Method for manufacturing an axial flux rotor and related axial flux rotor

Abstract

In one aspect, the present invention provides a three-phase axial flux stator. The stator includes a plurality of stator modules oriented in an axial direction, and each stator module includes a pair of teeth connected by a yoke. The stator also includes a plurality of windings, each winding being wound around one of the stator modules. The stator modules and the windings generate a three-phase magnetic flux in the axial direction.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Non-Provisional Patent Application No. 15 / 937,016, filed on March 27, 2018, the entire disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The field of the invention relates generally to electric machines, and more particularly to axial flux electric machines having axially embedded permanent magnet rotors. Background Art

[0004] One of the many applications of electric motors is to propel fluids, such as blowing air with a fan or blower when heating or cooling, and pumping liquids such as water to recirculate the water, such as in a swimming pool or spa. The electric motor can be configured to rotate an impeller within the pump or blower, which displaces the fluid, thereby causing the fluid to flow. Many gas appliances include electric motors, such as water heaters, boilers, pool heaters, space heaters, furnaces, and radiant heaters. In some examples, the electric motor provides power for a blower that moves air or a fuel / air mixture through the appliance. In other examples, the electric motor provides power for a blower that distributes the air output from the appliance.

[0005] A common motor used in such systems is an alternating current (AC) induction motor. Typically, an AC induction motor is a radial flux motor, in which the magnetic flux extends radially from the axis of rotation. Another type of motor that can be used in the above applications is an electronically commutated motor (ECM). ECMs may include, but are not limited to, brushless direct current (BLDC) motors, permanent magnet alternating current (PMAC) motors, and variable reluctance motors. Typically, these motors provide higher electrical efficiency than AC induction motors. Some ECMs have an axial flux configuration, in which the magnetic flux in the air gap extends in a direction parallel to the axis of rotation of the rotor.

[0006] Typically, to achieve adequate efficiency, such ECM motors utilize rotors with permanent magnets, which provide higher efficiency than induction motors. To further increase their efficiency, such ECM motors typically use rare earth magnets, which, while increasing efficiency, are very expensive and available only from very limited locations. It would be desirable to achieve increased motor efficiency without the need for rare earth magnets.

[0007] Typically, such ECM motors are provided with permanent magnets made of a permanently magnetizable material that has been magnetized before the magnets are assembled into the rotor. When assembled into the assembly of such a rotor, the magnetized magnets have an attractive force on magnetically attracted materials (e.g., ferrous materials). Typically, portions of the stator core (including the stator core) and portions of the rotor (including the rotor poles) are made of ferrous materials. In addition, the motor housing, motor bearings, and motor shaft are typically made of ferrous materials. The attraction of the magnets to these ferrous materials makes assembly very difficult. It is desirable to solve the problems associated with the assembly of these permanent magnets. Summary of the invention

[0008] In one aspect, a method for manufacturing an axial flux motor is provided. The method includes: providing a stator; providing a rotor having a first outer end face and a second outer end face opposite and parallel to the first outer end face; rotatably fixing the rotor to the stator about a center of rotation of the rotor; providing a magnetizable permanent magnet having a longitudinal axis thereof; firmly fixing the magnet to the rotor so that the longitudinal axis is positioned in a radial direction relative to the center of rotation of the rotor, thereby defining a radially inward surface and an opposite radially outward surface, the magnet having a first end face adjacent to the first outer end face of the rotor and having a second end face adjacent to the second outer end face of the rotor; partially magnetizing the magnet by positioning a first magnetizing device adjacent to the first end face of the magnet; and further magnetizing the magnet by positioning a second magnetizing device adjacent to the second end face of the magnet.

[0009] In another aspect, an axial flux rotor may be provided, wherein the step of providing the rotor includes the step of providing a body having an outer periphery defined by an outer radius OR. The body also has a central opening defined by an inner radius IR. The step of providing the body includes stamping a plurality of laminations. Each lamination in the plurality of laminations includes opposing parallel outer planes and opposing first and second ends. The step of providing the body also includes superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations.

[0010] The step of providing a body also includes repeating the above-mentioned superimposing step to provide a rotor pole. The step of providing a body also includes positioning the rotor pole in a spaced relationship, wherein the opposing first and second ends are oriented tangentially relative to the center of rotation of the rotor. The opposing first and second ends define an outer radius OR and an inner radius IR, respectively.

[0011] In yet another aspect, an axial flux rotor may be provided wherein the step of providing a body further comprises overmolding the rotor poles with a moldable material after positioning the rotor poles in spaced relationship.

[0012] In yet another aspect, an axial flux rotor may be provided wherein the step of providing a magnetizable permanent magnet includes providing one of a ferrite magnet, a bonded neodymium magnet, and a sintered neodymium magnet.

[0013] In yet another aspect, an axial flux rotor may be provided, further comprising the steps of providing a second magnetizable permanent magnet having a longitudinal axis thereof and securely securing the second magnetizable permanent magnet to the rotor, wherein the longitudinal axis is positioned in a radial direction relative to a center of rotation of the rotor, thereby defining a radially inward surface of the second magnet and an opposing radially outward surface of the second magnet. The second magnet may have a first end surface adjacent to a first outer end surface of the rotor, and may have a second end surface adjacent to a second outer end surface of the rotor.

[0014] In yet another aspect, an axial flux rotor may be provided, further comprising the steps of partially magnetizing the second magnet by positioning a first magnetizing device near a first end surface of the second magnet and further magnetizing the second magnet by positioning a second magnetizing device near a second end surface of the second magnet.

[0015] In yet another aspect, an axial flux rotor may be provided wherein the step of providing a magnetizable permanent magnet having its longitudinal axis includes providing a plurality of magnetizable permanent magnets, each permanent magnet of the plurality of magnetizable permanent magnets having its longitudinal axis.

[0016] In yet another aspect, an axial flux rotor may be provided, wherein the step of securely securing the magnets to the rotor includes securely securing each of the plurality of magnetizable permanent magnets to the rotor, wherein the longitudinal axis of each of the plurality of magnetizable permanent magnets is positioned in a radial direction relative to a center of rotation of the rotor, thereby defining a radially inward surface and an opposing radially outward surface of each of the plurality of magnetizable permanent magnets. Each of the plurality of magnetizable permanent magnets may have a first end surface adjacent to a first outer end surface of the rotor, and may have a second end surface adjacent to a second outer end surface of the rotor.

[0017] In yet another aspect, an axial flux rotor may be provided wherein the step of partially magnetizing the magnets comprises positioning a first magnetizing device adjacent to a first end surface of each of the plurality of magnetizable permanent magnets, and wherein the step of further magnetizing the magnets comprises positioning a second magnetizing device adjacent to a second end surface of each of the plurality of magnetizable permanent magnets.

[0018] In yet another aspect, an axial flux rotor may be provided, wherein the step of providing a magnetizable permanent magnet comprises providing a magnet having a shape given by the equation

[0019]

[0020] The minimum depth of an axially embedded magnet is defined as , where BrS is the remanent flux density of the surface mount magnet, where OR is the outer radius of the body, where IR is the inner radius of the body, where N is the number of rotor poles, and where BrA is the remanent flux density of the axially embedded magnet.

[0021] In yet another aspect, an axial flux rotor may be provided wherein the step of providing a magnetizable permanent magnet includes providing a magnetizable ring / disk positioned adjacent one of the opposing first and second end faces, the magnetizable ring defining an outer periphery and a central opening.

[0022] In yet another aspect, an axial flux rotor may be provided wherein the step of providing a rotor includes the step of providing a body having an outer periphery defined by an outer radius OR.

[0023] In yet another aspect, an axial flux rotor may be provided wherein the body further has a central opening defined by an inner radius IR.

[0024] In yet another aspect, an axial flux rotor may be provided, wherein the step of providing a body includes: providing a lamination of ferrous material; punching spaced apart openings in the lamination; and winding the lamination in a circular form to form a laminated rotor core while aligning some of the spaced apart openings to provide cavities for receiving magnets and providing rotor poles in spaced apart relationship, wherein opposed parallel outer planes of the laminations are oriented tangentially relative to the center of rotation of the rotor. The outer planes define an outer radius OR and an inner radius IR.

[0025] In yet another aspect, a method of manufacturing an axial flux rotor is provided. The method includes the steps of stamping a plurality of laminations, and superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations. Each of the plurality of laminations includes opposing parallel outer planes and opposing first and second ends. The method also includes: superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations; repeating the superimposing steps to provide rotor poles; and positioning the rotor poles in a spaced relationship around a center of rotation of the rotor, wherein the opposing first and second ends are oriented tangentially relative to the center of rotation of the rotor.

[0026] In yet another aspect, the method may further include the steps of providing a plurality of magnetizable permanent magnets, each magnet having a longitudinal axis thereof; and positioning each of the magnets between adjacent rotor poles, wherein the longitudinal axis is positioned in a radial direction relative to a center of rotation of the rotor, thereby defining a radially inward surface and an opposing radially outward surface. The magnet has a first end surface adjacent to a first outer end surface of the rotor, and has a second end surface adjacent to a second outer end surface of the rotor.

[0027] In yet another aspect, the method may further include the step of overmolding the rotor poles with a moldable material after positioning the rotor poles in spaced-apart relationship.

[0028] In yet another aspect, the method may further include the steps of partially magnetizing the magnet by positioning a first magnetizing device adjacent to a first end face of the magnet, and further magnetizing the magnet by positioning a second magnetizing device adjacent to a second end face of the magnet.

[0029] In yet another aspect, the method may be provided wherein the step of providing a plurality of magnetizable permanent magnets includes providing one of ferrite magnets, bonded neodymium magnets, and sintered neodymium magnets.

[0030] In yet another aspect, the method may be provided wherein positioning the rotor poles in spaced relationship includes positioning each lamination of the plurality of laminations such that the laminations form a body having an outer periphery defined by an outer radius OR and a central opening defined by an inner radius IR.

[0031] In yet another aspect, the method may be provided wherein the step of providing a magnetizable permanent magnet comprises providing a magnet having a shape given by the equation

[0032]

[0033] defined as the minimum length of the magnet, where BrS is the remanent flux density of a surface mounted magnet, where OR is the outer radius of the body, where IR is the inner radius of the body, where N is the number of rotor poles, and where BrA is the remanent flux density of an axially embedded magnet.

[0034] In yet another aspect, the method may further include the step of providing a magnetizable ring / disk positioned proximate one of the opposing first and second end faces. The magnetizable ring / disk defines an outer periphery and a central opening.

[0035] In yet another aspect, an axial flux rotor for use in an axial flux electric machine prepared by a process is provided. The process includes the steps of stamping a plurality of laminations and superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations. Each lamination of the plurality of laminations includes opposing parallel outer planes and opposing first and second ends. The process also includes the following steps: repeating the above-mentioned stacking step to provide a first rotor pole; repeating the above-mentioned step to provide at least one additional rotor pole, thereby providing a plurality of rotor poles; positioning the plurality of rotor poles in a spaced-apart relationship around a rotor rotation center, wherein the opposite first and second ends of the laminations are oriented tangentially relative to the rotor rotation center; providing a plurality of magnetizable permanent magnets, each magnet having a longitudinal axis thereof; positioning each of the magnets between adjacent rotor poles, wherein the longitudinal axis is positioned in a radial direction relative to the rotor rotation center, thereby defining a radially inward surface and an opposite radially outward surface, the magnet having a first end surface adjacent to a first outer end surface of the rotor and having a second end surface adjacent to a second outer end surface of the rotor; and overmolding the rotor poles with a moldable material after positioning each of the magnets between adjacent rotor poles.

[0036] In yet another aspect, the process may be provided wherein the step of positioning the rotor poles in spaced relationship includes providing positioning the rotor poles in spaced relationship to form a body having an outer periphery defined by an outer radius OR and a central opening defined by an inner radius IR, and wherein the step of providing a plurality of magnetizable permanent magnets includes providing a plurality of magnetizable permanent magnets, each magnet having a value determined by equation

[0037]

[0038] The minimum length defined is , where BrS is the remanent flux density of a surface mounted magnet, where OR is the outer radius of the body, where IR is the inner radius of the body, where N is the number of rotor poles, and where BrA is the remanent flux density of an axially embedded magnet.

[0039] In yet another aspect, the process may further include the step of providing a magnetizable ring / disk positioned proximate one of the opposing first and second end faces. The magnetizable ring defines an outer periphery and a central opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a cross-sectional view of an exemplary axial flux electric machine;

[0041] Figure 2 yes Figure 1 An exploded view of an axial flux motor is shown;

[0042] Figure 3 yes Figure 1 and2 An exploded view of the stator of the axial flux motor shown;

[0043] Figure 4 yes Figure 1 and 2 A plan view of the rotor of the axial flux motor shown in;

[0044] Figure 4A yes Figure 4 A partial cross-sectional view of a rotor showing a magnet in a recessed portion;

[0045] Figure 4 B is Figure 4 A perspective view of the magnetic poles used in the rotor;

[0046] Figure 4 C is used for Figure 4 A perspective view of the laminations in the magnetic pole of B;

[0047] Figure 4 D is Figure 4 A perspective view of a magnet used in a rotor of FIG.

[0048] Figure 5 is a perspective view of another embodiment of the present invention in the form of a rotor that can be used in an axial flux machine and has magnetic rings;

[0049] Figure 5A yes Figure 5 A perspective view of a magnetic ring of a rotor;

[0050] Figure 5B is with Figure 5B A partial cross-sectional view of a rotor similar to that of the rotor of the present invention, showing magnets in a recessed portion that do not extend from a first end face of the rotor to a second end face;

[0051] Figure 6 is a perspective view of another embodiment of the present invention in the form of a rotor that can be used in an axial flux machine and has pie-shaped poles and rectangular magnets;

[0052] Fig. 6A yes Figure 6 A perspective view of a magnet used in a rotor of FIG.

[0053] Figure 6B yes Figure 6 A perspective view of a magnetic pole used in a rotor of; and

[0054] Figure 7 is a perspective view of another exemplary stator that has been made from a metal roll and that can be used with an axial flux rotor according to the present invention.

[0055] Figure 8 is a partial cross-sectional view of the magnetization device, wherein Figure 4The rotor is positioned in the magnetizing device;

[0056] Fig. 9 yes Figure 8 A plan view of a magnetizing device, wherein Figure 4 The rotor is positioned in the magnetizing device;

[0057] Fig.10 is a flow chart of an exemplary method according to the present invention;

[0058] Fig.11 is a flow chart of another exemplary method according to the present invention;

[0059] Fig. 12A is a first portion of a flowchart of a method for making an exemplary article according to the present invention; and

[0060] Fig. 12B is the second part of the flowchart of the method for manufacturing the article of FIG. 12 according to the present invention. DETAILED DESCRIPTION

[0061] Figure 1 is a cross-sectional view of an exemplary axial flux machine 10 . Figure 2 is an exploded view of the axial flux machine 10 . Figure 1 and 2 Common components are indicated by the same reference numerals. In the exemplary embodiment, the electric machine 10 is an electric motor having a first end 12 and a second end 14. Alternatively, the electric machine 10 can be operated as a generator. The axial flux electric machine 10 can generally include a housing 16, a rotor assembly 18, a first bearing assembly 20, a second bearing assembly 22, and a stator assembly 24. A first end mount 26 is coupled to the housing 16 at the first end 12 of the electric machine. A second end mount 28 is connected to the stator assembly 24 at the second end 14 of the electric machine.

[0062] like Figure 1-4 As shown, the electric machine 10 may be an axial flux electric machine. The electric machine 10 includes a housing 16 and a stator 23 fixedly fixed to the housing 16. The stator 23 may be part of a stator assembly 24.

[0063] The electric machine 10 also includes a rotor in the form of, for example, a rotor assembly 18 rotatably fixed to the housing 16. The rotor assembly 18 may include a body or rotor core 30 defining an axis of rotation 36 of the body 30. The body 30 has opposing first and second end faces or surfaces 40 and 41, respectively.

[0064] like Figure 4 , 4AAs shown in Figures 5 and 6, the body 30 defines a plurality of recesses 31 formed in the body 30. The body 30 may be made of any suitable material and may be manufactured using any available manufacturing process. For example, the rotor 30 may be made of a soft magnetic alloy (SMA), a soft magnetic composite (SMC) material, and / or a powdered ferrite material using a sintering process. In order to minimize eddy current losses, the current path along the magnetic flux lines 33 may be interrupted in a suitable manner.

[0065] For example and Figure 4 As shown, the body 30 can be formed by a plurality of sheets or stacks 48. Each sheet can be coated with a non-conductive coating 27 on its end face 25. Although the sheets 48 can each have different thicknesses, for simplicity, each sheet has a substantially uniform thickness. Each sheet in the plurality of sheets defines an opposite end face 25.

[0066] Each of the plurality of plates 48 is in surface contact with one of the opposing end faces 25 of at least another of the plurality of plates 48. The rotor assembly 18 also has a plurality of spaced magnets 34. Each of the plurality of magnets 34 fits snugly into one of the plurality of recesses 31.

[0067] Although the plates can form a continuous core 30 and the magnets 34 can be fitted to the core 30, it should be understood that some plates can be combined to form the poles 19, with the plates of each pole spaced apart from the plates of the other poles. In this configuration, a bonding material such as resin 39 can be used to interconnect all of the components that form the rotor assembly 18. In this configuration, the core 30 can include a center portion 21. The center portion 21 can support the central rotor shaft 32 and the poles 19, and the magnets 34 can extend from the core periphery 43 to the center portion 21 of the core 30.

[0068] The rotor assembly 18 can be manufactured by placing the poles 19, the magnets 34, and the shaft 32 in a resin mold (not shown) and injecting resin into the mold, bonding the magnets 34, the shaft 32, and the poles 19 together. Note that the shaft 32 is not placed in the mold, but rather can be assembled into the rotor assembly 18 later.

[0069] like Figure 1-4 As shown, an axial flux machine 10 may be provided wherein a rotor or rotor core 30 is generally cylindrical and includes a plurality of rotor poles 19 .

[0070] like Figure 1-4As shown, rotor assembly 18 can include a rotor core 30 coupled to a shaft 32, and a plurality of permanent magnets 34 can be coupled to rotor 30. For example, permanent magnets made of neodymium, ferrite, or other materials can be surface mounted to one end surface of rotor core 30. Alternatively, the permanent magnets can be made of neodymium, ferrite, or other materials, and can be formed as an annular magnet with alternating magnetized segments. However, any suitable permanent magnet shape and material can be used that enables motor 10 to operate as described herein. It should be understood that the radially extending magnets 34 described below have the advantage of enhancing magnetic flux for a given mass of magnetic material.

[0071] The rotor assembly 18 can rotate within the housing 16, and more specifically, can rotate within the first bearing assembly 20 and the second bearing assembly 22 about the rotation axis 36. It should be understood that other support schemes can be used to support the rotating rotor assembly within the housing. For example, a single bearing assembly (not shown) can be used and can be arranged in the position where the first bearing assembly or the second bearing assembly is located.

[0072] In the exemplary embodiment, rotor core 30 includes an outer periphery 43 and an axial central opening or inner periphery 46 having a diameter corresponding to the diameter of shaft 32. In the exemplary embodiment, rotor 30 includes a plurality of laminations 48 that are interlocked or loose. For example, laminations 48 are made of a plurality of stamped layers of stamped metal, such as steel.

[0073] Alternatively, the rotor 30 may be made of SMC material, SMA material, and / or powdered ferrite material using a sintering process. Alternatively, the rotor 30 may be made of SMC material, SMA material, and / or powdered ferrite material using a sintering process. Alternatively, the rotor 30 may be machined and / or cast from any suitable material. In the exemplary embodiment, the rotor assembly 18 is driven by an electronic controller (not shown), such as a sinusoidal or trapezoidal electronic controller including a control board 88 (see FIG. 1 ). Figure 2 ).

[0074] like Figure 4 , 4A , 4B, 4C and 4D, the rotor assembly 18 may include a rotor core 30. Figure 4 As shown, the rotor core 30 is generally annular. The rotor core 30 also includes a radially outward peripheral ring having an outer wall or surface 43 having a first or outer radius R1, and a radially inward outer peripheral surface or inner wall 68 defining a central opening 69 having a second or inner radius R2.

[0075] Alternatively, the inner wall may extend to the outer periphery 29 of the shaft 32 so that the shaft 32 can support the core 30. In another alternative, the inner wall 68 may be spaced apart from the shaft 32 by a central portion 21 that includes, for example, a sleeve 35 (shown in phantom) that engages the shaft 32 and a hub 37 that includes a plurality of arms or spokes (shown in phantom) that connect the sleeve 35 to the inner wall 68.

[0076] like Figure 4 As shown, the core 30 extends from the outer periphery 43 to the inner wall 68. The poles 19 are formed by the laminations 48 and are positioned in a spaced relationship in the core 30, forming a portion of the inner wall 68 and the outer periphery 43. The laminations or laminations 48 are positioned tangentially around the core 30 so that the magnetic flux lines 33 pass perpendicularly through the laminations or laminations 48.

[0077] The spaces between the poles define recesses 31 for receiving magnets 34. At least one of the plurality of recesses 31 comprises a minimum depth defined by the following equation:

[0078]

[0079] Here N is the number of rotor poles 19 .

[0080] An axial flux machine 10 may be provided in which each lamination 48 is in the form of a layer or lamination. Each lamination 48 includes opposing parallel outer flat surfaces 25. The laminations may have any suitable shape. For example, the laminations may extend circumferentially around the central portion 21 of the rotor core 30, and the core 30 may include a recess or axial aperture 31 formed in the laminations 48. For simplicity, and as shown in FIG. Figure 4 and 4 As shown in FIG. 2B , the laminations 48 may be composed of separate sections that are circumferentially spaced around the central portion 21 of the rotor core 30. Each section may form one pole or tooth 19 of the rotor core 30.

[0081] like Figure 4 As shown in FIG. 3 , the lamination 48 may be rectangular or trapezoidal and may form one of the poles or teeth 19, having first and second opposite sides 51 and 53, respectively perpendicular to the outer plane 25, and first and second opposite ends 55 and 56, respectively perpendicular to the outer plane 25. Note that when using Figure 4 and 4 In the case of the laminations 48 shown in C, axial openings 31 are formed in the spaces between adjacent laminations 48.

[0082] Magnet 34 is positioned against sides 51 and 53. First end 55 and second end 56 form first end face 40 and second end face 41 of the rotor outer surface, respectively. Outer flat surface 25 of at least one of laminations 48 is located on outer flat surface 25 of another lamination 48 to form first rotor pole 45. Additional laminations, for example 3 to 25 laminations, are positioned to form first rotor pole 45.

[0083] The outer plane 25 of at least one lamination 48 is positioned on the outer plane 25 of another lamination 48 to form a second rotor pole 47. Additional laminations, such as 3 to 25 laminations, may be positioned to form the second rotor pole 47. The first rotor pole 45 and the second rotor pole 47 are each spaced apart and secured to a bonding material 39 such as a molded polymer or resin.

[0084] like Figure 4 B and Figure 4 C, a mechanical interlock 49 may be formed in the laminations 48 and may be in the form of, for example, a protrusion 49A in one lamination that mates with a recess 49B in the other lamination. Such an interlock 49 is more fully described in U.S. Pat. No. 6,847,285 B2 assigned to the same entity as the present application, which is hereby incorporated by reference in its entirety.

[0085] like Figure 4 As shown, the rotor assembly 18 can include additional rotor poles 19 as shown, which are made of laminations 48 as described above. The first pole 45, the second pole 47 and the additional pole 19 can be positioned in a mold (not shown) of a molding machine (not shown), preferably in a circular pattern and evenly positioned around the periphery of the mold. The permanent magnet 34 can be positioned in the mold between adjacent poles 19. The sleeve 35 and the hub 37 (as well as the shaft 32) can also be placed in the mold. Next, the molding material can be injected into the mold to form the rotor assembly. It should be understood that the sleeve 35 and the hub 37 can be integrally formed by the molding material in the mold.

[0086] In the exemplary embodiment, rotor 30 includes a plurality of axial apertures 31. For example, first side 51 and second side 53 define a first axial aperture or recess 31 of the plurality of axial apertures or recesses 31. Each axial aperture 31 includes a depth d extending axially inwardly from rotor core periphery 43 to rotor core inner wall 68, and extends axially from rotor outer surface 40 through rotor 30 to an opposite second rotor outer surface or surface 41. Each axial aperture 31 may be configured to receive one or more permanent magnets 34, such that each magnet is axially embedded in rotor 30 and extends inwardly from rotor outer surface 43 to inner wall or surface 68. In the exemplary embodiment, permanent magnet 34 is a substantially rectangular hard ferrite magnet. However, magnet 34 may have any suitable shape and may be made of any suitable material that enables motor 10 to operate as described herein. For example, magnet 34 may be conical and / or made of bonded neodymium, sintered neodymium, and / or samarium cobalt.

[0087] In the exemplary embodiment, rotor 30 includes a plurality of rotor poles 19, each of which has an outer surface along rotor periphery 43 and extends radially inwardly toward inner wall 68. Figure 4 and Figure 5 1 and 2. Although shown as being generally rectangular, rotor poles 19 may have any suitable shape that enables motor 10 to operate as described herein. For example, rotor poles 19 may have a generally rectangular shape. In an exemplary embodiment, the number of axial apertures 31 is equal to the number of rotor poles 19, and one magnet 34 is located in each axial aperture 31 between a pair of rotor poles 19. Rotor 30 may have any number of rotor poles 19 that enables motor 10 to function as described herein, for example, six, eight, ten, or twelve poles.

[0088] In the exemplary embodiment, the design of rotor 30 utilizes lower cost magnets, although the power density and high efficiency of the machine are achieved using higher cost magnets such as neodymium magnets. In the exemplary embodiment, the increased efficiency and power density of electric machine 10 is achieved by increasing the magnetic flux generated by rotor 30. The increase in magnetic flux is facilitated by magnets 34 having a minimum depth d, which is

[0089] d is defined by the following equation:

[0090]

[0091] Where D min represents the minimum depth variable, R1 represents the outer radius of the rotor, R2 represents the inner radius of the rotor, and n represents the number of rotor poles. maxThe saturation of the stator iron sections (teeth and yoke) is determined by any axial length constraints on the motor 10 designed for a particular application. In the exemplary embodiment, when the magnets 34 have a min and D max When the depth is between D and , the rotor 30 helps to increase the magnetic flux generation, thereby obtaining the best efficiency and power density. In an exemplary embodiment, the rotor 30 can be min and D max The depth d can be variably selected to adjust the power output of the motor 10 while maintaining a constant rotor and stator outer diameter. For example, decreasing the depth d will reduce the motor power output, and increasing the depth d will increase the motor output. In this way, the motor 10 can be designed for a specific power output application without requiring additional machining costs to adjust the outer diameter of the rotor and / or stator.

[0092] Figure 4 3 is a front view of a rotor 30 that may be included in the motor 10. The rotor 30 generally includes a sleeve 35 for engaging with the shaft 32, and a hub 37 positioned between the sleeve 35 and the rotor poles 19. In an exemplary embodiment, the sleeve 35 is made of steel. However, the sleeve 35 may be formed of any suitable material that enables the rotor 30 to operate as described herein. Alternatively, the sleeve 35 may not be included, and the hub 37 is directly connected to the shaft 32. In an exemplary embodiment, the hub 37 is made of an injection molded polymer. However, the hub 37 may be formed of any suitable non-magnetic material that enables the rotor 30 to operate as described herein. For example, the hub 37 may be a non-magnetic material that is machined, extruded or die-cast, such as aluminum or zinc. Alternatively, the hub 37 is made of an isolation damping material that is configured to reduce the transmission of at least one of motor torque pulsation, motor torque fluctuation, and motor torque cogging.

[0093] In the exemplary embodiment and as Figure 4 B and 4C, the rotor pole 19 may also include a pole retaining structure 74 in the form of a protrusion and / or a recess, which cooperates with a mating magnet retaining structure 76 in the form of a recess and / or a protrusion formed in the magnet 34, so as to retain the magnet 34 in the axial aperture 31 by substantially preventing the movement of the magnet 34 in the radial direction. In addition, the rotor pole 19 and the magnet 34 may define a space 80 between each other. In an exemplary embodiment, the space 80 is configured to receive a bonding material 39, such as a retaining material, such as a molded polymer or resin. The bonding material 39 can replace or enhance the retaining structures 74 and 76.

[0094] The bonding or retaining material 39 is configured to at least partially fill the space 80 and cause interaction between the surface structures 74 and 76 to substantially resist or prevent movement of the magnet 34 within the axial aperture 31. The retaining material 39 can be any material or member that at least partially fills the space 80 and helps prevent radial movement and / or general lateral movement of the magnet 34. In addition, the retaining material 39, such as a non-magnetic polymer, can be injection molded into the area between the rotor poles 19 and the magnets 34 to facilitate retaining the magnets 34 within the axial aperture 31.

[0095] Refer to Figure 1 An air gap 38 is formed between the second outer end face or outer surface 41 of the rotor and the stator outer surface 42 , and the magnetic flux within the motor 10 extends between the permanent magnets 34 and the stator assembly 24 in a direction parallel to the axis 36 .

[0096] Now refer to Figure 5 and Figure 5A In yet another aspect, an axial flux electric machine 10 may be provided, wherein the rotor assembly 18 further comprises a magnetizable ring 58 located near the rotor first end surface 40 (opposite to the stator 23). The magnetizable ring 58 defines an outer periphery 59 and a central opening 60. The magnetizable ring 58 is made of a magnetizable material such as an iron material. The magnetizable ring 58 is used to guide the magnetic flux generated by the permanent magnets 34.

[0097] Now refer to Figure 5B In yet another aspect, an axial flux machine 10 may be provided wherein rotor assembly 18 includes rotor poles 19B forming recesses 31B wherein magnets 34B do not extend to second rotor end surface 40B. Resin 39B may be positioned in recesses 31B between magnets 34B and second rotor end surface 40B.

[0098] While the axial flux motor of the present invention may be provided with generally rectangular poles, other shapes are contemplated and may function similarly. The use of rectangular poles provides for simpler manufacturing and assembly. For rectangular or square poles, each lamination forming the pole may be identical to one another. The laminations may be stamped from a roll of material (e.g., steel). The laminations may be randomly assembled to form the poles, as each lamination may be identical to one another.

[0099] like Figure 6 , 6A As shown in FIGS. 6B , the motor 210 may be provided with a rotor assembly 218 having a magnetic pole 219 that is trapezoidal or pancake-shaped. In such a configuration, the motor 210 may include a rectangular magnet 234 that may be square. It should be understood that the magnet may also be trapezoidal or pancake-shaped, wherein if both the magnet and the magnetic pole are trapezoidal or pancake-shaped, the angle of the sector component is smaller.

[0100] The trapezoidal pole 219 includes laminations 248 of increasing length. Each lamination 248 in each pole 219 is composed of different lengths, and the laminations need to be assembled, and the length of each lamination increases gradually. The manufacturing cost of such a pole 219 may be higher.

[0101] The rotor assembly 218 may include a backing ring or disk 258 similar to Figure 4 The ring 58 of the rotor assembly 18 .

[0102] According to yet another aspect and now with reference to Figure 7 , an axial flux motor 310 may be provided wherein a rotor assembly 318 includes a magnetic pole 319 formed of a plurality of layers wound from a single iron sheet into an annular rotor core 330. The sheet has notches or recesses 331 formed in the sheet in a spaced-apart configuration. The sheet is wound in a circular form to form the rotor core 330. Magnets 334 are positioned in the recesses 331.

[0103] The rotor core 330 may be manufactured in a roll forming machine, such as the machine more fully described in US Pat. No. 7,654,123 B2, which is hereby incorporated by reference in its entirety.

[0104] Refer to Figure 2 and Figure 3 The stator assembly 24 may generally include a plurality of stator modules 84, a bobbin assembly 86, and a control board 88. The stator assembly 24 is coupled to a stator housing 90 (at Figure 2 ) to form an assembled stator 92. The stator assembly 24 may also include a plurality of tooth tips 94.

[0105] like Figure 2 and Figure 3 As shown, the stator assembly 24 is a multi-phase (more than one phase) axial flux stator, and preferably a three-phase axial flux stator, which generates magnetic flux in an axial direction (i.e., parallel to the rotation axis 36). The stator module 84 is generally C-shaped and includes a pair of teeth 96 connected by a yoke 98. In the exemplary embodiment, the stator module 84 is oriented in a generally axial direction so that the teeth 96 extend substantially parallel to the rotation axis 36. In addition, the stator module 84 is made of a plurality of stacked laminate sheets 100. This structure simplifies the manufacturing process and enables the modular stator modules 84 to be produced quickly and efficiently.

[0106] Figure 2 and Figure 3A perspective view of an exemplary spool assembly 86 that may be included in the motor 10 is shown. The spool assembly 86 generally includes a plurality of spools 114 coupled to the control board 88. Although twelve spools 114 are shown, the spool assembly 86 may include any number of spools to enable the motor 10 to function as described herein. Each spool 114 includes an opening 116 that closely conforms to the outer shape of the stator module teeth 96 and the tooth tip axial member 102. For example, the stator module teeth 96 are configured to be at least partially positioned within a first end 118 of the opening 116, and the tooth tip axial member 102 is configured to be at least partially positioned within a second end 120 of the opening 116. The motor 10 may include one spool 114 for each tooth 96, a spool 114 located on every other tooth 96, and / or one spool 114 located on the yoke 98.

[0107] Figure 3 1 is a perspective view of a bobbin 114 that may be included in the bobbin assembly 86. In the exemplary embodiment, the bobbin assembly 86 also includes an electrical winding 122 that includes a plurality of coils 124. In the exemplary embodiment, the winding 122 is composed of twelve coils 124 and forms a twelve-pole stator. Each coil 124 is wound around a corresponding bobbin 114 that electrically isolates the coil 124 from the stator module 84 and the tooth tip 94. Alternatively, each coil is wound directly around one of the stator module teeth 96 and the tooth tip axial member 102 in a generally vertical direction (i.e., generally parallel to the rotational axis 36), and / or is wound directly around the yoke 98 in a generally horizontal direction (i.e., generally perpendicular to the rotational axis 36).

[0108] In an exemplary embodiment, the coils 124 are wound around the bobbins 114, and each coil 124 includes two ends, namely the start and end of the coil. The bobbins 114 are connected to the control board 88 via pins 126. In an exemplary embodiment, the control board 88 is a printed circuit board (PCB), and each end of each coil 124 is connected to the control board 88 using insulation displacement terminals (not shown) designed to be directly soldered into the control board 88. Alternatively, any other suitable connector can be used, which enables multiple bobbins 114 to be connected to the control board 88. In an exemplary embodiment, the control board 88 includes a wiring connector 128 for connecting the control board 88 directly to the motor control board (not shown). In an alternative embodiment, the control board 88 is incorporated into the motor control board, thereby eliminating redundant installations and connectors.

[0109] The teeth 96 have substantially the same width w from the inner edge 97 to the outer edge 99. That is, the width w of the teeth 96 does not expand from the inner edge 97 to the outer edge 99 as in some known stators. This allows the laminate sheets 100 to be substantially the same, which reduces manufacturing costs. In addition, the stator modules 84 are separated from each other and oriented so that adjacent teeth 96 form alternating parallel gaps 101 and angular gaps 103. Alternatively, the stator modules 84 can be solid.

[0110] In the exemplary embodiment, the tooth tip 94 is generally T-shaped and includes an axial member 102 and a cross member 104. Each cross member 104 includes an inwardly extending portion 106, an outwardly extending portion 108, and a groove 110. In the exemplary embodiment, the tooth tip 94 is made of a plurality of stacked laminate sheets 105. This structure simplifies the manufacturing process and enables modular tooth tips 94 to be produced quickly and efficiently. In the exemplary embodiment, the outwardly extending portion 108 has a greater length than the inwardly extending portion 106. The tooth tip 94 also includes a rounded portion 112 to reduce noise by reducing the harmonic content of the back electromagnetic field (EMF) and the cogging torque. The tooth tip 94 is generally aligned with the corresponding tooth 96 and increases the magnetic flux density in the stator assembly 24 and reduces the length of the winding 122 required for the stator assembly 24.

[0111] According to an embodiment of the present invention, the rotor may be provided with permanent magnets made of a permanently magnetizable material that has been magnetized before the magnets are assembled into the rotor. When assembled into an assembly of such a rotor, the magnetized magnets have an affinity for magnetically attracted materials (e.g., ferrous materials). Typically, portions of the stator core (including the stator core) and portions of the rotor (including the rotor poles) are made of ferrous materials. In addition, the motor housing, motor bearings, and motor shaft are typically made of ferrous materials. The attraction of the magnets to these ferrous materials makes assembly very difficult.

[0112] The applicant has found that assembly of an electric machine, and in particular of an electric machine rotor, is easier if the electric machine rotor is implemented with non-magnetized rotor magnets. The applicant has found that magnets within an assembled electric machine rotor can actually be magnetized after the rotor is assembled if appropriate means for such magnetization are provided.

[0113] Now refer to Figure 8 A fixture or jig 400 is provided for providing such magnetization of a magnetizable material, the requirements of which are described above. The fixture 400 is capable of magnetizing any magnetizable permanent magnet, including, for example, ferrite magnets, bonded neodymium magnets, and sintered neodymium magnets. It should be understood that the fixture 400 can be designed, customized, or adjusted to optimally magnetize a specific magnet material of a specific shape.

[0114] For example, Figure 1-5For use with the rotor 30 shown, the fixture 400 may include a recess or cavity 402 for receiving the rotor 30. The fixture 400 is designed to permanently magnetize the magnet 34 after the magnet 34 has been assembled to the rotor 30. The recess 402 may include an inner periphery 204 for mating with the outer periphery 43 of the rotor 30. The recess 402 may also include a locating surface 406 for the received end face 41 of the rotor 30. The rotor 30 may include a central shaft 32, and the fixture 400 may include a central opening (not shown) for receiving the central shaft 32.

[0115] The fixture 400 includes a magnetizing coil 410 for generating an electromagnetic field when current is applied to the coil 410. Although the fixture 400 is capable of magnetizing the coil 410 when the coil 410 is merely located near the magnet 34, optimal placement of the coil 410 relative to the magnet 34 will provide more effective and thorough magnetization of the magnet 34.

[0116] Such magnetizing coils are powered by a power source such as 110 / 130V AC or 210 / 230V AC single phase power or by a three phase AC power source. Circuits for energizing such coils are well known.

[0117] like Figure 8 and Fig. 9 As shown, preferably, the coil 410 is placed against both the first end surface 40 of the rotor and the second end surface 41 of the rotor 30. Figure 8 and Fig. 9 As shown, fixture 410 includes a top magnetizing fixture 408 adjacent to first end face 40 of magnet 34 and a bottom magnetizing fixture 409 adjacent to second end face 41 of magnet 34. Fixtures 408 and 409 may be similar, and each fixture 408, 409 includes a coil 410 corresponding to each magnet 34, and these coils 410 are positioned to be directly aligned with magnet 34.

[0118] As shown, a separate coil 410 is placed against (or spaced apart from) each magnet 34. It should be understood that a spacer 412 can be positioned between the faces 40 and 41 of the magnet 34 and the coil 410. The spacer 412 can be used to protect the coil and magnet and to insulate the magnet from the coil. The spacer 412 can be simply an air gap between the magnet 34 and the coil 410.

[0119] Note that a separate coil 410 may be alternately placed on each of the end faces 40 and 41 of the magnet 34 , but doing so would limit the magnetic flux pattern that can be formed by the coil 410 .

[0120] The coils 410 , particularly when a separate coil 410 is placed adjacent each end face 40 , 41 of the magnet 34 , can produce an optimal permanent magnetic flux pattern for the motor rotor 30 .

[0121] Now refer to Fig.10 And according to another embodiment of the present invention, a method 500 is provided. The method 500 includes a step 510 of providing a stator and a step 512 of providing a rotor. The method 500 includes a step 514 of fixing the rotor to the stator rotatably around the center of rotation of the rotor. The method 500 also includes a step 516 of providing a magnetizable permanent magnet having a longitudinal axis thereof. The method 500 includes a step 518 of firmly fixing the magnet to the rotor, wherein the longitudinal axis is positioned in a radial direction relative to the center of rotation of the rotor, thereby defining a radially inward surface and an opposite radially outward surface, the magnet having a first end surface adjacent to a first outer end surface of the rotor and having a second end surface adjacent to a second outer end surface of the rotor. The method 500 also includes a step 520 of partially magnetizing the magnet by positioning a first magnetizing device adjacent to the first end surface of the magnet. The method 500 also includes a step 522 of further magnetizing the magnet by positioning a second magnetizing device adjacent to the second end surface of the magnet.

[0122] In another aspect of method 500, an axial flux rotor may be provided, wherein step 512 of providing a rotor includes the step of providing a body having an outer periphery defined by an outer radius OR. The body also has a central opening defined by an inner radius IR. The step of providing a body includes stamping a plurality of laminations. Each lamination in the plurality of laminations includes opposing parallel outer planes and opposing first and second ends. The step of providing a body also includes superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations.

[0123] The step of providing a body also includes repeating the above-mentioned stacking step to provide rotor poles. The step of providing a body also includes positioning the rotor poles in a spaced relationship, wherein the opposite first and second ends of the laminations are oriented tangentially relative to the center of rotation of the rotor. The opposite first and second ends define an outer radius OR and an inner radius IR, respectively.

[0124] In another aspect, an axial flux rotor may be provided wherein the step of providing a body further comprises overmolding the rotor poles with a moldable material after positioning the rotor poles in spaced relationship.

[0125] In yet another aspect of the method 500 , an axial flux rotor may be provided wherein the step 516 of providing a magnetizable permanent magnet includes providing one of a ferrite magnet, a bonded neodymium magnet, and a sintered neodymium magnet.

[0126] In yet another aspect of method 500, an axial flux rotor may be provided, wherein step 516 of providing a magnetizable permanent magnet further comprises the steps of providing a second magnetizable permanent magnet having a longitudinal axis thereof and the steps of securely securing the second magnetizable permanent magnet to the rotor, wherein the longitudinal axis is positioned in a radial direction relative to a center of rotation of the rotor, thereby defining a radially inward surface of the second magnet and an opposing radially outward surface of the second magnet. The second magnet may have a first end surface adjacent to a first outer end surface of the rotor, and may have a second end surface adjacent to a second outer end surface of the rotor.

[0127] In yet another aspect, an axial flux rotor may be provided, further comprising the steps of partially magnetizing the second magnet by positioning a first magnetizing device adjacent to a first end surface of the second magnet and further magnetizing the second magnet by positioning a second magnetizing device adjacent to a second end surface of the second magnet.

[0128] In yet another aspect of method 500 , an axial flux rotor may be provided, wherein step 516 of providing a magnetizable permanent magnet having its longitudinal axis includes providing a plurality of magnetizable permanent magnets, each permanent magnet of the plurality of magnetizable permanent magnets having its longitudinal axis.

[0129] In yet another aspect of method 500, an axial flux rotor may be provided, wherein step 518 of securely securing magnets to the rotor includes securely securing each of the plurality of magnetizable permanent magnets to the rotor, wherein a longitudinal axis of each of the plurality of magnetizable permanent magnets is positioned in a radial direction relative to a center of rotation of the rotor, thereby defining a radially inward surface and an opposing radially outward surface of each of the plurality of magnetizable permanent magnets. Each of the plurality of magnetizable permanent magnets may have a first end surface adjacent to a first outer end surface of the rotor, and may have a second end surface adjacent to a second outer end surface of the rotor.

[0130] In yet another aspect of method 500, an axial flux rotor may be provided wherein the step 520 of partially magnetizing the magnets includes positioning a first magnetizing device adjacent to a first end surface of each of the plurality of magnetizable permanent magnets, and wherein the step of further magnetizing the magnets includes positioning a second magnetizing device adjacent to a second end surface of each of the plurality of magnetizable permanent magnets.

[0131] In yet another aspect of method 500, an axial flux rotor may be provided, wherein step 516 of providing magnetizable permanent magnets includes providing axially embedded magnets having a minimum depth defined by the following equation,

[0132]

[0133] where BrS is the remanent flux density of the surface mounted magnet, where OR is the outer radius of the body, where IR is the inner radius of the body, where N is the number of rotor poles, and where BrA is the remanent flux density of the axially embedded magnet.

[0134] In yet another aspect of method 500 , an axial flux rotor may be provided wherein step 516 of providing a magnetizable permanent magnet includes providing a magnetizable ring / disk positioned adjacent one of opposing first and second end faces, the magnetizable ring defining an outer periphery and a central opening.

[0135] In yet another aspect of method 500 , an axial flux rotor may be provided, wherein step 512 of providing a rotor includes the step of providing a body having an outer periphery defined by an outer radius OR.

[0136] In yet another aspect of the method 500 , an axial flux rotor may be provided wherein the body further has a central opening defined by an inner radius IR.

[0137] In yet another aspect of method 500, an axial flux rotor may be provided, wherein the step of providing a body includes: providing a lamination of ferrous material; punching spaced apart openings in the lamination; and winding the lamination in a circular form to form a laminated rotor core while aligning some of the spaced apart openings to provide cavities for receiving magnets and providing rotor poles in a spaced apart relationship, wherein opposed parallel outer planes of the laminations are oriented tangentially relative to a center of rotation of the rotor. The outer planes define an outer radius OR and an inner radius IR.

[0138] Now refer to Fig.11 And according to another embodiment of the present invention, a method 600 is provided. The method 600 is used to manufacture an axial flux rotor. The method includes a step 610 of stamping a plurality of laminations and a step 612 of superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations. Each of the plurality of laminations includes opposing parallel outer planes and opposing first and second ends. The method also includes superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations. The method also includes a step 614 of repeating the above-mentioned superimposing steps to provide rotor poles and a step 616 of positioning the rotor poles in a spaced relationship around the center of rotation of the rotor, wherein the opposing first and second ends of the laminations are oriented tangentially relative to the center of rotation of the rotor.

[0139] In yet another aspect, the method may further include the steps of providing a plurality of magnetizable permanent magnets, each magnet having a longitudinal axis thereof, and positioning each magnet between adjacent rotor poles, wherein the longitudinal axis is positioned in a radial direction relative to a center of rotation of the rotor, thereby defining a radially inward surface and an opposing radially outward surface. The magnet has a first end surface adjacent to a first outer end surface of the rotor, and has a second end surface adjacent to a second outer end surface of the rotor.

[0140] In yet another aspect, the method may further include the step of overmolding the rotor poles with a moldable material after positioning the rotor poles in spaced-apart relationship.

[0141] In yet another aspect, the method may further include the steps of partially magnetizing the magnet by positioning a first magnetizing device near a first end face of the magnet, and further magnetizing the magnet by positioning a second magnetizing device near a second end face of the magnet.

[0142] In yet another aspect, the method may be provided wherein the step of providing a plurality of magnetizable permanent magnets includes providing one of ferrite magnets, bonded neodymium magnets, and sintered neodymium magnets.

[0143] In yet another aspect, method 600 may be provided wherein step 616 of positioning rotor poles in spaced relationship includes positioning each lamination of the plurality of laminations such that the laminations form a body having an outer periphery defined by an outer radius OR and a central opening defined by an inner radius IR.

[0144] In yet another aspect, the method may be provided wherein the step of providing a magnetizable permanent magnet comprises providing a magnet having a minimum length defined by the equation,

[0145]

[0146] where BrS is the remanent flux density of the surface mounted magnet, where OR is the outer radius of the body, where IR is the inner radius of the body, where N is the number of rotor poles, and where BrA is the remanent flux density of the axially embedded magnet.

[0147] In yet another aspect, the method may further include the step of providing a magnetizable ring / disk positioned adjacent one of the opposing first and second end faces. The magnetizable ring defines an outer periphery and a central opening.

[0148] Now refer to Fig. 12A and 12B, and according to another embodiment of the present invention, a process 700 is provided. The process 700 is used to prepare an axial flux motor. The process 700 includes a step 710 of stamping a plurality of laminations and a step 712 of superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations. Each lamination in the plurality of laminations includes opposite parallel outer planes and opposite first and second ends. The process 700 also includes a step 714 of repeating the above-mentioned superposition step to provide a first rotor pole and a step 716 of repeating the above-mentioned step to provide at least one additional rotor pole, thereby providing a plurality of rotor poles. The process 700 also includes a step 718 of positioning the plurality of rotor poles in a spaced-apart relationship around the center of rotation of the rotor, wherein the opposite first and second ends of the laminations are oriented tangentially relative to the center of rotation of the rotor; and a step 720 of providing a plurality of magnetizable permanent magnets, each magnet having its longitudinal axis. The process 700 further includes a step 722 of positioning each of the magnets between adjacent rotor poles, wherein the longitudinal axis is positioned in a radial direction relative to the center of rotation of the rotor, thereby defining a radially inward surface and an opposing radially outward surface, the magnet having a first end surface adjacent to the first outer end surface of the rotor and having a second end surface adjacent to the second outer end surface of the rotor. The process 700 further includes a step 724 of overmolding the rotor poles with a moldable material after positioning each of the magnets between adjacent rotor poles.

[0149] In yet another aspect, a process 700 may be provided wherein the step 718 of positioning the rotor poles in spaced apart relationship includes providing positioning the rotor poles in spaced apart relationship to form a body having an outer periphery defined by an outer radius OR and a central opening defined by an inner radius IR, and wherein the step of providing a plurality of magnetizable permanent magnets includes providing a plurality of magnetizable permanent magnets, each magnet having a minimum length defined by the following equation,

[0150]

[0151] where BrS is the remanent flux density of the surface mounted magnet, where OR is the outer radius of the body, where IR is the inner radius of the body, where N is the number of rotor poles, and where BrA is the remanent flux density of the axially embedded magnet.

[0152] In yet another aspect, the process may further include the step of providing a magnetizable ring / disk positioned adjacent one of the opposing first and second end faces. The magnetizable ring defines an outer periphery and a central opening.

[0153] Exemplary methods and systems for an axial flux electric machine are described herein. The axial flux electric machine includes a rotor having axially embedded permanent magnets. The axially embedded rotor design enables the use of lower cost ferrite magnets while achieving the power density and higher efficiency of other rotor designs using higher cost neodymium magnets. In addition, the use of a permanent magnet fixture with the coils to permanently magnetize the assembled rotor makes it easier to assemble non-magnetized magnets into the rotor assembly.

[0154] In addition, an axial flux machine includes a multiphase stator having substantially similar stator modules and substantially similar tooth tips made from economical laminations, which enables modular construction. The stator module teeth are substantially similar and have substantially the same width, so that the manufacturing process is simplified and accelerated, and no cogging torque is generated. The tooth tips increase flux concentration and reduce noise. Thus, a lower cost axial flux machine is described herein that provides faster production with minimal impact on efficiency and performance.

[0155] Exemplary embodiments of axial flux motor assemblies are described above in detail. The motor and its components are not limited to the specific embodiments described herein, and rather, the components of the system can be used independently and separately from other components described herein. For example, the components can also be used in combination with other machine systems, methods, and apparatuses, and are not limited to practice with only the systems and apparatuses as described herein. Instead, the exemplary embodiments can be implemented and utilized in conjunction with many other applications.

[0156] Although the specific features of various embodiments of the present invention may be shown in some drawings and not in other drawings, this is only for convenience. According to the principles of the present invention, any feature of the drawings may be combined with any feature of any other drawings to discuss and / or claim rights.

[0157] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any incorporated method. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. If such other examples do not differ from the structural elements described in the literal language of the claims, or include equivalent structural elements that are not substantially different from the literal language of the claims, such other examples are deemed to be included in the scope of protection of the claims.

Claims

1. A method for manufacturing an axial flux motor, the method comprising: Provide a stator; Providing a rotor, the rotor having a first outer end surface and a second outer end surface opposite to and parallel to the first outer end surface; fixing the rotor to the stator so as to be rotatable about a rotor rotation center; providing a magnetizable permanent magnet having its longitudinal axis; securely securing the magnetizable permanent magnet to the rotor, wherein the longitudinal axis is positioned in a radial direction relative to a center of rotation of the rotor so as to define a radially inwardly facing surface and an opposing radially outwardly facing surface, the magnetizable permanent magnet having a first end surface adjacent to the first outer end surface of the rotor and having a second end surface adjacent to the second outer end surface of the rotor; partially magnetizing the magnetizable permanent magnet by positioning a first magnetizing device adjacent to the first end face of the magnetizable permanent magnet; and The magnetizable permanent magnet is further magnetized by positioning a second magnetizing device adjacent to the second end surface of the magnetizable permanent magnet.

2. The method according to claim 1, wherein: The step of providing a rotor comprises the step of providing a body having an outer periphery defined by an outer radius OR, the body also having a central opening defined by an inner radius IR, the step of providing a body comprising: stamping a plurality of laminations, each lamination of the plurality of laminations comprising opposed parallel exterior planar surfaces and opposed first and second ends; superimposing one of the outer planes of one of the plurality of laminations on one of the outer planes of another of the plurality of laminations; Repeating the above stacking steps to provide rotor poles; and The rotor poles are positioned in a spaced relationship with opposing first and second ends of the laminations oriented tangentially relative to the rotor center of rotation, the opposing first and second ends defining the outer radius OR and the inner radius IR, respectively.

3. The method according to claim 2, wherein: The step of providing a body further includes overmolding the rotor poles with a moldable material after positioning the rotor poles in spaced apart relationship.

4. The method according to claim 1, wherein: The step of providing a magnetizable permanent magnet includes providing one of a ferrite magnet, a bonded neodymium magnet, and a sintered neodymium magnet.

5. The method according to claim 1: Also included is the step of providing a second magnetizable permanent magnet having a longitudinal axis thereof; fixedly securing the second magnetizable permanent magnet to the rotor, wherein the longitudinal axis is positioned in a radial direction relative to a center of rotation of the rotor to define a radially inwardly facing surface of a second magnet and an opposing radially outwardly facing surface of a second magnet, the second magnet having a first end surface adjacent to a first outer end surface of the rotor and having a second end surface adjacent to a second outer end surface of the rotor; partially magnetizing the second magnet by positioning the first magnetizing device adjacent to a first end surface of the second magnet; and The second magnet is further magnetized by positioning the second magnetizing device adjacent to a second end surface of the second magnet.

6. The method according to claim 1, wherein: The step of providing a magnetizable permanent magnet having its longitudinal axis includes providing a plurality of magnetizable permanent magnets, each magnetizable permanent magnet of the plurality of magnetizable permanent magnets having its longitudinal axis; The step of fixedly securing the magnetizable permanent magnets to the rotor includes fixedly securing each of the plurality of magnetizable permanent magnets to the rotor, wherein a longitudinal axis of each of the plurality of magnetizable permanent magnets is positioned in a radial direction relative to a center of rotation of the rotor so as to define a radially inward surface and an opposing radially outward surface of each of the plurality of magnetizable permanent magnets, each of the plurality of magnetizable permanent magnets having a first end surface adjacent to a first outer end surface of the rotor and having a second end surface adjacent to a second outer end surface of the rotor; The step of partially magnetizing the magnetizable permanent magnets includes positioning the first magnetizing device adjacent to a first end surface of each of the plurality of magnetizable permanent magnets; and The step of further magnetizing the magnetizable permanent magnets includes positioning the second magnetizing device adjacent to a second end surface of each of the plurality of magnetizable permanent magnets.

7. The method according to claim 6, wherein: The step of providing a magnetizable permanent magnet includes providing a body having an outer periphery defined by an outer radius and providing a body having a radius defined by the equation Defined as the minimum depth of an axially embedded magnet, where BrS is the remanent flux density of the surface mount magnet, where OR is the outer radius of the body, where IR is the inner radius of the body, where N is the number of rotor poles, and where BrA is the remanent flux density of the axially embedded magnet.

8. The method according to claim 1, wherein: The step of providing a magnetizable permanent magnet includes providing a magnetizable ring positioned proximate one of the opposing first and second end faces, the magnetizable ring defining an outer periphery and a central opening.

9. The method according to claim 1, wherein: The step of providing a rotor comprises the step of providing a body having an outer periphery defined by an outer radius OR, the body also having a central opening defined by an inner radius IR, the step of providing a body comprising: Provide iron material plates; punching spaced-apart openings in the sheet; and The laminations are wound in a circular form to form a laminated rotor core comprising a plurality of laminations while aligning some of the spaced apart openings to provide cavities for receiving the magnetizable permanent magnets and to provide rotor poles in a spaced apart relationship, wherein opposed parallel outer planes of the laminations are oriented tangentially with respect to a center of rotation of the rotor, the outer planes defining an outer radius OR and an inner radius IR.

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