Airfoil bearing arrangement and method for making the same

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.

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.