Patent Description:
Vehicles, such as ships and aircrafts, commonly include propellers to provide motive force to the vehicles. The propellers are supported for rotation relative to the vehicle and are typically driven by an engine. The engine is generally connected mechanically to the propeller through a direct mechanical connection, such as through a coupling, to provide mechanical rotation to the propeller. In some vehicles, such as vehicles employing open rotor arrangements with more than one propeller, the engine drive arrangement can be relatively noisy in comparison to closed rotor engines.

According to one embodiment, a rotary propulsion system is provided as defined by claim <NUM>.

In an embodiment the fan includes a plurality of open-rotor fan blades having a scimitar shape.

Embodiments may include a generator connected to the electric motor and a gas turbine engine operably connected to the generator wherein rotational speed of the gas turbine engine is independent of rotational speed of the fan.

In an embodiment the reduction gear set includes a planetary gear arrangement.

In an embodiment the planetary gear arrangement axially overlaps the electric motor.

In an embodiment the planetary gear arrangement is axially offset from the electric motor.

In an embodiment the planetary gear arrangement comprises a sun gear fixed in rotation relative to the permanent magnet, a ring gear fixed in rotation relative to the fan, and two or more planetary gears distributed circumferentially about the rotation axis and intermeshed with the sun gear and the ring gear.

In an embodiment the second reduction gear set arranged axially on a side of the first reduction gear set opposite the electric motor.

According to another embodiment, an aircraft is provided as defined by claim <NUM>.

In an embodiment the rotation axis is substantially horizontal relative to the direction of gravity when the aircraft is normal, level flight.

In an embodiment the rotation axis is substantially vertical relative to the direction of gravity when the aircraft is normal, level flight.

According to yet another embodiment a method of propelling an aircraft is provided as defined by claim <NUM>.

Technical effects of embodiments of the present disclosure include providing a relatively compact, electric motor-driven contra-rotating rotary propulsion system. In certain embodiments rotary propulsion systems are provided that allow for fans to operate at difference speeds, limiting noise. In accordance with certain embodiments rotary propulsion systems are provided with reduction gear sets, allowing the employment of electric motors with relatively high power-density and high propulsive force and torque to the system fan.

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a rotary propulsion system in accordance with the disclosure is shown in <FIG> and is designated generally by reference character <NUM>. Other embodiments of rotary propulsion systems, aircraft having rotary propulsion systems, and methods of propelling aircraft using rotary propulsion systems in accordance with the present disclosure, or aspects thereof, are provided in <FIG>, as will be described. The systems and methods described herein can be used for rotary propulsion systems for aircraft, such as in rotary propulsion systems employing contra-rotating fans, though the present disclosure is not limited to rotary propulsion systems employing control rotating fans or to aircraft in general.

Referring to <FIG>, an aircraft <NUM> including the rotary propulsion system <NUM>, e.g., a fixed-wing aircraft or a rotorcraft, is shown. The aircraft <NUM> includes an airframe <NUM> with one or more pylon <NUM>. The pylon <NUM> supports the rotary propulsion system <NUM>, which in the embodiment shown in <FIG> includes a first fan <NUM> and a second fan <NUM> supported for rotation about a rotation axis <NUM>. Although a specific architecture is shown in <FIG> it is to be understood and appreciated that other aircraft architectures can also benefit from the present disclosure, such as aircraft architectures having a singular rotary propulsion system <NUM> or aircraft architectures having more than two rotary propulsion systems <NUM>. For example, it is contemplated the rotation axis <NUM> about which the rotary propulsion system <NUM> is arranged can be substantially horizontal relative to gravity during normal, level flight. It is also contemplated that, in accordance with certain embodiments, the rotation axis <NUM> about which the rotary propulsion system <NUM> is arranged can be substantially vertical relative to gravity during normal, level flight.

As shown in <FIG>, the aircraft <NUM> includes a gas turbine engine <NUM> with a compressor section <NUM> and a turbine section <NUM>, a generator <NUM> and a power bus <NUM>. The gas turbine engine <NUM> is carried within the airframe <NUM> and is operatively connected to the generator <NUM>. The generator <NUM> is configured to generate electrical power P for the rotary propulsion system <NUM> and is connected to the rotary propulsion system <NUM> by the power bus <NUM>. In the illustrated embodiment the generator <NUM> is an alternating current (AC) generator configured and adapted to provide variable frequency AC power to the rotary propulsion system <NUM> to the control rotational speed and direction of the first fan <NUM> and the second fan <NUM>. In this respect it is contemplated that the connection of the gas turbine engine <NUM> be indirect, gas turbine engine <NUM> providing rotation R to the generator <NUM>, which the generator <NUM> converts to electrical power P for provision the rotary propulsion system <NUM> via the power bus <NUM>. Rotational speed of the gas turbine engine <NUM> is therefore independent of rotational speed of the first fan <NUM> and the second fan <NUM>.

Referring to <FIG>, the rotary propulsion system <NUM> is shown according to an example not covered by the appended claims. As shown in <FIG>, the rotary propulsion system <NUM> includes a singular fan <NUM> arranged as an open-rotor. The fan <NUM> includes a plurality of fan blades <NUM> distributed circumferentially about the rotation axis <NUM> for rotary movement <NUM> about the rotation axis <NUM>. In the illustrated embodiment the fan <NUM> includes eight (<NUM>) fan blades <NUM>. This is for illustration purposes only and is non-limiting. As will be appreciated by those of skill in the art in view of the present disclosure the fan <NUM> can have fewer than eight (<NUM>) fan blades <NUM> or more than eight (<NUM>) fan blades <NUM>, as suitable for an intended application. In the illustrated embodiment the fan blades <NUM> each have a scimitar shape <NUM>, i.e., with increasing sweep along the leading edge of the blade, between radial inner and radially outer ends of the blade. As will be appreciated by those of skill in the art in view of the present disclosure, the scimitar shape <NUM> of the fan blades <NUM> improving efficiency of the fan <NUM> during operation.

As shown in <FIG>, the rotary propulsion system <NUM> includes a singular fan <NUM>, a shaft <NUM>, and electric motor <NUM> with windings <NUM> and one or more permanent magnet <NUM>, and a reduction gear set <NUM>. The fan <NUM> is arranged along the rotation axis <NUM>. The electric motor <NUM> with the windings <NUM> and the one or more permanent magnet <NUM> is arranged along the rotation axis <NUM> is and is operatively connected to the fan <NUM>. The reduction gear set <NUM> is arranged along the rotation axis <NUM> and couples the electric motor <NUM>, the one or more permanent magnet <NUM> being rotatable relative the windings <NUM> and the fan <NUM> to rotate the fan <NUM> using the electric motor <NUM> at a rotational speed RF that is lower than a rotational speed RM of the one or more permanent magnet <NUM>.

The shaft <NUM> is fixed relative to the airframe <NUM>. The windings <NUM> are fixed relative to the shaft <NUM> and are polyphase windings. In this respect the windings <NUM> receive AC power P from the generator <NUM> (shown in <FIG>) and generate therewith a rotating magnetic field that rotates according to the frequency of AC power P. The one or more permanent magnet <NUM> is carried by a rotor <NUM> of the electric motor <NUM>, is supported for rotation relative to the windings <NUM> by bearings <NUM>, and is magnetically coupled to the one or more windings <NUM> across a gap <NUM> to rotate at a speed correlated to the frequency of the AC power applied to the windings <NUM>. The reduction gear set <NUM> couples the rotor <NUM> of the electric motor <NUM> to the fan <NUM>, which reduces rotational speed of the fan <NUM> relative to the rotor <NUM> according the gear ratio of the reduction gear set <NUM>.

As shown in <FIG>, the reduction gear set <NUM> includes a planetary gear arrangement <NUM>. The planetary gear arrangement <NUM> axially overlaps the electric motor <NUM> (shown in <FIG>) to provide an axially compact arrangement and includes a sun gear <NUM>, a plurality of planetary gears <NUM> and a ring gear <NUM>. The sun gear <NUM> is fixed in rotation relative to the permanent magnet <NUM> of the electric motor <NUM>. The ring gear <NUM> is fixed in rotation relative to the singular fan <NUM> and extends circumferentially about the rotation axis <NUM>. The plurality of planetary gears <NUM> are distributed circumferentially about the rotation axis <NUM> and are intermeshed with the sun gear <NUM> and the ring gear <NUM>. The bearings <NUM> are arranged between the sun gear <NUM> and the shaft <NUM>, the sun gear <NUM> thereby being rotatable relative to the shaft <NUM>.

Referring to <FIG>, a rotary propulsion system <NUM> is shown. The rotary propulsion system <NUM> is similar to the rotary propulsion system <NUM> (shown in <FIG>) and additionally includes two fans. In this respect the rotary propulsion system <NUM> includes a first fan <NUM>, a second fan <NUM>, a first electric motor <NUM> with windings <NUM> and one or more permanent magnets <NUM>, and a second electric motor <NUM> with windings <NUM> and one or more permanent magnets <NUM>. The first fan <NUM> and the second fan <NUM> are each arranged along a rotation axis <NUM>, the second fan <NUM> being arranged along the rotation axis <NUM> on a side of the first fan <NUM> opposite the first electric motor <NUM> and the second electric motor <NUM>. As shown in <FIG>, the first fan <NUM> and the second fan <NUM> are contra-rotating, the first fan <NUM> arranged for rotation in a direction <NUM> opposite a rotation direction <NUM> of the second fan <NUM>. In certain embodiments the rotational speed of the second fan <NUM> may be different than that of the first fan <NUM>, e.g., faster or slower. As will be appreciated by those of skill in the art, varying the rotational speed of one of the first fan <NUM> and the second fan <NUM> relative to the other of the first fan <NUM> and the second fan <NUM> can limit the noise of the rotary propulsion system <NUM> during operation.

The windings <NUM> of the first electric motor <NUM> and the windings <NUM> of the second electric motor <NUM> are both fixed relative to the airframe <NUM>. The permanent magnets <NUM> of the first electric motor <NUM> and the permanent magnets <NUM> of the second electric motor <NUM> are each supported for rotation relative to airframe <NUM> in a radial flux-type arrangement. In this respect the one or more permanent magnet <NUM> of the first electric motor <NUM> is arranged on a first rotor <NUM>, is arranged for rotation about the rotation axis <NUM>, is supported by first bearings <NUM> for rotation relative to the airframe <NUM>, and is supported by second bearings <NUM> for rotation relative to the second electric motor <NUM>.

The one or more permanent magnet <NUM> of the second electric motor <NUM> is arranged on a second rotor <NUM> and is arranged for rotation about the rotation axis <NUM>, the windings <NUM> and the one or more permanent magnet <NUM> of the first electric motor <NUM> extending circumferentially about the windings <NUM> and the one or more permanent magnet <NUM> of the second electric motor <NUM>. The one or more permanent magnet <NUM> of the second electric motor <NUM> is in turn fixed relative to a shaft <NUM>, the shaft <NUM> in turn being supported for rotation relative to the airframe <NUM> by third bearings <NUM>.

A first reduction gear set <NUM> couples the first fan <NUM> to the first electric motor <NUM> and a second reduction gear set <NUM> couples the second fan <NUM> to the second electric motor <NUM>. The first reduction gear set <NUM> is similar to the reduction gear set <NUM> (shown in <FIG>) and supports the first fan <NUM> for rotation at a rotational speed that is lower than a rotational speed of the first electric motor <NUM> according to the gear ratio of the first reduction gear set <NUM>. The second reduction gear set <NUM> supports the second fan <NUM> for rotation relative to the second electric motor <NUM> according to the gear ratio of the second reduction gear set <NUM>.

As shown in <FIG>, the second reduction gear set <NUM> includes a planetary gear arrangement <NUM>. The planetary gear arrangement <NUM> is axially offset from the first electric motor <NUM> (shown in <FIG>) and the second electric motor <NUM> (shown in <FIG>) and includes sun gear <NUM>, a plurality of planetary gears <NUM>, and a ring gear <NUM>. The sun gear <NUM> is arranged along the rotation axis <NUM> and is fixed relative to the shaft <NUM>. The ring gear <NUM> extends about the sun gear <NUM> (shown in <FIG>) and is fixed relative to the second fan <NUM> (shown in <FIG>). The plurality of planetary gears <NUM> are distributed circumferentially about the sun gear <NUM> and are intermeshed with the sun gear <NUM> and the ring gear <NUM>.

Referring now to <FIG>, a rotary propulsion system <NUM> is shown. The rotary propulsion system <NUM> is similar to the rotary propulsion system <NUM> (shown in <FIG>) and additionally includes a first electric motor <NUM> and a second electric motor <NUM> having axial flux-type arrangements. In this respect the first electric motor <NUM> is operatively associated with a first fan <NUM> and includes a winding <NUM> and one or more permanent magnet <NUM>. The winding <NUM> of the first electric motor <NUM> is fixed relative to the airframe <NUM> and extends radially from a rotation axis <NUM>. The one or more permanent magnet <NUM> of the first electric motor <NUM> is supported by a rotor <NUM>, extends radially from the rotation axis <NUM>, and is axially spaced from the winding <NUM> by an axial gap <NUM>. The rotor <NUM> includes a shaft portion <NUM> that extends along the rotation axis <NUM>, is supported for rotation about the rotation axis <NUM> relative to the winding <NUM> by a bearings <NUM>, and is coupled to the first fan <NUM> by a first reduction gear set <NUM>.

As shown in <FIG>, the first reduction gear set <NUM> includes a planetary gear arrangement <NUM>. The planetary gear arrangement <NUM> includes a ring gear <NUM>, a plurality of planetary gears <NUM> and a sun gear <NUM>. The ring gear <NUM> extends circumferentially about the rotation axis <NUM> and is fixed to relative to the first fan <NUM>. The plurality of planetary gears <NUM> are distributed about the rotation axis <NUM> and are intermeshed with the ring gear <NUM> and the sun gear <NUM>. The sun gear <NUM> is arranged along the rotation axis <NUM>, is fixed in rotation relative to the shaft portion <NUM> (shown in <FIG>), and supported for rotation relative to a shaft <NUM> by bearings <NUM>, which is arranged radially inward of teeth of the sun gear <NUM>. As will be appreciated by those of skill in the art in view of the present disclosure, the first reduction gear set <NUM> allows the first fan <NUM> to rotate at a rotational speed that is lower than a rotational speed of the first electric motor <NUM> according to the gear ratio of the first reduction gear set <NUM>, enabling the use of a relatively high-speed motor run at high speed to provide high torque to the first fan <NUM>.

With continuing reference to <FIG>, the second electric motor <NUM> is arranged on a side of the first electric motor <NUM> axially opposite the first fan <NUM>, includes a winding <NUM> and one or more permanent magnet <NUM>, and is operatively connected to a second fan <NUM> through a second reduction gear set <NUM>. In this respect the winding <NUM> is fixed to the airframe <NUM>, extends radially from the rotation axis <NUM>, and opposes the one or more permanent magnet <NUM> across an axial gap <NUM>. The one or more permanent magnet <NUM> extends radially from the rotation axis <NUM> and is fixed relative to the shaft <NUM>.

The shaft <NUM> is arranged along the rotation axis <NUM> and is supported for rotation relative to the airframe <NUM> relative by bearings <NUM>. The shaft <NUM> is also supported for rotation relative to the shaft portion <NUM> by bearings <NUM> and is further supported for rotation relative to the sun gear <NUM> (shown in <FIG>) of the first reduction gear set <NUM> by the bearings <NUM>. This allows the shaft <NUM> to rotate about the rotation axis <NUM> independent of both the first electric motor <NUM> and the first fan <NUM>, thereby operably connecting the second electric motor <NUM> to the second fan <NUM>.

Operable connection of the second electric motor <NUM> to the second fan <NUM> is via the second reduction gear set <NUM>. In this respect, as shown in <FIG>, the second reduction gear set <NUM> includes a planetary gear arrangement <NUM> including a ring gear <NUM>, a plurality of planetary gears <NUM> and a sun gear <NUM>. The ring gear <NUM> extends about the rotation axis <NUM> and is fixed relative to the second fan <NUM>. The plurality of planetary gears <NUM> are distributed about the rotation axis <NUM> and are intermeshed with the ring gear <NUM> and the sun gear <NUM>. The sun gear <NUM> is arranged along the rotation axis <NUM> and is fixed in rotation relative to the shaft <NUM>. As will be appreciated by those of skill in the art, this allows the second electric motor <NUM> to drive the second fan <NUM> at a rotational speed that this lower than a rotational speed of the second electric motor <NUM>, i.e., according to the gear ratio of the second reduction gear set <NUM>.

With reference to <FIG>, a method <NUM> of propelling an aircraft, e.g., the aircraft <NUM> (shown in <FIG>), is shown. The method <NUM> includes, at a rotary propulsion system, e.g., the rotary propulsion system <NUM> (shown in <FIG>) or the rotary propulsion arrangement <NUM> (shown in <FIG>), applying AC power to windings of a first electric motor, e.g., the windings <NUM> (shown in <FIG>) of the first electric motor <NUM> (shown in <FIG>), as shown with box <NUM>. The current flow rotates a permanent magnet of the first electric motor, e.g., the permanent magnet <NUM> (shown in <FIG>), about the rotation axis <NUM> (shown in <FIG>) at a first electric motor permanent magnet rotational speed, as shown with box <NUM>. Using the rotation of the permanent magnet of the first electric motor, a first fan, e.g., the first fan <NUM> (shown in <FIG>) is rotated at a first fan rotational speed relative to the first windings about the rotation axis, e.g., the first fan rotational speed <NUM> (shown in <FIG>), as shown with box <NUM>. It is contemplated that the first fan rotational speed be lower than the first electric motor permanent magnet rotational speed, as shown with box <NUM>.

AC power is also applied to windings of a second electric motor, e.g., the windings <NUM> (shown in <FIG>) of the second electric motor <NUM> (shown in <FIG>), as shown with box <NUM>. The current flow rotates a permanent magnet of the second electric motor, e.g., the permanent magnet <NUM> (shown in <FIG>), about the rotation axis at a second permanent magnet rotational speed, as shown with box <NUM>. Using the rotation of the permanent magnet of second electric motor, a second fan is rotated at a second fan rotational speed relative to the windings of the second electric motor about the rotation axis, e.g., the second fan rotational speed <NUM> (shown in <FIG>), as shown with box <NUM>. It is contemplated that the second fan rotational speed be lower than the permanent magnet rotational speed of the second electric motor, as shown with box <NUM>. In certain embodiments the direction of rotation of the second fan can be opposite a direction of rotation of the first fan, as shown with box <NUM>.

Claim 1:
A rotary propulsion system, comprising:
a fan (<NUM>, <NUM>, <NUM>, <NUM>) arranged along a rotation axis;
an electric motor (<NUM>, <NUM>, <NUM>, <NUM>) having windings (<NUM>, <NUM>, <NUM>, <NUM>) and a permanent magnet (<NUM>, <NUM>, <NUM>, <NUM>) (<NUM>) arranged along the rotation axis and operatively connected to the fan; and
a reduction gear set (<NUM>, <NUM>) extending about the rotation axis and coupling the electric motor to the fan, wherein the permanent magnet is rotatable relative to the windings and the fan to rotate the fan using the electric motor at a rotational speed that is lower than a rotational speed of the permanent magnet;
wherein the fan is a first fan (<NUM>) and further comprising a second fan (<NUM>), the second fan coaxially supported for rotation about the rotation axis with the first fan; and
further comprising a shaft (<NUM>, <NUM>, <NUM>) supporting the fan and coupled to the fan by the reduction gear set, wherein the winding or the permanent magnet is fixed relative to the shaft, wherein the shaft is a first shaft and further comprising a second shaft, the second shaft arranged coaxially with the first shaft along the rotation axis and supported for rotation relative to the first shaft;
wherein the electric motor is a first electric motor (<NUM>, <NUM>), the winding is a first winding (<NUM>, <NUM>), and the permanent magnet is a first permanent magnet (<NUM>, <NUM>), the rotary propulsion system further comprising a second electric motor (<NUM>, <NUM>) with a second winding (<NUM>, <NUM>) and a second permanent magnet (<NUM>, <NUM>), the second winding fixed relative to the first winding and the second permanent magnet rotatable relative to the first permanent magnet and the second winding; and
wherein the reduction gear set is a first reduction gear set (<NUM>) and further comprising a second reduction gear set (<NUM>), the second reduction gear set axially offset from the first reduction gear set along the rotation axis, wherein the second reduction gear set arranged axially on a side of the first reduction gear set opposite the electric motor.