Formation of a Fluid Film between a Valve Plate and a Cylinder Block of Piston Pumps and Motors : 1st Report, A Valve Plate with Hydrodynamic Pads

Abstract

In order to improve the life and reliability of piston pumps and motors, it is essential to from a fluid film between the valve plate and the cylinder block. In this report, therefore, possibility of fluid lubrication is theoretically analyzed for the combination of a valve plate with conventional hydrodynamic pads and a cylinder block supported by both an outside journal bearing and an elastic shaft. The fluid film can be formed even in the case of swash plate type axial piston pumps, but a little change in operating conditions results in a large change in the film shape. Thus, even if a stable film is built up, it is liable to break.