Patent Description:
Gas turbine engines are known and typically include a fan delivering air into a bypass duct as bypass air and into a compressor as core air. The air is compressed and delivered into a combustor section where the air is mixed with fuel and ignited. Products of the combustion pass downstream over turbine rotors, which causes the turbine rotors to rotate.

Gas turbine engines require specific support stiffnesses and/or oil feed dampers to manage vibrations of rotating and static structures at specific operating speeds. In one configuration, a centering spring is used in combination with an oil damper that is positioned between a bearing outer race and a static engine structure. The oil damper comprises an oil squeeze film damper made from a plurality of segments that are mounted directly between the outer race and the engine static structure. The centering spring extends axially away from one end of the film damper to a distal end that is fixed to the static engine structure. While this configuration is effective at managing vibrations, a significant amount of axial space is consumed by the centering spring and damper. Additionally, the centering spring and damper are expensive and complicated to machine due to the large number of tightly controlled surfaces to manage stress and stiffness for a given amount of deflection. Curved beam dampers can also be used to dampen vibrations; however, this configuration is not conducive for providing an effective and reliable oil film damper in some applications.

<CIT> describes a bearing assembly for a gas turbine engine rotor including, an inner race, an outer race assembly, and a rolling element. The outer race assembly includes a body, a plurality of first springs attached to the body, and a plurality of second springs.

<CIT> describes a bearing assembly for a gas turbine engine rotor including a damper bearing configured to support the rotor, a bearing centering subassembly configured to position the damper bearing relative to the rotor, and a retainer.

<CIT> describes a ram air turbine power system with a deployable ram air turbine mounted in-line with a power supply unit such as an electrical generator and/or an hydraulic pump.

<CIT>, which was published after the priority date of the present application and so can only be considered for the assessment of novelty, describes unitary fan inlet case and bearing support structure for a gas turbine engine including an annular body having a radially inward ring connected to a radially outward ring via a plurality of struts.

From an aspect of the invention, there is provided a gas turbine engine component as claimed in claim <NUM>.

In another embodiment according to the previous embodiment, a fluid damper is spaced radially inward of the bearing housing and radially outward of the outer race.

In another embodiment according to any of the previous embodiments, the first mounting flange is formed at one end of the cylindrical wall and the second mounting flange is formed at an opposite end of the cylindrical wall.

In another embodiment according to any of the previous embodiments, the first mounting flange extends radially inward and the second mounting flange extends radially outward.

In another embodiment according to any of the previous embodiments, the bearing housing includes an outer housing wall extending circumferentially about the axis, a radial wall extending outwardly of the outer housing wall, and a shoulder portion that transitions from the radial wall to the bearing flange that extends in a radially outward direction, and wherein the radial wall includes an axially extending lip that seats a radially inner surface of the second mounting flange.

In another embodiment according to any of the previous embodiments, the curved beam centering spring is comprised of a plurality of curved beam segments.

In another embodiment according to any of the previous embodiments, the curved beam centering spring is a single-piece solid ring curved beam.

In another featured embodiment, a gas turbine engine component includes a bearing configured to support a shaft for rotation about an axis, wherein the bearing includes an outer race and an inner race, and a bearing housing spaced radially outwardly of the outer race. A fluid damper is between the bearing housing and the curved beam centering spring. A cylindrical wall is radially outward of the bearing housing and engages the outer race and the bearing housing.

In another embodiment according to any of the previous embodiments, the inner race is fixed for rotation with the shaft and the outer race is fixed to a static engine structure, and wherein the bearing housing surrounds the curved beam centering spring to form at least one fluid damping chamber between an inner surface of the bearing housing and an outer surface of the curved beam centering spring that is sealed by one or more piston rings or o-rings to provide the fluid damper as a squeeze film damper.

In another embodiment according to any of the previous embodiments, first bolted joint is radially outward of the second bolted joint.

The low speed spool <NUM> generally includes an inner shaft <NUM> that interconnects a first (or low) pressure compressor <NUM> and a first (or low) pressure turbine <NUM>. The inner shaft <NUM> is connected to a fan <NUM> through a speed change mechanism, which in exemplary gas turbine engine <NUM> is illustrated as a geared architecture <NUM> to drive the fan <NUM> at a lower speed than the low speed spool <NUM>.

<FIG> shows an example of a curved beam centering spring arrangement for a thrust bearing that provides desired support stiffness and damping to manage vibrations of associated rotating and static structures at specific engine operating speeds. At least one bearing <NUM> supports a rotating structure <NUM>, such as a shaft for example, for rotation relative to an engine static structure, such as a case structure or cross-over housing <NUM>, for example. The bearing <NUM> includes an outer race <NUM>, an inner race <NUM>, and one or more rolling elements <NUM> between the inner <NUM> and outer <NUM> races. The inner race <NUM> is fixed for rotation with the rotating structure <NUM> and the outer race is fixed to a non-rotating structure. A bearing housing <NUM> is spaced radially outwardly of the outer race <NUM>.

A curved beam centering spring <NUM> is positioned between the outer race <NUM> and the bearing housing <NUM>. A fluid damper <NUM> is positioned between the bearing housing and the curved beam centering spring <NUM>. In one example, the bearing housing <NUM> surrounds the curved beam centering spring <NUM> to form at least one fluid damping chamber <NUM> between an inner surface of the bearing housing <NUM> and an outer surface of the curved beam centering spring <NUM>. The damping chamber <NUM> is sealed by one or more piston rings or o-rings <NUM> to provide a squeeze film damper.

A cylindrical wall <NUM> is positioned radially outward of the bearing housing <NUM> and is configured to engage the outer race <NUM> and the bearing housing <NUM>. The cylindrical wall <NUM> is a relatively thin wall extending circumferentially about an axis, and is rigid in the axial direction to transmit the bilateral engine thrust load to ground, but is compliant in the radial direction to not interfere with the centering spring <NUM> and damper <NUM>. In one example, the cylindrical wall <NUM> includes a first mounting flange <NUM> that is connected to the outer race <NUM> and a second mounting flange <NUM> that is connected to the bearing housing <NUM>. The first mounting flange <NUM> is formed at one end of the cylindrical wall <NUM> and the second mounting flange <NUM> is formed at an opposite end of the cylindrical wall <NUM>. In one example, the first mounting flange <NUM> extends radially inward and the second mounting flange <NUM> extends radially outward.

In one example, the outer race <NUM> includes a bearing flange <NUM> and the bearing housing <NUM> includes a housing flange <NUM>. In one example, the first mounting flange <NUM> is directly connected to the bearing flange <NUM> and the second mounting flange <NUM> is directly connected to the housing flange <NUM> such that the cylindrical wall <NUM> is rigid in an axial direction and compliant in a radial direction. In this configuration, the curved beam centering spring <NUM> is only subject to forces in the radial direction. This makes sealing of the fluid damping chamber <NUM> much more robust.

In one example, the bearing housing <NUM> includes an outer housing wall <NUM> extending circumferentially about the axis, a radial wall <NUM> extending outwardly of the outer housing wall <NUM>, and a shoulder portion <NUM> that transitions from the radial wall <NUM> to the bearing flange <NUM>, which extends in a radially outward direction. In one example, the radial wall <NUM> includes an axially extending lip <NUM> that seats a radially inner surface <NUM> of the second mounting flange <NUM>. In this configuration, a lower portion of an end face <NUM> of the second mounting flange <NUM> abuts directly against the radial wall <NUM> and an upper portion of the end face <NUM> abuts directly against an intermediate case flange <NUM>. The case flange <NUM> is sandwiched between the housing flange <NUM> and the second mounting flange <NUM>. This provides radial stiffness for the centering spring <NUM> and damper <NUM> but does not subject the spring or damper to axial loading.

According to the claimed invention, the cross-over housing <NUM> is radially outward of the cylindrical wall <NUM>. The housing flange <NUM> and second mounting flange <NUM> are connected to a mount flange <NUM> of the cross-over housing <NUM> with at least one fastener <NUM>. This forms a first bolted joint between the cross-over housing <NUM>, cylindrical wall <NUM>, and the bearing housing <NUM>. The first mounting flange <NUM> and the bearing flange <NUM> are connected together with at least one fastener <NUM>. This forms a second bolted joint between the outer race <NUM> and the cylindrical wall <NUM>. The two bolted joints are axially spaced apart from each other. In one example, the first bolted joint is radially outward of the second bolted joint as shown in <FIG>.

In one example, the curved beam centering spring <NUM> is comprised of a plurality of curved beam segments <NUM> as shown in <FIG> shows the curved beam centering spring <NUM> that forms a ring, which is comprised of the curved beam spring segments <NUM>. <FIG> show an example of one of the curved beam spring segments <NUM>. Each curved beam spring segment <NUM> includes an arcuate body <NUM> with an outer surface <NUM> that forms a portion of an outer peripheral surface of the ring and an inner surface <NUM> that forms a portion of an inner peripheral surface of the ring. Each arcuate body <NUM> extends circumferentially from a first end <NUM> to a second end <NUM> that is opposite the first end <NUM>. The ends <NUM>, <NUM> of adjacent bodies <NUM> abut against each other when the curved beam spring segments <NUM> are positioned to form the ring. The number of curved beam spring segments <NUM> can vary.

In one example, each segment <NUM> has an inner pedestal <NUM> on an inside diameter surface at its center and outer pedestals <NUM> and <NUM> on an outside diameter surface at the respective opposing segment ends <NUM>, <NUM>. A fluid recess <NUM> is formed on an outer surface of each segment <NUM>. Loads due to shaft imbalance are transmitted through bearing <NUM> to the inner pedestal <NUM>, which contacts the outer diameter surface of the bearing outer race <NUM>. Rotor imbalances cause the segment <NUM> to deflect and compress the fluid film captured in the fluid recess <NUM>. The fluid recesses <NUM> are each bounded by a groove <NUM> configured in a racetrack shape to support a sealing ring. The fluid recesses <NUM> are continuously fed fluid from a supply tube <NUM> (<FIG>). Each fluid recess <NUM> may have one or more inlet holes <NUM> (<FIG>) and at least one outlet (not shown). In the configuration shown in <FIG>, the fluid damping chamber <NUM> corresponds to one of the fluid recesses <NUM> (<FIG>) and the sealing ring <NUM> corresponds to the sealing ring received within the groove <NUM> (<FIG>). The use of racetrack fluid recesses <NUM> is just one example configuration of a fluid damper, and other fluid damping configurations could also be utilized.

In another example, the curved beam centering spring <NUM> comprises a single-piece solid ring curved beam as shown in <FIG>. An example of this spring is set forth in application number <CIT>, which is assigned to the assignee of the subject disclosure. In this example, the curved beam centering spring <NUM> has an outer peripheral surface <NUM> and an inner peripheral surface <NUM>. As shown in <FIG>, the curved beam centering spring <NUM> includes a plurality of outer diameter (OD) pedestals <NUM> that are formed in the outer peripheral surface <NUM>, and which are circumferentially spaced apart from each other. The curved beam centering spring <NUM> further includes a plurality of inner diameter (ID) pedestals <NUM> that are formed in the inner peripheral surface <NUM>, and which are circumferentially spaced apart from each other. The curved beam centering spring <NUM> also includes a plurality of fluid recesses <NUM> (<FIG>) that are formed in the outer peripheral surface <NUM>, and which are circumferentially spaced apart from each other. The plurality of fluid recesses <NUM> circumferentially alternate with the plurality of outer diameter pedestals <NUM>. As such, there is one fluid recess <NUM> between each adjacent pair of outer diameter pedestals <NUM>.

In one example, the plurality of outer diameter pedestals <NUM> are circumferentially offset from the plurality of inner diameter pedestals <NUM>. In one example, each inner diameter pedestal <NUM> is radially aligned with a corresponding one of the plurality of fluid recesses <NUM>. The outer <NUM> and inner <NUM> diameter pedestals serve as spring structures to allow flexure in the radial direction to control stiffness and transfer radial loads to the static structure. The plurality of recesses <NUM> are configured to receive a fluid, such as oil for example, and serve as an oil squeeze film damper.

As shown in <FIG>, a first groove <NUM> is formed in the outer peripheral surface <NUM> and a second groove <NUM> is formed in the outer peripheral surface <NUM>. In this example, the piston rings or o-rings <NUM> (<FIG>) are positioned within the first groove <NUM> and the second groove <NUM> to provide sealing for each of the circumferentially spaced fluid recesses <NUM>. Thus, the fluid damping chamber <NUM> of <FIG> corresponds to one of the fluid recesses <NUM>. In one example, each of the fluid recesses <NUM> of the solid ring curved beam have one or more fluid inlets <NUM> as shown in <FIG> and each have at least one outlet (not shown). In another example, the solid ring can have one fluid feed or inlet <NUM> and the outer diameter pedestals <NUM> can have slots to feed fluid from one cavity to another. In one example, the inlet <NUM> extends through the outer housing wall <NUM> of the bearing housing <NUM>. The supply tube <NUM> is configured to supply fluid to the inlet(s) <NUM>.

The subject disclosure provides a curved beam centering spring and damper configuration that eliminates rolling problems related to segmented configurations. By creating an arrangement of parts that provides an alternate path for the axial thrust load, the curved beams are only exposed to force in the radial direction. For the multi-piece segment configuration, this makes fluid sealing more robust and reduces scuffing between mating surfaces of the segmented beams. For the solid damper ring configuration, a more conventional circumferential oil damper configuration is provided in combination with the cylindrical wall that takes the thrust loading. This arrangement of a curved beam and a thrust load carrying member results in a damper that is radially compliant, provides the capability of withstanding bilateral thrust loading, and offers the ability to tune stiffness as required with the curved beams.

Additionally, the curved beam design provides a wide range of applicability by allowing a more compact and lightweight design than a conventional centering spring design with fully machined beams. The separation of the axial thrust load addresses sealing and scuffing issues experienced by trying to transmit the thrust load through the segmented beams as done in traditional configurations.

Claim 1:
A gas turbine engine component comprising:
a static structure (<NUM>) comprising a cross-over housing (<NUM>);
a bearing (<NUM>) configured to support a shaft for rotation about an axis, wherein the bearing (<NUM>) includes an outer race (<NUM>) and an inner race (<NUM>);
a bearing housing (<NUM>) spaced radially outwardly of the outer race (<NUM>);
characterised by a curved beam centering spring (<NUM>) positioned between the outer race (<NUM>) and the bearing housing (<NUM>); and
a cylindrical wall (<NUM>) radially outward of the bearing housing (<NUM>), wherein the cross-over housing is radially outward of the cylindrical wall, wherein the cylindrical wall (<NUM>) engages the outer race (<NUM>) and the bearing housing (<NUM>),
wherein the cross-over housing (<NUM>) includes a mount flange (<NUM>),
wherein the cylindrical wall (<NUM>) includes a first mounting flange (<NUM>) that is connected to the outer race (<NUM>) and a second mounting flange (<NUM>) that is connected to the bearing housing (<NUM>),
wherein the outer race (<NUM>) includes a bearing flange (<NUM>) and wherein the bearing housing (<NUM>) includes a housing flange (<NUM>), and
wherein the first mounting flange (<NUM>) is directly connected to the bearing flange (<NUM>) with at least one first fastener (<NUM>) to form a second bolted joint, and the second mounting flange (<NUM>) which is directly connected to the housing flange (<NUM>) are connected to the mount flange (<NUM>) with at least one second fastener (<NUM>) to form a first bolted joint that is axially spaced apart from the second bolted joint, such that the cylindrical wall (<NUM>) is rigid in an axial direction and compliant in a radial direction, and such that the curved beam centering spring (<NUM>) is only subject to forces in the radial direction.