Structural stator core

Abstract

The electric motor and related method employ a stator assembly as part of a housing assembly that reacts output shaft loads to a mounting base. The 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. The structural stator core member extends circumferentially around the output shaft. The second housing is coupled to the first housing by a stator core.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 407,117, filed September 15, 2022, the disclosure of which is incorporated herein by reference. [Background technology]

[0002] An 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 wound around one or more magnetically permeable core members. A drive current is typically passed through the coils to generate a magnetic field that is used to drive rotation of the rotor, thereby driving rotation of the output shaft.

[0003] The use of electric motors is increasing significantly in many applications. For example, electric motors are increasingly being employed in vehicles such as automobiles and trucks. In recent years, electric motors have been increasingly employed in aircraft. In many vehicles, particularly aircraft, electric motors with improved power-to-weight ratios are of interest due to their beneficial impact on the efficiency and / or capacity of the vehicle. Summary of the Invention

[0004] The following presents a simplified summary of some embodiments of the invention in order to provide a basic understanding of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key / critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some embodiments of the invention in a simplified form as a prelude to the more detailed description that is presented later.

[0005] 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 mechanism, and the structural stator core is attached to two housing members between the two housing members via the stator-to-housing attachment mechanism. The structural stator core transfers loads between the two housing members. Employing a structural stator core as part of the housing assembly can reduce the overall weight of the electric motor. Additionally, the outer peripheral wall of the stator core can be exposed, allowing cooling fins to be attached directly to the structural stator core. Therefore, using a structural stator core as part of the housing assembly can reduce the weight of the electric motor and / or improve 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 mounting mechanism between the first housing and the stator. The first bearing assembly is coupled to the first housing and interfaces with a first section of the output shaft. The second housing includes a mounting mechanism between the second housing and the stator. The second bearing assembly is coupled to the second housing and interfaces 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 mounting mechanism between the stator and the housing. The second housing is coupled to the first housing by a stator core via a second housing-to-stator attachment mechanism, a first housing-to-stator attachment mechanism, and a stator-to-housing attachment mechanism. The stator back iron extends circumferentially about the output shaft rotation axis. The stator back iron is configured to react to the first housing one or more interface forces applied to the second bearing assembly by the second section of the output shaft. 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 respective one of the stator teeth.

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

[0008] In many embodiments of the electric motor, the stator core is attached between the first housing and the second housing. For example, in some embodiments, the electric motor includes stator mounting bolts, and the stator core is attached between the first housing and the second housing via the stator mounting bolts. The stator-to-housing attachment mechanism may include stator-to-housing attachment fastener holes. The first housing-to-stator attachment mechanism may include first housing-to-stator attachment fastener holes. The second housing-to-stator attachment mechanism may include second housing-to-stator attachment fastener holes. Each of the stator mounting bolts may extend 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.

[0009] In many embodiments of the electric motor, the stator core is attached to the first and second housings between the first and second housings, leaving the stator core 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 periphery of the stator back iron. The cooling fins may be attached to the outer periphery of the stator back iron using any suitable technique. For example, the cooling fins may be bonded to the outer periphery with 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 a permanent magnet.

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

[0012] The electric motors 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 powered 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 with a first bearing assembly and a second bearing assembly offset from the first bearing assembly along a rotational axis of the output shaft. The method further includes supporting the first bearing assembly by a first housing to which the first bearing assembly is coupled. The method further includes supporting the first housing by a mount base by attaching the first housing to the mount base. The method further includes supporting the second bearing assembly by 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 further includes supporting the stator assembly by the first housing by attaching a first end of the stator assembly to the first housing. The method further includes supporting the second housing by the stator assembly by attaching the second housing to a second end of the stator assembly, the second end of the stator assembly facing the first end of the stator assembly.

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

[0015] The stator assembly employed in the method for 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 mechanism. The stator core may be coupled to the first and second housings via the stator-to-housing attachment mechanism 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 assembly 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 by a first housing to which the first bearing assembly is coupled. The method further includes supporting a second bearing assembly for the output shaft by a second housing to which the second bearing assembly is coupled. The method further includes maintaining engagement between a first end of the stator assembly and the first housing by attaching the first end of the stator assembly to the first housing. The method further includes maintaining engagement between a second end of the stator assembly and the second housing by attaching the second end of the stator assembly to the second housing. The method further includes supporting cooling fins attached to the stator assembly such that the cooling fins are exposed to air not surrounded by the first housing, the second housing, and the stator assembly. The method further 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, the 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 mechanism. The stator back iron may extend circumferentially about the rotational axis of the output shaft. Each of the first and second housings may be coupled to the stator core via the stator-to-housing attachment mechanism. In some embodiments, the cooling fins are 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 by a thermally conductive adhesive.

[0019] For a more complete understanding of the nature and advantages of the present invention, reference should be made to the following detailed description and accompanying drawings. [Brief explanation of the drawings]

[0020] [Figure 1] 1 illustrates a partial cross-sectional view of an electric motor including a structural stator core member that forms a portion of a housing assembly of the electric motor, according to an embodiment. [Figure 2] 2 shows a schematic cross-sectional side view of the electric motor of FIG. 1. [Figure 3] 2 shows a partial top view of a stator assembly of the electric motor of FIG. 1; [Figure 4] FIG. 1 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 the support structure for the output shaft, according to an embodiment. [Figure 5] FIG. 1 is a simplified block diagram of a method for cooling an electric motor using cooling fins attached to a stator assembly of the electric motor, according to an embodiment. [Figure 6] 2 shows an electric aircraft including an electric motor according to the electric motor of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0021] In the following description, various embodiments of the present invention are described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that the present invention may be practiced without the specific details. Additionally, well-known features may be omitted or simplified so as not to obscure the described embodiments.

[0022] In many existing electric motors, the stator core is surrounded and supported by a housing made of a different material. For example, the housing is often made of aluminum, and the stator core is typically made of some suitable magnetically permeable iron alloy. Heat generated by many existing electric motors is typically transferred by conduction from the stator core into the housing and from the housing into cooling fins attached to the housing. The housing and stator core often have different thermal expansion rates, which may require the use of a thermal interface that can accommodate the different thermal expansion rates. However, the use of a thermal interface can reduce heat transfer, reduce motor cooling, and reduce motor performance.

[0023] Referring now to the drawings, in which like reference numerals refer to like features, FIG. 1 illustrates a partial cross-sectional view of an electric motor 10 according to an embodiment. FIG. 2 illustrates a side cross-sectional schematic view of the electric motor 10. FIG. 3 illustrates a partial top view of a stator assembly 12 of the electric motor 10. 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 to drive rotation of the output shaft 14. The first housing 18 includes a first housing-to-stator attachment mechanism 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 mechanism 30. A second bearing assembly 24 is coupled to the second housing 22 and interfaces with a second section of the output shaft 14 .

[0024] 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 mechanism 40. The stator back iron 36 extends circumferentially about the output shaft rotational 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 mechanism 30, the first housing-to-stator attachment mechanism 28, and the stator-to-housing attachment mechanism 40. One or more interface forces applied to the second bearing assembly 24 by the second section of the output shaft 14 are transferred to the first housing 18 by the stator back iron 36 and the stator-to-housing attachment mechanism 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 respective one of the stator teeth 38.

[0025] The stator core 32 forms part of a load path, and a load applied to the second bearing assembly 24 by the output shaft 14 is transmitted to the mount base 48 through part of the load path. 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 then transmits the one or more first bearing assembly radial loads received from the first bearing assembly 20 to the mount base 48. Each of the one or more first bearing assembly radial loads is directed radially relative to the output shaft axis of rotation 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 transmits the thrust load to the mount base 48. The thrust load is aligned with the output shaft axis of rotation 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, and the second housing 22 transfers the one or more second bearing assembly radial loads to the structural stator core 32 via the structural stator core's bolted connection to the structural stator core 32 via the second housing-to-stator attachment mechanism 30 and the stator-to-housing attachment mechanism 40. The structural stator core 32 transfers internal loads induced by the one or more second bearing assembly radial loads to the first housing 18, which transfers internal loads induced by the one or more second bearing assembly radial loads to the mount base 48. Each of the one or more second bearing assembly radial loads is directed radially relative to the output shaft rotation axis 26. The first housing 18 includes one or more motor mount mechanisms 50 configured to mount the electric motor 10 to the mount base 48.

[0026] The electric motor 10 includes stator mounting bolts 42, which are used to fasten the first housing 18 and the second housing 22 to the stator core 32. The stator-to-housing mounting mechanism 40 includes stator-to-housing mounting fastener holes. The first housing-to-stator mounting mechanism 28 includes first housing-to-stator mounting fastener holes. The second housing-to-stator mounting mechanism 30 includes second housing-to-stator mounting fastener holes. Each of the stator mounting bolts 42 extends through a respective one of the first housing-to-stator mounting fastener holes, a respective one of the second housing-to-stator mounting fastener holes, and a respective one of the stator-to-housing mounting fastener holes.

[0027] The motor 10 includes cooling fins 44 attached to the outer periphery of the stator back iron 36. The cooling fins 44 may be thermally coupled to the stator back iron 36 using any suitable technique. For example, the cooling fins 44 may be adhered to the outer periphery of the stator back iron 36 with a suitable thermally conductive adhesive.

[0028] Stator assembly 12 is operable to generate a magnetic field that rotates rotor 16 and causes output shaft 14 to rotate about output shaft axis of rotation 26. Rotor 16 may have any suitable configuration for interacting with the magnetic field generated by coils 34 of stator assembly 12. For example, in some embodiments, rotor 16 includes permanent magnets that interact with the magnetic field to drive rotation of rotor 16 and cause output shaft 14 to rotate about output shaft axis of rotation 26.

[0029] The stator core 32 may have any suitable configuration. For example, in many embodiments, the stator back irons 36, stator teeth 38, and stator-to-housing attachment mechanism 40 are integrally formed from a suitable magnetically permeable material.

[0030] 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.

[0031] 4 is a simplified block diagram of a method 200 for supporting an output shaft of an electric motor, in which a stator assembly forms part of a support structure for the output shaft, according to an embodiment. Method 200 includes (a) 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 (operation 202), (b) supporting the first bearing assembly by a first housing to which the first bearing assembly is coupled (operation 204), (c) supporting the first housing by a mount base by attaching the first housing to the mount base (operation 206), and (d) supporting the second bearing assembly by a second housing to which the second bearing assembly is coupled. (e) supporting the stator assembly by the first housing by attaching a first end of the stator assembly to the first housing (operation 210); and (f) supporting the second housing by the stator assembly by attaching the second housing to a second end of the stator assembly, wherein the second end of the stator assembly faces the first end of the stator assembly (operation 212).

[0032] In many embodiments, method 200 includes transferring a load from the output shaft to the mount base through a stator assembly. For example, in many embodiments, method 200 includes transferring a first bearing assembly load from the output shaft to the mount base through a first load path extending through a first bearing assembly and a first housing to the mount base, and transferring a second bearing assembly load from the output shaft to the mount base through a second load path extending through a second bearing assembly, a second housing, the stator assembly, and the first housing to the mount base. In many embodiments of method 200, the second bearing assembly load is directed radially relative to the axis of rotation of the output shaft, and the first bearing assembly load includes a radial load component and a thrust load component, where the radial load component is directed radially 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.

[0033] Any suitably configured electric motor, including electric motor 10 described herein, can be used to implement method 200. For example, in some embodiments, a stator assembly includes a structural stator core member and a stator coil. In some embodiments, the structural stator core member includes stator back irons, stator teeth, and a stator-to-housing attachment mechanism. The structural stator core member can be coupled to the first and second housings via the stator-to-housing attachment mechanism of the structural stator core member.

[0034] Method 200 may be performed by an electric motor employed in any suitable application. For example, method 200 may be performed by an electric motor employed in an aircraft. The output shaft may be drivingly coupled to, for example, a lift fan of the aircraft.

[0035] 5 is 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. Method 300 includes: (a) supporting a first bearing assembly for an output shaft of the electric motor by a first housing to which the first bearing assembly is coupled; (b) supporting a second bearing assembly for the output shaft by 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 by attaching the 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 by attaching the 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 not surrounded 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.

[0036] Any suitably configured electric motor, including the electric motor 10 described herein, can be used to implement method 300. For example, in some embodiments, a stator assembly includes a structural stator core member and a stator coil. The structural stator core member can include a stator back iron, stator teeth, and a stator-to-housing attachment mechanism. The stator back iron can extend circumferentially about the rotational axis of the output shaft. Each of the first and second housings can be coupled to the stator core via the stator-to-housing attachment mechanism of the structural stator core member and the corresponding housing-to-stator attachment mechanism of the first and second housings. Cooling fins can be thermally coupled to the outer circumferential surface of the stator back iron. For example, the cooling fins can be thermally coupled to the outer circumferential surface of the stator back iron by a thermally conductive adhesive.

[0037] The electric motor 10 may be employed in any suitable application, such as, for example, automobiles, trucks, and especially aircraft, given the reduced weight of the electric motor 10 resulting from the weight savings provided by the use of the structural stator core 32. For example, FIG. 6 illustrates an exemplary electric aircraft 400 that may include one or more of the electric motors 10, according to embodiments. The electric aircraft 400 includes a fuselage 402 and wings 404. Beneath each wing is a set of three underwing pylons 406. Each pylon 406 has two lift fans 408 mounted thereon, one forward and one aft of the wing. One or more batteries (not shown) and / or onboard generators (e.g., solar panels) 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 configured to push the aircraft through the air in a forward (e.g., x-axis) direction. The propellers 410 are positioned between a pair of aft-extending booms 412 joined at the aft end by a tail structure, and aerodynamic control surfaces including elevators 416 and rudder 418 are mounted on the booms 412. Additional control surfaces include ailerons 414 mounted on the trailing edges of the wings 404. Each of the lift fans 408, propellers 410, ailerons 414, elevators 416, and rudder 418 may be driven by any suitable associated drive mechanism, which may include electric motors 10.

[0038] Illustrative Embodiments

[0039] 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 mechanism. The first bearing assembly is coupled to the first housing and interfaces with a first section of the output shaft. The second housing includes a second housing-to-stator attachment mechanism. The second bearing assembly is coupled to the second housing and interfaces 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 mechanism. The second housing is coupled to the first housing by the stator core via the second housing-to-stator attachment mechanism, the first housing-to-stator attachment mechanism, and the stator-to-housing attachment mechanism. The stator back iron extends circumferentially about the output shaft rotation axis and is configured to react to the first housing one or more interface forces applied to the second bearing assembly by the second section of the output shaft. 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 respective one of the stator teeth. Optionally, the first bearing assembly may be 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 may be oriented radially relative to the output shaft rotation axis, and the first bearing assembly may be configured to react a thrust load from the output shaft into the first housing, the thrust loads 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 the second section of the output shaft into the second housing, and each of the one or more second bearing assembly radial loads may be directed radially relative to the output shaft axis of rotation. Optionally, the first housing may include one or more motor mount mechanisms configured to mount the electric motor to the mount base. Optionally, the electric motor may further include stator mounting bolts, the stator-to-housing mounting mechanism may include stator-to-housing mounting fastener holes, the first housing-to-stator mounting mechanism may include first housing-to-stator mounting fastener holes, the second housing-to-stator mounting mechanism may include second housing-to-stator mounting fastener holes, and each of the stator mounting bolts may extend through a respective one of the first housing-to-stator mounting fastener holes, a respective one of the second housing-to-stator mounting fastener holes, and a respective one of the stator-to-housing mounting fastener holes. Optionally, the electric motor may further include cooling fins attached to an outer circumferential surface of the stator back iron. Optionally, the cooling fins may be adhered to the outer circumferential surface by a thermally conductive adhesive. Optionally, the rotor may include a permanent magnet. Optionally, the stator back iron, the stator teeth, and the stator-to-housing mounting mechanism may be formed of a magnetically permeable material.

[0040] In one or more embodiments of the present disclosure, an aircraft may include any of the electric motor embodiments described herein. Optionally, the output shaft is drivingly coupled to a lift fan of the aircraft.

[0041] In one or more embodiments of the present disclosure, a method of 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 by a first housing to which the first bearing assembly is coupled; (c) supporting the first housing by a mount base by attaching the first housing to a mount base; (d) supporting the second bearing assembly by 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; (e) supporting the stator assembly by the first housing by attaching a first end of the stator assembly to the first housing; and (f) supporting the second housing by the stator assembly by attaching the second housing to a second end of the stator assembly, wherein the second end of the stator assembly faces the first end of the stator assembly. Optionally, the method may further include transferring a first bearing assembly load from the output shaft to the mount base through a first load path extending through the first bearing assembly and the first housing to the mount base, and transferring a second bearing assembly load from the output shaft to the mount base through a second load path extending through the second bearing assembly, the second housing, the stator assembly, and the first housing to the mount base. Optionally, the second bearing assembly load may be directed radially with respect to the axis of rotation of the output shaft, and the first bearing assembly load may include a radial load component and a thrust load component, where the radial load component may be directed radially with respect 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 mechanism, and the stator core may be coupled to the first housing and the second housing between the first housing and the second housing via the stator-to-housing attachment mechanism. Optionally, the output shaft may be drivingly coupled to a lift fan of the aircraft.

[0042] In one or more embodiments of the present disclosure, a method of cooling an electric motor includes: (a) supporting a first bearing assembly for an output shaft of the electric motor by a first housing to which the first bearing assembly is coupled; (b) supporting a second bearing assembly for the output shaft by a second housing to which the second bearing assembly is coupled; (c) maintaining engagement between a first end of a stator assembly and the first housing by attaching the 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 by attaching the 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 not surrounded 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 mechanism, the stator back iron may extend circumferentially about the rotational axis of the output shaft, and each of the first and second housings may be coupled to the stator core via the stator-to-housing attachment mechanism. Optionally, cooling fins may be thermally coupled to an outer peripheral surface of the stator back iron. Optionally, the cooling fins may be thermally coupled to the outer peripheral surface of the stator back iron by a thermally conductive adhesive.

[0043] Other variations are within the spirit and scope of the invention. Accordingly, while the invention is susceptible to various modifications and alternative constructions, specific illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the particular forms or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined by the appended claims.

[0044] The use of the terms "a," "an," and "the" and similar referents in the context of describing the present invention (particularly in the context of the claims that follow) should be construed to cover both the singular and the plural unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "comprising" should be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise indicated. The term "coupled" should be construed as partially or wholly contained within, attached to, or joined together, even if there is intervening material. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually listed herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or unless otherwise clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended merely to better clarify embodiments of the invention and does not pose a limitation on the scope of the invention unless specifically claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0045] Preferred embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect skilled artisans to adopt such variations as they see fit, and the inventors intend the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, unless otherwise indicated herein or otherwise clearly contradicted by context, the invention includes any combination of the above-described elements in all possible variations thereof.

[0046] All references cited in this specification, including publications, patent applications, and patents, are herein incorporated by reference to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and was set forth in its entirety herein.

Claims

1. an output shaft having an output shaft rotation axis; a rotor coupled to the output shaft; a first housing having an attachment mechanism between the first housing and the stator; a first bearing assembly coupled to the first housing and interfaced with a first section of the output shaft; a second housing having a mounting mechanism for the second housing and the stator; a second bearing assembly coupled to the second housing and interfaced with a second section of the output shaft; a stator assembly including a stator core and a stator coil, wherein the stator core includes a stator back iron, stator teeth, and a stator-to-housing attachment mechanism; the second housing is coupled to the first housing by the stator core via the second housing-to-stator attachment mechanism, the first housing-to-stator attachment mechanism, and the stator-to-housing attachment mechanism; the stator back iron extends circumferentially about the output shaft axis of rotation and is configured to react to the first housing one or more interface forces applied to the second bearing assembly by the second section of the output shaft; each of the stator teeth extends radially inward from the stator back iron toward the output shaft axis of rotation; and each of the stator coils extends circumferentially around a respective one of the stator teeth. Electric motor.

2. the first bearing assembly is configured to react one or more 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 directed radially relative to the output shaft axis of rotation; the first bearing assembly is configured to react a thrust load from the output shaft into the first housing; the thrust load is aligned with the output shaft axis of rotation; 2. The electric motor according to claim 1.

3. the second bearing assembly is configured to react one or more second bearing assembly radial loads from the second section of the output shaft into the second housing; each of the one or more second bearing assembly radial loads is directed radially relative to the output shaft rotational axis; 3. The electric motor according to claim 2.

4. The electric motor of claim 3 , wherein the first housing includes one or more motor mounting mechanisms configured to mount the electric motor to a mounting base.

5. Further provided with a stator mounting bolt, the stator-to-housing attachment mechanism includes stator-to-housing attachment fastener holes; the attachment mechanism between the first housing and the stator includes first housing and stator attachment fastener holes; the attachment mechanism between the second housing and the stator includes second housing and stator attachment fastener holes; each of the stator mounting bolts extending through a respective one of the first housing-to-stator mounting fastener holes, a respective one of the second housing-to-stator mounting fastener holes, and a respective one of the stator-to-housing mounting fastener holes; 5. An electric motor according to any one of claims 1 to 4.

6. The electric motor of claim 1 , further comprising cooling fins attached to an outer peripheral surface of the stator back iron.

7. 7. The electric motor according to claim 6, wherein the cooling fins are adhered to the outer peripheral surface by a thermally conductive adhesive.

8. 5. An electric motor according to claim 1, wherein the rotor comprises a permanent magnet.

9. 5. The electric motor of claim 1, wherein the stator back irons, the stator teeth, and the stator-to-housing attachment mechanism are formed from a magnetically permeable material.

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

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

12. 1. A method of supporting an output shaft of an electric motor, said 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 by a first housing to which the first bearing assembly is coupled; supporting the first housing by the mount base by attaching the first housing to the mount base; supporting the second bearing assembly by a second housing to which the second bearing assembly is coupled, the second housing being offset from the first housing along the axis of rotation of the output shaft; supporting the stator assembly by the first housing by attaching a first end of the stator assembly to the first housing; supporting the second housing by the stator assembly by attachment of a second end of the second housing to the stator assembly, the second end of the stator assembly opposing the first end of the stator assembly; A method comprising:

13. transferring a first bearing assembly load from the output shaft to the mount base through a first load path extending through the first bearing assembly and the first housing to the mount base; transferring a second bearing assembly load from the output shaft to the mount base through a second load path extending through the second bearing assembly, the second housing, the stator assembly, and the first housing to the mount base; The method of claim 12 further comprising:

14. the second bearing assembly load is oriented radially 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 directed radially relative to the axis of rotation of the output shaft; the thrust load component is aligned with the axis of rotation of the output shaft; The method of claim 13.

15. 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 mechanism; the stator core is coupled to the first housing and the second housing via a mounting mechanism between the stator and the housing, 15. The method according to any one of claims 12 to 14.

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

17. 1. A method of cooling an electric motor, the method comprising: supporting a first bearing assembly for an output shaft of the electric motor by a first housing to which the first bearing assembly is coupled; supporting a second bearing assembly for the output shaft by a second housing to which the second bearing assembly is coupled; maintaining engagement between a first end of a stator assembly and the first housing by mounting the first end of the stator assembly to the first housing; maintaining engagement between the second end of the stator assembly and the second housing by mounting 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 surrounded by the first housing, the second housing, and the stator assembly; cooling the electric motor by conducting heat from the stator assembly into the cooling fins; A method comprising:

18. 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 mechanism; the stator back iron extends circumferentially about the axis of rotation of the output shaft; Each of the first housing and the second housing is coupled to the stator core via an attachment mechanism between the stator and the housing.

18. The method of claim 17.

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

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

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