Patent Description:
Stators comprising a plurality of stator teeth for electric machines have typically been configured for external or internal rotors, and have been prepared for installation of an electric circuit (e.g., windings) using various methods. For example, in some systems, a plurality of laminates, punched or otherwise fabricated (e.g., laser cut) from a desired material (e.g., iron), may have a circular shape with a continuous <NUM> degree back iron, and include all stator teeth. These laminates are assembled together (e.g., layered) such that a completed <NUM> degree stator core results following such assembly. However, applying the electrical circuit to the teeth of a stator that has been assembled in such a way can be particularly difficult, especially where the stator is configured for internal rotor operation and/or is relatively small in size.

Another method for preparation of a stator involves segmenting the stator teeth into multiple stator segments having a back iron section and one or more teeth thereon. Each of these stator segments is formed from a plurality of laminates, each having a back iron and one or more teeth. The laminates may be assembled together (e.g., layered), resulting in a stator segment. The stator segments may then be joined (e.g., via their back irons) to form a complete stator core (i.e., <NUM> degrees around). However, such an assembly method can be difficult, because the individual laminates may not be easily stabilized and/or managed due to shape and/or size, among others.

An electrical circuit associated with the stator is typically prepared from a series of windings of wire (e.g. loops of copper wire) or other suitable material, for example, in a concentrated winding or distributed winding configuration. Where a segmented approach has been implemented, these windings may be applied prior to assembly of the individual stator segments into a complete stator. For example, each package of laminates forming a stator segment may be held in winding jig or other suitable apparatus while the windings are applied by any desired method.

It has been desirable to insulate these windings from the stator teeth and therefore, insulation is typically inserted in notches between each stator segment prior to winding. Such insulation may include sheets of paper or other suitable insulating material, which can be loose fitted into the sectors. Upon winding of the stator segment with wire, the insulation is held in place by the loops of wire forming the windings.

In addition to the insulation inserted within the sectors of each tooth, insulating members have typically also been provided at end portions of each package of laminates prior to winding for purposes of insulating the end portions associated with the stator teeth. Such end insulators may include plastic "caps" or other materials, and have been, similar to the insulating material, held in place by the windings.

Numerous issues exist with respect to current processes for manufacturing stator teeth. For example, because the completed stator is typically round in shape, the back irons of each tooth may possess a rounded bottom face, representing an arc of the circle to be formed by a surface of the completed stator. Such rounded edges may result in difficulties affixing a plurality of laminates to a single winding jig and a lack of stability during winding, among other things. In addition, because the plurality of laminates forming the teeth are sometimes not affixed to one another prior to winding, securing the plurality of laminates in a winding jig may be cumbersome and difficult to accomplish without occurrence of misalignment or loosening between laminates. This may be particularly prevalent when performing a winding process in which relatively large forces are applied (e.g., open slot needle winding process), resulting in relatively high wire tension.

Further issues may exist with regard to the insulating elements, both within the sectors of the teeth and the ends of the laminate packages. For example, because these insulating elements are typically loose fit into their respective positions prior to winding, it is possible that misalignment and/or complete separation may occur. Loss of such insulating components during the winding process may result in increased costs based on time and materials lost during the manufacturing process.

Some references describe stator laminates having notches and/or hollows made as a result of the cutting or punching process for the laminates. For example, French Patent <CIT> describes a method for manufacturing a plurality of laminates stamped from a sheet of metal to result in chains of teeth for formation into a stator. Cut outs present on a back iron having at least two stator teeth are a result of the cutting process for the laminate and are configured to enable placement of spacing members around a periphery of the stator. Likewise, Japanese Patent Application <CIT> describes hollows present on a single back iron having three stator teeth, for maximizing yield of a particular sheet of metal. However, neither of these references address the winding problems discussed above.

<CIT> describes methods and apparatus for wire winding and fabrication for electric machines using a plurality of holding members. However, these methods and apparatus do not address the desire to utilize a single winding jig with a plurality of packages mounted thereto in a simple and efficient configuration, nor do they address issues associated with retaining the insulating elements.

<CIT> describes an apparatus for winding stator teeth. However, the teeth are held spaced apart in a movable winding jig. Such a configuration provides little if any assistance with the cumbersome task of assembling a plurality of loose laminates for winding or the problems associated with the insulating materials described above.

<CIT> discloses that a stator core comprising mutually mating upper and lower end caps. The upper and lower end caps have partially overlapping thin parts in close contact respectively with the stator core and the windings.

<CIT> discloses a stator assembly having discrete stacks of laminations received in a plurality of nonmagnetic containment structures and coupled to one another by the containment structures.

<CIT> discloses stator teeth having convex portions at tooth side faces to prevent inclination of bobbin wound onto the stator teeth.

<CIT> discloses a wire-winding machine for forming coils on individual pole teeth of a core member. The core member comprises a locking groove formed on a yoke portion thereof, the locking groove locking on a rotating roller of the machine.

<CIT> discloses a stator segment having a groove for receiving a claw-like jig during winding.

Accordingly, there exists a need for systems and methods for winding stator teeth that results in relatively easy assembly of laminations and a firm holding of the laminations, while also providing systems for holding desired insulations in place during the winding process.

According to one aspect, the present invention is related to a stator core according to one of claims <NUM> to <NUM>.

According to another aspect, the present invention is related to a method for winding a stator core according to claim <NUM>.

According to another aspect, the present invention is related to a system according to one of claims <NUM> to <NUM>.

The stator segment includes only one tooth section and a back iron section, the back iron section having a retainer interface presenting a dovetail shape.

Stator teeth configured in such an arrangement may ease the task of assembling stator segment laminates and further provide secure retention of such laminates during winding, leading to less waste during manufacture due to such things as improper alignment during assembly, misalignment of laminates during winding, and bending of laminates, among other things.

In some embodiments, the stator segment further comprises a plurality of stator laminates comprising a magnetic material.

The retainer interface is located at a peripheral surface of the back iron and may comprise a channel open to three surfaces of the back iron section.

In some embodiments, an axis of symmetry associated with the retainer interface is substantially co-linear with an axis of symmetry associated with the tooth section.

An end cap is also provided. The end cap may comprise an end cap dovetail interface, the end cap interface being at least partially dovetailed in shape and configured to substantially coincide with a periphery of the retainer interface.

In some embodiments, the stator segment may comprise an aperture on a face of the stator segment forming an end cap aperture interface and a stator segment engaging portion associated with the end cap and configured for engaging the end cap aperture interface.

An axis of symmetry associated with the end cap aperture interface or the end cap dovetail interface may be substantially co-linear with an axis of symmetry associated with the stator segment.

The end cap includes an electrically non-conductive material, such as an injection molded plastic material. The end cap further includes an insulator engaging segment, which may include one or more protrusions configured to exert a force on one or more insulating materials.

The stator core comprises a plurality of the stator segments described above and assembled together.

The method for winding a stator segment includes retaining one or more stator segments via their retainer interfaces, and winding one or more coils of wire around the tooth section of each of the one or more stator segments.

The stator segment and retainer system include a retainer having a dovetail shape and a stator segment formed from a plurality of stator laminates. The stator segment includes a tooth section and a back iron section, the back iron section having a retainer interface. The retainer interface has a dovetail shape and is configured to receive the retainer, the retainer being configured to interface with a winding jig and the retainer interface such that the plurality of stator laminates remains in a substantially fixed position on the winding jig during a winding process.

Such a system may aid operators and or machines tasked with assembling stator laminates and winding stator teeth based on the ability to easily assemble laminates on a winding jig and subsequently transport the winding jig comprising any number of assembled stator teeth to a winding machine or, for example, test bench. Such a system may further reduce improper alignment during assembly, misalignment of laminates during winding, and bending of laminates, among other things.

In some embodiments, the retainer is affixed to the winding jig, and may be monolithically formed with the winding jig.

In some embodiments, interaction between the retainer interface and the retainer results in an interference fit between at least one of the plurality of stator laminates and the winding jig.

The retainer interface is a cut-out dovetail shape.

The end cap may include an end cap dovetail interface being dovetail in shape and/or a stator segment engaging portion and an insulator engaging segment configured to engage one or more insulating materials.

End caps configured according to the present disclosure may provide added stability with regard to assembled and wound stator segments based on the forces applied by the windings through the end caps. Further, because such end caps are configured to remain firmly in place during winding operations, chances of misalignment are substantially reduced.

In addition, such configurations enable the continued use of insulating elements loose fit into respective notches between stator teeth prior to winding, thanks to the insulation engaging segment provided. Such a segment being configured to hold insulating materials in place, thus reducing occurrence of costly misalignments and/or separations. Thus, stator manufacturing costs may be reduced based on, for example, reduced waste.

The end cap may comprise injection molded plastic material, and the insulator engaging segment may include a tab extending away from a face of the end cap, the face being configured to interface with an end portion of a stator segment.

Various stator embodiments may be implemented for utilization in electric machines, for example, electric motors, generators, or other electric devices, and are used in conjunction with a rotor among other components for purposes of performing various operations (e.g., performing work, generating electrical current, etc.) Such stators therefore, may include stator segments (e.g., comprised of a plurality of laminates) having a back iron and a tooth section, windings, and insulating elements, among other things.

<FIG> is an illustration of an exemplary winding jig <NUM> with a plurality of stator segments <NUM> (formed from stator segment laminates <NUM>) mounted thereon, in preparation of winding, <FIG> being consistent with embodiments of the present disclosure. Winding jig <NUM> may include, for example, a mount plate <NUM>, stator segment retainers <NUM>, as well as various jig fixtures <NUM>, among others. The general configuration of winding jig <NUM> is intended as exemplary only, and one of skill in the art will recognize that various embodiments of winding jig <NUM> could be implemented in accordance with the present disclosure.

Mount plate <NUM> is configured to receive one or more stator segment retainers <NUM> such that stator segments <NUM> are retained on mount plate <NUM>, and therefore winding jig <NUM>. Mount plate <NUM> may be fabricated from any suitable material (e.g., metal, plastic, etc.) and of any suitable size (e.g., having a width W) based on, for example, a number of stator teeth to be wound and a size of such stator teeth. Mount plate <NUM> may include numerous features <NUM> enabling transport of winding jig <NUM> and/or attachment of winding jig <NUM> to a winding machine. Features <NUM> may include various fasteners, connection points, etc. as desired for a particular winding application. One of skill in the art will recognize that the nature and position of features <NUM> may vary according to, for example, transport method, application, and/or winding machine, among other considerations. Thus, any such configuration is intended to fall within the scope of the present disclosure.

One of skill in the art will recognize that mount plate <NUM> may further include additional features to facilitate assembly of stator segments <NUM> using stator segment laminates <NUM> (e.g., contoured surfaces). For example, as shown in <FIG>, a contoured concave surface is provided on a face of mount plate <NUM> to facilitate receiving a convex rounded surface of a back iron <NUM> of a stator segment <NUM>. Such a contour may be of any desirable size and shape to facilitate receipt of various sizes and shape of back iron <NUM> associated with a stator segment <NUM>. For example, such a contour may be convex and configured to receive a concave surface of a back iron <NUM>.

Stator segment retainers <NUM> are configured to interface (e.g., receive and retain) a plurality of stator segment laminates <NUM> (shown in <FIG>) and to substantially hold stator segment laminates <NUM> in place on winding jig <NUM> during a winding process (e.g., open slot needle winding, bobbin winding, etc.). For example, stator segment retainers <NUM> may comprise one or more lengths of material suitable for interfacing with and retaining laminates (e.g., steel, aluminium, plastics, etc.), the length of material having a substantially "dovetail" shape and may include, for example, tapered sections <NUM> designed to facilitate receipt of one or more laminates <NUM>. One of skill in the art will recognize that the term "dovetail" as used herein, is derived generally from a class of joints, wherein the joints are formed via complementary male and female portions each having a substantially complementary shape (e.g., trapezoidal, diamond, oval, etc.) configured to cooperate with its counterpart to provide forces and/or counter forces that result in at least partial affixing of the two parts. In other words, as a result of joining the male and female portions, forces may result such that the male and female portions may remain joined. The male portion comprises a material while the female portion comprises a void of material (i.e., a groove or notch) each having a shape complementing the other. <FIG> are illustrations of exemplary shapes of male (M) and female (F) portions of a "dovetail" joint for purposes of the present disclosure. One of ordinary skill in the art will recognize that any shape combination comprising male and female portions of complementary shapes resulting in cooperation causing at least partial affixing between two parts is intended to fall within the scope of the present disclosure.

One or more stator segment retainers <NUM> may extend along width W of mount plate <NUM> and are affixed to mount plate <NUM> in any suitable fashion resulting in substantial immobility for stator segment retainers <NUM>. For example, stator segment retainers <NUM> may include one or more fasteners (e.g., reusable screws), clips (e.g., integrally fabricated with stator segment retainer <NUM>), and/or other gripping members configured to engage mount plate <NUM>. In some embodiments, stator segment retainers <NUM> may be operably engaged within mount plate <NUM> to allow movement of stator segment retainers <NUM> along an axis Y, which may correspond with axis of substantial symmetry S (discussed below). <FIG> shows a cross section of a portion winding jig <NUM> including stator segment retainers <NUM> operably engaged with mount plate <NUM>. In such embodiments, stator segment retainers <NUM> may extend through mount plate <NUM> along axis Y such that a dovetail portion is presented on a first face of mount plate <NUM>, with a force receiver portion <NUM> located near a second face (e.g., bottom) of mount plate <NUM>. This may allow the fixing portion <NUM> to engage with a force generating apparatus (e.g., machinery, tensioning bolts, etc.) to exert a force (e.g., slidable pulling) on laminates <NUM> when mounted on stator segment retainers <NUM>. For example, force receiver portion <NUM> may engage a machine (not shown) capable of causing a suitable force (e.g., a pulling) to be exerted on force receiver portion <NUM>, which may, in turn, result in a force being applied through stator segment retainer <NUM> on stator segment <NUM> and its associated laminates <NUM> that have been mounted on stator segment retainer <NUM> (e.g., via the dovetail of back iron <NUM>). Any suitable machine may be used, for example, pneumatic, hydraulic, mechanical (e.g., screw tensioner), etc..

In some embodiments, stator segment retainers <NUM> may also be affixed by heat (e.g., spot welded) and/or clipped to mount plate <NUM>. Alternatively, in some embodiments, stator segment retainers <NUM> may be integrally (e.g., monolithically) fabricated with mount plate <NUM>, for example, by a machining process configured to remove material from mount plate <NUM> resulting in formation of dovetail shaped stator segment retainers <NUM> on a surface of mount plate <NUM>. Various methods may be used for fabricating stator segment retainers <NUM> in conjunction with mount plate <NUM> (e.g., a molding process), all of which are intended to fall within the scope of the present disclosure.

Stator segment retainers <NUM> are spaced along a length of mount plate <NUM> according to various considerations such as laminate construction (e.g., continuous or individual), the number of laminates associated with a stator, winding method (e.g., open slot needle winding), winding type (e.g., concentrated or distributed winding), stator and/or tooth size (e.g., radius of curvature), and winding machine characteristics, among other things. In some embodiments, such spacing may be adjustable, for example, where clips or other reusable fasteners are used for affixing stator segment retainers <NUM> to mount plate <NUM>. In such embodiments, based on various factors, a user may position stator segment retainers <NUM> at any desired position along the length of mount plate <NUM> for affixing. Additionally, this may allow multiple sets of stator segments associated with one or more stators to be affixed to mount plate <NUM> and wound simultaneously, thereby resulting in potential cost savings.

<FIG> illustrate exemplary stator segment laminates <NUM>, a plurality of which are assembled for purposes of forming a complete stator segment <NUM> (e.g., assembly via mounting on stator segment retainers <NUM>). Stator segment laminates <NUM> include a distal end also known as a tooth <NUM>, a back iron <NUM> from which tooth <NUM> extends, and, in some embodiments, interconnecting segments <NUM> and <NUM>, among others. In some embodiments, such as those shown in <FIG>, tooth <NUM> may include pole shoes <NUM>, configured to support one or more windings associated with stator segment <NUM>, among other things. It is important to note that pole shoes <NUM> may or may not be implemented as desired, and are intended as exemplary only.

Stator segment laminates <NUM> are fabricated from any suitable material (e.g., magnetic materials such as steel, iron, etc.) and may be stamped, machined, and/or otherwise manufactured in any desired size and shape. Sizing, design, and fabrication of stator segment laminates <NUM> may take into consideration various factors such as strength, weight, magnetic flux, eddy current generation, cooling, and motor size, among other things.

In some embodiments, a shape associated with stator segment laminates <NUM> may be determined based on a motor configuration. For example, where a stator is configured to be implemented with an external rotor, back iron <NUM> may have a substantially convex shape relative to tooth <NUM>. In another example, where a stator is configured for implementation with an internal rotor, back iron <NUM> may have a substantially concave shape relative to tooth <NUM>, as shown in <FIG>. A radius of curvature associated with back iron <NUM> may further be based on design considerations such as rotor size, number of stator teeth, and desired power, among other things.

In embodiments including interconnecting segments <NUM> and <NUM>, joining of each back iron <NUM> of a stator segment <NUM> to another can be facilitated. In such embodiments, a first interconnecting segment <NUM> may possess a groove, channel, or punch-out configured to interface with a protrusion present on second interconnecting segment <NUM>. For example, shapes associated with interconnecting segments <NUM> and <NUM> may include shapes shown in <FIG> (e.g., semicircles and angular shapes). In addition, shapes may include those described with regard to the "dovetail" described herein. Thus, upon joining of two or more stator segments <NUM>, first interconnecting segment <NUM> engages second interconnecting segment <NUM> to facilitate alignment and assembly of the stator, among others. Such an arrangement may be present both with individual stator segment laminates, and laminates manufactured as a pre-connected strand of laminates.

Side faces of back iron <NUM>, and/or faces of interconnecting segments <NUM> and <NUM> (when present), maintain a predetermined angle α between their faces such that upon assembly, a stator of a desired diameter is formed. Such an angle may be based on the number of stator segments <NUM> to be included with the stator (e.g., where <NUM> stator teeth are to be included, α equals <NUM> degrees).

Each stator segment laminate <NUM> may have an axis of substantial symmetry S, about which each stator segment laminate <NUM>, and therefore, tooth <NUM>, is substantially symmetric. In some embodiments, some deviation from symmetry may occur, for example, to allow for alternating positioning of interconnecting segments <NUM> and <NUM> associated with stator segment laminates <NUM>, facilitating interconnectivity of stator teeth, among other things. One of skill in the art will understand that substantial symmetry should be considered as existing about axis S, in view of such a configuration.

In some embodiments, stator segment laminates <NUM> may include individual laminations and/or modular laminations machined as a continuous "strand" interconnected by pieces of material (e.g., hinged) using various manufacturing techniques.

To enable stator segment laminates <NUM> to be aligned and assembled along a stator segment retainer <NUM>, back iron <NUM> of stator segment laminate <NUM> includes a dovetail retainer interface <NUM>, among other things. For example, during a fabrication process for stator segment laminates <NUM>, or separately therefrom, material can be removed (e.g., cut out) from back iron <NUM> such that a dovetail void (i.e., female portion) is formed in back iron <NUM>. In some embodiments, such retainer interfaces <NUM> comprise a channel or hole open to three surfaces of the back iron section (e.g., a front face, a back face, and a bottom or periphery).

Retainer interface <NUM> may be configured such that when mounted on a stator segment retainer <NUM>, an interference fit may result, thereby enabling additional retentive forces on stator segment laminate <NUM>. For example, clearances between winding jig <NUM> and a bottom face of stator segment laminate <NUM> at a location near retainer interface <NUM> may be negative upon installation of stator segment laminate <NUM> on stator segment retainer <NUM>, thus resulting in compressive forces applied between the two parts, and thus additional retention. Additionally, as described above, such forces may be enhanced where stator segment retainers <NUM> are operably engaged within mount plate <NUM> and configured to engage a force providing machine.

While the present disclosure focuses primarily on embodiments wherein back iron <NUM> includes female portion F of a dovetail, in some embodiments, it may be desirable to implement an inversion, wherein back iron <NUM> includes male portion M of the dovetail. In such embodiments, stator segment retainers <NUM> can be implemented as grooves and/or channels forming the female portion F. For example, mount plate <NUM> may include a series of dovetail channels having a complementary shape to a shape of material present on back iron <NUM> of stator segment laminate <NUM>. One of ordinary skill in the art will recognize that such an implementation is intended to fall within the scope of the present disclosure.

In some embodiments, an axis of symmetry associated with retainer interface <NUM> may be substantially co-linear with axis of symmetry S associated with stator segment <NUM>. For example, retainer interface <NUM> may be aligned so as to maintain substantial symmetry of stator segment laminate <NUM>. One of ordinary skill in the art will recognize that retainer interface <NUM> may be located in any desired location associated with stator segment laminate <NUM>, particularly on back iron <NUM>.

Retainer interfaces <NUM> may serve additional purposes during operation of an assembled stator. <FIG> is a planar sectional illustration of an exemplary gap <NUM> implemented utilizing retainer interfaces <NUM> following assembly of stator core <NUM>, consistent with embodiments of the present disclosure. End caps <NUM> and windings are not shown in <FIG> for purposes of clarity. As shown, spacers <NUM> may comprise dovetail lengths of material, similar to stator segment retainers <NUM>, and may be inserted into retainer interfaces <NUM> prior to installation of stator casing <NUM> for purposes of forming a gap or channel <NUM> between stator casing <NUM> and back irons <NUM>. It may then be possible to cause a fluid (e.g., air) to flow between stator casing <NUM> and back irons <NUM> during operation of the stator for various purposes, such as, for example, cooling. Additionally, spacers <NUM> may be made hollow incorporating a cooling passage <NUM> such that a fluid (e.g., air) may be passed through the hollow lengths of material, resulting in enhanced cooling of the stator. One of ordinary skill in the art will recognize that numerous configurations may be implemented with regard to retainer interfaces <NUM> for various purposes, such as, cooling, eddy current control, etc. All such implementations are intended to fall within the scope of the present disclosure.

In some embodiments, each front and back face of back iron <NUM> may further include one or more end cap aperture interfaces <NUM>. End cap aperture interface <NUM> may be configured to interface with a stator segment end cap <NUM> (not shown in <FIG>) to facilitate holding of end cap <NUM> in place, e.g., during a winding process, among other things. As shown in <FIG>, end cap aperture interface <NUM> may comprise an aperture or hole of a desired shape and size placed in a desired location on stator segment laminate <NUM>, particularly back iron <NUM>. For example, end cap aperture interface <NUM> may be a circular, semi-circular, square, trapezoidal, triangular, or any other desired shape void or protrusion. In some embodiments, end cap aperture interface <NUM> may comprise a semi-circular void positioned in association with retainer interface <NUM>. In such an example, an axis of symmetry associated with end cap aperture interface <NUM> may be substantially co-linear with axis of symmetry S associated with stator segment laminate <NUM> (and therefore stator segment <NUM>) and/or an axis of symmetry associated retainer interface <NUM>. Alternatively, end cap interface <NUM> may be positioned independently of retainer interface <NUM>, as desired.

In some embodiments, a predetermined number of stator segment laminates <NUM> associated with a stator segment <NUM> may include end cap aperture interface <NUM>, for example, where end cap interface comprises a hole. In such an embodiment, stator segment laminates <NUM> including end cap aperture interface <NUM> may be positioned at a first end of stator segment <NUM> and at a second end of stator segment <NUM>. For example, X number of stator segment laminates <NUM> including an end cap aperture interface <NUM> configured as a void may be placed on stator segment retainer <NUM>, followed by a predetermined number of stator segment laminates <NUM> not including end cap aperture interface <NUM>, followed by another X number of laminates including end cap aperture interface <NUM>. Thus, the result may be a blind hole or aperture on each face of back iron <NUM>. Alternatively, where all stator segment laminates <NUM> include an end cap aperture interface <NUM> having a void, a through hole or aperture may result in back iron <NUM>.

Although not shown, in some embodiments, end cap aperture interface <NUM> may alternatively comprise a protrusion extending from back iron <NUM>. For example, stator segment laminates <NUM> may comprise an aperture, which, when stator segment laminates <NUM> are assembled, forms a hole extending through the length of stator segment <NUM>. A rod or other device may be inserted through this hole, for example, to introduce additional forces on stator segment laminates <NUM>, and also extending beyond the length of stator segment <NUM>. Such extension may result in a protrusion on a face of stator segment <NUM>, which may be caused to interface with an aperture on end cap <NUM> for example. One of ordinary skill in the art will recognize that other similar configurations may be implemented, for example, injection molding of plastic through the hole in stator segment <NUM>, resulting in protrusions on faces of stator segment <NUM>.

While the discussion herein is directed to the presence of a single end cap aperture interface <NUM>, more than one end cap aperture interface <NUM> may be present at various locations on a face of stator segment <NUM>. Each of such end cap aperture interfaces <NUM> may vary in size and shape, and may be configured for interfacing a corresponding tooth engaging segment <NUM> on end cap <NUM>.

<FIG> is an exemplary end cap <NUM> consistent with embodiments of the present disclosure. End cap <NUM> is configured for insulating end portions of stator segments <NUM>, supporting windings about stator segments <NUM> (windings not shown), and applying forces associated with the windings for maintaining stator segment laminates <NUM> in place, among other things. End cap <NUM> comprises any suitable insulating material, for example, a plastic (e.g., injection molded plastic), a ceramic, and/or a composite, and may be of any desired shape, particularly in view of a geometry associated with stator segments <NUM>.

End cap <NUM> may include a tooth engaging segment <NUM>, insulation engaging segments <NUM>, end cap face <NUM>, and winding stops <NUM>, among other things (e.g., wire guides). End cap face <NUM> may present tooth engaging segment <NUM>, and may therefore be configured to bear upon a face of stator segment <NUM>. End cap face <NUM> may be substantially flat and/or matching contours associated with the face of stator segment <NUM> on which it is to bear. Winding stops <NUM> may be configured to provide support for windings (not shown) on stator segment <NUM>, particularly where such winding may have a tendency to slip or otherwise dislodge from an initially wound position.

Tooth engaging segment <NUM> is configured to engage end cap aperture interface <NUM> present on back iron <NUM> and/or stator segment <NUM>. Therefore, tooth engaging segment <NUM> may comprise a protrusion or other suitable feature (e.g., hole/aperture) facilitating engagement with end cap aperture interface <NUM>. For example, where a semi-circular end cap aperture interface <NUM> having a radius R has been provided on a first face of stator segment <NUM>, a semi-circular protrusion having a radius approximately equal to or slightly smaller than R can be provided as tooth engaging segment <NUM> on end-cap <NUM>. Such a protrusion may be molded or otherwise fabricated on end cap <NUM>, or in some embodiments, may be fastened to end cap <NUM>.

While the discussion herein is directed to the presence of a single tooth engaging segment <NUM>, more than one tooth engaging segment <NUM> may be present on end cap <NUM>. Each of such tooth engaging segments <NUM> may vary in size and shape, and may be configured for interfacing a corresponding end cap interface on back iron <NUM> and/or stator segment <NUM>. For example, there may be <NUM>, <NUM>, <NUM>, or more tooth engaging segments present on end cap <NUM>, as desired.

Insulation engaging segments <NUM> are configured to interface with and retain insulating material <NUM> (shown in <FIG>) inserted between stator segments <NUM> and stator windings (not shown). Insulation engaging segments <NUM> therefore comprise one or more protrusions, tabs, extensions, or other suitable configurations molded with or otherwise affixed to end cap <NUM>. Insulation engaging segments <NUM> are aligned such that at least a portion of insulation engaging segments <NUM> extends along a length of stator segment <NUM> upon engagement of tooth engaging segment <NUM> and end cap aperture interface <NUM>. For example, insulation engaging segments <NUM> may be sloped such that, upon installation of end cap <NUM> on stator segment <NUM>, insulation engaging segments <NUM> project substantially parallel to pole shoes <NUM> (when present) and exert a force against pole shoes <NUM> (e.g., perpendicular to a surface of pole shoes <NUM>). In another example, insulation engaging segments <NUM> may be configured to run parallel to tooth <NUM> exerting a force against tooth <NUM> (e.g., perpendicular to a surface of tooth <NUM>) such that any inserted insulating material <NUM> may be retained.

<FIG> is an exemplary representation of an end-cap installed on an end portion of stator segment <NUM>. As can be seen in <FIG>, tooth engaging segment <NUM> may be engaged within end cap aperture interface <NUM>, and insulation engaging segments <NUM> may be configured to contact or otherwise exert forces on insulating material <NUM> located between insulation engaging segments <NUM> and, for example, pole shoes <NUM> and/or tooth <NUM>. For example, one or more layers of insulating material <NUM> (e.g., electrically non-conductive materials such as papers, plastics, composites, etc.) may be placed in contact with stator segment <NUM> between stator pole shoe <NUM> (when present) and/or tooth <NUM>, and back iron <NUM>. Following placement of such insulating material <NUM> (not shown in <FIG>), end cap <NUM> may be positioned such that insulation engaging segments <NUM> slide over and press against insulating material <NUM>, thereby resulting in substantial retention of insulating material <NUM> in a predetermined location.

<FIG> is an illustration of an alternative end cap <NUM> in elevation and three-dimensional view, consistent with embodiments of the present disclosure. In such embodiments, end cap <NUM> may include an end cap dovetail interface <NUM> similar to retainer interface <NUM> provided on stator segment laminates <NUM>, i.e., a dovetail shaped channel, groove, or hole configured to interface with stator segment retainers <NUM>. End cap dovetail interface <NUM> may be present in conjunction with, or in lieu of, tooth engaging segment <NUM>. Therefore, end cap dovetail interface <NUM> may be configured to interface with stator segment retainers <NUM>, thereby allowing installation of end-cap <NUM> in a similar manner to assembly of stator segment laminates <NUM> (e.g., align and press in place).

Notably, it may be desirable in some embodiments to injection mold end caps <NUM> in contact with stator segments <NUM>. For example, stator segments <NUM> mounted on mouting jig <NUM> may be inserted into a mold configured to receive such a device. Subsequently, insulating material <NUM> and end caps <NUM> may be injection molded using a thermoplastic or other suitable material to effectively encase portions of stator segments <NUM> thereby forming end caps <NUM>.

Systems and methods of the present disclosure may enable the manufacture of an electric device stator, facilitating increases in manufacturing efficiencies and reduction in assembly time and waste, among other things. <FIG> is a flowchart <NUM> of an exemplary method for preparation of winding stator teeth consistent with embodiments of the present disclosure. For purposes of clarity, <FIG> will also be referenced during the following discussion. Upon obtaining a desired number of stator segment laminates <NUM> and a mount plate <NUM> with stator segment retainers <NUM> suitably mounted thereon (e.g., clipped), stator segment laminates <NUM> may be loaded onto stator segment retainers <NUM> via retainer interfaces <NUM> (step <NUM>). For example, stator segment laminates <NUM> may be aligned with stator segment retainers <NUM> such that a pressing motion may be used to cause engagement of retainer interfaces <NUM> with stator segment retainers <NUM> along width W of mount plate <NUM>. If desired, such assembly of a stator segment laminate <NUM> onto a segment retainer <NUM> may result in an interference fit between stator segment laminate <NUM> and at least one of winding jig <NUM> and stator segment retainer <NUM>.

In some embodiments, stator segment laminates <NUM> may be placed one by one, or grouped in any desired combination. Further, it may be possible to assemble stator segment laminates <NUM> onto stator segment retainer <NUM> prior to affixing to mount plate <NUM>, where desired. Additional stator segment laminates <NUM> may be assembled along stator segment retainer <NUM> until a desired tooth size has been attained. A number of stator segment laminates <NUM> used for assembly of stator segment <NUM> may be based on the thickness of the laminates for example. This operation may be repeated as desired to prepare a desired number of stator teeth for winding upon winding jig <NUM>.

Notably, loose stator segment laminates <NUM> may be supplied as a loosely corresponding stack at any specified length with temporary holding materials to maintain correspondence between stator segment laminates <NUM> within the stack (e.g., tape, elastic, tie wraps, etc). Such a process may even be used during prototyping, thus enabling manufacture via lamination-punch tooling or, if desired, lasercut laminations. Such an arrangement may further facilitate loading onto stator segment retainers <NUM>, with the temporary holding materials removed prior to winding.

In some embodiments, following placement of a desired number of stator segment laminates <NUM> on stator segment retainers <NUM>, mount plate <NUM> may be engaged with a machine configured to introduce force to force receiver portion <NUM> for purposes of applying a force to retain stator segments <NUM> via retainer interfaces <NUM> (step <NUM>). For example, mount plate <NUM> may be engaged on a pneumatic machine configured to generate a pulling force on force receiver section, thereby resulting in a force operating on stator laminates <NUM> through retainer interfaces <NUM>.

Innsulating material <NUM> may then be placed in desired locations associated with stator segments <NUM> (step <NUM>). For example, <FIG> shows an exemplary configuration for insulating material <NUM>, wherein insulating material <NUM> comprises, for example, a paper sheet that has been pre-folded to a desired shape, thereby facilitating insertion of insulating material <NUM> into spaces between stator segments <NUM> (e.g., between pole shoes <NUM> and back irons <NUM>). Step <NUM> may be repeated as desired for purposes of placing a suitable amount of insulating material (e.g., between each stator segment <NUM> to be wound).

Following installation of insulating material <NUM>, end caps <NUM> may be aligned and installed on stator segments <NUM> and/or stator segment retainers <NUM> (step <NUM>). For example, end caps <NUM> may be aligned such that a sliding motion may cause engagement of end cap dovetail interface <NUM> and stator segment retainers <NUM>, and/or tooth engaging segment <NUM> and end cap aperture interfaces <NUM>. In some embodiments, interference fitting may occur between portions of end caps <NUM> (e.g., end cap dovetail interface <NUM>) and respective surfaces of stator segment <NUM> and/or jig <NUM>. <FIG> is an exemplary illustration of end cap <NUM> installation, showing end cap dovetail interface <NUM> engaged with stator segment retainers <NUM> and insulation engaging segments <NUM> engaged with insulating material <NUM>.

With end caps <NUM> installed, winding jig <NUM> may be affixed to a winding machine and/or otherwise transported/placed in preparation for winding (e.g., an open slot needle winding process) (step <NUM>).

Winding, as used herein, should mean any process whereby electrical coils are installed on a stator segment <NUM>. For example, winding may take place using a machine rotating about an axis and dispensing wire around the surface of stator segment <NUM>. Alternatively, for example where pole shoes <NUM> are absent, prefabricated coils or "windings" (i.e., wire already prepared as a desired number of loops) may be inserted on tooth <NUM> and secured in place via any suitable method (e.g., adhesive, interference fit, etc.).

Once stator segments <NUM> have been assembled and wound, the individual teeth may be removed from winding jig <NUM> (e.g., force released and stator segments <NUM> removed from stator segment retainers <NUM>) and assembled into a complete stator core. For example, each stator segment <NUM> may be joined to another stator segment <NUM> via interconnecting segments <NUM> and <NUM>. Following assembly into a stator core, and where desired, spacers <NUM> may be inserted into retainer interfaces <NUM>, and stator casing <NUM> may be installed.

Claim 1:
A stator core comprising a plurality of stator segments assembled together, each stator segment comprising:
only one tooth section (<NUM>);
a back iron section (<NUM>), the back iron section comprising a retainer interface (<NUM>) being a cut-out having a dovetail shape, the retainer interface being located at a peripheral surface of the back iron; and
an end cap (<NUM>) comprising an electrically non-conductive material,
characterized in that the end cap comprises an insulator engaging segment (<NUM>) for retaining one or more insulating elements (<NUM>) loose fit into respective notches between stator teeth prior to winding,
wherein the end cap comprises an end cap dovetail interface (<NUM>), the end cap dovetail interface (<NUM>) being at least partially dovetail in shape and being a dovetail shaped groove, and wherein a periphery of the end cap dovetail interface is configured to coincide with a periphery of the retainer interface (<NUM>).