CA2887776C - Rotary seal with improved film distribution - Google Patents

Abstract

The present invention is a generally circular rotary seal that establishes sealing between relatively rotatable machine components for lubricant retention and environmental exclusion, and incorporates seal geometry that interacts with the lubricant during relative rotation to distribute a lubricant film within the dynamic sealing interface. The features of a variable inlet size, a variable dynamic lip flank slope, and a reduction in the magnitude and circumferentially oriented portion of the lubricant side interfacial contact pressure zone at the narrowest part of the lip, individually or in combination thereof, serve to maximize interfacial lubrication in severe operating conditions, and also serve to minimize lubricant shear area, seal torque, seal volume, and wear, while ensuring retrofltability into the seal grooves of existing equipment.

Description

ROTARY SEAL WITH IMPROVED FILM DISTRIBUTION

[0002] This application is a divisional application of Canadian Patent File No. 2,697,678 filed September 2nd, 2008 from PCT Application No. PCT/US2008/010320.
BACKGROUND OF THE INVENTION
1. Field of the Invention.

[0003] This invention relates to hydrodynamic rotary seals for bi-directional rotation that are used to retain a lubricant and exclude an environment. More specifically, this invention relates to cooperative features that improve seal lubrication in conditions such as high operating temperature, skew-resisting confinement, high differential pressure, high initial compression, l adverse tolerance accumulation, circumferential compression, high modulus seal materials, thin viscosity lubricants, third body seal surface wear, and/or material swell (collectively referred to as "severe operating conditions").
2. Description of the Related Art.

[0004] Hydrodynamic seals used in down-hole oilfield tools are being challenged to operate at ever-greater temperatures and differential pressures. Such seals are installed with interference (i.e., compression) and establish sealing by blocking the leak path. For general examples of such seals, see FIG. 3 of U.S. Pat. 5,230,520, FIG. 4 of U.S. Pat. 6,315,302, and FIG. 6 of U.S.
Pat. 6,382,634.

[0005] Upon installation in a compressed condition, hydrodynamic seals define a "footprint"
representing the shape of the "dynamic sealing interface," and the two terms are generally interchangeable. Examples of footprints are shown in FIG. 2 of assignee's U.S.
Pat. 4,610,319 and FIG. 13 of assignee's U.S. Pat. 5,230,520.

[0006] Smaller seal cross-sections are desirable because shaft and housing wall thickness can be maximized. Miniaturization impacts seal lubrication, as described in U.S. Pat.
Appl. Pub.
US2007/0205563, paras. [0036]-[0039]. For a given dimensional compression, interfacial contact pressure increases as a seal cross-section is miniaturized. With radial seals, circumferential compression increases as diameter is miniaturized, increasing footprint spread and contact pressure.

[0007] The skew-induced wear mechanism described and illustrated in FIG. 3-27 of the Kalsi Seals Handbook, Rev. 1 is addressed with skew-resisting confinement of the seal, which increases interfacial contact pressure and footprint spread. The term "skew-resisting confinement," as used herein, encompasses (1) constraint imposed by seal contact with fixed location gland walls as disclosed in U.S. Pat. 6,315,302, and (2) spring-loading through a moveable gland wall, as disclosed in FIG. 3-28 of the Kalsi Seals Handbook, Rev. 1.

[0008] Generally, the conventional wisdom regarding how such hydrodynamic seals lubricate has been described in U.S. Pat. 4,610,319 at col. 9, lines 6-22 and U.S. Pat.
5,230,520, col. 3, lines 30-53. In the '520 patent, FIG. 13 uses a curved arrow to illustrate the conventional wisdom that a normal velocity component VN urges the lubricant toward the environment. The emphasis on VN has caused undue focus on inlet efficiency over the years, and diverted attention from finding other potential lubrication factors. Such conventional wisdom of how these seals operate has been repeated in numerous other patents and commercial literature. See, for example, U.S. Patents 5,678,829 (col. 4, lines 14-33), 5,738,358 (col. 2, lines 17-57), 5,873,576 (col. 2, lines 26-65), 6,036,192 (col. 2, lines 26-65), 6,120,036 (col. 2, lines 18-45), 6,227,547 (col. 11, lines 16-40), 6,315,302 (col. 10, lines 31-46), 6,334,619 (col. 1, line 57- col.
2, line 5), 6,382,634 (col. 11, lines 4-9), 6,685,194 (col. 4, lines 51-55), and 6,767,016 (col. 1, line 27 - col. 2, line 16). Additionally, the conventional wisdom has been that the footprint wave height, per se, is important to lubrication. "Footprint wave height" as used herein refers to the difference in width between the widest and narrowest parts of the footprint.

[0009] The use of the aforementioned conventional wisdom (relating to VN and footprint wave height) is inadequate in designing highly effective hydrodynamic rotary seals for use in severe operating conditions. The use of the conventional wisdom in the design of seals for severe operating conditions has resulted in limited seal effectiveness.

(0010] Another bit of the conventional wisdom pertaining to hydrodynamic rotary seals is related to physical hydrodynamic inlet convergence. A general (and correct) tenant is that more gradual convergence produces more efficient in-pumping. U.S. Patents 6,315,302, 6,382,634 and 6,685,194 teach the use of gradual convergences. Experience has shown that despite their inlet efficiency, such seals lubricate sub-optimally because their designs are based on the conventional wisdom pertaining to footprint wave height and VN.

[0011] U.S. Patent 6,109,618 teaches the use of abrupt trailing edge geometries, that are unsuitable as hydrodynamic inlets, on seals suitable only for uni-directional rotation. This abrupt geometry is on the trailing edges of the waves, and is coupled with a very gently converging inlet geometry on the leading edges. Due to the high hydrodynamic leakage of such geometry, and the small reservoir size of downhole tools, downhole seals cannot employ such geometries.

[0012] The prior art seals are constructed from elastomers which suffer accelerated degradation at elevated temperature. For example, media resistance problems, gas permeation, swelling, compression set, and pressure related extrusion damage all become worse at elevated temperature. A bi-directional rotation seal that operates with less torque and produces less seal-generated heat would be desirable, in order to moderate such degradation.

[0013] Circumferential slippage of a seal with respect to its groove occurs more often with large diameter seals because the moment arms between the static and dynamic sealing interfaces are more nearly equal, and the static sealing interface has less mechanical advantage. Rotational slippage is particularly undesirable in large diameter seals because the slippage can vary around the circumference of the seal, causing undesirable localized stretching. It is also undesirable in seals exposed to high differential pressure because slippage can accelerate seal extrusion damage. Slippage is exacerbated by seal or shaft wear because such wear increases running torque. A bi-directional seal that has lower running torque and more resistance to wear is therefore desirable.

[0014] It is desirable to overcome the aforementioned limitations of prior art seals.
SUMMARY OF THE INVENTION
[00151 The present invention relates to generally circular rotary seals that are suitable for bi-directional rotation, and overcome the aforementioned prior art problems. The seals are used to establish sealing between a machine component (such as a housing) and a relatively rotatable surface (such as a shaft), in order to separate a lubricating media from an environment. Seal geometry on a dynamic lip interacts with the lubricating media during relative rotation to wedge a lubricating film into the dynamic sealing interface between the seal and the relatively rotatable surface. A portion of the lubricating film migrates toward, and into the environment and thus provides a contaminant flushing action.
[00161 The rotary seal includes a dynamic lip that deforms when compressed into sealing engagement with the relatively rotatable surface, defining a hydrodynamic wedging angle with respect to the relatively rotatable surface, and defining an interfacial contact footprint of generally circular configuration but varying in width. A non-circular (i.e., wavy) footprint edge hydrodynamically wedges the lubricating film into the interfacial contact footprint.
[0017] One aspect of a preferred embodiment of the present invention involves a newly established variable referred to as EwH. EwH is used herein for a dimension that represents the difference in size between Dimension B2 and Width WI in which Dimension B2 is the dimension from a second footprint edge to a location P2 defining the maximum interfacial contact pressure at the widest footprint location and Width W1 is the footprint width at the narrowest footprint location. In other words, the value of EwH is calculated as Dimension B2 minus the Width W1, and the result may be a positive or negative number, depending on the circumstances.
[0018] It has now been discovered that in the aforementioned cases described in the Background, the lubrication problem occurs because the value of Ewig approaches zero or becomes negative¨a circumstance not contemplated under the conventional wisdom because EwH and its import were unknown. As seal temperature increases, lubrication decreases as the value of Eval decreases. As lubrication decreases, the seal generates more and more heat due to increasing asperity friction, causing a loss of lubricant film viscosity.
These factors further increase seal temperature, compounding the problem and leading to an unsustainable runaway operating condition. Thus, in one embodiment of the rotary seal of the present invention the value of EwH is maintained positive.
[0019] Another embodiment of the present invention is a generally circular, hydrodynamically lubricating rotary seal that accomplishes improved lubrication through the cooperative benefits of a modified zig-zag wave pattern, a variably sized inlet curvature that is a tighter curvature near the widest parts of the dynamic lip, and a less tight curvature near the narrower portions of the dynamic lip, and a dynamic lip flank that is more steeply sloped near the widest parts of the dynamic lip, and less steep near the narrower parts of the dynamic lip.

[0020] The modified zig-zag wave pattern improves interfacial contact pressure gradients and the orientation and/or location of the pressure gradients in critical locations. The variable radius controls the magnitude of the pressure at a critical location, and provides improved inlet convergence, while enhancing factors that contribute to lubrication in severe operating conditions. The variable slope of the dynamic lip flank provides a number of benefits related to a variety of seal performance issues, the most important of which is to minimize seal volume for improved compatibility with skew-resisting confinement.
[0021] The seal preferably provides a dynamic exclusionary intersection of abrupt substantially circular form that provides the interfacial contact footprint with an environment edge that resists environmental intrusion. The seal can be configured for dynamic sealing against a shaft, a bore, or a face. Simplified embodiments are possible wherein one or more features of the preferred embodiment are omitted.
[0022] One aspect of this invention seeks to provide a hydrodynamic rotary seal having low torque for reduced wear and heat generation. Another aspect of an embodiment seeks to improve distribution of lubricant across the dynamic sealing interface, particularly at high operating temperatures. Another aspect of yet another embodiment seeks to conserve void volume within the seal gland, to provide adequate room for seal thermal expansion, considering seal tolerances and as-manufactured variations in the coefficient of thermal expansion of the sealing material, with a view toward improved accommodation of skew-resisting confinement.
[0022a] A preferred aspect of the invention contemplates a rotary seal assembly including a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall, a second machine component located at least partially within the first machine component having a relatively rotatable surface in generally opposed relation to the peripheral groove wall and rotatable relative to the first machine component, and a generally ring-shaped interference-type rotary seal located at least partially within the seal groove that has a volume and includes a seal body of resilient thermally expandable sealing material. The seal body has axially-facing first and second seal ends. In an uncompressed condition, the seal body includes a dynamic lip of generally circular form.
The dynamic lip has an abrupt dynamic exclusionary intersection, a dynamic surface facing radially inward, a lubricant side flank that is non-circular having a slope in an axial direction and located in spaced relation with respect to the dynamic exclusionary intersection, and an inlet curvature located between and separating the dynamic surface and the lubricant side flank and located in spaced relation with respect to the dynamic exclusionary intersection and being at least a portion of a wavy, rotationally bi-directional hydrodynamic geometry. The seal body includes an inwardly facing surface between the first seal end and at least part of the lubricant side flank. The inwardly facing surface and the lubricant side flank are located entirely radially outward of and spaced from the dynamic surface. The dynamic surface extends from the inlet curvature to the dynamic exclusionary intersection, and the dynamic surface has at least two wider surface locations, at least one of the wider surface locations is the widest surface location between two narrower surface locations, at least one of the two narrower surface locations is the narrowest surface location between the at least two wider surface locations. The inlet curvature adjoins the lubricant side flank and the dynamic surface and extends from one of the narrower surface locations, past the widest surface location and past the narrowest surface location to one of the wider surface locations. The dynamic lip is held in compression against the relatively rotatable surface and defines a circumferential interfacial contact footprint against the relatively rotatable surface. The interfacial contact footprint includes peripheral first and second footprint edges with the first footprint edge being generally wavy, where a footprint width is defined between the first and second footprint edges, the interfacial contact footprint has at least two wider footprint locations, at least one of the wider footprint locations is the widest footprint location between 7a two narrower footprint locations, and at least one of the two narrower footprint locations is the narrowest footprint location between the at least two wider footprint locations. The slope of the lubricant side flank in the uncompressed condition is steepest at the widest surface location minimizing the volume, and the compression establishing interfacial contact pressure within the interfacial contact footprint includes a lubricant-side pressure ridge along the first footprint edge. The lubricant-side pressure ridge has a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of the interfacial contact footprint, and at the widest footprint location the interfacial contact pressure increases from zero at the first footprint edge to a greater value at a Position P2 on the ridgeline. The rotary seal maintains a positive value of EwH, wherein EwH = Dimension B2 - Width W1 where Dimension B2 is an axial length from the second footprint edge to the Position P2 on the ridgeline at the widest footprint location, and Width W1 is the axial footprint width at the narrowest footprint location, and the Dimension B2 is governed at least in part by the inlet curvature at the widest dynamic surface location.
[0022b] Yet a further aspect of the invention is a rotary seal assembly that includes a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall, a second machine component located at least partially within the first machine component having a relatively rotatable surface in generally opposed relation to the peripheral groove wall and rotatable relative to the first machine component, and a generally ring-shaped interference-type rotary seal located at least partially within the seal groove with the rotary seal including a seal body of at least one resilient sealing material and the seal body having first and second seal ends. In an uncompressed condition, the seal body includes a dynamic lip having a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward, a lubricant side flank 7b having a slope in an axial direction, and an inlet curvature located between and separating the dynamic surface and the lubricant side flank where the inlet curvature is at least part of a hydrodynamic geometry. The seal body includes an inwardly facing surface between the first seal end and at least part of the lubricant side flank and the dynamic lip projecting radially inward of the inwardly facing surface. The lubricant side flank is located entirely radially outward of and spaced from the dynamic surface. The dynamic surface has an axial width between the dynamic exclusionary intersection and the inlet curvature that increases from a first narrower surface location to a first wider surface location, decreases from the first wider surface location to a second narrower surface location, increases from the second narrower surface location to a second wider surface location, and decreases from the second wider surface location to a third narrower surface location. The first wider surface location is situated between the first and second narrower surface locations and is the widest surface location between the first and second narrower surface locations. The second narrower surface location is situated between the first and second wider surface locations and is the narrowest surface location between the first and second wider surface locations. The second wider surface location is situated between the second and third narrower surface locations and is the widest surface location between the second and third narrower surface locations.
The dynamic lip is held in compression against the relatively rotatable surface and defines a circumferential interfacial contact footprint against the relatively rotatable surface. The interfacial contact footprint comprises peripheral first and second footprint edges. The first footprint edge is generally wavy. The interfacial contact footprint has an axial footprint width between the first and second footprint edges that increases from a first narrower footprint location to a first wider footprint location, decreases from the first wider footprint location to a second narrower footprint location, increases from the second narrower footprint location to a second wider footprint location, and decreases from the second wider footprint location to a third narrower footprint location. The first wider footprint location is situated 7c between the first and second narrower footprint locations and is the widest footprint location between the first and second narrower footprint locations. The second narrower footprint location is situated between the first and second wider footprint locations and is the narrowest footprint location between the first and second wider footprint locations. The second wider footprint location is situated between the second and third narrower footprint locations and is the widest footprint location between the second and third narrower footprint locations. The compression of the dynamic lip against the relatively rotatable surface establishes interfacial contact pressure within the interfacial contact footprint including a lubricant-side pressure ridge along the first footprint edge. The lubricant-side pressure ridge has a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of the interfacial contact footprint. At the first wider footprint location the interfacial contact pressure increases from zero at the first footprint edge to a greater value at a Position P2 on the ridgeline. The rotary seal maintains a positive value of EwH, wherein EwH = Dimension B2 - Width Wi where Dimension B2 is an axial length from the second footprint edge to the Position P2 at the first wider footprint location, and Width WI is the axial footprint width at the second narrower footprint location, and the Dimension B2 is governed at least in part by the inlet curvature at the first wider dynamic surface location. The slope of the lubricant side flank in the uncompressed condition varies from the first wider surface location to the second narrower surface location, the slope being steeper at the first wider surface location than at the second narrower surface location, and is steeper at the first wider footprint location than at the second narrower footprint location. The first wider footprint location corresponds circumferentially to the first wider surface location, and the second narrower surface location corresponds circumferentially to the second narrower footprint location.
7d [0022c] Still a further aspect of the invention is a rotary seal assembly that includes a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall, a second machine component located at least partially within the first machine component having a relatively rotatable surface in generally opposed relation to the peripheral groove wall and rotatable relative to the first machine component, and a generally ring-shaped interference-type rotary seal located at least partially within the seal groove. The rotary seal includes a seal body of resilient thermally expandable sealing material having an operating temperature range having an upper bound defined by an upper temperature. The seal body has first and second seal ends where, in an uncompressed condition, the seal body includes a dynamic lip of generally circular form.
The dynamic lip has an abrupt dynamic exclusionary intersection, a dynamic surface facing radially inward, a lubricant side flank that is non-circular having a slope in an axial direction and located in spaced relation with respect to the dynamic exclusionary intersection and located entirely radially outward of and spaced from the dynamic surface, and an inlet curvature located between and separating the dynamic surface and the lubricant side flank and located in spaced relation with respect to the dynamic exclusionary intersection and is at least a portion of a wavy hydrodynamic geometry. The dynamic surface is separated from the lubricant side flank and extends from the inlet curvature to the dynamic exclusionary intersection. The dynamic surface has at least two wider surface locations. At least one of the wider surface locations is the widest surface location between two narrower surface locations. At least one of the two narrower surface locations is the narrowest surface location between the at least two wider surface locations. The inlet curvature is located between and adjoining the lubricant side flank and the dynamic surface and extends from one of the narrower surface locations, past the widest surface location and past the narrowest surface location to one of the wider surface locations. The rotary seal is held in skew-resisting confinement at the upper temperature by virtue of simultaneous contact of the first seal end with the first groove 7e wall and the second seal end with the second groove wall. The dynamic lip is held in compression against the relatively rotatable surface and defines a circumferential interfacial contact footprint against the relatively rotatable surface. The interfacial contact footprint includes peripheral first and second footprint edges. The first footprint edge is generally wavy. The interfacial contact footprint has an axial footprint width between the first and second footprint edges. The interfacial contact footprint has at least two wider footprint locations, at least one of the wider footprint locations is the widest footprint location between two narrower footprint locations, at least one of the two narrower footprint locations is the narrowest footprint location between the at least two wider footprint locations. The compression of the dynamic lip against the relatively rotatable surface establishes interfacial contact pressure within the interfacial contact footprint including a lubricant-side pressure ridge along the first footprint edge. The lubricant-side pressure ridge has a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of the interfacial contact footprint. A the widest footprint location the interfacial contact pressure increasing from zero at the first footprint edge to a greater value at a Position P2 on the ridgeline. The rotary seal maintains a positive value of EwH at the upper temperature, wherein EwH = Dimension B2 - Width W1 where Dimension B2 is an axial length from the second footprint edge to the Position P2 on the ridgeline at the widest footprint location, and Width W1 is the axial footprint width at the narrowest footprint location, and the Dimension B2 is governed at least in part by the inlet curvature at the widest dynamic surface location.
10022d1 Yet still a further aspect of the invention is a rotary seal assembly that includes a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall, a second machine component located at least 7f partially within the first machine component having a relatively rotatable surface in generally opposed relation to the peripheral groove wall and rotatable relative to the first machine component, and a generally ring-shaped interference-type rotary seal located at least partially within the seal groove. The rotary seal includes a seal body of at least one resilient thermally expandable sealing material having an operating temperature range with an upper bound defined by an upper temperature. The seal body has first and second seal ends.
The rotary seal is held in skew-resisting confinement at the upper temperature by virtue of simultaneous contact of the first seal end with the first groove wall and the second seal end with the second groove wall. In an uncompressed condition, the seal body includes a dynamic lip and an inwardly facing surface with the dynamic lip projecting radially inward from the inwardly facing surface and including a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward, a lubricant side flank having a slope and located entirely radially outward of and spaced from the dynamic surface, and an inlet curvature located between and separating the dynamic surface and the lubricant side flank. The inlet curvature is at least part of a hydrodynamic geometry. The dynamic surface has an axial width between the dynamic exclusionary intersection and the inlet curvature that increases from a first narrower surface location to a first wider surface location, decreases from the first wider surface location to a second narrower surface location, increases from the second narrower surface location to a second wider surface location, and decreases from the second wider surface location to a third narrower surface location. The first wider surface location is situated between the first and second narrower surface locations and is the widest surface location between the first and second narrower surface locations. The second narrower surface location is situated between the first and second wider surface locations and is the narrowest surface location between the first and second wider surface locations. The second wider surface location is situated between the second and third narrower surface locations and is the widest surface location between the second and third narrower surface locations.
7g The dynamic lip is held in compression against the relatively rotatable surface and defines a circumferential interfacial contact footprint against the relatively rotatable surface. The interfacial contact footprint includes peripheral first and second footprint edges. The first footprint edge is generally wavy. The footprint has an axial footprint width between the first and second footprint edges that increases from a first narrower footprint location to a first wider footprint location, decreases from the first wider footprint location to a second narrower footprint location, increases from the second narrower footprint location to a second wider footprint location, and decreases from the second wider footprint location to a third narrower footprint location. The first wider footprint location is situated between the first and second narrower footprint locations and is the widest footprint location between the first and second narrower footprint locations. The second narrower footprint location is situated between the first and second wider footprint locations and is the narrowest footprint location between the first and second wider footprint locations. The second wider footprint location is situated between the second and third narrower footprint locations and is the widest footprint location between the second and third narrower footprint locations. The compression of the dynamic lip against the relatively rotatable surface establishes interfacial contact pressure within the footprint including a lubricant-side pressure ridge along the first footprint edge.
The lubricant-side pressure ridge has a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of the interfacial contact footprint, and at the first wider footprint location the interfacial contact pressure increases from zero at the first footprint edge to a greater value at a Position P2 on the ridgeline. The rotary seal maintains a positive value of EwH at the upper temperature wherein Ewn -= Dimension B2 - Width Wi 7h where Dimension B2 is an axial length from the second footprint edge to the Position P2 on the ridgeline at the widest footprint location, and Width W1 is the axial footprint width at the second narrower footprint location. The first wider footprint location corresponds circumferentially to the first wider surface location, and the second narrower surface location corresponds circumferentially to the second narrower footprint location.
[0022e] Still further, an aspect of the invention is a rotary seal for bi-directional rotation; the rotary seal in an uninstalled condition includes a generally ring-shaped seal body having a circumference. The seal body has first and second seal ends, a dynamic lip and an inwardly facing surface having an exposed length. The dynamic lip projects radially inward of the inwardly facing surface and includes a lubricant side flank, a dynamic exclusionary intersection of abrupt generally circular form, an inlet curvature, and a dynamic surface facing radially inward and ending at the abrupt dynamic exclusionary intersection. The inlet curvature is located between and separates the lubricant side flank and the dynamic surface and varies in position from the dynamic exclusionary intersection about the circumference.
The dynamic surface is located between the inlet curvature and the dynamic exclusionary intersection. The dynamic surface has an axial width from the dynamic exclusionary intersection to the inlet curvature that varies around the circumference of the seal body in a wavy fashion and has at least two wider surface axial width locations and at least two narrower surface axial width locations. One of the narrower surface axial width locations is the narrowest surface axial width location between the at least two wider surface axial width locations and one of the at least two wider surface width locations is the widest surface location between the at least two narrower surface axial width locations. The inlet curvature adjoins the dynamic surface at and between the at least two narrower surface axial width locations and adjoins the dynamic surface at and between the at least two wider surface axial width locations. The lubricant side flank is located entirely radially outward of and is spaced 7i from the dynamic surface. At least a portion of the lubricant side flank is located between at least a portion of the inwardly facing surface and the inlet curvature. The lubricant side flank has an end thereof varying in position from the dynamic exclusionary intersection in a wavy fashion and has a slope in the axial direction that varies along at least part of the circumference. The slope of said lubricant side flank is steeper at at-least some of the wider surface axial width locations than at at-least some of the narrower surface axial width locations.
[0022f] Another aspect of the invention is a hydrodynamic rotary seal for bi-directional rotation; the rotary seal in an uninstalled condition includes a circumferential seal body having a dynamic lip of generally circular form. The seal body forms a ring comprised of sealing material having a thermally expandable seal volume. The seal body includes an inwardly facing surface with the dynamic lip projecting radially inwardly from the inwardly facing surface and includes a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward having an end at the dynamic exclusionary intersection, a lubricant side flank that is non-circular located in spaced relation with respect to the dynamic exclusionary intersection and located entirely radially outward of and spaced from the dynamic surface, and an inlet curvature located between and separating the dynamic surface and the lubricant side flank. The dynamic surface has narrower surface locations and wider surface locations, each of the wider surface locations is the axially widest surface location between a pair of the narrower surface locations, and at least one of the narrower surface locations is the axially narrowest surface location between a pair of the wider surface locations. The inlet curvature is at least a portion of a rotationally bi-directional hydrodynamic inlet capable of providing hydrodynamic lubrication of the dynamic surface in response to clockwise and counter-clockwise relative rotation when installed against a relatively rotatable surface and exposed to a lubricant. The inlet curvature adjoins the 7j dynamic surface at the wider and the narrower surface locations. The lubricant side flank has a slope in an axial direction that varies in steepness. The slope of the lubricant side flank is steeper at the wider surface locations compared to the slope at the at least one narrower surface location, with the slope at the wider surface locations minimizing the seal volume.
[0022g] Yet another aspect of the invention is a ring-shaped hydrodynamic rotary seal for bi-directional rotation; the hydrodynamic rotary seal in an uncompressed condition includes a ring-shaped seal body having a first end and an inwardly facing surface with the seal body including a dynamic lip of generally circular form projecting radially inward from the inwardly facing surface and having a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward, a lubricant side flank that is non-circular and located in spaced relation with respect to the dynamic exclusionary intersection and located entirely radially outward of and spaced from the dynamic surface, an inlet curvature located between and separating the dynamic surface and the lubricant side flank and located in spaced relation with respect to the dynamic exclusionary intersection and being at least a portion of a wavy, rotationally bi-directional hydrodynamic geometry, the dynamic surface extending from the inlet curvature to the dynamic exclusionary intersection. The dynamic surface has at least two wider surface locations with at least one of the wider surface locations being the widest surface location between two narrower surface locations, at least one of the two narrower surface locations being the narrowest surface location between the at least two wider surface locations. The inlet curvature is located between and adjoins the lubricant side flank and the dynamic surface and extends from one of the narrower surface locations, past the widest surface location and past the narrowest surface location to one of the wider surface locations.
The rotary seal is comprised of seal material having a volume. The lubricant side flank has a slope that varies relative to the dynamic surface width, with the slope of the lubricant side flank being steepest at the widest surface location minimizing the volume of the seal material.
7k [0022h] Still another aspect of the invention is a hydrodynamic rotary seal for bi-directional rotation; the rotary seal in an uninstalled condition includes a generally ring-shaped seal body having a first seal end and an inwardly facing surface. The seal body includes a dynamic lip projecting radially inward from the inwardly facing surface and comprises a dynamic surface facing radially inward, a lubricant side flank having a slope and located entirely radially outward of and spaced from the dynamic surface, and an inlet curvature located between and separating the dynamic surface and the lubricant side flank. The inlet curvature is at least part of a rotationally bi-directional hydrodynamic geometry. The dynamic surface has an axial width that increases from a first narrower surface location to a first wider surface location, decreases from the first wider surface location to a second narrower surface location, increases from the second narrower surface location to a second wider surface location, and decreases from the second wider surface location to a third narrower surface location. The first wider surface location is situated between the first and second narrower surface locations and is the widest surface location between the first and second narrower surface locations.
The second narrower surface location is situated between the first and second wider surface locations and is the narrowest surface location between the first and second wider surface locations. The second wider surface location is situated between the second and third narrower surface locations and is the widest surface location between the second and third narrower surface locations. The slope of the lubricant side flank varies from the first wider surface location to the second narrower surface location, with the slope being steeper at the first wider surface location than at the second narrower surface location.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0023] So that the manner in which the above recited features, advantages, and aspects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings only illustrate preferred embodiments of this invention, and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments that vary only in detail.
[0024] In the drawings:
FIG. l is a graph schematically representing a typical interfacial contact pressure plot at a circumferential location of a hydrodynamic seal;
FIG. 2 is a fragmentary cross-sectional view of a ring-shaped hydrodynamic seal according to a preferred embodiment of the present invention, the seal shown in an installed, compressed condition;
FIG. 2A is a fragmentary view of the hydrodynamic seal of FIG. 2 in an uncompressed condition;
FIG. 2B is a section view taken along line 2B-2B of FIGS. 2A and 5;
= FIG. 2C is a section view taken along line 2C-2C of FIGS. 2A, 3, 4, 5, 6, 7 and 8;
FIG. 2D is a section view taken along line 2D-2D of FIGS. 2A, 3, 4, 5, 6 and 7;
FIG. 2E is a fragmentary illustration of the interfacial contact footprint of the hydrodynamic seal of FIG. 2;
FIG. 3 is a fragmentary view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal in an uncompressed condition;

FIG. 3A is a fragmentary illustration of the interfacial contact footprint of the hydrodynamic seal of FIG. 3;
=
FIG. 4 is a fragmentary view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal in an uncompressed condition;
FIG. 4A is a fragmentary illustration of the interfacial contact footprint of the hydrodynamic seal of FIG. 4;
FIG. 4B is a section view taken along line 4B-4B of FIGS. 4, 7 and 8;
FIG. 5 is a fragmentary view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal in an uncompressed condition;
FIG. 5A is a fragmentary illustration of the interfacial contact footprint of the hydrodynamic seal of FIG. 5;
FIG. 6 is a fragmentary view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal in an uncompressed condition;
FIG. 6A is a fragmentary illustration of the interfacial contact footprint of the hydrodynamic seal of FIG. 6;
FIG. 7 is a fragmentary view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal in an uncompressed condition;
FIG. 7A is a fragmentary illustration of the interfacial contact footprint of the hydrodynamic seal of FIG. 7;

FIG. 7B is a graph representing the interfacial contact pressures at selected circumferential slices of the hydrodynamic rotary seal of FIGS. 2A and 7;
FIG. 8 is a fragmentary view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal in an uncompressed condition;
FIG. 8A is a fragmentary illustration of the interfacial contact footprint of the hydrodynamic seal of FIG. 8;
FIG. 9 is a fragmentary cross-sectional view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal shown in an installed, compressed condition;
FIG. 9A is a fragmentary view of the hydrodynamic seal of FIG. 9 in an uncompressed condition;
FIG. 10 is a fragmentary shaded perspective view of an alternative embodiment of the hydrodynamic seal showing a hydrodynamic inlet portion of a wave; and FIG. 11 is a fragmentary cross-sectional view of a hydrodynamic seal according to another preferred embodiment of the present invention, the seal shown in an installed, compressed condition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
1. Description of FIG. 1 [00251 FIGURE 1 is a graph that schematically represents an interfacial contact pressure plot at any circumferential location of a typical seal, for example, manufactured according to one of assignee's U.S. Patents 4,610,319, 5,230,520, 6,315,302, 6,382,634, and so forth. The proportions of a contact pressure plot will vary depending on specific seal geometry and analysis constraints, but the general plot characteristics are captured in FIG. 1. The plot has a first footprint edge L and second footprint edge E, which correspond to the lubricant-side and environment-side edges, respectively, of the dynamic sealing interface/footprint. The direction of relative rotation between the seal and the mating relatively rotatable surface is normal (perpendicular) to the axis labeled "interfacial width", and normal (perpendicular) to the page on which the figure is printed.
[0026] At any given circumferential location of the footprint, the inlet contact pressure rises from zero at the first footprint edge L to a maximum at Location P. Location P
is remote from the first footprint edge L by Dimension A, and is remote from the second footprint edge E by Dimension B. Width W represents the local width of the dynamic sealing interface/footprint.
In the text that follows, these labels and dimensions (i.e., first footprint edge L, second footprint edge E, Location P, Dimension A, Dimension B and Width W) are, when necessary, given a = subscript "1" or "2" to refer to the narrowest or the widest footprint location, respectively.
100271 The aforementioned labels and dimensions are used not only in describing FIG. 1, but are also used elsewhere in this "Description of the Preferred Embodiments," in order to facilitate communication via the use of consistent terminology. In certain figures, the aforementioned subscript "1" is, when necessary, modified by the addition of an "a" or "b" to designate specific locations on multiple wave footprint illustrations.
[0028] The footprint edge represented by second footprint edge E is substantially circular.
Width W varies about the circumference of the seal from a narrowest location defined by Width WI to a widest location defined by Width W2. In assignee's commercial variants suitable for bi-directional rotation, the variation of Width W has been sinusoidal. EwH is a newly established variable that is used herein for a dimension that represents the difference in size between Dimension B2 and Width W1. In other words, the value of EwH is calculated as Dimension B2 minus the Width W1, and the result may be a positive or negative number, depending on the circumstances.
[0029] With seals constructed in accordance with U.S. Patents 4,610,319, 5,230,520, 5,738,358, 6,120,036, 6,315,302, 6,382,634, and so forth, the interfacial contact pressure increases from Location P2 to Location P1, creating a zone of elevated interfacial contact pressure near Location P1. With the conventional sinusoidal variation of Width W, this zone has a generally circumferential orientation for a significant distance.
[0030] The lubricant film thickness is uneven across the Width W of the dynamic interface, and surface asperity contact sometimes occurs. For example, a portion of the footprint that is circumferentially aligned with Width W1 suffers film disruption due to the aforementioned circumferential contact pressure zone orientation, the sheer magnitude of contact pressure near Location Pi, and due to unfavorable contact pressure gradients.
100311 FIGURE 5 of U.S. Pat. 4,610,319 shows a wave pattern that addresses the aforementioned generally circumferential contact= pressure zone orientation, but it does not address the zone of elevated contact pressure near Location P1. If the teachings of FIG. 5 of the '319 patent are followed, the waves will have undesirable facets at the widest and narrowest parts of the dynamic lip.

[0032] FIGURES 2A, 2B, 2C, 2F and 9 of U.S. Pat. 6,109,618 teach the use of a similar wave for uni-directional rotation. These figures fail to address lubricating problems in the vicinity of Location P1. The narrowest part of the dynamic lip is dominated by an abrupt restrictive diverter 250. In FIGS. 2A and 2E of the '618 patent, the abrupt restrictive diverter 250 is in the form of a corner/facet between dynamic sealing surface 226 and wavy lubricant-side 230 of circular dynamic sealing lip 224, and in FIG. 9 the abrupt restrictive diverter 250 is in the form of a sharp projection. The abrupt restrictive diverter 250 causes contact pressure to skyrocket at the narrowest parts of the dynamic lip, making problems worse. The salient issues were clearly missed because the contact pressure zone 262 in FIG. 2F does not extend to Location 131, and the illustrated edge of the zone is circumferentially oriented at the narrowest points of the footprint. The footprint edge radii at the narrowest parts of the footprint are large--indicating that any corresponding seal fillets are much larger than needed to eliminate the surface facets inherent to FIG. 5 of U.S. Pat. 4,610,319.
[0033] It is desirable for a seal to be suitable for bi-directional rotation, and to address the prior art problems associated with the zone of elevated contact pressure near Location P1, particularly if the circumferential orientation of the zone could be minimized and its film thickness could be increased.
[0034] U.S. Patents 6,109,618 and 6,685,194 teach different ways of implementing a variable inlet curvature on the leading edge of a uni-directional hydrodynamic wave.
Both patents teach the use of a curvature that is most abrupt at the narrowest parts of the dynamic lip (for example, see FIGS. 2 to 2E of the '618 patent, and FIGS. 4 to 4C, 5A, 7, 8, 8A, 9 and 9A of the '194 patent). Because the inlet is more abrupt at the narrowest parts of the dynamic lip, it exacerbates contact pressure issues near Location Pi.
100351 Highly saturated nitrile ("HSN") seals made and employed in accordance with U.S. Pat.
6,315,302 suffer from under-lubrication at higher temperatures that are within the generally understood operating temperature limits of the elastomer (the 250 F
temperature stated in the '302 patent at col. 11, line 65 through col. 12, line 2 is well within the generally understood operating limits of the elastomer). With tetrafluoroethylene and propylene copolymer-flurocarbon rubber ("TFE/P-FKM") composite seals made in accordance with U.S.
Pat. Appl.
Pub. 2006/0214379, lubrication also suffers at high temperatures that are within the generally understood operating temperature limits of the elastomer compounds. This problem is exacerbated when such seals are used with the recommended aforementioned spring-loading.
100361 It has now been discovered that in both of the aforementioned cases, the lubrication problem occurs because the value of EwH approaches zero or becomes negative¨a circumstance not contemplated under the conventional wisdom because EwH and its import were unknown. As seal temperature increases, lubrication decreases as the value of EwH
decreases. As lubrication decreases, the seal generates more and more heat due to increasing asperity friction, causing a loss of lubricant film viscosity. These factors further increase seal temperature, compounding the problem and leading to an unsustainable runaway operating condition.

[0037] These issues are a result of design decisions made on the basis of the conventional wisdom pertaining to footprint wave height and VN. Lubrication breaks down even though, under the conventional wisdom, the remaining footprint wave height is quite satisfactory.
10038] Elastomers have a high coefficient of thermal expansion. Because there is more material at the widest parts of the dynamic lip, part of the differential thermal expansion between the seal and the housing is relieved circumferentially, causing material displacement from the widest to the narrowest parts of the dynamic lip, thereby increasing Width W1 relative to Dimension B2.
[0039] Even if the circumferential transfer of thermally expanded material had been understood, it would not have raised alarm unless the footprint wave height (Width W2 -Width W1) was significantly compromised, because moderate footprint wave height loss would not violate the conventional wisdom concerning the theory of operation. As part of the present invention resulting from considerable study, applicant now understands that lubrication can be seriously impaired even though significant footprint wave height remains, due to the differential growth of Width W1 relative to Dimension B2.
[0040] As used herein, the term "un-swept zone" refers to that portion of the footprint that is circumferentially aligned with Width W1, and the term "swept zone" refers to all the other area of the footprint. In other words the swept zone is that portion of the footprint that is circumferentially aligned with the footprint wave height. The swept zone is directly lubricated by the sweep of the First Footprint Edge L across the lubricant-wetted shaft.
[0041] When the pressure of the environment is greater than that of the lubricant, such as during down-hole swab events, the first footprint edge Li is displaced toward the lubricant more than Location P2, owing to significant variations in the stiffness of the prior art dynamic lip. This impairs lubrication due to an effect that parallels the situation when the value of EwH
approaches or equals zero, or becomes negative.
[0042] Although the "gentle" seal to shaft convergence taught by U.S. Patents 6,315,302, 6,382,634 and 6,685,194 is very effective in terms of hydrodynamic in-pumping, and in terms of reducing interfacial contact pressure near Location P1, such designs significantly increase Dimension A2 at the expense of Dimension B2. According to the conventional wisdom, this approach is unequivocally beneficial. With such seals, the value of EwH
approaches or equals zero, or becomes negative, especially in severe operating conditions.
[0043] FIGURE 13 of U.S. Pat. 6,109,618 shows how pervasive the conventional wisdom concerning a gentle inlet convergence has been. A seal intended for bi-directional rotation is shown where the inlet geometry produces extremely effective in-pumping by virtue of gentle convergence with the shaft, but unfortunately another gentle convergence allows the lubricant film to escape at the trailing edge of the wave. FIGURE 13 also demonstrates a lack of understanding of the problems that circumferentially-oriented contact zones cause. As shown by the dashed line representation of the tangency location, the seal of FIG.
13 has circumferentially-oriented zones of contact pressure that extend over most of the circumference of the seal. Furthermore, the contact pressure within these zones is relatively high because of the abrupt nature of the lip flank curvature, as shown in the section views of FIGS. 13A and 13B.

[0044] FIGURES 2 and 3 of U.S. Pat. 6,315,302 and the related discussion in lines 50-59 of col.
18 thereof, and FIGS. 3 and 4 of U.S. Pat. 6,382,634 and the related discussion in lines 27-33 of col. 14 and col. 14, line 43 through col. 15, line 18 thereof, and col. 2, lines 49-56, col. 4, lines 51-61, col. 6, lines 31-35 and col. 11, lines 33-39 of U.S. Pat. 6,685,194 also demonstrate how pervasive the conventional wisdom has been, in relation to achieving a gentle inlet convergence that was believed, in conjunction with VN, to create an ideal situation for lubricating the interfacial contact footprint. Such geometries were eventually found to suffer from under-lubrication in severe service conditions. After years of research, the cause has recently been determined to be the result of the value of Ewn approaching or equaling zero, or becoming negative.
[0045] U.S. Pat. 6,685,194 exemplifies the blind adherence to conventional wisdom, to the exclusion of the then-unknown importance of the numeric value of EwH. For example, in the variable radius examples of FIGS. 4, 4A and 4B, Location P2 would coincide with the circular exclusion edge, so the size of Dimension B2 is zero. Even though the footprints of these seals have generous footprint wave height, as signified by the dashed lines, the value of EwH is always less than zero, even at room temperature. Such seals only lubricate in low differential pressure conditions. The lubrication is due to secondary factors such as side leakage from the swept zone (related to the fact that film thickness tends to decay gradually, rather than abruptly, due to the relative stiffness of the seal material; see Abstract, U.S. Pat.
6,109,618), and such as macro-lubrication from surface finish affects.
[0046] It is a significant undesirable characteristic of the prior art bi-directional rotation seals that lubrication of the un-swept zone is impaired in severe operating conditions. In some of the prior art, the value of EwH is always less than zero, even at room temperature. Even in the best of the prior art, EwH is undesirably small at room temperature, and becomes compromised in severe operating conditions that include skew-resisting confinement.
100471 In the prior art, each molded wave is substantially identical, which means that all instances of Dimension B1 are substantially identical. This means that each of the film disturbances at and/or near any Location Pi lies in the poorly lubricated wake of a similar disturbance from the preceding wave. This compounds the problem by extending the disturbance circumferentially. The various aforementioned factors cooperate to thin the film in the un-swept zone. The resulting seal-generated heat exacerbates the aforementioned increase in the size of Width WI.
100481 U.S. Pat. 6,315,302 entitled "Skew Resisting Hydrodynamic Seal,"
teaches conservation of void volume to accommodate skew-resisting confinement. From a void volume conservation standpoint, it is desirable to avoid the condition shown in FIGS. 2A and 6 of U.S. Pat. 6,382,634 and FIG. 11 of U.S. Pat. 5,230,520, where the lubricant side flank is truncated by the lubricant end of the seal at the widest part of the dynamic lip, leaving very little void volume near that location. Likewise, it is desirable to avoid the condition shown in FIGS. 4-4C
of U.S. Pat.
6,315,302, where the lubricant side flank of the dynamic lip extends to the lubricant end of the seal. These examples are not only undesirable from an interfacial contact standpoint when the seal is installed in skew-resisting confinement, but it also negatively impacts mold design.
[0049] In the prior art radial seals, the initial compression also causes circumferential compression, which is increased by thermal expansion. Since the seal circumference is relatively long compared to the seal cross-section, circumferential compression can cause buckling in a manner similar to the classic textbook example of a long, slender structural column under compressive loading. This buckling tendency is augmented by the variable stiffness of the prior art seal about its circumference that is caused by the varying dynamic lip width.
10050] This buckling tendency is significantly worse in high temperature seals, such as those manufactured in accordance with FIG. 2 of U.S. Pat. Appl. Pub. US2006/0214379, because of the great amount of circumferential compression caused by seal thermal expansion at high temperature. Consequently, more spring loading is needed to prevent such buckling, and this spring loading further decreases the value of Ewm by increasing Width W1, to the detriment of lubrication.
2. Description of the seal of FIGS. 2-2E.
[0051] FIGURES 2-2E represent a preferred embodiment of the present invention.
These figures should be studied together to best understand the preferred embodiment. Features throughout this specification that are represented by like numbers have the same function.
[0052] FIGURE 2 is a fragmentary cross-sectional view that provides a general overview of how a preferred embodiment of the present invention may be employed when assembled into a machine that is shown generally at 2. The machine 2 includes a first machine component 4 and a second machine component 6 that defines a relatively rotatable surface 8.
The first machine component 4 and the second machine component 6 together typically define at least a portion of a chamber for locating a first fluid 12.

100531 A rotary seal, shown generally at 10, establishes sealing engagement with the relatively rotatable surface 8, to retain the first fluid 12, to partition the first fluid 12 from a second fluid 14, and typically to exclude the second fluid 14. For the purposes of this specification, the term "fluid" has its broadest meaning, encompassing both liquids and gases. The first fluid 12 is preferably a liquid-type lubricant such as a synthetic or natural oil, although other fluids are also suitable in some applications. The second fluid 14 may be any type of environment that the rotary seal 10 may be exposed to in service, such as any type of liquid or gaseous environment including, but not limited to, a lubricating media, a process media, a drilling fluid, an atmosphere, seawater, a partial vacuum, etc.
10054] The rotary seal 10 is of generally circular, ring-like configuration and includes at least one dynamic lip 16 that is also generally circular in form, and is disposed in facing relation to the relatively rotatable surface 8. In the cross-sectional views herein, the cutting plane of the cross-section is aligned with and passes through the theoretical axis/centerline of the rotary seal 10; i.e., the theoretical axis lies on the cutting plane.
[0055] When exclusion of the second fluid 14 is desired, the dynamic lip 16 preferably incorporates a dynamic exclusionary intersection 44 (sometimes called the "exclusion edge") of abrupt substantially circular form that is substantially aligned with the direction of relative rotation, and is adapted to exclude the second fluid 14, as taught by U.S.
Pat. 4,610,319.
Although truly perfect circularity is desirable, it is seldom, if ever, obtainable in any feature of any manufactured product in actual practice, hence the terminology "substantially circular form." The dynamic exclusionary intersection 44 develops substantially no hydrodynamic wedging activity during relative rotation, and presents a scraping edge to exclude the second fluid 14 in the event of relative motion that is perpendicular to the direction of relative rotation.

[0056] It is intended that the rotary seals of the present invention may incorporate one or more seal materials or components without departing from the spirit or scope of the invention, and may be composed of any suitable sealing material or materials, including plastics and elastomeric or rubber-like materials including, but not limited to, carbon, fiber or fabric reinforced elastomers. If desired, the rotary seals may be of monolithic integral, one piece construction as shown in FIGS. 9, 9A and 10, or may also incorporate different materials bonded, inter-fitted, co-vulcanized or otherwise joined together to form a composite structure, such as shown in U.S. Patents 5,738,358, 6,315,302, 6,685,194, 6,767,016 and U.S. Pat. Appl.
Publications 2006/0214379 and 2006/0214380. Preferably, at least part of the seal is constructed of a resilient material, such as an elastomer.
[0057] Elastomers used in seal construction are compounds that include base elastomers such as, but not limited to, HNBR (hydrogenated nitrile, also known as HSN), FKM
(fluorocarbon rubber), TFE/P (also known as FEPM) and EPDM. The elastomers may include other compounding ingredients such as, but not limited to, fillers, lubricants, processing aids, anti-degradants, vulcanizing agents, accelerators and activators. The effects of the ingredients are generally understood by individuals having ordinary skill in the art of compounding elastomers.
[0058] It is further understood that the invention can, if desired, incorporate an energizer to load the dynamic lip 16 against the relatively rotatable surface 8. The energizer can take any of a number of suitable forms known in the art including, but not limited to, elastomeric rings and various forms of springs such as garter springs, canted coil springs, and cantilever springs, without departing from the scope of the invention. If desired, the energizer can be located by or within an annular recess of any suitable form. For examples of such energizers and recesses, see U.S. Patents 6,685,194 and 7,052,020, and U.S. Pat. App!.
Publications 2006/0214380 and 2007/0013143.
[0059] FIGURES 2, 2B, 2C, 2D, 4B and 11 portray seal cross-sections having the high temperature, composite construction taught in U.S. Pat. App!. Pub.
2006/0214379, where preferably a first material layer 48 of TFE/P is co-vulcanized to a second material layer 49 of FKM.
[0060] In FIG. 2, the rotary seal 10 is oriented (i.e., positioned) at least in part by the first machine component 4. For the purpose of illustrating a typical application, the machine 2 has a generally circular seal groove that includes a first groove wall 18 and a second groove wall 20 that are in generally opposed relation to one another, and a peripheral groove wall 22. The first groove wall 18 and the second groove wall 20 are often referred to as the "lubricant-side gland wall," and the "environment-side gland wall," respectively. The peripheral groove wall 22 can be substantially parallel to the relatively rotatable surface 8 as shown, or all or part of it could be skewed with respect to the relatively rotatable surface 8 as shown, for example, by the prior art of FIGS. 4, 6, 7, 8 or 9 of U.S. Pat. 5,230,520.
[0061] For the purpose of establishing consistent nomenclature herein, the seal "groove" is the annular void that is defined by the first groove wall 18, the peripheral groove wall 22, and the second groove wall 20, and the seal "gland" is the generally enclosed annular cavity having a boundary that is defined by the groove and the relatively rotatable surface 8.
[0062) The peripheral groove wall 22 is located in spaced relation to the relatively rotatable surface 8, and it (or an energizer) compresses at least a portion of the dynamic lip 16 against the relatively rotatable surface 8. This compression establishes an interfacial contact footprint, shown generally at 38, between the dynamic lip 16 and the relatively rotatable surface 8. The footprint 38 has a first footprint edge located generally at L and facing the first fluid 12, and has a second footprint edge located generally at E and facing the second fluid 14.
The second footprint edge E is established by compression of the dynamic exclusionary intersection 44 against relatively rotatable surface 8.
[0063] The compression causes contact pressure at the interface (footprint 38) between the dynamic lip 16 and the relatively rotatable surface 8. Sealing is also established at the interface between a static sealing surface 46 of rotary seal 10 and the peripheral groove wall 22. The contact pressure at the footprint 38 establishes sealing in the same manner as any conventional resilient seal, such as an 0-ring or a seal having a lip that is loaded by an energizer. The interfacial contact pressure is related to the degree of compression, the modulus of elasticity of the seal material, and the shape of the rotary seal 10.
[0064] As taught by U.S. Pat. 4,610,319, the first footprint edge L is preferably wavy. Each wave of the footprint 38 has a leading edge and a trailing edge, relative to the direction of relative rotation. When the direction of relative rotation reverses, the application of the leading edge/trailing edge appellations also reverses.
[00651 The leading edges of the waves are sites of hydrodynamic wedging action during relative rotation between the dynamic lip 16 and the relatively rotatable surface 8. This hydrodynamic wedging action forces a film of lubricating fluid (i.e., a film of the first fluid 12) into the interfacial contact footprint 38 for lubrication purposes. In other words, the dynamic lip 16 slips or hydroplanes on a film of the first fluid 12 during periods of relative rotation. The hydroplaning activity reduces wear and seal-generated heat, and causes a minute flow of the first fluid 12 past the second footprint edge E and into the second fluid 14.
When relative rotation stops, the hydroplaning activity stops, and a static sealing relationship is re-established.
[0066] As taught by U.S. Pat. 4,610,319, the second footprint edge E
(sometimes called the "environment edge") is preferably substantially circular and substantially aligned with the possible directions of relative rotation between the dynamic lip 16 and the relatively rotatable surface 8, and does not produce a hydrodynamic wedging action in response to relative rotation between the dynamic lip 16 and the relatively rotatable surface 8.
[0067] Referring to FIG. 2, the rotary seal 10 is preferably held in skew-resisting confinement by virtue of simultaneously contacting the first groove wall 18 and the second groove wall 20.
The first groove wall 18 is shown in FIG. 2 as a face of a spring-loaded seal loading ring 24 of the general type taught by FIG. 3-28 of the Kalsi Seals Handbook, Rev. 1. The first groove wall 18 is loaded against the rotary seal 10 by a spring 28 that acts on the seal loading ring 24. The spring load is reacted to a retainer 30 of any suitable form. The spring-loading arrangement can take any of a number of suitable forms without departing from the scope of the invention. For example, a disk or coil spring arrangement could be substituted for the wave spring arrangement. For examples of coil spring-loaded seal loading rings, see U.S. Pat.
1,089,789, FIGS. 1 and 5, and U.S. Pat. 3,015,505. The typical spring loading ranges from about 15 pounds per square inch ("psi") "equivalent pressure" at room temperature, to about 45 psi at 400 F. The "equivalent pressure" is calculated by dividing the spring force by the circular area of the gland.
[0068] Although the first groove wall 18 and the second groove wall 20 are shown to be in movable relation to one another in FIG. 2, such is not intended to limit the scope of the invention, for the invention admits to other equally suitable arrangements.
For example, as shown in FIGS. 9 and 11, the first groove wall 18 and the second groove wall 20 could be fixed in position relative to each other. Although the rotary seal 10 is shown as having a contacting relationship with the first groove wall 18 and the second groove wall 20 in FIGS. 2 and 9, the features of the present invention are also advantageous for applications where the rotary seal 10 only contacts one groove wall at a time, as represented by FIG. 11.
[0069] As shown in FIG. 2, the rotary seal 10 preferably defines a first seal end 34 that generally faces the first groove wall 18 and first fluid 12, and preferably also defines a second seal end 36 that generally faces the second groove wall 20 and the second fluid 14. The first seal end 34 and the second seal end 36 are often referred to as the "lubricant end" and the "environment end," respectively, and are preferably in generally opposed relation. The first seal end 34 and second seal end 36 can take other forms without departing from the scope of the invention. For example, the first seal end 34 could be angulated as taught in U.S. Pat.
6,315,302 at col. 14, lines 22-22, or could be wavy as taught in U.S. Pat.
Appl. Pub.
2007/0205563. For another example, the second seal end 36 could include a recess for incorporating an energizer, as is well-known in the art.
[0070] The preferred embodiment of the present invention has application where the first machine component 4, the second machine component 6, or both, are individually rotatable. In the cross-sectional assembly views herein, the direction of relative rotation is normal (perpendicular) to the plane of the cross-section, and approximately concentric to the dynamic exclusionary intersection 44. The theoretical axis of the rotary seal 10 generally coincides with the axis of relative rotation.

[0071] In dynamic operation, the relatively rotatable surface 8 has relative rotation with respect to dynamic lip 16 and first machine component 4. The relatively rotatable surface 8 slips with respect to dynamic lip 16, causing the interfacial contact footprint 38 to become a dynamic sealing interface. In the absence of relative rotation, the interfacial contact footprint 38 is a static sealing interface. The rotary seal 10 preferably remains stationary relative to the first machine component 4, however, the prior art teaches that hydrodynamic seal embodiments are possible where relative rotation with the first machine component 4 is allowable; for example, see FIGS. 8 and 8A of U.S. Pat. 6,685,194.
[0072] In FIG. 2, the rotary seal 10 is shown located in a position that would occur if the pressure of the first fluid 12 were greater than or equal to the pressure of the second fluid 14. In such conditions, the force of the spring 28, and any differential pressure that may be present, forces the rotary seal 10 against the second groove wall 20. Owing to the complimentary shapes of the second seal end 36 and the second groove wall 20, the rotary seal 10 is well supported at all locations except the small clearance gap 52 (often called the "extrusion gap") that exists between the first machine component 4 and the relatively rotatable surface 8.
[0073] The relatively rotatable surface 8 can take the form of an externally-or internally-oriented substantially cylindrical surface, as desired, with the rotary seal 10 compressed radially between the peripheral groove wall 22 and the relatively rotatable surface 8, in which case the axis of relative rotation would be substantially parallel to relatively rotatable surface 8. In a radial sealing configuration, the dynamic lip 16 is oriented for compression in a substantially radial direction, and the peripheral groove wall 22 may be of substantially cylindrical configuration, and first groove wall 18, second groove wall 20, first seal end 34 and second seal end 36 may, if desired, be of substantially planar configuration. In a radial sealing configuration, the dynamic lip 16 is located either on the inner or the outer periphery of the seal, depending on whether the relatively rotatable surface 8 is an external or internal cylindrical surface.
[0074] Alternatively, the relatively rotatable surface 8 can take the form of a substantially planar surface, with the rotary seal 10 compressed axially between the peripheral groove wall 22 and the relatively rotatable surface 8 in a "face-sealing" arrangement, in which case the axis or relative rotation would be substantially perpendicular to the relatively rotatable surface 8. In an axial (face) sealing configuration, the dynamic lip 16 would be oriented for compression in a substantially axial direction, the peripheral groove wall 22 may be of substantially planar configuration, and the first groove wall 18, second groove wall 20, first seal end 34 and second seal end 36 may, if desired, be of substantially cylindrical configuration. In such face-sealing arrangements, the hydrodynamic features can be oriented to pump in a radially outward direction if the first fluid 12 is located inward of the dynamic lip 16, or can be oriented to pump in a radially inward direction if the first fluid 12 is located outward of the dynamic lip 16. In a face-sealing arrangement, the backup ring 24 is preferably segmented or split.
If split, the ring itself can, if desired, provide the spring force.
[0075) Large diameter seals are torsionally weak or limp, and therefore, the cross-section of large diameter seals can be rotated so that the dynamic lip 16 can face a relatively rotatable surface 8 of substantially planar or substantially cylindrical form, or even a sloped form. The torsional stiffness of small diameter seals is much higher, and therefore, small diameter seals with a dynamic lip 16 should be manufactured in the desired orientation as dictated by the configuration of the relatively rotatable surface 8 in a given sealing application.

[0076] FIGURE 2A is a fragmentary view of the rotary seal 10 in the uncompressed condition.
To minimize curvature-related foreshortening in the illustrations, for ease of understanding, FIGS. 2A, 3, 4, 5, 6, 7 and 8 are portrayals of seals that are relatively large or infinite in diameter, or as a smaller seal would appear if a short portion thereof is forced straight. The hydrodynamic geometries that are shown herein are bi-directional; that is to say they achieve efficient hydrodynamic lubrication in response to either clockwise or counter-clockwise relative rotation. In other words, the rotary seal 10 is suitable for bi-directional rotation.
[0077] FIGURES 2B-2D are section views representative of cutting planes 2B-2B, 2C-2C and 2D-2D, respectively, and represent the uncompressed cross-sectional shape of the rotary seal 10 of the preferred embodiment. These cutting planes are used on FIGS. 2A, 3, 4, 5, 6, 7 and 8.
FIGURES 2B, 2D and 4B are section views that are representative of the narrower portions of the dynamic lip 16, and FIG. 2C is representative of the wider portions of the dynamic lip 16.
[0078] Referring now to FIGS. 2B-2D, various previously defined portions of rotary seal 10 are labeled for orientation purposes, such as the dynamic lip 16, first seal end 34, second seal end 36, dynamic exclusionary intersection 44, static sealing surface 46, first material layer 48, and second material layer 49.
[0079] The static sealing surface 46 may, if desired, be defined by a projecting static lip 54 to provide a degree of twist-inhibiting compressive symmetry, as taught by U.S.
Pat. 5,230,520.
This arrangement provides a recessed surface 55 that, by being recessed, helps to minimize the volume of rotary seal 10, and thereby helps to maximize void volume within the gland. The projecting static lip 54 is preferably oriented in generally opposed relation to the dynamic lip 16. If desired, the embodiments illustrated herein can be simplified by eliminating the projecting static lip 54, such that the static sealing surface 46 is defined by the seal body, as taught by U.S. Pat. 4,610,319.
[0080] The dynamic lip 16 defines a dynamic surface 56 and a lubricant side flank 58 that are blended by an inlet curvature 60. The dynamic surface 56 and the recessed surface 55 need not be parallel. The lubricant side flank 58 is located in spaced relation with respect to the dynamic exclusionary intersection 44 and the second seal end 36. The inlet curvature 60 can be any suitable curved shape, such as, but not limited to, a radius, a portion of an ellipse, a portion of a sine wave curve, a portion of a parabolic curve, a portion of a cycloid curve, a portion of witch/versiera curves, or combinations thereof. If desired, the static sealing surface 46 and/or the dynamic surface 56 can be of tapered configuration as taught by U.S. Pat.
6,767,016.
[0081] If extended, the dynamic surface 56 and the lubricant side flank 58 would intersect at a theoretical intersection 62 that is positioned from the dynamic exclusionary intersection 44 by a distance that varies along the circumference of the rotary seal. In other words, the theoretical intersection 62 is non-circular and wavy. The lubricant side flank 58 is also non-circular and wavy. In keeping with American drafting third angle projection conventional representation, the theoretical intersection 62 is represented by an object line in FIGS. 2A, 3, 4, 5, 6, 7 and 8, even though blended by the inlet curvature 60. For a discussion of this blended intersection illustration convention, see paragraph 7.36 and FIG. 7.44(b) on page 213 of the classic drafting textbook "Technical Drawing," 10th edition (Prentice-Hall, Upper Saddle River, N.J.: 1997).
[0082] The extent of the inlet curvature 60 is represented by a first extent line 64 and a second extent line 66 in FIGS. 2A, 3, 4, 5, 6, 7 and 8. Preferably, a substantial tangency exists between the inlet curvature 60 and the lubricant side flank 58 at the first extent line 64, and between the inlet curvature 60 and the dynamic surface 56 at the second extent line 66.
Note that preferably the first extent line 64 and the second extent line 66 are skewed with respect to the possible directions of relative rotation; in other words, they are non-circular and wavy. Also note that preferably second extent line 66 reverses direction at a First Reversing Location R1 and at a Second Reversing Location R2, and that these locations are preferably staggered by Offset Dimension T. Another way to say this is that some of the blending curves 84 are offset with respect to other of the blending curves 84 by Offset Dimension T. The Offset Dimension T and the local cross-sectional geometry of the inlet curvature 60 in FIGS. 2A, 4, 5, 7 and 8 govern the size of the Offset Dimension X that is shown in FIGS. 2E, 4A, 5A, 7A, and 8A, respectively.
[0083] FIGURE 2E illustrates a fragmentary portion of the footprint (shown generally at 38) of the rotary seal 10 that is portrayed in FIGS. 2-2D. FIGURES 4A, 5A, 7A and 8A
illustrate a fragmentary portion of the footprint 38 of the rotary seal 10 that is portrayed in FIGS. 4, 5, 7 and 8, respectively. FIGURES 2E, 4A, 5A, 7A and 8A use the same nomenclature as FIG. 1, however the subscript "1" has, when necessary, been modified by the addition of an "a" or "b"
to designate specific locations of the footprint 38.
[0084] Referring now to FIGS. 2A through 2E, the dynamic lip 16 has wider lip locations 80 at cutting plane 2C-2C and narrower lip locations 82 at cutting planes 2B-2B and 2D-2D. The inlet curvature 60 preferably varies in curvature about the circumference of the rotary seal 10.
At or near the wider lip locations 80, the inlet curvature 60 is preferably a tighter curve, compared to the curve at the narrower lip locations 82. For example, if the inlet curvature 60 is a variable radius, the radius might be smallest in size at and/or near cutting planes 2C-2C (i.e., at and/or near the wider lip locations 80), medium in size at and/or near cutting planes 2B-28, and largest in size at and/or near cutting plane 2D-2D (i.e., at the narrower lip locations 82).
For another example, the inlet curvature 60 might be a portion of an ellipse, wherein the major axis varies from being smallest at and/or near the wider lip locations 80 (i.e., at and/or near cutting plane 2C-2C), to being largest at and/or near some of the narrower lip locations 82 (such as cutting plane 2D-2D) while varying to a medium size at and/or near other of the narrower lip locations 82 (such as at cutting planes 2B-2B). If desired, the minor and major axes can be identical to each other at and/or near the wider lip locations 80. It is preferred that the inlet curvature 60 variation be sinusoidal. Making the inlet curvature 60 smaller at and/or near the wider lip locations 80, as taught herein, does very little to increase the lubricant shear area of the footprint 38, but significantly impacts the size of Dimension B2.
[0085] Referring now to FIG. 2E, the local cross-sectional geometry of the inlet curvature 60 (shown in FIGS. 2A-2D) governs Dimension A2 of the footprint 38, and therefore directly influences the size of Dimension B2. For example, if the inlet curvature 60 is a radius, a larger radius would produce a larger Dimension A2 and a smaller Dimension B2. This is why the large inlet radii on seals constructed in accordance with U.S. Patents 6,315,302 and 6,382,634 do not perform as well as desired. The herein-disclosed understanding of the critical relevance of Dimension A2 and Dimension B2 is quite contrary to the conventional wisdom that such prior art seals are based on, and as such represents an inventive step.
[0086] Referring to FIG. 2A, the theoretical intersection 62 is preferably a zig-zag shape modified by small blending curves 68 at the narrower lip locations 82, and by blending curves 69 at the wider lip locations 80, so that the inlet curvature 60 and the lubricant side flank 58 are un-faceted.
3]

[0087] The first extent line 64 and the second extent line 66 preferably have zig-zag shapes that are generally similar to that of the theoretical intersection 62. The zig-zag shapes of the first extent line 64 and the second extent line 66 are preferably blended by curves at the wider lip locations 80 and at the narrower lip locations 82. Of particular importance, the second extent line 66 is blended by blending curves 84 at the narrower lip locations 82, and by blending curves 86 at the wider lip locations 80. An example of an appropriate curvature basic dimension for the blending curves 68, blending curves 69, blending curves 84 and blending curves 86 would be a radius in the range of 0.050" to 0.200", and preferably in the range of about 0.100" to 0.150". Another example would be that these blending curves should have a curvature basic dimension no looser than that of a 0.200" radius, and preferably no looser than that of a 0.150" radius. For example, a 0.250" radius would be considered to be a looser curvature than a 0.200" radius, and a 0.100" radius would be a tighter curvature than a 0.200"
radius. Throughout this specification, the term "basic dimension" has the same definition as is given by Section 1.3.9 of ASME Y14.5M-1994 "Dimensioning and Tolerancing."
[0088] The lubricant side flank 58 preferably varies in slope about the circumference of rotary seal 10. Referring to FIGS. 2B-2D, the slope of the lubricant side flank 58 is represented by angle a. As can be seen in FIGS. 2B-2D, the slope of the lubricant side flank 58 is preferably steeper at and/or near the wider lip locations 80, and less steep at and/or near the narrower lip locations 82. This slope is represented by angle a for illustrative purposes, however, it must be borne in mind that lubricant side flank 58 can be curved or straight, or a combination of straight and curved portions, when viewed in a cross-section aligned with the theoretical axis of rotary seal 10 (such as the illustrations of FIGS. 2B-2D). For example, instead of being a straight line having a variable angle about the circumference of the dynamic lip 16, the lubricant side flank 58 could be a curve that varies in slope. One possibility is to utilize a curve that varies from a given radius at the narrower lip locations 82, to an infinite radius (e.g., a straight line) at and/or near the wider lip locations 80. When used for the lubricant side flank 58, the difference between a line and a curve is insignificant due to the relatively small size of the lubricant side flank 58. In other words, either shape, or a combination of the two, can be used to achieve the desired result. The core idea is that the slope of the lubricant side flank 58 changes, being steeper near and preferably at the wider lip locations 80, and less steep nearer and preferably at the narrower lip locations 82. This is in contrast to the teaching of U.S.
Pat. 6,685,194; for example, see column 15, lines 27-35 of the '194 patent. It is preferred that the variation in the slope of the lubricant side flank 58 be sinusoidal.
[0089] Referring to FIGS. 2-2E, in severe operating conditions the first footprint edge L of the footprint 38 may be defined by either the lubricant side flank 58 or by the inlet curvature 60.
By having the least slope of the lubricant side flank 58 and the larger size of the inlet curvature 60 near the narrower lip locations 82, a hydrodynamically efficient, gradual convergence exists between the dynamic lip 16 and the relatively rotatable surface 8 in the region that is circumferentially aligned with the EwH dimension, regardless of whether the first footprint edge L happens to be defined by the lubricant side flank 58 or by the inlet curvature 60. Establishing gentle convergence along that portion of the leading edge of the footprint 38 is desirable because it (1) establishes an efficient hydrodynamic wedge at the portion of the leading edge that is circumferentially aligned with the dimension EwH, and (2) near that portion within the footprint 38, it establishes a desirably gradual increase in interface contact pressure in the circumferential direction from the First Footprint Edge L to the ridgeline 74.
Both of these attributes are beneficial to efficient lubrication of both the swept zone and the un-swept zone.

[0090] By making the slope of the lubricant side flank 58 steeper at the wider lip locations 80, the dynamic lip 16 can be wider (for more sacrificial material to accommodate third body wear) and the size difference between Dimension B2 and Width W1 can be maximized, while still fitting within a seal overall width that is compatible with the groove designs and any spring designs present in existing equipment. This enables the seal of the present invention to easily retrofit into existing equipment.
[0091] By making the slope of the lubricant side flank 58 steeper at and/or near the wider lip locations 80, void volume within the gland is conserved, making the rotary seal 10 more compatible with skew-resisting confinement in severe operating conditions. In other words, the varying slope of the lubricant side flank 58 helps minimize the volume of the rotary seal 10 in order to assure sufficient void volume within the gland to accommodate tolerances, seal thermal expansion, seal material displaced by compression, and swelling. This in turn helps to maintain interfacial contact pressure within a range that is compatible with efficient hydrodynamic lubrication, while accommodating a relatively large dynamic surface 56 width at the widest locations of the dynamic lip 16, which ensures that the value of EwH remains positive and effective in severe service conditions.
[0092] As mentioned previously, it is desirable to avoid the condition where the lubricant side flank is truncated by the lubricant end of the seal, or extends to the lubricant end of the seal.
This undesirable seal design characteristic is addressed by the varying slope of the lubricant side flank 58 in the present invention.
[0093] The shallow slope of the lubricant side flank 58 at the narrower lip locations 82 provides those portions with more stiffness and support, compared to the situation that would occur if the steeper slope at the wider lip locations 80 were also used at the narrower lip locations 82. This stiffness allows the narrower lip locations 82 to better resist conditions where the pressure of the second fluid 14 is greater than that of the first fluid 12, such as during down-hole swab events.
The additional stiffness has several benefits. It minimizes displacement of the second footprint edge El relative to Location P2, preserving lubrication. It reduces distortion of the dynamic exclusionary intersection 44, facilitating exclusion of the second fluid 14.
It also makes the rotary seal 10 moderately less susceptible to circumferential compression-induced buckling, twisting and skewing in applications where the rotary seal 10 is not held in skew-resisting confinement.
[0094] Referring now to FIG. 2E, the footprint 38 has widest locations 70 and narrower locations 72. As with the prior art, a zone of increased contact pressure, termed herein as a "lubricant-side pressure ridge" exists near the first footprint edge L. The center of the lubricant-side pressure ridge is schematically illustrated by ridgeline 74. This ridgeline 74 is representative of the location of the peak contact pressure at any specific circumferential position along the lubricant-side pressure ridge. At any circumferential location, the contact pressure varies from a maximum value at ridgeline 74 to zero at first footprint edge L.
[0095] While the contact pressure along the lubricant-side pressure ridge may vary from Location P2 to Location Pi (a) and from Location P2 to Location Pl(b), the variable inlet curvature 60 of the seal causes the contact pressure at Location P (0 and Location P1(b) to be much closer in value to that at Location P2, and significantly less than the contact pressure in the prior art at Location P1 of FIG. 1. By so-lowering the contact pressure, lubrication of the mating surfaces of the rotary seal 10 and the relatively rotatable surface 8 in the vicinity of Location P1(a) and Location Pi(b) is greatly enhanced. Location P1(a) and Location Pi(b) can be thought of as "reversing locations" on ridgeline 74.
[0096] The ridgeline 74 is preferably a generally zig-zag shape as shown, comprising more or less straight lines blended by small joining curves 73 and small joining curves 75. This shape provides the lubricant-side pressure ridge with the advantage, as compared to the prior art, of not being generally circumferential over a significant circumferential distance at and near the narrower locations 72 of the footprint 38. This improved orientation allows better lubrication of the mating surfaces of the rotary seal 10 and the relatively rotatable surface 8 in the vicinity of Location P1(a) and Location Pi(b). The keeping of the generally circumferentially oriented portions of the ridgeline 74 as short as practicable via use of the small joining curves 73, without creating a facet on the inlet curvature 60 or on the lubricant side flank 58 while keeping the interfacial contact pressure relatively low, is novel. An example of an appropriate curvature basic dimension for the joining curves 73 and the joining curves 75 would be a radius in the range of 0.050" to 0.200", and preferably in the range of about 0.100" to 0.150". Other curve shapes are possible, but preferably they would have a curvature basic dimension no looser than that of a 0.200" radius, and preferably no looser than that of a 0.150"
radius.
[0097] Varying the size of the inlet curvature 60 to be larger at and/or near the narrower lip locations 82 is quite unconventional in view of the abrupt restrictive diverter teachings of U.S.
Pat. 6,109,618. The present invention makes portions of the trailing edges of the waves less abrupt, allowing even more lubricant to escape at the wave trailing edges. The effectiveness of this approach was certainly not obvious prior to testing, and the excellent results were contrary to prior engineering judgment. The brilliance of the variable inlet curvature 60, as taught herein, is that (1) It reduces torque and seal generated heat, compared to the prior art, by reducing contact pressure, and facilitating lubrication, at and near the narrower lip locations 82 (i.e., near the Location Pi (a) and Location Pi(b) of the footprint 38 (see FIG. 2E));
(2) Without causing the corresponding reduction in Dimension B2 that was caused by the use of large inlet radii at the narrowest part of the dynamic lip in the prior art, it makes up for the increased lubricant escape at the trailing portions of the waves by assuring that an efficient, gradual convergence exists between the dynamic lip 16 and the relatively rotatable surface 8 in the portion of the first footprint edge L that is circumferentially aligned with the EwH dimension, and by assuring a gradual rate of increase in contact pressure from that portion of the first footprint edge L to ridgeline 74, in the circumferential direction; and (3) The tighter inlet curvature 60 at the wider lip locations 80 maximizes Dimension B2, to assure that the value of EwH remains positive throughout the useful temperature range of the elastomer used to construct the rotary seal 10, even when the rotary seal 10 is used in skew-resisting confinement.
100981 The need to maintain a positive value for EwH in severe operating conditions was by no means obvious to the prominent group of seal experts who have been researching such seals for decades, who have themselves developed the relevant prior art oilfield seals, and who have been working intensely for years to improve the lubrication of the prior art bi-directional rotation seals.

100991 Contrary to conventional wisdom, it is not the previously defined footprint wave height that governs lubrication. What matters in severe operating conditions is that the value of EwH
remains positive, and of sufficient size to assure lubricant migration in severe service conditions. Counter-intuitively, this improved lubrication occurs despite the fact that Dimension Ai (a) and Dimension Ai(b) are relatively large due to the variably sized nature of the inlet curvature 60, thus increasing the extent of the region within the un-swept zone where the film of the first fluid 12 has to cross unfavorable gradients.
[001001 When the present invention is used with skew-resisting constraint, such as shown in FIGS. 2, 9 and 9A, the value of EwH remains positive and effective throughout the useful temperature range of the material used in the construction of rotary seal 10.
In designing a seal according to the preferred embodiment of the present invention, the EwH
dimension is sized such that, unlike the prior art, it remains present (having a positive value rather than a negative value) and functional throughout the useful elevated temperature range of the polymer used in the construction of the rotary seal 10, even if used with skew-resisting constraint. Based on the conventional wisdom, the former ineffective design methodology was to evaluate the footprint wave height in extreme elevated temperature conditions. The current seal design methodology, which is an aspect of the present invention, is to evaluate the EwH dimension in extreme elevated temperature conditions that represent the upper limit of the useful temperature range of the polymer, to verify that the value of EwH remains positive throughout the useful temperature range of the material used in the construction of the seal, and preferably to insure that the value of EwH remains greater than or equal to 0.020". This methodology is best implemented via computer simulations utilizing three dimensional large displacement finite element analysis modeling that incorporates a conservative linear coefficient of thermal expansion assumption of 13 X 10-5 inches per inch per degree F, and takes into account the effects of skew-resisting confinement.
[00101] Downhole drilling equipment is ordinarily cooled by the circulating drilling fluid to a temperature that is lower than the local environment. When circulation and rotation occasionally cease, the temperature of the equipment may reach the temperature of the surrounding geological environment, if allowed to soak long enough without circulation.
Ideally, the useful elevated temperature range used in seal design should be considered to be the temperature that the polymer can withstand for brief periods of time so long as adequate lubrication is present. This "abuse temperature" is greater than the typically quoted long-term temperature capability of a material. For example, hydrogenated nitrile typically is given an extended-term temperature exposure rating of about 300 F, but in a seal constructed of such material and employed in accordance with U.S. Patent 6,315,302, it is highly desirable that the value of EwH remain positive if the seal is temporarily exposed to an "abuse temperature" that is 50 F higher than that, and preferably the value of EwH will remain greater than or equal to 0.020".
[00102] The service rating of TFE/P is typically 450 F, and the service rating of FKM is typically 400 F. When two different temperature-rated materials are used in the same seal, it is the lower service rating that typically governs the seal design. Therefore, a TFE/P-FKM
composite seal would preferably have a service rating of 400 F, and in a spring-loaded seal constructed of that material combination, it would be desirable that the value of EwH remain positive if the seal is temporarily exposed to an "abuse temperature" that is 50 F higher than that, and preferably the value of EwH will remain greater than or equal to 0.020".
[00103] Another way to state this is that the validation temperature used in the computer model of the seal, when validating the seal design for a positive EwH value, should be at least equal to the operating temperature limit of the least temperature-capable elastomer used in the construction of the seal (as that operating temperature limit is generally understood within the elastomer industry), and preferably the validation temperature should be 50 F
greater than the aforesaid operating temperature limit.
[00104] Referring to FIG. 2E, Dimension No and Dimension B1(b) are preferably different in size, so that Location P1(a) and Location P1(b) are misaligned¨i.e., offset¨by Offset Dimension X. This offset is desirable so that the film disturbances created by the direction reversals of the ridgeline 74 at Location No and Location Pi(b) do not lie in one-another's wake. This minimizes the circumferential extent of each such film disturbance and facilitates lubrication. The relative size of Dimension B1 (a) and Dimension B1 (b) is preferably controlled by the local cross-sectional geometry of the inlet curvature 60 of the dynamic lip 16 that is shown in FIGS. 2-2D. In those figures, note that the size of the inlet curvature 60 differs between Section 2B-2B and Section 2D-2D; this causes Dimension Bi (a) and Dimension B 1(b) to differ at the corresponding locations of the footprint 38. The salient point, however, is that Location Pi(a) and Location P1(b) are offset with respect to each other, regardless of how the offset is achieved. Another way of saying this is that at least some of the joining curves 73 are misaligned with respect to others. In FIG. 2E, some of the waves of the ridgeline 74 are different than other of its waves.
[00105] The cooperative benefits of the various features provides more complete lubrication, especially in the un-swept zone, in either direction of rotation.
The invention is suitable for a wider range of service conditions, including faster and slower rotary speeds, higher differential pressures, and thinner lubricants. Running torque is reduced, resulting in less self-generated heat. The result is better tolerance to high ambient environment temperature, less heat-related compression set, less footprint spread, less seal wear, longer polymer life, a higher retained modulus for improved extrusion resistance, lower interfacial contact pressure when installed in skew-resisting confinement, less slippage within the groove, and less tendency to cause floating compensation pistons to rotate.
3. Description of Simplifications and Alternate Embodiments.
[00106] The seal of FIGS. 2-2D includes several desirable features that are most advantageously used together, however simplifications are possible where one or more of the features are omitted or revert to the teachings of the prior art. FIGS. 3, 4, 5, 6, 7 and 8 represent simplifications and alternate embodiments of the invention, and are fragmentary views of a rotary seal 10 in the uncompressed condition thereof, showing a seal that is relatively large or infinite in diameter, or as a smaller seal would appear if a short portion thereof were forced straight, so that no curvature-related foreshortening is apparent. Cutting planes 2B-2B, 2C-2C, 2D-2D, and 4B-4B correspond to the cross-sections shown in FIGS. 2B, 2C, 213, and 4B, respectively.

[00107] To orient the reader, various previously defined features of the rotary seal 10 are labeled in FIGS. 3, 4, 5, 6, 7 and 8, such as the first seal end 34, second seal end 36, theoretical intersection 62, first extent line 64, second extent line 66, dynamic surface 56, lubricant side flank 58, inlet curvature 60, wider lip locations 80, narrower lip locations 82, blending curves 84, blending curves 86, First Reversing Location RI, Second Reversing Location R2 and Offset Dimension T. Additionally, in FIGS. 3, 4 and 8, the previously designated blending curves 68 are labeled to orient the reader.
[00108] The rotary seal 10 of FIG. 3 is a simplification of the preferred embodiment of the present invention that differs from that of FIG. 2A in one respect-each of the narrower lip locations 82 (at cutting planes 2D-2D) is substantially the same, which means that Offset Dimension T equals zero. The inlet curvature 60 varies in curvature about the circumference of the seal, being a tighter curve at cutting plane 2C-2C, and looser at cutting plane 2D-2D.
[00109] The rotary seal 10 of FIGS. 4 and 4B is a simplification of the preferred embodiment of the present invention that differs from that of FIG. 2A in one respect-the inlet curvature 60 does not vary between cutting plane 2C-2C and cutting plane 4B-4B, as taught by the prior art. As a result, First Reversing Location R1 is offset from Second Reversing Location R2 by Offset Dimension T. In FIG. 4B, which is representative of the cutting plane 4B-4B in FIG. 4, various previously defined portions of rotary seal 10 are labeled for orientation purposes, such as angle a, dynamic lip 16, first seal end 34, second seal end 36, dynamic exclusionary intersection 44, static sealing surface 46, first material layer 48, second material layer 49, projecting static lip 54, lubricant side flank 58, inlet curvature 60 and theoretical intersection 62. The inlet curvature 60 in FIG. 4 is the same as in the view of FIG. 2C, while the slope of the lubricant side flank 58 is shown as being the same as in FIG.
2D.
[00110] The rotary seal 10 of FIG. 5 is a simplification of the preferred embodiment of the present invention that differs slightly from that of FIG. 2A in that the theoretical intersection 62 is sinusoidal, as taught by the prior art. The variable size of inlet curvature 60 that is taught in this specification can be used with various wavy shapes, however it is best employed with the modified zig-zag wave shape of FIG. 2A.
[00111] The rotary seal 10 of FIG. 6 is a simplification of the preferred embodiment of the present invention that differs slightly from that of FIG. 3 in that the theoretical intersection 62 is sinusoidal, as taught by the prior art.
[00112] The rotary seal 10 of FIG. 7 is an alternate embodiment of the present invention that differs slightly from that of FIG. 4 in that the theoretical intersection 62 is sinusoidal, as taught by the prior art. In FIGS. 5, 6 and 7, The first extent line 64 and the second extent line 66 have shapes that are similar to that of the theoretical intersection 62.
[00113] The rotary seal 10 of FIG. 8 is an alternate embodiment of the present invention that accomplishes the Offset Dimension T between First Reversing Location R1 and Second Reversing Location R2 by having a different dynamic lip width at the First Reversing Location RI, compared to the lip width at the Second Reversing Location R2. In other words, some of the narrower lip locations 82 have a different width than other of the narrower lip locations 82, and in general, some of the waves of the dynamic lip 16 are different than other of its waves. Also, some of the waves of the second extent line 66 are different than other of its waves. The inlet curvature 60 may, if desired, be the same size throughout, as shown. Note that some of the blending curves 68 of the theoretical intersection 62 are offset with respect to other of the blending curves 68; this means that some of the waves of the theoretical intersection 62 are different than other of its waves.
[00114] FIGURES 3A, 4A, 5A, 6A, 7A and 8A represent the footprint 38 of the simplifications and alternate embodiments that are shown in FIGS. 3, 4, 5, 6, 7 and 8, respectively. To orient the reader, various previously defined portions of the footprint 38 are labeled in FIGS. 3A, 4A, 5A, 6A, 7A and 8A, such as Dimension Ai(a), Dimension Al), Dimension A2, Dimension No, Dimension BIN, Dimension B2, First Footprint Edge L, Second Footprint Edge E, Location No, Location Pi()), Location P2, Offset Dimension X, first fluid 12, second fluid 14, widest locations 70, narrower locations 72, joining curves 73, ridgeline 74 and joining curves 75. The previously defined Width W1 is labeled in FIGS. 3A, 4A, 5A, 6A, and 7A to orient the reader; in FIG. 8A, two different sizes of narrower width location are shown as Width W1(a) and Width Wi(b).
[00115] In FIG. 3A, the peak pressure of ridgeline 74 at the narrowest points of the footprint 38 are circumferentially aligned, unlike those in FIG. 2E. In other words, Dimension No and Dimension BI(b) are similarly sized, so that Location No and Location Pi(b) are substantially aligned. With such a simplification, the initial tooling manufacturing cost is reduced because design effort is reduced.
[00116] The footprint 38 of FIG. 4A differs from that of FIG. 2E in one important respect¨in FIG. 4A the contact pressure is relatively high at and near Location Pi(b) because the inlet curvature 60 in FIG. 4 does not vary between cutting plane 2C-2C and cutting plane 4B-4B. With this alternate embodiment, the peak pressures of the ridgeline 74 at the narrower locations 72 of the footprint 38 are circumferentially misaligned¨i.e., offset¨by Offset Dimension X so that the film disturbances created by the direction reversal of the ridgeline 74 at Location P1(a) and Location Pub) do not lie in one-another's wake. Some of the waves of the ridgeline 74 are different than other of its waves.
[00117] The footprints 38 identified in FIGS. 5A, 6A and 7A differ from those of FIGS.
2E, 3A and 4A, respectively, in that the ridgeline 74 and the First Footprint Edge L are sinusoidal rather than a modified zig-zag. In FIGS. 5A and 7A, some of the waves of the ridgeline 74 are different than other of its waves.
1001181 The graph of FIG. 7B represents interfacial contact pressure at selected circumferential slices of the rotary seal 10 of FIGS. 2A and 7. The slice representative of the rotary seal 10 of FIG. 2A was taken between cutting planes 2C-2C and 2B-2B, and the slice representative of the rotary seal 10 of FIG. 7 was taken between cutting planes 2C-2C and 4B-4B. One circumferential slice is aligned with Location 131(a) of FIG. 2E, and the other circumferential slice is aligned with Location P1(b) of FIG. 7A. Note that the gradient and magnitude of the FIG. 2E contact pressure is preferable to that of FIG. 7A.
This shows the benefit of the wave pattern and the varying size of the inlet curvature 60 of the rotary seal 10 of FIG. 2A, compared to that of FIG. 7.
[00119] The disadvantage of the embodiments of FIGS. 5, 6 and 7, compared to the zig-zag counterparts of FIGS. 2A, 3 and 4, is that significant portions of the ridgeline 74 at the narrower locations 72 of the footprint 38 have a generally circumferential orientation as shown in FIGS. 5A, 6A and 7A, which is disruptive to the lubricating film. All of the seals described herein can be further simplified, if space permits, by having a lubricant side flank 58 with a slope that does not vary about the circumference of rotary seal 10.
[00120] FIGURE 8A is representative of the footprint 38 of the rotary seal 10 that is shown in FIG. 8. The peak pressures of the ridgeline 74 at the narrower locations 72 of the footprint 38 are circumferentially misaligned¨i.e., offset¨by Offset Dimension X so that the film disturbances created by the direction reversal of the ridgeline 74 at Location P1(a) and Location P1 (b) do not lie in one-another's wake. Offset Dimension X is governed by the Offset Dimension T and the local cross-sectional geometry of the inlet curvature 60 that is illustrated in FIG. 8. The un-swept zone is defined by Width WI (a), since it is smaller than Width Wi(b).
Some of the waves of the ridgeline 74 are different than other of its waves, and some of the waves of the First Footprint Edge L are different than other of its waves.
[001211 FIGURE 9 is a fragmentary cross-sectional view that provides a general overview of another preferred embodiment of the present invention. FIGURE 9A shows the rotary seal of FIG. 9 in its uncompressed condition. Many of the previously described features are numbered in FIGS. 9 and 9A to orient the reader.
1001221 Machine 2 incorporates a first machine component 4 and a second machine component 6 that includes a relatively rotatable surface 8. The rotary seal 10 has a generally circular, ring-like configuration and at least one dynamic lip 16 that is also generally circular in form. At least a portion of the dynamic lip 16 is held in compressed, contacting relation with the relatively rotatable surface 8, and establishes sealing engagement with the relatively rotatable surface 8, to retain a first fluid 12, to partition the first fluid 12 from a second fluid 14, and to exclude the second fluid 14. In dynamic operation, the relatively rotatable surface 8 has relative rotation with respect to the dynamic lip 16 and with respect to first machine component 4. The dynamic lip 16 incorporates a dynamic exclusionary intersection 44 of abrupt substantially circular form that is substantially aligned with the direction of relative rotation.
[00123] The rotary seal 10 is oriented by the first machine component 4, which has a generally circular seal groove that includes a first groove wall 18 and a second groove wall 20 that are preferably in generally opposed relation to one another. The first machine component 4 also has a peripheral groove wall 22 that is located in spaced relation to the relatively rotatable surface 8, and compresses the rotary seal 10 against the relatively rotatable surface 8.
[001241 Although first groove wall 18 and second groove wall 20 are shown to be in fixed, permanent relation to one another, such is not intended to limit the scope of the invention, for the invention admits to other equally suitable forms. For example, first groove wall 18 and/or second groove wall 20 could be configured to be detachable from the first machine component 4 for ease of maintenance and repair, but then assembled in more or less fixed location for locating and constraining the rotary seal 10.
[001251 In FIG. 9, the rotary seal 10 is held in skew-resisting confinement by virtue of simultaneously contacting the first groove wall 18 and the second groove wall 20 under operating conditions. In the prior art axially-constrained seals made in accordance with U.S.
Pat. 6,315,302, even though the designers meticulously evaluated the footprint wave height in elevated temperature conditions, the heretofore unknown EwH dimension became compromised in elevated temperature conditions, causing loss of lubrication in the un-swept zone. This and other previously described lubrication problems are managed by incorporating any, or all, of the design features that were previously disclosed in conjunction with FIGS. 2-8.
[00126] Rotary seal 10 defines a first seal end 34 that generally faces the first groove wall 18 and first fluid 12. Rotary seal 10 also defines a second seal end 36 that generally faces the second groove wall 20 and the second fluid 14. The compression of the dynamic lip 16 against the relatively rotatable surface 8 establishes and defines an interfacial contact footprint, shown generally at 38, between the dynamic lip 16 and the relatively rotatable surface 8. The footprint 38 has a first footprint edge located generally at L and facing the first fluid 12, and has a second footprint edge located generally at E and facing the second fluid 14. The second footprint edge E is established by compression of the dynamic exclusionary intersection 44 against the relatively rotatable surface 8. The footprint 38 can take the form of any of the footprints shown in FIGS. 2E, 3A, 4A, 5A, 6A, 7A or 8A, with the same characteristics and benefits. The labels in those figures are therefore appropriate to this discussion of FIGS. 9 and 9A.
[00127] If desired, in the uncompressed condition the first seal end 34 may be wavy and vary in position relative to the second seal end 36, as taught by U.S. Pat.
Appl. Pub.
2007/0205563. This embodiment, and other embodiments, may if desired also incorporate an exclusion edge chamfer in accordance with the teachings of U.S. Pat.
6,120,036.
[00128] The dynamic lip 16 and the footprint 38 can have any or all of the attributes previously described in conjunction with FIGS. 2 to 8A; the following citations of such attributes do not represent an exhaustive list of the previously described attributes. The theoretical intersection 62 can have the previously described modified zig-zag shape, or other desired wave shape. The slope of the lubricant side flank 58 can vary around the circumference of the rotary seal 10, being steepest at the widest portions of the dynamic lip 16 to conserve void volume, and to maximize the body length 76. The slope is represented by angle a, however as described previously, the lubricant side flank 58 can be straight or curved in the cross-sectional view shown (even if straight in the uncompressed condition, the lubricant-side flank 58 tends to become curved in the compressed condition). The varying slope of the lubricant side flank 58 allows the EwH dimension of the footprint 38 to be increased without increasing the volume of the rotary seal 10, compared to the prior art. The varying slope also tends to strengthen the narrowest parts of the dynamic lip 16. This helps the dynamic exclusionary intersection 44 to remain more circular when the pressure of the second fluid 14 is greater than the first fluid 12.
[00129] When installed in skew-resisting confinement as taught by U.S. Pat.
6,315,302 and shown here in FIG. 9, the unsupported length (from first groove wall 18 to first footprint edge L) of the rotary seal 10 acts as a skew-resisting spring. The varying slope of the lubricant side flank 58 serves to maximize the exposed length 76 of the body 78 near the wider parts of the dynamic lip 16, which lowers the effective spring rate of the seal body 78 by minimizing the spring force contribution of the dynamic lip 16.
[00130] While FIG. 13 of U.S. Pat. 6,334,619 also discloses a seal with a variably angled flank, the purpose was not to conserve void volume or to preserve body length 76, since that flank is in intimate contact with a similarly shaped backup ring, which supports and constrains the flank, and the flank extends to the end of the seal body. Here in FIG. 9, the lubricant side flank 58 is part of an "unconstrained geometry" as taught by U.S. Pat.
6,315,302, so that additional compression or thermal expansion of the rotary seal 10 is compensated by displacement by the unconstrained geometry of the lubricant side flank 58; see col. 11, lines 42-46 and col. 12, lines 13-20 of the '302 patent. The seal in FIG. 13 of U.S.
Pat. 6,334,619 is not constrained in a manner that requires or permits the flank to serve as an unconstrained geometry to avoid excessive confinement-related and thermal expansion-related contact pressure. Even if it were so-constrained, as shown in the non-varying flank examples of FIGS.
2C, 2E, 6 and 10 of U.S. Pat. 6,334,619, the "unconstrained geometry" function could not be served by the angulated, well-supported lip flank. In the present invention, the lubricant side flank 58 is located remote from the first groove wall 18, establishing void volume within the gland.
[00131] The inlet curvature 60 can vary about the circumference of the rotary seal 10, being a tighter curvature at the wider portions of the dynamic lip 16, and a looser curvature at the narrowest portions of the dynamic lip 16. These features help to assure adequate seal lubrication at higher temperatures despite the higher interfacial contact pressure associated with skew-resisting confinement, as described previously in conjunction with FIGS.
2-2E.
[00132] FIGURE 10 is an enlarged fragmentary shaded perspective view of an uncompressed seal of an embodiment of the present invention in an uncompressed state, as such a seal would be configured for radial compression against a relatively rotatable shaft. This figure is included to facilitate the reader's understanding of the variable slope of the lubricant side flank 58, the variable curvature of the inlet curvature 60, and the generally circular configuration of the dynamic exclusionary intersection 44. The inlet curvature 60 is a radius that is smaller at the widest part of the dynamic lip, and larger at the narrower part of the dynamic lip. The lubricant side flank 58 is a sloped surface that is steeper at the widest part of the dynamic lip, and less steep at the narrower part of the dynamic lip. The wave form is a modified zig-zag shape of the type shown between cutting planes 2C-2C and 2D-2D in FIGS.

2A, 3 and 4. Instead of the dual material construction shown in FIGS. 2B-2D
and 4B, the rotary seal 10 in FIG. 10 is illustrated as being constructed from a single elastomeric material.
[00133) The present invention also provides a lubrication advantage over the prior art when the seal is not constrained by the walls of the groove. FIGURE 11 is a fragmentary cross-sectional view of an installed, ring-shaped hydrodynamic rotary seal 10 embodying the principles of the present invention, and installed in the machine that is shown generally at 2.
The machine 2 includes a first .machine component 4 and a second machine component 6 that defines a relatively rotatable surface 8. FIGURE 11 differs from that of FIG.
2 in that the first groove wall 18 and the second groove wall 20 are both defined by the first machine component 4 and are not both in contact with the rotary seal 10. The arrangement shown in FIG. 11 lacks the backup ring 24, spring 28, and retainer 30 that are provided in FIG. 2.
The peripheral groove wall 22 compresses the dynamic lip 16 of the rotary seal 10 against the relatively rotatable surface 8 of the second machine component 6, establishing a footprint shown generally at 38 that has Width W, a first footprint edge generally at L and a second footprint edge generally at E. The static sealing surface 46 has sealed engagement with the peripheral groove wall 22. The second footprint edge E is established by compression of dynamic exclusionary intersection 44 against the relatively rotatable surface 8.
[001341 The rotary seal 10 is shown in the position it would assume when the pressure of the first fluid 12 is greater than that of the second fluid 14. The second seal end 36 is supported by the second groove wall 20 at all locations except the clearance gap 52. The first seal end 34 is not touching the first groove wall 18. The rotary seal 10 and the footprint 38 can incorporate the features and advantages of the invention that have previously been described, sans the implications of skew-resisting confinement. The rotary seal 10 in FIG. 11 is prevented from skewing and twisting only when the pressure of the first fluid 12 is sufficiently higher than the pressure of the second fluid 14.
4. Conclusion.
[001351 In view of the foregoing it is evident that the present invention is one that is well adapted and believed to attain the aspects and features hereinabove set forth, together with other aspects and features which are inherent in the apparatus disclosed herein and defined by the appended claims.
1001361 Even though several specific hydrodynamic rotary seal and seal gland geometries are disclosed in detail herein, many other geometrical variations employing the basic principles and teachings of this invention are possible.
[00137] The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the scope of the invention defined in the appended claims. The present embodiment is, therefore, to be considered = as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.

Claims (99)

What is claimed is:

1. A rotary seal assembly, comprising:
a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall;
a second machine component located at least partially within said first machine component having a relatively rotatable surface in generally opposed relation to said peripheral groove wall and rotatable relative to said first machine component;
a generally ring-shaped interference-type rotary seal located at least partially within said seal groove and having a volume, said rotary seal comprising a seal body of resilient thermally expandable sealing material, said seal body having axially-facing first and second seal ends;
wherein in an uncompressed condition said seal body including a dynamic lip of generally circular form, said dynamic lip having an abrupt dynamic exclusionary intersection, a dynamic surface facing radially inward, a lubricant side flank that is non-circular having a slope in an axial direction and located in spaced relation with respect to said dynamic exclusionary intersection, a hydrodynamic inlet curvature located between and separating said dynamic surface and said lubricant side flank and located in spaced relation with respect to said dynamic exclusionary intersection and being at least a portion of a wavy, rotationally bi-directional hydrodynamic geometry, said seal body including an inwardly facing surface between said first seal end and at least part of said lubricant side flank, said inwardly facing surface and said lubricant side flank located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, said dynamic surface extending from said inlet curvature to said dynamic exclusionary intersection, and said dynamic surface having at least two wider surface locations, at least one of said wider surface locations being the widest dynamic surface location between two narrower surface locations, at least one of said two narrower surface locations being the narrowest dynamic surface location between said at least two wider surface locations;
said hydrodynamic inlet curvature adjoining said lubricant side flank and said dynamic surface and extending continuously in a circumferential direction from one of said narrower surface locations, past said widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations;
said dynamic lip being held in compression against said relatively rotatable surface and defining a circumferential interfacial contact footprint against said relatively rotatable surface, said interfacial contact footprint comprising peripheral first and second footprint edges, said first footprint edge being generally wavy, a footprint width defined between said first and second footprint edges, said interfacial contact footprint having at least two wider footprint locations, at least one of said wider footprint locations being the widest footprint location between two narrower footprint locations, at least one of said two narrower footprint locations being the narrowest footprint location between said at least two wider footprint locations;
wherein said slope of said lubricant side flank in the uncompressed condition being steepest relative to said dynamic surface at said widest dynamic surface location minimizing said volume, and said compression establishing interfacial contact pressure within said interfacial contact footprint including a lubricant-side pressure ridge along said first footprint edge, said lubricant-side pressure ridge having a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of said interfacial contact footprint, and at said widest footprint location said interfacial contact pressure increasing from zero at said first footprint edge to a greater value at a Position P2 on said ridgeline, said rotary seal maintaining a positive value of E WH, wherein E WH = Dimension B2 - Width W1 where Dimension B2 is an axial length from said second footprint edge to said Position P2 on said ridgeline at said widest footprint location, and Width W1 is said axial footprint width at said narrowest footprint location, and said Dimension B2 is governed at least in part by said inlet curvature at said widest dynamic surface location.

2. The rotary seal assembly of claim 1, wherein said rotary seal is held in skew-resisting confinement by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall.

3. The rotary seal assembly of claim 2, wherein said first and second groove walls are spaced a fixed distance from one another.

4. The rotary seal assembly of claim 2, wherein at least one of said first and second groove walls is a spring-loaded moveable gland wall.

5. The rotary seal assembly of claim 1, wherein:
said sealing material having an operating temperature range having an upper bound established by an upper temperature, and said rotary seal being held in skew-resisting confinement at said upper temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall, and said value of E WH remaining positive at said upper temperature.

6. The rotary seal assembly of claim 5, wherein said rotary seal has a positive value of E WH
of at least 0.020" at said upper temperature.

7. The rotary seal assembly of claim 5, wherein said rotary seal has a positive value of E WH
of at least 0.020" at a temperature 50°F greater than said upper temperature.

8. The rotary seal assembly of claim 1, wherein at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface of said seal body and said inlet curvature.

9. The rotary seal assembly of claim 1, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

10. The rotary seal assembly of claim 1, wherein in said uncompressed condition an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by an extent line blending curve at said narrowest dynamic surface location, said extent line extending in the circumferential direction from one of said narrower surface locations, past said widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations.

11. The rotary seal assembly of claim 1, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

12. The rotary seal assembly of claim 1, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said widest dynamic surface location.

13. The rotary seal assembly of claim 1, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said narrowest dynamic surface location.

14. The rotary seal assembly of claim 1, wherein said lubricant side flank being an unconstrained geometry and being axially spaced from said first groove wall.

15. The rotary seal assembly of claim 1, wherein in said uncompressed condition said dynamic exclusionary intersection being generally circular, and at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

16. The rotary seal assembly of claim 1, wherein said rotary seal is held in skew-resisting confinement at room temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall.

17. A rotary seal assembly, comprising:

a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall;
a second machine component located at least partially within said first machine component having a relatively rotatable surface in generally opposed relation to said peripheral groove wall and rotatable relative to said first machine component;
a generally ring-shaped interference-type rotary seal located at least partially within said seal groove, said rotary seal comprising a seal body of at least one resilient sealing material, said seal body having first and second seal ends;
wherein in an uncompressed condition said seal body including a dynamic lip having a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward, a lubricant side flank having a slope in an axial direction, and a hydrodynamic inlet curvature located between and separating said dynamic surface and said lubricant side flank, said inlet curvature being at least part of a hydrodynamic geometry, said seal body including an inwardly facing surface between said first seal end and at least part of said lubricant side flank and said dynamic lip projecting radially inward of said inwardly facing surface, said lubricant side flank located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, said dynamic surface having an axial width between said dynamic exclusionary intersection and said inlet curvature that in a circumferential direction increases from a first narrower surface location to a first wider surface location, decreases from said first wider surface location to a second narrower surface location, increases from said second narrower surface location to a second wider surface location, and decreases from said second wider surface location to a third narrower surface location, wherein said first wider surface location being situated between said first and second narrower surface locations and being the widest dynamic surface location between said first and second narrower surface locations, being referred to as the first widest dynamic surface location, said second narrower surface location being situated between said first and second wider surface locations and being the narrowest dynamic surface location between said first and second wider surface locations, and said second wider surface location being situated between said second and third narrower surface locations and being the widest dynamic surface location between said second and third narrower surface locations, being referred to as the second widest dynamic surface location, said dynamic lip being held in compression against said relatively rotatable surface and defining a circumferential interfacial contact footprint against said relatively rotatable surface, said interfacial contact footprint comprising peripheral first and second footprint edges, said first footprint edge being generally wavy, said interfacial contact footprint having an axial footprint width between said first and second footprint edges that in the circumferential direction increases from a first narrower footprint location to a first wider footprint location, decreases from said first wider footprint location to a second narrower footprint location, increases from said second narrower footprint location to a second wider footprint location, and decreases from said second wider footprint location to a third narrower footprint location, wherein said first wider footprint location being situated between said first and second narrower footprint locations and being the widest footprint location between said first and second narrower footprint locations, being referred to as the first widest footprint location, said second narrower footprint location being situated between said first and second wider footprint locations and being the narrowest footprint location between said first and second wider footprint locations, said second wider footprint location being situated between said second and third narrower footprint locations and being the widest footprint location between said second and third narrower footprint locations, being referred to as the second widest footprint location, and wherein said compression of said dynamic lip against said relatively rotatable surface establishes interfacial contact pressure within said interfacial contact footprint including a lubricant-side pressure ridge along said first footprint edge, said lubricant-side pressure ridge having a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of said interfacial contact footprint, and at said first widest footprint location said interfacial contact pressure increasing from zero at said first footprint edge to a greater value at a Position P2 on said ridgeline, said rotary seal maintaining a positive value of E WH, wherein E WH = Dimension B2 - Width W1 where Dimension B2 is an axial length from said second footprint edge to said Position P2 at said first widest footprint location, and Width W1 is said axial footprint width at said narrowest footprint location, and said Dimension B2 is governed at least in part by said inlet curvature at said first widest dynamic surface location; and said slope of said lubricant side flank in the uncompressed condition varies from said first widest dynamic surface location to said narrowest dynamic surface location, said slope being steeper relative to said dynamic surface at said first widest dynamic surface location than at said narrowest dynamic surface location, and being steeper relative to said dynamic surface at said first widest footprint location than at said narrowest footprint location, said first widest footprint location corresponding circumferentially to said first widest dynamic surface location, and said narrowest dynamic surface location corresponding circumferentially to said narrowest footprint location.

18. The rotary seal assembly of claim 17, wherein said rotary seal held in skew-resisting confinement by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall.

19. The rotary seal assembly of claim 18, wherein said first and second groove walls are spaced a fixed distance from one another.

20. The rotary seal assembly of claim 18, wherein at least one of said first and second groove walls is a spring-loaded moveable gland wall.

21. The rotary seal assembly of claim 17, wherein:
said sealing material being thermally expandable and having an operating temperature range having an upper bound established by an upper temperature;

said rotary seal being held in skew-resisting confinement at said upper temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall, and said value of E WH remaining positive at said upper temperature.

22. The rotary seal assembly of claim 21, wherein said rotary seal has a positive value of E WH
of at least 0.020" at said upper temperature.

23. The rotary seal assembly of claim 21, wherein said rotary seal has a positive value of E WH
of at least 0.020" at a temperature 50°F greater than said upper temperature.

24. The rotary seal assembly of claim 17, wherein at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface of said seal body and said inlet curvature.

25. The rotary seal assembly of claim 17, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

26. The rotary seal assembly of claim 17, wherein in said uncompressed condition an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by an extent line blending curve at said narrowest surface location, said extent line extending in the circumferential direction from one of said narrower surface locations, past said first widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations.

27. The rotary seal assembly of claim 17, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

28. The rotary seal assembly of claim 17, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said first widest dynamic surface location.

29. The rotary seal assembly of claim 17, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said narrowest dynamic surface location.

30. The rotary seal assembly of claim 17, wherein said lubricant side flank being an unconstrained geometry having no contact with said first groove wall.

31. The rotary seal assembly of claim 17, wherein in said uncompressed condition said dynamic exclusionary intersection being generally circular, and at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

32. The rotary seal assembly of claim 17, wherein said rotary seal is held in skew-resisting confinement at room temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall.

33. A rotary seal assembly, comprising:
a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall;
a second machine component located at least partially within said first machine component having a relatively rotatable surface in generally opposed relation to said peripheral groove wall and rotatable relative to said first machine component;
a generally ring-shaped interference-type rotary seal located at least partially within said seal groove, said rotary seal comprising a seal body of resilient thermally expandable sealing material having an operating temperature range having an upper bound defined by an upper temperature, said seal body having first and second seal ends, wherein in an uncompressed condition said seal body including a dynamic lip of generally circular form, said dynamic lip having an abrupt dynamic exclusionary intersection, a dynamic surface facing radially inward, a lubricant side flank that is non-circular having a slope in an axial direction and located in spaced relation with respect to said dynamic exclusionary intersection and located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, a hydrodynamic inlet curvature located between and separating said dynamic surface and said lubricant side flank and located in spaced relation with respect to said dynamic exclusionary intersection and being at least a portion of a wavy hydrodynamic geometry, said dynamic surface being separated from said lubricant side flank and extending from said inlet curvature to said dynamic exclusionary intersection, said dynamic surface having at least two wider surface locations, at least one of said wider surface locations being the widest dynamic surface location between two narrower surface locations, at least one of said two narrower surface locations being the narrowest dynamic surface location between said at least two wider surface locations;
said inlet curvature being located between and adjoining said lubricant side flank and said dynamic surface and extending from one of said narrower surface locations, past said widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations;
said slope of said lubricant side flank varies from said widest dynamic surface location to said narrowest dynamic surface location, said slope being steeper relative to said dynamic surface at said widest dynamic surface location than at said narrowest dynamic surface location;
said rotary seal held in skew-resisting confinement at said upper temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall;
said dynamic lip being held in compression against said relatively rotatable surface and defining a circumferential interfacial contact footprint against said relatively rotatable surface, said interfacial contact footprint comprising peripheral first and second footprint edges, said first footprint edge being generally wavy, said interfacial contact footprint having an axial footprint width between said first and second footprint edges, said interfacial contact footprint having at least two wider footprint locations, at least one of said wider footprint locations being the widest footprint location between two narrower footprint locations, at least one of said two narrower footprint locations being the narrowest footprint location between said at least two wider footprint locations;
wherein said compression of said dynamic lip against said relatively rotatable surface establishes interfacial contact pressure within said interfacial contact footprint including a lubricant-side pressure ridge along said first footprint edge, said lubricant-side pressure ridge having a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of said interfacial contact footprint, and at said widest footprint location said interfacial contact pressure increasing from zero at said first footprint edge to a greater value at a Position P2 on said ridgeline, said rotary seal maintaining a positive value of E WH at said upper temperature, wherein E WH = Dimension B2 - Width W1 where Dimension B2 is an axial length from said second footprint edge to said Position P2 on said ridgeline at said widest footprint location, and Width W1 is said axial footprint width at said narrowest footprint location, and said Dimension B2 is governed at least in part by said inlet curvature at said widest dynamic surface location.

34. The rotary seal assembly of claim 33, wherein said seal body having an inwardly facing surface, said dynamic lip projecting from said inwardly facing surface and at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface of said seal body and said inlet curvature.

35. The rotary seal assembly of claim 33, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

36. The rotary seal assembly of claim 33, wherein in said uncompressed condition an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by an extent line blending curve at said narrowest footprint location.

37. The rotary seal assembly of claim 33, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

38. The rotary seal assembly of claim 33, wherein said seal body has an inwardly facing surface, said dynamic lip projecting from said inwardly facing surface and said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said widest dynamic surface location.

39. The rotary seal assembly of claim 33, wherein said seal body has an inwardly facing surface, said dynamic lip projecting from said inwardly facing surface and said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said narrowest dynamic surface location.

40. The rotary seal assembly of claim 33, wherein said lubricant side flank being an unconstrained geometry having clearance with respect to said first groove wall.

41. The rotary seal assembly of claim 33, wherein said dynamic exclusionary intersection being generally circular, said dynamic surface extending from said dynamic exclusionary intersection to said inlet curvature, and at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

42. The rotary seal assembly of claim 33, wherein said rotary seal held in skew-resisting confinement even at room temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall.

43. The rotary seal assembly of claim 33, wherein said rotary seal has a positive value of E WH
of at least 0.020" at said upper temperature.

44. The rotary seal assembly of claim 33, wherein said rotary seal has a positive value of E WH
of at least 0.020" at a temperature of 50°F greater than said upper temperature.

45. The rotary seal assembly of claim 33, wherein said rotary seal has a positive value of E WH
at a temperature of 50°F greater than said upper temperature.

46. The rotary seal assembly of claim 33, wherein said first and second groove walls are spaced a fixed distance from one another.

47. The rotary seal assembly of claim 33, wherein at least one of said first and second groove walls is a spring-loaded moveable gland wall.

48. A rotary seal assembly, comprising:
a first machine component having a seal groove defined by generally opposing first and second groove walls and a peripheral groove wall;
a second machine component located at least partially within said first machine component having a relatively rotatable surface in generally opposed relation to said peripheral groove wall and rotatable relative to said first machine component;
a generally ring-shaped interference-type rotary seal being located at least partially within said seal groove, said rotary seal comprising a seal body of at least one resilient thermally expandable sealing material having an operating temperature range with an upper bound defined by an upper temperature, said seal body having first and second seal ends, said rotary seal held in skew-resisting confinement at said upper temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall;
wherein in an uncompressed condition said seal body including a dynamic lip and an inwardly facing surface, said dynamic lip projecting radially inward from said inwardly facing surface and comprising a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward, a lubricant side flank having a slope and located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, and a hydrodynamic inlet curvature located between and separating said dynamic surface and said lubricant side flank, said inlet curvature being at least part of a hydrodynamic geometry, said dynamic surface having an axial width between said dynamic exclusionary intersection and said inlet curvature that in a circumferential direction increases from a first narrower surface location to a first wider surface location, decreases from said first wider surface location to a second narrower surface location, increases from said second narrower surface location to a second wider surface location, and decreases from said second wider surface location to a third narrower surface location, wherein said first wider surface location being situated between said first and second narrower surface locations and being the widest dynamic surface location between said first and second narrower surface locations, being referred to as the first widest dynamic surface location, said second narrower surface location being situated between said first and second wider surface locations and being the narrowest dynamic surface location between said first and second wider surface locations, being referred to as the first narrowest dynamic surface location, and said second wider surface location being situated between said second and third narrower surface locations and being the widest dynamic surface location between said second and third narrower surface locations, being referred to as the second widest dynamic surface location;
said slope of said lubricant side flank varies from said first widest dynamic surface location to said first narrowest dynamic surface location, said slope being steeper relative to said dynamic surface at said first widest dynamic surface location than at said first narrowest dynamic surface location;
said dynamic lip being held in compression against said relatively rotatable surface and defining a circumferential interfacial contact footprint against said relatively rotatable surface, said interfacial contact footprint comprising peripheral first and second footprint edges, said first footprint edge being generally wavy, said footprint having an axial footprint width between said first and second footprint edges that increases from a first narrower footprint location to a first wider footprint location, decreases from said first wider footprint location to a second narrower footprint location, increases from said second narrower footprint location to a second wider footprint location, and decreases from said second wider footprint location to a third narrower footprint location, wherein said first wider footprint location being situated between said first and second narrower footprint locations and being the widest footprint location between said first and second narrower footprint locations, being referred to as the first widest footprint location, said second narrower footprint location being situated between said first and second wider footprint locations and being the narrowest footprint location between said first and second wider footprint locations, being referred to as the first narrowest footprint location, and said second wider footprint location being situated between said second and third narrower footprint locations and being the widest footprint location between said second and third narrower footprint locations, being referred to as the second widest footprint location;
wherein said compression of said dynamic lip against said relatively rotatable surface establishes interfacial contact pressure within said footprint including a lubricant-side pressure ridge along said first footprint edge, said lubricant-side pressure ridge having a ridgeline established by the maximum interfacial contact pressure of the lubricant-side pressure ridge at each circumferential location of said interfacial contact footprint, and at said first widest footprint location said interfacial contact pressure increasing from zero at said first footprint edge to a greater value at a Position P2 on said ridgeline, said rotary seal maintaining a positive value of E WH at said upper temperature wherein E WH = Dimension B2 - Width W1 where Dimension B2 is an axial length from said second footprint edge to said Position P2 on said ridgeline at said first widest footprint location, and Width W1 is said axial footprint width at said first narrowest footprint location; and said first widest footprint location corresponding circumferentially to said first widest dynamic surface location, and said first narrowest dynamic surface location corresponding circumferentially to said first narrowest footprint location.

49. The rotary seal assembly of claim 48, wherein at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature.

50. The rotary seal assembly of claim 48, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

51. The rotary seal assembly of claim 48, wherein in said uncompressed condition an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by an extent line blending curve at said first narrowest dynamic surface location.

52. The rotary seal assembly of claim 48, wherein in said uncompressed condition said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

53. The rotary seal assembly of claim 48, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said first widest dynamic surface location.

54. The rotary seal assembly of claim 48, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said first narrowest dynamic surface location.

55. The rotary seal assembly of claim 48, wherein said lubricant side flank being an unconstrained geometry.

56. The rotary seal assembly of claim 48, wherein in said uncompressed condition said dynamic exclusionary intersection being generally circular, and at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

57. The rotary seal assembly of claim 48, wherein said rotary seal held in skew-resisting confinement even at room temperature by virtue of simultaneous contact of said first seal end with said first groove wall and said second seal end with said second groove wall.

58. The rotary seal assembly of claim 48, wherein said rotary seal has a positive value of E WH
of at least 0.020" at said upper temperature.

59. The rotary seal assembly of claim 48, wherein said rotary seal has a positive value of E WH
of at least 0.020" in operating conditions having a temperature of 50°F
greater than said upper temperature.

60. The rotary seal assembly of claim 48, wherein said rotary seal has a positive value of E WH
in operating conditions having a temperature of 50°F greater than said upper temperature.

61. The rotary seal assembly of claim 48, wherein said first and second groove walls are spaced a fixed distance from one another.

62. The rotary seal assembly of claim 48, wherein at least one of said first and second groove walls is a spring-loaded moveable gland wall.

63. The rotary seal assembly of claim 48, wherein said inlet curvature extends continuously in a circumferential direction from said first widest dynamic surface location to said first narrowest dynamic surface location to said second widest dynamic surface location.

64. A rotary seal for bi-directional rotation, the rotary seal in an uninstalled condition comprising:

a generally ring-shaped seal body having a circumference, said seal body having first and second seal ends, a dynamic lip and an inwardly facing surface having an exposed length;
said dynamic lip projecting radially inward of said inwardly facing surface and comprising a lubricant side flank, a dynamic exclusionary intersection of abrupt generally circular form, a hydrodynamic inlet curvature, and a dynamic surface facing radially inward and ending at said abrupt dynamic exclusionary intersection, said hydrodynamic inlet curvature being located between and separating said lubricant side flank and said dynamic surface and varying in position from said dynamic exclusionary intersection about said circumference;
said dynamic surface being located between said hydrodynamic inlet curvature and said dynamic exclusionary intersection, said dynamic surface having an axial width from said dynamic exclusionary intersection to said hydrodynamic inlet curvature that varies around said circumference of said seal body in a wavy fashion, having at least two wider surface axial width locations and at least two narrower surface axial width locations, one of said narrower surface axial width locations being the narrowest dynamic surface axial width location between said at least two wider surface axial width locations and one of said at least two wider surface width locations being the widest dynamic surface location between said at least two narrower surface axial width locations, said hydrodynamic inlet curvature adjoining said dynamic surface at and between said at least two narrower surface axial width locations and adjoining said dynamic surface at and between said at least two wider surface axial width locations;
and said lubricant side flank being located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature, said lubricant side flank having an end thereof varying in position from said dynamic exclusionary intersection in a wavy fashion and having a slope in the axial direction that varies along at least part of said circumference, said slope of said lubricant side flank being steeper relative to said dynamic surface at said wider surface axial width locations than at said narrower surface axial width locations.

65.
The rotary seal of claim 64, wherein all of said lubricant side flank being located axially between said inwardly facing surface and said inlet curvature.

66. The rotary seal of claim 64, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

67. The rotary seal of claim 64, wherein an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by at least one extent line blending curve.

68. The rotary seal of claim 64, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

69. The rotary seal of claim 64, wherein said dynamic surface having a widest dynamic surface location, and said exposed length of said inwardly facing surface is present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said widest dynamic surface location.

70. The rotary seal of claim 64, wherein said dynamic surface having a narrowest dynamic surface location, and said exposed length of said inwardly facing surface is present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said narrowest dynamic surface location.

71. The rotary seal of claim 64, wherein said dynamic exclusionary intersection being generally circular, at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

72. The rotary seal of claim 64, wherein said slope of said lubricant side flank is represented by an angle a having a vertex when viewed in longitudinal cross-section, said vertex of said angle a is a theoretical intersection formed by extending the lines of said dynamic surface and said lubricant side flank.

73. A hydrodynamic rotary seal for bi-directional rotation, the rotary seal in an uninstalled condition comprising:
a circumferential seal body having a dynamic lip of generally circular form, said seal body forming a ring comprised of sealing material having a thermally expandable seal volume;
said seal body having an inwardly facing surface, said dynamic lip projecting radially inwardly from said inwardly facing surface and including a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward and having an end at said dynamic exclusionary intersection, a lubricant side flank that is non-circular and located in spaced relation with respect to said dynamic exclusionary intersection and located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, and a hydrodynamic inlet curvature located between and separating said dynamic surface and said lubricant side flank;
said dynamic surface having narrower surface locations and wider surface locations, each of said wider surface locations being the axially widest dynamic surface location between a pair of said narrower surface locations, and at least one of said narrower surface locations being the axially narrowest dynamic surface location between a pair of said wider surface locations;
said inlet curvature being at least a portion of a rotationally bi-directional hydrodynamic inlet capable of providing hydrodynamic lubrication of said dynamic surface in response to clockwise and counter-clockwise relative rotation when installed against a relatively rotatable surface and exposed to a lubricant, said inlet curvature adjoining said dynamic surface at said wider and said narrower surface locations;
said lubricant side flank having a slope in an axial direction that varies in steepness relative to said dynamic surface, said slope of said lubricant side flank being steeper relative to said dynamic surface at said wider surface locations compared to said slope at said at least one narrower surface location, said slope at said wider surface locations minimizing said seal volume.

74. The rotary seal of claim 73, wherein at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature.

75. The rotary seal of claim 73, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

76. The rotary seal of claim 73, wherein an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by at least one extent line blending curve, said extent line extending in a circumferential direction from one of said narrower surface locations, past said widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations.

77. The rotary seal of claim 73, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

78. The rotary seal of claim 73, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said widest dynamic surface location.

79. The rotary seal of claim 73, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said narrowest dynamic surface location.

80. The rotary seal of claim 73, wherein said dynamic exclusionary intersection being generally circular, and at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

81. The rotary seal of claim 73, wherein at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature.

82. A ring-shaped hydrodynamic rotary seal for bi-directional rotation, the hydrodynamic rotary seal in an uncompressed condition comprising:

a ring-shaped seal body having a first end and an inwardly facing surface;
said seal body including a dynamic lip of generally circular form projecting radially inward from said inwardly facing surface and having a dynamic exclusionary intersection of abrupt form, a dynamic surface facing radially inward, a lubricant side flank that is non-circular and located in spaced relation with respect to said dynamic exclusionary intersection and located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, a hydrodynamic inlet curvature located between and separating said dynamic surface and said lubricant side flank and located in spaced relation with respect to said dynamic exclusionary intersection and being at least a portion of a wavy, rotationally bi-directional hydrodynamic geometry, said dynamic surface extending from said inlet curvature to said dynamic exclusionary intersection;
said dynamic surface having at least two wider surface locations, at least one of said wider surface locations being the widest dynamic surface location between two narrower surface locations, at least one of said two narrower surface locations being the narrowest dynamic surface location between said at least two wider surface locations;
said hydrodynamic inlet curvature being located between and adjoining said lubricant side flank and said dynamic surface and extending continuously in a circumferential direction from one of said narrower surface locations, past said widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations;
said lubricant side flank having a slope that varies from said widest dynamic surface location to said narrowest dynamic surface location, said slope being steeper relative to said dynamic surface at said widest dynamic surface location than at said narrowest dynamic surface location; and said rotary seal being comprised of seal material having a volume, said slope of said lubricant side flank being steepest relative to said dynamic surface at said widest dynamic surface location minimizing said volume of said seal material.

83.
The rotary seal of claim 82, wherein said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature.

84. The rotary seal of claim 82, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

85. The rotary seal of claim 82, wherein an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by an extent line blending curve at said narrowest dynamic surface location, said extent line extending in the circumferential direction from one of said narrower surface locations, past said widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations.

86. The rotary seal of claim 82, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

87. The rotary seal of claim 82, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said widest dynamic surface location.

88. The rotary seal of claim 82, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said narrowest dynamic surface location.

89. The rotary seal of claim 82, wherein said dynamic exclusionary intersection being generally circular, and at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

90. The rotary seal of claim 82, wherein at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature.

91. A hydrodynamic rotary seal for bi-directional rotation, the rotary seal in an uninstalled condition comprising:

a generally ring-shaped seal body having a first seal end and an inwardly facing surface;
said seal body including a dynamic lip projecting radially inward from said inwardly facing surface and comprising a dynamic surface facing radially inward, a lubricant side flank having a slope and located entirely radially outward of said dynamic surface and in spaced relation to said dynamic surface, and a hydrodynamic inlet curvature located between and separating said dynamic surface and said lubricant side flank, said inlet curvature being at least part of a rotationally bi-directional hydrodynamic geometry, said dynamic surface having an axial width that increases from a first narrower surface location to a first wider surface location, decreases from said first wider surface location to a second narrower surface location, increases from said second narrower surface location to a second wider surface location, and decreases from said second wider surface location to a third narrower surface location, wherein said first wider surface location being situated between said first and second narrower surface locations and being the widest dynamic surface location between said first and second narrower surface locations, being referred to as the first widest dynamic surface location, said second narrower surface location being situated between said first and second wider surface locations and being the narrowest dynamic surface location between said first and second wider surface locations, said second wider surface location being situated between said second and third narrower surface locations and being the widest dynamic surface location between said second and third narrower surface locations, being referred to as the second widest dynamic surface location, and wherein said slope of said lubricant side flank varies from said first widest dynamic surface location to said narrowest dynamic surface location, said slope being steeper relative to said dynamic surface at said first widest dynamic surface location than at said narrowest dynamic surface location.

92.
The rotary seal of claim 91, wherein said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature.

93. The rotary seal of claim 91, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape with small blending curves.

94. The rotary seal of claim 91, wherein an extent line is defined by a substantial tangency between said inlet curvature and said dynamic surface, wherein said extent line has a generally zig-zag shape blended by an extent line blending curve at said narrowest dynamic surface location, said extent line extending in a circumferential direction from one of said narrower surface locations, past said first widest dynamic surface location and past said narrowest dynamic surface location to one of said wider surface locations.

95. The rotary seal of claim 91, wherein said dynamic lip further defines a theoretical intersection of said dynamic surface and said lubricant side flank, at least part of said theoretical intersection is a generally zig-zag shape.

96. The rotary seal of claim 91, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said first widest dynamic surface location.

97. The rotary seal of claim 91, wherein said inwardly facing surface has an exposed length present between said first seal end and at least part of said lubricant side flank, said exposed length being present at at least said narrowest dynamic surface location.

98. The rotary seal of claim 91, wherein said dynamic exclusionary intersection being generally circular, and at least part of a theoretical intersection between said dynamic surface and said lubricant side flank varies in position from said dynamic exclusionary intersection in a wavy zig-zag shape.

99. The rotary seal of claim 91, wherein at least a portion of said lubricant side flank being located between at least a portion of said inwardly facing surface and said inlet curvature.