Integrated motor and transmission system

Abstract

An integrated motor and transmission system, has: a housing enclosing an internal volume; an electric motor mounted to the housing within the internal volume and having a stator and a rotor rotatable around a central axis; a core shaft drivingly engaged by the rotor, the core shaft being rollingly supported by the housing for rotation relative to the housing around the central axis; a magnetic gear axially offset from the electric motor relative to the central axis, the magnetic gear mounted to the housing within the internal volume, the magnetic gear having an input drivingly engaged by the core shaft and an output, the magnetic gear configured to provide a speed ratio between the input and the output using magnetic forces; and a connector defining an output shaft of the system, the connector rollingly supported by the housing and drivingly engaged by the output of the magnetic gear.

Description

INTEGRATED MOTOR AND TRANSMISSION SYSTEMCROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims benefit from United States provisional application number 63 / 673967 filed on July 22, 2024, the entire contents of which are incorporated by reference herein.TECHNICAL FIELD

[0002] The application relates generally to electric vehicles and, more particularly, to transmission systems for such electric vehicles.BACKGROUND

[0003] Typically, transmission systems for vehicles are purely mechanical. They may include gears, such as worm gear, spur gear, bevel gear, and so on. These gears may require regular maintenance, cause friction loss, and are low efficiency. Although existing transmission systems are satisfactory to some extend, there is always a need for improvements.SUMMARY

[0004] The present disclosure pertains to a transmission system including a magnetic gear integrated with an electric motor within a common housing. The magnetic gear may be devoid of contact between input and output rotors of the transmission system. It may thus be substantially maintenance free, and may generate low noise and vibrations. This magnetic gear may have a greater torque density than a conventional mechanical gear.

[0005] The disclosed transmission system may axially integrate a magnetic gear and a motor in a common housing. This may yield a compact structure, a high torque density and a high efficiency. The magnetic gear may be free or devoid of contact between the input and output rotors. This may eliminate the friction loss in traditional mechanical gears. Therefore, this transmission system may require less maintenance while providing higher efficiency, lower noise, and reduced vibration. Existing magnetic-geared machines typically integrate the magnetic gear and the machine radially, whose modulator will increase the torque ripple and reduce power factor. The proposed axial magnetic-geared machine may alleviate these drawbacks. Moreover, due to the physical isolation between the input and output rotors, the proposed structure may provide the user with inherent overload protection. In other words, any disturbance and fault in the output side of the transmission system may not be transmitted to the prime electric motor.This feature may be beneficial especially for marine applications which are prone to unexpected forces during the performance.

[0006] The disclosed transmission system proposes a compact axial magnetically geared machine which provides the user with a compact structure that integrates magnetic gearbox into the electric motor for traction applications. The output torque of the primary electric motor may be transmitted to the input rotor of the magnetic gearbox through a common shaft, and the output rotor of the magnetic gearbox transmits the boosted output torque to the required application. Contrary to the conventional motors, the proposed structure may have a higher torque density because the output torque is boosted using the coupled magnetic gear. Furthermore, the proposed structure has a contact-free operation which may improve the transmission efficiency in comparison with the mechanically-geared counterparts.

[0007] In one aspect, there is provided an integrated motor and transmission system, comprising: a housing enclosing an internal volume; an electric motor mounted to the housing within the internal volume, the electric motor having a stator secured to the housing and a rotor rotatable relative to the stator around a central axis; a core shaft drivingly engaged by the rotor of the electric motor, the core shaft being rollingly supported by the housing for rotation relative to the housing around the central axis; a magnetic gear axially offset from the electric motor relative to the central axis, the magnetic gear mounted to the housing within the internal volume, the magnetic gear having an input drivingly engaged by the core shaft and an output, the magnetic gear configured to provide a speed ratio between the input and the output using magnetic forces; and a connector defining an output shaft of the system, the connector rollingly supported by the housing and drivingly engaged by the output of the magnetic gear.

[0008] The integrated motor and transmission system described above may include any of the following features, in any combinations.

[0009] In some embodiments, the core shaft is rollingly supported at a first end and at a second end respectively by a first bearing and a second bearing.

[0010] In some embodiments, the housing includes an inner plate located axially between the electric motor and the magnetic gear, a bearing supported mounted to a radially-inner end of the inner plate, the second bearing mounted to the bearing support.

[0011] In some embodiments, the housing includes a fore end housing being transverse to the central axis, the fore end housing defining a fore bore, the first end of the core shaft extending through the fore bore.

[0012] In some embodiments, the first bearing is mounted to the fore end housing within the fore bore.

[0013] In some embodiments, the housing includes a rear end housing extending transversally to the central axis, the rear end housing defining a rear bore, the output shaft extending through the rear bore.

[0014] In some embodiments, a rear bearing is mounted within the rear bore of the rear end housing, the output shaft engaged to the rear bearing.

[0015] In some embodiments, the rear bearing includes two rear bearings axially offset from one another, both of the two rear bearings engaged by the core shaft.

[0016] In some embodiments, the rear end housing define an axial protrusion, the rear bore extending through the axial protrusion, the rear bearing mounted within the axial protrusion.

[0017] In some embodiments, the magnetic gear has: an inner member including inner magnets circumferentially distributed around the central axis; an outer member disposed radially outwardly of the inner member and including outer magnets circumferentially distributed around the central axis; and a central member located radially between the inner member and the outer member relative to the central axis, the central member including magnetically-attractable members disposed circumferentially around the central axis, wherein the core shaft is drivingly engaged to one of the inner member, the outer member, and the central member, the output shaft is drivingly engaged by another of the inner member, the outer member, and the central member, and a remaining one of the inner member, the outer member, and the central member is secured to the housing.

[0018] In some embodiments, the core shaft is drivingly engaged to the inner member, the central member is fixed to the housing, and the outer member is drivingly engaging the output shaft.

[0019] In some embodiments, the outer member is drivingly engaged to the output shaft via a peripheral section of the connector, the peripheral section extending radially outward from the output shaft.

[0020] In another aspect, there is provided an electric vehicle (EV) comprising: a propulsor for propelling the EV; a power source; and an integrated motor and transmission system as described above.

[0021] The electric vehicle described above may include any of the following features, in any combinations.

[0022] In some embodiments, the core shaft is rollingly supported at a first end and at a second end respectively by a first bearing and a second bearing.

[0023] In some embodiments, the housing includes an inner plate located axially between the electric motor and the magnetic gear, a bearing supported mounted to a radially-inner end of the inner plate, the second bearing located mounted to the bearing support.

[0024] In some embodiments, the housing includes a fore end housing being transverse to the central axis, the fore end housing defining a fore bore, the first end of the core shaft extending through the fore bore.

[0025] In some embodiments, the first bearing is mounted to the fore end housing within the fore bore.

[0026] In some embodiments, the housing includes a rear end housing extending transversally to the central axis, the rear end housing defining a rear bore, the output shaft extending through the rear bore.

[0027] In some embodiments, a rear bearing is mounted within the rear bore of the rear end housing, the output shaft engaged to the rear bearing.

[0028] In some embodiments, the magnetic gear has: an inner member including inner magnets circumferentially distributed around the central axis; an outer member disposed radially outwardly of the inner member and including outer magnets circumferentially distributed around the central axis; and a central member located radially between the inner member and the outer member relative to the central axis, the central member including magnetically-attractablemembers disposed circumferentially around the central axis, wherein the core shaft is drivingly engaged to one of the inner member, the outer member, and the central member, the output shaft is drivingly engaged by another of the inner member, the outer member, and the central member, and a remaining one of the inner member, the outer member, and the central member is secured to the housing.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Reference is now made to the accompanying figures in which:

[0030] Fig. 1 is a schematic view of an electric vehicle;

[0031] Fig. 2 is a cutaway view of an integrated motor and transmission system for the electric vehicle of Fig. 1 ;

[0032] Fig. 3 is a three dimensional exploded view of the integrated motor and transmission system of Fig. 2;

[0033] Fig. 4 is a cross-sectional view of an electric motor for the system of Fig. 2;

[0034] Fig. 5 is a cross-sectional view of a magnetic gear for the system of Fig. 2;

[0035] Fig. 6 is an enlarged view of a portion of Fig. 4 illustrating parameters of the electric motor of Fig. 4;

[0036] Fig. 7 is an enlarged view of a portion of Fig. 5 illustrating parameters of the magnetic gear of Fig. 5;

[0037] Fig. 8 is a three dimensional view of an integrated motor and transmission system for the electric vehicle of Fig. 1 in accordance with another embodiment;

[0038] Fig. 9 is a three dimensional cutaway view of the integrated motor and transmission system of Fig. 8;

[0039] Fig. 10 is an three dimensional exploded view of the integrated motor and transmission system of Fig. 8;

[0040] Fig. 11 is partial three dimensional view of a magnetic gear of the integrated motor and transmission system of Fig. 8; and

[0041] Fig. 12 is a front view of the magnetic gear of Fig. 11 illustrating different design parameters thereof.DETAILED DESCRIPTIONIntroduction

[0042] Electric vehicles (EVs) represent a transformative paradigm in the automotive industry, embodying a sustainable solution to transportation challenges and environmental concerns. Unlike traditional internal combustion engine vehicles, EVs rely on electric motors (EMs) powered by rechargeable batteries, offering significant reductions in greenhouse gas emissions and dependence on fossil fuels. The optimal propulsion motor for EVs should exhibit distinct attributes such as high output torque to provide enough motive force to turn the wheels, and high efficiency to maximize the utilization of energy stored in the vehicle’s battery. Additionally, the speed range and size of EM influence its suitability for different driving conditions. It will be appreciated that the contents of the present disclosure may be used in other applications, such as robots, marine drive, etc.

[0043] The output torque produced by the drive motor is directly proportional to its size, which is why EMs are typically designed for operations at high-speed and low-torque. Inevitably, the output torque must be amplified through the transmission system to properly drive the wheels. The conventional approach involves incorporating a mechanical gearbox into the drive train to transmit power. Subsequently, a mechanical differential is installed on the drive axle for speed variation adjustment between the front wheels when the vehicle turns. However, the mechanical transmission strategy comes with drawbacks, including noise, vibration, power inefficiency, and the need for more frequent maintenance.

[0044] Up to now, the conventional transmission systems utilize mechanical gearboxes which are associated with many drawbacks such as regular maintenance, lubrication, friction loss, and teeth damage due to the overload faults. The disclosed transmission system, using a magnetic gear, which may provide a contact-free feature, may mitigate the above-mentioned drawbacks. Additionally, since the output torque of the electric motor is directly proportional to the volume of the motor, the traditional low-speed motors usually have a bulky size which causes practical drawbacks when they are exploited in real traction applications. There is a need to increase power density of propulsion system for electric vehicles. The power density may be defined as the powergenerated by the propulsion system divided by its mass. In recent years, the demand to increase the power density of propulsion system has increased.

[0045] The proposed structure may at least partially alleviate these drawbacks. There is herein presented a highly integrated magnetic gear motor assembly. This device may exhibit a higher torque density and compact configuration. The motor used may be designed with highspeed operation and may have a small size. The magnetic gearbox may have substantially the same volume as the motor. Therefore, it has a volume that may be suitable to be adopted in traction applications, such as electric vehicles.

[0046] Since the motor in the disclosed system may be a high-speed interior permanent magnet motor, it may have a smaller size compared to the conventional low-speed direct-drive motors. Also, the overall size of the axial magnetically-geared motor may be reduced. In addition, due to the axial connection between the magnetic gearbox and the electric motor, the maximum number of air-gaps is limited to two. This may improve the mechanical reliability of the drive system. The proposed system 20 may also offer a compact architecture, which may be advantageous for electric vehicles where space constraints are critical.Electric vehicle

[0047] Referring to Fig. 1 , an exemplary electric vehicle is shown at 10. The vehicle 10 may be an automobile, an aircraft, a boat, and so on. The vehicle 10 includes a propulsor 11 , which may be wheel(s), propeller(s), fan(s), impeller(s), endless track(s), and so on. The propulsor 11 is drivingly engaged by an integrated motor and transmission system 20, which includes an electric motor 30 and a transmission 40. A power source 12, which may be a battery, a generator, a fuel cell, and so on, is operatively connected to the electric motor 30 to supply power thereto. In some embodiments, the vehicle 10 may be a hybrid vehicle in which a combustion engine 14 is drivingly engaged to the motor 30, either directly or via transmission means, to compound power with the electric motor 30 in driving the propulsor 11. The combustion engine 14 may be a piston engine, a rotary engine, and so on. In some embodiments, the combustion engine 14 may be replaced by another electric motor. In some cases, the electric motor 30 may be configured to provide a rotational input to another system of the vehicle 10, such as a pump for a coolant, a compressor for an air conditioning system of the vehicle 10, and so on. The combustion engine 14 may be omitted in some configurations. Moreover, coupling the motor 30 with another machine may allow to control the power flow of the system 20.

[0048] Referring now to Figs. 2-3, the integrated motor and transmission system, referred to below simply as “system” 20 is shown in greater detail. The system 20 integrates a transmission and an electric motor into a compact structure. As aforementioned, the system 20 includes the electric motor 30, which may be a V-shape permanent magnet synchronous motor (PMSM), but any suitable electric motor may alternatively be used. For instance, the electric motor 30 may be an outer-rotor interior permanent magnet synchronous motor (OR-IPMSM), an outer-rotor induction motor (OR-IM), an outer-rotor switched reluctance motor (OR-SRM), and a pseudo- direct-drive (PDD) motor, to name a few may be used. The motor 30 may be a permanent magnet machine, an induction machine, or a reluctance machine. PDD motors may bridge the gap between high torque and direct connection to offer a balanced and efficient performance profile. The system 20 herein includes a magnetic gear 40, which is described further below. The magnetic gear 40 may be configured to amplify a torque generated by the electric motor 30. The present system 20 may include an axial magnetically-geared pseudo-direct-drive motor permanent magnet synchronous motor assembly. This configuration may yield a greater torque density and a more compact configuration compared to alternatives.Housing

[0049] The system 20 has a housing 21 including a peripheral housing 21 A disposed between two end housings, namely a fore end housing 21 B and a rear end housing 21 C. The peripheral housing 21A may be cylindrically shaped and extends around a central axis A, but other shapes are contemplated. The housing may be square or rectangular shape for instance. The housing 21 encloses an internal volume V sized for receiving the electric motor 30 and the magnetic gear 40. The housing 21 is therefore a single unique housing that contains both of the electric motor 30 and the magnetic gear 40. The system 20 may be devoid of a second housing. The internal volume V of the housing 21 is sized accordingly to accommodate both of the electric motor 30 and the magnetic gear 40. Coupling between the electric motor 30 and the magnetic gear 40 is down within the housing 21 itself. In the embodiment shown, fasteners 22 extends from one of the two end housings to the other and are used to secure the electric motor 30 and the magnetic gear 40 to the housing 21. The fasteners 22 are circumferentially distributed around the central axis A. Other fastening means are contemplated. For instance, the end housings may be threadingly engaged to the peripheral housing. They may be welded, brazed, etc.

[0050] Referring to Figs. 2-3, the system 20 include a core shaft 23 drivingly engaged by the electric motor 30. The core shaft 23 extends from a first end 23A to a second end 23B. The coreshaft 23 is rollingly supported to the housing 21 at or proximate the first end 23A. In the embodiment shown, a first bearing 24 is disposed within a bore defined through the fore end housing 21 B and radially between a peripheral surface extending around the bore and the core shaft 23. It will be appreciated that the first end 23A of the core shaft 23 may protrude from the fore end housing 21 B. This may be used to either provide a rotational input to another system or to receive a torque from another engine (e.g., hybrid engine including an electric motor and a combustion engine such as a piston engine). In some cases, an axial distance between the ends of the core shaft 23 and the bearings is at most about 1 inch. The first bearing 24 may be a journal bearing, a ball bearing, a roller bearing, or any other suitable kind of bearing. This is true for all of the bearings present in the system 20. The core shaft 23 is drivingly engaged by the electric motor 30 as will be explained below. In this disclosure, the expression “about” implies variations of plus or minus 10%.

[0051] The housing 21 may include an inner plate 21 D extending transversally to the peripheral housing 21 A and axially between the fore end housing 21 B and the rear end housing 21 C relative to the central axis A. The inner plate 21 D extends radially inwardly towards the central axis A from the peripheral housing 21 A to a bearing support 21 E at its radially-inner end. A second bearing 26 is disposed radially between the bearing support 21 E and the core shaft 23. As shown, the core shaft 23 protrudes axially beyond the inner plate 21 D such that the second end 23B drivingly engages the magnetic gear 40 as explained below. In some embodiments, the inner plate 21 D may be used to increase the mechanical robustness of the system 20. The inner plate 21 D may be omitted with a reduction of an axial length of the housing 21.

[0052] In the embodiment shown, the rear end housing 21C defines an axial protrusion 21 F extending axially away from the first end housing 21 B. A third bearing 27 and a fourth bearing 28 are disposed radially between the axial protrusion 21 F and an output shaft of the system 20. In this embodiment, the third bearing 27 and the fourth bearing 28 have different diameters to mate with different sections of the output shaft. Two bearings may be used to avoid or limit eccentricity of the core shaft 23. In some embodiments, one bearing may be used. It will be appreciated that only one bearing may be used if the core shaft 23 had a constant diameter in this section. Also, the axial protrusions 21 F allows to create an axial space to receive the two bearings. Having the one or more bearings as such may allow to ensure a concentricity of shaft supported thereby.Electric motor

[0053] Referring to Figs. 2-4, the electric motor 30 is mounted to the housing 21 within the internal volume V and axially between the fore end housing 21 B and the inner plate 21 D. More specifically, the electric motor 30 has a stator 31 and a rotor 32. The rotor 32 drivingly engages the core shaft 23. The stator 31 is disposed around the rotor 32. The stator 31 may be secured to the housing 21 via the fasteners 22, which may extend through apertures defined by the stator 31. Any other suitable ways of securing the stator 31 to the housing 21 may be used. In this configuration, the stator 31 is static relative to the housing 21 and the rotor 32 rotates relative to the stator 31 and relative to the housing 21 . It will be appreciated that the opposite may be used, that is, that the rotating part of the electric motor 30 may be located outwardly of the static part.

[0054] The electric motor 30 may be a synchronous electric motor, which is an AC motor that, under steady-state conditions, may ensure that the shaft's rotation aligns with the supply current's frequency. This means that the time it takes for one full rotation of the rotor 32 corresponds to a whole number of AC cycles. These motors employ electromagnets in the stator 31 , generating a magnetic field that synchronously rotates along with the current's oscillations. The rotor 32, which consists of either permanent magnets or electromagnets, also revolves in harmony with the stator field, producing a second magnetic field that rotates in synchronization. In the proposed axial magnetically-geared system, a V-shape PMSM is adopted which uses the V-shape magnets buried in the rotor iron yoke. The designed model is a 3 phase, 48 slots, 4 polepairs, and 70 kW PMSM motor. However, any other suitable electric motor may be used without departing from the scope of the present disclosure. As shown in Fig. 4, the electric motor 30 has windings 33 as part of the stator 31 and permanent magnets 34 as part of the rotor 32 and circumferentially distributed around the central axis A. Other configurations are contemplated. Any suitable motor may be used without departing from the scope of the present disclosure.Magnetic gear

[0055] Referring to Figs. 2-3 and 5, the magnetic gear 40 is described in more details below. The magnetic gear 40 is mounted to the housing 21 within the internal volume V between the inner plate 21 D and the rear end housing 21C. As shown, the magnetic gear 40 and the electric motor 30 are axially offset relative to one another relative to the central axis A. The magnetic gear 40 has an input 40A drivingly engaged by the core shaft 23 and an output 40B. The magneticgear 40 is configured to provide a speed ratio between the input 40A and the output 40B using magnetic forces as will be explained in further detail below.

[0056] The magnetic gear 40 includes an inner member 41 drivingly engaged by the core shaft 23, an outer member 42 disposed radially outwardly of the inner member 41 relative to the central axis A, and a central member 43, which may also be referred to as a modulating ring, located radially between the inner member 41 and the outer member 42 relative to the central axis A. The inner, outer, and central members are rotatable relative to one another relative to the central axis A. In this embodiment, the core shaft 23 of the electric motor 30 engages the inner member 41 , and the outer member 42 acts as the output while rotation of the central member 43 is blocked. In this configuration, the central member 43 is fixed to the housing 21 via the inner plate 21 D. Suitable fasteners or other fastening means may be used to fix the central member 43 to the inner plate 21 D. However, it will be appreciated that other configurations are contemplated. For instance, the core shaft 23 may be drivingly engaged to one of the inner member 41 , outer member 42, and central member 43, the output may be defined by another one of the inner member 41 , outer member 42, and central member 43, while rotation of a remaining one of the inner member 41 , outer member 42, and central member 43 is blocked. Any configuration is contemplated.

[0057] As shown in Fig. 5, the inner member 41 includes inner magnets 44 circumferentially distributed around the central axis A. The outer member 42 includes outer magnets 45 circumferentially distributed around the central axis A. The central member 43 includes magnetical ly-attractable members 47 disposed circumferentially around the central axis A. The magnetically-attractable members 47, are made of a magnetically-attractable material, such as iron or any other suitable material. In this embodiment, the central member 43 includes a holder 46 that supports the magnetically-attractable members 47. The holder 46 may allow rotation of the members 47 around the central axis A1.

[0058] Referring to Figs. 2-3, the system 20 includes a connector 25, which may also be referred to as a coupler. The connector 25 is used to transmit a torque from the output 40B of the magnetic gear 40 to an output shaft 25A. In this embodiment, the connector 25 defines the output shaft 25A such as these are two parts of a single body. It will be appreciated that this need not be the case and the output shaft 25A may be a separate component secured (e.g., fastened) to the connector 25. The output shaft 25A may be used to transfer a rotational input to the propulsor 11 (Fig. 1) of the vehicle 10 (Fig. 1). The connector 25 is rollingly supported by the housing 21 viathe third bearing 27 and the fourth bearing 28. As aforementioned, these bearings are disposed within a bore defined by the rear end housings 21 C and radially between a peripheral surface extending around the bore and the output shaft 25A. Only one bearing may be used in some embodiments.

[0059] The connector 25 is drivingly engaged by the output 40B of the magnetic gear 40, herein, by the outer member 42. The connector 25 has a peripheral section 25B that extends radially outwardly from the output shaft 25A. The peripheral section 25B is connected (e.g., fastened, welded, etc) to the outer member 42 of the magnetic gear 40. It may alternatively be fastened to the central member 43 as discussed above.

[0060] Referring to Figs. 6-7, manufacturing or design parameters of both of the electric motor 30 and the magnetic gear 40 are illustrated. The Table below presents possible values for these parameters. It will however be understood that these values are exemplary only and that other values may be used depending of the application, the required power output, and so on.

[0061] Referring to Figs. 8-10, another embodiment of a system is shown at 120. For the sake of conciseness, only features differing from the system 20 described above are described below.

[0062] In the embodiment shown, the connector 125 has a central section 125B defining a recess 125D. A third bearing 127 is received into the recess 125D. The second end 123B of the core shaft 123 is rollingly supported by the connector 125 via the third bearing 127. As one may appreciate, the connector 125 is used to conjointly support the core shaft 123 and the output shaft 125A. Hence, the second bearing 126 and the third bearing 127 are located on the same side of the magnetic gear 140. Thus, an annular space S defined axially between the electric motor 130 and the magnetic gear 140 may extend all the way from the core shaft 123 to the peripheral housing 121A. The annular space S may be devoid of any bearing. By moving the third bearing 127 from within the annular space S to inside the recess 125D of the connector 125, the size of the annular space S may be reduced. This may allow for a more compact system, thus increasing the power density of the system 120.

[0063] As shown in Fig. 8, the system 120 may include a cooling system 150 configured for flowing a liquid coolant. The cooling system 150 has a coolant inlet 151 and a coolant outlet 152.The coolant inlet 151 is fluidly connected to the coolant outlet 152 via the internal volume V of the housing 121 and via coolant flow passages 153 defined by both of the electric motor 130 and the magnetic gear 140. Put differently, by removing any separation in the annular space S, a single cooling system may be used for cooling conjointly both of the electric motor 130 and the magnetic gear 140. Hence, the coolant flow passages 153 extend through both of the electric motor 130 and the magnetic gear 140. In other words, flow passages of the electric motor 130 fluidly communicate with flow passage of the magnetic gear 140. This may allow to use a single inlet and a single outlet for the cooling system 150. This may offer simplicity to the system 120 while minimizing weight of the cooling system 150.

[0064] Referring more particularly to Figs. 10-11 , the magnetic gear 140 is further described. The magnetic gear 140 includes an inner member 141 drivingly engaged by the core shaft 123, an outer member 142 disposed radially outwardly of the inner member 141 relative to the central axis A, and a central member 143 located radially between the inner member 141 and the outer member 142 relative to the central axis A.

[0065] The inner member 141 includes inner magnets 144 circumferentially distributed around the central axis A. The outer member 142 includes outer magnets 145 circumferentially distributed around the central axis A. The central member 143 includes magnetically-attractable members 146 disposed circumferentially around the central axis A. The magnetically-attractable members 146 are made of a magnetically-attractable material, such as iron or any other suitable material. In the embodiment shown, the inner magnets 144 include inner circumferential magnets 144A and inner radial magnets 144B circumferentially interspaced with the inner circumferential magnets 144A. The inner circumferential magnets 144A extend a full radial span of the inner member 141 whereas the inner radial magnets 144B are located at a radially-inner section of the inner member 141. The inner member 141 further includes inner magnetically-attractable members 144C circumferentially aligned with the inner radial magnets 144B and extending radially outwardly therefrom.

[0066] Similarly, the outer magnets 45 include outer circumferential magnets 145A and outer radial magnets 145B circumferentially interspaced with the outer circumferential magnets 145A. The outer circumferential magnets 145A extend a full radial span of the outer member 142 whereas the outer radial magnets 145B are located at a radially-outer section of the outer member 142. The outer member 142 further includes outer magnetically-attractable members 145C circumferentially aligned with the outer radial magnets 145B and extending radially inwardlytherefrom. The different magnets and magnetically-attractable member extend axially a full axial span of the magnetic gear 140. Numbers of the different magnets and magnetically-attractable member is selected such that the magnetic gear 140 provides the desired speed ratio.

[0067] The core shaft 123 is drivingly engaged by one of the inner member 141 , the outer member 142, and the central member 143, the output shaft 125A and the connector 125 are drivingly engaged by another of the inner member 141 , the outer member 142, and the central member 143, and a remaining one of the inner member 141 , the outer member 142, and the central member 143 is secured to the housing 121 to be stationary relative to the housing 121. In this embodiment, the core shaft 123 is drivingly engaged by the inner member 141 , the outer member 142 is mounted to the housing 121 and is non-rotatable relative to the housing 121 , and the central member 143 drivingly engages the connector 125 and the output shaft 125A.

[0068] Due to the axial combination of the electric motor 130 and magnetic gear 140 in the system 120, a common shaft (i.e., the core shaft 123) is used to make the connection between the electric motor 130 and the magnetic gear 140. Moreover, the stator 131 of the electric motor 130 may have the same diameter as the outer member 142 of the magnetic gear 140 and they are fixed to the housing 121 and connected to each other using the fasteners 22. For the sake of eccentricity, three bearings are inserted into the system 20. The first bearing 124 connects the core shaft 123 to one of the end housings 121 B of the housing 121 , the second bearing 126 connects the connector 125 to the other of the end housings 121 B of the housing 121 , and the third bearing 127 makes the connection between the core shaft 123 and the connector 125.

[0069] The system 20, 120 may operate in two modes which may be 1) a constant torque mode and 2) a constant power mode. In the constant torque mode, the output power is adjustable with the input voltage while the output torque is constant. On the other hand, in the constant power region, the output power is set at the rated value and the output torque is adjustable with the current. The rated speed of the electric motor 30, 130 may be 3000 rpm and regarding the gear ratio of the magnetic gear 40, 140 (e.g., 6.5), the rated output speed of the axial magnetically- geared motor is 3000 / 6.5 = 460 rpm. At the speeds over than this value, the system 20 operates at constant power region.

[0070] Incorporating the magnetic gearing effect within the electric motor, it is possible to enhance the transmission torque using a simulated gear. Consequently, the electric motor can directly deliver substantial torque without the need for traditional mechanical gears. Through theapplication of field modulation effects, numerous innovative electric machines designed for direct- drive purposes have emerged in recent decades.

[0071] Referring now to Fig. 12, another view of the magnetic gear 140 is shown. The central member 143 provides a modulation effect that enables effective magnetic coupling between the inner and outer members. The magnetic gear may be a combination of flux-focusing and Halbach magnetic gears in which the flux-focusing PM arrangement transmits the major torque. Halbach array contributes to the torque transmission as well, and moreover, it reduces the leakage flux of the flux-focusing structure and increases the VTD of the magnetic gear accordingly. Therefore, the total output torque of the proposed gear may be larger than the sum of the output torque of flux-focusing and Halbach gears, and a high VTD can be achieved.

[0072] The Tables below present exemplary values of design parameters of the magnetic gears 140. Understandably, these values may be changed depending of the application, size, power requirement, and so on.Design Parameters of the Surrogate-based Multi-objective OptimizationConclusions

[0073] The existing magnetic-geared machines integrate magnetic gear and motor radially, which have multiple air-gaps, low power factor, large torque ripple, large noise and vibration. In this disclosure, the aforementioned drawbacks are at least partially alleviated by integrating magnetic gear and motor axially.

[0074] The proposed axial magnetic-geared machine may provides the users with a compact structure including primary electric motor and axially coupled magnetic gear. Due to the axial integration of the motor and magnetic gear, the disclosed structure may mitigate drawbacks associated with the counterpart mechanically-geared motors which usually have an inefficient performance. Since the magnetic gear is axially connected to the motor, the mechanical manufacturing of the structure may be more straightforward and facilitated. Contact-free operation is another key feature of the disclosed structure which means all the rotational and stationary parts of the magnetic gear are separated from each other and operate without any physical contact. As a result, the friction loss and regular maintenance are eliminated. Moreover, due to the physical isolation between the inner and outer members of the magnetic gear, the proposed structure may provide inherent overload protection. In other words, any disturbance and fault in the output side of the transmission system may not be transmitted to the electric motor.

[0075] It is noted that various connections are set forth between elements in the preceding description and in the drawings. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. The term “connected” or "coupled to" may therefore include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements).

[0076] It is further noted that various method or process steps for embodiments of the present disclosure are described in the preceding description and drawings. The description may present the method and / or process steps as a particular sequence. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the description should not be construed as a limitation.

[0077] Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0078] While various aspects of the present disclosure have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the present disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these particular features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the present disclosure. References to “various embodiments,” “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. The use of the indefinite article “a” as used herein with reference to a particular element is intended to encompass “one or more” such elements, and similarly the use of the definite article “the” in reference to a particular element is not intended to exclude the possibility that multiple of such elements may be present.

[0079] The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodimentsdescribed herein without departing from the scope of the present technology. Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology.

Claims

CLAIMS1. An integrated motor and transmission system, comprising: a housing enclosing an internal volume; an electric motor mounted to the housing within the internal volume, the electric motor having a stator secured to the housing and a rotor rotatable relative to the stator around a central axis; a core shaft drivingly engaged by the rotor of the electric motor, the core shaft being rollingly supported by the housing for rotation relative to the housing around the central axis; a magnetic gear axially offset from the electric motor relative to the central axis, the magnetic gear mounted to the housing within the internal volume, the magnetic gear having an input drivingly engaged by the core shaft and an output, the magnetic gear configured to provide a speed ratio between the input and the output using magnetic forces; and a connector defining an output shaft of the system, the connector rollingly supported by the housing and drivingly engaged by the output of the magnetic gear.

2. The integrated motor and transmission system of claim 1 , wherein the core shaft is rollingly supported at a first end and at a second end respectively by a first bearing and a second bearing.

3. The integrated motor and transmission system of claim 2, wherein the housing includes an inner plate located axially between the electric motor and the magnetic gear, a bearing supported mounted to a radially-inner end of the inner plate, the second bearing mounted to the bearing support.

4. The integrated motor and transmission system of claim 2 or 3, wherein the housing includes a fore end housing being transverse to the central axis, the fore end housing defining a fore bore, the first end of the core shaft extending through the fore bore.

5. The integrated motor and transmission system of claim 4, wherein the first bearing is mounted to the fore end housing within the fore bore.

6. The integrated motor and transmission system of any one of claims 1 to 5, wherein the housing includes a rear end housing extending transversally to the central axis, the rear end housing defining a rear bore, the output shaft extending through the rear bore.

7. The integrated motor and transmission system of claim 6, comprising a rear bearing mounted within the rear bore of the rear end housing, the output shaft engaged to the rear bearing.

8. The integrated motor and transmission system of claim 7, wherein the rear bearing includes two rear bearings axially offset from one another, both of the two rear bearings engaged by the core shaft.

9. The integrated motor and transmission system of claim 7 or 8, wherein the rear end housing define an axial protrusion, the rear bore extending through the axial protrusion, the rear bearing mounted within the axial protrusion.

10. The integrated motor and transmission system of any one of claims 1 to 9, wherein the magnetic gear has: an inner member including inner magnets circumferentially distributed around the central axis; an outer member disposed radially outwardly of the inner member and including outer magnets circumferentially distributed around the central axis; and a central member located radially between the inner member and the outer member relative to the central axis, the central member including magnetically-attractable members disposed circumferentially around the central axis, wherein the core shaft is drivingly engaged to one of the inner member, the outer member, and the central member, the output shaft is drivingly engaged by another of the inner member, the outer member, and the central member, and a remaining one of the inner member, the outer member, and the central member is secured to the housing.

11. The integrated motor and transmission system of claim 10, wherein the core shaft is drivingly engaged to the inner member, the central member is fixed to the housing, and the outer member is drivingly engaging the output shaft.

12. The integrated motor and transmission system of claim 11 , wherein the outer member is drivingly engaged to the output shaft via a peripheral section of the connector, the peripheral section extending radially outward from the output shaft.

13. An electric vehicle (EV) comprising: a propulsor for propelling the EV; a power source; and an integrated motor and transmission system as claimed in claim 1.

14. The EV of claim 13, wherein the core shaft is rollingly supported at a first end and at a second end respectively by a first bearing and a second bearing.

15. The EV of claim 14, wherein the housing includes an inner plate located axially between the electric motor and the magnetic gear, a bearing supported mounted to a radially- inner end of the inner plate, the second bearing located mounted to the bearing support.

16. The EV of claim 14 or 15, wherein the housing includes a fore end housing being transverse to the central axis, the fore end housing defining a fore bore, the first end of the core shaft extending through the fore bore.

17. The EV of claim 16, wherein the first bearing is mounted to the fore end housing within the fore bore.

18. The EV of any one of claims 13 to 17, wherein the housing includes a rear end housing extending transversally to the central axis, the rear end housing defining a rear bore, the output shaft extending through the rear bore.

19. The EV of claim 18, comprising a rear bearing mounted within the rear bore of the rear end housing, the output shaft engaged to the rear bearing.

20. The EV of any one of claims 13 to 19, wherein the magnetic gear has: an inner member including inner magnets circumferentially distributed around the central axis; an outer member disposed radially outwardly of the inner member and including outer magnets circumferentially distributed around the central axis; anda central member located radially between the inner member and the outer member relative to the central axis, the central member including magnetically-attractable members disposed circumferentially around the central axis, wherein the core shaft is drivingly engaged to one of the inner member, the outer member, and the central member, the output shaft is drivingly engaged by another of the inner member, the outer member, and the central member, and a remaining one of the inner member, the outer member, and the central member is secured to the housing.

Images