The Development Process for a New Variable Displacement, Open Circuit, Axial Piston Pump

Abstract In this paper an axial piston pump is studied using numerical and experimental approaches. The pump, manufactured by the company Continental Hydraulic Inc., has a maximum operating pressure limit of 280 bar and a displacement of 65.9 cm3/rev; it is a variable swashplate design with nine-piston, suitable for open circuit application, medium to high pressure. Two numerical approaches have been compared to simulate the pump units. First of all, an accurate 3D -CFD model has been built up putting emphasis on the description of the detailed features of the flow through the unit. Specific attention has been reserved to the flow losses due to cavitation. Then a fast-lumped parameter approach has been built up focusing the attention on the valve plate geometry. Using the proposed numerical approaches, it is possible to fully understand the unit operation with, obviously, different assumptions and level of result details. Numerical models have been validated with an experimental data performed by the pump manufactured on their test ring with high agreement. As results, the proposed analysis permit to gain a high level of understanding of the operation of the unit finding the critical aspects and giving important information to the designer in order to improve the pump performance. By the end a new valve plate has been designed to improve the pump volumetric efficiency and to reduce the flow ripples and the reverse flow.

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The influence of dynamic swash plate vibration on outlet flow ripple in constant power variable-displacement piston pump

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406219840379 ◽

2019 ◽

Vol 233 (14) ◽

pp. 4914-4933 ◽

Cited By ~ 2

Author(s):

Yang Pan ◽

Yibo Li ◽

Dedong Liang

Keyword(s):

Theoretical Model ◽

Piston Pump ◽

Plate Vibration ◽

Axial Piston Pump ◽

Constant Power ◽

Flow Ripple ◽

Swash Plate ◽

Variable Displacement ◽

Outlet Flow ◽

Axial Piston

The vibration of a swash plate is caused by the piston forces and the control actuator acting on the swash plate. An earlier study of the outlet flow ripple of variable-displacement axial piston pumps assumed a fixed swash plate angle; it ignored the influence of swash plate vibration on the outlet flow ripple of the axial piston pump. In this work, a theoretical model of the outlet flow ripple and pressure pulsation was established in a constant power variable-displacement piston pump. The vibration of swash plate, flow leakage, and valve dynamic characteristics are considered in the theoretical model. The computational results of the theoretical model at different external load pressures are verified by comparison with experimental results. The vibration of the swash plate is strongly influenced by both the piston chamber pressure variation and the control actuator mechanism. The study proved the influence of the swash plate vibration on the outlet flow ripple and the pressure pulsation of an axial piston pump. Compared to the case of a fixed swash plate angle, accounting for swash plate vibration is much more suitable for the accurate determination of the outlet flow ripple and pressure pulsation of an axial piston pump. It is also shown that the vibration of the swash plate affects the valve plate design. Accordingly, valve plate optimization based on the theoretical model of the outlet flow ripple was also studied in this work. The amplitude of the instantaneous outlet flow ripple was considered as the optimization objective function. Finally, the optimized design parameters for a constant power variable-displacement swash plate axial piston pump were evaluated.

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