INSULATOR, STATOR AND ELECTRIC MOTOR

An insulator attached to a core body in an annular shape and multiple teeth protruding from the core body along a radial direction for insulating the teeth and a coil wound around the teeth includes: a tooth end surface covering part covering an axial end surface of the tooth. The tooth end surface covering part includes: an inclined part provided on a front surface of the tooth end surface covering part on a side opposite to the tooth and inclined such that its height from the axial end surface of the tooth gradually changes along the radial direction; and an inclined part parallel part and a tooth parallel part provided on a back surface of the tooth end surface covering part on the tooth side and concave in a direction away from the axial end surface of the tooth.

TECHNICAL FIELD

The disclosure relates to an insulator, a stator and an electric motor.

RELATED ART

An electric motor includes, for example, a stator wound with a coil, and a rotor provided rotatably with respect to the stator and having a permanent magnet. The stator is made of a magnetic material, and includes an annular core body (circular core part) and teeth (magnetic pole teeth) radially protruding from the core body. A coil is wound around the teeth on the insulator. The insulator is made of an insulating resin. The insulator provides insulation between the teeth and the coil.

Under such a configuration, when the coil is energized, a magnetic field is formed in the teeth. Magnetic attractive force and repulsive force are generated between this magnetic field and the permanent magnet, and the rotor is continuously rotated.

Here, the torque performance of the electric motor greatly affects the space factor of the coil for generating the magnetic field. Therefore, various techniques have been proposed to improve the space factor of the coil. For example, a technique is disclosed in which the insulator is inclined such that the height from the surface of the tooth varies in a constant direction between the tip and base of the tooth. With this configuration, when the coil is wound on the insulator, the coil is wound in a constant direction. Therefore, the coil may be wound with as little space as possible, and the space factor of the coil may be improved as much as possible.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

However, in the conventional technology described above, since the insulator is inclined so that the height from the surface of the tooth varies in a constant direction between the tip and base of the tooth, the thickness of the teeth also changes without being constant. For this reason, there is a problem that heat sink marks or the like may occur when the insulator is molded with resin, and the moldability of the insulator is deteriorated.

Accordingly, the disclosure provides an insulator capable of improving moldability, and a stator and an electric motor using this insulator.

Solution to Problem

In view of the above, an insulator according to the disclosure is an insulator attached to a core body in an annular shape and multiple teeth protruding from the core body along a radial direction for insulating the teeth and a coil wound around the teeth, and the insulator includes: a tooth end surface covering part covering an axial end surface of the tooth. The tooth end surface covering part includes: an inclined part provided on a surface of the tooth end surface covering part on a side opposite to the tooth and inclined such that its height from the axial end surface of the tooth gradually changes along the radial direction; and a concave part provided on a surface of the tooth end surface covering part on the tooth side and concave in a direction away from the axial end surface of the tooth.

Effects of Invention

According to the disclosure, it is possible to prevent an increase in the thickness of the inclined part of the insulator. Therefore, deterioration of moldability due to heat sink marks or the like may be suppressed when the insulator is resin-molded.

DESCRIPTION OF THE EMBODIMENTS

Next, an embodiment of the disclosure will be described with reference to the drawings.

FIG.1is a perspective view of a motor1with a speed reducer.FIG.2is a cross-sectional view taken along the line II-II ofFIG.1.

The motor1with a speed reducer is used, for example, as a drive source for a wiper device of a vehicle.

As shown inFIGS.1and2, the motor1with a speed reducer includes an electric motor2, a speed reduction part3that decelerates and outputs the rotation of the electric motor2, and a controller4that controls the drive of the electric motor2.

In the following description, in the case of simply saying the “axial direction,” it means a direction parallel to the central axis of a shaft31of the electric motor2(rotation axis C1of the electric motor2). In the case of simply saying the “circumferential direction,” it means the circumferential direction (rotation direction) of the shaft31. In the case of simply saying the “radial direction,” it means the radial direction of the shaft31perpendicular to the axial direction and the circumferential direction.

The electric motor2includes a motor case5, a cylindrical stator8housed in the motor case5, and a rotor9provided inside the stator8in the radial direction and provided rotatably with respect to the stator8. The electric motor2is a so-called brushless motor that does not require a brush to supply electric power to the stator8.

The motor case5is made of a material having good heat dissipation property such as an aluminum alloy. The motor case5includes a first motor case6and a second motor case7which are configured to be separable in the axial direction. The outer shapes of the first motor case6and the second motor case7are each formed into a bottomed cylindrical shape.

A bottom part10of the first motor case6is formed integrally with a gear case40of the speed reduction part3. A through hole10athrough which the shaft31of the electric motor2may be inserted is formed at the center of the bottom part10in the radial direction. Outer flange parts16and17protruding radially outward are formed in openings6aand7aof the first motor case6and the second motor case7, respectively. The outer flange parts16and17are butted against each other, and the first motor case6and the second motor case7are integrated with bolts25. The motor case5has an internal space closed by the first motor case6and the second motor case7, and a stator8and a rotor9are housed in this internal space.

The rotor9is rotatably provided inside the stator8in the radial direction via a minute gap. The rotor9includes the shaft31, a cylindrical rotor core32fitted and fixed to the shaft31, multiple magnets (not shown) attached to the outer periphery of the rotor core32, and a magnet cover32acovering the rotor core32from above the magnets.

The shaft31is integrally molded with a worm shaft44that configures the speed reduction part3. However, the disclosure is not limited thereto, and the worm shaft44may be formed separately from the shaft31and connected to the end of the shaft31. The shaft31and the worm shaft44are rotatably supported by the gear case40via bearings46and47. The shaft31and the worm shaft44rotate around the rotation axis C1. A ferrite magnet, for example, is used as the magnet. However, the disclosure is not limited thereto, and a neodymium bond magnet, a neodymium sintered magnet, or the like may be applied as the magnet.

The speed reduction part3includes a gear case40integrated with the motor case5and a worm reduction mechanism41housed in the gear case40. The gear case40is made of a metal material having good heat dissipation property such as an aluminum alloy. The gear case40is formed in a box shape having an opening40aon one side. The gear case40includes a gear housing part42for housing the worm reduction mechanism41inside. Further, in a side wall40bof the gear case40, an opening43is formed at a part where the first motor case6is integrally formed to communicate the through hole10aof the first motor case6and the gear housing part42.

A cylindrical bearing boss49protrudes from a bottom wall40cof the gear case40. The bearing boss49is for rotatably supporting an output shaft48of the worm reduction mechanism41, and a slide bearing (not shown) is disposed on the inner peripheral side. An O-ring (not shown) is attached to the inner peripheral surface of the tip of the bearing boss49. Multiple ribs52are provided protruding from the outer peripheral surface of the bearing boss49to ensure rigidity.

The worm reduction mechanism41housed in the gear housing part42is configured by a worm shaft44formed integrally with the shaft31of the rotor9and a worm wheel45meshing with the worm shaft44. The worm shaft44is rotatably supported by the gear case40via bearings46and47at both ends in the axial direction about the rotation axis C1. The output shaft48of the electric motor2is provided coaxially and integrally with the worm wheel45. The worm wheel45and the output shaft48are disposed such that their rotation axes are perpendicular to the rotation axis C1of the worm shaft44(the shaft31of the electric motor2). The output shaft48protrudes outside through the bearing boss49of the gear case40. A protruding tip of the output shaft48is formed with a spline48athat may be connected to an object to be driven by the motor.

The worm wheel45is also provided with a sensor magnet (not shown). The position of this sensor magnet is detected by a magnetic detection element50(to be described later) provided in the controller4. That is, the rotational position of the worm wheel45is detected by the magnetic detection element50of the controller4.

The controller4includes a controller board51on which the magnetic detection element50is mounted. The controller board51is disposed in the opening40aof the gear case40so that the magnetic detection element50faces the sensor magnet of the worm wheel45. The opening40aof the gear case40is closed with a cover53.

The controller board51is electrically connected to coils24of the stator8, which will be described later. Further, terminals of the connector11(seeFIG.1) provided on the cover53are electrically connected to the controller board51. In addition to the magnetic detection element50, a power module (not shown) including a switching element such as a field effect transistor (FET) for controlling the drive voltage supplied to the coils24, a capacitor (not shown) for smoothing the voltage and the like are mounted on the controller board51.

FIG.3is a perspective view of the stator8.FIG.4is a plan view of the stator8as viewed from the axial direction, showing a state in which a terminal holder85is removed. Moreover,FIG.4shows a part of the insulator26cut away.

As shown inFIGS.3and4, the stator8includes a cylindrical stator core20whose center axis coincides with the rotation axis C1, an insulator26attached to the stator core20, and multiple coils24having a three-phase (U-phase, V-phase, W-phase) structure wound around the stator core20from above the insulator26.

A terminal holder85is provided on the stator core20. The terminal holder85includes terminals86, a holder body87that holds the terminals86, and a cover part88that covers one end of the stator core20in the axial direction, which are integrally formed. The terminals86are connected to terminal parts24aof the coils24of each phase, and to connectors (not shown) extending from the controller board51.

The cover part88includes an annular end surface cover part88adisposed to face the stator core20in the axial direction, and an outer periphery cover part88bextending from the outer peripheral edge of the end surface cover part88atoward the stator core20side and covering the insulator26from the outside in the radial direction, which are integrally formed.

The holder body87is formed to rise from a part of the end surface cover part88atoward the side opposite to the stator core20. A cut-out part88cis formed in a part corresponding to the holder body87of the end surface cover part88aand the outer periphery cover part88b.

The holder body87is formed in a rectangular parallelepiped shape extending in the axial direction and the circumferential direction. A connector (not shown) extending from the controller board51is attached to the holder body87. The holder body87is formed with three terminal housing recesses87adisposed in the longitudinal direction when viewed from the axial direction. The terminals86are housed and held in these terminal housing recesses87a. Then, the terminals86and connectors (not shown) extending from the controller board51are connected.

The stator core20is formed by stacking multiple electromagnetic steel sheets20p. However, the disclosure is not limited thereto, and the stator core20may be formed by, for example, pressure-molding soft magnetic powder.

The stator core20includes a cylindrical core body21, multiple (six in this first embodiment) teeth22protruding radially inward from the inner peripheral surface of the core body21, and two fixing parts23integrally formed on the outer peripheral surface of the core body21. The tooth22includes a tooth body28protruding radially from the inner peripheral surface of the core body21and a collar part29integrally formed with a tooth tip part28a, which is radially inner end of the tooth body28opposite to the core body21. The coil24is wound around the tooth body28from above the insulator26.

The collar part29extends along the circumferential direction. The inner peripheral surface of the collar part29is formed along a circle centered on the rotation axis C1. Between the teeth22adjacent in the circumferential direction, dovetail groove-shaped slots27are formed by the inner peripheral surface of the core body21, the circumferential side surface of the tooth body28, and the outer peripheral surface of the collar part29when viewed in the axial direction.

The fixing part23protrudes radially outward from the outer peripheral surface of the core body21and are disposed at intervals of 180° in the circumferential direction. A bolt insertion hole23ais formed in the fixing part23so as to extend therethrough in the axial direction.

With such a configuration, the outer peripheral surface of the core body21is fitted to the inner peripheral surface of the first motor case6and housed therein. The stator core20is fastened and fixed to the first motor case6by inserting a tapping screw (not shown) into the bolt insertion hole23aof the fixing part23and screwing the tapping screw into the bottom part10of the first motor case6. The stator core20fixed in this way is covered with the second motor case7. Then, the second motor case7is fixed to the first motor case6.

First Embodiment

FIG.5is a perspective view of the insulator26.FIG.5shows the insulator26attached to the stator core20.FIG.6is a perspective view of a first insulator61in the insulator26.

The insulator26serves to provide insulation between the teeth22and the coils24, and is made of insulating resin.

As shown inFIGS.5and6, the insulator26is axially divided into two parts so as to be attached from both sides of the stator core20in the axial direction. That is, the insulator26includes a first insulator61attached from one axial side (upper side inFIG.5) of the stator core20and a second insulator62attached from the other axial side (lower side inFIG.5) of the stator core20.

In the following description, the side of the first insulator61will be referred to as the upper side, and the side of the second insulator62will be referred to as the lower side in order to facilitate understanding of the description.

The first insulator61includes a core body covering part63that covers the core body21and a tooth covering part64that covers the tooth22, which are integrally formed. The core body covering part63includes an annular core end surface covering part65covering the axial end surface of the core body21, a core side surface covering part66protruding downward from a lower surface65aof the core end surface covering part65, and a cylindrical outer wall part67protruding upward from an upper surface65bof the core end surface covering part65.

The core side surface covering part66is disposed on the inner peripheral edge of the core end surface covering part65. The core side surface covering part66covers the inner peripheral surface of the core body21. The outer wall part67is disposed near the outer peripheral edge of the core end surface covering part65. An outer periphery cover part88bof the terminal holder85is disposed radially outside the outer wall part67.

A pull-in slit68and a pull-out slit69are formed in the outer wall part67at positions corresponding to the respective tooth covering parts64.

The pull-in slit68is for pulling in the coil24from the radially outer side to the radially inner side of the outer wall part67. The pull-out slit69is for pulling out the coil24from the radially inner side to the radially outer side of the outer wall part67. The details of the pulling in or pulling out of the coil24through the slits68,69and the detailed positions of the slits68,69will be described later.

The core end surface covering part65and the outer wall part67are integrally formed with a coil pull-out part77at the base of the tooth covering part64A (hereinafter, this tooth covering part64A is referred to as a specific tooth covering part64A) that covers a specific tooth22A (with reference toFIG.4, hereinafter, this tooth22A is referred to as the specific tooth22A) among the multiple teeth22.

The coil pull-out part77is a part for pulling upward the terminal part24a(seeFIG.3) of the coil24of each phase. The terminal holder85is disposed such that the cut-out part88cof the terminal holder85fits into the coil pull-out part77. That is, the terminal86of the terminal holder85is disposed directly above the coil pull-out part77.

The coil pull-out part77has multiple (three, for example, because the coils24of the first embodiment have a three-phase structure) coil guide recesses78for separately regulating the pull-out parts of the terminal parts24aof the coils24of each phase. These coil guide recesses78are collectively disposed side by side in the circumferential direction. Each coil guide recess78is integrally formed with a coil holding claw78aprotruding in the circumferential direction. The terminal parts24aof the coils24of each phase are individually pulled out upward through the respective coil guide recesses78. The terminal parts24aof the pulled-out coils24of each phase are guided to the terminals86of the terminal holder85while being held by the coil holding claws78a, and are connected to the terminals86.

FIG.7is a view in the direction of the arrow VII ofFIG.5.FIG.8is a view in the direction of the arrow VIII ofFIG.6.FIG.9Ais a cross-sectional view taken along the line IXA-IXA ofFIG.7.FIG.9Bis a cross-sectional view taken along the line IXB-IXB ofFIG.7.FIG.9Cis a cross-sectional view taken along the line IXC-IXC ofFIG.7.

As shown inFIGS.5to9C, the tooth covering part64includes a tooth end surface covering part71extending from the core end surface covering part65along the plane direction of the core end surface covering part65and extending in the radial direction, a tooth side surface covering parts72protruding downward from both sides (two ends in the lateral direction) of the tooth end surface covering part71in the circumferential direction, a collar side surface covering part73protruding outward in the circumferential direction from the radially inner end of the tooth side surface covering part72, and an inner wall part74joined to the radially inner end of the tooth end surface covering part71and the upper end of the collar side surface covering part73and extending upward from the upper end of the collar side surface covering part73.

The tooth end surface covering part71covers the upper end of the tooth body28. Here, the surface of the tooth end surface covering part71opposite to the upper end of the tooth body28is defined as a front surface71a, and the surface facing the upper end of the tooth body28is defined as a back surface71b. Most of the front surface71aof the tooth end surface covering part71is formed with an inclined part75over the entire radial direction. The inclined part75is inclined such that the height from the axial end surface of the tooth body28gradually decreases radially outward. In this way, the circumferential width of the inclined part75gradually increases radially outward.

A pin contact recess (an example of a recess in the claims)76having a circular shape when viewed from the axial direction is formed radially inward on the front surface71aof the tooth end surface covering part71. The pin contact recess76is a part with which an ejector pin of a resin molding machine (not shown) is in contact during resin molding of the first insulator61. The pin contact recess76is formed parallel to the axial end surface of the tooth body28.

As for the detailed position of the pin contact recess76, a center76cof the pin contact recess76is located radially inside a radial center75cof the inclined part75. The pin contact recess76is formed so as to fit on the inclined part75. Since the pin contact recess76is disposed radially inward, the diameter is smaller than when it is disposed radially outward.

The back surface71bof the tooth end surface covering part71is formed with an inclined part parallel part95(concave part). The inclined part parallel part95is formed to correspond to the shape of the inclined part75. Therefore, the thickness T1of the tooth end surface covering part71is constant in the region where the inclined part parallel part95exists. The inclination angle θ1of such an inclined part75is smaller than 45°. The inclination angle θ1refers to the inclination angle with respect to the upper end (virtual plane Kp) of the tooth body28.

Furthermore, the tooth parallel part96(concave part) is formed on the back surface71bradially inward of the inclined part parallel part95. The tooth parallel part96is formed parallel to the axial end surface of the tooth body28. Therefore, the thickness T2of the tooth end surface covering part71gradually increases radially outward in the region where the tooth parallel part96exists. That is, T1<T2. In this way, the wall thickness of the connecting part of the tooth end surface covering part71with the inner wall part74is increased, and the strength of the inner wall part74may be increased. Therefore, even if a radially inward stress is applied to the inner wall part74due to the winding of the coil24, deformation of the inner wall part74may be suppressed.

Here, the boundary line BL between the inclined part parallel part95and the tooth parallel part96is disposed along a part of the outer periphery of the pin contact recess76when viewed from the axial direction. Further, the tooth parallel part96is disposed on the back surface71bin the region where the pin contact recess76exists. That is, the thickness T3of the tooth end surface covering part71is constant in the region where the pin contact recess76exists. Further, T1=T3is set.

A contact part97provided on the same plane as the lower surface65aof the core end surface covering part65is formed on the back surface71b. The contact part97is in contact with the tooth body28. In addition, the inclined part parallel part95and the tooth parallel part96are further apart from the tooth body28in the axial direction than the contact part97is. In other words, the inclined part parallel part95and the tooth parallel part96are recessed with respect to the contact part97.

The tooth side surface covering part72covers the circumferential side surface of the tooth body28of the tooth22. The collar side surface covering part73covers the outer peripheral surface of the collar part29of the tooth22.

The tooth side surface covering part72and the collar side surface covering part73, and the core side surface covering part66of the core body covering part63are continuously formed to form a cylindrical skirt part79protruding downward from the tooth end surface covering part71and the core end surface covering part65. That is, skirt part79is interposed in the slot27of the stator core20.

A tip part (an example of a skirt tip part in the claims79a, which is the lower end of the skirt part79, is formed to be oblique so that the protruding height from the tooth end surface covering part71and the core end surface covering part65gradually changes along the circumferential direction. A flat part79bparallel to the tooth end surface covering part71and the core end surface covering part65is formed at the tip part79aof the skirt part79where the protruding height is the lowest.

Further, a parting line PL parallel to the tooth side surface covering part72and the collar side surface covering part73is set in the skirt part79nearer to the tip part79athan the center in the vertical direction. The parting line PL is a part where an upper mold91and a lower mold92(seeFIG.12) of a mold90used when resin-molding the first insulator61are overlapped. In other words, the parting line PL is a line along which the mold90used for resin molding is divided.

A concave part81is formed on the inner side surface79cof the skirt part79(the side surface of the tooth side surface covering part72, the collar side surface covering part73, and the core side surface covering part66opposite to the stator core20) through a small stepped part80over the entirety from the parting line PL to the tip part79a. In this way, the thickness of the skirt part79is slightly thinner at the lower part than at the upper part across the parting line PL. By forming the small stepped part80on the parting line PL, even when the parting line PL is set in the middle of the side surface of the resin molded product (skirt part79), it is possible to suppress the occurrence of burrs at this parting line PL at the time of resin molding. In addition, the dimension of the small step part80is, for example, about 0.04 mm.

FIG.10is a view in the direction of the arrow X ofFIG.6.

As shown inFIGS.5,6, and10, a pair of press-fit protrusions82aand82bare formed on the outer side surface79dof the skirt part79(the side surface of the tooth side surface covering part72, the collar side surface covering part73, and the core side surface covering part66on the stator core20side) near the tooth side surface covering part72of the core side surface covering part66. The pair of press-fit protrusions82aand82bare disposed on two sides in the circumferential direction with the tooth covering part64interposed therebetween. These press-fit protrusions82aand82bare for press-fitting and mounting the first insulator61on the stator core20. The press-fit protrusions82aand82bmay prevent the first insulator61from coming off the stator core20.

The pair of press-fit protrusions82aand82bare disposed at equal intervals in the circumferential direction every other tooth covering part64, except for a part corresponding to the specific tooth22A (specific tooth covering part64A). In the first embodiment, since there are six teeth22(tooth covering parts64), a pair of press-fit protrusions82aand82bare disposed at locations corresponding to three tooth covering parts64disposed at equal intervals in the circumferential direction except for the specific tooth covering part64A.

FIG.11is a perspective view of the second insulator62.

As shown inFIGS.5and11, the basic configuration of the second insulator62is line-symmetrical with the first insulator61about the axial center (vertical center) of the stator core20. Therefore, in the following description, the same reference numerals as those of the first insulator61are assigned to the same configurations of the second insulator62as those of the first insulator61, and the description thereof is omitted.

The difference between the first insulator61and the second insulator62is that the outer wall part67of the first insulator61is formed with a pull-in slit68and a pull-out slit69, whereas the outer wall part83of the second insulator62is not formed with the pull-in slit68or the pull-out slit69.

Further, the tip part79aof the skirt part79of the second insulator62is formed along the inclination direction of the tip part79aof the skirt part79of the first insulator61. Therefore, when the first insulator61and the second insulator62are attached from both sides in the axial direction of the stator core20, a gap S (seeFIG.5) between the tip parts79aof the skirt parts79that face each other is constant.

<Action of Insulator During Resin Molding>

Next, based onFIG.12, the action of the insulator26(the first insulator61and the second insulator62) during resin molding will be described.

FIG.12is an illustration view comparing the mold90used for resin-molding the first insulator61and the second insulator62with a mold290of a comparative example.

A parting line PL parallel to the tooth side surface covering part72and the collar side surface covering part73is set on the skirt part79of each insulator61and62. Therefore, as shown inFIG.12, the parting line PL is perpendicular to the mold clamping and mold release direction Y1between the upper mold91and the lower mold92in the mold90. Therefore, when the mold90is clamped, no clamping force is applied to the upper mold91or the lower mold92in the direction perpendicular to the mold clamping and mold release direction Y1, and the positional deviation of the upper mold91or the lower mold92is prevented. Therefore, the resin molding accuracy of the insulator26is improved.

In contrast, for example, when the parting line PL is set on the skirt part79of each insulator61and62along the tip part79a, as in the mold290of the comparative example, the mold clamping between the upper mold291and the lower mold292and the parting line PL are oblique to the mold release direction Y21, not perpendicular thereto. Therefore, when the mold290is clamped, a clamping force is applied to the upper mold291and the lower mold292in a direction perpendicular to the mold release direction Y21, and the upper mold291and the lower mold292may be displaced. Therefore, the resin molding accuracy of the insulator26is lowered.

By the way, when measuring the molding accuracy of the insulator26, it is difficult to measure the skirt part79because the tip part79athereof is obliquely formed. That is, in measuring the skirt part79, the reference position is the lower surface65aof the core end surface covering part65, for example. In this case, it is easy to identify the tip of the skirt part79protruding from the lower surface65a, but it is difficult to identify the part where the protruding height of the skirt part79is lowest.

A more specific description will be given with reference to the enlarged part ofFIG.6. The enlarged part ofFIG.6is viewed from a direction perpendicular to the axial direction for the sake of clarity of description, and the scale is appropriately changed.

For example, when the skirt part79is measured with the lower surface65aof the core end surface covering part65as a reference using a three-dimensional measuring machine m or the like, the tip of the skirt part79is likely to come into contact with the probe Pr. In addition, since the probe Pr has a spherical shape, at the part where the protruding height of the skirt part79is the lowest, the probe Pr contacts a slightly higher inclined part than this point (see the contact point Pj inFIG.6), and it becomes an obstacle when the probe Pr comes into contact with the part of the skirt part79where the protruding height is the lowest. Therefore, it is difficult to reliably bring the probe Pr into contact with the part of the skirt part79where the protruding height is the lowest.

Here, in the first embodiment, the flat part79bis formed at the tip part79aof the skirt part79where the protruding height is the lowest. Therefore, it is possible to easily identify the part where the skirt part79has the lowest protruding height. Further, when measuring the skirt part79with the lower surface65aof the core end surface covering part65as a reference using, for example, a three-dimensional measuring machine m, the probe Pr may be reliably brought into contact with the part where the protruding height of the skirt part79is lowest. Therefore, the insulator26may be measured with high accuracy.

<Insulator Assembly and Action of the Insulator during Assembly>

Next, action of the insulator26during assembly will be described with reference toFIGS.6,10and13.

FIG.13is a plan view of a jig93used when assembling the first insulator61of the insulator26to the stator core20as viewed from the axial direction. The second insulator62is assembled to the stator core20in the same manner as the first insulator61using the same jig93as the first insulator61, so the description thereof will be omitted.

As shown inFIGS.6and13, when the first insulator61is assembled to the stator core20, the skirt part79of the first insulator61is axially above stator core20and directed downward (toward the stator core20side). In this state, the jig93presses the outer wall part67of the first insulator61from above the first insulator61.

The jig93is formed in a columnar shape to correspond to the shape of the first insulator61. The outer diameter of the jig93is slightly larger than the outer diameter of the core end surface covering part65of the first insulator61. A chamfered part93ais formed in the jig93at a position corresponding to the coil pull-out part77of the first insulator61. In this way, when the jig93presses the first insulator61, the jig93may be prevented from coming into contact with the coil pull-out part77, and the first insulator61may be stably pressed by the jig93.

When the jig93presses the first insulator61, the skirt part79is first inserted into the slot27of the stator core20. At this time, since the tip part79aof the skirt part79is formed obliquely, the tip part79aof the skirt part79is not inserted into the slot27all at once. That is, the skirt part79is gradually inserted into the slot27from the tip of the skirt part79. Therefore, the tip part79aof the skirt part79serves as a guide, and the skirt part79is smoothly inserted into the slot27.

When the jig93presses the first insulator61, the outer side surface79dof the skirt part79is fitted to the stator core20. At this time, the first insulator61is press-fitted into the stator core20by the press-fit protrusions82aand82bformed on the skirt part79.

Here, the chamfered part93ais formed in the jig93at a position corresponding to the coil pull-out part77of the first insulator61. Therefore, the jig93does not press the specific tooth covering part64A where the coil pull-out part77is disposed and the periphery of the specific tooth covering part64A.

In addition, the press-fit protrusions82aand82bare disposed at equal intervals in the circumferential direction every other tooth covering part64, except for the part corresponding to the specific tooth covering part64A. Therefore, the press-fit protrusions82aand82bare evenly pressed. In addition, slight deformation of the first insulator61that occurs when the press-fit protrusions82aand82bare pushed into the stator core20is evenly dispersed on the tooth covering part64where the press-fit protrusions82aand82bare not formed and on the periphery of this tooth covering part64. In this way, the first insulator61is reliably press-fitted into the stator core20and attached.

<Winding Method of Coil and Detailed Positions of Pull-In Slit and Pull-Out Slit>

Next, a winding method of the coil24wound from above the insulator26attached to the stator core20and the detailed positions of the pull-in slit68and the pull-out slit69formed in the first insulator61of the insulator26will be described based onFIGS.4and14to19.

First, as shown inFIG.4, as a method of winding the coil24, the coil24is wound around the tooth22from above the insulators61and62by a so-called concentrated winding method. More specifically, the coils24of each phase are wound in series on the teeth22of the corresponding phase while being routed over the core end surface covering part65of the first insulator61.

That is, for example, since the electric motor2of the first embodiment has a three-phase structure, the teeth22of the same phase are disposed every two teeth22in the circumferential direction. For example, since there are six teeth22in the first embodiment, the coil24of each phase is continuously wound around the two teeth22while being routed over the core end surface covering part65of the first insulator61.

At this time, the coil24routed over the core end surface covering part65of the first insulator61is pulled toward the tooth covering part64through the pull-in slit68of the first insulator61. Then, the coil24is wound around the tooth22from above the tooth covering part64.

After that, the coil24wound around the tooth covering part64(tooth22) is pulled out again onto the core end surface covering part65via the pull-out slit69of the first insulator61. Then, the coil is guided to the terminal86of the terminal holder85via the coil guide recess78and connected to the terminal86.

The coil24pulled into the pull-in slit68may be routed over the core end surface covering part65to straddle the base of the corresponding tooth covering part64(tooth22) (counterclockwise CCW inFIG.4). After that, it may be pulled into the tooth covering part64side through the pull-in slit68. Hereinafter, this case will be referred to as the case where the coil24is routed counterclockwise CCW.

Further, the coil24pulled into the pull-in slit68may be routed over the core end surface covering part65from the direction opposite to the corresponding tooth covering part64(tooth22) (clockwise CW inFIG.4). After that, it may be pulled into the tooth covering part64side through the pull-in slit68. Hereinafter, this case will be referred to as the case where the coil24is routed clockwise CW.

Next, the detailed position of the pull-in slit68will be described with reference toFIGS.14to17.

FIG.14is a plan view of the first insulator61viewed from the axial direction, showing a state in which the coil24is pulled into the pull-in slit68when the coil24is routed clockwise CW.FIG.15is a perspective view of the first insulator61showing a state in which the coil24is pulled into the pull-in slit68when the coil24is routed clockwise CW.FIG.16is a plan view of the first insulator61viewed from the axial direction, showing a state in which the coil24is pulled into the pull-in slit68when the coil24is routed counterclockwise CCW.FIG.17is a perspective view of the first insulator61showing a state in which the coil24is pulled into the pull-in slit68when the coil24is routed counterclockwise CCW.

As shown inFIGS.14to17, the pull-in slit68is disposed on a side surface covering part straight line L passing through the tooth side surface covering part72of the corresponding tooth covering part64when viewed from the axial direction. More specifically, when viewed from the axial direction, the first side68aand the second side68bfacing each other in the circumferential direction of the pull-in slit68are disposed on two sides of the side surface covering part straight line L.

Here, the position of the pull-in slit68is slightly different depending on the routing direction of the coil24pulled into the pull-in slit68.

As shown inFIG.14, the pull-in slit68into which the coil24routed clockwise CW is pulled is disposed so that its width W1between the side surface covering part straight line L and the first side68awhen viewed from the axial direction is smaller than the wire diameter D of the coil24.

Therefore, as shown inFIGS.14and15, the coil24that is routed clockwise CW is pulled in through the pull-in slit68to the tooth covering part64side, and then is wound on the tooth covering part64along the tooth side surface covering part72on the side surface covering part straight line L in a slightly folded manner. Therefore, the coil24is wound on the tooth covering part64at the base of the tooth22. The occurrence of a gap between the tooth covering part64and the coil24is suppressed as much as possible.

As shown inFIG.16, the pull-in slit68into which the coil24routed counterclockwise CCW is pulled is disposed so that its width W2between the side surface covering part straight line L and the second side68bwhen viewed from the axial direction is larger than the wire diameter D of the coil24.

Therefore, as shown inFIGS.16and17, the coil24that is routed counterclockwise CCW is pulled in through the pull-in slit68to the tooth covering part64side, and then is wound on the tooth covering part64along the tooth side surface covering part72on the side surface covering part straight line L in such a manner as to ride on the tooth end surface covering part71. Therefore, the coil24is wound on the tooth covering part64at the base of the tooth22. The occurrence of a gap between the tooth covering part64and the coil24is suppressed as much as possible.

Next, the detailed position of the pull-out slit69will be described with reference toFIGS.18and19.

FIG.18is a plan view of the first insulator61viewed from the axial direction, showing a state in which the coil24routed clockwise CW is pulled through the pull-in slit68to the tooth covering part64side and then pulled out through the pull-out slit69.FIG.19is a plan view of the first insulator61viewed from the axial direction, showing a state in which the coil24routed counterclockwise CCW is pulled in through the pull-in slit68to the tooth covering part64side, and then pulled out through the pull-out slit69.

As shown inFIG.18, the coil24that has been routed clockwise CW and wound through the pull-in slit68is pulled out radially outward through the pull-out slit69and then routed clockwise CW again.

As shown inFIG.19, the coil24that has been routed counterclockwise CCW and wound through the pull-in slit68is pulled out radially outward through the pull-out slit69and then routed counterclockwise CCW again.

Here, as shown inFIGS.18and19, the position of the pull-out slit69does not change whether the coil24is routed clockwise CW or counterclockwise CCW. That is, the pull-out slit69is disposed on the side opposite to the pull-in slit68across the circumferential center C2of the tooth covering part64(the tooth body28of the tooth22). In addition, the pull-in slit69is disposed in an area Ar between a first straight line Ld1passing through the circumferential center C2of the tooth covering part64and the rotation axis C1, and a second straight line Ld2passing through the circumferential end of the collar part29of the tooth22and the rotation axis C1. Therefore, when the coil24wound around the tooth22is pulled out radially outward through the pull-out slit69, there is no large gap between the pulled-out coil24and the wound coil24.

<Winding State of Coil and Action of Inclined Part>

Next, the winding state of the coil24and the action of the inclined parts75in the insulators61and62will be described with reference toFIGS.20,21A, and21B.

FIG.20is an illustration view showing the winding state of the coil24on the insulator26.FIG.20corresponds to a plan view of the first insulator61viewed from above.FIG.21Ais an illustration view of the inclination angle of the inclined part75.FIG.21Bis an illustration view of the inclination angle of a comparative example.

As shown inFIG.20, the coil24is spirally wound in order from the base side of the tooth22(the tooth covering part64) to the radially inner side.

At this time, as shown inFIG.21A, the inclined part75formed on the tooth end surface covering part71allows the coil24to slide down toward the base of the tooth22and be wound forward (see arrow Y1inFIG.21A). That is, the coil24is wound while being packed toward the base of the teeth22. Therefore, no unnecessary gap is formed between the wound coil24.

Moreover, the center76cof the pin contact recess76used when resin-molding the insulator26is located radially inside the radial center75cof the inclined part75. Further, the pin contact recess76is formed to fit on the inclined part75. Since the pin contact recess76is disposed radially inside, the diameter is smaller than when it is disposed radially outside. As a result, the coil24smoothly slides down toward the base of the tooth22along the inclined part75as compared with the case where the center76cof the pin contact recess76is located radially outward of the radial center75cof the inclined part75.

Here, the inclination angle θ1of the inclined part75is smaller than 45°. Further, Lk is defined as an inclined straight line that is inclined by 45° with respect to a vertical straight line Ls that passes through the center of the coil24and is parallel to the rotation axis C1. The contact point Sp of the later-wound coil24(hereinafter referred to as the later coil24) with respect to the earlier-wound coil24(hereinafter referred to as the earlier coil24) is located axially inside the inclined straight line Lk of the earlier coil24. Therefore, the later coil24does not ride over the earlier coil24.

For example, as shown inFIG.21B, when the inclination angle θ1′ of the inclined part75is greater than 45°, the contact point Sp′ of the later coil24with respect to the earlier coil24is located on the inclined straight line Lk of the coil24or axially outside the inclined straight line Lk. Therefore, the later coil24may ride over the earlier coil24. Therefore, by setting the inclination angle θ1of the inclined part75to be smaller than 45°, the wound coil24is prevented from being unwound.

Under such a configuration, interlinkage magnetic flux is formed in the stator core20when power is supplied to each coil24via the controller4. Magnetic attraction and repulsion are generated between this interlinkage magnetic flux and the magnet (not shown) of the rotor9, and the rotor9is continuously rotated.

When the rotor9is rotated, the worm shaft44integrated with the shaft31is rotated. Further, the worm wheel45meshed with the worm shaft44is rotated. Rotation of the worm wheel45is transmitted to the output shaft48connected to the worm wheel45. In this way, a desired electrical component connected to the output shaft48is driven.

As described above, in the above-described first embodiment, the inclined parts75are formed on the front surfaces71aof the tooth end surface covering parts71of the insulators61and62. The inclined part75is inclined such that the height from the axial end surface of the tooth body28gradually decreases radially outward. Further, the back surface71bof the tooth end surface covering part71is formed with the inclined part parallel part95and the tooth parallel part96. Since the inclined part parallel part95is formed parallel to the inclined part75, the thickness T1of the tooth end surface covering part71is constant in the region where the inclined part parallel part95exists. Furthermore, since the tooth parallel part96is formed parallel to the pin contact recess76, the thickness T3of the tooth end surface covering part71is constant in the region where the pin contact recess76exists. Therefore, the height of the inclined part75from the axial end surface of the tooth body28is formed to gradually decrease toward the radially outer side, and even if the pin contact recess76is formed parallel to the upper end of the tooth body28, the thickness of most of the tooth end surface covering parts71may be made constant. That is, it is possible to prevent an increase in the thickness of the inclined parts75of the insulators61and62. As a result, deterioration of moldability due to heat sink marks or the like may be suppressed when the insulators61and62are resin-molded. The resin molding accuracy of the insulators61and62may be improved.

Since the resin molding accuracy of the insulators61and62may be improved, it is possible to contribute to Goal 12 of Sustainable Development Goals (SDGs) led by the United Nations, “ensure sustainable consumption and production patterns.”

The teeth22radially protrude from the inner peripheral surface of the core body21. In contrast, the inclined part75is inclined such that the height from the axial end surface of the tooth body28gradually decreases radially outward. The coil24wound from above the insulator26starts winding from the base side of the teeth22. Therefore, the coil24is wound while being packed toward the base of the teeth22. It is possible to prevent unnecessary gaps from being formed between the wound coil24. Therefore, the space factor of the coil24may be reliably improved.

The inclination angle θ1of the inclined part75is smaller than 45°. Therefore, the contact point Sp of the later coil24with respect to the earlier coil24may be located axially inside the inclined straight line Lk of the earlier coil24. Therefore, it is possible to prevent the later coil24from riding over the earlier coil24, and prevent the unwinding of the coil24.

The tip part79aof the skirt part79formed on each insulator61and62is formed to be oblique so that the protruding height from the tooth end surface covering part71and the core end surface covering part65gradually changes along the circumferential direction. Therefore, when the skirt part79is inserted into the slot27of the stator core20(when the insulators61and62are attached to the core body21and the teeth22), the skirt part79may be gradually inserted into the slot27from the tip of the skirt part79. Therefore, the tip part79aof the skirt part79serves as a guide, and the insulators61and62of the stator core20may be easily attached.

Further, the flat part79bparallel to the tooth end surface covering part71and the core end surface covering part65is formed at the tip part79aof the skirt part79where the protruding height is the lowest. Therefore, it is possible to easily identify the part where the skirt part79has the lowest protruding height. Further, when measuring the skirt part79with the lower surface65aof the core end surface covering part65as a reference using, for example, a three-dimensional measuring machine m, the probe Pr may be reliably brought into contact with the part where the protruding height of the skirt part79is lowest. Therefore, the insulator26may be measured with high accuracy.

While the tip part79aof the skirt part79is formed obliquely, a parting line PL parallel to the tooth side surface covering part72and the collar side surface covering part73is set on the skirt part79. Therefore, the parting line PL may be perpendicular to the mold clamping and mold release direction Y1between the upper mold91and the lower mold92in the mold90. Therefore, when the mold90is clamped, no clamping force is applied to the upper mold91or the lower mold92in the direction perpendicular to the mold clamping and mold release direction Y1, and the positional deviation of the upper mold91or the lower mold92may be prevented. Therefore, the resin molding accuracy of the insulator26may be improved.

Further, the concave part81is formed on the inner side surface79cof the skirt part79(the side surface of the tooth side surface covering part72, the collar side surface covering part73, and the core side surface covering part66opposite to the stator core20) through the small stepped part80over the entirety from the parting line PL to the tip part79a. Therefore, even when the parting line PL is set in the middle of the side surface of the resin molded product (skirt part79), it is possible to suppress the occurrence of burrs at this parting line PL at the time of resin molding.

The core end surface covering part65and the outer wall part67are integrally formed with a coil pull-out part77collectively disposed at the base of the specific tooth22A (the specific tooth covering part64A). The pair of press-fit protrusions82aand82bfor press-fitting each insulator61and62into the stator core20are disposed at equal intervals in the circumferential direction every other tooth covering part64, except for a part corresponding to the specific tooth22A (specific tooth covering part64A).

By forming the press-fit protrusions82aand82b, the insulators61and62are press fitted when attached to the stator core20(core body21). Therefore, the insulators61and62are less likely to come off from the stator core20.

In addition, since the pair of press-fit protrusions82aand82bare disposed at equal intervals in the circumferential direction for every tooth covering part64, the jig93may evenly press the press-fit protrusions82aand82b. In addition, slight deformation of the first insulator61that occurs when the press-fit protrusions82aand82bare pushed into the stator core20(core body21) may be evenly dispersed on the tooth covering part64where the press-fit protrusions82aand82bare not formed and on the periphery of this tooth covering part64. As a result, distorted deformation of the insulators61and62may be suppressed.

Moreover, for example, when the insulators61and62are pressed using the jig93, the jig93is pressed while avoiding the coil pull-out part77, which is a part of the deformed part (seeFIG.13). Therefore, by forming the press-fit protrusions82aand82bwhile avoiding the specific tooth22A on which the coil pull-out part77is disposed, the press-fit protrusions82aand82bmay be evenly pressed by the jig93. Therefore, the insulators61and62may be reliably attached to the stator core20(core body21).

The center76cof the pin contact recess76used when resin-molding the insulator26is located radially inside the radial center75cof the inclined part75. Further, the pin contact recess76is formed to fit on the inclined part75. Since the pin contact recess76is disposed radially inside, the diameter is smaller than when it is disposed radially outside. As a result, the coil24smoothly slides down toward the base of the tooth22along the inclined part75as compared with the case where the center76cof the pin contact recess76is located radially outward of the radial center75cof the inclined part75. That is, when the coil24is moved in one direction along the inclined part75, it is possible to prevent the pin contact recess76from hindering the movement of the coil24. Therefore, the coil24may be disposed on the inclined part75without a gap.

The pull-in slit68into which the coil24routed clockwise CW is pulled is disposed so that its width W1between the side surface covering part straight line L and the first side68awhen viewed from the axial direction is smaller than the wire diameter D of the coil24. Therefore, the coil24that is routed clockwise CW is pulled in through the pull-in slit68to the tooth covering part64side, and then is wound on the tooth covering part64along the tooth side surface covering part72on the side surface covering part straight line L in a slightly folded manner. Therefore, the coil24is wound on the tooth covering part64at the base of the tooth22. The occurrence of a gap between the tooth covering part64and the coil24may be suppressed as much as possible. Therefore, the insulator26and the coil24may be brought into close contact with each other at the base of the tooth22, and the space factor of the coil24may be improved.

The pull-in slit68into which the coil24routed counterclockwise CCW is pulled is disposed so that its width W2between the side surface covering part straight line L and the second side68bwhen viewed from the axial direction is larger than the wire diameter D of the coil24. Therefore, the coil24that is routed counterclockwise CCW is pulled in through the pull-in slit68to the tooth covering part64side, and then is wound on the tooth covering part64along the tooth side surface covering part72on the side surface covering part straight line L in such a manner as to ride on the tooth end surface covering part71. Therefore, the coil24is wound on the tooth covering part64at the base of the tooth22. The occurrence of a gap between the tooth covering part64and the coil24may be suppressed as much as possible. Therefore, the insulator26and the coil24may be brought into close contact with each other at the base of the tooth22, and the space factor of the coil24may be improved.

The pull-in slit69is disposed in an area Ar between the first straight line Ld1passing through the circumferential center C2of the tooth covering part64and the rotation axis C1, and the second straight line Ld2passing through the circumferential end of the collar part29of the tooth22and the rotation axis C1. Therefore, when the coil24wound around the tooth22is pulled out radially outward through the pull-out slit69, it is possible to suppress a large gap between the pulled-out coil24and the wound coil24. Therefore, the coil24wound around the tooth22may be reliably wound, and the space factor of the coil24may be improved.

By improving the space factor of the coil24, the torque performance of the electric motor2may be improved. Therefore, energy consumption when the electric motor2is driven may be suppressed. Therefore, it is possible to contribute to Goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, “ensure access to affordable, reliable, sustainable and modern energy for all.”

Second Embodiment

Next, a second embodiment of the disclosure will be described based onFIGS.22and23. The same reference numerals are assigned to the same configurations as in the first embodiment.

FIG.22is a plan view of a tooth covering part264of a first insulator261according to the second embodiment as viewed from the axial direction.FIG.23is a cross-sectional view taken along the line XXIII-XXIII ofFIG.22.

The second embodiment has the same basic configuration as that of the above-described first embodiment, in that the stator8includes a cylindrical stator core20whose center axis coincides with the rotation axis C1, an insulator26attached to the stator core20, and multiple coils24having a three-phase (U-phase, V-phase, W-phase) structure wound around the stator core20from above the insulator26, and in that the insulator26includes a first insulator61attached from one axial side of the stator core20and a second insulator62attached from the other axial side of the stator core20.

As in the first embodiment described above, the basic configuration of the second insulator62in the second embodiment is line-symmetrical with the first insulator261about the axial center (vertical center) of the stator core20. Therefore, the second insulator62in the second embodiment has the same reference numerals as in the first embodiment, and the description thereof is omitted.

As shown inFIGS.22and23, the difference between the first embodiment described above and the second embodiment is that the shape of the tooth end surface covering part71in the first embodiment and the shape of the tooth end surface covering part271in the second embodiment are different.

More specifically, the front surface271aof the tooth end surface covering part271of the second embodiment is provided with an inclined part275aformed radially outward of a radial center271cof the tooth end surface covering part271and a non-inclined part275bformed radially inward of the radial center271cof the tooth end surface covering part271. The inclined part275ais inclined such that the height from the axial end surface of the tooth body28gradually decreases radially outward. The non-inclined part275bis formed parallel to the axial end surface of the tooth body28.

Further, a pin contact recess276is formed on the front surface271aof the tooth end surface covering part271. The pin contact recess276is a part with which an ejector pin of a resin molding machine (not shown) is in contact during resin molding of the first insulator61.

A center276cof the pin contact recess276is located slightly radially outward of a radial center271cof the tooth end surface covering part271. The diameter of the pin contact recess276is larger than the diameter of the pin contact recess76of the first embodiment.

Further, the back surface271bof the tooth end surface covering part271on the side of the tooth body28is provided with an inclined part parallel part295formed to correspond to the shape of the inclined part275a, a tooth parallel part296formed parallel to the axial end surface of the tooth body28, and a contact part297that contacts the axial end surface of the tooth body28. Therefore, the thickness T4of the inclined part275a, the thickness T5of the non-inclined part275b, and the thickness T6of the pin contact recess276are all constant. Furthermore, the thickness of the entire tooth end surface covering part71is constant. In addition, the inclination angle θ2of the inclined part275ais smaller than 45°.

Therefore, according to the above-described second embodiment, the inclined part275ahas the same effect as the above-described first embodiment. In addition, since the thickness of the entire tooth end surface covering part271is constant, deterioration of moldability due to heat sink marks or the like may be suppressed when the insulators261and62are resin-molded. The resin molding accuracy of the insulators261and62may be improved.

The disclosure is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the disclosure.

For example, in the above-described embodiment, the case where the motor1with a speed reducer is used, for example, as a drive source for a wiper device of a vehicle has been described. However, the disclosure is not limited thereto, and the motor1with a speed reducer may be applied as various drive devices. In addition, among the motors1with a speed reducer, only the electric motors2having the above configuration may be employed in various electric devices.

In the second embodiment described above, the case where the non-inclined part275bis formed parallel to the axial end surface of the tooth body28has been described. However, the disclosure is not limited thereto, and the non-inclined part275bmay be formed to be inclined at an angle smaller than the inclination angle θ2of the inclined part275a.

In the above-described embodiments, the case where the inclined parts75and275aare inclined such that the height from the axial end surface of the tooth body28gradually decreases radially outward has been described. However, the disclosure is not limited thereto, and the inclination direction of the inclined parts75and275amay be changed according to the direction in which the teeth22protrude. That is, when the teeth22protrude radially outward, the base of the teeth22are located radially inward from the tips of the teeth22. In such a case, the height of the inclined parts75and275afrom the axial end surface of the tooth body28may be inclined to gradually decrease radially inward.

In the above-described embodiments, the coil24of the stator8has a three-phase (U-phase, V-phase, W-phase) structure. However, the number of phases of the coil24is not limited to three.

REFERENCE SIGNS LIST