Synchronous reluctance machine having stator with stacked laminations and method of construction

Abstract

An electric motor is disclosed that includes a plurality of structural rings defining a plurality of stator teeth. The tooth section is formed from a stack of laminations positioned within each of the plurality of stator teeth. A stack of laminations is positioned between adjacent rings of the plurality of structural rings. A spool is positioned on each stator tooth. Winding sections are respectively positioned on each stator tooth and around the bobbin. The winding segments are coupled together to define a plurality of stator poles configured to be selectively energized. The outer ring is positioned around an outer circumference of the plurality of stator teeth. The outer ring defines a stator core and contains the winding segments within a stator cavity defined between the outer ring and an inner circumference of the plurality of structural rings.

Description

Technical Field

[0001] The present invention relates generally to electric motors, and more particularly to a synchronous reluctance motor having a series of stacked tooth laminations coupled together to form a continuous stator. In addition, separate bobbins and winding sections can be attached to each formed tooth of the stator. The winding sections can also be attached together to form stator windings. The stator can be overmolded so that each individual tooth and winding section can be covered and insulated by an overmolding material. Background Art

[0002] An electric motor generally includes a stator and a rotor, wherein the stator includes windings that can be energized to form an electromagnetic field that interacts with the rotor. The interaction between the electromagnetic field of the stator and the 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 segment is formed by a stack of laminations positioned within each of the plurality of stator teeth. The stack of laminations is positioned between adjacent rings of the plurality of structural rings. A bobbin is positioned on each stator tooth. A winding segment is positioned on each stator tooth and around the bobbin, respectively. The winding segments are coupled together to define a plurality of stator poles configured to be selectively energized. An outer ring is positioned around an outer circumference of the plurality of stator teeth. The outer ring defines a stator core and contains the winding segment within a stator cavity, the stator cavity being defined between the outer ring and an inner circumference of the plurality of structural rings.

[0004] According to another aspect, an electric motor includes a plurality of tooth segments. Each tooth segment includes stacked tooth laminations forming a core portion and a tooth portion, a bobbin slidably positioned on the tooth portion of the stacked tooth laminations, and a winding section positioned around the bobbin. Each tooth segment is coupled to two adjacent tooth segments to form a ring with a plurality of tooth segments extending inwardly, and the winding sections of the plurality of tooth segments are coupled together 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 mold; placing a layer of stacked tooth laminations on the bottom structural ring; positioning intermittent structural rings between adjacent layers of stacked tooth laminations in an alternating configuration; placing a top structural ring on a top layer of the layer of stacked tooth laminations to form a laminated stator; removing the laminated stator from the mold; and positioning 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 segment. The method also includes placing an outer ring around the segmented stator winding and the laminated stator, and overmolding the laminated stator and the segmented stator winding with an overmolding material.

[0006] According to another aspect, a method for forming a stator for an electric motor includes: forming a plurality of laminated tooth segments; placing a bobbin assembly onto a tooth portion of each respective laminated tooth segment in 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 also includes attaching the plurality of stator segments to form a pre-wound stator core; attaching a winding support 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 overmolding material.

[0007] According to another aspect, a method for forming a rotor for an electric motor includes: forming steel laminations, removing reluctance segments from each of the steel laminations; stacking the steel laminations to form a rotor body, wherein the reluctance segments are aligned to define a reluctance gap within the rotor body; providing opposite ends on the rotor body to close the reluctance gap; and overmolding the rotor structure with an overmolding material. Opposing end caps prevent the overmolding material from penetrating into the reluctance gap.

[0008] Those skilled in the art will understand and appreciate these and other aspects, objects and features of the present disclosure upon studying the following specification, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In the attached picture:

[0010] Figure 1 is a perspective view of an electric motor incorporating an aspect of the stator and rotor configuration described herein;

[0011] Figure 2 It is taken along line II-II Figure 1 A schematic cross-sectional view of an electric motor;

[0012] Figure 3 is a perspective view of a stator incorporating an outer ring positioned around an outer circumference of the teeth of the stator;

[0013] Figure 4 yes Figure 3 A partially exploded perspective view of a stator of FIG. 1 , wherein the stator is separated from the overmold;

[0014] Figure 5 yes Figure 4 An exploded perspective view of a stator;

[0015] Figure 6 The tooth lamination assembly is shown using a structural ring and stacked Figure 5 A schematic perspective view of a stator tooth of a stator;

[0016] Figure 7 yes Figure 5 A top perspective view of a stator core of a stator, positioned between adjacent structural rings to form Figure 2A side perspective view of a stack of stator tooth laminations;

[0017] Figure 8 yes Figure 7 An exploded perspective view of a stator core;

[0018] Fig. 9 is a schematic diagram illustrating assembling stator teeth of a stator core using a structural ring and stacked tooth laminations;

[0019] Fig.10 is a partial exploded view of a stator incorporating a plurality of pre-wound tooth segments and showing the stator separated from an overmold;

[0020] Fig.11 yes Fig.10 An exploded perspective view of a stator;

[0021] Fig.12 yes Fig.11 An exploded perspective view of the stator core is shown;

[0022] Fig.13 yes Fig.10 A perspective view of a pre-wound tooth segment of a stator;

[0023] Fig.14 yes Fig.13 An exploded perspective view of a pre-wound tooth segment;

[0024] Fig.15 is a perspective view of a rotor incorporating a reluctance gap within a rotor body;

[0025] Fig.16 yes Fig.15 An exploded perspective view of a rotor;

[0026] Fig.17 It is taken along XVII-XVII Fig.15 A cross-sectional view of a stator;

[0027] Fig.18 It is cut along XVIII-XVIII Fig.15 A cross-sectional view of a stator;

[0028] Fig.19 is a schematic flow chart illustrating a method for forming a stator for an electric motor;

[0029] Fig. 20 is a schematic flow chart illustrating a method for forming a stator for an electric motor; and

[0030] Fig.21 is a schematic flow chart illustrating a method for forming a stator for an electric motor. DETAILED DESCRIPTION

[0031] As required, detailed embodiments of the present disclosure are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the present invention, which may be embodied in various and alternative forms. The drawings are not necessarily detailed designs; some schematic diagrams may be enlarged or minimized to show a functional overview. 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 to adopt the present invention in various ways.

[0032] For the purpose of the description herein, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal" and their derivatives shall refer to the above. Figures 1 to 18 The concepts of the present invention are oriented in the following embodiments. However, it should be understood that the concepts can take various alternative orientations unless expressly specified to the contrary. It should also be understood that the specific devices and processes illustrated in the drawings and described in the following specification are merely exemplary embodiments of the present invention concepts defined in the appended claims. Therefore, unless the claims expressly state otherwise, the specific dimensions and other physical characteristics related to the embodiments disclosed herein should not be considered limiting.

[0033] The presently illustrated embodiments reside primarily in a combination of method steps and apparatus components associated with an electric motor having a shaped and overmolded stator having pre-wound winding segments attached to the teeth of the stator and an overmolded rotor including hollow reluctance gaps contained between outer laminations. Accordingly, where appropriate, apparatus components and method steps have been represented by conventional symbols in the drawings, with only those specific details relevant to understanding the embodiments of the present disclosure being shown so as not to obscure the present disclosure with details that would be apparent to one of ordinary skill in the art having the benefit of the description herein. Additionally, like reference numerals in the specification and drawings represent like elements.

[0034] As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items may be taken alone, or any combination of two or more of the listed items may be taken. For example, if a composition is described as comprising components A, B, and / or C, the composition may comprise 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.

[0035] In this document, relational terms such as first and second, top and bottom, etc. are used only to distinguish one entity or action from another entity or action, and do not necessarily require or imply any actual such relationship or order between such entities or actions. The terms "comprises" or "comprising" or any 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 includes not only those elements, but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by "comprises..." does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0036] As used herein, the term "about" means that the amount, size, formulation, parameter and other quantities and features are not exact and need not be exact, but can be approximate and / or larger or smaller as needed, reflecting tolerances, conversion factors, rounding, measurement errors, etc., and other factors known to those skilled in the art. When the term "about" is used to describe the endpoints of a value or range, the disclosure should be understood to include the specific value or endpoint mentioned. Regardless of whether the endpoint of a numerical value or range in the specification is expressed as "about", the endpoint of the numerical value or range is intended to include two embodiments: one modified by "about" and one not modified by "about". It should also be understood that each endpoint in the range is meaningful whether it is related to another endpoint or independent of another endpoint.

[0037] As used herein, the terms "substantially," "substantially," and variations thereof are intended to mean that the feature being described is equal to or approximately equal to a value or description. For example, a "substantially planar" surface is intended to mean a planar or approximately planar surface. Additionally, "substantially" is intended to mean that two values ​​are equal or approximately equal. In some embodiments, "substantially" can mean values ​​that are within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0038] As used herein, the terms "the," "a," or "an" mean "at least one," and should not be limited to "only one," unless expressly indicated to the contrary. Thus, for example, reference to "a component" includes embodiments having two or more such components, unless the context clearly indicates otherwise.

[0039] Reference now Figures 1 to 18, reference numeral 10 generally refers to a stator 10 incorporated within an electric motor 12, wherein the stator 10 includes one or more windings 14 positioned on teeth 16 of the stator 10. The windings 14 are energized to generate a magnetic field that rotates a rotor 18 positioned relative to the stator 10. The windings 14 are typically energized by a controller that manages the delivery of current to one or more phases in the windings 14. The rotor 18 may be positioned within an inner circumference 20 of the stator 10, or may be positioned outside an outer circumference 22 of the stator 10, depending on the configuration of the electric motor 12. Generally, the configurations described herein involve a rotor 18 rotating within an inner circumference 20 of the stator 10. Therefore, the configurations described herein involve apparatus and methods for constructing a stator 10 and positioning the windings 14 of the stator 10 on an inner rotor configuration electric motor 12.

[0040] Reference now Figures 3 to 9 , the electric machine 12 includes a stator 10, which is constructed of a plurality of structural rings 24 that may define a plurality of stator teeth 16 included within the stator 10. The tooth segments 26 are constructed of stacks 28 of tooth laminations 30. The stacks 28 of tooth laminations 30 are positioned within each tooth 16 and between adjacent structural rings 24. Thus, each stator tooth 16 of the stator 10 is constructed of an alternating arrangement of structural rings 24 and stacks 28 of tooth laminations 30 that cooperate to form the stator tooth 16. A bobbin 30 is positioned around a portion of each tooth 16 of the stator 10. For each tooth 16 of the stator 10, winding segments 34 of conductive material are slidably positioned on the bobbin 30, respectively. At this time, the winding segments 34 are separated from each other when they are respectively mounted on the plurality of stator teeth. The winding segments 34 are coupled together to define a continuous winding 14 of the stator 10 that forms a plurality of stator poles 36 that are configured to be selectively energized to generate an electromagnetic field.

[0041] The outer ring 38 is positioned around the outer circumference 22 of the teeth 16 of the stator 10. The outer ring 38 serves as a back iron 40 and also serves to contain the winding segments 34 within the stator cavity 42. The stator cavity 42 is defined within the outer ring 38 and outside of the connecting portion 62 of the structural ring 24, which extends radially between adjacent stator teeth 16. In other words, the stator cavity 42 is defined within the outer ring 38 and outside of the core 44 of the stator 10, from which the teeth 16 of the stator 10 extend, wherein the core 44 is formed by the connecting portion of the structural ring 24. The overmold 46 extends around the outer ring 38, the winding segments 34, the plurality of teeth 16, and the core 44 to form the overmold stator 10. In certain aspects of the device, the outer ring 38 may include an alignment channel 52 that interacts with an alignment protrusion 54 of the tooth segment 26, which is formed by the stack of structural rings 24 and tooth laminations 30. In this way, the outer ring 38 can be aligned in one or more desired orientations relative to the tooth segments 26 of the stator 10. This can also serve as a securing means to ensure a secure fit between the outer ring 38 and the tooth segments 26 that form the stator cavity 42 that holds the winding segments 34.

[0042] In some aspects of the device, such as Figures 3 to 9 , the winding sections 34 can be connected together using a winding support 48. The winding support 48 includes a plurality of connectors 50 that link specific winding sections 34 together. The connectors 50 are attached to the wire ends 60 of the winding sections 34 to complete the winding 14. Some of the wire ends 60 are not attached to the connectors 50 so that they can be attached to wiring for conveying current through the winding 14. These wire ends 60 of the connectors 50 that are not connected to the winding support 48 can be positioned to extend from the overmold 46 to connect with electrical leads to and from the power supply. The winding sections 34 are coupled together by the winding support 48, which defines subsets 64 of the winding sections 34. These subsets 64 form individual phases of the winding 14 that are electrically connected to each other. The winding support 48 includes a plurality of winding connections 72 that form the subsets 64 of the winding sections 34. Similarly, the subsets 64 of the winding sections 34 correspond to the phases of the plurality of stator poles 36. As an example and not limitation, the plurality of winding connections 72 may include three winding connections corresponding to the three phases of the plurality of stator poles 36. To define the various phases, the winding connections 72 of the winding support 48 are generally separated by insulating spacers 82 that electrically separate the winding connections 72. The insulating spacers 82 provide dedicated and separate current delivery to the subsets 64 of the winding sections 34 to produce multi-phase operation of the stator 10.

[0043] With this configuration, the stator 10 as an inner rotor configuration can be wound from the outer circumference 22 before the outer ring 38 is placed around the winding sections 34. The outer ring 38 can then be placed around the stator 10 to contain the winding sections 34 on the teeth 16 of the stator 10. This configuration allows the manufacture of an inner rotor configuration of the stator 10 without the need to position the windings 14 within the limited space within the rotor cavity 74 of the stator 10. In addition, the windings 14 can be applied as pre-wound winding sections 34, as described more fully herein.

[0044] According to various aspects of the device, such as Figure 4 and Figure 5 As illustrated, the winding segments 34 slidably positioned on each bobbin 32 and each tooth 16 of the stator 10 can be pre-wound into shaped winding segments 34. Each winding segment 34 is then placed on the bobbin 32 for the corresponding tooth 16 of the stator 10. In certain aspects of the device, the winding segments 34 can be placed on the bobbin 32, and the bobbin 32 with the winding segments 34 thereon can be placed on the corresponding tooth 16 of the stator 10. Thus, the winding segments 34 and the corresponding bobbin 32 members form a bobbin assembly 76, which is placed on the corresponding stator tooth 16 as a single component. Using this configuration, multiple winding segments 34 and multiple bobbins 30 can be pre-manufactured and paired to be installed on the stator teeth 16. The wire ends 60 extending from each winding segment 34 can be connected to adjacent winding segments 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 , the overmold 46 is defined by placing an overmold material over the components to form the now insulated stator 10 .

[0045] like Figures 3 to 9 As illustrated, the various bobbins 30 extending over the teeth 16 of the stator 10 may be formed from one or more bobbin segments 70 or end caps that are slidably positioned over each tooth 16 having an enlarged tooth end 108. Figure 13 to Figure 14As illustrated, in various aspects of the device, the bobbin 32 may include two opposing bobbin sections 70 that slide over and around each tooth 16 from opposing directions (such as from above and below, or from one side to the other) and are located behind the tooth ends to form the complete structure of the bobbin 32. The winding sections 34 of the conductive material are then positioned on the two-piece or multi-piece bobbin 32. The winding sections 34 can be wrapped around the bobbin sections 70, or in the case where the teeth do not include enlarged tooth ends, the winding sections 34 can be slidably mounted on the bobbin sections 70. The bobbin 32 is used to insulate the winding sections 34 from the material of the stack 28 of tooth laminations 30 and the structural ring 24 that forms each tooth 16 of the stator 10. In certain aspects of the device, such as in the case where the teeth 16 do not have enlarged tooth ends, a single-piece bobbin 32 can be used instead of a multi-piece bobbin 32 with bobbin sections 70. In such aspects of the device, the pre-wound winding section 34 may also be slidably disposed in the bobbin 32 .

[0046] Reference again Figures 3 to 9 During the formation of the stator 10, a mold 130 in the shape of the finished stator 10 can be used to assemble the various components that make up the stator 10. Within the mold, a first outer structural ring 80 can be positioned within the base of the mold. Then tooth laminations 30 can be added around the mold in the location of each tooth 16 of the stator 10. As the various teeth 16 of the stator 10 are built within the mold, these tooth laminations 30 can be positioned one at a time for each tooth 16, or multiple tooth laminations 30 formed into a stack 28 can be positioned within each mold. The number of tooth laminations 30 within a stack 28 can vary depending on the design of the stator 10. Typically, the number of tooth laminations 30 stacked between adjacent structural rings 24 will be consistent. This is to ensure that the structural rings 24 pass through the stator 10 in a generally parallel manner. The number of tooth laminations 30 in a particular stack 28 can range from 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.

[0047] Reference again Fig. 9Typically, a sheet of metal stock is moved over a die. Subsequently, structural rings 24 and tooth laminations 30 are punched out of the sheet of metal stock and directed into the die. As described herein, the sheet is made of a ferrous metal that forms the stator 10. Using the metal stock, the stator 10 is built up layer by layer. The structural ring 24 is punched and set in the die. Subsequently, successive layers of these punched out tooth laminations 30 are directed into the cavity of the die. In addition, for each stamped portion of the metal stock sheet, alignment protrusions 90 are punched out in each lamination that forms one of the teeth 16 of the stator 10. These protrusions 90 operate in a nested configuration to lock the layers together to structurally support the stator 10. In this way, the process of stamping the components of the stator 10 and forming these components into the stator 10 is combined into a single operation.

[0048] During the formation of the stator 10, the assembly includes two punch configurations. One punch operates to form the structural ring 24 from a sheet of metal stock. The other punch operates to form the layers of the tooth laminations 30. As the stator 10 is built up layer by layer, the appropriate punch is positioned over the die to punch the next layer of the stator 10 into the die. Again, the stamped parts are directed into the die immediately after being stamped.

[0049] During such assembly of the stator 10, layers of tooth laminations 30 are continuously punched into the die to form a stack 28 of tooth laminations 30 for each tooth 16. Thus, these stacks 28 of tooth laminations 30 are formed simultaneously to maintain a consistent height of each tooth 16 during assembly of the stator 10. In other words, when the stator 10 is built, each position of the die receives one tooth lamination 30 from a sheet of metal stock. In certain aspects of the apparatus, multiple sheets may be punched simultaneously so that the same number of tooth laminations 30 are placed in the die. Structural rings 24 are then punched to rest on a predetermined number of tooth laminations 30 for a plurality of teeth 16 so that each structural ring 24 rests evenly on each stack 28 of tooth laminations 30. In this manner, when the teeth 16 of the stator 10 are built, the laminations and structural rings 24 are evenly distributed among the tooth positions of the die.

[0050] Periodically, additional structural rings 24 are positioned above the stack 28 of tooth laminations 30 to strengthen the structure of the stator 10. When the desired height of the stator 10 is achieved, a final outer structural ring 80 is positioned over the stack 28 of tooth laminations 30 and at the top of the stator 10 to complete the structure of the stator 10. With this configuration, the stator 10 is formed of a plurality of tooth laminations 30 that are positioned and strengthened using intermittent structural rings 24 and a pair of outer structural rings 80.

[0051] To aid in assembling the various tooth laminations 30 and structural rings 24 for the stator 10, a portion of each tooth lamination 30 and structural ring 24 for each stator tooth 16 may be stamped to form protrusions 90. Each protrusion 90 forms a nested configuration with adjacent tooth laminations 30. This nested configuration further positions and strengthens the structure of the stator 10. These protrusions 90 may also serve as locating features for ensuring that the stack 28 of tooth laminations 30 is properly aligned relative to the other tooth laminations 30 and structural rings 24 forming the stator 10. By using the protrusions 90, lateral displacement or misalignment of the tooth laminations 30 and structural rings 24 is greatly minimized or eliminated.

[0052] Reference now Figures 10 to 14 , the stator 10 may include a plurality of tooth segments 100. Each tooth segment 100 may be formed from a plurality of tooth laminations 30 that are stacked to form a desired tooth height of the teeth 16 of the stator 10. After the stacked tooth laminations 30 are positioned to form each tooth segment 100, the bobbin 32 may be slidably positioned over the tooth portion 102 of the tooth segment 100. Then, the pre-wound tooth winding 14 may be slidably positioned over the bobbin 32 to form a pre-wound stator segment 106.

[0053] As discussed herein, the winding segments 34 may be placed in the bobbin 32, and the assembled bobbin 32 and winding segments 34 may be placed onto the tooth portion 102 of the tooth segment 100 to form the stator segment 106. Each pre-wound stator segment 106 having the pre-attached bobbin 32 and winding segments 34 is then 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 from the stator core 44. The core portion 104 of the tooth segment 100 includes mating geometries that interlock to form the core 44 of the stator 10. The winding segments 34 of each tooth segment 100 are then connected together to form one or more windings 14 of the stator 10. In this manner, the respective winding segments 34 of the stator segments 106 are coupled with the corresponding winding segments 34 to form phases of the windings 14 of the plurality of stator segments 106. Typically, the winding 14 has three phases. The phases of the winding 14 and the winding 14 generally define a plurality of stator poles 36 configured to be selectively energized. After the windings 14 are attached together in the desired configuration, an overmold material is disposed on the plurality of stator segments 106 to form an overmold 46 for the stator 10, with the stator 10 being insulated by the overmold 46. In certain aspects of the device, the individual winding segments 34 can be attached together after the overmold 46 is completed. In this configuration, the wire ends 60 of each winding segment 34 can protrude from the overmold 46 and be connected together to form the desired winding configuration.

[0054] According to various aspects of the device, the desired winding configuration can be in 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 attached together prior to applying the overmold material that forms the insulating stator 10. As discussed herein, the winding bracket 48 used to attach the winding sections 34 together can be used to define the phase configuration of the winding 14.

[0055] The use of pre-wound winding sections 34 attached to the teeth sections 26 of the stator 10 provides more efficient winding for the desired motor configuration. In particular, the winding configuration described herein can achieve more efficient filling of the slots 110 defined between the teeth 16 of the stator 10. In addition, the configuration described herein allows a larger gauge wire to be used for the pre-wound winding sections 34. Since the components used to wind the stator 10 do not need to be wound between the stator core 44 having pre-positioned teeth 16 (which may be difficult to wrap around and between the pre-positioned teeth), a larger gauge wire can be used. The pre-wound winding sections 34 can be formed into the desired shape and can then be slidably disposed on the corresponding teeth 16 of the stator 10 or the tooth portion 102 of the tooth segment 100. This pre-assembled configuration of the stator segment 106 allows the finished winding 14 to occupy more parts of each slot 110 because no space is required to accommodate the components used to wind the wire of the winding 14 around the teeth 16 of the stator 10.

[0056] In addition, 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 density is achieved without the use of permanent magnets. Furthermore, the insulating construction described herein by using the insulating overmold 46 allows exposure to corrosive environments without damaging the components of the stator 10 surrounded by the overmold material. Because the stator 10 described herein utilizes higher gauge wire and the slots 110 between the teeth 16 have increased filling, power density is not lost compared to other conventional motor systems.

[0057] According to various aspects of the apparatus, the configurations of the stators 10 described herein may be used with any of a variety of rotors 18, including the rotor 18 configurations described herein. Additionally, as described herein, the disclosure of a rotor 18 having a reluctance gap 122 is provided as an exemplary and non-limiting type of rotor 18 that may be used in conjunction with the stator 10 configurations described herein as well as other types of stators 10.

[0058] Reference now Figure 2 and Figures 15 to 18The rotor 18 for the synchronous reluctance motor 12 includes a stack 28 of rotor laminations 120, which are typically made of electrical grade steel to form a rotor body 140. Reluctance gaps 122 are stamped from the rotor laminations 120 that form the rotor body 140 of the rotor 18. The reluctance gaps 122 may also be stamped as part of each rotor lamination 120. A single end lamination 124 may be positioned at each opposite end of the rotor 18 to serve as a cover. The opposite end laminations 124 are typically solid within the cross-section of the rotor 18 and do not include reluctance gaps 122. The opposite end laminations 124 are installed to prevent windage noise that may occur if the reluctance gaps 122 are exposed. Space is typically provided for a drive member, such as a drive shaft. After the end laminations 124 are placed, the rotor 18 is then encapsulated with an overmolding material that at least partially encapsulates an outer surface 126 of the rotor 18 to form a rotor overmold 128. Typically, the overmolding material is in the form of a non-metallic resin material. The resin may also be in the form of a non-magnetic material, such as a resin, a polymer or other similar overmolding material. Because the ends of the rotor 18 are covered by the end laminations 124, the overmolding material cannot penetrate into the reluctance gaps 122. In the absence of overmolding material in the reluctance gaps 122, the rotor 18 is balanced with the consistent thickness of the overmolding around the rotor body 140. The penetration of the overmolding material into one or more of the reluctance gaps 122 may have the effect of causing an imbalance in the rotor 18, which may cause undesirable vibration or oscillation. Therefore, the shape and size of the reluctance gaps 122 can be maintained throughout the assembly and overmolding process of the rotor 18. The use of the overmolding around the rotor body 140 also limits the occurrence of corrosion within the rotor laminations 120 and the opposing end laminations 124.

[0059] During formation of the rotor 18, the connecting webs 150 of the rotor body that define the reluctance gaps 122 may 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 providing a more defined path of minimum reluctance through which magnetic flux may flow through the rotor 18. Such demagnetization of the connecting webs 150 has the effect of making the interaction between the electromagnetic field generated by the stator 10 and the rotor 18 more efficient. Demagnetization of the rotor may be achieved by localized heating, such as with a laser or other heat source, or by applying additional induced mechanical stresses within the rotor body.

[0060] During operation of the stator and rotor, the controller operates to control the delivery of current to one or more phases of the windings. The controller may also operate in conjunction with a position sensor that monitors the rotational position of the rotor relative to the stator or one or more windings of the stator. Commutation of the current may be achieved by electrically exciting the electromagnetic phases of the windings 14 to selectively attract the reluctance of the rotor and align the reluctance of the rotor in a desired direction to cause rotation of the rotor. In addition, sensor feedback of the rotor position delivered to the controller allows smooth and controllable current to flow to the windings. This in turn may be used to control the speed and torque output of the motor.

[0061] In certain aspects of the device, the controller operates in a sensorless configuration. In an exemplary and non-limiting aspect of the device, a voltage sensor or voltage monitor may be used at the center point of the back EMF voltage. This is typically compared to half of the supplied DC bus voltage to calculate the relative inductance for determining the position of the rotor relative to the phase of the winding 14. When the position of the rotor is known, a smooth and controllable current to the windings may be used to control the speed and torque of the motor without the need for a separate position sensing component.

[0062] Reference now Figures 1 to 19, various aspects of the stator 10 and rotor 18 for the motor 12 have been described, and a method 400 for forming the stator 10 of the motor 12 is disclosed. According to the method 400, step 402 includes placing a bottom outer structural ring 80 in a mold. Then the layer of stacked tooth laminations 30 is placed on the bottom outer structural ring 80 (step 404). Intermittent structural rings 24 are placed between adjacent layers of the stacked tooth laminations 30 in an alternating configuration (step 406). As discussed herein, each tooth lamination 30 is positioned in a simultaneous manner relative to each tooth 16 to maintain a consistent height of each tooth 16 of the stator 10 during assembly of the stator 10. The top outer structural ring 80 is then placed on the top layer of the layer of stacked tooth laminations 30 to form the laminated stator 10 (step 408). The laminated stator 10 is then removed from the mold (step 410). The bobbin assembly 76 is positioned on each tooth 16 of the laminated stator 10 (step 412). As described herein, the bobbin 32 can be in the form of a single-piece bobbin 32 or a multi-part bobbin 32 that can be assembled on each tooth 16 of the laminated stator 10. The bobbin assembly 76 can include the bobbin 32 and the pre-wound winding section 34, which can be slidably set into the tooth 16 as a single assembly. It is contemplated that in alternative aspects, the bobbin 32 and the winding section 34 can be sequentially set on the tooth 16. With all the bobbin assemblies 76 installed on 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 the winding bracket 48 to form a complete stator winding 14 (step 414). The outer ring 38 is placed around the stator winding 14 and the laminated stator 10 (step 416). The outer ring 38 prevents the winding section 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). As described herein, the use of pre-wound winding sections 34 provides greater slot filling and also provides for the use of larger gauge wires that can produce more efficient electromagnetic fields when energized with current.

[0063] As part of the method 400 for forming the stator 10, the structural ring 24 and the tooth laminations 30 can be made to have lower magnetic properties. By way of example and not limitation, thin sections (such as the connecting portions of the structural ring 24) can be metallurgically altered to have lower magnetic properties. This is typically performed by heating (such as by using a laser) the steel. In certain aspects of the device, the connecting portions of the structural ring 24 can be upset using a laser or by a mechanical de-bridging device to reduce or eliminate magnetic effects that may be generated by the presence of the connecting portions. It is contemplated that only a portion of the connecting portion is upset or removed to provide structure to the stator 10.

[0064] Reference now Figures 1 to 18 and Fig. 20 , having described various aspects of the electric motor 12, a method 500 for forming the stator 10 of the electric motor 12 is disclosed. According to the method 500, the laminated tooth segments 26 are formed (step 502). The bobbin 32 is placed onto the tooth portion 102 of each of the laminated tooth segments 100 (step 504). The pre-wound winding segment 34 is then placed onto the tooth portion 102 of each laminated tooth segment 100 and onto the corresponding bobbin 32 (step 506). The laminated tooth segments 100 with the pre-wound winding segments 34 are then attached together to form the circular core 44 of the stator 10 (step 508). The pre-wound winding segments 34 are then attached together to form the desired configuration of the windings 14 for the stator 10 (step 510). The core 44, the teeth 16, and the windings 14 are then overmolded using an overmolding material (step 512).

[0065] Usually, in Figures 11 to 18 The inner rotor configuration generally illustrated in FIG. 1 uses laminated winding sections 34 that are pre-wound and then attached together. Figure 4 The star configuration of the structural rings 24 for the stator 10 illustrated in FIG. 4 may be used in either an inner rotor configuration or an outer rotor configuration, depending on the design of the electric machine 12 .

[0066] Reference now Figures 1 to 18 and Fig.21 , various aspects of the apparatus having been described, a method 600 for forming a rotor 18 of an electric motor 12 is disclosed. According to the method 600, steel rotor laminations 120 are formed, and reluctance segments are removed from each of the rotor laminations 120 to form a reluctance gap 122 (step 602). The rotor laminations 120 are stacked to form the structure of the rotor 18 (step 604). The reluctance segments are aligned to define the reluctance gap 122 within the rotor 18. Opposing end laminations 124 or end caps are then disposed on the ends of the rotor 18 to close the reluctance gap 122 (step 606). As discussed herein, the closure of the reluctance gap 122 prevents the penetration of the overmold material into and occupying the reluctance gap 122. The rotor 18 is then overmolded with the overmold material (step 608). As described herein, the opposing end laminations 124 prevent the overmold material from penetrating into the reluctance gap 122. Such penetration of the overmold material may negatively impact the operation and efficiency of the reluctance gap 122 when operating in conjunction with the energized windings 14 of the stator 10 .

[0067] The assembly method for the synchronous reluctance machine 12 described herein allows the bobbin windings 14 of the machine assembly to provide additional and more efficient filling of the slots 110 of the stator 10. The configuration described herein also allows for more efficient use and easier winding of thicker gauge wire and improved slot fill rates compared to conventional pin-wound stators 10. Overmolding of the stator 10 and overmolding of the rotor 18 allow the machine 12 to be exposed to corrosive fluids without corroding the ferrous stator 10 or the ferrous rotor 18. In addition, as described herein, closing each end of the stack 28 of rotor laminations 120 prior to overmolding prevents injection molded non-metallic resin material from flowing into the reluctance gaps 122. Such infiltration may result in potential rotor imbalance. The use of overmolding relative to the rotor 18 provides a smooth overmolded surface that reduces windage noise that may be caused by the gaps 122 in the rotor 18 and eliminates "blade" drag within wet rotor designs, particularly where the gaps 122 are exposed to fluids that may cause increased drag forces on the rotor 18 when the rotor 18 is rotated in a wet rotor setting.

[0068] In addition, when the non-metallic resin material is overmolded to surround the stator 10 and windings 14, the overmold material is configured to at least partially encapsulate the inner diameter of the stator teeth 16. As described herein, this configuration provides for the use of the stator 10 in liquid and corrosive environments. The use of the overmold 46 at the inner diameter of the stator teeth 16 prevents these materials from corroding or otherwise damaging the laminations of the stator 10.

[0069] It is to be understood that changes and modifications may be made to the above described structures without departing from the inventive concepts and it is also to be understood that such concepts are intended to be covered by the following claims unless such claims expressly state otherwise by their language.

Claims

1. An electric motor, comprising: a plurality of structural rings defining a plurality of stator teeth; a tooth segment formed from a stack of laminations positioned within each of the plurality of stator teeth, wherein the stack of laminations is positioned between adjacent ones of the plurality of structural rings; a bobbin positioned on each stator tooth; winding segments, the winding segments respectively positioned on each stator tooth and about the bobbin, wherein the winding segments are coupled together to define a plurality of stator poles configured to be selectively energized; as well as An outer ring is positioned around an outer circumference of the plurality of stator teeth, wherein the outer ring defines a stator core and contains the winding segments within a stator cavity defined between the outer ring and an inner circumference of the plurality of structural rings.

2. The electric motor according to claim 1, further comprising: An overmold extends around the outer ring, the winding section, and the plurality of stator teeth.

3. An electric motor according to any one of claims 1-2, wherein the winding sections are coupled together by a winding support, the winding support defining subsets of the winding sections that are in electrical communication with each other. 4 . The electric motor of claim 3 , wherein the winding support comprises a plurality of winding connections forming the subset of the winding sections corresponding to phases of the plurality of stator poles. 5 . The electric motor according to claim 4 , wherein the plurality of winding connection portions include three winding connection portions corresponding to three phases of the plurality of stator poles.

6. The electric motor of any one of claims 1-5, 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. The electric motor of any one of claims 1-6, wherein each of the stacks of laminations comprises from about three laminations to about ten laminations, the laminations being positioned between the adjacent ones of the plurality of structural rings.

8. The electric motor of any one of claims 1-7, wherein the bobbin and the winding sections are preformed to define a plurality of bobbin assemblies, each bobbin assembly of the plurality of bobbin assemblies comprising a bobbin member and a corresponding winding section disposed on the bobbin member.

9. The electric motor of claim 8, wherein the plurality of spool assemblies are slidably mounted to corresponding stator teeth of the plurality of stator teeth.

10. The electric motor of any one of claims 1-7, wherein each bobbin comprises a multi-part bobbin slidably mounted on a corresponding stator tooth of the plurality of stator teeth.

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

12. The electric motor according to any one of claims 1 to 11, further comprising: a rotor comprising a rotor body defined by a plurality of laminations; as well as Opposed end laminations are positioned at opposite ends of the rotor body, wherein the opposed end laminations are configured to reduce windage noise during operation of the rotor within a rotor cavity defined within the plurality of stator teeth.

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

14. The electric motor of claim 13, wherein the rotor body includes a connecting web of material forming the plurality of reluctance voids, wherein the connecting web is demagnetized to reduce the reluctance of the connecting web.

15. The electric motor of any of claims 13-14, further comprising an overmold extending around the rotor body and the opposing end laminations, wherein the opposing end laminations maintain the plurality of reluctance gaps free of the overmold.

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

17. The electric motor according to claim 1, further comprising: A rotor having a plurality of reluctance gaps defined within a rotor body of the rotor and opposing end laminations enclosing the plurality of reluctance gaps within the rotor body.

18. A motor, comprising: A plurality of tooth segments, the 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; a bobbin of the plurality of bobbins, the bobbin slidably positionable on the tooth portion of the stacked tooth laminations; and a respective winding section of the plurality of winding sections, the respective winding section being positioned around the bobbin; wherein: Each tooth segment is coupled to two adjacent tooth segments to form a ring, wherein the plurality of tooth segments extend inwardly; and The plurality of winding sections are coupled to form at least one phase winding of the plurality of tooth segments, wherein the phase winding defines a plurality of stator poles configured to be selectively energized.

19. The electric machine 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 electric machine of claim 19, wherein the bobbin includes opposing end caps positioned around the tooth portion of the stacked tooth laminations.

21. An electric machine as claimed in any one of claims 18 to 20, wherein an electrically conductive material is wound around the bobbin and the tooth portion to form the respective winding sections.

22. The electric machine of any one of claims 18-21, wherein an overmold is provided on the plurality of tooth segments to form an overmolded stator.

23. The electric machine of any one of claims 18-22, wherein the plurality of winding sections are coupled together by a winding support, the winding support defining subsets of the plurality of winding sections that are in electrical communication with each other.

24. The electric machine of claim 23, wherein the winding support comprises 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 . The motor of claim 24 , wherein the plurality of winding connection portions include three winding connection portions corresponding to three phases of the plurality of stator poles.

26. The electric machine according to any one of claims 18 to 25, further comprising: a rotor comprising a rotor body defined by a plurality of laminations; as well as Opposed end laminations are positioned at opposite ends of the rotor body, wherein the opposed end laminations are configured to reduce windage noise during operation of the rotor within a rotor cavity defined within the plurality of tooth segments.

27. The electric machine of claim 26, wherein the rotor body includes a plurality of reluctance gaps defined within the plurality of laminations, and wherein the opposing end laminations enclose the plurality of reluctance gaps within the rotor body.

28. The electric machine of claim 27, wherein the rotor body includes a connecting web of material forming the plurality of reluctance voids, wherein the connecting web is demagnetized to reduce the reluctance of the connecting web.

29. The electric machine of any of claims 27-28, further comprising an overmold extending around the rotor body and the opposing end laminations, wherein the opposing end laminations maintain the plurality of reluctance gaps free of the overmold.

30. The electric machine of claim 29, wherein the overmold comprises an overmold material, the overmold material being a non-magnetic material.

31. The electric machine of claim 18, further comprising: A rotor having a plurality of reluctance gaps defined within a rotor body of the rotor and opposing end laminations enclosing the plurality of reluctance gaps within the rotor body.

32. A method for forming a stator for an electric motor, the method comprising the steps of: placing the bottom structural ring in the mold; placing a layer of stacked tooth laminations onto the base structural ring; positioning intermittent structural rings between adjacent layers of said stacked tooth laminations in an alternating configuration; placing a top structural ring on a top layer of said layers of said stacked tooth laminations to form a laminated stator; removing the laminated stator from the mold; positioning a bobbin assembly over each tooth of the laminated stator to define a segmented stator winding, each bobbin assembly comprising a bobbin member and a pre-wound winding segment; placing an outer ring around the segmented stator windings and the laminated stator; as well as The laminated stator and the segmented stator windings are overmolded with an overmolding material.

33. The method according to claim 32, further comprising the steps of: A winding support is attached to the pre-wound winding sections of the segmented stator winding to form a stator winding.

34. The method according to any one of claims 32-33, further comprising the steps of: At least a portion of the laminated stator is demagnetized.

35. The method of claim 34, wherein the demagnetizing step is performed relative to connecting portions of the bottom structural ring, the intermittent structural ring and the top structural ring, wherein the connecting portions extend between radially adjacent stacks of the layers of the stacked tooth laminations.

36. A method for forming a stator for an electric motor, the method comprising the steps of: forming a plurality of stacked tooth segments; placing a bobbin assembly onto the tooth portion of each respective one of the plurality of laminated tooth segments to define a plurality of stator segments, each bobbin assembly comprising a respective bobbin member and a respective winding section; attaching the plurality of stator segments to form a pre-wound stator core; attaching winding supports to the corresponding winding sections of the pre-wound stator core to form stator windings of the pre-wound stator core; as well as The pre-wound stator core is overmolded with an overmolding material.

37. A method according to claim 36, wherein the bobbin member includes relative end caps, which are positioned to surround the tooth portion of the corresponding stacked tooth segment among the plurality of stacked tooth segments, and wherein the winding section is wrapped around the relative end caps and the tooth portion of the corresponding stacked tooth segment.

38. The method of claim 36, wherein the step of placing the spool assembly onto the tooth portion comprises: disposing the winding sections on the spool member to define the spool assembly; as well as The spool assembly is slid around the tooth portion.

39. A method for forming a rotor for an electric motor, the method comprising: forming rotor laminations, removing a reluctance segment from each of said rotor laminations; stacking the rotor laminations to form a rotor body, wherein the reluctance segments are aligned to define a reluctance gap within the rotor body; Disposing opposite end covers on the rotor body to close the reluctance gap; as well as The rotor body is overmolded with an overmolding material, wherein the opposing end caps prevent the overmolding material from penetrating into the reluctance gap.

40. The method according to claim 39, further comprising the steps of: The reluctance section of the rotor body is demagnetized to reduce the reluctance of the reluctance section.

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