Patent ID: 12234019

DETAILED DESCRIPTION

FIG.1illustrates a gas turbine engine10having a principal rotational axis9. The engine10comprises an air intake12and a propulsive fan23that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine10comprises a core11that receives the core airflow A. The engine core11comprises, in axial flow series, a low pressure compressor14, a high-pressure compressor15, combustion equipment16, a high-pressure turbine17, a low pressure turbine19and a core exhaust nozzle20. A nacelle21surrounds the gas turbine engine10and defines a bypass duct22and a bypass exhaust nozzle18. The bypass airflow B flows through the bypass duct22. The fan23is attached to and driven by the low pressure turbine19via a shaft26and an epicyclic gearbox30.

In use, the core airflow A is accelerated and compressed by the low pressure compressor14and directed into the high pressure compressor15where further compression takes place. The compressed air exhausted from the high pressure compressor15is directed into the combustion equipment16where it is mixed with fuel and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines17,19before being exhausted through the nozzle20to provide some propulsive thrust. The high pressure turbine17drives the high pressure compressor15by a suitable interconnecting shaft27. The fan23generally provides the majority of the propulsive thrust. The epicyclic gearbox30is a reduction gearbox.

An exemplary arrangement for a geared fan gas turbine engine10is shown inFIG.2. The low pressure turbine19(seeFIG.1) drives the shaft26, which is coupled to a sun wheel, or sun gear,28of the epicyclic gear arrangement30. Radially outwardly of the sun gear28and intermeshing therewith is a plurality of planet gears32that are coupled together by a planet carrier34. The planet carrier34constrains the planet gears32to precess around the sun gear28in synchronicity whilst enabling each planet gear32to rotate about its own axis. The planet carrier34is coupled via linkages36to the fan23in order to drive its rotation about the engine axis9. Radially outwardly of the planet gears32and intermeshing therewith is an annulus or ring gear38that is coupled, via linkages40, to a stationary supporting structure24.

Note that the terms “low pressure turbine” and “low pressure compressor” as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e. not including the fan23) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft26with the lowest rotational speed in the engine (i.e. not including the gearbox output shaft that drives the fan23). In some literature, the “low pressure turbine” and “low pressure compressor” referred to herein may alternatively be known as the “intermediate pressure turbine” and “intermediate pressure compressor”. Where such alternative nomenclature is used, the fan23may be referred to as a first, or lowest pressure, compression stage.

The epicyclic gearbox30is shown by way of example in greater detail inFIG.3. Each of the sun gear28, planet gears32and ring gear38comprise teeth about their periphery to intermesh with the other gears. However, for clarity only exemplary portions of the teeth are illustrated inFIG.3. There are four planet gears32illustrated, although it will be apparent to the skilled reader that more or fewer planet gears32may be provided within the scope of the disclosure. Practical applications of a planetary epicyclic gearbox30generally comprise at least three planet gears32.

The epicyclic gearbox30illustrated by way of example inFIGS.2and3is of the planetary type, in that the planet carrier34is coupled to an output shaft via linkages36, with the ring gear38fixed. However, any other suitable type of epicyclic gearbox30may be used. By way of further example, the epicyclic gearbox30may be a star arrangement, in which the planet carrier34is held fixed, with the ring (or annulus) gear38allowed to rotate. In such an arrangement the fan23is driven by the ring gear38. By way of further alternative example, the gearbox30may be a differential gearbox in which the ring gear38and the planet carrier34are both allowed to rotate.

It will be appreciated that the arrangement shown inFIGS.2and3is by way of example only, and various alternatives are within the scope of the present disclosure. Purely by way of example, any suitable arrangement may be used for locating the gearbox30in the engine10and/or for connecting the gearbox30to the engine10.

By way of further example, the connections (such as the linkages36,40in theFIG.2example) between the gearbox30and other parts of the engine10(such as the input shaft26, the output shaft and the fixed structure24) may have any desired degree of stiffness or flexibility. By way of further example, any suitable arrangement of the bearings between rotating and stationary parts of the engine (for example between the input and output shafts from the gearbox and the fixed structures, such as the gearbox casing) may be used, and the disclosure is not limited to the exemplary arrangement ofFIG.2. For example, where the gearbox30has a star arrangement (described above), the skilled person would readily understand that the arrangement of output and support linkages and bearing locations would typically be different to that shown by way of example inFIG.2.

Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gearbox styles (for example star or planetary), support structures, input and output shaft arrangement, and bearing locations.

Optionally, the gearbox may drive additional and/or alternative components (e.g. the intermediate pressure compressor and/or a booster compressor).

Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown inFIG.1has a split flow nozzle18,20meaning that the flow through the bypass duct22has its own nozzle18that is separate to and radially outside the core engine nozzle20. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct22and the flow through the core11are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the disclosure may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine10may not comprise a gearbox30.

The geometry of the gas turbine engine10, and components thereof, is defined by a conventional axis system, comprising an axial direction (which is aligned with the rotational axis9), a radial direction (in the bottom-to-top direction inFIG.1), and a circumferential direction (perpendicular to the page in theFIG.1view). The axial, radial and circumferential directions are mutually perpendicular.

FIG.4shows schematically a system40for use on an aircraft.

The system40comprises a gas turbine engine151. In some embodiments, the gas turbine engine151may be a gas turbine engine10as described above.

Drive is taken from a shaft of the gas turbine engine151via an accessory gearbox153. A transmission150is mechanically coupled to the accessory gearbox153. In some implementations, the transmission150may be a continuously variable transmission.

A cabin blower system, indicated generally by the dashed line100, operates to take drive from an output of the transmission in the form of a transmission drive shaft106to drive mechanically a cabin blower compressor102. The cabin blower compressor102is arranged to compress air for delivery as an air stream154to a cabin152of an aircraft.

In the cabin blower system100, a flexible drive coupling114mechanically couples the transmission drive shaft106to a compressor drive shaft110. The compressor drive shaft110runs on a contactless bearing system, as will be described in more detail below with reference toFIG.5.

A portion of the cabin blower system100is shown in more detail inFIG.5.

An output108comprises an end portion of the transmission drive shaft106. The transmission drive shaft106runs on a mechanical bearing system112.

The output108is mechanically coupled to the compressor drive shaft110via the flexible drive coupling114. The compressor drive shaft110drives the compressor102.

The compressor drive shaft110runs on a contactless bearing system104. In the illustrated example, the contactless bearing system104comprises an air bearing system in the form of an air foil bearing system. The compressor drive shaft includes a centrifugal compressor and a plurality of rotor shaft elements that are arranged to interface with one or more radial air foil bearings and one or more thrust air foil bearings. The radial air foil bearing(s) and the thrust air foil bearing(s) are not shown inFIG.5.

The compressor drive shaft110may be formed of one or more compressor drive shaft portions. Alternatively, the compressor drive shaft110may be made as a single piece.

The contactless bearing system104may be disposed relatively near to the flexible drive coupling114. The mechanical bearing system112may be disposed relatively near to the flexible drive coupling114.

The lateral stiffness of the mechanical bearing system112is greater than the lateral stiffness of the contactless bearing system104. The lateral stiffness of the contactless bearing system104is greater than the lateral stiffness of the flexible drive coupling114.

The axial stiffness of the mechanical bearing system112is greater than the axial stiffness of the contactless bearing system104. The axial stiffness of the contactless bearing system104is greater than the axial stiffness of the flexible drive coupling114.

The flexible drive coupling114has a lower axial stiffness than the contactless bearing system104. The flexible drive coupling114has a lower lateral stiffness than the contactless bearing system104.

The flexible drive coupling114has a lower axial stiffness than the mechanical bearing system112. The flexible drive coupling114has a lower lateral stiffness than the mechanical bearing system112.

As a consequence of tolerance stack ups, in use, the transmission drive shaft106may be urged to run out of true and rotate non-concentrically with the compressor drive shaft110.

The flexible drive coupling114provides a means for correcting misalignment between the transmission drive shaft106and the compressor drive shaft110. In use, the lower lateral stiffness of the flexible drive coupling114, in relation to the lateral stiffness of the contactless bearing system104, allows the flexible drive coupling114to continually flex through its rotation to correct any misalignment between the transmission drive shaft106and the compressor drive shaft110caused by tolerance stack ups. As such, the compressor rotor shaft will be able to run concentric and parallel with the contactless bearing system.

The contactless bearing system104may take the form of an air bearing system or a magnetic bearing system. The air bearing system may be an air foil bearing system or an aerostatic bearing system.

The flexible drive coupling114may comprise a form metal bellows arrangement. In some embodiments, the flexible drive coupling114may comprise a diaphragm, a flexible beam, a flexible jaw pin and bush, a disc pack, a grid coupling, a spring or a magnetic arrangement.

FIG.6shows schematically an aircraft50. The aircraft50has a fuselage501with a cabin502therein. A first wing503and a second wing504extend away from the fuselage501in opposite directions. A first gas turbine engine505is connected to the first wing504. A second gas turbine engine506is connected to the second wing505. The first gas turbine engine505and/or the second gas turbine engine506may be any gas turbine engine for an aircraft. For example, the first gas turbine engine505and/or the second gas turbine engine506may be similar to or the same as the gas turbine engine10disclosed herein.

A first cabin blower system201according to the present disclosure is associated with the first gas turbine engine505. The first cabin blower system200operates to compress and deliver air to the cabin502of the aircraft50.

A second cabin blower system202according to the present disclosure is associated with the second gas turbine engine506. The second cabin blower system202operates to compress and deliver air to the cabin502of the aircraft50.

The first cabin blower system201and/or the second cabin blower system202may be any cabin blower system disclosed herein. For instance, the first cabin blower system201and/or the second cabin blower system202may be similar to or the same as the cabin blower system100disclosed herein.

FIG.7shows an example of a drive transfer system70. The drive transfer system70may be suitable for use in or on an aircraft. The drive transfer system70may also be suitable for other uses, including, for example, in other transport applications.

The drive transfer system70comprises a first drive shaft701running on a contactless bearing system702and a second drive shaft704. The first drive shaft701and the second drive shaft704are connected via a flexible drive coupling703.

The first drive shaft701and the second drive shaft704are axially aligned with each other.

The flexible drive coupling703has a lower lateral stiffness than the contactless bearing system702. The flexible drive coupling703has a lower axial stiffness than the contactless bearing system702.

The contactless bearing system702may take the form of an air bearing system or a magnetic bearing system. The air bearing system may comprise an air foil bearing system. The air bearing system may comprise an aerostatic bearing system.

The flexible drive coupling703may comprise a form metal bellows arrangement. In some embodiments, the flexible drive coupling703may comprise a diaphragm, a flexible beam, a flexible jaw pin and bush, a disc pack, a grid coupling, a spring or a magnetic arrangement.

The second drive shaft704may run on a mechanical bearing system or a contactless bearing system. The second drive shaft704may run on a similar or substantially the same bearing system as the first drive shaft701.

It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.