An Approach to Visualize Lifetime Limiting Factors in the Cylinder Block/Valve Plate Gap in Axial Piston Pumps

Abstract

The lifetime of axial piston pumps is depending on the application and it’s overall robustness to external loads, but even in ideal conditions pumps will fail eventually. The analytics to this problem are known to pump manufacturers. Bearing and shaft calculations paired with FEM models are invaluable tools, however the main questions remain with the rotating kit – cylinder block, pistons, and slippers. If properly designed these parts should theoretically outlast the finite lifetime parts, such as roller bearings due to their hydrostatic and hydrodynamic bearings. In reality however failures still occur due to fatigue or other factors such as contamination or wear. This paper describes an approach for the thermal analysis of the cylinder block / valve plate sealing interface. Using a state of the art test rig the temperature distribution, instantaneous gap height as well as particle wear have been analyzed across the entire operating range of an axial piston pump at the block / valve plate sealing interface. Simulations are done with cooperation of Purdue University by using their developed gap simulation model called Caspar FSTI. These simulations along with the measurements are used to locate potential lifetime reducing operating conditions and analyze them. The first results of the thermal behavior of this interface will be presented in this paper.