Beschreibung
Sound and vibration issues have ever since been addressed in the research and development of fluid power machines, especially pumps and motors. Most efforts concentrate on fluid borne (FBS) and structure borne sound (SBS), only few address air borne sound (ABS). The presented thesis expands beyond the SBS simulation to finite element based ABS analysis of an axial swash plate motor with the aim of reducing the humanly perceived sound pressure level. The simulation builds on a model of the entire motor incorporating simplified physical approaches for miscellaneous complex mechanisms, e.g., non-linear contact, lubrication gaps or damping. A three-step FE simulation - numerical modal analysis, harmonic response analysis and acoustic simulation - is pursued. Therefore the modal parameters of the motor are experimentally analyzed and compared to the results of the numerical simulation model. The excitation loads are derived from simulated piston chamber pressure courses. Their incorporation in the simulation in addition to the surrounding air volume leads to the ABS emission simulation. The results for different operating points (OP) and valve plate (VP) designs are successfully compared to sound measurements in an anechoic chamber, resulting in a satisfying accuracy for most simulated combinations of OP and VP. Finally, the acoustical impact of the different valve plate designs is reviewed and local structural reinforcements are analyzed by means of the numerical acoustical model. The results show that an early consideration of the ABS emission in the develop-ment process of a displacement machine, especially regarding valve plate design, can lead to a significant reduction in the ABS emission.
