Acoustic Problems Relating to Microhydraulic Components and Systems

Abstract

This paper presents selected applications of the miniaturized hydraulic components offered by specialized manufacturers and some results of the authors' own research on microflows, including results of hydraulic microfeeder vibration measurements performed by the touchless method using a laser vibrometer. The latter was chosen in order to eliminate measuring instrument influence on the investigated microhydraulic object. Special attention was focused on acoustic problems: noise sources and methods of noise reduction.

Studies of flow and cavitation in hydraulic lift valve

“…3 dm 3 /min) in such systems their power is also low, whereas the EU directives [2] relate the permissible level of noise emitted by a mechanical device to the transmitted power. The noise level permissible in microhydraulic systems is relatively low and despite the advantages of this kind of drive it cannot always be used due to the exceedance of the recommended standard indices [3]. One of the major sound generating sources in hydraulic and microhydraulic systems is the unstable operation of the relief valves excited by, among other things, external excitations originating from the vibrations of the machine frame or the feeder cover, on which hydraulic relief valves are often mounted [4].…”

Coincidence of pressure pulsations with excitation of mechanical vibrations of hydraulic system components: An experimental study

“…The issue of the impact of these excitations on the operation of the valve control component applies to all hydraulic systems operating in real conditions, and, in particular, those subject to increased requirements as to the manufacture of precision elements and response to control signals. Due to the above, a significant impact of external signals on the operation of modern proportional elements or hydraulic microvalves is to be expected, as interferential excitation forces in these components may be of the same size as the controlling forces, leading to many detrimental effects that include stability loss, lack of positional precision, sealing damage, and increased noise generation (Kollek et al, 2010). At present, there is a strong tendency for proportional control technologies to be developed in various types of hydraulic components (Jesionek et al, 2004b;Tomasiak, 2001), replacing the previously used conventional components and opening up new possibilities with regard to time of response to control signals (Cichoń and Stosiak, 2011) and bandwidth frequency, and completely new opportunities for performing pre-programmed work cycles, reducing dynamic surplus and mitigating transitional states (Kudźma and Stosiak, 2013;Bury et al, 2022).…”

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…The most convenient types of drives used for powering servomechanisms of UAV control systems and their controlling are electrical or hydrostatic drives. An important advantage of a hydrostatic drive is, i.a., the possibility to achieve high flux density of the power transmitted within the propulsion system, i.e., small mass per unit of generated or transmitted power [1][2][3][4]. The operating nature of a servomechanism in a hydrostatic drive largely depends on the properties of a working liquid flow in a hydraulic line connecting the supply source (hydraulic pomp) with the servomechanism.…”

“…The operating nature of a servomechanism in a hydrostatic drive largely depends on the properties of a working liquid flow in a hydraulic line connecting the supply source (hydraulic pomp) with the servomechanism. Due to the small dimensions of the hydraulic pump and servomechanism used in UAV, their connections and hydraulic lines connecting them have internal diameters less than 6 mmm [3,5,6]. To ensure the required speed of movement of the UAV actuator, the working fluid flow rate in the pipe must be 25-30 dm 3 /min.…”