Rotor assembly and system and method for manufacturing the same

Abstract

This invention relates to improvements to rotor assemblies and methods for assembling them for electric engines that may be used in aircraft and other types of vehicles driven by electric propulsion systems. [Solution] The rotor assembly 1100 includes a sleeve 1104, a rotor hub 1106, and a plurality of tapered magnets 1102 arranged along the circumference of the inner diameter of the sleeve. The plurality of tapered magnets are configured to abut each other. The plurality of tapered magnets includes a first set of tapered magnets and a second set of tapered magnets. The axial insertion of the first set of tapered magnets into the second set of tapered magnets is configured to increase the diameter of the sleeve. The rotor hub is configured to hold at least one of the plurality of tapered magnets or the sleeve.

Description

Technical Field

[0001] Cross - Reference to Related Applications This disclosure claims the priority and benefit of U.S. Application No. 18 / 316,931, filed May 12, 2023, titled "ROTOR ASSEMBLY INCLUDING TAPERED MAGNETS WITHIN A RETAINING SLEEVE AND A METHOD FOR ASSEMBLING THE SAME" (Attorney Docket No. 16163.0033 - 00000), which claims the priority and benefit of U.S. Provisional Application No. 63 / 378,536, filed October 6, 2022, titled "Tilt Rotor Systems and Methods for eVTOL Aircraft", and U.S. Provisional Application No. 63 / 378,680 (Attorney Docket No. 16163.6002 - 00000), filed October 7, 2022, titled "Systems and Methods for Improved Propulsion Systems for eVTOL Aircraft". The entire content of the above applications is incorporated herein in their entirety for all purposes.

[0002] This disclosure generally relates to the field of powered aerial vehicles. More specifically, without limitation, this disclosure relates to technological innovations in aircraft driven by electric propulsion systems. Certain aspects of the disclosure generally relate to improvements to rotor assemblies for electric engines and methods of assembling them that can be used in aircraft and other types of vehicles driven by electric propulsion systems.

Summary of the Invention

[0003] This disclosure primarily deals with systems, components, and technologies for use in non-conventional aircraft driven by electric propulsion systems. For example, the tiltrotor aircraft of this disclosure may be configured for frequent (e.g., more than 50 flights per operating day) short flights (e.g., less than 100 miles per flight) in and out of densely populated areas. The aircraft may be configured to carry 4 to 6 passengers or commuters who expect a comfortable experience with low noise and low vibration. Accordingly, the components of the aircraft may be configured and designed to withstand frequent use without wear and tear and to generate less heat and vibration, and it may be desirable that the aircraft include mechanisms for effectively controlling and managing the heat or vibration generated by the components. Furthermore, some of these aircraft may be intended to operate in close proximity to each other over congested metropolitan areas. Accordingly, their components may be configured and designed to generate low levels of noise inside and outside the aircraft and to have various safety and backup mechanisms. For example, for safety reasons, it may be desirable for an aircraft to be propelled by a distributed propulsion system, avoid the risk of a single point of failure, and be able to perform conventional takeoffs and landings on runways. Furthermore, it may be desirable for an aircraft to be able to safely take off and land vertically from and into relatively small or limited spaces (e.g., vertiports, parking lots, or private roads) compared to conventional airport runways, while transporting several passengers or commuters along with their baggage. These usage requirements may impose design constraints on the size, weight, and operational efficiency (e.g., drag, energy use) of the aircraft, and may affect the design and configuration of aircraft components.

[0004] The disclosed embodiments provide novel and improved aircraft component configurations not found in conventional aircraft and / or specific design criteria for components that differ from those of conventional aircraft. Such alternative configurations and design criteria, coupled with an address of the shortcomings and challenges of conventional components, have resulted in the embodiments disclosed herein for various configurations and designs of components for aircraft driven by electric propulsion systems. The disclosed embodiments may also provide improvements for hybrid aircraft (e.g., aircraft including battery packs and / or fuel cells such as hydrogen fuel cells, or gas-electric hybrid aircraft).

[0005] In some embodiments, an aircraft powered by the electric propulsion system of the Disclosure may be designed to be capable of both vertical and conventional takeoffs and landings, with a distributed electric propulsion system that enables vertical, horizontal, and lateral flight, and transitions. Thrust may be generated by supplying high-voltage power to multiple electric engines of the distributed electric propulsion system, which may include components necessary to convert the high-voltage power into mechanical shaft power to rotate the propellers. Embodiments disclosed herein may involve optimizing the energy density of the electric propulsion system. Embodiments may include electric engines connected to an onboard power source, which may include devices capable of storing energy, such as batteries or capacitors, and may include one or more systems for utilizing or generating electricity, such as fuel-powered generators or solar panel arrays. Some disclosed embodiments provide weight and space reduction of components within the aircraft to improve the efficiency and performance of the aircraft. Disclosed embodiments also improve safety in passenger transport by using new and improved safety protocols and system redundancy in the event of failure to minimize any single point of failure in the aircraft propulsion system. Some disclosed embodiments also provide new and improved approaches that meet and exceed aviation and transport laws and regulations. For example, the Federal Aviation Administration enforces federal laws and regulations that require safety components, such as fire barriers adjacent to engines using quantities of oil or other flammable materials exceeding a threshold. A fire barrier may include engine or aircraft components designed, constructed, or installed primarily to prevent hazardous quantities of air, fluid, or flame from passing around or through the fire barrier and / or to protect against corrosion. In some embodiments, a fire barrier may include components separated from additional components, as described herein.In some embodiments, a fire barrier may include a firewall, fire barrier, fireproof barrier, flame-retardant barrier, or any other barrier that can ensure that hazardous amounts of air, fluid, or flame cannot pass around or through the barrier and / or protect against corrosion. For example, a fuselage may be constructed to prevent hazardous amounts of air, fluid, or flame from passing around or through the fire barrier and / or protect against corrosion, but the fuselage may not be considered a fire barrier because its primary purpose is not a fire barrier. In some embodiments, an electric propulsion system may use oil below a threshold level to provide efficient and effective lubrication and cooling, thereby resulting in an aircraft that does not require an engine fire barrier, maximizing performance and efficiency while saving aircraft weight.

[0006] In some embodiments, a distributed electric propulsion system may include twelve electric engines that can be mounted on forward and aft booms of the aircraft's wings. A subset of the electric engines, such as those mounted forward of the wings, may be tiltable during flight between a horizontal position (e.g., generating forward thrust for cruising) and a vertical position (e.g., generating vertical lift for takeoff, landing, and hovering). The propellers of the forward electric engines may rotate clockwise or counterclockwise. The propellers may be reversed relative to adjacent propellers. The aft electric engines may be fixed in a vertical position (e.g., generating vertical lift). The propellers associated with the aft electric engines may also rotate clockwise or counterclockwise. In some embodiments, differences in rotation direction may be achieved using engine rotation directions. In other embodiments, the engines may all rotate in the same direction, and gearing may be used to achieve different propeller rotation directions.

[0007] In some embodiments, an aircraft may have a number of electric engines in various combinations of forward and rear engine configurations. For example, an aircraft may have six forward electric engines and six rear electric engines, four forward electric engines and four rear electric engines, or any other combination of forward and rear electric engines, including embodiments with different numbers of forward and rear electric engines.

[0008] In some embodiments, for vertical take-off and landing (VTOL) missions, forward and rear electric engines may provide vertical thrust during take-off and landing. During the forward flight phase, the forward electric engine may provide horizontal thrust, while the rear electric engine's propellers may be retracted to a fixed position to minimize drag. The rear electric engine may be actively retracted while position monitoring is performed. Transitions from vertical to horizontal flight and vice versa may be achieved via a tilt propeller subsystem. The tilt propeller subsystem may redirect thrust, primarily vertical, during vertical flight mode to the horizontal or nearly horizontal direction during the forward flight cruising phase. A variable pitch mechanism may change the collective angle of the forward electric engine's propeller hub assembly blades for operation during the hovering, transition, and cruising phases.

[0009] In some embodiments, in conventional take-off and landing (CTOL) missions, the forward electric engines may provide horizontal thrust for fixed-wing take-off, cruising, and landing, while the wings may provide vertical lift. In some embodiments, the rear electric engines may not be used to generate thrust during CTOL missions, and the rear propellers may be retracted into a fixed position. In other embodiments, the rear electric engines may be used at reduced power to shorten the length of CTOL take-off or landing.

[0010] The disclosed embodiments provide a rotor assembly comprising a sleeve, a rotor hub, and a plurality of tapered magnets arranged along the circumference of the inner diameter of the sleeve. The plurality of tapered magnets are configured to abut each other and include a first set of tapered magnets and a second set of tapered magnets. The axial insertion of the first set of tapered magnets relative to the second set of tapered magnets is configured to increase the diameter of the sleeve. The rotor hub is configured to hold at least one of the plurality of tapered magnets or the sleeve.

[0011] The sleeve may be configured to hold multiple tapered magnets. The sleeve may contain carbon fiber.

[0012] The rotor assembly may include a core. The core may include, for example, at least one notch for mating the core with a rotor hub. The rotor assembly may include a first rotor hub abutting a first side surface of the laminated core, and a second rotor hub abutting a second side surface of the core opposite to the first side surface. The rotor assembly may include at least one cavity disposed between a plurality of tapered magnets and the core, the at least one cavity configured to guide fluid for cooling the magnets among the plurality of tapered magnets. The core or at least one cavity may be configured to deliver fluid for direct cooling of the plurality of tapered magnets.

[0013] The disclosed embodiments also provide an electric propulsion system for a vertical take-off and landing (VTOL) aircraft. The electric propulsion system includes at least one electric engine that is mechanically connected directly or indirectly to the fuselage of the VTOL aircraft. The electric engine includes a gearbox assembly. The gearbox assembly includes a sun gear and an electric motor, the electric motor having a stator and rotor assembly. The rotor assembly includes a sleeve, a rotor hub and a plurality of tapered magnets arranged along the circumference of the inner diameter of the sleeve. The plurality of tapered magnets are configured to abut each other and include a first set of tapered magnets and a second set of tapered magnets. The axial insertion of the first set of tapered magnets relative to the second set of tapered magnets is configured to increase the diameter of the sleeve. The rotor hub is configured to hold at least one of the plurality of tapered magnets or the sleeve.

[0014] The sun gear can be mounted on the rotor hub. The gearbox may include bearings, the outer diameter of which is in contact with the inner diameter of the sun gear.

[0015] The sleeve may be configured to hold multiple tapered magnets. The sleeve may contain carbon fiber.

[0016] The rotor assembly may include a core. The core may include, for example, at least one notch for mating the core with a rotor hub. The rotor assembly may include a first rotor hub abutting against a first side surface of the core, and a second rotor hub abutting against a second side surface of the core opposite to the first core. The rotor assembly may include at least one cavity disposed between a plurality of tapered magnets and the core, the at least one cavity being configured to guide fluid for cooling the magnets among the plurality of tapered magnets. The core or at least one cavity may be configured to deliver fluid for direct cooling of the plurality of magnets.

[0017] The disclosed embodiments also provide a vertical take-off and landing (VTOL) aircraft including an electric propulsion system.

[0018] The disclosed embodiments further provide a method for assembling a rotor assembly. The method includes inserting a first plurality of tapered magnets and a second plurality of tapered magnets from opposite axial directions such that each of the second plurality of tapered magnets is positioned between adjacent pairs of the first plurality of tapered magnets. The first and second plurality of tapered magnets are arranged to form a magnetic ring that abuts against the inner surface of an expandable sleeve.

[0019] Inserting a first set of tapered magnets and a second set of tapered magnets may involve increasing the diameter of the expandable sleeve. The method may involve inserting a bearing into the sun gear and mounting the sun gear to at least one rotor hub. The method may involve balancing the rotor assembly. At least one rotor hub may hold at least one of a magnet ring or an expandable sleeve.

[0020] The disclosed embodiments also provide a method for manufacturing a rotor assembly for an electric engine. The method includes loading a first plurality of magnets into a magnet insertion tool, loading a second plurality of magnets into the magnet insertion tool, wherein the first plurality of magnets and the second plurality of magnets are shaped to form a magnet ring of a rotor assembly, and loading a sleeve into the magnet insertion tool. The method further includes performing a first insertion movement using the magnet insertion tool, wherein the first insertion movement involves moving one of the first plurality of magnets or the second plurality of magnets radially in the sleeve, performing a second insertion movement using the magnet insertion tool, wherein the second insertion movement involves moving one of the first plurality of magnets or the second plurality of magnets axially in the sleeve relative to the sleeve, and, between the first or second insertion movement, using the magnet insertion tool to radially expand the radius of the sleeve.

[0021] This method may include performing at least a portion of the first insertion movement and the second insertion movement simultaneously. One of the first or second plurality of magnets may remain stationary axially relative to the sleeve during the second insertion movement. This method may include moving both the first and second plurality of magnets radially during the first insertion movement.

[0022] The first insertion movement may involve expanding the sleeve by pressing the first set of magnets radially against the sleeve. The second insertion movement may involve sliding the second set of magnets so that they are axially aligned with both the first set of magnets and the sleeve. Expanding the radius of the sleeve may involve expanding the radius from a first radius to a second radius. The method may include contracting the radius of the sleeve from a second radius to a third radius. In some embodiments, the third radius is greater than the first radius and less than the second radius. The third radius may be at least 98% of the second radius.

[0023] The first and second sets of magnets may be tapered along their axial direction.

[0024] A first set of magnets may be supported on a first set of magnet keys of a magnet insertion tool. A second set of magnets may be supported on a second set of magnet keys of a magnet insertion tool. The method may include using an expansion mandrel of the magnet insertion tool to move the first set of magnets, the first set of magnet keys, the second set of magnets, and the second set of magnet keys radially during the first insertion movement.

[0025] The mandrel for expansion may include a first plurality of pushing bars configured to push a first plurality of magnetic keys, and a second plurality of pushing bars configured to push a second plurality of magnetic keys. The method may include sliding, by a magnet insertion tool, the first plurality of magnetic keys relative to the surface of the first plurality of pushing bars. The method may include sliding, by the magnet insertion tool, the second plurality of magnetic keys relative to the surface of the second plurality of pushing bars.

[0026] The mandrel for expansion may include a pushing bar guiding plate configured to guide the first plurality of pushing bars and the second plurality of pushing bars in the radial direction. The mandrel for expansion may include an alignment shaft configured to axially align the pushing bar guiding plate when the pushing bar guiding plate guides the first plurality of pushing bars and the second plurality of pushing bars in the radial direction.

[0027] The magnet insertion tool may include a first support plate configured to support the first plurality of magnetic keys, and a second support plate configured to support the second plurality of magnetic keys. The method may include moving the first plurality of magnetic keys radially relative to the first support plate and moving the second plurality of magnetic keys radially relative to the second support plate.

[0028] The method may include axially pressing the second support plate toward the first support plate between the first insertion movement and the second insertion movement.

[0029] The method may include that moving the first plurality of magnetic keys radially relative to the first support plate includes moving the first plurality of magnetic keys in a first plurality of slots in the first support plate, or moving the second plurality of magnetic keys radially relative to the second support plate includes moving the second plurality of magnetic keys in a second plurality of slots in the second support plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] [Figure 1] An illustration of a perspective view of an exemplary VTOL aircraft that conforms to the disclosed embodiments. [Figure 2] Another illustration of a perspective view of an exemplary VTOL aircraft of an alternative configuration that conforms to the embodiments of the present disclosure. [Figure 3] An illustration of a top view of an exemplary VTOL aircraft that conforms to the embodiments of the present disclosure. [Figure 4] A schematic diagram illustrating an exemplary propeller rotation of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 5] A schematic diagram illustrating an exemplary power connection in a VTOL aircraft that conforms to the disclosed embodiments. [Figure 6] A block diagram illustrating an exemplary architecture and design of an electric propulsion unit of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 7] A schematic diagram illustrating an exemplary tilt electric propulsion system of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 8A] An illustration of an exemplary tilt electric propulsion system of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 8B] An illustration of an exemplary tilt electric propulsion system of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 8C] An illustration of an exemplary tilt electric propulsion system of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 9] A schematic diagram illustrating an exemplary ascent electric propulsion system of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 10A] An illustration of an exemplary ascent electric propulsion system of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 10B] An illustration of an exemplary ascent electric propulsion system of a VTOL aircraft that conforms to the disclosed embodiments. [Figure 11] An illustration of a rotor assembly that conforms to the disclosed embodiments. [Figure 12A] This is an isometric view of the rotor assembly, consistent with the disclosed embodiment. [Figure 12B] This is an isometric view of the rotor assembly, consistent with the disclosed embodiment. [Figure 13A] This is an illustrative side view of a rotor assembly consistent with the disclosed embodiment. [Figure 13B] This is an illustrative side view of a rotor assembly consistent with the disclosed embodiment. [Figure 14A] This is an illustrative front view of an exemplary rotor assembly consistent with the disclosed embodiment. [Figure 14B] This is an illustrative partial front section view of a magnet assembly, consistent with the disclosed embodiment. [Figure 15] This is an illustrative top view of a laminated core, consistent with the disclosed embodiment. [Figure 16] This is an illustrative example of a rotor hub consistent with the disclosed embodiments. [Figure 17A] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 17B] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 17C] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 17D] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 18A] This is an illustrative example of the assembly process for a rotor assembly, consistent with the disclosed embodiments. [Figure 18B] This is an illustrative example of the assembly process for a rotor assembly, consistent with the disclosed embodiments. [Figure 18C] This is an illustrative example of the assembly process for a rotor assembly, consistent with the disclosed embodiments. [Figure 18D] This is an illustrative example of the assembly process for a rotor assembly, consistent with the disclosed embodiments. [Figure 18E]This is an illustrative example of the assembly process for a rotor assembly, consistent with the disclosed embodiments. [Figure 18F] This is an illustrative example of the assembly process for a rotor assembly, consistent with the disclosed embodiments. [Figure 19] This is an illustrative exploded view of a rotor assembly consistent with the disclosed embodiment. [Figure 20] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 21A] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 21B] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 22] This is an illustrative cross-sectional view of a rotor assembly consistent with the disclosed embodiment. [Figure 23A] This is an illustrative front view of a rotor assembly consistent with the disclosed embodiment. [Figure 23B] This is an illustrative front view of a rotor assembly consistent with the disclosed embodiment. [Figure 24A] Exemplary mandrels and mandrel components for manufacturing a rotor assembly consistent with embodiments of this disclosure are illustrated. [Figure 24B] Exemplary mandrels and mandrel components for manufacturing a rotor assembly consistent with embodiments of this disclosure are illustrated. [Figure 24C] Exemplary mandrels and mandrel components for manufacturing a rotor assembly consistent with embodiments of this disclosure are illustrated. [Figure 24D] Exemplary mandrels and mandrel components for manufacturing a rotor assembly consistent with embodiments of this disclosure are illustrated. [Figure 24E] Exemplary mandrels and mandrel components for manufacturing a rotor assembly consistent with embodiments of this disclosure are illustrated. [Figure 24F]Exemplary mandrels and mandrel components for manufacturing a rotor assembly consistent with embodiments of this disclosure are illustrated. [Figure 24G] Exemplary mandrels and mandrel components for manufacturing a rotor assembly consistent with embodiments of this disclosure are illustrated. [Figure 25A] A first diagram illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 25B] A first diagram illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 25C] A first diagram illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 25D] A first diagram illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 25E] A first diagram illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 25F] A first diagram illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 26A] An exemplary key for a magnet insertion tool, consistent with the embodiments of this disclosure, is illustrated. [Figure 26B] An exemplary key for a magnet insertion tool, consistent with the embodiments of this disclosure, is illustrated. [Figure 27A] A second figure illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 27B] A second figure illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 27C] A second figure illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 27D] A second figure illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 27E] A second figure illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 27F] A second figure illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 27G] A second figure illustrates an exemplary method for manufacturing a rotor assembly consistent with embodiments of the present disclosure. [Figure 28A] An illustrative cross-sectional view of an exemplary magnet insertion tool, consistent with the embodiments of this disclosure, is provided. [Figure 28B] An illustrative cross-sectional view of an exemplary magnet insertion tool, consistent with the embodiments of this disclosure, is provided. [Figure 29] A diagram illustrating a magnet insertion tool consistent with the embodiments of this disclosure is provided as an example. [Figure 30] A diagram illustrating a magnet insertion tool consistent with the embodiments of this disclosure is provided as an example. [Figure 31] An exemplary method for manufacturing a rotor assembly consistent with embodiments of this disclosure is illustrated. [Modes for carrying out the invention]

[0031] The disclosed embodiments provide systems, subsystems, and components for rotor assemblies, as well as methods for assembling or manufacturing them.

[0032] The disclosed embodiments provide systems, subsystems, and components for a new VTOL aircraft having various combinations of electric propulsion and cooling systems that maximize performance while minimizing weight.

[0033] In some embodiments, the electric propulsion systems described herein may generate thrust by supplying high-voltage (HV) power to an electric engine, which converts the HV power into mechanical shaft power used to rotate a propeller. The aircraft described herein may include a plurality of electric engines mounted forward and backward on the wings. The engines may be mounted directly on the wings or on one or more booms attached to the wings. The amount of thrust generated by each electric engine may be controlled by torque commands from a flight control system (FCS) provided via a digital communication interface to each electric engine. Embodiments may include forward electric engines whose orientation or inclination can be changed. Some embodiments include forward engines that can rotate clockwise (CW) or counterclockwise (CCW). The forward electric propulsion subsystem may consist of a multi-blade adjustable pitch propeller, as well as a variable pitch subsystem.

[0034] In some embodiments, the aircraft may include a rear electric engine or lifter, which can be of the clockwise (CW) or counterclockwise (CCW) type. Some embodiments may include a rear electric engine utilizing a multi-blade fixed-pitch propeller.

[0035] As described herein, the orientation and use of electric propulsion system components may change throughout the operation of the aircraft. In some embodiments, during vertical takeoff and landing, the forward propulsion system and the rear propulsion system may provide vertical thrust during takeoff and landing. During the flight phase when the aircraft is in forward flight mode, the forward propulsion system may provide horizontal thrust, while the propellers of the rear propulsion system may be retracted to a fixed position to minimize drag. The rear electric propulsion system may be actively retracted while monitoring its position. Some embodiments may include transitions from vertical to horizontal flight and vice versa. In some embodiments, the transition may be achieved via a tilt propeller system (TPS). The TPS redirects the thrust, which is primarily vertical during vertical flight mode, to primarily horizontal during forward flight mode. Some embodiments may include a variable pitch mechanism that can change the collective angle of the propeller blades of the forward propulsion system for operation during the hovering phase, cruising phase, and transition phase. Some embodiments may include a conventional takeoff and landing (CTOL) configuration such that the tilter provides horizontal thrust for the fixed-wing takeoff phase, cruising phase, and landing phase. In some embodiments, the rear electric engine is not used to generate thrust during CTOL missions, and the rear propeller is retracted to minimize drag.

[0036] In some embodiments, the electric engines described herein may possess design features that mitigate and defend against uncontained fires, such as by utilizing non-hazardous amounts of flammable fluid contained in both tilt and lift engines. For example, in some embodiments, the electric engine may be configured to utilize less than one quart of oil or another flammable fluid. Some embodiments may include an electric engine containing a non-hazardous amount of air so that any fire cannot maintain a duration that allows it to spread to another part of the aircraft. In some embodiments, the non-hazardous amount of air may be in contact with the flammable liquid throughout the electric engine. Some embodiments may include an electric engine having up to 1 liter, 2 liters, 3 liters, 4 liters, 5 liters, 10 liters, or 20 liters of air in the electric engine housing. In some embodiments, the amount of air present in the electric engine housing may have a fixed ratio to the amount of oil or other liquid for cooling present in the electric propulsion system. Such a ratio may be driven by determining the amount of heat required to adequately cool the electric propulsion system. Some embodiments may include a ratio of approximately 3:1 of air to oil present in the electric propulsion system. Some embodiments may include an electric engine housing in which 75% of the open volume, i.e., the internal volume not occupied by the components of the electric engine, is composed of air, and 25% of the open volume is composed of oil or some other liquid for cooling and / or lubrication. Some embodiments may also include an electric engine without a nominal ignition source, an engine with a temperature operating limit that may be 50°C or more below the ignition temperature of a flammable fluid, and may have overheat detection and protection, overvoltage detection and protection, and / or overcurrent detection and protection. Furthermore, some embodiments may include an electric propulsion system in which the bulk temperature of the electric propulsion system is lower than the ignition temperature and flash point of the oil or other liquid present in the electric propulsion system under all normal operating conditions. In some embodiments, if an abnormal condition occurs that causes the bulk electric propulsion system temperature to rise, a system response may occur that prevents the temperature from exceeding the flash point and ignition point of the oil or other liquid.In some embodiments, the ratio of air to oil or other liquids may be such that, in the event of a fire occurring within the electric engine housing, including when an arc causes a fire, the amount of air present in the electric engine housing prevents the fire from spreading to other areas of the aircraft. In some embodiments, these and other design features may result in an electric engine that is not considered a specific fire-protected area under one or more guidelines or regulations.

[0037] Herein, we will refer in detail to exemplary embodiments illustrated in the accompanying drawings. The following description refers to the accompanying drawings, and unless otherwise noted, the same numbers in different drawings represent the same or similar elements. In some aspects of the drawings, elements may have similar numbers and refer to similar elements in the disclosed embodiments. The implementations described below in the description of the exemplary embodiments do not represent all implementations consistent with this disclosure. Instead, they are merely examples of apparatus and methods consistent with embodiments relating to the subject matter described in the accompanying claims.

[0038] A. Characteristics of an exemplary electric aircraft Figure 1 is an illustrative perspective view of an exemplary VTOL aircraft consistent with the disclosed embodiments. Figure 2 is another illustrative perspective view of an exemplary VTOL aircraft in an alternative configuration consistent with embodiments of the present disclosure. Figures 1 and 2 illustrate VTOL aircraft 100, 200 in cruising configuration and vertical takeoff, landing, and hovering configuration (also referred to herein as “climb” configuration), respectively, consistent with embodiments of the present disclosure. Elements corresponding to Figures 1 and 2 may have similar figures and refer to similar elements of aircraft 100, 200. Aircraft 100, 200 may include fuselages 102, 202, wings 104, 204 mounted on fuselages 102, 202, and one or more rear stabilizers 106, 206 mounted on the rear of fuselages 102, 202. Multiple lift propellers 112, 212 may be mounted on wings 104, 204 and may be configured to provide lift for vertical takeoff, landing, and hovering. Multiple tilt propellers 114, 214 may be mounted on wings 104, 204 and may be tiltable between an ascent configuration, as shown in Figure 2, which provides a portion of the lift required for vertical takeoff, landing, and hovering, and a cruising configuration, as shown in Figure 1, which provides forward thrust to the aircraft 100 for horizontal flight. As used herein, the ascent configuration of a tilt propeller refers to any tilt propeller orientation in which the tilt propeller thrust primarily provides lift to the aircraft, and the cruising configuration of a tilt propeller refers to any tilt propeller orientation in which the tilt propeller thrust primarily provides forward thrust to the aircraft.

[0039] In some embodiments, the lift propellers 112, 212 may be configured to provide only lift, with all horizontal thrust provided by the tilt propellers. Thus, the lift propellers 112, 212 may be configured in a fixed position and may generate thrust only during the takeoff, landing, and hovering phases of flight. On the other hand, the tilt propellers 114, 214 may be tilted upward in an upward configuration, where the thrust from the propellers 114, 214 is directed downward to provide additional lift.

[0040] For forward flight, the tilt propellers 114, 214 can be tilted from their ascent configuration to their cruising configuration. In other words, the orientation of the tilt propellers 114, 214 can change from an orientation in which the thrust of the tilt propellers is directed downward (to provide lift during vertical takeoff, landing, and hovering) to an orientation in which the thrust of the tilt propellers is directed aft (to provide forward thrust to the aircraft 100, 200). The tilt propeller assembly for a particular electric engine can be tilted around an axis of rotation defined by the mounting point connecting the boom and the electric engine. When the aircraft 100, 200 is in full forward flight, lift can be fully provided by the wings 104, 204. On the other hand, in the cruising configuration, the lift propellers 112, 212 can be shut off. The blades 120, 220 of the lift propellers 112, 212 can be held in a low-drag position for aircraft cruising. In some embodiments, the lift propellers 112, 212 may each have two blades 120, 220 that can be locked for cruising in a minimum drag position where one blade is directly in front of the other blade, as illustrated in Figure 1. In some embodiments, the lift propellers 112, 212 may have three or more blades. In some embodiments, the tilt propellers 114, 214 may include more blades 116, 216 than the lift propellers 112, 212. For example, as illustrated in Figures 1 and 2, the lift propellers 112, 212 may each include, for example, two blades, while the tilt propellers 114, 214 may each include more blades, such as the five blades shown. In some embodiments, each of the tilt propellers 114, 214 may have two to five blades, and in some cases more blades, depending on the design considerations and requirements of the aircraft.

[0041] In some embodiments, the aircraft may include a single wing 104, 204 on each side of the fuselage 102, 202 (or a single wing extending over the entire aircraft). At least a portion of the lift propellers 112, 212 may be located behind the wings 104, 204, and at least a portion of the tilt propellers 114, 214 may be located in front of the wings 104, 204. In some embodiments, all of the lift propellers 112, 212 may be located behind the wings 104, 204, and all of the tilt propellers 114, 214 may be located in front of the wings 104, 204. According to some embodiments, all of the lift propellers 112, 212 and tilt propellers 114, 214 may be mounted on the wings, i.e., the lift propellers or tilt propellers may not be mounted on the fuselage. In some embodiments, the lift propellers 112, 212 may all be located behind the wings 104, 204, and the tilt propellers 114, 214 may all be located in front of the wings 104, 204. According to some embodiments, all the lift propellers 112, 212 and the tilt propellers 114, 214 may be located inside the ends of the wings 104, 204.

[0042] In some embodiments, lift propellers 112, 212 and tilt propellers 114, 214 may be mounted on the wings 104, 204 by booms 122, 222. Booms 122, 222 may be mounted below, above, and / or incorporated into the wing profile. In some embodiments, lift propellers 112, 212 and tilt propellers 114, 214 may be mounted directly on the wings 104, 204. In some embodiments, one lift propeller 112, 212 and one tilt propeller 114, 214 may be mounted on each boom 122, 222. Lift propellers 112, 212 may be mounted at the rear end of booms 122, 222, and tilt propellers 114, 214 may be mounted at the front end of booms 122, 222. In some embodiments, lift propellers 112, 212 may be mounted in fixed positions on booms 122, 222. In some embodiments, tilt propellers 114, 214 may be mounted to the front end of booms 122, 222 via hinges. The tilt propellers 114, 214 may be mounted on booms 122, 222 such that when in their cruising configuration, the tilt propellers 114, 214 are aligned with the body of booms 122, 222, forming a continuous extension of the front end of booms 122, 222 that minimizes drag for forward flight.

[0043] In some embodiments, the aircraft 100, 200 may include, for example, one wing on each side of the fuselage 102, 202, or a single wing extending across the entire aircraft. According to some embodiments, at least one wing 104, 204 is a high wing mounted on the upper side of the fuselage 102, 202. According to some embodiments, the wing includes control surfaces such as flaps and / or ailerons. According to some embodiments, the wings 104, 204 may be designed with a profile that reduces drag during forward flight. In some embodiments, the wingtip profile may be curved and / or tapered to minimize drag.

[0044] In some embodiments, the rear stabilizers 106, 206 include control surfaces such as one or more rudders, one or more elevators, and / or one or more combined rudder-elevator configurations. The wings(s) may have any preferred design. In some embodiments, the wings have tapered leading edges.

[0045] In some embodiments, a lift propeller 112, 212 or tilt propeller 114, 214 may tilt relative to at least one other lift propeller 112, 212 or tilt propeller 114, 214. As used herein, canting refers to the relative orientation of the axis of rotation of a lift propeller / tilt propeller around a line parallel to the longitudinal direction, similar to the roll degrees of freedom of an aircraft. The tilting of a lift propeller and / or tilt propeller may help minimize damage from propeller rupture by oriented the plane of rotation of the lift propeller / tilt propeller disc (the blades and the hub on which those blades are mounted) so as not to intersect with critical parts of the aircraft (such as areas of the fuselage where a person may be positioned, critical flight control systems, batteries, adjacent propellers, etc.) or other propeller discs, and may provide enhanced yaw control during flight.

[0046] Figure 3 is an illustrative top view of an exemplary VTOL aircraft consistent with embodiments of the present disclosure. The aircraft 300 shown in the figure may be a top view of aircraft 100 and 200 shown in Figures 1 and 2, respectively. As considered herein, the aircraft 300 may include twelve electric propulsion systems distributed across the aircraft 300. In some embodiments, the distribution of electric propulsion systems may include six forward electric propulsion systems 314 and six rear electric propulsion systems 312 mounted on the forward and rear booms of the main wing 304 of the aircraft 300. In some embodiments, the length of the trailing end of the boom 324 from the wing 304 to the lift propeller 312 may include similar trailing ends of the boom 324 across a number of trailing ends of the boom. In some embodiments, the length of the trailing end of the boom may vary across six exemplary trailing ends of the boom. For example, each trailing end of the boom 324 may include a different length from the wing 304 to the lift propeller 312, or a subset of the trailing ends of the boom may have similar lengths. In some embodiments, the front end of the boom 322 may include varying lengths from the wings 304 to the tilt propeller 314 across the entire front end of the boom. For example, as shown in Figure 3, the length of the front end of the boom 322 from the tilt propeller 314 closest to the fuselage to the wings 304 may include a length longer than the length of the front end of the boom 322 from the wings 304 to the tilt propeller 314 furthest from the fuselage. Some embodiments may include a boom front end having similar lengths across the entire six exemplary front ends of the boom, or any other length distribution, from the wings 304 to the tilt propeller 314. Some embodiments may include an aircraft 300 having eight electric propulsion systems, with four forward electric propulsion systems 314 and four rear electric propulsion systems 312, or any other distribution of forward and rear electric propulsion systems, including embodiments in which the number of forward electric propulsion systems 314 is less than or greater than the number of rear electric propulsion systems 312. Furthermore, Figure 3 illustrates an exemplary embodiment of a VTOL aircraft 300, which has a forward propeller 314 oriented horizontally for horizontal flight and a rear propeller blade 320 in a retracted position for forward flight.

[0047] As disclosed herein, forward and rear electric propulsion systems may be of the clockwise (CW) or counterclockwise (CCW) type. Some embodiments may include a variety of forward electric propulsion systems having a mixture of both CW and CCW types. In some embodiments, the rear electric propulsion system may have a mixture of CW and CCW type systems among the rear electric propulsion systems.

[0048] Figure 4 is a schematic diagram illustrating exemplary propeller rotation of a VTOL aircraft, consistent with the disclosed embodiments. The aircraft 400 shown in the figure may be a top view of the aircraft 100, 200, and 300 shown in Figures 1, 2, and 3, respectively. The aircraft 400 may include six forward electric propulsion systems, three of which are CW type 424 and the remaining three forward electric propulsion systems are CCW type. In some embodiments, three rearward electric propulsion systems may be CCW type 428 and the remaining three rearward electric propulsion systems are CW type 430. Some embodiments may include an aircraft 400 having four forward electric propulsion systems and four rearward electric propulsion systems, each having two CW type and two CCW type propulsion systems. In some embodiments, propellers may be reversed relative to adjacent propellers to cancel torque steer generated by the propeller rotation and resulting in the aircraft's fuselage or wings. In some embodiments, the difference in rotation direction may be achieved using the engine rotation direction. In other embodiments, the engines may all rotate in the same direction, and gearing may be used to achieve different propeller rotation directions.

[0049] Some embodiments may include an aircraft 400 having a forward electric propulsion system and a rear electric propulsion system, where the quantities of CW type 424 and CCW type 426 are not equal between forward electric propulsion systems, between rear electric propulsion systems, or between forward electric propulsion systems and rear electric propulsion systems.

[0050] Figure 5 is a schematic diagram illustrating exemplary power connections in a VTOL aircraft, consistent with the disclosed embodiments. A VTOL aircraft may have various power systems connected to diagonally opposed electric propulsion systems. In some embodiments, the power systems may include high-voltage power systems. In some embodiments, high-voltage power systems may be connected to electric engines via high-voltage channels. In some embodiments, the aircraft 500 may include six power systems, including batteries 526, 528, 530, 532, 534, and 536 housed within the wings 570 of the aircraft 500. In some embodiments, the aircraft 500 may include six forward electric propulsion systems having six electric engines 502, 504, 506, 508, 510, and 512, as well as six rear electric propulsion systems having six electric engines 514, 516, 518, 520, 522, and 524. In some embodiments, batteries may be connected to diagonally opposed electric engines. In such a configuration, the first power system 526 may supply power to the electric engine 502 via a power connection channel 538 and to the electric engine 524 via a power connection channel 540. In some embodiments, the first power system 526 may be paired with a fourth power system 532 via a power connection channel 542 having a fuse to prevent excessive current from flowing through power systems 526 and 532. In addition to this embodiment, the VTOL aircraft 500 may include a second power system 528 paired with a fifth power system 534 via a power connection channel 548 having a fuse, which may supply power to electric engines 510 and 516 via power connection channels 544 and 546, respectively. In some embodiments, a third power system 530 may be paired with a sixth power system 536 via a power connection channel 554 having a fuse, and may supply power to electric engines 506 and 520 via power connection channels 550 and 552, respectively. A fourth power system 532 may also supply power to electric engines 508 and 518 via power connection channels 556 and 558, respectively. A fifth power system 534 may also supply power to electric engines 504 and 522 via power connection channels 560 and 562, respectively.The sixth power grid 536 may also supply power to the electric engines 512 and 514 via power connection channels 564 and 566, respectively.

[0051] As disclosed herein, an electric propulsion system may include an electric engine connected to a high-voltage power system, such as a battery located within the aircraft, via a high-voltage channel or power connection channel. Some embodiments may include various batteries housed within the aircraft wings, having high-voltage channels leading to the electric propulsion system throughout the aircraft, including the wings and boom. In some embodiments, multiple high-voltage power systems may be used to create an electric propulsion system with multiple high-voltage power sources to avoid the risk of a single point of failure. In some embodiments, the aircraft may include multiple electric propulsion systems that can be pattern-wired to various batteries or power sources housed throughout the aircraft. It will be recognized that such a configuration may be beneficial in avoiding the risk of a single point of failure, where the failure of one battery or power source could result in a condition in part of the aircraft where it cannot maintain the amount of thrust necessary to continue flight or perform a controlled landing. For example, if a VTOL has two forward electric propulsion systems and two rearward electric propulsion systems, the forward and rearward electric propulsion systems on both sides of the VTOL aircraft may be connected to the same high-voltage power system. In such a configuration, if one high-voltage power system fails, the forward and rear electric propulsion systems on opposite sides of the VTOL aircraft may remain operational, providing a more balanced flight or landing compared to a failed forward and rear electric propulsion system on the same side of the VTOL aircraft. Some embodiments may include four forward and four rear electric propulsion systems in which diagonally opposed electric engines are connected to a common battery or power source. Some embodiments may include various configurations of electric engines electrically connected to a high-voltage power system so that the risk of a single point of failure in the event of a power failure is avoided, and the flight phase during the failure can continue or the aircraft can perform an alternative flight phase in response to the failure.

[0052] As discussed above, an electric propulsion system may include an electric engine that provides mechanical shaft power to a propeller assembly to generate thrust. In some embodiments, the electric engine of the electric propulsion system may include a high-voltage power system that supplies high-voltage power to the electric engine and / or a low-voltage system that supplies low-voltage DC power to the electric engine. Some embodiments may include an electric engine(s) that digitally communicates with a flight control system ("FCS") which includes a flight control computer ("FCC") that can send and receive signals to and from the electric engine, including command and response data or status. Some embodiments may include an electric engine that can receive operating parameters from the FCC, including speed, voltage, current, torque, temperature, vibration, propeller position, and any other values ​​of operating parameters, and transmit the operating parameters to the FCC.

[0053] In some embodiments, the flight control system may include a system capable of communicating with the electric engine to send and receive analog / discrete signals to the electric engine and controlling a device that can redirect the thrust of the tilt propeller between primarily vertical in vertical flight mode and primarily horizontal in forward flight mode. In some embodiments, this system may be referred to as a tilt propeller system ("TPS") and may be capable of transmitting and oriented additional features of the electric propulsion system.

[0054] Figure 6 illustrates an exemplary architecture and design block diagram of an electric propulsion unit 600 consistent with the disclosed embodiments. In some embodiments, the electric propulsion system 602 may include an electric engine subsystem 604 that can supply torque to a propeller subsystem 606 via a shaft to generate thrust for the electric propulsion system 602. In some embodiments, the electric engine subsystem 604 may receive low-voltage DC (LV DC) power from a low-voltage system (LVS) 608. In some embodiments, the electric engine subsystem 604 may receive high-voltage (HV) power from a high-voltage power system (HVPS) 610 that includes at least one battery or other device capable of storing energy. In some embodiments, the high-voltage power system may include two or more batteries or other devices capable of storing energy and supplying high-voltage power to the electric engine subsystem 604. It will be recognized that such configurations may be advantageous in that a single battery failure does not pose a single point of failure risk leading to a failure of the electric propulsion system 602.

[0055] In some embodiments, the electric propulsion system 602 may include an electric engine subsystem 604 that receives signals from and transmits signals to the flight control system 612. In some embodiments, the flight control system 612 may include a flight control computer that can send commands to and receive status and data from the electric engine subsystem 604 using Controller Area Network ("CAN") data bus signals. While the CAN data bus signals are used between the flight control computer and the electric engine(s), it should be understood that in some embodiments, any form of communication capable of sending and receiving data from the flight control computer to and from the electric engine(s) may be included. In some embodiments, the flight control system 612 may also include a tilt propeller system ("TPS") 614 that can send and receive analog discrete data to and from the tilt propeller electric engine subsystem 604. The tilt propeller system 614 may include a device that transmits operating parameters to the electric engine subsystem 604 and moves the orientation of the propeller subsystem 606, thereby redirecting the thrust of the tilt propeller during various phases of flight using mechanical means such as a gearbox assembly, a linear actuator, and any other configuration of components for changing the orientation of the propeller subsystem 606.

[0056] As will be considered throughout, exemplary VTOL aircraft may possess various types of electric propulsion systems, including tilt and lift propellers, with forward-facing electric engines having the ability to tilt during various phases of flight, and rear-facing electric engines that remain in one orientation and can only be active during specific phases of flight (i.e., takeoff, landing, and hovering).

[0057] Figure 7 is a schematic diagram illustrating an exemplary tilt electric propulsion system for a VTOL aircraft, consistent with the disclosed embodiments. The tiltable electric propulsion system 700 may include an electric engine assembly 702 aligned along a shaft 724 connected to an output shaft 738 mechanically coupled to a propeller assembly 720 having a hub, spinner, and tilt propeller blades. In some embodiments, the electric engine assembly 702 may include a motor and gearbox assembly 704 aligned along the shaft 724 and mechanically coupled. In some embodiments, the motor and gearbox assembly 704 may include an electric motor assembly having a stator 706 and a rotor 708. As shown in Figure 7 and in some embodiments, the stator 706 may include a plurality of stator windings connected to an inverter 716. In such a configuration, the stator 706 may incorporate one or more redundancies, so that if one set of windings fails, power is still transmitted to the stator 706 through one or more remaining windings, and as a result, the electric engine assembly 702 retains power and continues to generate thrust in the propeller assembly 720.

[0058] In some embodiments, the motor and gearbox assembly 704 may include a gearbox 710 aligned along the shaft 724 to provide gear reduction between the torque on the shaft 724 from the electric engine assembly, which comprises a stator 706 and a rotor 708, and the output shaft 738. The torque applied to the output shaft 738 can be transmitted to the propeller assembly 720. In some embodiments, the gearbox 710 may include an oil pump. In such embodiments, the oil pump may drive the circulation of oil throughout the motor and gearbox assembly 704 at a speed equivalent to the rotation of the output shaft 738 to cool and lubricate the gearbox and electric motor components. In some embodiments, the oil pump may drive the circulation of oil at a speed faster or slower than the rotation of the output shaft 738. In some embodiments of the motor and gearbox assembly 704, a propeller position sensor 712 located within the housing may include a propeller position sensor 712 that can detect the magnetic field generated by the electric engine assembly to determine the propeller position. Further embodiments may include a propeller position sensor 712 that is powered by the inverter 716 and transmits collected data to the inverter 716.

[0059] In some embodiments, the electric engine assembly 702 may also include an inverter assembly 714 aligned along the shaft 724. The inverter assembly 714 may include an inverter 716 and an inverter power supply 740. The inverter power supply 740 may accept low-voltage DC power from a low-voltage system 734 located outside the electric engine assembly 702. The inverter power supply 740 may accept low-voltage DC power originating from a high-voltage power system 732 located outside the electric engine assembly 702, which is converted to low-voltage DC power via a DC-DC converter 742. The inverter 716 may supply high-voltage AC to the stator 706 of the electric engine assembly located within the motor and gearbox assembly 704 via at least one three-phase winding. The inverter assembly 714 may include an inverter 716 that can receive flight control data from a flight control computing subsystem 736.

[0060] In some embodiments, the motor and gearbox 704 may be located between the inverter assembly 714 and the propeller assembly 720. Some embodiments may also include a partition plate 744 coupled to the motor and gearbox assembly 704 and the inverter assembly 714. The partition plate 744 may create an enclosed environment for the upper part of the motor and gearbox assembly 704 via an end bell assembly and an enclosed environment for the lower part of the inverter assembly 714 via a thermal plate. In some embodiments, the partition plate 744 may function as an integrated mounting bracket for supporting a heat exchanger 718. The heat exchanger 718 may include, for example, folded fins or other types of heat exchangers. In some embodiments, the electric propulsion system 700 may circulate oil or other coolant throughout the electric engine assembly 702, the motor and gearbox assembly 704, or the inverter assembly 714 to transfer heat generated from the components to the oil or other coolant liquid. The heated oil or other coolant liquid may circulate through the heat exchanger 718 to transfer heat to the airflow 722 passing through the fins of the heat exchanger.

[0061] In some embodiments, the electric engine assembly 702 may be mounted to or coupled to the aircraft's boom structure 726. The variable pitch mechanism 730 may be mechanically coupled to the propeller assembly 720. In some embodiments, the variable pitch mechanism may abut against the electric engine assembly 702. In some embodiments, the variable pitch mechanism 730 may be coupled to the variable pitch mechanism 730 so that it can be remotely mounted in the aircraft's boom, wing, or fuselage. In some embodiments, the variable pitch mechanism 730 may include a shaft or component that proceeds into the propeller assembly 720 within or adjacent to the shaft 724. The variable pitch mechanism 730 may function to change the collective angle of the forward electric engine's propeller hub assembly blades as needed for operation during the hovering, transition, and cruising phases. In some embodiments, the electric engine assembly 702 may include being mechanically coupled to a tilt propeller subsystem 728 that can redirect thrust between primarily vertical during vertical flight mode and primarily horizontal during forward flight mode. In some embodiments, the tilt propeller subsystem may be in contact with the variable pitch mechanism 730. Some embodiments may include a tilt propeller subsystem 728 comprising various components located in different locations. For example, components of the tilt propeller subsystem may be coupled to the electric engine assembly 702, while other components may be coupled to the variable pitch mechanism 730. These various components of the tilt propeller subsystem 728 may cooperate to redirect the thrust of the tiltable electric propulsion system 700.

[0062] Figures 8A–8C illustrate exemplary tilt electric propulsion systems for VTOL aircraft, consistent with the disclosed embodiments. Figures 8A–8C refer to similar elements of tiltable electric propulsion systems 800A, 800B, and 800C, which possess similar figures. Thus, similar design considerations and configurations may be considered throughout the embodiments.

[0063] Figures 8A and 8B illustrate side profiles and perspective views, respectively, of tiltable electric propulsion systems 800A and 800B in a cruising configuration integrated into booms 812A and 812B, consistent with the present disclosure. The tiltable propeller electric propulsion systems 800A and 800B may include electric engine assemblies 802A and 802B housed within the booms 812A and 812B of a VTOL aircraft. In some embodiments, the cruising configuration may include electric engine assemblies 802A and 802B located within the booms 812A and 812B. The electric engine assemblies 802A and 802B may comprise an electric motor assembly, a gearbox assembly, an inverter assembly having power connection channels 810A and 810B, and heat exchangers 804A and 804B, as described herein. The electric engine assemblies 802A and 802B may be mechanically coupled to propulsion assemblies 808A and 808B, which include shaft flange assemblies 806A and 806B, a spinner, and propeller blades.

[0064] Figure 8C illustrates a top-down view along the spinner 808C of a tiltable electric propulsion system 800C in an ascent configuration integrated into boom 812B, consistent with the present disclosure. As shown in Figure 8C, the tiltable electric propulsion system 800C in the ascent configuration may include electric engine assemblies 802A, 802B that are located outside the boom 812C and whose orientation relative to the boom 812C is altered.

[0065] As discussed herein, an electric ascent propulsion system may be configured to provide thrust in one direction and may not provide thrust during all phases of flight. For example, an ascent system may provide thrust during takeoff, landing, and hovering, but may not provide thrust during cruising.

[0066] Figure 9 is a schematic diagram illustrating an exemplary climb electric propulsion system for a VTOL aircraft, consistent with the disclosed embodiments. The climb electric propulsion system 900 may be mounted on or coupled to the boom structure 924 of the aircraft. The climb electric propulsion system 900 may include an electric engine assembly 902 aligned along a shaft 940 connected to an output shaft 932 mechanically coupled to a propeller assembly 920 having a hub and tilt propeller blades. In some embodiments, the electric engine assembly 902 may include a motor and gearbox assembly housing 904 aligned along the shaft 940 and mechanically coupled. In some embodiments, the motor and gearbox assembly housing 904 may include an electric motor assembly having a stator 906 and a rotor 908. The stator 906 may include a plurality of stator windings connected to an inverter 916. In such configurations, the stator 906 may incorporate one or more redundancies and backup measures to avoid a single point of failure in the case. For example, the stator 906 may include multiple windings so that if one winding fails, power can continue to be transmitted to the stator 906 through the remaining windings, allowing the electric engine assembly 902 to retain power and continue generating thrust in the propeller assembly 920.

[0067] In some embodiments, the motor and gearbox assembly housing 904 may include a gearbox 910 aligned along the shaft 940, providing gear reduction between the torque on the shaft 932 from the electric engine assembly, which comprises a stator 906 and a rotor 908, and the output shaft 932. The torque applied to the output shaft 932 can be transmitted to the propeller assembly 920. In some embodiments, the gearbox 910 may include a fluid pump for circulating cooling and / or lubricating fluid. In the shown embodiment, the fluid pump is an oil pump. In such embodiments, the oil pump may cool and lubricate the gearbox and electric motor components by driving the circulation of oil throughout the motor and gearbox assembly housing 904 at a speed equivalent to the rotation of the output shaft 932. In some embodiments of the motor and gearbox assembly housing 904, a propeller position sensor 912 located within the housing may include a propeller position sensor 912 that can detect a magnetic field generated by the electric engine assembly to determine the propeller position. Further embodiments may include a propeller position sensor 912 that transmits collected data to the inverter 916, which is powered by the inverter 916 and can be transferred to the flight control computing system 930 along with other flight control data.

[0068] In some embodiments, the electric engine assembly 902 may also include an inverter assembly housing 914 aligned along an axis sharing the axis of the shaft 932. The inverter assembly housing 914 may include an inverter 916 and an inverter power supply 934. The inverter power supply 934 may accept low-voltage DC power from a low-voltage grid 928 located outside the electric engine assembly 902. The inverter power supply 934 may accept low-voltage DC power originating from a high-voltage power grid 926 located outside the electric engine assembly 902, which is converted to low-voltage DC power via a DC-DC converter 936. The inverter 916 may supply high-voltage AC to the stator 906 of the electric engine assembly located within the motor and gearbox assembly housing 904 via at least one three-phase winding. The inverter assembly 914 may include an inverter 916 that can transmit data to and receive data from the flight control computing subsystem 930.

[0069] In some embodiments, the motor and gearbox housing 904 may be located between the inverter assembly housing 914 and the propeller assembly 920. Some embodiments may also include a partition plate 938 coupled to both the motor and gearbox assembly housing 904 and the inverter assembly housing 914. The partition plate 938 may create an enclosed environment for the upper part of the motor and gearbox assembly housing 904 via the end bell assembly and an enclosed environment for the lower part of the inverter assembly housing 914 via the thermal plate. In some embodiments, the partition plate 938 may function as an integrated mounting bracket for supporting a heat exchanger 918. The heat exchanger 918 may include, for example, folded fins or other types of heat exchangers. In some embodiments, the electric propulsion system 900 may circulate oil or other coolant liquid throughout the electric engine assembly 902, the motor and gearbox assembly 904, or the inverter assembly 914 to transfer heat generated from the components to the oil or other coolant liquid. The heated oil or other coolant liquid may circulate through the heat exchanger 918 to transfer heat to the airflow 922 passing through the fins of the heat exchanger.

[0070] In some embodiments, tiltable electric propulsion systems and climbable electric propulsion systems may have similar components. This can be advantageous with respect to many design considerations present in VTOL aircraft. For example, from a manufacturability standpoint, different types of electric propulsion systems with similar components may be beneficial from a manufacturing efficiency standpoint. Furthermore, having similar components may be beneficial from a risk management standpoint, as similar components have similar failure points, and these failure points can be thoroughly considered and designed when comparing systems with similar components to systems with different components and configurations.

[0071] It should be understood that a tiltable electric propulsion system may have additional components compared to a climb electric propulsion system, and in some embodiments may have different components, but in some embodiments, a tiltable electric propulsion system and a climb electric propulsion system may have the same components. For example, in some embodiments, a tiltable and a climb electric propulsion system may include the same components, but because a climb electric propulsion system may be coupled to the boom, wing, or fuselage of an aircraft, it may not be able to provide thrust in as many directions as a tiltable electric propulsion system.

[0072] Figures 10A–10B are illustrative examples of an exemplary climb electric propulsion system for a VTOL aircraft, consistent with the disclosed embodiments. Figures 10A and 10B have similar figures and refer to similar elements of climb electric propulsion systems 1000A and 1000B. Thus, similar design considerations and configurations may be considered throughout the embodiments.

[0073] Figure 10A illustrates a side profile of a climb electric propulsion system 1000A in a climb configuration integrated into boom 1010A, consistent with the present disclosure. The climb electric propulsion system 1000A may comprise an electric engine assembly 1002A housed within boom 1010A of a VTOL aircraft. In some embodiments, the climb configuration may include an electric engine assembly 1002A positioned vertically within boom 1010A. The electric engine assembly 1002A may comprise an electric motor assembly, a gearbox assembly, an inverter assembly with a power connection channel 1008A, and a heat exchanger 1004A, as described herein. The electric engine assembly 1002A may be mechanically coupled to a propulsion assembly 1006A comprising a shaft flange assembly and propeller blades.

[0074] Figure 10B illustrates a top-down view of the lift electric propulsion system 1000B in a lift configuration integrated into the boom 1010B, consistent with the present disclosure.

[0075] Some embodiments of the disclosed electric engine may generate heat during operation and may be equipped with a thermal management system to ensure that the components of the electric engine do not fail during operation. In some embodiments, a coolant may be used and circulated throughout some or all of the components of the engine, or through some of the components, or through some of the components, throughout the individual components of the engine, such as an inverter, gearbox, or motor, to help manage the heat present in the engine. Some embodiments may include using an air cooling method to cool the electric engine, or using a mixture of coolant and air to manage the heat generated in the electric engine during operation. In some embodiments, the coolant used may also be the same liquid used as a lubricant throughout the inverter, gearbox, or motor. For example, components of the electric engine may be cooled using liquid or air, or using a mixture of air and liquid cooling. As another example, the motor may be cooled using air cooling, and the inverter and gearbox may be cooled using liquid cooling. It should be understood that the cooling mixture may be used in any combination of electric engine components, or within each component.

[0076] In some embodiments, oil may be used as a lubricant throughout the electric engine and as a coolant fluid to help manage the heat generated by the engine during operation. In addition to this example, different amounts of oil, e.g., less than 1 quart, 1.5 quarts, 2 quarts, 2.5 quarts, 3 quarts, 5 quarts, or any other amount of oil necessary to lubricate and cool the electric engine, may be used in combination with or without air cooling assistance, and may be utilized as both lubricant and coolant fluids within the electric engine. In some embodiments, the amount of oil or liquid used in the system in connection with cooling may be determined based on the amount of heat required to drive heat transfer from the components of the electric propulsion system. As disclosed herein, electric engines may have different primary functions, such as being used only for ascent and landing and therefore only in one orientation, or being used throughout all stages of flight, such as ascent, landing, and during flight. Engines used throughout all stages of flight may have various orientations throughout the flight and may contain more lubricant and coolant than engines used only in one orientation. Therefore, not all engines on an aircraft have to contain the same amount of lubricant and coolant. For example, climb and landing engines may require less than one quart of oil, while engines operating at all stages of flight may require more than one quart. In some embodiments, the amount of oil or liquid for cooling may be appropriate to provide enough heat to drive heat transfer from the components of the electric propulsion system, regardless of the orientation of the electric propulsion system. The embodiments considered herein are illustrative and non-limiting and do not determine limits on the amount of lubricant and coolant that may be used in electric engines.

[0077] In some embodiments, oil may be used to lubricate and cool the electric engine. Such embodiments may require an additional volume of oil. In such embodiments, the additional oil may allow for the elimination of conventional components that could be used to cool such an electric engine. For example, if the electric engine is cooled by another liquid such as glycol, the engine may have separate heat exchangers for both the lubricating fluid and the coolant fluid. Thus, in embodiments where a single fluid, such as oil, is used for both lubrication and cooling, an increase in oil will be seen, but since only one heat exchanger is required, the number of heat exchangers used is reduced, and potentially fewer other components are needed, which can lead to a reduction in the overall mass of the system and a more favorable drag profile. Furthermore, using a single substance for lubrication and cooling of the engine reduces mass and can increase the efficiency of the system due to the advantages of cooling the engine with a substance rather than relying on air cooling, which can be problematic in distributing throughout the engine.

[0078] Some embodiments of electric engines may include various components for monitoring flammable fluids and preventing flammable materials from entering specific sections of the electric engine. Some embodiments may include an electric engine having a wet zone enclosure which may be defined by a gearbox, motor, and / or heat exchanger. In some embodiments, an electric engine may have up to 4 liters or more of air in the motor gearbox housing in contact with the engine oil. Embodiments of the motor gearbox housing may use a breather to equalize internal and external pressures. Embodiments of the breather may include a breather that protrudes above nearby design features to prevent unintended ingress of external fluids. Some embodiments may include a breather that has a screen and a bypass entry path to prevent ingress of external debris. Embodiments may include a sight glass present in both tilt and rise electric engines to ensure that the oil is not overfilled or underfilled during maintenance.

[0079] Some embodiments of the electric engine may include, as necessary, active protection features in the forward and rear electric engines, such as monitoring vibrations throughout the engine, as well as internal temperatures throughout the engine, including oil temperature, stator winding set temperature, inverter bulk capacitor temperature, power module temperature, control board power module temperature, control board control processor temperature, control board monitor processor temperature, internal hotspot temperature, and various other operating conditions. Such monitoring may be achieved using various sensors positioned throughout the electric propulsion system and the aircraft. Embodiments may include vibration limits based on known fault points or component resonances, and overheat limits set based on known fault temperatures and operating limits related to the ignition temperature of the fluid. In some embodiments, various sensors used to monitor operating conditions throughout the engine may report the operating conditions to the flight control system. Some embodiments may include threshold operating values ​​that may be required before the operating values ​​are transmitted to or flagged by the flight control system. In some embodiments, the flight control system may act to reduce the amount of power directed to the electric propulsion system in response to the detection of operating conditions. Some embodiments may include reducing the amount of power supplied to the electric propulsion system to reduce mechanical wear or friction sparks due to vibration, and / or reducing power to lower the temperature of components present within the electric propulsion system. Furthermore, some embodiments may include reducing power to an electric propulsion system whose efficiency, as detected by the inverter, is below a target efficiency. In some embodiments, for example, if twelve electric propulsion systems are present in an aircraft, the flight control system may act to reduce or terminate power to a single electric propulsion system while increasing power directed to the remaining electric propulsion systems or a subset thereof to counteract the reduction in lift generated by one electric propulsion system. In some embodiments, the flight control system may establish various thresholds for operating states to correspond to the reduction or increase in power to the electric propulsion systems.

[0080] Some embodiments may include a high-voltage power system that may have fuses at high-voltage battery terminals that can quickly and irreversibly disconnect the engine's electrical connections to mitigate and avoid overcurrent events. Such overcurrent protection may be activated when the electric engine's current consumption is greater than the overcurrent operation. Thus, in some embodiments, a fault condition leading to an overcurrent may only cause a transient overheating, arcing, or sparking fault. Some embodiments may include a fire threat characterization test ignition source that may be selected as a more serious ignition source than a short circuit occurring within the electric engine and opened by the engine fuse. In some embodiments, the inverter may detect AC overcurrents, isolate abnormal phases, and / or continuously monitor the input DC voltage and apply protective actions to maintain the voltage below the overvoltage operating limit.

[0081] During takeoff, landing, hovering, and cruising, the motors and associated control components of a VTOL aircraft can generate heat. Heat dissipation is necessary to prevent degradation or damage to the motors, control components, and other elements of a VTOL aircraft. In some types of VTOL aircraft, such as electric VTOL (eVTOL) aircraft, thermal control is also important for maintaining optimal energy efficiency of components such as battery-powered parts.

[0082] Some elements can generate high heat loads only during specific operating periods. For example, some lift propellers may only be used during takeoff, landing, and hovering, and may be shut off during cruising. Thus, such lift propellers may generate high heat loads during takeoff, landing, and hovering, and generate little to no heat during cruising.

[0083] B. Exemplary Embodiment of a Rotor Assembly In some embodiments, at least one electric engine may be mechanically connected directly or indirectly to the aircraft's fuselage and electrically connected to a power source. Mechanical connection may include fastening, mounting, coupling, fixing, or joining. Direct connection may include the electric engine being connected to the fuselage such that it is in contact with or abuts against the fuselage. Indirect connection may include the electric engine being connected to the fuselage such that intermediate components, such as wings, booms, or other intermediate components, may be present between the fuselage and the electric engine.

[0084] In some embodiments, the electric propulsion system may include a gearbox assembly. The gearbox may assist in gear reduction of the electric propulsion system. The gearbox assembly may include multiple sets of gearboxes. For example, in some embodiments, the output of a gearbox assembly may be supplied to another gearbox assembly to achieve greater gear reduction. Such embodiments may include at least one sun gear, at least one set of planetary gears, at least one ring gear, and at least one planetary carrier. The gearbox may have common gears such as a common sun gear, a common set of planetary gears, and a common ring gear. In some embodiments, the sun gear may be the central gear of a planetary gear system or an epicyclic gear system. In some embodiments, the sun gear may be an input gear. Embodiments considered herein may be modified to include multiple sets of gearboxes. In some embodiments, a combination of using a sun gear, planetary gears including a composite planetary gear, and a ring gear may result in gear reduction. Thus, the characteristics of the gears in the gearbox assembly may determine the gear reduction available in the electric propulsion system. In some embodiments, the aircraft may require a specific value of torque applied to the propeller assembly to achieve the desired or required lift to the payload; therefore, the gear reduction value can be an relevant design criterion for VTOL aircraft. The gearbox can assist in providing torque while minimizing the drag profile and mass of the electric engine. Accordingly, the embodiments described herein may provide an electric propulsion system design optimized in terms of drag profile and mass-to-payload capability.

[0085] In some embodiments, an electric propulsion system may include an electric motor having a stator assembly and a rotor assembly. For example, an electric engine may drive the rotation of a rotor, which in turn may drive the rotation of a gearbox providing gear reduction to a shaft in an electric propulsion system. In some embodiments, the rotor may include a plurality of magnets. Electromagnetic interaction between the stator and the rotor may drive the rotation of the rotor, and therefore centrifugal force may act on the magnets in the rotor. It will be recognized that at certain rotational speeds, the magnets may move away from the rotor due to centrifugal force. For example, centrifugal force may move the magnets radially outward so that they move away from the rotor, creating a distance between the rotor and the magnets, which may be detrimental to the electromagnetic properties of the rotor. Therefore, the magnets may be held in place to prevent them from moving away from the rotor. In some embodiments, the rotor assembly may include a sleeve. A sleeve may hold, enclose, surround, confine, or hold one or more objects. For example, a sleeve may include a wrapper, jacket, cover, casing, or shell. As discussed herein, the disclosed embodiments may involve expandable sleeves that can be expanded or stretched in diameter or circumference. Pre-fabricated sleeves may include expandable sleeves such as carbon fiber sleeves.

[0086] Some disclosed embodiments involve methods, systems, and apparatus for manufacturing a rotor assembly, including the assembly and installation of components of the rotor assembly. As described herein, disclosed embodiments of a rotor assembly may involve inserting magnets into a prefabricated sleeve, thereby eliminating the need to wind a material such as carbon fiber around the magnets after they have been mounted to the back iron of the rotor. Winding, or other methods of applying the sleeve after the magnets have been assembled, do not provide the tension (e.g., preload) necessary to hold the magnets when rotating at the motor's operating speed, and may therefore require a larger air gap (e.g., the distance between the rotor magnets and the stator's copper windings) between the rotor and the stator, which could reduce rotor efficiency. For example, when winding carbon fiber around the magnets (e.g., if adhesive can be used to fix the magnets to the back iron), the tension used to wind the carbon fiber may not provide the optimal preload to hold the magnets. In addition, disclosed embodiments may reduce the need to heat the rotor to high temperatures to cure the carbon fiber, which could degrade the strength of the magnets (e.g., reduce the magnetism of the magnets). The disclosed embodiments may also reduce the need for adhesives or fillers at contact points between magnets in the rotor (e.g., joint line gaps resulting from joining the sides of magnets together), thereby potentially providing improvements for efficiency, magnetic force, maximum RPM, and mass savings. Furthermore, because the disclosed embodiments can reduce air gaps and the need for adhesives, they may enable higher magnet concentrations (e.g., higher magnetic force) for a given rotor size, thereby potentially providing a more compact and smaller motor.

[0087] Furthermore, the disclosed embodiments of rotor assembly manufacturing can prevent failures (e.g., breakage or damage) of the magnets and / or sleeves during installation. For example, the disclosed embodiments can insert the magnets into the sleeve to support and expand the magnets while preventing shear forces into the sleeve that could lead to failure of the sleeve, thereby creating a desired load or expansion to hold the magnets in the sleeve. In some embodiments, the magnet insertion tool can support the magnets during sleeve expansion in a manner that prevents excessive sliding friction, for example, between the two magnet surfaces or between the sleeve surface and the magnet surface. For example, some of the sliding friction may instead be exerted on the moving surface of the magnet insertion tool.

[0088] The disclosed embodiments may be applicable to any use in motors, such as in any automobile, alternators, generators, and manufacturing motors (e.g., conveyors). For example, the disclosed embodiments may relate to a rotor including surface-mounted magnets. Furthermore, the disclosed embodiments may provide improvements in rotor assembly efficiency and speed, including inserting magnets into the rotor. For example, winding carbon fibers around magnets may take more time compared to expanding a pre-fabricated sleeve.

[0089] Figure 11 illustrates a rotor assembly 1100 consistent with embodiments of the present disclosure. The rotor assembly 1100 may include a sleeve 1104 configured to enclose permanent magnets 1102, 1103, which may be attached to a laminated core 1108, along its circumference. The rotor assembly 1100 may also include a rotor hub 1106. In some exemplary embodiments, the rotor hub 1106 may hold the laminated core 1108, the magnets 1102, and / or the sleeve 1104. The rotation of the rotor may impart a centrifugal force to the magnets in a direction 1116 that may tend to shift or separate the magnets 1102, 1103 from the rotor hub 1106. Some embodiments may involve the use of a material having elastic properties to prevent the magnets from separating from the rotor. Some alternative embodiments may utilize direct winding of a material such as carbon fiber. For example, the magnets 1102 / 1102 may be attached to the laminated core 1108, and the carbon fiber may be wound directly around the magnets along its circumference. It will be recognized that conventional systems may involve the use of adhesives such as glue to attach the magnets to the laminated core. The winding of the carbon fibers may be carried out under high tension to stretch the fibers, resulting in a preload or pressure applied to the magnets, which may help to press the magnets against the laminated core 1108 and prevent the magnets 1102 and 1103 from separating. It will be recognized that higher tension in the carbon fibers may generate a higher preload, which may be more effective in applying pressure to the magnets and preventing them from separating from the rotor at operating speeds. For example, operating speeds may include high rotational speeds, which may require a higher preload because they result in higher centrifugal force.

[0090] The rotor assemblies described herein, though not limited to them, may be used in a variety of fields, including flywheels, automobiles, turbocharging, electric motors, and other fields. The disclosed embodiments may be applicable to fields involving high performance and high efficiency, such as high-performance vehicles (e.g., race cars). In another example, the disclosed embodiments may be applicable to the space sector, including rockets and vehicles for space exploration, where smaller, more compact engine specifications are preferred. Further non-limiting examples may include hobby vehicles (e.g., model aircraft or radio-controlled vehicles), industrial applications (e.g., automation or manufacturing robotics), wind turbines, surgical robotics or MRI machines, boat engines, and consumer electronics. As considered herein, the centrifugal force resulting from the rotation of the rotor can deflect mass, such as magnets, away from the rotor's axis of rotation. The disclosed embodiments may include a sleeve (e.g., sleeve 1104) that can hold the magnets and prevent them from separating from the rotor. The sleeve may be expandable and contractible, and its diameter may increase as multiple magnets are positioned along the circumference of the sleeve. In some embodiments, to prevent the magnets from separating from the rotor during rotation, the sleeve may exert a force sufficient to counteract centrifugal forces, such as centrifugal force, that are expected at the operating rotational speed. For example, as the sleeve stretches when the magnets are positioned in the sleeve, the tension in the sleeve may cause a force to be exerted on the magnets in the opposite direction (e.g., radially inward) to the centrifugal force (e.g., radially outward). The sleeve may exert force on the magnets by preloading them against the rotor. For example, the sleeve may exert force on the magnets, causing them to contact the rotor.

[0091] In some embodiments, the rotor assembly may include a plurality of tapered magnets. The tapered magnets may have dimensions that narrow, shrink, or gradually decrease in size. For example, a tapered magnet may have a first length or width and a second length or width, the second width or length being shorter than the first. In some embodiments, the amount of taper may be determined by the characteristics of the rotor assembly, such as the dimensions of the rotor, the required amount of sleeve expansion, and the amount of pressure or force to be generated in the sleeve. The angle or amount of taper may affect the amount of displacement along the circumference, and therefore the amount of sleeve stretching obtained when the magnets are positioned along the circumference in the sleeve. In some embodiments, the tapered magnets may include a taper angle (e.g., inclination) of 0.1 to 45 degrees. In some examples, the tapered magnets may include a taper angle on opposing faces of 7 degrees or less. As an example, the tapered magnet may have a trapezoidal shape with an inclination of 0.6 degrees. In some embodiments, the tapered magnet may include a 0.6-degree inclination on one surface or a 0.6-degree inclination on opposing surfaces. Multiple tapered magnets may include one or more permanent magnets. In some embodiments, the tapered magnets offer advantages including reducing the gap between magnets, thereby improving the balance of the rotor assembly.

[0092] In some embodiments illustrated in Figure 11, multiple magnets may be in contact with each other. For example, magnet 1102 may correspond to a first set of magnets and may contact magnet 1103 which may correspond to a second set of magnets. It will be understood that the tension in the sleeve 1104 applies pressure to magnet 1102, preventing magnet 1102 from separating from the laminated core 1108. For example, the tension in the sleeve 1104 may apply a preload or retaining force in the direction 1114 opposite to the direction of centrifugal force 1116. It will be understood that the disclosed embodiments including tension in the sleeve 1104 may reduce the use of adhesives such as glue, thereby enabling simpler assembly. For example, it will be understood that utilizing tension in the sleeve may provide a higher preload compared to the retention provided by adhesives, thereby improving the retention of the magnets. In some embodiments, one of the multiple magnets may be in contact with at least one other magnet.

[0093] Figures 12A and 12B illustrate isometric views of a rotor assembly consistent with embodiments of the present disclosure. In some embodiments, multiple magnets may be in contact with each other along the inner diameter of the sleeve. For example, the rotor assembly 1200 includes a first set of tapered magnets 1206A and a second set of tapered magnets 1208A. For example, the width of the first side surface 1205A may be greater than the width of the second side surface 1207A. The first side surface 1205A may be parallel to the second side surface 1207A. The first tapered side surface 1211A and the second tapered side surface 1209A may be inclined with respect to the first side surface 1205A and the second side surface 1207A. In some embodiments, the first tapered side surface 1211A and the second tapered side surface 1209A may form a tapered magnet such that the second side surface 1207A may be narrower than the first side surface 1205A. The magnets may be positioned along the inner diameter 1204A of the sleeve 1202A. In some embodiments, the direction of the taper in the tapered magnet 1206A may be opposite to the direction of the taper in the tapered magnet 1208A. In some embodiments, multiple tapered magnets may be inserted circumferentially from one another. Insertion circumferentially may involve arranging the magnets along the circumference of the sleeve. The magnet arrangement may be sized such that the arrangement fits inside the diameter of the sleeve before the magnets press against each other. For example, magnets 1206B and 1208B of the rotor assembly 1200B may be arranged inside the sleeve 1202B such that the magnets are distributed on the circumference 1203B of the sleeve. In some embodiments, magnet 1206B may represent pole magnets. For example, pole magnets may indicate the orientation of the magnetic poles of the magnets and may contribute to the main interaction between the stator and rotor (e.g., drive poles). In one example, magnet 1206B may include 14 pole magnets. In some embodiments, magnet 1208B may represent side magnets. For example, pole magnets may have a stronger magnetic force (e.g., attractive force) with the stator than side magnets, while side magnets provide the opposite force (e.g., repulsive force). The inclined or tapered sides of the first set of magnets 1206A may contact the inclined sides of the second set of magnets 1208A.In some embodiments, the tapered magnets may be wedge-shaped so that when tapered magnets facing opposite directions are in contact with each other, the magnets can cause displacement and stretch the sleeve 1202B. For example, magnet 1206B may have an opposite orientation to magnet 1208B, such that its narrow side is to the right of magnet 1206B and its narrow side is to the left of magnet 1208B. For example, the wider first side 1205A of magnet 1208A may be closer to the right end 1214A of sleeve 1202A. The narrower second side 1207A of magnet 1208A may be closer to the left end 1212A of sleeve 1202A. The wider first side 1216A of magnet 1206A may be closer to the left end 1212A of sleeve 1202A, and the parallel, narrower second side of magnet 1206A may be closer to the right end 1214A of sleeve 1202A.

[0094] In some embodiments, a plurality of tapered magnets may involve axial insertion of a first set of tapered magnets into a second set of tapered magnets. For example, the tapered magnets may be distributed along a circumference, and axial insertion of the tapered magnets may involve pushing the magnets toward the center of the sleeve. The magnets may be wedge-studded with each other. For example, magnet 1206A may be wedge-studded between a pair of adjacent magnets 1206B, and vice versa. In this arrangement, as each magnet (e.g., 1206A or 1206B) is inserted axially, the magnet exerts a force circumferentially on adjacent magnets of the same magnet having opposite taper, and as the opposing magnets push away from each other, an increase in the diameter of the magnet arrangement occurs, thereby stretching the sleeve 1202A and inducing tension in the sleeve. In some embodiments, the amount of strain allowed by the sleeve can help determine how much the sleeve can be stretched without breaking, and therefore can help determine the size of the sleeve (e.g., diameter) and the size of the magnets (e.g., length, width, taper angle). In some embodiments, a magnet insertion tool can guide the magnets along the insertion path while reducing the magnitude of the forces exerted by the magnets on each other. For example, in some embodiments, the tapered sides of adjacent magnets may come into contact as the magnets slide against each other, but may not press against each other with enough force to expand the sleeve. Instead, the expanding force may be applied by a magnet insertion tool guiding the magnets into position. In some embodiments, friction between magnets 1206B and 1208B can fix or lock the magnets in place. In some embodiments, it will be understood that inserting the magnets circumferentially using a prefabricated sleeve may provide higher achievable cylinder stress and pressure for holding the magnets compared to direct winding.

[0095] Figures 13A and 13B depict side views of a rotor assembly consistent with embodiments of the present disclosure. The rotor assembly 1300A may include a first plurality of magnets 1304A, surrounded by a sleeve 1302A, having a taper opposite to that of a second plurality of magnets 1308A. The disclosed embodiments may involve the second plurality of tapered magnets 1308A being positioned between adjacent pairs of the first plurality of magnets 1304A. For example, a tapered end 1305A corresponding to the first plurality of magnets 1304A may contact a tapered end 1307A corresponding to the second plurality of magnets 1308A. As considered herein, the plurality of magnets may be inserted axially. For example, the first plurality of magnets 1304A may be pushed axially 1306A toward the second plurality of magnets 1308A which are pushed axially 1310A. The first axial direction 1306A may be axially relative to the second axial direction 1310A by being in the opposite direction to the second axial direction 1310A along the same axis. The magnets may be positioned at a constant length in the axial direction and at a constant distance from the central axis on the rotor assembly. For example, the broad end of magnet 1304A may be positioned at a distance of 1312A from the axis 1311A of the rotor assembly 1300A such that the tapered magnets abut each other. Under this condition, the sleeve 1302A may have an unstretched diameter 1314A. When the tapered magnets are pushed toward each other, the axial distance 1312A may decrease. It will be recognized that when the tapered magnets are pushed toward each other, the wedge-shaped magnets are displaced toward each other in the circumferential direction, thereby increasing the diameter of the sleeve 1302A such that the stretched diameter 1314B of the sleeve 1302A is greater than the unstretched diameter 1314A. For example, magnets 1304B and 1308B may be inserted such that the wider ends of these magnets are at a reduced axial distance 1312B from the central axis 1311B. As a result, sleeve 1302B may expand and stretch in diameter so that sleeve 1302B reaches an expanded diameter 1314B, and consequently, a preload is generated in the sleeve. The expanded diameter 1314B may be an increase in diameter from the unexpanded diameter 1314A.In some embodiments, the rotor assembly 1300B may represent the position of the magnets during operation or in the operating configuration. It will be recognized that such a configuration of the rotor assembly may have improvements over a directly wound carbon fiber rotor assembly. For example, such a configuration may offer advantages including the ability to generate greater pressure or tension compared to a directly wound rotor assembly. A directly wound rotor assembly may also involve a hardening process, and changes in the components due to hardening can impair the preload from the winding. Additionally, a directly wound rotor assembly may involve a hardening process at high temperatures, which can be detrimental to the permanent magnets and may induce demagnetization.

[0096] Figure 14A illustrates a front view of a rotor assembly consistent with an embodiment of the present disclosure. The rotor assembly 1400A may include a sleeve 1402A and a magnet arrangement 1404A. In some embodiments, inserting tapered magnets along the circumference may expand the sleeve 1402A, as described herein. For example, inserting magnets along the circumference may expand the sleeve 1402A in direction 1406A such that the circumference of the sleeve 1402A expands.

[0097] In some embodiments, multiple tapered magnets include a crown. The crown may include a raised surface on the magnet. For example, the crown may include a raised surface on the upper surface of the magnet. In some embodiments, the crown abuts against the inner diameter of the sleeve. Figure 14B illustrates a partial front section view of a magnet assembly consistent with embodiments of the present disclosure. Magnet 1404B may include a crown 1410B on its outer circumferential surface 1412B. The crown 1410B may include a raised surface such that the thickness 1414B (e.g., radially) of magnet 1404B may be greater at the center 1416B than at the edge 1418B. The crown 1410B may abut against the inner diameter of the sleeve 1402A. The interaction between the crown 1410B and the sleeve 1402A may provide a locking function that can secure the magnet to the sleeve. For example, due to the increased height of the magnet in the center of the crown 1410B, the sleeve 1402A may stretch more in the center and have higher tension there. Therefore, the increased tension and friction may provide retention and prevent the sleeve 1402A from shifting. In some embodiments, the crown 1410B may contribute to meeting regulatory requirements by providing additional retention to the frictional retention of the sleeve.

[0098] In some embodiments, the rotor assembly may include a laminated core. The laminated core may include the core of an electric motor. In some embodiments, the laminated core may be made of a metal such as steel or iron. The laminated core may assist in the movement of magnetic flux between different poles on the stator or rotor. As considered herein, the laminated core may refer to a back iron, a steel core, or a steel laminate or laminated stack. For example, the rotor assembly 1100 includes a laminated core 1108, as referenced in Figure 11. As considered herein, the magnets in the rotor assembly may be in contact with or adjacent to the laminated core. In some embodiments, the magnets may have curved or flat surfaces that can contact the laminated core. For example, a plurality of tapered magnets 1404B may include magnets having flat sides 1406B and magnets having curved sides 1408B. The flat sides 1406B and the curved sides 1408B may be the inner diameters of the magnets that contact the outer diameter of the laminated core. A magnet having a curved side surface 1408B may include a curve, arch, or arc on the surface of the magnet that is in contact with the laminated core. A magnet having a flat side surface 1406B may assist in the transmission of torque from the magnet to the laminated core. For example, the rotation of the magnet and the preload generated by the sleeve may generate torque, which is transmitted from the flat side surface of the magnet to the laminated core, thereby coupling the magnet and the laminated core so that the rotation of the magnet induces the rotation of the laminated core. In some embodiments, the core may include magnets (e.g., laminated sheets including magnets embedded between or within sheets). In some embodiments, the rotor may not include a core. For example, the magnets of the rotor may be in contact with the hub rather than the laminated core. In some embodiments, the magnet may include one or more flat surfaces, flat edges, or flat faces, one or more curved faces, or any combination thereof, or a preferred shape such as flat and curved faces.

[0099] Figure 15 illustrates a top view of a laminated core consistent with an embodiment of the present disclosure. The disclosed embodiment may include flat sections 1504 on the outer diameter of the laminated core 1502. The flat sections 1504 may correspond to the number of magnets or poles in the rotor assembly. For example, there may be a number of flat sections corresponding to the number of tapered magnets arranged on the circumference of the rotor assembly. In some embodiments, the laminated core may include at least one notch. The notch may include an area from which material has been removed, such as a recess, cut, or notch. For example, the laminated core 1502 includes a triangular notch 1506 below the flat section 1504. In some embodiments, there may be reduced magnetic flux in the area of ​​the notch. Thus, metal may not be required in that area, and removing the metal may result in mass savings. Additionally, notches and notches may provide a torque transmission function from the rotor laminate to the rotor hub. In some embodiments, a flat magnet 1406B may contact a flat portion 1504 or otherwise interact with the outer diameter of the laminated core 1502, thereby transmitting torque from the magnet to the laminated core. Such a configuration, in which the flat side surface of the magnet abuts the flat side surface of the laminated core, can transmit torque. In some embodiments, the outer diameter of the laminated core abuts with at least some of the multiple magnets. For example, the outer diameter of the laminated core 1502 may abut with some of the multiple magnets 1102 or 1103, as referenced in Figure 11. At least some of the multiple magnets may include one or more magnets, or specific parts of magnets. For example, the laminated core 1502 may abut with the flat side surface of a magnet, as described herein. In some embodiments, the laminated core 1502 may abut with all of the magnets, such that the laminated core abuts with each of the multiple magnets, or the laminated core contacts a large portion of the surface of each of the multiple magnets. In some embodiments, the laminated core may not have notches. In some embodiments, the laminated core may have a preferred shape, such as one or more flat sides, an overall curved shape, a rounded shape, or any combination thereof.

[0100] In some embodiments, the rotor assembly may include a rotor hub. The hub may include a disk, a cover, or a central component. The hub may connect one or more components within the rotor assembly. For example, the hub may connect a bearing to the rotor. In some embodiments, the rotor hub may hold at least one of a laminated core, a plurality of tapered magnets, or a sleeve. Holding may involve preventing separation or movement, including restraining, surrounding, holding, fixing, fastening, and / or fixing. The hub may be made of a metal, including aluminum. In some embodiments, the rotor assembly may include one or more rotor hubs.

[0101] Figure 16 illustrates an exemplary embodiment illustrating a pair of rotor hubs consistent with embodiments of the present disclosure. For example, a rotor assembly may include a first rotor hub 1602 and a second rotor hub 1604. The first rotor hub 1602 may abut a first side surface of the laminated core, and the second rotor hub 1604 may abut a second side surface of the laminated core. In some embodiments, a rotor assembly including two rotor hubs may offer advantages including symmetry, improved thermal expansion, and improved dimensional consistency, which can improve manufacturability and assembly. Disclosed embodiments of rotor assemblies may allow for lower radial engagement, or contact, between the hubs and the laminated core. For example, embodiments including two rotor hubs may reduce contact between the rotor hubs and the inner diameter of the steel core, thereby allowing for a reduction in unnecessary material and mass. In some embodiments, placing a conductive metal such as aluminum adjacent to an electromagnetic field, such as an electromagnetic field within the laminate, may result in short circuits or eddy current losses, which can generate heat and reduce efficiency. The disclosed embodiments may minimize the interaction between the rotor hub and the lamination, thereby reducing vortex loss and improving efficiency. The rotor hub may include a hole 1608, which may allow the rotor hub to be fastened or connected to other components by dowel pins, rods, or screws, etc. Mounting components, including fastening or connecting as considered herein, may involve any preferred mounting means, such as dowel pins, rods, screws, bolts, or rivets. The first rotor hub 1602 and the second rotor hub 1604 may include projections 1606, 1610. The projections 1606, 1610 may help hold components of the rotor assembly. For example, as referenced in Figure 11, a projection 1110 on the rotor hub 1106 may hold the lamination core 1108, magnets 1102, 1103, and sleeve 1104. The protrusion 1110 extends from the rotor hub 1106 and can capture or mechanically engage with the laminated core 1108, magnets 1102, 1103, and sleeve 1104 to prevent them from being displaced, such as shifting axially during operation.In some embodiments, displacements such as magnet displacement can be detrimental to the operation of the electric propulsion system because the displacement may fatigue the sleeve or require rotor rebalancing. The projection 1110 may offer additional engagement and retention of components within the rotor assembly that can further prevent the components from separating or shifting away from the rotor, thereby providing better separation or shift prevention than relying solely on frictional forces.

[0102] In some embodiments, the rotor hub may include a torque transmission function. For example, the first rotor hub 1602 and the second rotor hub 1604 may include one or more protrusions such as projections 1612, 1614. The projections 1612, 1614 may be pins or raised surfaces on the outer diameter of the first rotor hub 1602 and the second rotor hub 1604. The projections 1612, 1614 may assist in transmitting torque to the rotor hub. For example, the projections 1612, 1614 may be linked to a notch 1506 on the laminated core 1502. The projections 1612, 1614 may be alignable with the notch of the notch 1506 so that the projections abut against the notch. Therefore, the laminated core 1502 can be coupled to the first rotor hub 1602 and the second rotor hub 1604 such that the rotation of the laminated core 1502 can induce rotation in the rotor hub due to contact between the notch 1506 and the protrusions 1612, 1614. For example, torque from the tapered magnet 1102 can be transmitted to the laminated core 1108, as shown in Figure 11. Contact at the linkage portion 1112 between the protrusion of the rotor hub 1106 and the notch of the laminated core 1108 can assist in transmitting torque from the laminated core 1108 to the rotor hub 1106.

[0103] Figures 17A to 17D illustrate cross-sectional views of a rotor assembly consistent with embodiments of the present disclosure. The rotor assembly 1700A may include a first rotor hub 1702A and a second rotor hub 1704A, which can enclose and hold the laminated cores 1706A and 1709A. For example, the first rotor hub 1702A may enclose the laminated core 1709A at a first coupling portion 1711A, and the second rotor hub 1704A may enclose the laminated core 1709A at a second coupling portion 1713A. The disclosed embodiments may include a gap, space, or isolation portion 1708B between the first rotor hub 1702A and the second rotor hub 1704A. It will be understood that a rotor hub that engages the magnet and the laminated core 1706A from two sides may provide better mechanical axial retention compared to retention from one side. In some embodiments, the rotor hub may provide a radial connection between the bearings and the laminated core. For example, rotor hub 1702A may have a first coupling portion 1708A with the laminated core 1709A, and rotor hub 1704A may have a second coupling portion 1710A with the laminated core 1709A, the coupling portion may enable torque transmission from the laminated core to the rotor hub, to the bearings, or to the input gear. In some embodiments, the rotor hub may have a separation portion or gap, such as a separation distance 1708B between the first rotor hub 1702B and the second rotor hub 1704B, which may allow the flow of a fluid such as a coolant. In some embodiments, the rotor hub may assist in bearing the load of a gyroscope. For example, increasing the separation distance 1708B between the first rotor hub 1702B and the second rotor hub 1704B may result in an increase in the second moment of area. The disclosed embodiments of the multiple rotor hubs may allow for easier adjustment of the rotor assembly, such as easier adjustment of the second moment of area over the connection to the input gear, while maintaining mass savings. For example, increasing the separation distance 1708B may result in a stronger rotor.

[0104] Figure 17C illustrates a cross-sectional view of a rotor assembly consistent with embodiments of the present disclosure. The rotor assembly 1700C may include a first rotor hub 1702C and a second rotor hub 1704C. The bearing 1714C and buttress 1716C may be substantially integrated into the sun gear 1712C. Substantially integrated may involve the bearing 1714C and buttress 1716C being surrounded by or housed within the sun gear 1712C. Such a configuration of the bearing 1714C within the sun gear 1712C may offer advantages including preventing the bearing 1714C from having to respond to loads such as loads resulting from tension or pressure in the sleeve 1703C, as such pressure or loads may reduce the size of the bearing's inner diameter. Rather, the disclosed embodiments may involve the magnet 1701C reacting to loads, as discussed herein. Accordingly, the disclosed embodiments can prevent deformation or reduction in the bearing's internal diameter, thereby ensuring consistent component fit during assembly. The magnet 1701C can be held on opposing ends or periphery portions of the rotor assembly 1700C. For example, the first rotor hub 1702C may hold the magnet on the first side surface 1705C of the rotor assembly 1700C, and the second rotor hub 1704C may hold the magnet on the second side surface 1707C of the rotor assembly 1700C, thereby providing improved retention for the magnet. In some embodiments, bolts 1718C extend through holes in the second rotor hub 1704C, the first rotor hub 1702C, and the sun gear 1712C, thereby allowing components to be mounted and connected. For example, bolt 1718C may mechanically connect the first rotor hub 1702C and the second rotor hub 1704C to the sun gear 1712C such that the movement or rotation of the rotor, and consequently the rotation of the rotor hub, results in the rotation of the sun gear. In some embodiments, the sun gear may be an input gear such that the rotation of the sun gear drives an input to a gearbox, including a planetary gearbox.For example, the torque path may extend from the rotor to the sun gear 1712C, to the planetary gear, and to the main shaft, which may be attached to the propeller. As described herein, the linkage between the magnet, the laminated core, and the rotor hub may assist in transmitting torque from the magnet to the sun gear.

[0105] Figure 17D illustrates an enlarged partial cross-sectional view of a rotor assembly consistent with an embodiment of the present disclosure. The rotor assembly 1700D may include a bearing 1714D housed within a sun gear 1712D, thereby preventing deformation of the bearing's bore due to load reaction, and thereby providing a consistent bore fit. Additionally, housing the bearing 1714D within the sun gear 1712D may reduce the use of boring, which may occur due to thermal expansion mismatches during assembly. The bearing 1714D may include rolling elements 1724D between the inner race 1720D and the outer race 1722D. In some embodiments, the first rotor hub 1702D and the second rotor hub 1704D may include holes for fastening. For example, a bolt 1718D may extend through the second rotor hub 1704D, the first rotor hub 1702D, and the sun gear 1712D so that the sun gear is attached to and coupled to the rotor hub. The Sun Gear 1712D may include a female bolt filament for securing the bolt 1718D, thereby eliminating the need for a nut.

[0106] The disclosed embodiments may involve a method for assembling a rotor assembly. The disclosed embodiments may include generating pressure in a prefabricated sleeve, as discussed herein. Generating pressure may involve inducing a preload by expanding the prefabricated sleeve. The prefabricated sleeve may include a sleeve such as carbon fiber wound on a mandrel. For example, carbon fiber may be wound on an aluminum cylinder as a mold under low tension. Curing the sleeve may involve high temperatures, followed by cooling and drawing the sleeve. Thus, by stretching the cured composite material, the load may be evenly distributed across the fibers, enabling higher tension or hoop stress. The disclosed embodiments may present improvements to the installation and stretching of the sleeve, such as stretching the sleeve onto the rotor. For example, a prefabricated sleeve may be expanded by inserting a magnet arrangement along its circumference. The magnet arrangement may include a first plurality of tapered magnets 1206A and a second plurality of tapered magnets 1208A, as referenced in Figure 12A. When the first plurality of tapered magnets 1206A and the second plurality of tapered magnets 1208A are pushed axially toward each other while enclosed by the sleeve 1202A, the sleeve 1202A may expand due to the tapered magnets acting as wedges toward each other. In some embodiments, each magnet of the first plurality of magnets, as well as each magnet of the second plurality of magnets, may be pressed toward each other simultaneously. In some embodiments, the prefabricated sleeve may allow the use of a wider variety of resins or curing processes, as it can avoid limitations resulting from exposing temperature-sensitive magnets to higher curing temperatures. Thus, the prefabricated sleeve may allow for shorter curing times and reduced cycle times. The prefabricated sleeve may offer greater flexibility in selecting materials, such as highly characterized materials, which may simplify the regulatory approval process.

[0107] Figures 18A–18F illustrate the assembly process of a rotor assembly consistent with embodiments of the present disclosure. The magnet arrangement assembly 1802A may include tapered magnets 1801A inserted into an expanded sleeve 1803A. The disclosed embodiments may involve the insertion of a laminated core. For example, a laminated core 1804A may be inserted into the magnet assembly arrangement 1802A by press-fitting or the like, thereby forming a torque ring assembly 1806B, as referenced in Figure 18B. Press-fitting may involve tolerance adjustments for various components. In some embodiments, the laminated core 1804A may be inserted into the magnet assembly configuration by stretching the sleeve. As considered herein, pushing tapered magnets against each other can stretch the sleeve and increase its diameter. In some embodiments, during assembly, the magnets may be pushed against each other by a distance greater than the distance they are pushed against each other during operation, so that the sleeve stretches to a diameter greater than the stretched diameter during operation. For example, referring to Figure 13B, during assembly, magnet 1304B may be pushed against magnet 1308B such that the magnet has an axial length smaller than the axial length 1312B. As a result, as the magnets are pushed further against each other, the amount of contact on the tapered surfaces of the magnets increases, thereby increasing the amount of expansion in the sleeve so that the sleeve has a diameter larger than the stretched diameter 1314B. The laminated core 1804A can then be inserted into the magnet assembly arrangement 1802A, which has an expanded diameter (e.g., beyond its operating diameter). Thus, in some embodiments, the laminated core 1804A can be inserted without shrink-fitting the laminated core. Once inserted, the magnets may be pushed by an amount of axial displacement during operation. Thus, as the amount of contact on the tapered surfaces of the magnets decreases, the amount of expansion, i.e., the diameter of the sleeve, may decrease. As a result, the sleeve and magnet arrangement can apply tension to the laminated core and thus be fixed or coupled to the laminated core.

[0108] In some embodiments, the outer diameter 1805A of the laminated core 1804A may abut the inner diameter 1807A of the magnet assembly arrangement 1802A. The disclosed embodiments may involve mounting at least one rotor hub to the laminated core. For example, referring to Figure 18B, a first rotor hub 1808B may be mounted to the first side 1807B of the torque ring assembly 1806B, and a second rotor hub 1810B may be mounted to the second side 1809B of the torque ring assembly 1806B, thereby forming a rotor assembly 1812C as referenced in Figure 18C. Mounting may involve heat fitting, such as shrinking the aluminum hub using liquid nitrogen. For example, the hub may be position-aligned with the steel core or placed within the steel core, heated to expand, mounted on the steel core, and cooled to operating temperature. The disclosed embodiments may involve balancing the rotor assembly. In some embodiments, the rotor may be unbalanced, such as having an uneven mass distribution or an inconsistent weight distribution. It will be recognized that an unbalanced rotor can shorten rotor life, reduce efficiency, and increase vibration. In some embodiments, the rotor assembly 1812C may be balanced by machining off material or by machining off added material to correct the imbalance. For example, material such as rivets may be added to the rotor where additional mass is needed for a uniform weight distribution, or material may be subtracted from the rotor.

[0109] Figures 18D–18F illustrate the assembly process of a rotor assembly consistent with embodiments of the present disclosure. The disclosed embodiments may involve inserting bearings into the sun gear. For example, referring to Figure 18D, the buttress 1816D and bearing 1818D may be pressed or press-fitted into the sun gear 1814D, thereby forming the input gear assembly 1815E, as referenced in Figure 18E. The buttress 1816D may assist in reacting to axial loads. The disclosed embodiments may involve mounting the sun gear to at least one rotor hub. For example, the input gear assembly 1815E may be mounted to the rotor assembly 1812E, as referenced in Figure 18F, to form the rotor gear assembly 1822F. The input gear assembly 1815E may be mounted to the rotor assembly 1812C by bolts 1820E. For example, bolt 1820E may extend through holes in the second rotor hub 1810B, the first rotor hub 1808B, and hole 1817D in the input gear assembly 1815E to integrally mount and join components. In some embodiments, the rotor gear assembly 1822F may be balanced by adding rivets, magnetizing, etc. It will be understood that the disclosed embodiments may involve assembly or manufacture via any preferred method, including press-fit, press-fit, heat-fit, shrink-fit, or form-fit.

[0110] Figure 19 illustrates an exploded view of a rotor assembly consistent with an embodiment of the present disclosure. The rotor assembly 1900 may include a bearing 1906 and a buttress 1904, both of which may be housed within a sun gear 1902. A sleeve 1910 may hold a magnet arrangement 1909, and a laminated core 1912 may be inserted such that the outer diameter of the laminated core abuts the inner diameter of the magnet arrangement 1909. A first rotor hub 1914 and a second rotor hub 1908 may be attached to the laminated core, such as by heat fitting. Bolts 1916 fasten the rotor assembly 1900 by fastening the first rotor hub 1914 to the second rotor hub 1908 and the sun gear 1902, thereby joining the laminated core 1912 and the magnet arrangement 1909 due to press-fit and shrink-fit, as described herein.

[0111] Figure 20 illustrates a cross-sectional view of a rotor assembly consistent with embodiments of the present disclosure. The magnet 2004 may be arranged around the inner diameter of the sleeve 2002. In some embodiments, the magnet 2004 may be tapered and inserted circumferentially so that the sleeve 2002 stretches and generates pressure on the magnet 2004. A laminated core 2006 may be in contact with the magnet 2004, and a first rotor hub 2010 and a second rotor hub 2008 may be mounted on the laminated core 2006. The rotor hubs may include protrusions such as a projection 2012 on the first rotor hub 2010, the projection 2012 may help hold the laminated core 2006, the magnet 2004, and the sleeve 2002. Bolts 2020 may fasten the sun gear 2014 to the first rotor hub 2010 and the second rotor hub 2008. The buttress 2016 and bearing 2018 may be housed within the sun gear 2014 so that the load may be reacted to by the magnet 2004 rather than the bearing 2018. The laminated core 2006 may include a triangular notch 2022, as discussed herein.

[0112] Figures 21A and 21B illustrate cross-sectional views of alternative rotor assemblies consistent with embodiments of the present disclosure. The rotor assembly 2100A may include magnets 2102A held by sleeve 2104A. The rotor hub 2106A may be in contact with sun gear 2108A and bearing 2110A. In some embodiments, magnets 2102B may be radially positioned and enclosed by sleeve 2014B.

[0113] It will be recognized that during the operation of the rotor assembly, the magnets may experience high heat or temperature increases that may be detrimental to their performance or efficiency. For example, high temperatures may result in demagnetization. The disclosed embodiments may involve cooling of the magnets within the rotor. The magnets may be cooled through heat exchange or heat transfer, such as convection. In some embodiments, a fluid, such as a coolant, may provide cooling by exchanging heat with the tapered magnets. In non-limiting examples, the fluids and coolants may include air, glycerol, and oil. In some embodiments, the fluid used to cool the magnets may also be used as a lubricant in the electric propulsion system. In some embodiments, the magnets may be cooled indirectly. Indirect cooling may involve cooling in which the coolant does not come into contact with the magnets. For example, fluid 2112A may be directed toward the rotor hub 2106A, as referenced in Figure 21A. Fluid 2112A may indirectly cool magnet 2102A by coming into contact with the rotor hub 2106A and providing heat exchange through the rotor hub 2106A. For example, the fluid 2112A may come into contact with the rotor hub 2106A, and the rotor hub 2106A may be press-fitted with the laminated core 2107A. Thus, heat exchange can be transmitted to the rotor hub 2106A, the laminated core 2107A, and the magnet 2102A.

[0114] The disclosed embodiments may include at least one cavity disposed between a plurality of tapered magnets and a laminated core. The cavity may include a space such as a gap, hole, passage, outlet, or chamber. For example, the space between the magnets of a plurality of tapered magnets and the laminated core may form a cavity. In some embodiments, the cavity may be a gap between the laminated core and the magnets having a curved surface, as described herein. In some embodiments, the cavity may be configured to guide a fluid for cooling. Being configured to guide a fluid may involve directing the movement of a fluid such as oil. For example, the cavity may guide a fluid by directing the fluid toward the magnets. As an example, the cavity may be small, such as having a diameter or height of 200 microns.

[0115] Figure 22 illustrates a cross-sectional view of a rotor assembly consistent with embodiments of the present disclosure. The rotor assembly 2200 may include a laminated core 2210 in contact with tapered magnets 2208, which may be held by a sleeve 2205. In some embodiments, a fluid such as oil may be distributed throughout the electric propulsion system. For example, oil may be distributed to a sun gear 2212 or a bearing 2214 to provide lubrication. It will be recognized that the rotor and sun gear 2212 rotate, thereby imparting centrifugal force to the oil. For example, oil flowing adjacent to the sun gear 2212 or a bearing 2214 may be subjected to centrifugal force and directed toward the rotor hub. The centrifugal force may drive the oil into the gap 2201 between a first rotor hub 2216 and a second rotor hub 2218, or it may cause the oil to move toward the laminated core 2204. For example, oil may move in a gap provided by the separation distance 1708B between the first rotor hub 1702B and the second rotor hub 1704B, as referenced in Figure 17B. In some embodiments, a laminated core or at least one cavity may allow direct cooling of multiple tapered magnets. Direct cooling may involve heat transfer when a fluid, such as a coolant, comes into contact with the magnets. For example, direct cooling may involve the magnets exchanging heat with oil that comes into contact with them. In some embodiments, the laminated core 2210 may include walls 2220 and 2222 such that the oil forms an oil collection, such as a pool 2224, as the oil moves in a direction 2204 toward the laminated core 2210. Centrifugal force or pressure may drive the oil from the pool through an opening 2226 to the cavity 2202. In some embodiments, the opening 2226 may be provided to allow the flow of a fluid, such as a coolant. For example, the opening 2226 may be a leak path or hole through which pressure drives the movement of oil into the cavity 2202. The cavity 2202 may be located between the magnet 2208 and the laminated core 2210. Oil may be present in the cavity 2202 so that it can come into contact with the magnet 2208 and provide cooling.For example, the oil may be in direct contact with the magnet 2208 to provide heat exchange. In some embodiments, centrifugal force may drive the oil in direction 2206 so that it contacts different parts of the magnet 2208, such as the side or axial surfaces of the tapered magnet 2208, and the end faces or inner diameter faces, thereby increasing the surface area of ​​the magnet that receives heat transfer. It will be understood that a laminated core and cavity that allows direct cooling of the magnet improves cooling and heat transfer. For example, as the oil moves through the opening, the oil is a fluid flowing through a small area, which can have a high velocity and may result in an increased heat transfer coefficient. Additionally, compared to indirect cooling, directly applying oil to a portion of the magnet 2208 may increase the amount of surface area of ​​the magnet that receives heat transfer, and therefore may result in an increased amount of heat transfer. Furthermore, direct cooling may reduce the thermal impedance when the oil exchanges heat with the magnet rather than conducting heat through other components. In some embodiments, a fluid such as oil may return from the cooling magnet 2208 to a distribution channel or reservoir through leak paths, cavities, or holes in the laminated core 2210.

[0116] Figures 23A and 23B illustrate front views of a rotor assembly consistent with embodiments of the present disclosure. In some embodiments, the rotor assembly 2300A may include one or more cavities 2302A distributed along the circumference. For example, a cavity could be an oil outlet such as a cavity 2302B located between several portions of the laminated core 2304B and a tapered magnet 2306B. The tapered magnet 2306B may include an inner diameter surface 2308B that is in direct contact with the oil in the cavity 2302B. For example, the inner diameter surface 2308B may include a curved side or curved surface 1408B, as referenced in Figure 14B. In some embodiments, the cavity 2302B may include a space between the laminated core 2304B and the magnet having the curved surface 1408B, as referenced in Figure 14B. Since cavities can exist between the laminated core and the curved magnets, it will be understood that torque transmission can also be provided through flat surfaces such as the magnet 1406B that can contact the laminated core 2304B.

[0117] Some disclosed embodiments may involve the manufacture (e.g., assembly) of a rotor assembly, which may involve the use of various tools. It will be understood that the manufacture of a rotor assembly may involve an assembly of magnet rings, which may achieve a high amount of tension (e.g., preload) in the retaining sleeve to hold the magnets during operation. For example, the magnet rings may refer to a magnet placement assembly 1802A, as referenced in Figure 18A, and may include tapered magnets 1801A inserted into an expanded sleeve 1803A. Thus, it will be understood that the disclosed embodiments of rotor assembly manufacture may be configured to produce a rotor assembly having sufficient tension as described herein without degrading the strength of the rotor assembly (e.g., by chipping the magnets or damaging the sleeve). It will be further understood that the disclosed embodiments of rotor assembly manufacture are not limited to tapered magnets. In some embodiments, the magnets include an axial taper, as referenced in Figure 12A. In some embodiments, the magnets may include multiple tapers, such as an axial taper, and one or more radial tapers in the sleeve. In some embodiments, the magnets may be rectangular with linear edge contacts between them (e.g., without axial taper).

[0118] In some embodiments, the manufacturing of a rotor assembly may involve a magnet insertion tool. The magnet insertion tool may assist in providing support and various movements for assembling the magnets into a given design. In some embodiments, the magnet insertion tool may include tools such as a press and a mandrel. For example, Figures 24A–24G illustrate a mandrel and mandrel components for manufacturing a rotor assembly consistent with embodiments of the present disclosure.

[0119] Figures 24A–24G illustrate a mandrel for a magnet insertion tool consistent with embodiments of the present disclosure. The expansion mandrel 2400A may be any mandrel (e.g., an arbor) for supporting and / or holding components during manufacturing. The expansion mandrel 2400A may be configured to fix or guide components while expanding and contracting radially from the position alignment shaft 2404A. For example, the expansion mandrel 2400A may be configured to move between a retracted state and an expanded state. For example, in the retracted state, the expansion mandrel 2400A may have a retracted mandrel diameter 2402A between the opposing outer surfaces of the push bars 2408A or 2410A, and in the expanded state, it may have a larger expanded diameter. The expansion mandrel 2400A may include a position alignment shaft 2404A which can help maintain radial position alignment of components during manufacturing. The position alignment shaft 2404A may be keyed such that it includes a groove 2406A, which may help lock the position alignment shaft 2404A to components of the expansion mandrel 2400A, such as a guide plate and / or support plate. In some embodiments, the expansion mandrel 2400A may include push bars for transmitting force and movement to rotor assembly components such as magnets. For example, the push bars may include metal and may expand from and retract to a retracted mandrel diameter 2402A. The expansion mandrel 2400A may include push bars according to a predetermined magnet configuration, such as a magnet ring configuration as described herein. For example, a first push bar 2408A may correspond to a first set of tapered magnets, and a second push bar 2410A may correspond to a second set of tapered magnets. In some embodiments, the tapered magnets of the first set may be larger than those of the second set, and similarly, the first push bar may be larger in the circumferential direction than the second push bar. For example, in some embodiments, the tapered magnets of the first set may include the pole magnets of the rotor assembly, while the tapered magnets of the second set may include the side magnets of the rotor assembly, which may be smaller than the pole magnets.Accordingly, in some embodiments, the first push bar 2408A may include a pole push bar 2408A configured to act on the pole magnet as a first set of tapered magnets, and the second push bar 2410A may include a side push bar configured to act on the side magnet as a second set of tapered magnets. Thus, the first and second push bars 2408A and 2410A may sometimes be referred to as the pole push bar 2408A and the side push bar 2410A, respectively. In some examples, a position matching shaft 2404A may extend through the length of the push bars in the extension mandrel 2400.

[0120] Figures 24B and 24C illustrate push bars for an expansion mandrel consistent with embodiments of the present disclosure. Figure 24B may illustrate a side magnet push bar 2410B, and Figure 24C may illustrate a pole magnet push bar 2408C for an expansion mandrel 2400A. In some embodiments, manufacturing a rotor assembly may involve the use of tapered surfaces on or in components of a magnet insertion tool. For example, components of a magnet insertion tool may include tapers configured to perform insertion movements, including the movement of the expansion mandrel 2400A during expansion. The side magnet push bar 2410B may include a first taper 2412B and a second taper 2414B, and the pole magnet push bar 2408C may similarly include a first taper 2412C and a second taper 2414C. The magnet insertion tool may also have a function that can assist in the positional alignment and positioning of components, for example, by guiding the components during expansion and / or retraction. For example, the side magnet push bar 2410B may include a pocket 2416B (and the pole magnet push bar 2408C may include a pocket 2416C) for guiding the push bar radially during operation while constraining the push bar in the axial and circumferential directions. The pocket may refer to any slot or recess, such as a partially hollowed portion of the push bar. In another example, the side magnet push bar 2410B may include a stop surface 2418B along the inner side surface 2422B, and the pole magnet push bar 2408C may include a stop surface 2418C along the inner side surface 2422C. In some embodiments, the side magnet push bar 2410B may include an outer side surface 2420B, which may be the outer surface of the expansion mandrel 2400, and the pole magnet push bar 2408C may similarly include an outer surface 2420C. In some embodiments, push bars may be configured to push, drive, or otherwise propel magnets to assist in assembling them into a configuration. For example, a pole magnet push bar 2408C may be configured to push a first group of magnets, such as pole magnets, and a side magnet push bar 2410B may be configured to push a second group of magnets, such as side magnets.In some embodiments, the push bar may push one or more components configured to support or hold a magnet, such as keys 2510B and 2510C, which are discussed below.

[0121] Figure 24D illustrates a vertical cross-section 2400D of an expansion mandrel 2400A for a magnet insertion tool, consistent with embodiments of the present disclosure. Cross-section 2400D may be a cross-section passing through the pole push bar 2408B. As described herein, the magnet insertion tool may include components for guiding the movement of the push bar, such as a push bar guide plate 2422D and a stop plate 2424D. The push bar guide plate 2422D may, in conjunction with the inner side surface 2420D of the pole push bar 2408B, provide position alignment during expansion and / or retraction. The stop plate 2424D may, in conjunction with the inner side surface 2420D of the pole push bar 2408B, provide a stopping point for retraction (e.g., an expansion starting point). In some examples, the guide plate 2422D and the stop plate 2424D may be linked to an inner side surface 2420D away from the first taper 2412D and the second taper 2414D. The position alignment shaft 2404D may extend through one or more guide plates 2422D and stop plates 2424D inside the ring formed by the pole magnet push bar 2408D and the side magnet push bar 2410D. In some embodiments, the position alignment shaft 2404D may be configured to position-align one or more push bar guide plates and / or stop plates. For example, the push bar guide plate 2422D may be concentric with the position alignment shaft 2404D so that the push bar guide plate 2422D remains position-aligned with the position alignment shaft 2404D.

[0122] Figure 24E illustrates guide plate 2422E and stop plate 2424E consistent with embodiments of the present disclosure. Guide plate 2422E may include linkages for positional alignment of components such as slots or notches. For example, pole slot 2426E may link with pocket 2416C of pole push bar 2408C. In another example, side slot 2428E may link with pocket 2416B of side push bar 2410B. Pole push bar 2408C may slide radially along pole slot 2426E of guide plate 2422E during expansion. In some embodiments, linkage between guide plate 2422E and either pole slot 2426E or side slot 2428E of the push bar may reduce unwanted vertical movement of the push bar (e.g., vertical movement relative to the positional alignment shaft). Stop plate 2424E may provide a stopping point for the retraction of the push bar. For example, the inner side surface 2420D of the pole push bar 2408B may contact the surface 2430E of the stop plate 2424E during retraction. Referring to Figure 24D, the guide plate 2422D and the stop plate 2424D may be stacked to provide additional position alignment and guidance.

[0123] Figure 24F illustrates an expansion mandrel 2400 in a retracted configuration 2430F, and Figure 24G illustrates an expansion mandrel 2400 in an expanded configuration 2430G consistent with embodiments of the present disclosure. For example, the side push bar 2410G and pole push bar 2408G in the expanded configuration 2430G may be extended to an expanded diameter 2432G, which may be larger than the retracted diameter 2402F of the side push bar 2410F and pole push bar 2408F in the retracted configuration 2430F. The pole push bar 2408G may be further displaced along slot 2426G in the expanded configuration 2430G compared to the pole push bar 2408F along slot 2426F.

[0124] Figures 25A to 25F illustrate first figures of further components of a magnet insertion tool consistent with embodiments of the present disclosure, and a method for manufacturing a rotor assembly. Figure 25A illustrates step 2500A, which may involve loading a support plate 2502A onto a tapered cone 2504A. The tapered cone 2504A may be any structure having an inclined edge. In some embodiments, the tapered cone 2504A may have a taper that can match the taper of a push bar described herein. The taper of the tapered cone 2504A may be in conjunction with the taper of one or more of the push bars. For example, the tapered cone 2504A may have an inclination angle complementary to one or more of the angles of the first taper 2412B, the second taper 2414B, the first taper 2412C, or the second taper 2414C, respectively, with reference to Figures 25B and 25C. In some embodiments, the inclination (e.g., angle) of the taper in the tapered cone 2504 may be such that the axial movement of the sleeve is proportional to or equal to the radial expansion of the sleeve. In some embodiments, as described herein, the taper of the tapered cone and / or the taper of the push bar may be proportional to the taper of the tapered magnet.

[0125] Figure 25B illustrates step 2500B, which may involve loading an expansion mandrel 2506B onto the support plate 2502B. The expansion mandrel 2506B may be similar to, for example, the expansion mandrel 2400A referenced in Figure 24A. In some examples, a position-aligning shaft 2508B may extend through the support plate 2502B.

[0126] Figure 25C illustrates step 2500C, which may involve loading the first plurality of magnets 2512C. In some embodiments, the first plurality of magnets 2512C may refer to one or more side magnets as described herein. In some embodiments, the first plurality of magnets 2512C may refer to one or more pole magnets. The first plurality of magnets 2512C may be pushed by push bars corresponding to the magnets. For example, push bar 2514C may be a side magnet push bar when the first plurality of magnets 2512C includes side magnets. In another example, push bar 2514C may be a pole magnet push bar when the first plurality of magnets 2512C includes pole magnets. In some embodiments, the first plurality of magnets 2512C may be supported by one or more keys 2510C. A key may refer to any component that can support the magnets, such as by holding and / or fixing the magnets. For example, key 2510C may seat in a slot 2516C of a support plate 2502C (e.g., a base). The slot may be configured to allow radial movement of key 2510C relative to the support plate 2502C. For example, during expansion, the magnet insertion tool may involve pushing the first plurality of magnets radially outward (relative to the support plate 2502C) so that key 2510C, including the first plurality of magnets 2512C, slides along the slot 2516C. In other examples, the plurality of magnets may be in direct contact with a push bar. For example, in some embodiments, the first plurality of magnets 2512C may remain axially stationary during assembly. In such cases, relative axial sliding movement between the push bar 2514C and key 2510C may not be required, and the two components may be manufactured as a single unit. In some embodiments, if several magnets remain stationary in the axial direction and the first and second sets of magnets are not of equal size, it may be desirable for the larger magnet to remain stationary. This can minimize wear or strain on the inner surface of the sleeve during insertion.

[0127] In some embodiments, the second set of magnets may include the same number of magnets as the first set of magnets. In some embodiments, the second set of magnets may include a different number of magnets than the first set of magnets. For example, the second set of magnets may have, for example, half or one-third the number of magnets as the first set of magnets, or the second set of magnets may have two or one magnet. It will be recognized that as the number of inserted magnets (e.g., or the total surface area facing the sleeve along the circumference of the inserted magnets) decreases, the stretching of the sleeve may become uneven, and the risk of fault points in the sleeve (e.g., buckling of the sleeve) may increase.

[0128] Figure 25D illustrates step 2500D, which may involve loading sleeve 2518D. In some embodiments, sleeve loading may be performed after loading the first plurality of magnets. In some embodiments, sleeve loading may be performed after loading the first plurality of magnets and the second plurality of magnets. Sleeve 2518D may represent any sleeve described herein, such as sleeve 1202A, as referenced in Figure 12A. For example, sleeve 2518D may contain carbon fiber. In some examples, sleeve 2518D may be loaded into the magnet insertion tool by loading the sleeve onto the first plurality of keys 2512D. In some embodiments, the expansion mandrel 2506D may be in a retracted configuration when the sleeve is loaded. Keys such as key 2510D may support the sleeve and prevent the sleeve from falling axially.

[0129] Figure 25E illustrates step 2500E, which may involve loading a second plurality of magnets 2520E. In some embodiments, the second plurality of magnets 2520E may refer to one or more side magnets as described herein. In some embodiments, the second plurality of magnets 2520E may refer to one or more pole magnets. The second plurality of magnets 2520E may be pushed by push bars corresponding to the magnets. In some embodiments, the second plurality of magnets 2520E may be supported by one or more keys 2522E. The second plurality of magnets 2520E may be loaded such that the second plurality of magnets 2520E may be radially inward (e.g., on the inner diameter) of the sleeve 2518E. For example, the second plurality of magnets 2520E may be partially inserted into the sleeve 2518E and the first plurality of magnets.

[0130] Figure 25F illustrates step 2500F, which may involve loading the upper plate and performing an insertion movement. The insertion movement may be any movement, motion, or operation of the components for manufacturing the rotor assembly. In some embodiments, the insertion movement may refer to the movement of one or more sets of magnets. In some embodiments, the insertion movement may refer to a component that can be configured to hold the magnets. The insertion movement may include the movement of a key containing magnets. In one example, the insertion movement may involve moving the key 2510F (e.g., corresponding to a first set of magnets) toward the sleeve 2518F, such as by pressing the lower plate 2526E. In another example, the insertion movement may involve moving the key 2522F (e.g., corresponding to a second set of magnets) axially toward the sleeve 2518F, such as by pressing the upper plate 2524F. In an additional example, the insertion movement may involve moving both keys 2510F and 2522F, for example, by pressing both the upper plate 2524F and the lower plate 2526F (for example, simultaneously).

[0131] Figures 26A and 26B illustrate keys for a magnet insertion tool consistent with embodiments of the present disclosure. Figure 26A illustrates a first magnet key 2600A consistent with embodiments of the present disclosure. In some embodiments, the first magnet key 2600A may include one or more magnets from a first plurality of magnets. For example, the first magnet key 2600A may hold one or more pole magnets, and a set of first magnet keys 2600A may correspond to a set of pole magnets. The first magnet key 2600A may include a load surface 2602A, which may be the surface of the key 2600A configured to support the z-axis (e.g., axial) load of the magnet during insertion. The first magnet key 2600A may also include an outer surface 2604A, which may be the surface configured to support the back surface (e.g., a flat surface) of the magnet. In some examples, the load surface 2602A may extend radially further than the outer surface 2604A. For example, the outer surface 2604A may be recessed relative to the load surface 2602A. The first magnetic key 2600A may include an inner surface 2606A. For example, the inner surface 2606A may be a surface that is in contact with the push bar of the magnet insertion tool (e.g., a polar magnet push bar) such that the movement of the expansion mandrel acting on the push bar can move the first magnetic key 2600A (e.g., exert a force on the first magnetic key 2600A). The first magnetic key 2600A may also include a bottom surface 2608A that can move along the lower support plate during expansion and / or contraction of the mandrel, such as inside the slot 2516C discussed above.

[0132] Figure 26B illustrates a second magnetic key 2600B consistent with embodiments of the present disclosure. In some embodiments, the second magnetic key 2600B may include one or more magnets from a second plurality of magnets. For example, the second magnetic key 2600B may hold one or more side magnets, and a set of second magnetic keys 2600B may correspond to a set of side magnets. The second magnetic key 2600B may include a load surface 2602B, which may be a surface of the key 2600B that sets the height of the magnet relative to the sleeve and can provide axial load support during insertion. The second magnetic key 2600B may also include an outer surface 2604B, which may be a surface configured to support the back surface (e.g., a flat surface) of the magnet. In some examples, the load surface 2602B may extend radially further than the outer surface 2604B. For example, the outer surface 2604B may be recessed relative to the load surface 2602B. The second magnetic key 2600B may include an inner surface 2606B. For example, the inner surface 2606B may be a surface in contact with the push bar of the magnet insertion tool (e.g., a side magnet push bar) so that the movement of the expansion mandrel acting on the push bar can move the second magnetic key 2600B (e.g., apply force to the second magnetic key 2600B). The second magnetic key 2600B may also include an upper surface 2610B that can move along the upper support plate (e.g., in a slot in the upper support plate) during the expansion and / or contraction of the mandrel. In some examples, the second magnetic key 2600B may be held and / or supported by dowel pins and by a locking mechanism or ring support structure of the upper support plate.

[0133] Figures 27A–27G illustrate a second diagram of further components of the magnet insertion tool consistent with embodiments of the present disclosure, and a method for manufacturing a rotor assembly. Figure 27A illustrates step 2700A of an apparatus and method for manufacturing a rotor assembly. In some embodiments, the axial direction 2701A may refer to the axial direction of the sleeve (e.g., along the axis of the position-aligning shaft 2705A), and the radial direction 2703A may refer to the radial direction of the sleeve (e.g., along the radius of the position-aligning shaft 2705A). In some embodiments, the magnet insertion tool described herein may include an upper tool portion 2702A and a lower tool portion 2704A. However, the disclosed embodiments of the magnet insertion tool are not limited in this respect, and the magnet insertion tool may be illustrated with the upper tool portion and the lower tool portion for ease of illustration. In some embodiments, the lower tool portion 2704A may include an extension mandrel 2706A, which may include a first plurality of push bars 2708A that are in contact with a first plurality of magnetic keys 2710A. In one example, the first plurality of magnetic keys 2710A may be configured to hold a first plurality of magnets, such as a plurality of polar magnets (for example, the magnetic keys 2710A may be polar magnet keys). In some embodiments, the first plurality of magnetic keys 2710A may slide against the surface of the first plurality of push bars 2708A. For example, the inner surface of a magnetic key may be in contact with the outer surface of a push bar and may slide along the outer surface of a push bar. A second plurality of push bars 2712A may be in contact with a second plurality of magnetic keys 2714A that may be attached to the upper tool portion 2702A. In one example, a second set of multiple magnetic keys 2714A may be configured to hold a second set of multiple magnets, such as a set of multiple side magnets (for example, the magnetic key 2714A may be a polar magnet key). In some embodiments, the second set of multiple magnetic keys 2714A may slide against the surface of a second set of multiple push bars 2712A. Since the key containing the magnets may slide along the push bar and / or the push bar during the movement of the key, it will be understood that the magnet insertion tool can reduce the amount of frictional force exerted on the magnets themselves, thereby protecting the integrity of the magnets.For example, key 2714A can expand the sleeve diameter to a diameter slightly larger than the diameter that would result from the insertion of the magnet alone. This can allow the magnet to slide into place without applying excessive force to its surface. When the expansion mandrel retracts again, the sleeve can contract to its final diameter, holding the magnet in place.

[0134] In some embodiments, the lower tool portion 2704A may include a support plate 2716A configured to support a first plurality of magnetic keys 2710A. For example, the magnetic keys 2710A may be seated in slots in the support plate 2716A so that the support plate 2716A can support the load of the magnetic keys 2710A in the axial direction 2701A. In addition, the magnetic keys 2710A may be configured to move radially 2703A relative to the support plate 2716A. For example, during expansion and / or contraction, the magnetic keys 2710A may slide along the slots in the support plate 2716A (e.g., relative to the surface of the support plate 2716A). In some embodiments, the upper tool portion 2702A may include a support plate 2720A configured to support a second plurality of magnetic keys 2714A. For example, the magnetic key 2714A may be positioned in a slot in the support plate 2720A so that the support plate 2720A can support the load of the magnetic key 2714A in the axial direction 2701A. In another example, the magnetic key 2714A may be supported by a support ring as described herein. The upper tool portion 2702A may be configured to hold the magnetic key 2714A when suspended over the lower tool portion 2704A. In addition, the magnetic key 2714A may be configured to move radially 2703A relative to the support plate 2720A. For example, during expansion and / or contraction, the magnetic key 2714A may slide or move along the slot in the support plate 2720A.

[0135] Figure 27B illustrates step 2700B of an apparatus and method for manufacturing a rotor assembly. In one example, the upper tool portion 2702B may be separated from the lower tool portion 2704B. Some disclosed embodiments may involve loading a first plurality of magnets into a magnet insertion tool. For example, magnets of the first plurality of magnets 2722B may be loaded onto a first plurality of keys 2710B. The keys 2710B may support the magnets 2722B axially 2701B (e.g., supporting the load of the magnets) and / or support the back surface of the magnets 2722B. In some embodiments, the first plurality of magnets 2722B may be polar magnets. In some embodiments, the insertion movement may involve moving the first plurality of magnets 2722B radially 2703B. For example, the expansion mandrel 2706B may be configured to move a first plurality of push bars 2708B that are in contact with a first plurality of keys 2710B, thereby moving the magnet 2722B radially 2703B. In some embodiments, the first plurality of magnets may be tapered along the axial direction 2701B. In some embodiments, the first plurality of magnets 2722B may be side magnets.

[0136] Figure 27C illustrates step 2700C of an apparatus and method for manufacturing a rotor assembly. Some disclosed embodiments may involve loading a sleeve onto a magnet insertion tool. In some embodiments, the sleeve 2724C may be loaded onto a first plurality of magnets (e.g., 2722B) supported by a first plurality of keys 2710C on the lower tool portion 2704B. In some embodiments, the sleeve may be loaded when the expansion mandrel 2706C may be in a retracted configuration, as described herein. For example, a retracted radius 2725C may be the first radius of the sleeve, such that the expansion mandrel 2706C may be in a retracted configuration.

[0137] Figure 27D illustrates step 2700D of an apparatus and method for manufacturing a rotor assembly. Some disclosed embodiments may involve loading a second plurality of magnets into a magnet insertion tool. For example, magnets of the second plurality of magnets 2726D may be loaded onto a second plurality of keys 2714D. The keys 2714D may support the magnets 2726D axially 2701D (e.g., to support the load of the magnets) and / or support the back of the magnets 2726D. In some embodiments, the second plurality of magnets 2726D may be side magnets. In some embodiments, a sleeve 2724D may be loaded onto the second plurality of magnets 2726D (e.g., the sleeve 2724D may be supported by the second plurality of keys 2714D). In some embodiments, the second plurality of magnets 2726D may be tapered along the axial direction.

[0138] Figure 27E illustrates step 2700E of an apparatus and method for manufacturing a rotor assembly. In some embodiments, the insertion movement (e.g., a second insertion movement) may involve moving one or more magnets in an axial direction, such as axial direction 2701E.

[0139] In some embodiments, the insertion movement may involve moving one of the magnets in the first plurality of magnets (e.g., 2722B). For example, the insertion movement may involve moving one of the magnets in the first plurality of magnets and the corresponding first plurality of keys 2710E in a direction 2731E which may be axial of the sleeve 2724E. In this example, the first plurality of magnets (hidden behind the sleeve 2724E in Figure 27E and shown as 2722B in Figure 27B) may move axially toward the second plurality of magnets 2726E, while the second plurality of magnets 2726E (and / or the second plurality of keys 2714E) may remain stationary relative to the sleeve 2724E. In this example, the lower tool portion 2704E may move in a direction 2731E toward the upper tool portion 2702E, for example, due to pressure on the lower tool portion of the lower tool portion 2704E or pressure on the support plate 2716E.

[0140] In some embodiments, the insertion movement may involve moving one of the magnets in a second plurality of magnets (e.g., 2726E). For example, the insertion movement may involve moving one of the magnets in the second plurality of magnets 2726E and the corresponding second plurality of keys 2714E in a direction 2733E which may be axial of the sleeve 2724E. In this example, the second plurality of magnets 2726E may move axially toward the first plurality of magnets (e.g., 2722B as behind the sleeve 2724E), while the first plurality of magnets (and / or the first plurality of keys 2710C) may remain stationary relative to the sleeve 2724E. In this example, the upper tool portion 2702E may move in a direction 2733E toward the lower tool portion 2704E, for example, due to pressure on the upper tool portion 2702E or pressure on the support plate 2720E.

[0141] In some embodiments, the insertion movement may involve moving one of the magnets in both the second plurality of magnets (e.g., 2726E) and the first plurality of magnets such that the second plurality of magnets moves axially 2733E and the first plurality of magnets moves in direction 2731E (e.g., movement due to pressure). In one example, at least a portion of the movement of both plurality of magnets in the axial direction 2731E may occur simultaneously.

[0142] Some disclosed embodiments involve inserting movement of the sleeve in the radial direction (e.g., a first inserting movement). For example, movement of an expansion mandrel as described herein (e.g., 2706B in Figure 27B) may result in movement of a first plurality of push bars and / or a second plurality of push bars. In some embodiments, the inserting movement may involve moving a first plurality of magnets radially 2703E of the sleeve. For example, movement of an expansion mandrel may move a push bar of a first plurality of push bars that may be in contact with a key of a first set of keys, thereby moving a magnet of a first plurality of magnets radially 2703E. The movement may involve expansion and / or contraction (e.g., retraction) in the radial direction 2703E.

[0143] In some embodiments, insertion movement may involve moving a second set of magnets (such as 2726D in Figure 27D) radially 2703E of the sleeve. For example, movement of the expansion mandrel may move a push bar among a second set of push bars that may be in contact with a key among a second set of keys, thereby moving a magnet among a second set of magnets radially 2703E of the sleeve 2724E. Movement may involve expansion and / or contraction (e.g., retraction) in the radial direction 2703E.

[0144] In some embodiments, the insertion movement may involve moving both the first and second sets of magnets radially.

[0145] Figure 27F illustrates step 2700F of an apparatus and method for manufacturing a rotor assembly. In some embodiments, the insertion movement may involve sliding a second plurality of magnets 2722F so that they are aligned axially 2701F with the first plurality of magnets 2722F and the sleeve. For example, a second plurality of magnets 2726F may be carried axially toward the first plurality of magnets 2722F so that the second plurality of magnets 2726F and the first plurality of magnets 2722F can be aligned (e.g., aligned along the inner diameter of the sleeve (not illustrated)). In the case of magnets that are tapered in the axial direction, such axial insertion may displace the contacting magnets (e.g., the contacting taper), thereby causing expansion of the sleeve radially 2703F and generating a preload in the sleeve. In some embodiments, the insertion movement may involve expanding the sleeve by pressing the plurality of magnets against the sleeve radially 2703F. Such movement can also expand the sleeve radially 2703F and generate preload. In some embodiments, at least a portion of the radial insertion movement and the axial insertion movement can occur simultaneously.

[0146] In some embodiments, the magnet ring may consist of a first plurality of magnets 2722F and a second plurality of magnets 2726F that are aligned. In some embodiments, the magnet insertion tool may have a hard stop. For example, the upper post 2734F of the upper tool portion 2702F may align with and contact the lower post 2736F of the lower tool portion 2704F according to a desired axial alignment of the magnets (e.g., to reduce unwanted movement of the magnets in the axial direction 2701F). In some embodiments, during insertion movement, the first plurality of magnets 2722F and the second plurality of magnets 2726F may move radially 2703F. It will be understood that the hard stop may prevent over-expansion of the sleeve and thereby reduce the occurrence of sleeve rupture.

[0147] Figure 27G illustrates step 2700G of an apparatus and method for manufacturing a rotor assembly. In some embodiments, manufacturing a rotor assembly may involve expanding a sleeve, as described herein. For example, axial 2701G and radial 2703G insertion movements may involve the movement of a first plurality of magnets and / or a second plurality of magnets to expand the sleeve radially 2703G. The expanded sleeve 2738G may include a magnet ring composed of the first plurality of magnets and a second plurality of magnets along the inner diameter of the expanded sleeve 2738G. In some embodiments, the sleeve may expand from a retracted radius 2725C to a second radius greater than the retracted radius 2725C and greater than the expanded radius 2741G (e.g., a third radius greater than the retracted radius 2725C and smaller than the second radius). For example, the extended radius 2741G may correspond to the operating radius of the extended sleeve 2738G, and the sleeve may extend beyond the operating radius (e.g., to maximize magnet preload and positional alignment). In some embodiments, the extended radius 2741G may be at least 98% of the second radius. In one example, the sleeve radius may be reduced from the second radius to the extended radius 2741G by removing the upper tool portion 2702G from the lower tool portion 2704G, and this reduction to the extended radius 2741G may provide locking of the magnet within the extended sleeve 2738G. In some embodiments, the sleeve may be extended from a retracted radius 2725C to an extended radius 2741G (e.g., the operating radius).

[0148] Figures 28A and 28B illustrate cross-sectional views of a magnet insertion tool consistent with embodiments of the present disclosure. Figure 28A may illustrate a cross-sectional view (taken through the first plurality of magnet keys) of the magnet insertion tool 2800A before expansion. As described herein, the magnet insertion tool 2800A may include a first plurality of push bars 2808A of an expansion mandrel corresponding to a first plurality of keys 2810A, and a second plurality of push bars (concealed by the push bars 2808A) corresponding to a second plurality of keys 2814A. The first plurality of keys 2810A may support a first plurality of magnets 2822A, and the second plurality of keys 2814A may support a second plurality of magnets 2826A. A sleeve 2824A may be mounted on the first plurality of magnets 2822A and may have an unexpanded (e.g., contracted) radius 2825A. In some embodiments, the first plurality of magnets 2822A may include pole magnets, and the second plurality of magnets 2826A may include side magnets. In some embodiments, the magnet insertion tool may include a push bar guide plate 2850A.

[0149] As described herein, the magnet insertion tool 2800A may include one or more tapered cones that can assist in insertion movement. In some embodiments, the magnet insertion tool 2800A may include one tapered cone, and the push bar may have a taper corresponding to the tapered cone. In some embodiments, the magnet insertion tool 2800A may include a first tapered cone 2840A and a second tapered cone 2842A. For example, a first plurality of push bars 2808A (and similarly, a second plurality of push bars) may include a first taper 2844A and a second taper 2846A, where the first taper 2844A may be linked with the taper of the first tapered cone 2840A and move along this taper, and the second taper 2846A may be linked with the taper of the second tapered cone 2842A and move along this taper.

[0150] In some embodiments, the first insertion movement may be performed by moving a first plurality of magnets 2822A or a second plurality of magnets 2826A radially 2803A with a magnet insertion tool 2800A. For example, the magnet insertion tool 2800A may be pressed (from above, from below, or from above and below, such as by pressing it onto a support plate as described herein) to move the expansion mandrel axially 2801A of the sleeve 2824A. The tapers of the first tapered cone 2840A and the second tapered cone 2842A act on the first taper 2844A and the second taper 2846A of the push bar, thereby moving the key, and therefore the magnet, outward radially 2803A. In some embodiments, the guide plate 2850A may move the push bar radially 2803A as the guide plate 2850A moves axially 2801A (for example, the push bar may slide along the guide plate). The first plurality of magnets 2822A may be pressed against and in contact with the sleeve 2824A, thereby expanding the sleeve 2824A radially 2803A. In some embodiments, the second insertion movement may involve sliding the second plurality of magnets 2826A so as to be aligned with both the first plurality of magnets 2822A and the sleeve 2824A. In the example of tapered magnets, contact of the magnet taper may expand the radius of the sleeve 2824A radially 2803A. Thus, it will be understood that the first insertion movement, the second insertion movement, or both the first and second insertion movements may expand the radius of the sleeve 2824A. In some embodiments, the first insertion movement may be performed before the second insertion movement. In some embodiments, the second insertion movement may be performed before the first insertion movement. It will be understood that the first and second insertion movements can reduce buckling and minute twisting in the sleeve. Some disclosed embodiments may involve performing at least a portion of the first and second insertion movements simultaneously. It will be understood that performing at least a portion of the first and second insertion movements simultaneously can reduce magnet chipping and bending moment on the magnet.In some examples, the first set of magnets 2822A may be polar magnets, and the second set of magnets 2826A may be side magnets. In this example, the polar magnets may be larger than the side magnets (e.g., have a larger surface area), and therefore the polar magnets may provide a frictional force to support the sleeve 2824A while the side magnets (which have a smaller coefficient of friction) move axially toward the sleeve 2824A, thereby supporting the sleeve while reducing torsion and other deterioration of the sleeve.

[0151] Figure 28B may illustrate a cross-sectional view (taken through a first set of magnet keys) of the extended configuration of the magnet insertion tool 2800B. For example, a first tapered cone 2840B may be linked to a first taper 2844B of the push bar 2808B, and a second tapered cone 2842B may be linked to a second taper 2846B. The extended sleeve 2838B may include a magnet ring 2852B containing a first set of magnets and a second set of magnets aligned axially, and the extended sleeve 2838B may extend to an extended radius 2841B which can be larger than the unextended radius 2825A, thereby providing a preload for holding the magnets in the magnet ring 2852B.

[0152] Figure 29 illustrates a diagram of a magnet insertion tool 2900 consistent with embodiments of the present disclosure. For example, the magnet insertion tool 2900 may refer to the lower portion of a magnet insertion tool as described herein. In some embodiments, the magnet insertion tool may include a support ring 2902 for supporting magnets and / or magnetic keys in the axial and / or radial directions. For example, the support ring may support a first plurality of magnets, a first plurality of magnetic keys, and / or a second plurality of magnetic keys. The support ring may also support a sleeve. For example, a stilt 2912 extending from the support ring 2902 may provide circumferential support and positional alignment to a first plurality of magnets 2904 and a first plurality of magnetic keys 2906. The surface of the stilt 2912 may also contact (e.g., rest on) the surface of the second plurality of magnetic keys (e.g., when a second plurality of magnetic keys, not illustrated, may be moved toward the first plurality of keys). In some examples, the shoulder portion 2910 may provide support and positional alignment to the sleeve. For example, the surface 2914 of the shoulder portion 2910 may support the sleeve during manufacturing. A support ring 2902 may extend from the support base and be subjected to a spring load via a spring 2908. It will be understood that the height of the sleeve may be set by adjusting the support ring 2902 (e.g., via the spring 2908).

[0153] Figure 30 illustrates a diagram of a magnet insertion tool 3000 consistent with embodiments of the present disclosure. For example, the magnet insertion tool 3000 may refer to the upper tool portion of a magnet insertion tool as described herein. In some embodiments, the magnet insertion tool 3000 may include a support ring 3002 extending from a support plate 3004. For example, the support ring 3002 may be connected to the support plate 3004 by screws. The support ring may be configured to move, such as to expand and contract (e.g., axially in the sleeve). The support ring 3002 may be compressed (e.g., by a spring 3006), and the magnet 3010 may be loaded into a magnet key 3008 (e.g., a second plurality of magnets may be loaded into a second plurality of keys). In some embodiments, the support ring 3002 may support and / or hold the magnet key 3008. For example, the support ring may be released (e.g., when spring 3006 expands) to fix the magnet 3010 and / or magnetic key 3008 in place. In one example, the support ring 3002 may be compressed to remove the rotor (e.g., magnetic ring) from the magnetic key. As described herein, in some examples, the magnetic key 3008 may be held and / or supported by a dowel pin and / or a slot in the support plate 3004. For example, the magnetic key 3008 may include a dowel pin extending through the key, and the slot in the support plate 3004 may be configured to allow radial expansion and contraction of the dowel pin and / or magnetic key 3008.

[0154] Figure 31 illustrates a flowchart of a method 3100 for manufacturing a rotor assembly for an electric engine, consistent with embodiments of the present disclosure. In some embodiments, the method 3100 may include a step 3102 of loading a first plurality of magnets into a magnet insertion tool. For example, the magnet insertion tool may include an expansion mandrel. In some examples, the first plurality of magnets may be tapered. In some examples, the first plurality of magnets may be rectangular.

[0155] In some embodiments, method 3100 may include step 3104 of loading a second plurality of magnets into a magnet insertion tool. The first plurality of magnets and the second plurality of magnets may be molded to form a magnet ring of a rotor assembly. For example, the magnet ring may include tapered magnets and / or non-tapered magnets. In the example of tapered magnets, the first plurality of magnets may have a taper complementary to the taper of the second plurality of magnets. In some examples, the magnet ring may include a non-magnetic material.

[0156] In some embodiments, method 3100 may include step 3106 of loading a sleeve into a magnet insertion tool. For example, the sleeve may be a sleeve configured to stretch, such as a carbon fiber sleeve as described herein.

[0157] In some embodiments, method 3100 may include step 3108 of performing a first insertion movement using a magnet insertion tool. In some embodiments, the first insertion movement may include moving one of the first plurality of magnets or the second plurality of magnets radially in the sleeve. In some examples, the first insertion movement may involve moving both the first plurality of magnets and the second plurality of magnets. In some examples, the first insertion movement may involve expanding the sleeve by pressing the first plurality of magnets radially against the sleeve.

[0158] In some embodiments, a plurality of magnets may be radially aligned behind another plurality of magnets (for example, the second plurality of magnets may initially be positioned closer to the center of the expansion mandrel radially than the first plurality of magnets). The first plurality of magnets may be in contact with the sleeve and pushed radially outward, thereby expanding the sleeve radially. If the radial expansion is sufficiently large, the second plurality of magnets may be inserted directly into the gap between the first plurality of magnets without axial sliding of either set of magnets. Thus, some disclosed embodiments may not require axial insertion movement or tapered magnet surfaces. Alternatively, in some embodiments, if the radial expansion of the sleeve is sufficiently large, the second set of magnets may be inserted directly axially into the gap between the first set of magnets. Thus, in some embodiments, the magnets may be assembled without requiring radial movement or tapered magnet surfaces.

[0159] In some embodiments, method 3100 may include step 3110 of performing a second insertion movement using a magnet insertion tool. In some embodiments, the second insertion movement may include moving one of the first plurality of magnets or the second plurality of magnets relative to the sleeve in the axial direction of the sleeve. In some examples, one of the first plurality of magnets or the second plurality of magnets may remain stationary in the axial direction relative to the sleeve during the second insertion movement. In some examples, the second insertion movement may include sliding the second plurality of magnets so that they are axially aligned with both the first plurality of magnets and the sleeve.

[0160] In some embodiments, a first set of magnets in contact with the sleeve may be expanded radially, and a second set of magnets may be inserted axially. For example, the axial movement of the second set of magnets may occur after the radial expansion of the first set of magnets.

[0161] In some embodiments, method 3100 may include step 3112 of using a magnetic insertion tool to radially expand the radius of the sleeve during either the first or second insertion movement. Some disclosed embodiments may involve performing at least part of the first and second insertion movements simultaneously.

[0162] The embodiments disclosed herein are intended to be non-limiting. Those skilled in the art will understand that certain components and configurations of components can be modified without departing from the scope of the disclosed embodiments. The above description is provided for illustrative purposes only. The above description is not exhaustive and does not limit the invention to the disclosed forms or embodiments themselves. Modifications and adaptations of the invention will be apparent to those skilled in the art with regard to the specification and practice of the disclosed embodiments of the invention disclosed herein. Furthermore, any sequence of steps shown in the figures is for illustrative purposes only and is not intended to limit to any particular sequence of steps. For example, steps may be performed in a different order than illustrated, steps may be performed simultaneously, or steps may be omitted. Thus, those skilled in the art will understand that these steps may be performed in a different order while implementing the same method.

[0163] The following clauses set forth some non-limiting aspects of this disclosure. 1. A rotor assembly, Sleeves and Rotor hub and, A plurality of tapered magnets arranged along the circumference of the inner diameter of a sleeve, wherein the plurality of tapered magnets are configured to be in contact with each other, Multiple tapered magnets include a first set of tapered magnets and a second set of tapered magnets. The insertion of the first set of tapered magnets axially into the second set of tapered magnets is configured to increase the diameter of the sleeve. A rotor assembly in which the rotor hub is configured to hold at least one of a plurality of tapered magnets or sleeves. 2. The rotor assembly described in Clause 1, wherein the sleeve is configured to hold a plurality of tapered magnets. 3. A rotor assembly as described in Clause 1 or 2, wherein the sleeve contains carbon fiber. 4. A rotor assembly further comprising a core, as described in any one of clauses 1 to 3. 5. The rotor assembly according to Clause 4, wherein the core includes at least one notch, the at least one notch configured to engage the core with the rotor hub. 6. The rotor assembly according to clause 4 or 5, further comprising a first rotor hub in contact with a first side surface of the core, and a second rotor hub in contact with a second side surface of the core opposite to the first side surface. 7. The rotor assembly according to any one of the clauses 4 to 6, further comprising at least one cavity disposed between a plurality of tapered magnets and a core, wherein at least one cavity is configured to guide a fluid for cooling one of the magnets among the plurality of tapered magnets. 8. The rotor assembly described in Clause 7, wherein the core or at least one cavity is configured to deliver fluid for the direct cooling of a plurality of tapered magnets. 9. An electric propulsion system for a vertical take-off and landing (VTOL) aircraft, wherein the electric propulsion system is The VTOL aircraft is equipped with at least one electric engine that is mechanically connected directly or indirectly to the fuselage, and the electric engine is The gearbox assembly is equipped, and the gearbox assembly is Sun Gear and, A system comprising an electric motor, wherein the electric motor has a stator and a rotor assembly as described in any one of clauses 1 to 8. 10. The system described in Clause 9, wherein the gearbox includes a bearing, the outer diameter of which is in contact with the inner diameter of the sun gear. 11. A method for assembling a rotor assembly, A method comprising inserting a first plurality of tapered magnets and a second plurality of tapered magnets from opposing directions such that each of the second plurality of tapered magnets is positioned between adjacent pairs of the first plurality of tapered magnets, and the first and second plurality of tapered magnets are arranged to form a magnetic ring on the inner surface of an expandable sleeve. 12. The method according to Clause 11, wherein inserting a first plurality of tapered magnets and a second plurality of tapered magnets increases the diameter of the expandable sleeve. 13. The method according to clause 11 or 12, further comprising inserting a bearing into the sun gear and mounting the sun gear to at least one rotor hub. 14. The method described in any one of clauses 11 to 13, further including balancing the rotor assembly. 15. The method according to any one of the clauses 11 to 14, wherein at least one rotor hub holds at least one of a magnetic ring or an expandable sleeve. 16. A method for manufacturing a rotor assembly for an electric engine, the method being: Loading the first set of magnets into the magnet insertion tool, Loading a second set of magnets into a magnet insertion tool, wherein the first set of magnets and the second set of magnets are molded to form a magnet ring of a rotor assembly; Loading the sleeve into the magnet insertion tool, Performing a first insertion movement using a magnet insertion tool, wherein the first insertion movement includes moving one of a first group of magnets or a second group of magnets in the radial direction of the sleeve. Performing a second insertion movement using a magnet insertion tool, wherein the second insertion movement includes moving one of the first or second plurality of magnets relative to the sleeve in the axial direction of the sleeve. A method comprising: using a magnetic insertion tool to radially expand the radius of the sleeve during either a first or second insertion movement. 17. The method according to Clause 16, further comprising performing at least a portion of the first insertion movement and the second insertion movement simultaneously. 18. The method according to clause 16 or 17, wherein during the second insertion movement, one of the first or second plurality of magnets remains stationary axially with respect to the sleeve. 19. The method according to any one of the clauses 16 to 18, further comprising moving both the first plurality of magnets and the second plurality of magnets radially during the first insertion movement. 20. The method according to any one of the clauses 16 to 19, wherein the first insertion movement includes expanding the sleeve by radially pressing the first plurality of magnets against the sleeve. 21. The method according to any one of the clauses 16 to 20, wherein the second insertion movement includes sliding the second plurality of magnets so that they are axially aligned with both the first plurality of magnets and the sleeve. 22. Expanding the radius of a sleeve includes expanding the radius from a first radius to a second radius, and the method is: The method according to Clause 16, further comprising reducing the radius of the sleeve from a second radius to a third radius, wherein the third radius is greater than the first radius and less than the second radius. 23. The method according to Clause 22, wherein the third radius is at least 98% of the second radius. 24. The method according to any one of the clauses 16 to 23, wherein the first plurality of magnets and the second plurality of magnets are tapered along the axial direction. 25. The first set of multiple magnets and the second set of multiple magnets are supported on the first set of multiple magnet keys and the second set of multiple magnet keys of the magnet insertion tool, respectively, and the method is as follows: The method according to any one of the clauses 16 to 24, further comprising using an extension mandrel of the magnet insertion tool to move the first plurality of magnets, the first plurality of magnet keys, the second plurality of magnets, and the second plurality of magnet keys radially during the first insertion movement. 26. The extension mandrel, A first set of push bars configured to press a first set of magnetic keys, The method according to clause 25, further comprising: a second plurality of push bars configured to push a second plurality of magnetic keys. 27. The method according to clause 26, further comprising sliding a plurality of first magnetic keys against the surface of a plurality of first push bars using a magnet insertion tool. 28. The method according to clause 25 or 26, further comprising sliding a second plurality of magnetic keys against the surface of a second plurality of push bars using a magnet insertion tool. 29. The method according to any one of the claims 25 to 28, wherein the expansion mandrel comprises a push bar guide plate configured to guide a first plurality of push bars and a second plurality of push bars radially. 30. The method according to Clause 29, wherein the expansion mandrel comprises a position alignment shaft configured to axially align the push bar guide plate when the push bar guide plate guides a first plurality of push bars and a second plurality of push bars radially. 31. The magnet insertion tool comprises a first support plate configured to support a first plurality of magnet keys, and a second support plate configured to support a second plurality of magnet keys, The method is, Moving the first set of magnetic keys radially relative to the first support plate, The method according to any one of the claims 25 to 30, further comprising moving a second set of magnetic keys radially relative to a second support plate. 32. The method according to clause 31, further comprising pressing the second support plate axially toward the first support plate between the first and second insertion movements. 33. The method according to clause 31 or 32, wherein moving the first plurality of magnetic keys radially relative to the first support plate includes moving the first plurality of magnetic keys in the first plurality of slots in the first support plate. 34. The method according to any one of the clauses 31 to 33, wherein moving the second plurality of magnetic keys radially relative to the second support plate includes moving the second plurality of magnetic keys in the second plurality of slots in the second support plate. 35. A vertical take-off and landing (VTOL) aircraft equipped with an electric propulsion system as described in Clause 9 or 10.

Claims

1. It is a rotor assembly, Sleeves and Rotor hub and, The device comprises a plurality of tapered magnets arranged along the circumference of the inner diameter of the sleeve, wherein the plurality of tapered magnets are configured to be in contact with each other. The plurality of tapered magnets include a first set of tapered magnets and a second set of tapered magnets, The insertion of the tapered magnets of the first set into the tapered magnets of the second set in the axial direction is configured to increase the diameter of the sleeve. A rotor assembly in which the rotor hub is configured to hold at least one of the plurality of tapered magnets or the sleeves.

2. The rotor assembly according to claim 1, wherein the sleeve is configured to hold the plurality of tapered magnets.

3. The rotor assembly according to claim 1 or 2, wherein the sleeve includes carbon fiber.

4. A rotor assembly according to any one of claims 1 to 3, further comprising a core.

5. The rotor assembly according to claim 4, wherein the core includes at least one notch, the at least one notch is configured to engage the core with the rotor hub.

6. The rotor assembly according to claim 4 or 5, further comprising: a first rotor hub in contact with a first side surface of the core; and a second rotor hub in contact with a second side surface of the core opposite to the first side surface.

7. The rotor assembly according to any one of claims 4 to 6, further comprising at least one cavity disposed between the plurality of tapered magnets and the core, wherein the at least one cavity is configured to guide a fluid for cooling one of the plurality of tapered magnets.

8. The rotor assembly according to claim 7, wherein the core or the at least one cavity is configured to deliver the fluid for direct cooling of the plurality of tapered magnets.

9. An electric propulsion system for a vertical take-off and landing (VTOL) aircraft, wherein the electric propulsion system is The VTOL aircraft comprises at least one electric engine directly or indirectly mechanically connected to the fuselage, wherein the electric engine A gearbox assembly is provided, and the gearbox assembly is Sun Gear and, A system comprising an electric motor, wherein the electric motor has a stator and a rotor assembly according to any one of claims 1 to 8.

10. The system according to claim 9, wherein the gearbox includes a bearing, and the outer diameter of the bearing is in contact with the inner diameter of the sun gear.

11. A vertical take-off and landing (VTOL) aircraft comprising the electric propulsion system according to claim 9 or 10.

12. A method for assembling a rotor assembly, A method comprising inserting a first plurality of tapered magnets and a second plurality of tapered magnets from opposing directions such that each of the second plurality of tapered magnets is positioned between adjacent pairs of the first plurality of tapered magnets, and the first and second plurality of tapered magnets are arranged to form a magnetic ring on the inner surface of an expandable sleeve.

13. The method according to claim 12, wherein inserting the first plurality of tapered magnets and the second plurality of tapered magnets increases the diameter of the expandable sleeve.

14. The method according to claim 12 or 13, further comprising inserting a bearing into a sun gear and mounting the sun gear to at least one rotor hub.

15. The method according to any one of claims 12 to 14, further comprising balancing the rotor assembly.

16. The method according to any one of claims 12 to 15, wherein the at least one rotor hub holds at least one of the magnetic ring or the expandable sleeve.

17. A method for manufacturing a rotor assembly for an electric engine, wherein the method is Loading the first set of magnets into the magnet insertion tool, Loading a second plurality of magnets into the magnet insertion tool, wherein the first plurality of magnets and the second plurality of magnets are molded to form a magnet ring of the rotor assembly, Loading a sleeve into the aforementioned magnet insertion tool, Performing a first insertion movement using the magnet insertion tool, wherein the first insertion movement includes moving one of the first plurality of magnets or the second plurality of magnets in the radial direction of the sleeve. Performing a second insertion movement using the magnet insertion tool, wherein the second insertion movement includes moving one of the first plurality of magnets or the second plurality of magnets relative to the sleeve in the axial direction of the sleeve. A method comprising expanding the radius of the sleeve in the radial direction using the magnet insertion tool during either the first insertion movement or the second insertion movement.

18. The method according to claim 17, further comprising performing at least a portion of the first insertion movement and the second insertion movement simultaneously.

19. The method according to claim 17 or 18, wherein during the second insertion movement, one of the first or second plurality of magnets remains stationary in the axial direction relative to the sleeve.

20. The method according to any one of claims 17 to 19, further comprising moving both the first plurality of magnets and the second plurality of magnets in the radial direction during the first insertion movement.

21. The first insertion movement described above is The method according to any one of claims 17 to 20, comprising expanding the sleeve by pressing the first plurality of magnets against the sleeve in the radial direction.

22. The aforementioned second insertion movement, The method according to any one of claims 17 to 21, comprising sliding the second plurality of magnets so as to be aligned in the axial direction with both the first plurality of magnets and the sleeve.

23. Expanding the radius of the sleeve includes expanding the radius from a first radius to a second radius, and the method is The method according to claim 17, further comprising reducing the radius of the sleeve from the second radius to a third radius, wherein the third radius is greater than the first radius and less than the second radius.

24. The method according to claim 23, wherein the third radius is at least 98% of the second radius.

25. The method according to any one of claims 17 to 24, wherein the first plurality of magnets and the second plurality of magnets are tapered along the axial direction.

26. The first plurality of magnets and the second plurality of magnets are each supported on the first plurality of magnet keys and the second plurality of magnet keys of the magnet insertion tool, and the method is The method according to any one of claims 17 to 25, further comprising moving the first plurality of magnets, the first plurality of magnet keys, the second plurality of magnets, and the second plurality of magnet keys in the radial direction using an expansion mandrel of the magnet insertion tool during the first insertion movement.

27. The aforementioned expansion mandrel, A first plurality of push bars configured to press the first plurality of magnetic keys, The method according to claim 26, further comprising: a second plurality of push bars configured to push the second plurality of magnetic keys.

28. The method according to claim 27, further comprising sliding the first plurality of magnetic keys against the surface of the first plurality of push bars using the magnet insertion tool.

29. The method according to claim 26 or 27, further comprising sliding the second plurality of magnetic keys against the surface of the second plurality of push bars using the magnet insertion tool.

30. The aforementioned expansion mandrel, The method according to any one of claims 26 to 29, comprising a push bar guide plate configured to guide the first plurality of push bars and the second plurality of push bars in the radial direction.

31. The aforementioned expansion mandrel is The method according to claim 30, further comprising a position alignment shaft configured to align the push bar guide plate in the axial direction when the push bar guide plate guides the first plurality of push bars and the second plurality of push bars in the radial direction.

32. The magnet insertion tool comprises a first support plate configured to support the first plurality of magnet keys, and a second support plate configured to support the second plurality of magnet keys, and the method is as follows: The method according to any one of claims 26 to 31, further comprising moving the first plurality of magnetic keys in the radial direction relative to the first support plate, and moving the second plurality of magnetic keys in the radial direction relative to the second support plate.

33. The method according to claim 32, further comprising pressing the second support plate toward the first support plate in the axial direction between the first insertion movement and the second insertion movement.

34. The method according to claim 32 or 33, wherein moving the first plurality of magnetic keys radially relative to the first support plate includes moving the first plurality of magnetic keys in a first plurality of slots in the first support plate.

35. The method according to any one of claims 32 to 34, wherein moving the second plurality of magnetic keys radially with respect to the second support plate includes moving the second plurality of magnetic keys in a second plurality of slots in the second support plate.

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