The load capacity of the gas lubricated spiral groove thrust bearing - on the effect of the groove depth -

摘要

The spiral groove thrust bearing can be operated at the dynamic stable condition and furthermore can bring a large load capacity comparing with the other type of gas bearing such as the Rayleigh pad or the tilting pad types. Accordingly this type of gas bearing has been used as a practical one for a thrust gas bearing of rotary performance. Although the principle and its function have been studied much enough on their theoretical points, it is quite difficult at present to get the plentiful experimental data for practical design. In the spiral groove thrust bearing, when the pad which has the spiral groove on the surface rotates over the other surface, the air as lubricant can be introduced into the centre of the bearing along the centre line of the spiral groove (call it as pumping-in condition). Consequently the pressure can yield the load capacity to separate each surface, but if the depth of the groove is too much high to keep the air in it, the leakage of air will become larger and loose its load capacity. Thereupon the number of the grooves, a spiral angle, the depth of the groove and the bearing clearance are the main and important design factors to confine the ability. The present paper reports a few results which we could get from the experiments to determine the effect of the groove depth on the dynamic properties of the spiral groove thrust bearing. And we discuss also whether the experimental values agree well with the theoretical ones or not.