Patent Description:
<CIT> describes an electric motor driven fan assembly. The present inventor is unaware of any production examples of the device described in <CIT>. This is most likely due to how inefficient the fan assembly would be in practice.

<CIT> describes a dual-rotor electric machine. The dual rotor electric machine comprises: a stator having one or more slots and one or more stator windings. The dual rotor electric machine further comprises a first rotor arranged to rotate relative to the stator with an airgap therebetween. The first rotor comprises a first rotor excitation element having one or more magnetic pole pairs arranged to interact with the stator windings, the first rotor configured to rotate about an axis. The dual rotor electric machine further comprises a second rotor arranged to rotate relative to the stator with an airgap therebetween. The second rotor comprises a second rotor excitation element having one or more magnetic pole pairs arranged to interact with the stator windings, the second rotor being configured to rotate about the axis. One or both of the first and second rotor excitation elements comprises a permanent magnetic material The number of magnetic pole pairs on the first rotor is different from the number of magnetic pair poles on the second rotor. The first rotor is arranged to rotate about the axis in an opposite direction and at a different speed to the second rotor.

<CIT> describes an aircraft propulsion system comprises first and second co-axial propulsors, one of the first and second propulsor being positioned forward of the other propulsor. A first electric motor is configured to drive the first propulsor, and a second electric motor is configured to drive the second propulsor. The first electric motor comprising a rotor radially inwardly of the stator, and the second electric motor comprises a rotor radially outwardly of the stator. The stator of the first electric motor is mounted to the stator of the second electric motor.

<CIT> describes an electromagnetic propulsive motor having a rotor capable of rotation around a shaft and having a plurality of radially disposed blades including blade tip portions for compressing a working fluid. A stator having a case frame, and a plurality of radially disposed vanes extending generally between said case frame and said shaft for directing the working fluid are also provided. A plurality of electromagnetic elements disposed within said rotor blades proximate the tip portions thereof interact electromagnetically with a plurality of electromagnetic elements disposed in said stator case frame to drive said rotor.

It is an aim of the present disclosure to alleviate such problems and improve on the prior art.

According to an aspect of the present disclosure, there is provided an electrically powered fan engine according to Claim <NUM>. Optional features of the electrically powered fan engine are provided in dependent Claims <NUM> to <NUM>.

According to an aspect of the present disclosure, there is provided an aircraft comprising the aforementioned electrically powered fan engine.

The embodiments of the present disclosure are best understood with reference to the accompanying figures, in which:.

With reference to <FIG>, an electrically powered fan engine <NUM> is provided in the form of an aircraft engine. The electrically powered fan engine <NUM> includes an intake <NUM> (or inlet), an energiser chamber <NUM>, an exhaust nozzle <NUM> (or exhaust), and a pylon attachment <NUM>.

The intake <NUM> is substantially circular. The intake <NUM> includes a rim <NUM>, having a dome shaped cross-section. The rim <NUM> surrounds the intake <NUM> to allow a fluid, e.g. air, to enter the energiser chamber <NUM>.

The energiser chamber <NUM> is between the intake <NUM> and the exhaust <NUM> nozzle, and is surrounded by a wall <NUM>. The wall <NUM> is substantially cylindrical. The pylon attachment <NUM> is attached to the wall <NUM>. The pylon attachment <NUM> includes a plate <NUM> fixed to an upper section of the wall <NUM> when in-use. The plate <NUM> is substantially integrally formed with the wall <NUM>. In other embodiments, the plate <NUM> is attached to the wall <NUM> with bolts. A plurality of flanges <NUM> are attached to the plate <NUM>. There are three flanges <NUM> in this embodiment. Other embodiments may include more or fewer flanges <NUM>.

The flanges <NUM> include a through-hole <NUM>, and a dome shaped head <NUM>. The through-holes <NUM> allow through-passage of an attachment device, such as a bolt, to attach to electrically powered fan engine <NUM> to a wing of an aircraft being propelled by it or to provide lift if vertical take-off and landing is desired.

The exhaust nozzle <NUM> extends rearwards from the energiser chamber <NUM>. The exhaust nozzle <NUM> is a converging nozzle.

With reference to <FIG>, the electrically powered fan engine <NUM> also includes the electric fan assembly <NUM> in the energiser chamber <NUM>.

The electric fan assembly <NUM> is surrounded by the wall <NUM>, and includes a nose cone <NUM>, a first rotor <NUM>, a static guide vane <NUM>, a second rotor <NUM>, and an exhaust fairing <NUM>. The first rotor <NUM>, the static guide vane <NUM>, and the second rotor <NUM>, are positioned in axial alignment. The nose <NUM> and the exhaust fairing <NUM> are also in axial alignment with the first rotor <NUM>, the static guide vane <NUM>, and the second rotor <NUM>.

The nose <NUM> may be made from an elastomer, such as rubber. Rubber is used to provide an anti-icing function. The nose <NUM> is substantially conical and protrudes into the intake into an in-coming air stream.

The first rotor <NUM> may also be called a front rotor due to it being in front of the static guide vane <NUM>. The first rotor <NUM> includes a plurality of radially extending blades <NUM>. The blades <NUM> are configured to receive a fluid from the inlet <NUM>. The blades <NUM> have an aerofoil cross-section and have an angle of inclination with respect to the on-coming airflow. The blades <NUM> extend from a first hub <NUM> (or front hub) at the centre and a first rim <NUM>.

With reference to <FIG>, the engine also includes a shaft <NUM> on bearings <NUM>. A front bearing track <NUM> and a rear bearing track <NUM> are provided to house the bearings <NUM>. The shaft <NUM> is divided into a front stub axle and a rear stub axle. The front hub <NUM> is thus journalled about the front stub axle. The first hub <NUM> is substantially trapezoidal in cross-section in shape and continues the profile of the conical nose <NUM>, when viewed in cross-section.

With continued reference to <FIG>, the first rim <NUM> is substantially cylindrical. The first rim <NUM> supports a plurality of permanent magnets <NUM> and a front rotor-iron <NUM>. The permanent magnets <NUM> are separated from one another circumferentially around the first rim <NUM>. The magnets <NUM> may be arranged in a Halbach array. In this embodiment, the motors are radial motors. In other embodiments, the motors can equally be axial motors.

With further reference to <FIG>, the electrically powered fan engine <NUM> also includes a front stator iron <NUM> and a plurality of motor windings <NUM>. The front stator iron may be a laminated stator iron <NUM>. The front stator iron <NUM> is attached to an interior surface of the wall <NUM>, whilst maintaining a fluid flow path between the wall <NUM> and the front stator iron <NUM> (see below on by-pass duct). The front stator irons <NUM> and the motor windings <NUM> are configured to the slotless. In other embodiments, they could by slotted. The motor windings <NUM> may be made from an electrically conductive material, for example copper or aluminium. The motor windings <NUM> may be energised by an electrical supply provided from a remote source. The remote source may be located external to the electrically powered fan engine, e.g. within the aircraft. The motor windings <NUM> may be energised by a direct current (DC) supply or, more likely, an alternating current (AC) supply. Where an AC supply is used, the supply may be single phase or, more likely, a polyphase supply. For example, a three-phase AC supply is used in this example.

In this way, the front stator iron <NUM>, the plurality of motor windings <NUM>, the front rotor iron <NUM>, and the permanent magnets <NUM>, form an electromagnetic circuit configured to drive the rim (in this case, a front motor). The electromagnetic circuit may comprise an electric motor. Accordingly, the electrically powered fan engine <NUM> may be called an electric rim-driven fan. The electric motor may operate synchronously. For instance, the electric motor may be configured as a permanent magnet synchronous motor although a fan device may also be configured as an induction motor or a switched reluctance motor or a hybrid combination of such motor technologies.

With reference to <FIG>, the static guide vane <NUM> includes a plurality of blades <NUM>. Each blade has an aerofoil cross-section, and is inclined into the oncoming airflow. In this way, a pitch of the blades <NUM> may be different to a pitch of the blades <NUM> of the first rotor <NUM>. The blades <NUM> extend radially between a central hub <NUM> and a central rim <NUM>.

With reference to <FIG>, the central hub <NUM> is substantially trapezoidal in cross-section, and follows a profile of the nose <NUM> and the first hub <NUM>. The central hub <NUM> has a fluid passage <NUM> having a step <NUM> at a section where an interior diameter of the fluid passage <NUM> decreases from a first diameter to a second diameter. The shaft <NUM> includes a wall <NUM>, or a flange. The wall <NUM> has an outer diameter between the first and second diameters of the central bore <NUM>. In this way, the shaft <NUM> can fit within the central bore of the central hub <NUM>, and the wall <NUM> can be attached to the step <NUM>. In this way, the shaft <NUM> may be fixed in position relative to the static guide vane <NUM>. In other words, the shaft <NUM> may be configured so it does not rotate. An axial extent of the shaft <NUM> is greater than that of the central hub <NUM> such that the shaft <NUM> provides a front stub axle and a rear stub axle upon which the front hub <NUM> and a rear hub <NUM> are journalled.

The central rim <NUM> has a substantially I-shaped cross-section having a body <NUM> extending between opposing ends <NUM>, where the body <NUM> has a comparatively narrow width compared to the ends <NUM>. The central rim <NUM> is attached to the wall <NUM> by the outer end <NUM>. In this way, the static guide vane <NUM> is coupled to the pylon attachment <NUM> indirectly via the wall <NUM>. Accordingly, thrust forces are transmitted through the static guide vane <NUM> to the pylon attachment <NUM> through the respective attachments to the wall <NUM>. In other embodiments, the wall <NUM> may include a hole such that the central rim <NUM> is connected directly to the pylon attachment <NUM>, again coupling the static guide vane to the pylon attachment <NUM>.

With reference to <FIG>, the second rotor <NUM> may also be called a rear rotor due to it being aft of the static guide vane <NUM>. The second rotor <NUM> includes a plurality of radially extending blades <NUM>. The blades <NUM> have an aerofoil cross-section and are inclined into the on-coming airflow. The blades <NUM> extend from a third hub <NUM> (or rear hub <NUM>) at the centre and a third rim <NUM> (or rear rim <NUM>).

A front bearing track <NUM> and a rear bearing track <NUM> are provided to house the bearings <NUM>. The front hub <NUM> is thus journalled about the front stub axle. The first hub <NUM> is substantially trapezoidal in cross-section in shape and continues the profile of the conical nose <NUM>, when viewed in cross-section.

With reference to <FIG>, the rear hub <NUM> is journalled about the rear stub-axle. The rear hub <NUM> is substantially trapezoidal in cross-section and continues the profile of the conical nose <NUM>, the first hub <NUM>, and the central hub <NUM>, when viewed in cross-section. In this way, the front hub <NUM>, the central hub <NUM>, and the rear hub <NUM>, combine to form a substantially frusto-conical hub, having a surface area that gradually increases axially from the inlet <NUM> to the exhaust <NUM>. The substantially frusto-conical hub also forms a substantially conical fairing due to its interaction with the fluid flowing through the energiser camber <NUM>.

With continued reference to <FIG>, the rear rim <NUM> is substantially cylindrical. The rear rim <NUM> supports a plurality of permanent magnets <NUM> and a rear rotor-iron <NUM>. The permanent magnets <NUM> are separated from one another circumferentially around the rear rim <NUM>. The magnets <NUM> may be arranged in a Halbach array.

With further reference to <FIG>, the electrically powered fan engine <NUM> also includes a rear stator iron <NUM> and a plurality of motor windings <NUM>. The rear stator iron <NUM> may be a laminated stator iron <NUM>. The rear stator iron <NUM> is attached to an interior surface of the wall <NUM> as are the plurality of motor windings <NUM>. The rear stator irons <NUM> and the motor windings <NUM> are configured to the slotless. In other embodiments, they may also be slotted. The motor windings <NUM> may be made from an electrically conductive material, for example copper or aluminium. The motor windings <NUM> may be energised by an electrical supply provided from a remote source. The remote source may be located external to the electrically powered fan engine, e.g. within the aircraft. The motor windings <NUM> may be energised by a direct current (DC) supply or, more likely, an alternating current (AC) supply. Where an AC supply is used, the supply may be single phase or, more likely, a polyphase supply. For example, a three-phase AC supply is used in this example.

The rear stator iron <NUM>, the plurality of motor windings <NUM>, the rear rotor iron <NUM>, and the permanent magnets <NUM>, form an electromagnetic circuit configured to drive a the rim (in this instance a rear motor). The electromagnetic circuit may comprise an electric motor. Accordingly, the electrically powered fan engine may be called an electric rim-driven fan. The electric motor may operate synchronously. For instance, the electric motor may be configured as a permanent magnet synchronous motor although a fan device may also be configured as an induction motor or a switched reluctance motor or a hybrid combination of such motor technologies. The electrical supply to the front motor and the rear motor may be independent.

Sealing devices (not shown) may be provided between the front rim <NUM> and the central rim <NUM>, and between the central rim <NUM> and the rear rim <NUM>. An example of a sealing device may include a dynamic seal such as an elastomeric ring. Examples includes a washer or an O-ring. Sealing devices may also be provided between the rim <NUM> and the front rim <NUM> and the rear rim <NUM> and the exhaust nozzle <NUM> (specifically the nozzle wall <NUM> as introduced below).

The exhaust fairing <NUM> may be substantially bullet shaped, or dome shaped.

It can be seen from the figures that the front rim <NUM>, the central rim <NUM>, and the rear rim <NUM>, combine with the front hub <NUM>, the central hub <NUM>, and the rear hub <NUM>, to provide the energiser chamber <NUM>. For instance, an interior outer surface of the energiser chamber <NUM> is provided by cooperation of the front rim <NUM>, the central rim <NUM>, and the rear rim <NUM>. An interior inner surface of the energiser chamber <NUM> is provided by the front hub <NUM>, the central hub <NUM>, and the rear hub <NUM>.

With reference to <FIG>, the electrically powered fan engine <NUM> includes a by-pass <NUM>. The by-pass <NUM> includes a by-pass inlet <NUM>, a by-pass duct <NUM>, and a by-pass outlet <NUM>. The by-pass inlet <NUM> may be a ram-air inlet. The rim <NUM> may include a ramped section <NUM> where the radius of an outer surface decreases. The by-pass inlet <NUM> is formed by the ramped section <NUM> of the rim <NUM> and an annular ramp <NUM> concentrically arranged outside the ramped section <NUM>. The annular ramp <NUM> is attached to the rim <NUM> by means of radially extending brackets (not shown for brevity). The annular ramp <NUM> is attached to the wall <NUM> by including a recess for receiving the wall <NUM>. In this way, exterior surfaces of the wall <NUM> and the annual ramp <NUM> are aligned and form a continuous surface.

The by-pass duct <NUM> includes a channel extending from the by-pass inlet <NUM> positioned upstream of the first rotor and the by-pass outlet positioned downstream of the second rotor. More specifically, the by-pass outlet <NUM> is positioned within the exhaust nozzle. The central rim <NUM> includes a hole <NUM> (see <FIG>) within the body <NUM> extending from fore to aft. The hole <NUM> may be a plurality of holes arranged circumferentially. In this way, the by-pass duct <NUM> is able to pass air from the inlet <NUM> to the outlet <NUM>. The outlet <NUM> is provided as a channel formed between the wall <NUM> and the exhaust nozzle <NUM>.

The by-pass outlet <NUM> is formed by the exhaust nozzle. The exhaust nozzle <NUM> includes an interior nozzle wall <NUM> and an exterior nozzle wall <NUM>. The interior nozzle wall <NUM> is attached to the exterior nozzle wall <NUM> by means of brackets (not shown for brevity) arranged circumferentially around the nozzle. The exterior nozzle wall <NUM> is attached to the wall <NUM>. In particular, the exterior nozzle wall <NUM> includes a recess at a fore end to receive the wall <NUM>. Exterior surfaces of the wall <NUM> and the exterior nozzle wall <NUM> are aligned and form a continuous surface. The interior <NUM> and exterior <NUM> nozzle walls form the by-pass outlet <NUM> therebetween.

The front motor and the rear motor are positioned within the by-pass duct <NUM>. More specifically, the front and rear rotor irons <NUM>, <NUM>, the magnets <NUM>, <NUM>, the front and rear stator irons <NUM>, <NUM>, and the motor windings <NUM>, <NUM>, are provided within the by-pass duct <NUM>. In this way, by-pass air is able to reduce the temperature of the front and rear motor components.

During operation, current is supplied independently to the motor windings <NUM>, <NUM>. The electromagnetic interaction between the windings <NUM>, <NUM>, urges the magnets <NUM>, <NUM> to move according to the right-hand rule. It is worth noting that since the windings <NUM>, <NUM>, are independently energised, rotational velocity of the front and rear rotors <NUM>, <NUM>, are independent. Velocity is taken herein to mean the angular speed and the direction. For example, the same velocity requires both speed and direction of rotation to be the same, whereas a different velocity requires at least one of the speed or the direction of rotation to be different. For instance, the first rotor <NUM> may be associated with a first direction, a first speed and a first velocity. The second rotor <NUM> may be associated with a first direction, a second speed and a second velocity. The first velocity may be different from the second velocity when the first and second directions differ and/or when the first and second speeds differ. The first velocity is the same as the second velocity when the first speed and the second speed are the same and when the first direction and the second direction are the same.

The increase in pressure across the front rotor <NUM> can be controlled separately to the pressure increased across the rear rotor <NUM>, since the rotors are independently driven. To increase the efficiency of the pressure increase, the front rotor <NUM> may be driven in an opposite direction to the rear rotor <NUM>. In this way, the rotors <NUM>, <NUM>, may contra-rotate. Contra-rotating rotors <NUM>, <NUM> increases the efficiency of the electrically powered fan engine <NUM> by increasing the pressure gain, and reducing swirl momentum in the fluid flow in the energiser chamber <NUM> compared to a case where the rotors <NUM>, <NUM>, rotate in the same direction as is the case with <CIT> where the front and rear rotors are driven dependent on each other.

The frusto-conical hub formed by the front hub <NUM>, the central hub <NUM>, and the rear hub <NUM>, reduces a cross-sectional area of a fluid flow path through the energiser chamber <NUM>. In this way, the front rim <NUM>, the central rim <NUM>, and the rear rim <NUM>, in addition to the front hub <NUM>, the central hub <NUM>, and the rear hub <NUM>, cooperate to reduce the flow area through the energiser chamber. In particular, the front rim <NUM>, the central rim <NUM>, and the rear rim <NUM>, in addition to the front hub <NUM>, the central hub <NUM>, and the rear hub <NUM> cooperate to reduce the flow area through the energiser chamber <NUM>. The reduction in cross-sectional area is gradual and substantially consistent along an axial length of the energiser chamber <NUM>. The reduction in cross-sectional area of the annulus helps to maintain the pressure increase induced in the fluid stream by rotation of the front rotor <NUM> and the rear rotor <NUM>. The bullet shaped exhaust fairing <NUM> compliments an interior convergence of the interior exhaust nozzle <NUM>. In this way, the exhaust fairing <NUM> and the exhaust nozzle <NUM> cooperate the maintain the cross-sectional flow area substantially constant in the exhaust <NUM>. This reduces the risk of the air decelerating.

The guide vane <NUM> serves to direct the fluid flow to a leading edge of the blades <NUM> of the rear rotor <NUM> at an angle of incidence that increases the pressure gain induced by the blades <NUM>. In this way, the blades <NUM> of the rear rotor <NUM> are less likely to operate in an aerodynamically stalled condition.

Due to the front rotor <NUM> and the rear rotor <NUM> rotating relative to the static guide vane <NUM>, the sealing devices help maintain the pressure increase by reducing air leakage paths between the rotors <NUM>, <NUM>, and the adjacent static structures.

The bearings <NUM> being located within the front and rear bearing tracks <NUM> and <NUM> around the shaft <NUM>, locates the bearing structures out of the airflow. As a result, a reduction in drag occurs compared to <CIT> where the central shaft rotates as one with the rotors being fixed to it. The arrangement in <CIT> requires bearing arrangements at either end of the central shaft within the airflow causing a drag increase and efficiency reduction of the electrically powered fan engine <NUM>. Aside from the drag reduction, the arrangement of the present disclosure also reduces structural effects such as vibration where the shaft can vibrate and wobble due to its inherent length and the moment applied to the shaft during rotation of the rotors as would be the case with <CIT>.

Whilst the present disclosure has been explained as the embodiment described above with reference to <FIG>, the inventive concepts contained herein may be extended to various other embodiments falling within the scope of the appended claims. For instance, the device <NUM> may include two axially aligned rotors or may be an assembly of three or more axially aligned rotors wherein each rotor is located in front of or behind a static guide vane.

The subject-matter of the present disclosure may be described more briefly as follows.

Referring to the accompanying drawings, <FIG>,<FIG> and <FIG> show a fan device of the invention having a forward intake section a central energiser section and an aft exhaust nozzle section. The central energiser section houses a forward fan rotor and an aft fan rotor. The fan-rotors are able to rotate, by means of bearings which are supported on a shaft fixed to a static guide vane structure which is attached to the duct casing. Around the periphery of each fan rotor is a rim that supports the permanent magnets and the rotor back-irons. In this example the rotor magnets are arranged in a Halbach array.

Attached to the duct casing are the laminated stator irons and the conductor windings of the motor circuits. In this example the stator irons and conductor windings are configured to be slotless. The hub regions of the fan rotors and the guide vane structure are conical in form and tapered in order to progressively reduce the air-flow annulus-area from the nose cone, located at the ducted fan intake, to the bullet fairing located at the ducted fan outlet.

In order to provide a source of air, to cool the rotor back-irons and magnets and the stator irons and conductor windings, an air-inlet aperture is located around the external peripheral surface of the ducted fan device between the intake lip and the duct casing. To facilitate the passage of the cooling air ventilation passages are provided in the static guide vane structure. The cooling air is exhausted into the fan efflux air by means of the double-walled air channel.

Claim 1:
An electrically powered fan engine (<NUM>) including:
an inlet (<NUM>), an exhaust nozzle (<NUM>);
a by-pass (<NUM>) including a by-pass inlet (<NUM>), a by-pass duct (<NUM>) and a by-pass outlet (<NUM>);
an energiser chamber (<NUM>) between the eminlet (<NUM>) and the exhaust nozzle (<NUM>) of the electrically powered fan engine;
a first rotor (<NUM>) within the energiser chamber, the first rotor including a plurality of blades (<NUM>) and being configured to receive a fluid from the inlet and configured to rotate at a first velocity; and
a second rotor (<NUM>) within the energiser chamber, the second rotor including a plurality of blades (<NUM>) and being configured to receive the fluid after passing through the first rotor and configured to rotate at a second velocity,
wherein the first velocity is different from the second velocity,
wherein the first rotor includes a rim (<NUM>) and the second rotor includes a rim (<NUM>),
wherein the electrically powered fan engine further comprises a first electromagnetic circuit configured to drive the rim of the first rotor and a second electromagnetic circuit configured to drive the rim of the second rotor,
wherein the by-pass duct (<NUM>) extends between the by-pass inlet (<NUM>) and the by-pass outlet (<NUM>), wherein the by-pass inlet is positioned upstream of the first rotor, and wherein the by-pass outlet is positioned in the exhaust nozzle, and
characterised in that the first electromagnetic circuit and the second electromagnetic circuit are each provided within the by-pass duct for cooling, in-use.