Effects of PCFV and Pre-Compression Groove on the Flow Ripple Reduction in Axial Piston Pumps

This paper represents the results obtained with a preliminary numerical methodology adopted to reduce noise in axial piston pumps. Starting from a preliminary design (further called 'Valve plate #1'), two different valve plates have been proposed comparing their contribution to reduction of flow ripple. The pump is an open circuit axial piston pump, swash plate designed with nine-piston and a maximum displacement of 65.9 cm3/rev. A three-dimensional CFD model of the first pump design has been built up with the commercial code PumpLinx®, developed by Simerics Inc. The numerical model has been validated, considering the pump rotation, fluid characteristic and leakages. The pump has been tested by the pump manufacturer in all the working conditions. The first valve plate design ('Valve plate #1') has been modified optimizing the pre-compression relief groove design ('Valve plate #2') and including a pre-compression filter volume (PCFV, 'Valve plate #3') The Valve plate #2, including an optimized pre-compression groove, has been designed mainly to improve the volumetric efficiency and as well as to reduce the flow ripple. The second solution ('Valve plate #3 has been obtained on the basis of the Valve plate #2, including a PCFV to reduce the reverse flow back to the cylinder chamber. All the designs presented in this paper have been modelled for minimizing the peak-to-peak discharge flow ripple at the pump full displacements and for the rotational speed of 1500rpm delivery pressure. The best geometry has been found demonstrating that, with the introduction of the PCFV into axial piston pump, the reverse flow has been drastically reduced up to 40%. This research is result of a collaboration among the University of Naples 'Federico II' and the pump manufacturers Duplomatic MS and Continental Hydraulics Inc.