Synchronous reluctance motor having a stator including stacked laminations and method of manufacturing same

Abstract

The electric motor includes a plurality of structural rings defining a plurality of stator teeth. A tooth section is formed from a stack of lamination strips disposed within each stator tooth of the plurality of stator teeth. The stack of lamination strips is disposed between adjacent ones of the plurality of structural rings. A bobbin is disposed surrounding each stator tooth. A winding section is disposed surrounding each stator tooth and around the bobbin, respectively. The winding sections are coupled to each other to define a plurality of stator poles configured to be selectively energized. An outer ring is disposed around the outer periphery of the plurality of stator teeth. The outer ring defines a stator core and includes the winding section within a stator cavity defined between the outer ring and the inner periphery of the plurality of structural rings.

Description

[Technical Field]

[0001] The present invention relates generally to electric motors, and more particularly to synchronous reluctance motors having a series of stacked tooth laminations connected together to form a continuous stator. Furthermore, a separate bobbin and winding section can be attached to each tooth of the formed stator. The winding sections can also be joined together to form the stator winding. The stator can be overmolded so that an overmolding material covers and insulates the individual teeth and winding sections. [Background technology]

[0002] An electric motor typically includes a stator and a rotor, the stator containing windings that can be energized to create electromagnetic fields that interact with the rotor. The interaction between the electromagnetic fields of the stator and rotor generates an electromotive force that causes the rotor to rotate relative to the stator. Summary of the Invention

[0003] According to a first aspect of the present disclosure, an electric motor includes a plurality of structural rings defining a plurality of stator teeth. A tooth section is formed from a stack of lamination strips disposed within each stator tooth of the plurality of stator teeth. The stack of lamination strips is disposed between adjacent ones of the plurality of structural rings. A bobbin is disposed surrounding each stator tooth. A winding section is disposed surrounding each stator tooth and around the bobbin, respectively. The winding sections are coupled to each other to define a plurality of stator poles configured to be selectively energized. An outer ring is disposed around the outer periphery of the plurality of stator teeth. The outer ring defines a stator core, and the winding section is contained within a stator cavity defined between the outer ring and the inner periphery of the plurality of structural rings.

[0004] According to another aspect, a motor includes a plurality of tooth segments, each of which includes stacked tooth laminations forming a core portion and a tooth portion, a bobbin slidably disposed to surround the tooth portion of the stacked tooth laminations, and a winding section disposed around the bobbin, wherein each tooth segment is coupled with two adjacent tooth segments to form a ring with the plurality of inwardly extending tooth segments, and the winding sections of the plurality of tooth segments are coupled to one another to define a plurality of stator poles configured to be selectively energized.

[0005] According to another aspect, a method for forming a stator for an electric motor includes placing a bottom structural ring in a die, placing layers of stacked tooth lamination pieces on the bottom structural ring, arranging interrupted structural rings between adjacent layers of the stacked tooth lamination pieces in an alternating configuration, placing a top structural ring on the top layer of the stacked tooth lamination pieces to form a laminated stator, removing the laminated stator from the die, and placing a bobbin assembly on each tooth of the laminated stator to define a segmented stator winding. Each bobbin assembly includes a bobbin member and a pre-wound winding section. The method further includes placing an outer ring around the segmented stator windings and the laminated stator, and overmolding the laminated stator and the segmented stator windings with an overmolding material.

[0006] According to another aspect, a method of forming a stator for an electric motor includes forming a plurality of laminated tooth segments and disposing a bobbin assembly over a tooth of each corresponding laminated tooth segment of the plurality of laminated tooth segments to define a plurality of stator segments. The bobbin assembly includes a bobbin member and a winding section. The method further includes combining the plurality of stator segments to form a pre-wound stator core, attaching a winding bracket to the winding section of the pre-wound stator core to form a stator winding of the pre-wound stator core, and overmolding the pre-wound stator core with an overmold material.

[0007] According to another aspect, a method of forming a rotor for an electric motor includes forming steel laminations by removing a reluctance section from each lamination, stacking the steel laminations to form a rotor body with the reluctance sections arranged to define a reluctance air gap within the rotor body, positioning opposing ends on the rotor body to enclose the reluctance air gap, and overmolding the rotor structure with an overmold material, the opposing end caps preventing the overmold material from entering the reluctance air gap.

[0008] These and other aspects, objects, and features of the present disclosure will be understood and appreciated by those skilled in the art upon review of the following description, claims, and accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of an electric motor incorporating one aspect of the stator and rotor configuration described herein. [Figure 2] 2 is a schematic cross-sectional view of the electric motor of FIG. 1 taken along line II-II. [Figure 3] FIG. 1 is a perspective view of a stator incorporating an outer ring disposed around the periphery of the stator teeth. [Figure 4] 4 is a partially exploded perspective view of the stator of FIG. 3, with the stator separated from the overmold. FIG. [Figure 5] FIG. 5 is an exploded perspective view of the stator of FIG. 4. [Figure 6] FIG. 6 is a schematic perspective view showing the assembly of the stator teeth of the stator of FIG. 5 using structural rings and stacked tooth laminations. [Figure 7] 5 is a top perspective view of a stator core of the stator of FIG. 5; FIG. 5 is a side perspective view of a stack of tooth laminations positioned between adjacent structural rings to form the stator of FIG. 2; [Figure 8] FIG. 8 is an exploded perspective view of the stator core of FIG. 7. [Figure 9]FIG. 10 is a schematic diagram illustrating the assembly of stator teeth of a stator core using structural rings and stacked tooth laminations. [Figure 10] FIG. 10 is a partially exploded view of a stator incorporating a plurality of pre-wound tooth segments, with the stator separated from the overmold. [Figure 11] FIG. 11 is an exploded perspective view of the stator of FIG. 10. [Figure 12] FIG. 12 is an exploded perspective view of the stator core shown in FIG. [Figure 13] FIG. 11 is a perspective view of a pre-wound tooth segment of the stator of FIG. [Figure 14] FIG. 14 is an exploded perspective view of the pre-wrapped tooth segment of FIG. 13. [Figure 15] FIG. 1 is a perspective view of a rotor incorporating a reluctance air gap within the rotor body. [Figure 16] FIG. 16 is an exploded perspective view of the rotor of FIG. 15. [Figure 17] FIG. 17 is a cross-sectional view of the stator of FIG. 15 taken along the line XVII-XVII. [Figure 18] FIG. 18 is a cross-sectional view of the stator of FIG. 15 taken along line XVIII-XVIII. [Figure 19] 1 is a schematic flow diagram illustrating a method of forming a stator for an electric motor. [Figure 20] 1 is a schematic flow diagram illustrating a method of forming a stator for an electric motor. [Figure 21] 1 is a schematic flow diagram illustrating a method of forming a stator for an electric motor. DETAILED DESCRIPTION OF THE INVENTION

[0010] While detailed embodiments of the present disclosure are disclosed herein as necessary, it should be understood that the disclosed embodiments are merely exemplary of the present invention, which may be embodied in various and alternative forms. The drawings do not necessarily depict detailed designs, and some schematic diagrams may be exaggerated or reduced in size to illustrate general functions. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art how to use the present invention in various forms.

[0011] For purposes of this description, the terms "up," "down," "right," "left," "rear," "front," "vertical," "horizontal," and their derivatives refer to the concepts in the orientation shown in FIGS. 1-18. However, it is understood that the concepts may assume various alternative orientations, unless expressly stated to the contrary. It is also understood that the specific devices and processes illustrated in the accompanying drawings and described in the following specification are merely exemplary embodiments of the inventive concepts defined in the appended claims. Accordingly, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered limiting, unless the claims expressly state otherwise.

[0012] The illustrated embodiment primarily pertains to a combination of method steps and apparatus components for an electric motor having an overmolded stator formed with pre-wound winding sections attached to the stator teeth and an overmolded rotor having a hollow reluctance air gap contained between the outer laminations. Accordingly, while conventional symbols are used in the drawings to indicate apparatus components and method steps where appropriate, only specific details pertinent to understanding the disclosed embodiments are shown so as not to obscure the disclosure with details that will be readily apparent to those skilled in the art having the benefit of this description. Furthermore, like numerals in the description and drawings represent like elements.

[0013] As used herein, the term "and / or," when used to list more than one item, means that any one of the listed items can be used alone, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C.

[0014] As used herein, relational terms such as first and second, upper and lower, etc., are used solely to distinguish one entity or action from another and do not necessarily require or imply any actual relationship or order between such entities or actions. Terms such as "comprises," "comprising," or other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements, and may include other elements not expressly listed or other elements inherent in such process, method, article, or apparatus. An element preceded by "comprising" does not, unless further constraints exist, exclude the presence of other identical elements in a process, method, article, or apparatus that includes the element.

[0015] As used herein, the term "about" means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not, and need not be, exact, but may be approximate and / or larger or smaller, as appropriate, to reflect tolerances, conversion factors, rounding, measurement error, and the like, as well as other factors known to those of ordinary skill in the art. When the term "about" is used in describing a value or the endpoint of a range, the disclosure should be understood to include the specific value or endpoint referred to. Regardless of whether "about" is stated at the endpoint of a numerical value or range within this specification, that endpoint is intended to include both embodiments: one modified by "about" and one not modified by "about." Furthermore, it is understood that the endpoints of each range are significant both in relation to the other endpoint and independently of the other endpoint.

[0016] As used herein, the terms "substantial," "substantially," and variations thereof are intended to indicate that a stated characteristic is equal to or approximately equal to a value or description. For example, a "substantially flat" surface is intended to indicate a surface that is flat or nearly flat. Furthermore, "substantially" is intended to indicate that two values ​​are equal or approximately equal. In some embodiments, "substantially" may refer to values ​​that are within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0017] As used herein, the terms "the," "a," or "an" mean "at least one" and should not be limited to "only one" unless expressly stated to the contrary. Thus, for example, reference to "a component" includes embodiments having two or more such components, unless the context clearly indicates otherwise.

[0018] 1-18 , the numeral 10 generally refers to a stator 10 incorporated within an electric motor 12, the stator 10 having one or more windings 14 located on teeth 16 of the stator 10. The windings 14 are energized to generate a magnetic field that rotates a rotor 18 disposed relative to the stator 10. The windings 14 are typically energized by a controller that manages the supply of power to one or more phases of the windings 14. Depending on the configuration of the electric motor 12, the rotor 18 can be located inside an inner periphery 20 of the stator 10 or outside an outer periphery 22 of the stator 10. Generally, configurations described herein are directed to a rotor 18 that rotates inside the inner periphery 20 of the stator 10. Accordingly, configurations described herein are directed to apparatus and methods for constructing the stator 10 and arranging the windings 14 of the stator 10 in a motor 12 with an internal rotor configuration.

[0019] 3-9, the motor 12 includes a stator 10, which is comprised of a plurality of structural rings 24 that can define the numerous stator teeth 16 contained within the stator 10. A tooth section 26 is comprised of a stack 28 of tooth lamination pieces 30. The stack 28 of tooth lamination pieces 30 is disposed within each tooth 16 and between adjacent structural rings 24. Thus, each stator tooth 16 of the stator 10 is comprised of an alternating arrangement of structural rings 24 and stacks 28 of tooth lamination pieces 30 that cooperate to form the stator tooth 16. A bobbin 30 is disposed around a portion of each tooth 16 of the stator 10. Winding sections 34 of conductive material are slidably disposed around the bobbin 30 relative to each tooth 16 of the stator 10. At this point, the winding sections 34 are separated from one another as they are attached to the respective stator teeth. The winding sections 34 are connected together to define the continuous winding 14 of the stator 10, which in turn forms a plurality of stator poles 36 configured to be selectively energized to generate an electromagnetic field.

[0020] An outer ring 38 is disposed around the outer periphery 22 of the teeth 16 of the stator 10. The outer ring 38 functions as a backiron 40 and also serves to house the winding sections 34 within a stator cavity 42. The stator cavity 42 is defined inside the outer ring 38 and outside the connecting portions 62 of the structural ring 24 that extend radially between adjacent stator teeth 16. In other words, the stator cavity 42 is defined inside the outer ring 38 and outside the core 44 of the stator 10, from which the teeth 16 of the stator 10 extend and which is made up of the connecting portions of the structural ring 24. An overmold 46 extends around the outer ring 38, the winding sections 34, the plurality of teeth 16, and the core 44 to form the overmolded stator 10. In certain embodiments of the present device, the outer ring 38 can have alignment channels 52 that interact with alignment protrusions 54 on the structural ring 24 and the tooth sections 26 of the stack of tooth laminations 30. In this manner, the outer ring 38 can be aligned in one or more desired orientations relative to the tooth sections 26 of the stator 10. This can also be used as a fastening device to securely fit the winding sections 34 between the outer ring 38 and the tooth sections 26 that form the stator cavity 42.

[0021] In certain embodiments of the present device, as illustrated in FIGS. 3-9 , the winding sections 34 can be connected to one another using a winding bracket 48. The winding bracket 48 includes a plurality of connectors 50 that connect certain winding sections 34 together. The connectors 50 are attached to wire ends 60 of the winding sections 34 to complete the windings 14. Certain wire ends 60 are not attached to the connectors 50 so that they can be attached to wiring that supplies current through the windings 14. Those wire ends 60 that are not connected to the connectors 50 of the winding bracket 48 can be positioned to extend beyond the overmold 46 and be connected to electrical leads to a power source. The winding sections 34 are coupled to one another by the winding bracket 48, which defines subsets 64 of the winding sections 34. These subsets 64 form various phases of the winding 14 that are in electrical communication with one another. The winding bracket 48 includes a plurality of winding connections 72 that define the subsets 64 of the winding sections 34. Again, the subsets 64 of winding sections 34 correspond to phases of the plurality of stator poles 36. By way of example, and without limitation, the plurality of winding connections 72 may include three winding connections corresponding to three phases of the plurality of stator poles 36. To define the various phases, the winding connections 72 on the winding bracket 48 are typically separated by insulating spacers 82 that electrically isolate the winding connections 72. The insulating spacers 82 provide dedicated, individual currents to the subsets 64 of winding sections 34 to achieve multi-phase operation of the stator 10.

[0022] With this configuration, the stator 10, which is an inner rotor configuration, can be wound from the outer periphery 22 before the outer ring 38 is placed around the winding sections 34. The outer ring 38 can then be fitted around the stator 10 to fit the winding sections 34 onto the teeth 16 of the stator 10. This configuration allows for the manufacture of an inner rotor configuration for the stator 10, without the need to place the windings 14 within the limited space within the rotor cavity 74 of the stator 10. Additionally, the windings 14 can be applied as pre-wound winding sections 34, as described more fully herein.

[0023] According to various embodiments of the present apparatus, as illustrated in FIGS. 4 and 5 , each bobbin 32 and the winding section 34 that is slidably disposed around each tooth 16 of the stator 10 can be pre-wound as a pre-formed winding section 34. Each winding section 34 is then positioned around the bobbin 32 relative to a corresponding tooth 16 of the stator 10. In certain embodiments of the present apparatus, the winding section 34 can be placed on the bobbin 32, and the bobbin 32 with the attached winding section 34 can be positioned around the corresponding tooth 16 of the stator 10. Thus, the winding section 34 and its corresponding bobbin 32 member form a bobbin assembly 76 that is disposed as a single component around the corresponding stator tooth 16. Using this configuration, multiple winding sections 34 and multiple bobbins 30 can be pre-fabricated and paired and then attached to the stator teeth 16. The wire ends 60 extending from each winding section 34 may be connected to adjacent winding sections 34 to form one or more continuous windings 14 extending around the stator 10. After the winding sections 34 are connected together to form one or more continuous windings 14, an overmold 46 is defined by placing overmold material around the components, at this point forming the insulated stator 10.

[0024] As illustrated in FIGS. 3-9 , the various bobbins 30 extending around the teeth 16 of the stator 10 can be formed with one or more bobbin sections 70 or end caps that slide around each tooth 16 having an enlarged tooth end 108. In various embodiments of the present device, as illustrated in FIGS. 13-14 , the bobbin 32 can have two opposing bobbin sections 70 that slide around each tooth 16 from opposite directions, such as above and below or left and right, and behind the tooth end to form the complete bobbin 32 structure. A winding section 34 of conductive material is then positioned around the two- or multi-piece bobbin 32. The winding section 34 can be wound around the bobbin section 70 or, if the tooth does not have an enlarged tooth end, can slide onto the bobbin section 70. The bobbin 32 serves to insulate the winding section 34 from the material of the structural ring 24 and stack 28 of tooth lamination pieces 30 that form each tooth 16 of the stator 10. In certain embodiments of the device, such as when teeth 16 do not have enlarged tooth ends, a single-piece bobbin 32 can be used instead of the multi-piece bobbin 32 having bobbin section 70. In such embodiments of the device, a pre-wound winding section 34 can also be slid onto the bobbin 32.

[0025] Referring again to FIGS. 3-9 , the process of forming the stator 10 can use a die 130 in the shape of the completed stator 10 to assemble the various components that make up the stator 10. Within the die, an initial outer structural ring 80 can be placed within the base of the die. Then, tooth laminate strips 30 can be added along the die at the location of each tooth 16 of the stator 10. These tooth laminate strips 30 can be placed one for each tooth 16, or multiple tooth laminate strips 30 can be formed into stacks 28 and placed within each die as the various teeth 16 of the stator 10 are assembled within the die. The number of tooth laminate strips 30 within a stack 28 can vary depending on the design of the stator 10. Typically, the number of tooth laminate strips 30 stacked between adjacent structural rings 24 will be constant to ensure that the structural rings 24 are generally parallel throughout the stator 10. The number of tooth laminations 30 in a particular stack 28 may be within the range of about 3 tooth laminations to about 10 tooth laminations, or about 5 tooth laminations to about 8 tooth laminations, or about 2 tooth laminations to about 15 tooth laminations.

[0026] Referring again to FIG. 9 , a sheet of metal material is typically transferred onto a die. Structural rings 24 and tooth laminations 30 are then stamped from the sheet of metal material and fed into the die. This sheet material is made of a ferrous metal that will form stator 10, as described herein. Stator 10 is built layer by layer using metal material. Structural rings 24 are stamped and placed into the die. Successive layers of stamped tooth laminations 30 are then fed into the die cavities. Additionally, each stamped portion of the sheet of metal material stamps alignment protrusions 90 into each lamination that will form one of stator 10's teeth 16. These protrusions 90 function in a nested configuration to secure the layers together and provide structural support to stator 10. In this manner, the processes of stamping the components of stator 10 and forming those components into stator 10 are integrated into a single operation.

[0027] In forming the stator 10, the assembly includes two punch arrangements. One punch operates to form the structural ring 24 from the sheet of metallic material. The other punch operates to form the layers of tooth laminations 30. As the stator 10 is built layer by layer, the appropriate punch is positioned above the die to punch the next layer of the stator 10 into the die. Again, the punched component is fed into the die immediately after being punched.

[0028] During this assembly of the stator 10, layers of tooth lamination strips 30 are punched sequentially into the die to form stacks 28 of tooth lamination strips 30 for each tooth 16. These stacks 28 of tooth lamination strips 30 are therefore formed simultaneously to maintain a consistent height for each tooth 16 as the stator 10 is assembled. In other words, as the stator 10 is built, each die position receives one tooth lamination strip 30 from a sheet of metal material. In certain embodiments of the apparatus, multiple sheets can be punched simultaneously to place an equal number of tooth lamination strips 30 in the die. Structural rings 24 are then punched and placed on the predetermined number of tooth lamination strips 30 for the multiple teeth 16, with each structural ring 24 evenly distributed among the various stacks 28 of tooth lamination strips 30. In this manner, as the teeth 16 of the stator 10 are built, the lamination strips and structural rings 24 are evenly distributed among the tooth 16 positions in the die.

[0029] Periodically, additional structural rings 24 are placed on top of the stack 28 of tooth lamination pieces 30 to strengthen the structure of the stator 10. When the stator 10 reaches a desired height, a final outer structural ring 80 is placed on top of the stack 28 of tooth lamination pieces 30 and on top of the stator 10 to complete the structure of the stator 10. With this configuration, the stator 10 is formed from a plurality of tooth lamination pieces 30 that are placed and strengthened using intermittent structural rings 24 and pairs of outer structural rings 80.

[0030] To aid in the assembly of the various tooth lamination pieces 30 and structural rings 24 of the stator 10, protrusions 90 may be stamped into a portion of each tooth lamination piece 30 and structural ring 24 of the various stator teeth 16. Each protrusion 90 forms a nested structure with an adjacent tooth lamination piece 30. This nested structure further positions and strengthens the structure of the stator 10. These protrusions 90 may also function as a locating feature to ensure that the stack 28 of tooth lamination pieces 30 is properly aligned with the other tooth lamination pieces 30 and structural rings 24 that form the stator 10. The use of protrusions 90 significantly reduces or eliminates lateral movement or shearing of the tooth lamination pieces 30 and structural rings 24.

[0031] 10-14, the stator 10 can include a plurality of tooth segments 100. Each tooth segment 100 can be formed from a plurality of tooth laminations 30 stacked together to form a desired tooth height for the teeth 16 of the stator 10. After the stacked tooth laminations 30 are arranged to form each tooth segment 100, a bobbin 32 is slid into place around the teeth 102 of the tooth segment 100. A pre-wound tooth winding 14 is then slid into place around the bobbin 32 to form a pre-wound stator segment 106.

[0032] As discussed herein, the winding sections 34 can be disposed on bobbins 32, and the assembled bobbins 32 and winding sections 34 can be placed on the teeth 102 of the tooth segments 100 to form stator segments 106. Each pre-wound stator segment 106, with its pre-attached bobbin 32 and winding sections 34, can then be coupled to two adjacent pre-wound stator segments 106 to form a stator core 44 having a plurality of pre-wound stator poles 36 extending inwardly therefrom. The core portions 104 of the tooth segments 100 have mating shapes that couple to form the core 44 of the stator 10. The winding sections 34 of each tooth segment 100 are then connected to each other to form one or more windings 14 of the stator 10. In this manner, each winding section 34 of a stator segment 106 couples with a corresponding winding section 34 to form phases of the windings 14 of the multiple stator segments 106. Typically, the windings 14 have three phases. The phases of the windings 14 and the windings 14 generally define a plurality of stator poles 36 configured to be selectively energized. After the windings 14 are combined into a desired configuration, an overmold material is placed over the plurality of stator segments 106 to form an overmold 46 for the stator 10, which insulates the stator. In certain embodiments of the present device, the individual winding sections 34 may be combined together after the overmold 46 is completed. In such a configuration, the wire ends 60 of each winding section 34 protrude from the overmold 46 and may be connected together to form the desired winding configuration.

[0033] According to various aspects of the present apparatus, the desired winding configuration can take the form of a single-phase winding, a three-phase winding, a stepper motor 12, or other similar motor configuration. Typically, the winding sections 34 are joined together prior to applying the overmold material that forms the insulating stator 10. As discussed herein, the winding brackets 48 used to attach the winding sections 34 to one another can be used to define the phase configuration of the windings 14.

[0034] The use of pre-wound winding sections 34 attached to the tooth sections 26 of the stator 10 allows for more efficient winding of a desired motor configuration. In particular, the winding configurations described herein achieve more efficient filling of the slots 110 defined between the teeth 16 of the stator 10. Furthermore, the configurations described herein allow for the use of heavier gauge wire in the pre-wound winding sections 34. This is possible because the assembly for winding the stator 10 does not have to weave through the stator core 44 with pre-positioned teeth 16, which can be difficult to thread around or between. The pre-wound winding sections 34 can be formed into a desired shape and then slid onto the corresponding teeth 16 of the stator 10 or onto the teeth 102 of the tooth segments 100. This pre-assembled configuration of the stator segments 106 allows the completed windings 14 to fill more of each slot 110 because space is not required to accommodate the assembly to weave the wires of the windings 14 around the teeth 16 of the stator 10.

[0035] Additionally, the motor 12 formed by the stator 10 described herein does not require the use of rare earth materials similar to permanent magnet motors. Competitive power densities are achieved without the use of permanent magnets. Additionally, the insulation structure described herein, by utilizing insulation in the overmold 46, allows the stator 10 components enclosed by the overmold material to be exposed to corrosive environments without damage. The stator 10 described herein uses heavier gauge wire and fills more of the slots 110 between the teeth 16, so power density is not lost as much as in other conventional electric motor systems.

[0036] In accordance with various aspects of the present apparatus, the stator 10 configurations described herein may be used with any one of a variety of rotors 18, including the rotor 18 configurations described herein. Furthermore, the disclosure of rotors 18 having reluctance air gaps 122, as described herein, is provided as exemplary and non-limiting types of rotors 18 that may be used in conjunction with the stator 10 configurations described herein, as well as other types of stators 10.

[0037] 2 and 15-18, the rotor 18 of the synchronous reluctance motor 12 includes a stack 28 of rotor laminations 120, typically fabricated from electrical-grade steel, to form a rotor body 140. Reluctance air gaps 122 are stamped from the rotor laminations 120 that form the rotor body 140 of the rotor 18. The reluctance air gaps 122 may also be stamped as part of each rotor lamination 120. One end lamination 124 may be positioned at each opposing end of the rotor 18 to act as a cover. The opposing end lamination 124 is generally solid within the cross-section of the rotor 18 and does not include the reluctance air gap 122. The opposing lamination 124 is attached to prevent wind noise that may occur if the reluctance air gap 122 were exposed. This typically provides clearance for a drive member, such as a drive shaft. After the end lamination pieces 124 are installed, the rotor 18 is encased in an overmold material that at least partially encases the outer surface 126 of the rotor 18 to form a rotor overmold 128. Typically, the overmold material is in the form of a non-metallic resin material. The resin may be in the form of a non-magnetic material, such as a resin, polymer, or other similar overmold material. Because both ends of the rotor 18 are covered by the end lamination pieces 124, the overmold material cannot penetrate into the reluctance air gaps 122. Because the reluctance air gaps 122 are free of overmold material, the rotor 18 remains balanced with a consistent overmold thickness around the rotor body 140. If the overmold material were to penetrate one or more of the reluctance air gaps 122, it could have an unbalancing effect on the rotor 18, potentially resulting in undesirable vibration or wobble. Therefore, the shape and size of the reluctance air gaps 122 are maintained throughout the assembly and overmold process of the rotor 18. The use of an overmold around the rotor body 140 also reduces the occurrence of corrosion within the rotor laminations 120 and on the opposing end laminations 124 .

[0038] During the process of forming the rotor 18, the connecting webs 150 of the rotor body, which define the reluctance air gaps 122, can be demagnetized or at least partially demagnetized to increase the reluctance characteristics of the rotor 18. In other words, demagnetizing the connecting webs 150 reduces the reluctance of the connecting webs 150, thereby creating a clearer path of least reluctance through which magnetic flux can flow through the rotor 18. Demagnetizing the connecting webs 150 in this manner promotes more effective interaction between the electromagnetic fields generated by the stator 10 and the rotor 18. Demagnetizing the rotor can be achieved by applying localized heating, such as with a laser or other heat source, or by inducing additional mechanical stresses within the rotor body.

[0039] During operation of the stator and rotor, the controller operates to control the supply of current to one or more phases of the windings. The controller may also operate in conjunction with position sensors that monitor the rotational position of the rotor relative to the stator or one or more windings on the stator. Current commutation is achieved by energizing the electromagnetic phases of the windings 14, selectively attracting the rotor's reluctance to align in a desired direction and inducing rotor rotation. Further, sensor feedback regarding the rotor's position is sent to the controller, allowing current to be smoothly and controlled through the windings, which in turn can be used to control the speed and torque output of the motor.

[0040] In certain embodiments of the device, the controller operates in a sensorless configuration. In an exemplary and non-limiting embodiment of the device, a voltage sensor or monitor can be used at the center point of the back electromotive force (EMF) voltage. This is typically compared to half the supplied DC bus voltage to calculate the relative inductance to determine the rotor position relative to the phase of the windings 14. When the rotor position is known, smooth, controlled current to the windings can be used to control the speed and torque of the motor without the use of separate position-sensing components.

[0041] 1-19 , which illustrate various aspects of the stator 10 and rotor 18 of the electric motor 12, a method 400 for forming the stator 10 of the electric motor 12 is disclosed. According to the method 400, step 402 includes placing a bottom outer structural ring 80 in a die. Next, a layer of stacked tooth lamination strips 30 is placed on the bottom outer structural ring 80 (step 404). Interrupted structural rings 24 are placed in an alternating configuration between adjacent layers of stacked tooth lamination strips 30 (step 406). As discussed herein, the various tooth lamination strips 30 are placed simultaneously relative to each tooth 16 to maintain a consistent height for each tooth 16 of the stator 10 as it is assembled. Next, a top outer structural ring 80 is placed on the top layer of stacked tooth lamination strips 30 to form the laminated stator 10 (step 408). The laminated stator 10 is then removed from the die (step 410). A bobbin assembly 76 is placed on each tooth 16 of the laminated stator 10 (step 412). As described herein, the bobbin 32 may be in the form of a single-piece bobbin 32 or a multi-piece bobbin 32 that can be assembled to surround each tooth 16 of the laminated stator 10. The bobbin assembly 76 may include the bobbin 32 and pre-wound winding sections 34 as a single assembly that can be slidably placed on the teeth 16. Alternatively, it is contemplated that the bobbin 32 and winding sections 34 can be sequentially placed on the teeth 16. When all of the bobbin assemblies 76 are attached to the stator teeth 16, the winding sections 34 form a segmented stator winding. The pre-wound winding sections 34 of the segmented stator winding are then attached using winding brackets 48 to form the completed stator winding 14 (step 414). An outer ring 38 is placed around the stator winding 14 and the laminated stator 10 (step 416). The outer ring 38 prevents the winding sections 34 from moving outward along each tooth 16 of the stator 10. The laminated stator 10 and stator windings 14 are then overmolded with an overmolding material (step 420).The use of pre-wound winding sections 34 as described herein also allows for greater slot filling and the use of heavier gauge wire which can generate a more effective electromagnetic field when current is passed through it.

[0042] As part of the method 400 for forming the stator 10, the structural ring 24 and tooth laminations 30 may be made less magnetic. By way of example and not limitation, thin sections of the structural ring 24, such as the connections, may be metallurgically modified to make them less magnetic. This is typically done by heating the steel, such as with a laser. In certain embodiments of the present apparatus, the connections of the structural ring 24 may be upset using a laser or by mechanical debridging means to reduce or eliminate magnetic effects that may result from the presence of the connections. It is contemplated that only portions of the connections may be upset or removed to provide the structure of the stator 10.

[0043] 1-18 and 20, which illustrate various aspects of the electric motor 12, a method 500 for forming a stator 10 for the electric motor 12 is disclosed. According to the method 500, a laminated tooth section 26 is formed (Step 502). A bobbin 32 is placed on the tooth portion 102 of each laminated tooth segment 100 (Step 504). A pre-wound winding section 34 is then placed on the tooth portion 102 of each laminated tooth segment 100, surrounding the corresponding bobbin 32 (Step 506). The laminated tooth segments 100 with their pre-wound winding sections 34 are then combined to form the annular core 44 of the stator 10 (Step 508). The pre-wound winding sections 34 are then combined to form the desired configuration of the windings 14 of the stator 10 (Step 510). The core 44, teeth 16, and windings 14 are then overmolded with an overmolding material (Step 512).

[0044] The use of pre-wound and then combined stacked winding sections 34 is typically utilized in the inner rotor configuration generally illustrated in Figures 11-18. The star configuration of the structural ring 24 of the stator 10 illustrated in Figure 4 can be used in either the inner rotor configuration or the outer rotor configuration depending on the design of the motor 12.

[0045] 1-18 and 21 , which illustrate various aspects of the present apparatus, a method 600 for forming a rotor 18 for an electric motor 12 is disclosed. According to method 600, steel rotor laminations 120 are formed by removing a reluctance section from each rotor lamination 120 to form a reluctance air gap 122 (Step 602). The rotor laminations 120 are stacked to form the rotor 18 structure (Step 604). The reluctance sections are aligned to define the reluctance air gap 122 within the rotor 18. Opposing end laminations 124, or end caps, are then placed on either end of the rotor 18 to enclose the reluctance air gap 122 (Step 606). As discussed herein, sealing the reluctance air gap 122 prevents the overmold material from penetrating and filling the reluctance air gap 122. The rotor 18 is then overmolded with the overmold material (Step 608). The opposing end lamination pieces 124, as described herein, prevent overmolding material from seeping into the reluctance air gap 122, which could adversely affect the operation and efficiency of the reluctance air gap 122 when operating with the windings 14 of the energized stator 10.

[0046] The assembly method for the synchronous reluctance motor 12 described herein allows for bobbin windings 14 in the motor assembly, which can fill the slots 110 of the stator 10 even more efficiently. The configuration described herein also facilitates the use of windings 14 with heavier gauge wire for improved slot filling compared to conventional needle-wound stators 10. Overmolding the stator 10 and overmolding the rotor 18 allows the motor 12 to be exposed to corrosive fluids without corroding the iron stator 10 or the iron rotor 18. Furthermore, as described herein, closing each end of the stack 28 of rotor lamination pieces 120 before overmolding prevents the injection-molded non-metallic resin material from flowing into the reluctance air gaps 122, which could cause rotor imbalance. Using overmolding on the rotor 18 provides a smooth overmolded surface, reducing wind noise that can arise from the air gaps 122 in the rotor 18 and eliminating "paddle" drag in wet rotor designs. In particular, if the gap 122 is exposed to fluid, it may increase the resistance to the rotor 18 as it rotates in a wet rotor configuration.

[0047] Additionally, when a non-metallic resin material is overmolded around the stator 10 and windings 14, the overmold material is configured to at least partially encase the inner diameter of the stator teeth 16. As described herein, this configuration allows the stator 10 to be used in liquids and corrosive environments. The use of an overmold 46 on the inner diameter of the stator teeth 16 prevents these materials from corroding or damaging the laminations of the stator 10.

[0048] It is to be understood that variations and modifications may be made to the above-described structure without departing from the concepts of the present invention, and it is to be further understood that such concepts are intended to be encompassed by the following claims unless expressly stated otherwise in language therein.

Claims

1. a plurality of structural rings defining a plurality of stator teeth; a tooth section formed from a stack of laminations disposed within each stator tooth of the plurality of stator teeth, the stack of laminations being disposed between adjacent ones of the plurality of structural rings; a bobbin disposed to surround each stator tooth; winding sections disposed around each stator tooth and around the bobbin, the winding sections coupled together to define a plurality of stator poles configured to be selectively energized; an outer ring disposed around an outer periphery of the plurality of stator teeth, the outer ring defining a stator core and including the winding sections within a stator cavity defined between the outer ring and an inner periphery of the plurality of structural rings; An electric motor comprising:

2. an overmold extending around the outer ring, the winding sections, and the plurality of stator teeth; The electric motor of claim 1 further comprising:

3. 3. The electric motor of claim 1 or 2, wherein the winding sections are coupled together by winding brackets that define subsets of the winding sections in electrical communication with each other.

4. 4. The electric motor of claim 3, wherein the winding bracket includes a plurality of winding connections forming the subset of the winding sections, the subset of the winding sections corresponding to phases of the plurality of stator poles.

5. The electric motor of claim 4 , wherein the plurality of winding connections includes three winding connections corresponding to three phases of the plurality of stator poles.

6. 6. The electric motor of claim 1, wherein the plurality of structural rings and the stack of laminations cooperate to form the stator core and the plurality of stator teeth extending from the stator core.

7. 7. The electric motor of claim 1, wherein each stack of the stacks of laminations includes in the range of about 3 to about 10 laminations disposed between adjacent ones of the plurality of structural rings.

8. 8. The electric motor of claim 1, wherein the bobbin and the winding sections are pre-formed to define a plurality of bobbin assemblies, each bobbin assembly of the plurality of bobbin assemblies including a bobbin member and a corresponding winding section disposed on the bobbin member.

9. The electric motor of claim 8 , wherein the plurality of bobbin assemblies are slidably mounted on corresponding ones of the plurality of stator teeth.

10. 8. The electric motor of claim 1, wherein each bobbin comprises a multi-piece bobbin slidably mounted on a corresponding one of the plurality of stator teeth.

11. 11. The electric motor of claim 10, wherein the multi-piece bobbin includes opposing bobbin sections that are slidably mounted on the corresponding stator teeth to define a bobbin member.

12. a rotor including a rotor body defined by a plurality of laminations; opposing end lamination pieces disposed on opposing ends of the rotor body, the opposing end lamination pieces configured to reduce wind noise during rotor operation occurring within a rotor cavity defined within the plurality of stator teeth; 12. An electric motor according to any one of claims 1 to 11, further comprising:

13. 13. The electric motor of claim 12, wherein the rotor body includes a plurality of reluctance air gaps defined within the plurality of laminations, and the opposing end laminations confine the plurality of reluctance air gaps within the rotor body.

14. 14. The electric motor of claim 13, wherein the rotor body includes connecting webs of material that form the plurality of reluctance air gaps, the connecting webs being demagnetized to reduce reluctance therethrough.

15. 15. The electric motor of claim 13 or 14, further comprising an overmold extending around the rotor body and the opposing end lamination pieces, the opposing end lamination pieces maintaining the plurality of reluctance air gaps free of the overmold.

16. The electric motor of claim 15 , wherein the overmold comprises a non-magnetic overmold material.

17. a rotor having a plurality of reluctance gaps defined within a rotor body of the rotor, and opposing end laminations that confine the plurality of reluctance gaps within the rotor body; The electric motor of claim 1 further comprising:

18. A plurality of tooth segments having a plurality of winding sections and a plurality of bobbins, each tooth segment comprising: stacked tooth laminations forming a core portion and a tooth portion; One bobbin among the plurality of bobbins is slidably disposed so as to surround the tooth portion of the stacked tooth stack pieces; a corresponding one of the plurality of winding sections disposed around the bobbin; and a plurality of tooth segments including each tooth segment is connected to two adjacent tooth segments to form a ring with the plurality of tooth segments extending inward; the plurality of winding sections are coupled to form at least one phase winding of the plurality of tooth segments, the phase winding defining a plurality of stator poles configured to be selectively energized; Motor.

19. 20. The motor of claim 18, wherein each tooth segment includes the bobbin and the corresponding winding section pre-attached when coupled with the two adjacent tooth segments.

20. The motor of claim 19 , wherein the bobbin includes opposing end caps disposed around the teeth of the stacked tooth laminations.

21. 21. The motor of any one of claims 18 to 20, wherein a conductive material is wound around the bobbin and the teeth to form each of the winding sections.

22. 22. The motor of claim 18, wherein an overmold is disposed around the plurality of tooth segments to form an overmolded stator.

23. 23. The motor of any one of claims 18 to 22, wherein the plurality of winding sections are coupled together by winding brackets that define subsets of the winding sections in electrical communication with each other.

24. 24. The motor of claim 23, wherein the winding bracket includes a plurality of winding connections forming the subset of the plurality of winding sections, the subset of the plurality of winding sections corresponding to phases of the plurality of stator poles.

25. 25. The motor of claim 24, wherein the plurality of winding connections includes three winding connections corresponding to three phases of the plurality of stator poles.

26. a rotor including a rotor body defined by a plurality of laminations; opposing end laminations disposed on opposing ends of the rotor body, the opposing end laminations configured to reduce wind noise during rotor operation within a rotor cavity defined within the plurality of tooth segments; 26. The motor of any one of claims 18 to 25, further comprising:

27. 27. The motor of claim 26, wherein the rotor body includes a plurality of reluctance air gaps defined within the plurality of laminations, and the opposing end laminations confine the plurality of reluctance air gaps within the rotor body.

28. 28. The motor of claim 27, wherein the rotor body includes connecting webs of material that form the plurality of reluctance air gaps, the connecting webs being demagnetized to reduce reluctance of the connecting webs.

29. 29. The motor of claim 27 or 28, further comprising an overmold extending around the rotor body and the opposing end lamination pieces, the opposing end lamination pieces maintaining the plurality of reluctance air gaps free of the overmold.

30. 30. The motor of claim 29, wherein the overmold comprises a non-magnetic overmold material.

31. A rotor having a plurality of reluctance gaps defined within a rotor body thereof, and opposing end laminations that confine the plurality of reluctance gaps within the rotor body. The motor of claim 18 further comprising:

32. placing a bottom structural ring into a die; placing a layer of stacked tooth lamination strips on the bottom structural ring; disposing interrupted structural rings in an alternating configuration between adjacent layers of the stacked tooth laminations; placing a top structural ring on top of the layer of the stacked tooth laminations to form a laminated stator; removing the laminated stator from the die; placing a bobbin assembly on each tooth of the laminated stator to define a segmented stator winding, each bobbin assembly including a bobbin member and a pre-wound winding section; disposing an outer ring around the segmented stator windings and the laminated stator; overmolding the laminated stator and the sectioned stator windings with an overmolding material; 1. A method of forming a stator for an electric motor, comprising:

33. attaching winding brackets to the pre-wound winding sections of the segmented stator winding to form the stator winding.

33. The method of claim 32, further comprising:

34. demagnetizing at least a portion of the laminated stator 34. The method of claim 32 or 33, further comprising:

35. 35. The method of claim 34, wherein the demagnetizing step is performed on a connection between the bottom structural ring, the interrupted structural ring, and the top structural ring, the connection extending between radially adjacent stacks of the layers of the stacked tooth laminations.

36. forming a plurality of stacked tooth segments; placing a bobbin assembly on a tooth portion of a corresponding laminated tooth segment of each of the plurality of laminated tooth segments to define a plurality of stator segments, each bobbin assembly including a corresponding bobbin member and a corresponding winding section; combining the plurality of stator segments to form a pre-wound stator core; attaching winding brackets to the corresponding winding sections of the prewound stator core to form stator windings on the prewound stator core; overmolding the pre-wound stator core with an overmolding material; 1. A method of forming a stator for an electric motor, comprising:

37. 37. The method of claim 36, wherein the bobbin member includes opposing end caps positioned to surround the teeth of the corresponding laminated tooth segment of the plurality of laminated tooth segments, and the winding section is wound around the opposing end caps and the teeth of the corresponding laminated tooth segment.

38. The step of placing the bobbin assembly on the teeth comprises: placing the winding section on the bobbin member to define the bobbin assembly; Sliding the bobbin assembly around the teeth; 37. The method of claim 36, comprising:

39. forming rotor laminations with the reluctance section removed from each rotor lamination; stacking the rotor laminations to form a rotor body and aligning the reluctance sections to define a reluctance gap within the rotor body; placing opposing end caps on the rotor body to enclose the reluctance gap; overmolding the rotor body with an overmold material, the opposing end caps preventing the overmold material from entering the reluctance air gap; 1. A method of forming a rotor for an electric motor, comprising:

40. demagnetizing the reluctance section of the rotor body to reduce the reluctance of the reluctance section; 40. The method of claim 39, further comprising:

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