Foil bearing

Abstract

Spacer ridge portions (51), which have higher rigidity than a bump foil (40) and serve as deformation restricting portions for restricting deformation of ridge portions (43), are provided in spaces between adjacent valley portions (44) in a circumferential direction of a rotating shaft (12). Each spacer ridge portion (51) protrudes toward each ridge portion (43) such that a gap (55) is formed between the spacer ridge portion (51) and the ridge portion (43) in a radial direction of the rotating shaft (12), and, when the rotating shaft (12) rotates, the ridge portion (43) deforms toward the spacer ridge portion (51) such that the gap (55) between the spacer ridge portion (51) and the ridge portion (43) is reduced. Even when the rotating shaft (12) moves in the radial direction due to vibration or the like and the rotating shaft (12) moves in such a manner that a top foil (30) crushes the ridge portions (43) of the bump foil (40), the deformation of the ridge portions (43) is restricted by the spacer ridge portions (51). As a result, complete crushing of the ridge portions (43) is avoided, thereby mitigating the decrease in fatigue strength of the bump foil (40).

Claims

1. A foil bearing for supporting a rotating shaft in the radial direction, comprising: a bearing housing having a through hole through which the rotating shaft is inserted; a thin plate-shaped top foil disposed between the rotating shaft and the bearing housing; and a thin plate-shaped bump foil disposed between the bearing housing and the top foil and elastically supporting the top foil, wherein the bump foil has a plurality of peaks that contact the top foil and a plurality of valleys that are supported by the bearing housing, the peaks and valleys are arranged alternately in the circumferential direction of the rotating shaft, and a deformation restricting portion is provided in the space between adjacent valleys in the circumferential direction of the rotating shaft, which has higher rigidity than the bump foil and restricts the deformation of the peaks, the deformation restricting portion protrudes toward the peaks in the radial direction of the rotating shaft such that a gap is formed between the deformation restricting portion and the peaks, and the peaks deform toward the deformation restricting portion when the rotating shaft rotates such that the gap becomes smaller.

2. The foil bearing according to claim 1, comprising a corrugated spacer disposed between the bearing housing and the bump foil and having a thickness greater than the thickness of the bump foil, wherein the spacer has a spacer peak that protrudes toward the peak and a spacer trough that contacts the bearing housing and supports the trough, the pitch between adjacent peaks in the circumferential direction of the rotating shaft and the pitch between adjacent spacer peaks in the circumferential direction of the rotating shaft are equal, and the spacer peak is the deformation restricting portion.

3. The foil bearing according to claim 1, comprising a cylindrical spacer disposed between the bearing housing and the bump foil, wherein the outer circumferential surface of the spacer is in contact with the inner circumferential surface of the bearing housing, the inner circumferential surface of the spacer has spacer protrusions projecting toward the peaks and spacer recesses supporting the valleys, the pitch between adjacent peaks in the circumferential direction of the rotating shaft and the pitch between adjacent spacer protrusions in the circumferential direction of the rotating shaft are equal, and the spacer protrusions are the deformation restricting portions.

4. The inner circumferential surface of the bearing housing has housing protrusions projecting toward the peaks and housing recesses supporting the valleys, wherein the pitch between adjacent peaks in the circumferential direction of the rotating shaft is equal to the pitch between adjacent housing protrusions in the circumferential direction of the rotating shaft, and the housing protrusions are the deformation restricting portions, as described in claim 1.

Images