FOIL THRUST BEARING

PROBLEM TO BE SOLVED: To provide a foil thrust bearing capable of preventing fluid from flowing-out caused by varied pressure of a bearing surface when rotating at a high speed and also improving loading capacity. SOLUTION: A rotary body in an upper face of a bearing plate 20 is rotated in a counterclockwise direction. A fan-shaped backspring 21 is arranged in the surface of the bearing plate 20, and a top foil 22 is further arranged above the backspring. The backspring 21 is fitted in a groove 24 and is arranged to right and left sides. An upstream side of the backspring is enlarged toward an outer periphery side, and a downstream side of the backspring is arranged to the adjacent groove 24, and the backspring 21b in the upstream side is eventually overlapped on the backspring 21a in the downstream side. The top foil 22 fixed in a spring 22 in the upstream side covers an overlapped portion of the backsprings 21a and 21b through the upstream side of the groove 24. When the backspring 21 is bent, its clearance is getting narrower toward the outer periphery side. When centrifugal force acts therein, the outer periphery side performs a role of a dam, and flowing-out of fluid is consequently prevented.