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

doi:10.3901/JME.2022.20.438

Abstract

Abstract: The axial piston pump, as the core power element of the hydraulic transmission system, higher nominal pressure is its inevitable development trend and requirement. However, ultra-high pressure will cause the oil film of the key piston cylinder pair friction interface to form a significant solid-liquid coupling effect. The effect of the significant solid-liquid coupling on the friction, lubrication and sealing, and load-bearing performance of the piston cylinder pair oil film is still unclear. To this end, a solid-liquid coupling solution method based on the deformation matrix method is developed. The method is built on the finite volume method to solve the oil film fluid lubrication equation, and the finite element method used to realize the regularization of the deformation calculation nodes on the friction interface and the accurate calculation of the deformation matrixes. On this basis, a numerical calculation model of the elastic hydrodynamic lubrication of the piston cylinder pair oil film is established. Numerical analysis and experimental research are carried out on the solid-liquid coupling action characteristics of the friction interface of the soft-hard paired piston cylinder pair, under the 63 MPa ultra-high pressure working condition. The results show that: With the solid-liquid coupling effect, the axial viscous friction and leakage flow of piston cylinder pair are slightly reduced, the total circumferential viscous friction is basically unchanged but the distribution of the force is more concentrated, causing a greater peak friction; Significant structural deformation is concentrated in the local area near the two ends of the oil film distribution area, which is found that it does not induce the increase of the leakage flow. Under the ultra-high pressure conditions, with the solid-liquid coupling effect, the original standard cylindrical bushing bore formed a “flared” microscopic appearance after running of the piston cylinder pair, which helps to enlarge the contact surface between the piston and the bushing bore, enhance the ability to seal ultra-high pressure oil, and reduce contact stress. The established model and research results can provide guidance for the design of the ultra-high pressure axial piston pump.

Key words: axial piston pump, piston/cylinder pair, ultra-high pressure, fluid structure interaction, elastic hydrodynamic lubrication(EHD)

CLC Number:

TH137

HU Min, GAO Peng, MIN Sijie, LIU Rui, QIU Tianxiang, ZENG Yishan, LIU Changhai. 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 Mechanical Engineering, 2022, 58(20): 438-452.

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