Noise reduction of hydraulic systems by axial piston pumps with variable reversing valves

摘要

Hydraulic pumps are often considered to be the leading noise source. The main criteria for noise generation of hydraulic piston pumps are the flow ripple, the pulsating piston force and the pulsating swash plate torque. Common methods to reduce noise of axial piston pumps are grooves or boreholes to smoothen the reversing process. More recently, pre-compression volumes are used which mainly focus on flow ripple reduction. However, these methods only have the ability to reduce noise and flow ripple significantly in a designed operating range. Using special reversing valves, a variable approach to reduce noise is investigated in this paper. Hereby, the valve openings can be adapted to the actual operating point of the pump, which is defined by the rotational speed, the pump displacement and the system pressure. Furthermore, this variability allows different control strategies, so that the focus can be shifted between the different noise criteria and optimized for a specific hydraulic system. The required valve openings for different control strategies and operating points were determined by simulation runs and verified by measurements. Depending on the investigated operating point, flow ripple reductions of up to 50% and swash plate torque ripple reductions of up to 70% were measured. Furthermore, different cylinder pressurization slopes are presented along with the resulting pump noise. Depending on the operating point, sound power level of the pump itself can be reduced by up to 2dBA compared to a highly optimized standard pump.