Investigation Into The Piston Coupling And The Ball Friction Coupling Based On Hydrostatics Support On The Axial Piston Pumps

This task will be foundation to develop a new type hydrostatic transmission piston pumps with high efficiency, long life, high pressure and high speed, which combined the item of Nature Science Fund of Zhejiang Province, Tribology Study on Sealing, Hydrostatic Support and Piston on Hydrostatic Transmission Piston Pump. In this paper, a new design idea of the ball friction coupling based on hydrostatic bearing was given, and analysis was carried out to the static state properties and the dynamic properties of the oil-film of this friction pair. In this thesis, investigative content includes mainly:1. Kinematics of the axial piston pump with swash plate yoke's angle were analysed. There was a lot of analysis about relative movement between piston and cylinder block, between piston and swash plate, between slipper and swash plate. At same time, the movement simulation curves were given.2. The received load of the piston and the slipper were analysed. Besides establishing the calculation formulas of the support force of the swash plate, the contact load and the friction force between piston and cylinder block, the interaction force between piston and slipper, and the heel over moment of slipper, the relation between each machinery parameter and all these forces were discussed.3. There are some research on the static state property of the ball friction coupling based on the hydrostatic bearing. By application Navier-Stokes equations under the sphere coordinate, the calculation formula of the support load of the oil film of the ball joint coupling based on hydrostatic bearing. Support property equation of this ball joint coupling was set up. At same time, the formula of the oil film stiffness was established.4. Investigation into the dynamic property of the oil film of the ball frictioncoupling based on hydrostatic support was given. The calculation formula of the extrusion bearing load of the ball friction coupling and slipper pair was educed, and the dynamic equation of the oil film was established. By application of the SIMULINK toolbox of Matlab, the simulation models were obtained. In addition, the relation between various parameters of the slipper pair and ball friction coupling based on hydrostatic support and dynamic characteristic of the oil film was analyzed.5. The derivation of the leakage flow rate formula of the special annular clearance between the piston and cylinder under condition of variable viscosity in the axial piston pumps was carried out. At same time, considering the questions of the eccentricity and the variable sealing length of piston friction pair, the modified coefficient of the calculation formula of the flow-rate of the leakage was given.6. The experimental equipment based on theoretical analysis and simulation was set up hi order to measure the oil film thickness of the ball friction coupling and the slipper coupling based on hydrostatic support.