Modeling and analysis of the leakage performance of the spherical valve plate pair in axial piston pumps

Axial piston pumps are widely used in construction machinery due to the high power density. The leakage performance of the spherical valve plate pair is of great significance to the large displacement pumps' volumetric efficiency. However, the model and calculation of leakage are unclear. This paper proposed a cylinder block dynamic and oil film lubrication based leakage model of the spherical valve plate pair for axial piston pumps. Numerical solutions on the leakage performance under different working conditions were carried out. The tilt behavior of the cylinder block, thickness, and longitude velocity of the oil film were solved. In addition, the effects of central spring stiffness on leakage performance were analyzed and experiments were conducted. Results show that the pump is with poor volumetric efficiency for operation at low speed and high pressure, and +/- 5% adjustment of spring stiffness leads to a 237% maximum leakage gap for spherical valve plate pair.