Patent Description:
Cabin blower systems are known for pressurising the cabin of an aircraft. Cabin blower systems provide an airflow to cabins of an aircraft at a controlled temperature and pressure for ventilation. The pressurised air from the cabin blower can also be used for other aircraft functions e.g. wing anti-icing, fuel tank inerting, cargo heating, and other aircraft systems pressurisation (e.g. hydraulic and potable water), A cabin blower system includes a cabin blower typically driven by a compressor, which in turn is driven by a shaft of the gas turbine engine via an accessory gearbox. As it is not desirable for the compressor of the cabin blower to rotate at a speed determined by the particular operating point of the gas turbine at any particular moment, the cabin blower system normally includes a variable drive system to vary the compressor speed and keep the cabin airflow and pressure within acceptable limits. The cabin blower is driven by the variable drive system, which in turn is connected to, and driven by, the accessory gearbox. The accessory gearbox is arranged in a core engine accessory bay, which is normally quite congested. As the variable drive system includes several components, such as electrical motors/generators and a summing gearbox, and is integrated with the cabin blower into a single combined unit, known cabin blower systems are bulky and present several installation and integration challenges.

There is therefore a need for a cabin blower system with improved installation and integration capabilities.

European Patent Application publication <CIT> describes a cabin blower system. The cabin blower system comprises a transmission configured to receive mechanical power from a gas turbine in the form of a first transmission input; and an electrical circuit comprising first and second electrical machines and a power management system. In a blower mode, the first electrical machine is configured to receive mechanical power from the gas turbine engine and act as a generator to provide electrical power to the power management system, and the second electrical machine is configured to act as a motor providing mechanical power to the transmission in the form of a second transmission input, the second electrical machine being driven by electrical power from the power management system.

UK Patent Application publication <CIT> relates to an integrated auxiliary power and environmental control unit. The unit comprises a prime mover, a variable geometry compressor, and a controlled emission turbine which is shaft-coupled to the compressor and cooperating with the compressor to form an environmental control unit.

US Patent Application publication <CIT> relates to a hybrid drive system for transferring power from a gas turbine engine of an aircraft. The system includes a planetary gear set, a first motor-generator and a second motor-generator.

US Patent Publication <CIT> relates to an all electric environmental control system for aircraft.

The scope of protection is defined in the appended claims.

According to claim <NUM>, there is provided a gas turbine engine including an engine core including a compressor, a combustor, and a turbine, the compressor being connected to the turbines through a respective shaft; an accessory gearbox arranged within an accessory gearbox casing; and a cabin blower system adapted to be driven by the accessory gearbox and comprising: an electric variator comprising a first electrical machine connected to a drive pad of the accessory gearbox by a first shaft arranged along a first axis, a second electrical machine connected to a second shaft arranged along a second axis, and a power management system interconnecting the first and second electrical machines and controlling whether each of the first and second electrical machines operate as a motor or a generator; a differential gearbox having a first input connected to a drive pad of the accessory gearbox to receive drive therefrom, a second input connected to the second shaft of the second electrical machine, and an output; and a cabin blower comprising a compressor driven by the output of the differential gearbox by a third shaft, the compressor comprising an air inlet and an air outlet.

According to claim <NUM>, the cabin blower, the first electrical machine, the second electrical machine and the differential gearbox are configured as modules, and the first and second electrical machines are arranged on a first side of the accessory gearbox casing and the cabin blower is arranged on a second side of the accessory gearbox casing opposite the first side.

In another group of embodiments which are not covered by the claims, the first electrical machine, the second electrical machine, and the cabin blower are arranged on a same side of the accessory gearbox casing such that the third shaft is not coaxial with either the first or the second shaft.

The cabin blower, the first electrical machine, the second electrical machine, and the differential gearbox are configured as modules, such that the cabin blower system may be configured to best fit in the core engine accessory bay where the accessory gearbox is arranged.

Contrary to the known cabin blower systems, the cabin blower, the first electrical machine, the second electrical machine, and the differential gearbox of the present disclosure may be split and arranged to be housed where space is available around the accessory gearbox.

Depending on the available space in the core engine accessory bay, the cabin blower, first electrical machine, second electrical machine, and differential gearbox may be split in two or more groups of modules and arranged on a single side of the accessory gearbox in examples not forming part of the claimed invention, or on two different sides of the accessory gearbox casing. The two different sides of the accessory gearbox casing are opposite to each other according to the claimed invention.

The latter arrangements, with the modules split in groups on opposite sides of the accessory gearbox, may be particularly advantageous, as it may allow for a more compact arrangement and may reduce overhang and unbalance.

For example, the electric variator may be arranged on a first side of the accessory gearbox casing and the differential gearbox and/or the cabin blower may be arranged on a second side of the accessory gearbox casing. The first side of the accessory gearbox casing may be opposite to the second side of the accessory gearbox casing.

The electric variator and the differential gearbox may be arranged on a common axis. Alternatively, the electric variator and the differential gearbox may be arranged on separate axes.

The electric variator and the cabin blower may be arranged on a common axis. Alternatively, the electric variator and the cabin blower may be arranged on separate axes.

The second side of the accessory gearbox is be opposite the first side of the accessory gearbox.

The accessory gearbox may include a plurality of drive output pads to connect with a number of engine accessories, including fuel and oil pumps.

The accessory gearbox is arranged within an accessory gearbox casing. The accessory gearbox and accessory gearbox casing may be arranged either axially, substantially parallel to a longitudinal axis of the gas turbine engine, or circumferentially about the longitudinal axis of the gas turbine engine.

The first and second electrical machines of the electric variator may be either ganged and coaxial, i.e. such that the first and second shafts are coaxial, or separate and arranged such that the first and second shafts are arranged on different axes.

At least one of the first and second shafts may be coaxial with a drive output pad of the plurality of drive output pads of the accessory gearbox.

The differential gearbox may be connected to, and coaxial with, a drive output pad of the plurality of drive output pads of the differential gearbox.

The cabin blower compressor may be arranged coaxially with the differential gearbox. The cabin blower compressor may be a centrifugal fan, one or more impellers, or any other known devices adapted to increase pressure of a gas.

The first shaft, the second shaft, and the third shaft may be arranged on respective, non-coincident axes.

The first and second electrical machines may be ganged and the first and second shafts may be coaxial with a drive output pad of the differential gearbox.

The cabin blower and the differential gearbox may be ganged and arranged on one side of the accessory gearbox.

The differential gearbox may be an epicyclic gearbox comprising a summing gearbox and a step-up, amplifying gearbox.

The summing gearbox may be an epicyclic gearbox in a planetary configuration and may comprise a sun gear, a plurality of planet gears, a carrier connecting the planet gears, and a ring gear.

The first shaft may connect the accessory gearbox and the first electrical machine to drive the planet gears of the summing gearbox through the carrier, and the second shaft may connect the second electrical machine to the sun gear of the summing gearbox.

The step-up, amplifying gearbox may be an epicyclic gearbox in a star arrangement and may comprise a sun gear connected to the third shaft to drive the cabin blower.

The gas turbine engine may further comprise a fan air offtake adapted to feed air to the cabin blower through the air inlet.

The gas turbine engine may comprise a bypass duct, and the fan air offtake may be arranged in the bypass duct.

The gas turbine engine may further comprise a bifurcation, or splitter, spanning the bypass duct and comprising a leading edge, a trailing edge, and a first and a second sidewall connecting the leading edge and the trailing edge. The fan air offtake may be either a forward facing offtake arranged on the bifurcation leading edge, or either a flush scoop or forward facing scoop on either the first or second sidewalls of the bifurcation.

The gas turbine engine may further comprise a heat exchanger to cool the cabin blower system. The heat exchanger may be either a surface heat exchanger or matrix cooler.

The heat exchanger may be a surface heat exchanger mounted from fairings of the engine core.

The compressor of the cabin blower may be a dual impeller, mounted from a single side of the gearbox casing. Alternatively, each impeller of the dual impeller may be mounted on opposite sides of the gearbox casing on a coaxial shaft.

In the present disclosure, upstream and downstream are with respect to the air flow through the compressor, and front and rear is with respect to the gas turbine engine, i.e. the fan being in the front and the turbine being in the rear of the engine. As used herein, forward refers to the direction from the rear to the front of the gas turbine engine.

The gas turbine engine may comprise an upper bifurcation, or upper splitter, and a lower bifurcation, or lower splitter, spanning the bypass duct and the fan air offtake may be arranged either on the upper splitter, or the lower splitter.

With reference to <FIG>, a gas turbine engine, generally indicated at <NUM>, has a longitudinal axis <NUM>. The engine <NUM> comprises, in axial flow series, an air intake <NUM>, a propulsive fan <NUM>, an intermediate pressure compressor <NUM>, a high-pressure compressor <NUM>, combustion equipment <NUM>, a high-pressure turbine <NUM>, an intermediate pressure turbine <NUM>, a low-pressure turbine <NUM> and an exhaust nozzle <NUM>. A nacelle <NUM> generally surrounds the engine <NUM> and defines both the intake <NUM> and the exhaust nozzle <NUM>.

The gas turbine engine <NUM> works in the conventional manner so that air entering the intake <NUM> is accelerated by the fan <NUM> to produce two air flows: a first air flow into the intermediate pressure compressor <NUM> and a second air flow which passes through a bypass duct <NUM> to provide propulsive thrust. The intermediate pressure compressor <NUM> compresses the air flow directed into it before delivering that air to the high pressure compressor <NUM> where further compression takes place.

The compressed air exhausted from the high-pressure compressor <NUM> is directed into the combustion equipment <NUM> where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines <NUM>, <NUM>, <NUM> before being exhausted through the nozzle <NUM> to provide additional propulsive thrust. The high <NUM>, intermediate <NUM> and low <NUM> pressure turbines drive respectively the high pressure compressor <NUM>, intermediate pressure compressor <NUM> and fan <NUM>, each by suitable interconnecting shaft.

Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example, such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further, the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.

<FIG> illustrates an example of gas turbine engine <NUM>' comprising a gearbox <NUM> provided in the drive train from a turbine to the fan.

The gas turbine engine <NUM>' has a longitudinal axis <NUM> and comprises a propulsive fan <NUM> and an engine core <NUM> comprising in axial flow series, a low pressure compressor <NUM>, a high-pressure compressor <NUM>, combustion equipment <NUM>, a high-pressure turbine <NUM>, a low pressure turbine <NUM> and a core exhaust nozzle <NUM>. A nacelle <NUM> surrounds the gas turbine engine <NUM>' and defines a bypass duct <NUM> and a bypass exhaust nozzle <NUM>.

<FIG> illustrates in more detail the gas turbine engine <NUM>' and the gearbox <NUM> of <FIG>. The gearbox <NUM> is of the epicyclic type. The low pressure turbine <NUM> (see <FIG>) drives the shaft <NUM>, which is coupled to a sun wheel, or sun gear, <NUM> of the gearbox <NUM>. The planet carrier <NUM> is coupled via linkages <NUM> to the fan <NUM> in order to drive its rotation about the longitudinal axis <NUM>.

The epicyclic gearbox <NUM> illustrated by way of example in <FIG> is of the planetary type, in that the planet carrier <NUM> is coupled to an output shaft via linkages <NUM>, with the ring gear <NUM> fixed.

<FIG> illustrate an embodiment of a modular cabin blower system <NUM> according to the disclosure connected to an accessory gearbox <NUM> arranged within an accessory gearbox casing <NUM>.

The cabin blower system <NUM> includes a cabin blower <NUM>, an electric variator <NUM>, and a differential gearbox <NUM>.

The cabin blower <NUM> comprises a compressor <NUM>, an air inlet <NUM> and an air outlet <NUM>. Air from the engine, for example from the bypass duct of the engine, is fed to the compressor <NUM> of the cabin blower <NUM> through the air inlet <NUM>, compressed by the compressor <NUM>, which in turn feeds the compressed air to the cabin of the aircraft via the air outlet <NUM>. The compressor <NUM> may be a blower, or an impeller, or a pair of impellers.

The electrical variator <NUM> includes a first electrical machine <NUM>, a second electrical machine <NUM>, and a power management system <NUM>.

The first and second electrical machines <NUM>, <NUM> are each configured to work as electric motor and/or power generators. The power management system <NUM> interconnects the first and second electrical machines <NUM>, <NUM> and controls whether each of the first and second electrical machines <NUM>, <NUM> work as electric motor or power generator to drive the cabin blower <NUM> within specific operating conditions regardless the operating point of the gas turbine engine.

The differential gearbox <NUM> has a first input connected to a drive output pad <NUM> of the accessory gearbox <NUM> to receive drive therefrom.

The first electrical machine <NUM> is also connected to the same drive output pad <NUM> in this embodiment; in other embodiments, the first electrical machine <NUM> may be on a different drive output pad of the accessory gearbox <NUM>.

The differential gearbox <NUM> has a second input connected to the second electrical machine <NUM>, and an output connected to the cabin blower <NUM>.

The electrical variator <NUM> and differential gearbox <NUM> are arranged on a first side <NUM> of the accessory gearbox casing <NUM>; the cabin blower <NUM> is arranged on a second side <NUM> of the accessory gearbox casing <NUM> opposite the first side <NUM>.

The cabin blower <NUM>, the electrical variator <NUM>, and differential gearbox <NUM> are coaxially arranged along a common axis <NUM>.

<FIG> illustrates in more detail the arrangement of the differential gearbox <NUM> and how the first electrical machine <NUM>, the second electrical machine <NUM>, the differential gearbox <NUM>, and the cabin blower <NUM> are connected to each other.

The differential gearbox <NUM> is an epicyclic gearbox <NUM> comprising a summing gearbox <NUM> and a step-up, amplifying gearbox <NUM>.

A common ring gear <NUM> mutually connects the summing gearbox <NUM> and the amplifying gearbox <NUM>. The summing gearbox <NUM> is an epicyclic gearbox in a planetary arrangement and includes a sun gear <NUM>, a plurality of planet gears <NUM>, a carrier <NUM> connecting the planet gears <NUM>, and the ring gear <NUM>. The planet gears <NUM>, according to the planetary arrangement, rotate about their own axis and precess around the sun gear <NUM>.

The amplifying gearbox <NUM> is an epicyclic gearbox in a star arrangement and comprises a sun gear <NUM>, a plurality of planet gears <NUM>, and the ring gear <NUM>. The planet gears <NUM>, according to the star arrangement, are held stationary with respect to the sun gear <NUM>, and rotate about their own axis only.

A first shaft <NUM>, driven by the drive output pad <NUM> of the accessory gearbox <NUM>, is connected to the first electrical machine <NUM> and to the differential gearbox <NUM>, in particular to the planet gears <NUM> of the summing gearbox <NUM> via the carrier <NUM>. The first shaft <NUM> represents the first input of the summing gearbox <NUM>. The first shaft <NUM> passes through the accessory gearbox casing <NUM> in correspondence of the first side <NUM> to connect the drive output pad <NUM> and the carrier <NUM>. The first shaft <NUM> is connected at a first end portion to the accessory gearbox <NUM> and at a second end portion to the summing gearbox <NUM>.

A second shaft <NUM> is connected to the differential gearbox <NUM>, in particular to the sun gear <NUM> of the summing gearbox <NUM>. The second shaft <NUM> represents the second input of the differential gearbox <NUM>. The second shaft <NUM> is arranged outside the accessory gearbox <NUM> and does not pass through the accessory gearbox casing <NUM>.

A third shaft <NUM> is connected at a first end portion to the differential gearbox <NUM>, in particular to the sun gear <NUM> of the amplifying gearbox <NUM>, and at a second end portion is connected to, and drives, the cabin blower <NUM>, in particular the compressor <NUM>. The third shaft <NUM> represents the output of the differential gearbox <NUM>. The third shaft <NUM> connects the differential gearbox <NUM> arranged on the first side <NUM> of the accessory gearbox casing <NUM> to the cabin blower <NUM> arranged on the second side <NUM> of the accessory gearbox casing <NUM>, passing all the way through the accessory gearbox <NUM>.

In the embodiment of <FIG>, the first, second and third shafts <NUM>, <NUM>, <NUM> are coaxial and arranged along the common axis <NUM>.

<FIG> illustrate a cabin blower system <NUM>' according to an embodiment similar to the embodiment of <FIG>, and differing therefrom for the arrangement of the differential gearbox <NUM>. Like features between <FIG> and <FIG> are given like reference numerals, and will not be described in detail again in relation to <FIG>.

In the <FIG> embodiment the electrical variator <NUM> is arranged on the first side <NUM> of the accessory gearbox casing <NUM>, the cabin blower <NUM> is arranged on the second side <NUM> of the accessory gearbox casing <NUM>, and the differential gearbox <NUM> is integrated with the accessory gearbox <NUM> and arranged within the accessory gearbox casing <NUM>. The cabin blower system <NUM>' is particularly compact and suitable where limited space is available. In alternative embodiments, for example in the cabin blower system <NUM>" illustrated in <FIG>, the differential gearbox <NUM> is arranged only partially within the accessory gearbox casing <NUM> and protrudes thereof. However, without limitation, integrating the differential gearbox, even only partially, within the differential gearbox may add complexity to the cabin blower system.

The first shaft <NUM>' is connected at a first end portion to the first electrical machine <NUM> and at a second end portion to the differential gearbox <NUM>, in particular the carrier <NUM> of the summing gearbox <NUM>. The first shaft <NUM>' is driven by the accessory gearbox <NUM>, which is arranged between the electrical variator <NUM> and the differential gearbox <NUM>. In details, gears of the accessory gearbox <NUM> are connected to, and drive, the first shaft <NUM>' and are arranged at an axial position along the first shaft <NUM>' between the differential gearbox <NUM> and the first electrical machine <NUM>.

The second shaft <NUM>' connects the second electrical machine <NUM> to the sun gear <NUM> of the summing gearbox <NUM>. As the sun gear <NUM> is arranged within the accessory gearbox <NUM> and the second electrical machine <NUM> is arranged outside the accessory gearbox <NUM>, the second shaft <NUM>' passes through the first side <NUM> of the accessory gearbox casing <NUM> and is longer than the second shaft <NUM> of the <FIG> embodiment.

The third shaft <NUM>' is connected to the differential gearbox <NUM>, in particular to the sun gear <NUM> of the amplifying gearbox <NUM>, and drives the cabin blower <NUM>. As the sun gear <NUM> is arranged within the accessory gearbox <NUM> and the cabin blower <NUM> is arranged outside the accessory gearbox <NUM> on the second side <NUM>, the third shaft <NUM>' passes through the second side <NUM> of the accessory gearbox casing <NUM>. The third shaft <NUM>' is shorter than the third shaft <NUM> of the <FIG> embodiment.

Like in the embodiment of <FIG>, the first, second and third shafts <NUM>', <NUM>', <NUM>' are coaxial and arranged along the common axis <NUM>.

<FIG> illustrate various embodiments of cabin blower systems according to the disclosure, wherein the electrical variator <NUM> is arranged on the first side <NUM> of the accessory gearbox casing <NUM>, and the cabin blower <NUM> is arranged on the second side <NUM> of the accessory gearbox casing <NUM>. Like features between <FIG> and <FIG> are given like reference numerals, and will not be described in detail again in relation to <FIG>.

In detail, <FIG> illustrates a cabin blower system <NUM> wherein the differential gearbox <NUM> is partly integrated in the accessory gearbox <NUM> and protrudes from the second side <NUM> of the accessory gearbox casing <NUM>. The electric variator <NUM> is arranged on the first side <NUM> of the accessory gearbox casing <NUM>.

The first electrical machine <NUM> and the second electrical machines <NUM> are connected to the first shaft, and the second shaft, not shown for sake of simplicity. The first shaft and the second shaft are not coaxial. In particular the first shaft is arranged on a first axis <NUM>, and the second shaft is arranged on a second axis <NUM>. The first axis <NUM> and the second axis <NUM> may, as in the illustrated embodiment, or may not, be parallel. The first shaft is directly connected to the differential gearbox <NUM>; the second shaft is connected to the differential gearbox <NUM> through known, and therefore not illustrated, gear systems.

Connected to the differential gearbox <NUM> and arranged on the second side <NUM> of the accessory gearbox <NUM> there is the cabin blower <NUM> with the compressor <NUM>, the air inlet <NUM> and the air outlet <NUM>. The compressor <NUM> is driven by a third shaft, not shown for sake of simplicity, arranged on a third axis <NUM>, coaxial to the first axis <NUM>.

<FIG> illustrates a cabin blower system <NUM>' which differs from the cabin blower system <NUM> of <FIG> in that the first axis <NUM> and the third axis <NUM> are not coaxial. The differential gearbox <NUM> and the cabin blower <NUM> are arranged such that the third axis <NUM> is parallel to the first axis <NUM> and the second axis <NUM>, and is equidistant therefrom. In not illustrated embodiments, the third axis <NUM> may be closer to either the first axis <NUM> or the second axis <NUM> than the second axis <NUM> or the first axis <NUM>, respectively. In further not illustrated embodiment, the first, second, and third axis <NUM>, <NUM>, <NUM> may not be mutually parallel; for example, the first and second axis <NUM>, <NUM> may be mutually parallel and the third axis <NUM> may be arranged at an angle thereto. Known, and therefore not illustrated, gear systems connect the first and second shaft to the differential gearbox <NUM>.

<FIG> illustrates a cabin blower system <NUM>" which differs from the cabin blower system <NUM>' of <FIG> in that the differential gearbox <NUM> is not integrated in the accessory gearbox <NUM> and is arranged outside thereof. The differential gearbox is arranged on the second side <NUM> of the accessory gearbox casing <NUM> between the accessory gearbox <NUM> and the cabin blower <NUM>. In a not illustrated embodiment, the differential gearbox <NUM> and the cabin blower <NUM> are arranged such that the third axis <NUM> is coaxial to the first axis, as in the embodiment of <FIG>. Such embodiment would differ from the embodiment of <FIG> in that the differential gearbox <NUM> is not integrated in the accessory gearbox <NUM>.

<FIG>, and <FIG> illustrate further embodiments of cabin blower systems according to the disclosure wherein the first, second, and third shafts (not illustrated for sake of simplicity) are arranged such that their respective first, second, and third axis are coaxial and arranged on a common axis <NUM>.

The electrical variator <NUM> is arranged on the first side <NUM> of the accessory gearbox <NUM> and the first and second electrical machines <NUM>, <NUM> are arranged coaxially. The first electrical machine <NUM> is arranged between the second electrical machine <NUM> and the accessory gearbox <NUM>. In not illustrated embodiments, the second electrical machine <NUM> is arranged between the first electrical machine <NUM> and the accessory gearbox <NUM>.

The differential gearbox <NUM> is arranged on the second side <NUM> of the accessory gearbox casing <NUM> and may be partly integrated in the accessory gearbox <NUM>, as in the cabin blower system <NUM> of <FIG> and in the cabin blower system <NUM>" of <FIG>, or arranged outside the accessory gearbox <NUM> as in the cabin blower system <NUM>'of <FIG>.

The cabin blower system <NUM>" of <FIG> differs from the cabin blower systems <NUM>, <NUM>' of <FIG> in that it includes a cabin blower <NUM> different from the cabin blower <NUM>. The cabin blower <NUM> comprises a compressor <NUM> in the form of a pair of impellers <NUM> and an air inlet system <NUM> comprising a manifold <NUM> and two inlet ducts <NUM>. The impellers <NUM> are arranged back to back in order to minimise/eliminate thrust load. In not illustrated embodiments, the impellers may be positioned on opposing faces of the accessory gearbox, for example on a coaxial shaft.

Air from the engine, for example from the bypass duct of the engine, is fed to the manifold <NUM> and in turn to the impellers <NUM> through the air inlet ducts <NUM>, compressed by the impellers <NUM>, which in turn feeds the compressed air to the cabin of the aircraft via the air outlet <NUM>. Each inlet duct <NUM> feeds a respective impeller <NUM>.

<FIG> illustrates an embodiment of cabin blower system <NUM> wherein the electric variator <NUM> is arranged on the first side <NUM> of the accessory gearbox casing <NUM> with the first electrical machine <NUM> and the second electrical machine <NUM> coaxially arranged. In other words, a first and a second shaft (not shown for sake of simplicity) are connected to the first electrical machine <NUM> and the second electrical machine <NUM>, respectively, and are arranged along respective first and second axis <NUM>, <NUM>. The first and second axis <NUM>, <NUM> are coaxial. The differential gearbox <NUM> and the cabin blower <NUM> are arranged on the second side <NUM> of the accessory gearbox casing <NUM>. The cabin blower <NUM> includes a compressor <NUM> driven by a third shaft, not shown for sake of simplicity, arranged on a third axis <NUM>. The first and second axis <NUM>, <NUM> are parallel to the third axis <NUM>, and mutually distanced. The first shaft and the second shaft are connected to the differential gearbox <NUM> through a known, and therefore not illustrated, gear system.

<FIG> illustrate embodiments of cabin blower systems wherein the cabin blower <NUM>, the electric variator <NUM>, and the differential gearbox <NUM> are all arranged on a same side of the accessory gearbox casing <NUM>. These embodiments are not within the scope of the claims. For simplicity and consistency with the nomenclature used so far, the cabin blower <NUM>, the electric variator <NUM>, and the differential gearbox <NUM> may be seen as arranged on the second side <NUM> of the accessory gearbox casing <NUM>, but the skilled person would recognise that any side of the accessory gearbox casing <NUM> may be referred to as the second side <NUM>.

In <FIG> there is illustrated an embodiment of a cabin blower system <NUM>, wherein the first and second machines <NUM>, <NUM> of the electric variator <NUM> are arranged such that the first and second shaft (not illustrated for sake of simplicity) are coaxially arranged along coincident first and second axis <NUM>, <NUM>.

The cabin blower system <NUM> further comprise a differential gearbox <NUM> partially integrated within the accessory gearbox <NUM> as in the embodiments of <FIG>, <FIG>, and <FIG>. A known gear system connects the first and second shaft to the differential gearbox <NUM>.

The cabin blower <NUM> comprises a compressor <NUM> driven by the third shaft (not shown) arranged along a third axis <NUM>, parallel to, but not coincident with, the first and second axis <NUM>, <NUM>.

<FIG> illustrates a further embodiment of a cabin blower system <NUM>' which differs from the cabin blower system <NUM> of <FIG> in that the differential gearbox <NUM> is not partially integrated with accessory gearbox <NUM>. The accessory gearbox <NUM> protrudes from the accessory gearbox casing <NUM> and is arranged between the accessory gearbox <NUM> and the cabin blower <NUM>.

<FIG> illustrates another embodiment of a cabin blower system <NUM>" which differs from the cabin blower systems <NUM> and <NUM>' of <FIG> in that the differential gearbox <NUM> is arranged at a distance from the accessory gearbox <NUM>. In detail, the cabin blower system <NUM>" comprises an electric variator <NUM> with first and second electric machines <NUM>, <NUM> arranged adjacent to the accessory gearbox <NUM> (as in the embodiments of <FIG>), and a differential gearbox <NUM>, connected to the first and second electrical machines <NUM>, <NUM> through known gears (not shown for sake of simplicity) and arranged at a distance from the accessory gearbox <NUM>. As in the embodiments of <FIG> the first and second shaft (not illustrated) connected to the first and second electric machines <NUM>, <NUM> are arranged along the first and second axis <NUM>, <NUM>, respectively. The cabin blower system <NUM>" further comprises a cabin blower <NUM> connected to the differential gearbox through the third shaft (not illustrated) such as to be arranged at a distance from the accessory gearbox <NUM>. The third shaft is arranged along the third axis <NUM>. The first and second axis <NUM>, <NUM> and the third axis <NUM> are parallel and mutually distanced.

The cabin blower systems according to the disclosure and illustrated with reference to <FIG> comprise an accessory gearbox <NUM> that can be mounted either axially or circumferentially in the gas turbine engine.

<FIG> illustrates an embodiment of gas turbine engine according the disclosure wherein the accessory gearbox <NUM> is arranged axially, or in other words substantially parallel to the longitudinal axis <NUM> of the gas turbine engine, in a core accessory bay <NUM>. The gas turbine engine may be either a direct drive gas turbine engine as the gas turbine engine <NUM> of <FIG>, or a geared gas turbine engine as the gas turbine engine <NUM>' of <FIG>.

The accessory gearbox <NUM> comprises a plurality of drive output pads <NUM>, one of which is connected to a cabin blower system <NUM> of the type described with reference to <FIG>. Engine and airframe accessories (not illustrated), such for example fuel and oil pumps, are connected to the remaining drive output pads <NUM>.

Fan air is scooped from the fan stream in the bypass duct <NUM> by means of a fan air offtake <NUM> connected to the air inlet of the cabin blower, compressed by the compressor (or impellers) of the cabin blower, and delivered through the air outlet <NUM> to the aircraft for cabin ventilation and pressurisation. The fan air offtake <NUM> is arranged in the bypass duct <NUM> and protrudes from a core faring <NUM> which defines a radially inner surface of the bypass duct <NUM>. It is to be noted that such arrangement allows a short fan air offtake <NUM>. In alternative embodiments, the fan air offtake <NUM> is arranged in the bypass duct <NUM> and protrudes from a nacelle inner wall.

The gas turbine engine may further comprise a heat exchanger <NUM> mounted from the core fairing <NUM> and configured to dissipate heat generated by the cabin blower system. Alternatively, heat generated by the cabin blower system may be dissipated by the engine cooling circuit (not illustrated).

The heat exchanger <NUM> is used to dissipate heat from the cabin blower system, and can be a surface heat exchanger mounted from the engine core fairings <NUM> as illustrated, so that the heat exchanger is cooled by the fan by-pass air. Equally the surface cooler could be mounted on any surface of the bypass duct <NUM> or splitters <NUM>,<NUM>. Ideally the heat exchanger is mounted in close proximity to the cabin blower system.

Note a matrix heat exchanger fed by a dedicated offtake from the bypass duct <NUM> would be another means (not illustrated) of cooling the cabin blower system.

The fan air offtake may be arranged differently from the fan air offtake <NUM>. For example, in the embodiment of <FIG>, the fan air offtake <NUM>' is arranged at a splitter faring.

In detail, <FIG> illustrates a gas turbine engine <NUM>, <NUM>' of the type illustrated with reference to <FIG>, comprising an accessory gearbox <NUM> arranged circumferentially from the core. A cabin blower system <NUM> of the type illustrated with reference to <FIG> is connected to one of the drive output pads of the accessory gearbox <NUM>. Engine and airframe accessories <NUM>, such for example fuel and oil pumps, are connected to the remaining drive output pads <NUM>.

The gas turbine engine further comprises an upper bifurcation, or upper splitter, <NUM> and a lower bifurcation, or lower splitter, <NUM> spanning the bypass duct <NUM>. The upper splitter <NUM> and the lower splitter <NUM> comprise respective leading edges, trailing edges and a first and a second sidewalls connecting the leading edges and the trailing edges. The fan air offtake <NUM>' may be either a forward facing offtake arranged on the lower splitter leading edge (as illustrated in <FIG>), or a scoop on either the first or second sidewalls of the lower splitter <NUM>. In alternative non-illustrated embodiments the fan air offtake <NUM>' may be either a forward facing offtake arranged on the upper splitter leading edge, or a scoop on either the first or second sidewalls of the upper splitter <NUM>.

Claim 1:
A gas turbine engine (<NUM>, <NUM>') including:
an engine core (<NUM>) including a compressor (<NUM>, <NUM>, <NUM>, <NUM>), a combustor (<NUM>, <NUM>), and a turbine (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>), the compressor being connected to the turbines through a respective shaft (<NUM>);
an accessory gearbox (<NUM>) arranged within an accessory gearbox casing (<NUM>); and
a cabin blower system (<NUM>-<NUM>", <NUM>-<NUM>", <NUM>-<NUM>", <NUM>) adapted to be driven by the accessory gearbox and comprising:
an electric variator (<NUM>) comprising a first electrical machine (<NUM>) connected to a drive pad (<NUM>) of the accessory gearbox by a first shaft (<NUM>, <NUM>') arranged along a first axis (<NUM>, <NUM>), a second electrical machine (<NUM>) connected to a second shaft (<NUM>, <NUM>') arranged along a second axis (<NUM>, <NUM>), and a power management system (<NUM>) interconnecting the first and second electrical machines and controlling whether each of the first and second electrical machines operate as a motor or a generator;
a differential gearbox (<NUM>) having a first input connected to a drive pad (<NUM>) of the accessory gearbox to receive drive therefrom, a second input connected to the second shaft of the second electrical machine, and an output; and
a cabin blower (<NUM>) comprising a compressor (<NUM>) driven by the output of the differential gearbox by a third shaft (<NUM>, <NUM>') arranged along a third axis (<NUM>, <NUM>), the compressor comprising an air inlet (<NUM>) and an air outlet (<NUM>);
characterized in that the cabin blower, the first electrical machine, the second electrical machine and the differential gearbox are configured as modules, and in that the first and second electrical machines (<NUM>, <NUM>) are arranged on a first side (<NUM>) of the accessory gearbox casing (<NUM>) and the cabin blower (<NUM>) is arranged on a second side (<NUM>) of the accessory gearbox casing (<NUM>) opposite the first side.