Patent Description:
Rotational equipment typically includes one or more seal assemblies for sealing gaps between rotors and stators. A typical seal assembly includes a contact seal with a seal element such as a knife edge seal that engages a seal land. Such a contact seal can generate a significant quantity of heat that can reduce efficiency of the rotational equipment as well as subject other components of the rotational equipment to high temperatures and internal stresses. To accommodate these high temperatures and stresses, certain components of the rotational equipment may be constructed from specialty high temperature materials. However, these materials can significantly increase manufacturing and servicing costs as well as mass of the rotational equipment. While non-contact seals have been developed in an effort to reduce heat within rotational equipment, there is still room for improvement to provide an improved non-contact seal. In particular, there is room in the art for a non-contact seal with improved secondary sealing characteristics.

Prior art includes <CIT>, <CIT>, <CIT> and <CIT>. <CIT> discloses an assembly for rotational equipment according to the preamble of claim <NUM>.

According to an aspect of the present invention, an assembly is provided for rotational equipment as claimed in claim <NUM>. Various embodiments of the invention are defined by the dependent claims.

The present invention may include any one or more of the individual features disclosed above and/or below alone or in any combination thereof falling within the scope of the claims.

<FIG> illustrates an assembly <NUM> for rotational equipment with an axial centerline <NUM>, which axial centerline <NUM> may also be an axis of rotation (e.g., a rotational axis) for one or more components of the rotational equipment assembly <NUM>. An example of such rotational equipment is a gas turbine engine for an aircraft propulsion system, an exemplary embodiment of which is described below in further detail (e.g., see <FIG>). However, the rotational equipment assembly <NUM> of the present disclosure is not limited to such an aircraft or gas turbine engine application. The rotational equipment assembly <NUM>, for example, may alternatively be configured with rotational equipment such as an industrial gas turbine engine, a wind turbine, a water turbine or any other apparatus in which a seal is provided between a stationary structure and a rotating structure; e.g., a rotor.

The rotational equipment assembly <NUM> of <FIG> includes a stationary structure <NUM>, a rotating structure <NUM> and a seal assembly <NUM> such as, for example, a non-contact seal assembly. The seal assembly <NUM> is mounted with the stationary structure <NUM> and configured to substantially seal an annular gap between the stationary structure <NUM> and the rotating structure <NUM> as described below in further detail.

The stationary structure <NUM> includes a seal carrier <NUM>. This seal carrier <NUM> may be a discrete, unitary annular body. Alternatively, the seal carrier <NUM> may be configured with another component / portion of the stationary structure <NUM>. The seal carrier <NUM> has a seal carrier inner surface <NUM>. This seal carrier inner surface <NUM> may be substantially cylindrical. The seal carrier inner surface <NUM> extends circumferentially about (e.g., completely around) and faces towards the axial centerline <NUM>. The seal carrier inner surface <NUM> at least partially forms a bore in the stationary structure <NUM>. This bore is sized to receive the seal assembly <NUM>, which seal assembly <NUM> may be fixedly attached to the seal carrier <NUM> by, for example, a press fit connection between the seal assembly <NUM> and the seal carrier inner surface <NUM>. The seal assembly <NUM>, of course, may also or alternatively be fixedly attached to the seal carrier <NUM> using one or more other techniques / devices.

The rotating structure <NUM> includes a rotating seal land <NUM>. This rotating seal land <NUM> may be a discrete, unitary annular body. For example, the rotating seal land <NUM> may be mounted to a shaft of the rotating structure <NUM>. Alternatively, the rotating seal land <NUM> may be configured with another component / portion of the rotating structure <NUM>. For example, the rotating seal land <NUM> may be an integral part of a shaft of the rotating structure <NUM>, or another component mounted to the shaft.

The rotating seal land <NUM> of <FIG> has an outer seal land surface <NUM>. This outer seal land surface <NUM> may be substantially cylindrical. The outer seal land surface <NUM> extends circumferentially about (e.g., completely around) and faces away from the axial centerline <NUM>. The outer seal land surface <NUM> is configured to face towards and may be axially aligned with the seal carrier inner surface <NUM>. While <FIG> illustrates the outer seal land surface <NUM> and the seal carrier inner surface <NUM> with approximately equal axial lengths along the axial centerline <NUM>, the outer seal land surface <NUM> may alternatively be longer or shorter than the seal carrier inner surface <NUM> in other embodiments.

The seal assembly <NUM> includes a primary seal device <NUM> and one or more secondary seal devices 40A and 40B (generally referred to as "<NUM>"); e.g., free floating seal plates. The seal assembly <NUM> also includes one or more additional components for positioning, supporting and/or mounting one or more of the seal devices <NUM> and <NUM> with the stationary structure <NUM>. The seal assembly <NUM> of <FIG>, for example, includes a first ring structure <NUM> configured for positioning, supporting and/or mounting the secondary seal devices <NUM> relative to the primary seal device <NUM>. The one or more secondary seal devices <NUM> and the first ring structure <NUM> may collectively provide a secondary seal assembly <NUM>. The first ring structure <NUM> may also be configured for axially positioning and/or supporting an axial first side surface <NUM> of the primary seal device <NUM> relative to the stationary structure <NUM>.

The seal assembly <NUM> of <FIG> also includes a second ring structure <NUM> (e.g., a scalloped support ring / plate) configured for axially positioning and/or supporting an axial second side surface <NUM> of the primary seal device <NUM> relative to the stationary structure <NUM>. However, the second ring structure <NUM> may be omitted where, for example, the second side surface <NUM> of the primary seal device <NUM> is abutted against another component / portion of the stationary structure <NUM> (e.g., an annular or castellated shoulder) or otherwise axially positioned / secured with the stationary structure <NUM>; e.g., see <FIG>.

Referring to <FIG>, the primary seal device <NUM> is configured as an annular seal device such as, but not limited to, a non-contact hydrostatic seal device. The primary seal device <NUM> includes a seal base <NUM>, a plurality of seal shoes <NUM>, and a plurality of spring elements <NUM> (see also <FIG>).

The seal base <NUM> may be configured as an annular full hoop body. The seal base <NUM> of <FIG> extends circumferentially about (e.g., completely around) the axial centerline <NUM>. The seal base <NUM> is configured to extend circumferentially around and thereby circumscribe and support the seal shoes <NUM> as well as the spring elements <NUM>. Referring to <FIG>, the seal base <NUM> extends axially along the axial centerline <NUM> between and forms the axial first side surface <NUM> and the axial second side surface <NUM>. The seal base <NUM> extends radially between a seal base inner side <NUM> and a seal base outer side <NUM>. The seal base outer side <NUM> radially engages (e.g., is press fit against or otherwise contacts) the stationary structure <NUM> and its inner surface <NUM> as shown in <FIG>.

Referring to <FIG>, the seal shoes <NUM> may be configured as arcuate bodies and are arranged circumferentially around the axial centerline <NUM> in an annular array. Each seal shoe <NUM>, for example, is arranged circumferentially between and next to (e.g., in close proximity) a pair of adjacent circumferentially neighboring seal shoes <NUM>. The annular array of the seal shoes <NUM> extends circumferentially about (e.g., completely around) the axial centerline <NUM>, thereby forming an inner bore at an inner side <NUM> of the primary seal device <NUM>. As best seen in <FIG>, the inner bore is sized to receive the rotating seal land <NUM>, where the rotating structure <NUM> projects axially through (or into) the inner bore formed by the seal shoes <NUM>.

Referring to <FIG> and <FIG>, each of the seal shoes <NUM> extends radially from the inner side <NUM> of the primary seal device <NUM> to an outer side <NUM> of that seal shoe <NUM>. Each of the seal shoes <NUM> extends circumferentially about the axial centerline <NUM> between opposing circumferential first and second ends <NUM> and <NUM> of that seal shoe <NUM>. Referring to <FIG>, each of the seal shoes <NUM> extends axially along the axial centerline <NUM> between an axial first (e.g., upstream and/or high pressure) side <NUM> and an axial second (e.g., downstream and/or low pressure) side <NUM> of the seal shoe <NUM>. The axial seal shoe first side <NUM> may be an upstream and/or high pressure side relative, for example, to flow of leakage fluid across the primary seal device <NUM>. The axial seal shoe first side <NUM> is axially offset / displaced from the axial first side surface <NUM>. The axial seal shoe second side <NUM> may be a downstream and/or low pressure side relative, for example, to the flow of leakage fluid across the primary seal device <NUM>. The axial seal shoe second side <NUM> may be axially aligned with the axial second side surface <NUM>. The seal shoes <NUM> of the present disclosure, however, are not limited to such exemplary relationships.

Each of the seal shoes <NUM> includes a seal shoe base <NUM> and one or more seal shoe projections 76A-D (generally referred to as "<NUM>"); e.g., inner projections such as rails and/or teeth. Each seal shoe <NUM> also includes a seal shoe rib <NUM>.

The seal shoe base <NUM> of <FIG> includes an inner portion <NUM> and an outer portion <NUM>. The base inner portion <NUM> may be configured as a carrier for the one or more seal shoe projections <NUM> and the base outer portion <NUM>. The base outer portion <NUM> may be configured as a (e.g., non-rotating) seal land for the one or more secondary seal devices <NUM> (see <FIG>).

The base inner portion <NUM> includes one or more (e.g., arcuate) base outer surfaces 84A and 84B (generally referred to as "<NUM>") and one or more (e.g., arcuate) base inner surfaces 86A-D (generally referred to as "<NUM>"). The base inner portion <NUM> extends radially between the one or more base outer surfaces <NUM> and the one or more base inner surfaces <NUM>. Referring to <FIG> and <FIG>, the base inner portion <NUM> extends circumferentially about the axial centerline <NUM> between and to the circumferentially opposing seal shoe ends <NUM> and <NUM>. The base inner portion <NUM> includes a first end surface at the seal shoe first end <NUM> and a second end surface at the seal shoe second end <NUM>. Each of the end surfaces may be a flat planar surface. Each of the end surfaces, for example, may have a straight sectional geometry when viewed, for example, in a plane perpendicular to the axial centerline <NUM>; e.g., the plane of <FIG> or <FIG>. Referring to <FIG>, the base inner portion <NUM> extends axially between the seal shoe first side <NUM> and the seal shoe second side <NUM>.

Referring to <FIG>, the base outer portion <NUM> extends circumferentially about the axial centerline <NUM> between and to the opposing seal shoe ends <NUM> and <NUM>. Referring again to <FIG>, the base outer portion <NUM> is arranged at the seal shoe outer side <NUM>. The base outer portion <NUM> of <FIG>, for example, projects radially out from the base inner portion <NUM> and its outer surfaces <NUM> to an unsupported radial distal end <NUM> of the base outer portion <NUM>. This base outer portion radial distal end <NUM> is arranged at the seal shoe outer side <NUM>. The base outer portion <NUM> extends axially along the axial centerline <NUM> between opposing axial sides and associated arcuate, planar side surfaces <NUM> and <NUM> of the base outer portion <NUM>. The base outer portion first side surface <NUM> is axially displaced from the seal shoe first side <NUM> by a non-zero axial distance. The base outer portion second side surface <NUM> is axially displaced from the seal shoe second side <NUM> by a non-zero axial distance.

The base outer portion <NUM> may be generally axially aligned with and/or axially overlapped by the one or more seal shoe projections <NUM>. The base outer portion <NUM> of <FIG>, for example, is axially aligned with and is axially overlapped by the seal shoe projection 76B. The present disclosure, however, is not limited to such an exemplary arrangement. For example, in other embodiments, the base outer portion <NUM> may be axially aligned with any other one of the seal shoe projections <NUM> (e.g., 76A, 76C and/or 76D). In still other embodiments, the base outer portion <NUM> may be axially offset from the seal shoe projections <NUM>. The base outer portion <NUM>, for example, may be arranged axially upstream of (e.g., towards the side <NUM>) or axially downstream of (e.g., towards the side <NUM>) the one or more seal shoe projections <NUM>. In another example, the base outer portion <NUM> may be arranged axially between an adjacent / neighboring pair of seal shoe projections <NUM> (e.g., 76A and 76B, 76B and 76C, 76C and 76D).

The seal shoe projections <NUM> are arranged at discrete axial locations along the axial centerline <NUM> and the seal shoe base <NUM>. Each pair of axially adjacent / neighboring projections <NUM> may thereby be axially separated by an (e.g., arcuate) inter-projection gap. The seal shoe projections <NUM> of <FIG> are configured parallel to one another.

The seal shoe projections <NUM> may be arranged in a concentrated grouping <NUM>. This grouping <NUM> may be asymmetrically arranged axially along the axial centerline <NUM> between the axial seal shoe first side <NUM> and the axial seal shoe second side <NUM>. For example, an axial center <NUM> (e.g., midpoint) of the grouping <NUM> of the seal shoe projections <NUM> in <FIG> is arranged closer to the seal shoe first side <NUM> than the seal shoe second side <NUM>. The seal shoe projections <NUM> of the present disclosure, however, are not limited to the foregoing exemplary asymmetric configuration.

The seal shoe projections <NUM> are connected to (e.g., formed integral with or otherwise attached to) the seal shoe base <NUM> and its base inner portion <NUM>. Each of the seal shoe projections <NUM> projects radially inwards from the seal shoe base <NUM>, the base inner portion <NUM> and the base inner surfaces <NUM> to an unsupported distal projection end.

Each of the seal shoe projections <NUM> has a projection inner surface 98A-D (generally referred to as "<NUM>") at its unsupported distal projection end. One or more or each of the projection inner surfaces <NUM> may also be at (e.g., on, adjacent or proximate) the inner side <NUM> of the primary seal device <NUM>. Each projection inner surface <NUM> may be an arcuate surface. Each projection inner surface <NUM>, for example, may have an arcuate sectional geometry when viewed, for example, in a plane perpendicular to the axial centerline <NUM>; e.g., the plane of <FIG> or <FIG>. The projection inner surfaces <NUM> are configured to be arranged in close proximity with (but not touch) and thereby sealingly mate with the outer seal land surface <NUM> in a non-contact manner (see <FIG>), where the rotating structure <NUM> projects axially through (or into) the inner bore formed by the seal shoes <NUM>.

Each of the seal shoe projections <NUM> extends axially between opposing projection end surfaces (e.g., <NUM> and <NUM>). Each of these end surfaces (e.g., <NUM> and <NUM>) extends radially between and may be contiguous with a respective one of the projection inner surfaces <NUM> (e.g., 98D in <FIG>) and a respective one of the base inner surfaces <NUM> (e.g., 86A and 86B in <FIG>).

Each of the seal shoe projections <NUM> of <FIG> has the same radial height. In other embodiments, however, one or more of the seal shoe projections <NUM> may have a different radial height than at least another one of the seal shoe projections <NUM>; e.g., see <FIG>.

Referring to <FIG>, the seal shoe rib <NUM> is configured to form a seal land surface <NUM> (e.g., a crowned surface) for the base outer portion <NUM>; e.g., the seal land. More particularly, the seal shoe rib <NUM> is configured to form a controlled contact surface for the one or more secondary seal devices <NUM> (see <FIG>) as described below in further detail.

Referring to <FIG>, the seal shoe rib <NUM> and its seal land surface <NUM> extend circumferentially about the axial centerline <NUM> between and to the opposing seal shoe ends <NUM> and <NUM>. Referring to <FIG>, the seal shoe rib <NUM> and its seal land surface <NUM> extend radially between opposing radial sides <NUM> and <NUM> of the seal shoe rib <NUM>. The outer rib side <NUM> may be arranged at (e.g., on, adjacent or proximate) the seal shoe outer side <NUM>. The inner rib side <NUM> may be radially displaced from the seal base outer surface 84A by a non-zero radial distance. Thus, the seal shoe rib <NUM> is radially outboard of and forms an outer radial peripheral boundary of an arcuate channel <NUM>. This channel <NUM> extends axially along the axial centerline <NUM> into the seal shoe <NUM> to the surface <NUM>, and extends radially between the surfaces <NUM> and 84B. The seal shoe rib <NUM> of <FIG> also projects axially outward from the seal shoe base <NUM> and its base outer portion <NUM> to the seal land surface <NUM> and an unsupported, axial distal end <NUM> of that seal shoe rib <NUM>.

The seal shoe rib <NUM> and the seal land surface <NUM> of <FIG> are each configured with a crowned sectional geometry. The seal land surface <NUM> of <FIG>, for example, is configured with a curved (e.g., arcuate, semi-circular, splined and/or otherwise rounded) sectional geometry when viewed, for example, in a plane coincident with and/or parallel with the axial centerline <NUM>; e.g., plane of <FIG>. The present disclosure, however, is not limited to such an exemplary curved or even crowned sectional geometry as described below in further detail.

The seal land surfaces <NUM> of the seal shoes <NUM> are configured to collectively form a generally annular, but circumferentially segmented, seal land surface. More particularly, when the seal shoes <NUM> are arranged in the array (see <FIG>), the seal land surfaces <NUM> collectively form the annular seal land surface. Referring to <FIG>, this annular seal land surface and, thus, the surfaces <NUM> are configured to be sealingly engaged (e.g., axially contacted) the one or more secondary seal devices <NUM> as described below in further detail.

Referring to <FIG>, the spring elements <NUM> are arranged circumferentially about the axial centerline <NUM> in an annular array. Referring to <FIG> and <FIG>, the spring elements <NUM> are also arranged (e.g., radially) between the seal shoes <NUM> and the seal base <NUM>. Each of the spring elements <NUM> is configured to moveably and resiliently connect a respective one of the seal shoes <NUM> to the seal base <NUM>.

The spring element <NUM> of <FIG> includes first and second mounts <NUM> and <NUM> (e.g., inner and outer radial fingers / projections) and one or more spring beams 118A and 118B (generally referred to as "<NUM>"). The first mount <NUM> may be directly or indirectly connected to (e.g., formed integral with or otherwise attached to) a respective one of the seal shoes <NUM> at (e.g., on, adjacent or proximate) the seal shoe first end <NUM>, where the opposing seal shoe second end <NUM> is free floating (e.g., the seal shoe is cantilevered from the first mount <NUM>). The first mount <NUM> projects radially outward from the seal shoe base <NUM>.

The second mount <NUM> may be directly or indirectly connected to the seal base <NUM>, and is generally circumferentially aligned with or near the seal shoe second end <NUM>. The second mount <NUM> is therefore disposed a non-zero circumferential distance from the first mount <NUM>. The second mount <NUM> projects radially inward from the seal base <NUM>.

The spring beams <NUM> are configured as resilient, biasing members of the primary seal device <NUM>. The spring beams <NUM> of <FIG>, for example, are configured as cantilevered-leaf springs. These spring beams <NUM> may be radially stacked and spaced apart from one another so as to form a four bar linkage with the first mount <NUM> and the second mount <NUM>. More particularly, each of the spring beams <NUM> may be directly or indirectly connected to the first mount <NUM> and the second mount <NUM>. Each of the spring beams <NUM> extends laterally (e.g., circumferentially or tangentially) between and to the first mount <NUM> and the second mount <NUM>. The spring beams <NUM> of <FIG> may thereby laterally overlap a major circumferential portion (e.g., ~<NUM>-<NUM>%) of the respective seal shoe <NUM>.

During operation of the primary seal device <NUM> of <FIG>, rotation of the rotating structure <NUM> may develop aerodynamic forces and apply a fluid pressure to the seal shoes <NUM> causing each seal shoe <NUM> to respectively move radially up and down relative to the outer seal land surface <NUM>. The fluid velocity may increase as a gap between a respective seal shoe <NUM> and the outer seal land surface <NUM> increases, thus reducing pressure in the gap and drawing the seal shoe <NUM> radially inwardly toward the outer seal land surface <NUM>. As the gap closes, the velocity may decrease and the pressure may increase within the gap, thus, forcing the seal shoe <NUM> radially outwardly from the outer seal land surface <NUM>. The respective spring element <NUM> and its spring beams <NUM> may deflect and move with the seal shoe <NUM> to enable provision of a primary seal of the gap between the outer seal land surface <NUM> and the seal shoe projections <NUM> within predetermined design tolerances.

While the primary seal device <NUM> described above is operable to generally seal the annular gap between the stationary structure <NUM> and the rotating structure <NUM>, the fluid (e.g., gas) may still flow axially through passages 120A-C (generally referred to as "<NUM>") defined by radial air gaps between the elements. The secondary seal assembly <NUM> and its one or more secondary seal devices <NUM> therefore are provided to seal off these passages <NUM> and, thereby, further and more completely seal the annular gap.

Referring to <FIG>, each of the secondary seal devices <NUM> may be configured as an annular seal plate such as, but not limited to, a split ring seal element. Each secondary seal device <NUM> (e.g., seal plate), for example, may be configured as (e.g., only include) or otherwise include a monolithic, unitary body that extends at least substantially (e.g., more than <NUM>, <NUM>, <NUM> degrees) around the axial centerline <NUM>. The secondary seal device of <FIG>, for example, extends substantially around the axial centerline <NUM> between opposing circumferential ends <NUM> and <NUM>, which ends <NUM> and <NUM> are disposed next to one another thereby forming a slit / cut <NUM> through that secondary seal device <NUM>. The secondary seal device <NUM> of <FIG> extends radially between opposing radial sides <NUM> and <NUM>. The secondary seal device <NUM> of <FIG> extends axially along the axial centerline <NUM> between opposing (e.g., planar or conical) annular side surfaces <NUM> and <NUM>. The present disclosure, however, is not limited to the foregoing exemplary seal plate configuration. For example, in other embodiments, one or more or each secondary seal device may be configured as a full-hoop body seal plate.

Referring still to <FIG>, one or more or each secondary seal device <NUM> is configured such that a ratio of its axial thickness <NUM> (e.g., a distance between the side surfaces <NUM> and <NUM>) to radial height <NUM> (e.g., average sectional diameter) is relatively small. The ratio of the radial height <NUM> to the axial thickness <NUM>, for example, may be greater than <NUM>:<NUM> and/or less than <NUM>:<NUM>. The ratio of the radial height <NUM> to the axial thickness <NUM>, for example, may be between <NUM>:<NUM> and <NUM>:<NUM>; e.g., in some embodiments between <NUM>:<NUM> and <NUM>:<NUM>; in some embodiments between <NUM>:<NUM> and <NUM>:<NUM>; in some embodiments between <NUM>:<NUM> and <NUM>: <NUM>; or in some embodiments between <NUM>:<NUM> and <NUM>:<NUM>. For example, the radial height <NUM> may be twenty inches, the axial thickness <NUM> may be <NUM> inches and the ratio may be about <NUM>,<NUM>:<NUM>. In another example, the radial height <NUM> may be forty inches, the axial thickness <NUM> may be <NUM> inches and the ratio may be about <NUM>:<NUM>. In still another example, the radial height <NUM> may be five inches, the axial thickness <NUM> may be <NUM> inches and the ratio may be about <NUM>:<NUM>. Each secondary seal devices <NUM> may thereby be torsionally flexible. The present disclosure, however, is not limited to the foregoing exemplary dimensional relationships.

The secondary seal devices <NUM> (e.g., seal plates) of <FIG> are arranged together in an axial stack. In this stack, each of the secondary seal devices <NUM> axially engages (e.g., contacts) another adjacent one of the secondary seal devices <NUM>. Note, the slit / cut <NUM> (not visible in <FIG>) in one of the secondary seal devices <NUM> may be clocked circumferentially about the axial centerline <NUM> from the slit / cut <NUM> in the other one of the secondary seal devices <NUM> such that each slit / cut <NUM> is covered and, thus, sealed by the adjacent secondary seal device <NUM>.

The stack of the secondary seal devices <NUM> is arranged with the first ring structure <NUM>. More particularly, the stack of the secondary seal devices <NUM> project radially, in a radially outward direction, into an annular channel <NUM> in the first ring structure <NUM>. Note, each of the secondary seal devices <NUM> may be operable to freely float within the annular channel <NUM>. For example, the rotational equipment assembly <NUM> may not include any fasteners (e.g., pins, bolts, screws, etc.) that fix or otherwise constrain movement of one or more or any of the secondary seal devices <NUM> relative to a stationary support structure <NUM> (e.g., a combination of the components <NUM> and <NUM>) and/or relative to one, some or any of the seal shoes <NUM>. No fasteners, for example, may be included that engage (e.g., contact) one or more or any of the secondary seal devices <NUM>. In another example, the rotational equipment assembly <NUM> may not include any biasing elements (e.g., spring elements, etc.) that constrain movement of one or more or any of the secondary seal devices <NUM> relative to the stationary support structure <NUM> and/or relative to one, some or any of the seal shoes <NUM>. No biasing elements, for example, may be included that engage (e.g., contact) one or more or any of the secondary seal devices <NUM>. With such a free floating configuration, each secondary seal device <NUM> (or the devices <NUM> collectively in the stack) may move within the annular channel <NUM> based on a pressure differential axially thereacross without, for example, any other outside influences.

The stack of the secondary seal devices <NUM> is operable to axially engage (e.g., contact) and form a seal between (a) the seal land surface <NUM> of one or more or each seal shoe <NUM> and (b) an annular seal land surface <NUM> of the stationary support structure <NUM>. The stack of the secondary seal devices <NUM> is thereby operable to seal an annular gap between the seal shoe(s) <NUM> and the stationary support structure <NUM> and, more particularly, the first ring structure <NUM>. It is worth noting, the torsional flexibility of the secondary seal devices <NUM> enables those secondary seal devices <NUM> to deform and maintain engagement (e.g., contact) with each seal land surface <NUM>, <NUM>. Each secondary seal device <NUM>, for example, may twist, bend and/or otherwise deform so as to maintain full engagement (e.g., contact) with each seal land surface <NUM>, <NUM>.

The annular seal land surface <NUM> may have a similar configuration (e.g., sectional geometry) as each of the seal land surfaces <NUM>. The annular seal land surface <NUM>, for example, may be formed by an annular rib <NUM> of the first ring structure <NUM>. This annular rib <NUM> and the annular seal land surface <NUM> of <FIG> are each configured with a crowned sectional geometry. The annular seal land surface <NUM> of <FIG>, for example, is configured with a curved (e.g., arcuate, semi-circular, splined and/or otherwise rounded) sectional geometry when viewed, for example, in a plane coincident with and/or parallel with the axial centerline <NUM>; e.g., plane of <FIG>. The present disclosure, however, is not limited to such an exemplary curved or even crowned sectional geometry as described below in further detail.

Referring to <FIG>, under ideal conditions as well as when the rotational equipment is non-operation, the seal land surfaces <NUM> and <NUM> may be axially aligned with one another. This alignment enables the stack of the secondary seal devices <NUM> to slide radially against, but maintain a seal engagement with, one or more or each of the seal shoe ribs <NUM> and their seal land surfaces <NUM> and/or the rib <NUM> and its seal land surface <NUM> as the seal shoes <NUM> move radially relative to the outer seal land surface <NUM> (see <FIG>) as described above. However, referring to <FIG>, the seal land surfaces <NUM> and <NUM> may become axially misaligned due to vibrations within the rotational equipment, pressure differential fluctuations across the seal assembly <NUM> and/or thermally induced movement of one or more components of the rotational equipment assembly <NUM>. The provision and configuration of the seal land surfaces <NUM> and/or <NUM>, however, enables the seal assembly <NUM> to accommodate such axial misalignment. Furthermore, as discussed above, the torsional flexibility of the secondary seal devices <NUM> enables the secondary seal devices <NUM> to deform and maintain engagement (e.g., contact) with each seal land surface <NUM>, <NUM>. For example, by providing each seal land surface <NUM>, <NUM> with a crown, the stack of secondary seal devices <NUM> may roll along the seal land surfaces <NUM> and <NUM> and thereby maintain sealing engagement with the ribs <NUM> and <NUM>. Furthermore, the crown of <FIG> may also enable the secondary seal devices <NUM> to pivot about and/or slide along the seal land surfaces <NUM> and <NUM> with relatively low resistance. This in turn may enable maintenance of contact points <NUM> and <NUM> between the elements <NUM> and <NUM>, <NUM> and <NUM>/<NUM> during axial shifting of the seal shoe(s) <NUM> relative to the stationary support structure <NUM>.

Referring to <FIG>, the first ring structure <NUM> may include a secondary seal device support ring <NUM> and a retention ring <NUM>. The support ring <NUM> is configured with an (e.g., monolithic, unitary) annular full hoop body, which extends circumferentially about (e.g., completely around) the axial centerline <NUM>.

The support ring <NUM> of <FIG> includes the annular rib <NUM> and its seal land surface <NUM>. The support ring rib <NUM>, for example, projects axially out from a base <NUM> of the support ring <NUM> to the seal land surface <NUM> and an unsupported distal end <NUM> of the support ring rib <NUM>. The support ring rib <NUM> and its seal land surface <NUM> extend radially between opposing radial sides <NUM> and <NUM> of the support ring rib <NUM>. The inner rib side <NUM> may be arranged at (e.g., on, adjacent or proximate) an inner side of the support ring <NUM>. The outer rib side <NUM> may be radially displaced from an end surface <NUM> of the annular channel <NUM> by a non-zero radial distance. Thus, the support ring rib <NUM> is radially inboard of and forms an inner radial peripheral boundary of an arcuate channel / groove <NUM> adjacent the arcuate channel <NUM>. The support ring rib <NUM> may also extend (e.g., uninterrupted) circumferentially about (e.g., completely around) the axial centerline <NUM>.

The retention ring <NUM> is configured with an annular full hoop body, which extends circumferentially about (e.g., completely around) the axial centerline <NUM>. The retention ring <NUM> is disposed axially adjacent and may be engaged with (e.g., axially contact, abut against) the support ring <NUM>. The stack of the secondary seal devices <NUM> may thereby be captured within the annular channel <NUM> formed between the rings <NUM> and <NUM>.

The seal land surfaces <NUM> and <NUM> are described above as having curved sectional geometries. However, in other embodiments, one or more or each of the seal land surfaces <NUM> and/or <NUM> and, thus, its associated rib <NUM>, <NUM> may have a non-curved or not completely curved sectional geometry. For example, referring to <FIG>, one or more or each of the seal land surfaces <NUM> and/or <NUM> and, thus, its associated rib <NUM>, <NUM> may have a rectangular sectional geometry with a flat planar surface <NUM> for at least a portion or an entirety of the seal land surface <NUM>, <NUM>. One or more or each corner <NUM> of the rib <NUM>, <NUM> may be relatively sharp as shown, for example, in <FIG>. One or more or each corner <NUM> of the rib <NUM>, <NUM> may alternatively be relatively blunt (e.g., rounded, chamfered, etc.) as shown, for example, in <FIG>. In still another example, referring to <FIG>, one or more or each of the seal land surfaces <NUM> and/or <NUM> and, thus, its associated rib <NUM>, <NUM> may have a non-rectangular polygonal sectional geometry (e.g., a pointed sectional geometry, a triangular sectional geometry) and/or extend to a point or tip <NUM>. The seal land surfaces <NUM> and <NUM> and the ribs <NUM> and <NUM>, however, are not limited to the foregoing exemplary sectional geometries.

In some embodiments, referring to <FIG>, a radial height <NUM> of one or some or each of the secondary seal devices <NUM> may be sized to be greater than a radial distance between the ribs <NUM> and <NUM> and, more particularly, a radial distance <NUM> between peaks of the ribs <NUM> and <NUM>. Note, since the seal shoes <NUM> may move radially up and down relative to the stationary support structure <NUM> during operation, the radial distance <NUM> is typically measured for conditions when the peaks of the ribs <NUM> and <NUM> are farthest apart from one another. With such this configuration, the secondary seal devices <NUM> may (e.g., always) maintain sealing engagement with the seal land surfaces <NUM> and <NUM>.

In some embodiments, the channel end surface <NUM> may be configured as a radial outer stop / limiter for radial outward movement of the secondary seal devices <NUM>.

In some embodiments, the seal shoe outer surface 84B may be configured as a radial inner stop / limiter for radial inward movement of the secondary seal devices <NUM>.

Referring to <FIG>, in accordance with the invention the inner and/or the outer ribs (e.g., the ribs <NUM> and <NUM> in <FIG>) are configured with at least one of the secondary seal devices <NUM> (one shown in <FIG>). The secondary seal device <NUM> of <FIG> is configured with an annular inner rib <NUM>' (e.g., corresponding to the rib <NUM> in <FIG>) and/or an annular outer rib <NUM>' (e.g., corresponding to the rib <NUM> in <FIG>). The inner rib <NUM>' is arranged at (e.g., on, adjacent or proximate) or towards the secondary seal device inner end <NUM>. The outer rib <NUM>' is arranged at (e.g., on, adjacent or proximate) or towards the secondary seal device outer end <NUM>. Each rib <NUM>', <NUM>' projects axially along the axial centerline <NUM> out from a base <NUM> of the secondary seal device <NUM> to its a respective unsupported distal end in a similar manner as described above with reference to the ribs <NUM> and <NUM> (e.g., see <FIG>). Each of the ribs <NUM>', <NUM>' may thereby sealingly engage a respective one of the seal land surfaces <NUM>', <NUM>' in a similar manner as described above and, thus, is operable to accommodate axial misalignment between the seal surfaces.

In some embodiments, one or more or each of the seal land surfaces <NUM> and/or <NUM> may be partially or completely covered with a protective coating. This protective coating may be a wear coating. The protective coating, for example, may be configured to reduce or prevent (e.g., rubbing) wear of the elements <NUM>, <NUM> and/or <NUM>.

While the seal land surfaces <NUM> and <NUM> are shown in the drawings at certain radial positions, the present disclosure is not limited to configuring those surfaces <NUM> and <NUM> thereat. One or more or each of the seal land surfaces <NUM> and/or <NUM>, for example, may alternatively be positioned further radially outward or further radially inward to, for example, optimize the delta pressure load distribution across the secondary seal devices <NUM>. In this manner, the radial positions of the seal land surfaces <NUM> and <NUM> may be tailored to reduce or prevent "see-saw" loading / movement of the secondary seal devices <NUM>.

In some embodiments, as best seen in <FIG> and <FIG>, the primary seal device <NUM> and some or all of its elements (e.g., <NUM>, <NUM> and <NUM>) may be configured as a monolithic body. However, the present disclosure is not limited to such a primary seal device construction.

As described above, the rotational equipment assembly <NUM> of the present disclosure may be configured with various different types and configurations of rotational equipment. <FIG> illustrates one such type and configuration of the rotational equipment - a geared turbofan gas turbine engine <NUM>. Such a turbine engine includes various stationary structures (e.g., bearing supports, hubs, cases, etc.) as well as various rotors (e.g., rotor disks, shafts, shaft assemblies, etc.) as described below, where the stationary structure <NUM> and the rotating structure <NUM> of <FIG> can respectively be configured as anyone of the foregoing structures in the turbine engine <NUM> of <FIG>, or other structures not mentioned herein.

The turbine engine <NUM> of <FIG> extends along the axial centerline <NUM> between an upstream airflow inlet <NUM> and a downstream airflow exhaust <NUM>. The turbine engine <NUM> includes a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. The compressor section <NUM> includes a low pressure compressor (LPC) section 175A and a high pressure compressor (HPC) section 175B. The turbine section <NUM> includes a high pressure turbine (HPT) section 177A and a low pressure turbine (LPT) section 177B.

The engine sections <NUM>-177B are arranged sequentially along the axial centerline <NUM> within an engine housing <NUM>. This engine housing <NUM> includes an inner case <NUM> (e.g., a core case) and an outer case <NUM> (e.g., a fan case). The inner case <NUM> may house one or more of the engine sections 175A-177B; e.g., an engine core. The outer case <NUM> may house at least the fan section <NUM>.

Each of the engine sections <NUM>, 175A, 175B, 177A and 177B includes a respective rotor <NUM>-<NUM>. Each of these rotors <NUM>-<NUM> includes a plurality of rotor blades arranged circumferentially around and connected to one or more respective rotor disks. The rotor blades, for example, may be formed integral with or mechanically fastened, welded, brazed, adhered and/or otherwise attached to the respective rotor disk(s).

The fan rotor <NUM> is connected to a gear train <NUM>, for example, through a fan shaft <NUM>. The gear train <NUM> and the LPC rotor <NUM> are connected to and driven by the LPT rotor <NUM> through a low speed shaft <NUM>. The HPC rotor <NUM> is connected to and driven by the HPT rotor <NUM> through a high speed shaft <NUM>. The shafts <NUM>-<NUM> are rotatably supported by a plurality of bearings <NUM>. Each of these bearings <NUM> is connected to the engine housing <NUM> by at least one stationary structure such as, for example, an annular support strut.

During operation, air enters the turbine engine <NUM> through the airflow inlet <NUM>. This air is directed through the fan section <NUM> and into a core gas path <NUM> and a bypass gas path <NUM>. The core gas path <NUM> extends sequentially through the engine sections 175A-177B. The air within the core gas path <NUM> may be referred to as "core air". The bypass gas path <NUM> extends through a bypass duct, which bypasses the engine core. The air within the bypass gas path <NUM> may be referred to as "bypass air".

The rotational equipment assembly <NUM> may be included in various turbine engines other than the one described above as well as in other types of rotational equipment. The rotational equipment assembly <NUM>, for example, may be included in a geared turbine engine where a gear train connects one or more shafts to one or more rotors in a fan section, a compressor section and/or any other engine section. Alternatively, the rotational equipment assembly <NUM> may be included in a turbine engine configured without a gear train. The rotational equipment assembly <NUM> may be included in a geared or non-geared turbine engine configured with a single spool, with two spools (e.g., see <FIG>), or with more than two spools. The turbine engine may be configured as a turbofan engine, a turbojet engine, a propfan engine, a pusher fan engine or any other type of turbine engine. The present disclosure therefore is not limited to any particular types or configurations of turbine engines or rotational equipment.

Claim 1:
An assembly (<NUM>) for rotational equipment, comprising:
a plurality of seal shoes (<NUM>) arranged circumferentially around an axial centerline (<NUM>) in an annular array, the plurality of seal shoes (<NUM>) comprising a first seal shoe (<NUM>);
a stationary support structure (<NUM>) extending circumferentially around the plurality of seal shoes (<NUM>);
a plurality of spring elements (<NUM>) comprising a first spring element (<NUM>), the first spring element (<NUM>) connecting and extending between the first seal shoe (<NUM>) and the stationary support structure (<NUM>); and
a seal plate (<NUM>) configured to seal a gap between the stationary support structure (<NUM>) and the plurality of seal shoes (<NUM>), characterised in that the seal plate (<NUM>) is
configured with an annular seal plate rib (<NUM>', <NUM>') configured to axially contact and slide radially along one of the first seal shoe (<NUM>) and the stationary support structure (<NUM>).