含磨粒油液高压叶片泵浮动配流副油膜的承载特性研究

High-pressure, small volume and high speed is one of developing direction of hydraulic pump. Vane pump has the mechanical properties of symmetrical force for rotor, without radial load for shaft from theory, so it has a good potential to increase pressure. However, effect of wear grain which is inevitable in oil make film dynamic characteristic produce great changes, which become obstacle for vane pump pressure to further increase. Wear mechanism of port plate will be found to improve load-bearing characteristic in true oil condition become important foundation subject to increase pressure for vane pump..Liquid flow characteristics of oil film in friction pair of unstable port plate in high pressure vane pump which working in oil with wear grain will be studied with two-phase flow theory under the condition of high speed shearing. The law of velocity distribution and influence of wear grain on load-bearing characteristic of oil film will be revealed. Dynamic characteristics of pressure field and thickness of oil film of friction pair of unstable port plate in high pressure vane pump will be studied in order to find best design theory which can make friction loss power is minimum and volumetric efficiency is maximum, and overcome the defect from design method of residual pressing force. Theory analysis and experiment will be used in project, and research result will provide important theoretical basis for increasing pressure of vane pump.

高压、小体积、高转速是液压泵发展方向之一，叶片泵因其转子受力对称、主轴无径向载荷的力学特性，具有进一步高压化的独特潜力。然而实际工作环境中，因工作油液不可避免受到各种磨粒杂质侵入，导致配流副油膜动力学特性大幅度变化，成为叶片泵压力进一步提升的严重障碍。认知配流副磨损机理、提高在真实油液条件下配流副的承载能力，是实现叶片泵高压化的重要基础课题。. 本项目运用高速剪切条件下的两相流理论，研究含磨粒油液高压叶片泵浮动配流副油膜液体流场特征；揭示磨粒速度分布规律和磨粒对油膜承载力的影响规律；研究浮动配流副油膜压力场及油膜厚度变工况动态特性，探求高压叶片泵容积效率最高、配流副摩擦损失功率最小的最佳配流副设计理论，克服剩余压紧力设计方法的缺陷。项目采用理论与实验结合的方法进行，预期结果可为油液含磨粒的真实工作条件下，叶片泵高压化提供基础理论支持。

项目研究含磨粒油液中，高压叶片泵浮动配流副油膜的承载特性相关内容。对叶片泵配流副油膜进行流场仿真，发现高压区位于排油区叶片中间腔分油槽附近，转速和工作压力的变化会影响油膜的速度分布而不影响压力分布。在不同磨粒直径和浓度条件下，油膜表面的磨粒分布规律不同，温度分布也不相同。油液中磨粒的存在使配流副油膜表面的温度降低。吸油区油膜温度受剪切流和压差流的共同作用，排油区油膜温度主要受剪切流的影响，壳体的导热为主要散热途径。工作压力和油膜厚度对油膜温升值的影响规律相反。吸油区油膜温升值比排油区的高，吸、排油区外层区域温升值都比内层区域的高。配流副油膜承载力受到边界压力的影响，包角一定时，承载力的变化幅度不大，但是包角变大会使得承载力变大。承载力按照一定周期性发生变化。计算得到配流副理论最佳油膜厚度值。得到考虑配流盘形变时，油膜厚度随着半径的变化曲线，获得三个典型位置油膜厚度的理论计算与测试结果相对误差小于5%的结论。不同粗糙度配流盘摩擦副的摩擦系数都呈现先减小后增大趋势，且摩擦系数值随着表面粗糙度增大而增大。磨粒浓度一定时，随着磨粒直径的增大，配流盘摩擦副的摩擦系数增大，而磨损率则先增大后减小。磨粒直径一定时，摩擦副摩擦系数随磨粒浓度的增大而减小。配流盘磨损率和磨粒浓度基本呈线性关系。油液中的磨粒使配流盘表面产生刮擦磨损、磨粒磨损和轻微的黏着磨损。最后研究了高压叶片泵内部泄漏、空化及流量脉动问题。内部泄漏主要由配流副轴向缝隙泄漏引起，容积效率损失随着轴向缝隙的增大而成倍增加。得到了吸油区和排油区空化严重的位置及空化影响因素。研究结论对改善叶片泵性能，提高容积效率与机械效率，解决叶片泵向高压高速方向发展的瓶颈问题起到关键作用。