油圧ポンプ構造体振動のモード解析

Abstract

Structure vibration modes of an oil-hydraulic pump bolted onto fixed bracket, like under real operating conditions, are investigated using FEM and an experimental modal analysis so as to obtain fundamental design data for reducing the pump audible noise level by the vibration control technique. Particular attention has been paid to the FEM analysis by assigning appropriate coupling conditions for the contact surface between the bolted flanges and bracket and the appropriate element attributes for carrying out accurate three-dimensional modeling of solid structures. The natural frequencies and mode shapes simulated by FEM agree with those obtained by the experimental modal analysis with a sufficient accuracy for practical usage for almost all vibration modes up to around 4 kHz. It has also been shown that the standard size axial piston pump has broadly, at the relatively low frequency range up to around 2 kHz, the vibration modes (1st and 2nd vertical bending, 1st and 2nd horizontal bending, 1st longitudinal and 1st torsional vibration modes) due to the pump casing regarded as the cantilever supported resiliently to the bracket, and, in the relatively high frequency range over 2 kHz, local vibration modes mainly due to the various members of pump structural framework.