Patent Description:
A conventional commercial aircraft generally includes a fuselage, a pair of wings, and a propulsion system that produces thrust. Such propulsion systems typically include at least two aircraft engines, such as turbofan jet engines. Each turbofan jet engine is typically mounted to one of the wings of the aircraft, such as in a suspended position beneath the wing separated from the wing and fuselage.

Hybrid electric propulsion systems are being developed to improve the efficiency of such conventional commercial aircraft. Hybrid electric propulsion systems typically include one or more propulsors. A propulsor can include an electric machine operatively coupled with an aircraft engine, for example. While many advances have been achieved, further efficiency improvements and integrated solutions for propulsors of hybrid electric propulsion systems are desirable.

Thus, improved hybrid electric propulsors and methods of operating the same would be useful additions to the art.

<CIT> relates to hybrid propulsion engines for aircraft.

In one aspect, a propulsor is provided. The propulsor includes an electric machine and a gas turbine engine. The gas turbine engine includes a fan spool, the electric machine being operatively coupled with the fan spool. The gas turbine engine also includes a core spool. Further, the gas turbine engine includes a hydraulic coupling encasing at least a portion of the fan spool and at least a portion of the core spool, the hydraulic coupling hydraulically coupling the fan spool and the core spool.

In another aspect, an aircraft is provided. The aircraft includes an electric machine and a gas turbine engine. The gas turbine engine includes a fan spool having a fan shaft and a fan coupled with the fan shaft, the electric machine being operatively coupled with the fan shaft. The gas turbine engine also includes a compressor having rotatable blades and a turbine having rotatable blades. Further, the gas turbine engine includes a core spool having a core shaft coupled with the rotatable blades of the compressor and the rotatable blades of the turbine. Moreover, the gas turbine engine includes a hydraulic coupling encasing at least a portion of the fan spool and at least a portion of the core spool, the hydraulic coupling hydraulically coupling the fan spool and the core spool.

In yet another aspect, a method of operating a propulsor of an aircraft is provided. The method includes receiving an input indicating a command to change a thrust output of the propulsor, the propulsor having a gas turbine engine and an electric machine. Further, the method includes causing, in response to receiving the input, the electric machine operatively coupled with a fan spool of the gas turbine engine to apply a torque on the fan spool so that the thrust output of the propulsor is changed, the fan spool being hydraulically coupled with a core spool of the gas turbine engine via a hydraulic coupling.

In a further aspect, a non-transitory computer readable medium is provided. The non-transitory computer readable medium comprises computer-executable instructions, which, when executed by one or more processors of a computing system of an aircraft having a propulsor that includes a gas turbine engine and an electric machine, cause the one or more processors to: cause, in response to an input indicating a command to change a thrust output of the propulsor of the aircraft, the electric machine operatively coupled with a fan spool of the gas turbine engine to apply a torque on the fan spool so that the thrust output of the propulsor is changed, the fan spool being hydraulically coupled with a core spool of the gas turbine engine via a hydraulic coupling.

These and other features, aspects and advantages of the present subject matter will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the subject matter and, together with the description, explain the principles of the subject matter.

A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:.

The terms "upstream" and "downstream" refer to the relative direction with respect to a flow in a pathway. For example, with respect to a fluid flow, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows. However, the terms "upstream" and "downstream" as used herein may also refer to a flow of electricity.

For example, the approximating language may refer to being within a ten percent margin.

Generally, the present disclosure is directed to aircraft hybrid electric propulsors equipped with a hydraulic coupling. In one example aspect, a propulsor includes a gas turbine engine and an electric machine operatively coupled thereto. For instance, the gas turbine engine can be a turbofan, and thus, the propulsor can be a hybrid electric turbofan. The gas turbine engine includes a fan spool having a fan shaft, a fan, and an impeller. The fan and the impeller are both connected to the fan shaft, e.g., at opposite ends. The electric machine is operatively coupled with the fan spool, e.g., to the fan shaft. The gas turbine engine also includes a core engine. The core engine includes one or more core spools. The core spool has a core shaft, a propeller, and various other components connected thereto, such as compressor and turbine blades.

Notably, a hydraulic coupling is provided to hydraulically couple the fan spool and the core spool. This allows for power transmission between the fan spool and the core spool. Particularly, the hydraulic coupling defines a sealed volume in which hydraulic transmission fluid is provided. The hydraulic coupling encases at least a portion of the fan spool and at least a portion of the core spool. For instance, the impeller of the fan spool and the propeller of the core spool can both be encased within the hydraulic coupling. When the core spool is driven about its axis of rotation, e.g., via extraction of energy by the turbine, the propeller is rotated within the hydraulic fluid contained within the sealed volume, thereby transmitting mechanical power to the impeller of the fan spool, which causes the fan spool to rotate in turn. The fan spool and the core spool can be physically disconnected yet power can be transmitted therebetween via the hydraulic fluid contained within the hydraulic coupling. Stated another way, the fan spool and the core spool need not be physically coupled with one another, e.g., directly or via a gearbox. Further, in some instances, the electric machine can apply a torque to the fan spool. In this regard, the electric machine can be used to change a thrust output of the propulsor. Example manners and methods in which the electric machine can be used to change a thrust output of the propulsor will be provided herein.

The arrangement of the hydraulic coupling with respect to the fan spool and the core spool may provide for a reduction in noise of the propulsor, improved fuel consumption of the gas turbine engine, reduced dioxide emissions, and increased life of the hot section components of the gas turbine engine. In addition, such an arrangement eliminates the need for physically coupling the fan spool with the core spool via a gearbox. Such an arrangement can also eliminate the need for an accessory gearbox. Moreover, such an arrangement provides for an integrated thrust reverse system and can also be integrated into current engine architecture, among other benefits. Further, the architecture of the hybrid electric propulsor provides for the capability of independently controlling the rotational speeds of the spools.

Although example embodiments of a hybrid electric propulsor equipped with a hydraulic coupling are described herein with respect to aviation specific applications, it will be appreciated that the inventive aspects of the present disclosure may be applicable to other suitable industries and applications, such as power generation applications, automotive applications, maritime applications, train applications, among other possible applications.

<FIG> provides a schematic top view of an exemplary aircraft <NUM> as may incorporate various embodiments of the present disclosure. As shown in <FIG>, for reference, the aircraft <NUM> defines a longitudinal direction L1 and a lateral direction L2. The aircraft <NUM> also defines a longitudinal centerline <NUM> that extends therethrough along the longitudinal direction L1. The aircraft <NUM> extends between a forward end <NUM> and an aft end <NUM>, e.g., along the longitudinal direction L1. Moreover, the aircraft <NUM> includes a fuselage <NUM> that extends longitudinally from the forward end <NUM> of the aircraft <NUM> to the aft end <NUM> of the aircraft <NUM>. The aircraft <NUM> also includes an empennage <NUM> at the aft end <NUM> of the aircraft <NUM>. In addition, the aircraft <NUM> includes a wing assembly including a first, port side wing <NUM> and a second, starboard side wing <NUM>. The first and second wings <NUM>, <NUM> each extend laterally outward with respect to the longitudinal centerline <NUM>. The first wing <NUM> and a portion of the fuselage <NUM> together define a first side <NUM> of the aircraft <NUM> and the second wing <NUM> and another portion of the fuselage <NUM> together define a second side <NUM> of the aircraft <NUM>. For the embodiment depicted, the first side <NUM> of the aircraft <NUM> is configured as the port side of the aircraft <NUM> and the second side <NUM> of the aircraft <NUM> is configured as the starboard side of the aircraft <NUM>.

The aircraft <NUM> includes various control surfaces. For this embodiment, each wing <NUM>, <NUM> includes one or more leading edge flaps <NUM> and one or more trailing edge flaps <NUM>. The aircraft <NUM> further includes, or more specifically, the empennage <NUM> of the aircraft <NUM> includes, a vertical stabilizer <NUM> having a rudder flap (not shown) for yaw control and a pair of horizontal stabilizers <NUM> each having an elevator flap <NUM> for pitch control. The fuselage <NUM> additionally includes an outer surface or skin <NUM>. It should be appreciated that in other exemplary embodiments of the present disclosure, the aircraft <NUM> may additionally or alternatively include any other suitable configuration. For example, in other embodiments, the aircraft <NUM> may include any other control surface configuration.

The exemplary aircraft <NUM> of <FIG> also includes a hybrid-electric propulsion system <NUM>. For this embodiment, the hybrid-electric propulsion system <NUM> has a first propulsor <NUM> and a second propulsor <NUM> both operable to produce thrust. The first propulsor <NUM> is mounted to the first wing <NUM> and the second propulsor <NUM> is mounted to the second wing <NUM>. Moreover, for the embodiment depicted, the first propulsor <NUM> and second propulsor <NUM> are each configured in an underwing-mounted configuration. However, in other example embodiments, one or both of the first and second propulsors <NUM>, <NUM> may in other exemplary embodiments be mounted at any other suitable location.

The first propulsor <NUM> includes a gas turbine engine <NUM> and an electric machine <NUM> operatively coupled with the gas turbine engine <NUM>. The electric machine <NUM> can be an electric generator, an electric motor, or a combination generator/motor. For this example embodiment, the electric machine <NUM> is a combination generator/motor. In this manner, when operating as an electric generator, the electric machine <NUM> can generate electrical power when driven by the gas turbine engine <NUM>. When operating as an electric motor, the electric machine <NUM> can drive or motor a fan spool of the gas turbine engine <NUM>. Moreover, for this example embodiment, the gas turbine engine <NUM> is configured as a turbofan, and thus, the first propulsor <NUM> is configured as a hybrid electric turbofan.

Likewise, the second propulsor <NUM> includes a gas turbine engine <NUM> and an electric machine <NUM> operatively coupled with the gas turbine engine <NUM>. The electric machine <NUM> can be an electric generator, an electric motor, or a combination generator/motor. For this example embodiment, the electric machine <NUM> is a combination generator/motor. In this manner, when operating as an electric generator, the electric machine <NUM> can generate electrical power when driven by the gas turbine engine <NUM>. When operating as an electric motor, the electric machine <NUM> can drive or motor a fan spool of the gas turbine engine <NUM>. Furthermore, for this example embodiment, the gas turbine engine <NUM> is configured as a turbofan, and thus, the second propulsor <NUM> is configured as a hybrid electric turbofan.

The hybrid-electric propulsion system <NUM> further includes an electric energy storage unit <NUM> electrically connectable to the electric machines <NUM>, <NUM>, and in some embodiments, other electrical loads. The electric energy storage unit <NUM> may be configured as one or more batteries, such as one or more lithium-ion batteries, or alternatively may be configured as any other suitable electrical energy storage devices, such as supercapacitors. For the hybrid-electric propulsion system <NUM> described herein, the electric energy storage unit <NUM> is configured to store a relatively large amount of electrical power. For example, in certain exemplary embodiments, the electric energy storage unit <NUM> may be configured to store at least about fifty kilowatt hours of electrical power, such as at least about sixty-five kilowatt hours of electrical power, such as at least about seventy-five kilowatts hours of electrical power, and up to about one thousand kilowatt hours of electrical power.

The hybrid-electric propulsion system <NUM> also includes a power management system having a controller <NUM> and a power bus <NUM>. The electric machines <NUM>, <NUM>, the electric energy storage unit <NUM>, and the controller <NUM> are each electrically connectable to one another through one or more electric lines <NUM> of the power bus <NUM>. For instance, the power bus <NUM> may include various switches or other power electronics movable to selectively electrically connect the various components of the hybrid-electric propulsion system <NUM>. Additionally, the power bus <NUM> may further include power electronics, such as inverters, converters, rectifiers, etc., for conditioning or converting electrical power within the hybrid-electric propulsion system <NUM>.

The controller <NUM> is configured to distribute electrical power between the various components of the hybrid-electric propulsion system <NUM>. For example, the controller <NUM> may control the power electronics of the power bus <NUM> to provide electrical power to, or draw electrical power from, the various components, such as the electric machines <NUM>, <NUM>, to operate the hybrid-electric propulsion system <NUM> between various operating modes and perform various functions. Such is depicted schematically as the electric lines <NUM> of the power bus <NUM> extend through the controller <NUM>.

The controller <NUM> can form a part of a computing system <NUM> of the aircraft <NUM>. The computing system <NUM> of the aircraft <NUM> can include one or more processors and one or more memory devices embodied in one or more computing devices. For instance, as depicted in <FIG>, the computing system <NUM> includes controller <NUM> as well as other computing devices, such as computing device <NUM>. The computing system <NUM> can include other computing devices as well, such as engine controllers (not shown). The computing devices of the computing system <NUM> can be communicatively coupled with one another via a communication network. For instance, computing device <NUM> is located in the cockpit of the aircraft <NUM> and is communicatively coupled with the controller <NUM> of the hybrid-electric propulsion system <NUM> via a communication link <NUM> of the communication network. The communication link <NUM> can include one or more wired or wireless communication links.

For this embodiment, the computing device <NUM> is configured to receive and process inputs, e.g., from a pilot or other crew members, and/or other information. In this manner, as one example, the one or more processors of the computing device <NUM> can receive an input indicating a command to change a thrust output of the first and/or second propulsors <NUM>, <NUM> and can cause, in response to the input, the controller <NUM> to control the electrical power drawn from or delivered to one or both of the electric machines <NUM>, <NUM> to ultimately change the thrust output of one or both of the propulsors as will be explained herein.

The controller <NUM> and other computing devices of the computing system <NUM> of the aircraft <NUM> may be configured in substantially the same manner as the exemplary computing devices of the computing system <NUM> described below with reference to <FIG> (and may be configured to perform one or more of the functions of the exemplary method (<NUM>) described below).

<FIG> provides a schematic view of the first propulsor <NUM> of the hybrid-electric propulsion system <NUM> of the aircraft <NUM> of <FIG>. Although the first propulsor <NUM> is shown, it will be appreciated that the second propulsor <NUM> can be configured in the same or similar manner as the first propulsor <NUM> depicted in <FIG>. For reference, the first propulsor <NUM> defines an axial direction A, a radial direction R, a longitudinal or axial centerline AX extending therethrough along the axial direction A, and a circumferential direction C extending three hundred sixty degrees around the axial centerline AX.

As noted above, the first propulsor <NUM> includes gas turbine engine <NUM> and electric machine <NUM> operatively coupled thereto. The gas turbine engine <NUM> can be configured as any suitable type of aviation gas turbine engine, such as a turbofan, a turboprop, a turboshaft, or some other suitable configuration. For this embodiment, the gas turbine engine <NUM> is configured as a turbofan, and as the electric machine <NUM> is operatively coupled thereto, the first propulsor <NUM> is a hybrid electric turbofan.

As shown in <FIG>, the gas turbine engine <NUM> includes a fan <NUM> and a core engine <NUM> disposed downstream of the fan <NUM>. The fan <NUM> forms a part of a fan spool <NUM> that is rotatable about an axis of rotation, such as the axial centerline AX. The fan spool <NUM> includes the fan <NUM>, an impeller <NUM>, and a fan shaft <NUM> connecting the fan <NUM> and the impeller <NUM>. For this embodiment, the fan <NUM> is connected to a forward end of the fan shaft <NUM> and the impeller <NUM> is connected to an aft end of the fan shaft <NUM>. The fan <NUM> includes a plurality of fan blades <NUM> circumferentially spaced from one another. The fan blades <NUM> can be fixed or can be pitched in unison about respective pitch axes by an actuation member. The fan <NUM> can be ducted as shown in <FIG> or can be unducted. Particularly, for this embodiment, an annular fan casing <NUM> circumferentially surrounds the fan <NUM> and at least a portion of the core engine <NUM>. Accordingly, the exemplary gas turbine engine <NUM> depicted may be referred to as a "ducted" engine. The fan casing <NUM> can be supported relative to the core engine <NUM> by a plurality of circumferentially-spaced outlet guide vanes (not shown). The fan casing <NUM> defines an inlet <NUM> through which air may flow into the first propulsor <NUM>. A downstream section of the fan casing <NUM> extends axially over a portion of the core engine <NUM> so as to define a bypass airflow passage <NUM> therebetween. Air flowing through the bypass airflow passage <NUM> exits the bypass airflow passage <NUM> through downstream outlet <NUM>.

The core engine <NUM> includes a substantially tubular engine cowl <NUM> that defines an annular core inlet <NUM>. The engine cowl <NUM> encases, in serial flow relationship, a compressor section including a compressor <NUM>; a combustion section including a combustor <NUM>; a turbine section including a turbine <NUM>; and a jet exhaust nozzle section <NUM>. The compressor section, combustion section, and turbine section together define at least in part a core flowpath <NUM>. The compressor <NUM> can be a multi-stage, axial-flow compressor that increases the pressure of the air flowing along the core flowpath <NUM>. The compressor <NUM> can include a number of stages of compressor stator vanes and corresponding rotatable blades <NUM> (represented schematically in <FIG>). The turbine <NUM> can include one or more stages of turbine stator vanes and corresponding rotatable blades <NUM> as well (represented schematically in <FIG>).

The core engine <NUM> of the gas turbine engine <NUM> also includes a core spool <NUM> rotatable about an axis of rotation, such as the axial centerline AX. For this embodiment, the core spool <NUM> and the fan spool <NUM> are rotatable about the same axis of rotation, e.g., the axial centerline AX of the first propulsor <NUM>. In other embodiments, however, the axis of rotation of the fan spool <NUM> can be offset from the axis of rotation of the core spool <NUM>, e.g., along the radial direction R. The core spool <NUM> has a core shaft <NUM> and a propeller <NUM> connected to the core shaft <NUM>. Furthermore, the rotatable blades <NUM> of the compressor <NUM> and the rotatable blades <NUM> of the turbine can be coupled with the core shaft <NUM> and thus can form part of the core spool <NUM>. In this regard, the core shaft <NUM> drivingly connects the turbine <NUM> and the compressor <NUM>.

As further shown in <FIG>, the gas turbine engine <NUM> of the first propulsor <NUM> further includes a hydraulic coupling <NUM>. The hydraulic coupling <NUM> encases at least a portion of the fan spool <NUM> and at least a portion of the core spool <NUM>. Particularly, for this embodiment, the impeller <NUM> of the fan spool <NUM> is at least partially encased within the hydraulic coupling <NUM> and the propeller <NUM> of the core spool <NUM> is at least partially encased within the hydraulic coupling <NUM>. More particularly still, for this embodiment, the impeller <NUM> of the fan spool <NUM> and the propeller <NUM> of the core spool <NUM> are both completely encased within the hydraulic coupling <NUM>.

The hydraulic coupling <NUM> defines a sealed volume <NUM> in which hydraulic fluid is provided. The hydraulic fluid can be any suitable non-compressible liquid, for example. The hydraulic fluid can be moved into the sealed volume <NUM> as shown schematically in <FIG> by arrow HF. The hydraulic fluid can be stored in a sump or reservoir and provided to the sealed volume <NUM>, for example. The hydraulic fluid can be moved into the sealed volume <NUM> continuously, periodically, or as needed, e.g., based on the working temperature of the hydraulic fluid, the thrust demanded from the propulsor, etc. The hydraulic fluid can be drained from the sealed volume <NUM> as schematically depicted in <FIG> by the dashed line HFD. The drained hydraulic fluid can be cooled and particulates can be removed as necessary before being returned to the sump, for example, but ultimately before being returned to the sealed volume <NUM> of the hydraulic coupling <NUM>.

Generally, the hydraulic coupling <NUM> hydraulically couples the fan spool <NUM> and the core spool <NUM>. In this regard, mechanical power can be transmitted from the core spool <NUM> to the fan spool <NUM>. As depicted, for this embodiment, the fan spool <NUM> and the core spool <NUM> are spaced from one another along the axial direction A. Particularly, for this embodiment, the fan spool <NUM> and the core spool <NUM> are spaced from one another along the axial direction A and can be aligned with one another along the radial direction R (e.g., the spools <NUM>, can be coaxial with one another with respect to the radial direction R). In this regard, the fan spool <NUM> and the core spool <NUM> are not physically connected to one another and transmission of power occurs via the hydraulic fluid provided within the sealed volume <NUM> of the hydraulic coupling <NUM>.

Moreover, for this embodiment, the hydraulic coupling <NUM> is formed by at least two complementary shells connected together. Particularly, for the depicted embodiment of <FIG>, the hydraulic coupling <NUM> has a first shell <NUM> and a second shell <NUM> connected together. As one example, the first shell <NUM> and the second shell <NUM> can be bolted together. In other example embodiments, the hydraulic coupling <NUM> can be formed as a single unitary monolithic component. The hydraulic coupling <NUM> can be formed via an additive manufacturing process (e.g., 3D printing), for example.

Referring still to <FIG>, the electric machine <NUM> of the first propulsor <NUM> includes a rotor <NUM> and a stator <NUM>. The rotor <NUM> operatively couples the electric machine <NUM> with the fan spool <NUM>, or more particularly with the fan shaft <NUM> of the fan spool <NUM>, and rotates within the stator <NUM> about an axis of rotation. In this regard, the rotor <NUM> of the electric machine <NUM> is in mechanical communication with the fan shaft <NUM>. For this embodiment, the electric machine <NUM> is mounted coaxially with the fan shaft <NUM>. However, in other example embodiments, the electric machine <NUM> can be positioned offset from the fan shaft <NUM> and can be mechanically coupled thereto via a suitable gear train.

The electric machine <NUM> may be operable in a generator mode or in drive mode. When operating in a generator mode, the electric machine <NUM> is configured to convert mechanical power output by the fan shaft <NUM> to electrical power such that the fan shaft <NUM> drives the electric machine <NUM>. Alternatively, when operating in a drive mode, the electric machine <NUM> is configured to convert electrical power provided thereto into mechanical power for the fan shaft <NUM> such that the electric machine <NUM> drives, or assists with driving, the fan shaft <NUM>. That is, when the electric machine <NUM> operates as an electric motor and electrical power is directed thereto, the rotor <NUM> is driven by an interaction between windings and/or magnetic fields of the rotor <NUM> and stator <NUM> as will be appreciated by those of skill in the art. The rotation of the rotor <NUM> causes the electric machine <NUM> to apply torque to the fan shaft <NUM> such that a rotational speed of the fan spool <NUM> is changed (e.g., increased or decreased). In this manner, the rotational speed of the fan spool <NUM> can be changed independent of the core spool <NUM>. Further, although the electric machine <NUM> is described as an electric motor/generator, in other exemplary embodiments, the electric machine <NUM> may be configured solely as an electric generator or solely as an electric motor.

The first propulsor <NUM> further includes a controller <NUM> and a plurality of sensors (not shown). The controller <NUM> may be an Electronic Engine Controller (EEC) that is a component of a Full Authority Digital Engine Control (FADEC) system, for example. The controller <NUM> of the first propulsor <NUM> may be configured to control operation of various components of the gas turbine engine <NUM>, e.g., components of a fuel delivery system that selectively provides fuel to the combustor <NUM>. Additionally, referring back also to <FIG>, the controller <NUM> of the first propulsor <NUM> is communicatively coupled with the controller <NUM> as well as other components of the computing system <NUM>, such as the computing device <NUM> positioned in or proximate the cockpit of the aircraft <NUM>. Moreover, as will be appreciated, the controller <NUM> may further be communicatively coupled with one or more components of hybrid-electric propulsion system <NUM>, including the electric machine <NUM>, components of the second propulsor <NUM>, and the electric energy storage unit <NUM> via the communication network, e.g., via through a suitable wired or wireless connection.

The electric machine <NUM> of the first propulsor <NUM> can be used to control the thrust output of the first propulsor <NUM> in a number of example manners. For instance, in some embodiments with reference to <FIG> and <FIG>, one or more processors of the controller <NUM> can receive an input indicating a command to change a thrust output of the first propulsor <NUM>. For instance, an input can be provided to the one more processors of the computing device <NUM> locating in the cockpit of the aircraft <NUM>. The input can indicate that a change in thrust output of the propulsor is desired. As one example, a pilot or crew member can move a thrust lever within the cockpit indicating the desired change in thrust. As another example, a flight system can automatically provide an input to the computing device <NUM> indicating that a change in thrust output of the propulsor is desired, e.g., based on one or more flight operating conditions, detected threats, etc. The computing device <NUM> can receive the input and can communicate the input over the aircraft communication network to the controller <NUM>, e.g., over communication link <NUM>.

With the input received, the one or more processors of the controller <NUM> can cause, in response to receiving the input, the electric machine <NUM> operatively coupled with the fan spool <NUM> to apply a torque on the fan spool <NUM> so that the thrust output of the first propulsor <NUM> is changed. As will be appreciated, additionally or alternatively, the one or more processors of the controller <NUM> can cause the electric machine <NUM> of the second propulsor <NUM> to apply a torque to the fan spool of the second propulsor <NUM> so that the thrust output of the second propulsor <NUM> is changed, e.g., in the same manner as described above.

In some embodiments, the input indicating a command to change the thrust output of the first propulsor <NUM> can be a demand to increase the thrust output of the propulsor, e.g., for power assists during takeoff, climb, evasive maneuvers, etc. In such implementations, in response to receiving the input, the electric machine <NUM> is caused or controlled by the controller <NUM> to apply the torque on the fan spool <NUM> so that a rotational speed of the fan spool <NUM> is increased. As one example, the controller <NUM> can cause, based on the received input, electrical power to be provided to the electric machine <NUM> of the first propulsor <NUM>. For instance, electrical power from the electric energy storage unit <NUM> can be provided to the electric machine <NUM>. The provided electrical power can cause the electric machine <NUM> to apply a torque to the fan spool <NUM> so that a rotational speed of the fan spool <NUM> is increased. In this manner, the thrust output of the first propulsor <NUM> is increased. The increased rotational speed of the fan spool <NUM> can cause the fan <NUM> to increase the pressure of the air flowing thereacross into the bypass passage <NUM> and core inlet <NUM>, which ultimately increases the thrust output of the first propulsor <NUM>. Notably, with the increase in rotational speed of the fan spool <NUM> being caused by the applied torque provided by the electric machine <NUM>, the thrust output of the first propulsor <NUM> can be increased without increased fuel to the combustor <NUM> assuming all other variables remain the same. Stated another way, this arrangement will help to reduce the amount of energy needed from the turbine at high power configurations. Therefore it reduces fuel consumption, emissions, and noise during aircraft operation.

In other embodiments, the electric machine <NUM> of the first propulsor <NUM> can be used to control the thrust output of the first propulsor <NUM> by operating the first propulsor <NUM> in a reverse thrust mode. For instance, by way of example, the one or more processors of the controller <NUM> can receive an input indicating a command to operate the first propulsor <NUM> in a reverse thrust mode. The one or more processors of the controller <NUM> can cause, in response to the input, electrical power to be provided to the electric machine <NUM> of the first propulsor <NUM>. For instance, electrical power from the electric energy storage unit <NUM> can be provided to the electric machine <NUM>. The provided electrical power can cause the electric machine <NUM> to apply a torque to or on the fan spool <NUM> so that the fan spool <NUM> rotates in a direction opposite the core spool <NUM>. In this manner, the thrust output of the first propulsor <NUM> is changed in that the thrust output is decreased, and in some instances, to the point where the first propulsor <NUM> reverses thrust. Accordingly, the first propulsor <NUM> can include an integrated thrust reverser system. To operate the first propulsor <NUM> in the reverse thrust mode, no variable geometry on the outer nacelle (not shown) or other components need be moved to achieve reverse thrust save for rotating the fan spool <NUM> in a direction opposite the core spool <NUM>. As will be appreciated, the second propulsor <NUM> can be operated in the reverse thrust mode in the same manner as described above with reference to the first propulsor <NUM>. In some instances, the first and second propulsors <NUM>, <NUM> can be operated in the reverse thrust mode simultaneously, e.g., during landing of the aircraft <NUM>.

In yet other example embodiments, with reference still to <FIG> and <FIG>, the one or more processors of the controller <NUM> can receive an input indicating a command to operate the electric machine <NUM> of the first propulsor <NUM> in a generator mode. For instance, a flight system of the aircraft <NUM> can indicate that the aircraft <NUM> is operating in a cruise mode or cruise segment of flight and can generate an input. The input can be received by the computing device <NUM> and communicated to the one or more processors of the controller <NUM>. The one or more processors of the controller <NUM> can cause, in response to the input, the electric machine <NUM> to generate electrical power. The generated electric power can be provided to one or more electrical loads onboard the aircraft <NUM>, such as the electric energy storage unit <NUM>, aircraft systems, etc..

<FIG> provides a schematic view of another hybrid electric propulsor <NUM> for an aircraft according to one example embodiment of the present disclosure. The hybrid electric propulsor <NUM> of <FIG> is similarly configured as the hybrid electric propulsor <NUM> of <FIG> except as provided below. Similar reference numerals are used to identify like parts and structures.

For this embodiment, the core engine <NUM> of the hybrid electric propulsor <NUM> includes a low pressure system and a high pressure system. Particularly, the core engine <NUM> includes a low pressure spool <NUM> and a high pressure spool <NUM>. The low pressure spool <NUM> has a low pressure shaft <NUM> rotatable about an axis of rotation AX. As depicted, the propeller <NUM> is connected to the low pressure shaft <NUM> of the low pressure spool <NUM>. The propeller <NUM> of the low pressure spool <NUM> is encased at least partially within the hydraulic coupling <NUM>. In this regard, in some embodiments, the core spool at least partially encased within the hydraulic coupling <NUM> can be a low pressure spool. The low pressure system can also include a low pressure compressor <NUM> or booster and a low pressure turbine <NUM> both having rotatable blades connected to the low pressure shaft <NUM>.

The high pressure spool <NUM> has a high pressure shaft <NUM> rotatable about an axis of rotation AX. For this embodiment, the high pressure shaft <NUM> is coaxial with the low pressure shaft <NUM>. The high pressure system can also include a high pressure compressor <NUM> and a high pressure turbine <NUM> both having rotatable blades connected to the high pressure shaft <NUM>.

In addition, the inventive aspects of the present disclosure may apply to turbomachines or core engines having more than two core spools. For instance, the inventive aspects of the present disclosure can apply to a gas turbine engine for an aerial vehicle or aircraft having a high pressure spool, an intermediate pressure spool, and a low pressure spool. As will be explained herein, an electric machine can be operatively coupled to the low pressure spool and can be controlled to apply a torque thereto, e.g., as described above.

<FIG> provides a flow diagram of an exemplary method (<NUM>) of operating a hybrid electric propulsor in accordance with exemplary embodiments of the present disclosure. For instance, the exemplary method (<NUM>) may be utilized to operate the hybrid electric propulsor <NUM> and/or <NUM> of the aircraft <NUM> described herein. In this regard, the exemplary method (<NUM>) may be utilized to operate a hybrid electric propulsor having a fan spool and a core spool. The fan spool has a fan, an impeller, and a fan shaft connecting the fan and the impeller. The core spool has a core shaft and a propeller connected to the core shaft. The impeller and the propeller can be both at least partially encased within the hydraulic coupling. The hydraulic coupling can define a sealed volume in which hydraulic fluid is provided. Mechanical power can be transmitted from the core spool to the fan spool via the hydraulic transmission fluid. The electric machine can be operatively coupled with the fan spool, and as provided below, can be utilized to control the thrust output of the propulsor. It should be appreciated that the method (<NUM>) is discussed herein to describe exemplary aspects of the present subject matter and is not intended to be limiting.

At (<NUM>), the method (<NUM>) includes receiving an input indicating a command to change a thrust output of the propulsor. For instance, with reference to <FIG> and <FIG>, an input can be provided to the computing device <NUM> indicating that a change in thrust output of the propulsor is desired. As one example, a pilot or crew member can move a thrust lever within the cockpit indicating the desired change in thrust. As another example, a flight system can automatically provide an input to the computing device <NUM> indicating that a change in thrust output of the propulsor is desired, e.g., based on one or more flight operating conditions, detected threats, etc. The computing device <NUM> can receive the input and can communicate the input over the aircraft communication network to the controller <NUM>, e.g., over communication link <NUM>.

At (<NUM>), with refence again to <FIG>, the method (<NUM>) includes causing, in response to receiving the input, an electric machine operatively coupled with a fan spool of a gas turbine engine to apply a torque on the fan spool so that the thrust output of the propulsor is changed, the fan spool being hydraulically coupled with a core spool of a gas turbine engine via a hydraulic coupling. For instance, with reference to <FIG> and <FIG>, the controller <NUM> can cause the electric machine <NUM> of the first propulsor <NUM> to apply a torque to the fan spool <NUM> so that the thrust output of the first propulsor <NUM> is changed. Additionally or alternatively, the controller <NUM> can cause the electric machine <NUM> of the second propulsor <NUM> to apply a torque to the fan spool of the second propulsor <NUM> so that the thrust output of the second propulsor <NUM> is changed.

In some implementations, for instance, the input indicating a command to change the thrust output of the propulsor is a demand to increase the thrust output of the propulsor, e.g., for power assists during takeoff, climb, evasive maneuvers, etc. In such implementations, in response to receiving the input, the electric machine is caused or controlled to apply the torque on the fan spool so that a rotational speed of the fan spool is increased.

By way of example, the electric machine <NUM> can be controlled to operate in a drive mode to increase a rotational speed of the fan spool <NUM>. Particularly, the controller <NUM> can cause, based on the received input, electrical power to be provided to the electric machine <NUM> of the first propulsor <NUM>. For instance, electrical power from the electric energy storage unit <NUM> can be provided to the electric machine <NUM>. The provided electrical power can cause the electric machine <NUM> to apply a torque to the fan spool <NUM> so that a rotational speed of the fan spool <NUM> is increased. In this manner, the thrust output of the first propulsor <NUM> is changed in that the thrust output is increased. The increased rotational speed of the fan spool <NUM> can cause the fan <NUM> to increase the pressure of the air flowing thereacross into the bypass passage <NUM> and core inlet <NUM>, which ultimately increases the thrust output of the first propulsor <NUM>. Notably, with the increase in rotational speed of the fan spool <NUM> being caused by the applied torque provided by the electric machine <NUM>, the thrust output of the first propulsor <NUM> can be increased without increased fuel to the combustor <NUM> assuming all other variables remain the same.

According to the invention, the command to change the thrust output of the propulsor is a demand to operate the propulsor in a reverse thrust mode. In such implementations, in response to receiving the input, the electric machine is caused or controlled to apply the torque on the fan spool so that the fan spool rotates in a direction opposite the core spool.

The electric machine <NUM> can be controlled to operate in a drive mode, or more particularly in a reverse drive mode, to ultimately reverse a rotational direction of the fan spool <NUM> so that it rotates in a direction opposite the core spool <NUM>. Particularly, the controller <NUM> can cause, based on the received input, electrical power to be provided to the electric machine <NUM> of the first propulsor <NUM>. For instance, electrical power from the electric energy storage unit <NUM> can be provided to the electric machine <NUM>. The provided electrical power can cause the electric machine <NUM> to apply a torque to or on the fan spool <NUM> so that the fan spool <NUM> rotates in a direction opposite the core spool <NUM>. In this manner, the thrust output of the first propulsor <NUM> is changed in that the thrust output is decreased, and in some instances, to the point where the first propulsor <NUM> reverses thrust. Accordingly, the first propulsor <NUM> can include an integrated thrust reverser system. To operate the first propulsor <NUM> in the reverse thrust mode, no variable geometry on the outer nacelle (not shown) or other components need be moved to achieve reverse thrust save for rotating the fan spool <NUM> in a direction opposite the core spool <NUM>.

In yet another example method, with reference to <FIG> and <FIG>, the computing system <NUM> can have one or more processors configured to receive an input indicating a command to operate the electric machine <NUM> of the first propulsor <NUM> in a generator mode. For instance, a flight system of the aircraft <NUM> can indicate that the aircraft <NUM> is operating in a cruise mode or cruise segment of flight and can generate an input. The input can be received by the computing device <NUM> and communicated to the controller <NUM>. The one or more processors, e.g., of the controller <NUM>, can further be configured to cause, in response to the input, the electric machine <NUM> to generate electrical power. The generated electric power can be provided to one or more electrical loads onboard the aircraft <NUM>, such as the electric energy storage unit <NUM>, aircraft systems, etc..

<FIG> provides an example computing system <NUM> according to example embodiments of the present disclosure. The computing system <NUM> described herein may include various components and perform various functions of the computing system <NUM> described below, for example.

As shown in <FIG>, the computing system <NUM> can include one or more computing device(s) <NUM>. The computing device(s) <NUM> can include one or more processor(s) 510A and one or more memory device(s) 510B. The one or more processor(s) 510A can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and/or other suitable processing device. The one or more memory device(s) 510B can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and/or other memory devices.

The one or more memory device(s) 510B can store information accessible by the one or more processor(s) 510A, including computer-readable instructions 510C that can be executed by the one or more processor(s) 510A. The instructions 510C can be any set of instructions that when executed by the one or more processor(s) 510A, cause the one or more processor(s) 510A to perform operations. In some embodiments, the instructions 510C can be executed by the one or more processor(s) 510A to cause the one or more processor(s) 510A to perform operations, such as any of the operations and functions for which the computing system <NUM> and/or the computing device(s) <NUM> are configured, such as operations for causing an electric machine of a propulsor to electrically assist the gas turbine engine to produce more thrust during transient operation, operations for generating electrical power during cruise flight, and/or operations for causing a fan of a hybrid electric propulsor to function as a thrust reverser. The instructions 510C can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the instructions 510C can be executed in logically and/or virtually separate threads on processor(s) 510A. The memory device(s) 510B can further store data 510D that can be accessed by the processor(s) 510A. For example, the data 510D can include models, databases, etc..

The computing device(s) <NUM> can also include a network interface 510E used to communicate, for example, with the other components of system <NUM> (e.g., via a communication network). The network interface 510E can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, and/or other suitable components. One or more devices can be configured to receive one or more commands from the computing device(s) <NUM> or provide one or more commands to the computing device(s) <NUM>.

Claim 1:
A propulsor (<NUM>, <NUM>), comprising:
an electric machine (<NUM>, <NUM>); and
a gas turbine engine (<NUM>, <NUM>), comprising:
a fan spool (<NUM>), the electric machine (<NUM>, <NUM>) being operatively coupled with the fan spool (<NUM>);
a core spool (<NUM>); and
a hydraulic coupling (<NUM>) encasing at least a portion of the fan spool (<NUM>) and at least a portion of the core spool (<NUM>), the hydraulic coupling (<NUM>) hydraulically coupling the fan spool (<NUM>) and the core spool (<NUM>)
wherein the propulsor is operable in a reverse thrust mode, in which the electric machine is configured to apply torque on the fan spool so that the fan spool rotates in a direction opposite the core spool.