Patent Description:
Typical aircraft propulsion systems include one or more gas turbine engines. For certain propulsion systems, the gas turbine engines generally include a fan and a core arranged in flow communication with one another. Additionally, the core of the gas turbine engine general includes, in serial flow order, downstream of the fan, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is provided from the fan to an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are routed from the combustion section to the turbine section. The flow of combustion gasses through the turbine section drives the turbine section and is then routed through the exhaust section, e.g., to atmosphere.

For certain aircraft propulsion systems, and aircraft incorporating such aircraft propulsion systems, it may be beneficial for the propulsion system to include an electric machine to, e.g., generate electrical power for various accessory systems of the gas turbine engines and/or the aircraft, for electric or hybrid electric propulsion devices, etc. One issue with permanent magnet electric machines is that in the event of a fault condition, such as a short within a stator coil, continued rotation of the rotor continues to generate a magnetic flux/ electric flow through such fault, potentially creating high temperatures. When the electric machine is tied to an integral part of the aircraft propulsion system, such as a primary gas turbine engine, it may not be practical to shut down the gas turbine engine to prevent rotation of the rotor of the electric machine.

Accordingly, a propulsion system for an aircraft having an electric machine capable of addressing one or more of these issues would be useful.

<CIT> relates to a retractable modular stator for an electric motor/generator. <CIT> relates to a high speed electric machine with a tracking tooth that is radially moveable to adjust the height of an air gap. <CIT> relates to radially actuated stator cores for a hubless rotor. XP <NUM>, "<NPL>, relates to stator elements that are radially moveable. <CIT> relates to an engine with a permanent magnet electric machine.

Approximating language, as used herein throughout the description (but not the claims), is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. For example, the approximating language may refer to being within a <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent margin in either individual values, range(s) of values and/or endpoints defining range(s) of values.

Here and throughout the description (but not the claims), range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

Aspects of the present disclosure are directed to an electric machine having a segmented and movable stator, a turbomachine having such an electric machine embedded therein, and a method of operating such an electric machine. In one aspect, a turbomachine defines a radial direction and includes a rotating component, actuators, and an electric machine. The turbomachine can be an aviation gas turbine engine, for example. The rotating component can be one of a low pressure and a high pressure shaft or spool, for example. The electric machine includes a rotor assembly rotatable with and operatively coupled with the rotating component. The electric machine also includes a stator assembly having a stator split or segmented into stator segments. Each one of the stator segments is movable by one of the actuators between a first position and a second position along the radial direction. The stator segments are closer to the rotor assembly along the radial direction when in the first position than when in the second position. Moving the stator segments relative to the rotor assembly can prevent or mitigate damage when faults or failures associated with the electric machine are detected and can be used to control the amount of power extracted by the electric machine, among other benefits.

Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures, <FIG> is a schematic cross-sectional view of a propulsion engine in accordance with an exemplary embodiment of the present disclosure. In certain exemplary embodiments, the propulsion engine may be configured as a turbofan jet engine, herein referred to as "turbofan <NUM>. " The turbofan <NUM> can be incorporated into an aircraft propulsion system, e.g., as an under-wing mounted turbofan engine. Alternatively, however, in other embodiments, the turbofan <NUM> may be incorporated into any other suitable aircraft or propulsion system. As shown in <FIG>, the turbofan <NUM> defines an axial direction A (extending parallel to a longitudinal centerline <NUM> provided for reference) and a radial direction R. The turbofan <NUM> also defines a circumferential direction C (<FIG>).

The turbofan <NUM> includes a fan section <NUM> and a core engine <NUM> disposed downstream of the fan section <NUM>. The core turbine engine <NUM> depicted includes a substantially tubular outer casing <NUM> that defines an annular core inlet <NUM>. The outer casing <NUM> encases, in serial flow relationship, a compressor section including a booster or Low Pressure (LP) compressor <NUM> and a High Pressure (HP) compressor <NUM>; a combustion section <NUM>; a turbine section including an HP turbine <NUM> and an LP turbine <NUM>; and a jet exhaust nozzle section <NUM>. The compressor section, combustion section <NUM>, and turbine section together define a core air flowpath <NUM> extending from the annular core inlet <NUM> through the LP compressor <NUM>, HP compressor <NUM>, combustion section <NUM>, HP turbine section <NUM>, LP turbine section <NUM>, and jet nozzle exhaust section <NUM>. An HP shaft or spool <NUM> drivingly connects the HP turbine <NUM> to the HP compressor <NUM>. An LP shaft or spool <NUM> drivingly connects the LP turbine <NUM> to the LP compressor <NUM>.

The fan section <NUM> includes a variable pitch fan <NUM> having a plurality of fan blades <NUM> coupled to a disk <NUM> in a spaced apart manner. As depicted, the fan blades <NUM> extend outward from the disk <NUM> generally along the radial direction R. The fan blades <NUM> and disk <NUM> are together rotatable about the longitudinal centerline <NUM> by the LP shaft <NUM> across a power gear box <NUM>. The power gear box <NUM> includes a plurality of gears for adjusting the rotational speed of the LP shaft <NUM>. Additionally, for the embodiment depicted, the disk <NUM> of the variable pitch fan <NUM> is covered by a rotatable spinner or front hub <NUM> aerodynamically contoured to promote an airflow through the plurality of fan blades <NUM>.

The turbofan <NUM> also includes a plurality of circumferentially-spaced outlet guide vanes <NUM>. The plurality of outlet guide vanes <NUM> are positioned downstream of the fan <NUM> along the axial direction A and extend outward from the outer casing <NUM> of the core engine <NUM> generally along the radial direction R. Notably, for the embodiment depicted in <FIG>, the turbofan <NUM> does not include any outer fan casing enclosing the fan section <NUM> and/or outlet guide vanes <NUM>. Moreover, the fan section <NUM> only includes a single fan. Accordingly, the turbofan <NUM> depicted in <FIG> may be referred to as an Unducted Single Fan (USF) turbofan.

For the exemplary turbofan <NUM> depicted, the fan section <NUM>, or more particularly, the rotation of the fan blades <NUM> of the fan <NUM>, provides a majority of the propulsive thrust of the turbofan <NUM>. Additionally, the plurality of outlet guide vanes <NUM> are provided to increase an efficiency of the fan section <NUM> as well as to provide other benefits, such as decreasing an amount of noise generated by the turbofan <NUM>, by directing a flow of air from the plurality of fan blades <NUM> of the fan section <NUM>.

During operation of the turbofan <NUM>, a volume of air <NUM> passes over the plurality of blades <NUM> of the fan section <NUM>. A first portion of the volume of air <NUM>, i.e., the first portion of air <NUM>, is directed or routed into the core air flowpath <NUM> extending through the compressor section, the combustion section <NUM>, the turbine section, and the exhaust section <NUM>. Additionally, a second portion of the volume of air <NUM>, i.e. a second portion of air <NUM>, flows around the core engine <NUM>, bypassing the core engine <NUM> (i.e., in a bypass air flowpath). The ratio between the second portion of air <NUM> and the first portion of air <NUM> is commonly known as a bypass ratio.

The pressure of the first portion of air <NUM> is increased as it is routed through the LP compressor <NUM> and subsequently through the HP compressor <NUM>. The compressed first portion of air <NUM> is then provided to the combustion section <NUM>, where it is mixed with fuel and burned to provide combustion gases <NUM>. The combustion gases <NUM> are routed through the HP turbine <NUM> where a portion of thermal and/or kinetic energy from the combustion gases <NUM> is extracted via sequential stages of HP turbine stator vanes <NUM> that are coupled to the outer casing <NUM> and HP turbine rotor blades <NUM> that are coupled to the HP shaft <NUM>. Extraction of thermal and/or kinetic energy from the combustion gases <NUM> causes the HP shaft <NUM> to rotate, thereby supporting operation of the HP compressor <NUM>. The combustion gases <NUM> are then routed through the LP turbine <NUM> where a second portion of thermal and kinetic energy is extracted from the combustion gases <NUM> via sequential stages of LP turbine stator vanes <NUM> that are coupled to the outer casing <NUM> and LP turbine rotor blades <NUM> that are coupled to the LP shaft <NUM>, thus causing the LP shaft or spool <NUM> to rotate, thereby supporting operation of the LP compressor <NUM> and/or rotation of the fan <NUM>. The combustion gases <NUM> are subsequently routed through the jet exhaust nozzle section <NUM> of the core engine <NUM> to provide propulsive thrust to supplement propulsive thrust provided by the fan <NUM>.

As further shown in <FIG>, the exemplary turbofan <NUM> includes an electric machine <NUM> embedded therein. For this embodiment, the electric machine <NUM> is operatively coupled with the low pressure system of the turbofan <NUM>, and more particularly, the LP shaft <NUM>. The electric machine <NUM> includes a rotor assembly <NUM> and a stator assembly <NUM>. The rotor assembly <NUM> is rotatable with one or more rotatable components of the turbofan <NUM>. Specifically, for this embodiment, the rotor assembly <NUM> is mounted to and is rotatable with the LP shaft <NUM>. Further, the electric machine <NUM> is arranged co-axially with the LP shaft <NUM>. As used herein, "co-axially" refers to the axes being aligned. It should be appreciated, however, that in other embodiments, an axis of the electric machine <NUM> may be offset radially from the axis of the LP shaft <NUM>. The rotor assembly <NUM> and the stator assembly <NUM> define an air gap <NUM> (<FIG>) therebetween. As will be explained further below, the stator assembly <NUM> includes a stator split into stator segments that are each movable along the radial direction R relative to the rotor assembly <NUM> during certain operations.

It will be appreciated that the turbofan <NUM> depicted in <FIG> is provided by way of example only, and that in other exemplary embodiments, the turbofan <NUM> may have any other suitable configuration. For example, in other exemplary embodiments, the turbofan <NUM> may be configured as a turboprop engine, a turbojet engine, a differently configured turbofan engine, or any other suitable gas turbine engine. Additionally or alternatively, exemplary aspects of the present disclosure (such as the electric machine <NUM>) may be incorporated into or otherwise utilized with any other suitable type of turbomachine, such as an aeroderivative gas turbine engine, a nautical gas turbine engine, a power generation gas turbine engine, an internal combustion engine, etc., or further with any other machine having rotating components.

Referring now to <FIG>, a schematic, cross-sectional view of the electric machine <NUM> is provided. For this embodiment, the electric machine <NUM> is embedded within the turbofan <NUM> along the axial direction A aft of the fan <NUM> and forward of inlet guide vanes <NUM> positioned at the annular core inlet <NUM>. However, it will be appreciated that in other exemplary embodiments that the electric machine <NUM> can be positioned at other suitable locations within the turbofan <NUM>. Further, as shown, the electric machine <NUM> defines a centerline <NUM> extending along an axial direction (A). The electric machine <NUM> also defines a radial direction (R), and a rotor assembly <NUM> rotatable about the centerline <NUM>. For this embodiment, the centerline <NUM> of the electric machine is aligned with the longitudinal axis <NUM> of the turbofan <NUM>.

As noted above, the electric machine <NUM> includes rotor assembly <NUM> and stator assembly <NUM>. The rotor assembly <NUM> generally includes a rotor <NUM> and a rotor connection member <NUM>. The stator assembly <NUM> includes a stator <NUM> and a stator connection member <NUM>. The stator <NUM> is connected to and supported by the stator connection member <NUM>. The rotor <NUM> of the rotor assembly <NUM> and stator <NUM> of the stator assembly <NUM> together define an air gap <NUM> therebetween. Moreover, for this embodiment, the rotor <NUM> includes a plurality of magnets <NUM>, such as a plurality of permanent magnets, and the stator <NUM> includes a plurality of coils or windings <NUM>. As such, it will be appreciated, that the electric machine <NUM> may be referred to as a permanent magnet electric machine. However, in other exemplary embodiments, the electric machine <NUM> may be configured in any suitable manner. For example, the electric machine <NUM> may be configured as an electromagnetic electric machine, including a plurality of electromagnets and active circuitry, as an induction type electric machine, a switched reluctance type electric machine, a synchronous AC electric machine, an asynchronous electric machine, or having any other suitable configuration.

For the embodiment shown, the rotor assembly <NUM> is operatively coupled with the LP shaft <NUM>, and accordingly, the rotor assembly <NUM> is rotatable with the LP shaft <NUM>. More specifically, as depicted, the rotor connection member <NUM> extends between the LP shaft <NUM> and the rotor <NUM> for connecting the rotor <NUM> to the LP shaft <NUM>. For this embodiment, the rotor connection member <NUM> is connected to the LP shaft <NUM> through a splined connection. Particularly, the rotor connection member <NUM> includes a connection portion <NUM> having a plurality of teeth <NUM> arranged generally along the axial direction A, and similarly, the LP shaft <NUM> includes a connection portion <NUM> having a plurality of teeth <NUM> arranged generally along the axial direction A. The plurality of teeth <NUM> of the connection portion <NUM> of the rotor connection member <NUM> are configured to engage with the plurality of teeth <NUM> of the connection portion <NUM> of the LP shaft <NUM>, fixing the two components to one another along the circumferential direction C. Notably, however, such a configuration allows for relative movement of the rotor assembly <NUM> relative to the LP shaft <NUM> along the axial direction A.

It will be appreciated that in other embodiments that the rotor connection member <NUM> may be coupled to the LP shaft <NUM> in any other suitable manner allowing for relative movement along the axial direction A, while fixing the components along the circumferential direction C. For example, in other example embodiments, the rotor connection member <NUM> may be coupled to the LP shaft <NUM> using a plurality of linear bearings, linear slides, etc..

During certain operations of the turbofan <NUM>, the LP shaft <NUM> may rotate the rotor assembly <NUM> of the electric machine <NUM> relative to the stator assembly <NUM>, allowing the electric machine <NUM> to function in a generator mode. Accordingly, during such operations, the electric machine <NUM> can generate electrical power. For this embodiment, the electric machine <NUM> is electrically coupled with a power bus <NUM>. The power bus <NUM> can electrically couple or connect the electric machine <NUM> with various electrical sinks (accessory systems, electric/ hybrid-electric propulsion devices, etc.), electrical sources (other electric machines, electric energy storage units, etc.), or both. In such a manner, electrical power generated by the electric machine <NUM> can be provided to such electrical sinks and/or sources. During some operations, the electric machine <NUM> may function in a drive mode. Accordingly, during such operations, the electric machine <NUM> can drive the LP shaft <NUM> about the longitudinal centerline <NUM>.

Moreover, in some embodiments, the turbofan <NUM> can further include a cavity wall surrounding at least a portion of the electric machine <NUM>. In some embodiments, the cavity wall can substantially completely surround the electric machine <NUM>, extending from a location proximate a forward end of the electric machine <NUM> to a location aft of the electric machine <NUM>. The cavity wall may function as, e.g., a cooling air cavity wall, a sump for cooling fluid, a protective cover for the electric machine <NUM>, etc. For example, in certain embodiments, the engine may further include a second cavity wall (not shown) to form a buffer cavity surrounding the electric machine <NUM> and thermally protect the electric machine <NUM>.

Referring now to <FIG>, <FIG>, <FIG>, and <FIG>, the stator assembly <NUM> will now be further described. As shown best in <FIG> and <FIG>, the stator <NUM> is split or segmented into stator segments. The stator <NUM> is split into at least two stator segments. The stator <NUM> can be split into any suitable number of stator segments. In some embodiments, for example, the stator <NUM> can be split into a first segment and a second segment. In other embodiments, the stator <NUM> can be split into at least four stator segments. For instance, for this embodiment, the stator <NUM> is split into four stator segments, including a first stator segment 232A, a second stator segment 232B, a third stator segment 232C, and a fourth stator segment 232D. Only the first stator segment 232A is depicted in <FIG> and <FIG>. The four stator segments 232A, 232B, 232C, 232D can be sized evenly or as equally sized segments as shown best in <FIG> and <FIG>.

Each one of the stator segments 232A, 232B, 232C, 232D has an associated set of stator windings or coils. Particularly, as shown best in <FIG> and <FIG>, the first stator segment 232A has a first set of stator windings 236A associated therewith, the second stator segment 232B has a second set of stator windings 236B associated therewith, the third stator segment 232C has a third set of stator windings 236C associated therewith, and the fourth stator segment 232D has a fourth set of stator windings 236D associated therewith. Notably, the stator windings of each set 236A, 236B, 236C, 236D are wound only within their respective stator segments 232A, 232B, 232C, 232D. This allows the stator segments 232A, 232B, 232C, 232D to be separately movable along the radial direction R as will be explained below. The stator windings 236A, 236B, 236C, 236D can be wound only within their respective stator segments 232A, 232B, 232C, 232D through slots defined between adjacent teeth of the stator segments 232A, 232B, 232C, 232D as shown in <FIG> and <FIG>.

Moreover, for this embodiment, the first set of stator windings 236A wound only within the first stator segment 232A include one or more windings associated with a first phase, one or more second windings associated with a second phase, and one or more third windings associated with a third phase. Accordingly, the first set of stator windings 236A is a three-phase set of windings. The second, third, and fourth sets of stator windings 236B, 236C, 236D wound only within their respective stator segments 232B, 232C, 232D can each be similarly wound as the first set of stator windings 236A. Accordingly, in this example, each stator segment 232A, 232B, 232C, 232D includes a set of three-phase windings 236A, 236B, 236C, 236D wound only within their respective stator segments 232A, 232B, 232C, 232D. It will be appreciated that the inventive aspects of the present disclosure may apply to any multiphase winding arrangement having any suitable number of phases, such as six phases. For instance, each stator segment can have an associated set of six-phase windings instead of an associated set of three-phase windings.

In some embodiments, the stator windings of a set associated with one of the stator segments can be arranged in a tooth or concentrated configuration. In such configurations, the go-side of a given winding is wound through a slot and the return-side of the given winding is wound through an adjacent slot. Thus, in a tooth or concentrated winding configuration, the stator windings go and return within the same stator segment and in slots that are spaced from one another by only a single slot (i.e., they are adjacent slots). The stator windings 236A, 236B, 236C, 236D are shown wound within their respective stator segments 232A, 232B, 232C, 232D in a tooth or concentrated winding configuration in <FIG> and <FIG>. In other embodiments, the stator windings can be arranged in a distributed configuration. In a distributed configuration, the stator windings go and return within the same stator segment and in slots that are spaced from one another by more than one slot. It will be appreciated that the winding configurations disclosed herein are non-limiting examples and that sets of stator windings associated with their respective stator segments can be wound in other suitable configurations.

As shown best in <FIG>, each one of the stator segments 232A, 232B, 232C, 232D has at least one associated power converter 260A, 260B, 260C, 260D. Each of the power converters 260A, 260B, 260C, 260D are electrically coupled with the stator windings 236A, 236B, 236C, 236D of their respective stator segments 232A, 232B, 232C, 232D. As one example, the power converters 260A, 260B, 260C, 260D can each be operable to convert the electrical power generated by the electric machine <NUM> from Alternating Current (AC) into Direct Current (DC) and/or to convert incoming electrical power provided to the electric machine <NUM> from DC to AC.

As will be appreciated by comparing the position of the stator segments 232A, 232B, 232C, 232D in <FIG> with their respective positions in <FIG>, each one of the stator segments 232A, 232B, 232C, 232D is movable between a first position (shown in <FIG>) and a second position (shown in <FIG>). <FIG> and <FIG> show a different perspective of the first stator segment 232A movable between the first position (<FIG>) and the second position (<FIG>). Notably, the stator segments 232A, 232B, 232C, 232D are each movable between their respective first and second positions along the radial direction R. The stator segments 232A, 232B, 232C, 232D are each closer to the rotor assembly <NUM> when in their respective first positions than when in their respective second positions. In some instances, each of the stator segments 232A, 232B, 232C, 232D can be moved to an intermediate position between their respective first and second positions.

The stator segments 232A, 232B, 232C, 232D are each movable along the radial direction R relative to the rotor assembly <NUM> by actuators. As shown best in <FIG> and <FIG>, each stator segment has an actuator associated therewith. Particularly, the first stator segment 232A has a first actuator 250A associated therewith, the second stator segment 232B has a second actuator 250B associated therewith, the third stator segment 232C has a third actuator 250C associated therewith, and the fourth stator segment 232D has a fourth actuator 250D associated therewith. Each of the actuators 250A, 250B, 250C, 250D are operable to move their respective stator segments 232A, 232B, 232C, 232D along the radial direction R between their respective first and second positions or to an intermediate position therebetween.

The first actuator 250A is coupled to the first stator segment 232A for moving the first stator segment 232A relative to the rotor assembly <NUM> along the radial direction R, e.g., between the first position and the second position. For this embodiment, the first actuator 250A is a linear actuator. The first actuator 250A includes a base 252A and an extension portion 254A moveable relative to the base 252A along the radial direction R. The base 252A is coupled or attached to the stator connection member <NUM> as shown in <FIG> and <FIG>. The extension portion 254A is coupled or attached to the first stator segment 232A. In a similar manner, the second actuator 250B is coupled to the second stator segment 232B for moving the second stator segment 232B relative to the rotor assembly <NUM> along the radial direction R, e.g., between the first position and the second position. The second actuator 250B is also a linear actuator and includes a base 252B and an extension portion 254B moveable relative to the base 252B along the radial direction R. Although not shown, the base 252B is coupled or attached to a stator connection member at a circumferentially-spaced location from where the base 252A of the first actuator 250A is coupled or attached to the stator connection member <NUM> as shown in <FIG> and <FIG>. The extension portion 254B is coupled or attached to the second stator segment 232B.

Further, the third actuator 250C is coupled to the third stator segment 232C for moving the third stator segment 232C relative to the rotor assembly <NUM> along the radial direction R, e.g., between the first position and the second position. The third actuator 250C is a linear actuator and includes a base 252C and an extension portion 254C moveable relative to the base 252C along the radial direction R. The base 252C can be coupled or attached to a stator connection member at a circumferentially-spaced location from where the base 252A of the first actuator 250A is coupled or attached to the stator connection member <NUM> as shown in <FIG> and <FIG> and from where the base 252B of the second actuator 250B is coupled with its corresponding stator connection member. The extension portion 254C is coupled or attached to the third stator segment 232C. Similarly, like the other actuators, the fourth actuator 250D is coupled to the fourth stator segment 232D for moving the fourth stator segment 232D relative to the rotor assembly <NUM> along the radial direction R, e.g., between the first position and the second position. For this embodiment, the fourth actuator 250D is a linear actuator and includes a base 252D and an extension portion 254D moveable relative to the base 252D along the radial direction R. The base 252D is coupled or attached to a stator connection member at a circumferentially-spaced location from where the base 252A of the first actuator 250A is coupled or attached to the stator connection member <NUM> as shown in <FIG> and <FIG> and from where the base 252B of the second actuator 250B is coupled with its corresponding stator connection member and from where the base 252C of the third actuator 250C is coupled with its corresponding stator connection member. The extension portion 254D is coupled or attached to the fourth stator segment 232D.

The actuators 250A, 250B, 250C, 250D can be powered in any suitable manner. For instance, the actuators 250A, 250B, 250C, 250D can be hydraulically powered, pneumatically powered, electrically powered, thermally activated, magnetically activated, etc. Further, still, in other embodiments, the actuators 250A, 250B, 250C, 250D may not be a linear actuator and instead may be a scissor-actuator, a circular to linear actuator (such as a screw actuator), or any other actuator capable of creating a linear movement.

Referring still to <FIG>, <FIG>, <FIG>, and <FIG>, for the embodiment shown, when the stator segments 232A, 232B, 232C, 232D are positioned in their respective first positions as shown in <FIG> and <FIG>, they are each in an engaged position. When the stator segments 232A, 232B, 232C, 232D are positioned in their respective second positions as shown in <FIG> and <FIG>, they are each in a disengaged position. As used herein, the term "engaged position" refers to a relative positioning of the rotor <NUM> of the rotor assembly <NUM> to the stator <NUM> of the stator assembly <NUM> in which the electric machine <NUM> is capable of operating within a reasonable margin of error of the design efficiency for the electric machine <NUM>. For example, in the engaged position, the air gap <NUM> defined between the rotor <NUM> of the rotor assembly <NUM> and the stator <NUM> of the stator assembly <NUM> may be within a reasonable margin of an optimal design value, enabling a desired portion of magnetic flux from the magnets <NUM> of the rotor <NUM> to reach the stator windings 236A, 236B, 236C, 236D of the stator segments 232A, 232B, 232C, 232D. By contrast, as used herein, the term "disengaged position" refers to a relative positioning of the rotor <NUM> of the rotor assembly <NUM> to the stator <NUM> of the stator assembly <NUM> in which the electric machine <NUM> is not capable of operating with a reasonable efficiency (e.g., with an efficiency less than <NUM>% of a maximum efficiency).

When the stator segments 232A, 232B, 232C, 232D are positioned in their respective first or engaged positions as shown in <FIG> and <FIG>, a size of the air gap <NUM> (i.e., a distance <NUM> between a given stator segment and the rotor <NUM>, shown in <FIG> and <FIG>) may be a first value. When the stator segments 232A, 232B, 232C, 232D are positioned in their respective second or disengaged positions as shown in <FIG> and <FIG>, the size of the air gap <NUM> may be a second value. In some embodiments, the second value is at least two times larger than the first value, such as at least four times larger than the first value, such as at least five times larger than the first value, such as up to <NUM> times larger than the first value, such as up to <NUM> times larger than the first value, such as up to <NUM> times larger than the first value. In some embodiments, the actuators 250A, 250B, 250C, 250D can move their respective stator segments 232A, 232B, 232C, 232D along the radial direction R between the engaged position and the disengaged position or vice versa with the distance being greater than <NUM> inches and less than <NUM> inches, such as greater than <NUM> inch and less than <NUM> inches.

An electric machine <NUM> configured as provided herein may provide for an extra layer of safety in the event of a failure or fault of the electric machine <NUM>. More specifically, in the event of a short or other fault within the stator <NUM> of the stator assembly <NUM> (e.g., within one or more of the windings 236A, 236B, 236C, 236D), continued rotation of the rotor <NUM> of the rotor assembly <NUM> relative to the stator <NUM>, when the rotor assembly <NUM> is in the engaged position relative to the stator assembly <NUM>, may create excess heat, potentially damaging other components within the turbofan <NUM>. By utilizing the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D from their respective engaged positions to their respective disengaged positions, the turbofan <NUM> can continue to operate without risking additional damage thereto. Such functionality may be particularly useful when the turbofan <NUM> is, e.g., an aeronautical gas turbine engine producing thrust for an aircraft.

In such a manner, the turbofan <NUM> can include a control system for controlling the position of the stator segments 232A, 232B, 232C, 232D relative to the rotor assembly <NUM>. As shown best in <FIG> and <FIG>, the turbofan <NUM> and/or the electric machine <NUM> includes a controller <NUM>, and one or more controllable devices, such as the actuators 250A, 250B, 250C, 250D, and optionally one or more sensors <NUM> (only one shown in <FIG> and <FIG>). The controller <NUM> is communicatively coupled with the one or more sensors <NUM> and each of the actuators 250A, 250B, 250C, 250D, e.g., via one or more suitable wired and/or wireless communication links.

The controller <NUM> includes one or more memory devices and one or more processors. The one or more memory devices can store information accessible by the one or more processors, including computer-executable instructions that can be executed by the one or more processors. The instructions can be any set of instructions that, when executed by the one or more processors, cause the one or more processors to perform operations, such as the operations provided herein. The controller <NUM> can be configured in accordance with the computing system <NUM> of <FIG>. Although the controller <NUM> is depicted in <FIG> and <FIG> at a location proximate to the electric machine <NUM>, it will be appreciated that the controller <NUM> can be located at any suitable position within the turbofan <NUM>, such as under a cowling. The controller <NUM> can also be positioned at a remote location with respect to the turbofan <NUM>, e.g., within the fuselage of an aircraft to which the turbofan <NUM> is mounted. In some embodiments, the controller <NUM> can be a dedicated controller for controlling actuation of the stator segments 232A, 232B, 232C, 232D. In other embodiments, the controller <NUM> can be an Electronic Engine Controller (EEC) of a Full Authority Digital Engine Control (FADEC) system.

In some embodiments, the controller <NUM> is configured to receive data from the one or more sensors <NUM>. The data can indicate a fault within or associated with the electric machine <NUM>. For example, the one or more sensors <NUM> can be, e.g., one or more temperature sensors configured to sense a temperature of their respective stator segments 232A, 232B, 232C, 232D. If the data sensed by the one or more sensors <NUM> indicates that a temperature associated with one or more of the stator segments 232A, 232B, 232C, 232D is in excess of a certain threshold, such may be indicative of a fault within the electric machine <NUM>. Accordingly, the controller <NUM> can determine that a fault is associated with the electric machine <NUM> and can cause the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D from their respective first or engaged positions outward along radial direction R away from the rotor assembly <NUM> to their respective second or disengaged positions. Stated another way, the controller <NUM> can cause the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D from their respective first or engaged positions to their respective second or disengaged positions along the radial direction R in response to receiving the data indicating the fault within the electric machine <NUM>. In this way, in the event of a fault within or associated with the electric machine <NUM>, damage to the electric machine <NUM> and/or other components of the turbofan <NUM> can be prevented or mitigated.

Further, in some embodiments, the controller <NUM> is configured to receive subsequent data indicating that the fault within or associated with the electric machine <NUM> has been remedied or is no longer present and/or a command that indicates the electric machine <NUM> is to operate despite the fault condition. Accordingly, in such embodiments, the controller <NUM> can cause the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D from their respective second or disengaged positions inward along radial direction R toward the rotor assembly <NUM> to their respective first or engaged positions. The subsequent data can be received from the one or more sensors <NUM>, from an aircraft flight management system, a pilot, etc..

In addition to the above-noted functionality, it should be appreciated that the controller <NUM> can cause the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D along the radial direction R to one or more intermediate or partial power positions located between their respective first and second positions, or rather between their respective engaged and disengaged positions. In such a manner, the actuators 250A, 250B, 250C, 250D may be configured to move their respective stator segments 232A, 232B, 232C, 232D relative to the rotor assembly <NUM> in order to affect an efficiency of the electric machine <NUM>, to effectively control an amount of power extracted by the electric machine <NUM>.

Accordingly, in such embodiments, the controller <NUM> is configured to receive data indicating an electrical power demand. The electrical power demand can indicate the electrical power demanded by one or more electrical loads electrically coupled with the electric machine <NUM>. The electrical power demand can be a demand requesting an increase in electrical power, a decrease in electrical power, or in some instances, a demand requesting the same electrical power as previously requested. In response to the electrical power demand, the controller <NUM> can cause the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D away from or toward the rotor assembly <NUM> along the radial direction R.

For instance, on one hand, if the electrical power demand is a demand requesting an increase in electrical power, the controller <NUM> can cause the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D toward the rotor assembly <NUM> along the radial direction R. The radial distance the stator segments 232A, 232B, 232C, 232D are moved toward the rotor assembly <NUM> along the radial direction R can be in accordance with a schedule that correlates the demanded electrical power with respective positions of the stator segments 232A, 232B, 232C, 232D and/or their associated actuators 250A, 250B, 250C, 250D, for example.

On the other hand, if the electrical power demand is a demand requesting a decrease in electrical power, the controller <NUM> can cause the actuators 250A, 250B, 250C, 250D to move their respective stator segments 232A, 232B, 232C, 232D away from the rotor assembly <NUM> along the radial direction R. The radial distance the stator segments 232A, 232B, 232C, 232D are moved away from the rotor assembly <NUM> along the radial direction R can be in accordance with the schedule that correlates the demanded electrical power with respective positions of the stator segments 232A, 232B, 232C, 232D and/or their associated actuators 250A, 250B, 250C, 250D, for example. If the electrical power demand is a demand requesting neither a decrease nor increase in electrical power, the controller <NUM> can cause the actuators 250A, 250B, 250C, 250D to maintain the positions of their respective stator segments 232A, 232B, 232C, 232D along the radial direction R.

Accordingly, advantageously, the controller <NUM> can control the radial position of each of the stator segments 232A, 232B, 232C, 232D relative to the rotor assembly <NUM> to control an amount of power extraction from the electric machine <NUM>. In addition, the electrical power output by the electric machine <NUM> can be decoupled from the rotational speed of the rotating component to which the rotor assembly <NUM> is coupled, which is the LP shaft <NUM> in this example.

It will further be appreciated that the exemplary electric machine <NUM> and turbofan <NUM> depicted in <FIG> is provided by way of example only. In other exemplary embodiments, the electric machine <NUM> and turbofan <NUM> may have any other suitable configuration. For example, in other exemplary embodiments, the electric machine <NUM> may be positioned in any other suitable location within the gas turbine engine. For example, a gas turbine engine can include an electric machine coupled to an LP shaft, an HP shaft, or both within the compressor section at a location forward of the HP compressor. Additionally or alternatively, the gas turbine engine can include an electric machine coupled to the LP shaft, the HP shaft, or both within the compressor section at a location inward of the HP compressor. Additionally or alternatively, the gas turbine engine can include an electric machine coupled with the LP shaft within the turbine section, e.g., at a location forward of the LP turbine. Other suitable locations are possible.

Referring now to <FIG>, a flow diagram for a method (<NUM>) of operating a turbomachine in accordance with an exemplary aspect of the present disclosure is depicted. The method (<NUM>) utilizes the electric machine <NUM> provided herein. Accordingly, in certain exemplary aspects the electric machine includes a stator assembly and a rotor assembly, and defines a centerline. Furthermore, the control system described herein can be used to implement all or certain aspects of the method (<NUM>). The turbomachine can be any suitable turbomachine, such as an aviation gas turbine engine.

At (<NUM>), the method (<NUM>) includes operating an electric machine to convert electrical power to rotational power or to convert rotational power to electrical power. The electric machine has a stator assembly and a rotor assembly rotatable with a rotating component of a turbomachine. Notably, the stator assembly has a stator split into stator segments. In some implementations, for instance, the stator assembly can be split or segmented into at least two segments. In some implementations, the stator assembly can be split or segmented into at least four segments. Moreover, in some implementations, the turbomachine is an aviation gas turbine engine. In such implementations, the rotating component can be one of a low pressure shaft and a high pressure shaft of the aviation gas turbine engine. Further, in such implementations, operating the electric machine to convert rotational power to electrical power can occur during a flight operation, such as a takeoff operation, a climb operation, a cruise operation, and/or a descent operation, or alternatively, during a ground operation.

At (<NUM>), the method (<NUM>) includes receiving data indicating a fault condition within the electric machine. Receiving the data indicating the fault condition within the electric machine at (<NUM>) can include receiving sensor data indicative of a short within one or more stator windings or coils associated with one of the stator segments. For example, receiving information indicative of the fault condition within the electric machine at (<NUM>) can include receiving data indicative of a temperature of one or more aspects of the stator assembly.

At (<NUM>), the method (<NUM>) includes moving each one of the stator segments away from the rotor assembly along a radial direction defined by the turbomachine in response to receiving the data indicating the fault condition within the electric machine. For instance, the stator segments can be moved outward along the radial direction from their respective first or engaged positions to respective second or disengaged positions, wherein the stator segments are each positioned closer to the rotor assembly when in their respective first positions than when in their respective second positions. This can increase the air gap or distance between the stator segments and the rotor assembly.

In some implementations, the stator segments are movable between their respective first and second positions simultaneously. In some implementations, the stator segments are each separately movable between their respective first and second positions, e.g., by associated actuators. In some implementations, the stator segments are each moved away from the rotor assembly along the radial direction a distance that is greater than <NUM> inches and less than <NUM> inches.

Further, in some implementations, the stator is split or segmented into a first stator segment and a second stator segment. In such implementations, moving each one of the stator segments away from the rotor assembly along the radial direction includes moving the first stator segment and the second stator segment opposite one another along the radial direction. In other implementations, the stator is split or segmented into a first stator segment, a second stator segment, a third stator segment, and a fourth stator segment, e.g., as shown in <FIG> and <FIG>. In such implementations, moving each one of the stator segments away from the rotor assembly along the radial direction includes moving the first stator segment and the third stator segment opposite one another along the radial direction and the second stator segment and the fourth stator segment opposite one another along the radial direction. In this manner, each of the stator segments is moved away from the rotor assembly along the radial direction opposite of an opposing segment.

Additionally, it should be appreciated that the method (<NUM>) may be configured to additionally move the stator segments relative to the rotor assembly along the radial direction to respective intermediate positions between their respective first and second positions, or rather between their respective engaged and disengaged positions. In such manner, the method (<NUM>) can also be implemented to affect the efficiency of the electric machine so as to effectively control an amount of power extracted by the electric machine (or provided to an engine including the electric machine).

In such manner, a controller associated with the electric machine may further be configured to move the stator segments relative to the rotor assembly along the radial direction to control an amount of power extraction from the electric machine or power provided to an engine including the electric machine. For example, the controller associated with the electric machine may determine that additional power extraction is required or desired, and in response may move the stator segments to reduce the air gap and increase a power extraction. Additionally, the controller associated with the electric machine may determine that a lesser amount of power extraction is required or desired, and in response may move the stator segments to increase the air gap and reduce a power extraction. Additionally, the controller associated with the electric machine may determine that additional power is required or desired to be provided to an engine including the electric machine, and in response may move the stator segments to reduce the air gap and increase a power provided to the engine. Additionally, the controller associated with the electric machine may determine that a lesser amount power is required or desired to be provided to the engine including the electric machine, and in response may move the stator segments to increase the air gap and reduce a power provided to the engine.

<FIG> provides a block diagram of the computing system <NUM> in accordance with exemplary aspects of the present disclosure. The computing system <NUM> is one example of a suitable computing system for implementing certain aspects of the present disclosure.

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

The one or more memory device(s) <NUM> can store information accessible by the one or more processor(s) <NUM>, including computer-readable instructions <NUM> that can be executed by the one or more processor(s) <NUM>. The instructions <NUM> can be any set of instructions that, when executed by the one or more processor(s) <NUM>, cause the one or more processor(s) <NUM> to perform operations. The instructions <NUM> can be software written in any suitable programming language or can be implemented in hardware. The instructions <NUM> can be any of the computer-readable instructions noted herein.

The memory device(s) <NUM> can further store data <NUM> that can be accessed by the processor(s) <NUM>. For example, the data <NUM> can include received data from the one or more sensors <NUM> (<FIG> and <FIG>). Further, the data <NUM> can include one or more table(s), function(s), algorithm(s), model(s), equation(s), etc. according to example embodiments of the present disclosure.

The one or more computing device(s) <NUM> can also include a communication interface <NUM> used to communicate, for example, with other systems or devices, e.g., the actuators 250A, 250B, 250C, 250D. The communication interface <NUM> can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, or other suitable components.

It will be appreciated that the inherent flexibility of computer-based systems allows for a great variety of possible configurations, combinations, and divisions of tasks and functionality between and among components.

Claim 1:
An electric machine (<NUM>) defining an axial direction (A), a radial direction (R), and a centerline (<NUM>) extending along the axial direction (A), the electric machine comprising:
a rotor assembly (<NUM>) rotatable about the centerline (<NUM>);
a stator assembly (<NUM>) having a stator (<NUM>) split into stator segments (232A, 232B, 232C, 232D), each one of the stator segments being movable between a first position and a second position along the radial direction defined by the electric machine, the stator segments (232A, 232B, 232C, 232D) each being radially (R) closer to the rotor assembly when in the first position than when in the second position;
wherein each stator segment (232A, 232B, 232C, 232D) has an actuator (250A, 250B, 250C, 250D) associated therewith, each of the actuators being operable to move their respective one of the stator segments between their respective first and second positions; and
a controller (<NUM>) associated with the electric machine and operatively coupled with the actuators (250A, 250B, 250C, 250D) and configured to cause the actuators to move their respective stator segments away from the rotor assembly (<NUM>) from their respective first positions to their respective second positions in response to receiving data indicating a fault with the electric machine.