Airfoil bearing arrangement and method for making the same

1 . A journal foil bearing system comprising:

a journal housing member comprising a journal housing wall that is disposed about a bore that extends along an axis, the journal housing wall having an inner diameter surface that faces the bore and that is spaced apart generally a nominal radius distance from the axis, wherein the journal housing wall locally along the inner diameter surface has a first relief region that extends in a depth direction from the bore to an inner relief surface that is spaced apart from the axis a radius distance that is greater than the nominal radius distance;

a shaft disposed within the bore and supported for rotation about the axis relative to the journal housing member; and

a biasing foil member and a top foil member, the biasing foil member comprising at least one biasing foil received within the bore and disposed radially between the journal housing member and the shaft with respect to the axis, the top foil member comprising at least one top foil disposed within the bore radially between the at least one biasing foil and the shaft with respect to the axis, wherein the at least one biasing foil is disposed circumferentially along the inner diameter surface and the first relief region;

wherein the at least one biasing foil comprises a first biasing foil having first opposing ends that are retained by the journal housing wall and a first intermediate portion that is disposed between the first opposing ends, wherein the first intermediate portion is disposed circumferentially along the inner diameter surface and the first relief region;

wherein the first intermediate portion has an arcuate, elongated form comprising a wavy pattern including peaks and valleys extending in a circumferential direction between the opposing ends, and wherein a plurality of the peaks abuts the inner diameter surface adjacent to the first relief region and at least one of the peaks is disposed circumferentially along the first relief region; and

wherein the at least one of the peaks is spaced apart from the inner relief surface.

2 . The journal foil bearing system of claim 1 , wherein the at least one of the peaks comprises two adjacent peaks that are disposed circumferentially along the first relief region.

3 . The journal foil bearing system of claim 1 , wherein the at least one of the peaks comprises three adjacent peaks that are disposed circumferentially along the first relief region.

4 . The journal foil bearing system of claim 1 , wherein the at least one of the peaks that is disposed circumferentially along the first relief region is disposed adjacent to one of the first opposing ends.

5 . The journal foil bearing system of claim 1 , wherein the at least one of the peaks that is disposed circumferentially along the first relief region is disposed between the plurality of peaks that abuts the inner diameter surface adjacent to the first relief region.

6 . The journal foil bearing system of claim 1 , wherein the journal housing wall locally along the inner diameter surface has a second relief region that that is circumferentially spaced apart from the first relief region and that extends in the depth direction from the bore to a corresponding inner relief surface that is spaced apart from the axis a corresponding radius distance that is greater than the nominal radius distance, and wherein the at least one biasing foil further comprises a second biasing foil having second opposing ends retained by the journal housing wall and a second intermediate portion that is disposed between the second opposing ends, wherein the second intermediate portion is disposed circumferentially along the inner diameter surface and the second relief region.

7 . The journal foil bearing system of claim 6 , wherein the first and second relief regions are disposed on opposing sides of the inner diameter surface.

8 . The journal foil bearing system of claim 7 , wherein the first and second relief regions are diametrically opposed.

9 . The journal foil bearing system of claim 7 , wherein the first and second relief regions are disposed at an angle to each other relative to the axis of from about 120° to about 179°.

10 . The journal foil bearing system of claim 1 , wherein a difference between the radius distance and the nominal radius distance is from about 0.025 mm to about 0.25 mm.

11 . The journal foil bearing system of claim 1 , wherein at least one peak of the at least one biasing foil that is disposed circumferentially along the first relief region is spaced apart from the inner relief surface by a distance from about 0.025 mm to about 0.25 mm.

12 . A journal foil bearing system comprising:

a journal housing member comprising a journal housing wall that is disposed about a bore that extends along an axis, the journal housing wall having an inner diameter surface that faces the bore and that is spaced apart generally a nominal radius distance from the axis, wherein the journal housing wall locally along the inner diameter surface has a first relief region that extends in a depth direction from the bore to an inner relief surface that is spaced apart from the axis a radius distance that is greater than the nominal radius distance;

a shaft disposed within the bore and supported for rotation about the axis relative to the journal housing member; and

a biasing foil member and a top foil member, the biasing foil member comprising a first biasing foil and a second biasing foil received within the bore and disposed radially between the journal housing member and the shaft with respect to the axis, the top foil member comprising a single top foil disposed within the bore radially between the first and second biasing foils and the shaft with respect to the axis;

wherein the first biasing foil is disposed circumferentially along the inner diameter surface and the first relief region,

wherein the second biasing foil is disposed circumferentially along the inner diameter surface on a side opposite the first relief region, and

wherein at least one peak of the first biasing foil is disposed circumferentially along the first relief region and is spaced apart from the inner relief surface by a distance from about 0.025 mm to about 0.25 mm.

13 . The journal foil bearing system of claim 12 , wherein the journal housing wall further comprises a second relief region disposed circumferentially from the first relief region, the first and second relief regions being disposed at an angle relative to the axis of from about 120° to about 179°.

14 . The journal foil bearing system of claim 12 ,

wherein the first biasing foil includes an intermediate portion having an arcuate, elongated form with a wavy pattern including peaks and valleys extending in a circumferential direction between opposing ends,

wherein the wavy pattern includes the at least one peak of the first biasing foil that is disposed circumferentially along the first relief region and spaced apart from the inner relief surface, and a plurality of additional peaks abutting the inner diameter surface adjacent to the first relief region, and

wherein elastic deformation of the wavy pattern peaks compensates for dimensional variation in the journal housing member, the foil arrangement, or the shaft resulting from manufacturing or assembly tolerances.

15 . The journal foil bearing system of claim 12 , wherein the journal housing wall defines axially extending grooves recessed from the inner diameter surface and dimensioned to receive ends of the top foil and the first and second biasing foils so as to retain the first and second foils in position during operation.

16 . A method for making a journal foil bearing system, the method comprising:

providing a journal housing member that comprises a journal housing wall disposed about a bore that extends along an axis, the journal housing wall having an inner diameter surface that faces the bore and that is spaced apart generally a nominal radius distance from the axis, wherein the journal housing wall locally along the inner diameter surface has a first relief region that extends in a depth direction from the bore to an inner relief surface that is spaced apart from the axis a radius distance that is greater than the nominal radius distance;

disposing a foil arrangement within the bore;

inserting a shaft within the bore and supporting the shaft with the foil arrangement for rotation about the axis relative to the journal housing member, wherein the foil arrangement comprises a biasing foil member and a top foil member, the biasing foil member comprising at least one biasing foil received within the bore and disposed radially between the journal housing member and the shaft with respect to the axis, the top foil member comprising at least one top foil disposed within the bore radially between the at least one biasing foil and the shaft with respect to the axis, wherein the at least one biasing foil is disposed circumferentially along the inner diameter surface and the first relief region;

wherein the at least one biasing foil comprises a first biasing foil having first opposing ends and a first intermediate portion that is disposed between the first opposing ends,

wherein disposing the foil arrangement further comprises retaining the first opposing ends by the journal housing wall and disposing the first intermediate portion circumferentially along the inner diameter surface and the first relief region;

wherein the first intermediate portion has an arcuate, elongated form comprising a wavy pattern including peaks and valleys extending in a circumferential direction between the opposing ends, and wherein disposing the first intermediate portion comprises abutting a plurality of the peaks against the inner diameter surface adjacent to the first relief region and disposing at least one of the peaks circumferentially along the first relief region; and

wherein disposing the first intermediate portion comprises disposing at least two adjacent peaks circumferentially along the first relief region.

17 . The method of claim 16 , further comprising the steps of:

providing a second relief region in the journal housing wall, wherein the first and second relief regions are disposed on opposing sides of the inner diameter surface and are separated by an angle relative to the axis of from about 120° to about 179°;

inserting the first opposing ends of the first biasing foil and the ends of the top foil into axially-extending grooves formed in the inner diameter surface of the journal housing wall;

wherein the at least one of the peaks disposed along the first relief region is spaced apart from the inner relief surface by a distance from about 0.025 mm to about 0.25 mm; and

wherein disposing the first biasing foil further comprises compensating for variation in dimensional tolerances among the journal housing member, foil arrangement, and shaft.