On Fluid Power Piston Pumps : With Special Reference to Flow Ripple Reduction

Sammanfattning: Among the major disadvantages of fluid power systems, leakage and an unpleasant sound level can be mentioned. Both drawbacks increase with increasing pressure ripple. Functional problems may be caused, even fatigue and breakdown. A main source of noise is hydrostatic pumps. Airborne noise is induced by the force unbalance in the pump, but also by flow ripple, which transforms to airborne noise through pressure ripple in the system.In this thesis both conventional and newly developed methods to reduce the origin of the flow ripple from the pump are considered. All methods are relatively simple, without components which have to be controlled and with no externa} supply of fluid energy. The study is made both analytically, using computer simulations, and experimentally. The measurement technique is also described.Cavitation and air release in the pump is studied, rendering an accurate model of these phenomena in pump delivery flow simulations.