静圧気体ジャーナル軸受の負荷容量増加に関する一考察

Abstract

In externally pressurized gas journal bearings, to avoid pneumatic hammer instability, a large pocket in the bearing surface cannot be used, and compressed air is supplied to the bearing surface through inherently compensated restrictor or pocketed orifice restrictor. Therefore, load capacity of gas bearings is less than that of hydrostatic bearings. This paper deals with externally pressurized gas journal bearing with the large land area in the pocket, and the improvement of load capacity without occurring pneumatic hammer instability. The test bearing is 46 mm in length, and 50 mm in diameter and out of roundness of the bearing diameter is less than 0.4 μm. The pocket is about 0.1 mm in depth, and the orifice is 0.2 mm in diameter. The following conclusions are obtained. (1) In case of no rotation, the test bearing with a pad in the pocket has the same load capacity as hydrostatic journal bearing with the same geometry. (2) Due to the hydrodynamic effects on the pad and the land, load capacity increases with the shaft rotational speed.