Patent Description:
Modem gas turbine engines include rotator features to enable manual rotation of one or more rotors of the gas turbine engine during engine maintenance and inspection. Typically, a rotator will be located on an idler gear of the accessory gearbox known to drive various components necessary for proper operation of the gas turbine engine, which may include a fuel pump, a lubricating oil pump, a hydraulic pump, an air turbine starter, an electric generator, and an engine starter, among other possible engine accessory components. Locating the rotator along with the driven engine accessories requires components along the load path between the gas turbine rotor and the rotator location to accommodate loads associated with engine operation as well as relatively higher loads associated with manual rotation of a gas turbine engine rotor. Further, access to the rotator often requires removal of an access cover on the accessory gearbox. Failure to replace the access cover following maintenance potentially introduces foreign object debris into the accessory gearbox, lubrication system, and/or other systems of the gas turbine engine depending on the location of the rotator-gearbox interface as well as increases risk of lubrication leakage potentially rendering the accessory gearbox inoperable. <CIT>, <CIT>, <CIT>, <CIT> and <CIT> relate to assemblies for gas turbine engines.

An exemplary rotator assembly of the present invention as defined in claim <NUM> is provided.

As disclosed herein is a rotator for rotating a gas turbine engine rotor without the assistance of the engine such as manual rotation of the gas turbine engine rotor for maintenance and inspection operations. By configuring the rotator to be selectively engageable to an input shaft of a transmission coupling the engine to an accessory gearbox rather than a component of the gearbox itself, the size and weight of many of the accessory gearbox components driving various engine accessories can be reduced as operational load path is restored, and rotator operation does not become a sizing constraint. A seal cap encircling a drive end of the rotator shaft isolates and protects the accessory gearbox and transmission interiors without requiring removal and reinstallation of an access cover while facilitating access to the drive end of the rotator auxiliary shaft. Further, motor and/or hand tool mounting provisions can be added to an exterior of accessory gearbox transmission and the drive end of such device configured to displace the rotator shaft into engagement with a shaft of the accessory gearbox transmission upon installation of the motor or hand tool. Additionally, the rotator shaft can be spring-loaded, facilitating automatic disengagement of the rotator shaft from the transmission shaft via a spring-generated restoring force acting on the rotator shaft after removal of the motor or hand tool.

While described in reference to a gas turbine engine rotator, features of the rotator disclosed herein can, in embodiments not forming part of the claimed invention, be incorporated into other applications in which manual rotation of a component would be beneficial. Within the aerospace industry, features of the disclosed rotator can be applied to a device for manual rotation of aircraft control surfaces or other aircraft actuation mechanisms. More generally, other applications are conceivable including manual rotation of industrial gas turbine engines, other turbomachines, or other industrial machine components.

<FIG> is a partial cross-sectional view of accessory gearbox <NUM> including transmission <NUM> rotationally coupling a gas turbine engine rotor to one or more engine accessories. Transmission <NUM> includes housing <NUM> enclosing input shaft <NUM> and output shaft <NUM>. Input shaft <NUM> extends along axis <NUM> from engine-side end 16A, where input shaft <NUM> rotationally couples to a shaft of a gas turbine engine, to auxiliary-side end 16B, where input shaft <NUM> selectively couples to rotator <NUM>. Between engine-side end 16A and auxiliary-side end 16B, input shaft <NUM> rotationally couples to output shaft <NUM> at gearing <NUM>. Output shaft <NUM> extends along axis <NUM> from gearing <NUM> to accessory gearbox <NUM>, where rotation of output shaft <NUM> drives one or more engine accessories which can include a fuel pump, a lubricating oil pump, a hydraulic pump, an air turbine starter, an electric generator, and an engine starter, among other possible engine accessory components.

The orientation of input shaft <NUM> is perpendicular to output shaft <NUM> in the embodiment depicted by <FIG> such that axes <NUM> and <NUM> are coplanar. However, input shaft <NUM> can be configured in other orientations relative to output shaft <NUM> compatible with the gas turbine engine application. For instance, axis <NUM> of input shaft <NUM> can be perpendicular to axis <NUM> of output shaft <NUM> without being coplanar, such as when axis <NUM> and axis <NUM> extend along mutually orthogonal directions. In other embodiments, input shaft <NUM> can extend along an oblique direction relative to output shaft <NUM>, whether axes <NUM> and <NUM> are coplanar or not. In still other embodiments, axis <NUM> of input shaft <NUM> and axis <NUM> of output shaft <NUM> can be offset and parallel.

In each embodiment, gearing <NUM> can be selected to accommodate the relative orientations of input shaft <NUM> and output shaft <NUM> as well as to accommodate the mechanical design of transmission <NUM>. In the depicted embodiment, gearing <NUM> includes intermeshing bevel gears 22A and 22B with straight or spiral profile gear teeth. Bevel gear 22A rotates with input shaft <NUM> while bevel gear 22B rotates with output shaft <NUM>. Each of bevel gears 22A and 22B can be integrally manufactured with, joined to, or otherwise mechanically attached to respective shafts <NUM> and <NUM>. In other embodiments, gearing <NUM> can take other potential configurations such as a spur gear pair, a spur gear and worm gear pair, or a spline coupling, among other possible configurations.

At engine-side end 16A, input shaft <NUM> includes spline <NUM>, or other mechanical coupling for connecting input shaft <NUM> to a drive shaft of the gas turbine engine. For example, input shaft <NUM> can be rotationally coupled to an outer end of radial drive shaft <NUM> (sometimes referred to as a tower shaft) relative to a centerline of the gas turbine engine. At the inner end, radial drive shaft <NUM> rotationally couples to a turbine shaft or a compressor shaft of the gas turbine engine. During operation of gas turbine engine, energy extracted by the turbine drives rotation of the turbine shaft, the compressor shaft, and the radial drive shaft, which in turn drives accessory gearbox <NUM> via input shaft <NUM>, output shaft <NUM>, and gearing <NUM>. However, when the gas turbine engine is not operating, rotator <NUM> can selectively engage auxiliary-side end 16B of input shaft <NUM> to manually rotate the gas turbine engine rotor facilitating maintenance and/or inspection of the gas turbine engine.

Input shaft <NUM> and output shaft <NUM> are laterally supported within housing <NUM> by one or more bearings <NUM>, the number and position of each bearing determined based on the specific configuration of transmission <NUM> as well as the load and stiffness requirements for transmission <NUM>, accessory gearbox <NUM>, and the gas turbine engine. In the depicted embodiment, bearings 29A, 29B, and 29C laterally support input shaft <NUM>. Bearing 29A supports input shaft <NUM> at a location between engine-side end 16A and gearing <NUM> while bearings 29B and 29C are adjacent to each other and located between gearing <NUM> and auxiliary-side end 16B along shaft <NUM>. Similarly, bearings 29D and 29E laterally support output shaft <NUM> adjacent to gearing <NUM>. The opposing side of output shaft <NUM> can be supported by another bearing and/or a coupling (not shown) of accessory gearbox <NUM>.

<FIG> and <FIG> are enlarged views of region A from <FIG> depicting features of rotator <NUM> and associated components in greater detail. <FIG> depicts rotator <NUM> disengaged from input shaft <NUM>, and <FIG> shows rotator <NUM> engaged to input shaft <NUM>. All components of rotator <NUM> are installed into bore <NUM> of housing <NUM> without requiring a cover to shield rotator <NUM> and/or internal components of accessory gearbox <NUM> and transmission <NUM> internal to housing <NUM>.

Rotator <NUM> includes auxiliary shaft <NUM> accessible through bore <NUM> of housing <NUM>. Auxiliary shaft <NUM> extends from outboard end 30A to inboard end 30B along axis <NUM>. One or more bearings <NUM> or bushings <NUM> laterally support auxiliary shaft <NUM> within bore <NUM>. As depicted, bearings 32A and 32B form a duplex bearing laterally supporting auxiliary shaft <NUM>. In other embodiments, bushings 33A and 33B can be used to provide lateral support of auxiliary shaft <NUM>. Restraint of auxiliary shaft <NUM> along axis <NUM> is provided by spring <NUM> concentrically positioned about auxiliary shaft <NUM> and, at opposite ends of spring <NUM>, engaging lip <NUM> of housing <NUM> and thrust washer <NUM>, which in turn, abuts thrust plate <NUM> manufactured integrally with or otherwise mechanically attached to auxiliary shaft <NUM>. As installed, spring <NUM> is at least partially compressed to bias auxiliary shaft <NUM> towards an exterior of housing <NUM>.

At inboard end 30B, auxiliary shaft <NUM> includes rotational coupling <NUM> for engaging coupling <NUM> at auxiliary-side end 16B of input shaft <NUM>. For instance, coupling <NUM> can be a spline along an outer diameter of auxiliary shaft <NUM> for engaging a corresponding spline formed along an inner diameter surface of input shaft <NUM>. In other embodiments, coupling <NUM> can be a key drive formed by one or more square or rectangular cross-section keys seated into auxiliary shaft <NUM>, and coupling <NUM> is a corresponding key socket formed by a complimentary keyway of input shaft <NUM>.

Seal cap <NUM> is an annular body in which radially outer surface 46A engages bore <NUM> and radially inner surface 46B guides auxiliary shaft <NUM> along axis <NUM>. Engagement of seal cap <NUM> can be achieved by providing an interference or location fit between outer surface 46A and bore <NUM>, restraining seal cap <NUM> axially and laterally with respect to axis <NUM> and housing <NUM>. In other embodiments, seal cap <NUM> can be retained within bore <NUM> using one or more snap rings. Further, seal cap <NUM> abuts bearing 32A and encloses bore <NUM> without obstructing access to outboard end 30A of auxiliary shaft <NUM>, which is equipped with socket <NUM> for facilitating connection to a motor and/or a hand tool, manually turning auxiliary shaft <NUM>, input shaft <NUM>, and thereby rotating the gas turbine engine rotor and accessory gearbox components. Outer seal groove <NUM> extends into seal cap <NUM> and circumferentially along outer surface 46A of seal cap <NUM> to house static seal <NUM>, and inner seal groove <NUM> extends into seal cap <NUM> and circumferentially along inner surface 46B of seal cap <NUM> to house sliding seal <NUM>. As depicted in <FIG>, static seal <NUM> is an o-ring and sliding seal <NUM> is a lip seal, although different static and sliding seal configurations can be used in other embodiments.

To utilize rotator <NUM>, drive end <NUM> of motor <NUM> or hand tool <NUM> is inserted into socket <NUM> of auxiliary shaft <NUM>. Drive end <NUM> can be a square driver and socket <NUM> can be a square socket. In some embodiments, socket <NUM> has square geometry common to both motor <NUM> and hand tool <NUM> driven ends <NUM>, such as a standard socket and driver size typical for hand tools. However, other drivers and socket combinations can be used including custom or standard hexagonal or other polygonal driver and socket combinations.

If motor <NUM> is used to drive auxiliary shaft <NUM>, motor <NUM> can be attached to housing <NUM> using bolt pattern <NUM>, which can be configured as any suitable circumferentially spaced pattern of blind, threaded holes. In another example, motor <NUM> can be attached to housing <NUM> by a twist lock whereby a portion of motor <NUM> inserts into a cavity defined by housing <NUM> and is trapped in place following a twisting action of motor attachment. In either arrangement and as a consequence of attaching motor <NUM> to housing <NUM>, drive end <NUM> displaces auxiliary shaft <NUM> along axis <NUM> and compresses spring <NUM> causing inboard end 30B of auxiliary shaft <NUM> to engage corresponding features on auxiliary-side end 16B of input shaft <NUM> as shown in <FIG>. For instance, length LT between mounting flange <NUM> and a distal end of drive end <NUM> can be equal to distance RS between an exterior of housing <NUM> and a bottom of socket <NUM> plus engagement distance ED necessary to rotationally couple to input shaft <NUM> between end 30B of auxiliary shaft <NUM> and auxiliary-side end 16B of input shaft <NUM>. Whether implemented as complimentary splines or as complimentary key drive and key socket arrangement, mating features of couplings <NUM> and <NUM> can be equipped with lead-in features that promote angular alignment of couplings <NUM> and <NUM> as coupling <NUM> axially engages coupling <NUM>. For instance, lead-in surfaces of couplings <NUM> and <NUM> can be equipped with a chamfer, a taper, or other feature tending to impose a torque about axis <NUM> of auxiliary shaft <NUM> to promote angular alignment. In other embodiments, coupling <NUM> can be angularly aligned to coupling <NUM> through manual manipulation of auxiliary shaft <NUM> using motor <NUM> or hand tool <NUM>. Electric, pneumatic, or hydraulic power applied to motor <NUM> drives rotation of auxiliary shaft <NUM>, input shaft <NUM>, and output shaft <NUM> as well as the gas turbine engine rotor rotationally coupled to engine-side end 16A of input shaft <NUM> and engine accessories of accessory gearbox <NUM> driven by rotation of output shaft <NUM>. In some embodiments, motor <NUM> can be equipped with reduction gearbox <NUM> such that for each rotation of motor <NUM>, drive end <NUM> and auxiliary shaft <NUM> rotate a fractional rotation.

Hand tool <NUM> can be used to drive rotation of auxiliary shaft <NUM> in lieu of motor <NUM>. In situations where hand tool <NUM> is a ratcheting hand tool, an operator of hand tool <NUM> exerts force along axis <NUM> during engagement of drive end <NUM> to socket <NUM>, compressing spring <NUM> and engaging inboard end 30B with auxiliary-side end 16B of input shaft <NUM>. Thereafter, the operator can rotate auxiliary shaft <NUM>, input shaft <NUM>, and output shaft <NUM> to turn the gas turbine engine rotor and engine accessories of accessory gearbox <NUM> while maintaining compression of spring <NUM>. In other embodiments, hand tool <NUM> can be equipped with mounting flange <NUM> to facilitate attachment to housing <NUM> at bolt pattern <NUM>. Like motor <NUM>, when hand tool <NUM> is attached to housing <NUM> using mounting flange <NUM>, the act of attaching mounting flange <NUM> to housing <NUM> engages socket <NUM> and simultaneously compresses spring <NUM> and engages inboard end 30B to auxiliary-side end 16B of input shaft <NUM>. For this purpose, length LT between a tip of drive end <NUM> and mounting flange <NUM> is equal to recess distance RS between an exterior surface of housing <NUM> and the bottom of socket <NUM> plus an engagement distance ED necessary to displace auxiliary shaft <NUM> into engagement with input shaft <NUM>. Once engaged, the operator can rotate auxiliary shaft <NUM>, input shaft <NUM>, and output shaft <NUM> as well as the gas turbine rotor and engine accessories of accessory gearbox <NUM> by applying a torque to hand tool <NUM>.

Whether motor <NUM> or hand tool <NUM> is used to rotate auxiliary shaft <NUM>, detaching motor <NUM>, mounting flange <NUM> or hand tool <NUM> from bolt pattern <NUM> or otherwise disengaging drive end <NUM> from socket <NUM> displaces auxiliary shaft <NUM> towards an exterior surface of housing <NUM> and disengages input shaft <NUM> under a restoring force from spring <NUM>. Accordingly, when gas turbine engine is operating, auxiliary shaft <NUM> is disengaged as shown in <FIG> eliminating unnecessary wear to auxiliary shaft <NUM>, and sliding seal <NUM>. This configuration also is accessible from an exterior of housing <NUM> without removing a cover as is typical in conventional rotator configurations.

<FIG> and <FIG> show rotator <NUM> in an orientation accessible from the bottom of accessory gearbox <NUM> when installed on the gas turbine engine and auxiliary shaft <NUM> displaces upward to engage input shaft <NUM>. This configuration allows maintenance to be performed easily on-wing after opening the engine cowl doors. However, auxiliary shaft <NUM> need not displace vertically to engage input shaft <NUM>, but can be configured to displace laterally or from a side of accessory gearbox <NUM> as installed on the gas turbine engine as shown in <FIG>. Still other configurations are possible. For instance, rotator <NUM> can be mounted to an aft or forward portion of accessory gearbox <NUM>. Alternatively, rotator <NUM> can be mounted to the top of accessory gearbox <NUM> such that auxiliary shaft <NUM> translates downward to engage input shaft <NUM> when installed on the gas turbine engine. As depicted, rotator <NUM> can be installed in any location and angle providing convenient access to auxiliary shaft <NUM> and input shaft <NUM>.

Claim 1:
An assembly for a gas turbine engine comprising:
a housing (<NUM>) enclosing a first shaft (<NUM>) extending from a first spline (<NUM>) at a first end to a second spline or a key-drive socket at a second end;
a second shaft (<NUM>)
extending from a third end accessible through an exterior wall of the housing to a third spline complementary to the second spline or a key-drive complimentary to the key-drive socket at a fourth end;
a thrust plate (<NUM>) extending from and rotatable with the second shaft;
a spring (<NUM>) circumscribing the second shaft and between the thrust plate and the housing;
wherein the spring biases the second shaft towards the exterior wall of the housing;
the assembly further comprising:
a seal cap (<NUM>) affixed within and enclosing a bore of the housing at the exterior of the housing and circumscribing the third end of the second shaft;
wherein the bore of the housing extends between the exterior wall of the housing and a housing lip (<NUM>);
a static seal (<NUM>) disposed within a first groove extending circumferentially about an outer diameter of the seal cap, the static seal engaging the bore of the housing; and
a lip seal (<NUM>) disposed within a second groove extending circumferentially about an inner diameter of the seal cap, the lip seal engaging the second shaft;
a radial drive shaft (<NUM>) rotationally coupled, in use, to a rotor of the gas turbine engine and rotationally coupled to the first shaft at the first end, and/or an accessory gearbox rotationally coupled in use, to a shaft coupled to the first shaft at a gearing (<NUM>), the accessory gearbox (<NUM>) rotationally coupled to one or more of a fuel pump, a lubricating oil pump, a hydraulic pump, an air turbine starter, a generator, and an engine starter; and
a duplex bearing (32A, 32B) or bushing affixed within the bore relative to and abutting the seal cap, laterally supporting the second shaft;
wherein the thrust plate is disposed between the duplex bearing or bushing and the lip (<NUM>) of the housing
wherein the spring (<NUM>) is positioned in the bore between the thrust plate (<NUM>) and the housing lip (<NUM>).