Article citation information:
Vinogradov, B. Mechanical systems with air spring flexible elements. Scientific Journal of Silesian University of Technology. Series Transport. 2019, 103, 199-207. ISSN: 0209-3324. DOI: https://doi.org/10.20858/sjsutst.2019.103.16.
MECHANICAL SYSTEMS WITH AIR SPRING FLEXIBLE ELEMENTS
Summary. The purpose of this study was to assess the effectiveness of flexible air-spring systems operating in parallel to share the total load, taking into account installation and in-operation errors. This study presented experimental and calculated characteristics of the air spring flexibility and its dependence on the polytropic index and additional volume. It considered patterns of load distribution between the air springs when they are operating in parallel to share the total load for the case when the air springs were used as the supporting elements for various machines and units, and between transmission lines containing flexible couplings, where air springs were installed as flexible elements.
Keywords: air spring, rubber-cord shell, load distribution, flexible
A wide standard size series of rubber-cord air springs with a load capacity from 350 N to 230,103 Nwas developed and is being produced. Prospects for effective use of air springs as hydraulic inertial transducers of motion , vibration dampers and shock absorbers for rail vehicles  are being considered. The use of pneumatic couplings in machine drives solved the problem of limiting dynamic loads [3, 7]. One of the most important features of pneumatic couplings is the ability to control their stiffness and, accordingly, torsional vibrations of mechanical systems . Furthermore, air springs may be effectively used as flexible elements sharing the total load, and in systems with a branched power flow.
2. FLEXIBILITY CHARACTERISTICS OF AIR SPRINGS
When choosing a reference point in the static equilibrium position, the characteristics of the air spring flexibility has the form
where , are the gas volume and overpressure in the air spring bellows in the static equilibrium position; is atmospheric pressure; is the air spring effective area depending on the displacement x.
The experimental studies of the flexibility characteristics were carried out for the Connect MD 1895 double convolution air spring, according to the manufacturer’s company catalogue, its features are: weight - 2.95 kg; working pressure - 0.5 MPa; maximum pressure - 0.8 MPa; minimum pressure - 0 MPa; working diameter - 265 mm; assembly height 210 mm; load capacity - 900 kg. The internal volume of the air spring with its design height of 140 mm is 3.64 litres. Based on experimental studies, the dependence of the air spring effective area on its deformation is represented by a first-order polynomial.
where is the effective area in the static equilibrium position, m2, P is the external load, β = 0.118 m.
The difference between the experimental and calculated flexibility of the air spring, when compared by the formula (1) given (2), does not exceed 2%, which allows for further consideration of it as an actual flexibility .
Expanding the expression (1) considering (2) in a Taylor series and retaining only the first two terms, we obtain