2015 年 81 巻 832 号 p. 14-00477
Pressure pulsation is caused by the flow ripples from a positive displacement hydraulic pump. It transmits throughout fluid power equipment and causes unwanted excitation of the mechanical parts. In many practical applications, a Helmholtz type hydraulic silencer may be used to attenuate such pulsation. It is the preferred solution on account of its simple structure and high attenuation performance. However the distinctive drawback of this silencer is that it is effective only within a narrow range of the attenuating frequency. Therefore, the silencer is only suitable for use in the hydraulic systems running at constant pump rotational speeds. The purpose of this research is to develop a novel silencer for hydraulic systems that have a fixed displacement pump driven under variable speed. Firstly, a mechanism for adjusting the resonant frequency has been pro-posed. This works by changing the volume of the silencer. Secondly, a prototype of the novel silencer was designed using a new distributed parameter system model, in which the vessel volume was modelled as an annular fluid line. Finally, the at-tenuation characteristics of the prototype silencer were verified by measuring the transmission loss and insertion loss under various conditions, and comparing them with the calculated results.