DESC:FOUR AIR-GAP MOTOR
CROSS REFERENCE TO RELATED APPLICTIONS
The present application claims priority from Indian Provisional Patent Application No. 202221049854 filed on 31/08/2022, the entirety of which is incorporated herein by a reference.
TECHNICAL FIELD
Generally, the present disclosure generally relates to a motor for an electric vehicle. Particularly, the present disclosure relates to a four air-gap motor for an electric vehicle.
BACKGROUND
Recently, electric vehicles have emerged as an alternative to conventional vehicles using gasoline diesel, and similar fossil fuels. Electric vehicles require traction motors to convert the electrical energy into mechanical energy for driving the vehicle. There are multiple types of electric motors being used in electric vehicles. Some known types of electrical motors are radial flux motors and axial flux motors. The radial flux motors are more commonly used as they are known for a longer time, however, radial flux motors have limitations such as longer axial length, low power and torque density, and higher losses and weight.
The axial flux motors overcome these limitations, because, in the axial flux motor, the direction of the lines of magnetic flux that are cut during the operation of the motor is parallel to the rotational axis of the motor. The axial flux motors have characteristics including small axial length, higher power and torque density, lesser losses, and lesser weight compared to radial flux motors.
The axial flux motor comprises a stator having a plurality of wound core teeth or stator assemblies arranged circumferentially. The wound core tooth comprises a bobbin, a core, and conductors wound over the bobbin. However, the stator of the axial flux motor is difficult to assemble due to the requirement of a segmented design. Moreover, the power density is limited by the size and weight of the motor. Furthermore, the axial flux motors have thermal issues and suffer lower efficiency at high speeds. To overcome the limitations of the radial flux motors and the axial flux motors, hybrid flux motors have been developed as a solution combining the advantages of the radial flux motors and the axial flux motors. However, the hybrid flux motors are highly complex to design. Moreover, the hybrid flux motors are difficult to assemble due to their complex structure and components. Moreover, the hybrid flux motors also suffer the limitations of size and weight, as the compactness of the motor reduces with an increase in the power output. Moreover, the hybrid flux motors suffer reduced flux utilization and increased noise and vibrations due to the inefficiencies in the design. Such problems might even lead to motor failure in some cases.
Furthermore, the motors of electric vehicles generally use neodymium magnets such as Neodymium-iron-boron (NdFeB) magnets in the rotor assemblies. However, in the case of the hybrid flux motors, as the cost of the motor is already high compared to other motors, the use of such expensive magnets becomes even more impractical and cost-inefficient.
Therefore, there exists a need for an improved motor for an electric vehicle that overcomes one or more problems associated with the conventional electric flux motor as set forth above.
SUMMARY
An object of the present disclosure is to provide a four air-gap motor for an electric vehicle.
Another object of the present disclosure is to provide a four air-gap hybrid flux motor of an electric vehicle with increased efficiency and power density.
In accordance with an aspect of the present disclosure, there is provided a four air-gap motor for an electric vehicle, comprising a stationary motor shaft, a stator assembly mounted on the stationary motor shaft, at least one roller bearing mounted on the stationary motor shaft, and a rotor assembly. The rotor assembly comprises a radial rotor cup, a radial rotor wall, and a pair of axial rotor plates. The radial rotor cup is mounted on the at least one roller bearing in a radially inward direction of the stator assembly and the pair of axial rotor plates are mounted on the at least one roller bearing in mutually opposite axial directions sandwiching the stator assembly, and wherein the radial rotor wall is mounted on one of the axial rotor plates in a radially outward direction of the stator assembly.
The present disclosure provides a four air-gap motor with improved efficiency and power density. Advantageously, the present invention provides an easy-to-assemble and disassemble four air-gap hybrid flux motor. Furthermore, the four air-gap motor has lower non-flux weight i.e., low weight of components that are not generating any flux, resulting in increased power density and efficiency. Furthermore, the four air-gap motor comprises hybrid magnetic flux, i.e., magnetic flux in both radial and axial directions. Beneficially, the four air-gap motor is utilizing the magnetic flux in all four possible directions comprising radially inward, radially outward, and mutually opposite axial directions. Advantageously, the four air-gap motor is cost-efficient in manufacturing, servicing, and maintenance. Beneficially, the four air-gap motor efficiently utilizes the space inside the motor casing resulting in compact size despite increased power density. Beneficially, the four air-gap motor is suitable for use in high-power applications such as use in the powertrain of electric vehicles. Beneficially, the four air-gap motor is advantageous in terms of reducing flux leakage and maximizing flux utilization resulting in higher power density and efficiency. Beneficially, the four air-gap motor has reduced vibrations due to the balanced nature of rotor assembly.
Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow.
It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
Figure 1 illustrates a perspective view of a four air-gap motor for an electric vehicle, in accordance with an embodiment of the present disclosure.
Figure 2 illustrates an exploded view of the components of the four air-gap motor for an electric vehicle, in accordance with an embodiment of the present disclosure.
Figure 3 illustrates a perspective view of the hollow stator tooth along with flux coil, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognise that other embodiments for carrying out or practicing the present disclosure are also possible.
The description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a four air-gap hybrid flux motor and is not intended to represent the only forms that may be developed or utilized. The description sets forth the various structures and/or functions in connection with the illustrated embodiments; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to employ the present invention variously.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
The terms “comprise”, “comprises”, “comprising”, “include(s)”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, or system that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system. In other words, one or more elements in a system or apparatus preceded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings which are shown by way of illustration-specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
The present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
As used herein, the terms ‘electric vehicle’, ‘EV’, and ‘EVs’ are used interchangeably and refer to any vehicle having stored electrical energy, including the vehicle capable of being charged from an external electrical power source. This may include vehicles having batteries that are exclusively charged from an external power source, as well as hybrid vehicles which may include batteries capable of being at least partially recharged via an external power source. Additionally, it is to be understood that the ‘electric vehicle’ as used herein includes electric two-wheelers, electric three-wheelers, electric four-wheelers, electric pickup trucks, electric trucks, and so forth.
As used herein, the terms “electric motor”, “motor”, “hybrid motor”, “hybrid flux motor”, “four air-gap motor” and “radial-axial flux motor” are used interchangeably and refer to electric motors capable of being implemented in an industrial or automobile application, such as on the work machine or other vehicle. The four air-gap flux motor is a type of electric motor that combines the radial and axial flux configurations. The four air-gap flux motor comprises permanent magnets arranged radially around the stator and permanent magnets arranged axially along the stator. The four air-gap flux motors combine the advantages of both radial and axial configurations, such as the high torque density of radial flux motors and the high efficiency of axial flux motors. The four air-gap flux motor comprises a combination of axial flux rotors and radial flux rotors.
As used herein, the terms “stator” and “stator assembly” are used interchangeably and refer to the stationary part of a motor which provides a magnetic field that drives the rotors (the rotating component of the motor). The stator may act as a field magnet. The stator typically consists of a disc-shaped structure with coil windings. The coil windings, also called stator windings, are responsible for generating a magnetic field when electric current passes through them. The magnetic field produced by the stator interacts with the permanent magnets on the rotor to induce rotation.
As used herein, the terms “stationary motor shaft”, “motor shaft”, “shaft” and “stationary shaft” are used interchangeably and refer to a cylindrical component of the four air-gap motor which is fixed in its position and the rest of the components are mounted on the same. The stationary motor shaft provides mechanical support to the components of the four air-gap motor. It is to be understood that the stationary motor shaft is fixed on a mounting structure and the rotors deliver mechanical power to the mechanical load.
As used herein, the terms “plurality of hollow stator teeth”, “hollow stator teeth”, “stator teeth”, “wound core teeth”, and “teeth” are used interchangeably and refer to a component of the stator assembly that generates and shape the magnetic field and contributes to the motor’s performance. It is to be understood that multiple wound core teeth are arranged in a disc plane to form a segmented stator assembly of the hybrid flux motor. The hollow stator teeth are made of soft magnetic composite material suitable for the high-efficiency operation of the motor. The design and configuration of the wound core teeth, along with the stator windings, play a crucial role in the performance and efficiency of the hybrid flux motor. The hollow stator teeth contribute to the motor's ability to generate torque, provide smooth and reliable operation, and optimize power density.
As used herein, the terms “rotor” and “rotor assembly” are used interchangeably and refer to the rotating part of the motor which is typically made of iron or other magnetic materials. It contains the permanent magnets that generate the magnetic field used to drive the rotor. The rotor converts electrical energy supplied to the stator into mechanical energy.
As used herein, the terms “roller bearings”, and “bearings” are used interchangeably and refers to a type of rolling-element bearing that uses a cylinder (roller) instead of a ball. The roller bearings are designed to carry heavier loads than ball bearings and enables the handling of both radial and axial loads. The roller bearings are also more efficient than ball bearings due to less friction.
As used herein, the term “radial rotor cup” refers to a rotor in an electric motor in that utilizes the radially inward magnetic flux to rotate and deliver mechanical output. It is to be understood that the radial rotor cup is mounted over the roller bearing which in turn is mounted on the stationary motor shaft.
As used herein, the term “radial rotor wall” refers to a rotor in an electric motor in that utilizes the radially outward magnetic flux to rotate and deliver mechanical output. It is to be understood that the radial rotor wall is mounted on one of axial rotor plates.
As used herein, the term “axial rotor plates” refers to a rotor in an electric motor in that utilizes the axial magnetic flux to rotate and deliver mechanical output. It is to be understood that the axial rotor plates are mounted over the roller bearing which in turn is mounted on the stationary motor shaft. Alternatively, the axial rotor plates are mounted on the radial rotor cup.
As used herein, the terms “plurality of wound core bobbin”, “wound core bobbin”, and “bobbin” are used interchangeably and refer to spool-like structure on which the winding of the wire is done to form the flux coil and the bobbin wound with the coil is inserted into the hollow stator tooth. The bobbin may be made up of a non-conductive material that provides electrical insulation and mechanical stability. The bobbin may be specifically designed to hold the coil in place and maintain the desired shape and configuration.
As used herein, the term locking ring “locking ring” refers to a ring-like securing component that is used to hold the plurality of wound core bobbins and the plurality of hollow stator teeth together forming the stator assembly. The locking ring is beneficially designed to restrict the movement of the plurality of wound core bobbins and the plurality of hollow stator teeth in the stator assembly. The locking ring may comprise a plurality of segments.
As used herein, the term “locking disc” refers to a component of the four air-gap motor that is designed to securely hold the stator assembly on the stationary motor shaft.
As used herein, the term “outward resting surface” refers to a surface projecting perpendicularly outward from the cylindrical surface of the stationary motor shaft. The outward resting surface provides mechanical support to the stator assembly for secured mounting of the stator assembly on the stationary motor shaft.
As used herein, the term “inward radial-flux surface” refers to a surface of the stator tooth that guides the magnetic flux in a radially inward direction.
As used herein, the term “outward radial-flux surface” refers to a surface of the stator tooth that guides the magnetic flux in a radially outward direction.
As used herein, the terms “pair of axial-flux surfaces” and “axial-flux surface” are used interchangeably and refer to a surface of the stator tooth that guides the magnetic flux in a mutually opposite axial direction.
As used herein, the terms “flux coil”, and “magnetic flux coil” are used interchangeably and refer to a coil of wire that is used to generate a magnetic field.
As used herein, the term “male formation” refers to a protruding design feature on one of the segments of the locking ring for securing one segment of the locking ring with each adjacent segment of the locking ring. As used herein, the term “cavity” refers to a recessed design feature on one of the segments of the locking ring for securing one segment of the locking ring with each adjacent segment of the locking ring.
As used herein, the term “locking groove” refers to a recessed design feature on the stator tooth for receiving a complimentary component of the locking disc for securely mounting the stator assembly on the stationary motor shaft.
As used herein, the term “locking projection” refers to a protruding design feature on the edge of the locking disc for securely mounting the stator assembly on the stationary motor shaft.
As used herein, the term “securing means” refers to a design feature on the locking disc for securing the locking disc on the stationary motor shaft.
As used herein, the term “motor casing” refers to the outer shell of an electric motor for providing a protective enclosure for the motor's internal components, such as the windings, bearings, shaft, etc.
As used herein, the term “permanent magnet blocks” refers to blocks arranged in the rotors of electric motors, in a specific pattern to create a permanent magnetic flux.
Figure 1, in accordance with an embodiment, describes an exploded view of a four air-gap motor 100 for an electric vehicle. The four air-gap motor 100 comprises a stationary motor shaft 102, a stator assembly 104 mounted on the stationary motor shaft 102, at least one roller bearing 106 mounted on the stationary motor shaft 102, and a rotor assembly. The rotor assembly comprises a radial rotor cup 108, a radial rotor wall 110, and a pair of axial rotor plates 112. The radial rotor cup 108 is mounted on the at least one roller bearing 106 in a radially inward direction of the stator assembly 104 and the pair of axial rotor plates 112 are mounted on the at least one roller bearing 106 in mutually opposite axial directions sandwiching the stator assembly 104, and wherein the radial rotor wall 110 is mounted on one of the axial rotor plates 112 in a radially outward direction of the stator assembly 104.
The four air-gap motor 100 as disclosed, provides improved efficiency and power density. Advantageously, the present invention provides an easy-to-assemble and disassemble four air-gap hybrid flux motor 100. Furthermore, the four air-gap motor 100 has lower non-flux weight i.e., low weight of components that are not generating any flux, resulting in increased power density and efficiency. Furthermore, the four air-gap motor 100 comprises hybrid magnetic flux, i.e., magnetic flux in both radial and axial directions. Beneficially, the four air-gap motor 100 utilizes the magnetic flux in all four directions comprising radially inward, radially outward and mutually opposite axial directions. Beneficially, the four air-gap motor 100 utilizes the magnetic flux directed in the four directions for rotating the rotor resulting in improved torque output. Advantageously, the four air-gap motor 100 is cost-efficient in manufacturing and provides ease of servicing and maintenance. Beneficially, the four air-gap motor 100 efficiently utilizes the space inside the motor casing resulting in compact size despite increased power density. Beneficially, the four air-gap motor 100 is suitable for use in high-power applications such as use in the powertrain of electric vehicles. Beneficially, the four air-gap motor 100 is advantageous in terms of reducing flux leakage and maximizing flux utilization resulting in higher power density and efficiency. Beneficially, the four air-gap motor 100 has reduced vibrations and operates smoothly. Beneficially, the four air-gap motor 100 comprises reduced flux leakage and efficient utilization of the generated magnetic flux.
In an embodiment, the stationary motor shaft 102 comprises a radially outward resting surface 102a along a cylindrical surface of the stationary motor shaft 102. In a specific embodiment, the radially outward resting surface 102a along a cylindrical surface of the stationary motor shaft 102 is located at a specific distance from one end of the stationary motor shaft 102. In an alternative embodiment, the radially outward resting surface 102a along a cylindrical surface of the stationary motor shaft 102 is located at any suitable distance from one end of the stationary motor shaft 102. It is to be understood that the radially outward resting surface 102a along a cylindrical surface of the stationary motor shaft 102 is designed according to dimensions of the stator assembly 104.
In an embodiment, the stator assembly 104 comprises a plurality of hollow stator teeth 104a. Furthermore, in an embodiment, each hollow stator tooth of the plurality of hollow stator teeth 104a comprises an inward radial-flux surface, an outward radial-flux surface, and a pair of axial-flux surfaces. It is to be understood that the inward radial-flux surface guides radial flux in a radially inward direction towards the stationary motor shaft 102. Furthermore, it is to be understood that the outward radial-flux surface guides the radial flux in a radially outward direction. Furthermore, it is to be understood that the pair of axial-flux surfaces guides axial flux in mutually opposite axial directions. Beneficially, the plurality of hollow stator teeth 104a guides flux in all four possible directions for maximum utilization of the flux for generating mechanical output from the hybrid motor 100.
In an embodiment, the stator assembly 104 comprises a plurality of wound core bobbins 104b accommodated within the plurality of hollow stator teeth 104a, and wherein each wound core bobbin of the plurality of wound core bobbins 104b comprises a flux coil 104c of a conductive material for generating a magnetic flux. Preferably, the flux coil 104c is made up of copper. Alternatively, the flux coil 104c is made up of any other suitable material. Beneficially, the flux coil 104c is wound firmly on the bobbin 104b to avoid any movement of the flux coil 104c during the operation of the hybrid flux motor 100.
In an embodiment, the stator assembly 104 comprises a locking ring 116 for securing the plurality of hollow stator teeth 104a and the plurality of wound core bobbins 104b together forming the stator assembly 104. Further, in an embodiment, the locking ring 116 comprises a plurality of segments, wherein each segment of the locking ring 116 comprises a first end and a second end. Beneficially, the locking ring 116 secures the plurality of hollow stator teeth 104a and the plurality of wound core bobbins 104b together to form the stator assembly 104. In a specific embodiment, the locking ring 116 comprises two segments. In another embodiment, the locking ring 116 comprises three segments. In yet another embodiment, the locking ring 116 comprises four segments. In yet another embodiment, the locking ring 116 comprises any suitable number of segments.
In an embodiment, the first end of the segment comprises a male formation and the second end of the segment comprises a cavity, and wherein the cavity of the segment receives the male formation of adjacent segment securing the plurality of segments together forming the locking ring 116. It is to be understood that the cavity of each segment receives the male formation of adjacent segment until the locking ring 116 is completely formed (closed). Beneficially, the male formation of the segment locks into the cavity to securely hold the plurality of segments forming the locking ring 116.
In an embodiment, each wound core bobbin 104b comprises a hole through centre of the wound core bobbin 104b for receiving the locking ring 116. Beneficially, shape of the hole conforms with the shape of the locking ring 116. More beneficially, the locking ring 116 is firmly received in the hole restricting any sideways movement of the locking ring 116 inside the hole to prevent any vibration in the stator assembly 104, during the operation of the hybrid flux motor 100.
In an embodiment, the stator assembly 104 is formed by inserting the plurality of segments of the locking ring 116 through the plurality of wound core bobbins 104b accommodated within the plurality of hollow stator teeth 104a. It is to be understood that the plurality of wound core bobbins 104b snugly fits into the plurality of hollow stator teeth 104a to prevent any vibration in the stator assembly 104, during the operation of the hybrid flux motor 100. Furthermore, it is to be understood that locking ring 116 securely holds the plurality of hollow stator teeth 104a (with the plurality of wound core bobbins 104b) together to prevent any vibration in the stator assembly 104, during the operation of the hybrid flux motor 100.
In an embodiment, each of the hollow stator tooth 104a comprises at least one locking groove for secure mounting of the stator assembly 104 on the stationary motor shaft 102. In another embodiment, the hollow stator tooth 104a comprises a plurality of locking groove for secure mounting of the stator assembly 104 on the stationary motor shaft 102. In yet another embodiment, the hollow stator tooth 104a comprises any suitable number of locking grooves for secure mounting of the stator assembly 104 on the stationary motor shaft 102. Beneficially, the locking grooves are shaped in conformity with the corresponding locking mechanism to prevent any vibration in the stator assembly 104, during the operation of the hybrid flux motor 100.
In an embodiment, the stator assembly 104 comprises a locking disc 114 for securely mounting the stator assembly 104 on the stationary motor shaft 102. In an embodiment, the locking disc 114 comprises a plurality of locking projections projecting from an edge of the locking disc 114, and wherein the locking projections lock in the locking grooves of the plurality of hollow stator teeth 104a. Beneficially, the plurality of locking projections are shaped in conformity with the locking grooves to ensure secure locking of the locking projections into the locking grooves. Beneficially, such secure locking of the locking projections into the locking grooves prevents any vibration in the stator assembly 104, during the operation of the hybrid flux motor 100.
In an embodiment, the locking disc 114 comprises at least one securing means for securely mounting the locking disc 114 on the stationary motor shaft 102, along with the stator assembly 104. It is to be understood that the at least one securing means of the locking disc 114 is a combination of suitable mechanical components that enables secure mounting of the locking disc 114 on the stationary motor shaft 102, along with the stator assembly 104. In an embodiment, the at least one securing means comprises holes and screws, nuts and bolts, holes and rivets, or a combination thereof. It is to be understood that the locking disc 114 is secured on the radially outward resting surface 102a along a cylindrical surface of the stationary motor shaft 102 to securely mount the stator assembly 104 on the stationary motor shaft 102. Beneficially, such secure mounting of the stator assembly 104 on the stationary motor shaft 102 prevents any vibration in the stator assembly 104, during the operation of the hybrid flux motor 100.
In an embodiment, the plurality of locking projections are made of magnetic material. It is to be understood that the plurality of locking projections are inserted into the locking grooves that are located on the flux guiding surface of the plurality of hollow stator tooth 104a. Thus, beneficially, the plurality of locking projections are made of magnetic material to maintain the maximum utilization of the magnetic flux and prevent any possible flux leakage.
In an embodiment, the inward radial-flux surface of the plurality of hollow stator teeth 104a guides the magnetic flux in the radially inward direction. Beneficially, the magnetic flux guided in the radially inward direction rotates the radial rotor cup 108.
In an embodiment, the radial rotor cup 108 comprises at least one ring of the permanent magnet blocks 108a facing towards the stator assembly 104, wherein the at least one ring of the permanent magnet blocks 108a interacts with the radially inward magnetic flux to rotate the radial rotor cup 108. Beneficially, the at least one ring of the permanent magnet blocks 108a, is aligned non-linearly with respect to each other, to reduce cogging torque in the radial rotor cup 108.
In an embodiment, the outward radial-flux surface of the plurality of hollow stator teeth 104a guides the magnetic flux in the radially outward direction. Beneficially, the magnetic flux guided in the radially outward direction rotates the radial rotor wall 110.
In an embodiment, the radial rotor wall 110 comprises at least one ring of the permanent magnet blocks 110a facing towards the stator assembly 104, wherein the at least one ring of the permanent magnet blocks 110a interacts with the radially outward magnetic flux to rotate the radial rotor wall 110. Beneficially, the at least one ring of the permanent magnet blocks 110a, is aligned non-linearly with respect to each other, to reduce cogging torque in the radial rotor wall 110.
In an embodiment, the pair of axial-flux surfaces of the plurality of hollow stator teeth 104a guides the magnetic flux in the mutually opposite axial directions. Beneficially, the magnetic flux guided in the axial directions rotates the pair of the axial rotor plates 112.
In an embodiment, each of the axial rotor plates 112 comprises a disc of permanent magnet blocks 112a facing towards the stator assembly 104, wherein the discs of the permanent magnet blocks 112a interact with mutually opposite axial magnetic flux to rotate each of the axial rotor plates 112.
In an embodiment, the permanent magnet blocks 112a of the discs are skewed in direction of rotation of each of the axial rotor plates 112 to reduce a cogging torque. It is to be understood that the skewing of the permanent magnet blocks 112a in direction of rotation of each of the axial rotor plates 112 causes misalignment between the rotor magnetic field and stator magnetic flux. Beneficially, the misalignment between the rotor magnetic field and stator magnetic flux reduces the cogging torque inside the motor 100.
In an embodiment, the permanent magnet blocks 108a, 110a, 112a are made of ferrite material. Beneficially, the disclosed four air-gap motor 100 has increased power density that enables the usage of ferrite material in the permanent magnet blocks 108a, 110a, 112a of the motor 100. It is to be understood that the power loss occurred due to the use of ferrite material permanent magnet blocks 108a, 110a, 112a is compensated by the increased power density resulting from the use of the radial rotor cup 108, the radial rotor wall 110 and the pair of axial rotor plates 108.
In an embodiment, the pair of axial rotor plates 112 and the radial rotor wall 110 forms a casing of the four air-gap motor 100. Beneficially, an outer surface of the pair of axial rotor plates 112 and the radial rotor wall 110 acts as the casing of the four air-gap motor 100. In an embodiment, the outer surface of the pair of axial rotor plates 112 and the radial rotor wall 110 is made of mild steel. In an alternative embodiment, the outer surface of the pair of axial rotor plates 112 and the radial rotor wall 110 is made of any suitable material.
In an embodiment, a mechanical load is connected to the casing of the four air-gap motor 100 to receive a mechanical output from the four air-gap motor 100. It is to be understood that the stationary shaft 102 is fixed in its position and the mechanical output of the four air-gap motor 100 is delivered by the motor casing formed by the rotor assembly.
In an embodiment, the radial rotor cup 108, the pair of axial rotor plates 112 and the radial rotor wall 110 are connected together to form the rotor assembly. In a specific embodiment, the radial rotor cup 108 is mounted on the at least one roller bearing 106. The pair of axial rotor plates 112 are mounted on the radial rotor cup 108. The radial rotor wall 110 is fixed on a circumference of the pair of axial rotor plates 112. It is to be understood that fasteners may be used to assemble the rotor assembly together.
Figure 2, in accordance with an embodiment, describes an exploded view of the four air-gap motor 100 for an electric vehicle. The four air-gap motor 100 comprises a stationary motor shaft 102, a stator assembly 104 mounted on the stationary motor shaft 102, at least one roller bearing 106 mounted on the stationary motor shaft 102, and a rotor assembly. The rotor assembly comprises a radial rotor cup 108, a radial rotor wall 110, and a pair of axial rotor plates 112. The radial rotor cup 108 is mounted on the at least one roller bearing 106 in a radially inward direction of the stator assembly 104 and the pair of axial rotor plates 112 are mounted on the at least one roller bearing 106 in mutually opposite axial directions sandwiching the stator assembly 104, and wherein the radial rotor wall 110 is mounted on one of the axial rotor plates 112 in a radially outward direction of the stator assembly 104.
In an embodiment, the four air-gap motor 100 comprises a stationary motor shaft 102, a stator assembly 104 mounted on the stationary motor shaft 102, at least one roller bearing 106 mounted on the stationary motor shaft 102, and a rotor assembly. The rotor assembly comprises a radial rotor cup 108, a radial rotor wall 110, and a pair of axial rotor plates 112. The radial rotor cup 108 is mounted on the at least one roller bearing 106 in a radially inward direction of the stator assembly 104 and the pair of axial rotor plates 112 are mounted on the at least one roller bearing 106 in mutually opposite axial directions sandwiching the stator assembly 104, and wherein the radial rotor wall 110 is mounted on one of the axial rotor plates 112 in a radially outward direction of the stator assembly 104. Furthermore, the stationary motor shaft 102 comprises a radially outward resting surface 102a along a cylindrical surface of the stationary motor shaft 102. Furthermore, the stator assembly 104 comprises a plurality of hollow stator teeth 104a. Furthermore, each hollow stator tooth of the plurality of hollow stator teeth 104a comprises an inward radial-flux surface, an outward radial-flux surface, and a pair of axial-flux surfaces. It is to be understood that the inward radial-flux surface guides radial flux in a radially inward direction towards the stationary motor shaft 102. Furthermore, the stator assembly 104 comprises a plurality of wound core bobbins 104b accommodated within the plurality of hollow stator teeth 104a, and wherein each wound core bobbin of the plurality of wound core bobbins 104b comprises a flux coil 104c of a conductive material for generating a magnetic flux. Furthermore, the stator assembly 104 comprises a locking ring 116 for securing the plurality of hollow stator teeth 104a and the plurality of wound core bobbins 104b together forming the stator assembly 104. Furthermore, the stator assembly 104 comprises a locking disc 114 for securely mounting the stator assembly 104 on the stationary motor shaft 102. Furthermore, the locking disc 114 comprises at least one securing means for securely mounting the locking disc 114 on the stationary motor shaft 102, along with the stator assembly 104. Furthermore, the inward radial-flux surface of the plurality of hollow stator teeth 104a guides the magnetic flux in the radially inward direction. Furthermore, the radial rotor cup 108 comprises at least one ring of the permanent magnet blocks 108a facing towards the stator assembly 104, wherein the at least one ring of the permanent magnet blocks 108a interacts with the radially inward magnetic flux to rotate the radial rotor cup 108. Furthermore, the outward radial-flux surface of the plurality of hollow stator teeth 104a guides the magnetic flux in the radially outward direction. Furthermore, the radial rotor wall 110 comprises at least one ring of the permanent magnet blocks 110a facing towards the stator assembly 104, wherein the at least one ring of the permanent magnet blocks 110a interacts with the radially outward magnetic flux to rotate the radial rotor wall 110. Furthermore, the pair of axial-flux surfaces of the plurality of hollow stator teeth 104a guides the magnetic flux in the mutually opposite axial directions. Furthermore, each of the axial rotor plates 112 comprises a disc of permanent magnet blocks 112a facing towards the stator assembly 104, wherein the discs of the permanent magnet blocks 112a interact with mutually opposite axial magnetic flux to rotate each of the axial rotor plates 112. Furthermore, the permanent magnet blocks 112a of the discs are skewed in direction of rotation of each of the axial rotor plates 112 to reduce a cogging torque. Furthermore, the pair of axial rotor plates 112 and the radial rotor wall 110 forms a casing of the four air-gap motor 100. Furthermore, a mechanical load is connected to the casing of the four air-gap motor 100 to receive a mechanical output from the four air-gap motor 100.
Figure 3, in accordance with an embodiment, describes an exploded view of a tooth assembly 200 of the stator assembly 104. The tooth assembly 200 comprises a hollow stator tooth 104a with a wound core bobbin 104b accommodated within. The wound core bobbin 104b comprises a flux coil 104c of a conductive material. A locking ring 116 is inserted through a hole in the wound core bobbin 104b. A plurality of hollow stator tooth 104a with the wound core bobbin 104b accommodated within, is mounted on the locking ring 116 until the locking ring 116 is complete and occupied with the tooth assembly 200 to form the stator assembly 104.
In the description of the present invention, it is also to be noted that, unless otherwise explicitly specified or limited, the terms “disposed,” “mounted,” and “connected” are to be construed broadly, and may for example be fixedly connected, detachably connected, or integrally connected, either mechanically or electrically. They may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Modifications to embodiments and combinations of different embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, and “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural where appropriate.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

,CLAIMS:WE CLAIM:
1. A four air-gap motor (100) for an electric vehicle, comprising:
- a stationary motor shaft (102);
- a stator assembly (104) mounted on the stationary motor shaft (102);
- at least one roller bearing (106) mounted on the stationary motor shaft (102); and
- a rotor assembly comprising:
- a radial rotor cup (108),
- a radial rotor wall (110), and
- a pair of axial rotor plates (112),
wherein the radial rotor cup (108) is mounted on the at least one roller bearing (106) in a radially inward direction of the stator assembly (104) and the pair of axial rotor plates (112) are mounted on the at least one roller bearing (106) in mutually opposite axial directions sandwiching the stator assembly (104), and wherein the radial rotor wall (110) is mounted on one of the axial rotor plates (112) in a radially outward direction of the stator assembly (104).
2. The four air-gap motor (100) as claimed in claim 1, wherein the stationary motor shaft (102) comprises a radially outward resting surface (102a) along a cylindrical surface of the stationary motor shaft (102).
3. The four air-gap motor (100) as claimed in claim 1, wherein the stator assembly (104) comprises a plurality of hollow stator teeth (104a), and wherein each hollow stator tooth of the plurality of hollow stator teeth (104a) comprises: an inward radial-flux surface, an outward radial-flux surface, and a pair of axial-flux surfaces.
4. The four air-gap motor (100) as claimed in any of the claims 1 and 3, wherein the stator assembly (104) comprises a plurality of wound core bobbins (104b) accommodated within the plurality of hollow stator teeth (104a), and wherein each wound core bobbin of the plurality of wound core bobbins (104b) comprises a flux coil (104c) of a conductive material for generating a magnetic flux.
5. The four air-gap motor (100) as claimed in any of the claims 1, 3 and 4, wherein the stator assembly (104) comprises a locking ring (116) for securing the plurality of hollow stator teeth (104a) and the plurality of wound core bobbins (104b) together forming the stator assembly (104).
6. The four air-gap motor (100) as claimed in any of the claims 1, 3, 4 and 5, wherein the stator assembly (104) comprises a locking disc (114) for securely mounting the stator assembly (104) on the stationary motor shaft (102), and wherein the locking disc (114) comprises a plurality of locking projections projecting from an edge of the locking disc (114).
7. The four air-gap motor (100) as claimed in claim 6, wherein the plurality of locking projections locks in a locking groove of each of the plurality of hollow stator teeth (104a).
8. The four air-gap motor (100) as claimed in any of the claims 6 and 7, wherein the locking disc (114) comprises at least one securing means for securely mounting the locking disc (114) on the stationary motor shaft (102), along with the stator assembly (104).
9. The four air-gap motor (100) as claimed in any of the claims 1 and 3, wherein the inward radial-flux surface of the plurality of hollow stator teeth (104a) guides the magnetic flux in the radially inward direction.
10. The four air-gap motor (100) as claimed in any of the claims 1, 3 and 9, wherein the radial rotor cup (108) comprises at least one ring of the permanent magnet blocks (108a) facing towards the stator assembly (104), wherein the at least one ring of the permanent magnet blocks (108a) interacts with the radially inward magnetic flux to rotate the radial rotor cup (108).
11. The four air-gap motor (100) as claimed in any of the claims 1 and 3, wherein the outward radial-flux surface of the plurality of hollow stator teeth (104a) guides the magnetic flux in the radially outward direction.
12. The four air-gap motor (100) as claimed in any of the claims 1, 3 and 11, wherein the radial rotor wall (110) comprises at least one ring of the permanent magnet blocks (110a) facing towards the stator assembly (104), wherein the at least one ring of the permanent magnet blocks (110a) interacts with the radially outward magnetic flux to rotate the radial rotor wall (110).
13. The four air-gap motor (100) as claimed in any of the claims 1 and 3, wherein the pair of axial-flux surfaces of the plurality of hollow stator teeth (104a) guides the magnetic flux in the mutually opposite axial directions.
14. The four air-gap motor (100) as claimed in any of the claims 1, 3 and 13, wherein each of the axial rotor plates (112) comprises a disc of permanent magnet blocks (112a) facing towards the stator assembly (104), wherein the discs of the permanent magnet blocks (112a) interact with mutually opposite axial magnetic flux to rotate each of the axial rotor plates (112).
15. The four air-gap motor (100) as claimed in claim 14, wherein the permanent magnet blocks (112a) of the discs are skewed in direction of rotation of each of the axial rotor plates (112) to reduce a cogging torque.
16. The four air-gap motor (100) as claimed in any of the claims 10, 12 and 14, wherein the permanent magnet blocks (108a, 110a, 112a) are made of ferrite material.
17. The four air-gap motor (100) as claimed in claim 1, wherein the pair of axial rotor plates (112) and the radial rotor wall (110) forms a casing of the four air-gap motor (100).
18. The four air-gap motor (100) as claimed in claim 1 and 17, wherein a mechanical load is connected to the casing of the four air-gap motor (100) to receive a mechanical output from the four air-gap motor (100).