Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Utility Patent
1998-12-08
2001-01-02
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S560000, C029S417000
Utility Patent
active
06168164
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to hydrodynamic seals and more particularly to the formation of the hydrodynamic grooves in such seals.
2. Related Prior Art
Hydrodynamic shaft seals are conventionally made by molding, embossing, or cutting a spiral groove or other hydrodynamic structure or aid into the seal. The hydrodynamic groove interacts with the rotating shaft to pump any lubricating oil that may find its way under the seal back to the oil side of the seal.
Hydrodynamic aids often take the form of a spiraling groove as illustrated, for example, in U.S. Pat. No. 4,739,998, or an open spiraling channel as illustrated, for example, in U. S. Pat. No. 3,857,156. Each of the above hydrodynamic configurations has its advantages and disadvantages.
The spiraling grooves generally extend deeper into the seal than do the open spiraling channels and as such generally increase the flexibility of the seal to a greater extent than do channels. The increased flexibility advantageously decreases the required sealing force that the seal must exert about the shaft to effect a fluid tight seal, thereby decreasing wear and prolonging the life of the seal. The closed nature of such grooves, however, provides less fluid pumping action than an open spiraling channel.
The open spiraling channels have greater fluid pumping capacity due to the relatively larger fluid volume capacity they offer, but generally are less effective at increasing the flexibility of seals. There is an upper limit to the size of such open channels. Making them too large in an effort to increase flexibility can impair the static sealing capabilities and/or lead to excessive hydrodynamic pumping action, both of which are detrimental to the performance of the seal.
It is a principal object of the present invention to provide a hydrodynamic shaft seal having the benefits of both of the mentioned closed groove and open channel hydrodynamic aids without their inherent drawbacks.
SUMMARY OF THE INVENTION
A hydrodynamic shaft seal assembly is provided comprising a carrier, a seal member mounted on the carrier for sealingly engaging a relatively rotatable shaft, and at least one hydrodynamic feature formed on the seal member having a spiraling open channel portion and at least one spiraling flex-enhancing cut extending from the open channel portion into the seal member.
The shaft seal is thus a hybrid of sorts between an open channel-type hydrodynamic seal and a closed groove-type hydrodynamic seal. The open channel portion optimizes hydrodynamic pumping action and minimizes the entrapment of debris while the flex-enhancing cut optimizes seal flexibility without sacrificing the static and hydrodynamic sealing capabilities of the seal.
The invention also provides a method of forming such a hydrodynamic groove in a shaft seal comprising forming the spiraling open channel portion in a face of the shaft seal along with forming the flex-enhancing cut portion extending into the seal from the open channel portion. Shaft seals formed according to the method of the invention share the same advantages discussed above.
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Smith Stanley N.
Toth David M.
Federal-Mogul World Wide Inc.
Knight Anthony
Patel Vishal
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
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