恒流量四缸径向往复式柱塞泵动力端运动学与仿真分析

在传统的四缸径向往复式柱塞泵动力端原理的基础上,提出了新的径向恒流量往复式柱塞泵动力端的方案。新柱塞泵动力端主要由四边形轨迹机构和变比传动机构组成。针对此动力端中存在的问题提出了解决方案。使用Creo软件建立其简化模型并进行仿真,结果表明,此恒流量柱塞泵动力端可以实现恒流量输出的目的。最后展望基于此动力端今后的研究方向。     

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。     

大流量阀配流式径向柱塞泵柱塞缸最大许用转速与作用次数研究

阀配流式径向柱塞泵相比其他类型柱塞泵具有结构简单,工作稳定可靠的特点,然而由于进出口阀的存在,阀口处液体流动受阻,主要工作单元柱塞缸存在自吸性能差的问题,当在特殊应用场合需要大流量化设计时,吸油性能恶化,导致吸油不完全而容积效率骤降。这里以径向柱塞泵中柱塞缸为研究对象,在大流量设计的需求下,综合径向柱塞泵考虑单作用与多作用情形,通过AMEsim对大流量柱塞缸许用转速与作用次数进行仿真实例研究,总结出针对大流量柱塞缸的最大许用转速与作用次数选值方法。该结论为后续阀配流式大流量径向柱塞泵的设计提供设计思路。     

平衡式径向柱塞泵的设计

进行了平衡式柱塞泵的理论分析,针对柱塞泵的运动情况,阐述了为实现柱塞泵的无流量脉动的柱塞的运动速度曲线所必须具备的特征,导出了几种常见的无流量脉动特征速度曲线,并设计了平衡式径向柱塞泵。     

某型径向柱塞泵配流轴的结构设计研究

针对径向柱塞泵的偏磨和"抱轴"问题,设计了一种平衡结构,并进行了相应的分析.该结构设计简单、加工方便,使用可靠,可广泛应用于大中型轴配流径向柱塞泵中.     

径向柱塞泵流场仿真中UDF的分析与实现

CFD方法在产品问题分析与研究方面具有一定的优越性,在通过CFD方法对径向柱塞泵进行流场分析与优化过程中发现,由于径向柱塞泵工作原理及其刚体运动关系的独特性,流场仿真分析需要借助CFD动网格技术和用户自定义函数(UDF)才能进行。该文着重推导了径向柱塞泵柱塞相对于转子做往复运动的速度表达式,并对其进行正交分解处理,编写柱塞相对于转子运动的UDF程序,结果显示UDF程序编写方法及程序是合理的、正确的,研究结果对径向柱塞泵内部流场的分析奠定基础。     

新型变量径向柱塞泵配流轴模态分析

机械振动与流体振动是径向柱塞泵中两种常见的振动类型。配流轴及变量机构的振动、由转子偏心与不平衡所产生的振动都为机械振动;由径向柱塞泵的压力冲击和固有流量脉动所引起的振动则为流体振动。对各激振源及其激振频率进行了详细介绍,并分析了其对径向柱塞泵的性能影响。     

径向变量柱塞泵的修复

径向变量柱塞泵比轴向柱塞泵耐冲击、寿命长、控制精度高,是一种高技术含量的高压泵。但径向变量柱塞泵的制造和维修都很困难。作者通过仔细分析,找出某径向变量柱塞泵失效的原因并采取措施对之进行了修复。该修复方案被证明是合理有效的,对今后修复类似柱塞泵有很好的借鉴意义。     

新型径向恒流柱塞泵的设计

本文提出了新型的恒流柱塞泵的理论分析和设计，针对柱塞泵的运动情况，阐述了为实现柱塞泵的无流量脉动的柱塞的运动速度曲线所必须具备的特征，导出了几种常见的恒流特征速度曲线，并设计了径向恒流柱塞泵。     

静压支承圆柱副油膜刚度研究

提出一种新的径向柱塞泵,并对其中的一对重要摩擦副——圆柱副的油膜刚度进行了研究,对径向柱塞泵的理论分析具有指导意义。     

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。     

Investigation on the radial micro-motion about piston of axial piston pump

The limit working parameters and service life of axial piston pump are determined by the carrying ability and lubrication characteristic of its key friction pairs. Therefore, the design and optimization of the key friction pairs are always a key and difficult problem in the research on axial piston pump. In the traditional research on piston/cylinder pair, the assembly relationship of piston and cylinder bore is simplified into ideal cylindrical pair, which can not be used to analyze the influences of radial micro-motion of piston on the distribution characteristics of oil-film thickness and pressure in details. In this paper, based on the lubrication theory of the oil film, a numerical simulation model is built, taking the influences of roughness, elastic deformation of piston and pressure-viscosity effect into consideration. With the simulation model, the dynamic characteristics of the radial micro-motion and pressure distribution are analyzed, and the relationships between radial micro-motion and carrying ability, lubrication condition, and abrasion are discussed. Furthermore, a model pump for pressure distribution measurement of oil film between piston and cylinder bore is designed. The comparison of simulation and experimental results of pressure distribution shows that the simulation model has high accuracy. The experiment and simulation results demonstrate that the pressure distribution has peak values that are much higher than the boundary pressure in the piston chamber due to the radial micro-motion, and the abrasion of piston takes place mainly on the hand close to piston ball. In addition, improvement of manufacturing roundness and straightness of piston and cylinder bore is helpful to improve the carrying ability of piston/cylinder pair. The proposed research provides references for designing piston/cylinder pair, and helps to prolong the service life of axial piston pump.     

基于Fluent的径向柱塞泵内流道流场分析

针对40ml/r径向柱塞泵内流道的非定常流动,应用流场仿真专用软件Fluent进行了可视化分析。利用滑移网格和动网格技术对柱塞绕配流轴旋转以及柱塞沿自身轴线的往复运动进行动态模拟,得到柱塞在不同位置的速度和压力分布云图,以及出口处压力和流量随转角的变化规律,数值模拟结果为径向柱塞泵流道的设计提供了理论基础。     

往复泵水头损失及空化现象的数值仿真优化

为减轻往复泵的水头损失及空化现象，以提高吸入性能，根据魏斯特法尔理论分析了泵阀运动特性，基于阀盘结构和活塞冲次等参量，提出了水头损失和空化量的优化模型。采用Fluent动网格技术进行动态数值模拟，分析了各参量对吸入过程水头损失和空化现象的影响及其发展过程，优选出了最佳阀盘结构参数和活塞冲次，可有效减小液缸内的水头损失，降低因阀盘开启滞后而产生的空化现象，改善泵的吸入性能和汽蚀现象。得出了往复泵吸入过程水头损失最小、活塞端面的空化量最小时的阀盘锥角及最优的工作冲次，为往复泵的吸入特性研究提供了参考依据。     

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。     

Dynamic analysis of a reciprocating compression mechanism considering hydrodynamic forces

In this paper, a dynamic analysis of the reciprocating compression mechanism of a small refrigeration compressor is performed. In the problem formulation of the mechanism dynamics, the viscous frictional force between the piston and the cylinder wall is considered in order to determine the coupled dynamic behaviors of the piston and the crankshaft. Simultaneous solutions are obtained for the equations of motion of the reciprocating mechanism and the time-dependent Reynolds equations for the lubricating film between the piston and the cylinder wall and for the oil films on the journal bearings. The hydrodynamic forces of the journal bearings are calculated by using a finite bearing model along with the Gümbel boundary condition. A Newton-Raphson procedure is employed in solving the nonlinear equations for the piston and crankshaft. The developed computer program can be used to calculate the complete trajectories of the piston and the crankshaft as functions of the crank angle under compressor-running conditions. The results explored the effects of the radial clearance of the piston, oil viscosity, and mass and mass moment of inertia of the piston and connecting rod on the stability of the compression mechanism.     

海水径向柱塞泵陶瓷摩擦副摩擦学性能研究

海水径向柱塞泵通过增加单转柱塞往复运动频率,减少了泄漏量,提高了泵的容积效率,适用于低转速场合。但低速下的泵内摩擦副尤其是微型面接触摩擦副很难形成流体动力润滑,这就对摩擦副材料性能提出了较高要求。选择几种陶瓷材料与17-4PH配对,通过海水环境中销盘摩擦实验,考察了材料的摩擦学性能。实验结果表明在不同载荷下,ZrO₂摩擦系数和磨损量均为最低,磨损后的表面粗糙度最低。ZrO₂与17-4PH配对更适合作为微型面接触摩擦副的材料。     

Dynamic behavior analysis of reciprocating compressor with subsidence fault considering flexible piston rod

Subsidence wear is inevitable in a reciprocating compressor system, but how to induce body vibration is not clear. We investigated the dynamic behavior of a reciprocating compressor system with subsidence fault considering a flexible piston rod. The flexible piston rod was modeled as a cantilever beam. The dynamic model, in which the influence of the subsidence size, variational cylinder pressure, impact effects and piston rod flexibility are taken into account, was established. Influences of the four parameters including subsidence size, vertical force of flexible piston rod, cylinder pressure and crankshaft speed were analyzed in the dynamic response. Numerical results reveal that with the change of the four parameters, the existence of subsidence fault has a significant effect on the displacement, velocity and acceleration of the crosshead in the transverse direction, but only conspicuously affects the acceleration in the longitudinal direction. In addition to cylinder pressure, the larger the values of the other three parameters, the greater the influences. The cylinder pressure is a time-varying working load. Not only the cylinder pressure but also the open/close time of the valves and change rate of the pressure all affect the dynamic behavior of the system with subsidence. Meanwhile, the change in the vertical force of the flexible piston rod has a remarkable effect on the jump position of the crosshead, but the effect of other parameters is not obvious. In addition, the changes of parameters produce obvious influences on the impact force and the impact range of the crosshead. The stability of the reciprocating compressor system was studied using Poincaré portraits method. The result shows that the system with subsidence fault has chaotic behavior.     

Piston Assembly Design for Improved Thermal-Tribological Performance

The tribological system in the piston assembly of an internal combustion engine includes contacts at interfaces of piston/piston ring/cylinder liner, piston skirt/cylinder wall, and piston/piston pin/ connecting rod. The thermal and tribological properties of the piston, piston rings, and cylinder wall are critical to the life and quality of the engine. Severe wear and scuffing failure, especially at the ring/ring groove and ring/liner interfaces, may present a major problem if the piston temperature is too high. Temperature considerations for the piston often limit the effort to increase the engine power.

A new engine piston incorporating the heat pipe cooling technology has been developed for reducing the piston temperature, especially in the ring land and along the piston wall. The current work aims at investigating the effect of reciprocating heat pipes on heat conduction in the piston, and thus the tribological behavior of the piston assembly. Due to the high thermal conductance of the reciprocating heat pipe, a considerably large amount of combustion heat, which is conventionally conducted through the piston wall, is transferred through heat pipes. This new design will result in a lower temperature on the piston wall and a reasonably low temperature distribution in the piston.     

一种新型井下排水采气泵的设计与仿真

为进一步满足低压、低产气井的排水采气作业需求,降低运行成本,完善排水采气工艺,提出一种适用于直井、斜井、水平井,仅依靠储层中的天然气作为动力来源的新型井下排水采气泵。该泵基于气动增压原理,利用多级气缸增压并以机械闭环的控制方式驱动往复泵机构工作,从而将井筒内的积液泵送至地面。介绍新型排水采气泵的结构和工作原理,阐述工作流程并具体分析驱动气缸的控制方式与运动换向逻辑;建立排水采气泵的数学模型;最后,利用MATLAB/Simulink进行动态特性仿真,研究包括驱动气缸活塞直径、驱动气缸活塞行程、控制阀开关行程和换向阀阀芯直径在内的结构参数对系统动态特性的影响以及在不同载荷、驱动压力与增压比下的工作特性。通过仿真计算,确定了排水采气泵的结构参数,同时为实际运用中的选型提供了参考。