Variable Displacement Hydraulic Bent Axis Pumps

In hydraulic power systems, variable displacement pumps (VDPs) save power, increase the productivity, or control the motion of a load precisely, safely & economically. The displacement mechanism & power-to-weight ratio of VDPs make them most suitable for control of hydraulic hybrid vehicles (HHVs). One of the problems reported from testing HHVs is that noise levels emitted by the pumps & motors are not acceptable. The lack of space, the extreme pressures and the dynamics of the pump's components limits direct observation of potential noise causing mechanisms. There are several theories as to the source of noise from the pump but little concrete information to further isolate and reduce noise generation. This book presents a mathematical model of the pump that permits the methodical study of the variation of pressure head, flow rate, and dynamic forces acting on the pump case as a function of angular rotations of both the main shaft and the yoke. Knowing the sources of noise enables taking appropriate decisions in terms of design, control strategy, and the implementation of anti-noise techniques & procedures either to the pump or to the hydraulic system.