Development of Externally Pressurised Foil bearings

摘要

This paper describes the development of a new type of externally pressurised partial journal foil bearing, giving an overview of design theory, fabrication and experimental validation. The bearing consists of a thin metal foil, equipped with feeding hole(s), which enfolds the shaft, and forms an effective, low cost alternative for (rigid) cylindrical bearings, whose application is hampered by technical as well as economical limitations. The basic design problematic appears to be to make the right tradeoff between foil stiffness, load capacity, and total stiffness of the system. The latter is the resultant of the foil and air-gap stiffness, in series. Several prototype bearings have been built and tested for their load capacity, air consumption and stiffness characteristics. The first two are far superior to conventional air bearings; the last is comparable to rigid bearings of the same dimensions. Measurements on a prototype bearing, (50 mm, diameter, 40 mm wide, 6 bar(g) supply pressure), shows a load capacity of more than 800 N, a radial stiffness of 8.5 N/micrometers, and air consumption of around 2 Normal-litre/min.