Experimental investigation on the sharpness reduction of an axial piston pump with reinforced shell

Axial piston pumps have been widely used in the engineering equipment with high power performance. Sound quality is one crucial concern due to the ever-increasing demand for comfort. Sharpness is one important parameter in the objective evaluation of sound quality. In this study, an experimental work was conducted to investigate the sharpness reductions of an axial piston pump with a reinforced shell. Sharpness, frequency spectrums of the sound pressure levels (SPLs) and vibration velocities in the low-frequency range (LFR), medium-frequency range (MFR) and high-frequency range (HFR), and root sum square values of the SPLs and vibration velocities in the three frequency ranges were compared. The effects of the SPLs in the LFR, MFR and HFR, and the effects of the SPLs at the 9th, 18th and 27th order harmonics on the sharpness were analyzed. Results showed that sharpness is reduced using the reinforced shell, and the increases of the SPLs in the LFR and decreases of the SPLs in the MFR and HFR are the main causes. Moreover, the increases of the SPLs in the LFR have the largest effects on sharpness reductions, and the SPLs at the 18th order harmonic are the most protruded to affect the sharpness.