高速液压缸可控变间隙密封技术及密封界面仿生织构润滑机理研究

The friction of seal interface and leakage are difficult to coordinate that restrict the development of high speed hydraulic cylinder. The friction of rubber seal in hydraulic cylinder is large and reduces its frequency response; even though clearance sealing can effectively improve dynamic performance of hydraulic cylinder, but its leakage is hard to control. This project perfects the description of the classical clearance to sealing structure, complex flow field and the variable clearance flow process; puts foward the thought of controlled -variable clearance seal, and builds the controlled elastic seal clearance deformable structure on both ends of the piston to construct the nonlinear pressure feedback field to realize the clearance adaptive adjustment with pressure's changing to effectively control the leakage volume, thus improve the volumetric efficiency. Meanwhile, this project raises a soft sensing technology to gauge the variable clearance sealing interface based on "steady state measurement + velocity correction + profile effect correction", which can solve the problem of measuring the trace clearance inside the hydraulic cylinder. This project introduces bionic placoid scale grid texture of plane friction pair into the design of the hydraulic cylinder piston surface topography; and optimize the bionic placoid scale structure by using analysis principle of generalized complex impedance dynamic pressure grid to increase the storage capability of sealing interface and enhance the support stiffness of oil film, thereby realize the fine lubrication and support to handle the problem of dynamic response of hydraulic cylinder and finally to achieve high speed.

密封界面的摩擦与泄漏是一对难以协调的矛盾，制约了高速液压缸的发展。橡胶密封液压缸摩擦力大，频率响应低；间隙密封能有效提高液压缸动态性能，但泄漏量难以控制。本项目结合基于复杂液压阻抗网络的流场本构方程，完善了经典间隙密封理论关于密封结构复杂流场及变间隙流动过程的描述；提出可控变间隙密封思想，在活塞两端构造可控弹性密封间隙变形结构，形成非线性压力反馈区，使密封间隙随压力变化而自适应调节，实现泄漏量有效控制，提高容积效率；提出基于"稳态测量+速度修正+形面影响修正"的变间隙密封界面间隙量软测量技术，解决液压缸内微量间隙测量的难题；将平面摩擦副仿盾鳞网格织构思想引入液压缸活塞表面形貌设计中，采用广义复阻抗动压网络分析原理，对环形面仿盾鳞织构进行优化，使密封界面的储油功能提高，油膜支撑刚度增强，从而实现良好的润滑和支撑，解决液压缸动态特性问题，实现高速化。

本项目以高速液压缸的低摩擦变间隙密封问题为典型背景，拟研究变间隙密封技术和表面织构动压润滑技术，解决高速液压缸泄漏与摩擦之间的矛盾。该项目研究了密封结构复杂流场及变间隙流动过程，对可控变间隙密封原理及特性进行了研究，采用多种数学建模方法和实验方法进行理论与实验分析，将变形唇边结构简化为悬臂梁、薄壁圆筒结构，进行数学建模与计算，结果表明，合理设计的唇边结构可实现密封间隙的压力补偿，且唇边厚度、均压槽位置对唇边变形形状有影响，在此基础上，结合流体动力学规律，分析了变形结构对泄漏量的压力补偿机理，发现随液压缸两腔压力差增大，泄漏量先增大后减小，最后稳定在某一平衡值，并进行了实验验证；提出了基于“稳态测量+速度修正+形面影响修正”的变间隙密封界面间隙量软测量技术，探索了超声波测量方法在液压缸内的微量间隙测量方面的应用，研究采用弹簧模型，根据入射超声波在金属缸筒和间隙内油膜交界处的反射系数，计算中间液压油膜层厚度，并建立了间隙密封液压缸实验装置和超声波油膜厚度测量系统，对测试方法进行验证；研究了摩擦副表面织构结构的动压润滑机理，对不同形状表面织构的润滑性能进行数值与实验分析，分析织构形状、布置方向等对动压润滑性能的影响；分析了存在气体的空化模型流体的润滑特性，并推到了空化耦合楔形效应的可压缩模型LCP方程，研究了楔形油膜的微观特性以及其摩擦学特性；采用曲面响应法和混合BP-GA神经网络法对表面织构结构进行优化。该项目研究成果可为液压非橡胶密封技术和表面仿生织构动压润滑技术研究提供借鉴。