Hydrodynamic mating ring with integrated groove inlet pressure control

A hydrodynamic mating ring of the present disclosure may include a sealing face, a hydrodynamic groove disposed in the sealing face, an impeller portion, and an inlet conduit configured to provide fluid communication between the hydrodynamic groove and the impeller portion. A method of sealing may include providing a mating ring having a sealing face, a plurality of hydrodynamic grooves disposed in the sealing face, a plurality of impeller portions, and a plurality of inlet conduits configured to provide fluid communication between respective ones of the plurality of hydrodynamic grooves and the plurality of impeller portions. The method may include rotating the mating ring, and increasing at least one of a pressure, a volume, and a flow rate of fluid to the hydrodynamic grooves via the plurality of impeller portions drawing said fluid into the plurality of inlet conduits.

BACKGROUND

Technical Field

The present disclosure relates generally to hydrodynamic face seals.

Description of the Related Art

Spiral groove lift-off seals (also known as hydrodynamic seals or hydrodynamic face seals) have been used successfully for many years in the industrial gas compressor industry.

Generally, the seal assembly involves a system fluid pressure (e.g., gas density). The high fluid pressure may be located on either an inside diameter of a seal assembly or the outside diameter of a seal assembly. The seal assemblies may comprise two rings where a face of each ring is adjacent to one another. A first ring may be a stationary member, also known as a seal ring, and may be movable only in an axial direction. A second ring may be a rotational member, also known as a mating ring or rotor, which may rotate about an axis that is generally shared by the two components. The second ring may contain a plurality of grooves on the face adjacent to the first ring. The grooves, which may be spiral in shape, may be grooved toward a low pressure side of the second ring. The grooves may have a dam section where the groove ends. A sealing, effect around the dead ended grooves can provide a compression of a working fluid, such as gas, resulting in a pressure increase in the groove region. The increase in pressure can cause the faces to separate slightly, which can allow the pressured fluid, such as air, to escape the grooves. A steady state force balance between opening and closing forces may be generally achieved at some determinable face separation gap. The seal may operate in a non-contact mode above some threshold rotational speed.

However, when employing conventional hydrodynamic groove technology for the purpose of producing a film riding seal (e.g., non-contacting) in or under certain conditions, such as the outside environment of an aircraft at cruising altitude, the ability for a sufficient amount of fluid to enter the hydrodynamic grooves may be diminished due to a lower speed, lower density, and/or a rarefaction of the fluid. The resulting hydrodynamic fluid film between the rotating mating ring and the stationary seal ring can be significantly reduced. Thin hydrodynamic fluid films may be less stable than desired and may result in higher heat generation due, for example, to intermittent contact from transient conditions and high vicious shear of the fluid.

Among other things, the present disclosure addresses one or more of the aforementioned challenges.

SUMMARY

In embodiments, a hydrodynamic mating ring may include a sealing face, a hydrodynamic groove disposed in the sealing face, an impeller portion, and/or an inlet conduit that may be configured to provide fluid communication between the hydrodynamic groove and the impeller portion. The mating ring may include a buffer that may be disposed beneath the sealing face and may be in fluid communication with the impeller portion and/or the inlet conduit.

In embodiments, a method of sealing may include providing a mating ring that may include a sealing face, a plurality of hydrodynamic grooves disposed in the sealing face, a plurality of impeller portions, and/or a plurality of inlet conduits that may be configured to provide fluid communication between respective ones of the plurality of hydrodynamic grooves and the plurality of impeller portions. The method may include rotating the mating ring, and increasing at least one of a pressure, a volume, and a flow rate of fluid to the hydrodynamic grooves via the plurality of impeller portions drawing said fluid into the plurality of inlet conduits.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the present disclosure, examples of which are described herein and illustrated in the accompanying drawings. While the disclosed concepts will be described in conjunction with embodiments, it will be understood that they are not intended to limit the disclosure to these embodiments. On the contrary, the disclosure is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope as defined by the appended claims.

Referring toFIGS. 1 and 2, a seal assembly20may include a first ring30and a second ring40. The first ring30, which may also be referred to as a seal ring30, may be stationary in terms of rotation, but for applications may be permitted to move in the axial direction22A—e.g., along a central axis22. An axial/sealing face32of the seal ring30may be disposed adjacent the axial/sealing face42of a second ring40. In embodiments, an axial face32may be a flat lapped face, and may be substantially flat.

In embodiments, second ring40, which may also be referred to as a mating ring40or rotor40, may be configured to rotate about central axis22(e.g., with shaft24). Second ring40may include axial face42, an inner diameter44, an inner diameter surface46, an outer diameter48, an outer diameter surface50, a groove52, a dam54, an inlet conduit70, and/or an impeller portion80. With embodiments, axial face42of rotating second ring40may include a relatively hard face coating and/or material with respect to the material of the first ring30.

In embodiments, axial face42may include groove52, which may include a single groove or a plurality of grooves, where each groove of the plurality of grooves may have characteristics such as those described in further detail herein. In embodiments, grooves52may include a depth52A that may be configured to generate a hydrodynamic force. Groove depths52A may vary, for example, and without limitation, from 150 to 900 micro-inches. A dam54may be disposed at or near the ends of the grooves52somewhere along the axial face42of second ring40. The dam54can facilitate the compression of a fluid, such as a gas (e.g., air), which can result in a pressure increase in and/or near the groove52of second ring40. The increase in the pressure may cause axial face42of second ring40to separate by a distance38from a corresponding/mating surface of an adjacent component, such as axial face32of first ring30(e.g., at least one of first ring30and second ring40may move away from the other). This distance/separation38may be slight, such as, for example, on the order of around 100 to 600 micro-inches. Seal leakage may occur across dam54and may be relatively minimal because distance38between the axial faces32,42may be relatively small.

In embodiments, grooves52may be disposed in a sealing portion56of axial face42. In embodiments, sealing portion56may be defined by a first intermediate diameter58of second ring40and a second intermediate diameter60of second ring40, and/or may include a radial extent56A. For example, and without limitation, grooves52may extend generally radially between first intermediate diameter58and second intermediate diameter60. First intermediate diameter58may be disposed radially inward of second intermediate diameter60, and first and second intermediate diameters58,60of second ring40may correspond, respectively, to an inner diameter34and an outer diameter36of first ring30. In embodiments of a seal assembly20, first ring30may be disposed such that first ring30covers some or all of grooves52of second ring40in radial direction22B and/or in a circumferential direction22C. For example, and without limitation, a distance/radial extent30A between inner diameter34and outer diameter36may be greater than With such configurations, first ring30may effectively cover and/or seal off grooves52in such a way that system fluid26may not enter grooves52directly. Instead, grooves52may be in indirect fluid communication with system fluid26via inlet conduits70and/or impellers80.

An inlet conduit70may be configured to provide fluid communication between a groove52and an impeller portion80, and may be disposed partially or entirely below axial face42. Inlet conduit70may be configured such that it does not compress fluid26that travels through inlet conduit70. For example, and without limitation, inlet conduit70may include a generally constant cross-sectional area. In embodiments, inlet conduits70may be configured to help maintain the momentum of flowing fluid26. For example, and without limitation, inlet conduits70may be generally aligned with (e.g., may include a central axis that is generally parallel to central axes of) outlets84of impeller portions80, which may allow flowing fluid26to continue to flow from impeller portions80into inlet conduits70without a significant change in direction. In an axial configuration of an impeller portion80, described in greater detail below, inlet conduits70may be generally aligned with (e.g., parallel to) the radial direction22B. In a radial configuration of an impeller portion80, also described in greater detail below, inlet conduits70may be disposed at an angle, which may be an oblique angle, relative to the radial direction22B.

With embodiments, to improve (e.g. increase) the volume, pressure, and/or rate of the fluid26(e.g., gas) entering grooves52, such to create a fluid film28, second ring40may include one or more impeller portions80. An impeller portion80may include an inlet82and/or an outlet84. Inlet82may be configured to receive system fluid26and an outlet84may be configured for fluid connection/communication with an inlet conduit70. Impeller portion80may help maintain a sufficient fluid film28between first and second rings30,40to reduce/prevent wear. In embodiments, a second ring40may include an impeller portion80for each groove52. In such embodiments, each impeller portion80may be configured to improve the volume, pressure, and/or flow rate of fluid26for a respective groove52. In embodiments, an impeller portion80may correspond to (e.g., be in fluid communication with) with a plurality of inlet conduits70and/or grooves52. In embodiments, a plurality of impeller portions80may correspond to the same inlet conduit70and/or the same groove52.

As generally illustrated in the figures (see, e.g.,FIG. 3A), each impeller portion80may be configured to provide fluid to a respective inlet conduit70and groove52pairing, and one or more of the impeller inlets82may not overlap radially with the groove52to which the impeller portion80is intended to provide fluid26. For example, and without limitation, the circumferential position of impeller inlet82′ may be offset by a distance (e.g., distance86) from the circumferential position of groove52′. In embodiments, an inlet82of an impeller portion80may be disposed ahead of a corresponding groove52relative to a direction of rotation of second ring40. For example, and without limitation, as generally illustrated inFIG. 3A, the direction of rotation of second ring40may be a counterclockwise direction22E and inlet82′ of impeller portion80may be disposed ahead of corresponding groove52′ in the counterclockwise direction22E.

In embodiments, a circumferential length82A of an impeller inlet82,82′ may correspond to the number of impeller portions80and/or the number of grooves52of second ring40. Impeller inlets82,82′ may be configured such that each has a given length—e.g., the largest circumferential length82A possible that also allows for a desired circumferential length90A of a land90between each impeller portion80. In embodiments, the circumferential length82A of an impeller inlet82may be significantly greater than the width52B of the grooves52, which may include the circumferential length82A of an impeller inlet62being three or four or more times larger than the width52B of the grooves52.

In embodiments, impeller portions80may be configured to help maintain the momentum, of flowing system fluid26and/or minimize flow disturbances (e.g., sharp turns), which may help maintain a fluid film28between first and second rings30,40. For example, and without limitation, as generally illustrated inFIGS. 1 and 2, in embodiments in which system fluid26is directed generally along an axial direction22A substantially aligned with central axis22, an axial configuration of impeller portion80may include an impeller inlet82being disposed at axial face42. An impeller inlet82disposed at axial face42may receive fluid26and gradually alter the path of the fluid26as fluid26moves toward an inlet conduit70and ultimately to a groove52. In an axial configuration, impeller portion80and/or inlet conduit70may be disposed radially inward of grooves52.

As generally illustrated inFIGS. 3A, 3B, and 4, in other embodiments, in which system fluid26is provided in the radial direction22B relative to central axis22(e.g., at outer diameter surface50), a radial configuration of an impeller portion80may include the inlet82of impeller portion80being disposed at outer diameter surface50of second ring40. Inlet82in a radial configuration of impeller portion80may extend generally in the axial direction22A and the circumferential direction22C, and impeller portion80may extend generally radially inward toward inlet conduit70. In a radial configuration, impeller portion80and/or inlet conduit70may be disposed radially outward of grooves52.

In embodiments, the shape of the impeller portion80may be configured to receive system fluid26, compress the received fluid26, and convey the compressed fluid26to inlet conduit70. As generally illustrated inFIG. 2, in an axial configuration, an impeller inlet82may include a relatively large cross-sectional area and/or perimeter (e.g., relatively large radial and/or circumferential dimensions at axial face42), and the cross-sectional area and/or perimeter of impeller portion80may decrease as the impeller portion80extends radially outward and axially inward within second ring40to connect with inlet conduit70. As generally illustrated inFIG. 4, in a radial configuration, an impeller inlet82may include a relatively large cross-sectional area and/or perimeter at outer diameter48and/or inlet82, and the cross-sectional area and/or perimeter of impeller portion80may decrease as impeller portion80extends radially inward toward its outlet84. A decreasing cross-sectional area of impeller portion80(e.g., from inlet82to outlet84) may permit impeller portion80to compress fluid26that enters impeller portion80(e.g., at axial face42or outer diameter surface50) as fluid26moves toward inlet conduit70.

In embodiments, impeller portion80may be configured to take advantage of relative rotation between first ring30and second ring40. Impeller portion80may be shaped to correspond to a direction of rotation, such that rotation of first ring30relative to second ring40may permit impeller portion80to draw fluid26in the vicinity of impeller portion80into impeller portion80. Impeller portion80may draw in fluid26even if fluid26is not otherwise directed toward impeller portion80(e.g., if fluid26is not flowing toward impeller portion80and/or if fluid26is not sufficiently pressurized). In such a configuration, impeller portion80may transfer energy from the rotation of the first and second rings30,40to the fluid26, which may be in the form of increasing flow rate (e.g., kinetic energy) and/or increasing fluid pressure (e.g., potential energy). Increasing the energy of fluid26may help generate sufficient hydrodynamic force to maintain sealing film28between the first and second rings30,40. For example, in low pressure (e.g., high altitude) and/or low rotational speed conditions, fluid26may not be sufficiently pressurized and/or may not be flowing at a sufficient rate on its own to generate a sufficient fluid film28between first and second rings30,40to keep first and second rings30,40apart. In such low pressure and/or low rotational speed conditions, impeller portion80may draw and/or scoop in a sufficient amount of fluid26and/or sufficiently compress fluid26(e.g., as a result of impeller portion geometry) such that fluid film28is maintained between the first and second rings30,40.

In embodiments, an impeller portion80may comprise one or more of a variety of shapes, sizes and/or configurations. In embodiments, a second ring40may comprise a plurality of impeller portions80, at least one of which may include a different shape, size, and/or configuration than another of the plurality of impeller portions80. Impeller portions80may be customized according, to an intended environment (e.g., expected pressure conditions/altitudes, expected rotational speeds, expected flow rates, etc.).

As generally illustrated inFIG. 1, an embodiment of an impeller portion80may include a generally rectangular shape that may include a convex edge and/or a concave edge. A concave edge may be a leading edge relative to an intended direction of rotation. As generally illustrated inFIGS. 5 and 6, a top portion92of a land90may generally be disposed at or near, and/or be generally flush with axial face42. In embodiments, as generally illustrated inFIG. 7, a top portion92of a land90may be generally curved with respect to the axial direction22A. A curved impeller top portion92may include a first section92A of top portion92being disposed generally flush with axial face42and a second section9213of top portion92being disposed axially offset from (e.g., below or above) axial face42.

In embodiments, a land90may separate adjacent impeller portions80. As generally illustrated inFIG. 1, lands90may be about the same size and/or shape as the impeller portions80. As generally illustrated inFIGS. 5-6, lands90between adjacent impeller portions80may be relatively thin compared to the circumferential length/extent82A of impeller portions80(e.g., the circumferential extent90A of the lands90may be half or less of the circumferential extent80A of the impeller portions80). Also as generally illustrated inFIGS. 5-6, impeller portions80may be angled relative to the axial direction22A (e.g., planes defined by the axial and radial directions) and/or may be angled toward a direction of intended rotation. For example, and without limitation, for a second ring40with an intended rotation in the clockwise direction22D, impeller portions80and/or land top portions92may be angled toward the clockwise direction22D.

In embodiments, impeller portions80may include a portion having a generally wavy configuration/shape (see, e.g.,FIGS. 5, 5A, and 5B). A wavy shape may correspond to lands90including a wavy shape relative to the radial direction22B. In embodiments, such as generally illustrated inFIG. 5, impeller portions80may include a neutral configuration, in which lands90may be generally aligned with the radial direction22B. In embodiments, such as generally illustrated inFIG. 5A, impeller portions80may include a leading configuration, in which lands90may be angled such that radially outer portions of lands90are circumferentially ahead (e.g., in a direction of rotation) of radially inner portions of lands90. In embodiments, such as generally illustrated inFIG. 5B, impeller portions80may include a trailing configuration, in which lands90may be angled such that radially outer portions of lands90are circumferentially behind (e.g., in a direction of rotation) radially inner portions of lands90.

In embodiments, impeller portions may include a generally rectangular configuration/shape, such as generally illustrated inFIG. 5C, which may correspond to lands90being generally aligned with the radial direction. Rectangular-shaped impeller portions80may include a neutral, trailing, and/or leading configuration.

In embodiments, impeller portions80may include a generally convex configuration/shape, such as generally illustrated inFIG. 5D, which may correspond to lands90being curved in the direction of anticipated rotation (e.g., curved in the clockwise direction). Convex-shaped impeller portions80may include a neutral, trailing, and/or leading configuration.

In embodiments, impeller portions may include a generally concave configuration/shape, such as generally illustrated inFIG. 5E, which may correspond to lands90being curved in the direction opposite of anticipated rotation (e.g., curved in the counterclockwise direction). Concave-shaped impeller portions80may include a neutral, trailing, and/or leading configuration.

In embodiments, the circumferential length/extent90A of lands90may vary across their axial lengths. For example, and without limitation, the circumferential length90A of lands90may be the smallest at or near axial face42and may increase as lands90extend generally axially inward (e.g., farther below axial face42).

In embodiments, such as generally illustrated inFIGS. 5, 6, and 7, second ring40may include a buffer100that may be configured to dampen the effects of variations in system fluid pressure. Buffer100may be configured to accumulate or store system fluid26received by impeller portions80so that in the event of a change in system fluid characteristics (e.g., pressure, flow rate, etc.), accumulated or stored fluid26in buffer100may be provided to grooves52via inlet conduits70to maintain the film28between first and second rings30,40.

Buffer100may comprise one or more of a variety of shapes, sizes, and/or configurations. Buffer100may include a fluid chamber102disposed under axial face42and/or may extend generally circumferentially about second ring40relative to central axis22. Chamber102may extend circumferentially along part and/or all of second ring40. In embodiments, chamber102may include a single continuous chamber, or chamber102may include a plurality of chamber sections (e.g., chamber sections104,106). A plurality of chamber sections may include sections of generally the same size, shape, and configuration or at least one of the sections may be different from the at least one other section. In embodiments, buffer100may include first chamber section104and second chamber106, and first section104may include a relatively small volume with respect to second section106.

Buffer100may be disposed in a fluid path between impeller portions80and inlet conduits70and/or may provide fluid communication between impeller portions80and inlet conduits70. In embodiments, impeller portions80may not be in direct fluid communication with inlet conduits70, but may instead be in indirect fluid communication with inlet conduits70via buffer100.

In embodiments, the volume associated with buffer100may correspond to a desired behavior of second ring40. For example, and without limitation, in embodiments, variations in external conditions (e.g., system pressure) may typically occur relatively quickly, but may last for a relatively short period of time. For such quick and short variations, it may be desirable for the volume of buffer100to be relatively small so that buffer100is able to quickly respond to the variations. For embodiments in which variations occur relatively slowly, but may last for a relatively long period of time, it may be desirable for the volume of buffer100to be relatively large so that grooves52may be supplied with fluid26from buffer100for a longer or extended period of time. In embodiments, the volume of buffer100may be greater than the collective volumes of all of the inlet conduits70. In embodiments, buffer100may include a portion100A disposed axially inward of (e.g., further below axial face42than) inlet conduit70.

Although only certain embodiments have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this disclosure. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily imply that two elements are directly connected/coupled and in fixed relation to each other. The use of “e.g.” throughout the specification is to be construed broadly and is used to provide non-limiting examples of embodiments of the disclosure, and the disclosure is not limited to such examples. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the present disclosure.