Gas bearing

Gas bearings have appeared at several points in the history of drive systems. In the 1950s and 1960s, they enjoyed their first commercial success as foil bearings in the aerospace industry. Common synonyms for gas bearings are the terms ‘fluid film bearings’ or often simplified to ‘air bearings’. This means that the bearing consists of a thin gas cushion between the rotor and the stator bushing. Celeroton uses spiral groove bearings, also known as herringbone bearings, consisting of two radial bearings and one axial bearing. In order to generate the necessary load capacity, an overpressure is built up in this gas cushion, which increases with displacement of the rotor versus the stator bushing. In this way, the gas exerts a force against the displacement on the rotor and holds it in the center of the stator bushing, thus ensuring a contact-free bearing of the rotor to the stator. The core technical feature of the gas cushion is to provide the necessary load capacity, stiffness and damping. This allows the gas cushion to absorb disturbances such as imbalance, shock and vibrations.

With the dynamic gas bearings used by Celeroton, the pressure in the gas cushion is built up by the movement of the rotor relative to the stator itself. No external pressure supply is required and the gas bearing also works lubricant-free. The rotor is operated at a minimum speed, the so-called lift-off speed. Up to the lift-off speed, the rotor and stator are in contact and thus in stiction or mixed friction. The required start/stop cycles can be achieved by selecting materials as well as the shape of the friction partners. Once the lift-off speed is exceeded, the force built-up by the gas cushion is sufficient to overcome gravity and enable robust operation. The load capacity and thus vibration resistance grows with increasing speed. Using Celeroton’s system design, the vibration resistance of turbo compressors can be specified in the compressor map.