机构中增加阻尼孔以提高变排量控制性能的方案,推导了变排量控制系统的传递函数;通过AMESim仿真模型分别研究了有无阻尼孔情况下的斜盘倾角振荡、变量缸活塞...     

Improvement of the low-speed friction characteristics of a hydraulic piston pump by PVD-coating of TiN

The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large ume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so t the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed rication. The results showed that the friction torque of the valve plate mated with a TiN-coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test p was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to 40–50%.     

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。     

轴向柱塞泵在不同工况下的效率

该文分析并通过试验验证了液压轴向柱塞泵在不同温度、压力、转速及摆角工况其效率的变化情况。     

水压柱塞泵(马达)配流盘的研究与仿真

介绍了柱塞泵 (马达 )配流型式的发展 ,对水压轴向柱塞泵 (马达 )力矩全平衡型配流盘进行了分析。通过数字仿真研究了配流盘结构对柱塞腔内压力的影响 ,发现减振槽及其过流面积对气蚀的产生有直接的作用 ,合适的吸入口压力或背压可减小泵或马达发生气蚀的可能性     

某型航空液压柱塞泵压力脉动优化设计

为解决飞机液压能源系统中液压柱塞泵压力脉动带来的危害,保证航空液压系统的工作稳定性,防止管路系统的损坏,以某型航空液压柱塞泵为研究对象,提出了基于配流盘包角和缓冲瓶容积的柱塞泵压力脉动优化设计方法,探究了柱塞泵压力脉动产生机理与配流盘包角设计原理。基于AMESim软件进行了柱塞泵压力脉动仿真分析,并通过试验进行了验证。结果表明:2号配流盘和240 mL缓冲瓶组合的压力脉动优化效果最佳。