Structural stator core

Abstract

Electric motors and related methods employ a stator assembly as part of a housing assembly that counteracts an output shaft load to a mounting base. An electric motor includes an output shaft, a rotor coupled to the output shaft, a first housing, a first bearing assembly coupled to the first housing, a second housing, a second bearing assembly coupled to the second housing, and a stator assembly. The stator assembly includes a structural stator core member and a stator coil. A structural stator core member extends circumferentially around the output shaft. The second housing is coupled to the first housing by the stator core.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 407,117, filed on September 15, 2022, the disclosure of which is incorporated herein by reference. Background Art

[0002] The electric motor typically includes a housing assembly, an output shaft, a rotor, and a stator. The housing assembly includes bearings that support the output shaft. The rotor is attached to the output shaft. The stator typically includes coils, each of which is wrapped around one or more magnetically permeable core members. A drive current is typically applied to the coils to generate a magnetic field that is used to drive the rotation of the rotor, thereby driving the rotation of the output shaft.

[0003] The use of electric motors in many applications is increasing at a significant rate. For example, electric motors are increasingly being employed in vehicles such as cars and trucks. More recently, electric motors are increasingly being employed in aerial vehicles. In many vehicles, and especially in aerial vehicles, electric motors having an increased power-to-weight ratio are of interest due to the beneficial effects on vehicle efficiency and / or capability. Summary of the invention

[0004] A simplified overview of some embodiments of the present invention is presented below to provide a basic understanding of the present invention. This overview is not an extensive overview of the present invention. It is not intended to identify key / important elements of the present invention or to describe the scope of the present invention. Its sole purpose is to present some embodiments of the present invention in a simplified form as a preface to a more detailed description presented later.

[0005] The embodiments described herein are directed to an electric motor that includes a structural stator core that forms part of a housing assembly that supports an output shaft of the electric motor. In many embodiments, the structural stator core includes a stator-to-housing attachment feature, via which the structural stator core is attached to and between two housing members. The structural stator core transfers loads between the two housing members. By employing the structural stator core as part of the housing assembly, the overall weight of the electric motor can be reduced. In addition, since the outer circumferential wall of the stator core can be exposed, cooling fins can be directly attached to the structural stator core. Therefore, using the structural stator core as part of the housing assembly facilitates reducing the weight of the electric motor and / or improving the cooling of the electric motor.

[0006] Thus, in one aspect, an electric motor includes an output shaft, a rotor, a first housing, a first bearing assembly, a second housing, a second bearing assembly, and a stator assembly. The output shaft is configured to rotate about an output shaft rotation axis. The rotor is coupled to the output shaft. The first housing includes a first housing-to-stator attachment feature. The first bearing assembly is coupled to the first housing and docks with a first section of the output shaft. The second housing includes a second housing-to-stator attachment feature. The second bearing assembly is coupled to the second housing and docks with a second section of the output shaft. The stator assembly includes a stator core and a stator coil. The stator core includes a stator back iron, stator teeth, and a stator-to-housing attachment feature. The second housing is coupled to the first housing by the stator core via the second housing-to-stator attachment feature, the first housing-to-stator attachment feature, and the stator-to-housing attachment feature. The stator back iron extends circumferentially around the output shaft rotation axis. The stator back iron is configured to react one or more interface forces applied to the second bearing assembly by the second section of the output shaft to the first housing. Each of the stator teeth extends radially inward from the stator back iron toward the output shaft rotation axis. Each of the stator coils extends circumferentially around a corresponding one of the stator teeth.

[0007] In some embodiments of the electric motor, one of the first bearing assembly and the second bearing assembly is configured to react both radial loads and thrust loads, and the other of the first bearing assembly and the second bearing assembly is configured to react only radial loads. For example, in some embodiments of the electric motor, the first bearing assembly is configured to react one or more first bearing assembly radial loads from a first section of the output shaft into a first housing, wherein each of the one or more first bearing assembly radial loads is radially oriented relative to the output shaft rotation axis. The first bearing assembly may also be configured to react thrust loads from the output shaft into the first housing, wherein the thrust load is aligned with the output shaft rotation axis. The second bearing assembly may be configured to react one or more second bearing assembly radial loads from a second section of the output shaft into the second housing, wherein each of the one or more second bearing assembly radial loads is radially oriented relative to the output shaft rotation axis. The first housing may include one or more motor mounting features configured to mount the electric motor to a mounting base.

[0008] In many embodiments of the electric motor, the stator core is attached to the first housing and the second housing and is attached between the first housing and the second housing. For example, in some embodiments, the electric motor includes a stator attachment bolt, via which the stator core is attached to the first housing and the second housing and is attached between the first housing and the second housing. The stator-to-housing attachment feature may include a stator-to-housing attachment fastener hole. The first housing-to-stator attachment feature may include a first housing-to-stator attachment fastener hole. The second housing-to-stator attachment feature may include a second housing-to-stator attachment fastener hole. Each of the stator attachment bolts may extend through a corresponding one of the first housing-to-stator attachment fastener holes, a corresponding one of the second housing-to-stator attachment fastener holes, and a corresponding one of the stator-to-housing attachment fastener holes.

[0009] Since the stator core is attached to and between each of the first and second housings in many embodiments of the electric motor, the stator core is exposed along the outer periphery of the electric motor, thereby enabling more direct cooling of the stator core. For example, in many embodiments, the electric motor includes cooling fins attached to the outer circumferential surface of the stator back iron. The cooling fins can be attached to the outer periphery of the stator back iron using any suitable method. For example, the cooling fins can be bonded to the outer circumferential surface via a thermally conductive adhesive.

[0010] The rotor of the electric motor may have any suitable configuration. For example, in some embodiments of the electric motor, the rotor includes permanent magnets.

[0011] In many embodiments of the electric motor, the stator core is integrally formed from magnetically permeable material.The stator back iron, stator teeth, and stator to housing attachment features may be integrally formed from magnetically permeable material.

[0012] The electric motor may be configured for use in any suitable application. For example, an aircraft may include at least one of the electric motors. The output shaft may be drivingly coupled to any suitable power assembly of the aircraft. For example, the output shaft may be drivingly coupled to a lift fan of the aircraft.

[0013] In another aspect, a method for supporting an output shaft of an electric motor employs a structural stator core. The method includes supporting the output shaft using a first bearing assembly and a second bearing assembly offset from the first bearing assembly along the rotational axis of the output shaft. The method also includes supporting the first bearing assembly via a first housing to which the first bearing assembly is coupled. The method also includes supporting the first housing via a mounting base via attachment of the first housing to the mounting base. The method also includes supporting the second bearing assembly via a second housing to which the second bearing assembly is coupled. In many embodiments, the second housing is offset from the first housing along the rotational axis of the output shaft. The method also includes supporting the stator assembly by the first housing via attachment of a first end of the stator assembly to the first housing. The method also includes supporting the second housing by the stator assembly via attachment of the second housing to a second end of the stator assembly, wherein the second end of the stator assembly is opposite to the first end of the stator assembly.

[0014] In many embodiments of the method of supporting an output shaft of an electric motor, a structural load is transmitted through a stator assembly. For example, in many embodiments, the method further includes: transmitting a first bearing assembly load from the output shaft to the mounting base through a first load path extending through a first bearing assembly and a first housing to the mounting base; and transmitting a second bearing assembly load from the output shaft to the mounting base through a second load path extending through a second bearing assembly, a second housing, a stator assembly, and the first housing to the mounting base. In many embodiments of the method, the second bearing assembly load is radially oriented relative to the axis of rotation of the output shaft, the first bearing assembly load includes a radial load component and a thrust load component, the radial load component is radially oriented relative to the axis of rotation of the output shaft, and the thrust load component is aligned with the axis of rotation of the output shaft.

[0015] The stator assembly employed in the method of supporting the output shaft of an electric motor may have any suitable configuration. For example, the stator assembly may include a stator core and a stator coil. The stator core may include a stator back iron, stator teeth, and a stator-to-housing attachment feature. The stator core may be coupled to and between a first housing and a second housing via the stator-to-housing attachment feature of the stator core.

[0016] The method of supporting the output shaft of the electric motor may be employed in any suitable application.For example, the output shaft of the electric motor may be drivingly coupled to any suitable electric component of the aircraft, such as, for example, a lift fan.

[0017] In another aspect, a method for cooling an electric motor employs a structural stator core. The method includes supporting a first bearing assembly for an output shaft of the electric motor via a first housing to which the first bearing assembly is coupled. The method also includes supporting a second bearing assembly for the output shaft via a second housing to which the second bearing assembly is coupled. The method also includes maintaining engagement between the first end of the stator assembly and the first housing via attachment of the first end of the stator assembly to the first housing. The method also includes maintaining engagement between the second end of the stator assembly and the second housing via attachment of the second end of the stator assembly to the second housing. The method also includes supporting cooling fins attached to the stator assembly so that the cooling fins are exposed to air that is not enclosed by the first housing, the second housing, and the stator assembly. The method also includes cooling the electric motor by conducting heat from the stator assembly into the cooling fins.

[0018] In some embodiments of the method for cooling an electric motor, a stator assembly includes a stator core and a stator coil. The stator core may include a stator back iron, stator teeth, and a stator to housing attachment feature. The stator back iron may extend circumferentially around the axis of rotation of the output shaft. Each of the first housing and the second housing may be coupled to the stator core via the stator to housing attachment feature. In some embodiments, a cooling fin is thermally coupled to an outer circumferential surface of the stator back iron. For example, the cooling fin may be thermally coupled to the outer circumferential surface of the stator back iron via a thermally conductive adhesive.

[0019] For a fuller understanding of the nature and advantages of the present invention, reference should be made to the ensuing detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A partial cross-sectional view of an electric motor is shown according to an embodiment, the electric motor including a structural stator core member forming part of a housing assembly of the electric motor.

[0021] Figure 2 Show Figure 1 Schematic illustration of a side cross section of an electric motor.

[0022] Figure 3 Show Figure 1 A partial top view of a stator assembly of an electric motor.

[0023] Figure 4 is a simplified block diagram of a method of supporting an output shaft of an electric motor in which a structural stator core member forms part of a support structure for the output shaft, according to an embodiment.

[0024] Figure 5 is a simplified block diagram of a method of cooling an electric motor using cooling fins attached to a stator assembly of the electric motor, according to an embodiment.

[0025] Figure 6Shown including according to Figure 1 The electric motor of the electric aircraft. DETAILED DESCRIPTION

[0026] In the following description, various embodiments of the present invention will be described. For the purpose of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to those skilled in the art that the present invention may be practiced without the specific details. In addition, well-known features may be omitted or simplified so as not to obscure the described embodiments.

[0027] In many existing electric motors, the stator core is enclosed and supported by a housing made of different materials. For example, the housing is usually made of aluminum, and the stator core is typically made of some suitable magnetically permeable iron alloy. The heat generated by many existing electric motors is typically transferred from the stator core to the housing via conduction, and from the housing to cooling fins attached to the housing. The housing and the stator core typically have different rates of thermal expansion, which may require the use of a thermal interface that can accommodate the different rates of thermal expansion. However, the use of a thermal interface can result in reduced thermal conduction, thereby reducing the cooling of the electric motor and reducing the performance of the electric motor.

[0028] Turning now to the drawings in which like reference numerals refer to like features, Figure 1 A partial cross-sectional view of an electric motor 10 according to an embodiment is shown. Figure 2 A schematic illustration of a side cross section of an electric motor 10 is shown. Figure 3 A partial top view of the stator assembly 12 of the electric motor 10 is shown. The electric motor 10 includes an output shaft 14, a rotor 16, a first housing 18, a first bearing assembly 20, a second housing 22, a second bearing assembly 24, and the stator assembly 12. The output shaft 14 has an output shaft rotation axis 26. The rotor 16 is coupled to the output shaft 14 for driving rotation of the output shaft 14. The first housing 18 includes a first housing to stator attachment feature 28. The first bearing assembly 20 is coupled to the first housing 18 and interfaces with a first section of the output shaft 14. The second housing 22 includes a second housing to stator attachment feature 30. The second bearing assembly 24 is coupled to the second housing 22 and interfaces with a second section of the output shaft 14.

[0029] The stator assembly 12 includes a stator core 32 and a stator coil 34. The stator core 32 includes a stator back iron 36, stator teeth 38, and a stator-to-housing attachment feature 40. The stator back iron 36 extends circumferentially around the output shaft rotation axis 26. The second housing 22 is coupled to the first housing 18 by the stator core 32 via the second housing-to-stator attachment feature 30, the first housing-to-stator attachment feature 28, and the stator-to-housing attachment feature 40. One or more interface forces applied to the second bearing assembly 24 by the second segment of the output shaft 14 are transmitted to the first housing 18 through the stator back iron 36 and the stator-to-housing attachment feature 40. Each of the stator teeth 38 extends radially inward from the stator back iron 36. Each of the stator coils 34 extends circumferentially around a corresponding one of the stator teeth 38.

[0030] The stator core 32 forms part of a load path through which the load applied to the second bearing assembly 24 by the output shaft 14 is transferred to the mounting base 48. The first bearing assembly 20 is configured to react one or more first bearing assembly radial loads from the first section of the output shaft 14 into the first housing 18, which transfers the one or more first bearing assembly radial loads received from the first bearing assembly 20 to the mounting base 48. Each of the one or more first bearing assembly radial loads is radially oriented relative to the output shaft rotational axis 26. The first bearing assembly 20 is configured to react a thrust load from the output shaft 14 into the first housing 18, which then transfers the thrust load to the mounting base 48. The thrust load is aligned with the output shaft rotational axis 26. The second bearing assembly 24 is configured to react one or more second bearing assembly radial loads from the second section of the output shaft 14 into the second housing 22, which transmits the one or more second bearing assembly radial loads to the structural stator core 32 via the second housing-to-stator attachment features 30 and the stator-to-housing attachment features 40 of the structural stator core 32 via the bolted connection of the second housing 22 to the structural stator core 32. The structural stator core 32 transmits the internal load caused by the one or more second bearing assembly radial loads to the first housing 18, which transmits the internal load caused by the one or more second bearing assembly radial loads to the mounting base 48. Each of the one or more second bearing assembly radial loads is radially oriented relative to the output shaft rotational axis 26. The first housing 18 includes one or more motor mounting features 50, which are configured for mounting the electric motor 10 to the mounting base 48.

[0031] The electric motor 10 includes stator attachment bolts 42 for fastening the first housing 18 and the second housing 22 to the stator core 32. The stator-to-housing attachment feature 40 includes a stator-to-housing attachment fastener hole. The first housing-to-stator attachment feature 28 includes a first housing-to-stator attachment fastener hole. The second housing-to-stator attachment feature 30 includes a second housing-to-stator attachment fastener hole. Each of the stator attachment bolts 42 extends through a corresponding one of the first housing-to-stator attachment fastener holes, a corresponding one of the second housing-to-stator attachment fastener holes, and a corresponding one of the stator-to-housing attachment fastener holes.

[0032] The electric motor 10 includes cooling fins 44 attached to the outer circumferential surface of the stator back iron 36. The cooling fins 44 may be thermally coupled to the stator back iron 36 using any suitable method. For example, the cooling fins 44 may be bonded to the outer circumferential surface of the stator back iron 36 via a suitable thermally conductive adhesive.

[0033] The stator assembly 12 is operable to generate a magnetic field that rotates the rotor 16 to rotate the output shaft 14 about the output shaft rotation axis 26. The rotor 16 may have any suitable configuration for interacting with the magnetic field generated by the coils 34 of the stator assembly 12. For example, in some embodiments, the rotor 16 includes permanent magnets that interact with the magnetic field to drive rotation of the rotor 16 to rotate the output shaft 14 about the output shaft rotation axis 26.

[0034] The stator core 32 may have any suitable construction. For example, in many embodiments, the stator back iron 36, stator teeth 38, and stator-to-casing attachment features 40 are integrally formed from a suitable magnetically permeable material.

[0035] The electric motor 10 may be configured for use in any suitable application. For example, the output shaft 14 may be drivingly coupled to a lift fan 46 of an aircraft.

[0036] Figure 42 is a simplified block diagram of a method 200 for supporting an output shaft of an electric motor according to an embodiment, wherein a stator assembly forms part of a support structure for the output shaft. The method 200 includes: (a) supporting the output shaft using a first bearing assembly and a second bearing assembly offset from the first bearing assembly along a rotational axis of the output shaft (act 202), (b) supporting the first bearing assembly via a first housing to which the first bearing assembly is coupled (act 204), (c) supporting the first housing via a mounting base via attachment of the first housing to the mounting base (act 206), (d) supporting the second bearing assembly via a second housing to which the second bearing assembly is coupled, wherein the second housing is offset from the first housing along the rotational axis of the output shaft (act 208), (e) supporting the stator assembly by the first housing via attachment of a first end of the stator assembly to the first housing (act 210), and (f) supporting the second housing by the stator assembly via attachment of the second housing to a second end of the stator assembly, wherein the second end of the stator assembly is opposite the first end of the stator assembly (act 212).

[0037] In many embodiments, method 200 includes transferring a load from the output shaft to the mounting base through the stator assembly. For example, in many embodiments, method 200 includes: transferring a first bearing assembly load from the output shaft to the mounting base through a first load path extending through the first bearing assembly and the first housing to the mounting base; and transferring a second bearing assembly load from the output shaft to the mounting base through a second load path extending through the second bearing assembly, the second housing, the stator assembly, and the first housing to the mounting base. In many embodiments of method 200, the second bearing assembly load is radially oriented relative to the axis of rotation of the output shaft, the first bearing assembly load includes a radial load component and a thrust load component, the radial load component is radially oriented relative to the axis of rotation of the output shaft, and the thrust load component is aligned with the axis of rotation of the output shaft.

[0038] Any appropriately configured electric motor may be used to practice the method 200 including the electric motor 10 described herein. For example, in some embodiments, the stator assembly includes a structural stator core member and a stator coil. In some embodiments, the structural stator core member includes a stator back iron, stator teeth, and a stator to housing attachment feature. The structural stator core member may be coupled to and between the first housing and the second housing via the stator to housing attachment feature of the structural stator core member.

[0039] The method 200 may be practiced via an electric motor employed in any suitable application. For example, the method 200 may be practiced via an electric motor employed in an aircraft. For example, the output shaft may be drivingly coupled to a lift fan of the aircraft.

[0040] Figure 5is a simplified block diagram of a method 300 for cooling an electric motor using cooling fins attached to a stator assembly of the electric motor according to an embodiment. The method 300 includes: (a) supporting a first bearing assembly for an output shaft of the electric motor via a first housing to which the first bearing assembly is coupled, (b) supporting a second bearing assembly for the output shaft via a second housing to which the second bearing assembly is coupled, (c) maintaining engagement between a first end of the stator assembly and the first housing via attachment of a first end of the stator assembly to the first housing, (d) maintaining engagement between a second end of the stator assembly and the second housing via attachment of a second end of the stator assembly to the second housing, (e) supporting cooling fins attached to the stator assembly such that the cooling fins are exposed to air that is not enclosed by the first housing, the second housing, and the stator assembly, and (f) cooling the electric motor by conducting heat from the stator assembly into the cooling fins.

[0041] Any appropriately constructed electric motor may be used to practice the method 300 including the electric motor 10 described herein. For example, in some embodiments, the stator assembly includes a structural stator core member and a stator coil. The structural stator core member may include a stator back iron, stator teeth, and a stator to housing attachment feature. The stator back iron may extend circumferentially around the axis of rotation of the output shaft. Each of the first housing and the second housing may be coupled to the stator core via the stator to housing attachment feature of the structural stator core member and the corresponding housing to stator attachment feature of the first housing and the second housing. The cooling fins may be thermally coupled to the outer circumferential surface of the stator back iron. For example, the cooling fins may be thermally coupled to the outer circumferential surface of the stator back iron via a thermally conductive adhesive.

[0042] The electric motor 10 may be employed in any suitable application such as, for example, cars, trucks, and particularly in aircraft given the reduced weight of the electric motor 10 due to the weight savings provided by using the structural stator core 32. For example, Figure 6An example electric aircraft 400 is shown that may include one or more of the electric motors 10 according to an embodiment. The electric aircraft 400 includes a fuselage (body) 402 and wings 404. A group of three underwing pylons 406 are provided under each wing. Each pylon 406 has two lift fans 408 mounted thereon, one in front of the wing and one behind the wing. One or more batteries (not shown) and / or an onboard generator (e.g., a solar panel) may be used to power the electric motor 10 to drive the lift fans 408 and / or charge / recharge the onboard batteries. A propeller 410 is mounted on the fuselage 402 and is configured to propel the aircraft through the air in a forward (e.g., x-axis) direction. The propeller 410 is positioned between a pair of tail booms 412 that extend rearward and are connected at their rear ends by a tail structure on which aerodynamic control surfaces including an elevator 416 and a rudder 418 are mounted. Additional control surfaces include ailerons 414 mounted on the trailing edge of wing 404. Each of lift fan 408, propeller 410, ailerons 414, elevator 416, and rudder 418 may be driven by any suitable associated drive mechanism, which may include electric motor 10.

[0043] Example Embodiments

[0044] In one or more embodiments of the present disclosure, an electric motor includes an output shaft, a rotor, a first housing, a first bearing assembly, a second housing, a second bearing assembly, and a stator assembly. The output shaft has an output shaft rotation axis. The rotor is coupled to the output shaft. The first housing includes a first housing-to-stator attachment feature. The first bearing assembly is coupled to the first housing and docks with a first section of the output shaft. The second housing includes a second housing-to-stator attachment feature. The second bearing assembly is coupled to the second housing and docks with a second section of the output shaft. The stator assembly includes a stator core and a stator coil. The stator core includes a stator back iron, stator teeth, and a stator-to-housing attachment feature. The second housing is coupled to the first housing by the stator core via the second housing-to-stator attachment feature, the first housing-to-stator attachment feature, and the stator-to-housing attachment feature. The stator back iron extends circumferentially around the output shaft rotation axis and is configured to react one or more interface forces applied to the second bearing assembly by the second section of the output shaft to the first housing. Each of the stator teeth extends radially inward from the stator back iron toward the output shaft rotation axis. Each of the stator coils extends circumferentially around a corresponding one of the stator teeth. Optionally, the first bearing assembly may be configured to react one or more first bearing assembly radial loads from a first section of the output shaft into the first housing, each of the one or more first bearing assembly radial loads may be radially oriented relative to the output shaft rotation axis, the first bearing assembly may be configured to react a thrust load from the output shaft into the first housing, and the thrust load may be aligned with the output shaft rotation axis. Optionally, the second bearing assembly may be configured to react one or more second bearing assembly radial loads from a second section of the output shaft into the second housing, and each of the one or more second bearing assembly radial loads may be radially oriented relative to the output shaft rotation axis. Optionally, the first housing may include one or more motor mounting features configured to mount the electric motor to a mounting base. Optionally, the electric motor may further include stator attachment bolts, the stator to housing attachment feature may include stator to housing attachment fastener holes, the first housing to stator attachment feature may include a first housing to stator attachment fastener hole, the second housing to stator attachment feature may include a second housing to stator attachment fastener hole, and each of the stator attachment bolts may extend through a corresponding one of the first housing to stator attachment fastener holes, a corresponding one of the second housing to stator attachment fastener holes, and a corresponding one of the stator to housing attachment fastener holes. Optionally, the electric motor may further include cooling fins attached to the outer circumferential surface of the stator back iron. Optionally, the cooling fins may be bonded to the outer circumferential surface via a thermally conductive adhesive. Optionally, the rotor may include permanent magnets. Optionally, the stator back iron, the stator teeth, and the stator to housing attachment feature may be formed of a magnetically permeable material.

[0045] In one or more embodiments of the present disclosure, an aircraft may include any embodiment of the electric motor described herein. Optionally, the output shaft is drivingly coupled to a lift fan of the aircraft.

[0046] In one or more embodiments of the present disclosure, a method for supporting an output shaft of an electric motor includes: (a) supporting the output shaft using a first bearing assembly and a second bearing assembly offset from the first bearing assembly along a rotational axis of the output shaft, (b) supporting the first bearing assembly via a first housing connected to the first bearing assembly, (c) supporting the first housing via a mounting base via attachment of the first housing to a mounting base, (d) supporting the second bearing assembly via a second housing connected to the second bearing assembly, wherein the second housing is offset from the first housing along the rotational axis of the output shaft, (e) supporting the stator assembly by the first housing via attachment of a first end of the stator assembly to the first housing, and (f) supporting the second housing by the stator assembly via attachment of the second housing to a second end of the stator assembly, wherein the second end of the stator assembly is opposite to the first end of the stator assembly. Optionally, the method may further include: transmitting a first bearing assembly load from the output shaft to the mounting base through a first load path extending through the first bearing assembly and the first housing to the mounting base; and transmitting a second bearing assembly load from the output shaft to the mounting base through a second load path extending through the second bearing assembly, the second housing, the stator assembly and the first housing to the mounting base. Optionally, the second bearing assembly load may be radially oriented relative to the axis of rotation of the output shaft, the first bearing assembly load may include a radial load component and a thrust load component, the radial load component may be radially oriented relative to the axis of rotation of the output shaft, and the thrust load component may be aligned with the axis of rotation of the output shaft. Optionally, the stator assembly may include a stator core and a stator coil, the stator core may include a stator back iron, stator teeth, and a stator to housing attachment feature, and the stator core may be coupled to and between the first housing and the second housing via the stator to housing attachment feature. Optionally, the output shaft may be drivingly coupled to a lift fan of the aircraft.

[0047] In one or more embodiments of the present disclosure, a method for cooling an electric motor includes: (a) supporting a first bearing assembly for an output shaft of the electric motor via a first housing coupled to the first bearing assembly, (b) supporting a second bearing assembly for the output shaft via a second housing coupled to the second bearing assembly, (c) maintaining engagement between a first end of the stator assembly and the first housing via attachment of a first end of the stator assembly to the first housing, (d) maintaining engagement between a second end of the stator assembly and the second housing via attachment of a second end of the stator assembly to the second housing, (e) supporting cooling fins attached to the stator assembly so that the cooling fins are exposed to air not enclosed by the first housing, the second housing, and the stator assembly, and (f) cooling the electric motor by conducting heat from the stator assembly into the cooling fins. Optionally, the stator assembly may include a stator core and a stator coil, the stator core may include a stator back iron, stator teeth, and a stator-to-housing attachment feature, the stator back iron may extend circumferentially around an axis of rotation of the output shaft, and each of the first housing and the second housing may be coupled to the stator core via the stator-to-housing attachment feature. Optionally, the cooling fins may be thermally coupled to the outer circumferential surface of the stator back iron. Optionally, the cooling fins may be thermally coupled to the outer circumferential surface of the stator back iron via a thermally conductive adhesive.

[0048] Other variations are within the spirit of the invention. Therefore, although the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments of the invention are shown in the drawings and have been described in detail above. However, it should be understood that there is no intention to limit the invention to the disclosed specific form or forms, but rather, it is intended to cover all modifications, alternative constructions and equivalents that fall within the spirit and scope of the invention as defined in the appended claims.

[0049] In the context of describing the present invention (especially in the context of the appended claims), the use of the terms "one" and "an" and "the" and similar indicators should be interpreted as covering both the singular and the plural, unless otherwise indicated herein or clearly contradictory to the context. Unless otherwise stated, the terms "include", "have", "include" and "contain" should be interpreted as open terms (i.e., meaning "including but not limited to"). The term "connection" should be understood as being partially or completely included, attached to or linked together, even if there is something in between. The enumeration of the range of values ​​herein is only intended to be used as a shorthand method for individually quoting each individual value falling within the range, unless otherwise indicated herein, and each individual value is incorporated into the specification, just as if individually enumerated herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradictory to the context in other aspects. The use of any and all examples or exemplary language (e.g., "such as") provided herein is only intended to better illustrate embodiments of the present invention, and is not to limit the scope of the present invention, unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0050] Preferred embodiments of the present invention are described herein, including the best mode known to the inventor for implementing the present invention. After reading the above description, variations of those preferred embodiments may become apparent to those of ordinary skill in the art. The inventor expects that the technician will appropriately adopt such variations, and the inventor hopes that the present invention will be implemented in a manner different from that specifically described herein. Therefore, the present invention includes all modifications and equivalents of the subject matter described in the appended claims as allowed by applicable law. In addition, any combination of the above-mentioned elements in all possible variations thereof is encompassed by the present invention, unless otherwise indicated herein or clearly contradictory to the context.

[0051] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

Claims

1. An electric motor comprising: an output shaft having an output shaft rotation axis; a rotor coupled to the output shaft; a first housing including a first housing-to-stator attachment feature; a first bearing assembly coupled to the first housing and interfaced with a first section of the output shaft; a second housing including a second housing to stator attachment feature; a second bearing assembly coupled to the second housing and interfaced with a second section of the output shaft; as well as A stator assembly comprising a stator core and stator coils, wherein the stator core comprises a stator back iron, stator teeth and a stator-to-housing attachment feature, wherein the second housing is coupled to the first housing by the stator core via the second housing-to-stator attachment feature, the first housing-to-stator attachment feature and the stator-to-housing attachment feature; wherein the stator back iron extends circumferentially around the output shaft rotation axis and is configured to react one or more interface forces applied to the second bearing assembly by the second section of the output shaft to the first housing, wherein each of the stator teeth extends radially inwardly from the stator back iron toward the output shaft rotation axis; and wherein each of the stator coils extends circumferentially around a corresponding one of the stator teeth.

2. The electric motor according to claim 1, wherein: the first bearing assembly being configured to react one or more first bearing assembly radial loads from the first section of the output shaft into the first housing; Each of the one or more first bearing assembly radial loads is radially oriented relative to the output shaft rotational axis; The first bearing assembly is configured to react thrust loads from the output shaft into the first housing; and The thrust load is aligned with the output shaft rotational axis.

3. The electric motor according to claim 2, wherein: the second bearing assembly being configured to react one or more second bearing assembly radial loads from the second section of the output shaft into the second housing; and Each of the one or more second bearing assembly radial loads is radially oriented relative to the output shaft axis of rotation.

4. The electric motor according to claim 3, wherein: The first housing includes one or more motor mounting features configured for mounting the electric motor to a mounting base.

5. The electric motor according to any one of claims 1 to 4, further comprising stator attachment bolts, and wherein: The stator-to-housing attachment features include stator-to-housing attachment fastener holes; The first housing-to-stator attachment feature includes a first housing-to-stator attachment fastener hole; The second housing-to-stator attachment feature comprises a second housing-to-stator attachment fastener hole; and Each of the stator attachment bolts extends through a respective one of the first housing-to-stator attachment fastener holes, a respective one of the second housing-to-stator attachment fastener holes, and a respective one of the stator-to-housing attachment fastener holes.

6. The electric motor according to any one of claims 1 to 4, further comprising cooling fins attached to an outer circumferential surface of the stator back iron.

7. The electric motor according to claim 6, wherein: The cooling fins are bonded to the outer circumferential surface via a thermally conductive adhesive.

8. The electric motor according to any one of claims 1 to 4, wherein: The rotor includes permanent magnets.

9. The electric motor according to any one of claims 1 to 4, wherein: The stator back iron, the stator teeth, and the stator-to-housing attachment features are formed of a magnetically permeable material.

10. An aircraft comprising an electric motor according to any one of claims 1 to 4.

11. The aircraft according to claim 10, wherein: The output shaft is drivingly coupled to a lift fan of the aircraft.

12. A method of supporting an output shaft of an electric motor, the method comprising: supporting the output shaft with a first bearing assembly and a second bearing assembly offset from the first bearing assembly along an axis of rotation of the output shaft; supporting the first bearing assembly via a first housing to which the first bearing assembly is coupled; supporting the first housing via the mounting base via attachment of the first housing to the mounting base; supporting the second bearing assembly via a second housing to which the second bearing assembly is coupled, wherein the second housing is offset from the first housing along the rotational axis of the output shaft; supporting a stator assembly by the first housing via attachment of a first end of the stator assembly to the first housing; and The second housing is supported by the stator assembly via attachment of the second housing to a second end of the stator assembly, wherein the second end of the stator assembly is opposite the first end of the stator assembly.

13. The method according to claim 12, further comprising: transferring a first bearing assembly load from the output shaft to the mounting base via a first load path extending through the first bearing assembly and the first housing to the mounting base; as well as A second bearing assembly load is transferred from the output shaft to the mounting base via a second load path extending through the second bearing assembly, the second housing, the stator assembly and the first housing to the mounting base.

14. The method according to claim 13, wherein: the second bearing assembly load being radially oriented relative to the axis of rotation of the output shaft; The first bearing assembly load includes a radial load component and a thrust load component; The radial load component is oriented radially relative to the axis of rotation of the output shaft; and The thrust load component is aligned with the rotational axis of the output shaft.

15. The method according to any one of claims 12 to 14, wherein: The stator assembly includes a stator core and a stator coil; The stator core includes a stator back iron, stator teeth, and stator-to-housing attachment features; and The stator core is coupled with and between the first and second housings via the stator-to-housing attachment features.

16. The method according to any one of claims 12 to 14, wherein: The output shaft is drivingly coupled to a lift fan of the aircraft.

17. A method of cooling an electric motor, the method comprising: supporting the first bearing assembly for an output shaft of the electric motor via a first housing coupled to the first bearing assembly; a second housing supporting the second bearing assembly for the output shaft via a second bearing assembly coupled thereto; maintaining engagement between the first end of the stator assembly and the first housing via attachment of the first end of the stator assembly to the first housing; maintaining engagement between a second end of the stator assembly and the second housing via attachment of the second end of the stator assembly to the second housing; supporting cooling fins attached to the stator assembly such that the cooling fins are exposed to air not enclosed by the first housing, the second housing, and the stator assembly; as well as The electric motor is cooled by conducting heat from the stator assembly into the cooling fins.

18. The method of claim 17, wherein: The stator assembly includes a stator core and a stator coil; wherein the stator core includes a stator back iron, stator teeth, and stator-to-housing attachment features; The stator back iron extends circumferentially around the axis of rotation of the output shaft; and Each of the first housing and the second housing is coupled to the stator core via the stator-to-housing attachment feature.

19. The method according to claim 18, wherein: The cooling fins are thermally coupled to an outer circumferential surface of the stator back iron.

20. The method according to claim 19, wherein: The cooling fins are thermally coupled to the outer circumferential surface of the stator back iron via a thermally conductive adhesive.

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