Electric rotational machine

Abstract

An electric machine includes a rotor configured to rotate on an axis and a stator spaced radially from the rotor. The stator includes a plurality of stator phases arrayed along the axis, each stator phase including a pair of flux rings and a coil extending about the axis and disposed between the pair of flux rings. Axial returns extend between the pair of flux rings. A barrier spaces laminas of the flux ring from laminas of the axial return.

Description

[0001] ELECTRIC ROTATIONAL MACHINE

[0002] CROSS-REFERENCE TO RELATED APPLICATION(S)

[0003] This application claims priority to U.S. Provisional Application No. 63 / 671,341 filed July 15, 2024 and entitled “ELECTRIC ROTATIONAL MACHINE,” the disclosure of which is hereby incorporated by reference in its entirety.

[0004] BACKGROUND

[0005] The present disclosure relates generally to electric machines. More specifically, the present disclosure relates to motors and / or generators, such as transverse flux motors and / or generators.

[0006] Electric motors utilize electricity to generate a mechanical output. Some electric motors generate rotational outputs. In alternating current (A / C) induction motors, a stator is electrically energized to electromagnetically drive rotation of a rotor about a rotational axis. The stator includes laminates and windings. The rotor includes permanent magnets that are acted on by the electromagnetic field induced by current through the stator to cause rotation of the rotor. Such electric motors include coils that extend axially relative to the rotational axis and that extend axially beyond the ends of the rotor to wrap around and form the ends of the coil windings.

[0007] SUMMARY

[0008] According to an aspect of the disclosure, an electric rotational machine includes a rotor rotatable on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; and a stator configured to electromagnetically drive rotation of the rotor, the stator including a plurality of phases. Each phase of the plurality of phases includes at least one coil wound around the axis such that the axis extends through the at least one coil; a first flux ring including a first plurality of teeth extending around the axis such that the axis extends through the first flux ring, wherein the first flux ring is formed by a first plurality of tooth laminas; a second flux ring including a second plurality of teeth extending about the axis such that the axis extends through the second flux ring, wherein the second flux ring is formed by a second plurality of tooth laminas; a plurality of axial returns arrayed about the axis, the plurality of axial returns extending between the first flux ring and the second flux ring, wherein each axial return of the plurality of axial returns is formed by a plurality of return laminas; and at least one spacer forming a gap directly radially between the first flux ring and a first axial return of the plurality of axial returns. According to an additional or alternative aspect of the disclosure, an electric rotational machine includes a rotor rotatable on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; and a stator configured to electromagnetically drive rotation of the rotor, the stator including a plurality of phases. Each phase of the plurality of phases includes at least one coil wound around the axis such that the axis extends through the at least one coil; a first flux ring including a first plurality of teeth extending around the axis such that the axis extends through the first flux ring, wherein the first flux ring is formed by a first plurality of tooth laminas; a second flux ring including a second plurality of teeth extending about the axis such that the axis extends through the second flux ring, wherein the second flux ring is formed by a second plurality of tooth laminas; a plurality of axial returns arrayed about the axis, the plurality of axial returns extending between the first flux ring and the second flux ring, wherein each axial return of the plurality of axial returns is formed by a plurality of return laminas; a first spacer forming a first gap directly radially between the first flux ring and a first axial return of the plurality of axial returns; and a second spacer forming a second gap directly radially between the second flux ring and the first axial return.

[0009] According to another additional or alternative aspect of the disclosure, an electric rotational machine includes a rotor rotatable on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; and a stator configured to electromagnetically drive rotation of the rotor, the stator including a plurality of phases. Each phase of the plurality of phases includes at least one coil wound around the axis such that the axis extends through the at least one coil; a first flux ring including a first plurality of teeth extending around the axis such that the axis extends through the first flux ring, wherein the first flux ring is formed by a first plurality of tooth laminas; a second flux ring including a second plurality of teeth extending about the axis such that the axis extends through the second flux ring, wherein the second flux ring is formed by a second plurality of tooth laminas; a plurality of axial returns arrayed about the axis, the plurality of axial returns extending between the first flux ring and the second flux ring, wherein each axial return of the plurality of axial returns is formed by a plurality of return laminas; a first transverse lamina interface formed directly radially between the first plurality of tooth laminas and the plurality of return laminas of a first axial return of the plurality of axial returns; a second transverse lamina interface formed directly radially between the second plurality of tooth laminas and the plurality of return laminas of the first axial return; and at least one spacer maintaining a first gap between the first plurality of tooth laminas and the plurality of return laminas of the first axial return at the first transverse lamina interface and the at least one spacer maintaining a second gap between the second plurality of tooth laminas and the plurality of return laminas of the first axial return at the second transverse lamina interface.

[0010] According to yet another additional or alternative aspect of the disclosure, an electric rotational machine includes a rotor that rotates on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; a stator comprising a plurality of phases. Each phase of the plurality of phases includes at least one coil wound around the axis such that the axis extends through the at least one coil; a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the phase located between the pair of circular arrays of teeth such that electrical energy delivered through the coil electromagnetically polarizes the teeth of the pair of circular arrays of teeth, each tooth formed from tooth laminations orientated radially with respect to the axis; a plurality of axial returns arrayed around the axis that connect a plurality of flux paths between the pair of circular arrays of teeth, the plurality of flux paths extending axially across the at least one coil, the axial returns formed from return laminas oriented axially with respect to the axis; and a plurality of transverse lamination interfaces comprising a plurality of spacers respectively maintaining a plurality of gaps, each transverse lamination interface of the plurality of transverse lamination interfaces comprising a respective gap of the plurality of gaps between the tooth laminas and the return laminas in which the tooth laminas are orientated transverse to the return laminas, the respective gap inhibiting eddy currents conduction between the tooth laminas and the axial return laminas.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a block diagram of an electric machine.

[0013] FIG. 2 is a block diagram of an electric machine.

[0014] FIG. 3 is an isometric view of a fan system.

[0015] FIG. 4A is an isometric view of an electric machine with a housing removed.

[0016] FIG. 4B is a partially exploded isometric view of the electric machine shown in FIG. 4A.

[0017] FIGS. 5A and 5B are isometric cross-sectional views of a portion of a stator phase that demonstrate how flux circuits are formed through flux paired teeth of a stator phase. FIG. 5C shows a detailed view of flux paired teeth of a stator phase interacting with concentrators and permanent magnets of a magnet phase of a rotor.

[0018] FIG. 6 is an isometric view of a portion of a stator phase.

[0019] FIG. 7 is a schematic view showing a transverse lamination interface between return laminas and tooth laminas.

[0020] FIG. 8 is a cross-sectional view of a portion of a stator phase.

[0021] FIG. 9 is a cross-sectional view of a portion of a stator phase.

[0022] FIG. 10 is a cross-sectional view of a portion of a stator phase.

[0023] FIG. 11 is a cross-sectional view of a portion of a stator phase.

[0024] FIG. 12A is a cross-sectional view of a portion of a stator phase.

[0025] FIG. 12B is an enlarged view of detail B in FIG. 12A.

[0026] FIG. 13A is a cross-sectional view of a portion of a stator phase.

[0027] FIG. 13B is an enlarged view of detail B in FIG. 13A.

[0028] FIG. 14 is an isometric view illustrating a configuration of standoff projections.

[0029] FIG. 15 is an isometric view showing a portion of a ring segment of a flux ring.

[0030] DETAILED DESCRIPTION

[0031] The present disclosure concerns electric rotational machines. Such electric rotational machines include motors and / or generators. While a motor will generally be referenced herein as the main example, any or all aspects referenced and / or shown herein can be implemented in a hybrid motor-generator or simply a generator.

[0032] The main type of electric machine presented herein is a transverse flux machine, which is distinguished from axial or radial flux type electric motors. However, the inventive aspects discussed herein can be applied to various types of electric machines beyond just transverse flux machines.

[0033] The electric machines of this disclosure include a rotor rotatable about a rotational axis and relative to a stator. The stator extends about the axis of rotation and can be around or within the rotor. The stator can be configured to electromagnetically drive rotation of the rotor.

[0034] According to aspects of the disclosure, the stator of the transverse flux electric motor includes stator phases, such as one, two, three, or more, formed from flux rings and a coil disposed axially between opposing flux rings. The flux rings include teeth that extend radially relative to the rotational axis and towards the rotor. The opposing flux rings of a single stator phase can be joined by axial returns contacting each flux ring and disposed on an opposite radial side of the coil from the rotor. The axial returns can form the radial-most portion of the laminate structures of the phases (e.g., radially inward for an outer rotating machine and radially outward for an inner rotating machine).

[0035] The rotor includes permanent magnets and can include concentrators interspersed between the permanent magnets. The interspersed concentrators and permanent magnets form a magnet array of the rotor. The permanent magnet array formed by the interspersed permanent magnets and concentrators can be formed in axially-arrayed magnet phases.

[0036] According to aspects of the present disclosure, the stator of an electric rotational machine can include axial returns formed from return laminas and teeth that are at least partially formed from tooth laminas. Multiple of the return laminas are stacked together to form the axial returns. Multiple of the tooth laminas are stacked together to form the teeth. The return laminas are oriented transverse to the tooth laminas. The return laminas can bridge over a coil to connect a first set of tooth laminas, forming a first flux ring, and a second set of tooth laminas, forming a second flux ring. The axial return facilitates transmission of magnetic flux between the tooth lamina sets. Laminas, which can also be referred to as laminations, can be formed from material which is readily susceptible to polarization from the electromagnetic fields generated by coils. Such material is typically ferromagnetic. The ferromagnetic materials can be metal such as iron or an alloy of iron, such as steel.

[0037] Transverse lamination interfaces are formed at the interfaces between return laminas and tooth laminas. A single axial return can define a pair of transverse lamination interfaces, with a first transverse lamination interface between a first flux ring and the axial return and a second transverse lamination interface between a second flux ring and the axial return. The return laminas are oriented transverse to the tooth laminas at each transverse lamination interface. The return laminas can be oriented orthogonal to the tooth laminas at each transverse lamination interface.

[0038] Electric rotational machines according to the disclosure include at least one spacer that forms a gap between the return laminas and the tooth laminas at the transverse lamination interface. The spacer forms a physical gap between the return laminas and the tooth laminas. Spacing the return laminas away from the tooth laminas inhibits the generation of eddy currents, providing for more efficient operation of the electric machine. The spacer can include one or multiple spacers for each transverse lamination interface. The spacer can be disposed directly radially between the return laminas and the tooth laminas at the transverse lamination interface. The spacer can be formed by one or both of the return laminas and tooth laminas or can be formed separately from the return laminas and tooth laminas.

[0039] According to aspects of the disclosure, the spacer forming the gap at the transverse lamination interface can be disposed directly radially between the return laminas and the tooth laminas. In some examples, the spacer can be formed as a spacing layer applied to one or both of the return laminas and the tooth laminas. In some examples, the spacing layer can be or include an adhesive layer, such that the spacing layer can be directly adhered to the tooth laminas and / or the return laminas. The spacing layer can, in some examples, fully encapsulate a set of laminas. For example, the spacing layer can encapsulate the axial return.

[0040] According to aspects of the disclosure, the spacer forming the gap at the transverse lamination interface can be formed as a spacing layer in which at least a portion, up to all, of the spacing layer does not radially overlap with the tooth laminas. In some examples, the spacing layer can be disposed on the coil located between the tooth laminas of the pair of flux rings of the stator phase. The spacing layer can be disposed directly radially between the return laminas and the coil.

[0041] According to aspects of the disclosure, the spacer forming the gap at the transverse lamination interface can be formed as a spacer strip that is disposed between the return laminas and the tooth laminas. The spacer strip can be elongate. The spacer strip can extend transverse to one or both of the return laminas and the tooth laminas. The spacer strip can extend parallel to one or the other of the return laminas and the tooth laminas. The spacer strip can extend orthogonal to one or the other of the return laminas and the tooth laminas. The spacer strip can be at least partially disposed in a trench. The trench can include a depression formed in the tooth laminas. In additional or alternative examples, the trench can include a depression formed in the return laminas.

[0042] According to aspects of the disclosure, the spacer strip can be formed as a continuous line of material. According to other aspects of the disclosure, the spacer strip can be formed as a discontinuous line of material in which the spacer strip includes multiple discrete parts. The discrete parts of the spacer strip can be aligned with each other, such as in a direction parallel to one or the other of the return laminas and the tooth laminas. According to aspects of the disclosure, the spacer forming the gap at the transverse lamination interface can be formed as a standoff projection. The standoff projection is formed by a subset of the return laminas at the transverse lamination interface and / or by a subset of the tooth laminas at the transverse lamination interface. The standoff projection is configured to extend across the gap at the transverses lamination interface to interface with the opposed lamina structure and form the gap. The laminations forming the standoff projection can extend further radially than others of the laminations forming the standoff projection.

[0043] According to some aspects of the disclosure, the subset of laminas forming the standoff projection includes one or more laminations. In examples in which the standoff projection is formed by multiple laminations, the multiple laminations can be disposed directly adjacent to each other.

[0044] According to aspects of the disclosure, the standoff projection can be formed as a contiguous projection. The contiguous standoff projection can form a single line that is disposed between the return laminas and the tooth laminas. It is understood that the standoff projection can form a contiguous line in examples in which the standoff projection is formed from multiple laminas. For example, the standoff projection can be formed by a series of protuberances each formed on a return lamina. The protuberances can be stacked adjacent to each other to form the contiguous standoff projection.

[0045] According to aspects of the disclosure, the standoff projection can be formed as a discontinuous projection. The discontinuous standoff projection can be formed as a series of lines that are spaced apart from each other. For example, the standoff projection can be formed as a series of protuberances that are spaced from each other. The series of protuberances can, in some examples, be formed on a single lamina. For example, the standoff projection can be formed by multiple protuberances from a single tooth lamina. The series of protuberances can, in some examples, be formed by multiple laminations. For examples, the standoff projection can be formed by multiple protuberances that are formed in separate laminas and that are aligned to form the standoff projection.

[0046] This disclosure uses multiple examples to demonstrate various inventive aspects. The inventive scope of this disclosure is not necessarily limited to any one of these embodiments, nor to all of them in just the manner shown and / or described. Rather, the inventive aspects demonstrated herein can be implemented in various other containers. One aspect or feature shown or described from one embodiment could be implemented on another embodiment in this disclosure even if not shown or described for that embodiment, or various embodiments not illustrated herein. The embodiments illustrated and / or discussed are intended to be illustrative and not limiting, and the described and / or illustrated features can be mixed and matched between different embodiments but including and excluding various features amongst the embodiments.

[0047] Components with common reference numbers can be structurally and functionally equivalent unless specifically shown and / or described to be different.

[0048] Several of the figures of the disclosure show a common axis, which is sometimes referred to as a rotational axis. An axis of rotation of the rotor is disposed coaxially with the common axis. The term annular is used herein, which can refer to a ring shape (continuous or broken) about the common axis, which can be coaxial with the common axis. The term radial is used herein which when referring to a direction is any direction orthogonal to the common axis, unless otherwise noted. The term axial is used herein which when referring to a direction is any direction parallel with the common axis, unless otherwise noted. The terms circumferential or circumferentially as used herein means around the common axis, unless otherwise noted.

[0049] Components can be considered to radially overlap when those components are disposed at common axial locations along an axis. A radial line extending from the axis will extend through each of the radially overlapping components. Components can be considered to axially overlap when those components are disposed at common radial and circumferential locations relative to an axis such that an axial line parallel to the axis extends through the axially overlapping components. Components can be considered to circumferentially overlap when aligned about the axis, such that a circle centered on the axis passes through the circumferentially overlapping components. Components can be considered to tangentially overlap when aligned about the axis such that a tangent line on a circle centered on the axis passes through each of the tangentially overlapping components.

[0050] FIG. 1 is a block diagram of electric machine 10. FIG. 2 is a block diagram of electric machine 10. FIG. 1 shows electric machine 10 in an outer rotator configuration in which the rotor 12 is spaced radially outward from the stator 14. FIG. 2 shows electric machine 10 in an inner rotator configuration in which the rotor 12 is spaced radially inward from the stator 14. FIGS. 1 and 2 are discussed together.

[0051] Electric machine 10 includes rotor 12, stator 14, and motor controller 16. Rotor 12 includes rotor body 18 and permanent magnet array 20. Stator 14 includes stator phases 22a, 22b, 22c (collectively herein “stator phase 22” or “stator phases 22”). While stator 14 is shown as a three-phase stator in the example shown, it is understood that stator 14 can be of any desired configuration regarding phase count, such as two, three, four, six, or more phases. Stator phase 22a includes flux rings 24a, 24b, coil 26, and axial returns 28. Stator phase 22b includes flux rings 24c, 24d, coil 26, and axial returns 28. Stator phase 22c includes flux rings 24e, 24f, coil 26, and axial returns 28. Flux rings 24a-24f are referred to collectively herein as “flux rings 24” or “flux ring 24.” Each flux ring 24 can be considered to form a half phase of a stator phase 22. Each flux ring 24 includes an annular array of teeth that extend about the axis CA.

[0052] Rotor 12 is spaced radially from stator 14 such that air gap 30 is formed between rotor 12 and stator 14. Electric machine 10 extends along axis CA and rotor 12 is configured to rotate on axis CA. Axis CA can be considered to be an axis of rotation of the rotor 12. Rotor 12 is configured to rotate on motor axis MA. In the example shown, the motor axis MA and common axis CA are disposed coaxially.

[0053] In the example shown in FIG. 1, rotor 12 surrounds stator 14 such that electric machine 10 is an outer rotator. In the example shown in FIG. 2, electric machine 10 includes stator 14 extending about rotor 12 such that electric machine 10 is an inner rotator.

[0054] Permanent magnet array 20 is supported by the rotor body 18. Permanent magnet array 20 is disposed across air gap 30 from stator 14 such that permanent magnet array 20 is spaced radially from stator 14. Permanent magnet array 20 includes a plurality of permanent magnets disposed annularly about motor axis MA. Permanent magnet array 20 can further include a plurality of concentrators, as discussed in more detail below. It is understood that in various examples the rotor body 18 can be formed by flux directing material of the rotor 12 (e.g., by laminas forming the concentrators among other options). In various other examples, the rotor body 18 can be formed separate from such flux directing structure and the permanent magnet array 20 can be mounted on that rotor body 18.

[0055] Stator 14 is formed by stator phases 22 arrayed along the axis CA. Each stator phase 22 includes paired flux rings 24 that are disposed on opposite axial sides of a coil 26 of that stator phase 22. The coil 26 is disposed directly axially between the flux rings 24 of the same stator phase 22. Flux rings 24a, 24b are paired to form stator phase 22a and are disposed on opposite axial sides of the coil 26 of stator phase 22a. Flux rings 24c, 24d are paired to form stator phase 22b and are disposed on opposite axial sides of the coil 26 of stator phase 22b. Flux rings 24e, 24f are paired to form stator phase 22c and are disposed on opposite axial sides of the coil 26 of stator phase 22c. In some examples, portions of each flux ring 24 can extend axially over the coil 26. As such, portions of each flux ring 24 can be disposed directly radially between the coil 26 and rotor 12. Flux rings 24 are formed by laminations and can include powdered metal components, though not all examples are so limited.

[0056] Laminations can be formed from material which is readily susceptible to polarization from the electromagnetic fields generated by coils 26. Such material is typically ferromagnetic. The ferromagnetic materials can be metal such as iron or an alloy of iron, such as steel. More specifically, laminations can be formed from silicon steel, among other options. Ferromagnetic material can be a ceramic that is doped or otherwise embedded with ferromagnetic elements. The laminations can be stacked together to form lamination stacks. Laminations can also be referred to as laminas.

[0057] In the example show, each stator phase 22 includes axial returns 28 that are disposed on an opposite radial side of coil 26 from permanent magnet array 20. Axial returns 28 extend between and connect paired ones of the flux rings 24 in each stator phase assembly 22. Axial returns 28 electromagnetically connect the paired flux rings 24. Axial returns 28 can be formed by stacked laminations having an axially oriented lamination grain (e.g., parallel with the motor axis MA). The laminations forming the axial returns 28 can be stacked circumferentially along a width of the axial return and extend axially along a length of the axial return 28.

[0058] Each coil 26 is a winding, typically copper, around the motor axis MA. Thus, each coil 26 could be a continuous winding of multiple loops (e.g., 2, 3, 4, 5, 10, 15, 20, 40, 50, 100, or more) around the motor axis MA. Examples of the winding can be formed by round wire or ribbon strand.

[0059] Controller 16 is operably connected to electric machine 10, electrically or communicatively, to control operation of electric machine 10, thereby controlling the rotational output of electric machine 10. Controller 16 can be of any desired configuration for controlling operation of electric machine 10 and can include control circuitry (e.g., one or more of a processor, a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a graphics processing unit (GPU), a system-on-module (SOM), or other equivalent discrete or integrated logic circuitry) and computer-readable memory.

[0060] Controller 16 is configured to store executable code, implement functionality, and / or process instructions. Controller 16 is configured to perform any of the functions discussed herein, including controlling operation of any components referenced herein. Controller 16 can be of any suitable configuration for controlling operation of electric machine 10, gathering data, processing data, etc. Controller 16 can include hardware, firmware, and / or stored software. Controller 16 can be of any type suitable for operating in accordance with the techniques described herein. While controller 16 is illustrated as a single unit, it is understood that controller 16 can be entirely or partially mounted on one or more circuit boards. In some examples, controller 16 can be implemented as a plurality of discrete circuitry subassemblies.

[0061] During operation, an alternating current (A / C) signal is run through each coil 26. The A / C signal rapidly builds and collapses the magnetic field due to the current reversal of the A / C signal through the coil 26. Flux concentrating material of each stator phase assembly 22 (e.g., the lamina stacks) is wrapped around at least three sides of the coil 26. Generally, magnetic flux flows with the grain, along the direction of lamination, as flux will generally follow the path of highest permeability and there is resistance to flux jumping from one layer of lamination to another layer of lamination (e.g., radially within the tooth laminas forming flux rings 24 and axially within the return laminas forming axial returns 28). At least a portion of the lamination grain of the flux rings 24 can be radially orientated relative to axis CA while the lamination grain of the axial returns 28 can be axially oriented relative to axis CA. As such, the flux can flow axially through the axial returns 28 and radially through flux rings 24 in a U-shaped path about coil 26 and towards rotor 12.

[0062] The A / C signal routed through the coil 26 is synchronized to develop magnetic fields through the flux rings 24 in time with the rotational position of permanent magnet array 20 to drive rotation of rotor 12. The respective A / C signals (e.g., sinusoidal or trapezoidal) delivered through the coils 26 in each stator phase 22a, 22b, 22c are out of phase with respect to each other. In this way, the magnets of the permanent magnet array 20 more frequently have flux peaks acting on them, as compared to synchronizing the sinusoidal A / C signals, thereby providing a smoother torque profile acting on the rotor 12 along the axis CA.

[0063] The examples of the electric machine 10 discussed in FIGS. 1 and 2 have three stator phases 22 (corresponding to the three stator phases 22a, 22b, 22c) and respective coils 26 therein. As such, three A / C signals are delivered through the coils 26 120-degrees electrically offset. In some examples, pairs of the phases (e.g., three phase pairs in a six phase example) can be provided with electrically aligned signals such that the electric signals are electrically offset between phase pairs but electrically aligned within a phase pair (e.g., three phase pairs for a six phase example). FIG. 3 is an isometric view of fan system 32. Fan system 32 includes an electric machine 10, which is configured as a motor in this example, and blade assembly 34. Motor housing 36, supports 38, and drive shaft 40 of electric machine 10 are shown. Motor housing 36 includes stator housing 42 and bearing housing 44. Blades 46 and fan hub 48 of blade assembly 34 are shown.

[0064] Electric machine 10 is shown as an electric motor configured to generate a rotating mechanical output. In the example shown, electric machine 10 is configured to generate the output coaxially with common axis CA. Motor housing 36 encloses other components of electric machine 10. In the example shown, motor housing 36 includes a first, larger diameter portion and a second, smaller diameter portion. The first portion is formed by stator housing 42 and the second portion is formed by bearing housing 44. Both stator housing 42 and bearing housing 44 enclose rotating components of electric machine 10. Electric components of electric machine 10 are disposed, at least partially, within stator housing 42.

[0065] Supports 38 extend axially from stator housing 42 and are configured to interface with a support surface. In some examples, supports 38 can rest on the support surface such that stator housing 42 extends vertically above supports 38. Bearing housing 44 is disposed a lower axial end of stator housing 42 opposite blade assembly 34. Bearing housing 44 can thereby be disposed vertically between stator housing 42 and the support surface. In the example shown, bearing housing 44 has a smaller diameter than stator housing 42 and is located vertically below stator housing 42.

[0066] Blade assembly 34 is connected to electric machine 10 to be rotated by electric machine 10. Drive shaft 40 extends from electric machine 10 to provide the rotating mechanical output from electric machine 10 to blade assembly 34 to rotate blades 46 on common axis CA. Fan hub 48 is disposed at an end of drive shaft 40 opposite electric machine 10. More specifically, fan hub 48 is disposed at a distal end of drive shaft 40 opposite a second distal end of drive shaft 40 extending into bearing housing 44. Blades 46 extend radially outward from fan hub 48. In the example shown, electric machine 10 and blade assembly 34 are disposed coaxially on common axis CA such that blades 46, fan hub 48, drive shaft 40, and the rotor of electric machine 10 rotate coaxially.

[0067] In the example shown, fan system 32 is configured such that blade assembly 34 is disposed vertically above stator 14 and rotor 12. For example, fan system 32 can be configured for use in a cooling tower. It is understood that, while vertically oriented fans are discussed, fans according to the present disclosure can be oriented in any desired orientation and can be used to move any desired fluid, including gas and / or liquid.

[0068] Further, while electric machine 10 is described as driving blade assembly 34, it is understood that any one or more aspects of electric machine 10 can be implemented in nonfan applications. Electric machine 10 can be configured for use in any desired electric motor assembly. It is thus understood that, while a fan is one implementation of the motor technologies presented herein, other applications, including non- fan applications, are possible and contemplated as within the scope of the disclosure.

[0069] FIG. 4A is an isometric view of electric machine 10 with the housing removed. FIG. 4B is a partially exploded isometric view of the electric machine 10 shown in FIG. 4A. FIGS. 4A and 4B will be discussed together. Drive shaft 40, rotor 12, and stator 14 of electric machine 10 are shown. Stator 14 is formed in stator phases 22a-22c. Stator phase 22a includes flux rings 24a, 24b, coil 26, and axial returns 28. Stator phase 22b includes flux rings 24c, 24d, coil 26, and axial returns 28. Stator phase 22c includes flux rings 24e, 24f, coil 26, and axial returns 28. Rotor 12 includes rotor body 18 and permanent magnet array 20. Rotor 12 is formed in rotor phases 50a-52c in this example, though it is understood that not all examples are so limited. Rotor phase 50a includes rotor hub 52 and magnet phase 54a. Rotor phase 50b includes rotor hub 52 and magnet phase 54b. Rotor phase 50c includes rotor hub 52 and magnet phase 54c.

[0070] Stator 14 and rotor 12 are disposed coaxially in this example to generate a rotational mechanical output based on electrical inputs. In the example shown, rotor 12 is disposed within stator 14 such that electric machine 10 is an inner rotator, though it is understood that other examples of electric machine 10 are configured as outer rotators having a rotor disposed about the stator. Stator 14 defines a cylindrical interior that rotor 12 is disposed within. Stator 14 is formed by stator phases 22 arrayed along common axis CA. Each stator phase 22 is an annular ring disposed about common axis CA.

[0071] The stator phases 22a-22c do not overlap each other along common axis CA. Stator phases 22a-22c do not radially overlap along axis CA, such that a radial line extending from common axis CA passes through at most only one of the stator phases 22 and does not pass through multiple ones of the stator phases 22 at any given location along common axis CA. The electromagnetic components of each stator phase 22 (e.g., lamina structure and coils 26) only radially overlap with components of that same stator phase 22 and do not radially overlap with electromagnetic components of another of the stator phases 22. For example, axial returns 28 of stator phase 22a only support the function of stator phase 22a and not, for example, stator phase 22b or stator phase 22c. The flux rings 24a, 24b of stator phase 22a only support the function of stator phase 22a and not, for example, stator phases 22b, 22c. Each of the stator phases 22a-22c may only contain one coil 26 and two annular flux rings 24 and, in some cases, only two annular laminate pieces forming the flux rings 24.

[0072] Each stator phase 22 includes first and second flux rings 24 (e.g., flux rings 24a, 24b of stator phase 22a) disposed on opposite lateral sides of a coil 26 of that stator phase 22. In some examples, each flux ring 24 is formed by multiple ring segments 56 fixed relative to each other and extending about the common axis CA. In some examples, the flux ring 24 can be formed by a single laminate structure that extends about the axis CA, such that the flux ring 24 does not include multiple ring segments 56.

[0073] Ring segments 56 are each arcuate portions of laminate structure that together form the annular laminate structure of flux ring 24. Teeth 58 are formed on a radial side of each ring segment 56 facing rotor 12. For example, teeth 58 can project radially inward in examples in which electric machine 10 is an inner rotator and teeth 58 can project radially outward in examples in which electric machine 10 is an outer rotator.

[0074] An annular array of axial returns 28 extends between connects the opposing flux rings 24. The axial returns 28 are disposed on an opposite radial side of the flux rings 24 from rotor 12 and teeth 58. As shown, the axial returns 28 form the outermost electrically conducting portion of stator 14. In the example shown, axial returns 28 form the outermost laminate structure of the electric machine 10 as electric machine 10 is shown as an inner rotator. It is understood that in examples in which electric machine 10 is an outer rotator the axial returns 28 can form the innermost laminate structure of the electric machine 10. The axial returns 28 can extend radially outward from the common axis CA further than the flux rings 24 or other laminate or metal superstructure.

[0075] Axial returns 28 can be connected directly to stator housing 42, such as by potting compound, and interface with other laminate portions of stator 14 on only the inner radial side of the axial return 28 and, in some cases, interface with the other laminate portions on one or both circumferential sides of the axial return 28. Axial returns 28 are not disposed radially between laminate structures of stator 14 in this example. Axial returns 28 are not disposed radially between laminate structure that is itself directly connected to teeth 58 by laminate or other electrically conductive structure in this example. It is understood, however, that not all examples are so limited. For each stator phase 22, coil 26 is disposed axially between the first and second flux rings 24 of the stator phase 22. Wire ends 68 extend from coil 26 at a location radially between the axial returns 28 and rotor 12 to a location radially outside of the axial returns 28 through wire gaps. Wire ends 68 are thereby exposed outside of electric machine 10 and provide locations for electrical connections to be formed with electric machine 10. The wires ends 68 of the multiple coils 26 of the stator phases 22a-22c are shown as arrayed along the common axis CA and aligned axially along the common axis CA, though it is understood that not all examples are so limited.

[0076] Rotor 12 is configured similar to stator 14, in the example shown, in that rotor 12 is formed from multiple rotor phases 50 configured to operate together. It is understood, however, that not all examples are so limited. For example, the rotor 12 can include a single magnet array 20 that extends the length of the rotor 12 such that each stator phase 22 interacts with the same magnet array 20 of the rotor 12.

[0077] Rotor body 18 supports permanent magnet array 20. As best seen in FIG. 4B, the rotor 12 includes three rotor phases 50a-50c. Each rotor phase 50 corresponds with a single stator phase 22 of stator 14. It is understood that electric machine 10 can include more or fewer than three rotor phases 50. For example, electric machine 10 can include a single rotor phase 50 that magnetically interacts with each of the multiple stator phases 22 of the stator 14. It is understood that in various other examples the electric machine 10 can include a single permanent magnet array 20 that radially overlaps with all of the stator phases 22 of the stator 14.

[0078] Permanent magnet array 20 is formed by interposed permanent magnets 60 and concentrators 62 in the example shown, though it is understood that not all examples are so limited. Concentrators 62 can be formed by stacks of laminas. In the example shown, permanent magnet array 20 is formed by magnet phases 54a-54c respectively associated with rotor phases 50a-50c.

[0079] Rotor 12 is mounted on drive shaft 40. In the example shown, each rotor phase 50 includes a rotor hub 52 connected to the drive shaft 40 and forming a portion of the rotor body 18. In the example shown, each magnet phase 54 is disposed on the outer radial side of an associated rotor hub 52.

[0080] Each stator phase 22 includes two annular arrays of teeth 58 disposed on opposite axial sides of the coil 26 of that stator phase 22. It is understood that in some examples the teeth 58 do not extend to radially overlap with the coil 26 while in various other examples the teeth 58 can include portions that extend at least partially axially to radially overlap with the coil 26.

[0081] Each stator phase 22 includes a first flux ring 24 and a second flux ring 24. The first flux ring 24 (e.g., flux ring 24a of stator phase 22a; flux ring 24c of stator phase 22b; and flux ring 24e of stator phase 22c) and its associated components and aspects can be referred to as forming an A-side of the stator phase 22. The second flux ring 24 (e.g., flux ring 24b of stator phase 22a; flux ring 24d of stator phase 22b; and flux ring 24f of stator phase 22c) and its associated components and aspects can be referred to as forming a B-side of the stator phase 22. The first flux ring 24 has a first annular array of teeth 58 and the second flux ring 24 has a second annular array of teeth 58.

[0082] Within each stator phase 22, the first annular array of teeth 58 is disposed on a first axial side of coil 26 (e.g., spaced in first axial direction ADI from its coil 26) while the second annular array of teeth 58 is disposed on the second, opposite axial side of the coil 26 (e.g., spaced in second axial direction AD2 from its coil 26). Within each stator phase 22, the teeth 58 of the first annular array of teeth 58 are at least partially misaligned or offset (circumferentially and axially) relative to the teeth 58 of the second annular array of teeth 58 (e.g., teeth 58 of flux ring 24a are axially misaligned with teeth 58 of flux ring 24b). This misalignment of the A-side teeth 58 relative to the B-side teeth 58 facilitates flux coupling across the magnet array 20 from oppositely poled teeth 58 of the respective A- side and B-side annular arrays of teeth 58.

[0083] While the teeth 58 within each stator phase 22 are offset and misaligned (circumferentially and axially), the respective A-side teeth 58 of the multiple stator phases 22 can be axially aligned and the respective B-side teeth 58 of the multiple stator phases 22 can be axially aligned. It is understood, however, that not all examples are so limited. For example, the respective A-side teeth 58 of the multiple stator phases 22 can be axially misaligned relative to each other. For example, the respective A-side teeth 58 of the multiple stator phases 22 in a three phase electric machine 10 can be circumferentially offset and axially misaligned to facilitate driving signals 120-degrees electrically offset through each of the three stator phases 22. The driving signals can be between about 110- degrees and 130-degrees electrically offset in some examples. The driving signals can be about 120-degrees electrically offset.

[0084] The A / C signals routed through the coils 26 are synchronized to develop magnetic fields through the flux rings 24 in time with the rotational position of permanent magnet array 20 to drive rotation of rotor 12. The respective A / C signals (e.g., sinusoidal or trapezoidal) delivered through the coils 26 in each stator phase 22a-22c are out of phase with respect to each other. In this way, the permanent magnets 60 forming the permanent magnet array 20 more frequently have flux peaks acting on them, as compared to synchronizing the sinusoidal A / C signals, thereby providing a smoother torque profile acting on the rotor 12 along the axis of rotation of rotor 12.

[0085] The embodiment of the electric machine 10 discussed has three phases corresponding to the three stator phases 22a, 22b, 22c and respective coils 26 therein. As such, three sinusoidal A / C signals are delivered through the coils 26 120-degrees electrically offset. If there were two stator phases 22 and two coils 26, then the two sinusoidal A / C signals would be 180-degrees electrically offset, or 90-degrees electrically offset for sets of four stator phases 22 and four coils 26.

[0086] Stator phases 22a-22c can each be of the same configuration such that a common base stator phase 22 can be used to form any one of the multiple stator phases 22 of the electric machine 10.

[0087] Two opposite polarized states are shown between FIGS 5A and 5B. As shown, the alternating flux path directions and polarizations are developed through the laminate of the ring segments 56, formed by tooth laminas 70, and the laminate of the axial returns 28, formed by return laminas 72. The alternating flux paths can be due to a sinusoidal signal delivered to each coil 26 to flux pair adjacent teeth 58 on opposite sides of the coil 26. These flux paths polarize the teeth 58a relative to teeth 58b to attract or repel the permanent magnets 60 of rotor 12 in synchrony with rotation of the rotor 12 so that flux paired ones of the teeth 58 attract a permanent magnet 60 as the permanent magnet 60 approaches and / or repel the permanent magnet 60 as the permanent magnet 60 passes.

[0088] Flux paired teeth 58 refer to respective closest pairs of teeth 58 of opposed circular tooth arrays of a stator phase 22 (e.g., the teeth 58 of flux ring 24a and teeth 58 of flux ring 24b are flux paired, the teeth 58 of flux rings 24c, 24d are flux paired, the teeth 58 of flux rings 24e, 24f are flux paired). While a subset of teeth 58a, 58b are highlighted as flux paired ones of teeth in FIGS. 5A and 5B, it is understood that these are examples and all teeth 58a, 58b of flux rings 24a, 24b similarly flux pair across the circular arrays of teeth 58a, 58b.

[0089] Each tooth 58a is part of a similar flux circuit with its corresponding flux pair tooth 58b. The flux paired teeth 58a, 58b pair generally axially with a tooth 58a, 58b of the opposing circular array of teeth 58a, 58b, and not circumferentially to the neighbor tooth 58a, 58b of the same circular array of teeth 58a, 58b because all teeth 58a of the circular array of teeth 58a will have the same polarity at any given time while all teeth 58b of the opposed circular arrays of teeth 58b of the same stator phase 22a will have the opposite polarity at any given time. More specifically, each tooth 58a of the circular array of teeth 58a flux pairs with the closest teeth 58b of the circular array of teeth 58b on the other axial side of the coil 26. As shown in FIGS. 5A and 5B, a flux circuit is formed through flux paired teeth 58a, 58b such that the teeth 58a, 58b are respectively polarized, north and south.

[0090] In various examples, each tooth 58 can narrow circumferentially as the tooth 58 extends radially away from the body of its flux ring 24. The lamina structure that the tooth 58 extends from, which can form the body of the flux ring 24 or of a ring segment 56 and which is formed from tooth laminas 70, forms a lamina base 64 from which the teeth 58 extend. Multiple adjacent teeth 58 of an annular array of teeth 58 can extend from a common lamina base 64. In some examples, all teeth 58 of an annular array of teeth 58 can extend from a common lamina base 64 such as in examples in which the flux ring 24 does not include multiple ring segments 56. The teeth 58 can be wholly or partially formed by the tooth laminas 70 that form the common lamina base 64. As such, multiple adjacent ones of the teeth 58 can be formed from the same laminas and monolithic with each other.

[0091] In the example shown, teeth 58 extend to a tooth face 66 oriented towards rotor 12. In the example shown, the teeth 58 each narrow to the tooth face 66, though it is understood that not all examples are so limited. The tooth faces 66 can be planar and / or can be formed tangentially to a circle centered on common axis CA, among other options. The tooth faces 66 provide a narrowed surface area relative to the lamina base 64 and the axial returns 28. Teeth 58 narrow to concentrate flux towards rotor 12 to focus concentrated flux to a limited part of the rotor 12.

[0092] The magnetic flux is generated by coil 26. Specifically, an A / C signal is run through coil 26 which rapidly builds and collapses the magnetic field due to the current reversal of the A / C signal through the coil 26. As shown, flux concentrating material of a stator phase 22 is wrapped around at least three sides of the coil 26. In the example shown, the flux rings 24a, 24b and axial returns 28 wrap around at least three sides of the coil 26. The lamination grain of the flux concentrating material is shown in FIGS. 5A-5C. The lamination grain of the concentrators 160 and axial returns 48 can further be seen in FIG. 5C. While the concentrators are shown as including circumferentially stacked lamina sheets that extend axially, it is understood that not all examples are so limited. For example, the lamina sheets forming a concentrator 62 can be stacked axially. Generally, flux flows with the grain, along the direction of lamination, as flux will generally follow the path of highest permeability and there is significant resistance to flux jumping from one layer of lamination to another layer of lamination. The lamination grain of the ring segments 56, including the teeth 58a, 58b, is radially orientated while the lamination grain of the axial returns 28 is axially oriented. As such, the flux flows axially through the axial returns 28 and radially through the ring segments 56 and teeth 58a, 58b in a U shape toward the rotor 12, with the base of the U on an opposite side of the coil 26 from the rotor 12 and the legs of the U oriented towards the rotor 12. FIGS. 5A and 5B represent the reversal of the A / C signal and how the poles of the flux paired teeth 58a, 58b are switched.

[0093] In the example shown, the teeth 58 and ring segments 56 are formed by tooth laminas 70 and the axial returns 28 are formed by return laminas 72. The return laminas 72 and the tooth laminas 70 interface with each other at a transverse lamination interface 74.

[0094] Each flux ring 24 can be formed by tooth laminas 70. It is understood that all teeth 58 and / or ring segments 56 of a flux ring 24 can be formed from tooth laminas 70. All axial returns 28 can be formed from the return laminas 72. The return laminas 72 and the tooth laminas 70 cross over each other.

[0095] A single return lamina 72 can span across multiple tooth laminas 70 of a single flux ring 24. A single return lamina 72 can span across all tooth laminas 70 of a single flux ring 24. A single return lamina 72 can span across multiple flux rings 24, such as both flux rings 24 of a pair of flux rings 24 of a stator phase 22.

[0096] A single tooth lamina 70 can span across multiple return laminas 72 of a single axial return 28. A single tooth lamina 70 can span across multiple return laminas 72 of multiple axial return 28. A single tooth lamina 70 can span across all of the return laminas 72 of one or multiple of the axial returns 28.

[0097] The return laminas 72 and the tooth laminas 70 are oriented transverse to each other. In the example shown, the return laminas 72 and the tooth laminas 70 are disposed orthogonal with respect to each other, though it is understood that not all examples are so limited. The return laminas 72 are orientated axially (e.g., the long parallel sides of the return laminas 72 are parallel with the axis). The tooth laminas 70 are orientated circumferentially and / or tangentially (e.g., the long sides of the tooth laminas 70 extend around the axis). The flux paired ones of teeth 58a, 58b are circumferentially offset from each other such that the teeth 58a of one flux ring 24 are not axially aligned with teeth 58b of the other flux ring 24 of the same stator phase 22. Being that the ends of the flux paired teeth 58a, 58b of the same stator phase 22 are not aligned axially, because teeth 58a are offset circumferentially from teeth 58b, the flux circuit travels at least a limited distance circumferentially between the flux paired ones of teeth 58a, 58b. Therefore, a cumulative flux circuit comprised of a plurality of flux paired teeth 58a, 58b can flow in a spiral pattern circumferentially through the teeth 58a, 58b and axial returns 28. It is noted that, while most flux flows between flux paired ones of teeth 58a, 58b, the ring segments 56 permit flux flow between teeth 58a, 58b of the same ring segment 56, such that a limited amount of flux may skip a set of flux paired teeth 58a, 58b to the next-over tooth 58a, 58b of the same ring segment 56. As discussed above, adjacent ring segments 56 of the same flux ring 24 can be separated by one or more circumferential gaps that is bridged only by potting compound. The adjacent ring segments 56 are isolated to prevent flux flow between the adjacent ring segments 56, thereby inhibiting the formation of eddy currents and facilitating efficient operation of electric machine 10.

[0098] While the illustrated electric machine embodiment generally shows aligned teeth across the stator phases and offset magnet phases of the rotor, this convention can be reversed such that the teeth are offset between phases and the magnets are aligned across phases, among other options.

[0099] FIG. 5C shows a detailed view of flux paired teeth 58a, 58b of the stator 14 interacting with concentrators 62 and permanent magnets 60 of the magnet array 20. The A / C signal through the coil 26 changes the direction of the electric current rapidly and thus changes the north-south polarity of the flux paired teeth 58a, 58b rapidly. The view of FIG. 5C shows an instance in which all teeth 58a of the circular array of teeth 58a have a north polarization while all teeth 58b of the circular array of teeth 58b have a south polarization.

[0100] Also at this instance, the teeth 58a, 58b are aligned with the concentrators 62 that are disposed circumferentially between the permanent magnets 60. The laminate of the concentrators 62 does not have an inherent polarization, but due to the fixed position of concentrators 62 between magnet poles, the concentrators 62 assume an effective permanent polarization as indicated. Each concentrator 62 contacts two permanent magnets 60. Each concentrator 62 contacts the same pole of the two permanent magnets 60. For example, a concentrator 62 will be in contact with two south poles or be in contact with two north poles. The concentrators 62 take on alternating north and south polarization on opposite sides of each permanent magnet 60 depending on the polarization adjacent to that concentrator 62. As indicated, each permanent magnet 60 is permanently polarized north and south on opposite sides of its short axis. The interleaved arrangement of permanent magnets 60 and concentrators 62 creates circumferential regions of oppositely polarized concentrators 62 and permanent magnet 60 poles.

[0101] The concentrators 62 route the magnetic flux from the permanent magnets 60 toward the stator 14. Flux circuits are completed across the air gap 30 between the stator 14 and rotor 12. The flux from the rotor 12 (specifically the permanent magnets 60) and the flux from the coil 26 (through the teeth 58a, 58b) interact in the air gap 30, and the resulting flux shear forces rotation of the rotor 12. The flux of the present electric machine 10 has an orientation transverse to the axis of rotation (which axis of rotation is coaxial with common axis CA). This is different from the radial flux orientation of traditional A / C and D / C brushless motors.

[0102] The flux generated by the stator 14 and acting on the rotor 12 is constantly changing due to both changing position of the permanent magnets 60 and concentrators 62 due to rotation of the rotor 12 as well as the change in polarization of the teeth 58a, 58b due to the change in the A / C signal through the coil 26. As such, the A / C signal routed through the coil 26 is synchronized with rotation of the rotor 12 to develop magnetic fields through the teeth 58a, 58b in time to the concentrators 62 approaching and departing the teeth 58a, 58b to simultaneously push and pull the permanent magnets 60 of the rotor 12 to provide the force that rotates the rotor 12. More specifically, the N-N and S-S interfaces repel while N- S interfaces attract, on approach and departure of alignment.

[0103] At least some of the respective A / C signals (e.g., sinusoidal or trapezoidal) delivered through the multiple coils 26 forming stator 14 are out of phase with respect to each other. In this way, the rotor 12 (along its axial length) more frequently has flux peaks acting on it, as compared to synchronizing the sinusoidal A / C signals, for a smoother torque profile acting on the rotor 12 along the axis of rotation of the rotor 12, which is also the common axis CA.

[0104] Traditional A / C induction motors use a plurality of discrete coils that form an array of coils that extend circumferentially around the axis of rotation of the rotor. Each coil represents a potential pole for acting on a magnet. The discrete coils arrayed circumferentially around the axis of rotation in a conventional A / C induction motor are out of phase with respect to each other. The discrete coils can interact with a small subset of the magnets at any given instance. The potential torque generated is proportional to the number of poles. The number of poles in such a motor is limited by the ability to fit discrete coils circumferentially around the axis of rotation within the motor. Coil windings can be made smaller, and the diameter of the stator can be made bigger, to accommodate more coils to support more poles, but this increases the size, weight, and cost of the motor and still has limits. Power can also be increased when the rotor is rotating at a relatively high rate, whereby more coil-magnet passes can be experienced per unit time. But such power increase requires the motor to operate at relatively high speed when some applications may desire low-speed output. Providing reduction gearing to reduce speed and increase torque to the desired high torque and low speed increases cost, weight, size, and friction.

[0105] Electric machines 10 according to the present disclosure are different from traditional A / C and D / C machines. An aspect of the electric machine 10 is that it contains relatively few coils 26, only three in the illustrated embodiment. Unlike traditional A / C and D / C motors, the coils 26 are formed from loops of wire that extend entirely around the axis of rotation of the rotor 12 (and the common axis CA). The axis of rotation of the rotor 12 (and the common axis CA) extends through each loop (e.g., the center of each loop). Each coil 26 is annular, and the loops of each coil 26 are likewise annular, and the circular planar profile of the coil 26 and loops are orthogonal to the common axis CA. The wire of each coil 26 forms a single hoop, which has multiple loops that overlap and contact one another to form the single hoop assembly. The coils 26 do not include loops that generate flux that rotates the rotor 12 through which the common axis CA does not extend. Instead of adding a coil for each pole as in traditional A / C induction motors, the flux rings 24 and axial returns 28 surrounding a single coil 26 channel the flux to a plurality of teeth 58 that flux pair across the flux rings 24 of a stator phase 22 to create a plurality of poles from the single coil 26.

[0106] In the example shown, for each stator phase 22, one coil 26 supports multiple poles equal to the number of teeth 58 of a single flux ring 24. For example, if each flux ring 24 includes twenty-four teeth 58, then twenty-four poles will be formed from the single coil 26 between those flux rings 24. It is understood that lower and higher poles can be created depending on the number of teeth 58. As such, activating one coil 26 activates many poles, whereas in some traditional A / C and D / C motors activation of one coil activates only one pole. Multiple coils 26 are arrayed along the axis of rotation of the rotor 12 with each coil 26 interacting with the magnet array 20, thereby multiplying the number of poles.

[0107] The high pole count eliminates or reduces the need for reduction gearing for outputs from electric machine 10, reducing off-center forces as well as reducing weight and friction, allowing for a more compact arrangement of electric machine 10. The electric machines 10 of the present disclose can generate high torque with a small package size, even at low speed. Therefore, gear reduction of a drive can be minimized or entirely excluded, providing savings on cost, size, weight, and friction.

[0108] FIG. 6 is an isometric view of a potion of a stator phase 22. An axial return 28 is removed to show the tooth laminas 70 that form the ring segments 56 and the teeth 58. Axial return laminas 72 are also shown for one of the axial returns 28.

[0109] Flux paths 76 are shown in FIGS. 5A and 5B. The flux paths 76 generally go through the teeth 58 to generate flux paired teeth 58 an opposite sides of the coil 26, as previously described. The flux paths 76 through the teeth 58 and ring segments 56 are generally orientated radially, alternately directed towards the axis and away from the axis in sync with the drive signal (e.g., sinusoidal drive signal). The radial orientation of the flux path 76 is due to the tooth laminas 70 being radially oriented as the flux readily flows along the grain of stacked laminations. Being that the tooth laminas 70 are axially stacked, the flux traveling through the tooth laminas 70 is generally prevented from traveling axially as there is significant resistance to the flux jumping between adjacent laminas. However, the flux can travel circumferentially / tangentially because the shorter side of each lamination of the tooth laminas 70 also extends circumferentially / tangentially.

[0110] The flux path through the axial returns 28 is generally orientated axially. Flux paths 76 can also extend radially, partway through the axial returns 28, being that the short sides of the axial return laminas 72 are oriented radially to receive flux along flux paths 76, but such flux gets redirected to flow axially along the long sides of the axial return laminas 72 to couple pairs of teeth 58 on opposite sides of the coil 26 to have opposite polarities.

[0111] According to the right-hand rule, the radially orientated flux paths 76 through the tooth laminas 70 and the axial return laminas 72 could induce current around the flux paths 76, in this case eddy currents, in circular paths orthogonal to the flux paths 76, which is unwanted due to lowering efficiency and increasing heat rise. Such eddy currents orthogonal to the flux paths 76 are mitigated in part by the orientation of the laminations because current tends to flow along the laminations (e.g., is channeled in each lamination) and not between adjacent laminations. The tooth laminas 70 permit radial and circumferential / tangential current flow while inhibiting axial current flow, while the axial return laminas 72 permit radial and axial current flow while inhibiting circumferential / tangential current flow. No current paths which are orthogonal to the flux paths 76 are permitted in the tooth laminas 70 because there is significant resistance to the current flowing axially between the stacked tooth laminas 70, and no current paths which are orthogonal to the flux paths 76 are permitted in the axial return laminas 72 because there is significant resistance to the current flowing circumferentially / tangentially between the circumferentially stacked return laminas 72. As such, the general lack of circular current paths substantially inhibits the generation of eddy currents, or at least this is how such motors were understood.

[0112] However, the inventors have discovered that circular current paths are unexpectedly developed by bridging between the tooth laminas 70 and the return laminas 72 in direct contact with each other, still resulting in loss of performance and heat rise. In particular, when the return laminas 72 make physical contact with the tooth laminas 70 along a transverse laminations interface 74, then general circular current paths, roughly but not strictly orthogonal to the flux paths 76, can be developed by the current traveling circumferentially / tangentially along the tooth laminas 70 and then conducting across the transverse laminations interface 74 (by direct contact between the transversely oriented return laminas 72 and tooth laminas 70) to the return laminas 72 to conduct axially and then back across the transverse laminations interface 74 to the tooth laminas 70 to once again travel circumferentially / tangentially. Such a three dimensional square / rectangular connection pathway CP, not strictly orthogonal to the flux paths 76, still approximates the circular paths that generate eddy currents sufficient to result in unwanted losses and heat rise. Such a connection pathway CP can thereby generate unwanted currents that can result in loss of performance and heat rise.

[0113] FIG. 7 is a schematic view showing a transverse lamination interface 74 between return laminas 72 and tooth laminas 70. The schematic of FIG. 7 further demonstrates how eddy current pathways CP are generated by traveling through the transverse laminations interface 74 and thus between the return laminas 72 of the axial returns 28 and the tooth laminas 70 of the ring segments 56 / teeth 58. Specifically, a circumferential / tangential path Pl extends through the tooth laminas 70 which connects with an axial path P2 as the current conducts across the transverse laminations interface 74 to conduct through the return laminas 72. In this way, the mitigation of eddy currents by use of parallel lamination stacks is defeated by unexpected conduction of the current between the transversely orientated laminations of the axial returns 28 and the teeth 58 / ring segments 56.

[0114] As detailed above, the inventors have discovered an unexpected source of eddy currents which had been degrading performance without explanation. Aspects of the disclosure unexpectedly increase performance by minimizing the previously unknown eddy current generation by the current conducting across the transverse laminations interface 74.

[0115] To combat the previously unknown eddy current generation, spacers 78 are disposed to generate a gap 80 between the opposed return laminas 72 and tooth laminas 70. The gap 80inhibits conduction across the transverse laminations interface 74 between the return laminas 72 and the tooth laminas 70. The spacers 78 provide a spacing distance between the return laminas 72 and the tooth laminas 70 that inhibits such conduction across separate lamination stacks. Previously, the return laminas 72 and tooth laminas 70 were generally pressed into contact each other during motor assembly, in which such close contact was thought to support the strongest transfer of flux (along flux path 76) between the axial return laminas 72 and tooth laminas 70, and was not thought to be at risk of generating eddy currents because the axial return laminas 72 are oriented transverse to the tooth laminas 70. But as explained herein, creating and maintaining a short separation distance between the return laminas 72 and the tooth laminas 70 at the transverse laminations interface 74 can reduce generation of such eddy currents (the presence of which were previously unexplained) while still supporting robust flow of flux between the tooth laminas 70 and the return laminas 72 across the transverse laminations interface 74.

[0116] The spacers 78 can take several forms, as further discussed herein. The spacers 78 can be in the form of standoffs, forcing a separation distance between tooth laminas 70 and the return laminas 72 across the transverse laminations interface 74. The flux paths 76 can extend directly though the spacers 78.

[0117] FIG. 8 is a cross-sectional view of a stator phase 22. Flux rings 24, axial return 28, and coil 26 are shown. Spacer 78 is disposed between axial return 28 and the lamina base 64 of the flux ring 24. A gap 80 is formed and maintained directly between the tooth laminas 70 and the return laminas 72 across the transverse laminations interface 74. The gap 80 is formed and maintained by the spacer 78. Spacer 78, in this example, is formed by spacing layer 82. The spacing layer 82 can be formed from polymer or other dielectric material. The spacing layer 82 can be formed from sheet material, such as PET, Kapton, or Nomex amongst others. The spacing layer 82 can be a cured liquid coating such as formed by epoxy or polyester, amongst other options. The spacing layer 82 can be a deposited coating, such as being coated by CVD or PVD. The spacing layer 82 can be adhered glass microspheres, amongst other options. The spacing layer 82 can be in the form of tape, having at least one of the sides of the spacing layer 82 coated in adhesive to adhere to one or both of the tooth laminas 70 and the return laminas 72. In some examples, the spacing layer 82 can include adhesive on both of radial sides to stick to both of the tooth laminas 70 and the return laminas 72. The spacing layer 82 can be in the form of molded inserts, such as a polymer injected molded piece.

[0118] The spacing layer 82 can partially or fully radially overlap with the transverse laminations interface 74. The flux path 76 can extend directly through the spacing layer 82 while the spacing layer 82 stops electrical conduction through the transverse laminations interface 74. In some examples, the spacer 78 can be formed by multiple of the spacing layers 82 disposed between the axial return 28 and flux ring 24. In the example shown, a first spacing layer 82 is disposed directly radially between the axial return 28 and a first one of the flux rings 24 and a second spacing layer 82 is disposed directly radially between the axial return 28 and a second one of the flux rings 24. In such an example, one of the spacing layers 82 is disposed at each transverse lamination interface between the axial return 28 and the flux rings 24. In the example shown, the spacing layers 82 do not extend to radially overlap with the coil 26, though it is understood that not all examples are so limited.

[0119] The spacing layer 82 can be adhered to the tooth laminas 70 or the return laminas 72 during assembly, such as before the transverse laminations interface 74 is formed. The spacing layer 82 can be placed and adhered to the return laminas 72 or the tooth laminas 70, and then the return laminas 72 can be mounted across from the tooth laminas 70 (or the tooth laminas 70 can be mounted across from the return laminas 72 depending on the assembly process). The spacing layer 82 can, in some examples, adhere to both the tooth laminas 70 and the return laminas 72 with stator 14 assembled.

[0120] The spacing layer 82 can be adhered to the teeth 58 and / or ring segments 56 (depending on how the stator 14 is structured) and then the axial returns 28 can be mounted to the teeth 58 and / or ring segments 56. Alternatively, the spacing layer 82 can be adhered to the axial returns 28 and then the teeth 58 and / or ring segments 56 can be mounted to the axial returns 28. It is understood that other assembly procedures are possible.

[0121] In some examples, the spacing layer 82 can be square or otherwise rectangular. In the example shown, the spacing layer 82 extends over at least 50% of the transverse laminations interface 74. As shown, the spacing layer 82 can extend over 70% of the transverse laminations interface 74. As shown, the spacing layer 82 can extend over 90% of the transverse laminations interface 74. In the example shown, the spacing layer 82 does not extend radially over the coil. As shown, the spacing layer 82 does not extend axially beyond the teeth 58, ring segments 56, and / or axial returns 28. It is understood, however, that not all examples are so limited.

[0122] The gap 80 is preferably as thin as possible while maintaining the return laminas 72 out of direct contact with the tooth laminas 70. For example, the gap 80 can be between .001-.50 millimeters. The gap 80 can be between .002-.80 millimeters. These ranges can be applied to all examples and motor embodiments referenced herein. The gap 80 can be an air gap or can be filled with dielectric material. For example, the gap 80 can be filled with potting compound, among other options.

[0123] In various examples, the spacer 78 can be adhered to the return laminas 72 and / or the tooth laminas 70 independent of any other adhesive, such as potting compound. In some examples, the spacing layer 82 can be formed for a material that only forms the spacing layer 82 and which material is not used to form any other part of the stator 14. In some examples, the type of material from which the spacing layer 82 is made, such type of material only forms the spacing layer 82 and is not used to form any other part of the stator 14.

[0124] FIG. 9 is a cross-sectional view showing a portion of a stator phase 22. As shown, the spacer 78 is formed as a spacing layer 82. The spacing layer 82 in this example is disposed radially between the coil 26 and the axial return 28. The spacing layer 82 in this example is disposed directly radially between the coil 26 and the axial return 28. The spacing layer 82 in the example shown is disposed directly radially between the coil 26 and the return laminas 72. In the example shown, the spacing layer 82 does not radially overlap with tooth laminas 70. The spacing layer 82 can, in some examples, axially overlap with the tooth laminas 70. The spacing layer 82 does not axially overlap with the return laminas 72 in the example shown.

[0125] The spacing layer 82 can first be deposited on the coil 26 or the center of the axial return 28. The spacing layer 82 can take the form of any layer referenced herein. In the example shown, the spacing layer 82 is not directly within a transverse laminations interface 74. In this case, the transverse laminations interface 74 may be left as an air gap that is maintained during operation of the machine 10, through it is understood that the transverse laminations interface 74 may still be occupied by other material in various other embodiments (e.g., filled with potting compound). In some examples, the spacing layer 82 can be formed as part of structure that partially or fully encapsulates the coil 26. For example, the coil 26 can be overmolded by material that forms the spacing layer 82.

[0126] FIG. 10 is a cross-sectional view showing a portion of a stator phase 22 similar to FIGS. 8 and 9. In the example shown, the spacing layer 82 extends to radially overlap with the coil 26 and with the tooth laminas 70. The spacing layer 82 can extend fully across the return laminas 72 and can fully cover a face of the axial return 28 oriented radially towards the tooth laminas 70. In some examples, the spacing layer 82 can fully encapsulate the axial return 28. For example, the spacing layer 82 can be overmolded onto the return laminas 72 forming the axial return 28. In the example shown, the spacing layer 82 radially overlaps with the tooth laminas 70 of both flux rings 24. In the example shown, a single spacing layer 82 can extend into both transverse lamination interface 74, one between the first flux ring 24 and the axial return 28 and the other between the second flux ring 24 and the axial return 28. In the example shown, the spacing layer 82 can radially overlap with both the tooth laminas 70 and the coil 26.

[0127] FIG. 11 shows a cross-sectional view similar to that of FIG. 8, except a different spacer 78 is used. In the example shown, the gap 80 is still present and is formed by the spacer 78. However, the spacer 78 itself is formed by elongate strips 84. The elongate strips 84 form and maintain the gap 80 between the axial return 28 and the flux rings 24. The elongate strips 84 can ideally be formed from nonconductive material, however in some examples the elongate strips 84 can be formed from conductive material. The elongate strips 84 can be string or a ribbon. The elongate strips 84 are formed from different types of material than the material which forms the return laminas 72 and the tooth laminas 70. The elongate strips 84 can be adhered in any manner described in reference to the spacing layer 82. In some examples, the elongate strips 84 can include an adhesive layer such that the elongate strip 84 can be directly adhered to one or both of return laminas 72 and tooth laminas 70.

[0128] In some examples, the elongate strip 84 is at least partially disposed in a trench 86. The trench 86 can be formed in one or both of the axial return 28 and the flux ring 24. The trench 86 can be formed in one or more of the return laminas 72. The trench 86 can be formed in one or more of the tooth laminas 70. In various examples, the trench 86 can include a first depression in one of the tooth laminas 70 and the return laminas 72 and can include a second depression in the other one of the tooth laminas 70 and the return laminas 72. The elongate strips 84 can be laid in trenches 86 formed in the axial returns 28 and / or in the teeth 58 and / or ring segments 56. The elongate strips 84 can be laid in trenches 86 formed in the return laminas 72 and / or the tooth laminas 70. In the example shown, the elongate strips 84 extend along the elongated portion of tooth laminas 70 and extend transverse to the elongated portion of the return laminas 72. The elongate strips 84 can be considered to extend along the grain of the tooth laminas 70 and transverse to the grain of the return laminas 72. In the example shown, the elongate strips 84 extend circumferentially or tangentially to a circle centered on the axis. In the example shown, the elongate strips 84 do not extend over the coil 26.

[0129] FIG. 12A is a cross-sectional view showing a portion of a stator phase 22. FIG. 12B is an enlarged view of detail B in FIG. 12A. FIGS. 12A and 12B are discussed together. In the example shown, the spacer 78 is formed as a standoff projection 88. The standoff projection 88 is formed by one or more laminas of the stator phase 22. In the example shown, the standoff projection 88 is formed by one or more of the return laminas 72 of the axial return 28. It is understood, however, that not all examples are so limited. In some examples, the standoff projection 88 can be formed by one or more of the tooth laminas 70 of the flux rings 24.

[0130] The standoff projection 88 can be formed by a subset of laminas of the stator 14. For example, the standoff projection 88 can be formed by a subset of return laminas 72, which can include up to all of the return laminas 72 of the axial return 28. In some examples, the standoff projection 88 can be formed by a series of aligned protuberances 90 across the return laminas 72 of the axial return 28. The protuberances can be formed as bumps among other options. In some such examples, each lamination of the return laminas 72 includes a protuberance 90 and the respective protuberances 90 align when the return laminas 72 are stacked together to form the standoff projection 88. The standoff projection 88 is sized to form the gap 80 and inhibit formation of eddy currents.

[0131] In examples in which spacer 78 is formed by standoff projection 88, the spacer 78 is capable of transmitting magnetic flux. The standoff projection 88 is sized such that the direct interfacing between the standoff projection 88 and the opposed lamina structure (e.g., tooth laminas 70 when the standoff projection 88 is formed from one or more return laminas 72) does not support the circular pathway that forms eddy currents.

[0132] In some examples, the standoff projection 88 can be sized based on the transverse lamination interface 74. In some examples, the standoff projection 88 can span across less than 50% of the axial length L of the transverse lamination interface 74. In some examples, standoff projection 88 can span across less than 20% of the axial length L of the transverse lamination interface 74. In some examples, standoff projection 88 can span across less than 10% of the axial length L of the transverse lamination interface 74. In some examples, the standoff projection 88 can span across less than 5% of the axial length L of the transverse lamination interface 74. In some examples, the standoff projection 88 can span across less than 1% of the axial length L of the transverse lamination interface 74.

[0133] In some examples, the standoff projection 88 can be sized based on the opposing laminas at the transverse lamination interface 74 (e.g., based on the size of the tooth laminas 70 when the standoff projection 88 is formed from one or more return laminas 72). For example, the standoff projection 88 can be sized to contact a subset of the tooth laminas 70 at the transverse lamination interface 74. In some examples, the standoff projection 88 formed by one or more return laminas 72 can span directly over ten or fewer of the tooth laminas 70. In some examples, the standoff projection 88 can span over five or fewer of the tooth laminas 70. In some examples, the standoff projection 88 can span over three or fewer of the tooth laminas 70. In some examples, the standoff projection 88 can span over two or fewer of the tooth laminas 70. In some examples, the standoff projection 88 can span over a single tooth lamina 70.

[0134] The standoff projection 88, whether formed from return laminas 72 or tooth laminas 70, can be formed from a subset of the laminas, the subset including one or more of the laminas. For example, the standoff projection 88 formed by return laminas 72 can be formed by one or more, up to all, of the return laminas 72 of an axial return 28. In examples in which the standoff projection 88 is formed by tooth laminas 70, the standoff projection 88 can be formed by a subset of the tooth laminas 70, such as one, two, three or another number of the tooth laminas 70. For example, a single tooth lamina 70 can extend radially further towards the axial return 28 at the transverse lamination interface 74 than others of the tooth laminas 70 to form the standoff projection 88.

[0135] FIG. 13A is a cross-sectional view showing a portion of a stator phase 22. FIG. 13B is an enlarged view of detail B in FIG. 13A. FIGS. 13A and 13B are discussed together. In the example shown, the spacer 78 is formed as a standoff projection 88. The standoff projection 88 is formed by one or more laminas of the stator phase 22. In the example shown, the standoff projection 88 is formed by one or more of the tooth laminas 70 at the transverse lamination interface 74.

[0136] The standoff projection 88 is sized to form the gap 80 and inhibit formation of eddy currents. In examples in which spacer 78 is formed by standoff projection 88, the spacer 78 is capable of transmitting magnetic flux. The standoff projection 88 is sized such that the direct interfacing between the standoff projection 88 and the opposed lamina structure (e.g., return laminas 72 when the standoff projection 88 is formed from one or more tooth laminas 70) does not support the circular pathway that forms eddy currents. The standoff projection 88 can be a single lamination that extends further out than the rest of the laminations of the same tooth 58 and / or ring segment 56. Standoff projection 88 can extend in a line that is circumferentially / tangentially orientated.

[0137] In some examples, the standoff projection 88 is formed by one or more tooth laminas 70 that project further radially towards the axial return 28 than others of the tooth laminas 70 at the transverse laminations interface 74. In some examples, the standoff projection 88 is formed as a continuous line across the return laminas 72. For example, the standoff projection 88 can be formed as a contiguous projection that does not include breaks. The standoff projection 88 can be contiguous and extend across a full width of the axial return 28, among other options. In some examples, the standoff projection 88 is formed by one or more discrete projections of the tooth lamina 70. For example, the one or more tooth laminas 70 forming the standoff projection 88 can include multiple protuberances that are spaced apart and together form the standoff projection 88. The multiple protuberances can be considered to form a discontinuous standoff projection 88 when spaced apart from each other.

[0138] The standoff projection 88 can be formed by a single tooth lamina 70. It is understood, however, that the standoff projection 88 can be formed by one or more of the tooth laminas 70. The tooth laminas 70 forming a standoff projection 88 for a transverse lamination interface 74 can be disposed adjacent to each other such that the standoff projection 88 is formed as a single enlargement without axial gapping.

[0139] FIG. 14 is an isometric view illustrating a configuration of standoff projections 88. It is understood that the standoff projection 88 illustrated can be formed by one or more return laminas 72 or one or more tooth laminas 70. Whether the standoff projection 88 is formed from return lamina 72 or tooth lamina 70, it can be important to have only a single line of the standoff projection 88 for each transverse lamination interface 74, regardless of whether that line is formed in the return laminas 72 or the tooth laminas 70. The single line can be formed as a continuous line or a broken segmented line (e.g., with gaps along the elongate extent of the line). This is because multiple lines spaced axially apart could support a circuit of eddy current as previously described, but a single standoff projection 88 line is not believed to support such eddy current, regardless of whether the standoff projection 88 is contiguous or discontinuous. The standoff projections 88 as shown are circumferentially / tangentially orientated. It is understood, however, that the standoff projection 88 lines can be axially orientated in various examples.

[0140] In the example shown, the standoff projection 88 is formed as a continuous line. The standoff projection 88 can be contiguous across the extent of the standoff projection 88. For example, the standoff projection 88 can be formed by a tooth lamina 70 and be formed without gapping between portions of the standoff projection 88. In another example, the standoff projection 88 can be formed by a set of aligned protuberances 90 formed by return laminas 72, which protuberances 90 together form the continuous line. While standoff projection 88 can be formed as a continuous line, it is understood that not all examples are so limited. For example, standoff projection 88 can be formed as a disjointed line formed by multiple segments.

[0141] FIG. 15 is an isometric view showing a portion of a ring segment 56. In the example shown, the spacer 78 is formed as a standoff projection 88. It is understood that the standoff projection 88 shown can be formed by one or more tooth laminas 70 or one or more return laminas 72. In the example shown, the standoff projection 88 is disjointed, being split into multiple spaced apart segments, rather than contiguous. The standoff projection 88 is formed as a series of discrete projections that are configured to bridge across the gap 80 at the transverse lamination interface 74. The various discrete projections that form the standoff projection 88 can be aligned with each other to inhibit eddy current generation. For example, the multiple discrete projections forming the disjointed standoff projection 88 can circumferentially and / or tangentially overlap, among other options.

[0142] As shown, at least a portion of the standoff projection 88 is configured to be disposed at the transverse lamination interface 74. However, the standoff projection 88 can include one or more discrete projections that are radially elongate and that project circumferentially or tangentially relative to adjacent laminas.

[0143] While a fan embodiment is shown herein, it is understood that the features of this disclosure could be applied to an electric motor of any application, including non-fan applications.

[0144] Any aspect may be mix as between the different embodiments and features. Two components that are described as connected are not necessarily in contact with each other without an intermediary component, unless it is specified that they are directly connected, in which case the two components are in contact with each other. Although not necessarily stated, any two materials that are contacting in any of the figures can be described (e.g., specifically claimed) as directly connected, and any two components described herein as being connected can be described (e.g., specifically claimed), optionally, as directly connected.

[0145] Optional language is used herein describing what “can” or “may” be present, or what “various” embodiment may include, not what is or must necessarily be present. Therefore, if in reference to an embodiment, it is stated that an aspect “may” or “can” be present, then the option can be included, or left out, of the embodiment, particularly in a claim. Each sentence or paragraph can refer to multiple, independent aspects. A claim can be amended with a select word or phrase from a sentence or paragraph without taking the whole sentence or paragraph.

[0146] While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMS:

1. An electric rotational machine comprising: a rotor rotatable on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; and a stator configured to electromagnetically drive rotation of the rotor, the stator including a plurality of phases, wherein each phase of the plurality of phases comprises: at least one coil wound around the axis such that the axis extends through the at least one coil; a first flux ring including a first plurality of teeth extending around the axis such that the axis extends through the first flux ring, wherein the first flux ring is formed by a first plurality of tooth laminas; a second flux ring including a second plurality of teeth extending about the axis such that the axis extends through the second flux ring, wherein the second flux ring is formed by a second plurality of tooth laminas; a plurality of axial returns arrayed about the axis, the plurality of axial returns extending between the first flux ring and the second flux ring, wherein each axial return of the plurality of axial returns is formed by a plurality of return laminas; and at least one spacer forming a gap directly radially between the first flux ring and a first axial return of the plurality of axial returns.

2. The electric rotational machine of claim 1, wherein the at least one spacer includes a first spacer disposed directly radially between the first flux ring and the first axial return.

3. The electric rotational machine of claim 2, wherein the at least one spacer includes a second spacer disposed directly radially between the first flux ring and the first axial return.

4. The electric rotational machine of claim 1, wherein the at least one spacer does not radially overlap with the first plurality of tooth laminas.

5. The electric rotational machine of claim 4, wherein the at least one spacer does not radially overlap with the second plurality of tooth laminas.

6. The electric rotational machine of any one of claims 1-5, wherein the at least one spacer radially overlaps with the at least one coil.

7. The electric rotational machine of any one of claims 1-3, wherein the at least one spacer does not radially overlap with the coil.

8. The electric rotational machine of claim 1, wherein a first transverse lamina interface is formed between the first plurality of tooth laminas and the plurality of return laminas, and the at least one spacer includes a first spacer forming the gap between the first plurality of tooth laminas and the plurality of return laminas.

9. The electric rotational machine of claim 8, wherein a second transverse lamina interface is formed between the second plurality of tooth laminas and the plurality of return laminas, and the at least one spacer includes a second spacer forming a second gap between the second plurality of tooth laminas and the plurality of return laminas.

10. The electric rotational machine of claim 9, wherein the first spacer is formed separately from the second spacer.

11. The electric rotational machine of any one of claims 8-10, wherein the first spacer is formed by at least one tooth lamina of the first plurality of tooth laminas.

12. The electric rotational machine of claim 11, wherein the at least one tooth lamina is radially larger than other tooth laminas of the first plurality of tooth laminas.

13. The electric rotational machine of any one of claims 8-10, wherein the first spacer is formed by at least one return lamina of the plurality of return laminas.

14. The electric rotational machine of any one of claims 8-10, wherein the first spacer is formed as a first layer formed separately from the first plurality of tooth laminas and from the plurality of return laminas.

15. The electric rotational machine of claim 14, wherein the first layer is formed from an adhesive tape.

16. The electric rotational machine of any one of claims 14 and 15, wherein the first layer is adhered to at least one tooth lamina of the first plurality of tooth laminas.

17. The electric rotational machine of any one of claims 14-16, wherein the first layer is adhered to at least one return lamina of the plurality of return laminas.

18. The electric rotational machine of any one of claims 14 and 15, wherein the first layer is directly adhered to at least one return lamina of the plurality of return laminas and the first layer is directly adhered to at least one tooth lamina of the first plurality of tooth laminas.

19. The electric rotational machine of any one of claims 8-10, wherein the first spacer is disposed in a trench formed in the first plurality of tooth laminas.

20. The electric rotational machine of any one of claims 8-10 and 19, wherein the first spacer is disposed in a trench formed in the plurality of return laminas.

21. The electric rotational machine of any one of claims 8-10, 19, and 20, wherein the first spacer is formed as a strip.

22. The electric rotational machine of claim 21, wherein the strip extends transversely to the plurality of return laminas.

23. The electric rotational machine of claim 21, wherein the strip extends parallel to the first plurality of tooth laminas.

24. The electric rotational machine of any one of claims 21-23, wherein the strip is discontinuous.

25. The electric rotational machine of any one of claims 21-23, wherein the strip is continuous.

26. The electric rotational machine of any one of claims 1-25 wherein the first plurality of tooth laminas are oriented transverse to the plurality of return laminas.

27. The electric rotational machine of claim 26, wherein the first plurality of tooth laminas are oriented orthogonal to the plurality of return laminas.

28. The electric rotational machine of any one of claims 1-27, wherein the second plurality of tooth laminas are oriented transverse to the plurality of return laminas.

29. The electric rotational machine of claim 28, wherein the second plurality of tooth laminas are oriented orthogonal to the plurality of return laminas.

30. The electric rotational machine of any one of claims 1-29, wherein the first plurality of tooth laminas are stacked axially.

31. The electric rotational machine of any one of claims 1-30, wherein the plurality of return laminas are stacked circumferentially.

32. The electric rotational machine of any one of claims 1-31, wherein the plurality of return laminas are disposed radially inward of the first plurality of tooth laminas and the second plurality of tooth laminas.

33. The electric rotational machine of any one of claims 1-31, wherein the plurality of return laminas are disposed radially outward of the first plurality of tooth laminas and the second plurality of tooth laminas.

34. An electric rotational machine comprising: a rotor rotatable on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; and a stator configured to electromagnetically drive rotation of the rotor, the stator including a plurality of phases, wherein each phase of the plurality of phases comprises:at least one coil wound around the axis such that the axis extends through the at least one coil; a first flux ring including a first plurality of teeth extending around the axis such that the axis extends through the first flux ring, wherein the first flux ring is formed by a first plurality of tooth laminas; a second flux ring including a second plurality of teeth extending about the axis such that the axis extends through the second flux ring, wherein the second flux ring is formed by a second plurality of tooth laminas; a plurality of axial returns arrayed about the axis, the plurality of axial returns extending between the first flux ring and the second flux ring, wherein each axial return of the plurality of axial returns is formed by a plurality of return laminas; a first spacer forming a first gap directly radially between the first flux ring and a first axial return of the plurality of axial returns; and a second spacer forming a second gap directly radially between the second flux ring and the first axial return.

35. The electric rotational machine of claim 34, wherein the first spacer is formed separately from the second spacer.

36. The electric rotational machine of claim 34, wherein the first spacer is formed as a layer directly radially between the first plurality of tooth laminas and the plurality of return laminas.

37. The electric rotational machine of claim 36, wherein the second spacer is formed as a layer directly radially between the first plurality of tooth laminas and the plurality of return laminas.

38. The electric rotational machine of claim 34, wherein the first spacer is formed as a first standoff, the first standoff formed by at least one tooth lamina of the first plurality of tooth laminas.

39. The electric rotational machine of claim 34, wherein the first spacer is formed as a first standoff, the first standoff formed by at least one return lamina of the plurality of return laminas.

40. The electric rotational machine of claim 34, wherein the first spacer is formed as an elongate strip disposed at least partially in a first trench.

41. The electric rotational machine of claim 40, wherein the first trench is formed in at least one tooth lamina of the first plurality of tooth laminas.

42. The electric rotational machine of claim 40, wherein the first trench is formed in the plurality of return laminas.

43. The electric rotational machine of claim 40, wherein the first trench is formed at least partially in the plurality of return laminas and at least partially in at least one tooth lamina of the first plurality of tooth laminas.

44. An electric rotational machine comprising: a rotor rotatable on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; and a stator configured to electromagnetically drive rotation of the rotor, the stator including a plurality of phases, wherein each phase of the plurality of phases comprises: at least one coil wound around the axis such that the axis extends through the at least one coil; a first flux ring including a first plurality of teeth extending around the axis such that the axis extends through the first flux ring, wherein the first flux ring is formed by a first plurality of tooth laminas; a second flux ring including a second plurality of teeth extending about the axis such that the axis extends through the second flux ring, wherein the second flux ring is formed by a second plurality of tooth laminas; a plurality of axial returns arrayed about the axis, the plurality of axial returns extending between the first flux ring and the second flux ring,wherein each axial return of the plurality of axial returns is formed by a plurality of return laminas; a first transverse lamina interface formed directly radially between the first plurality of tooth laminas and the plurality of return laminas of a first axial return of the plurality of axial returns; a second transverse lamina interface formed directly radially between the second plurality of tooth laminas and the plurality of return laminas of the first axial return; and at least one spacer maintaining a first gap between the first plurality of tooth laminas and the plurality of return laminas of the first axial return at the first transverse lamina interface and the at least one spacer maintaining a second gap between the second plurality of tooth laminas and the plurality of return laminas of the first axial return at the second transverse lamina interface.

45. The electric rotational machine of claim 44, wherein the first plurality of tooth laminas are disposed transverse to the plurality of return laminas of the first axial return at the first transverse lamina interface.

46. The electric rotational machine of claim 45, wherein the first plurality of tooth laminas are disposed orthogonal to the plurality of return laminas of the first axial return at the first transverse lamina interface.

47. The electric rotational machine of any one of claims 44-46, wherein the second plurality of tooth laminas are disposed transverse to the plurality of return laminas of the first axial return at the second transverse lamina interface.

48. The electric rotational machine of claim 47, wherein the second plurality of tooth laminas are disposed orthogonal to the plurality of return laminas of the first axial return at the second transverse lamina interface.

49. The electric rotational machine of any one of claims 44-48, wherein the at least one spacer includes:a first spacer directly radially between the first plurality of tooth laminas and the plurality of return laminas of the first axial return; and a second spacer directly radially between the second plurality of tooth laminas and the plurality of return laminas of the first axial return.

50. The electric rotational machine of claim 49, wherein the first spacer is at least partially disposed in a first trench formed in the first flux ring.

51. The electric rotational machine of claim 50, wherein the first spacer is at least partially disposed in a second trench formed in the first axial return.

52. The electric rotational machine of claim 49, wherein the first spacer is at least partially disposed in a first trench formed in the first axial return.

53. The electric rotational machine of claim 49, wherein the first spacer is formed as a first layer.

54. The electric rotational machine of claim 53, wherein the first layer includes an adhesive side.

55. The electric rotational machine of claim 54, wherein the adhesive side is adhered to the first plurality of tooth laminas.

56. The electric rotational machine of claim 54, wherein the adhesive side is adhered to the plurality of return laminas of the first axial return.

57. The electric rotational machine of any one of claims 44-56 wherein the first plurality of tooth laminas are stacked axially and the plurality of return laminas of the first axial return are stacked circumferentially.

58. An electric rotational machine comprising: a rotor that rotates on an axis, the rotor comprising a plurality of magnetic sections circularly arrayed around the axis; anda stator comprising a plurality of phases, each phase of the plurality of phases comprising: at least one coil wound around the axis such that the axis extends through the at least one coil; a pair of circular arrays of teeth around the axis such that the axis extends through each circular array of teeth of the pair of circular arrays of teeth, the at least one coil of the phase located between the pair of circular arrays of teeth such that electrical energy delivered through the coil electromagnetically polarizes the teeth of the pair of circular arrays of teeth, each tooth formed from tooth laminations orientated radially with respect to the axis; a plurality of axial returns arrayed around the axis that connect a plurality of flux paths between the pair of circular arrays of teeth, the plurality of flux paths extending axially across the at least one coil, the axial returns formed from return laminas oriented axially with respect to the axis; and a plurality of transverse lamination interfaces comprising a plurality of spacers respectively maintaining a plurality of gaps, each transverse lamination interface of the plurality of transverse lamination interfaces comprising a respective gap of the plurality of gaps between the tooth laminas and the return laminas in which the tooth laminas are orientated transverse to the return laminas, the respective gap inhibiting eddy currents conduction between the tooth laminas and the axial return laminas.

59. The electric rotational machine of claim 58, wherein the tooth laminas are orientated orthogonal with respect to the return laminas at the plurality of transverse lamination interfaces.

60. The electric rotational machine of any one of claims 58 and 59, wherein the tooth laminations and the axial return laminations together form a grid pattern at the plurality of transverse lamination interfaces.

61. The electric rotational machine of any one of claims 58-60, wherein the plurality of spacers comprise a plurality of layers.

62. The electric rotational machine of claim 61, wherein the plurality of layers are respectively disposed within the plurality of gaps.

63. The electric rotational machine of claim 61, wherein the plurality of layers are respectively disposed adjacent to the plurality of gaps.

64. The electric rotational machine of any one of claims 61-63, wherein the plurality of layers comprise, for each transverse lamination interface of the plurality of transverse lamination interfaces, a respective layer disposed on the tooth laminations defining the transverse lamination interface.

65. The electric rotational machine of any one of claims 61-63, wherein the plurality of layers comprise, for each transverse lamination interface of the plurality of transverse lamination interfaces, a respective layer disposed on the return laminas defining the transverse lamination interface.

66. The electric rotational machine of any one of claims 61 and 63 , wherein the plurality of layers are adhered directly to at least one of the tooth laminas and the return laminas.

67. The electric rotational machine of any one of claims 64-66, wherein each layer of the plurality of layers is orientated orthogonal with respect to an orientation of a set of laminas on which the layer is disposed, the set of laminas formed by one of the tooth laminas and the return laminas.

68. The electric rotational machine of any one of claims 61-67, wherein the plurality of layers are located only directly between the tooth laminas and the return laminas.

69. The electric rotational machine of any one of claims 61-67, wherein the plurality of layers are disposed on the one or more coils.

70. The electric rotational machine of any one of claims 61-69, wherein, of the type of material from which the plurality of layers are made, such type of material only forms the plurality of layers and is not used to form any other part of the stator.

71. The electric rotational machine of any one of claims 58-60, wherein the plurality of spacers comprise a plurality of elongate pieces.

72. The electric rotational machine of claim 71 , wherein the plurality of elongate pieces are disposed, at least partially, within respective trenches formed in one or both of the tooth laminas and the return laminas, the respective trenches extending along the plurality of transverse lamination interfaces.

73. The electric rotational machine of any one of claims 71 and 72, wherein the plurality of elongate pieces extend orthogonal to at least one of an orientation of the tooth laminas and an orientation of the return laminas to which the respective elongate piece directly contacts along the plurality of transverse lamination interfaces.

74. The electric rotational machine of any one of claims 58-60, wherein the plurality of spacers comprise a plurality of standoff projections formed from one or both of the tooth laminas and the return laminas along the plurality of transverse lamination interfaces.

75. The electric rotational machine of claim 74, wherein the plurality of standoff projections comprise a plurality of lines respectively located along each transverse lamination interface of the plurality of transverse lamination interfaces.

76. The electric rotational machine of claim 75, wherein for each transverse lamination interface of the plurality of transverse lamination interfaces, the line is contiguous within the transverse lamination interface.

77. The electric rotational machine of claim 75, wherein for each transverse lamination interface of the plurality of transverse lamination interfaces, the line is disjointed within the transverse lamination interface.

78. The electric rotational machine of any one of claims 75-77, wherein for each transverse lamination interface of the plurality of transverse lamination interfaces, one a single standoff projection of the plurality of standoff projections is disposed within the transverse lamination interface.

79. The electric rotational machine of any one of claims 75-78, wherein for each transverse lamination interface of the plurality of transverse lamination interfaces, the line is formed from multiple laminations.

80. The electric rotational machine of any one of claims 75-78, wherein for each transverse lamination interface of the plurality of transverse lamination interfaces, the line is formed from a single lamination.

81. The electric rotational machine of any one of claims 74-80, wherein the plurality of standoff projections are formed from the tooth laminas.

82. The electric rotational machine of claim 81, wherein the plurality of standoff projections are formed only from the tooth laminas.

83. The electric rotational machine of any one of claims 74-80, wherein the plurality of standoff projections are formed from the return laminas.

84. The electric rotational machine of claim 83, wherein the plurality of standoff projections are formed only from the return laminas.

85. The electric rotational machine of any one of claims 74-80, wherein the plurality of standoff projections are formed from both of the return laminas and the tooth laminas.

86. The electric rotational machine of any one of claims 58-85, wherein the tooth laminas do not directly axially overlap with the return laminas.

87. The electric rotational machine of any one of claims 58-86, wherein each transverse lamination interface of the plurality of transverse lamination interfaces is rectangular.

88. The electric rotational machine of any one of claims 58-87, wherein each gap of the plurality of gaps is radial such that at least one tooth lamina is radially outward of other of the tooth laminas along the gap.

89. The electric rotational machine of any one of claims 58-88, wherein each gap of the plurality of gaps is radial such that at least one return lamina is radially outward of other of the return laminas along the gap.

90. The electric rotational machine of any one of claims 58-89, wherein the tooth laminas are disposed radially inward of the return laminas.

91. The electric rotational machine of any one of claims 58-89, wherein the tooth laminas are radially outward of the return laminas.

92. The electric rotational machine of any one of claims 58-91, wherein the tooth laminas form a plurality of ring segments, each ring segment of the plurality of ring segments respectively forming multiple teeth of a respective circular array of teeth.

93. The electric rotational machine of any one of claims 58-92, wherein: the pair of circular arrays of teeth comprise a first circular array of teeth and a second circular array of teeth; the plurality of transverse lamination interfaces comprising a first plurality of transverse lamination interfaces and a second plurality of transverse lamination interfaces; the first circular array of teeth and the first plurality of transverse lamination interfaces are located on first axial side of the at least one coil and the second circular array of teeth and the second plurality of transverse lamination interfaces are located on the second axial side of the at least one coil opposite the first axial side; and the plurality of axial returns respectively bridge across the at least one coil from the first plurality of transverse lamination interfaces to the second plurality of transverse lamination interfaces.

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