Abstract: In order to analyze the noise characteristics and the location of the specific sound source of the axial variable piston pump, a noise and vibration test of the pump was carried out by building a noise and vibration test bench. When the rotating speed was at a constant speed of 1 660 r/min and a fixed displacement of 75 mL/min, the noise and vibration signals of the pump were measured and recorded at load pressures of 16, 20, and 24 MPa, respectively. The collected signals were subsequently analyzed by means of spectral analysis and partial coherence analysis to obtain the noise characteristics of the pump and accurately trace the location of the sound source of the pump. The results show that the noise of the pump increases with the increase of the load pressure. The reciprocating impact of the piston, oil flow backward, and the pulsation of oil were the main noise sources of the pump under test. The noise caused by bearing vibration and spindle rotation was the secondary noise source. When the characteristic frequency was less than 200 Hz in the low frequency band, the main structural noise source of the pump under test was the vibration of the spindle rotation and the noise generated by the reciprocating movement of a single plunger. Conversely, when the characteristic frequency was above 200 Hz in the middle and high frequency band, the main structural noise source of the tested pump was the vibration caused by the plunger reciprocating movement.

Key words: axial variable piston pump, noise, frequency spectrum analysis, partial coherence analysis