Identification of vibration and noise sources in EHA internal gear pumps under variable operating conditions and noise reduction design

Hydraulic pump serves as the primary noise source in Electro-Hydraulic Actuator (EHA), with complex variable speed and pressure conditions leading to intricate evolution of EHA pump excitation. This study establishes a fluid–structure-acoustics-coupled prediction model for an EHA internal gear pump, incorporating the effects of mechanical excitations, to accurately identify these vibration and noise excitations under such variable conditions. The model is validated through tests conducted in a semi-anechoic chamber. Results demonstrate a radiated noise prediction error of less than 1.5 dB(A), representing a 28.6 % improvement in accuracy compared to traditional prediction models. The evolution laws and contribution of excitations under variable conditions are also evaluated, and a housing noise reduction design is implemented. The results show that the fluid surface source consistently contributes the most to radiated noise across all operating conditions. Moreover, mechanical excitations contribute significantly at the peak sound pressure frequencies. The fluid volume source is considerably influenced by rotational speed, and under high-speed conditions, pronounced turbulence, cavitation, and trapped oil phenomena make the contribution of the volume source non-negligible. Structural optimization yields a reduction of 3.7 dB(A) in the predicted overall sound pressure level (SPL) of the EHA pump under the rated operating condition, and the average total SPLs under variable pressure and speed working conditions decrease by 1.2 and 2.2 dB(A), respectively. These findings are significant for guiding the noise reduction design of EHA internal gear pumps under variable operating conditions.