Thrust supporting apparatus

1. A thrust supporting apparatus comprising:

a thrust runner configured to rotate integrally with a shaft; and

a foil thrust bearing supporting an axial load of the shaft, the axial load being transmitted from the thrust runner,

wherein:

the foil thrust bearing includes a top foil facing a first surface of the thrust runner, and

the thrust runner comprises at least one stepped portion provided at the first surface of the thrust runner,

the thrust runner further comprises first one or more grooves formed on the first surface,

first ends of the first one or more grooves are disposed on the at least one stepped portion, and

the first ends of the first one or more grooves include first openings provided at a side of the at least one stepped portion.

2. The thrust supporting apparatus of claim 1 , wherein the first one or more grooves are formed as spirals.

3. The thrust supporting apparatus of claim 2 , wherein the first one or more grooves extend from a radially inner side of the thrust runner to a radially outer side of the thrust runner, and are curved from the radially inner side to the radially outer side of the thrust runner in an opposite direction of a rotational direction of the thrust runner.

4. The thrust supporting apparatus of claim 1 , wherein the first one or more grooves are formed as straight lines that extend from a radially inner side of the thrust runner to a radially outer side of the thrust runner.

5. The thrust supporting apparatus of claim 4 , wherein the first one or more grooves, that are formed as the straight lines, extend along a radial direction of the thrust runner in a direction opposite to a rotational direction of the thrust runner.

6. The thrust supporting apparatus of claim 1 , further comprising an additional foil thrust bearing,

wherein:

the additional foil thrust bearing includes a top foil disposed to a second surface opposite to the first surface of the thrust runner in an axial direction of the shaft,

the second surface comprises second one or more grooves formed on the second surface of the thrust runner, and

first extending directions of the first one or more grooves formed on the first surface of the thrust runner match second extending directions of the second one or more grooves formed on the second surface of the thrust runner.

7. The thrust supporting apparatus of claim 1 , wherein a cross section of each of the first one or more grooves has at least one of a semicircular shape, a square shape, and a triangular shape.

8. The thrust supporting apparatus of claim 1 , wherein second ends of the first one or more grooves include second openings that are opposite to the first ends and do not overlap with the top foil.

9. The thrust supporting apparatus of claim 8 , wherein:

the top foil is provided a predetermined distance apart radially from an internal diameter of the thrust runner.

10. The thrust supporting apparatus of claim 8 , wherein the first one or more grooves extend to an outer diameter of the thrust runner so that outer ends of the first one or more grooves are disposed on an outer circumferential surface of the thrust runner.

11. A thrust supporting apparatus comprising:

a thrust runner configured to rotate integrally with a shaft and comprising:

a first surface facing an impeller; and

a second surface opposite to the first surface of the thrust runner;

foil thrust bearings supporting an axial load of the shaft being transmitted through the thrust runner and comprising:

a first foil thrust bearing including a first top foil facing the first surface; and

a second foil thrust bearing including a second top foil facing the second surface;

wherein the thrust runner further comprises:

at least one stepped portion provided at the first surface of the thrust runner;

first grooves formed on the first surface; and

second grooves formed on the second surface, and

wherein first ends of the first grooves are disposed on the at least one stepped portion, and

the first ends of the first grooves include first openings provided at a side of the at least one stepped portion.

12. The thrust supporting apparatus of claim 11 , wherein the first grooves and the second grooves extend from a radially inner side of the thrust runner to a radially outer side of the thrust runner, and are curved from the radially inner side to the radially outer side of the thrust runner in an opposite direction of a rotational direction of the thrust runner.

13. The thrust supporting apparatus of claim 11 , wherein the first grooves and the second grooves extend in straight lines that extend from a radially inner side of the thrust runner to a radially outer side of the thrust runner, such that the first grooves and the second grooves extend in a radial direction of the shaft in an opposite direction of a rotational direction of the thrust runner.

14. The thrust supporting apparatus of claim 11 , wherein a cross section of each of the first grooves and each of second grooves has at least one of a semicircular shape, a square shape, and a triangular shape.