実稼働時における油圧ポンプ構造体振動のFEM解析

抄録

Structural vibrations of an oil-hydraulic pump working under real operating conditins have been investigated using a FEM analysis so as to obtain fundamental design data to reduce the pump's audible noise level through the use of a vibration control technique. A variable-displacement, swash-plate type axial piston pump was used as the test pump. Particular attention was paid to the FEM analysis by substituting the moving excitiing force and moments due to the transient pressure fluctuation in the cylinder near the bottom and top dead centers and due to the rotary motion of the cylinder block with some equivalent forces capable of handling the FEM analysis, as well as assigning appropriate coupling conditions for the contacting surface between the bolted flanges and the L-type bracket, for carrying out accurate modeling for the forced vibration of a three-dimensional solid structure with a moving load being applied. Especially for the former, a new method capable of replacing the real moving exciting force and moments accurately with the stationary virtual forces applied on the three node points of the FEM model has been devised.
The harmonic amplitudes of casing surface vibration simulated by the FEM analysis agree relatively well with measured results for its complex structure for almost all harmonics up to around 3 kHz except for the frequency ranges around some resonances and anti-resonances. It has also been shown that the pump casing vibrations in the direction of trunnion axis was mainly excited by the pressure ripple in the delivery line.