Locking assembly for a propeller rotor of an aircraft, a rotor assembly for the aircraft, and a method

A locking assembly for a propeller rotor includes an electric machine having a first mode to energize the electric machine to produce torque and a second mode to deenergize the electric machine to stop production of the torque. A magnetic assembly includes a first component coupled to a first wall via a pivot point, and a second component attached to a second wall. The first component and the second component align proximal to each other when the first component is in a locked position such that the first and second components create a magnetic attraction therebetween to lock the first wall in a stationary position when the electric machine is in the second mode. The first component moves away from the second component to an unlocked position due to rotation of the first wall when the electric machine is in the first mode.

BACKGROUND

A vertical take-off and landing (VTOL) aircraft is a type of aircraft that can take off, hover, and land vertically. A VTOL aircraft generally includes one or more rotors that support respective propeller(s) that produce vertical lift by rotating the propeller(s). Some VTOL aircraft also have fixed-wings that generate lift when the aircraft is propelled forward by one or more propeller(s), jet engine(s), etc. When the fixed-wing aircraft transverses from vertical flight to horizontal or wing-borne flight, the rotors that produce vertical lift are turned off to stop rotation of the respective propeller(s). However, when the rotors that produced vertical lift are shut off, the propellers of those rotors are free to spin due to airflow across those propellers during wing-borne flight. That is, the rotors that are shut off may free-wheel which allows the corresponding propellers to free-wheel, and this free-wheeling can produce drag and hinder efficiency of wing-borne flight.

SUMMARY

Therefore, it is desirable to develop a locking assembly, a rotor assembly, and associated method, that locks one or more rotors in place to prevent free-wheel of the rotors when the rotors are stationary during wing-borne flight.

The present disclosure provides for a locking assembly for a propeller rotor of an aircraft. The locking assembly includes an electric machine having a first mode to energize the electric machine to produce torque and a second mode to deenergize the electric machine to stop production of the torque. The electric machine includes a first wall rotatable about a longitudinal axis when the electric machine is in the first mode. The first wall becomes stationary relative to the longitudinal axis when the electric machine is in the second mode. The electric machine includes a second wall spaced apart from the first wall and the second wall is stationary relative to the first wall regardless of the electric machine being in the first mode or the second mode. The locking assembly includes a magnetic assembly, and the magnetic assembly includes a first component coupled to the first wall via a pivot point. The magnetic assembly also includes a second component attached to the second wall. The first component is movable relative to the pivot point to a locked position and an unlocked position. The first component and the second component align proximal to each other when the first component is in the locked position such that the first component and the second component create a magnetic attraction therebetween to lock the first wall in a stationary position when the electric machine is in the second mode. The first component moves away from the second component to the unlocked position due to rotation of the first wall when the electric machine is in the first mode.

The present disclosure also provides for a rotor assembly for an aircraft. The rotor assembly includes a propeller rotor selectively rotatable about a longitudinal axis, and includes a locking assembly coupled to the propeller rotor. The locking assembly is configured to selectively lock the propeller rotor in a stationary position. The locking assembly includes an electric machine coupled to the propeller rotor. The electric machine has a first mode to energize the electric machine to produce torque to drive rotation of the propeller rotor and a second mode to deenergize the electric machine to stop production of the torque which causes rotation of the propeller rotor to stop. The electric machine includes a first wall coupled to the propeller rotor such that the first wall and the propeller rotor are rotatable together about the longitudinal axis when the electric machine is in the first mode. The first wall and the propeller rotor become stationary relative to the longitudinal axis when the electric machine is in the second mode. The electric machine includes a second wall spaced apart from the first wall and the second wall is stationary relative to the first wall regardless of the electric machine being in the first mode or the second mode. The locking assembly also includes a magnetic assembly, and the magnetic assembly includes a first component coupled to the first wall via a pivot point. The magnetic assembly also includes a second component attached to the second wall. The first component is movable relative to the pivot point to a locked position and an unlocked position. The first component and the second component align proximal to each other when the first component is in the locked position such that the first component and the second component create a magnetic attraction therebetween to lock the first wall and the propeller rotor in the stationary position when the electric machine is in the second mode. The first component moves away from the second component to the unlocked position due to rotation of the first wall when the electric machine is in the first mode.

The present disclosure further provides for a method of controlling a propeller rotor of an aircraft. An electric machine is signaled, via a controller, to operate in a first mode to produce torque to drive rotation of the propeller rotor. The electric machine includes a first wall coupled to the propeller rotor such that the first wall and the propeller rotor are rotatable together about a longitudinal axis when the electric machine is in the first mode. The electric machine is signaled, via the controller, to operate in a second mode to deenergize the electric machine to stop production of the torque which causes rotation of the propeller rotor to stop. The first wall and the propeller rotor become stationary relative to the longitudinal axis when the electric machine is in the second mode. The electric machine includes a second wall spaced apart from the first wall and the second wall is stationary relative to the first wall regardless of the electric machine being in the first mode or the second mode. A locking assembly is operated to selectively lock the propeller rotor in a stationary position such that a first component of a magnetic assembly and a second component of the magnetic assembly align proximal to each other when the first component is in a locked position in which the first component and the second component create a magnetic attraction therebetween to lock the first wall and the propeller rotor in the stationary position when the electric machine is in the second mode. The first component moves away from the second component to an unlocked position due to rotation of the first wall when the electric machine is in the first mode. The first component is coupled to the first wall via a pivot point and movable relative to the pivot point to the locked position and the unlocked position. The second component is attached to the second wall.

The detailed description and the drawings or FIGS. are supportive and descriptive of the disclosure, but the claim scope of the disclosure is defined solely by the claims. While some of the best modes and other configurations for carrying out the claims have been described in detail, various alternative designs and configurations exist for practicing the disclosure defined in the appended claims.

The present disclosure may be extended to modifications and alternative forms, with representative configurations shown by way of example in the drawings and described in detail below. Inventive aspects of the disclosure are not limited to the disclosed configurations. Rather, the present disclosure is intended to cover modifications, equivalents, combinations, and alternatives falling within the scope of the disclosure as defined by the appended claims.

DETAILED DESCRIPTION

Those having ordinary skill in the art will recognize that all directional references (e.g., above, below, upward, up, downward, down, top, bottom, left, right, vertical, horizontal, etc.) are used descriptively for the FIGS. to aid the reader's understanding, and do not represent limitations (for example, to the position, orientation, or use, etc.) on the scope of the disclosure, as defined by the appended claims. Moreover, terms such as “first,” “second,” “third,” and so on, may be used to describe separate components. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Furthermore, the term “substantially” can refer to a slight imprecision or slight variance of a condition, quantity, value, or dimension, etc., some of which that are within manufacturing variance or tolerance ranges.

As used herein, an element or step recited in the singular and preceded by the word “a” or “an” should be understood as not necessarily excluding the plural of the elements or steps. Further, any reference to “one configuration” is not intended to be interpreted as excluding the existence of additional configurations that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, configurations “comprising” or “having” an element or a plurality of elements having a particular property may include additional elements not having that property. The phrase “at least one of” as used herein should be construed to include the non-exclusive logical “or”, i.e., A and/or B and so on depending on the number of components.

Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, an aircraft10is generally shown inFIGS.1and2.

The aircraft10may be a manned aircraft10that is flown by one or more pilots therein, or may be an unmanned aircraft10that is flown without a pilot therein (e.g., a drone). The structure of aircraft10as shown inFIGS.1and2is one non-limiting example, and it is to be appreciated that the aircraft10may be configured differently than shown and still utilize the features described herein. In the example ofFIGS.1and2, the aircraft10may include a fuselage12and a plurality of wings14extending from opposite sides of fuselage12, which assist in horizontal or wing-borne flight. The aircraft10may include a tail16having one or more tail-wings18that extend from the fuselage12and/or the tail16.

Continuing withFIGS.1and2, the aircraft10may also include a main propulsor20that rotates a main propeller22to provide thrust for wing-borne flight. The main propeller22may be in any suitable location, and in the example ofFIGS.1and2the main propeller22is coupled to the tail16. It is to be appreciated that the main propulsor20may be any suitable type of propulsor to operate the main propeller22and/or to generate thrust, such as jet engines, electric machines, electric motors, etc. In addition, more than one main propulsor20may be used and/or more than one main propeller22may be used.

Again, continuing withFIGS.1and2, the aircraft10may further include a plurality of auxiliary propulsors24and a plurality of auxiliary propellers26coupled to the respective auxiliary propulsors24. That is, one of the auxiliary propellers26is operated by one of the auxiliary propulsors24, and so on depending on the number of auxiliary propellers26being utilized. Therefore, operation of the auxiliary propulsors24rotates the respective auxiliary propellers26to provide thrust for take-off and landing. The auxiliary propellers26may be in any suitable location, and in the example ofFIGS.1and2, some of the auxiliary propellers26are coupled to one of the wings14and other ones of the auxiliary propellers26are coupled to the other one of the wings14. It is to be appreciated that the auxiliary propulsors24may be any suitable type of propulsor to operate the auxiliary propellers26, such as jet engines, electric machines, electric motors, etc. In addition, any suitable number of auxiliary propulsors24and the auxiliary propellers26may be used.

Generally, the aircraft10may take-off from a location, cruise, and land at a desired location. For example, the aircraft10may be a vertical take-off and landing (VTOL) type of vehicle, and in certain configurations, the VTOL type of the aircraft10is an electric vehicle, i.e., includes electric powered motor and/or electrical batteries. It is to be appreciated that the VTOL type of the aircraft10may be a fuel powered vehicle or any other suitable powered VTOL vehicle. In the configuration of the VTOL type of vehicle, the aircraft10may land and take-off vertically without relying on a runway, and the VTOL type of vehicle may hover vertically.

The aircraft10may move vertically relative to the ground when taking-off and landing, which will be referred to as a hover phase. Referring toFIG.1, which is an illustration of the hover phase, the main propeller22may be stationary when the aircraft10is in the hover phase, and the auxiliary propellers26operate to provide thrust for take-off and landing when the aircraft10is in the hover phase. That is, the auxiliary propellers26are operated to take-off and land the aircraft10and the main propeller22is not operated in this phase, i.e., in the hover phase.

The aircraft10may move horizontally when the aircraft10is cruising or in wing-born flight, which will be referred to as a cruise phase. Generally, the cruise phase occurs after the hover phase when the aircraft10has taken off. It is to be appreciated that when the aircraft10is going to land after the cruise phase, the aircraft10will return to the hover phase and operate as discussed above.

Referring toFIG.2, which is an illustration of the cruise phase, the main propulsor20operates to provide thrust to rotate the main propeller22for wing-borne flight when the aircraft10is in the cruise phase, and the auxiliary propellers26are not operated in this phase, i.e., in the cruise phase. That is, the main propeller22is operated to cruise the aircraft10and the auxiliary propellers26are off in this phase, i.e., the cruise phase. The present disclosure provides a way to lock the auxiliary propellers26in a stationary position when the aircraft10is in the cruise phase, which reduces drag because the auxiliary propellers26will not be able to free-wheel.

The aircraft10may take-off and land on a runway, a landing pad, or any suitable ground. Therefore, the aircraft10may include a landing gear assembly indirectly or directly coupled to the fuselage12. Optionally, the landing gear assembly may be movable relative to the fuselage12between a retracted position and an extended position. During landing and take-off, the landing gear assembly is in the extended position to facilitate movement of the aircraft10on the ground and/or prevent the fuselage12from directly contacting the ground. When the aircraft10is in the air, if the landing gear is retractable, the landing gear assembly may move to the retracted position to minimize drag.

The aircraft10may be electrically powered and/or fuel powered, or powered by any other suitable fuels, components, energy storage devices, optionally including batteries, etc. Therefore, the main propulsor20and the auxiliary propulsors24of the aircraft10may be electrically powered and/or fuel powered, or powered by any other suitable fuels, components, energy storage devices, optionally including batteries, etc.

As non-limiting examples, the auxiliary propulsors24may be an electric machine24, such as a rotating or rotary-type electric machine24, referred to hereinafter as the electric machine24for simplicity. The below discussion applies to any number of auxiliary propulsors24, and thus, any number of the electric machines. The below discussion generally refers to one electric machine24, but it is to be appreciated that each of the electric machines24may include the features discussed below.

Referring toFIGS.3and4, the electric machine24may include a stator28and a rotor30that is rotatable relative to the stator28when the electric machine24is operating. The stator28may include windings, or electromagnets that each includes a coiled conductor, that is configured to generate a magnetic field when electric current is passed through the windings or the coiled conductor The magnetic field causes the rotor30to rotate during operation of the electric machine24. Therefore, each of the electric machines24include a stator28and a rotor30. The auxiliary propeller26, the stator28, and the rotor30are illustrated inFIGS.3and4, but these features are also applicableFIGS.5-8.

Referring toFIGS.3and4, the electric machine24may include a housing32having an end cap34. Generally, the housing32of the electric machine24is fixed to a component of the aircraft10such that the housing32remains in a fixed position. That is, the housing32is stationary. Therefore, the end cap34is also stationary. In addition, the stator28is disposed inside of the housing32, and optionally, one or more portions of the rotor30may be disposed inside of the housing32. Each of the electric machines24may include the housing32and the end cap34.

Again, referring toFIGS.3and4, the electric machine24may include a fan blade structure36configured to dissipate heat inside of the electric machine24. In addition, the electric machine24includes a first wall38rotatable about a longitudinal axis40. Generally, the first wall38is attached to the fan blade structure36. Therefore, the first wall38and the fan blade structure36are rotatable concurrently with each other. The fan blade structure36may include any suitable number of blades42, and the blades42may be spaced from each other. Furthermore, generally, the fan blade structure36and the first wall38are disposed inside of the housing32of the electric machine24.

In addition, generally, the first wall38surrounds the fan blade structure36. For example, the first wall38may surround the fan blade structure36relative to a distal end44A of the fan blade structure36. As another example, the first wall38may surround the fan blade structure36relative to a proximal end46A of the fan blade structure36. As yet another example, the first wall38may include an inner wall portion48and an outer wall portion50spaced apart from each other to define an opening52therebetween. The fan blade structure36is disposed between the inner wall portion48and the outer wall portion50, and specifically, the fan blade structure36is disposed in the opening52. More specifically, the blades42of the fan structure are disposed in the opening52.

In certain configurations, the first wall38may surround both the distal end44A and the proximal end46A of the fan blade structure36. For example, the distal end44A of the fan blade structure36is attached to the outer wall portion50, and the proximal end46A of the fan blade structure36is attached to the inner wall portion48. Therefore, in this configuration, the inner wall portion48, the outer wall portion50, and the fan blade structure36are rotatable concurrently with each other about the longitudinal axis40. Also, it is to be appreciated that the inner wall portion48, the outer wall portion50, and the blades42may be attached to each other or formed as one unitary unit, and thus, be referred to as the fan blade structure36.

Continuing withFIGS.3and4, the inner wall portion48and the outer wall portion50of the first wall38are spaced away from the longitudinal axis40. More specifically, the inner wall portion48and the outer wall portion50each surround the longitudinal axis40such that the longitudinal axis40is disposed inside of the inner wall portion48and the outer wall portion50. The inner wall portion48is disposed closer to the longitudinal axis40than the outer wall portion50is to the longitudinal axis40. That is, for example, the inner wall portion48is disposed radially closer to the longitudinal axis40than the outer wall portion50is to the longitudinal axis40, such that the inner wall portion48is disposed inside of the outer wall portion50.

Furthermore, the inner wall portion48may have a first length L1that is substantially parallel to the longitudinal axis40, and the outer wall portion50may have a second length L2that is substantially parallel to the longitudinal axis40. In certain configurations, the first length L1is greater than the second length L2. Therefore, the outer wall portion50provides a space54between the housing32and the outer wall portion50that is substantially parallel to the longitudinal axis40.

Continuing withFIGS.3and4, the first wall38may include an inner surface56that faces inwardly toward the longitudinal axis40and an outer surface58that opposes the inner surface56and faces outwardly away from the longitudinal axis40. Each of the inner wall portion48and the outer wall portion50includes a respective inner surface56and a respective outer surface58of the first wall38. Therefore, the inner surface56of the first wall38of the inner wall portion48is disposed closer to the longitudinal axis40than the inner surface56of the first wall38of the outer wall portion50relative to the longitudinal axis40. Similarly, the outer surface58of the first wall38of the inner wall portion48is disposed closer to the longitudinal axis40than the outer surface58of the first wall38of the outer wall portion50relative to the longitudinal axis40. In certain configurations, the blades42of the fan blade structure36is attached to the outer surface58of the inner wall portion48and attached to the inner surface56of the outer wall portion50.

Continuing withFIGS.3and4, one of the auxiliary propellers26is attached to the rotor30of one of the electric machines24, and the rotor30of that electric machine24is attached to the fan blade structure36via the first wall38. Therefore, one rotor30is attached to one auxiliary propeller26, and so on depending on the number of auxiliary propellers26being used. When the electric machine24is energized to rotate the rotor30, the rotor30causes one of the auxiliary propellers26to correspondingly rotate. More specifically, when the rotor30rotates due to being energized, the rotor30, the auxiliary propeller26, the fan blade structure36, and the first wall38concurrently rotate. For the discussion below, the rotor30may be referred to as a propeller rotor30.

The electric machine24may be controlled via a controller60. That is, the controller60signals the electric machine24to operate or to turn-off depending on the desired operation. Specifically, the controller60signals the electric machine24to switch between modes. For example, the electric machine24may have a first mode to energize the electric machine24to produce torque, and a second mode to deenergize the electric machine24to stop production of the torque. Generally, the electric machine24is coupled to the propeller rotor30and the first mode energizes the electric machine24to produce torque to drive rotation of the propeller rotor30, and the second mode deenergizes the electric machine24to stop production of the torque which causes rotation of the propeller rotor30to stop. Simply stated, in the first mode, the propeller rotor30rotates which causes rotation of the auxiliary propeller26, and in the second mode, the propeller rotor30slows down to a stop which causes the auxiliary propeller26to slow down to a stop. While the electric machine24is in the first mode, the torque produced via the electric machine24may be varied to increase thrust or decrease thrust depending on the desired operation of the aircraft10.

Therefore, the controller60may be in electrical communication with one or more of the electric machines24. Optionally, a plurality of controllers60may be used, with one controller60in electrical communication with a respective one of the electric machines24. In addition, optionally, each of the controller60may communicate with each other and/or to a main controller60. Instructions may be stored in a memory M of the controller60and automatically executed via a processor P of the controller60to provide the respective control functionality.

The controller60is configured to execute the instructions from the memory, via the processor. For example, the controller60may be a host machine or distributed system, e.g., a computer such as a digital computer or microcomputer, and, as the memory M, tangible, non-transitory computer-readable memory such as read-only memory (ROM) or flash memory. The controller60may also have random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a high-speed clock, analog-to-digital (A/D) and/or digital-to-analog (D/A) circuitry, and any required input/output circuitry and associated devices, as well as any required signal conditioning and/or signal buffering circuitry. Therefore, the controller60may include all software, hardware, memory M, algorithms, connections, sensors, etc., necessary to control, for example, the electric machines24. As such, a control method operative to control the electric machines24may be embodied as software or firmware associated with the controller60. It is to be appreciated that the controller60may also include any device capable of analyzing data from various sensors, comparing data, making the necessary decisions required to control and/or monitor the electric machines24.

Referring toFIGS.3and4, the electric machine24includes a second wall62spaced apart from the first wall38. The second wall62is stationary relative to the first wall38regardless of the electric machine24being in the first mode or the second mode. In certain configurations, the second wall62is a stationary component of the electric machine24. Therefore, in certain configurations, the second wall62may be further defined as part of the housing32of the electric machine24, the end cap34of the housing32of the electric machine24, or a component of the stator28, etc. The second wall62will be discussed further below.

It is desirable to prevent rotation of the auxiliary propellers26when the aircraft10is in the cruise phase, which will assist in reducing or minimizing drag. Therefore, as will be discussed in detail below,FIGS.3-8illustrate features of a locking assembly64that may be used to lock the auxiliary propeller26in a desired position when the aircraft10is in the cruise phase to reduce or minimize drag. Specifically, the locking assembly64may be used to lock the propeller rotor30in a desired position, which correspondingly locks the auxiliary propeller26coupled to that propeller rotor30in the desired position. Therefore, the locking assembly64prevents the propeller rotor30and the corresponding auxiliary propeller26from free-wheeling when the aircraft10is cruising in wing-borne flight. It is to be appreciated that the locking assembly64may be used on any desired number of propeller rotors30/auxiliary propellers26, and therefore, a plurality of locking assemblies64may be utilized depending on the number of propeller rotors30/auxiliary propellers26being utilized. As such, the features of the locking assembly64may be incorporated into any desired number of auxiliary propulsors24, even though the below discussion focuses on one auxiliary propulsor24/electric machine24.

Turning toFIGS.3-8, the locking assembly64also includes a magnetic assembly66that is configured to prevent rotation of the auxiliary propeller26when the aircraft10is in the cruise phase. The arrangement of the magnetic assembly66with the electric machine24provides a way to lock the auxiliary propeller26in a desired position, via the propeller rotor30, when the aircraft10is in the cruise phase. Therefore, the locking assembly64may include the electric machine24, and thus, includes the first wall38of the electric machine24being rotatable about the longitudinal axis40when the electric machine24is in the first mode. The first wall38of the electric machine24is coupled to the propeller rotor30such that the first wall38and the propeller rotor30are rotatable together about the longitudinal axis40when the electric machine24is in the first mode.

The first wall38becomes stationary relative to the longitudinal axis40when the electric machine24is in the second mode. That is, the first wall38and the propeller rotor30become stationary relative to the longitudinal axis40when the electric machine24is in the second mode. The arrangement of the magnetic assembly66with the electric machine24allows the auxiliary propeller26to be locked in the desired position.

Generally, it is desirable to lock the auxiliary propellers26in a complementary orientation relative to the direction of the airflow as the aircraft10is cruising to minimize drag. For example, as shown inFIG.2, the auxiliary propellers26may be locked in a fore-aft position. When the aircraft10is in the cruise phase, generally moving forward, an airflow A is directed into the aircraft10and across the wings14as represented by arrows A inFIG.2. Therefore, it is desirable to orientate the auxiliary propeller26into the airflow A, such as shown inFIG.2, in the fore-aft position. That is, the auxiliary propeller26is orientated generally lateral relative to the airflow A, generally in the same direction as the airflow A, or in some configurations substantially parallel to the airflow A.

As mentioned above, the magnetic assembly66is configured to prevent rotation of the auxiliary propeller26when the aircraft10is in the cruise phase. Therefore, each of the auxiliary propellers26may be equipped with the magnetic assembly66. The magnetic assembly66uses magnetic attraction to lock the auxiliary propeller26in the fore-aft position, and the details are discussed below. That is, the magnetic assembly66is designed to create a magnetic interaction that locks the auxiliary propeller26in the fore-aft position.

Turning toFIGS.3-8, the magnetic assembly66includes a first component68coupled to the first wall38via a pivot point70. Therefore, the first component68is supported by the first wall38. As discussed above, the first wall38is attached to the propeller rotor30, and therefore, movement of the propeller rotor30causes movement of the first wall38. The first component68is also movable in response to movement of the propeller rotor30. That is, the first component68is rotatable about the longitudinal axis40concurrently with the propeller rotor30. It is to be appreciated that the first component68may be in any suitable location along the first wall38, and the figures provide some non-limiting examples.

In addition, the first component68is movable relative to the pivot point70to a locked position and an unlocked position. Therefore, the pivot point70may define a pivot axis72. It is to be appreciated that directional arrows X inFIGS.3-8are illustrative of the general movement of the first component68about the pivot axis72between the locked position and the unlocked position. The movement of the first component68relative to the pivot point70(i.e., pivot axis72) is independent of the rotation of the first component68relative to the longitudinal axis40. Therefore, the first component68is movable relative to multiple axes40,72, but the first wall38is rotatable relative to the longitudinal axis40, not the pivot axis72.

As the speed of the propeller rotor30increases about the longitudinal axis40, the first component68rotates at the same speed with the propeller rotor30about the longitudinal axis40, and the forces acting on the first component68due to this rotation, causes the first component68to also rotate independently of the first wall38relative to the pivot axis72to the unlocked position. As the speed of the propeller rotor30decreases about the longitudinal axis40, the first component68again rotates at the same speed as the propeller rotor30about the longitudinal axis40, and the forces acting on the first component68due to this rotation causes the first component68to also rotate independently of the first wall38relative to the pivot axis72to the locked position.

For the locked position to be achieved, a first speed threshold is reached, and for the unlocked position to be achieved, a second speed threshold is reached. The first speed threshold and the second speed threshold may be any suitable speed value based on engineering requirements, government requirements, aircraft parameters, etc. As one non-limiting example, the first speed threshold may be greater than 100 revolutions per minute (rpm). As another non-limiting example, the first speed threshold may be greater than 200 rpm. As yet another non-limiting example, the second speed threshold may be 100 rpm or less. As another non-limiting example, the second speed threshold may be 200 rpm or less.

Continuing withFIGS.3-8, the magnetic assembly66also includes a second component74attached to the second wall62. As discussed above, the second wall62is stationary. Therefore, the second component74is also stationary. The first component68and the second component74interact with each other to create the magnetic attraction when the first component68is in the locked position.

Referring toFIGS.3-6and8, the first component68and the second component74align proximal to each other when the first component68is in the locked position such that the first component68and the second component74create the magnetic attraction therebetween to lock the first wall38in a stationary position when the electric machine24is in the second mode. More specifically, the first component68and the second component74align proximal to each other when the first component68is in the locked position such that the first component68and the second component74create the magnetic attraction therebetween to lock the first wall38and the propeller rotor30in the stationary position when the electric machine24is in the second mode. That is, magnetic latching occurs between the first component68and the second component74, without there being a physical attachment or physical engagement between the first component68and the second component74.

Referring toFIG.7, the first component68moves away from the second component74to the unlocked position due to rotation of the first wall38when the electric machine24is in the first mode. In certain configurations, the second component74is a stationary component of the electric machine24. Therefore, in certain configurations, the second component74may be further defined as part of the housing32of the electric machine24, the end cap34of the housing32of the electric machine24, or a component of the stator28, etc.

Referring toFIGS.3-8, the first component68may include an arm76having a proximal end46B attached to the first wall38via the pivot point70and a distal end44B extending outwardly away from the proximal end46B such that the distal end44B is spaced apart from the first wall38. The orientation and the configuration of the arm76may be any suitable orientation/configuration, and the figures provide some non-limiting examples. The different orientations and configurations will be discussed further below.

Generally, the first component68may include at least one first magnet78, and the second component74may include at least one second magnet80(seeFIGS.3-8). The at least one first magnet78is attached to the distal end44B of the arm76. The at least one second magnet80is attached to the second wall62. In certain configurations, the first magnet78aligns proximal to the second component74to create the magnetic attraction therebetween to lock the first wall38in the stationary position when the first component68is in the locked position. In other configurations, the first component68aligns proximal to the second magnet80to create the magnetic attraction therebetween to lock the first wall38in the stationary position when the first component68is in the locked position. More specifically, the first magnet78aligns proximal to the second magnet80to create the magnetic attraction therebetween to lock the first wall38in the stationary position when the first component68is in the locked position. The magnetic attraction created, when the first component68is in the locked position, is designed to be stronger than the forces due to the airflow A across the auxiliary propeller26to maintain the propeller rotor30in the stationary position.

Referring toFIGS.3-8, the first magnet78and the second magnet80are spaced away from each other regardless of the position of the first magnet78relative to the second magnet80, with the difference being the size of a gap82A,82B between the first magnet78and the second magnet80. Therefore, depending on the size of the gap82A,82B, the magnetic attraction changes, and thus, the magnetic assembly66uses magnetic latching to lock the propeller rotor30in the stationary position. No contact occurs between the first magnet78and the second magnet80. That is, locking of the propeller rotor30relative to the housing32of the electric machine24is not by a physical attachment between the propeller rotor30and the housing32, and instead occurs via the magnetic latching. As such, no drag is created between the first magnet78and the second magnet80due to the gap82A,82B being present at all times.

Turning toFIGS.3-6and8, the first magnet78and the second magnet80define a first gap82A therebetween when the first component68is in the locked position. Referring toFIG.7, the first magnet78and the second magnet80define a second gap82B therebetween when the first component68is in the unlocked position. As best shown by comparingFIGS.3-8, the second gap82B ofFIG.7is greater than the first gap82A ofFIGS.3-6and8.

When a predetermined torque is reached from operation of the electric machine24, the torque will override the magnetic attraction or magnetic pull between the first magnet78and the second magnet80and the first magnet78will move to the unlocked position. Referring toFIG.9, one non-limiting example of the relationship between the torque to lock the propeller rotor30in the locked position (i.e., locking torque) versus the size of the gap82A,82B is provided, and if these parameters are met (i.e., peak torque vs size of the gap82A,82B), the magnet attraction between the first magnet78and the second magnet80will be overcome to unlock the propeller rotor30. The relationship as illustrated in theFIG.9relates to a dual arm magnetic array, which corresponds to the array ofFIG.11.

Operation of the electric machine24in the first mode may easily override the second mode because the torque that locks the propeller rotor30in the locked position is overcome. For example, when the electric machine24is operating in the first mode to produce a torque of about 50 Newton meter (Nm) or greater, the magnetic attraction between the first magnet78and the second magnet80may be overcome to move to the unlocked position. That is, the locking torque is overcome to move the first component68to the unlocked position. Therefore, for example, the torque (i.e., the locking torque) to lock the first magnet78and the second magnet80in the locked position may be about 50 Nm or less. As another example, the torque produced in the first mode may be increased to about 400 Nm or greater, which is greater than the torque to lock the propeller rotor30in the locked position, and therefore, the magnetic attraction is overcome.

When the first component68(with the first magnet78) moves away from the second component74(with the second magnet80) toward the unlocked position, the gap82A,82B therebetween increases, which causes the magnetic attraction between the first magnet78and the second magnet80to decrease, eventually to a negligible amount. Therefore, when the propeller rotor30is rotating in normal operation (such as about 400 rpm or greater), the propeller rotor30is in the unlocked position and the gap82A,82B moves to the second gap82B spacing, which reduces the magnetic attraction between the first magnet78and the second magnet80to the negligible amount. Thus, the operation of the propeller rotor30is not affected by the magnetic assembly66.

In certain configurations, a plurality of magnets78,80may be utilized.FIGS.10-13include various non-limiting examples, which will be discussed further below. For illustrative purposes, many structures have been eliminated inFIGS.10-13to focus on the magnet configurations relative to the longitudinal axis40.

For example, the at least one first magnet78of the first component68may include a plurality of first magnets78, and the at least one second magnet80of the second component74may include a plurality of second magnets80. In certain configurations, the at least one first magnet78of the first component68may include the plurality of first magnets78spaced apart from each other around the first wall38, and the at least one second magnet80of the second component74may include the plurality of second magnets80spaced apart from each other around the second wall62. The first magnets78may be spaced around the first wall38radially relative to the longitudinal axis40, and the second magnets80may be spaced around the second wall62radially relative to the longitudinal axis40.

In certain configurations, respective first magnets78and respective second magnets80define the first gap82A therebetween when the first component68is in the locked position, as similarly discussed above in reference to the first magnet78and the second magnet80. Furthermore, the respective first magnets78and the respective second magnets80define the second gap82B therebetween when the first component68is in the unlocked position, as similarly discussed above in reference to the first magnet78and the second magnet80. The second gap82B of the respective first magnets78and the respective second magnets80is greater than the first gap82A of the respective first magnets78and the respective second magnets80, as similarly discussed above in reference to the first magnet78and the second magnet80.

Generally, the first magnets78and the second magnets80are arranged relative to each other to create the magnetic attraction when the electric machine24is in the second mode. The above discussion with regards to the first magnet78and the second magnet80also applies to the first magnets78and the second magnets80, and will not be repeated. In certain configurations, the first magnets78and the second magnets80are permanent magnets, and any of the configurations discussed herein may utilize permanent magnets as the magnets78,80.

In various configurations, the first magnets78and the second magnets80are arranged in a Halbach array, and more specifically, the first magnets78and the second magnets80may be collectively arranged in the Halbach array. The Halbach array is an arrangement of permanent magnets that create a magnetic field on one side of the array but minimizes a magnetic field on the other side of the array. Therefore, having the magnetic assembly66described herein optionally utilizing the Halbach array, the magnetic field created between the first magnets78and the second magnets80may be focused to a desired location between these magnets78,80and minimize any stray magnetic field being produced to affect the locking torque.

Optionally, the plurality of first magnets78may be arranged in clusters84,86and the plurality of second magnets80may be arranged in clusters84,86(see for exampleFIGS.10-13). Specifically, the first magnets78are clustered together and the second magnets80are also clustered together, and respective clusters84,86cooperate with each other to create the locking torque when in the locked position. Generally, the first magnets78are separated into a plurality of first clusters84each having two or more of the first magnets78. Each of the first clusters84are spaced from each other around the first wall38.

Similarly, the second magnets80are separated into a plurality of second clusters86each having two or more of the second magnets80. Each of the second clusters86are spaced from each other around the second wall62. The first clusters84and the second clusters86create a permanent magnet array, and in various configurations, the first clusters84and the second clusters86are arranged in the Halbach array.

In the examples ofFIGS.10-13, the first clusters84and the second clusters86are illustrated relative to each other when in the locked position (i.e., the respective clusters84,86align with each other). Also, provided inFIGS.10and11, is the magnetization pattern for the permanent magnets. Different arrangements of the first cluster(s)84and the second cluster(s)86may provide different flux configurations, and examples will be discussed below. Generally, whether the flux is an axial flux configuration or a radial flux configuration depends on the flux direction in the gap82A,82B.

Referring toFIGS.10and11, brackets have been provided to associate the magnetization pattern for each of the first magnets78of one of the first clusters84, and similarly, brackets have been provided to associate the magnetization pattern for each of the second magnets80of one of the second clusters86.

Referring toFIG.10, as an example, there are two separate first clusters84and two separate second clusters86, and one of the first clusters84has a bracket Y that correspond to the magnetization pattern of each of the first magnets78. One of the second clusters86has a bracket YY that correspond to the respective magnetization pattern of each of the second magnets80. Even though not labeled inFIG.10, the other first cluster84and the other second cluster86have the same corresponding magnetization pattern as shown inFIG.10. The configuration ofFIG.10may create an axial flux configuration.

Now turning toFIG.11, as another example, there are two separate first clusters84and two separate second clusters86, and one of the first clusters84has a bracket Z that correspond to the magnetization pattern of each of the first magnets78. One of the second clusters86has a bracket ZZ that correspond to the respective magnetization pattern of each of the second magnets80. Even though not labeled inFIG.11, the other first cluster84and the other second cluster86have the same corresponding magnetization pattern as shown inFIG.11. The configuration ofFIG.11may create an axial flux configuration.

The difference between the configuration ofFIG.10and the configuration ofFIG.11is that the number of magnets78,80in the first cluster84is different than the number of magnets78,80in the first cluster84, and similarly, the number of magnets78,80in the second cluster86is different than the number of magnets78,80in the second cluster86. In addition, the magnetization pattern ofFIG.11is different from the magnetization pattern ofFIG.10.

FIG.12provides yet another example of two separate first clusters84and two separate second clusters86, and the first clusters84are angled relative to the respective second clusters86. The configuration ofFIG.12may create an axial flux configuration.

Referring toFIG.13, another example of the first clusters84and the second clusters86is provided. In this example, there are four separate first clusters84and four separate second clusters86. The configuration ofFIG.13may create a radial flux configuration.

It is to be appreciated that the orientation of the first clusters84and the second clusters86of theFIG.10configuration may be changed to the orientation of theFIG.13configuration, which would convert theFIG.10arrangement from the axial flux configuration to a radial flux configuration. Also, it is to be appreciated that the orientation of the first clusters84and the second clusters86of theFIG.11configuration may be converted similarly to create a radial flux configuration instead of the axial flux configuration.

Generally, the flux configurations may be different depending on the orientation of the first component68and the second component74relative to each other. That is, whether the flux is an axial flux configuration or a radial flux configuration depends on the flux direction in the gap82A,82B. For example, the radial flux configuration ofFIG.13may correspond to the configuration ofFIG.5where the arm76moves inwardly toward the longitudinal axis40and outwardly away from the longitudinal axis40. For the axial flux configuration configurations ofFIGS.10-12, the axial flux configurations may correspond to the configurations ofFIGS.6-8, where the arm76moves upwardly and downwardly relative to the longitudinal axis40.

Next, the different orientations of the first component68will be discussed. Generally, the first component68and the second component74may be in any suitable location, and non-limiting examples will be discussed in regards toFIGS.3-8.

Turning toFIGS.3and4, these figures generally illustrate two different mounting locations of the arm76relative to the first wall38. In the configurations ofFIGS.3and4, the arm76pivots about the pivot point70such that the arm76moves axially relative to the longitudinal axis40. That is, referring to the orientation of the arm76inFIGS.3and4for illustrative purposes only, the distal end44B of the arm76lifts upwardly away from the second component74, which is generally axially relative to the longitudinal axis40.

Referring toFIG.3, the pivot point70is attached to the outer surface58of the first wall38. More specifically, the pivot point70may be attached to the inner wall portion48of the first wall38, and in certain configurations, attached to the outer surface58of the inner wall portion48. In this configuration, the distal end44B of the arm76extends outwardly away from the proximal end46B, and faces outwardly toward the stator28and away from the longitudinal axis40. The arm76is movable concurrently with the first wall38about the longitudinal axis40when the electric machine24is in the first mode, and the arm76is also movable about the pivot axis72independently of the first wall38. Generally, the arm76is disposed in the opening52between the inner wall portion48and the outer wall portion50. The distal end44B of the arm76may move into and out of the opening52or the distal end44B of the arm76may be disposed in the space54between the outer wall portion50and the second wall62. That is, the second length L2of the outer wall portion50may accommodate the distal end44B and movement thereof.

Referring toFIG.4, in other configurations, the pivot point70is attached to the inner surface56of the first wall38. More specifically, the proximal end46B of the arm76of the first component68is attached to the inner surface56of the first wall38via the pivot point70and the distal end44B extends outwardly away from the proximal end46B such that the distal end44B is spaced apart from the first wall38. In this configuration, the distal end44B of the arm76extends outwardly toward the longitudinal axis40and faces inwardly toward the inner wall portion48. The distal end44B of the arm76may move into and out of the opening52or the distal end44B of the arm76may be disposed in the space54between the outer wall portion50and the second wall62. That is, the second length L2of the outer wall portion50may accommodate the distal end44B and movement thereof. The arm76is movable concurrently with the first wall38about the longitudinal axis40when the electric machine24is in the first mode, and the arm76is also movable about the pivot axis72independently of the first wall38.

Turning toFIGS.6-8, the orientation of the arm76may be changed as compared toFIGS.3and4. In the configuration ofFIGS.6-8, the pivot point70is disposed transverse to the longitudinal axis40, and extends outwardly from the first wall38. For example, the pivot axis72intersects the inner surface56of the first wall38in these configurations. As another example, the pivot axis72may intersect the inner surface56and the outer surface58of the first wall38. Therefore, the arm76is mounted to the pivot point70such that the arm76moves substantially parallel relative to part of the first wall38. The arm76is spaced apart from the inner surface56of the first wall38relative to the pivot axis72such that the arm76moves laterally alongside the inner surface56as the arm76rotates about the pivot axis72when the electric machine24is in the first mode. As such, rotation of the arm76is not impeded by the first wall38. For the configurations ofFIGS.3,4, and6-8, generally, gravity may assist in returning the arm76back to the locked position. However, for the configurations ofFIGS.3,4, and6-8, optionally, a biasing member, such as a spring, etc., may be used to assist in returning the arm76back to the locked position when the electric machine24is shut off. Therefore, the biasing member may engage the arm76to assist in returning the arm76to the locked position.

More specifically, as shown inFIGS.6-8, the arm76is disposed at least partially in the opening52between the inner wall portion48and the outer wall portion50, and the pivot point70may be attached to the inner surface56of the outer wall portion50. In other configurations, the arm76is disposed at least partially in the opening52between the inner wall portion48and the outer wall portion50, and the pivot point70may be attached to the outer surface58of the inner wall portion48. The distal end44B of the arm76may move into and out of the opening52or the distal end44B of the arm76may be disposed in the space54between the outer wall portion50and the second wall62. That is, the second length L2of the outer wall portion50may accommodate the distal end44B and movement thereof.

Also, the arm76may have a middle portion88disposed between the proximal end46B and the distal end44B. The middle portion88may be any suitable configuration to assist in aligning the first magnet(s)78with the second magnet(s)80. ComparingFIGS.3,4,6, and7withFIG.8, the middle portion88has different configurations.FIGS.3,4,6, and7provide a generally right-angle bend or a generally left-angle bend of the middle portion88, whileFIG.8illustrates a tapered bend or gradual angular bend of the middle portion88.

Turning toFIG.5, the orientation and the configuration of the arm76are different thanFIGS.3,4, and6-8. The arm76is movable concurrently with the first wall38about the longitudinal axis40when the electric machine24is in the first mode, and the arm76is also movable about the pivot axis72independently of the first wall38. That is, referring to the orientation of the arm76inFIG.5for illustrative purposes only, the distal end44B of the arm76moves sideways away from the second component74, which is generally radially relative to the longitudinal axis40.

Continuing with the configuration ofFIG.5, the pivot axis72is spaced apart from and is substantially parallel to the longitudinal axis40. Here, the second component74extends outwardly from the second wall62toward the opening52such that the arm76is disposed between the second component74and the first wall38. The first component68and the second component74are both disposed between the inner wall portion48and the outer wall portion50radially relative to the longitudinal axis40. The arm76may be disposed in the space54between the first wall38and the second wall62, and therefore, the first component68and the second component74are disposed between the outer surface58of the inner wall portion48and the inner surface56of the outer wall portion50.

With continued reference toFIG.5, the arm76is spaced apart from the first wall38such that the arm76moves closer to the inner surface56as the arm76rotates about the pivot axis72when the electric machine24is in the first mode. As the propeller rotor30speeds up when the electric machine24is in the first mode, inertia acts on the arm76, and once the second speed threshold is reached, the arm76will rotate about the pivot axis72due to the inertia which will push the arm76away from the second magnet80and toward the inner surface56of the first wall38. In the configuration ofFIG.5, this movement of the arm76toward the unlocked position, is toward the inner surface56of the outer wall portion50of the first wall38. Optionally, for the configuration ofFIG.5, a biasing member, such as a spring, etc., may be used to assist in returning the arm76back to the locked position when the electric machine24is shut off. Therefore, the biasing member may engage the arm76to assist in returning the arm76to the locked position.

Referring toFIGS.6and7, the first component68may optionally include a stop90disposed adjacent to the arm76. The stop90limits movement of the arm76beyond at least one of the locked position and the unlocked position. In certain configurations, the stop90limits movement of the arm76beyond the unlocked position. In other configurations, the stop90limits movement of the arm76beyond the locked position. In yet other configurations, the stop90limits movement of the arm76beyond the locked position and the unlocked position. The stop90may extend outwardly from the first component68.

The arm76engages or abuts the stop90to limit movement of the arm76. The stop90may include a first stop segment92relative to one side of the arm76and a second stop segment94spaced from the first stop segment92. The arm76is disposed between the first stop segment92and the second stop segment94, and in one configuration, the proximal end46B of the arm76is disposed between the first stop segment92and the second stop segment94. In the example ofFIGS.6and7, when the arm76rotates to the unlocked position, rotation will be limited when the arm76engages the first stop segment92, and when the arm76rotates to the locked position, rotation will be limited when the arm76engages the second stop segment94. It is to be appreciated that any of the configurations described herein may optionally include the stop90even if this feature is eliminated from some of the figures.

The present disclosure also provides for a rotor assembly96for the aircraft10. The rotor assembly96may include the propeller rotor30that is selectively rotatable about the longitudinal axis40. As discussed above, one of the auxiliary propellers26is attached to one of the propeller rotors30of one of the electric machines24. Therefore, when the electric machine24is energized to rotate the propeller rotor30, the propeller rotor30causes the auxiliary propeller26to correspondingly rotate. The propeller rotor30and the auxiliary propeller26are rotatable about a respective longitudinal axis40. That is, each of the auxiliary propellers26are rotatable about a respective longitudinal axis40. As a non-limiting example, referring toFIGS.1and2, there are eight auxiliary propellers26, and each of these auxiliary propellers26are rotatable about a respective longitudinal axis40.

The rotor assembly96may include the locking assembly64coupled to the propeller rotor30and configured to selectively lock the propeller rotor30in the stationary position. That is, the locking assembly64may prevent the propeller rotor30from rotating about the longitudinal axis40, and thus, locks the propeller rotor30in the stationary position. As discussed above, the stationary position may be the fore-aft position of the auxiliary propellers26. The rotor assembly96may include all of the locking assembly64features discussed above, and therefore, will not be repeated.

The present disclosure also pertains to a method of controlling the propeller rotor30of the aircraft10. The method uses the locking assembly64to selectively lock the propeller rotor30in the stationary position. By locking the propeller rotor30in the stationary position, drag may be reduced because the auxiliary propellers26will not be able to free-wheel during wing-borne flight. Furthermore, the propeller rotor30is locked in a desired position, such as the auxiliary propeller26is locked in the fore-aft position to minimize drag due to the direction of the airflow A.

For illustrative purposes, the below discussion will assume that the aircraft10is taking off, and thus, will start in the hover phase.

To start the hover phase, the electric machine24is signaled, via the controller60, to operate in the first mode to produce torque to drive rotation of the propeller rotor30. As discussed above, the electric machine24includes the first wall38coupled to the propeller rotor30such that the first wall38and the propeller rotor30are rotatable together about the longitudinal axis40when the electric machine24is in the first mode. Once the second speed threshold is reached, the first component68moves from the locked position to the unlocked position. When this occurs, the first magnet(s)78and the second magnet(s)80further separate, and the magnetic attraction therebetween decreases, eventually to a negligible amount. The operation of the propeller rotor30is not affected by the magnetic assembly66when the locking assembly64is in the unlocked position.

Once the aircraft10reaches the cruise phase, the electric machine24is signaled, via the controller60, to operate in the second mode to deenergize the electric machine24to stop production of the torque which causes rotation of the propeller rotor30to stop. As discussed above, the first wall38and the propeller rotor30become stationary relative to the longitudinal axis40when the electric machine24is in the second mode. Furthermore, the electric machine24includes the second wall62spaced apart from the first wall38and the second wall62is stationary relative to the first wall38regardless of the electric machine24being in the first mode or the second mode. Once the first speed threshold is reached, the first component68moves from the unlocked position to the locked position. When this occurs, the first magnet78(s) and the second magnet(s)80align with each other, and the magnetic attraction therebetween increases to lock the propeller rotor30in the stationary position.

The locking assembly64is operated to selectively lock the propeller rotor30in the stationary position such that the first component68of the magnetic assembly66and the second component74of the magnetic assembly66align proximal to each other when the first component68is in the locked position in which the first component68and the second component74create the magnetic attraction therebetween to lock the first wall38and the propeller rotor30in the stationary position when the electric machine24is in the second mode. The first component68moves away from the second component74to the unlocked position due to rotation of the first wall38when the electric machine24is in the first mode. As discussed above, the first component68is coupled to the first wall38via the pivot point70and is movable relative to the pivot point70to the locked position and the unlocked position. The second component74is attached to the second wall62.

When it is desirable to land the aircraft10, the hover phase will again be reached, and the controller60will signal the electric machine24to switch from the second mode back to the first mode, and operate accordingly.

It is to be appreciated that the order or sequence of performing the method as discussed above is for illustrative purposes and other orders or sequences are within the scope of the present teachings. It is to also be appreciated that the method may include other features not specifically discussed above.

The present disclosure provides a light weight design that does not require any additional controls, or any additional power supply, to operate the locking assembly64. As discussed above, there is always the gap82A,82B, such as an airgap, between the first magnet(s)78and the second magnet(s)80, and therefore, no drag occurs between these components68,74. The magnetic assembly66may be incorporated into the electric machine24, and therefore, further reduce the footprint of the locking assembly64.

While the best modes and other configurations for carrying out the disclosure have been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and configurations for practicing the disclosure within the scope of the appended claims. Furthermore, the configurations shown in the drawings or the characteristics of various configurations mentioned in the present description are not necessarily to be understood as configurations independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of a configuration can be combined with one or a plurality of other desired characteristics from other configurations, resulting in other configurations not described in words or by reference to the drawings. Accordingly, such other configurations fall within the framework of the scope of the appended claims.

The following Clauses provide some example configurations of the locking assembly, the rotor assembly, and the method as disclosed herein.

Clause 1: A locking assembly for a propeller rotor of an aircraft, the locking assembly comprising: an electric machine having a first mode to energize the electric machine to produce torque and a second mode to deenergize the electric machine to stop production of the torque; wherein the electric machine includes a first wall rotatable about a longitudinal axis when the electric machine is in the first mode, and the first wall becomes stationary relative to the longitudinal axis when the electric machine is in the second mode; wherein the electric machine includes a second wall spaced apart from the first wall and the second wall is stationary relative to the first wall regardless of the electric machine being in the first mode or the second mode; a magnetic assembly including a first component coupled to the first wall via a pivot point, and including a second component attached to the second wall; wherein the first component is movable relative to the pivot point to a locked position and an unlocked position; and wherein the first component and the second component align proximal to each other when the first component is in the locked position such that the first component and the second component create a magnetic attraction therebetween to lock the first wall in a stationary position when the electric machine is in the second mode, and wherein the first component moves away from the second component to the unlocked position due to rotation of the first wall when the electric machine is in the first mode.

Clause 2: The locking assembly of clause 1, wherein the first component includes an arm having a proximal end attached to the first wall via the pivot point and a distal end extending outwardly away from the proximal end such that the distal end is spaced apart from the first wall.

Clause 3: The locking assembly of clause 2, wherein the first component includes at least one first magnet attached to the distal end of the arm, and the first magnet aligns proximal to the second component to create the magnetic attraction therebetween to lock the first wall in the stationary position when the first component is in the locked position.

Clause 4: The locking assembly of any of the preceding clauses, wherein: the first component includes a pivot support attached to the first wall and the pivot support extends outward from the first wall; the proximal end of the arm is movably attached to the pivot support; and the arm is rotatable about the pivot support along a pivot axis, and the pivot axis intersects the pivot support and the first wall.

Clause 5: The locking assembly of clauses 1 or 2, wherein the first component includes at least one first magnet, and the first magnet aligns proximal to the second component to create the magnetic attraction therebetween to lock the first wall in the stationary position when the first component is in the locked position.

Clause 6: The locking assembly of clause 5, wherein the second component includes at least one second magnet attached to the second wall, and the first magnet aligns proximal to the second magnet to create the magnetic attraction therebetween to lock the first wall in the stationary position when the first component is in the locked position.

Clause 7: The locking assembly of clauses 5 or 6, wherein: the first magnet and the second magnet define a first gap therebetween when the first component is in the locked position; the first magnet and the second magnet define a second gap therebetween when the first component is in the unlocked position; and the second gap is greater than the first gap.

Clause 8: The locking assembly of clauses 5, 6, or 7, wherein the at least one first magnet includes a plurality of first magnets spaced apart from each other around the first wall, and the at least one second magnet includes a plurality of second magnets spaced apart from each other around the second wall.

Clause 9: The locking assembly of any of the preceding clauses, wherein the first magnets and the second magnets are permanent magnets arranged in a Halbach array.

Clause 10: The locking assembly of any of clauses 1-3 or 5-9, wherein: the first wall includes an inner surface that faces inwardly toward the longitudinal axis and an outer surface that opposes the inner surface and faces outwardly away from the longitudinal axis; the first component includes an arm having a proximal end attached to the inner surface of the first wall via the pivot point and a distal end extending outwardly away from the proximal end such that the distal end is spaced apart from the first wall; the arm is movable concurrently with the first wall about the longitudinal axis when the electric machine is in the first mode, and the arm is also movable about a pivot axis independently of the first wall; and the pivot axis intersects the inner surface and the outer surface of the first wall.

Clause 11: The locking assembly of clause 10, wherein the arm is spaced apart from the inner surface of the first wall relative to the pivot axis such that the arm moves laterally alongside the inner surface as the arm rotates about the pivot axis when the electric machine is in the first mode.

Clause 12: The locking assembly of clause 10, wherein the arm is spaced apart from the first wall such that the arm moves closer to the inner surface as the arm rotates about the pivot axis when the electric machine is in the first mode.

Clause 13: The locking assembly of clauses 1 or 2, wherein the second component includes at least one second magnet attached to the second wall, and the first component aligns proximal to the second magnet to create the magnetic attraction therebetween to lock the first wall in the stationary position when the first component is in the locked position.

Clause 14: The locking assembly of any of the preceding clauses, wherein the electric machine includes a housing having an end cap, and wherein the second component is further defined as the end cap.

Clause 15: A rotor assembly for an aircraft, the rotor assembly comprising: a propeller rotor selectively rotatable about a longitudinal axis; a locking assembly coupled to the propeller rotor and configured to selectively lock the propeller rotor in a stationary position, the locking assembly including: an electric machine coupled to the propeller rotor and having a first mode to energize the electric machine to produce torque to drive rotation of the propeller rotor and a second mode to deenergize the electric machine to stop production of the torque which causes rotation of the propeller rotor to stop; wherein the electric machine includes a first wall coupled to the propeller rotor such that the first wall and the propeller rotor are rotatable together about the longitudinal axis when the electric machine is in the first mode, and wherein the first wall and the propeller rotor become stationary relative to the longitudinal axis when the electric machine is in the second mode; wherein the electric machine includes a second wall spaced apart from the first wall and the second wall is stationary relative to the first wall regardless of the electric machine being in the first mode or the second mode; a magnetic assembly including a first component coupled to the first wall via a pivot point, and including a second component attached to the second wall; wherein the first component is movable relative to the pivot point to a locked position and an unlocked position; and wherein the first component and the second component align proximal to each other when the first component is in the locked position such that the first component and the second component create a magnetic attraction therebetween to lock the first wall and the propeller rotor in the stationary position when the electric machine is in the second mode, and wherein the first component moves away from the second component to the unlocked position due to rotation of the first wall when the electric machine is in the first mode.

Clause 16: The rotor assembly of clause 15, wherein: the electric machine includes a fan blade structure configured to dissipate heat inside of the electric machine; the first wall surrounds the fan blade structure and is attached to the fan blade structure; the first wall includes an inner surface that faces inwardly toward the longitudinal axis; the first component includes an arm having a proximal end attached to the inner surface of the first wall via the pivot point and a distal end extending outwardly away from the proximal end such that the distal end is spaced apart from the first wall; the arm is movable concurrently with the first wall about the longitudinal axis when the electric machine is in the first mode, and the arm is also movable about a pivot axis independently of the first wall; and the pivot axis intersects the inner surface.

Clause 17: The rotor assembly of clauses 15 or 16, wherein the first component includes a stop disposed adjacent to the arm, and the stop limits movement of the arm beyond at least one of the locked position and the unlocked position.

Clause 18: The rotor assembly of clauses 15, 16, or 17, wherein: the first component includes a plurality of first magnets spaced apart from each other around the first wall; the second component includes a plurality of second magnets spaced apart from each other around the second wall; respective first magnets and respective second magnets define a first gap therebetween when the first component is in the locked position; the respective first magnets and the respective second magnets define a second gap therebetween when the first component is in the unlocked position; and the second gap of the respective first magnets and the respective second magnets is greater than the first gap of the respective first magnets and the respective second magnets.

Clause 19: The rotor assembly of any one of clauses 15-18, wherein: the first magnets are separated into a plurality of first clusters each having two or more of the first magnets, and each of the first clusters are spaced from each other around the first wall; the second magnets are separated into a plurality of second clusters each having two or more of the second magnets; and the first clusters and the second clusters create a permanent magnet array.

Clause 20: A method of controlling a propeller rotor of an aircraft, the method comprising: signaling, via a controller, an electric machine to operate in a first mode to produce torque to drive rotation of the propeller rotor, wherein the electric machine includes a first wall coupled to the propeller rotor such that the first wall and the propeller rotor are rotatable together about a longitudinal axis when the electric machine is in the first mode; signaling, via the controller, the electric machine to operate in a second mode to deenergize the electric machine to stop production of the torque which causes rotation of the propeller rotor to stop, wherein the first wall and the propeller rotor become stationary relative to the longitudinal axis when the electric machine is in the second mode, and wherein the electric machine includes a second wall spaced apart from the first wall and the second wall is stationary relative to the first wall regardless of the electric machine being in the first mode or the second mode; and operating a locking assembly to selectively lock the propeller rotor in a stationary position such that a first component of a magnetic assembly and a second component of the magnetic assembly align proximal to each other when the first component is in a locked position in which the first component and the second component create a magnetic attraction therebetween to lock the first wall and the propeller rotor in the stationary position when the electric machine is in the second mode, and wherein the first component moves away from the second component to an unlocked position due to rotation of the first wall when the electric machine is in the first mode, wherein the first component is coupled to the first wall via a pivot point and movable relative to the pivot point to the locked position and the unlocked position, and the second component is attached to the second wall.