Electric motor

Abstract

Provided is an electric motor in which the filling amount of an adhesive for fixing a portion in the vicinity of a wire end section of a coil can be reduced and assembly work time can be shortened.　The electric motor includes a stator and a rotor. A plurality of coils 33 of the stator are wound around respective teeth of a stator core 34. A bus bar unit is disposed on one end side of the stator core in the axial direction. The bus bar unit has a plurality of bus bar terminals 51Ub, 51Vb, 51Wb disposed so as to straddle winding sections of the respective coils adjacent to each other in the circumferential direction. The bus bar terminals are each provided with a wire start connection part 54s to which a wire start section 33s of one of the adjacent coils is connected and a wire end connection part 54e to which a wire end section 33e of the other adjacent coil is connected. A filling opening 65 for filling the winding section of the coil in the vicinity of the wire end section with an adhesive is provided between the wire start connection part and the wire end connection part of each bus bar terminal.

Description

electric motor

[0001] The present invention relates to an electric motor used as a drive source for a vehicle, etc.

[0002] A known electric motor used as a drive source for a vehicle, etc., is equipped with an annular stator and a rotor arranged radially inside the stator, with multiple coils wound around the stator to generate a rotating magnetic field (see, for example, Patent Document 1).

[0003] The electric motor described in Patent Document 1 includes an annular stator fixed within a housing and a rotor rotatably disposed radially inside the stator. The stator includes a stator core made of a magnetic material, an insulator attached to the stator core, multiple coils wound around the stator core via the insulator, and a busbar unit for supplying drive current to each coil. The rotor includes a rotor core made of a magnetic material and multiple permanent magnets provided in the rotor core. The busbar unit is disposed on one axial end of the stator core.

[0004] The stator core of the stator has multiple teeth protruding radially inward from multiple circumferential positions, and insulators are attached to the multiple teeth. Each coil is wound around the multiple teeth via the insulators. The busbar unit has U-phase, V-phase, and W-phase busbars, which are held by an insulating resin block. Each busbar includes a substantially C-shaped busbar body and multiple busbar terminals protruding radially outward from the busbar body. Each busbar terminal is arranged to straddle the winding portions of adjacent coils in the axial direction. Each busbar terminal is connected to the start wire portion of one circumferentially adjacent coil and the end wire portion of the other circumferentially adjacent coil. Furthermore, the busbar body of each busbar is configured to receive U-phase, V-phase, and W-phase drive currents from a power supply terminal.

[0005] Japanese Patent Application Laid-Open No. 2021-164260

[0006] The coil wound around each tooth has a starting wire portion where the winding begins and a finishing wire portion where the winding ends. The starting wire portion is located inside the winding portion of the coil (inner layer side), and the finishing wire portion is located outside the winding portion of the coil (outer layer side). The area near the starting wire portion of the coil is constrained in position by the coil of the winding portion stacked on top, but the area near the finishing wire portion of the coil is not constrained in position by the coil of the winding portion. For this reason, the area near the finishing wire portion of the coil is separately fixed to the winding portion of the coil using adhesive.

[0007] In the electric motor described above, a busbar unit is attached to the axial end of a stator (insulator) around which coils are wound, and multiple busbar terminals of the busbar unit are arranged to cover the gaps between adjacent coils from the axial outside. Therefore, the base sides of the start and end wires of each coil (the sides closest to the coil windings) are covered on the axial outside by the busbar terminals. Therefore, when fixing the coil end wires to the coil windings using adhesive as described above, a large amount of adhesive must be poured from a position spaced from the base of the end wire so that it spreads all the way to the base of the end wire. This requires a large amount of adhesive to be filled, and it takes a long time for the adhesive to harden, which increases the assembly time of the electric motor.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electric motor that can reduce the amount of adhesive used to fix the vicinity of the end of the coil and shorten the assembly time.

[0009] an electric motor according to one aspect of the present invention includes an annular stator; and a rotor disposed radially inside the stator and rotating relative to the stator; the stator includes a stator core having a plurality of teeth protruding radially inward from a plurality of circumferential positions, a plurality of coils wound around each of the teeth, and a busbar unit disposed at one axial end of the stator core and supplying power to each of the coils wound around the teeth; the busbar unit has a plurality of busbar terminals disposed so as to straddle the winding portions of each of the circumferentially adjacent coils when viewed in the axial direction, and each of the busbar terminals is provided at two circumferentially spaced positions with a start wire connection portion to which a start wire portion of one of the adjacent coils is connected and an end wire connection portion to which an end wire portion of the other circumferentially adjacent coil is connected, and a filling opening is provided between the start wire connection portion and the end wire connection portion of each of the busbar terminals for filling an adhesive with the winding portion of the coil near the end wire portion.

[0010] When manufacturing the electric motor of this aspect, if the end wire portions of the coil wound around each tooth are to be connected to the end wire connection portions of the busbar terminals, the following work is performed as a pre-process for the connection. Specifically, adhesive is filled into the winding portion near the end wire portion of the coil through a fill opening provided between the start wire connection portion and the end wire connection portion of each busbar terminal. When the filled adhesive hardens, the vicinity of the end wire portion of the coil is fixed to the winding portion of the coil, preventing the end wire portion of the coil from coming apart from the winding portion. This makes it possible to easily and stably connect the end wire portion of the coil to the corresponding end wire connection portion of the busbar terminal. In the electric motor of this aspect, when bonding the vicinity of the end wire portion of the coil to the winding portion, adhesive can be filled directly into the vicinity of the end wire portion of the coil through the fill opening of the busbar terminal. This prevents the adhesive from flowing into unnecessary areas other than the vicinity of the end wire portion. As a result, it is possible to reduce the amount of adhesive filled and shorten the adhesive hardening time, thereby shortening the assembly time.

[0011] The filling opening may be arranged at a position closer to a base of the end wire portion of one of the adjacent coils than to a base of the start wire portion of the other adjacent coil.

[0012] In this case, since the filling opening is positioned closer to the base of the end wire portion of one coil than to the base of the start wire portion of the other coil, the winding portion of the coil near the end wire portion can be easily and accurately filled through the filling opening.

[0013] The filling opening may be formed at a position closer to the end wire connecting portion than to the start wire connecting portion of the bus bar terminal.

[0014] In this case, since the filling opening is formed at a position closer to the end wire connection portion than to the start wire connection portion of each bus bar terminal, it is possible to position each bus bar terminal at a midpoint between the winding portions of two circumferentially adjacent coils, while shifting only the filling opening toward the base of the start wire portion of one of the coils.

[0015] The busbar unit may include three busbars for U-phase, V-phase, and W-phase, and an insulating resin block that holds the three busbars spaced apart from one another, and each busbar may include a substantially C-shaped busbar body embedded in the resin block, and the busbar terminals protruding radially outward from the busbar body.

[0016] In this case, by positioning and fixing the busbar unit to one end of the stator core in the axial direction, the filling openings of all the busbar terminals can be positioned to facilitate the adhesive filling operation. Therefore, adopting this configuration simplifies the manufacture of electric motors.

[0017] In the electric motor according to the present invention, adhesive can be directly filled near the end wire portions of the coils through the filling openings of the bus bar terminals, which reduces the amount of adhesive that needs to be filled to fix the areas near the end wire portions of the coils and shortens the assembly time.

[0018] 8 is a side view of an electric motor according to an embodiment. 9 is a plan view of an electric motor according to an embodiment with some components removed. 10 is a cross-sectional view taken along line III-III in FIG. 2. 11 is a cross-sectional view taken along line IV-IV in FIG. 2. 12 is a perspective view of an electric motor according to an embodiment with some components removed. 13 is a perspective view of a busbar unit according to an embodiment as seen from one axial side. 14 is a perspective view of a busbar unit according to an embodiment as seen from the other axial side. 15 is a plan view of a stator according to an embodiment. 16 is an enlarged view of a portion IX in FIG. 10. 17 is a side view of an example of an electric motorcycle equipped with an electric motor according to an embodiment. 18 is a side view of another example of an electric motorcycle equipped with an electric motor according to an embodiment.

[0019] An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a side view of an electric motor 1 according to this embodiment, and FIG. 2 is a plan view of the electric motor 1 with some components removed. FIG. 3 is a cross-sectional view of the electric motor 1 taken along line III-III in FIG. 2. The electric motor 1 according to this embodiment shown in these figures is used, for example, as a drive source for an electric motorcycle. When used as a drive source for an electric motorcycle, the electric motor 1 can be disposed, for example, on the side of the rear wheel Wr, which is the drive wheel, as shown in FIG. 10. In this case, the power of the electric motor 1 is transmitted to the rear wheel Wr via a gear mechanism (not shown). Note that the location of the electric motor 1 is not limited to this; the electric motor 1 can also be mounted on the vehicle frame between the front wheel Wf and the rear wheel Wr, as shown in FIG. 11. In this case, the power of the electric motor 1 is transmitted to the rear wheel Wr via a chain 2 or a belt.

[0020] The electric motor 1 includes an annular stator 10 and a rotor 11 rotatably disposed radially inside the stator 10. A small gap (air gap) is provided between the outer peripheral surface of the rotor 11 and the stator 10. The rotor 11 has a rotating shaft 12 at its axial position. Hereinafter, unless otherwise specified, the direction along the axis o of the rotating shaft 12 will be referred to as the "axial direction," the direction perpendicular to the axis o will be referred to as the "radial direction," and the circumferential direction around the axis o will be referred to as the "circumferential direction." Arrow A indicating the axial direction, arrow R indicating the radial direction, and arrow C indicating the circumferential direction are shown in appropriate locations in the drawings.

[0021] The stator 10 and the main part of the rotor 11 inside it are housed inside a housing 13. The housing 13 includes a substantially cylindrical case body 14, a rear cover 15 that closes one axial end of the case body 14, and a front cover 16 that closes the other axial end of the case body 14. The rear cover 15 and the front cover 16 are fixed to the case body 14 by bolting or the like. In the following description, the side of the case body 14 on which the front cover 16 is located will be referred to as the "front side," and the side on which the rear cover 15 is located will be referred to as the "rear side." Note that an arrow FR pointing to the front side is shown in the appropriate places in the drawings.

[0022] Fig. 4 is a cross-sectional view of the electric motor 1 taken along line IV-IV in Fig. 2, and Fig. 5 is a perspective view of the electric motor 1 with some components such as the rear cover 15 removed. As shown in Figs. 2 to 5, the stator 10 is formed in a generally cylindrical shape by connecting a plurality of split cores 30 of the same shape in an annular shape. In this embodiment, the stator 10 is formed by connecting a total of 12 split cores 30. Note that in Fig. 2, only two of the 12 split cores 30 are shown in detail by dotted lines. Each split core 30 includes a core portion 31, an insulator 32, and a coil 33.

[0023] The core portion 31 is formed by stacking multiple steel plates (magnetic materials) in an approximately T-shape in the axial direction. The core portion 31 includes core back segments 31a each having an arc-shaped configuration in the axial direction, and teeth 31b protruding radially inward from approximately the circumferential center of the core back segment 31a. The approximately T-shape is formed by these core back segments 31a and teeth 31b. The core portions 31 of the multiple split cores 30 form an annular stator core 34 by connecting both circumferential ends of the core back segments 31a to the ends of adjacent core back segments 31a. In this state, each tooth 31b protrudes radially toward the axis o.

[0024] The insulators 32 are made of an insulating resin material. The insulators 32 are attached to the outer peripheral surfaces of the teeth 31b of the corresponding core portion 31. The teeth 31b, which protrude radially inward from the core back segments 31a of the core portion 31, have a substantially rectangular cross section perpendicular to the radial direction. The insulators 32 cover two axial faces of the substantially rectangular cross section of the teeth 31b and two axial faces at one end and the other end. In other words, the insulators 32 cover the periphery of the substantially rectangular cross section of the corresponding tooth 31b. Each insulator 32 is composed of two divided blocks 32b divided in the axial direction. Only the rear divided block 32b is shown in FIG. 4.

[0025] As shown in FIG. 4 , the insulator 32 includes a rectangular cylindrical surrounding portion 35 surrounding the outer circumferential surface of the corresponding tooth 31 b, an outer flange portion 36 o extending outward (circumferentially and axially) from the radially outer end (toward the core-back segment 31 a) of the surrounding portion 35, and an inner flange portion 36 i extending outward (circumferentially and axially) from the radially inner end of the surrounding portion 35. A corresponding coil 33 is wound around the outer circumferential surface of the surrounding portion 35. Each coil 33 is wound around the outer circumferential surface of the surrounding portion 35 while being radially positioned and restricted by the inner flange portion 36 i and the outer flange portion 36 o. Each coil 33 is wound around the outer periphery of the corresponding tooth 31 b via the surrounding portion 35 of the insulator 32. In this embodiment, each coil 33 is made of a rectangular wire having a substantially rectangular cross section.

[0026] 2, 4, and 5, a protruding piece 37 that protrudes radially inward is provided on the rear axial end of the inner flange portion 36i of the rear divided block 32b of each insulator 32. The protruding piece 37 is a block that is generally rectangular in axial view, and a recessed portion 38 that is generally rectangular in axial view is formed on the surface facing the rear in the axial direction. The recessed portion 38 is open toward the rear in the axial direction.

[0027] As shown in FIGS. 4 and 5 , a thermistor housing 40 bulging radially outward in a rectangular shape is provided at the approximate circumferential center of the outer flange portion 36o of the rear split block 32b of each insulator 32. The thermistor housing 40 is located axially outward (toward the rear) of the rear end face of the stator core 34 on the outer flange portion 36o of the rear split block 32b. A thermistor 41 for detecting the temperature of the coil 33 is attached to the thermistor housing 40 of one of the insulators 32. A notch (not shown) is provided in the radially inner inner wall of the thermistor housing 40 so that the temperature detection portion of the thermistor 41 housed in the thermistor housing 40 abuts against the outer surface of the coil 33. Reference numeral 42 in FIGS. 4 and 5 denotes a leaf spring material for pressing the thermistor 41 against the outer surface of the coil 33.

[0028] As shown in FIG. 5 , a pair of coil fitting grooves 43s, 43e opening toward the rear are formed on the rear edge of the outer flange portion 36o of each divided block 32b. These coil fitting grooves 43s, 43e are provided on both circumferential sides of the thermistor housing portion 40. Each coil fitting groove 43s, 43e penetrates the outer flange portion 36o in the thickness direction. A start portion 33s of the coil 33 wound around the corresponding tooth 31b via the insulator 32 is fitted and temporarily locked in one of the coil fitting grooves 43s. An end portion 33e of the coil 33 wound around the corresponding tooth 31b via the insulator 32 is fitted and temporarily locked in the other coil fitting groove 43e. The start portion 33s and end portion 33e of the coil 33 fitted in the coil fitting grooves 43s, 43e are pulled out radially from the outer flange portion 36o. The starting wire portion 33s and the ending wire portion 33e of the coil 33 drawn out radially outward from the outer flange portion 36o are connected to the bus bars 51U, 51V, and 51W described later after the multiple divided blocks 32b are assembled in a ring shape.

[0029] As shown in FIG. 3 , the rotor 11, which is disposed radially inside the stator 10, includes a rotor body 20 formed into a generally cylindrical shape by stacking multiple steel plates (magnetic materials) in the axial direction. A rotating shaft 12 is press-fitted and fixed to the center of rotation (axial center) of the rotor body 20. Multiple, generally plate-shaped permanent magnets 21 are embedded inside the rotor body 20. The multiple permanent magnets 21 are arranged in the circumferential direction of the rotor body 20 so that their north and south poles alternately face radially outward. The rotor 11 of this embodiment employs a so-called "IPM (Interior Permanent Magnet) structure" in which multiple permanent magnets are embedded inside the rotor body 20, but the structure of the rotor 11 is not limited thereto. The rotor 11 may also employ a so-called "SPN (Surface Permanent Magnet) structure" in which the permanent magnets 21 are attached to the outer surface of the rotor body 20.

[0030] The rotating shaft 12 protrudes from one axial end (rear end) and the other axial end (front end) relative to the rotor body 20. One axial end of the rotating shaft 12 is rotatably supported by the rear cover 15 via a bearing 22R. The other axial end of the rotating shaft 12 passes through the front cover 16 and is rotatably supported by the front cover 16 via a bearing 22F. The end of the rotating shaft 12 passing through the front cover 16 forms a rotation output portion 12o to which an output gear or sprocket is attached. The rotation output portion 12o protrudes axially outward from the housing 13 of the electric motor 1, and when attached to the body of a motorcycle, protrudes outward in the width direction of the body, as shown in Figures 10 and 11 .

[0031] A recessed portion 23 that opens toward the rear side is formed in the rear surface of the rear cover 15. One end of the rotating shaft 12 penetrates the rear cover 15 in the thickness direction so that a rear end surface 12e is exposed in the recessed portion 23. A substantially disk-shaped sensor magnet 24 is fixed to the end surface 12e of the rotating shaft 12. The sensor magnet 24 serves as a detection target for detecting the rotation state when a rotation sensor 25 (described later) detects the rotation state of the rotor 11 (rotating shaft 12).

[0032] As shown in Figure 3, a plurality of support pillars 27 protrude from the recessed portion 23 of the rear cover 15 so as to surround the through-hole 26 of the rear cover 15. A sensor unit 45 is fixed to the tip portions of these support pillars 27. The sensor unit 45 includes a rotation sensor 25 made of a magnetoresistive element and a sensor board 46 on which the rotation sensor 25 is mounted. The sensor board 46 is fixed to the support pillars 27 so that the rotation sensor 25 faces the sensor magnet 24 on the end face 12e of the rotating shaft 12 with a small gap between them.

[0033] 2, the circuit on the sensor board 46 is electrically connected to a sensor connector 47 installed in the housing 13 via a sensor harness 48. A terminal portion of the sensor connector 47 is connected to a controller (not shown) via wiring (not shown). Note that the recessed portion 23 of the rear cover 15, in which the sensor unit 45 is attached as described above, is closed by a lid member 49 (shown in FIGS. 1 and 3).

[0034] 2 to 4, a substantially annular busbar unit 50 is attached to the rear end of the insulator 32. The busbar unit 50 includes busbars 51U, 51V, and 51W for supplying drive current to the coils 33 wound around each of the teeth 31b of the stator core 34. The busbar unit 50, together with the stator core 34 having the teeth 31b and the coils 33 wound around each of the teeth 31b, constitutes the stator 10.

[0035] A drive connector 52 is attached to the case body 14 of the housing 13. The drive connector 52 is attached to the case body 14 by penetrating the peripheral wall of the case body 14 near the rear side. As shown in FIG. 2 , the drive connector 52 is provided with a U-phase power terminal TU, a V-phase power terminal TV, and a W-phase power terminal TW. These power terminals TU, TV, and TW penetrate the peripheral wall of the case body 14, and their inner ends are electrically connected to bus bars 51U, 51V, and 51W, respectively. Furthermore, the outer ends of the power terminals TU, TV, and TW on the case body 14 are connected to a drive circuit of a controller (not shown). A drive current is supplied to the coils 33 wound around each tooth 31b of the stator 10 from the drive circuit via the power terminals TU, TV, and TW and the bus bars 51U, 51V, and 51W.

[0036] FIG. 6 is a perspective view of the busbar unit 50 as viewed from the rear side, and FIG. 7 is a perspective view of the busbar unit 50 as viewed from the front side. The busbar unit 50 includes busbar bodies 51Ua, 51Va, and 51W (see FIGS. 3 and 4 ) of three busbars 51U, 51V, and 51W embedded in an annular resin block 53 made of insulating resin material and spaced apart in the axial direction. Each busbar body 51Ua, 51V, and 51Wa is formed of a conductive metal plate that is substantially C-shaped in the axial direction. The annular resin block 53 is fixed to the rear end of each insulator 32 of the annularly assembled split core 30. In this state, the resin block 53 is positioned concentrically with the stator core 34. The specific manner in which the resin block 53 is fixed to the insulator 32 will be described in detail later.

[0037] Four busbar terminals 51Ub, 51Vb, 51Wb protruding radially outward are provided on the outer peripheral edge of each of the substantially C-shaped busbar bodies 51Ua, 51Va, 51Wa. The four busbar terminals 51Ub, 51Vb, 51Wb for the U-phase, V-phase, and W-phase are arranged at equal intervals in the circumferential direction of the resin block 53. Each busbar terminal 51Ub, 51Vb, 51Wb is formed integrally with the corresponding busbar body 51Ua, 51Va, 51Wa from a conductive metal plate.

[0038] Three of the four U-phase busbar terminals 51Ub are formed in a generally rectangular shape having a constant width along the circumferential direction of the resin block 53. The remaining one of the four U-phase busbar terminals 51Ub has a generally rectangular terminal base 51Ub1 having a constant width along the circumferential direction of the resin block 53, and a terminal connection portion 51Ub2 that bulges outward in a mountain-like shape in the radial direction, connected to the terminal base 51Ub1. Similarly, three of the four V-phase and W-phase busbar terminals 51Vb, 51Wb have a generally rectangular shape having a constant width along the circumferential direction of the resin block 53, and the remaining one of the four V-phase and W-phase busbar terminals 51Vb, 51Wb has a generally rectangular terminal base 51Vb1, 51Wb1 having a constant width along the circumferential direction of the resin block 53, and a terminal connection portion 51Vb2, 51Wb2 that bulges outward in a mountain-like shape in the radial direction, connected to the terminal base 51Vb1, 51Wb1. The terminal base portions 51Ub1, 51Vb1, 51Wb1 of the bus bar terminals 51Ub, 51Vb, 51Wb having the terminal connection portions 51Ub2, 51Vb2, 51Wb2 are shaped substantially the same as the other bus bar terminals 51Ub, 51Vb, 51Wb.

[0039] A V-phase busbar terminal 51Vb is arranged on one circumferential side of each U-phase busbar terminal 51Ub, a W-phase busbar terminal 51Wb is arranged on one circumferential side of each V-phase busbar terminal 51Vb, and a U-phase busbar terminal 51Ub is arranged on one circumferential side of each W-phase busbar terminal 51Wb. Adjacent U-phase busbar terminal 51Ub, V-phase busbar terminal 51Vb, and W-phase busbar terminal 51Wb are spaced apart at equal intervals in the circumferential direction of resin block 53. Busbar terminals 51Ub, 51Vb, and 51Wb of each phase, each having terminal connection portions 51Ub2, 51Vb2, and 51Wb2, are arranged collectively in a specific circumferential region of resin block 53. Terminal connection portions 51Ub2, 51Vb2, 51Wb2 of these bus bar terminals 51Ub, 51Vb, 51Wb are electrically connected to the corresponding power supply terminals TU, TV, TW of the drive connector 52 (see FIG. 2).

[0040] As shown in Figures 6 and 7, each busbar terminal 51Ub, 51Ub, 51Ub for the U-phase, V-phase, and W-phase is provided with a start wire connection portion 54s and a finish wire connection portion 54e for connecting the start wire portion 33s and the finish wire portion 33e (see Figure 5) of the coil 33 wound around each tooth 31b of the stator core 34, respectively. The start wire connection portion 54s is provided near one circumferential side of the radially outer edge of each busbar terminal 51Ub, 51Ub, 51Ub. The finish wire connection portion 54e is provided near the other circumferential side of the radially outer edge of each busbar terminal 51Ub, 51Ub, 51Ub. Each of the start wire connection portion 54s and the finish wire connection portion 54e is configured to include an engagement groove 28 and a cut-and-raised piece 29.

[0041] The engagement grooves 28 extend radially inward from the radially outer ends of the bus bar terminals 51Ub, 51Ub, 51Ub, and the raised pieces 29 are cut and raised from the bottom of the engagement grooves 28 toward the rear side. The starting wire portions 33s and ending wire portions 33e of the coils 33 drawn out from the coil fitting grooves 43s, 43e of the insulator 32 described above are inserted into and engaged with the engagement grooves 28. The starting wire portions 33s and ending wire portions 33e inserted into the engagement grooves 28 are drawn out axially toward the rear side. In this state, the starting wire portions 33s and ending wire portions 33e are welded and fixed to the corresponding raised pieces 29. The starting wire portions 33s and ending wire portions 33e of each coil 33 wound around the teeth 31b are thus connected to the starting wire connecting portions 54s and ending wire connecting portions 54e of the corresponding bus bar terminals 51Ub, 51Ub, 51Ub.

[0042] Here, each busbar terminal 51Ub, 51Ub, 51Ub protruding radially from the annular resin block 53 is disposed, in the axial view, at approximately the midpoint between the axial centers of the winding portions (teeth 31b) of two circumferentially adjacent coils 33. In other words, each busbar terminal 51Ub, 51Ub, 51Ub is disposed, in the axial view, so as to straddle the winding portions (teeth 31b) of two circumferentially adjacent coils 33. The start wire connection portion 54s of each busbar terminal 51Ub, 51Ub, 51Ub is connected to the start wire portion 33s of one circumferentially adjacent coil 33 winding portion, in the axial view, and the end wire connection portion 54e is connected to the end wire portion 33e of the other circumferentially adjacent coil 33 winding portion, in the axial view.

[0043] 4, 6, and 7, the resin block 53 of the busbar unit 50 includes an annular block main body 55 in which the substantially C-shaped busbar main bodies 51Ua, 51Va, and 51Wa are embedded and spaced apart in the axial direction, and a relatively thin inner flange 56 that extends radially inward from the inner periphery of the block main body 55. The inner flange 56 is formed in an annular shape and protrudes radially inward from a position closer to the front in the thickness direction (axial direction) of the block main body 55. A step 57r is provided between the block main body 55 and a base (radially outer end) of the rear-side surface of the inner flange 56.

[0044] 6, twelve reinforcing ribs 58 are provided at equal intervals in the circumferential direction on the rear side surface of the inner flange portion 56 of the resin block 53. Each reinforcing rib 58 bulges rearward from the rear side surface of the inner flange portion 56 by a predetermined thickness and extends radially inward from a step portion 57r between the block main body portion 55 and the inner flange portion 56. This increases the radial bending rigidity of the portion of the inner flange portion 56 where the reinforcing ribs 58 are located.

[0045] Each reinforcing rib 58 is disposed at a circumferential position corresponding to the midpoint between adjacent bus bar terminals 51Ub, 51Vb, 51Wb in the circumferential direction. An adhesive filling port 59 that penetrates vertically through the resin block 53 is formed at approximately the center of each reinforcing rib 58 in the extension direction (radial direction). Details of the adhesive filling port 59 will be described later.

[0046] As shown in Figures 4 and 7, a ring-shaped protrusion 60 is provided on the front side surface of the block main body 55 of the resin block 53. The protrusion 60 is provided along the inner peripheral edge of the block main body 55. Twelve locking projections 61 are provided on the front end surface of the protrusion 60, spaced at equal intervals in the circumferential direction. The front end surface of the protrusion 60 is capable of abutting against the rear end surface of the outer flange portion 36o (see Figures 4 and 5) of each insulator 32 of the stator 10.

[0047] Furthermore, an engagement recess 44 (see FIG. 5 ) that opens toward the rear side is formed between the outer flange portions 36o of each circumferentially adjacent insulators 32. A plurality of locking protrusions 61 protruding from the ridge portion 60 of the resin block 53 are capable of fitting into the engagement recesses 44 between the insulators 32. The resin block 53 (busbar unit 50) is positioned in the circumferential direction with respect to the stator core 34 by fitting the plurality of locking protrusions 61 into the engagement recesses 44 between the insulators 32. Note that, when the plurality of locking protrusions 61 are fitted into the engagement recesses 44 between the insulators 32, the inner flange portion 56 and the reinforcing rib 58 of the resin block 53 bulge radially inward beyond the tips of the teeth 31b of the stator 10.

[0048] As shown in FIGS. 4 and 7 , twelve rectangular pillar-shaped bosses 62 are circumferentially spaced apart from one another on the front side surface of the inner flange portion 56 of the resin block 53 and protrude toward the front. Each boss 62 is positioned so as to axially overlap a reinforcing rib 58 on the rear side surface of the inner flange portion 56. Each boss 62 is positioned at a circumferential position corresponding to the midpoint between adjacent bus bar terminals 51Ub, 51Vb, and 51Wb. Each boss 62 has a distal end that protrudes axially to face a corresponding protruding piece 37 protruding from the rear side of each of the insulators 32. The distal end of each boss 62 is inserted into a recess 38 (see FIGS. 4 and 5 ) formed in the protruding piece 37 of the insulator 32. The recess 38 of the protruding piece 37 is formed to have a volume sufficiently larger than the distal end of the boss 62 to be inserted. The gap between the recess 38 and the boss 62 serves as a filling portion to be filled with adhesive 63 (see FIG. 4). Each boss 62 inserted into the recess 38 of the protruding piece 37 is fixed to the corresponding protruding piece 37 by the adhesive 63 (see FIG. 4) filled in the recess 38.

[0049] Each boss 62 of the resin block 53 is formed to be continuous with the adhesive filling port 59 provided in the reinforcing rib 58 of the inner flange 56. The adhesive filling port 59 is formed to reach the front end face of each boss 62. The adhesive filling port 59 is funnel-shaped so that the opening area gradually narrows from the rear end face of the reinforcing rib 58 toward the front end face of the boss 62. With the corresponding boss 62 on the resin block 53 inserted, the recess 38 of the protruding piece 37 on the insulator 32 is filled with adhesive 63 from the rear side of the resin block 53 through the adhesive filling port 59. When the adhesive 63 filled in the recess 38 in this manner hardens, the resin block 53 of the busbar unit 50 is fixed to the rear end of the insulator 32.

[0050] When the resin block 53 of the busbar unit 50 is fixed to the rear end of the insulator 32 as described above, the inner flange portion 56 including the reinforcing rib 58 of the resin block 53 and the boss portion 62 bulge radially inward beyond the teeth 31 b of the stator core 34. When the stator 10 and the rotor 11 are assembled into the housing 13 together with the sensor unit 45 and the like, the inner flange portion 56 and the boss portion 62 bulge radially inward beyond the outer circumferential surface of the rotor 11 between the rotor 11 and the sensor unit 45 by a predetermined amount.

[0051] Fig. 8 is a plan view of the stator 10 as viewed from the rear side, and Fig. 9 is an enlarged view of section IX in Fig. 8. A circular filling opening 65 is formed at approximately the circumferential center of each busbar terminal 51Ub (between the start wire connection portion 54s and the end wire connection portion 54e). The filling opening 65 penetrates each busbar terminal 51Ub in the thickness direction. The filling opening 65 of each busbar terminal 51Ub opens in an approximately midpoint between each pair of circumferentially adjacent coils 33 when viewed in the axial direction. More specifically, the filling opening 65 faces the outer surfaces of the outermost layers of the winding portions of the two coils 33 and faces near the base of the end wire portion 33e of one of the coils 33.

[0052] To be precise, the filling openings 65 of each busbar terminal 51Ub, 51Ub, 51Ub are not formed exactly at the circumferential center of each terminal, but are positioned closer to the end-wire connection portion 54e than to the center. That is, in each busbar terminal 51Ub, 51Ub, 51Ub, the filling openings 65 are positioned closer to the end-wire connection portion 54e than to the start-wire connection portion 54s. In this embodiment, the filling openings 65 are offset by 1° about the axis o from the circumferential center of each busbar terminal 51Ub, 51Ub, 51Ub toward the end-wire connection portion 54e. The diameter of the filling openings 65 is set to approximately 5 mm from the viewpoints of maintaining the strength of each busbar terminal 51Ub, 51Ub, 51Ub and suppressing current density (suppressing heat generation due to increased current density).

[0053] The filling opening 65 is used as a filling port for adhesive 70 ( FIG. 9 ) when adhesively fixing the base of the wire end portion 33e to the winding portion of the coil 33 as a pre-processing step of connecting the wire end portion 33e of each coil 33 to the wire end connecting portion 54e of the busbar terminals 51Ub, 51Ub, 51Ub. When actually adhesively fixing the base of the wire end portion 33e to the winding portion of the coil 33, the tip of the nozzle of a filling device (not shown) is inserted into the filling opening 65 from the axial outside of the busbar terminals 51Ub, 51Ub, 51Ub, and adhesive 70 dispensed from the nozzle is filled into the winding portion of the coil 33 on the base side of the wire end portion 33e. At this time, the tip of the nozzle can be brought sufficiently close to the winding portion on the base side of the wire end portion 33e through the filling opening 65. Therefore, as shown in FIG. 9 , a necessary and sufficient amount of adhesive 70 can be filled into the winding portion on the base side of the wire end portion 33e. When the applied adhesive 70 hardens, the end wire portion 33e is fixed to the winding portion of the coil 33, and the end wire portion 33e does not separate (come apart) from the winding portion.

[0054] <Operation of Electric Motor 1> A three-phase drive current is supplied to the multiple coils 33 of the stator 10 through a drive circuit in the controller. When drive current is supplied to the coils 33 in this manner, a rotating magnetic field is generated in the stator 10. As a result, the rotor 11 receives torque from the rotating magnetic field and rotates in a predetermined direction. At this time, the rotation of the rotor 11 is detected by a sensor unit 45 disposed opposite the rear side of the rotating shaft 12. Rotation information of the rotating shaft 12 detected by the sensor unit 45 is output to the controller, and the controller controls the drive current based on this rotation information.

[0055] Effect of the Embodiment As described above, the electric motor 1 of this embodiment has a fill opening 65 provided between the start wire connection portion 54s and the end wire connection portion 54e of each busbar terminal 51Ub, 51Ub, 51Ub of the busbar unit 50. Therefore, when bonding the vicinity of the end wire portion 33e of the coil 33 to the winding portion, the adhesive 70 can be directly filled near the end wire portion 33e of the coil 33 through the fill opening 65 of the busbar terminals 51Ub, 51Ub, 51Ub. Therefore, when the electric motor 1 of this embodiment is used, the adhesive 70 is less likely to flow into unnecessary areas other than the vicinity of the end wire portion 33e, making it possible to reduce the amount of adhesive 70 filled. Furthermore, because the amount of adhesive 70 filled can be reduced in this way, the curing time of the adhesive 70 can be shortened, thereby shortening the assembly time of the electric motor 1.

[0056] Therefore, by adopting the electric motor 1 of this embodiment, it is possible to reduce the amount of adhesive 70 used and improve the efficiency of the assembly work, which makes it possible to contribute to Goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "Ensure access to affordable, reliable, sustainable and modern energy for all."

[0057] Furthermore, in the electric motor 1 of this embodiment, the filling opening 65 of each bus bar terminal 51Ub, 51Ub, 51Ub is positioned closer to the base of the end wire portion 33e of one adjacent coil 33 than to the base of the start wire portion 33s of the other adjacent coil 33. Therefore, when the electric motor 1 of this embodiment is used, the area near the end wire portion 33e can be easily and accurately filled into the winding portion of the other coil 33 through the filling opening 65 of each bus bar terminal 51Ub, 51Ub, 51Ub.

[0058] In particular, in the electric motor 1 of this embodiment, the filling opening 65 is formed in a position closer to the end wire connection portion 54e than to the start wire connection portion 54s of each bus bar terminal 51Ub. Therefore, while each bus bar terminal 51Ub remains positioned midway between the winding portions of two circumferentially adjacent coils 33, only the filling opening 65 can be positioned shifted toward the base of the start wire portion 33s of one of the coils 33. Therefore, when this configuration is adopted, the installation of each bus bar terminal 51Ub can be made easier. However, it is also possible to form the filling opening 65 at a midpoint between the start line connection portion 54s and the end line connection portion 54e of the bus bar terminals 51Ub, 51Ub, 51Ub, and shift the entire bus bar terminals 51Ub, 51Ub, 51Ub toward the end line portion 33e so that the filling opening 65 is close to the vicinity of the end line portion 33e of the other coil 33.

[0059] Furthermore, in the electric motor 1 of this embodiment, multiple busbar terminals 51Ub, 51Ub, 51Ub, each having a filling opening 65, are integrated into the annular busbar unit 50. In other words, the busbar unit 50 includes busbars 51U, 51V, 51W and an insulating resin block 53 that holds the busbars 51U, 51V, 51W spaced apart from one another, and each busbar 51U, 51V, 51W includes a substantially C-shaped busbar main body 51Ua, 51Va, 51Wa embedded in the resin block 53, and busbar terminals 51Ub, 51Ub, 51Ub protruding radially outward from the busbar main body 51Ua, 51Va, 51Wa. Therefore, by positioning and fixing the bus bar unit 50 to one axial end of the stator core 34 (insulator 32), the filling openings 65 of all of the bus bar terminals 51Ub, 51Ub, 51Ub can be positioned to facilitate filling with the adhesive 70. Therefore, when the electric motor 1 of this embodiment is adopted, the manufacture of the electric motor 1 can be facilitated.

[0060] The present invention is not limited to the above embodiment, and various design modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, the stator 10 is formed by twelve divided cores 30, but the number of divided cores 30 constituting the stator 10 may be any number other than twelve.

[0061] In the above embodiment, portions of the three bus bars 51U, 51V, and 51W for the U, V, and W phases are embedded inside the common resin block 53. However, the bus bars 51U, 51V, and 51W do not have to be integrated with the resin block 53. For example, the bus bars 51U, 51V, and 51W may be secured to insulating holding members.

[0062] 1...electric motor, 2...chain, 10...stator, 11...rotor, 12...rotating shaft, 12e...end face, 12o...rotation output portion, 13...housing, 14...case body, 15...rear cover, 16...front cover, 20...rotor body, 21...permanent magnet, 22F, 22R...bearing, 23...concave portion, 24...sensor magnet, 25...rotation sensor, 26...through hole, 27...support portion, 28...engagement groove, 29...raised piece, 30...division Core, 31...core portion, 31a...core back divided piece, 31b...teeth, 32...insulator, 32b...divided block, 33...coil, 33e...finishing portion, 33s...starting portion, 34...stator core, 35...surrounding portion, 36i...inner flange portion, 36o...outer flange portion, 37...projecting piece, 38...recess, 40...thermistor accommodating portion, 41...thermistor, 42...leaf spring, 43s, 43e...coil fitting groove, 44...engaging recess, 4 5...sensor unit, 46...sensor board, 47...sensor connector, 48...sensor harness, 49...lid member, 50...bus bar unit, 51U, 51V, 51W...bus bar, 51Ua, 51Va, 51Wa...bus bar main body, 51Ub, 51Vb, 51Wb...bus bar terminal, 51Ub1, 51Vb1, 51Wb1...terminal base, 51Ub2, 51Vb2, 51Wb2...terminal connection portion, 52...drive connector, 5 3...resin block, 54s...connection portion for starting line, 54e...connection portion for ending line, 55...block main body, 56...inner flange, 57r...step portion, 58...reinforcing rib, 59...adhesive filling port, 60...protrusion portion, 61...locking protrusion, 62...boss portion, 63...adhesive, 65...filling opening, 70...adhesive, TU, TV, TW...power terminal, A...axial direction, R...radial direction, C...circumferential direction, FR...front side, o...axis center, Wf...front wheel, Wr...rear wheel.

Claims

an annular stator; and a rotor arranged radially inside the stator and rotating relative to the stator, the stator comprising: a stator core having a plurality of teeth protruding radially inward from a plurality of circumferential positions, a plurality of coils wound around each of the teeth, and a busbar unit arranged at one axial end of the stator core and supplying power to each of the coils wound around the teeth, the busbar unit having a plurality of busbar terminals arranged to straddle the winding portions of each of the coils adjacent in the axial direction when viewed in the axial direction, each of the busbar terminals being provided at two positions spaced apart in the circumferential direction with a start wire connection portion to which a start wire portion of one of the adjacent coils is connected and an end wire connection portion to which an end wire portion of the other circumferentially adjacent coil is connected, and a filling opening is provided between the start wire connection portion and the end wire connection portion of each of the busbar terminals for filling an adhesive with the winding portion of the coil near the end wire portion.

2. An electric motor as described in claim 1, characterized in that the filling opening is positioned closer to the base of the end portion of one of the adjacent coils than to the base of the start portion of the other adjacent coil.

3. An electric motor according to claim 2, characterized in that the filling opening is formed at a position closer to the end wire connection portion than to the start wire connection portion of the bus bar terminal.

4. The electric motor according to claim 1, characterized in that the busbar unit comprises three busbars for U-phase, V-phase and W-phase, and an insulating resin block that holds the three busbars spaced apart from one another, and each of the busbars comprises a substantially C-shaped busbar body embedded in the resin block, and the busbar terminals protrude radially outward from the busbar body.

Images