Electric motor

Abstract

To provide an electric motor capable of suppressing performance deterioration of a sensor unit caused by heat generated by a coil and a rotor.SOLUTION: An electric motor comprises a stator 10, a rotor 11, and a sensor unit. The rotor 11 comprises a revolving shaft. The sensor unit is arranged opposed to an end face on one end side in a shaft direction of the revolving shaft. The stator 10 comprises a stator core 34, an insulator 32, and a coil 33. The stator core 34 comprises a plurality of teeth 31b each protruding inward in a radial direction. The insulator 32 is attached to an outer-peripheral part of the teeth 31b. The coil 33 is wound around each of the teeth 31b via the insulator 32. At an end in the shaft direction on the same side as a side where the sensor unit of the insulator 32 is arranged, a wall part 39 protruding on an inner side in a radial direction than an outer-peripheral face of the rotor 11 is provided between the rotor 11 and the sensor unit.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] 2. Description of the Related Art Known electric motors used as drive sources for vehicles and the like include those that detect the rotation state of a rotor by a rotation sensor formed of a magnetic resistance element and the like (see, for example, Patent Document 1).

[0003] The electric motor described in Patent Document 1 includes an annular stator fixed inside a housing, a rotor rotatably disposed radially inside the stator, and a sensor unit for detecting rotation of the rotor. The sensor unit includes a rotation sensor formed of a magnetoresistive element or the like, and a sensor board on which the rotation sensor is mounted.

[0004] The stator includes a stator core made of a magnetic material, an insulator attached to the stator core, a plurality of coils wound around the stator core via the insulator, and a busbar unit for supplying power to each coil. The stator core includes an annular core body and a plurality of teeth protruding radially inward from the core body. The insulator is made of an insulating resin material and is wound around the outer periphery of each tooth of the stator core. The busbar unit has three busbars in a substantially C-shape for U-phase, V-phase, and W-phase, and a portion of these busbars is embedded in an annular insulating resin block. Each of the three-phase busbars is electrically connected to the corresponding coil wound around the tooth and is connected to each of the three-phase power supply terminals. The busbar unit is fixed to the stator core while being placed on the axial ends of the multiple insulators.

[0005] The rotor has a rotating shaft at its axial center, and the rotating shaft is rotatably supported by the housing via a bearing. One axial end (hereinafter referred to as the "base end") of the rotating shaft is accommodated in the housing, and the other axial end (hereinafter referred to as the "tip end") protrudes from the housing to the outside. The tip end of the rotating shaft serves as a rotation output part for outputting power to the outside. A sensor magnet is attached to the end face of the base end of the rotating shaft. The sensor unit is fixed inside the housing so as to face the end face of the base end of the rotating shaft. The rotation sensor of the sensor unit detects the change in magnetic pole of the sensor magnet that accompanies the rotation of the rotor (rotating shaft), and detects the rotation state of the rotor based on the detection information. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2023-6461 A Summary of the Invention [Problem to be solved by the invention]

[0007] In this type of electric motor, the coil and rotor of the stator generate heat due to continuous operation, etc., and the heat is easily transferred to surrounding components. In particular, in the electric motor described in Patent Document 1, the sensor unit (rotation sensor and sensor board) is arranged inside the housing so as to face the base end of the rotating shaft, so there is a concern that the heat from the coil and rotor will be transferred to the sensor unit. Furthermore, there is a risk that the performance of electronic components mounted on the sensor board of the sensor unit will be degraded by high heat, so it is desirable to further suppress the heat transfer from the coil and rotor.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS The present invention provides an electric motor capable of suppressing degradation of the performance of a sensor unit caused by heat generated by a coil or a rotor. [Means for solving the problem]

[0009] An electric motor according to one embodiment of the present invention comprises an annular stator, a rotor having a rotating shaft and rotatably arranged radially inward of the stator, and a sensor unit arranged opposite an end face on one axial end of the rotating shaft and having a rotation sensor that detects rotation of the rotating shaft and a sensor board on which the rotation sensor is mounted, wherein the stator comprises a stator core having a plurality of teeth arranged along the circumferential direction of the stator and protruding radially inward, an insulator attached to the outer periphery of each of the teeth, and a coil wound around each of the teeth via the insulator, and the axial end of the insulator on the same side as the side on which the sensor unit is arranged is provided with a wall portion between the rotor and the sensor unit that protrudes radially inward beyond the outer periphery of the rotor.

[0010] With the above configuration, when a rotating magnetic field is generated in the stator by energizing the coil, the rotor receives a force from the rotating magnetic field and rotates in a predetermined direction. The rotation of the rotor at this time is detected by the sensor unit arranged on one end side of the rotating shaft. If the rotor continues to rotate due to energization of the coil, the coil of the stator and the rotor generate heat, and their temperatures rise. At this time, since a wall portion that protrudes radially inward from the outer circumferential surface of the rotor between the rotor and the sensor unit is provided at one axial end of the insulator of the stator, the heat of the coil and the rotor is blocked by the wall portion and is difficult to be transmitted to the rotation sensor and the sensor board of the sensor unit.

[0011] The wall portion may include a protruding piece that protrudes radially inward beyond an outer circumferential surface of the rotor from the axial end of each of the insulators.

[0012] In this case, if a protruding piece is formed in advance on the axial end of each insulator, at least a part of the wall portion can be easily formed by simply attaching the insulator to the corresponding tooth. Therefore, when this configuration is adopted, it is possible to facilitate the manufacture of the wall portion.

[0013] The wall portion may include an annular block fixed to the plurality of protruding pieces and arranged at a position where at least a portion of the annular block overlaps with an outer circumferential edge portion of the rotor in the axial direction.

[0014] In this case, in addition to the protruding pieces protruding from each insulator, an annular block is interposed between the rotor and the sensor unit, making it possible to more reliably suppress the heat generated by the coil and rotor from being transmitted to the sensor unit.

[0015] The annular block may be configured by a bus bar unit in which a plurality of bus bars are embedded in an insulating resin.

[0016] In this case, the busbar unit for supplying power to the coil constitutes part of the wall, and therefore, when this configuration is adopted, the number of parts can be reduced compared to a case in which the wall and the busbar unit are provided separately, and the electric motor can be made smaller and lighter.

[0017] The busbar unit may have a plurality of boss portions protruding axially to face each of the protruding pieces of the insulator, and each of the protruding pieces of the insulator may be provided with a recess into which a corresponding one of the boss portions of the busbar unit is inserted, and each of the boss portions, when inserted into the corresponding recess, may be fixed to the protruding piece by adhesive filled in the recess.

[0018] In this case, the multiple bosses of the busbar unit are adhesively fixed to the corresponding protruding pieces while being inserted into the recesses of the corresponding protruding pieces. Therefore, when this configuration is adopted, the busbar unit is firmly fixed to the multiple protruding pieces and is stably supported by the highly rigid stator core via the insulator.

[0019] The busbar unit may be configured so that the thickness direction of each busbar faces the axial direction of the rotation shaft, and the multiple busbars are arranged in series in the axial direction, and power terminals connected to each busbar protrude in a direction approximately perpendicular to the axial direction in an axial extension region of the busbar.

[0020] In this case, while adopting a structure in which the busbar unit blocks heat from the coil and rotor, it is possible to prevent the busbar unit and the power terminal from increasing the axial length of the electric motor. That is, in the busbar unit, the plate thickness direction of each busbar faces the axial direction of the rotation shaft, and multiple busbars are arranged in series in the axial direction, so that the busbar unit can be made thinner in the axial direction. In addition, the power terminals connected to each busbar of the busbar unit protrude in a direction approximately perpendicular to the axial direction in the axial extension region of the busbar, so that they do not protrude in the axial direction beyond the busbar unit. This makes it possible to shorten the axial length of the electric motor.

[0021] It is desirable that the wall portion protrudes radially inward to a position where it at least partially overlaps with a permanent magnet arranged on the rotor when viewed in the axial direction.

[0022] In this case, since the wall portion is positioned so that at least a portion of the wall portion overlaps with the rotor's permanent magnet in the axial direction, the heat generated by the rotor is less likely to be transmitted by the sensor unit. Therefore, when this configuration is adopted, it is possible to further suppress the deterioration of the performance of the sensor unit due to the heat generated by the rotor.

[0023] The rotating shaft may have an axial end on the side opposite to the side on which the sensor unit is disposed that protrudes outward as a rotation output portion.

[0024] In this case, when a large axial load is input from the outside to the end of the rotating shaft, which is the rotation output part, the rotor abuts against the wall, making it possible to suppress excessive axial displacement of the rotating shaft. Effect of the Invention

[0025] In the electric motor according to the present invention, the heat generated by the coil and rotor is blocked by the wall and is less likely to be transmitted to the sensor unit, thereby suppressing degradation of the performance of the sensor unit due to the heat generated by the coil and rotor. [Brief description of the drawings]

[0026] [Figure 1] FIG. 2 is a side view of the electric motor according to the embodiment. [Diagram 2] FIG. 2 is a plan view of the electric motor according to the embodiment with some components removed. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 . [Figure 4] 4 is a cross-sectional view taken along line IV-IV in FIG. 2 . [Diagram 5] FIG. 2 is a perspective view of the electric motor according to the embodiment with some components removed. [Figure 6] FIG. 2 is a perspective view of the busbar unit according to the embodiment, as viewed from one side in the axial direction. [Figure 7] FIG. 4 is a perspective view of the busbar unit according to the embodiment, as viewed from the other axial side. [Figure 8] 1 is a side view showing an example of an electric motorcycle equipped with an electric motor according to an embodiment; [Figure 9] FIG. 4 is a side view showing another example of an electric motorcycle equipped with the electric motor according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a side view of an electric motor 1 of this embodiment, and Fig. 2 is a plan view of the electric motor 1 with some components removed, and Fig. 3 is a cross-sectional view of the electric motor 1 taken along line III-III in Fig. 2. The electric motor 1 of 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 a drive wheel, as shown in FIG. 8. 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 arrangement of the electric motor 1 is not limited thereto, and the electric motor 1 can also be mounted on the vehicle body frame between the front wheel Wf and the rear wheel Wr, as shown in FIG. 9. In this case, the power of the electric motor 1 is transmitted to the rear wheel Wr via a chain 2 or a belt.

[0028] 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 circumferential surface of the rotor 11 and the stator 10. The rotor 11 has a rotating shaft 12 at its axial center. In the following, unless a direction is specifically specified, the direction along the axis o of the rotating shaft 12 is referred to as the "axial direction," the direction perpendicular to the axis o is referred to as the "radial direction," and the circumferential direction about the axis o is 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 places in the drawings.

[0029] The stator 10 and the main part of the rotor 11 inside are accommodated 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 bolts 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 place in the drawings.

[0030] 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 parts such as the rear cover 15 removed. As shown in Figs. 2 to 5, the stator 10 is formed into 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. The split cores 30 include a core portion 31, an insulator 32, and a coil 33.

[0031] The core portion 31 is formed by stacking a plurality of steel plates (magnetic bodies) in an approximately T-shape in an axial view in the axial direction. The core portion 31 includes core-back segments 31a in an arc shape in an axial view, and teeth 31b protruding radially inward from approximately the center position in the circumferential direction of the core-back segments 31a. The approximately T-shape is formed by the core-back segments 31a and the teeth 31b. The core portions 31 of the multiple split cores 30 form an annular stator core 34 by connecting both ends in the circumferential direction of the core-back segments 31a to the ends of the adjacent core-back segments 31a. In this state, each tooth 31b protrudes radially toward the axis o.

[0032] The insulators 32 are formed 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 protruding radially inward from the core back divided pieces 31a of the core portion 31 have a cross section perpendicular to the radial direction formed in a substantially rectangular shape. The insulators 32 cover two faces of the substantially rectangular cross section of the teeth 31b along the axial direction and two faces on one end side and the other end side in the axial direction. That is, the insulators 32 cover the periphery of the substantially rectangular cross section of the corresponding teeth 31b. Each insulator 32 is composed of two divided blocks 32b divided in the axial direction. In FIG. 4, only the rear divided block 32b is shown.

[0033] As shown in Fig. 4, the insulator 32 has a rectangular cylindrical surrounding portion 35 surrounding the outer circumferential surface of the corresponding tooth 31b, an outer flange portion 36o extending outward (outward in the circumferential direction and the axial direction) from an end portion of the surrounding portion 35 on the radially outer side (the core-back divided piece 31a side), and an inner flange portion 36i extending outward (outward in the circumferential direction and the axial direction) from an end portion of the surrounding portion 35 on the radially inner side. 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 in a state where its position is restricted in the radial direction by the inner flange portion 36i and the outer flange portion 36o. Each coil 33 is wound around the outer circumferential surface of 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.

[0034] As shown in Figures 2, 4 and 5, a protruding piece 37 that protrudes radially inward is provided at the axial end of the rear side of the inner flange portion 36i of the divided block 32b on the rear side of each insulator 32. The protruding piece 37 is a block that is approximately rectangular in the axial direction, and a recess 38 that is approximately rectangular in the axial direction is formed on the surface facing the rear side in the axial direction. The recess 38 opens toward the rear side in the axial direction. In this embodiment, the protruding pieces 37 of all the insulators 32 form part of a wall portion 39 that will be described in detail later.

[0035] As shown in Figs. 4 and 5, the rear split block 32b of each insulator 32 has a thermistor housing 40 that bulges outward in a rectangular shape in the radial direction at a substantially central portion in the circumferential direction of the outer flange portion 36o. The thermistor housing 40 is disposed axially outward (on the rear side) of the outer flange portion 36o of the rear split block 32b from the end face of the rear side of the stator core 34. 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 on the inner wall of the thermistor housing 40 on the radial inner side, so that the temperature detection portion of the thermistor 41 housed in the thermistor housing 40 comes into contact with 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.

[0036] As shown in FIG. 5, a pair of coil fitting grooves 43s, 43e that open toward the rear side are formed on the rear end edge of the outer flange portion 36o of each divided block 32b. These coil fitting grooves 43s, 43e are provided on both sides in the circumferential direction sandwiching the thermistor accommodating portion 40. Each coil fitting groove 43s, 43e penetrates the outer flange portion 36o in the thickness direction. In one coil fitting groove 43s, the start portion 33s of the coil 33 wound around the corresponding tooth 31b is fitted and provisionally locked via the insulator 32. In the other coil fitting groove 43e, the end portion 33e of the coil 33 wound around the corresponding tooth 31b is fitted and provisionally locked via the insulator 32. The start portion 33s and the end portion 33e of the coil 33 fitted in the coil fitting grooves 43s, 43e are drawn out in the radial direction of the outer flange portion 36o. A start portion 33s and an end portion 33e of the coil 33 drawn out radially outward from the outer flange portion 36o are connected to bus bars 51U, 51V, and 51W, which will be described later, after the divided blocks 32b are assembled in an annular shape.

[0037] The rotor 11, which is disposed radially inside the stator 10, includes a rotor body 20 formed in a generally cylindrical shape by stacking a plurality of steel plates (magnetic bodies) in the axial direction, as shown in Fig. 3. A rotating shaft 12 is press-fitted and fixed to the center of rotation (axial center) of the rotor body 20. A plurality of generally plate-shaped permanent magnets 21 are embedded inside the rotor body 20. The plurality of permanent magnets 21 are arranged in the circumferential direction of the rotor body 20 such that the N poles and S 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 to this. The rotor 11 can also employ a so-called "SPM (Surface Permanent Magnet) structure" in which permanent magnets 21 are attached to the outer surface of the rotor body 20.

[0038] The rotating shaft 12 protrudes from one end (rear side) and the other end (front side) in the axial direction 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 in this state. One end of the rotating shaft 12 passing through the front cover 16 is a rotation output part 12o to which an output gear or sprocket is attached. The rotation output part 12o protrudes outward in the axial direction from the housing 13 of the electric motor 1, and, as shown in Figs. 8 and 9, when attached to the body of a motorcycle, protrudes outward in the width direction of the body.

[0039] A concave portion 23 (see FIG. 3) that opens toward the rear side is formed on the rear side surface of the rear cover 15. One end of the rotating shaft 12 penetrates the rear cover 15 in the thickness direction so that an end face 12e on the rear side is exposed in the concave portion 23. A substantially disk-shaped sensor magnet 24 is fixed to the end face 12e of the rotating shaft 12. The sensor magnet 24 serves as a detection target for detecting the rotation state when the rotation state of the rotor 11 (rotating shaft 12) is detected by a rotation sensor 25 described later.

[0040] As shown in Fig. 3, a plurality of support pillars 27 are protrudingly provided within 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 magnetic resistance 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 therebetween.

[0041] 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) of the electric motor 1 by a wiring (not shown). As described above, the recessed portion 23 of the rear cover 15 in which the sensor unit 45 is attached is closed by a lid member 49 shown in FIGS.

[0042] 2 to 4, a substantially annular busbar unit 50 is attached to the rear end of the insulator 32 (stator 10). 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.

[0043] 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, a U-phase power terminal TU, a V-phase power terminal TV, and a W-phase power terminal TW are installed in the drive connector 52. These power terminals TU, TV, and TW penetrate the peripheral wall of the case body 14, and the inner ends of the case body 14 are electrically connected to the bus bars 51U, 51V, and 51W, respectively. Each of the power terminals TU, TV, and TW is formed of a conductive metal plate and is attached to the case body 14 so that the plate thickness direction faces the axial direction. Each of the power terminals TU, TV, and TW protrudes in a direction approximately perpendicular to the axial direction within the range of the axial thickness of the bus bar unit 50 described later (within the range of the axial extension area of ​​the bus bar unit 50). In addition, the outer ends of the case body 14 of each of the power terminals TU, TV, and TW are connected to a drive circuit of a controller not shown. A driving current is supplied to the coils 33 wound around each of the teeth 31b of the stator 10 from the driving circuit via power terminals TU, TV, TW and bus bars 51U, 51V, 51W.

[0044] 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. In the busbar unit 50, busbar bodies 51Ua, 51Va, and 51Wa (see Figs. 3 and 4) of three busbars 51U, 51V, and 51W are embedded in an annular resin block 53 made of insulating resin material in a state where they are spaced apart in the axial direction. Each busbar body 51Ua, 51Va, and 51Wa is formed of a conductive metal plate that is substantially C-shaped when viewed in the axial direction. The plate thickness direction of these busbar bodies 51Ua, 51Va, and 51Wa is oriented in the axial direction, and all of the busbar bodies 51Ua, 51Va, and 51Wa are arranged in series in the axial direction. The annular resin block 53 is fixed to the rear end of each insulator 32 of the divided core 30 assembled in an annular shape. In this state, the resin block 53 is arranged so as to be concentric with the stator core 34. A specific manner in which the resin block 53 is fixed to the insulator 32 will be described in detail later.

[0045] 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 of a conductive metal plate integrally with the corresponding busbar body 51Ua, 51Va, 51Wa. The three busbars 51U, 51V, 51W are arranged such that the plate thickness direction of each busbar 51U, 51V, 51W faces the axial direction, and all the busbars 51U, 51V, 51W are arranged in series in the axial direction.

[0046] Three of the four busbar terminals 51Ub for the U phase are formed in a substantially rectangular shape having a constant width along the circumferential direction of the resin block 53. The remaining one of the four busbar terminals 51Ub for the U phase has a shape in which a terminal connection portion 51Ub2 that bulges outward in a mountain shape in the radial direction is connected to a terminal base portion 51Ub1 that is substantially rectangular in shape having a constant width along the circumferential direction of the resin block 53. Similarly, three of the four busbar terminals 51Vb, 51Wb for the V phase and the W phase are formed in a substantially rectangular shape having a constant width along the circumferential direction of the resin block 53, and the remaining one of the four busbar terminals 51Vb, 51Wb for the V phase and the W phase has a shape in which a terminal connection portion 51Vb2, 51Wb2 that bulges outward in a mountain shape in the radial direction is connected to a terminal base portion 51Vb1, 51Wb1 that is substantially rectangular in shape having a constant width along the circumferential direction of the resin block 53. Terminal base portions 51Ub1, 51Vb1, 51Wb1 of the bus bar terminals 51Ub, 51Vb, 51Wb having terminal connection portions 51Ub2, 51Vb2, 51Wb2 are shaped substantially the same as the other bus bar terminals 51Ub, 51Vb, 51Wb.

[0047] 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. The U-phase busbar terminal 51Ub, the V-phase busbar terminal 51Vb, and the W-phase busbar terminal 51Wb that are arranged adjacent to each other are equally spaced apart in the circumferential direction of the resin block 53. The busbar terminals 51Ub, 51Vb, and 51Wb of each phase having terminal connection portions 51Ub2, 51Vb2, and 51Wb2 are arranged in a concentrated manner in a specific circumferential region of the resin block 53. Terminal connection portions 51Ub2, 51Vb2, 51Wb2 of these bus bar terminals 51Ub, 51Vb, 51Wb are electrically connected to corresponding power supply terminals TU, TV, TW of the drive connector 52 (see FIG. 2).

[0048] As shown in Figs. 6 and 7, each of the busbar terminals 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 Fig. 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 of the busbar terminals 51Ub, 51Ub, 51Ub. The finish wire connection portion 54e is provided near the other circumferential side of the radially outer edge of each of the busbar terminals 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.

[0049] The engagement groove 28 is a recessed groove extending from the radially outer end of each busbar terminal 51Ub, 51Ub, 51Ub toward the radially inner side, and the cut-and-raised piece 29 is cut and raised from the bottom of the engagement groove 28 toward the rear side. The start wire portion 33s and the end wire portion 33e of the coil 33 drawn out from the coil fitting grooves 43s, 43e of the insulator 32 described above are inserted and engaged in the engagement groove 28. The start wire portion 33s and the end wire portion 33e inserted into the engagement groove 28 are drawn out to the rear side along the axial direction. In this state, the start wire portion 33s and the end wire portion 33e are fixed by welding to the corresponding cut-and-raised piece 29. The start wire portion 33s and the end wire portion 33e of each coil 33 wound around the tooth 31b are thus connected to the start wire connecting portion 54s and the end wire connecting portion 54e of the corresponding busbar terminal 51Ub, 51Ub, 51Ub.

[0050] Here, each busbar terminal 51Ub, 51Ub, 51Ub protruding radially from the annular resin block 53 is disposed at a substantially midpoint of the axial center of the winding portions (teeth 31b) of two circumferentially adjacent coils 33 as viewed in the axial direction. That is, each busbar terminal 51Ub, 51Ub, 51Ub is disposed so as to straddle the winding portions (teeth 31b) of two circumferentially adjacent coils 33 as viewed in the axial direction. The start wire connection portion 54s of each busbar terminal 51Ub, 51Ub, 51Ub is connected to the start wire portion 33s of one of the winding portions adjacent in the circumferential direction as viewed in the axial direction, and the end wire connection portion 54e is connected to the end wire portion 33e of the coil 33 of the other winding portion adjacent in the circumferential direction as viewed in the axial direction.

[0051] 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, 51Wa are embedded and spaced apart in the axial direction, and an inner flange 56 having a relatively thin wall thickness 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 at a position closer to the front in the thickness direction (axial direction) of the block main body 55. A step 57r (see FIG. 4) is provided between the base (radially outer end) of the rear side surface of the inner flange 56 and the block main body 55.

[0052] 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 out toward the rear side 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 arranged.

[0053] Each reinforcing rib 58 is disposed at a circumferential position corresponding to the intermediate position between adjacent bus bar terminals 51Ub, 51Vb, 51Wb in the circumferential direction. An adhesive filling port 59 that vertically penetrates 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.

[0054] As shown in Figures 4 and 7, a ring-shaped protrusion 60 is provided on the front side surface of the block body 55 of the resin block 53. The protrusion 60 is provided along the inner peripheral edge of the block body 55. The front end face of the protrusion 60 is provided with twelve locking projections 61 spaced equally apart in the circumferential direction. The front end face of the protrusion 60 is capable of abutting against the rear end face of the outer flange portion 36o of each insulator 32 of the stator 10 (see Figures 4 and 5).

[0055] Furthermore, between the outer flange portions 36o of the insulators 32 adjacent to each other in the circumferential direction, engagement recesses 44 (see FIG. 5) that open toward the rear side are formed. A plurality of locking projections 61 protruding from the protruding stripe portion 60 of the resin block 53 are adapted to be able to fit 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 projections 61 into the engagement recesses 44 between the insulators 32. In addition, when the multiple locking projections 61 of the resin block 53 are fitted into the engagement recesses 44 between the insulators 32, the inner flange portion 56 and the reinforcing ribs 58 bulge radially inward beyond the tips of the teeth 31b of the stator 10.

[0056] As shown in Figs. 4 and 7, twelve rectangular pillar-shaped bosses 62 are provided on the front side of the inner flange 56 of the resin block 53 at equal intervals in the circumferential direction to protrude toward the front side. Each boss 62 is provided at a position overlapping with each reinforcing rib 58 provided on the rear side of the inner flange 56 in the axial direction. Each boss 62 is provided at a circumferential position corresponding to the intermediate position between each of the busbar terminals 51Ub, 51Vb, and 51Wb adjacent in the circumferential direction. In addition, each boss 62 protrudes at its tip in the axial direction so as to face each of the protruding pieces 37 protruding from the rear side of the insulators 32. The tip 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 sufficiently larger capacity than the tip of the boss 62 to be inserted. The gap between the recess 38 and the boss 62 is a filled portion that is 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.

[0057] Each boss 62 of the resin block 53 is formed to be continuous with an 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 formed in a funnel shape such 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. The adhesive filling port 59 is filled with adhesive 63 from the rear side of the resin block 53 through the adhesive filling port 59 into the recess 38 of the protruding piece 37 on the insulator 32 side, with the corresponding boss 62 on the resin block 53 side inserted. When the adhesive 63 filled in the recess 38 in this way hardens, the resin block 53 of the busbar unit 50 is fixed to the rear end of the insulator 32 (the stator 10).

[0058] 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 31b of the stator core 34. When the stator 10 and the rotor 11 are assembled into the housing 13 together with the busbar unit 50, the sensor unit 45, etc., as will be described in detail later, the inner flange portion 56 and the boss portion 62 protrude radially inward beyond the outer circumferential surface of the rotor 11 between the rotor 11 and the sensor unit 45 by a predetermined amount. At this time, the protruding pieces 37 of each insulator 32 also protrude radially inward beyond the outer circumferential surface of the rotor 11 by a predetermined amount between the rotor 11 and the sensor unit 45. In this embodiment, the protruding pieces 37 of each insulator 32 and a part of the resin block 53 form a wall portion 39. The wall portion 39 is interposed between the rotor 11 and the sensor unit 45, and blocks the heat of the coil 33 of the stator 10 and the rotor 11 from being transmitted to the sensor unit 45. In this embodiment, the wall portion 39 protrudes radially inward to a position where it at least partially overlaps with the permanent magnet 21 arranged on the rotor 11 when viewed in the axial direction.

[0059] <Assembly of electric motor 1> For the stator 10, a plurality of split cores 30 are prepared in advance by winding coils 33 around teeth 31b of each stator core 34 to which an insulator 32 is attached. Then, the plurality of split cores 30 thus prepared are assembled in an annular shape to form the stator 10.

[0060] Thereafter, the busbar unit 50 is coaxially arranged on the rear end face (end face on one axial end side) of each insulator 32 of the annular stator 10. At this time, the multiple locking projections 61 protruding from the front side of the resin block 53 are fitted into the engagement recesses 44 between the adjacent insulators 32 of the stator 10. As a result, the resin block 53 is positioned with respect to the stator 10.

[0061] In this way, when the resin block 53 is positioned relative to the stator, each boss portion 62 arranged radially inside the resin block 53 is also positioned relative to the corresponding protruding piece 37 of the insulator 32, and the tip portion of each boss portion 62 is inserted into the recess 38 of the corresponding protruding piece 37.

[0062] Thereafter, a filling nozzle (not shown) for adhesive 63 is inserted sequentially from the rear side of resin block 53 into adhesive filling port 59 of radially inner reinforcing rib 58, and adhesive 63 is filled through adhesive filling port 59 into the gap between recess 38 of protruding piece 37 and boss portion 62. In this manner, the adhesive 63 is left to harden, and when the adhesive 63 has hardened, resin block 53 (busbar unit 50) is adhesively fixed to the end portion on the rear side of insulator 32 (stator 10).

[0063] The assembly of the stator 10 and the busbar unit 50 fixed as described above is fixed inside the cylindrical case body 14 of the housing 13. The rotor 11 is inserted and disposed on the inner circumferential side of the stator 10 fixed to the case body 14. After that, the electric wiring and parts of each part are assembled, and then the rear cover 15 and the front cover 16 are assembled to both ends in the axial direction of the case body 14. At this time, the rotating shaft 12 of the rotor 11 is rotatably supported by the rear cover 15 and the front cover 16 via the bearings 22R and 22F. Also, at this time, the sensor magnet 24 at the rear end of the rotating shaft 12 inserted into the through hole 26 in the center of the rear cover 15 faces the sensor unit 45 (thermistor 41 and sensor board 46) supported by the rear cover 15. After that, the concave portion 23 of the rear cover 15 is closed by the lid member 49.

[0064] <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 of the controller. When the 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 begins to rotate in a predetermined direction. At this time, the rotation of the rotor 11 is detected by a sensor unit 45 disposed opposite to the rear side of the rotating shaft 12. Rotation information of the rotating shaft 12 detected by the sensor unit 45 is output to a controller, and the controller controls the drive current based on the rotation information.

[0065] <Effects of the embodiment> As described above, in the electric motor 1 of this embodiment, the wall portion 39 that protrudes radially inward from the outer circumferential surface of the rotor 11 between the rotor 11 and the sensor unit 45 is provided at the axial end (rear end) of the insulator 32 on the same side as the side where the sensor unit 45 is arranged. Therefore, even if the coil 33 of the stator 10 and the rotor 11 generate heat as the rotor 11 continues to rotate due to the energization of the coil 33, the heat is blocked by the wall portion 39 and is difficult to transmit to the sensor unit 45. Therefore, when the electric motor of this embodiment is used, the deterioration of the performance of the sensor unit 45 due to the heat generated by the coil 33 and the rotor 11 can be suppressed.

[0066] Therefore, by employing the electric motor 1 of this embodiment, it is possible to maintain stable operating performance of the electric motor 1 with a simple configuration. As a result, it is 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."

[0067] Furthermore, in the electric motor 1 of this embodiment, a part of the wall portion 39 is configured by a protruding piece 37 that protrudes radially inward from the rear end of each insulator 32 beyond the outer circumferential surface of the rotor 11. Therefore, if the protruding piece 37 is formed in advance on the rear end of each insulator 32, a part of the wall portion 39 can be easily configured by simply attaching the insulator 32 to the corresponding tooth 31b. Therefore, when this configuration is adopted, the manufacturing of the wall portion 39 can be facilitated. The insulator 32 is made of a resin with low thermal conductivity, which makes it possible to suppress the transfer of heat from the coil 33 and the rotor 11 to the rear cover 15.

[0068] Furthermore, in the electric motor 1 of this embodiment, the wall portion 39 is configured to include the above-mentioned protruding pieces 37 of the multiple insulators 32, and an annular block (busbar unit 50) that is fixed to the multiple protruding pieces 37 and is arranged at a position overlapping with the outer circumferential edge portion of the rotor 11 in the axial direction. Therefore, the annular block (busbar unit 50) blocks the space between the rotor 11 and the sensor unit 45 over a wide range (over a 360° range). Therefore, when this configuration is adopted, it is possible to more reliably suppress the heat generated by the coil 33 and the rotor 11 from being transmitted to the sensor unit 45 side.

[0069] Furthermore, in the electric motor 1 of this embodiment, the annular block arranged at a position overlapping with the outer circumferential edge of the rotor 11 in the axial direction is configured with a busbar unit 50 having a plurality of busbars 51U, 51V, 51W embedded in insulating resin. In this embodiment, the busbar unit 50 for supplying power to the coil 33 configures part of the wall portion 39. Therefore, compared to the case where the wall portion 39 and the busbar unit 50 are provided separately, the number of parts can be reduced, and the electric motor 1 can be made smaller and lighter. The resin block 53 of the busbar unit 50 is made of a resin with low thermal conductivity. Therefore, the annular resin block 53 can further suppress the heat transfer from the coil 33 and the rotor 11 to the rear cover 15.

[0070] In the electric motor 1 of this embodiment, the busbar unit 50 has a plurality of bosses 62 that protrude in the axial direction so as to face each of the protruding pieces 37 of the insulator 32, and each of the protruding pieces 37 of the insulator 32 has a recess 38 into which the corresponding boss 62 of the busbar unit 50 is inserted. When each boss 62 of the busbar unit 50 is inserted into the corresponding recess 38, it is fixed to the protruding piece 37 by adhesive 63 filled in the recess 38. For this reason, when the electric motor 1 of this embodiment is used, the busbar unit 50 can be firmly fixed to the plurality of protruding pieces 37, and the busbar unit 50 can be stably supported by the highly rigid stator core 34 via the insulator 32.

[0071] In the electric motor 1 of this embodiment, the plate thickness direction of each busbar 51U, 51V, 51W of the busbar unit 50 is oriented in the axial direction, and all (the plurality of) busbars 51U, 51V, 51W are arranged in series in the axial direction. The power supply terminals TU, TV, TW connected to each busbar 51U, 51V, 51W protrude in a direction substantially perpendicular to the axial direction in the axial extension region of the three busbars 51U, 51V, 51W. Therefore, the electric motor 1 of this embodiment employs a structure in which the wall portion 39 including the busbar unit 50 blocks heat from the coil 33 and the rotor 11, while preventing the busbar unit 50 and the power supply terminals TU, TV, TW from increasing the axial length of the electric motor 1.

[0072] That is, in the case of this configuration, the plate thickness direction of each busbar 51U, 51V, 51W of the busbar unit 50 is oriented in the axial direction, and all of the busbars 51U, 51V, 51W are arranged in series in the axial direction, so that the busbar unit 50 can be made thinner in the axial direction. On the other hand, the power supply terminals TU, TV, TW protrude in a direction substantially perpendicular to the axial direction in the axial extension region of the busbars 51U, 51V, 51W, so do not protrude in the axial direction beyond the busbar unit 50. Therefore, when the electric motor 1 of this embodiment is used, the axial length of the electric motor 1 can be shortened while adopting a structure that blocks heat from the coil 33 and the rotor 11.

[0073] Furthermore, in the electric motor 1 of this embodiment, the wall portion 39 protrudes radially inward to a position where it at least partially overlaps with the permanent magnets 21 arranged on the rotor 11 when viewed in the axial direction. The heat generated by the rotor 11 is blocked by the wall portion 39 and is less likely to be transmitted by the sensor unit 45. Therefore, when this configuration is adopted, the deterioration in performance of the sensor unit 45 due to the heat generated by the rotor 11 can be further suppressed.

[0074] Furthermore, in the electric motor 1 of this embodiment, the rotation output part 12o of the rotating shaft 12 is provided at the axial end opposite to the side where the sensor unit 45 is arranged, and the rotation output part 12o protrudes outside the housing 13. Therefore, when a large load is input to the rotation output part 12o along the axial direction, for example when the motorcycle falls over, the rotor 11 comes into contact with the wall part 39, thereby suppressing excessive axial displacement of the rotating shaft 12. In the electric motor 1 of this embodiment shown in Fig. 3, the axial separation width between the rotor 11 and the wall portion 39 is set to be sufficiently larger than the axial separation width between the rotating shaft 12 and the sensor unit 45, but it is also possible to make the separation width between the rotating shaft 12 and the sensor unit 45 smaller than the separation width between the rotor 11 and the wall portion 39. In this case, when a large load is input to the rotation output portion 12o along the axial direction, the rotor 11 abuts against the wall portion 39, thereby preventing the rotating shaft 12 from interfering with the sensor unit. In addition, the abutment between the rotor 11 and the wall portion 39 can also prevent an excessive load from being input to the bearings 22F, 22R.

[0075] 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 of 12 split cores 30, but the number of split cores 30 constituting the stator 10 may be other than 12. The stator 10 may be formed of a single annular core instead of the multiple split cores 30. In this case, the insulator may have a continuous, integral structure.

[0076] In the above embodiment, the wall portion 39 is formed by the protruding pieces 37 protruding from the insulators 32 and the busbar unit 50 fixed to the protruding pieces 37, but the configuration of the wall portion 39 is not limited to this. For example, the wall portion 39 may be formed only by the protruding pieces 37. In this case, the protruding pieces 37 may be in close contact with adjacent ones in the circumferential direction with no gaps, so that the entire wall portion 39 has an annular shape. Furthermore, the wall portion 39 may be formed by an annular block separate from the insulator 32 and the bus bar unit 50. [Explanation of symbols]

[0077] 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, 2 9...cut-and-raised piece, 30...split core, 31...core portion, 31a...core back split piece, 31b...teeth, 32...insulator, 32b...split block, 33...coil, 34...stator core, 35...surrounding portion, 36i...inner flange portion, 36o...outer flange portion, 37...projecting piece, 38...recess, 39...wall portion, 40...thermistor accommodating portion, 41...thermistor, 42...leaf spring, 43s, 43e... Coil fitting groove, 44...engagement recess, 45...sensor unit, 46...sensor board, 47...sensor connector, 48...sensor harness, 49...cover member, 50...busbar unit, 51U, 51V, 51W...busbar, 51Ua, 51Va, 51Wa...busbar main body, 51Ub, 51Vb, 51Wb...busbar terminal, 51Ub1, 51Vb1, 51Wb1...terminal base, 51Ub2, 51Vb 2,51Wb2...terminal connection portion, 52...drive connector, 53...resin block, 54s...connection portion for starting line, 54e...connection portion for ending line, 55...block main body portion, 56...inner flange portion, 57r...step portion, 58...reinforcing rib, 59...adhesive filling port, 60...projection portion, 61...locking protrusion, 62...boss portion, 63...adhesive, TU,TV,TW...power terminal, o...axis center, Wf...front wheel, Wr...rear wheel.

Claims

1. An annular stator; a rotor having a rotation axis and rotatably disposed radially inside the stator; a sensor unit that is disposed opposite to an end face on one end side in an axial direction of the rotating shaft and has a rotation sensor that detects rotation of the rotating shaft and a sensor board on which the rotation sensor is mounted, The stator includes: a stator core having a plurality of teeth arranged along a circumferential direction of the stator and protruding radially inward; an insulator attached to an outer periphery of each of the teeth; a coil wound around each of the teeth via the insulator, An electric motor characterized in that a wall portion is provided at the axial end of the insulator on the same side as the side on which the sensor unit is arranged, between the rotor and the sensor unit, and protrudes radially inward beyond the outer circumferential surface of the rotor.

2. 2. The electric motor according to claim 1, wherein the wall portion includes a protruding piece that protrudes radially inward beyond an outer circumferential surface of the rotor from the axial end of each of the insulators.

3. 3. The electric motor according to claim 2, wherein the wall portion includes an annular block fixed to the plurality of protruding pieces and disposed at a position where at least a portion of the annular block axially overlaps with an outer circumferential edge portion of the rotor.

4. 4. The electric motor according to claim 3, wherein the annular block is configured as a bus bar unit in which a plurality of bus bars are embedded in an insulating resin.

5. the busbar unit has a plurality of bosses protruding in an axial direction so as to face the respective protruding pieces of the insulator, each of the protruding pieces of the insulator is provided with a recess into which the corresponding boss portion of the busbar unit is inserted; 5. The electric motor according to claim 4, wherein each of the bosses is fixed to the protruding piece by an adhesive that fills the corresponding recess when the boss is inserted into the corresponding recess.

6. the busbar unit is arranged such that a plate thickness direction of each of the busbars is oriented in an axial direction of the rotation shaft, and the plurality of busbars are arranged in series in the axial direction, 5. The electric motor according to claim 4, wherein the power supply terminals connected to the respective bus bars protrude in a direction substantially perpendicular to the axial direction in an axial extension region of the bus bars.

7. The electric motor according to claim 1 , wherein the wall portion protrudes radially inward to a position where, when viewed in the axial direction, the wall portion at least partially overlaps with a permanent magnet arranged on the rotor.

8. 2. The electric motor according to claim 1, wherein the rotary shaft has an axial end portion on a side opposite to a side on which the sensor unit is disposed, the axial end portion protruding to the outside as a rotary output portion.

Images