Energy Efficiency of Hydraulic Systems with Shared Digital Pumps

Abstract

Conventional variable displacement pumps are being used instead of throttle controls if energy consumption of hydrostatic drives needs to be reduced. A new promising approach is the substitution of conventional “analog” pumps by digital pumps. A digital pump is composed of several parallel constant pumps and a number of switching valves. Digital pumps tend to have better efficiencies in partial load operation than conventional pumps.In addition, digital pumps offer new concepts to supply several actuators in parallel without requiring throttle controls. The shared use of a digital pump for several actuators at once, compared to separate digital pumps for each actuator, tends to further reduce energy losses because of smaller installed total power and reduced partial load operation.A study of digital pumps in a velocity control circuit is presented here with simulation results, comparing separate analog and digital pumps for each actuator vs. shared use of one digital pump for several actuators.