Energy Saving of Oil Hydraulic Pump Unit by Idling Stop Using Accumulator

Abstract

Energy saving have been made in a number of fields due to a shortage of energy resources such as oil and the need to protect the earth’s environment. If an accumulator is coupled with a hydraulic pump unit, intermittent operation of the electric motor powering the pump drive, called "idling stop type operation," can be attained by using the pressure-holding function. Consequently, a reduction in unneeded power consumption can be realized. In this research, an intermittently operated hydraulic pump unit coupled with an accumulator (ACC pump unit), an inverter control-type hydraulic pump unit (INV pump unit), and a variable displacement-type hydraulic pump (VD pump unit) are tested. The power consumption, pump output pressure, pump rotation speed, and energy efficiency of each pump unit were measured after the same work had been completed. The ACC Pump Unit was shown to clearly have the best energy-saving effect.