Investigation of a closed electro-hydraulic hybrid drive
Sprache des Titels:
Proceedings of the 11th Scandinavian International Conference on Fluid Power, SICFP'09
In the last decade a new drive technology evolved, namely to combine speed controllable
electrical motors with application specific hydraulic circuits for motion control to exploit in
this way the advantages of both drive technologies and to avoid their disadvantages.
Sometimes such drives are called hybrid.
A specific realization of such a drive featuring a fully closed hydraulic circuit and a compact
arrangement is investigated in this paper. From a design methodological viewpoint it
represents a true module with a minimum of couplings which in this case are only mechanical
and electrical connections. There is no external hydraulic connection
Lifetime critical components such as ball screw- or threaded spindles of typical
electromechanical drives and proportional- or servo valves, cooler, filter and even a tank of
conventional hydraulic drives are missing.
A test bench of such a drive was set-up. Besides demonstrating the main functionality
concerning dynamics and precision hydraulic fluid degradation and contamination, entrapped
air, and wear of the pump and the valves have been the main objectives of the experiments
with this test bench. Meanwhile the hybrid drive was tested under very severe load conditions
for more than 4000 hours. Despite a missing filter and a very low amount of hydraulic fluid
neither the fluid nor the hydraulic components show critical signs of deterioration or wear,