Multiple frequency vibration of the micro lubricating gap geometry between cylinder block and valve plate in an axial piston pump

Refined models of the forces in the cylinder block/valve plate system along Z axis and the moments around X and Y axes were built, considering the pressure ripple due to the piston reciprocating motions (PRM) and pressure variations in the wedge film (PVF) and the chambers (PVC) caused by the silencing slots. The multi-frequency vibration models of the gap geometry owing to the forces and moments are proposed. The dynamic mechanical balance equations are presented. The frequency spectra of the test gap thickness show the vibration amplitudes at the first three frequencies are larger than those of the other frequencies. PVF and PVC have obvious influences on the gap at the second frequency, and PRM exerts an impact at the third. The moment fluctuations around X and Y axes, bending stiffness of the shaft, and the rough surfaces contact could affect the vibration amplitude of the wedge gap geometry.