Stator bus ring assembly

Abstract

A stator bus ring assembly having an annular plastic housing and a plurality of bus rings arranged concentrically in the housing. Each of the bus rings is formed from one or more lengths of coated flat wire having a metal conductor coated with one or more layers of one or more insulating coatings. Each bus ring has a width-to-thickness ratio of from about 2 to about 8. A plurality of attachment structures is secured to each of the bus rings, such as by laser welding. The attachment structures extend from the housing and are configured for securement to wires of stator coils, respectively.

Description

STATOR BUS RING ASSEMBLYCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No.: 63 / 524,829 filed on 3 July 2023, which is herein incorporated by reference.TECHNICAL FIELD

[0001] This disclosure relates generally to the layout of electrical busbars that connect power input terminals to field windings of a multi-phase motor.BACKGROUND

[0002] A conventional brushless AC motor generally includes a cylindrical stator surrounding a rotor, which is secured to a motor shaft. Three-phase stator coils are wound around segments of a core of the stator. The stator coils are arranged around the rotor, which may have windings, permanent magnets or a squirrel cage metal rods. The stator windings are connected to a source of three-phase AC power. When the stator windings are provided with AC power, a rotating magnetic field is created, thereby causing the rotor and, thus, the motor shaft to rotate.

[0003] Often, AC power is provided to the stator coils through a stator bus ring assembly, which is positioned above the core and coils of the stator. A conventional stator bus ring assembly typically includes over-molded busbars disposed in a housing. The busbars must carry large motor currents, while being isolated at high voltages and temperatures. These constraints coupled with the limited space available in the housing presents challenges in manufacturing a conventional stator bus ring assembly.SUMMARY

[0004] In accordance with the disclosure, a stator bus ring assembly is provided having a housing and a plurality of bus rings arranged concentrically in the housing. Each bus ring is formed from one or more lengths of coated flat wire having a metal conductor coated with one or more layers of one or more insulating coatings. Each busring has a width-to-thickness ratio of from about 2 to about 8. Attachment structures are secured to each of the bus rings. The attachment structures extend from the housing and are configured for securement to wires of stator coils, respectively, to electrically connect the bus rings to the stator coils.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:

[0006] Fig. 1 shows a top perspective view of a first stator bus ring assembly constructed in accordance with a first embodiment;

[0007] Fig. 2 shows a portion of the first stator bus ring assembly, wherein a portion of a housing of the first stator bus ring assembly is broken-away to show the interior thereof in which bus rings are mounted in a groove of the housing;

[0008] Fig. 3 shows a portion of one of the bus rings in which a recess has been made in an exterior edge thereof;

[0009] Fig. 4 shows a laser beam welding a base of an attachment structure after it has been inserted into the recess formed in the bus ring, which is shown in Fig. 3;

[0010] Fig. 5 shows a length of coated flat wire that has been bent to form a semicircular bus portion;

[0011] Fig. 6 shows a top perspective view of a second stator bus ring assembly constructed in accordance with a second embodiment;

[0012] Fig. 7 shows a top perspective view of a portion of a housing of the second stator bus ring assembly;

[0013] Fig. 8 shows a sectional perspective view of a portion of the second stator bus ring assembly;

[0014] Fig. 9 shows a perspective view of components of the second stator bus ring assembly, namely an attachment structure spaced above a recess formed in a bus ring; and

[0015] Fig. 10 shows components of the second stator bus ring assembly, namely a neutral structure spaced above a portion of bus rings to which attachment structures are secured.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0016] It should be noted that in the detailed description that follows, identical components have the same reference numerals, regardless of whether they are shown in different embodiments of the present disclosure. It should also be noted that for purposes of clarity and conciseness, the drawings may not necessarily be to scale and certain features of the disclosure may be shown in somewhat schematic form.

[0017] Spatially relative terms, such as "top", "bottom", "lower", "above", "upper", and the like, are used herein merely for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as they are illustrated in (a) drawing figure(s) being referred to. It will be understood that the spatially relative terms are not meant to be limiting and are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings.

[0018] Referring now to Fig. 1 , there is shown a stator bus ring assembly 10 constructed in accordance with a first embodiment. The stator bus ring assembly 10 distributes AC power to coils of a stator (not shown) of an electric motor. The stator bus ring assembly 10 may be mounted on top of a core of the stator, above the stator coils. The stator bus ring assembly 10 includes an outer ring-shaped plastic housing 12 that encloses three bus rings 14 electrically connected to three terminals 15, respectively. The terminals 15 are for connection to an external three-phase AC power supply. The bus rings 14 are physically and electrically connected to an array of attachment structures 16, which are connected to stator coils (not shown).

[0019] Referring now also to Figs. 2 and 3, each of the bus rings 14 is circular and may be formed from one or more lengths of coated flat wire 18 that is / are bent or otherwise configured to have an arcuate shape, e.g., circular, semicircular or a quartercircle. Thus, by way of example, if a bus ring 14 is formed from two lengths of coated flat wire 18, the two lengths of coated flat wire 18 are bent to be semicircular and then are connected together to form a circle.

[0020] The coated flat wire 18 and, thus, each bus ring 14, includes a metal conductor 20 covered with one or more layers of one or more insulating coatings 22. The conductor 20 may comprise copper, a copper alloy or aluminum. The conductor 20 may be produced to have a dead-soft temper, i.e., ASTM 070, which is the maximum softness commercially available. Insulating coatings 22 that may be used include a polyurethane enamel, a polyamide-imide enamel, a polyvinylformal enamel and a THEIC-modified polyester enamel. Polytetrafluoroethylene or a silicone elastomer may also be used as an insulating coating 22. The coated flat wire 18 may be flexible to permit the coated flat wire 18 to be manually bent into an arcuate shape without undue effort.

[0021] The conductor 20 may be formed from wire having a circular cross-section, which is rolled or otherwise mechanically processed to yield the flat conductor 20. The insulating coating(s) 22 may be applied to the conductor 20 before or after the circular conductor is flattened.

[0022] The coated flat wire 18 and, thus, each bus ring 14 may have a rectangular cross-section, with opposing exterior major surfaces 24 and opposing exterior edges 26. The major surfaces 24 may be planar. The distance between the major surfaces 24 defines a thickness of the coated flat wire 18 and, thus, each bus ring 14, while the distance between the edges 26 define a width of the coated flat wire 18 and, thus, each bus ring 14.

[0023] In some embodiments, the coated flat wire 18 and, thus, each bus ring 14, may have a width-to-thickness ratio of from about 2 to about 8; in other embodiments, the coated flat wire 18 and, thus, each bus ring 14 may have a width-to-thickness ratio of from about 4 to about 6; and in still other embodiments, the coated flat wire 18 and, thus, each bus ring 14, may have a width-to-thickness ratio of about 5. In some embodiments, the width of the coated flat wire 18 may be from about 2 mm to about 16mm, and in other embodiments, the width of the coated flat wire may be from about 2 mm to about 8 mm. In some embodiments, the thickness of the conductor 18 may be from about 0.8 mm to about 6 mm, and in other embodiments, the thickness of the conductor 18 may be from about 0.8 mm to about 3 mm. In one embodiment, the width of the coated flat wire 18 may be about 6.5 mm, while the thickness may be about 1 .3 mm. The specific dimensions of each length of coated flat wire 18 depends on the required ampacity and the packaging requirements of the stator bus ring assembly 10.

[0024] The thicknesses of the insulating coating(s) 22 depend on the dimensions of the conductor 20. In some embodiments, the thickness of each of the insulating coating(s) 22 is from about 0.05 mm to about 0.3 mm, and in other embodiments the thickness of each of the insulating coating(s) 22 is from about 0.05 mm to about 0.18 mm.

[0025] The bus rings 14 may be disposed in an annular holding groove 25 inside the housing 12. The bus rings 14 may be arranged to adjoin each other in concentric fashion, with the planar surfaces 24 extending vertically. In such an arrangement, there will be an innermost bus ring 14a, a middle bus ring 14b and an outermost bus ring 14c. One planar surface 24 of the middle bus ring 14b may adjoin a planar surface 24 of the outermost bus ring 14c, while the other planar surface 24 of the middle bus ring 24 may adjoin a planar surface 24 of the innermost bus rings 14a. Top exterior edges 26 of the bus rings 14 may face upwardly. Recesses 140 are formed in the top exterior edges 26. In some embodiments, the recesses 140 may have a conventional or mostly conventional shape, such as arcuate or angular, e.g. semicircular or rectangular. In other embodiments, the recesses may have an irregular shape, such as described below.

[0026] The housing 12 enclosing the bus rings 14 may be formed from electrically insulating plastic and may include annular inner and outer walls 32, 33 and an annular top surface 30 that is flat and from which the attachment structures 16 extend upwardly and radially inward, as shown in Fig. 1. Although not shown in Fig. 1, an annular flange may be integrally joined to the outer wall 33 and extend upwardly therefrom, as shownin Fig. 2. The inner and outer walls 32, 33 may define the holding groove 25 in-between.

[0027] After the bus rings 14 are disposed in the holding groove 25 of the housing 12, a gap-filling insulating material may be injected into or otherwise added to the holding groove 25 to fill any gaps in the holding groove 25 above, between and / or around the bus rings 14. The insulating material displaces air gaps that may otherwise exist between and / or around the bus rings 14. This displacement helps prevent partial discharge, wherein air is ionized (in a strong electric field). Partial discharge can ablate the organic insulating coatings 22 of the bus rings 14. Over time, such ablation can result in electrical arcing between the conductors 20 of the bus rings 14. The insulating material may be liquid, such as an insulating oil, or may be semi-solid or solid, such as a dielectric resin. Example dielectric resins that may be used include silicone resins, acrylic resins, urethane resins and epoxy resins. Insulating material disposed above the bus rings 14 may form the annular top surface 30 of the housing 12.

[0028] As set forth above, the bus rings 14 are electrically connected to the terminals 15, respectively, to connect the bus rings 14 to an external source of AC power, which may have three phases A, B, C. A bus ring 14a may be connected to phase A, a bus ring 14b may be connected to phase B and a bus ring 14c may be connected to phase C. In addition, each bus ring 14 is secured to a plurality of the attachment structures 16, which are configured for securement to wires of stator coils (not shown) to electrically connect the conductor 20 of the bus ring 14 to the stator coils. Attachment structures 16a are secured to bus ring 14a, attachment structures 16b are secured to bus ring 14b and attachment structures 16c are secured to bus ring 14c. Attachment structures 16 are disposed around the circumference of each bus ring 14 in a spaced-apart manner. In some embodiments, the spacing of the attachment structures 16 in the bus rings 14 may be staggered such that when the bus rings 14 are mounted in the housing 12, the attachment structures 16a, b,c are interspersed around the circumference of the housing 12, i.e., each attachment structure 16 of a bus ring 14 is separated from an adjacent attachment structure 16 of the bus ring 16 by one or more attachment structures 16 from the other two bus rings 14. For example, in some embodiments, each attachmentstructure 16a may be separated from an adjacent attachment structure 16a by an attachment structure 16b and an attachment structure 16c. In other embodiments, the attachment structures 16a,b,c, may be arranged differently around the circumference of the housing 12.

[0029] In some embodiments, the attachment structures 16a,b,c may be interleaved with neutral connectors 31 such that each attachment structure 16 is separated from an adjacent attachment structure 16 by a neutral connector 31. In this manner, the attachment structures 16 and the neutral connectors 31 may be arranged around the circumference of the bus ring assembly 10 in groups of three neutral connectors 31 (represented by the letter "N") interleaved with three attachment structures 16a,b,c (represented by the letters A,B,C, respectively). An example of such a group may be N- A-N-B-N-C (as viewed counterclockwise). The neutral connectors 31 may be portions of a larger neutral structure (not shown). For example, a neutral structure may include a plurality of neutral connectors 31 that are connected together, similar to the neutral structure 110 described below.

[0030] The arrangement of the attachment structures 16a,b,c around the circumference of the housing 12 and the use of any neutral connectors 31 may be determined by the desired winding arrangement of the stator coils of the motor. For example, the use of the neutral connectors 31 to have the repeating N-A-N-B-N-C arrangement described above may be used for "star" or "wye" winding arrangements of the stator coils, wherein each N-A-N-B-N-C arrangement is for a single stator coil with the neutral connectors 31 being connected together to form a neutral point. Of course, other stator coil winding arrangements may be accommodated, such as "delta" winding arrangements.

[0031] The attachment structure 16 and any neutral connectors 31 may be configured to have their upper portions arranged in a circular configuration disposed proximate to an inner perimeter of the housing 12.

[0032] Each attachment structure 16 is formed from a conductive metal, such as copper or a copper alloy. The attachment structures 16 may be formed of copper or acopper alloy, even if the conductors 20 are formed of aluminum. Each attachment structure 16 may include a curved body 34 having an upper portion joined to a fastening section and a lower portion joined to a base 38. The fastening section is configured for connection to a wire of a stator coil and may comprise a vertically-extending weld finger or, alternately, inwardly-extending crimp arms 36. The weld finger may be seam-welded by a laser to the wire of the stator coil, while the crimp arms 36 may be crimped and / or welded to the wire of the stator coil. From the base 38, the body 34 may bend upwardly, then inwardly and then upwardly again so to have an inwardly-extending portion disposed between two upwardly-extending portions. The crimp arms 36 may be spacedapart and are configured to be bent inwardly to securely crimp a wire of a stator coil inbetween. The fastening sections of the attachment structures 16 (e.g., the crimp arms 36) and fastening sections of any neutral connectors 31 are disposed radially inward from the housing 12. The fastening sections of the neutral connectors 31 may also comprise weld fingers or crimp arms.

[0033] The body 34 may have different configurations in the attachment structures 16a,b,c, respectively. More specifically, the length of the inwardly-extending portion of the body 34 may be different in the attachment structures 16a,b,c to accommodate the different radial distances of the of the bus rings 14a, b,c from the center of the bus ring assembly 10. Thus, the attachment structures 16c would have bodies 34 with the longest inwardly-extending portions, since the bus rings 14c are the farthest from the center of the bus ring assembly 10. Having different lengths for the inwardly-extending portions of the attachment structures 16a, b,c permits the fastening structures (e.g., the crimp arms 36) of all the attachment structures 16 to have the same radial distance from the center of the bus ring assembly 10. The fastening sections of any neutral connectors 31 are disposed at the same radial distance from the center of the bus ring assembly 10 as the fastening structures.

[0034] Bottom edges of the bases 38 of the attachment structures 16 have a configuration that corresponds or conforms to the recesses 40 in the top exterior edges 26 of the bus rings 14, such that the bottom edges of the bases 38 fit into the recesses40 in the top exterior edges 26 in a close-fit manner. The conforming configurations of the bases 38 and the recesses 40 are used to secure the attachment structures 16 to the bus rings 14. More specifically, attachment structures 16 are secured to each bus ring 14 by inserting the bases 38 of the attachment structures 16 into the recesses 40 of the bus ring 14 and then welding them into place, such as by laser welding.

[0035] As described above, in some embodiments, the recesses 40 may have a regular shape and the bottom edges of the base 38 may have a corresponding regular shape. For example, the recesses 40 may be semi-circular or rectangular and the bottom edges 38 may correspondingly be semi-circular or rectangular, as the case may be. In other embodiments, the recesses 40 may have an irregular shape and the bottom edges of the base 38 may have a corresponding irregular shape. For example, the irregular shapes may be wavy, saw-toothed or crenellated. More specifically, the configuration of the recesses 40 may be defined by an interior edge having portions of at least two different depths. One such irregular shape is best shown in Figs. 2 and 3 and is formed by removing a saddle cut of material away from the top exterior edge 26 of each bus ring 14. This configuration has a deep central portion that is disposed between two shallower portions. In this embodiment, the bottom edge of each base 38 has a head and shoulders configuration, with the head extending lower than the shoulders. This configuration corresponds to the saddle-cut recesses 40 formed in the top exterior edges 26 of the bus rings 14. In this manner, the bottom edges of the bases 38 can fit into the recesses 40 in the top exterior edges 26 of the bus rings 14, where they may be welded into place to secure the attachment structures 16 to the bus rings 14.

[0036] Referring now to Figs. 3 and 4, a process of securing an attachment structure 16 to a bus ring 14 will be described. A recess 40 is made in the top exterior edge 26 of the bus ring 14, such as by making a saddle cut in the top exterior edge 26 and removing material of the bus ring 14. Fig. 3 shows a portion of the bus ring 14 after a saddle-cut is made to form the recess 40. The base 38 of the attachment structure 16 is then inserted into the recess 40, such as by a placement arm 42 of automatedmachinery. With the base 38 disposed in the recess 40, the base 38 is then welded to the conductor 20 of the bus ring 14, such as by welding using a laser beam 44, as shown in Fig. 4. The base 38 may be welded into the recess 40 on one or both sides of the bus ring 14. The insulating coating(s) 22 of the bus ring 14 proximate to the weld zone is / are vaporized during laser welding, thereby exposing the weld bead 50, which facilitates visual inspection of the weld bead 50.

[0037] The irregular edge formed in the conductor 20 by the saddle-cut provides for long weld length, which is desirable. The welding of the base 38 in the recess 40 formed by a cut, such as the saddle-cut, enables a weld to be formed that is confined to the thickness zone of the bus ring 14 (coated flat wire 18), thereby saving space.

[0038] Fig. 5 shows a length of the coated flat wire 18 that has been bent to form a semicircular bus portion 54. Another length of the coated flat wire 18 may be bent in the same manner to form another semicircular bus portion 54. The two semicircular bus portions 54 may then be connected together to form a circular bus ring 14.

[0039] Referring now to Fig. 6, there is shown a stator bus ring assembly 100 constructed in accordance with a second embodiment. The stator bus ring assembly 100 distributes AC power to coils of a stator (not shown) of an electric motor. The stator bus ring assembly 100 may be mounted on top of a core of the stator, above the stator coils. The stator bus ring assembly 100 includes an outer ring-shaped plastic housing 102 that encloses three bus rings 104 electrically connected to three terminals 105, respectively. The terminals 105 are for connection to an external three-phase AC power supply. The bus rings 104 are physically and electrically connected to attachment structures 106 and neutral structures 110, which are connected to stator coils (not shown).

[0040] Each of the bus rings 104 is circular and is formed from one or more lengths of coated flat wire 18 that is / are bent or otherwise configured to have an arcuate shape, e.g., circular, semicircular or a quarter circle. Thus, by way of example, if a bus ring 104 is formed from two lengths of coated flat wire 18, the two lengths of coated flat wire 18 are bent to be semicircular and then are connected together to form a circle.

[0041] Referring now also to Figs. 7 and 8, the housing 102 encloses the bus rings 104 and may be formed from electrically insulating plastic. The housing 102 has an annular holding groove 115 that is defined by an outer wall 118 and an inner wall structure 120. The outer wall 118 may have an integral upper flange so as to extend above the inner wall structure 120. The inner wall structure 120 comprises a plurality of holding blocks 121 , each of which has a top end with a raised center portion 122 bracketed by a pair of lower portions, through which vertically-extending slots 126 extend through, respectively.

[0042] The bus rings 104 may be disposed in the holding groove 115 inside the housing 102. The bus rings 104 may be arranged to adjoin each other in concentric fashion, with the planar surfaces 24 extending vertically. In such an arrangement, there will be an innermost bus ring 104a, a middle bus ring 104b and an outermost bus ring 104c. One planar surface 24 of the middle bus ring 104b may adjoin a planar surface 24 of the outermost bus ring 104c, while the other planar surface 24 of the middle bus ring 24 may adjoin a planar surface 24 of the innermost bus rings 104a. Top exterior edges 26 of the bus rings 104 may face upwardly. Recesses 140 are formed in the top exterior edges 26. In some embodiments, the recesses 140 may have an irregular shape or a conventional or mostly conventional shape, such as arcuate or angular, e.g. a semicircle or a quadrilateral. For example, the recesses 140 may have a trapezoidal shape, as best shown in Fig. 9.

[0043] Referring now to Fig. 9, each attachment structure 106 is formed from a conductive metal, such as copper or a copper alloy. The attachment structures 106 may be formed of copper or a copper alloy, even if the conductors 20 are formed of aluminum. Each attachment structure 106 may include a curved body 132 having an upper portion joined to a fastening section and a lower portion joined to a base 134. The fastening section is configured for connection to a wire of a stator coil and may comprise a vertically-extending weld finger, or alternately, inwardly-extending crimp arms 136. The weld finger may be seem-welded by a laser to the wire of the stator coil, while the crimp arms 136 may be crimped and / or welded to the wire of the stator coil.From the base 134, the body 132 may bend upwardly, then inwardly and then upwardly again so to have an inward-extending portion disposed between two upward-extending portions. The crimp arms 136 may be spaced-apart and are configured to be bent inwardly to securely crimp a wire of a stator coil in-between. A pair of mounting legs 138 are joined at their curved upper end portions to opposing sides of the inward-extending portion of the body 132 and bend laterally and then downwardly. Lower end portions of the mounting legs 138 may be barbed.

[0044] The body 132 may have different configurations in the attachment structures 106, respectively. More specifically, the length of the inward-extending portion of the body 132 may be different in the attachment structures 106 to accommodate the different radial distances of the of the bus rings 104 from the center of the bus ring assembly 100. Having different lengths for the inwardly-extending portions of the attachment structures 106 permits the fastening sections (e.g., the crimp arms 136) of all the attachment structures 106 to have the same radial distance from the center of the stator bus ring assembly 100.

[0045] Bottom edges of the bases 138 of the attachment structures 106 have a configuration that corresponds or conforms to the recesses 140 in the top exterior edges 26 of the bus rings 104, such that the bottom edges of the bases 138 fit into the recesses 140 in the top exterior edges 26 in a close-fit manner. As described above, the recesses 140 may have a trapezoidal shape, so the bases 138 may have a conforming trapezoidal shape. Of course, the recesses 140 and the bases 138 may have other shapes, either regular or irregular. The conforming configurations of the bases 138 and the recesses 140 are used to secure the attachment structures 106 to the bus rings 104. More specifically, attachment structures 106 are secured to each bus ring 104 by inserting the bases 138 of the attachment structures 106 into the recesses 140 of the bus ring 104 and then welding them into place, such as by laser welding.

[0046] Referring now to Fig. 10, each neutral structure 110 is formed from a conductive metal, such as copper or a copper alloy, and includes a plurality of neutral connectors 131 joined to an arcuate bar 144. As shown, three neutral connectors 131may be joined to the bar 144. Each connector structure 131 may have a curved body 142 with a U-shaped center portion joined between an inner portion and an outer portion joined to the bar 144. A pair of mounting legs 148 are joined at their curved upper end portions to opposing sides of the center portion of the body 142 and bend laterally and then downwardly. Lower end portions of the mounting legs 148 may be barbed. The inner portion of the body 142 may be joined to a fastening section configured for connection to a wire of a stator coil and may comprise a vertically extending weld finger or inwardly-extending crimp arms 146 for clasping a wire of a stator coil. The weld finger may be seam-welded by a laser to the wire of the stator coil, while the crimp arms 146 may be crimped and / or welded to the wire of the stator coil. Like the fastening structures of the attachment structures 106, the fastening structures of the neutral connectors 131 are disposed radially inward from the housing 102. An outer casing or shell 150 (shown best in Fig. 8) may be mounted over the bar 144. The shell 150 may be formed from an electrically insulating plastic and may be molded over the bar 144 or may be mechanically fastened to the bar 144.

[0047] As set forth above, the bus rings 104 are connected to the terminals 105, respectively, to electrically connect the bus rings 104 to an external source of AC power, which may have three phases A, B, C. A bus ring 104a may be connected to phase A, a bus ring 104b may be connected to phase B and a bus ring 104c may be connected to phase C. In addition, each bus ring 104 is secured to a plurality of the attachment structures 106, which are configured for securement to wires of stator coils (not shown) to electrically connect the conductor 20 of the bus ring 104 to the stator coils. Attachment structures 106a are secured to bus ring 104a, attachment structures 106b are secured to bus ring 104b and attachment structures 106c are secured to bus ring 104c. Attachment structures 106 are disposed around the circumference of each bus ring 104 in a spaced-apart manner. The spacing of the attachment structures 106 in the bus rings 104 may be staggered such that when the bus rings 104 are mounted in the housing 102, the attachment structures 106a,b,c are interspersed around the circumference of the housing 102, i.e., each attachment structure 106 of a bus ring 104is separated from an adjacent attachment structure 106 of the bus ring 106 by one or more attachment structures 106 from the other two bus rings 104. For example, in some embodiments, each attachment structure 106a may be separated from an adjacent attachment structure 106a by an attachment structure 106b and an attachment structure 106c. In other embodiments, the attachment structures 106a, b,c, may be arranged differently around the circumference of the housing 102.

[0048] The neutral connectors 131 are interleaved with the attachment structures 106a,b,c such that each attachment structure 106 is separated from an adjacent attachment structure 106 by a neutral connector 131 . In this manner, the attachment structures 106 and the neutral connectors 131 may be arranged around the circumference of the bus ring assembly 10 in groups of three neutral connectors 131 (represented by the letter "N") interleaved with three attachment structures 106a,b,c. (represented by the letters A,B,C, respectively). An example of such a group may be N- A-N-B-N-C (viewed counterclockwise), which may be used for a wye winding arrangement of a stator coil, with the neutral connectors 131 of a neutral structure 110 being connected together and forming the neutral point of the winding arrangement.

[0049] In addition to being electrically and physically connected to the bus rings 104, the attachment structures 106 may be physically connected to the housing 102.Referring back to Fig. 8, each attachment structure 106 is mounted to a holding block 121 of the housing 102 by having its mounting legs 138 inserted into the slots 126 of the holding blocks 121 , with the barbs of the mounting legs 138 engaging interior surfaces defining the slots 126 to thereby secure the mounting legs 138 in the slots 126.Similarly, each neutral connector 131 may also be secured to a holding block 121 by having its mounting legs 148 inserted into the slots 126 of the holding blocks 121 , with the barbs of the mounting legs 148 engaging interior surfaces defining the slots 126, thereby securing the mounting legs 148 in the slots 126. With the mounting legs of the attachment structures 106 and the neutral connectors 131 secured in the slots 126 of the holding blocks 121 , the bodies of the attachment structures 106 and the neutral connectors 131 are at least partially disposed over the holding groove 115 and extendbetween center portions 122 of the holding blocks 121 , with the curved upper end portions of their mounting legs adjoining or being closely proximate to adjacent center portions 122. In this manner, the attachment structures 106 and the neutral connectors 131 are circumferentially held in place.

[0050] With the attachment structures 106 and the neutral connectors 131 mounted to the housing 102, as described above, each neutral connector 131 of a neutral structure 110 is disposed between a pair of attachment structures 106, with the requisite spacing between the neutral connectors 131 being provided by the bar 144, which also electrically connects them together to form a neutral point of a wye winding arrangement. The bar 144 is disposed above the bus rings 104 in the holding groove 115.

[0051] Similar to the stator bus ring assembly 10, a gap-filling insulating material may be injected into or otherwise added to the holding groove 115 to fill any gaps in the holding groove 115 above, between and / or around the bus rings 104. The insulating material displaces air gaps that may otherwise exist between and / or around the bus rings 104. The insulating material may be liquid, such as an insulating oil, or may be semi-solid or solid, such as a dielectric resin. Example dielectric resins that may be used include silicone resins, acrylic resins, urethane resins and epoxy resins.

[0052] From the foregoing description, it should be appreciated that the stator bus ring assemblies 10, 100 provides a number of benefits over conventional stator busbar rings. The compact nature of the coated flat wire 18 enables the concentric arrangement of the bus rings 14, 104 to take less space than a concentric arrangement of overmold busbars. In addition, the construction of the bus rings 14, 104 from the coated flat wire 18 permits a form-fitting assembly tool to place “near-net shape” lengths of the coated flat wire 18 into the holding groove 25, 115 of the housing 12, 102 and conform to the space therein, which is not possible with overmold busbars. In addition, the conductor 20 of the coated flat wire 18 may be produced to have a dead-soft temper, which further reduces assembly forces.

[0053] It is to be understood that the description of the foregoing exemplaryembodiment(s) is (are) intended to be only illustrative, rather than exhaustive. Those of ordinary skill will be able to make certain additions, deletions, and / or modifications to the embodiment(s) of the disclosed subject matter without departing from the spirit of the disclosure or its scope.

Claims

What is claimed is:1 . A stator bus ring assembly, comprising: a housing; bus rings arranged concentrically in the housing, each bus ring comprising one or more lengths of coated flat wire having a metal conductor coated with one or more layers of one or more insulating coatings, each bus ring having a width-to-thickness ratio of from about 2 to about 8; and attachment structures secured to each of the bus rings, the attachment structures extending from the housing and being configured for securement to wires of stator coils, respectively, to electrically connect the bus rings to the stator coils.

2. The stator bus ring assembly of claim 1 , wherein each bus ring has a width-to- thickness ratio of from about 4 to about 6.

3. The stator bus ring assembly of claim 1 , wherein the metal conductor of each bus ring comprises copper or a copper alloy having a dead-soft temper.

4. The stator bus ring assembly of claim 1 , wherein the metal conductor of each bus ring comprises aluminum.

5. The stator bus ring assembly of claim 1 , wherein each of the attachment structures comprises a body having a bottom portion joined to a base and a top portion joined to a fastening section configured for connection to a wire of a stator coil, the fastening section being disposed exterior to the housing.

6. The stator bus ring assembly of claim 5, wherein in each bus ring, the bases of the attachment structures are welded into recesses in the bus ring.

7. The stator bus ring assembly of claim 6, wherein each bus ring has a rectangular cross-section, with opposing exterior major surfaces and opposing exterior edges, the distance between the major surfaces defining a thickness of the bus ring and the distance between the exterior edges defining a width of the bus ring; and wherein in each bus ring, the recesses extend into one of the exterior edges of the bus ring.

8. The stator bus ring assembly of claim 6, wherein in each bus ring, the recesses in the bus ring have an irregular shape defined by an interior edge having portions of at least two different depths.

9. The stator bus ring assembly of claim 5, wherein the fastening section comprises a pair of spaced-apart crimp arms configured to be bent towards each other to securely crimp the wire of the stator coil.

10. The stator bus ring assembly of claim 1 , wherein the bus rings comprise a first bus ring for a first phase of power, a second bus ring for a second phase of power and a third bus ring for a third phase of power, wherein the attachment structures comprise first attachment structures secured to the first bus ring, second attachment structures secured to the second bus ring and third attachment structures secured to the third bus ring.11 . The stator bus ring assembly of claim 10, further comprising neutral connectors extending from the housing, the neutral connectors not being secured to the bus rings.

12. The stator bus ring assembly of claim 11 , wherein the attachment structures and the neutral connectors are arranged in a circular configuration, and wherein the attachment structures are interleaved with the neutral connectors.

13. The stator bus ring assembly of claim 12, wherein in the circular configuration, the neutral connectors and the attachment structures are arranged in groups, each group having three neutral connectors, a first attachment structure, a second attachment structure and a third attachment structure.

14. The stator bus ring assembly of claim 13, wherein in each group, the three neutral connectors are separated by spaces and are part of a unitary neutral structure, and wherein the neutral connectors each comprise a pair of spaced-apart crimp arms configured to be bent towards each other to securely crimp a wire of the stator coil.

15. The stator bus ring assembly of claim 12, wherein fastening sections of the attachment structures and the neutral connectors are disposed radially inward from the housing.

16. The stator bus ring assembly of claim 1 , wherein each bus ring is formed from two lengths of the coated flat wire, the two lengths each being configured to have a semicircular shape and being connected together to provide the bus ring with a circular shape.

17. The stator bus ring assembly of claim 1 , wherein each bus ring has a rectangular cross-section, with opposing exterior major surfaces and opposing exterior edges, the distance between the major surfaces defining a thickness of the bus ring and the distance between the exterior edges defining a width of the bus ring; and wherein in each bus ring, recesses extend into one of the exterior edges of the bus ring; and wherein in each bus ring, portions of the attachment structures are secured within the recesses of the bus ring.

18. The stator bus ring assembly of claim 17, wherein the bus rings are flexible and manually bendable.

19. The stator bus ring assembly of claim 1, wherein the housing defines a groove in which the bus rings are disposed; and wherein insulating material is disposed in gaps between and / or around the bus rings in the groove.

20. The stator bus ring assembly of claim 19, wherein the insulating material in the groove comprises a dielectric resin and wherein the housing is formed from electrically insulating plastic.

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