Study on an Active Accumulator. Active Control of High-Frequency Pulsation of Flow Rate in Hydraulic Systems.

Abstract

The pulsation of flow rate through pipelines caused by hydraulic components (e.g., piston pumps) is one of the most common sources of vibration and noise in hydraulic control systems, particularly in pipelines between pumps and actuators. Among the flow rate pulsations caused by hydraulic piston pumps, which is called fluid borne noise, low-frequency pulsation can be easily absorbed and reduced by a passive element such as an accumulator. However, it is difficult to effectively reduce the high-frequency pulsation such as pulses using the passive elements. This paper deals with an active accumulator which is proposed, newly fabricated and is driven directly by multilayered PZT devices to reduce the flow rate pulsation produced by hydraulic elements in the high-frequency region. The active accumulator has the potential to actively reduce and cancel the variation of high-frequency pulsating flow rate (from 500 Hz to 1 kHz frequency) with hydraulic piston pumps by producing and using the inverse-phase flow by making use of fast-acting piezo device actuators. An active control method is proposed to simultaneously reduce several targeted frequency components of the pulsation without influencing on the other components. The validity and the effectiveness of the method are ascertained experimentally.