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Issue
Nine

Digital Displacement Hydraulics: How it works

The core component of a Digital Displacement system is a hydraulic piston pump/motor with actively controlled poppet valves connected to each cylinder, to rectify the flow into and out of it as the associated piston moves through its stroke.  …


The core component of a Digital Displacement system is a hydraulic piston pump/motor with actively controlled poppet valves connected to each cylinder, to rectify the flow into and out of it as the associated piston moves through its stroke.  Banks of cylinders can be assembled along a common crankshaft to allow multiple independent outputs.  Each valve is operated by a small electro-magnetic latch so that it can be opened and closed on a stroke-by-stroke basis.  The solenoid coil in each latch is activated by a power FET, which is in turn connected directly to the digital output of an embedded controller.

In the case of a motor, each cylinder has two actively controlled poppet valves, one to each of the high- and low-pressure manifolds. When idling, the fluid flows in and out around the low-pressure valve. The high-pressure valve remains closed and isolates the reciprocating cylinder from the high-pressure fluid. This idle cycle typically has a parasitic loss equivalent to one per cent of the potential power of the active cylinder.  When pumping, the microprocessor closes the low-pressure valve to send fluid to the high-pressure service.

 

 

 

"Digital Displacement Hydraulics: How it works". Science Scotland (Issue Nine)
Printed from http://www.sciencescotland.org/feature.php?id=74 on 24/09/17 11:23:47 AM

Science Scotland is a science & technology publication brought to you by The Royal Society of Edinburgh (www.rse.org.uk).