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.

[1]  Noah D. Manring,et al.  Friction Forces Within the Cylinder Bores of Swash-Plate Type Axial-Piston Pumps and Motors , 1999 .

[2]  H. Cheng,et al.  Application of Average Flow Model to Lubrication Between Rough Sliding Surfaces , 1979 .

[3]  Monika Ivantysynova,et al.  An Investigation into Micro- and Macrogeometric Design of Piston/Cylinder Assembly of Swash Plate Machines , 2004 .

[4]  Monika Ivantysynova,et al.  INVESTIGATION OF THE GAP FLOW IN DISPLACEMENT MACHINES CONSIDERING ELASTOHYDRODYNAMIC EFFECT , 2002 .

[5]  Monika Ivantysynova,et al.  Computer Aided Optimization of Bearing and Sealing Gaps in Hydrostatic Machines—The Simulation Tool Caspar , 2002 .

[6]  Hubertus Murrenhoff,et al.  Active systems for noise reduction and efficiency improvement of axial piston pumps , 2008 .

[7]  Yang,et al.  Flow Ripple of Axial Piston Pump with Computational Fluid Dynamic Simulation Using Compressible Hydraulic Oil , 2010 .

[8]  Hubertus Murrenhoff,et al.  Simulation of elastohydrodynamic contact between piston and cylinder in axial piston pumps , 2008 .

[9]  Xu,et al.  Modeling and Simulation on Axial Piston Pump Based on Virtual Prototype Technology , 2009 .

[10]  Lars Olems.  Investigations of the Temperature Behaviour of the Piston Cylinder Assembly in Axial Piston Pumps , 2000 .

[11]  Salvatore Manco,et al.  Modelling a Variable Displacement Axial Piston Pump in a Multibody Simulation Environment , 2007 .

[12]  Hubertus Murrenhoff,et al.  Simulation of the Lubricating Film between Contoured Piston and Cylinder , 2010 .

[13]  H. Cheng,et al.  An Average Flow Model for Determining Effects of Three-Dimensional Roughness on Partial Hydrodynamic Lubrication , 1978 .