Mechanical seals enhanced with microstructures

• US 6,149,160 A
• Filed: 08/05/1998
• Issued: 11/21/2000
• 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: Kelly, Kevin W., Stephens, Lyndon S.
• Primary Examiner(s): Knight, Anthony
• Assistant Examiner(s): Beres, John L.
• Application Number:
  US09/129,562
• Time in Patent Office: 839 Days
• Field of Search: 277/399, 277/400, 277/408, 277/559, 277/571
• US Class Current: 277/399
• 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 mechanical seal comprising at least at two faces that seal to one another, a first face and a second face, wherein said first face:

(a) comprises a plurality of microstructures covering between about 10% and about 70% of the area of said first 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 first 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 0.5 and about 50;

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 face, then in the presence of a load between said first and second faces, said microstructures and the spaces between adjacent microstructures are adapted to cause the lubricant to flow to substantially all portions of said first face subject to the load;

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

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

2. A mechanical seal 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 mechanical seal 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 mechanical seal 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 mechanical seal 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 mechanical seal as recited in claim 1, wherein the aspect ratio of each of said microstructures is between about 1 and about 10.

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

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

9. A seal comprising at least at two surfaces that seal to one another, a first surface and a second surface, wherein said first surface:

(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.