Research on Lubrication Characteristics of Textured Piston-cylinder Pairs of Axial Piston Pumps under Low-pressure Stroke

doi:10.3969/j.issn.1004-132X.2025.11.007

Abstract

Abstract:

The lubrication states of piston-cylinder pairs were the key to determining the service life of axial piston pumps. Therefore， a textured piston-cylinder pair was proposed to reduce the failure risk of oil film under low-pressure stroke. A textured lubrication model for piston-cylinder pairs was established based on a dynamic node mesh to address the variable support length of piston. Besides， the pressure equation was discretized by using a finite difference method， the pressure and thickness distribution of oil films were obtained by a double-layer cycle of film pressure and eccentricity. The influences of working parameters and texture parameters on lubrication characteristics were analyzed. The results show that the greater the texture radius and texture area ratio， the better the antifriction effectiveness， and the order of the effect in reducing friction（from high to low） is： texture area ratio， texture radius， texture depth. Both increasing the texture radius and decreasing the texture depth may enhance the bearing capacity of oil film， and a texture area ratio of 30% has higher adaptability. Combined with loading test， the maximum reduction in friction coefficient of textured specimen compared to that of non-textured specimen is as 29.8%. The results may provide some references for frictional design of axial piston pumps.

Key words: axial piston pump, textured piston-cylinder pair, lubrication characteristics, low-pressure stroke, eccentricity

摘要：

柱塞副的润滑状态是决定轴向柱塞泵使用寿命的关键，因此提出一种织构化柱塞副以降低低压程油膜的失效风险。针对柱塞副的支撑长度可变，基于动态节点网格建立了一种柱塞副织构化表面润滑模型。采用有限差分法对压力方程进行离散处理，通过油膜压力和偏心量的双层循环获取织构化表面的压力和膜厚分布，分析工况参数和织构参数对润滑特性的影响。研究结果表明：更大的织构半径和织构面积率对柱塞副的润滑减摩效果更好，减摩作用的影响顺序（从高至低）为：织构面积率，织构半径，织构深度；增大织构半径和减小织构深度均可增强油膜的承载能力，且30%的织构面积率具有更高的工况适应度；结合负载试验，织构化试件的摩擦因数较无织构时的摩擦因数最大降幅可达29.8%。研究结果可为轴向柱塞泵的摩擦学设计提供参考。

关键词: 轴向柱塞泵, 织构化柱塞副, 润滑特性, 低压程, 偏心量

CLC Number:

TH117

Gang LUO, Tao HE, Chuanli WANG, Kaiping ZHAO, Hao ZHANG. Research on Lubrication Characteristics of Textured Piston-cylinder Pairs of Axial Piston Pumps under Low-pressure Stroke[J]. China Mechanical Engineering, 2025, 36(11): 2525-2536.

罗刚, 何涛, 王传礼, 赵凯平, 郑浩. 轴向柱塞泵织构化柱塞副低压程润滑特性研究[J]. 中国机械工程, 2025, 36(11): 2525-2536.

Figures/Tables 30

Fig.1 Textured oil film of piston-cylinder pair

Fig.2 Dynamic node grid of oil film of piston- cylinder pair

Fig.3 Calculation process for lubrication of textured surface of piston-cylinder pair

Tab.1 Calculation parameters for lubrication of piston-cylinder pair

参数	数值	参数	数值
柱塞半径r_p/mm	8.00	压力收敛精度ε₁	10^-4
缸体孔半径r_c/mm	8.02	承载收敛精度ε₂	10^-2
常压黏度μ₀/（Pa·s）	0.05	黏压指数α	0.68
常压密度ρ₀/（kg·m^-3）	850	松弛因子ω	0.01
入口压力p_j₌₁/MPa	0.1	空化压力p_c/MPa	10^-8
出口压力p_j₌_J /MPa	0.1	柱塞长度l_max/mm	50

Tab.2 Texture parameters and mesh parameters under specified examples

织构参数	数值	网格参数	数值
织构半径r_t/mm	0.7	径向子域数M	14
织构深度h_t/μm	30	轴向子域数N	12
径向间距d_t_a /mm	3.5	径向节点数I	501
轴向间距d_t_b /mm	3.4	轴向节点数J	421
织构数n_t	168	网格数n_g	2.1×10⁵

Fig.4 Thickness of textured oil film of piston- cylinder pair

Fig.5 Pressure of textured oil film of piston- cylinder pair

Fig.6 Oil film pressure of textured piston-cylinder pair under different working parameters

Fig.7 Gap film thickness and minimum film thickness under different radial loads

Fig.8 Stacking pressure under different radial loads

Fig.9 Friction coefficient， eccentricity， and maximum pressure under different radial loads

Fig.10 Gap film thickness and minimum film thickness under different axial velocities

Fig.11 Stacking pressure under different axial velocities

Fig.12 Friction coefficient， eccentricity， and maximum pressure under different axial velocities

Tab.3 Grid parameters under different support lengths

网格参数	支撑长度l/mm
网格参数	29	32	35	38	41	44
径向子域数M	14	14	14	14	14	14
轴向子域数N	8	9	10	11	12	13
径向节点数I	501	501	501	501	501	501
轴向节点数J	285	319	353	387	421	455
网格数n_g/10⁵	1.42	1.60	1.77	1.93	2.10	2.27

Fig.13 Gap film thickness and minimum film thickness under different support lengths

Fig.14 Stacking pressure under different support lengths

Fig.15 Friction coefficient， eccentricity， and maximum pressure under different support lengths

Fig.16 Oil film pressure of textured piston-cylinder pair under different texture parameters

Tab.4 Grid parameters under different texture radii

网格参数	织构半径r_t/mm
网格参数	0.5	0.6	0.7	0.8	0.9
径向子域数M	20	16	14	12	11
轴向子域数N	17	14	12	10	9
径向节点数I	751	601	501	451	401
轴向节点数J	633	505	421	379	337
网格数n_g/10⁵	4.75	3.03	2.10	1.70	1.35

Fig.17 Eccentricity and friction coefficient under different texture radii

Fig.18 Gap film thickness and minimum film thickness under different texture radii

Fig.19 Eccentricity and friction coefficient under different texture depths

Fig.20 Gap film thickness and minimum film thickness under different texture depths

Tab.5 Calculation parameters under different texture area ratios

参数	织构面积率σ_t/%
参数	6	12	20	30	42
径向子域数M	10	14	18	22	26
轴向子域数N	8	12	15	18	22
织构数n_t	80	168	270	396	572
网格数n_g/10⁵	2.10	2.10	2.10	2.10	2.10

Fig.21 Eccentricity and friction coefficient under different texture area ratios

Fig.22 Gap film thickness and minimum film thickness under different texture area ratios

Fig.23 Average friction coefficient under different texture parameters

Fig.24 Surface friction coefficient under low- pressure stroke

Fig.25 Comparison of friction coefficients under different radial loads

References 22

[1]	TANG Hesheng， REN Yan， XIANG Jiawei. A Novel Model for Predicting Thermoelastohydrodynamic Lubrication Characteristics of Slipper Pair in Axial Piston Pump［J］. International Journal of Mechanical Sciences， 2017， 124： 109-121.
[2]	NIE Songlin， GUO Ming， YIN Fanglong， et al. Research on Fluid-structure Interaction for Piston/Cylinder Tribopair of Seawater Hydraulic Axial Piston Pump in Deep-sea Environment［J］. Ocean Engineering， 2021， 219： 108222.
[3]	ZHAO Kaiping， WANG Chuanli， HE Tao， et al. Theoretical and Experimental Study on Lubrication and Friction of Slipper Pair of Valve Distribution Piston Pump Based on FVM-TRD Coupling Method［J］. Tribology International， 2024， 194： 109456.
[4]	MA Kai， WU Defa， XU Runzhou， et al. Experimental Investigation and Theoretical Evaluation on the Leakage Mechanisms of Seawater Hydraulic Axial Piston Pump under Sea Depth Circumstance［J］. Engineering Failure Analysis， 2022， 142： 106848.
[5]	ZHANG Junhui， CHEN Yuan， XU Bing， et al. Effect of Surface Texture on Wear Reduction of the Tilting Cylinder and the Valve Plate for a High-speed Electro-hydrostatic Actuator Pump［J］. Wear， 2018， 414： 68-78.
[6]	聂松林，李硕，尹方龙，等. 水液压泵柱塞套变形特性的流固耦合研究［J］. 中国机械工程， 2020， 31（10）： 1135-1141.
	NIE Songlin， LI Shuo， YIN Fanglong， et al. Study on Fluid-solid Coupling of Deformation Characteristics of Piston Bush in Water Hydraulic Pumps［J］. China Mechanical Engineering， 2020， 31（10）： 1135-1141.
[7]	ZHANG Junhui， Fei LYU， XU Bing， et al. Simulation and Experimental Investigation on Low Wear Rate Surface Contour of Piston/Cylinder Pair in an Axial Piston Pump［J］. Tribology International， 2021， 162： 107127.
[8]	MA X， WANG Q J， LU X Q， et al. A Transient Hydrodynamic Lubrication Model for Piston/Cylinder Interface of Variable Length［J］. Tribology International， 2018， 118： 227-239.
[9]	王克龙，姜继海，汪泽波，等. 柱塞副微运动轨迹及微倒角对其影响分析［J］. 华中科技大学学报（自然科学版）， 2019， 47（6）： 46-51.
	WANG Kelong， JIANG Jihai， WANG Zebo， et al. Micro-motion of Piston/Cylinder Interface and the Influence of Micro Chamfering on It［J］. Journal of Huazhong University of Science and Technology （Natural Science Edition）， 2019， 47（6）： 46-51.
[10]	胡敏，高鹏，闵思婕，等. 超高压斜盘式轴向柱塞泵柱塞副摩擦界面油膜固液耦合作用特性研究［J］. 机械工程学报， 2022， 58（20）： 438-452.
	HU Ming， GAO Peng， MIN Sijie， et al. Study on the Solid-liquid Interaction Characteristics of the Oil Film within Piston Cylinder Pair of the Ultra-high Pressure Swash Plate Type Axial Piston Pump［J］. Journal of Mechcanical Engineering， 2022， 58（20）： 438-452.
[11]	杭旸，闫康昊，黄丹. 计入柱塞套弹性变形的柱塞副摩擦与密封特性分析［J］. 中国机械工程， 2023， 34（1）： 17-26.
	HANG Yang， YAN Kanghao， HUANG Dan. Analyses of Friction and Sealing Characteristics of Piston/Bushing Interfaces Considering Elastic Deformations［J］. China Mechanical Engineering， 2023， 34（1）： 17-26.
[12]	LIU Yinshui， LI Donglin， TANG Zhenyu， et al. Thermodynamic Modeling， Simulation and Experiments of a Water Hydraulic Piston Pump in Water Hydraulic Variable Ballast System［J］. Ocean Engineering， 2017， 138： 5-44.
[13]	LUO Gang， HE Tao， WANG Chuanli， et al. A Novel Variable Liquid-properties Thermal Network Model for Researching on Thermodynamic Characteristics of Ethylene Glycol Piston Pump［J］. International Communications in Heat and Mass Transfer， 2024， 150： 107185.
[14]	HAIDAK G， WEI X F， LI F Y， et al. Heat Effects Modelling on the Efficiency Loss of the Lubricating Interface between Piston and Cylinder in Axial Piston Pumps［J］. Tribology International， 2022， 175： 107846.
[15]	李强，刘清磊，杜玉晶，等. 织构化表面优化设计及应用的研究进展［J］. 中国表面工程， 2021， 34（6）： 59-73.
	LI Qiang， LIU Qinglei， DU Yujing， et al. Advances in Optimization Design and Application of Textured Surfaces［J］. China Surface Engineering， 2021， 34（6）： 59-73.
[16]	BAI L Q， MENG Y G， KHAN Z A， et al. The Synergetic Effects of Surface Texturing and MoDDP Additive Applied to Ball-on-disk Friction Subject to Both Flooded and Starved Lubrication Conditions［J］. Tribology Letters， 2017， 65（4）： 163.
[17]	MAO Yang， ZENG Liangcai， LU Yan. Modeling and Optimization of Cavitation on a Textured Cylinder Surface Coupled with the Wedge Effect［J］. Tribology International， 2016， 104： 212-224.
[18]	LIU Di， WANG Shaoping， ZHANG Chao， et al. Numerical Study of the Effects of Textured Shaft on the Wear of Rotary Lip Seals［J］. Tribology International， 2019， 138： 215-238.
[19]	张东亚，赵飞飞，高峰，等. 二层沟槽织构对机床导轨表面润滑特性的影响［J］. 中国机械工程， 2018， 29（14）： 1661-1665.
	ZHANG Dongya， ZHAO Feifei， GAO Feng， et al. Effects of Double-layer Groove Texture on Lubrication Performance of Machine Tool Slideway Surfaces［J］. China Mechanical Engineering， 2018， 29（14）： 1661-1665.
[20]	王丽丽，张伟，葛雪，等. 复合微织构排列方式对轴承润滑性能的影响［J］. 中国表面工程， 2023， 36（1）： 145-155.
	WANG Lili， ZHANG Wei， GE Xue， et al. Effect of Compound Micro Texture Arrangement on Journal Bearing Lubrication Performance［J］. China Surface Engineering， 2023， 36（1）： 145-155.
[21]	MA X， WANG Q J， LU X Q， et al. Piston Surface Design to Improve the Lubrication Performance of a Swash Plate Pump［J］. Tribology International， 2019， 132： 275-285.
[22]	李栋，刘晓玲，李磊，等. 计入刚度影响效应的滚动直线导轨几何参数对润滑性能的影响［J］. 机械工程学报， 2021， 57（7）： 100-108.
	LI Dong， LIU Xiaoling， LI Lei， et al. Influence of Geometric Parameters on Lubrication Performance of Rolling Linear Guides Considering Stiffness Effects［J］. Journal of Mechcanical Engineering， 2021， 57（7）： 100-108.