Performance optimization for high speed axial piston pump considering cylinder block tilt

Increasing the rotating speed is considered as an efficient approach to upgrade the power-to-weight ratio in an axial piston pump, but penalized by more leakage and more severe wear resulting from the adverse cylinder block tilt. Previous studies mainly focused on the bearing characteristic of the valve plate/cylinder block pair, but the spline coupling also plays a key role in the undesired cylinder block tilt, which has been little studied. A theoretical model for the rotating assembly is presented to investigate the effect of the spline coupling length on the cylinder block tilt and the performance of the valve plate/cylinder block pair. A typical high-speed axial piston pump with the displacement of 5.2 mL/r at 10,000 r/min was studied by simulation and experiment. It shows that the optimal spline coupling length is one value increased by 2 mm from the original, bringing a remarkable leakage reduction under the high-speed condition by decreasing the cylinder block tilting angle. The experiment result matches well with the simulation. The influences of the spline coupling on the cylinder block tilt and the leakage were demonstrated.