Influence of an Accumulator on the Performance of a Hydrostatic Drive with Control of the Secondary Unit

In a secondary control unit system, an accumulator changes the relationship of the pumps and motor from flow coupling to pressure coupling. This change creates several benefits, including energy conservation, increased stability and the ability to change the rotational direction of the hydraulic motor. The accumulator therefore plays an important role because it dominates the overall performance of the secondary control unit system. This paper studies the influence of accumulator volume and precharge gas pressure on the performance of a hydrostatic transmission system in a secondary unit control system. A small test rig of the secondary unit system was set up and a series of experimental studies were run. A mathematical model was derived for simulation purposes. The results reveal that making the volume of the accumulator and the precharge gas pressure as high as possible under permitted circumstances can decrease the fluctuation of working pressure, improve the dynamic performance of speed control and increase the recovery of energy.