Session: Digital Hydraulic

Paper Number: 111913

111913 - Digital Displacement Motoring Characteristics of Dynamic Energy Recovery and Hydraulic Transformation 

The Digital Displacement Pump (DDP) is a highly innovative hydraulic variable displacement radial piston pump, driven by a central crankshaft, wherein each cylinder can be independently controlled. With each crank rotation a given cylinder may idle, operate a full pumping stroke or operate a partial stroke. The Digital Displacement® Pump/Motor (DDPM) technology is expected to improve component and system efficiency as well as enabling recovery of useful energy which would otherwise be lost. The machine's unique capabilities include direct hydraulic transformation, allowing for pressure amplification or reduction on the machine pump service, with the pumping cylinders purely driven by the motoring ones.

This paper presents the efficiency results of a newly developed Digital Displacement machine, which comprises of 30 radially arranged valves with a total displacement of 300cc/rev. Test demonstrator data shows overall pumping and motoring efficiency above 95% at the main working operation area for excavators, i.e. 150-250 bar and 1400-1800 RPM. The machine also allows for dynamic energy recovery, with peak efficiency of 91.4% achieved from the hydraulic input power to the DDP150D to output power of the DC/DC inverters. The paper concludes that the machine's capabilities make it a promising solution for hydraulic transformation, with peak transforming efficiency of above 90% achieved for both pressure amplification and reduction at the pump outlet.

Presenting Author: Vojtech Pavlis Danfoss Scotland Inc.

Presenting Author Biography: Vojtech graduated with a Masters degree in Mechanical Engineering from the University of Edinburgh. He joined Danfoss Scotland in October 2022 to be a part of development of a new Digital Displacement Pump with motoring capabilites including Dynamic Energy Recovery and Hydraulic Transforming. Vojtech led the pump verification process and setup the methods to evaluate the machine's efficiency and performance.