Identification of acoustic sources for bent-axis axial piston motor under variable loads

The bent-axis axial piston motor is the key actuator of the construction machinery's torque drive and hydrostatic walking. The vibration of the whole motor is not only stimulated by the internal excitation sources, but also affected by the load fluctuation. At the same time, the continuous fluctuation of the load aggravates the evolution of the internal excitation source. Therefore, how to evaluate the impact of load fluctuation on motor vibration and identify the internal excitation source of motor is particularly important. In this paper, the theoretical and experimental research on acoustic sources identification of the bent-axis axial piston motor is carried out. Firstly, according to the structure principle and kinematics characteristics of the motor, the theoretical excitation sources and transfer paths are obtained, and the vibration transmission model based on the excitation sources located in the spindle is established, which can evaluate the effect of load excitation on the overall vibration of piston motor. Further vibration and noise tests under variable loads are completed in the semi-anechoic chamber. The experimental results validate the theoretical vibration transfer model effectively, and reveal the noise sources inside the tested motor under various loads and the transfer of the main noise sources. The maximum vibration amplitude of the outer surface of the motor is shifted from the shell to the backend cover in the process of increasing revs from 500 rpm to 1200 rpm, and the main acoustic source inside the motor is shifted from the eccentricity and unbalance of the spindle to pressure pulsation and flow distribution impact in the process of increasing pressure from 5 MPa to 15 MPa. The data in this paper can be applied to the structure optimization design with load matching, and further provide reference for the follow-up work of reducing vibration and noise under full working conditions.