Experimental verification of cross-angle for noise reduction in hydraulic piston pumps

One of the most important drawbacks with hydraulic systems is noise and vibration, which mainly originate from the hydrostatic pump. A great number of noise-reducing design features have been developed, but they are all, to a greater or lesser extent, sensitive to variations in operational conditions. The present paper is concerned with optimal design and experimental verification of the cross-angle in an axial piston pump. The cross-angle is a small fixed incline of the swash plate in the direction that is perpendicular to the traditional displacement direction. It enables effective noise reduction throughout the whole range of displacement angles. Simulation-based optimization is used to design a pump with optimal cross-angle and a matching valve plate. The design is manufactured and experimentally evaluated. Source flow measurements using the two-microphone method show good agreement between simulation and experiments, which verifies the applicability of the simulation model used. The benefits from using the cross-angle are then verified by comparing it with a pump with a traditional swash plate design, i.e. without the cross-angle. Both source flow measurements and sound level measurements in an anechoic chamber show good improvements from using the cross-angle.