Session: Pumps 1

Paper Number: 111507

111507 - Comparison of Airborne Sound Quality Between Digital Displacement & Traditional Axial Piston Pumps 

Digital Displacement Pump (DDP) is a 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. Variable displacement is achieved by utilising one of, or a combination of, these control options. The fundamental design differences between DDP and traditional axial piston pump determines different mechanical and fluid forcing is generated, producing distinctly different Noise, Vibration and Harshness (NVH) characteristics. DDP is the first major disruptor in the field of hydraulic pumps and as such the difference in human perception should be addressed and understood.

This paper presents a comparison of the airborne noise radiated from DDP096 and two axial piston pumps, in a semi-anechoic chamber and on identical 20-tonne excavators. Test chamber data shows that across a wide range of speeds and pressures, DDP is on average 3.5db(A) quieter than a comparable swashplate. Coupled with a significant reduction in Prominance Ratio, DDP has on average a 12% higher Articulation Index, whilst the transient nature of a radial piston pump shows detriment in other psychoacoustic metrics.  Observed trends are also apparent when pumps are compared on working excavators.  

Presenting Author: Jonathan Melling Danfoss Scotland

Presenting Author Biography: Jonathan is an Industrial Ph.D Student with the University of Bath, working at Danfoss Power Solutions in Edinburgh Scotland. His thesis title is "Noise, Vibration and Harshness of Digital Displacement Pumps". Prior experience includes a First Class Masters Degree in Acoustical Engineering from the University of Southampton and seven years at Jaguar Land Rover as a Chassis NVH Engineer.