Patent Description:
Gas turbine engines can include a fan for propulsion air and to cool components. The fan also delivers air into a core engine where it is compressed. The compressed air is then delivered into a combustion section, where it is mixed with fuel and ignited. The combustion gas expands downstream over and drives turbine blades. Static vanes are positioned adjacent to the turbine blades to control the flow of the products of combustion.

The gas turbine engine may include composite components formed from by ply layers. The ply layers may be arranged to define one or more voids or cavities. Fillers may be placed in the cavities and may be dimensioned to have a complementary geometry with the adjacent ply layers.

<CIT> discloses a prior art platform for a gas turbine engine with the features of the preamble of claim <NUM>.

<CIT> discloses a prior art composite filler.

<CIT> discloses a prior art method of using a laminated composite radius filler.

<CIT> discloses prior art composite radius filler and methods of forming the same.

<CIT> discloses a prior art platform for an airfoil of a gas turbine engine.

<CIT> discloses a prior art fan blade platform with stiffening feature, and a corresponding assembly and method.

According to a first aspect of the present invention, there is provided a platform for a gas turbine engine as set forth in claim <NUM>. According to a further aspect of the present invention, there is provided an assembly as set forth in claim <NUM>. According to a further aspect of the present invention, there is provided a gas turbine engine as set forth in claim <NUM>.

Particular embodiments are set forth in dependent claims <NUM> to <NUM> and <NUM>.

The various features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description.

The fan section <NUM> drives air along a bypass flow path B in a bypass duct defined within a housing <NUM>, such as a fan case or nacelle, and also drives air along a core flow path C for compression and communication into the combustor section <NUM> then expansion through the turbine section <NUM>.

It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

"Low corrected fan tip speed" is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R) / (<NUM> °R)]<NUM> (where T°R = TK x <NUM>/<NUM>).

<FIG> illustrates a rotor assembly <NUM> for the gas turbine engine <NUM>. The rotor assembly <NUM> can be incorporated as the fan <NUM> into the fan section <NUM> of <FIG>, for example.

The rotor assembly <NUM> includes a rotatable hub <NUM> mechanically attached or otherwise mounted to a fan shaft <NUM>. The rotatable hub <NUM> includes a main body 62A that extends along the longitudinal axis E. The longitudinal axis E can be parallel to or collinear with the engine longitudinal axis A of <FIG>. The fan shaft <NUM> and hub <NUM> are rotatable about the longitudinal axis E. The fan shaft <NUM> can be rotatably coupled to the low pressure turbine <NUM>, as illustrated in <FIG>, for example.

The rotor assembly <NUM> includes an array of airfoils <NUM> circumferentially distributed about and carried by an outer periphery 62B of the rotatable hub <NUM>. Each airfoil <NUM> includes an airfoil section 66A extending from a root section 66B. The hub <NUM> includes a plurality of retention slots 62C that extend inwardly from the outer periphery 62B of the hub <NUM>. Each root section 66B is slideably received in a respective one of the retention slots 62C to mechanically attach or otherwise secure the airfoil <NUM> to the hub <NUM>. The root section 66B can have a dovetail geometry that mates with a contour of the respective retention slot 62C (also shown in dashed lines in <FIG> for illustrative purposes).

The rotor assembly <NUM> includes an array of platforms <NUM>. In the illustrative example of <FIG>, the platforms <NUM> are separate and distinct from the airfoils <NUM>. In other examples, the platforms <NUM> are integrally formed with one or more of the airfoils <NUM>. The platforms <NUM> are circumferentially distributed about the outer periphery 62B of the hub <NUM>. The platforms <NUM> are situated between and abut against adjacent pairs of airfoils <NUM> to define an inner boundary of a gas path along the rotor assembly <NUM>, as illustrated in <FIG>. The platforms <NUM> are dimensioned to support the adjacent airfoils <NUM> and limit or otherwise oppose circumferential movement of the airfoils <NUM> during engine operation. The rotor assembly <NUM> includes a plurality of retention pins <NUM>. Each platform <NUM> can be mechanically attached or otherwise secured to the hub <NUM> with a respective one of the retention pins <NUM>.

Referring to <FIG>, with continuing reference to <FIG>, one of the airfoils <NUM> and platforms <NUM> mounted to the hub <NUM> is shown for illustrative purposes. The airfoil section 66A extends between a leading edge LE and a trailing edge TE in a chordwise direction X, and extends in a radial direction R between the root section 66B and a tip portion 66C (<FIG>) to provide an aerodynamic surface. The tip portion 66C defines a terminal end or radially outermost extent of the airfoil <NUM> to establish a clearance gap with fan case <NUM> (<FIG>). The airfoil section 66A defines a pressure side P (<FIG>) and a suction side S separated in a thickness direction T.

Each platform <NUM> includes a platform body 70A including a plurality of axially spaced apart flanges 70B. The platform body 70A includes a platform base 70E dimensioned to abut against and extend along the airfoil section 66A of adjacent airfoils <NUM>. The platform base 70E defines an aerodynamic contour and gas path surface between the adjacent airfoils <NUM>. The platform body 70A defines one or more slots 70C between the flanges 70B. Each slot 70C is dimensioned to receive a respective flange 62D of the hub <NUM>. Each flange 62D can have an annular geometry that extends circumferentially about the longitudinal axis E, as illustrated by <FIG>.

Each platform <NUM> is dimensioned to receive at least one retention pin <NUM> (shown in dashed lines in <FIG>) to mechanically attach and mount the platform <NUM> to the hub <NUM>. Each of the flanges 70B can include a respective platform bushing <NUM>. The bushings <NUM> can be axially aligned and dimensioned to slideably receive a common one of the retention pins <NUM>, as illustrated by <FIG>. Each retention pin <NUM> is dimensioned to extend through the flanges 62D of the hub <NUM> and through the flanges 70B of the respective platform <NUM> to mechanically attach the platform <NUM> to the hub <NUM>.

The rotor assembly <NUM> includes composite platforms and can include composite airfoils <NUM>. Example composite materials include thermoplastics and ceramics such as ceramic matrix composites (CMC) having one or more ply layers or fibers in a resin matrix.

The rotor assembly <NUM> includes one or more internal cavities defined in the composite platforms. The composite platforms are constructed from a layup of plies, for example. Contouring of the component may cause the plies to define the internal cavities. The internal cavities are at least partially filled or occupied with material utilizing the techniques disclosed herein to improve fabrication and structural support of the component.

Referring to <FIG>, with continuing reference to <FIG>, a perspective view of one of the platforms <NUM> is shown. The platform <NUM> is a composite structure including a plurality of composite layers L shaped to a predetermined geometry. The composite layers L define the platform body 70A and flanges 70B.

Various materials can be utilized to construct the composite layers L. Example materials include one or more plies of uni-tape, braided yarns, fabric, and two-dimensional or three-dimensional woven fibers, for example. It should be appreciated that uni-tape plies include a plurality of fibers oriented in the same direction ("unidirectional), and fabric includes woven or interlaced fibers, each known in the art. Example fiber constructions include carbon fibers, fiberglass, Kevlar®, a ceramic such as Nextel™, a polyethylene such as Spectra®, and/or a combination of fibers.

The composite layers L include first and second sets of ply layers L-<NUM>, L-<NUM> that define an outer periphery 70P of the platform <NUM>. The first set of ply layers L-<NUM> define the platform base 70E. The second set of ply layers L-<NUM> extend from the first set of ply layers L-<NUM> to define the flanges 70B. The composite layers L are arranged such that the flanges 70B form respective arches that extend outwardly from the platform base 70E to define respective hollow cavities 70F.

The composite layers L include a third set of ply layers L-<NUM> that abut against the first and second sets of ply layers L-<NUM>, L-<NUM> to surround the hollow cavities 70F.

The hollow cavities 70F can be arranged to define portions of an elongated passage <NUM>. The passage <NUM> is at least partially surrounded by the third set of ply layers L-<NUM> and extends longitudinally between opposed end portions <NUM> of the platform body 70A and through each of the flanges 70B, as illustrated by <FIG> and <FIG>. Each composite layer L can include one or more sublayers LL, as illustrated by <FIG>.

The composite layers L can be dimensioned and formed to follow a contour of the platform <NUM>. At least some of the composite layers L are joined together to define one or more of the internal cavities 70D. At least some of the internal cavities 70D are bounded by the platform base 70E and are defined in the flanges 70B. Each cavity 70D is at least partially enclosed by adjacent composite layers L and can be provided with one or more openings to an exterior of the platform <NUM>.

Each platform <NUM> includes one or more fillers <NUM> received in a respective cavity 70D. The fillers <NUM> are dimensioned to complement a geometry of a respective one of the inner cavities 70D and serve to at least partially support the adjacent composite layers L during fabrication. The fillers <NUM> can also serve as structural members to support the composite layers L during engine operation.

In the illustrated example of <FIG>, the platform <NUM> includes first and second fillers <NUM>-<NUM>, <NUM>-<NUM> that extend along the platform base 70E. The platform <NUM> includes a plurality of fillers <NUM> that define portions of the flanges 70B, such as filler <NUM>-<NUM>. Filler <NUM>-<NUM> is dimensioned to extend along and outwardly from the platform base 70E to define at least one of the flanges 70B. <FIG> illustrates a perspective view of the fillers <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> for illustrative purposes. It should be appreciated that the specific geometry of each filler <NUM> can be dimensioned according to a geometry of the platform <NUM>.

Referring to <FIG>, with continuing reference to <FIG>, adjacent layers L can be arranged to define one or more contours of the platform <NUM>. For example, the layers L can curve inwardly and/or outwardly from adjacent layers L. The geometry of the layers L can cause a cross section or perimeter of the respective internal cavity 70D to taper, as illustrated by the internal cavities 70D associated with filler <NUM>-<NUM> at junctions J1, J2 and J3. Some of the layers L may be arranged to have relatively large turning radii along the respective contour such that the internal cavities 70D associated with fillers <NUM>-<NUM>, <NUM>-<NUM> have a generally deltoid or delta-shaped geometry formed by inner radii, for example. The fillers <NUM> can be utilized to maintain a geometry of the platform <NUM> during layup of the layers L, which can improve the structural capability and manufacturability of the layers L.

Various materials can be utilized for the fillers <NUM>. In the illustrative examples of <FIG>, the fillers <NUM>-<NUM> and <NUM>-<NUM> include a composite structure <NUM>-<NUM> and <NUM>-<NUM>, respectively, situated in internal cavities 70D adjacent the platform base 70E. In other examples, the fillers <NUM>-<NUM> and <NUM>-<NUM> are constructed from uni-tape plies, discontinuous chopped fibers in a resin matrix, preforms made of a bulk or sheet molding compound, and/or thermoplastics.

According to the invention, the filler <NUM>-<NUM> includes a stacked composite structure <NUM>-<NUM> situated in one of the internal cavities 70D spaced furthest from the platform base 70E and in the flanges 70B. The filler <NUM>-<NUM> is dimensioned to extend between surfaces of the composite layers L that bound the respective internal cavity 70D. The stacked composite structure <NUM>-<NUM> can provide structural support and rigidity to the adjacent layers L and distribute structural loads across portions of the platform <NUM>. The stacked structure <NUM>-<NUM> includes a multitude of layers formed from discontinuous material sheets that are bonded together by an adhesive or resin material. Because the stacked structure <NUM>-<NUM> is formed from separate layers, a bond line is formed between adjacent layers.

The filler <NUM>-<NUM> also includes an overwrap ply 76A that surrounds the stacked composite structure <NUM>-<NUM>. The overwrap ply 76A can be bonded to the stacked composite structure <NUM>-<NUM> with an adhesive or through resin. According to the invention, the overwrap ply 76A includes a single layer or ply of composite material that encloses or abuts lateral edges of each layer in the stacked composite structure <NUM>-<NUM> on a first side and one of the layers L on a second opposite side. Because the overwrap ply 76A is a single layer, it defines a butt joint with a discontinuity that forms an opening into the stacked composite structure <NUM>-<NUM>.

One feature of the overwrap ply 76A is reduced crack propagation through the filler <NUM>-<NUM>. In particular, if a crack formed between adjacent layers of the stacked composite structure <NUM>-<NUM>, the overwrap ply 76A would prevent the crack from reaching a surface of the filler <NUM>-<NUM> and therefore would improve the strength and longevity of the filler <NUM>-<NUM> as well as the platform <NUM>.

Furthermore, in the illustrated example of <FIG> and <FIG>, each of the fillers <NUM>-<NUM> in the flanges <NUM>-B includes a bushing <NUM>. The stacked composite structure <NUM>-<NUM> supports the bushing <NUM> such that the filler <NUM>-<NUM> serves to provide a structural load path between the bushing <NUM> and composite layers L.

Although the different examples have the specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations.

Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention.

Claim 1:
A platform (<NUM>) for a gas turbine engine (<NUM>) comprising:
a platform body (70A) defining one or more slots (70C) between a plurality of flanges (70B), the one or more slots (70C) dimensioned to receive a respective flange of a hub (<NUM>), and the platform body (70A) including a plurality of composite layers (L) that join together to define an internal cavity (70D); and
a filler (<NUM>) extending in the internal cavity (70D) between the plurality of composite layers (L) and including a stacked composite structure (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) having a multitude of composite layers,
characterized in that:
the multitude of composite layers in the stacked composite structure (<NUM>-<NUM>) are arranged in parallel planes; and
the multitude of composite layers in the stacked composite structure (<NUM>-<NUM>) are surrounded by an overwrap ply (76A),
the overwrap ply (76A) including a single layer defining a butt joint with a discontinuity in the overwrap ply (76A) to form an opening to the stacked composite structure (<NUM>-<NUM>).