Foil bearing and driveshaft assemblies and compressor including same

1. A bearing system comprising:

a sleeve including a radial inner surface defining a cylindrical bore; and

a foil bearing assembly positioned within the cylindrical bore of the sleeve, wherein the foil bearing assembly includes:

a top foil layer; and

an outer layer positioned between the top foil layer and the radial inner surface; and

a driveshaft including a recess axially aligned with the top foil layer, the recess defines a cavity having a volume, the recess includes a leading end at a first circumferential position and a trailing end at a second circumferential position, wherein the volume of the cavity decreases from the leading end to the trailing end.

2. The bearing system of claim 1 , wherein the recess includes a recess depth that is greatest at the leading end.

3. The bearing system of claim 1 , wherein the leading end includes a first axial length and the trailing end includes a second axial length, wherein the first axial length is longer than the second axial length.

4. The bearing system of claim 1 , wherein the recess includes a recess depth that decreases from the leading end to the trailing end, wherein the recess depth at the trailing end is zero.

5. The bearing system of claim 4 , wherein the driveshaft includes three of the recesses arranged in a radially symmetric pattern, wherein each of the recesses include a recess arc angle α between the leading end and the trailing end, wherein the recess arc angle α is between 50° and 60°.

6. The bearing system of claim 1 , wherein the driveshaft includes a plurality of the recesses arranged in a radially symmetric pattern about a rotational axis of the driveshaft.

7. The bearing system of claim 1 , wherein the driveshaft includes a first portion and an opposing second portion that is axially offset from the first portion, wherein the driveshaft further comprises a first set including at least one of the recess formed at the first portion and a second set including at least one of the recess formed at the second portion.

8. The bearing system of claim 7 , wherein the first set includes a plurality of the recess arranged in a radially symmetric pattern, and the second set includes the same number of the recess as the first set, and wherein the second set are arranged in a radially symmetric pattern that is the same as the radially symmetric pattern of the first set.

9. The bearing system of claim 1 , wherein the recess has a base surface extending between the leading end and the trailing end, wherein the base surface is arched and has a radius of curvature that is less than a radius of curvature of an outer surface of the driveshaft.

10. A compressor comprising:

a compressor housing;

a bearing housing mounted to the compressor housing; and

a bearing system supported by the bearing housing, the bearing system comprising:

a sleeve including a radial inner surface defining a cylindrical bore; and

a foil bearing assembly positioned within the cylindrical bore of the sleeve, wherein the foil bearing assembly includes:

a top foil layer; and

an outer layer positioned between the top foil layer and the radial inner surface; and

a driveshaft including a recess axially aligned with the top foil layer, the recess defines a cavity having a volume, the recess includes a leading end at a first circumferential position and a trailing end at a second circumferential position, wherein the volume of the cavity decreases from the leading end to the trailing end.

11. The compressor of claim 10 , wherein the recess includes a recess depth that is greatest at the leading end.

12. The compressor of claim 10 , wherein the leading end includes a first axial length and the trailing end includes a second axial length, wherein the first axial length is longer than the second axial length.

13. The compressor of claim 10 , wherein the recess includes a recess depth that decreases from the leading end to the trailing end, wherein the recess depth at the trailing end is zero.

14. The compressor of claim 13 , wherein the driveshaft includes three of the recesses arranged in a radially symmetric pattern, wherein each of the three recesses include a recess arc angle α between the leading end and the trailing end, wherein the recess arc angle is a between 50° and 60°.

15. The compressor of claim 10 , wherein the driveshaft includes a plurality of the recesses arranged in a radially symmetric pattern about a rotational axis of the driveshaft.

16. The compressor of claim 10 , wherein the driveshaft includes a first portion and an opposing second portion that is axially offset from the first portion, wherein the driveshaft further comprises a first set of at least one of the recess formed at the first portion and a second set of at least one of the recess formed at the second portion.

17. The compressor of claim 16 , wherein the first set includes a plurality of recesses arranged in a radially symmetric pattern, and the second set includes the same number of recesses as the first set, and wherein the second set are arranged in a radially symmetric pattern that is the same as the radially symmetric pattern of the first set.

18. The compressor of claim 16 , wherein the first set includes a plurality of the recesses arranged in a radially symmetric pattern, and the second set includes a different number of the recesses as the first set, and wherein the second set are arranged in a radially symmetric pattern.

19. The compressor of claim 10 , wherein the recess has a base surface extending between the leading end and the trailing end, wherein the base surface is arched and has a radius of curvature that is the same as a radius of curvature of an outer surface of the driveshaft.