Hydrodynamic seal with circumferentially varying lift force
View Patent ↗A seal assembly which operates efficiently at high altitudes and low surface speeds includes a first seal ring, a second seal ring, and hydropads. The first seal ring is of a generally annular shape and defining radial and circumferential directions. The second seal ring is positioned in facing relation to the first seal ring and rotatably mounted relative to the first seal ring about an axis of rotation. A plurality of hydropads formed on one of the first seal ring and second seal ring provides a lift force that varies about the circumference of the mating ring.
1. A seal assembly comprising:
a first seal ring of a generally annular shape and defining radial and circumferential directions;
a second seal ring rotatably mounted about an axis of rotation and positioned in facing relation to said first seal ring to define an interface therebetween;
a plurality of hydropads formed in one of said first seal ring and second seal ring, each of said hydropads having an inner edge and an outer edge spaced radially outwardly from said inner edge, said inner edges defining an inner circumference of said hydropads and said outer edges defining an outer circumference of said hydropads, and one of said inner circumference and said outer circumference being eccentric relative to said axis of rotation; and
an entry point formed on a portion of one of an inner circumference and an outer circumference of one of said first seal ring and said second seal ring for introducing fluid between said first seal ring and said second seal ring, said entry point extending past at least two of said hydropads and less than all of said one of an inner circumference and an outer circumference of one of said first seal ring and said second seal ring.
2. The seal assembly as in claim 1 , in which said outer circumference of said hydropads is eccentric relative to said axis of rotation.
3. The seal assembly as in claim 1 , in which the other of said inner circumference and said outer circumference of said hydropads is substantially equidistant from said axis of rotation.
4. The seal assembly as in claim 1 , in which each of said hydropads includes a leading edge interconnecting said inner edge with said outer edge.
5. The seal assembly as in claim 1 , in which each of said hydropads includes a trailing edge interconnecting said inner edge with said outer edge.
6. The seal assembly as claimed in claim 1 , wherein said hydropads are positioned to pump air from an inner diameter of said seal assembly toward an outer diameter of said seal assembly.
7. The seal assembly as in claim 1 , in which said entry point is formed along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring including where said hydropads extend the least in a direction of pumping, and said entry point does not extend along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring where said hydropads extend the greatest in the direction of pumping.
8. A seal assembly comprising:
a first seal ring of a generally annular shape and defining radial and circumferential directions; and
a second seal ring positioned in facing relation to said first seal ring and rotatably mounted relative to said first seal ring about an axis of rotation;
a plurality of hydropads formed in one of said first seal ring and second seal ring and providing a lift force which varies about a circumference of said one of said first seal ring and said second seal ring; and
an entry point formed on a portion of one of an inner circumference and an outer circumference of one of said first seal ring and said second seal ring for introducing fluid between said first seal ring and said second seal ring, said entry point extending past at least two of said hydropads and less than all of said one of an inner circumference and an outer circumference of one of said first seal ring and said second seal ring.
9. The seal assembly as in claim 8 , in which each of said hydropads has a nominal center interposed between an inner edge and an outer edge, and said nominal centers are circumferentially spaced about a point offset from said axis of rotation.
10. The seal assembly as in claim 9 , in which said inner edges define an inner circumference of said hydropads and said outer edges define an outer circumference of said hydropads, and one of said inner circumference and said outer circumference of said hydropads is eccentric relative to said axis of rotation.
11. The seal assembly as in claim 10 , in which said outer circumference of said hydropads is eccentric relative to said axis of rotation.
12. The seal assembly as in claim 10 , in which the other of said inner circumference and said outer circumference of said hydropads is substantially equidistant from said axis of rotation.
13. The seal assembly as in claim 9 , in which each of said hydropads includes a leading edge interconnecting said inner edge with said outer edge.
14. The seal assembly as in claim 9 , in which each of said hydropads includes a trailing edge interconnecting said inner edge with said outer edge.
15. The seal assembly as claimed in claim 8 , wherein said hydropads are positioned to pump air from an inner diameter of said seal assembly toward an outer diameter of said seal assembly.
16. The seal assembly as in claim 8 , in which said entry point is formed along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring including where said hydropads extend the least in a direction of pumping, and said entry point does not extend along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring where said hydropads extend the greatest in the direction of pumping.
17. A seal assembly comprising:
a first seal ring of a generally annular shape and defining radial and circumferential directions; and
a second seal ring positioned in facing relation to said first seal ring and rotatably mounted relative to said first seal ring about an axis of rotation;
a plurality of hydropads formed in one of said first seal ring and second seal ring and defining an eccentric ring about said axis of rotation; and
an entry point formed on a portion of one of an inner circumference and an outer circumference of one of said first seal ring and said second seal ring for introducing fluid between said first seal ring and said second seal ring, said entry point extending past at least two of said hydropads and less than all of said one of an inner circumference and an outer circumference of one of said first seal ring and said second seal ring.
18. The seal assembly as in claim 17 , in which each of said hydropads generates lift and has an inner edge and an outer edge spaced radially outwardly from said inner edge, said inner edges define an inner circumference of said hydropads and said outer edges define an outer circumference of said hydropads, and one of said inner circumference and said outer circumference of said hydropads defines said eccentric ring about said axis of rotation.
19. The seal assembly as in claim 18 , in which said outer circumference of said hydropads is eccentric relative to said axis of rotation.
20. The seal assembly as in claim 18 , in which the other of said inner circumference and said outer circumference of said hydropads is substantially equidistant from said axis of rotation.
21. The seal assembly as in claim 17 , in which said entry point is formed along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring including where said hydropads extend the least in a direction of pumping, and said entry point does not extend along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring where said hydropads extend the greatest in the direction of pumping.
22. A seal assembly comprising:
a first seal ring;
a second seal ring rotatably mounted about an axis of rotation and positioned in facing relation to said first seal ring to define an interface therebetween;
a plurality of hydropads formed in one of said first seal ring and second seal ring and defining an eccentric ring about said axis of rotation; and
an entry point extending along only a portion of one of an inner circumference and an outer circumference of one of said first seal ring and said second seal ring for introducing fluid between said first seal ring and said second seal ring, said entry point extending past at least two of said hydropads along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring including where said hydropads extend the least in a direction of pumping.
23. The seal assembly as in claim 22 , in which and said entry point does not extend along a portion of said one of said inner circumference and said outer circumference of one of said first seal ring and said second seal ring where said hydropads extend the greatest in the direction of pumping.