Power losses in the lubricating gap between cylinder block and valve plate of swash plate type axial piston machines

Jonathan Early Baker, Purdue University

Abstract

This thesis presents an extensive simulation study of power loss in the lubricating gap between cylinder block and valve plate. The simulation model used in this investigation covers fluid structure interaction and micro motion of the cylinder block resulting from oscillating piston forces. The model calculates pressure and velocity fields generated in the lubricating film as well as leakage, and viscous friction. Details of the model are explained. Using the model, power losses in the cylinder block valve plate gap are investigated as a function of operating condition for three displacement units. It is shown that power losses for low load operating conditions are approximately the same as power loss for high load operating conditions. In order to reduce losses at low loads, a sinusoidal or wavy micro structured surface is applied to the cylinder block surface. The effect of operating parameters that waved surfaces of varying amplitude and frequency have on power loss in the cylinder block valve plate interface when compared to power loss of a standard, ideally smooth sliding surface is studied. As the gap height of the lubricating film represents the most critical parameter relating to pump performance, special attention is given to the relation between gap height, operating parameters, surface design and power loss. It is shown that significant reductions in power loss occur at low pressure operating conditions with the introduction of the waved surface.

Degree

M.S.

Advisors

Ivantysynova, Purdue University.

Subject Area

Mechanical engineering

COinS