Bearings and mechanical seals enhanced with microstructures

• US 6,280,090 B1
• Filed: 09/14/2000
• Issued: 08/28/2001
• Est. Priority Date: 08/08/1997
• Status: Expired due to Fees

• Current Assignee: Board of Supervisors of Louisiana State University Agricultural & Mechanical College (Louisiana State University System)
• Original Assignee: Board of Supervisors of Louisiana State University Agricultural & Mechanical College (Louisiana State University System)
• Inventors: Stephens, Lyndon S., Kelly, Kevin W.
• Primary Examiner(s): Hannon, Thomas R.
• Application Number:
  US09/661,756
• Time in Patent Office: 348 Days
• Field of Search: 384/276, 384/277, 384/278, 384/284, 384/293, 384/476, 384/625, 384/907
• US Class Current: 384/284
• CPC Class Codes: F16C 17/026 with helical grooves in the bearing surface to generate hydrodynamic pressure, e.g. herringbone grooves
• CPC Class Codes: F16C 17/04 for axial load only
• CPC Class Codes: F16C 17/045 with grooves in the bearing surface to generate hydrodynamic pressure, e.g. spiral groove thrust bearings
• CPC Class Codes: F16C 33/1065 Grooves on a bearing surface for distributing or collecting the liquid
• CPC Class Codes: F16C 33/24 with different areas of the sliding surface consisting of different materials
• CPC Class Codes: F16J 15/3424 with microcavities
• CPC Class Codes: F28F 13/185 Heat-exchange surfaces provided with microstructures or with porous coatings
• CPC Class Codes: F28F 2260/02 having microchannels

Abstract

Properties of mechanical bearings and mechanical seals can be significantly improved by covering the load-bearing surfaces with fields of high aspect ratio microstructures (HARMs), such as microchannels or microposts. The HARMs can substantially enhance heat transfer capability and lubricant flow. The present invention uses microstructures and micro-channels manufactured by a modified LIGA process to enhance the performance of load bearing surfaces. Benefits include reduced operating temperatures, precise metering of lubricant flow to all affected surfaces, increased reliability, increased life, higher maximum rotational speed, and the ability of the seal or bearing to run “dry,” that is, without periodic re-application of lubricant. The invention may be used with a variety of bearings and mechanical seals, including for example ball bearings, roller bearings, journal bearings, air bearings, magnetic bearings, single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines. Improved cooling jackets are also disclosed, for use with bearings, seals, or other applications.

Claims

1. A journal bearing comprising a stator and a journal interior to said stator, said stator having a face in contact with said journal, and said journal having a face in contact with said stator, wherein at least one of said faces:

(a) comprises a plurality of microstructures covering between about 10% and about 70% of the area of said face, wherein each of said microstructures comprises a distal end and a proximal end;

(b) the proximal end of each of said microstructures is connected to said face;

(c) the distal end of each of said microstructures is not connected to a shield, wall, or other object that inhibits heat transfer;

(d) the distance between the proximal and distal ends of each of said microstructures is between about 0.05 mm and about 1.0 mm, and the aspect ratio of each of said microstructures is between about 0.2 and about 20;

wherein the aspect ratio of a microstructure is the ratio of the distance between the proximal end and the distal end to the characteristic dimension of the microstructure;

wherein the characteristic dimension of the microstructure is the diameter of the microstructure in a plane perpendicular to a line between the proximal end and the distal end of the microstructure; and

(e) wherein, if a lubricant is applied to said face, then in the presence of a load between said journal and said stator, said microstructures and the spaces between adjacent microstructures are adapted to cause the lubricant to flow to substantially all portions of said face subject to the load;

whereby heat transfer at the interface of said journal and said stator is substantially greater than would be the heat transfer between an otherwise identical stator and an otherwise identical journal, both of which lacked said microstructures; and

whereby, if a lubricant is applied to said face, the friction between said journal and said stator is substantially less than would be the friction between an otherwise identical stator and an otherwise identical journal, both of which lacked said microstructures.

2. A journal bearing as recited in claim 1, wherein each of said microstructures has a rectangular cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

3. A journal bearing as recited in claim 1, wherein each of said microstructures has a square cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

4. A journal bearing as recited in claim 1, wherein each of said microstructures has a circular cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

5. A journal bearing as recited in claim 1, wherein each of said microstructures has an impeller blade cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

6. A journal bearing as recited in claim 1, wherein the aspect ratio of each of said microstructures is between about 0.25 and about 1.0.

7. A journal bearing as recited in claim 1, wherein said bearing is adapted to hold a sealed liquid lubricant that need not be replenished when said bearing is in use.

8. A journal bearing as recited in claim 1, wherein said bearing is adapted to hold a sealed solid lubricant that need not be replenished when said bearing is in use.

9. A shaft-thrust bearing comprising a shaft and a thrust bearing, said shaft having a face in contact with said thrust bearing, and said thrust bearing having a face in contact with said shaft, wherein at least one of said faces:

(a) comprises a plurality of microstructures covering between about 10% and about 70% of the area of said face, wherein each of said microstructures comprises a distal end and a proximal end;

(b) the proximal end of each of said microstructures is connected to said face;

(c) the distal end of each of said microstructures is not connected to a shield, wall, or other object that inhibits heat transfer,

(d) the distance between the proximal and distal ends of each of said microstructures is between about 0.05 mm and about 1.0 mm, and the aspect ratio of each of said microstructures is between about 0.2 and about 20;

wherein the aspect ratio of a microstructure is the ratio of the distance between the proximal end and the distal end to the characteristic dimension of the microstructure;

wherein the characteristic dimension of the microstructure is the diameter of the microstructure in a plane perpendicular to a line between the proximal end and the distal end of the microstructure; and

(e) wherein, if a lubricant is applied to said face, then in the presence of a load between said shaft and said thrust bearing, said microstructures and the spaces between adjacent microstructures are adapted to cause the lubricant to flow to substantially all portions of said face subject to the load;

whereby heat transfer at the interface of said shaft and said thrust bearing is substantially greater than would be the heat transfer between an otherwise identical shaft and an otherwise identical thrust bearing, both of which lacked said microstructures; and

whereby, if a lubricant is applied to said face, the friction between said shaft and said thrust bearing is substantially less than would be the friction between an otherwise identical shaft and an otherwise identical thrust bearing, both of which lacked said microstructures.

10. A shaft-thrust bearing as recited in claim 9, wherein each of said microstructures has a rectangular cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

11. A shaft-thrust bearing as recited in claim 9, wherein each of said microstructures has a square cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

12. A shaft-thrust bearing as recited in claim 9, wherein each of said microstructures has a circular cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

13. A shaft-thrust bearing as recited in claim 9, wherein each of said microstructures has an impeller blade cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

14. A shaft-thrust bearing as recited in claim 9, wherein the aspect ratio of each of said microstructures is between about 0.25 and about 1.0.

15. A shaft-thrust bearing as recited in claim 9, wherein said bearing is adapted to hold a sealed liquid lubricant that need not be replenished when said bearing is in use.

16. A shaft-thrust bearing as recited in claim 9, wherein said bearing is adapted to hold a sealed solid lubricant that need not be replenished when said bearing is in use.

17. A heat transfer device for heating or cooling an apparatus, comprising a first face and a second face, wherein:

(a) said first face is in thermal contact with the apparatus to be heated or cooled, or is adapted to be placed in thermal contact with the apparatus, or is part of the apparatus;

(b) the device additionally comprises a plurality of microstructures connecting said first and second faces, and covering between about 10% and about 70% of the area of each of said faces;

(c) the distance between said first and second faces is between about 0.05 mm and about 1.0 mm, and the aspect ratio of each of said microstructures is between about 0.5 and about 75;

wherein the aspect ratio of a microstructure is the ratio of the distance between said faces to the characteristic dimension of the microstructure;

wherein the characteristic dimension of the microstructure is the diameter of the microstructure in a plane perpendicular to a line between said faces; and

(d) wherein the space between said faces and said microstructures is adapted for circulation of a refrigerant fluid to carry heat to or from the apparatus.

18. A heat transfer device as recited in claim 17, wherein the aspect ratio of each of said microstructures is between about 1 and about 15.

19. A combination of a heat transfer device as recited in claim 17 and a bearing or seal, wherein said bearing or seal is in thermal contact with said heat transfer device, and wherein said bearing or seal is the apparatus heated or cooled by said device.

20. A combination of a heat transfer device as recited in claim 17 and a source of circulating refrigerant, wherein the refrigerant is circulated within the space between said faces and said microstructures, to transfer heat to or from the device and apparatus.

21. A ball bearing comprising a first race, and a second race interior to said first race, and a plurality of load-bearing balls between said first and second races, each of said races having a face in contact with said balls, wherein at least one of said faces:

(a) comprises a plurality of microstructures covering between about 10% and about 70% of the area of said face, wherein each of said microstructures comprises a distal end and a proximal end;

(b) the proximal end of each of said microstructures is connected to said face;

(c) the distal end of each of said microstructures is not connected to a shield, wall, or other object that inhibits heat transfer;

(d) the distance between the proximal and distal ends of each of said microstructures is between about 0.05 mm and about 1.0 mm, and the aspect ratio of each of said microstructures is between about 0.2 and about 5.0;

wherein the aspect ratio of a microstructure is the ratio of the distance between the proximal end and the distal end to the characteristic dimension of the microstructure;

wherein the characteristic dimension of the microstructure is the diameter of the microstructure in a plane perpendicular to a line between the proximal end and the distal end of the microstructure; and

(e) wherein, if a lubricant is applied to said face, then in the presence of a load between said races, said microstructures and the spaces between adjacent microstructures are adapted to cause the lubricant to flow to substantially all portions of said face subject to the load;

whereby heat transfer at the interface of said races is substantially greater than would be the heat transfer between otherwise identical races, both of which lacked said microstructures; and

whereby, if a lubricant is applied to said face, the friction between said races is substantially less than would be the friction between otherwise identical races, both of which lacked said microstructures.

22. A ball bearing as recited in claim 21, wherein each of said microstructures has a rectangular cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

23. A ball bearing as recited in claim 21, wherein each of said microstructures has a square cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

24. A ball bearing as recited in claim 21, wherein each of said microstructures has a circular cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

25. A ball bearing as recited in claim 21, wherein each of said microstructures has an impeller blade cross section in a direction perpendicular to a line between the proximal end and the distal end of said microstructure.

26. A ball bearing as recited in claim 21, wherein the aspect ratio of each of said microstructures is between about 0.25 and about 0.5.

27. A ball bearing as recited in claim 21, wherein said bearing is adapted to hold a sealed liquid lubricant that need not be replenished when said bearing is in use.

28. A ball bearing as recited in claim 21, wherein said bearing is adapted to hold a sealed solid lubricant that need not be replenished when said bearing is in use.

29. A bearing comprising a first member and a second member, wherein each of said members has a surface in contact with the other said member, and wherein said first member is adapted to movably support said second member under a load, wherein at least one of said surfaces:

(a) comprises a plurality of microstructures covering between about 10% and about 70% of the area of said first surface, wherein each of said microstructures comprises a distal end and a proximal end;

(b) the proximal end of each of said microstructures is connected to said first surface;

(c) the distal end of each of said microstructures is not connected to a shield, wall, or other object that inhibits heat transfer;

(d) the distance between the proximal and distal ends of each of said microstructures is between about 0.05 mm and about 1.0 mm, and the aspect ratio of each of said microstructures is between about 0.5 and about 75;

wherein the aspect ratio of a microstructure is the ratio of the distance between the proximal end and the distal end to the characteristic dimension of the microstructure;

wherein the characteristic dimension of the microstructure is the diameter of the microstructure in a plane perpendicular to a line between the proximal end and the distal end of the microstructure; and

(e) wherein, if a lubricant is applied to said first surface, then in the presence of a load between said first and second surfaces, said microstructures and the spaces between adjacent microstructures are adapted to cause the lubricant to flow to substantially all portions of said first surface subject to the load;

whereby heat transfer at the interface of said first and second surfaces is substantially greater than would be the heat transfer between otherwise identical surfaces lacking said microstructures; and

whereby, if a lubricant is applied to said first surface, the friction between said first and second surfaces is substantially less than would be the friction between otherwise identical surfaces lacking said microstructures.