Abstract: The variable displacement control has a great energy-saving advantages and application prospects than that valve control. But variable displacement control differential cylinder is not ideal for existing technologies. Using asymmetric pump-controlled asymmetric cylinder strategy to balance the unequal volumetric flow through a single rod cylinder in closed-circuit is an effective method. However, the asymmetric axial piston pump had been presented is fixed displacement. In this paper, variable-displacement asymmetric axial piston pumps (VAPP) is researched. The VAPP variable-displacement output is implemented by controlled the swash plate angle with angle feedback control loop, which is composed through servo proportional valve and angular displacement sensor fixed to connected to the swash plate. Experiments are carried to verify theoretical results. Both the simulation and Experiments results showed that Swash plate angle is controlled by variable mechanism; when swash plate angle increased, oil flow of port B and T are increased and response speed accelerate also. When the discharge ports have load pressure, the flow ripple significantly reduced with the increase of swash plate angle, but the cylinder pressure still increases with the increase of swash plate Angle. The flow ripple cycle of port B is longer than that port T and peak flow is higher than that port T when port B load pressure equals to port T. At same time port T should connection to the low pressure sides or oil tank, to avoid affecting the performance of VAPP.

Key words: asymmetric axial piston pump, flow ripple, pressure fluctuation, simulation analysis, variable-displacement