Stator assembly, motor provided with same, and method for assembling stator assembly

Abstract

This stator assembly of a motor comprises a stator subassembly and a bus bar assembly. The stator subassembly comprises an annular yoke, a plurality of teeth attached to the inner circumferential surface of the yoke at intervals, and a plurality of coils respectively attached to the plurality of teeth. Each of the plurality of coils has, at both ends thereof, lead parts that protrude along the axial direction, which is the direction of the axial center of a rotary shaft of the motor. The bus bar assembly includes: a plurality of first bus bars that are each a wire rod having a rectangular cross section and electrically connect an external power supply and the plurality of coils; and a bus bar guide that is made of an insulating material and is provided with a plurality of grooves for respectively holding the plurality of first bus bars. Each of the plurality of first bus bars has a first base section, a first terminal end section, and an external connection terminal section. The first base section, the first terminal end section, and the external connection terminal section are integrally formed by bending and folding the wire rod a plurality of times. The first base section is fitted into the corresponding groove such that a lateral surface parallel to the short-side direction of the rectangle is in contact with the bottom surface of the groove. The first terminal end section protrudes upward along the axial direction by being bent and folded in the long-side direction of the rectangle in the vicinity of both ends of the first base section. The external connection terminal section is formed by bending the first base section outward in the radial direction of the motor at the intermediate portion, and further folding back the first base section inward in the radial direction, thereby protruding outward in the radial direction from the first base section. The plurality of grooves provided in the bus bar guide are separated from each other. The first base sections of the plurality of first bus bars are arranged apart from each other in the radial direction in the bus bar guide.

Description

Stator assembly, motor including same, and method for assembling stator assembly

[0001] The present disclosure relates to a stator assembly, a motor including the same, and a method for assembling the stator assembly.

[0002] 2. Description of the Related Art Conventionally, in a stator assembly provided in a motor, a configuration using a plate-shaped bus bar to connect a plurality of coils is widely known.

[0003] For example, Patent Document 1 discloses a configuration in which a ring-shaped connecting plate provided on the top of a stator core has multiple grooves, and bus bars made of strip-shaped conductors are fitted into and held in place.

[0004] The busbars described in Patent Document 1 are generally formed by press-punching a plate made of a conductive material such as metal using a die. However, this method has the problem of low yield when punching the plate. Furthermore, since a new die is required when the shape of the busbar changes, it is not suitable for small-lot, high-mix production.

[0005] Conventionally, techniques for forming bus bars by bending linear conductor wires have been proposed. For example, Patent Document 2 discloses a configuration for forming bus bars by bending a round wire having a circular cross section. Patent Document 3 discloses a configuration for forming bus bars by crushing a round wire to form a wire having a substantially rectangular cross section and then bending the wire.

[0006] However, in some cases, a larger current flows through the connection portion of the bus bar to the external power supply than through other portions, such as when coils of the same phase are connected in parallel in a stator assembly.

[0007] However, in the conventional bus bars disclosed in Patent Documents 1 and 3, the cross-sectional area of ​​the connection portion with the external power supply is the same as the cross-sectional area of ​​the other portions. As a result, the current density becomes high at the connection portion with the external power supply, causing the temperature to rise during use of the motor. This increases the resistance of the bus bar and also causes the temperature of the stator core and coils near the connection portion with the external power supply, which may result in a decrease in motor performance.

[0008] Furthermore, the conventional bus bars disclosed in Patent Documents 2 and 3 require the bus bar itself to have multiple bent portions that protrude outward in the circumferential direction in order to connect to the coil, but this increases the radial size of the bus bar, and therefore the stator assembly.

[0009] Furthermore, in the conventional bus bars disclosed in Patent Documents 2 and 3, the bus bars carrying currents of different phases are arranged spaced apart from each other in the axial direction, which is the extension direction of the rotating shaft of the motor, which increases the axial size of the stator assembly.

[0010] Japanese Patent Laid-Open No. 11-018345 Japanese Patent Laid-Open No. 2003-324887 Japanese Patent Laid-Open No. 2009-124927

[0011] The present disclosure has been made in view of the above points, and an object of the present disclosure is to provide a stator assembly that can suppress a local increase in current density in a bus bar and suppress an increase in radial and axial sizes, a motor including the same, and an assembling method for the stator assembly.

[0012] To achieve the above object, the present disclosure provides a stator assembly for a motor, comprising a stator subassembly and a busbar assembly. The stator subassembly comprises an annular yoke, a plurality of teeth attached to the inner peripheral surface of the yoke at intervals, and a plurality of coils attached to the plurality of teeth, respectively. The coils have lead portions at both ends that protrude in the axial direction, which is the axial direction of the rotating shaft of the motor. the bus bar assembly includes: a plurality of first bus bars made of wire rod having a rectangular cross section and electrically connecting an external power supply to the plurality of coils; and a bus bar guide made of an insulating material and provided with a plurality of grooves for holding the plurality of first bus bars, each of the plurality of first bus bars having a first base portion, a first end portion, and an external connection terminal portion, the first base portion, the first end portion, and the external connection terminal portion being integrally formed by bending the wire rod multiple times, and the first base portion being fitted into the groove such that a side surface parallel to a short side direction of the rectangle contacts a bottom surface of the groove, The first terminal end portion is a portion that protrudes upward along the axial direction by being bent in the direction of the long side of the rectangle near both ends of the first base portion, and the external connection terminal portion is a portion that protrudes radially outward from the first base portion by being bent outward in the radial direction, which is the radial direction of the motor, at an intermediate portion and then folded back radially inward, and the multiple grooves provided in the busbar guide are separated from one another, and the multiple first bases that each of the multiple first busbars has are arranged radially spaced apart from one another in the busbar guide.

[0013] The motor according to the present disclosure includes the stator assembly, and a rotor assembly provided at a predetermined distance from the stator assembly in the radial direction.

[0014] a first bus bar provided in each of the plurality of grooves formed on the outermost periphery of the bus bar guide, and a second bus bar provided in each of the plurality of grooves formed on the outermost periphery of the bus bar guide, the first bus bar being fitted into each of the plurality of grooves formed on the outermost periphery of the bus bar guide, and the first to third terminal ends of the first to third bus bars and the intermediate connection portion of the third bus bar being connected to the lead portions, respectively.

[0015] According to the present disclosure, it is possible to suppress an increase in current density in the bus bar at the connection portion with the external power supply, and also to suppress an increase in the radial size of the stator assembly.

[0016] FIG. 1 is a view of a motor according to an embodiment, as viewed in the axial direction. FIG. 2A is a perspective view of a stator assembly according to an embodiment. FIG. 2B is an exploded perspective view of the stator assembly according to an embodiment. FIG. 3 is a wiring diagram of a motor according to an embodiment. FIG. 4 is an exploded perspective view of a busbar assembly according to an embodiment. FIG. 5A is a view of a busbar subassembly according to an embodiment, as viewed in the axial direction. FIG. 5B is a perspective view of a U-phase lead wire. FIG. 5C is a perspective view of a V-phase lead wire. FIG. 5D is a perspective view of a W-phase lead wire. FIG. 6A is an enlarged view of an external connection terminal portion of a busbar subassembly according to an embodiment. FIG. 6B is an enlarged view of an external connection terminal portion of a busbar subassembly according to an embodiment, as viewed in the axial direction. FIG. 7A is a view of three first in-phase series-connected busbars, as viewed in the axial direction. FIG. 7B is a perspective view of a first in-phase series-connected busbar. FIG. 8A is a view of three second in-phase series-connected busbars, as viewed in the axial direction. FIG. 8B is a perspective view of a second in-phase series-connected busbar. FIG. 9A is a view of two sets of neutral point busbars as viewed in the axial direction. FIG. 9B is a perspective view of one set of neutral point busbars. FIG. 10 is a view of a busbar guide as viewed in the axial direction. FIG. 11A is a process explanatory diagram of a method for assembling a stator assembly according to an embodiment. FIG. 11B is a process explanatory diagram continuing from FIG. 11A. FIG. 11C is a process explanatory diagram continuing from FIG. 11B. FIG. 12A is a diagram showing a connection state between a neutral point busbar and a lead portion of a coil. FIG. 12B is a schematic cross-sectional view of a portion surrounded by a dashed line in FIG. 12A. FIG. 12C is a schematic cross-sectional view of a portion surrounded by a dashed line in FIG. 12A. FIG. 13A is a perspective view of a busbar subassembly according to an embodiment. FIG. 13B is a perspective view of a busbar subassembly according to Modification 1. FIG. 14 is a schematic view showing a state in which a U-phase lead wire and an external connection wire are connected according to Modification 2.

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0018] (Embodiment) [Motor Configuration] Fig. 1 is a view of a motor 300 according to an embodiment as viewed along the axial direction. Fig. 2A is a perspective view of a stator assembly 100 according to an embodiment. Fig. 2B is an exploded perspective view of the stator assembly 100. Fig. 3 is a wiring diagram of the motor 300.

[0019] In the following description, the radial direction of the motor 300 will be referred to as the "radial direction," the outer circumferential direction as the "circumferential direction," and the extension direction of the rotating shaft 210 of the motor 300 (also referred to as the axial direction; the direction perpendicular to the paper surface in FIG. 1 ) as the "axial direction." In the radial direction, the axial side of the motor 300 will be referred to as the radially inner side, and the outer circumferential side will be referred to as the radially outer side. The outer circumferential direction of the motor 300 is the same as the outer circumferential direction of the stator assembly 100 and the bus bar assembly 60, which will be described later. Therefore, the outer circumferential direction of the bus bar assembly 60 will also be referred to as the "circumferential direction." Similarly, the radial direction of the motor 300 is the same as the radial direction of the stator assembly 100 and the bus bar assembly 60. Therefore, the radial direction of the bus bar assembly 60 will also be referred to as the "circumferential direction." In the motor 300, the side on which the bus bar assembly 60 is provided will be referred to as the upper side, and the opposite side along the axial direction will be referred to as the lower side. When viewed in the axial direction, the axis of the motor 300 coincides with the axis of the rotating shaft 210 .

[0020] In this specification, "parallel" or "same" means being parallel or the same, including the assembly tolerances and processing tolerances of the motor 300 or its component parts, the stator assembly 100 or the busbar assembly 60. "Parallel" or "same" does not mean that the objects being compared are parallel or the same in the strict sense.

[0021] The motor 300 has a stator assembly 100 and a rotor assembly 200. The motor 300 also has other components, such as a motor case that houses the stator assembly 100 and the rotor assembly 200, and a bearing that supports the rotating shaft 210. However, for the sake of convenience, illustration and description of these components will be omitted.

[0022] 1 and 2B , the stator assembly 100 includes a stator subassembly 80 and a busbar assembly 60. The stator subassembly 80 includes an annular yoke 20 and a plurality of teeth 10 connected to the inner peripheral surface of the yoke 20 and arranged at equal intervals along the inner peripheral surface. The stator subassembly 80 includes slots 30 arranged between each pair of circumferentially adjacent teeth 10, coils 40 housed in the slots 30, and insulators 50 attached to the outer peripheral surfaces of the teeth 10. The stator subassembly 80 is disposed radially outward from the rotor assembly 200 at a fixed interval.

[0023] The teeth 10 and the yoke 20 are each formed, for example, by laminating and punching electromagnetic steel sheets containing silicon or the like. The coil 40 is a component formed by spirally winding a conductor wire made of copper or the like and having a rectangular cross section. The coil 40 has lead portions 41 (see FIGS. 2A and 2B ) at both ends. The coil 40 is attached to each of the multiple teeth 10 with an insulator 50 sandwiched therebetween and housed in the slot 30. Although not shown, an insulating coating is formed on the surface of the conductor wire constituting the coil 40. The lead portions 41 protrude upward along the axial direction. As described later, various bus bars included in the bus bar assembly 60 are connected to each lead portion 41 by welding or the like. The configuration of the bus bar assembly 60 will be described in detail later.

[0024] In this embodiment, the multiple coils 40 may be referred to as coils U1 to U4, V1 to V4, and W1 to W4, respectively, depending on the phase of the current flowing through the coils 40 (see FIG. 3).

[0025] The rotor assembly 200 has a rotating shaft 210, a rotor core 220 having the rotating shaft 210 at its axis, and a plurality of magnets 230. The plurality of magnets 230 are embedded inside the rotor core 220. The plurality of magnets 230 are arranged with their north and south poles alternately arranged along the circumferential direction of the rotating shaft 210, facing the stator assembly 100. The material, shape, and composition of the magnets 230 can be changed as appropriate depending on the output of the motor 300, etc. The rotor core 220 is formed, for example, by laminating electromagnetic steel sheets containing silicon or the like and then punching them out.

[0026] As shown in FIG. 3 , coils U1 and U2 are connected in series. Coils U3 and U4 are connected in series. Coils U1 and U2 are connected in parallel with coils U3 and U4. The connection relationships of coils V1 to V4 and coils W1 to W4 are the same as the connection relationships of coils U1 to U4, respectively. In other words, in the stator subassembly 80, two sets of series-connected coils, each consisting of two coils 40, are provided, and currents of the same phase (hereinafter referred to as in-phase currents) flow through the two sets of series-connected coils connected in parallel. As shown in FIG. 3 , of the four coils 40 through which in-phase currents flow, two coils 40 included in one set of series-connected coils are electrically connected via either the first in-phase series-connected bus bars 65A to 65C or the second in-phase series-connected bus bars 66A to 66C.

[0027] Three-phase currents, U-phase, V-phase, and W-phase, which have a phase difference of 120° electrical angle from one another, are supplied to coils U1 to U4, coils V1 to V4, and coils W1 to W4 via bus bar assembly 60, respectively, to excite them, generating a rotating magnetic field in stator assembly 100. An interaction occurs between this rotating magnetic field and the magnetic field generated by magnet 230 provided in rotor assembly 200, generating torque, and rotating shaft 210 is supported by bearings (not shown) and rotates.

[0028] [Configuration of Busbar Assembly and Its Components] Figure 4 is an exploded perspective view of the busbar assembly 60. Figure 5A is a view of the busbar subassembly 69 as viewed in the axial direction. Figure 5B is a perspective view of the U-phase lead wire 61. Figure 5C is a perspective view of the V-phase lead wire 62. Figure 5D is a perspective view of the W-phase lead wire 63. Figure 6A is an enlarged view of the external connection terminal portion of the busbar subassembly 69. Figure 6B is an enlarged view of the external connection terminal portion of the busbar subassembly 69 as viewed in the axial direction. For ease of explanation, the terminal mold portion 64 is omitted from Figures 6A and 6B.

[0029] Fig. 7A is a view of three first in-phase series connection bus bars 65A to 65C as viewed along the axial direction. Fig. 7B is a perspective view of each of the first in-phase series connection bus bars 65A to 65C. Fig. 8A is a view of three second in-phase series connection bus bars 66A to 66C as viewed along the axial direction. Fig. 8B is a perspective view of each of the second in-phase series connection bus bars 66A to 66C. Fig. 9A is a view of two sets of neutral point bus bars 67 as viewed along the axial direction. Fig. 9B is a perspective view of one set of neutral point bus bars 67. Fig. 10 is a view of the bus bar guide 70 as viewed along the axial direction.

[0030] 4, the busbar assembly 60 includes three first in-phase series connection busbars 65A to 65C, three second in-phase series connection busbars 66A to 66C, two sets of neutral busbars 67, a busbar subassembly 69, and a busbar guide 70. The first in-phase series connection busbars 65A to 65C, the second in-phase series connection busbars 66A to 66C, the two sets of neutral busbars 67, and the busbar subassembly 69 are positioned relative to one another by being fitted into a plurality of grooves 71 (see FIG. 10) that are provided in the busbar guide 70 and extend in the circumferential direction.

[0031] As shown in Figures 4 and 5A, the busbar subassembly 69 includes a U-phase lead wire 61, a V-phase lead wire 62, a W-phase lead wire 63, and a terminal mold portion 64. As shown in Figures 5A, 6A, and 6B, the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 are radially spaced apart from one another. That is, the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 are electrically isolated from one another. The external connection terminal portions 61c, 62c, and 63c of the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 are held and fixed in a terminal mold portion 64 made of insulating resin. The terminal mold portion 64 is formed by insert molding or the like, with the external connection terminal portions 61c, 62c, and 63c positioned relative to one another. By providing the terminal mold portion 64 in this manner, the external connection terminal portions 61c, 62c, 63c are held and fixed in a state where they are positioned relative to one another, and further, are electrically insulated from one another.

[0032] The U-phase lead wire 61 is obtained by bending a wire made of a conductor with a rectangular cross section, for example, a single rectangular wire. The rectangular wire is obtained, for example, by press-punching a copper plate. As shown in FIG. 5B , the U-phase lead wire 61 has a base portion 61a (also referred to as a first base portion 61a), two end portions 61b (also referred to as first end portions 61b), and an external connection terminal portion 61c. The short side of the cross section corresponds to the thickness of the U-phase lead wire 61, and the long side corresponds to the width.

[0033] The U-phase lead wire 61 is attached to the bus bar guide 70 so that its thickness direction, in other words, the side parallel to the short side direction of the rectangle, contacts the bottom surface of the groove 71 of the bus bar guide 70. For this reason, as shown in FIG. 5B , the base 61a is bent multiple times in the thickness direction to match the shape of the groove 71 when viewed in the axial direction. That is, the base 61a is flatwise bent at multiple locations. The base 61a is also bent in the width direction near both ends of the U-phase lead wire 61. That is, the base 61a is edgewise bent near both ends of the U-phase lead wire 61. The portion of the base 61a bent in the width direction near one end of the U-phase lead wire 61 is bent radially inward and then further bent upward along the axial direction. The portion bent upward along the axial direction corresponds to one end 61b.

[0034] The portion of the base 61a that is bent in the width direction near the other end of the U-phase lead wire 61 is bent radially outward, then folded back radially inward, and then bent upward along the axial direction. The portion bent upward along the axial direction corresponds to the other end 61b.

[0035] On the other hand, the radially bent portion corresponds to the external connection terminal portion 61c. In other words, the external connection terminal portion 61c is formed by overlapping bent rectangular wires. A bolt insertion hole 61d is formed through the overlapped portion of the external connection terminal portion 61c. A gap with a predetermined radius of curvature is formed in the folded portion 61c1, which is the tip portion of the external connection terminal portion 61c. In other words, the folded rectangular wires do not contact each other at the folded portion 61c1.

[0036] As shown in FIG. 5C , like the U-phase lead wire 61, the V-phase lead wire 62 has a base 62a (also referred to as a first base 62a), two end portions 62b (also referred to as first end portions 62b), and an external connection terminal portion 62c. As shown in FIG. 5D , like the U-phase lead wire 61, the W-phase lead wire 63 has a base 63a (also referred to as a first base 63a), two end portions 63b (also referred to as first end portions 63b), and an external connection terminal portion 63c. The base portions 62a and 63a are also bent multiple times in the thickness direction to fit the shape of the groove 71 when viewed axially. In other words, like the U-phase lead wire 61, the V-phase lead wire 62 and the W-phase lead wire 63 are attached to the busbar guide 70 so that the side surfaces parallel to the thickness direction contact the bottom surfaces of the grooves 71 of the busbar guide 70.

[0037] The base 62a is bent in the width direction near both ends of the V-phase lead wire 62. The base 63a is bent in the width direction near both ends of the W-phase lead wire 63. The portions of the base 62a of the V-phase lead wire 62 that are bent upward in the axial direction at both ends are the terminal ends 62b and vb. The portions of the base 63a of the W-phase lead wire 63 that are bent upward in the axial direction at both ends are the terminal ends 63b.

[0038] The external connection terminals 62c and 63c have the same structure as the external connection terminal 61c. That is, the external connection terminals 62c and 63c have folded portions 62c1 and 63c1 and bolt insertion holes 62d and 63d, respectively. The folded portions 62c1 and 63c1 have the same structure as the folded portion 61c1.

[0039] The V-phase lead wire 62 and the W-phase lead wire 63 differ from the U-phase lead wire 61 in the arrangement of the external connection terminal portions 62c, 63c, respectively. As shown in FIG. 5C , in the V-phase lead wire 62, the base portion 62a is bent in the width direction at the middle portion, directed upward, and then bent radially outward and folded back. The portion bent radially and further folded back corresponds to the external connection terminal portion 62c. As shown in FIG. 5D , in the W-phase lead wire 63, the base portion 63a is bent in the width direction at the middle portion, directed upward, and then bent radially outward and folded back. The portion bent radially and further folded back corresponds to the external connection terminal portion 63c. The position of the external connection terminal portion 62c in the V-phase lead wire 62 differs from the position of the external connection terminal portion 63c in the W-phase lead wire 63. This is because the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 are each disposed in different positions on the bus bar guide 70. This is to ensure smooth and reliable connection between the external connection terminals 61c, 62c, and 63c and the external power source. The latter will be described in more detail below.

[0040] 6A and 6B , the external connection terminals 61c, 62c, and 63c are spaced apart from one another in the circumferential direction. When viewed along the axial direction, the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 overlap each other in the circumferential direction. Therefore, the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 are attached to different grooves 71 of the busbar guide 70 so as to be spaced apart from one another in the radial direction.

[0041] When viewed along the axial direction, the radial lengths of the external connection terminals 61c, 62c, and 63c are different. In the example shown in Figures 6A and 6B, the external connection terminal 61c is the longest. The lengths of the external connection terminals 62c and 63c decrease in this order. The bolt insertion holes 61d, 62d, and 63d are arranged in a straight line along the circumferential direction.

[0042] By defining the arrangements and shapes of the U-phase lead wire 61, the V-phase lead wire 62, the W-phase lead wire 63, and the external connection terminals 61c, 62c, and 63c as described above, an external power source can be connected to the external connection terminals 61c, 62c, and 63c via the external connection wires without shorting each other. Although not shown, the ends of the external connection wires are flat plates with through holes. The through holes of the external connection wires are aligned with the bolt insertion holes 61d, 62d, and 63d, respectively, and bolts (not shown) are inserted into these holes and tightened. In this manner, the U-phase external connection wire is connected to the external connection terminal 61c, the V-phase external connection wire is connected to the external connection terminal 62c, and the W-phase external connection wire is connected to the external connection terminal 63c, respectively. In the following description, the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 may be collectively referred to as first bus bars 61, 62, and 63.

[0043] The first in-phase series connection bus bars 65A to 65C are used to connect in series two coils 40 through which in-phase currents flow. Specifically, as shown in Fig. 3, the first in-phase series connection bus bar 65A connects coil U1 and coil U2. The first in-phase series connection bus bar 65B connects coil V1 and coil V2. The first in-phase series connection bus bar 65C connects coil W1 and coil W2.

[0044] 7A , the three first in-phase series connection bus bars 65A to 65C are fitted into different grooves 71 of the bus bar guide 70 and attached to the bus bar guide 70. As with the U-phase lead wire 61, each of the three first in-phase series connection bus bars 65A to 65C is attached to the bus bar guide 70 so that the side surface parallel to the thickness direction is in contact with the bottom surface of the groove 71 of the bus bar guide 70.

[0045] As shown in FIG. 7B , the first in-phase series connection bus bar 65A has a base 65Aa (also referred to as a second base 65Aa) and two end portions 65Ab (also referred to as second end portions 65Ab). Like the U-phase lead wire 61, the base 65Aa is bent multiple times in the thickness direction to match the shape of the groove 71 when viewed in the axial direction. That is, the base 65Aa is flatwise bent at multiple locations. The base 65Aa is bent in the width direction near both ends of the first in-phase series connection bus bar 65A. That is, the base 65Aa is edgewise bent near both ends of the first in-phase series connection bus bar 65A. The portions of the base 65Aa bent in the width direction near both ends of the first in-phase series connection bus bar 65A are bent radially inward and then further bent upward along the axial direction. The portions bent upward along the axial direction correspond to the end portions 65Ab.

[0046] As shown in FIG. 7B , the first in-phase series connection busbars 65B, 65C have the same shape as the first in-phase series connection busbar 65A. That is, the first in-phase series connection busbar 65B has a second base portion 65Ba and a second terminal portion 65Bb, and the first in-phase series connection busbar 65C has a second base portion 65Ca and a second terminal portion 65Cb. However, the length of the second base portions 65Aa to 65Ca and the number of bent portions are appropriately changed depending on the circumferential distance of the coil 40 to be connected. Unlike the U-phase lead wire 61, the first in-phase series connection busbars 65A to 65C do not have external connection terminal portions 61c, 62c, and 63c. That is, the first in-phase series connection busbars 65A to 65C do not have a portion where two wires are bent radially outward and then folded back to overlap each other.

[0047] The second in-phase series connection busbars 66A to 66C are also used to connect in series two coils 40 through which the same-phase current flows. Specifically, as shown in FIG. 3 , the second in-phase series connection busbar 66A connects coil U3 and coil U4. The second in-phase series connection busbar 66B connects coil V3 and coil V4. The second in-phase series connection busbar 66C connects coil W3 and coil W4. Therefore, as shown in FIG. 8A , the three second in-phase series connection busbars 66A to 66C are attached to the busbar guide 70 by being fitted into different grooves 71 in the busbar guide 70. As with the U-phase lead wire 61, each of the three second in-phase series connection busbars 66A to 66C is attached to the busbar guide 70 so that the side surface parallel to the thickness direction contacts the bottom surface of the groove 71 in the busbar guide 70.

[0048] As shown in FIG. 8B , the second in-phase series connection bus bar 66A has a base 66Aa (also referred to as a second base 66Aa) and two end portions 66Ab (also referred to as second end portions 66Ab). Like the U-phase lead wire 61, the base 66Aa is bent multiple times in the thickness direction to match the shape of the groove 71 when viewed in the axial direction. That is, the base 66Aa is flat-wise bent at multiple locations. The base 66Aa is bent in the width direction near both ends of the second in-phase series connection bus bar 66A. That is, the base 66Aa is edge-wise bent near both ends of the second in-phase series connection bus bar 66A. The portions of the base 66Aa bent in the width direction near both ends of the second in-phase series connection bus bar 66A are bent radially inward and then further bent upward along the axial direction. The portions bent upward along the axial direction correspond to the end portions 66Ab.

[0049] As shown in FIG. 8B , the second in-phase series connection busbars 66B, 66C have the same shape as the second in-phase series connection busbar 66A. That is, the second in-phase series connection busbar 66B has a second base portion 66Ba and a second terminal portion 66Bb, and the second in-phase series connection busbar 66C has a second base portion 66Ca and a second terminal portion 66Cb. The length of the second base portions 66Aa-66Ca and the number of bent portions are appropriately changed depending on the circumferential distance of the coil 40 to be connected. Like the first in-phase series connection busbars 65A-65C, the second in-phase series connection busbars 66A-66C do not have external connection terminal portions 61c, 62c, and 63c. That is, the second in-phase series connection busbars 66A-66C do not have portions where two wires are bent radially outward and then folded back to overlap each other. In the following description, the first in-phase series connection bus bars 65A to 65C and the second in-phase series connection bus bars 66A to 66C may be collectively referred to as second bus bars 65A to 65C and 66A to 66C.

[0050] As shown in Fig. 3, the neutral point bus bar 67 constitutes the neutral point of the stator assembly 100 of the motor 300. In this embodiment, two sets of neutral point bus bars 67 are provided in the bus bar subassembly 69 to match the number of parallel connections of the coils 40 of the same phase. In the following description, the neutral point bus bar 67 may be referred to as the third bus bar 67.

[0051] As shown in Fig. 9A, two sets of neutral point bus bars 67 are attached to a bus bar guide 70 with a circumferential gap between them. As shown in Fig. 9B, the neutral point bus bar 67 is formed by connecting two sub-bus bars 67A and 67B. As with the U-phase lead wire 61, each of the two sets of neutral point bus bars 67 is attached to the bus bar guide 70 so that the side surface parallel to the thickness direction is in contact with the bottom surface of the groove 71 in the bus bar guide 70.

[0052] The sub-busbar 67A has a base 67Aa (also referred to as a third base 67Aa), a terminal end 67Ab (also referred to as a third terminal end 67Ab), and an intermediate connection portion 67Ac. The base 67Aa is bent once in the thickness direction to match the shape of the groove 71 when viewed in the axial direction. The base 67Aa is also bent in the width direction near both ends of the sub-busbar 67A. The portion of the base 67Aa bent in the width direction near one end of the sub-busbar 67A is bent radially inward and then further bent upward along the axial direction. The portion bent upward along the axial direction corresponds to the terminal end 67Ab. The portion of the base 67Aa bent in the width direction near the other end of the sub-busbar 67A is also bent radially inward and then further bent upward along the axial direction. The portion bent upward along the axial direction corresponds to the intermediate connection portion 67Ac.

[0053] The sub-busbar 67B has the same shape as the sub-busbar 67A. The sub-busbar 67B has a base 67Ba (also referred to as a third base 67Ba), a terminal end 67Bb (also referred to as a third terminal end 67Bb), and an intermediate connection portion 67Bc. The base 67Ba is bent once in the thickness direction to match the shape of the groove 71 when viewed in the axial direction. The base 67Ba is also bent in the width direction near both ends of the sub-busbar 67B. The portion of the base 67Ba bent in the width direction near one end of the sub-busbar 67B is bent radially inward and then further bent upward along the axial direction. The portion bent upward along the axial direction corresponds to the terminal end 67Bb. The portion of the base 67Ba bent in the width direction near the other end of the sub-busbar 67B is also bent radially inward and then further bent upward along the axial direction. The portion bent upward along the axial direction corresponds to the intermediate connecting portion 67Bc.

[0054] 9B , the intermediate connection portion 67Ac of the sub-bus bar 67A and the intermediate connection portion 67Bc of the sub-bus bar 67B are joined together in a radially overlapping state to obtain the neutral bus bar 67. When actually connecting the intermediate connection portion 67Ac and the intermediate connection portion 67Bc, the lead portion 41 of the coil is also joined together, as will be described in more detail later.

[0055] The bus bar guide 70 is made of insulating resin and has a plurality of grooves 71 formed therein. As described above, a plurality of bus bars of different types are attached to the bus bar guide 70. Many of these bus bars must be electrically isolated from one another. For example, the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 must be electrically isolated from one another. The first in-phase series connection bus bars 65A to 65C and the second in-phase series connection bus bars 66A to 66C must be electrically isolated from one another. For this reason, the bus bar guide 70 has a groove 71 formed for each bus bar, including the neutral bus bar 67, and the plurality of grooves 71 are separated so as not to intersect with one another.

[0056] In order to electrically isolate at least two bus bars included in the bus bar assembly 60 from one another, the multiple grooves 71 are arranged at different distances from the center of the bus bar guide 70. However, it is not necessary for each of the eleven grooves 71 to be arranged at different distances from the center of the bus bar guide 70. In this embodiment, as shown in FIG. 10 , a maximum of four grooves 71 are arranged at different positions along the radial direction of the bus bar guide 70 when viewed along the axial direction.

[0057] Of the lead portions 41 at both ends of the coil 40, one is located radially inward and the other is located radially outward. To connect to the lead portions 41, one of the pair of end portions of each of the U-phase lead wire 61, V-phase lead wire 62, W-phase lead wire 63, first in-phase series connection bus bars 65A to 65C, and second in-phase series connection bus bars 66A to 66C must be located radially inward and the other radially outward. Therefore, the grooves 71 in which the U-phase lead wire 61, V-phase lead wire 62, W-phase lead wire 63, first in-phase series connection bus bars 65A to 65C, and second in-phase series connection bus bars 66A to 66C are disposed are arranged such that their ends are not equidistant from the center of the bus bar guide 70 as viewed along the axial direction. Similarly, the grooves 71 in which the two neutral point bus bars 67 are disposed are arranged such that their ends are not equidistant from the center of the bus bar guide 70 as viewed along the axial direction.

[0058] 5C and 5D, the V-phase lead wire 62 and the W-phase lead wire 63 are formed by bending external connection terminal portions 62c, 63c from the intermediate portions of the first base portions 62a, 63a, respectively. Therefore, if the grooves 71 along the radial direction are designated as the first to fourth turns from the innermost circumference as shown in FIG. 10, the first base portion 62a is divided into the groove 71 on the third turn and the groove 71 on the fourth turn, with the external connection terminal portion 62c sandwiched between them. The first base portion 63a is divided into the groove 71 on the third turn and the groove 71 on the fourth turn, with the external connection terminal portion 63c sandwiched between them.

[0059] On the other hand, as shown in FIG. 5B , in the U-phase lead wire 61, the external connection terminal portion 61c is formed by bending from near the end of the first base portion 61a. As shown in FIG. 10 , the groove 71 into which the first base portion 61a is fitted is continuous in the circumferential direction. Meanwhile, the radial position of the groove 71 on the busbar guide 70 varies along the circumferential direction so that one end of the groove 71 is located at the same radial position as the groove 71 on the first turn. This same principle applies to the grooves 71 in which the first in-phase series connection busbars 65A to 65C are disposed. The same applies to the grooves 71 in which the second in-phase series connection busbars 66A to 66C and the neutral point busbar 67 are disposed.

[0060] In other words, except for the groove 71 located on the innermost periphery, the grooves 71 into which the bus bars included in the bus bar assembly 60 are fitted vary in radial position on the bus bar guide 70 along the circumferential direction, regardless of whether they are continuous in the circumferential direction or not, so that one end of each groove approaches the first groove 71 in the radial direction. In particular, when the base of a bus bar is fitted into the same continuous groove 71, the radial position of the groove 71 on the bus bar guide 70 varies along the circumferential direction so that one end of each groove is in the same radial position as the first groove 71.

[0061] The number and circumferential length of the bus bars provided in the bus bar assembly 60 may be changed as appropriate depending on the number and connection method of the coils 40 included in the stator assembly 100. The number, circumferential length, and arrangement of the grooves 71 provided in the bus bar guide 70 may also be changed as appropriate.

[0062] [Method of assembling stator assembly] Fig. 11A is a process explanatory diagram of a method of assembling the stator assembly 100. Fig. 11B is a process explanatory diagram continuing from Fig. 11A. Fig. 11C is a process explanatory diagram continuing from Fig. 11B.

[0063] Fig. 12A is a diagram showing the connection state between the neutral bus bar 67 and the lead portion 41 of the coil 40. Fig. 12B is a schematic cross-sectional view of the portion surrounded by the dashed line in Fig. 12A. Fig. 12C is a schematic cross-sectional view of the portion surrounded by the dashed line in Fig. 12A.

[0064] To assemble the stator assembly 100, first prepare the stator subassembly 80 shown in FIGS. 2A and 2B . Specifically, an insulator 50 is attached to each of the multiple teeth 10 connected to the inner circumferential surface of the yoke 20, and the coil 40 is attached to cover the outer circumferential surface of the insulator 50. If necessary, insulating paper (not shown) is placed in the slot 30 to cover all or part of the outer circumferential surface of the coil 40. The yoke 20 may be assembled by connecting multiple split yokes circumferentially. In this case, one or multiple teeth 10 are connected to one split yoke in advance, and then the multiple split yokes are connected circumferentially. Depending on the magnitude of the current flowing through the coil 40, the surfaces of the teeth 10 may be covered with insulating paper instead of attaching the insulators 50 to the teeth 10.

[0065] Next, the bus bar guide 70 is positioned relative to the lead portions 41 of the multiple coils 40 and installed on the upper surface of the yoke 20. As shown in the left diagram of Fig. 11A , two sub-bus bars 67A are fitted into grooves 71 provided on the innermost periphery of the bus bar guide 70. Furthermore, as shown in the right diagram of Fig. 11A , two sub-bus bars 67B are fitted into predetermined positions in the innermost groove 71 so that intermediate connection portions 67Ac and 67Bc overlap in the radial direction. At this time, the two sub-bus bars 67B are positioned so that intermediate connection portions 67Ac are positioned radially outward of intermediate connection portions 67Bc.

[0066] The terminal ends 67Ab, 67Bb are joined to the lead portion 41, and the intermediate connection portions 67Ac, 67Bc are joined to the lead portion 41 later. However, the terminal ends 67Ab, 67Bb and the lead portion 41, and the intermediate connection portions 67Ac, 67Bc and the lead portion 41 may also be joined once the two sub-bus bars 67B are attached to the bus bar guide 70.

[0067] Next, as shown in the left diagram of Fig. 11B , the first in-phase series connection bus bar 65A and the second in-phase series connection bus bar 66C are fitted into two predetermined grooves 71 in the bus bar guide 70. Furthermore, as shown in the center diagram of Fig. 11B , the first in-phase series connection bus bar 65B and the second in-phase series connection bus bar 66B are fitted into two other grooves 71 in the bus bar guide 70. Furthermore, as shown in the right diagram of Fig. 11B , the first in-phase series connection bus bar 65C and the second in-phase series connection bus bar 66A are fitted into two further other grooves 71 in the bus bar guide 70.

[0068] 11C, the busbar subassembly 69 is attached to the busbar guide 70. Unlike the first in-phase series-connected busbars 65A to 65C and the second in-phase series-connected busbars 66A to 66C, the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 have portions where they cross each other in the radial direction when attached to the busbar guide 70. For this reason, attaching the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 individually to the busbar guide 70 would complicate the assembly process. In view of this, the busbar subassembly 69 is assembled in advance using the method described above.

[0069] 6B and 11C , the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 are positioned relative to one another so that the external connection terminal portions 61c, 62c, and 63c are parallel to one another. In this state, a terminal mold portion 64 is formed by insert molding so that each of the external connection terminal portions 61c, 62c, and 63c is held in place. The assembly process is simplified by attaching the busbar subassembly 69 formed in this manner to a busbar guide 70. The U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63 in the busbar subassembly 69 are not in contact with one another and are electrically isolated.

[0070] 11A, 11B, and 11C, of ​​the various bus bars included in the bus bar subassembly 69, the bus bar located at the innermost periphery in the radial direction, i.e., the neutral bus bar 67, is attached first. Thereafter, the bus bars are attached sequentially in order moving radially outward. Finally, the bus bar subassembly 69 is attached to the bus bar guide 70.

[0071] After all the bus bars are attached to the bus bar guide 70, the terminal end of each bus bar is connected to the lead portion 41 of the opposing coil 40. This connection is made by Tungsten Inert Gas (TIG) welding. However, this is not a particular limitation. Other welding methods or methods other than welding may also be used.

[0072] As shown in Fig. 12A , the neutral point bus bar 67 is connected to the lead portion 41 at three locations: terminal ends 67Ab and 67Bb and intermediate connection portions 67Ac and 67Bc. As shown in Fig. 12B , when the neutral point bus bar 67 is attached to the bus bar guide 70, the terminal end 67Ab and the lead portion 41 have side surfaces parallel to the axial direction facing each other. TIG welding is performed with the two facing side surfaces abutting against each other to connect the terminal end 67Ab and the lead portion 41. The connection state shown in Fig. 12A is also the same between the terminal ends and the lead portion 41 of the other bus bars included in the bus bar assembly 60. In other words, TIG welding is performed with the side surfaces parallel to the axial direction abutting against each other to connect the terminal end and the lead portion 41.

[0073] 12C , when the neutral bus bar 67 is attached to the bus bar guide 70, the intermediate connection portion 67Bc and the lead portion 41 are arranged to sandwich the intermediate connection portion 67Ac in the radial direction. Therefore, when the intermediate connection portion 67Ac, the lead portion 41, and the intermediate connection portion 67Bc are connected by TIG welding, a higher power is required than when TIG welding the terminal end portion and the lead portion 41.

[0074] 4, 12B, and 12C, the terminal end portions and intermediate connection portions 67Ac and 67Bc of each bus bar included in the bus bar assembly 60 protrude upward along the axial direction, and their side surfaces parallel to the width direction are parallel to the axial direction. The base portions of each bus bar included in the bus bar assembly 60 are attached to the bus bar guide 70 so that their side surfaces parallel to the thickness direction are in contact with the bottom surfaces of the grooves 71. In other words, the base portions of each bus bar are attached to the bus bar guide 70 so that their side surfaces parallel to the thickness direction are parallel to the radial direction.

[0075] [Effects, etc.] As described above, the stator assembly 100 according to this embodiment includes a stator subassembly 80 and a busbar assembly 60. The stator subassembly 80 includes an annular yoke 20, a plurality of teeth 10 attached to the inner peripheral surface of the yoke 20 at intervals, and a plurality of coils 40 attached to each of the plurality of teeth 10. The coil 40 has lead portions 41 protruding in the axial direction from both ends thereof.

[0076] The busbar assembly 60 is made of wire having a rectangular cross section and has a U-phase lead wire 61, a V-phase lead wire 62, and a W-phase lead wire 63 that electrically connect an external power supply to the plurality of coils 40, i.e., a plurality of first busbars 61, 62, and 63. The busbar assembly 60 has a busbar guide 70 made of an insulating material and provided with a plurality of grooves 71 that hold the plurality of first busbars 61, 62, and 63. The plurality of grooves 71 provided in the busbar guide 70 are separated from one another.

[0077] The plurality of first bus bars 61, 62, 63 each have a first base portion 61a, 62a, 63a, a first end portion 61b, 62b, 63b, and an external connection terminal portion 61c, 62c, 63c.

[0078] In the first bus bar 61, the wire is bent multiple times to integrally form a first base portion 61 a, a first termination portion 61 b, and an external connection terminal portion 61 c. In the first bus bar 62, the wire is bent multiple times to integrally form a first base portion 62 a, a first termination portion 62 b, and an external connection terminal portion 62 c. In the first bus bar 63, the wire is bent multiple times to integrally form a first base portion 63 a, a first termination portion 63 b, and an external connection terminal portion 63 c.

[0079] Each of the first base portions 61 a , 62 a , and 63 a is fitted into the groove 71 so that the side surface parallel to the short side direction of the rectangle contacts the bottom surface of the groove 71 .

[0080] The first terminal portions 61b, 62b, and 63b are portions that are bent in the direction of the long sides of the rectangle near both ends of the first base portions 61a, 62a, and 63a, respectively, and thus protrude upward along the axial direction.

[0081] The external connection terminal portions 61c, 62c, and 63c are portions that protrude radially outward from the first base portions 61a, 62a, and 63a, respectively, by bending the first base portions 61a, 62a, and 63a radially outward at their middle portions and then further bending them radially inward.

[0082] The first base portions 61 a , 62 a , and 63 a are arranged in the bus bar guide 70 so as to be spaced apart from one another in the radial direction.

[0083] Each of the first terminal ends 61b, 62b, 63b and the corresponding lead portion 41 are connected with their axially parallel side surfaces abutting against each other.

[0084] By configuring the stator assembly 100 in this manner, it is possible to suppress a local increase in current density in the first bus bars 61, 62, 63. It is also possible to suppress an increase in the radial and axial sizes of the stator assembly 100. These will be described in further detail below.

[0085] Each set of coils 40 through which a common-mode current flows is formed by connecting two series-connected coils 40 in parallel. Therefore, in each of the first bus bars 61, 62, and 63, the common-mode current flowing through the external connection terminals 61c, 62c, and 63c is twice as large as that flowing through other portions, such as the first base portions 61a, 62a, and 63a. Meanwhile, by bending the wire material radially via the external connection wire, each of the external connection terminals 61c, 62c, and 63c has a structure in which two pieces of wire material are stacked on top of each other. In other words, the external connection terminals 61c, 62c, and 63c are twice as thick as the first base portions 61a, 62a, and 63a.

[0086] Therefore, even when three in-phase currents flow from an external power source to each of the first bus bars 61, 62, and 63 via external connection lines, the current density of each of the external connection terminal portions 61c, 62c, and 63c will be the same as the current density of each of the first base portions 61a, 62a, and 63a.

[0087] This makes it possible to suppress a local increase in current density in the first bus bars 61, 62, and 63. It also makes it possible to suppress a temperature increase during use of the motor that occurs in response to an increase in current density. As a result, it is possible to suppress a temperature increase in the yoke 20 and the coil 40 near the first bus bars 61, 62, and 63 and the external connection terminals 61 c, 62 c, and 63 c, and to suppress a decrease in performance of the motor 300.

[0088] Furthermore, each of the first terminal ends 61 b, 62 b, and 63 b is connected to the corresponding lead portion 41 with its axially parallel side surfaces abutting against each other, which prevents the bus bar, and therefore the stator assembly, from increasing in radial size.

[0089] Furthermore, the first base portions 61 a, 62 a, 63 a are arranged to be spaced apart from one another in the radial direction in the bus bar guide 70. This eliminates the need to arrange the bus bars through which currents of different phases flow to be spaced apart from one another in the axial direction as disclosed in Patent Documents 2 and 3, and can prevent the axial size of the stator assembly from increasing.

[0090] The first bus bars 61, 62, and 63 are formed by bending a rectangular wire multiple times using a forming machine, which improves the manufacturing yield of the first bus bars 61, 62, and 63 and reduces manufacturing costs compared to conventional press punching methods using dies.

[0091] The external connection terminal portions 61 c, 62 c, 63 c are provided with bolt insertion holes 61 d, 62 d, 63 d that penetrate in the axial direction, respectively. The external power source and the plurality of first bus bars 61, 62, 63 are electrically connected by fastening external connection wires connected to the external power source to the external connection terminal portions 61 c, 62 c, 63 c with bolts inserted in the bolt insertion holes 61 d, 62 d, 63 d, respectively.

[0092] In this way, the external power supply and the plurality of first bus bars 61, 62, 63 can be reliably electrically connected.

[0093] The folded portions 61c1, 62c1, and 63c1, which are the tip portions of the external connection terminal portions 61c, 62c, and 63c, respectively, are provided with gaps having a predetermined radius of curvature, which can alleviate stress at the folded portions 61c1, 62c1, and 63c1, thereby preventing breakage of the first bus bars 61, 62, and 63 during long-term use.

[0094] In this embodiment, the external power supply is a three-phase AC power supply, and the bus bar assembly 60 further includes a plurality of second bus bars 65A to 65C and 66A to 66C and a plurality of third bus bars 67.

[0095] Each of the plurality of second bus bars 65A to 65C and 66A to 66C is made of wire material having a rectangular cross section, similar to the first bus bars 61, 62, and 63. The plurality of second bus bars 65A to 65C and 66A to 66C connect in series coils through which currents of the same phase flow.

[0096] Each of the third bus bars 67 is made of a wire material having a rectangular cross section, similar to the first bus bars 61, 62, and 63. The third bus bars 67 form a neutral point of the stator assembly 100.

[0097] In this way, the three-phase AC power supply and the stator assembly 100 can be electrically connected more reliably by the bus bar assembly.

[0098] In this specification, each bus bar included in bus bar assembly 60 is formed by bending a wire rod having a rectangular cross section. In this case, the corners of the rectangle may be chamfered. For example, the corners of the rectangle may be C-chamfered or R-chamfered.

[0099] The plurality of second bus bars 65A to 65C and 66A to 66C have second base portions 65Aa, 65Ba, 65Ca, 66Aa, 66Ba, and 66Ca and second terminal portions 65Ab, 65Bb, 65Cb, 66Ab, 66Bb, and 66Cb, respectively.

[0100] The wire is bent multiple times to integrally form the second base portion 65Aa and the second terminal end portion 65Ab. Similarly, the second base portion 65Ba and the second terminal end portion 65Bb are integrally formed. Similarly, the second base portion 65Ca and the second terminal end portion 65Cb are integrally formed.

[0101] The wire is bent multiple times to integrally form the second base portion 66Aa and the second terminal end portion 66Ab. Similarly, the second base portion 66Ba and the second terminal end portion 66Bb are integrally formed. Similarly, the second base portion 66Ca and the second terminal end portion 66Cb are integrally formed.

[0102] Each of the second base portions 65Aa, 65Ba, 65Ca, 66Aa, 66Ba, and 66Ca is fitted into the groove 71 so that the side surface parallel to the short side direction contacts the bottom surface of the groove 71. The second terminal portions 65Ab, 65Bb, 65Cb, 66Ab, 66Bb, and 66Cb are portions that protrude upward along the axial direction by being bent in the long side direction near both ends of the second base portions 65Aa, 65Ba, 65Ca, 66Aa, 66Ba, and 66Ca, respectively.

[0103] The plurality of third bus bars 67 each have third base portions 67Aa, 67Ba, third terminal portions 67Ab, 67Bb, and intermediate connection portions 67Ac, 67Bbc.

[0104] Each of the third base portions 67Aa, 67Ba is fitted into the groove 71 so that the side surface parallel to the short side contacts the bottom surface of the groove 71. The third terminal portions 67Ab, 67Bb are portions of the third base portions 67Aa, 67Ba that are bent near one end in the long side direction and protrude upward along the axial direction. The intermediate connection portions 67Ac, 67Bbc are portions of the third base portions 67Aa, 67Ba that are bent near the other end in the long side direction and protrude upward along the axial direction.

[0105] By configuring the second bus bars 65A to 65C and 66A to 66C and the third bus bar 67 in this manner, it is possible to prevent the radial and axial sizes of the stator assembly 100 to which the three-phase AC power supply is connected from increasing.

[0106] Similar to the first bus bars 61, 62, 63, the second bus bars 65A to 65C and 66A to 66C and the third bus bars 67, 67 are formed by bending a rectangular wire multiple times using a forming machine. This improves the manufacturing yield of the second bus bars 65A to 65C and 66A to 66C and the third bus bars 67, 67 and reduces manufacturing costs compared to conventional press punching methods using dies.

[0107] The external connection terminal portions 61c, 62c, 63c provided on the plurality of first bus bars 61, 62, 63 respectively have different radial lengths. By doing so, for example, the connection portions between the external connection wires and the external connection terminal portions 61c, 62c, 63c can be arranged on the same straight line, and the external power supply can be connected to the stator assembly 100 without special alignment or the like. In this case, the radial lengths from the tips of the external connection terminal portions 61c, 62c, 63c provided on the plurality of first bus bars 61, 62, 63 respectively to the center of the bus bar guide 70 may be the same.

[0108] Bolt insertion holes 61d, 62d, 63d that axially penetrate the external connection terminal portions 61c, 62c, 63c are provided in the external connection terminal portions 61c, 62c, 63c, respectively. In this case, it is preferable that the radial lengths from the bolt insertion holes 61d, 62d, 63d provided in the plurality of first bus bars 61, 62, 63, respectively, to the center of the bus bar guide 70 are the same.

[0109] By doing so, the bolt insertion holes 61d, 62d, and 63d, which are the connection points with the external connection lines, can be arranged on the same straight line, and the external power source and the stator assembly 100 can be connected without any special alignment or the like.

[0110] With the exception of the groove 71 located at the innermost periphery, the radial position of each of the plurality of grooves 71 on the busbar guide 70 varies along the circumferential direction so that one end thereof approaches the innermost groove 71 in the radial direction. In particular, when the base of one busbar included in the busbar assembly 60 is fitted into the same continuous groove 71, the radial position of the groove 71 on the busbar guide 70 varies along the circumferential direction so that one end thereof is at the same radial position as the innermost groove 71.

[0111] In this way, the busbar can be reliably connected to two lead portions 41 of the coil 40 that are located at different radial positions. In particular, when multiple busbars are located at different radial positions, these busbars can be attached to the busbar guide 70 without interfering with each other during assembly of the stator assembly 100.

[0112] In the bus bar assembly 60, the second bus bars 65A to 65C and 66A to 66C are arranged radially outward from the third bus bars 67. The first bus bars 61, 62, 63 are arranged radially outward from the second bus bars 65A to 65C and 66A to 66C.

[0113] By arranging the bus bars included in the bus bar assembly 60 in this manner, each bus bar can be easily attached to the bus bar guide 70. Furthermore, because the third bus bar 67, which forms the neutral point of the stator assembly 100, is arranged at a distance from the first bus bars 61, 62, and 63, through which a large current flows, potential fluctuations at the neutral point can be suppressed, thereby ensuring stable operation of the motor 300.

[0114] The motor 300 includes a stator assembly 100 and a rotor assembly 200 that is provided at a predetermined radial distance from the stator assembly 100 .

[0115] According to this embodiment, it is possible to suppress a local increase in current density in the first bus bars 61, 62, and 63. This makes it possible to suppress a temperature increase in the yoke 20 and the coil 40, and ultimately to suppress a decrease in performance of the motor 300.

[0116] This also prevents the radial and axial sizes of stator assembly 100, and therefore motor 300, from increasing. Each bus bar included in bus bar assembly 60 is formed by bending a rectangular wire multiple times using a forming machine. This improves the manufacturing yield of each bus bar, and therefore the assembly yield of stator assembly 100, compared to conventional press punching methods using dies, and reduces the manufacturing cost of motor 300.

[0117] The method for assembling the stator assembly 100 according to this embodiment includes the following steps.

[0118] The first step is to provide the stator subassembly 80 .

[0119] In the second step, the bus bar guide 70 is positioned relative to the lead portions 41 of the multiple coils 40 and is installed on the upper surface of the yoke 20 .

[0120] In the third step, the third bus bar 67 is fitted into the groove 71 provided on the innermost periphery of the bus bar guide 70 .

[0121] In the fourth step, second bus bars 65A to 65C and 66A to 66C are fitted into a plurality of grooves 71 provided radially outside of innermost groove 71, respectively.

[0122] In the fifth step, the first bus bars 61 , 62 , and 63 are fitted into the plurality of grooves 71 provided on the outermost periphery of the bus bar guide 70 .

[0123] In a sixth step, first terminal ends 61b, 62b, 63b, second terminal ends 65Ab, 65Bb, 65Cb, 66Ab, 66Bb, 66Cb, and third terminal ends 67Ab, 67Bb of first bus bars 61, 62, 63, second bus bars 65A to 65C, 66A to 66C, and third bus bar 67 are connected to the corresponding lead portions 41. Intermediate connection portions 67Ac, 67Bc of third bus bar 67 are connected to lead portions 41.

[0124] In the fifth step, the multiple first bus bars 61, 62, 63 are fitted into multiple grooves 71 provided on the outermost periphery, with the external connection terminal portions 61c, 62c, 63c held and fixed to the terminal mold portion 64 and positioned relative to each other.

[0125] According to this embodiment, each bus bar can be easily attached to the bus bar guide 70. Furthermore, in this embodiment, the first bus bars 61, 62, 63, which have portions that intersect with each other in the radial direction, are held and fixed in advance by the terminal mold portion 64 to form a bus bar sub-assembly 69, and the bus bar sub-assembly 69 is attached to the bus bar guide. In this manner, the first bus bars 61, 62, 63 can be easily attached to the bus bar guide 70.

[0126] <Modification 1> Fig. 13A is a perspective view of a busbar subassembly 69 according to the embodiment. Fig. 13B is a perspective view of a busbar subassembly 69A according to Modification 1. For ease of explanation, in Fig. 13B and Fig. 14 shown below, the same parts as those in the embodiment are denoted by the same reference numerals, and detailed explanations thereof will be omitted.

[0127] 13A includes a terminal mold portion 64. The terminal mold portion 64 holds and fixes external connection terminal portions 61c, 62c, and 63c.

[0128] The busbar subassembly 69A of the first modified example shown in FIG. 13B differs from the busbar subassembly 69 of the embodiment in that, instead of the terminal mold portion 64, a terminal block 68 holds and fixes the external connection terminal portions 61c, 62c, and 63c.

[0129] The terminal block 68 is made of an insulating material. As shown in FIG. 13B , the terminal block 68 abuts against the underside of each of the external connection terminals 61c, 62c, and 63c to support them. Walls 68a protruding upward are provided between the external connection terminals 61c and 62c, and between the external connection terminals 62c and 63c, to protect the external connection terminals 61c, 62c, and 63c from contacting each other. In this modification, insert nuts (not shown) are press-fitted into holes in the terminal block 68, or the holes and insert nuts are molded simultaneously. External connection wires are fastened with bolts to connect the external connection terminals 61c, 62c, and 63c to the external connection wires, respectively.

[0130] The member that holds and fixes the external connection terminals 61c, 62c, and 63c may be the terminal mold 64 or the terminal block 68. The terminal mold 64 and the terminal block 68 may be collectively referred to as terminal holders 64, 68.

[0131] <Modification 2> FIG. 14 is a schematic diagram showing a state of connection between the U-phase lead wire 61 and the external connection wire 310 according to Modification 2. In FIG.

[0132] 14, the external connection wire 310 is inserted into a gap 61c2 provided in a folded portion 61c1 of the U-phase lead wire 61, and the two are connected together. In this manner, the U-phase of the external power supply and the U-phase lead wire 61 are electrically connected together.

[0133] When the radius of curvature of the gap 61c2 is R and the diameter of the cross section of the external connection line 310 is D, the relationship shown in formula (1) is satisfied.

[0134] R>D / 2 (1) In this way, the external connection wire 310 can be easily inserted into the gap 61c2, and the U-phase of the external power supply and the U-phase lead wire 61 can be reliably electrically connected.

[0135] In this case, the external connection wire 310 and the external connection terminal portion 61c of the U-phase lead wire 61 are joined by the above-mentioned TIG welding or the like.

[0136] 14, the external connection wire 310 is similarly inserted through the gaps 62c2, 63c2 of the folded-back portions 62c1, 63c1 of the external connection terminal portion 62c of the V-phase lead wire 62 and the external connection terminal portion 63c of the W-phase lead wire 63. Thereafter, the external connection terminal portions 62c, 63c are connected to the external connection wire 310 by TIG welding or the like.

[0137] This allows the external connection wires 310 to be easily inserted through the gaps, and also ensures reliable electrical connection between the V-phase and V-phase lead wires 62, and between the W-phase and W-phase lead wires 63 of the external power supply.

[0138] In this modification, it is preferable that the tips of the external connection terminal portions 61c, 62c, 63c provided on the plurality of first bus bars 61, 62, 63, i.e., the lengths along the radial direction from the folded portions 61c1, 62c1, 63c1 to the center of the bus bar guide 70, are different from one another. This allows the external connection wire 310 to be easily inserted through the gaps between the folded portions 61c1, 62c1, 63c1. Furthermore, the V-phase, W-phase, and V-phase of the external power supply can be reliably electrically connected to the U-phase lead wire 61, the V-phase lead wire 62, and the W-phase lead wire 63, respectively.

[0139] (Other Embodiments) In the present specification, the number of series connections of the coils 40 through which the same-phase current flows is set to two. However, this is not particularly limited. For example, the number of series connections may be two or more. The number of parallel connections of the coils 40 through which the same-phase current flows is set to two. However, this is not particularly limited. The number of parallel connections of the coils 40 may be m (m is an integer of 2 or more).

[0140] In this case, the multiple grooves 71 in the busbar guide 70 have (m+2) mutually separated portions along the radial direction. The groove 71 provided on the innermost circumference is the first circumference, and the groove 71 provided on the outermost circumference is the (m+2)th circumference. One of the two end portions of the ith in-row series-connected busbar (i is an integer, 1≦i≦m) is positioned at the same radial distance as the groove 71 on the first circumference, as viewed from the center of the busbar guide 70, and the other is positioned at the same distance as the groove 71 on the (i+1)th circumference. In other words, the radial position of the groove 71 located on the (i+1)th circumference on the busbar guide 70 changes along the circumferential direction so that one end of the groove 71 is positioned at the same position as the groove 71 on the first circumference.

[0141] The stator assembly of the present disclosure is useful because it can suppress a local increase in current density in the first bus bar and suppress an increase in radial and axial sizes.

[0142] 10 Teeth 20 Yoke 30 Slot 40, U1, U2, U3, U4, V1, V2, V3, V4, W1, W2, W3, W4 Coil 41 Lead portion 50 Insulator 60 Busbar assembly 61 U-phase lead wire (first busbar) 61a Base portion (first base portion) 61b End portion (first end portion) 61c External connection terminal portion 61c1 Folded portion 61c2 Gap 61d Bolt insertion hole 62 V-phase lead wire (first busbar) 62a Base portion (first base portion) 62b End portion (first end portion) 62c External connection terminal portion 62c1 Folded portion 62c2 Gap 62d Bolt insertion hole 63 W-phase lead wire (first busbar) 63a Base portion (first base portion) 63b Termination portion (first termination portion) 63c External connection terminal portion 63c1 Folded portion 63c2 Gap 63d Bolt insertion hole 64 Terminal mold portion (terminal holding portion) 65A First common-phase series connection bus bar (second bus bar) 65Aa Base portion (second base portion) 65Ab Termination portion (second termination portion) 65B First common-phase series connection bus bar (second bus bar) 65Ba Base portion (second base portion) 65Bb Termination portion (second termination portion) 65C First common-phase series connection bus bar (second bus bar) 65Ca Base portion (second base portion) 65Cb Termination portion (second termination portion) 66A Second common-phase series connection bus bar (second bus bar) 66Aa Base portion (second base portion) 66Ab Termination portion (second termination portion) 66B Second in-phase series connection bus bar (second bus bar) 66Ba Base portion (second base portion) 66Bb Termination portion (second termination portion) 66C Second in-phase series connection bus bar (second bus bar) 66Ca Base portion (second base portion) 66Cb Termination portion (second termination portion) 67 Neutral point bus bar (third bus bar) 67A Sub-bus bar 67Aa Base portion (third base portion) 67Ab Termination portion (third termination portion) 67Ac Intermediate connection portion 67B Sub-bus bar 67Ba Base portion (third base portion) 67Bb Termination portion (third termination portion) 67Bc Intermediate connection portion 68 Terminal block (terminal holding portion) 68a Wall portion 69, 69A Bus bar sub-assembly 70 Bus bar guide 71 Groove 80 Stator sub-assembly 100 Stator assembly 200 Rotor assembly210 Rotating shaft 220 Rotor core 230 Magnet 300 Motor 310 External connection line

Claims

1. A stator assembly for a motor, comprising: a stator subassembly; and a busbar assembly, wherein the stator subassembly comprises: an annular yoke; a plurality of teeth attached to the inner peripheral surface of the yoke at intervals; and a plurality of coils respectively attached to the plurality of teeth, wherein each of the plurality of coils has a lead portion protruding from each of both ends along the axial direction which is the axial direction of the rotating shaft of the motor, and the busbar assembly comprises: a plurality of first busbars which are wire rods with rectangular cross sections and which electrically connect an external power source to the plurality of coils, and a busbar guide made of an insulating material and which is provided with a plurality of grooves for holding each of the plurality of first busbars, wherein each of the plurality of first busbars has a first base portion, a first end portion, and an external connection terminal portion, and wherein the first base portion, the first end portion, and the external connection terminal portion are integrally formed by bending the wire rod multiple times, the first base is fitted into the groove so that the side parallel to the short side direction of the rectangle is in contact with the bottom surface of the groove; the first end portion is a portion that protrudes upward along the axial direction by being bent in the long side direction of the rectangle near both ends of the first base; the external connection terminal portion is a portion that protrudes radially outward from the first base by being bent outward at an intermediate portion in a radial direction that is the radial direction of the motor and then folded back radially inward; the multiple grooves provided in the bus bar guide are separated from one another; and the multiple first bases that each have on the multiple first bus bars are arranged at a distance from one another in the radial direction on the bus bar guide.

2. A stator assembly according to claim 1, wherein the first terminal end portion and the lead portion are connected with their side surfaces parallel to the axial direction abutting against each other.

3. A stator assembly as claimed in claim 1, wherein the external connection terminal section is provided with a bolt insertion hole that passes through the external connection terminal section in the axial direction, and an external connection line connected to the external power source and the external connection terminal section are fastened together with a bolt inserted into the bolt insertion hole.

4. A stator assembly as described in claim 1, wherein a gap having a predetermined radius of curvature is provided at the tip of the external connection terminal portion, and an external connection wire connected to the external power source is inserted into the gap to connect the external connection wire to the external connection terminal portion.

5. A stator assembly as claimed in claim 1, wherein the external connection terminals provided on the first bus bars are arranged parallel to each other at intervals, and the external connection terminals are held and fixed by a terminal holder.

6. A stator assembly according to claim 5, wherein the plurality of external connection terminal portions provided on the plurality of first bus bars respectively have different lengths along the radial direction.

7. A stator assembly as claimed in claim 5, wherein the lengths along the radial direction from the tips of the external connection terminal portions provided on each of the first bus bars to the centre of the bus bar guide are the same.

8. A stator assembly as claimed in claim 5, wherein a plurality of bolt insertion holes each passing through the external connection terminal portion in the axial direction are provided in each of the external connection terminal portions, and the lengths along the radial direction from the plurality of bolt insertion holes provided in each of the plurality of first bus bars to the centre of the bus bar guide are all the same.

9. A stator assembly as claimed in claim 1, wherein the external power supply is a three-phase AC power supply, and the bus bar assembly further comprises: a plurality of second bus bars made of the wire rod having the rectangular cross section and connecting in series the coils through which currents of the same phase flow; and a plurality of third bus bars made of the wire rod having the rectangular cross section and constituting a neutral point of the stator assembly.

10. A stator assembly according to claim 9, wherein each of the plurality of second bus bars has a second base portion and a second terminal portion, and the second base portion and the second terminal portion are integrally formed by bending the wire rod multiple times, and the second base portion is fitted into the groove so that the side surface parallel to the short side direction contacts the bottom surface of the groove, and the second terminal portion is a portion that protrudes upward along the axial direction by being bent in the long side direction near both ends of the second base, and each of the plurality of third bus bars has a third base portion, a third terminal portion, and an intermediate connection portion, and the third base portion is fitted into the groove so that the side surface parallel to the short side direction contacts the bottom surface of the groove, and the third terminal portion is a portion that protrudes upward along the axial direction by being bent in the long side direction near one end of the third base, The intermediate connection portion is a portion that is bent in the long side direction near the other end of the third base portion and thereby protrudes upward along the axial direction.

11. A stator assembly as claimed in claim 10, wherein the radial position of each of the plurality of grooves, excluding the groove at the innermost periphery, in the bus bar guide varies along the circumferential direction, which is the outer periphery of the motor, so that one end of each of the plurality of grooves approaches the groove at the innermost periphery in the radial direction.

12. A stator assembly as claimed in claim 11, wherein when the base of one bus bar included in said bus bar assembly is fitted into the same continuous groove, the radial position of said groove in said bus bar guide changes along the circumferential direction so that said one end of said groove is at the same radial position as said innermost groove.

13. A stator assembly according to claim 10, wherein the second bus bars are arranged radially outward from each of the third bus bars, and the first bus bars are arranged radially outward from each of the second bus bars.

14. A motor comprising: a stator assembly according to any one of claims 1 to 13; and a rotor assembly provided at a predetermined radial distance from said stator assembly.

15. A method for assembling a stator assembly as recited in claim 10, comprising the steps of: preparing the stator sub-assembly; positioning the lead portions of each of the plurality of coils and installing the bus bar guide on the upper surface of the yoke; fitting the third bus bar into the groove provided on the innermost periphery of the bus bar guide; fitting the second bus bar into each of the plurality of grooves provided radially outward of the groove on the innermost periphery; fitting the first bus bar into each of the plurality of grooves provided on the outermost periphery of the bus bar guide; and connecting the first to third terminal ends of the first to third bus bars and the intermediate connection portion of the third bus bar to the lead portions, respectively;

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