Simulation of dynamic phenomena in a high pressure variable displacement axial piston hydraulic pump

Abstract

Substituting a valve plate-based commutation unit with a hydrostatic-load-free commutation bushing controllable with a signal of negligible power, that could be applied in constant and variable displacement pumps introduced a different approach to the design of commutation units in multi-piston axial hydraulic pumps.
Conducted research showed that valve plate-based commutator is responsible for over 50% energy loss. The new idea assumed a stationary cylinder block and the replacement of the valve plate with a camdriven commutation unit that would be totally unloaded hydrostatically. That eliminated main source of mechanical losses as well as a flow resistance loss. Additionally, the dead volume was significantly reduced, which helped to reduce the pump noise level and resulted in a great decrease in power needed to control the pump displacement. That allowed to eliminate a servomechanism and the direct control of the pump displacement with a low power element. However, the new design presented a challenge in the form of pressure peaks occurring in the working chamber, which were difficult to eliminate. This article presents attempts to solve problems connected with those dynamic phenomena.