Pumping down the volume: The design evolution of low-noise spur and helical gear pumps

摘要

Balancing noise reduction with high-efficiency hydraulics has been one of the biggest challenges of recent years for industrial vehicle manufacturers. David Brown Hydraulics' strategy in the constant battle to cut pump noise is its Q Series range of spur and helical gear pumps. In any system to which hydraulic pumps are likely to be fitted, there are two principal sources of noise: one is the prime mover, the other is the pump. The noise from the pump is from both airborne noise and fluid-borne noise. Airborne noise is emitted directly from the pump and is usually very low compared to the noise emitted from the fluid. Fluid-borne noise is emitted through the pumped media and is the major area of concern. The fluid noise problem is caused by the fact that the output flow from the pump is not constant, but is a series of cyclic flow pulses generated by the elements within the pump. As this flow ripple reacts with the impedances within the hydraulic circuit, it causes a pressure ripple. This pressure rippling in turn causes components within and connected to the hydraulic circuit to vibrate, generating structure-borne noise. The vibrations are frequency-dependent and proportional to the pressure ripple, which is in turn proportional to the flow ripple.