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 it is mixed with fuel and ignited. Products of the combustion pass downstream over turbine rotors, driving them to rotate.

In one known type of gas turbine engine, there are at least two turbine rotors, each driving a compressor rotor. One of the two rotors rotates at higher speeds relative to a lower speed rotor. In one example, a seal for an engine bearing compartment is installed within a stationary seal carrier. The seal has an end face that contacts a rotating seal face plate or seat. The face plate is mounted for rotation with a rotor shaft that connects a turbine rotor to a compressor rotor.

The seal should be able to accommodate axial and radial movement, however, excessive movement can be potentially damaging. For example, the seal has a vibratory mode that results in a lower frequency precession, which can cause damage to the seal as a result of an impact between the stationary seal and the rotating seat. It has been proposed to control movement using an air or oil film damper but these systems can be overly complicated and expensive.

An example of such a system is disclosed in <CIT> in which a noncontacting dynamic seal having wave springs is disclosed. The seal has a shoe coupled to an outer ring by an inner and an outer beam. A wave spring is located between the inner and outer beams, between the shoe and the inner beam, or between the outer beam and the outer ring. The wave spring may damp vibrations in the inner and outer beams.

<CIT> discloses a rotary air-riding seal between a first structure and an adjacent second structure. At least one of the structures is rotatable relative to the other about an axis of rotation. A seal between the structures includes first and second seal members defining respective seal surfaces which are facing each other. The seals are mounted on the first and second structures in a fashion allowing axial oscillation of one of the seal members and to resiliently bias the seal member towards each other.

<CIT> discloses a seal support structure for a circumferential. The seal support structure includes an engine support structure, a seal support, and a shoulder joining the engine support and seal support. The shoulder offsets the engine support from the seal support, and the shoulder and the seal support structure are configured to dampen vibration for the circumferential seal. The seal support structure employs a dampening ring that interoperates with the seal support structure to dampen radial vibration of seal system.

In accordance with a first aspect of the disclosure, a gas turbine engine component comprising: a static component comprising a seal housing fixed to a non-rotating engine structure; a seal body associated with the static component, the seal body having an end face configured to face a rotating seal seat; a seal carrier fixed to the seal body; characterised in that the component further comprises at least one spring acting between the seal housing and the seal body to accommodate axial movement of the seal body relative to the rotating seal seat, a damper positioned radially outward of the seal body, wherein the damper comprises a plurality of fingers, each finger extending from the seal housing in an axial direction to a distal end that extends in a radial inward direction toward the seal carrier, and wherein each finger includes a contact that engages the seal body to dampen radial movement of the seal body while accommodating axial movement of the seal body.

In an embodiment according to the previous embodiment, the static component comprises a seal housing fixed to a non-rotating engine structure.

In another embodiment according to any of the previous embodiments, the component includes a seal carrier fixed to the seal body.

In another embodiment according to any of the previous embodiments, the at least one spring has a first spring end fixed to the seal housing and a second spring end fixed to the seal carrier.

In another embodiment according to any of the previous embodiments, the at least one finger includes a narrowing neck portion to adjust radial stiffness.

In another embodiment according to any of the previous embodiments, the distal end includes the contact that directly engages a radially outer surface of the seal carrier.

In another embodiment according to any of the previous embodiments, the contact comprises at least one bearing ball that maintains radial contact with the seal carrier while allowing axial movement of the seal carrier relative to the seal housing and seal seat.

In another embodiment according to any of the previous embodiments, the seal body comprises a carbon face seal.

In accordance with a second aspect of the disclosure, a gas turbine engine comprising: at least one rotor shaft that interconnects a compressor and a turbine for rotation about an engine center axis; and a carbon face seal assembly including a gas turbine engine component of the first aspect of the disclosure, a seal seat mounted for rotation with the at least one rotor shaft, and the seal body is positioned axially between the seal housing and the seal seat.

In another embodiment according to any of the previous embodiments, the distal end includes the contact, which comprises at least one bearing ball that maintains radial contact with the seal body while allowing axial movement of the seal body relative to the seal housing and seal seat.

In another embodiment according to any of the previous embodiments, the seal body includes a first end face, a second end face axially spaced from the first end face, and radially inner and radially outer surfaces that extend between the first and the second end faces, and including a seal carrier fixed to the seal body at least at the radially outer surface, and wherein the distal end of the at least one finger extends in a radial inward direction to directly engage a radially outer surface of the seal carrier.

In another embodiment according to any of the previous embodiments, the engine further includes at least one spring acting between the seal housing and the seal body to accommodate axial movement of the seal body relative to the seal seat, and wherein the at least one spring has a first spring end fixed to the seal housing and a second spring end fixed to the seal carrier.

In accordance with a third aspect of the disclosure, a method of operating a gas turbine comprising the steps of: driving at least one shaft with a turbine rotor to drive a compressor; holding a seal body in a non-rotating relationship relative to a rotating seal seat coupled to the at least one shaft in which the seal body has an end face configured to face the seal seat and which is associated with a static component comprising a seal housing fixed to a non-rotating engine structure; fixing a seal carrier to the seal body; and damping radial movement of the seal body with a damper positioned radially outward of the seal body while accommodating axial movement of the seal body relative to the rotating seal seat, wherein the damper comprises a plurality of fingers, each finger extending from the seal housing in an axial direction to a distal end that extends in a radial inward direction toward the seal carrier, and wherein each finger includes a contact that engages the seal body to dampen radial movement of the seal body while accommodating axial movement of the seal body.

In another embodiment according to any of the previous embodiments, the method includes providing a seal carrier fixed to the seal body and providing the distal end with at least one bearing ball, and further includes connecting a first spring end of at least one spring to a non-rotating engine structure, connecting a second spring end of the at least one spring to the seal carrier such that the at least one spring accommodates axial movement of the seal body relative to the rotating seal seat, and extending the distal end of each finger in a radial inward direction to directly engage a radially outer surface of the seal carrier to dampen radial movement of the seal body.

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>.

A face seal assembly <NUM> is illustrated in <FIG>. A seal face plate or seal seat <NUM> is mounted for rotation about an axis A defined by an engine centerline (<FIG>). The seal seat <NUM> rotates relative to a non-rotating engine component or structure <NUM>. A seal housing <NUM> is fixed to the non-rotating structure <NUM>. A seal body <NUM> is associated with the seal housing <NUM> and includes a first end surface or face <NUM> that faces an end surface or face <NUM> of the seal seat <NUM>. The seal body <NUM> has a central bore <NUM> that surrounds the axis A. It should be understood that only the upper cross-section of the seal assembly <NUM> is shown in <FIG>, with the lower cross-section being similarly configured to that of the upper cross-section as these components extend around the axis A.

The seal body <NUM> is made from a carbon-based material as known. The seal body <NUM> includes the first end face <NUM>, a second end face <NUM> axially spaced from the first end face <NUM>, and radially inner <NUM> and radially outer <NUM> surfaces that extend between the first <NUM> and the second <NUM> end faces. The radially inner <NUM> and radially outer <NUM> surfaces extend parallel to each other in an axial direction along the axis A. The first <NUM> and second <NUM> end faces extend generally perpendicular to the radially inner <NUM> and radially outer <NUM> surfaces. The first end face <NUM> includes a protruding portion or nose 70a that extends toward the seal seat <NUM> to make sealing contact with the end face <NUM>. Thus, there is direct contact between the face <NUM> of the seal seat <NUM> and the nose 70a of the carbon seal body <NUM>.

A seal carrier <NUM> is associated with the seal body <NUM>. The seal carrier <NUM> comprises a carbon carrier for the seal body <NUM> that is coupled to the seal housing <NUM> such that the seal carrier <NUM> and seal body <NUM> comprise non-rotating components. In one example, the seal carrier <NUM> includes a radially outer wall <NUM> that extends in an axial direction and seats the radially outer surface <NUM> of the seal body <NUM> and a radially inwardly extending wall <NUM> that seats the second end face <NUM> of the seal body <NUM>. The seal carrier <NUM> also includes a flange <NUM> that extends in an axial direction opposite from the outer wall <NUM>. The flange <NUM> is positioned at a radially inward edge of the wall <NUM>.

In one example, the seal housing <NUM> includes a radially outer wall <NUM> extending in an axial direction and a radial wall <NUM> that extends radially inward from the outer wall <NUM>. An open cavity <NUM> is formed between the outer wall <NUM> and radial wall <NUM> of the seal housing <NUM> and the radial wall <NUM> and flange <NUM> of the seal carrier <NUM>. At least one resilient member, such as a spring <NUM> for example, is received within this cavity <NUM> and is used to exert a spring force between the seal housing <NUM> and seal carrier <NUM>. The at least one spring <NUM> has a first spring end <NUM> fixed to the seal housing <NUM> and a second spring end <NUM> fixed to the seal carrier <NUM>.

The seal assembly <NUM> includes a damper <NUM> that includes a contact <NUM> that engages the seal to dampen radial movement of the seal while accommodating axial movement of the seal. In one example, the damper <NUM> comprises at least one finger <NUM> extending from the seal housing <NUM> in an axial direction to a distal end <NUM> that extends in a radial inward direction toward the seal carrier <NUM>. The finger <NUM> has an axially extending elongated body <NUM> having the distal end <NUM> at one end and a connecting portion <NUM> at an opposite end. In one example, the connecting portion <NUM> extends in a radially inward direction from the elongated body <NUM> to connect to a radially outer surface <NUM> of the outer wall <NUM> of the seal housing <NUM>.

In one example, the elongated body <NUM> of the finger <NUM> includes a narrowing neck portion <NUM> to adjust radial stiffness. The narrowing neck portion <NUM> comprises a reduced diameter portion compared to diameters at portions of the elongated body <NUM> at the distal end <NUM> and/or connecting portion <NUM>. This reduced diameter portion or narrowing neck portion <NUM> basically comprises a pivoting area that allows the distal end <NUM> to move up and down in a radial direction to accommodate radial movement of the seal carrier <NUM> and seal body <NUM>. The distal end <NUM> is configured such that the finger <NUM> is always in contact with the seal carrier <NUM> during engine operation, i.e. there is never a radial gap between the contact <NUM> at the distal end <NUM> and the seal carrier <NUM>. As such, the distal end <NUM> includes the contact <NUM> that directly engages a radially outer surface <NUM> of the seal carrier <NUM>.

In one example, the contact <NUM> comprises at least one bearing ball that maintains radial contact with the seal carrier while simultaneoulsy allowing axial movement of the seal carrier <NUM> relative to the seal housing <NUM> and seal seat <NUM>. The bearing ball rotates within the distal end <NUM> of the finger <NUM> to accommodate the axial movement. In one example, the bearing ball comprises a full sphere that is installed within a socket formed in the distal end <NUM> of the finger <NUM>. In one example, the ball is fully retained within the socket with approximately ¼ of the ball protruding to contact the carbon seal carrier <NUM>. The bearing ball is made from a ceramic material such as silicon nitride or other similar materials, for example.

In one example, the at least one finger <NUM> comprises a plurality of fingers <NUM>. <FIG> shows a configuration where there are three fingers <NUM> with dampers <NUM>. The fingers <NUM> are equally spaced apart from each other in a circumferential direction about the axis A.

The subject invention provides one or more fingers that contact the carbon seal carrier in a radial direction via bearing balls. The fingers are attached to the seal housing and are configured to be flexible enough to account for small amounts of radial travel while maintaining contact. The distal end(s) of the finger(s) include the bearing ball(s), which are in direct contact with the carbon seal carrier. This allows axial movement of the seal without creating extra drag. The seal includes a spring and is compressed/elongated during operation so the bearing ball(s) will not impede the natural motion of the seal.

The subject invention provides a mechanical solution that is much simpler and compact as compared to prior air or oil film dampers. Further, the mechanical solution is capable of limiting radial movement of the seal without adversely impacting axial movement of the seal.

Claim 1:
A gas turbine engine component comprising:
a static component comprising a seal housing (<NUM>) fixed to a non-rotating engine structure (<NUM>);
a seal body (<NUM>) associated with the static component, the seal body (<NUM>) having an end face (<NUM>) configured to face a rotating seal seat (<NUM>);
a seal carrier (<NUM>) fixed to the seal body (<NUM>); characterised in that the component further comprises
at least one spring (<NUM>) acting between the seal housing (<NUM>) and the seal carrier (<NUM>) to accommodate axial movement of the seal body (<NUM>) relative to the rotating seal seat (<NUM>) and a damper (<NUM>) positioned radially outward of the seal body (<NUM>), wherein the damper (<NUM>) comprises a plurality of fingers (<NUM>), each finger (<NUM>) extending from the seal housing (<NUM>) in an axial direction to a distal end (<NUM>) that extends in a radial inward direction toward the seal carrier (<NUM>), and wherein each finger (<NUM>) includes a contact (<NUM>) that engages the seal body (<NUM>) to dampen radial movement of the seal body (<NUM>) while accommodating axial movement of the seal body (<NUM>).