Air bearing for use with concentric rotary shafts in machines

摘要

U.S. Pat. No. 4,118,079 discloses a fluid bearing in which resilient shells are bent during operation of the bearing in response to changes in pressure of the fluid to make them conform more closely to the confronting surface defining the fluid gap. In the present invention a bearing of this type is used as an intershaft bearing by mounting the shells on one of the rotating shafts the problems associated with centrifugal forces on the shells being turned to advantage by mounting the shells on an external surface of one of the shafts to confront an internal surface on the other shaft. In an application of the invention to a gas turbine engine the two shafts are the high pressure shaft 10 and the concentric inner low pressure shaft 12. The bearing shells 34 of the air bearing 32 are mounted on resilient spring levers 36 on the slower low pressure shaft 12 and their convex surfaces confront the concave internal surface of the high pressure shaft 10, to define the air gap. The spring levers together with the centrifugal forces on the shells modify the shapes of the shells in response to air pressure in the gap to improve the load carrying capacity of the bearing. The shafts contra rotate to maximize relative rotational speed of the surfaces.