Rotor for axial flux motor and manufacturing method thereof

Abstract

A rotor and manufacturing method for an axial flux motor includes a rotor core having a rotor hub having a plurality of spaced fingers extending radially from the rotor hub to form magnet pockets with magnets inserted between adjacent fingers, the rotor core being formed from a plurality of layers of material arranged in a layer stack, each layer having a set of primary fibers extending in a selected direction that is different from the set of primary fiber layers of adjacent layers in the layer stack.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to, and the benefit of, U.S. Provisional Application No. 63 / 147,090, filed February 8, 2021, the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0002] The present invention relates generally to electric motors, and more particularly to axial flux motors in which a rotor and a stator are coaxially disposed. More particularly, the present invention relates to rotors for use in such axial flux motors, and to methods of manufacturing the rotors.

[0003] Various embodiments of the present disclosure will become more fully understood from the detailed description set forth below and the accompanying drawings of various embodiments of the present disclosure, in which like reference numbers may indicate identical or functionally similar elements. [Brief description of the drawings]

[0004] [Figure 1] FIG. 2 is an exploded perspective view of an axial flux motor according to the present disclosure. [Figure 2A] FIG. 2 illustrates a perspective view of an embodiment of a rotor assembly. [Figure 2B] FIG. 2B is an exploded perspective view of the rotor assembly of FIG. 2A. [Figure 2C] FIG. 2 is an enlarged perspective view of a portion of the rotor core illustrating the layered structure of the rotor core. [Figure 3A] FIG. 2 is a plan view of one layer of a rotor core illustrating a first fiber direction of the layer. [Figure 3B] FIG. 2 is an exploded view of an embodiment of a rotor core in which adjacent layers have different fiber orientations. [Figure 4A] Illustrates a method and apparatus for manufacturing the rotor assembly of FIGS. [Figure 4B]1 illustrates a mold utilized to form an embodiment of a rotor assembly described herein. [Figure 4C] 4 illustrates the insertion of a retaining ring into a mold during manufacture of the rotor assembly of FIGS. 2 and 3; [Figure 4D] 4 illustrates the insertion of magnets into a mold during manufacture of the rotor assembly of FIGS. 2 and 3; [Figure 4E] 4 illustrates the insertion of a rotor core (spider stack) into a mold during manufacture of the rotor assembly of FIGS. 2 and 3. [Diagram 5] FIG. 2 is a plan view of a rotor assembly of the present disclosure. [Figure 6A] FIG. 6 is an enlarged elevational view of a magnet within a magnet pocket of the rotor assembly of FIG. [Figure 6B] FIG. 6B is an enlarged elevational view of the magnet of FIG. 6A with a spacer positioned radially outward from the magnet. [Figure 6C] FIG. 13 is an enlarged elevation view of a grooved magnet in a grooved magnet pocket with the magnet spaced from the spider edge. [Figure 6D] FIG. 6D is an enlarged elevational view of the grooved magnet of FIG. 6C illustrating a magnet retaining member interposed between the magnet and the spider. [Figure 7] FIG. 13 is an enlarged elevational view of the wedge-shaped spider fingers of the rotor core, which allow for rectangular shaped magnets. [Figure 8] FIG. 2 is a plan view of a rotor core assembly having a spacer inserted between the magnets and the outer ring. [Figure 9A] FIG. 2 is a perspective view of another embodiment of a rotor assembly. [Figure 9B] FIG. 9B is an exploded view of the rotor assembly of FIG. 9A. [Figure 9C] FIG. 9B is a cutaway elevation view of the rotor assembly of FIG. 9A. [Figure 9D] FIG. 9B is a perspective view of the partially assembled rotor assembly of FIG. 9A. [Figure 9E] FIG. 9B is an enlarged perspective view of the connection between the magnets and fingers of the rotor assembly of FIG. 9A. [Figure 10A]FIG. 13 is a perspective view of an embodiment of a rotor assembly having stress relief spacers between each magnet and the outer ring. [Figure 10B] FIG. 10B is an exploded view of the rotor assembly of FIG. 10A. [Figure 11A] 13 is a perspective view of another embodiment of a rotor assembly having stress relief spacers between each magnet and the outer ring. FIG. [Figure 11B] FIG. 11B is an exploded view of the rotor assembly of FIG. [Figure 11C] FIG. 11B is an enlarged perspective view of the connection between the magnets and fingers of the rotor assembly of FIG. [Figure 11D] FIG. 11B is a perspective view of a connector assembly utilized in the rotor assembly of FIG. [Figure 11E] FIG. 11B is a perspective view of a connector assembly utilized in the rotor assembly of FIG. [Figure 12A] FIG. 11D is a partial assembled perspective view of another embodiment of the rotor assembly of FIG. 11C but having an alternative connector assembly. [Figure 12B] FIG. 12B is a perspective view of a connector assembly utilized in the rotor assembly of FIG. 12A. [Figure 12C] FIG. 12B is a perspective view of a connector assembly utilized in the rotor assembly of FIG. 12A. [Figure 12D] FIG. 11D is a partial assembled perspective view of another embodiment of the rotor assembly of FIG. 11C but having an alternative connector assembly. [Figure 12E] FIG. 12E is a perspective view of a connector assembly utilized in the rotor assembly of FIG. 12D. [Figure 12F] FIG. 12E is a perspective view of a connector assembly utilized in the rotor assembly of FIG. 12D. [Figure 13A] FIG. 2 illustrates a perspective view of an embodiment of a rotor assembly having trapezoidal shaped magnets and magnet pockets. [Figure 13B] FIG. 13B is a plan view of the rotor assembly of FIG. 13A. [Figure 13C] FIG. 13B is an exploded view of the rotor assembly of FIG. 13A. [Figure 14A]FIG. 2 is an exploded view of another embodiment of a rotor assembly of the present disclosure. [Figure 14B] FIG. 14B is a perspective view of the rotor assembly of FIG. 14A. [Figure 14C] FIG. 14B is a partial cut-away assembly view of the rotor assembly of FIG. 14A illustrating the cooling channels. [Figure 14D] FIG. 14B is a cutaway plan view of a rotor finger of the rotor assembly of FIG. 14A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Disclosed herein is a rotor assembly for an axial flux motor in which a rotor core is formed of multiple fiber layers stacked and bonded together. Each layer of the stack is oriented such that the primary fibers of the layer extend in a selected direction and a set of primary fibers of an adjacent fiber layer extend in a different direction. Each layer is cut to have the shape of a rotor hub having multiple radially extending, spaced apart fingers such that the stacked and bonded layers form magnet pockets between adjacent fingers. A magnet is positioned in each magnet pocket of the rotor core. In one or more embodiments, the fingers of the rotor core may be triangular or wedge shaped, thereby creating a rectangular magnet pocket for receiving a rectangular magnet. A radial spacer may be inserted into the magnet pocket radially outward from the magnet to reduce stress on the magnet, particularly stress that may be caused by a radial retaining ring. Similarly, to reduce magnet stress, each magnet may be grooved along at least its side edge where a hardening resin or offset connector in the form of a pin or blade may be utilized to center the magnet in the pocket so as to be spaced apart from the fingers. In some embodiments, the radial spacers and offset connectors may be integrally formed. In one or more embodiments, the magnet pockets may be trapezoidal in shape with fingers tapering outward so that the fingers hold radially uniform magnets within the magnet pockets. In one or more embodiments, airflow channels may be formed along the fingers and between the magnets to enhance cooling. In one or more embodiments, retention covers may be disposed on either side of the rotor core to axially secure the magnets within the pockets. In this regard, one or both covers may further include an outer radial lip that radially secures the magnets. The retention covers may include integrally formed magnet sheets and / or airflow channels.

[0006] 1, an axial-flux electric motor assembly 100 is shown. The electric motor assembly 100 includes at least one rotor assembly 110 and at least one stator assembly 112 disposed axially from one another along a motor axis 114. In the illustrated embodiment, a rotor spindle or shaft 116 extends along the axis 114 and supports the rotor assembly 110. The rotor shaft 116 may include a spindle flange 117 attached to the rotor assembly 110. The rotor shaft 116 may in turn be supported by one or more bearings 118.

[0007] Although only a single stator assembly 112 may be utilized, in the illustrated embodiment, two stator assemblies 112 a , 112 b are shown, positioned on opposite sides of the rotor assembly 110 along the axis 114 .

[0008] A motor housing 120 and opposing stator supports or end plates 122 surround the rotor assembly 110 and the one or more stator assemblies 112. In one or more embodiments, at least one end plate 122 supports the stator assembly 112 on an inner surface 123 of the end plate 122. In the illustrated embodiment, end plate 122a supports stator assembly 112a and end plate 122b supports stator assembly 112b.

[0009] Insofar as the end plate 122 supports the stator assembly 112 , the end plate 122 may include cooling mechanisms 124 positioned along an exterior surface 126 of the end plate 122 .

[0010] In one or more embodiments, the cooling mechanism 124 may form one or more coolant passages 128 along the exterior surface 126 of the end plate 122. The coolant passages 128 may be one or more cooling channels 130 formed in the exterior surface 126 of the end plate 122.

[0011] In the illustrated embodiment, a plurality of fluidly connected cooling channels 130 are illustrated and positioned to generally extend around the end plate 122 opposite the stator assembly 112 mounted to the inner surface 123 of the end plate 122. While not limited to a particular configuration, in one embodiment, the cooling channels 130 may form a star shape along the outer surface 126 to maximize cooling while allowing the fasteners 127 to secure the various motor components to the end plate 122 from the inner surface 123 without extending through the end plate 122 to the outer surface 126 of the end plate 122. In other words, threaded holes for engagement by the fasteners 127 may be formed on the inner surface 123 of the end plate 122, but the holes do not extend all the way through the end plate 122. It will be appreciated that such an arrangement minimizes the possibility of fluid inside the motor assembly 100 leaking or migrating out, or vice versa. In other embodiments, the coolant passages 128 may be formed from tubes (not shown) positioned on the outer surface 126. In yet other embodiments, the coolant passages 128 may be formed from ribs or fins (not shown) extending from the exterior surface 128, while in other embodiments, the coolant passages 128 may be coolant chambers formed between the end plate 122 and the outer plate 134. Notwithstanding the above, it will be appreciated that the cooling channels 130 formed in the exterior surface 126 of the end plate 122 may be particularly desirable to minimize the overall axial length of the electric motor assembly 100. In any event, one or more ports 125 in fluid communication with the passages 128 may be utilized to introduce and extract coolant from the cooling mechanism 124.

[0012] Each stator assembly 112 is generally formed from a stator core 138 and stator windings 140, as may be known to those skilled in the art. In this regard, the stator windings 140 may be formed from electrical wire. The present disclosure is not limited to a particular configuration of the stator assemblies 112.

[0013] 2A and 2B, and with continued reference to FIG. 1, rotor assembly 110 is generally formed with a rotor core or yoke 142 arranged to carry a plurality of magnets 144. In one or more embodiments, rotor core 142 is spider-shaped and formed from a hub 146 with fingers 148 extending radially therefrom. Fingers 148 are spaced apart from one another around the circumference of hub 146 to form magnet pockets 150 between adjacent fingers 148. In one or more embodiments, rotor assembly 110 further includes a rotor ring 152 arranged radially outward from fingers 148. In one or more embodiments, rotor ring 152 and rotor core 142 may be separate components as shown in FIGS. 1, 2A, and 2B, while in other embodiments rotor ring 152 and rotor core 142 may be integrally formed.

[0014] In one or more embodiments, the rotor core 142 is formed from a non-conductive composite material. Similarly, in one or more embodiments, the rotor ring 152 is formed from a non-conductive composite material.

[0015] 2A-2B, an embodiment of rotor assembly 110 is shown and generally described as rotor assembly 210. Rotor assembly 210 generally includes a rotor core or yoke 242 arranged to carry a plurality of magnets 244. In one or more embodiments, rotor core 242 is spider-shaped and formed from a hub 246 with fingers 248 extending radially therefrom. Fingers 248 are spaced apart from one another around the circumference of hub 246 to form magnet pockets 250 between adjacent fingers 248. Rotor assembly further includes a rotor ring 252 disposed radially outward from fingers 248. In the illustrated embodiment, rotor core 242 includes ten fingers 248 and ten magnet pockets 250, although not limited to any particular number of fingers 248 and pockets 250.

[0016] In the illustrated embodiment of rotor assembly 210, fingers 248 are generally rectangular in shape such that magnet pockets 250 are generally wedge-shaped.

[0017] Thus, in this illustrated embodiment, the magnets 244 are generally wedge-shaped, with each magnet 244 having a radially outer edge 260 that is a greater length than a radially inner edge 262, with the edges 260, 262 being joined by a side edge 264. In one or more embodiments, as best seen in FIG. 2B , at least one, and preferably each, side edge 264 of the magnets 244 includes a groove or slot 266 that extends along at least a portion of the length of the side edge 264 between the radially outer edge 260 and the radially inner edge 262. In one or more embodiments, each groove 266 extends completely between the radially outer edge 260 and the radially inner edge 262, while in other embodiments the groove 266 extends from the radially outer edge 260 and is spaced apart from the radially inner edge 262. In yet another embodiment, groove 266 is spaced from radially outer edge 260 and extends from radially inner edge 262. Finally, in another embodiment, groove 266 is formed along side edge 264 such that it is spaced from both radially outer edge 260 and radially inner edge 262.

[0018] Similarly, each finger 248 of hub 246 has a side edge 268 that extends from a proximal end 269a adjacent hub 246 to a distal end 269b at the periphery of rotor core 242. In one or more embodiments, side edge 268 of each finger may be generally smooth without any features formed there along. In one or more other embodiments, each side edge 268 of finger 248 includes a groove or slot 270 that extends along at least a portion of the length of side edge 268 between proximal end 269a and distal end 269b of finger 248.

[0019] In one or more embodiments, each groove 270 extends completely between the proximal end 269a and the distal end 269b of the finger 248, while in other embodiments, the groove 270 extends from the distal end 269b and is spaced from the proximal end 269a. In yet other embodiments, the groove 270 is spaced from the distal end 269b and extends from the proximal end 269a. Finally, in other embodiments, the groove 270 is formed along the side edge 268 and is spaced from both the distal end 269b and the proximal end 269a of the finger 248.

[0020] In one or more embodiments, rotor ring 252 is a preformed ring positioned about rotor core 242. In some embodiments, rotor ring 252 is a continuous solid ring. In this regard, rotor ring 252 may be formed of a composite material, such as a fiber material. Rotor ring 252 has a radially inner edge 276 and a radially outer edge 278, where radially inner edge 276 may abut fingers 248 when positioned about rotor core 242. In one or more embodiments, radially inner edge 276 of solid, preformed rotor ring 252 is formed, as will be appreciated, with carbon fiber material and glass fiber material each being formed from a substrate upon which the fibers are supported.

[0021] 2C, in one or more embodiments, the rotor core or yoke 242 may be formed from multiple layers 280 of fibrous material arranged in a stack 282 or "book," as shown. Each fiber layer 280 may be a material having a set of primary fibers.

[0022] With reference to FIG. 3A and continuing with reference to FIG. 2C, layers 280 of fibrous material forming stack 282 are illustrated in more detail. Specifically, as shown, each layer 280 may be characterized as having at least a primary set of fibers 284 extending in a first direction, as generally indicated by arrow 286. The fibers 284 need not be limited to a particular type of fiber and may include glass fiber, carbon fiber, or other fibers known in the art. In one or more embodiments, the fibers may be short or long fibers, so long as the primary fibers are generally aligned in separate directions. Likewise, the material carrying the fibers need not be limited to a particular type of material. In one or more embodiments, the material may be a fabric or even a woven material. In other embodiments, the material may be a polymeric material, such as a plastic sheet. Each layer 280 may further include one or more secondary sets of fibers 287, such as may be arranged in a cross weave. However, as best illustrated in FIG. 3B , it is the primary set of fibers that is utilized in the assembly of the stack 282 of the rotor core 242. In one or more embodiments, each layer 280 may be formed by punching the layer 280 from a sheet of fiber material. In other embodiments, each layer 280 may be cut from the sheet of fiber material, such as by precision laser cutting. Although not required, in one or more embodiments, the sheet of fiber material may be pre-impregnated with a bonding material or adhesive for use in the manufacturing hub 246. Similarly, in one or more embodiments, to aid in manufacturing as described herein, designation symbols, such as arrows 286, may be stamped or otherwise imprinted on the layer 280 at the time of cutting or punching to indicate the orientation of the primary set of fibers 284.

[0023] In FIG. 3B, a partial exploded view of the stack 282 is shown. In either case, as the individual plies 280 are formed in the stack 282, the plies 280 are rotated through a predetermined angle such that adjacent plies 280 have a primary set of fibers 284 extending in different directions. It has been found that by arranging the plies as described, in an ordered orientation as described herein, the performance life of the rotor assembly 210 can be significantly enhanced. Thus, as shown, a first ply 280a has a primary set of fibers 284 extending in a first direction as indicated by arrow 286a, and an adjacent second ply 280b has a primary set of fibers 284 extending in a second direction as indicated by arrow 286b. Similarly, a third ply 280c has a primary set of fibers 284 extending in a third direction as indicated by arrow 286c, and an adjacent fourth ply 280d has a primary set of fibers 284 extending in a fourth direction as indicated by arrow 286d. In a preferred embodiment, this rotational sequence of plies 280 continues as stack 282 is formed. Thus, a fifth ply 280e adjacent to a fourth ply 280d is thus disposed such that a primary set of fibers 284 in the fifth ply 280e extend in a fifth direction, as indicated by arrow 286e.

[0024] While it is desirable to maximize the number of directions 286 of the layers 280 in the stack 282, it will be understood that in one or more embodiments, the multiple layers 280 are arranged at least such that a set of fibers 284 extend in at least three different directions, with successive or adjacent layers extending in different directions.

[0025] In one or more embodiments of the stack 282 having three directions 286, successive layers are rotated 60 degrees relative to one another. It will be appreciated that the number of fingers 248 may determine the degree of rotation of each layer 280. Thus, in one or more embodiments, the number of different directions 286 for a set of fibers 284 is equal to half the number of fingers 248, unless the fibers are of approximately uniform cross-section or the fibers are not of uniform cross-section (such that fibers extending in one direction do not have the same material properties as those extending 180 degrees in the opposite direction). Thus, in other embodiments, the number of different directions 286 for a set of fibers 284 is equal to the number of fingers 248. It will be appreciated that in the embodiment illustrated in FIG. 3B, five directions 286 are illustrated based on the ten fingers 248 of the rotor core 242. Thus, a sixth layer (not shown) adjacent to the fifth layer 280e would have sixth layer fibers 284 extending in a first direction, as indicated by arrow 286a. In one or more embodiments of a stack 282 having five orientations 286, successive layers are rotated 18 degrees from one another. In one or more embodiments, successive layers are rotated 60 degrees from one another. Although a uniform angular rotation of successive layers is used in the examples, it will be understood that the present disclosure is not limited to any particular angular rotation of successive layers, if any.

[0026] It will be appreciated that during assembly of rotor core 242, each ply 280 may be machine cut, stamped, or otherwise formed from a web or bolt of fibrous material. For each ply 280, in one or more embodiments, the direction of the primary set of fibers 284 is marked or otherwise indicated by reference points such that each ply 280 may be oriented as described above relative to successive adjacent plies. It will also be appreciated that each individual ply 280 may be formed such that when combined into stack 282, various three-dimensional shapes or features, such as slots 270, may be present.

[0027] While rotor ring 252 (see FIGS. 2A and 2B ) is preferably a solid preformed ring positioned about rotor core 242, in one or more other embodiments rotor ring 252 may be formed from layers of fibrous material formed into a ring stack as generally described above with respect to rotor core 242. In such a case, in a preferred embodiment, multiple successive rings may be cut from the fibrous material and formed into a stack. The ring layers are preferably continuous to ensure uniform application of hoop stress around the rings, which is particularly desirable given the high rotational speeds rotor assembly 210 experiences during use. Successive ring layers may be oriented at an angle relative to one another such that the fiber direction is offset from adjacent layers of fibrous material, as described. In one or more embodiments, layer 280 may be cut to include rings such that the rings and fingers of layer 280 are integrally formed.

[0028] In FIG. 4A, a method 400 of manufacturing the rotor assembly 210 is illustrated. As described above, the first step 402 of the method 400 is to cut a plurality of plies 280 from a fibrous material. The fibrous material is selected to have at least primary fibers extending in an identifiable primary fiber direction. In one or more embodiments of step 402, once the plies 280 are cut, they may be marked with a label, printed designator, or other device indicating the orientation of the primary fibers. In one or more embodiments, the material is pre-impregnated with an adhesive or bonding material. In step 404, the plurality of plies 280 are arranged in a stack 282 such that the fingers 148 are aligned. In one or more embodiments of step 404, each ply is axially rotated relative to an adjacent ply such that the primary fibers 284 of one ply 280 are angularly offset from the primary fibers 284 of the adjacent ply 280.

[0029] In one or more embodiments, the material forming each layer 280 is a fiberglass material having glass fibers forming the primary fibers. In other embodiments, the material forming each layer 280 is a carbon fiber material having carbon fibers forming the primary fibers. In other embodiments, other types of fibers may be utilized in the material forming each layer 280.

[0030] In step 406, once the stack 282 is formed, heat and / or pressure may be applied to the stack 282 to activate the adhesive or bonding material to form the composite rotor core 242. In this regard, minimal heat and / or pressure may be applied only to the extent necessary to initially secure the individual layers 280 together, but not to allow the pre-impregnated adhesive or bonding material to emerge from the stack 282. In one or more embodiments, a mold 300, such as that shown in FIGS. 4C-4E, may be utilized to apply such initial heat and / or pressure to the stack 282 to form the rotor core 242. Notably, in the prior art, rotor assemblies, and in particular rotor cores, are generally formed of milled metal or milled composite materials, as opposed to forming the rotor core 242 as described herein. In any event, the mold 300 includes a mold cavity 301 having reliefs or other orientation features 302 to allow the stack 282 to be positioned within the mold 300.

[0031] In addition to utilizing the mold 300 to form the rotor core 242, the mold 300 may also be utilized to assemble together the other components of the rotor assembly 210, namely, the rotor ring 252 and the magnets 244. In this regard, the mold 300 may also include the reliefs, protrusions, or other orientation features 302 referred to above, such as the illustrated magnet sheet 302a for receiving and positioning the magnets, and the rotor core sheet 302b for receiving and aligning the stack 282 of the rotor core 242. In particular, the magnet sheet 302a may be a raised relief or a recess relative to the rotor core sheet 302b, depending on the features desired for the rotor assembly 210 (such as cooling channels, discussed below). In any event, in addition to initially bonding the layers 280 of the stack 282 together to form the rotor core 242, as described, the mold 300 may be used to activate an adhesive or bonding material to bond the rotor ring 252 and the magnets 244 to the rotor core 242. In particular, in one or more embodiments, the orienting features 302 are positioned such that the magnets 244 are spaced apart from the fingers 248, leaving a gap such that the magnets 244 are not in physical contact with the fingers 248. As will be appreciated, as the bonding material is exposed during the forming steps below, the bonding material will flow into this gap and maintain the spaced apart relationship once fabrication is complete, thereby minimizing stress on the magnets during use of the rotor assembly 210.

[0032] 4C , in step 408, a solid pre-formed rotor ring 252 may be positioned within the mold 300. In one or more embodiments of step 408, the rotor ring 252 is pre-heated prior to inserting it into the mold 300. Similarly, the mold 300 may be pre-heated to receive the rotor ring 252. It will be appreciated that the mold 300 includes a mold cavity 301 having an outer diameter 306 positioned to receive and accommodate the rotor ring 252.

[0033] In step 410, as illustrated in FIG. 4D, the magnets 244 are inserted into the mold 300. Each magnet 244 may be aligned on or within the magnet sheet 302a. In one or more embodiments, the magnets 244 are preheated prior to inserting them into the mold 300.

[0034] Finally, in step 412, the stack 282 of layers 280 is inserted into the mold 300, as illustrated in FIG. 4E. As mentioned above, in one or more embodiments, the stack 282 may be at least partially preassembled by applying heat or pressure sufficient to secure the layers 280 together prior to insertion into the mold 300 for step 412. In other embodiments of step 412, the stack 282 may simply be inserted into the mold 300 without this preassembly step. In this regard, it will be appreciated that unlike the rotor ring 252 and magnets 244, the stack 282 is preferably not preheated so as not to reveal the pre-impregnated adhesive / bonding material prior to insertion into the mold 300. While the above is a preferred order for inserting the components of the rotor assembly 210 into the mold 300, the manufacturing method is not limited to any particular order. In particular, if the rotor ring 252 is formed of a stack of fibrous material as described above, the rotor ring 252 is positioned in the mold 300 at the same time as the stack 282, and in such cases, the rotor ring 252 is not preheated.

[0035] In any event, once the rotor assembly 210 components are inserted into the mold 300 in step 414, the mold 300 may be closed and actuated to apply heat and / or pressure as known in the art. It should be appreciated that heated adhesive / bonding material is at least partially expressed from the stack 282 to engage the magnets with the rotor ring, bond the magnets within the magnet pockets, and bond the rotor ring to the distal ends of the rotor fingers. In this regard, all of the magnets are bonded to the rotor core simultaneously, which significantly reduces the time period required to manufacture the rotor assembly 210. By bonding all of the magnets to the rotor core simultaneously, the shortcomings of the prior art are overcome, particularly those found in the prior art where each magnet is separately inserted and secured into a magnet pocket.

[0036] At step 416, rotor assembly 210 may be cured in the mold or removed from the mold for curing, as known in the art. It will be appreciated that upon curing, in one or more embodiments, the hardened bonding material may secure magnets 244 in spaced apart relationship relative to fingers 248 of rotor core 242.

[0037] 5, another embodiment of the rotor assembly 110 of FIG. 1 is shown and generally designated as rotor assembly 310. The rotor assembly 310 is generally formed from a rotor core or yoke 342 arranged to carry a plurality of magnets 344. In one or more embodiments, the rotor core 342 is spider-shaped and formed from a hub 346 with fingers 348 extending radially therefrom. The fingers 348 are spaced apart from one another around the circumference of the hub 346 to form magnet pockets 350 between adjacent fingers 348. The rotor assembly 310 further includes a rotor ring 352 disposed radially outward from the fingers 348. In one or more embodiments, the rotor ring 352 and the rotor core 342 may be separate components as shown in FIG. 5, while in other embodiments the rotor ring 352 and the rotor core 342 may be integrally formed.

[0038] In one or more embodiments, the rotor core 342 is formed from a non-conductive composite material. Similarly, in one or more embodiments, the rotor ring 352 is formed from a non-conductive composite material.

[0039] In the illustrated embodiment of rotor assembly 310, fingers 348 are generally wedge shaped and magnet pockets 350 are generally rectangular in shape. Thus, in this illustrated embodiment, magnets 344 are generally rectangular in shape. This arrangement is desirable because it reduces the machining required for magnets 344 and allows the magnets to be more easily inserted into magnet pockets 350. In this regard, this arrangement is more easily manufactured from the methods described above with respect to Figures 2, 3, and 4 than conventional methods because conventional machining methods result in significant stresses on the proximal ends of fingers 348 during manufacture, whereas rotor assembly 310 formed in a mold, such as mold 300 described above, substantially eliminates such stresses during manufacture.

[0040] 6A-6D with continued reference to FIG. 5, the magnets 344 may be inserted into the magnet pockets 350 in a variety of arrangements. In FIG. 6A, the magnets 344 are inserted into the magnet pockets 350 between adjacent fingers 348 of the rotor core 342. The rotor ring 352 is positioned radially outward from the magnets 344. The magnets 344 include a radially outer edge 360, a radially inner edge 362, and side edges 364 joining the outer edge 360 ​​and the inner edge 362. In one or more embodiments, one or both of the radially outer edge 360 ​​and the radially inner edge 362 may be arcuate in shape. In the embodiment of FIGS. 6A-6D, the side edges 364 are parallel, thereby creating a generally rectangular shape for the magnets 344.

[0041] 6B shows spacers or wedges 345 disposed in magnet pockets 350 between rotor ring 352 and magnets 344. It has been found that if magnets 344 were to directly contact rotor ring 352, undesirable stresses would be created at the corners of magnets 344 where they abut rotor ring 352. By using spacers 345, stresses created within rotor assembly 310 at these points are significantly reduced. Spacers 345 may be formed of a variety of materials. In one or more embodiments, spacers 345 may be formed of a metal or conductive material, while in other embodiments, spacers 345 may be formed of a non-conductive material such as a composite material or polymer. In still other embodiments, spacers 345 may be formed of the same or similar magnetic material as magnets 344.

[0042] In FIG. 6C, the magnets 344 are positioned in the magnet pocket 350 so that they are spaced apart from the fingers 348 that define the magnet pocket 350 such that an open space or gap 347 (as defined by the fingers 348 and the hub 346) is formed around each side of the magnets 344 and the rotor core 342. This allows the adhesive / bonding material that is exposed during the molding process described above to flow into the open space 347 to better bond to the magnets 344. In one or more embodiments, to further enhance bonding, one or more edges 364 of the magnets 344 may include a groove or recess 343a into which the adhesive / bonding material may flow. Alternatively, or in addition, one or more edges 368 of the fingers 348 may also include a groove or recess 343b into which the adhesive / bonding material may flow. Any of the grooves 343 as illustrated in FIG. 6C may extend fully or partially as generally described above with respect to FIG. 2B. In any event, it will be appreciated that when rotor assembly 310 having the features illustrated in Figure 6C is manufactured in manufacturing process 400 as described above, magnets 344 are positioned within mold 300 such that magnets 344 are spaced from the edges of fingers 348 and from abutment with rotor hub 346 (see gap 347), thereby allowing for uniform flow of bonding material therebetween. This reduces stress on magnets 244 during high speed revolutions per minute (RPM) operation of rotor assembly 310.

[0043] In FIG. 6D , a connector or fastening mechanism 353, such as a pin or blade, may be inserted into adjacent grooves 343a, 343b of magnet 344 and finger 348, respectively, thereby securing magnet 344 in magnet pocket 350 but spaced apart from finger 348 of rotor core 342.

[0044] 7 is an enlarged elevational view of the wedge-shaped spider fingers 348 of the rotor core 342 shown in FIG. 5. To maximize the total surface area of ​​the magnets 344 on the periphery of the rotor core 342, the proximal ends 348a of the fingers 348 are substantially narrower than the distal ends 348b of the fingers 348, as illustrated by their respective widths W1 and W2. Forming the rotor core 342 by conventional machining methods results in undesirable stresses on the proximal ends 348a of the fingers 348 during machining. Thus, in one or more embodiments, such rotor cores 342 are formed by stacking multiple layers of fiber material 280 as described above, eliminating the need for machining.

[0045] Referring to Figure 8, similar to Figure 5, an elevational view of the rotor assembly 310 is shown with a spacer 345 inserted into the magnet pocket 350 between the magnets 344 and the rotor ring 352. As explained above with respect to Figure 6B, the spacer 345 absorbs stresses that would otherwise be transferred from the rotor ring 352 during operation of the rotor assembly 310. It has been found that such stresses can reduce the operational life of the magnets 344 and affect the electrical output of the axial flux motor during operation. An opening 305 can be formed in the central hub 346 to receive the rotor shaft (see Figure 1).

[0046] 9A-9E illustrate another embodiment of a rotor assembly 500 according to the present disclosure. In FIG. 9A, the rotor assembly 500 includes a spider-shaped rotor core 502 having a central hub 504 formed along a rotor axis 503 with fingers 506 extending radially therefrom. An opening 505 may be formed in the central hub 504 for receiving the rotor shaft (see FIG. 1). The fingers 506 are spaced apart from one another around the circumference of the hub 504 to form magnet pockets 508 between adjacent fingers 506. Each magnet pocket 508 is positioned to receive a magnet 510. A rotor ring 514 is positioned radially outward from the fingers 506. In the illustrated embodiment, the rotor core 502 includes ten fingers 506 and ten magnet pockets 508, although not limited to a particular number of fingers 506 and pockets 508. In one or more embodiments, the magnets 510 can be positioned within the magnet pockets 508 such that they are spaced apart from adjacent fingers 506 and / or central hub 504 to form gaps 507 therebetween.

[0047] In one or more embodiments, rotor core 502 may be formed from multiple fiber layers bonded together in a fiber layer stack, as generally described above, while in other embodiments rotor core 502 may be formed in other manners.

[0048] FIG. 9B is an exploded view of rotor assembly 500 , in which it can be seen that each magnet 510 may be supported within magnet pocket 508 by a connector 513 .

[0049] In the illustrated embodiment, the fingers 506 are generally rectangular in shape and form a magnet pocket 508 that is generally wedge-shaped. Thus, in this illustrated embodiment, the magnets 510 are generally wedge-shaped, with each magnet 510 having a radially outer edge 512a that is a greater length than a radially inner edge 512b, the radial edges 512a, 512b being joined by a side edge 516. The radially outer edge 512a and / or the radially inner edge 512b may be arcuate. In one or more embodiments, at least one, and preferably each, magnet side edge 516 includes a magnet groove or slot 518 that extends along at least a portion of the length of the side edge 516 between the radially outer edge 512a and the radially inner edge 512b. In the illustrated embodiment, each groove 518 extends completely between the radially outer edge 512a and the radially inner edge 512b. The magnet groove 518 is not limited to a particular shape, but in some embodiments may be arcuate or rectangular in cross section.

[0050] To reduce stress on the magnets 510, the outer corners 519 of each magnet 510 may also be rounded.

[0051] Similarly, each finger 506 has a side edge 520 that extends from a proximal finger end 506a adjacent the hub 504 to a distal finger end 506b at the periphery of the rotor core 502. In the illustrated embodiment, each side edge 520 of the finger 506 includes a finger groove or slot 522 that extends along at least a portion of the length of the side edge 520 between the proximal finger end 506a and the distal finger end 506b. The finger grooves 522 are not limited to a particular shape, but in some embodiments may be arcuate or rectangular in cross-section. Additionally, in one or more embodiments, the finger grooves 522 have the same cross-sectional shape as the magnet grooves 518 such that they are mirror images of one another.

[0052] The fingers 506 may be characterized as having a thickness Tf, and the magnets 510 may be characterized as having a thickness Tm. In one or more embodiments, the finger thickness Tf and the magnet thickness Tm are the same. In yet other embodiments, the finger thickness Tf and the magnet thickness Tm may differ such that cooling channels may be formed in the rotor assembly 500.

[0053] In one or more embodiments, rotor ring 514 is a pre-formed ring positioned about rotor core 502. Rotor ring 514 has a radially inner edge 526 and a radially outer edge 528, and radially inner edge 526 may abut fingers 506 when rotor ring 514 is positioned about rotor core 502.

[0054] Connector 513 is positioned to engage each of finger grooves 522 and magnet groove 518. Connector 513 is not limited to a particular shape, but while finger grooves 522 and magnet groove 518 are each semicircular in cross section, connector 513 could be a round pin as shown. Similarly, if finger grooves 522 and magnet groove 518 are each rectangular in cross section, connector 513 could be a square pin or a rectangular blade.

[0055] 9C, 9D, and 9E, the rotor assembly 500 is partially assembled, but the rotor ring 514 is removed in FIGS. 9D and 9E, thereby illustrating the positioning of the magnets 510 within the magnet pockets 508. Each magnet 510 is positioned within the magnet pocket 508 such that the finger grooves 522 align with the magnet grooves 518, allowing the connectors 513 to be inserted therebetween. In one or more embodiments, the magnets 510 are positioned within the magnet pockets 508 such that they are spaced apart from adjacent fingers 506 such that a gap 530 is formed between each magnet edge 516 and each finger side edge 520. It has been found that by maintaining the magnets 510 in a spaced apart relationship relative to the fingers 506, stresses on the magnets 510 are reduced, particularly during the high RPMs experienced by the rotor assembly 500 during operation. Whether the magnet 510 abuts or is spaced from the finger 506, the connector 513 is inserted into the aligned grooves 522, 518 to secure the magnet 510 within the magnet pocket 508. When the gap 530 is formed, the connector 513 is also utilized to maintain the spaced apart relationship between each magnet 510 and the adjacent fingers 506 that form the finger pocket 508 in which the magnet 510 is positioned.

[0056] 9A-9E are shown with connector 513, in other embodiments, connector 513 may be eliminated. In such cases, it will be understood that during manufacture, adhesive or bonding material may flow into finger grooves 522 and magnet grooves 518, as well as any gaps 530, and upon curing and setting of the adhesive or bonding material, magnet 510 is secured in pocket 508 by the set material.

[0057] 10A and 10B illustrate another embodiment of a rotor assembly 600. In this embodiment, the rotor assembly 600 includes a spider-shaped rotor core 602 having a central hub 604 formed along a rotor axis 603 with fingers 606 extending radially therefrom. Although not required, in this embodiment, the rotor core 602 is shown having a plurality of fiber layers 605 formed together in a fiber layer stack 609, as generally described above. The fingers 606 are spaced apart from one another around the circumference of the hub 604 to form magnet pockets 608 between adjacent fingers 606. Each magnet pocket 608 is positioned to receive a magnet 610. A rotor ring 614 is positioned radially outward from the fingers 606. In addition, an outer radial element 611 is positioned as a spacer between each magnet 610 and the rotor ring 614 in much the same manner as described above with respect to FIGS. 6B and 8.

[0058] Each magnet 610 has a radially outer edge 612a of greater length than a radially inner edge 612b, with the radial edges 612a, 612b being joined by a side edge 616. In one or more embodiments, at least one, and preferably each, magnet side edge 616 includes a magnet groove or slot 618 extending along at least a portion of the length of the side edge 616. The magnet groove 618 is not limited to a particular shape, but in some embodiments may be arcuate or rectangular in cross-section.

[0059] Similarly, each finger 606 has a side edge 620 that extends from a proximal finger end 606a adjacent the hub 604 to a distal finger end 606b at the periphery of the rotor core 602. In the illustrated embodiment, the finger side edge 620 is smooth, but in other embodiments may include finger grooves or slots, as illustrated in FIG.

[0060] In one or more embodiments, the rotor ring 614 is a pre-formed ring that is positioned about the rotor core 602. The rotor ring 614 has a radially inner edge 626 and a radially outer edge 628, and when the rotor ring 614 is positioned about the rotor core 602, the radially inner edge 626 abuts the outer radial element 611.

[0061] A connector 613 is positioned to seat in each magnet groove 618. In this embodiment, connector 613 may be semicircular in cross-section, with an arcuate surface that engages groove 618 and a flat surface adjacent smooth edge 620 of finger 606.

[0062] The outer radial element 611 is elongated at a first end 615 and a second end 617 and is generally arcuate to engage an inner radial edge 626 of the rotor ring 614, as shown particularly in FIG. 10B. One or both ends 615, 617 may also include a notch 619 that allows the connector 613 to pass therethrough. In one or more embodiments, in addition to securing the magnet 610 as described above, the connector 613 may also secure the outer radial element 611 within the magnet pocket 608 between the magnet 610 and the rotor ring 614.

[0063] 11A and 11B illustrate another embodiment of an assembled and disassembled rotor assembly 700, respectively. In this embodiment, as shown in FIG. 11A, the rotor assembly 700 includes a spider-shaped rotor core 702 formed along a rotor axis 703 and having a central hub 704 from which fingers 706 extend radially. The fingers 706 are spaced apart from one another around the circumference of the hub 704 to form magnet pockets 708 between adjacent fingers 706. Each magnet pocket 708 is positioned to receive a magnet 710. A rotor ring 714 is positioned radially outward from the fingers 706. Each magnet 710 is supported within the magnet pocket 708 by at least one connector assembly 723 positioned between the magnet 710 and the rotor ring 714.

[0064] In one or more embodiments, rotor core 702 may be formed from multiple fiber layers bonded together in a fiber layer stack, as generally described above, while in other embodiments rotor core 702 may be formed in other manners.

[0065] 11B and continuing to FIG. 11A , each magnet 710 has a radially outer edge 712a and a radially inner edge 712b, the radial edges 712a, 712b being joined by a side edge 716. In one or more embodiments, at least one, and preferably each, magnet side edge 716 includes a magnet groove or slot 718 extending along at least a portion of the length of the side edge 716. The magnet groove 718 is not limited to a particular shape, but in some embodiments may be arcuate or rectangular in cross section. In the illustrated embodiment, the magnet radial side edges 716 are substantially parallel such that each magnet 710 is generally rectangular in shape. Additionally, as illustrated, one or both radial edges 712a, 712b may be arcuate.

[0066] Similarly, each finger 706 has side edges 720 that extend from a proximal finger end 706a adjacent the hub 704 to a distal finger end 706b at the periphery of the rotor core 702. Each finger 706 is generally triangular or wedge shaped, as discussed above with respect to FIG. 7. As such, the proximal end 706a of the finger 706 is substantially narrower in width than the distal end 706b of the finger 706, as also illustrated above in FIG. 7. It will be appreciated that because each finger 706 is wedge shaped, when disposed about the rotor core 702, each set of adjacent wedge shaped fingers 706 that define a magnet pocket 708 have opposing edges 720 that are substantially parallel such that the magnet pocket 708 formed by adjacent fingers 706 is substantially rectangular to receive a substantially rectangular magnet 710.

[0067] In the illustrated embodiment, each side edge 720 of the fingers 706 includes a finger groove or slot 722 that extends along at least a portion of the length of the side edge 720 between the proximal finger end 706a and the distal finger end 706b. The finger grooves 722 are not limited to a particular shape, but in some embodiments may be arcuate or rectangular in cross section. Additionally, in one or more embodiments, the finger grooves 722 have the same cross-sectional shape as the magnet grooves 718 such that they are mirror images of one another.

[0068] Each connector assembly 723 includes an outer radial element 711 extending such that the two connectors 713 are parallel to one another. The connectors 713 are positioned to engage opposing finger grooves 722 and magnet grooves 718 of the magnet pocket 708. The connectors 713 are not limited to a particular shape, although the opposing finger grooves 722 and magnet grooves 718 are each semicircular in cross section as shown in FIG. 11A, while the connectors 713 could be round pins as shown. Similarly, if the opposing finger grooves 722 and magnet grooves 718 are each rectangular in cross section, the connectors 713 could be square pins or rectangular blades.

[0069] 11C and 11D, in the illustrated embodiment, two connectors 713a, 713b of the connector assembly 723 are arranged to extend from the outer radial element 711. More specifically, each outer radial element 711 includes two spaced apart, substantially parallel connectors 713a, 713b extending from the outer radial element 711, thereby forming the connector assembly 723. Each outer radial element 711 is elongated having a first end 715 and a second end 717, and an inner surface 719 and an outer surface 721, and in some embodiments, one or both surfaces 719, 721 may be generally arcuate. In such an embodiment, the arcuate outer surface 721 may be arranged to engage an inner radial edge 726 of the rotor ring 714, as specifically shown in FIG. 11B. The first and second connectors 713a, 713b of the connector assembly 723 are parallel to one another and extend from an inner surface 719 of the outer radial element 711. In this embodiment, the first and second connectors 713a, 713b are spaced inwardly from the first and second ends 715, 717, respectively, of the outer radial element 711.

[0070] 11E, rotor assembly 700 is shown partially assembled but with rotor ring 714 removed, thereby illustrating the positioning of magnets 710 within magnet pockets 708. Each magnet 710 is positioned within magnet pocket 708 such that finger groove 722 is aligned with magnet groove 718. In one or more embodiments, magnets 710 are positioned within magnet pocket 708 such that they are spaced apart from adjacent fingers 706 such that a gap 730 is formed between each magnet edge 716 and each finger side edge 720. It has been found that by maintaining magnets 710 in a spaced apart relationship relative to fingers 706, stress on magnets 710 is reduced, particularly during the high RPMs experienced by rotor assembly 700 during operation. Regardless of whether the magnet 710 is adjacent to the finger 706 or spaced apart from the finger 706, a set of connectors 713a, 713b of a connector assembly 723 are inserted into aligned grooves 722, 718 to secure the magnet 710 within the magnet pocket 708. When the gap 730 is formed, the connectors 713a, 713b are also utilized to maintain the spaced apart relationship between each magnet 710 and the adjacent fingers 706 that form the finger pocket 708 in which the magnet 710 is positioned.

[0071] As best seen in Figures 11A and 11C, in the illustrated embodiment, the length of each outer radial element 711 is selected to cover the outer radial edge 712 of the magnet 710 and a portion of the distal finger ends 706b of two adjacent fingers 706 that form the magnet pocket 708.

[0072] 12A, 12B, and 12C illustrate another embodiment of rotor assembly 700 and connector assembly 723 shown in FIGS. 11A-11D, but where connector 713 is a square pin for engaging with rectangular shaped finger grooves 722 and magnet grooves 718.

[0073] 12C and 12D illustrate an alternative embodiment of the rotor assembly 700 and connector assembly 723 shown in Figures 12A and 12B, but where each finger 706 includes a notch 725 formed in a side edge 720 of the distal finger end 706b. In such case, the length of each outer radial element 711 is selected such that the connector assembly 725 is received in the opposing notch 725 and fits between the opposing fingers 706 that form the magnet pocket 708. In this embodiment, first and second connectors 713a, 713b are adjacent first and second ends 715, 717, respectively, of the outer radial element 711.

[0074] 13A-13D illustrate another embodiment of a rotor assembly 800. In FIGS. 13A and 13B, the rotor assembly 800 includes a spider-shaped rotor core 802 formed along a rotor axis 803 and having a central hub 804 with fingers 806 extending radially therefrom. In one or more embodiments, the rotor core 802 may be formed of multiple fiber layers 807 compressed together in a fiber layer stack 809 as generally described above, while in other embodiments, the rotor core 802 may be formed in other ways, such as by machining. An opening 805 may be formed in the central hub 804 to receive the rotor shaft (see FIG. 1). The fingers 806 are wedge or triangular shaped and are spaced apart from one another about the circumference of the hub 804 to form trapezoidally shaped magnet pockets 808 between adjacent fingers 806. Each magnet pocket 808 is positioned to receive a trapezoidally shaped magnet 810. Rotor ring 814 is disposed radially outward from fingers 806 .

[0075] 13C is an exploded view of rotor assembly 800 in which it can be seen that each magnet 810 may be supported within magnet pocket 808 by at least one connector 813. In other embodiments of rotor assembly 800, connector 813 may be eliminated, as generally described above.

[0076] Each magnet 810 has a radially outer edge 812a and a radially inner edge 812b, which are joined by a side edge 816. The radially inner edge 812b of the magnet 810 has a longer length than the radially outer edge 812a, such that the magnet 810 is trapezoidal in shape. In one or more embodiments, at least one, and preferably each, magnet side edge 816 includes a magnet groove or slot 818 that extends along at least a portion of the length of the side edge 816. The magnet groove 818 is not limited to a particular shape, but in some embodiments may be arcuate or rectangular in cross section. In the illustrated embodiment, each radial side edge 816 of the magnet is angled or tapered inwardly from the radially inner edge 812b. Additionally, as illustrated, one or both radial edges 812a, 812b may be arcuate.

[0077] In one or more embodiments, the magnets 810 may be positioned within the magnet pockets 808 so as to be spaced apart from adjacent fingers 806 and / or central hub 804 so as to form gaps therebetween, as generally described above.

[0078] Each finger 806 has a side edge 820 that extends from a proximal finger end 806a adjacent the hub 804 to a distal finger end 806b at the periphery of the rotor core 802. Each finger 806 is generally triangular or wedge shaped. As such, the proximal end 806a of the finger 806 is substantially narrower in width than the distal end 806b of the finger 806. In the illustrated embodiment, the side edge 820 of each finger 806 is trapezoidal in shape, angling outwardly from the proximal end 806a to define a magnet pocket 808 that is wider at the base of the magnet pocket 808 adjacent the hub 804 and narrower adjacent the distal end 806b of the finger 806. In the illustrated embodiment, the finger side edge 820 is smooth, although in other embodiments, it may include finger grooves or slots, as illustrated in FIG. 9.

[0079] A connector 813 is positioned to seat in each magnet groove 818. In this embodiment, connector 813 may be semi-circular in cross-section, with an arcuate surface that engages groove 818 and a flat surface adjacent smooth edge 820 of finger 806.

[0080] It will be appreciated that the magnets 810 are trapezoidal in shape and that the magnet pockets 808 are likewise trapezoidal in shape such that each magnet pocket 808 is wider at the proximal end 808a and narrower at the distal end 808b (as opposed to the rectangular shaped magnet pockets shown in Figures 11A-11E).

[0081] In any event, because of their trapezoidal shape, the magnets 810 may be secured to the magnet pockets 808 by the fingers 806 without the need for connectors 813 or rotor rings 813 to secure the magnets 810 within the magnet pockets 808. Thus, as explained above, in some embodiments of the rotor assembly 800, the connectors 813 and even the magnet grooves 818 may be eliminated. Similarly, for this reason, the rotor rings 814 may be eliminated.

[0082] While the magnets 810 need not be secured within the magnet pockets 808, in some embodiments the rotor ring 814 may be provided to strengthen the rotor assembly 800, particularly to provide support to the fingers 806. In such embodiments, the magnets 810 may be sized such that the radially outer edge 812a of the magnets 810 is spaced from the radially inner edge 826 of the rotor ring 814 to create a radial gap between the magnets 810 and the rotor ring 814 and reduce the possibility of the magnets 810 being stressed by the rotor ring 814 during operation. In other embodiments, the rotor ring 814 may abut the radially outer edge 812a of the magnets 810.

[0083] 14A is an exploded view of another embodiment of a rotor assembly 900, in which the rotor assembly 900 includes a spider-shaped rotor core 902 having a central hub 904 with fingers 906 extending radially therefrom, disposed about an axis 903. In one or more embodiments, the rotor core 902 may be formed of a plurality of fiber layers 907 bonded together in a fiber layer stack 909, as generally described above, while in other embodiments, the rotor core 902 may be formed in other manners. The fingers 906 are spaced apart from one another about the circumference of the hub 904 to form magnet pockets 908 between adjacent fingers 906. Each magnet pocket 908 is positioned to receive a magnet 910. A retaining cover assembly 915 having a first plate 917a and a second plate 917b may be utilized to axially surround and axially secure the rotor core 902 and magnets 910 relative to one another.

[0084] Each plate 917 is circular and includes an outer radial edge 919, an outer surface 921, and an inner surface 923. The retaining cover assembly 915 may be utilized in one or more of the rotor assembly embodiments described above to provide axial support to the rotor core 902 and magnets 910 along the axis 903. In some embodiments of the rotor assembly 900, a rotor ring as described above may be disposed radially outward of the fingers 906 and cooperate with the retaining cover assembly 915. In this regard, in some embodiments, the opposing plates 917a, 917b may also axially surround the rotor ring to provide axial support to the rotor ring. In other embodiments, the outer radial edge 919 of the plates 917a, 917b abuts the inner radial edge of the rotor ring. In the embodiment shown in FIG. 14A, each plate 917 includes an outer radial lip 925 integrally formed on the inner surface 923 of the plate 917 adjacent the outer radial edge 919. In such an embodiment, the outer radial lip 925 of each plate 917 may replace the rotor ring described in other embodiments above. In this regard, as best seen in FIG. 14B, when the rotor assembly 900 is assembled, the retaining cover assembly 915 completely surrounds the rotor core 902 and magnets 910 both axially and radially, and specifically, the radial lips 925 of the two opposing plates 917a, 917b are adjacent to one another.

[0085] In one or more embodiments, rotor assembly 900 includes internal rotor cooling channels 927 formed to allow air to flow between magnets 910. In some embodiments, cooling channels 927 may be formed by providing a sheet 929 on an inner surface 923 of one or both plates 917a, 917b.

[0086] In embodiments of rotor assembly 900, each magnet 910 may be supported within magnet pocket 908 in a variety of different ways as generally described above, whether by the shape of connectors or fingers 907, or by rotor rings, or even by radial lips 925, and embodiments of rotor assembly 900 having internal rotor cooling channels 927 are not limited in this respect.

[0087] Each magnet 910 has a radially outer edge 912a and a radially inner edge 912b that are joined by a side edge 916. In one or more embodiments, at least one, and preferably each, magnet side edge 916 includes a magnet groove or slot 918 that extends along at least a portion of the length of the side edge 916.

[0088] Similarly, each finger 906 has a side edge 920 that extends from a proximal finger end 906a adjacent the hub 904 to a distal finger end 906b at the periphery of the rotor core 902. Each side edge 920 of the fingers 906 may include a finger groove or slot (not shown in FIG. 14A but described above in various embodiments) that extends along at least a portion of the length of the side edge 920 between the proximal finger end 906a and the distal finger end 906b.

[0089] A connector (not shown in FIG. 14A, but in various embodiments, as described above) can be positioned to engage the opposing finger grooves and magnet groove 918.

[0090] Formed on the inner surface 923 of the plate 917 are one or more raised sheets 929 that support the rotor core 902. In one or more embodiments, a plurality of spaced apart raised sheets 929 are formed about the axis 903. Each raised sheet 929 is spaced from an adjacent sheet 929 to partially define a cooling channel 927 therebetween. In the illustrated embodiment, a plurality of wedge-shaped raised sheets 929 are formed on the inner surface 923 of the plate 917 about the axis 903 and extend radially outward toward the outer radial edge 919, thereby defining a plurality of cooling channels 927. In this embodiment, the raised sheets 929 are also spaced from the outer radial edge 919 of the plate 917. The rotor core 902 is positioned on the raised seat 929 such that the central hub 904 engages the raised seat 929 and the fingers 906 are aligned with the cooling channels 927 such that each finger 906 extends along the cooling channel 927. Thus, in some embodiments, each raised seat 929 is formed to extend radially outwardly below the outer diameter of the central hub 904 when the central hub 904 is received in the plate 917. In any event, when the rotor core 902 abuts the raised seat 929 as described, the fingers 906 are spaced from the inner surface 923 of the plate 917 such that the cooling channels 927 continue to extend outwardly along the length of the fingers 906. In one or more embodiments, the seat 929 is wedge shaped and may be positioned around an opening 933 formed in the plate 917.

[0091] In one or more embodiments, as best seen in FIGS. 14C and 14D , the magnet thickness Tm is greater than the finger thickness Tf, so that the cooling channels 927 defined along the fingers 906 will extend between successive magnets 910 when the magnets 910 are positioned radially outward of the raised sheet 929 in the magnet pocket 908 formed between adjacent fingers 906. In such embodiments, it will be appreciated that the cooling channels 927 extend along a portion of each side edge 916 of the magnets 910. If the plate 917 includes a radial lip 925, each magnet 910 may be positioned and secured radially between the raised sheet 929 and the radial lip 925. In such a case, the magnets 910 abut against the inner surface 923 of the plate 917. When both plates 917a, 917b include the raised seats 929 as described, the rotor assembly 900 defines four cooling channels 927 around each magnet 910. Finally, in one or more embodiments, the cooling channels 927 extend radially. Alternatively, or in addition, the cooling channels may also be circumferentially extending channels 931 formed in the seats 929. Such circumferentially extending channels 931 may interconnect the radially extending cooling channels. Although not shown, in other embodiments, additional seats 929 may be formed on the interior surface 923 of the plate 917 adjacent the distal end 906b of each finger to provide additional support to the fingers 906.

[0092] Thus, a rotor assembly for an axial flux motor has been described. In one or more embodiments, the rotor assembly generally includes a rotor hub having a plurality of radially extending, spaced apart fingers with adjacent fingers forming magnet pockets therebetween, a magnet positioned in each magnet pocket of the rotor core, and a rotor ring extending around a periphery of the rotor core, the rotor core including a plurality of fiber layers formed together in a fiber layer stack, each fiber layer having a set of primary fibers extending in a selected direction, the set of primary fibers of adjacent fiber layers extending in different directions. In other embodiments, the rotor assembly may include a rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers with adjacent fingers forming magnet pockets therebetween, a magnet positioned in each magnet pocket of the rotor core, and a rotor ring extending around a periphery of the rotor core, the rotor core including a plurality of material layers formed together in a material layer stack. Similarly, an axial flux motor has been described. In one or more embodiments, an axial flux motor may include at least one stator assembly disposed along an axis, a rotor assembly disposed along the axis and spaced from the at least one stator assembly, the rotor assembly comprising a rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers with adjacent fingers forming magnet pockets therebetween, magnets positioned in each magnet pocket of the rotor core, and a rotor ring extending around a periphery of the rotor core, the rotor core comprising a plurality of fiber layers formed together in a fiber layer stack, each fiber layer having a set of primary fibers extending in a selected direction and a set of primary fibers of adjacent fiber layers extending in a different direction.In another embodiment, a rotor assembly generally includes a rotor core having a rotor hub with a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, and a magnet positioned in each magnet pocket of the rotor core, the rotor core comprising a plurality of fiber layers formed together in a fiber layer stack, each fiber layer comprising a material having a set of primary fibers extending in a selected direction, the sets of primary fibers of adjacent fiber layers extending in different directions. In yet another embodiment, a rotor assembly may include a rotor core having a rotor hub with a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, and a magnet positioned in each magnet pocket of the rotor core, the rotor core comprising a plurality of fiber layers formed together in a fiber layer stack. In yet another embodiment, a rotor assembly may include a rotor core having a rotor hub with a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, a magnet positioned in each magnet pocket of the rotor core, a rotor ring extending around a periphery of the rotor core, and a spacer positioned radially outward of each magnet between the magnet and the rotor ring. In yet other embodiments, a rotor assembly may include a rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, magnets positioned in each magnet pocket of the rotor core, and a rotor ring extending around a periphery of the rotor core, each magnet having a radially outer edge and a radially inner edge, the radial edges joined by side edges, each side edge having a groove formed therein along at least a portion of a length of the side edge.In yet other embodiments, a rotor assembly may include a rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers; magnets positioned within each magnet pocket of the rotor core, each magnet having a radially outer edge and a radially inner edge, the radial edges being joined by side edges, each side edge having a groove formed along at least a portion of a length of the side edge; a rotor ring extending around a periphery of the rotor core; and a hardened bonding material between each finger and an adjacent magnet side edge, the hardened bonding material being disposed in the grooves of the adjacent magnets. In yet another embodiment, a rotor assembly may include a rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core, each finger side edge having a finger groove formed therein along at least a portion of the length of the finger side edge; magnets positioned in each magnet pocket of the rotor core, each magnet having a radially outer edge and a radially inner edge, the radial edges being joined by side edges of the magnet, each side edge having a magnet groove formed therein along at least a portion of the length of the side edges of the magnet, at least one finger groove of the fingers aligning with at least one magnet groove of the magnet; a rotor ring extending around a periphery of the rotor core; and a connector inserted into the aligned finger grooves and magnet grooves.In yet another embodiment, a rotor assembly may include a rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at the periphery of the rotor core, magnets positioned within each magnet pocket of the rotor core, each magnet having a radially outer edge and a radially inner edge, the radial edges being joined by a magnet side edge, and a rotor ring extending around the periphery of the rotor core, the magnet side edges being spaced from the finger side edges on each side of each magnet. In yet another embodiment, a rotor assembly includes a rotor core having a rotor hub with a plurality of radially extending, spaced apart, wedge-shaped fingers forming magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core, the finger side edges of adjacent fingers forming the magnet pockets being parallel to one another, each finger side edge having a finger groove formed therein along at least a portion of the length of the finger side edge, and a magnet groove located within each magnet pocket of the rotor core. the magnets may include magnets attached to the magnets, each magnet having a radial outer edge and a radial inner edge, the radial edges joined by magnet side edges that are parallel to one another, each magnet side edge having a magnet groove formed therein along at least a portion of a length of the magnet side edge, at least one finger groove of the finger aligning with at least one magnet groove of the magnet; and a connector assembly adjacent the radial outer edge of each magnet, each connector assembly including an outer radial element from which extends a first connector spaced from a second connector, the first and second connectors being parallel to one another.In yet other embodiments, a rotor assembly may include a rotor core having a rotor hub having a plurality of radially extending, spaced apart, wedge-shaped fingers forming magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core, and a magnet positioned in each magnet pocket of the rotor core, each magnet having a radially outer edge of a first width and a radially inner edge of a second width, the radial edges being joined by magnet side edges, the first width being less than the second width, and the magnets being trapezoidal in shape. In yet another embodiment, the rotor assembly may include a rotor core having a rotor hub with a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core, a magnet positioned within each magnet pocket of the rotor core, each magnet having a radially outer edge and a radially inner edge, the radial edges being joined by a magnet side edge, and a cooling channel formed along at least one finger between adjacent magnets. In yet another embodiment, the axial-flux motor may include at least one stator assembly disposed along a primary axis, a rotor assembly disposed along the primary axis and spaced apart from the at least one stator assembly, and a cooling mechanism on which the at least one stator assembly is supported, the cooling mechanism comprising a plate having an outer surface and an inner surface, the stator assembly attached to the inner surface, and a plurality of fluidly connected cooling channels formed in the outer surface.In yet another embodiment, an axial-flux motor may include at least one stator assembly disposed along a primary axis, a rotor assembly disposed along the primary axis and spaced apart from the at least one stator assembly, and a cooling mechanism on which the at least one stator assembly is supported, the cooling mechanism comprising a plate having an exterior surface and an interior surface, the stator assembly extending from the stator assembly and attached to the interior surface by fasteners that engage the interior surface of the plate but are spaced apart from the exterior surface of the plate.

[0093] For any of the previously described embodiments, the rotor assembly may include any one of the following elements, either alone or in combination with each other. The rotor core comprises a hub having a rotor core periphery and having a plurality of fingers extending radially from the hub, each finger having a proximal end adjacent the hub and a distal end adjacent the rotor core periphery, the plurality of fingers being circumferentially spaced around the hub such that the fingers are spaced apart from one another to form magnetic pockets between adjacent fingers.

[0094] The multiple layers of material each have a set of primary fibers extending in a selected direction.

[0095] The cooling mechanism includes a plate having an exterior surface and an interior surface, with a plurality of fluidly connected cooling channels formed in the exterior surface.

[0096] The set of primary fibers includes glass fibers.

[0097] The set of primary fibers includes carbon fibers.

[0098] The rotor core is spider shaped.

[0099] The magnet side edges are spaced from the finger side edges on each side of the magnet.

[0100] The magnet radially inner edge is spaced from the rotor hub.

[0101] The fasteners that attach the stator assembly extend only partially into the plate.

[0102] A plate to which the stator assembly is attached by fasteners extending from the stator assembly and engaging the inner surface of the plate but spaced from the outer surface of the plate.

[0103] Each connector assembly engages the magnet such that parallel first and second connectors of the connector assembly extend into the aligned magnet and finger grooves, and a radially outer element of the connector assembly abuts a radially outer edge of the magnet.

[0104] Each connector assembly covers only a portion of the adjacent fingers that form the magnet pocket.

[0105] Cooling channels formed along each finger between adjacent magnets.

[0106] The cooling channels extend radially.

[0107] 1. A retaining cover assembly having a first plate axially spaced from a second plate, each plate being circular and including an outer radial edge, an outer surface, and an inner surface, at least one plate including spaced apart sheets formed on the inner surface of one of the plates, the spaced apart sheets at least partially forming cooling channels.

[0108] The rotor core is formed from a hub having radially extending fingers spaced apart about the circumference of the hub to define magnet pockets between adjacent fingers.

[0109] The rotor assembly further includes a rotor ring disposed radially outward from the fingers.

[0110] At least 10 fingers and at least 10 magnetic pockets.

[0111] The plurality of fingers are each rectangular in shape and the plurality of magnet pockets are each wedge shaped.

[0112] The plurality of fingers are each wedge shaped and the plurality of magnet pockets are rectangular shaped.

[0113] Each magnet has a radially outer edge of a first length and a radially inner edge of a second length that is less than the first length.

[0114] Each magnet has a radially outer edge of a first length and a radially inner edge of a second length that is longer than the first length.

[0115] Each magnet has an outer radial edge of a first length and an inner radial edge of a second length that is the same as the first length.

[0116] Each magnet has a side edge that extends from a radially outer edge to a radially inner edge of the magnet.

[0117] A groove extending along at least a portion of the length of a side edge of the magnet between the radially outer and inner edges of the magnet.

[0118] The groove extends completely between the radially outer and inner edges of the magnet.

[0119] The groove extends from the radially outer edge and is spaced from the radially inner edge of the magnet. The groove extends from the radially inner edge and is spaced from the radially outer edge of the magnet.

[0120] The groove is spaced from both the radially outer edge and the radially inner edge of the magnet.

[0121] A groove extending along at least a portion of the length of the side edge of the finger between the proximal and distal ends of the finger.

[0122] The groove extends completely between the proximal and distal ends of the finger.

[0123] A groove extends from a distal end and is spaced from the proximal end of the finger.

[0124] The groove extends from the proximal end of the finger and is spaced from the distal end.

[0125] The grooves are spaced from both the distal and proximal ends of the fingers.

[0126] Grooves along both sides of a magnet.

[0127] A groove along each side edge of a finger.

[0128] The grooves are rectangular or square in shape and the connectors are blades.

[0129] The groove is semicircular and the connector is a round pin.

[0130] A spacer positioned radially between the outer radial edge of the magnet and the outer ring.

[0131] Each magnet has a separate spacer positioned radially between the outer radial edge of the magnet and the outer ring.

[0132] A plurality of spacers positioned between the outer radial edge of the magnets and the outer ring.

[0133] The spacer includes a spacer body.

[0134] The spacer body is arcuate in shape.

[0135] The spacer further includes a connector extending radially inward from the spacer body.

[0136] The spacer further includes spaced apart connectors extending radially inwardly from the spacer body.

[0137] The spaced connectors are parallel.

[0138] The grooves on adjacent finger ends are parallel.

[0139] The grooves on the radially extending edges of the magnet are parallel.

[0140] An integrally formed rotor ring and rotor core, the integrally formed rotor ring and rotor core including a plurality of radially extending fingers spaced apart from one another around the outer periphery of a hub and extending to a ring disposed around the core, adjacent fingers forming magnet pockets therebetween.

[0141] Each material layer in the material layer stack is formed with a plurality of radially extending fingers spaced apart from one another around the outer periphery of the hub and extending to a ring disposed about the core, adjacent fingers forming magnetic pockets therebetween.

[0142] A rotor ring disposed radially outward from the fingers.

[0143] A rotor ring disposed radially outward from the spacer.

[0144] The rotor ring is integrally formed with the fingers.

[0145] The rotor ring is a continuous ring.

[0146] The rotor ring has a radially inner edge and a radially outer edge, the radially inner edge adjacent the distal ends of the fingers.

[0147] The rotor ring is formed with a radially inner edge of a first material and a radially outer edge of a second material.

[0148] The first material is fiberglass and the second material is carbon fiber.

[0149] Each finger has a proximal width adjacent a proximal end of the finger and a distal width adjacent a distal end of each finger, the distal width being greater than the proximal width.

[0150] Each magnet pocket narrows radially outward.

[0151] The inner radial edge of each magnet is longer than the outer radial edge of each magnet.

[0152] An inner radial edge of each magnet is adjacent a proximal end of a finger and an outer radial edge of each magnet is adjacent a distal end of a finger.

[0153] Each magnet pocket is in the shape of an inverted trapezoid, and each magnet is in the shape of a trapezoid and is positioned to be received in the inverted trapezoid shaped pocket.

[0154] Each fibrous layer has a set of primary fibers that extend in a selected direction, with the sets of primary fibers in adjacent fibrous layers extending in different directions.

[0155] A rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, and a magnet positioned in each magnet pocket of the rotor core.

[0156] The rotor core comprises a plurality of fiber layers formed together in a fiber layer stack, each fiber layer including a material having a set of primary fibers extending in a selected direction, with the sets of primary fibers of adjacent fiber layers extending in different directions.

[0157] a rotor core having a rotor hub having a plurality of radially extending, spaced apart fingers forming magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core;

[0158] A magnet positioned in each magnet pocket of a rotor core, each magnet having a radially outer edge and a radially inner edge, the radially inner edges being bounded by magnet side edges.

[0159] A plurality of layers of material arranged in a layer stack, each layer having a set of primary fibers extending in a selected direction that is different from the set of primary fiber layers of an adjacent layer in the layer stack.

[0160] Each magnet side edge is spaced from each finger side edge to form a gap between each magnet side edge and the finger side edge.

[0161] A connector, wherein at least one of the side edges of the magnet or fin includes a groove formed therein along at least a portion of the length of the side edge, and the connector is inserted into the groove to secure the magnet within the magnet pocket.

[0162] A rotor ring that extends around the periphery of the rotor core.

[0163] A spacer positioned radially outward of each magnet between the magnet and the rotor ring.

[0164] A radially extending cooling channel formed along at least one finger between adjacent magnets.

[0165] A radially outer edge of each magnet has a first width and a radially inner edge of each magnet has a second width, the first width being less than the second width such that each magnet is trapezoidally shaped, and each radially extending spaced apart fingers forming the magnet pocket are wedge shaped to form a corresponding trapezoidally shaped magnet pocket for receiving the trapezoidally shaped magnet.

[0166] The finger side edges of adjacent fingers that define the magnet pockets are parallel to one another and the magnet side edges of each magnet are parallel to one another.

[0167] Each finger side edge has a finger groove formed therein along at least a portion of the length of the finger side edge, and each side edge has a magnet groove formed therein along at least a portion of the length of the magnet side edge, and at least one finger groove of a finger aligns with at least one magnet groove of a magnet.

[0168] Cooling channels formed along each finger between adjacent magnets.

[0169] Each magnet has a magnet thickness and each finger has a finger thickness, the magnet thickness being greater than the finger thickness.

[0170] A plurality of spaced apart sheets, the sheets being wedge shaped and positioned around an opening formed in the plate in which the sheets are formed such that cooling channels extend radially from the center of the plate.

[0171] The rotor core abuts the plates such that the rotor hub engages the seats and each magnet abuts an inner surface of the plate.

[0172] Each plate further includes an outer radial lip on its inner surface.

[0173] Thus, a method of manufacturing a rotor for an axial flux motor is described. The method generally includes disposing a plurality of fiber layers in a fiber layer stack, each fiber layer having a set of primary fibers extending in a selected direction that is different from the set of primary fiber layers of adjacent fiber layers in the fiber layer stack, inserting a preformed rotor ring into a mold, inserting a plurality of magnets into the mold within the rotor ring, inserting the fiber layer stack into the mold, and actuating the mold to express a bonding material from the fiber layer stack and bond the rotor ring and the magnets to the fiber layer stack. In another embodiment, the method may generally include disposing a plurality of material layers in a layer stack, each layer having a set of primary fibers extending in a selected direction that is different from the set of primary fiber layers of adjacent layers in the layer stack, inserting a preformed rotor ring into the mold, inserting a plurality of magnets into the mold within the rotor ring, inserting the fiber layer stack into the mold, and actuating the mold to express a bonding material from the layer stack and bond the rotor ring and the magnets to the layer stack. In yet another embodiment, a method may include cutting a plurality of plies from a material having a primary set of fibers aligned in a first direction, and arranging the plies in a ply stack, each ply having a primary set of fibers extending in a selected direction that is a different direction than adjacent plies in the ply stack.

[0174] For any of the embodiments described above, the method may include any one of the following, either alone or in combination with each other.

[0175] Applying heat and pressure to the layer stack to expose the bonding material from the stack and bond the layers together.

[0176] Inserting a preformed rotor ring into a mold, inserting a number of magnets into the mold within the rotor ring, inserting a layer stack into the mold, and actuating the mold to expose bonding material from the layer stack to bond the rotor ring and magnets to the layer stack.

[0177] Preheat the rotor ring before inserting it into the mold.

[0178] Preheat the magnet before inserting it into the mold.

[0179] While various embodiments have been shown and described, it will be understood that the disclosure is not limited to such embodiments, but includes all modifications and variations as would be apparent to one skilled in the art. It is therefore to be understood that the disclosure is not intended to be limited to the particular forms disclosed, but rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.

Claims

1. 1. A rotor assembly for an axial flux motor, comprising: a rotor core having a rotor hub formed about a rotor axis and having a plurality of spaced apart fingers extending radially from the rotor hub to form magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core; a magnet positioned in each magnet pocket of the rotor core, each magnet having a radially outer edge and a radially inner edge joined by a radially extending magnet side edge, the magnet side edge of each magnet being spaced a length of the magnet side edge from the fingers that define the magnet pocket; For each magnet, at least one finger side edge having a radially extending finger groove formed therein along at least a portion of a length of the at least one finger side edge; at least one magnet side edge having a magnet groove formed therein along at least a portion of a length of the at least one magnet side edge; A rotor assembly in which each magnet groove of a magnet disposed in a magnet pocket is aligned parallel to but spaced apart from each adjacent finger groove of a finger forming said magnet pocket in the same plane, a gap is formed between each magnet side edge and each adjacent finger side edge within said magnet pocket over the length of each magnet side edge and finger side edge, and each finger side edge and each magnet side edge are in a spaced-apart offset relationship with each other.

2. A rotor assembly as described in claim 1, further comprising hardened bonding material disposed within each aligned finger groove and magnet groove and the gap therebetween.

3. Further comprising an elongated offset connector disposed between each finger side edge and an adjacent magnet side edge; 2. The rotor assembly of claim 1, wherein the offset connectors are radially inserted into the aligned finger grooves and magnet grooves to maintain the magnet side edges in a spaced apart relationship relative to adjacent finger side edges while securing magnets within magnet pockets.

4. The rotor assembly of claim 1 , further comprising a rotor ring extending around a periphery of the rotor core.

5. The rotor assembly of claim 4 , further comprising a spacer positioned radially outward of each magnet between the magnet and the rotor ring.

6. 2. The rotor assembly of claim 1, wherein each magnet has a magnet thickness and each finger has a finger thickness, each magnet thickness being equal to or greater than each finger thickness, so as to define a radially extending cooling channel formed along at least one finger between adjacent magnets.

7. 2. The rotor assembly of claim 1, wherein the radially outer edge of each magnet has a first width and the radially inner edge of each magnet has a second width, the first width being less than the second width such that each magnet is trapezoidal in shape and each radially extending spaced apart fingers forming a magnet pocket are wedge shaped to form a corresponding trapezoidally shaped magnet pocket for receiving the trapezoidally shaped magnet.

8. A rotor assembly for an axial flux motor, comprising: a rotor core having a rotor hub formed about a rotor axis and having a plurality of spaced apart fingers extending radially from the rotor hub to form magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core; a magnet positioned in each magnet pocket of the rotor core, each magnet having a radially outer edge and a radially inner edge joined by a radially extending magnet side edge; a first elongated connector interposed between the magnet side edge and the finger side edge at one magnet side edge of the magnet, and a second elongated connector interposed between the magnet side edge and the finger side edge at the other magnet side edge of the magnet; the first elongated connector and the second elongated connector are parallel to each other; A rotor assembly wherein the finger side edges of adjacent fingers forming a magnet pocket are parallel to one another and the magnet side edges of each magnet are parallel to one another.

9. A rotor assembly for an axial flux motor, comprising: a rotor core having a rotor hub formed about a rotor axis and having a plurality of spaced apart fingers extending radially from the rotor hub to form magnet pockets between adjacent fingers, each finger having two finger side edges extending from a proximal finger end adjacent the rotor hub to a distal finger end at a periphery of the rotor core; a magnet positioned in each magnet pocket of the rotor core, each magnet having a radially outer edge and a radially inner edge joined by a radially extending magnet side edge, the magnet side edge of each magnet being spaced a length of the magnet side edge from the fingers that define the magnet pocket; each magnet side edge having a magnet groove formed therein along at least a portion of the length of said magnet side edge, at least one finger groove of said finger aligning with at least one magnet groove of said magnet; each magnet groove of a magnet disposed in a magnet pocket is aligned parallel to but spaced apart from a finger side edge of a finger forming said magnet pocket, a gap is formed between each magnet side edge and each adjacent finger side edge in said magnet pocket over the length of each magnet side edge and finger side edge, and each finger side edge and adjacent magnet side edge are in a spaced offset relationship with each other; a hardened bonding material disposed in the gap between the magnet groove of the magnet side edge and the finger side edge aligned with the magnet side edge.

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