Each of foils (22) includes: a top foil portion (22a) including a bearing surface (S); and a back foil portion (22b), which is formed on an upstream side of the top foil portion (22a), and is arranged so as to overlap behind the top foil portion (22a) of the adjacent foil (22) (on a side opposite to the bearing surface (S)). An angle (E) covering a radially inner end of an overlapping portion (P) between the adjacent foils (22) is smaller than an angle (D) covering a radially outer end of the overlapping portion (P).

A base plate of a thrust foil bearing is provided with a plurality of protrusions and a plurality of recesses formed alternately in a first direction in a striped manner, and either one of top surfaces of the plurality of protrusions and bottom surfaces of the plurality of recesses gradually lower toward one side in the first direction.

A bearing structure includes a rotating shaft, a thrust collar, and a first thrust bearing. The rotating shaft has a central axis. The thrust collar is mounted on the rotating shaft. The first thrust bearing includes a first dynamic pressure generating mechanism. The first dynamic pressure generating mechanism faces the thrust collar. The relation Rt>Rf1 is satisfied, where Rt represents a length from the central axis to the outer circumferential edge of the thrust collar, and Rf1 represents a length from the central axis to the outer circumferential edge of the first dynamic pressure generating mechanism.

A thrust supporting apparatus includes: 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. The foil thrust bearing includes a top foil facing a first surface of the thrust runner, and the thrust runner comprises first one or more grooves formed on the first surface.

A thrust foil bearing (3) of the present disclosure includes a base plate (30) which includes an insertion hole (30a) through which a rotation shaft (1) is inserted, a back foil (20) which is disposed around the insertion hole (30a) and supported by the base plate (30), and a top foil (10) which is supported by the back foil (20), wherein the top foil (10) includes an expansion portion (13) in which a width of the expansion portion in a virtual straight line direction in which a virtual straight line extends decreases in a direction orthogonal to the virtual straight line, the virtual straight line being supported by the back foil (10) on a most downstream side in a rotation direction of the shaft.

A thrust foil bearing includes: a base plate provided with an insertion hole into which a shaft is inserted; a back foil that is disposed around the insertion hole; and a sandwiched portion that extends from an end portion of the back foil in a circumferential direction of the insertion hole to an outer side in a radial direction of the insertion hole.

A thrust foil bearing includes a foil which faces a thrust collar mounted on a shaft in an axial direction, and a case which supports the foil and surrounds the thrust collar, wherein a cooling hole is formed in the case.

A thrust gas bearing includes a collar portion fixed to a shaft portion, a first base part facing one axial end surface of the collar portion, a first gas film forming part formed between the collar portion and first base part, a second base part facing an other axial end surface of the collar portion, a second gas film forming part formed between the collar portion and second base part, and a cooling flow path to carry a fluid flow. The cooling flow path includes a first flow path formed on one axial end side of the first base part and extending from an axial center toward an outer periphery, and a second flow path formed on an other axial end side of the second base part and extending from an outer periphery toward an axial center. The second flow path is located downstream of the first flow path.

A thrust foil bearing includes a base plate including an insertion hole through which a rotating shaft is inserted and a support surface disposed around the insertion hole on one side of the insertion hole in an axial direction, and a back foil disposed on the support surface, in which the support surface has a plurality of inclined surfaces of which inclination angles inclined toward the other side of the base plate in the axial direction become shallower in order toward an outside of the insertion hole in a radial direction, and the back foil is divided into a plurality of divided regions in the radial direction by a slit, and the plurality of divided regions are supported by the plurality of inclined surfaces.

A thrust foil bearing includes: a base plate including an insertion hole through which a shaft is inserted, and a supporting surface expanding in a direction orthogonal to an axial direction of the insertion hole; a step member placed on the supporting surface and formed of a different body from the base plate; and a back foil extending in a circumferential direction of the insertion hole and in which one part of the back foil is supported by the supporting surface and another part of the back foil next to the one part in the circumferential direction is supported by the step member.