Stacked flat-wire bus bars

Abstract

A bus bar assembly in which bus bars are arranged in a stack having two or more layers of the bus bars. The stack of the bus bars is at least partially disposed inside a housing formed from electrically insulating plastic. Each of the layers of the bus bars has one or more of the bus bars. Each bus bar has opposing major surfaces and opposing side edges. At least one of the side edges of each bus bar has a recess formed therein. Each bus bar includes one or more lengths of coated flat wire having a metal conductor coated with one or more layers of one or more insulating coatings. Attachment structures are secured in the recesses of the bus bars, respectively. Each of the attachment structures is configured for securement to a conductor for conveying power.

Description

STACKED FLAT-WIRE BUS BARSCROSS-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 / 677,164 filed on 30 July 2024, which is herein incorporated by reference.TECHNICAL FIELD

[0002] This disclosure relates generally to bus bars for conveying electrical power.BACKGROUND

[0003] Bus bars are commonly used to provide power to electrical and electronic devices and components, such as electric motors. Conventionally, a bus bar includes a conductor, such as a bar or a plate composed of a conductive metal, such as copper or aluminum, and is relatively wide and thick to better conduct electric current. In some applications, the conductor may be overmolded with an insulating plastic. Due to the composition, thickness and configuration of an overmolded bus bar, the bus bar is typically rigid and difficult to position and make electrical connections thereto.SUMMARY

[0004] A bus bar assembly in which bus bars are arranged in a stack having two or more layers of the bus bars. Each of the layers of the bus bars has one or more of the bus bars. Each bus bar has opposing major surfaces and opposing side edges. At least one of the side edges of each bus bar has a recess formed therein. Each bus bar includes 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 bar has a width-to-thickness ratio of from about 2 to about 8. Attachment structures are secured in the recesses of the bus bars, respectively. Each of the attachment structures is configured for securement to a power conductor for conveying power.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 perspective view of a bus bar assembly having a stack of bus bars;

[0007] Fig. 2 shows a perspective view of the bus bar assembly of Fig. 1 , wherein bus bars of the stack are spaced apart;

[0008] Fig . 3 shows ends of portions of the bus bars of the bus bar assembly of Fig . 1 ;

[0009] Fig. 4 shows a perspective view of the bus bar assembly of Fig. 1 , wherein terminals are spaced from recesses in the bus bars in which they are normally mounted;

[0010] Fig. 5 shows a perspective view of a second bus bar assembly having the stack of the bus bar assembly of Fig. 1 mounted inside a plastic housing;

[0011] Fig. 6 shows a sectional view of the second bus bar assembly of Fig. 5;

[0012] Fig. 7 shows a top front perspective view of a third bus bar assembly;

[0013] Fig. 8 shows a top front perspective view of the third bus bar assembly of Fig. 7 with a housing and a separator removed and several components spaced from their normal mounting positions;

[0014] Fig. 9 shows a top front perspective view of bus bars of the third bus bar assembly of Fig. 7, with other components removed;

[0015] Fig. 10 shows a bottom plan view of the third bus bar assembly of Fig. 7;

[0016] Fig. 11 shows a top plan view of the third bus bar assembly of Fig. 8, with the housing removed;

[0017] Fig. 12 shows a top perspective view of a fourth bus bar assembly;

[0018] Fig. 13 shows a top perspective view of a portion of a housing of the fourth bus bar assembly of Fig. 12;

[0019] Fig. 14 shows a sectional perspective view of a portion of the fourth bus bar assembly of Fig, 12;

[0020] Fig. 15 shows a perspective view of components of the fourth bus bar assembly of Fig. 12, namely an attachment structure spaced above a recess formed in a bus bar; and

[0021] Fig. 16 shows components of the fourth bus bar assembly of Fig. 12, namely a neutral structure spaced above a portion of bus bars to which attachment structures are secured.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0022] 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.

[0023] 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.

[0024] The present disclosure is directed to a bus bar assembly configured to convey electric power to an electrical device, such as an electric motor, or another electrical conductor. The bus bar assembly includes a plurality of bus bars arranged in a stack. In some embodiments, the stack may include two or more bus bars, such as two, three, four, five or more bus bars. The bus bars in the stack may be arranged in two or more layers with each layer containing one or more bus bars. For example, the bus bar assembly 60 described below has two layers with an upper layer being discontinuous and containing three bus bars. In some embodiments, the stack may be held together mechanically, such as by using one or more clamps or bands (not shown), or by using an adhesive, such as an epoxy adhesive. In other embodiments, the stack may be held together by an outer housing, such as the overmoldedhousing described below. An example of a bus bar assembly constructed in accordance with the disclosure is shown in Fig. 1. and is designated by the reference numeral 10. The bus bar assembly 10 includes a stack 15 having two layers, with a first layer adjoining or in close proximity to a second layer. The first layer includes a first or upper bus bar 12 and the second layer includes a second or lower bus bar 14.

[0025] In some embodiments, the bus bars, such as the upper bus bar 12 and the lower bus bar 14, may be straight or linear, while in other embodiments, the bus bars may be curved, semi-circular, mostly circular, or circular. In linear embodiments, the bus bars, such as the upper bus bar 12 and the lower bus bar 14, may have the same or different lengths. For example, the upper bus bar 12 may be longer than the lower bus bar 14, such as is shown. In other embodiments, the bus bars, such as the upper bus bar 12 and the lower bus bar 14, may be non-linear, such as curved. In some embodiments, each of the bus bars, such as the upper bus bar 12 and the lower bus bar 14, may have a multi-piece construction, with the individual pieces being secured together.

[0026] Each of the bus bars in the bus bar assembly of the disclosure, such as the upper bus bar 12 and / or the lower bus bar 14 may be formed from one or more lengths of coated flat wire 18. Referring now also to Fig. 3, the coated flat wire 18 and, thus, each of the upper bus bar 12 and the lower bus bar 14, includes a metal conductor 20 covered with one or more outer 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 a curved shape without undue effort.

[0027] 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 insulatingcoating(s) 22 may be applied to the conductor 20 before or after the circular conductor is flattened.

[0028] The coated flat wire 18 and, thus, each of the bus bars, such as the upper and lower bus bars 12, 14 may have a rectangular cross-section, with opposing exterior major surfaces 24 and opposing side 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 of the upper and lower bus bars 12, 14, while the distance between the edges 26 define a width of the coated flat wire 18 and, thus, each of the upper and lower bus bars 12, 14.

[0029] In some embodiments, the coated flat wire 18 and, thus, each of the bus bars in the stack, such as the upper and lower bus bars 12, 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 of the bus bars, such as the upper and lower bus bars 12, 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 of the bus bars, such as the upper and lower bus bars 12, 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 16 mm, 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 bus bar assembly 10.

[0030] 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.

[0031] In some embodiments of the bus bar assembly, the bus bars, such as the upper and lower bus bars 12, 14 may be stacked together to form a stack such that their widths arealigned. The stack may be arranged to be horizontal, vertical or some other orientation. When the bus bars are arranged in a stack, major surfaces 24 of the bus bars may be adjacent or adjoin each other. For example, a lower major surface 24 of the upper bar 12 may adjoin an upper major surface 24 of the lower bus bar 14, as shown. In a vertical stack, some of the bus bars overlie adjoining bus bars. For example, the upper bus bar 12 overlies the lower bus bar 14 such that their widths are aligned. If in adjoining pairs, an overlying bus bar is longer than an underlying bus bar, overhangs may be formed. For example, the upper bus bar 12 may be longer than the lower bus bar 14, as shown. With this difference in lengths, portions of the upper bus bar 12, toward the first and second ends, may overhang the lower bus bar 14.

[0032] In each of the bus bars, such as the upper and lower bus bars 12, 14, recesses 30 are formed in the side edges 26. In some embodiments, the recesses 30 may have a conventional or mostly conventional shape, such as curved or angular, e.g. a semicircle or a quadrilateral. In other embodiments, the recesses 30 may have an irregular shape. The recesses 30 may be located in one or both of the side edges 26 of each of the bus bars, e.g., the upper and lower bus bars 12, 14. In some embodiments, a recess 30 may be located in each side edge 26 of each bus bar, with the recesses 30 being located toward opposing ends of the bus bar. For example, as shown in Figs. 3 and 4, a first recess 30 may be located in a first side edge 26 of the upper bus bar 12, toward a first end thereof, while a second recess 30 may be located in a second side edge 26 of the upper bus bar 12, toward a second end thereof. A first recess 30 may be located in a second side edge 26 of the lower bus bar 14, toward a first end thereof, while a second recess 30 may be located in a first side edge 26 of the lower bus bar 12, toward a second end thereof. In this manner, the first recesses 30 of the upper bus bar 12 are aligned with the first recesses 30 of the lower bus bar 14 in the direction of the lengths of the upper and lower bus bars 12, 14, but are oppositely facing. Similarly, the second recesses 30 of the upper bus bar 12 are aligned with the second recesses 30 of the lower bus bar 14 in the direction of the lengths of the upper and lower bus bars 12, 14, but are oppositely facing.

[0033] A terminal 32 may be secured in each of the recesses 30 in the bus bars, such asthe upper and lower bus bars 12, 14. The terminal 32 may be a ring terminal (such as shown) or other type of terminal. Each terminal 32 may be formed, such as by stamping, from a piece of conductive metal, such as copper or a copper alloy. Each terminal 32 may have a flat body with opposing planar surfaces, a free end, and a mounting end. The mounting ends have a configuration that corresponds or conforms to the recesses 30 in the side edges 26 of the bus bars, such that the mounting ends fit into the recesses 30 in the side edges 26 in a close-fit manner. In the embodiment shown, the free end is curved and the mounting end is rectangular. A circular opening 36 extends through the body of each terminal 32. The conforming configurations of the mounting ends and the recesses 30 are used to secure the terminals 32 to the bus bars. More specifically, terminals 32 are secured to the bus bars by inserting the mounting ends of the terminals 32 into the recesses 30 of the bus bars and then welding them into place, such as by laser welding. With laser welding, a mounting end of a terminal 32 may be welded into a recess 30 on one or both sides of the bus bar. The insulating coating(s) 22 of the bus bars proximate to the weld zone is / are vaporized during laser welding, thereby exposing a weld bead, which facilitates visual inspection of the weld bead.

[0034] As shown, the mounting ends of the terminals 32 are rectangular. Accordingly, the recesses 30 are rectangular and are configured to receive the mounting ends of the terminals 32. In other embodiments, the mounting ends of the terminals 32 may have a different configuration, such as curved, and the recesses 30 will have a different, corresponding configuration, such as curved.

[0035] When secured in the recesses 30, the terminals 32 are disposed on two sides of the bus bar assembly 10. For example, a first pair of the terminals 32 may be disposed toward a first end and extend in opposing directions from opposite side edges 26, and a second pair of the terminals 32 may be disposed toward a second end and extend in opposing directions from opposite side edges 26. At each end, the terminals 32 are offset in the direction of the thickness of the bus bars, e.g., the upper and lower bus bars 12, 14.

[0036] As mentioned above, in some embodiments, the stack of bus bars in the bus bar assembly may be enclosed in a housing. An example of this type of embodiment is illustratedin Figs. 5 and 6, which shows a bus bar assembly 42 that has a housing 44 in which the stack 15 of the upper and lower bus bars 12, 14 is disposed. The housing 44 may be formed from electrically insulating plastic and may have a rectangular configuration with opposing main walls 46 and opposing side walls 48. The housing 44 may be formed in an overmold process in which the upper and lower busbars 12, 14 are held in a mold by holding or pinch pins and the insulating plastic is injected into the mold over the upper and lower busbars 12, 14. Afterwards, the pinch pins are removed and the overmolded housing 44 with the upper and lower busbars 12, 14 disposed inside are removed from the mold. The removal of the pinch pins leaves holes 52 in the main walls 46.

[0037] Using the bus bar assembly 42 in lieu of a pair of conventional overmolded bus bars formed by stamping has a number of advantages, such as: providing tighter overall package dimensions; simplifying the securement of bus bars during overmolding by using pinch pins on only the top-most and bottom-most bus bar surfaces; canceling parasitic inductances in DC applications; using less copper scrap than stamped bus bars; and reducing insulator cracking risk typically present in conventional overmolded bus bars.

[0038] Referring now to Fig, 7 there is shown a bus bar assembly 60 that may be used for distributing AC power to coils of a stator (not shown) of an electric motor, i.e., is a stator bus bar assembly. The bus bar assembly 60 may be mounted on top of a core of a stator, above the stator coils. The bus bar assembly 60 includes a curved plastic housing 62 that at least partially encloses a neutral bus bar 64 (shown in Figs. 8 and 9) and three power bus bars 68 electrically connected to three terminal structures 70, respectively. The terminal structures 70 are for connection to an external three-phase AC power supply. The neutral bus bar 64 is physically and electrically connected to attachment structures 72, while the power bus bars 68 are physically and electrically connected attachment structures 73. The attachment structures 72, 73 are configured for connection to stator coils (not shown). Each of the neutral bus bar 64 and the power bus bars 68 is curved and formed from a length of coated flat wire 18. Being curved, each of the neutral bus bar 64 and the power bus bars 68 has an inner side edge 26 that is shorter and disposed radially inward from an outer side edge 26.

[0039] Referring now also to Figs. 8 and 9, the power bus bars 68 are shown being spaced apart and overlying the neutral bus bar 64. In this manner, the bus bar assembly 60 has a stack of bus bars comprising two layers of bus bars. The two layers include a lower layer comprising a single bus bar, namely the neutral bus bar 64, and an upper layer being discontinuous and comprising three separate bus bars, namely the power bus bars 68. A curved separator 75 may be disposed between the two layers of bus bars, so the power bus bars 68 may overlie, but not touch the neutral bus bar 64. The separator 75 may be formed from an electrically insulating material and may take the form of a rigid or semi-rigid plate or a flexible web.

[0040] Each of the power bus bars 68 has a recess 74 formed in its inner side edge 26. The neutral bus bar 64 has three recesses 76 formed in its inner side edge 26 that are spaced apart. The neutral bus bar 64 and its recesses 76 and the power bus bars 68 and their recesses 74 are configured and arranged such that the recesses 76 of the neutral bus bar 64 are interleaved with the recesses of the power bus bars 68 along an inner periphery of the bus bar assembly 60, as best shown in Fig. 9.

[0041] In some embodiments, the recesses 74, 76 may have a conventional or mostly conventional shape, such as curved or angular, e.g. a semicircle or a quadrilateral. In other embodiments, the recesses 74, 76 may have an irregular shape. In the shown embodiment, the recesses 74, 76 are rectangular.

[0042] In addition to the recesses 74, holes 78 are formed in the power bus bars 68, respectively. A hole 78 is formed in each power bus bar 68 and extends through one or both of the major surfaces 24 of the power bus bar 68 so as to extend through all or a portion of the power bus bar 68. The holes 78 are located toward first ends of the power bus bars 68, respectively. The holes 78 at least partially extend through the conductors 20 of the power bus bars 68 and are configured to receive tabs 80 of mounting arms 82 of the terminal structures 70, respectively, such that the tabs 80 engage the conductors 20. The tabs 80 may be welded into the holes 78 to physically secure and electrically connect the terminal structures 70 to the power bus bars 68, respectively. Ring-shaped holders 84 are joined at bends to the mountingarms 82 of the terminal structures 70. The ring-shaped holders 84 hold terminals 85 for connection to the external source of AC power, such as by cables. The terminals 85 may be internally threaded to threadably receive connectors of connecting cables. The mounting arms 82 space the ring-shaped holders 84 above the housing 62 and the neutral bus bar 64 and the power bus bars 68 disposed therein. The bends in the mounting arms 82 position the ringshaped holders 84 and, thus, the terminals 85 so as to permit the terminals 85 to receive vertically extending connectors.

[0043] Each of the attachment structures 72 may be a unitary structure formed from a conductive metal, such as copper or a copper alloy. Each attachment structure 72 may have a rectangular base 90 joined to a plurality of spaced-apart fasteners 92, which may be weld fingers (as shown) or paired crimp arms. Weld fingers may be seam-welded by a laser to wires of the stator coils, while crimp arms may be crimped and / or welded to the wires of the stator coils. From the base 90, the fasteners 92 may bend upwardly to extend at right angles to the base 90. The bases 90 of the attachment structures 72 have a configuration that corresponds or conforms to the recesses 76 in the side edge 26 of the neutral bus bar 64, such that the bases 90 fit into the recesses 76 in the side edge 26 in a close-fit manner. The conforming configurations of the bases 90 and the recesses 76 are used to secure the attachment structures 72 to the neutral bus bar 64. More specifically, an attachment structure 72 is secured to the neutral bus bar 64 by inserting the base 90 of the attachment structure 72 into a recess 76 of the neutral bus bar 64 and then welding it into place, such as by laser welding.

[0044] The attachment structures 73 may have the same or similar construction as the attachment structures 72. Each of the attachment structures 73 may be a unitary structure formed from a conductive metal, such as copper or a copper alloy. Each attachment structure 73 may have a rectangular base 86 joined to a plurality of spaced-apart fasteners 88, which may be weld fingers (as shown) or crimp arms. Weld fingers may be seam-welded by a laser to wires of the stator coils, while crimp arms may be crimped and / or welded to the wires of the stator coils. From the base 86, the fasteners 88 may bend upwardly to extend at right angles to the base 86. The bases 86 of the attachment structures 73 have a configuration thatcorresponds or conforms to the recesses 74 in the side edges 26 of the power bus bars 68, such that the bases 86 fit into the recesses 74 in the side edges 26 in a close-fit manner. The conforming configurations of the bases 86 and the recesses 74 are used to secure the attachment structures 73 to the power bus bars 68. More specifically, an attachment structure 73 is secured to a power bus bar 68 by inserting the base 86 of the attachment structure 73 into a recess 74 of the power bus bar 68 and then welding it into place, such as by laser welding.

[0045] As set forth above, the housing 62 at least partially encloses the neutral bus bar 64 and the power bus bars 68. The housing 62 includes a curved outer wall, a top wall 96 and end walls. Thus, the housing 62 mostly covers the top, rear and ends of the neutral bus bar 64 and the power bus bars 68, leaving their bottom and front exposed. Openings in the top wall permit the mounting arms 82 of the terminal structures 70 to extend through the top wall 96. With the front of the housing 62 open, the attachment structures 72, 73 may extend inwardly and upwardly without hinderance.

[0046] The attachment structure 72, 73 may be configured to have their fasteners 92, 88 arranged in a curved configuration disposed proximate to an inner perimeter of the housing 62, as shown best in Figs. 10 and 11 .

[0047] As described above, the power bus bars 68 are electrically connected to the terminal structures 70, respectively, to connect the power bus bars 68 to the external source of AC power, which may have three phases A, B, C. Referring now to Fig. 11 , a power bus bar 68a may be connected to phase A, a power bus bar 68b may be connected to a phase B and a power bus bar 68c may be connected to phase C. In addition, each power bus bar 68 is secured to a plurality of fasteners 88, which are configured for securement to wires of stator coils (not shown) to electrically connect the conductor 20 of the power bus bar 68 to the stator coils. Fasteners 88a are secured to power bus bar 68a, fasteners 88b are secured to power bus bar 68b and facteners 88c are secured to power bus bar 68c. Along the inner perimeter of the bus bar assembly 60, groups of fasteners may be alternately arranged. For example, as shown in Fig. 11 , going from left to right, there is a group of neutral fasteners 92, a group offasteners 88a, a group of neutral fasteners 92, a group of fasteners 88b, a group of neutral fasteners 92 and a group of fasteners 88c. In this manner, the fasteners 88 for each phase are separated from fasteners 88 for another phase by neutral fasteners 92 connected to the neutral bus bar 64.

[0048] The attachment structures 72 may be used for wye winding arrangements of the stator coils, with the attachment structures 72 being connected together by the neutral bus bar 64 and forming the neutral points of the winding arrangements.

[0049] Referring now to Fig. 12, there is shown a stator bus bar assembly 100 constructed in accordance with a second embodiment. The stator bus bar assembly 100 distributes AC power to coils of a stator (not shown) of an electric motor. The stator bus bar assembly 100 may be mounted on top of a core of the stator, above the stator coils. The stator bus bar assembly 100 includes an outer ring-shaped plastic housing 102 that encloses three bus bars 104 electrically connected to three terminals 105, respectively. The terminals 105 are for connection to an external three-phase AC power supply. The bus bars 104 are physically and electrically connected to attachment structures 106, which are connected to stator coils (not shown). The attachment structures 106 and neutral structures 110 may be configured to have their fastening sections arranged in a circular or mostly circular configuration disposed proximate to an inner perimeter of the housing 102.

[0050] Each of the bus bars 104 may be mostly circular or 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 or curved shape, e.g., circular, mostly circular, semicircular or a quarter circle. Thus, by way of example, if a bus bar 104 is formed from two lengths of coated flat wire 18, the two lengths of coated flat wire 18 may be bent to be semicircular or mostly semicircular and then are connected together to form a circle or mostly a circle.

[0051] Referring now also to Figs. 13 and 14, the housing 102 encloses the bus bars 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. Theinner 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.

[0052] The bus bars 104 may be disposed in the holding groove 115 inside the housing 102. The bus bars 104 may be arranged to adjoin each other in concentric fashion, with the planar surfaces 24 extending vertically. In this manner, a horizontal stack is formed with three concentric layers of bus bars 104. In this concentric arrangement, there is an innermost bus bar 104a, a middle bus bar 104b and an outermost bus bar 104c. One major surface 24 of the middle bus bar 104b may adjoin a major surface 24 of the outermost bus bar 104c, while the other major surface 24 of the middle bus ring 24 may adjoin a major surface 24 of the innermost bus bars 104a. Top side edges 26 of the bus bars 104 may face upwardly.Recesses 140 are formed in the top side edges 26. In some embodiments, the recesses 140 may have an irregular shape or a conventional or mostly conventional shape, such as curved or angular, e.g. a semicircle or a quadrilateral. For example, the recesses 140 may have a trapezoidal shape, as best shown in Fig.15.

[0053] Referring now to Fig. 15, 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. 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 inbetween. 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.

[0054] 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 side edges 26 of the bus bars 104, such that the bottom edges of the bases 138 fit into the recesses 140 in the top side 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 bars 104. More specifically, attachment structures 106 are secured to each bus bar 104 by inserting the bases 138 of the attachment structures 106 into the recesses 140 of the bus bar 104 and then welding them into place, such as by laser welding.

[0055] Referring now to Fig. 16, each neutral structure 110 may be a unitary structure stamped or cast from a conductive metal, such as copper or a copper alloy, and includes a plurality of neutral connectors 131 connected to a curved bus bar 144. As shown, three neutral connectors 131 may be connected to the bus 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 connected to the bus 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 sections of the attachment structures 106, the fastening sections of the neutral connectors 131 are disposed radially inward from the housing 102. An outer casing or shell 150 (shown best in Fig. 14) may be mounted over the bus bar 144. The shell 150 may be formed from an electrically insulatingplastic and may be molded over the bus bar 144 or may be mechanically fastened to the bus bar 144.

[0056] As set forth above, the bus bars 104 are connected to the terminals 105, respectively, to electrically connect the bus bars 104 to an external source of AC power, which may have three phases A, B, C. The bus bar 104a may be connected to phase A, the bus bar 104b may be connected to phase B and the bus bar 104c may be connected to phase C. In addition, each bus bar 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 bar 104 to the stator coils. Attachment structures 106a are secured to bus bar 104a, attachment structures 106b are secured to bus bar 104b and attachment structures 106c are secured to bus bar 104c. Attachment structures 106 are disposed around the circumference of each bus bar 104 in a spaced-apart manner. The spacing of the attachment structures 106 in the bus bars 104 may be staggered such that when the bus bars 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 bar 104 is separated from an adjacent attachment structure 106 of the bus bar 104 by one or more attachment structures 106 from the other two bus bars 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.

[0057] 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 bar assembly 100 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 wyewinding 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.

[0058] In addition to being electrically and physically connected to the bus bars 104, the attachment structures 106 may be physically connected to the housing 102. Referring back to Fig. 14, 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 extend between 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.

[0059] 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 bus bar 144, which also electrically connects them together to form a neutral point of a wye winding arrangement. The bus bar 144 may be disposed above the bus bars 104 in the holding groove 115.

[0060] As described above, there may be a plurality of neutral structures 110 each of which may be a unitary structure stamped or cast from conductive metal. It should be appreciated, however, that in other embodiments, a single neutral bus bar formed from one or more lengths of coated flat wire 18 may be used instead of the neutral structures 110. In theseembodiments, the neutral bus bar may be disposed in the holding groove 115 inside the housing 102 and may be arranged concentrically with the bus bars 104, with its planar surfaces 24 extending vertically. A top side edge 26 of the neutral bus bar may face upwardly and may contain recesses 140. Neutral attachment structures having the same construction as the attachment structures 106 may be welded into the recesses 140. The neutral attachment structures may have neutral connectors that are interleaved with the attachment structures 106a,b,c in the same manner as the neutral connectors 131 or in a different manner.

[0061] 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 bars 104. The insulating material displaces air gaps that may otherwise exist between and / or around the bus bars 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.

[0062] It is to be understood that the description of the foregoing exemplary embodiment(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 bus bar assembly, comprising: bus bars arranged in a stack comprising two or more layers of the bus bars, each of the layers of the bus bars having one or more of the bus bars, wherein each bus bar has opposing major surfaces and opposing side edges, at least one of the side edges of each bus bar having a recess formed therein, wherein each bus bar comprises one or more lengths of coated flat wire having a metal conductor coated with one or more layers of one or more insulating coatings, and wherein each bus bar has a width-to-thickness ratio of from about 2 to about 8; and attachment structures secured in the recesses of the bus bars, respectively, each of the attachment structures being configured for securement to a power conductor for conveying power.

2. The bus bar assembly of claim 1, wherein the bus bars are flexible and manually bendable.

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

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

5. The bus bar assembly of claim 1 , wherein the stack of the bus bars is at least partially disposed inside a housing formed from electrically insulating plastic.

6. The bus bar assembly of claim 1 , wherein the stack of the bus bars comprises a first layer adjoining a second layer, the first layer comprising a single bus bar and the second layercomprising a plurality of spaced-apart bus bars, thereby making the second layer discontinuous.

7. The bus bar assembly of claim 1 , wherein the bus bars are straight.

8. The bus bar assembly of claim 7, wherein the bus bars each have first and second ends, first and second side edges, and first and second recesses disposed toward the first and second ends, respectively, and wherein in a first one of the bus bars, the first recess is formed in the first side edge and the second recess is formed in the second side edge, and wherein in a second one of the bus bars, the first recess is formed in the second side edge and the second recess is formed in the first side edge.

9. The bus bar assembly of claim 8, wherein the first one of the bus bars is disposed on top of the second one of the bus bars to form the stack, such that the first ends of the bus bars are aligned to form a first end of the stack and the second ends of the bus bars are aligned to form a second end of the stack, and wherein a first pair of the attachment structures located toward the first end of the stack extend in opposite directions, and a second pair of the attachment structures located toward the second end of the stack extend in opposite directions.

10. The bus bar assembly of claim 9, wherein the stack of the bus bars is disposed inside a rectangular housing formed from electrically insulating plastic, wherein the housing has planar major walls and planar side walls, and wherein the attachment structures extend through openings in the side walls.11 . The bus bar assembly of claim 10, wherein the attachment structures comprise ring terminals.

12. The bus bar assembly of claim 1 , wherein the bus bars comprise a neutral bus bar and a plurality of power bus bars for connection to different phases of an AC power source.

13. The bus bar assembly of claim 12, wherein the bus bar assembly is curved and is configured for distributing AC power to coils of a stator of an electric motor, wherein the attachment structures are configured for securement to wires of stator coils, respectively, to electrically connect the bus bars to the stator coils.

14. The bus bar assembly of claim 12, wherein the neutral bus bar has a plurality of the recesses formed in one of its side edges, wherein the power bus bars each have one or more of the recesses formed in one of its side edges, wherein the attachment structures each have a base joined to one or more fasteners, and wherein the bases of the attachment structures conform to the recesses in the bus bars such that the bases fit into the recesses.

15. The bus bar assembly of claim 14, wherein the bases of the attachment structures are welded into the recesses of the bus bars.

16. The bus bar assembly of claim 14, wherein the power bus bars have holes formed in them; and wherein the bus bar assembly further comprises terminal structures for connection to the AC power source, the terminal structures comprising mounting arms having portions secured in the holes of the power bus bars to physically and electrically connect the terminal structures to the power bus bars, respectively.

17. The bus bar assembly of claim 16, wherein ends of the mounting arms are joined to ring-shaped terminal holders, the mounting arms spacing the terminal holders above the power bus bars and the neutral bus bar.

18. The bus bar assembly of claim 14, wherein the neutral bus bar comprises a lower layer and the power bus bars comprise an upper layer, the power bus bars being spaced apart, thereby making the upper layer discontinuous.

19. The bus bar assembly of claim 14, wherein the attachment structures are unitary structures, and wherein each base is joined to a plurality of spaced-apart fasteners configured for connection to wires.

20. The bus bar assembly of claim 1 , wherein the stack of the bus bars is at least partially disposed inside a housing formed from electrically insulating plastic; and wherein the stack of the bus bars is horizontally disposed in the housing.

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