Patent Description:
More precisely, the invention relates to an assembly, as well as to a method for installing.

a bladed rotor on a shaft of a gas turbine engine or removing the bladed rotor from the gas turbine engine.

Aircraft (e.g., gas turbine) engines have rotors that are rotatably mounted inside shrouds with relatively small clearances between the rotors and the shrouds. The removal or installation of some rotors in gas turbine engines, whether during initial assembly of the engine or during maintenance, is a time-consuming and expensive task that requires significant disassembly of the gas turbine engine in order to facilitate access and safe handling of the rotor(s). Improvement is desirable. <CIT> and <CIT> disclose arrangements of the prior art. <CIT> discloses a method and tooling for partial disassembly of a bypass turbofan engine for removing a low pressure turbine module with a low pressure turbine module horizontal removal tool. <CIT> discloses a gas turbine shaft bearing system service tool and method. The apparatus has two units, one coupled to the rotor shaft and the other to the bearing system.

In one aspect, the invention describes an assembly as claimed in claim <NUM>.

In a further aspect, the invention describes a method for installing a rotor on a shaft of a gas turbine engine, or removing the rotor from the gas turbine engine, as claimed in claim <NUM>.

The following disclosure describes aircraft engine repair tools and methods for facilitating the installation of a rotor (or rotor assembly) in an aircraft (e.g., gas turbine) engine, or removing the rotor (or rotor assembly) from the gas turbine engine with reduced disassembly of the gas turbine engine. In some embodiments, the tools and methods may be used to install or remove, as a unit, a rotor assembly such as a compressor boost module that may include one or more rotors and one or more stators. In some embodiments, the tool may have a stabilizer attachable to a shaft of the gas turbine engine and a holder attachable to the rotor or rotor assembly. The movement of the holder together with the rotor (or rotor assembly) axially along the shaft may be guided by the stabilizer so as to permit relatively accurate and stable movement of the holder and rotor (or rotor assembly) over a relatively long reach inside the gas turbine engine. The stability of the movement of the holder within the gas turbine engine provided by the stabilizer may, in some embodiments, facilitate safe access and handling of the rotor or rotor assembly without requiring significant disassembly of the gas turbine engine. Embodiments of the tools described herein may be suitable for use in the field for removable/installation of a rotor or rotor assembly in an aircraft-mounted engine (e.g., on wing).

The term "attached" as used herein may include both direct attachment (in which two elements that are attached to each other contact each other) and indirect attachment (in which at least one additional intermediate element is disposed between the two elements). The term "substantially" as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.

<FIG> illustrates a gas turbine engine <NUM> of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a fan <NUM> through which ambient air is propelled, a multistage compressor <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases. Engine <NUM> may include bypass duct <NUM> and core gas path <NUM> that are separated by inner casing <NUM>. Flow splitter <NUM> may be disposed at a forward end of inner casing <NUM>. Flow splitter <NUM> may be releasably attached to and consequently removable from the remainder of inner casing <NUM> according to known or other methods. Engine <NUM> may include fan case <NUM> inside which fan <NUM> is rotatably mounted. Nose cone <NUM> may be disposed forward of fan <NUM> and releasably attached for common rotation with fan <NUM>. Engine <NUM> may include bypass stator <NUM>, which may be an airfoil-shaped strut providing structural support within engine <NUM>.

Engine <NUM> may be a dual spool gas turbine engine. Engine <NUM> may include low-pressure shaft <NUM> to which fan <NUM>, compressor boost module <NUM> (referred herein after as "boost module <NUM>") and low-pressure turbine <NUM> are drivingly coupled thereto. Boost module <NUM> may be a compressor rotor assembly including one or more initial stages of compressor <NUM>. Accordingly, boost module <NUM> may be considered a low-pressure compressor of compressor <NUM>. Boost module <NUM> may include one or more bladed rotors and one or more stators (e.g., vane rings). For example, as explained below, boost module <NUM> may include an alternating arrangement of rotors and stators.

Engine <NUM> may include high-pressure shaft <NUM> to which high-pressure turbine <NUM> and high-pressure compressor <NUM> are drivingly coupled thereto. Low-pressure shaft <NUM> and high-pressure shaft <NUM> may be mechanically uncoupled to permit separate rotation. Low-pressure shaft <NUM> may have shaft axis SA, which may correspond to a central axis of engine <NUM>. For example, low-pressure shaft <NUM> and high-pressure shaft <NUM> may be mounted coaxially for rotation about shaft axis SA.

Engine <NUM> may include a conventional or other type of gas turbine engine suitable for use in aircraft or ground-based applications. <FIG> shows engine <NUM> of the turbofan type but it is understood that some embodiments of the tools and methods described herein may be suitable for use on other types of gas turbine engines such as turboshaft engines and turboprop engines.

<FIG> is a perspective view of an exemplary aircraft engine repair tool <NUM> for facilitating the installation and/or removal of boost module <NUM> (shown in <FIG>), other rotor or rotor assembly releasably mounted to a shaft of engine <NUM>. A forward portion of engine <NUM> is shown in <FIG> in conjunction with tool <NUM>. It is understood that tool <NUM> may be used for the installation and/or removal of a single rotor, an assembly of multiple rotors (i.e., as a unit/module), or an assembly of one or more rotors and one or more stators (i.e., as a unit/module) of engine <NUM>.

Some parts of engine <NUM> may be required to be removed from engine <NUM> to provide access to boost module <NUM>. However, the amount of disassembly required may be less than that required in other methods. <FIG> shows the part of engine <NUM> where nose cone <NUM> and fan <NUM> have been removed from engine <NUM>. In some situations, depending on the configuration of engine <NUM>, one or more other components such as flow splitter <NUM>, bypass stator <NUM>, an inner shroud of fan case <NUM>, and/or an outer retaining strap of fan case <NUM> may need to be removed from engine <NUM> to permit the removal or installation of boost module <NUM> using tool <NUM>.

Tool <NUM> includes stabilizer <NUM> and holder <NUM>. Stabilizer <NUM> has a shaft interface attachable to low-pressure shaft <NUM> or other shaft of engine <NUM>. Holder <NUM> has a rotor interface attachable to compressor boost module <NUM>. Holder <NUM> is engageable with stabilizer <NUM> so that movement of holder <NUM> relative to stabilizer <NUM> along guide axis GA may be guided by stabilizer <NUM>, and movement of holder <NUM> relative to stabilizer <NUM> transverse to guide axis GA may be substantially prevented. Accordingly, the use of stabilizer <NUM> attached to low-pressure shaft <NUM> may facilitate stable axial movement of holder <NUM> over a relatively long axial distance/reach into engine <NUM>. In other words, stabilizer <NUM> may allow holder <NUM> to be supported by (i.e., rest on) low-pressure shaft <NUM> as holder <NUM> is moved axially in or out of engine <NUM>. Guide axis GA may be substantially parallel (e.g., coaxial) to shaft axis SA.

Holder <NUM> may also be supported by (e.g., fastened to) a suitable support structure <NUM> (shown schematically in <FIG>) such as a stand, wheeled cart, articulated arm, or overhead support for example. As shown in <FIG>, support structure <NUM> may be a wheeled cart including floor-engaging wheels <NUM>, brakes and/or adjustable leveling feet.

Holder <NUM> may be movable along one or more axes relative to support structure <NUM> to permit alignment, axial advancement and/or axial retraction of holder <NUM> within engine <NUM>. For example, holder48 may be translatable axially along arrow A, which may be substantially parallel to guide axis GA, via a suitable guide rail system including one or more guide rails and one or more slide block/carriages. In some embodiments, holder <NUM> may also be translatable laterally along arrow L, which may be transverse to guide axis GA, via a suitable guide rail system (not shown). In some embodiments, holder <NUM> may also be rotatable along arrow R and about guide axis GA, via a suitable guide bearing system (not shown). Translational movement of holder <NUM> along arrows A and/or L, and/or rotation of holder <NUM> along arrow R may be actuated via suitable rack-and-pinion system, ball screw system or hydraulic ram and may be actuated manually (e.g., via control knobs) or via electric and/or hydraulic actuators.

<FIG> is a perspective view of an exemplary stabilizer <NUM> of tool <NUM> of <FIG> and a forward end of low-pressure shaft <NUM> of engine <NUM>. Stabilizer <NUM> may include ring-shaped body <NUM> including forward side 60A facing axially forward (see <FIG>) along guide axis GA and aft side 60B opposite forward side 60A facing aft along guide axis GA. Body <NUM> may not necessarily be ring-shaped and may instead be a circular disc or a polygonal plate instead. Body <NUM> may be made from suitable metallic material such as steel.

Stabilizer <NUM> includes shaft interface <NUM> for attachment with low-pressure shaft <NUM>. Shaft interface <NUM> may be disposed on aft side 60B of body <NUM>. Shaft interface <NUM> may include a relatively flat annular surface for contacting first (fan) flange <NUM> formed on low-pressure shaft <NUM>. First flange <NUM> may provide an interface for attaching fan <NUM> to low-pressure shaft <NUM> during operation of engine <NUM>. With nose cone <NUM> and fan <NUM> removed from first flange <NUM>, stabilizer <NUM> may be attached to first flange <NUM> instead. In some embodiments of low-pressure shaft <NUM>, first flange <NUM> may be disposed at a forward axial end of low-pressure shaft <NUM> but it is understood that stabilizer <NUM> may be adapted to interface with low-pressure shaft <NUM> at a location that is axially inward from the axial end of low-pressure shaft <NUM>.

Body <NUM> of stabilizer <NUM> may have one or more fastener holes <NUM> for accommodating suitable threaded fasteners (e.g., bolts, threaded stud) therethrough. Fastener holes <NUM> may be substantially aligned with corresponding one or more threaded holes, threaded studs, or holes and nuts <NUM> associated with in first flange <NUM>. For convenience, one or more of the same nuts <NUM> used to mount fan <NUM> to first flange <NUM> may be used to mount stabilizer <NUM> to first flange <NUM>. For example, threaded fasteners (not shown) may be inserted into threaded holes <NUM> and threaded into corresponding threaded holes formed in first flange <NUM> or nuts <NUM> for attaching stabilizer <NUM> thereto in place of fan <NUM>.

In some embodiments of tool <NUM>, it may be desirable to install stabilizer <NUM> at a specific angular orientation with respect to low-pressure shaft <NUM>. In order to facilitate the clocking of stabilizer <NUM> with low-pressure shaft <NUM>, and/or clocking stabilizer <NUM> to holder <NUM>, body <NUM> of stabilizer <NUM> may have indication <NUM> disposed on forward side 60A for indicating a top dead center (TDC) of engine <NUM>. Indication <NUM> may be used to orient stabilizer <NUM> relative to a corresponding reference disposed on low-pressure shaft <NUM> and/or to a corresponding indication disposed on holder <NUM> for example.

In some embodiments of tool <NUM>, stabilizer <NUM> may include one or more locating pins <NUM> extending in the aft direction from body <NUM>. Locating pins <NUM> may engage with corresponding locating holes <NUM> formed in first flange <NUM>. Locating pins <NUM> may be used to at least partially set an orientation and position of stabilizer <NUM> relative low-pressure shaft <NUM>. Locating pins <NUM> may be made from a suitable tool steel.

Shaft <NUM> may also have second (rotor) flange <NUM> to which a hub of a rotor portion of boost module <NUM> may be mounted. Boost module <NUM> may be mounted to second flange <NUM> any suitable way. For example, a plurality of T-bolts <NUM> may extend through holes formed through second flange <NUM> and be circumferentially distributed about second flange <NUM>. T-bolts <NUM> may then extend through corresponding holes formed in boost module <NUM> and suitable nuts may be used to secure boost module <NUM> to low-pressure shaft <NUM> via second flange <NUM>.

Stabilizer <NUM> includes one or more first guide counterparts that are configured to engage with one or more corresponding second guide counterparts provided on holder <NUM>. In the embodiments shown, the first guide counterpart includes one or more guide pins <NUM> that extend axially outwardly from forward side 60A of body <NUM> of stabilizer <NUM>. As explained below, guide pins <NUM> may engage with corresponding bushings <NUM> (shown in <FIG>) provided on holder <NUM>. The engagement of guide pins <NUM> with corresponding bushings <NUM> may guide movement of holder <NUM> relative to stabilizer <NUM> along guide axis GA and substantially prevent movement of holder <NUM> relative to stabilizer <NUM> transverse to guide axis GA.

In some embodiments, two or more guide pins <NUM> may be provided on stabilizer <NUM> to substantially prevent relative rotation of holder <NUM> relative to stabilizer <NUM> when guide pins <NUM> are engaged with corresponding bushings <NUM>. Guide pins <NUM> may be substantially parallel elongated members. Guide pins <NUM> may be spaced apart from each other. Guide pins <NUM> may each have a longitudinal axis that is parallel to guiding axis GA. Guide pins <NUM> may have useful length L1 and may each have a substantially uniform (e.g., circular) cross-section profile along its useful length L1. As explained further below, length L1 may be selected based on an axial distance along which guiding of holder <NUM> may be desired. Guide pins <NUM> may have substantially the same length L1.

It is understood that other arrangements for providing such guiding function may be suitable. As an alternative to the embodiment shown in <FIG>, one or more guide pins may instead be provided on holder <NUM> and one or more corresponding bushings may instead be provided on stabilizer <NUM>. As another alternative, holder <NUM> may include a guide pin and a bushing, and stabilizer <NUM> may include a bushing for cooperating with the guide pin of the holder <NUM> and a guide pin for cooperating with the bushing of the holder <NUM>. Types of elongated members other than guide pins <NUM> may be suitable. For example, one or more guide rails or tracks of various cross-sections may be provided on stabilizer <NUM> or holder <NUM>, and one or more corresponding carriages or slide blocks may be provided on the other of stabilizer <NUM> or holder <NUM>.

<FIG> is a perspective view of an exemplary rotor holder <NUM> of tool <NUM>. Holder <NUM> includes one or more second guide counterparts for engagement with the one or more first guide counterparts of stabilizer <NUM>. For example, holder <NUM> may include one or more bushings <NUM> receiving corresponding guide pins <NUM> of stabilizer <NUM> for sliding engagement therewith. <FIG> includes an inset schematically illustrating engagement of an exemplary bushing <NUM> with a corresponding guide pin <NUM> of stabilizer <NUM> and also showing movement of bushing <NUM> along arrow B relative to guide pin <NUM> to permit corresponding movement of holder <NUM> along guide axis GA relative to stabilizer <NUM>. Bushings <NUM> may be disposed in hub <NUM> of holder <NUM>.

Holder <NUM> may include indication <NUM> indicative of the top dead center. Indication <NUM> on holder <NUM> and corresponding indication <NUM> on stabilizer <NUM> may provide a visual indication of proper relative orientation/positioning between holder <NUM> and stabilizer <NUM> during installation of tool <NUM> on engine <NUM>.

Holder <NUM> may include one or more clamps <NUM> for holding boost module <NUM>. Clamps <NUM> may be configured to permit releasable attachment of boost module <NUM> to holder <NUM>. Clamp <NUM> may provide axially opposed first and second clamping surfaces 90A, 90B between which part of boost module <NUM> may be received and releasably secured. The axial distance between respective sets of clamping surfaces 90A, 90B may be adjustable so as to permit clamping and releasing of boost module <NUM>. For example, second clamping surfaces 90B may be axially movable relative to first clamping surface 90A. First clamping surface 90A may be annular. Second clamping surfaces 90B may each include a movable pad disposed on a movable (e.g., articulated, extendable/retractable) arm <NUM>. In some embodiments, first clamping surface 90A may have a fixed position relative to holder hub <NUM> and second clamping surfaces 90B may each have a variable position relative to holder hub <NUM>. However, it is understood that first clamping surface 90A may be fixed and that second clamping surfaces 90B may instead be movable. A plurality of clamps <NUM> may be circumferentially spaced apart about guide axis GA. Clamps <NUM> may be disposed radially outwardly of stabilizer <NUM> and may also extend axially aft of stabilizer <NUM> during use so that boost module <NUM>, disposed axially behind stabilizer <NUM> may be clamped into and retained by holder <NUM>.

Holder <NUM> may include optional extension frame <NUM> for releasably mounting between clamps <NUM> and support structure <NUM>. Extension frame <NUM> may serve as an axial spacer for providing sufficient reach of clamps <NUM> into engine <NUM>. In various situations, extension frames <NUM> of various sizes may be used. Alternatively, no extension frame <NUM> may be required in some situations.

<FIG> is a rear elevation view of holder <NUM>.

<FIG> is a left elevation view of holder <NUM> with rotor <NUM> retained in holder <NUM>. Only part of rotor <NUM> is shown schematically. Rotor <NUM> is a bladed rotor part of compressor <NUM> of engine <NUM>. Rotor <NUM> may be part of boost module <NUM>. Arms <NUM> of clamps <NUM> may be disposed radially outward of rotor <NUM> and second clamping surfaces 90B may be disposed radially inward of arms <NUM>. Clamping surfaces 90A, 90B may engage with axially-opposite surfaces of rotor <NUM>. In some embodiments, clamping surfaces 90A, 90B may engage with non-blade surfaces (e.g., a hub, platform, rim) of rotor <NUM>.

Arms <NUM> may be movably attached to holder <NUM> by way of respective bolts <NUM> (or pins) receive in respective through slots <NUM> formed in each arm <NUM>. For example, arms <NUM> may be movable along guide axis GA to permit movement of second clamping surfaces 90B relative to first clamping surface(s) 90A. Holder <NUM> may include one or more actuators <NUM> to apply a clamping force between first and second clamping surfaces 90A, 90B. Such actuator <NUM> may be manually actuatable and may include a threaded member such as a jacking bolt or screw that is engaged with one or more arm <NUM> and arranged to cause relative movement between arms(s) <NUM> and some other structure of holder <NUM>. Alternatively, actuator(s) <NUM> may be electrically and/or hydraulically powered.

<FIG> is a flowchart illustrating method <NUM> for installing rotor <NUM> (or rotor assembly such as boost module <NUM>) on a shaft of engine <NUM>, or removing the rotor (or rotor assembly) from the shaft. Method <NUM> is performed using tool <NUM> as described above or some other tool(s). Aspects of method <NUM> may be combined with aspects of tool <NUM> and/or with other methods and/or actions described herein. In various embodiments, method <NUM> includes: attaching stabilizer <NUM> to the shaft (see block <NUM>); movably engaging holder <NUM> with stabilizer <NUM> so that movement of holder <NUM> relative to stabilizer <NUM> along shaft axis SA of rotation of the shaft is permitted and movement of holder <NUM> relative to stabilizer <NUM> transverse to shaft axis SA of the shaft is substantially prevented (see block <NUM>); with rotor <NUM> attached to holder <NUM>, rotor <NUM> released from the shaft and holder <NUM> engaged with stabilizer <NUM>, moving holder <NUM> and rotor <NUM> together along shaft axis SA of the shaft toward or away from an installed position of rotor <NUM> along the shaft (see block <NUM>).

When rotor <NUM> is being moved toward the installed position, this may be indicative of rotor <NUM> being installed into engine <NUM>. Hence, after moving holder <NUM> and rotor <NUM> along shaft axis SA and toward the installed position (see block <NUM>), rotor <NUM> may the be attached to the shaft (see block <NUM>).

When rotor <NUM> is being moved away from the installed position, this may be indicative of rotor <NUM> being removed from engine <NUM>. Hence, after moving holder <NUM> and rotor <NUM> along shaft axis SA and away from the installed position (see block <NUM>), rotor <NUM> may the be removed from engine <NUM> (see block <NUM>).

As explained above, engine <NUM> may be a turbofan engine and method <NUM> may include removing fan <NUM> from a fan interface such as first flange <NUM> of low-pressure shaft <NUM>; and attaching stabilizer <NUM> to the fan interface. In some embodiments, depending on the configuration of engine <NUM> and on the type of rotor <NUM> being attached to holder <NUM>, one or more other components such as splitter <NUM>, bypass stator <NUM>, an inner shroud of fan case <NUM>, and/or an outer retaining strap of fan case <NUM> may need to be removed from engine <NUM> to permit the removal or installation of rotor <NUM> and/or boost module <NUM> using tool <NUM>. Accordingly, method <NUM> may include removing such components and reinstalling such components at the appropriate time. Method <NUM> may include moving holder <NUM> and rotor <NUM> together along shaft axis SA while splitter <NUM> and/or one or more other components of engine are removed from engine <NUM>.

<FIG> is a schematic view of part of aircraft engine repair tool <NUM> of <FIG> during the removal of boost module <NUM> from engine <NUM> or the installation of boost module <NUM> into engine <NUM>. Aspects of method <NUM> are illustrated in <FIG>. Boost module <NUM> may include rotor stages 34B and 34D, an stator stages 34A and 34C. Rotor stages 34B and 34D may be separate circular arrays of blades that are mounted for common rotation about a same rotor hub <NUM>. Stator stages 34A and 34C may be vane rings. Stator stage 34A may be a set of inlet guide vanes. In the configuration shown, clamping onto a single rotor stage 34B or 34D may be sufficient to carry boost module <NUM> as a unit. Only an upper part of boost module <NUM> is shown in <FIG>.

Boost module <NUM> may include one or more rows of rotor blades and/or more rows of stator vanes. Tool <NUM> may engage boost module <NUM> by directly securing to the rotor assembly including rotor stage 34B and rotor stage 34D while at the same time securing to the stator assembly including stator stage 34A and stator stage 34C. The connection(s) (e.g., via clamps <NUM>) to the rotor assembly may be fixed while the connection(s) (e.g., via clamps <NUM>) to the stator assembly may be adjusted in order to duplicate and maintain the nominal rotor/stator axial position as established when boost module <NUM> is installed inside engine <NUM>. For example, different clamps <NUM> or pairs of clamps <NUM> may be used to secure tool <NUM> to different components of boost module <NUM>. Accordingly, in some embodiments, tool <NUM> may permit boost module <NUM> to be installed into or removed from engine <NUM> as a unit while substantially maintaining the desired axial spacing between components of boost module <NUM>.

In reference to <FIG>, method <NUM> may also include moving holder <NUM> and boost module <NUM> away from the installed position shown in <FIG> along arrow C while holder <NUM> is engaged with stabilizer <NUM> at least until boost module <NUM> (or rotor <NUM>) has axially cleared a rotor mounting interface such as second flange <NUM> disposed on low-pressure shaft <NUM>. This may reduce the risk of damage by impact between boost module (or rotor <NUM>) and second flange <NUM>. Similarly, method <NUM> may also include moving holder <NUM> and boost module <NUM> toward the installed position shown in <FIG> along arrow C while holder <NUM> is engaged with stabilizer <NUM> at least while boost module <NUM> (or rotor <NUM>) axially overlaps the second flange <NUM> disposed on low-pressure shaft <NUM>.

Length L1 of guide pins <NUM> may be selected to provide the support for holder <NUM> over a desired distance along guide axis GA. For example, length L1 may be selected to be equal to or greater than length L2 between second flange <NUM> and an aft position of boost module <NUM> so that boost module <NUM> may be supported by stabilizer <NUM> until second flange <NUM> is cleared. As another example, length L1 may be selected to be equal to or greater than length L3 between first flange <NUM> (or the axial end of low-pressure shaft <NUM>) and an aft position of boost module <NUM> so that boost module <NUM> may be supported by stabilizer <NUM> until first flange <NUM> is cleared.

Claim 1:
An assembly comprising:
a gas turbine engine (<NUM>) including a bladed rotor (<NUM>) releasably mounted to a shaft (<NUM>) rotatable about a shaft axis (SA), the bladed rotor (<NUM>) being part of a compressor (<NUM>) of the gas turbine engine (<NUM>); and
a tool (<NUM>) for facilitating the installation and/or removal of the bladed rotor (<NUM>) releasably mounted to the shaft (<NUM>) of the gas turbine engine (<NUM>), the tool (<NUM>) including:
a stabilizer (<NUM>) having a shaft interface (<NUM>) attached to the shaft (<NUM>) of the gas turbine engine (<NUM>), the stabilizer (<NUM>) including a first guide counterpart; and
a rotor holder (<NUM>) having a rotor interface attached to the rotor (<NUM>), the rotor holder (<NUM>) having a second guide counterpart engaged with the first guide counterpart of the stabilizer (<NUM>), the first and second guide counterparts guiding movement of the rotor holder (<NUM>) relative to the stabilizer (<NUM>) along the shaft axis (SA) and substantially preventing movement of the rotor holder (<NUM>) relative to the stabilizer (<NUM>) transverse to the shaft axis (SA).