WINDING DEVICE AND MOTOR

Provided are a winding device and a motor A nozzle that feeds out a coil has: a nozzle hole from which the coil is fed out; an inner-diameter round chamfered part formed on an opening edge of a tip of the nozzle; an outer-diameter round chamfered part formed on the outer peripheral edge of the tip of the nozzle. When the wire diameter of the coil is defined as Φc, the inner diameter of the nozzle hole is defined as Φin, the radius of curvature of the inner-diameter round chamfered part is defined as Rin, and the radius of curvature of the outer-diameter round chamfered part is defined as Rout, they satisfy 1.2Φc≤Φin≤1.4Φc, 0.5Φc≤Rin≤Φc, and 0.25Φc≤Rout≤0.5Φc.

TECHNICAL FIELD

The disclosure relates to a winding device and a motor.

RELATED ART

Some motors include a stator having multiple teeth around which a coil is wound, and a rotor rotatably provided with respect to the stator. The winding device that winds the coil around the teeth includes a flyer having a nozzle for feeding the coil and a base for supporting the stator. Then, when winding the coil around the teeth, the base is rotated or moved up and down, and the flyer is moved. As a result, the relative position between the stator and the flyer changes. That is, a nozzle is inserted from a slot between adjacent teeth, and the nozzle moves around the teeth while feeding out a coil. As a result, the coil is wound around the teeth.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

By the way, when winding the coil around the teeth, the coil drawn out from the nozzle is greatly bent with the end of the nozzle as a fulcrum. At this time, if the pulling force of the coil is large, an unreasonable bending stress is applied to the coil, which may damage the coil.

In order to suppress the bending stress, it is conceivable to increase the size of the nozzle to reduce the bending stress applied to the coil. However, if the nozzle is simply enlarged in this way, the motor may be enlarged or the motor characteristics may be deteriorated, and, for example, it is necessary to increase the slot width between the teeth.

Therefore, the disclosure provides a winding device and a motor which can prevent damage on a coil during winding work and prevent an increase in size and a decrease in motor property.

Solution to Problem

In view of the above problems, a winding device according to the disclosure is a winding device for winding a coil around a tooth. The winding device includes a nozzle that feeds out the coil. The nozzle includes: a nozzle hole through which the coil is fed out; an inner-diameter round chamfered part formed on an opening edge of the nozzle hole on a side where the coil is fed out; and an outer-diameter round chamfered part formed on an outer peripheral edge at an end on the side where the coil is fed out. When a wire diameter of the coil is defined as Φc, an inner diameter of the nozzle hole is defined as Φin, a radius of curvature of the inner-diameter round chamfered part is defined as Rin, and a radius of curvature of the outer-diameter round chamfered part is defined as Rout, each of Φc, Φin, Rin, and Rout satisfies:

0.5Φc≤Rin≤Φc, and

A motor according to the disclosure is a motor in which a coil is wound by the winding device as described above. The motor includes: a stator having a core part in a tubular shape, and the tooth that protrudes inward in a radial direction from an inner peripheral surface of the core part and around which the coil is wound; and a rotor provided inside the stator in the radial direction and rotating around a rotation axis. The rotor includes: a shaft that rotates around the rotation axis; a rotor core that is supported by the shaft and rotates with the rotation axis as a radial center; a magnet disposed on an outer peripheral surface of the rotor core; and a protrusion that protrudes outward in the radial direction between the magnets adjacent to each other in a circumferential direction of the outer peripheral surface of the rotor core.

In the above configuration, the core part may be formed in a polygonal shape when viewed from a direction of the rotation axis, and the inner peripheral surface of the core part may be formed flat so that a wall thickness of one side of the core part is uniform.

In the above configuration, the wire diameter Φc may satisfy 0.3 mm≤Φc≤1.5 mm.

In the above configuration, the tooth may include: a tooth body that protrudes inward in the radial direction from the inner peripheral surface of the core part; and a collar that extends along a circumferential direction from a radial inner end of the tooth body. When a width in the circumferential direction at a tooth opening between the collars adjacent to each other in the circumferential direction is defined as Wt, the width Wt and the wire diameter Φc may satisfy 3.83≤Wt/Φc≤6.73.

Effects of Invention

According to the disclosure, since the bending stress of the coil fed out from the nozzle may be reduced, damage to the coil during the winding work may be prevented. Further, since it is not necessary to unnecessarily increase the size of the nozzle, it is possible to prevent the motor from becoming large and the motor characteristics from deteriorating.

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 brushless motor1.FIG.2is a cross-sectional view taken along the line A-A ofFIG.1.

The brushless motor1is, for example, a drive source for a sunroof mounted on a vehicle.

As shown inFIGS.1and2, the brushless motor1includes a motor part (motor)2, a deceleration part3that decelerates and outputs the rotation of the motor part2, and a controller part4that controls the drive of the motor part2.

The motor part2includes a motor case5, a stator8housed in the motor case5, and a rotor9provided inside the stator8in the radial direction and provided rotatably with respect to the stator8. The motor part2is a so-called brushless motor that does not require a brush to supply electric power to the stator8.

In the following description, the rotation axis C1direction of the rotor9is simply referred to as the axial direction, the rotation direction of the rotor9is referred to as the circumferential direction, and the radial direction orthogonal to the axial direction and the circumferential direction is simply referred to as the radial direction.

The motor case5is made of a material having good heat dissipation property such as aluminum die casting. 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 tube.

The outer shape of the first motor case6is formed, for example, in a bottomed polygonal tubular shape with the second motor case7side open. The first motor case6is integrally molded with a gear case40so that the end part10on the deceleration part3side is joined to the gear case40of the deceleration portion3. A through hole10athrough which a shaft31of the rotor9may be inserted is formed at substantially the center of the end part10in the radial direction. Further, an edge part16for joining the second motor case7is formed in an opening6aon the second motor case7side in the first motor case6.

The outer shape of the second motor case7is formed, for example, into a regular hexagon with rounded corners when viewed from the axial direction. That is, the peripheral wall of the second motor case7has six corner parts7A and flat parts7B, respectively. The second motor case7is formed in a bottomed tubular shape with the first motor case6side open. An outer flange part17protruding outward in the radial direction is formed in the opening7aon the first motor case6side in the second motor case7.

The motor case5has an internal space by abutting the edge part16of the first motor case6and the outer flange part17of the second motor case7. The stator8is disposed in the internal space of the motor case5so that a part of a coil24(to be described later) is housed inside the first motor case6, and a stator core20(to be described later) is fitted inside the second motor case7.

FIG.3is a plan view of the stator8and the rotor9as viewed from the axial direction.

As shown inFIGS.2and3, the stator8has a stator core20in which a tubular core part21and multiple (for example, six in this embodiment) teeth22protruding radially inward from an inner peripheral surface21aof the core part21are integrally formed.

The stator core20is formed by stacking multiple metal plates in the axial direction. The stator core20is not limited to the case of being formed by multiple metal plates stacked in the axial direction, and may be formed, for example, by pressure molding soft magnetic powder.

The core part21is formed in a tubular shape of regular hexagon with rounded corners when viewed from the axial direction to be fitted inside the second motor case7. That is, the core part21has six corner parts20A and flat parts20B, respectively. The flat part20B is formed to have a uniform wall thickness so that the inner peripheral surface21aand the outer peripheral surface21bare parallel to each other. The flat part20B corresponds to one side in the claims.

The multiple teeth22protrude from the center of each flat part20B of the core part21in the circumferential direction toward the inside in the radial direction.

The tooth22includes an integrally molded tooth body22aand a pair of collars22b.The tooth body22aprotrudes radially inward along the radial direction from the inner peripheral surface of the core part21. The collar22bextends along the circumferential direction from the radial inner end of the tooth body22a.The collar22bis formed to extend outward in the circumferential direction from the tooth body22a.Then, a slot19is formed between the teeth22adjacent to each other in the circumferential direction. In the following description, the space between the collars22badjacent to each other in the circumferential direction in the slot19is referred to as a tooth opening19a,and the width of the tooth opening19ain the circumferential direction, that is, the width between the adjacent collars22bin the circumferential direction is referred to as a tooth opening width Wt.

The inner peripheral surface of the core part21and the teeth22are covered with a resin insulator23. The coil24is mounted to be wound around each tooth22from the surface of the insulator23. Each coil24generates a magnetic field for rotating the rotor9by supplying power from the controller part4.

The rotor9is rotatably provided inside the stator8in the radial direction via a minute gap. The rotor9includes a shaft31, a rotor core32, and four permanent magnets33. As described above, in the motor part2, for example, the ratio of the number of magnetic poles of the permanent magnets33to the number of slots19(teeth22) is 4:6.

The axis of the shaft31coincides with the rotation axis C1of the rotor9. The shaft31rotates around the rotation axis C1. The shaft31is integrally molded with a worm shaft44(seeFIG.2) that configures the deceleration part3.

The rotor core32is fixed to be fitted to the outside of the shaft31. The outer shape of the rotor core32is formed in a columnar shape with the shaft31as the rotation axis C1.

The rotor core32is formed by stacking multiple metal plates in the axial direction. The rotor core32is not limited to the case of being formed by multiple metal plates stacked in the axial direction, and may be formed, for example, by pressure molding soft magnetic powder.

Further, a through hole32apenetrating in the axial direction is formed at the center of the rotor core32in the radial direction. The shaft31is press-fitted into the through hole32a.The shaft31may be relatively inserted into the through hole32aso that the rotor core32is fitted to the outside of the shaft31, and the shaft31and the rotor core32may be fixed by an adhesive or the like.

In the rotor core32, the arc center of the inner peripheral surface (that is, the inner peripheral surface of the through hole32a) on the inner side in the radial direction and the arc center on the outer peripheral surface32bon the outer side in the radial direction coincide with the position of the rotation axis C1of the shaft31.

Further, four protrusions35are provided on the outer peripheral surface32bof the rotor core32at equal intervals in the circumferential direction. The protrusion35is formed to protrude outward in the radial direction and extend over the entire axial direction of the rotor core32.

Further, the protrusion35is formed so that two side surfaces35afacing each other in the circumferential direction are parallel to the protruding direction. That is, the protrusion35is formed so that the width dimension in the circumferential direction is uniform in the protruding direction.

Further, round chamfered parts35bare formed at the corners on both sides in the circumferential direction on the outer side of the protrusion35in the protruding direction.

On the outer peripheral surface32bof the rotor core32formed in this way, the space between the two protrusions35adjacent to each other in the circumferential direction is configured as a magnet accommodating part36, respectively.

That is, the rotor9is a surface permanent magnet (SPM) type rotor having field permanent magnets33on the outer peripheral surface32bof the rotor core32, and is an inset-type rotor having protrusions35protruding radially outward from the rotor core32between the permanent magnets33arranged in the circumferential direction.

The four permanent magnets33are disposed in the four magnet accommodating parts36provided on the outer peripheral surface32bof the rotor core32. Each permanent magnet33is fixed to the rotor core32in the magnet accommodating part36, for example, with an adhesive or the like.

The permanent magnet33is, for example, a ferrite magnet, a neodymium bond magnet, a neodymium sintered magnet, or the like.

The permanent magnet33is magnetized so that the orientation of the magnetism (magnetic field) is parallel in the thickness direction. That is, the orientation of the permanent magnet33is a parallel orientation in which the easy magnetization direction is parallel to the radial direction in the central part of the permanent magnet33.

The permanent magnets33adjacent to each other in the circumferential direction are disposed so that their magnetization directions are opposite to each other. The four permanent magnets33are disposed so that the magnetic poles are alternated in the circumferential direction. That is, the permanent magnet33having the N pole on the outer peripheral side and the permanent magnet33having the S pole on the outer peripheral side are disposed to be adjacent to each other in the circumferential direction. As a result, the protrusion35of the rotor core32disposed between the permanent magnets33adjacent to each other in the circumferential direction is located at the boundary (pole boundary) of the magnetic poles.

With reference back toFIGS.1and2, the deceleration part3includes a gear case40to which the motor case5is attached, and a worm deceleration mechanism41housed in the gear case40.

The gear case40is made of a material having good heat dissipation property such as aluminum die casting. The outer shape of the gear case40is formed in a box shape, for example. The gear case40has a gear accommodating part42for accommodating the worm deceleration mechanism41inside. Further, in an end part40aon the motor part2side of the gear case40, an opening43through which the through hole10aof the first motor case6and the gear accommodating part42are passed through is formed in the part where the first motor case6is integrally molded.

Further, a guide plate49is provided on a side surface40borthogonal to the end part40aof the gear case40. The guide plate49is provided to rotatably support an output shaft48of the worm deceleration mechanism41.

The worm deceleration mechanism41housed in the gear accommodating part42is configured by a worm shaft44and a worm wheel45meshed with the worm shaft44.

The worm shaft44is disposed coaxially with the shaft31of the motor part2(on the rotation axis C1). Both ends of the worm shaft44are rotatably supported by bearings46and47provided in the gear case40. The end of the worm shaft44on the motor part2side protrudes through the bearing46to the opening43of the gear case40. The end of the protruding worm shaft44and the end of the shaft31of the motor part2are joined, and the worm shaft44and the shaft31are integrated. The worm shaft44and the shaft31may be integrally formed by forming a worm shaft part and a rotation shaft part from one base material.

The worm wheel45is provided with an output shaft48at the center of the worm wheel45in the radial direction. The output shaft48is disposed coaxially with the rotation axis direction of the worm wheel45. The output shaft48is connected to a gear part50protruding to the outside of the gear case40via the guide plate49of the gear case40. The gear part50is connected to an electrical component (not shown).

Further, the worm shaft44is provided with a rotation position detection part60for detecting the rotation position of the worm shaft44. The rotation position detection part60is connected to the controller part4.

The controller part4that controls the drive of the motor part2has a controller board62on which a magnetic detection element or the like is mounted. The controller board62is disposed in the through hole10aof the first motor case6.

The controller board62is a so-called epoxy board on which multiple conductive patterns (not shown) are formed. The end part of the coil24drawn from the stator core20of the motor part2is connected to the controller board62, and a terminal11provided in the gear case40is electrically connected to the controller board62. Further, in addition to the magnetic detection element, a power module (not shown) including a switching element such as a field effect transistor (FET) that controls the current supplied to the coil24is mounted on the controller board62. Further, a capacitor (not shown) or the like that smooths the voltage applied to the controller board62is mounted on the controller board62.

The terminal11is formed to be able to fit with a connector extending from an external power supply (not shown). Then, the controller board62is electrically connected to the terminal11. As a result, the electric power of the external power supply is supplied to the controller board62.

Next, the operation of the brushless motor1will be described.

In the brushless motor1, the electric power supplied to the controller board62via the terminal11is selectively supplied to each coil24of the motor part2via a power module (not shown).

Then, the current flowing through each coil24forms a predetermined interlinkage magnetic flux on the stator8(teeth22). This interlinkage magnetic flux generates a magnetic attractive force or a repulsive force (magnet torque) with the effective magnetic flux formed by the permanent magnets33of the rotor9.

Further, the protrusions35of the rotor core32generate a reluctance torque that rotates the rotor core32so as to make the protruding direction in a direction in which the interlinkage magnetic flux from the stator8(teeth22) easily flows, and to reduce the magnetic resistance (reluctance) of the magnetic path of the interlinkage magnetic flux.

These magnet torques and reluctance torques continuously rotate the rotor9. The rotation of the rotor9is transmitted to the worm shaft44integrated with the shaft31, and further transmitted to the worm wheel45meshed with the worm shaft44. Then, the rotation of the worm wheel45is transmitted to the output shaft48connected to the worm wheel45, and the output shaft48drives a desired electrical component.

Further, the detection signal of the rotation position of the worm wheel45detected by the magnetic detection element mounted on the controller board62and the rotation position detection part60is output to an external device (not shown). The external device (not shown) is a software function part that functions by executing a predetermined program by a processor such as a central processing unit (CPU). The software function part is an electronic control unit (ECU) including a processor such as a CPU, a read only memory (ROM) for storing a program, a random access memory (RAM) for temporarily storing data, and an electronic circuit such as a timer.

Further, at least a part of the external device (not shown) may be an integrated circuit such as a large scale integration (LSI). The external device (not shown) controls the switching timing of the switching element or the like of the power module (not shown) based on the rotation position detection signal of the worm wheel45, and controls the drive of the motor part2. The output of the drive signal of the power module and the drive control of the motor part2may be executed by the controller part4instead of the external device (not shown).

Next, a winding device70and a method of winding the coil24around the stator core20using the winding device70will be described with reference toFIGS.4to7.

FIG.4is an illustration view showing a method of winding the coil24around the stator core20using the winding device70.

As shown inFIG.4, the winding device70has a nozzle71for feeding out the coil24. The nozzle71is formed in a cylindrical shape. The tip71aon the side where the coil24of the nozzle71is fed out is directed toward the slot19, and the nozzle71is inserted into the slot19through the tooth opening19a.Then, while the nozzle71moves around the tooth22, the coil24is fed out from the nozzle71, and the coil24is wound around the tooth22.

Further, the nozzle71repeats reciprocating movement along the radial direction, and winds the coil24on the tooth22to be disposed along the radial direction. More specifically, when the coil24is wound while moving in the direction of pulling out the nozzle71from the slot19(see the arrow Y1inFIG.4), the coil24is sequentially wound on the outer peripheral surface of the tooth body22afrom the base on the core part21side toward the collar22b.In addition, when the coil24is wound while moving in the direction of inserting the nozzle71toward the slot19(see the arrow Y2inFIG.4), the coil24is sequentially wound on the outer peripheral surface of the tooth body22afrom the collar22btoward the base on the core part21side. By winding the coil24on the teeth22in this way, the coil24is stacked on the bundle, and the winding work of the coil24is completed.

Here, the core part21of the stator core20is formed in a tubular shape of regular hexagon with rounded corners when viewed from the axial direction, and has six corner parts20A and flat parts20B, respectively. The flat part20B is formed to have a uniform wall thickness so that the inner peripheral surface21aand the outer peripheral surface21bare parallel to each other. Therefore, as shown inFIG.3, the space in the slot19may be increased (see the hatch part Hb inFIG.3) as compared with the case where the core part21is formed in a cylindrical shape (see reference numeral21eof the two-dot chain line inFIG.3). The space factor of the coil24may be reduced by this amount, and the nozzle71may be easily entered into the slot19.

Next, the details of the nozzle71will be described with reference toFIG.5.

FIG.5is a schematic view of the nozzle71.

As shown inFIG.5, the nozzle71has a nozzle hole72from which the coil24is fed, an inner-diameter round chamfered part73formed at the opening edge of the nozzle hole72on a tip71aside, and an outer-diameter round chamfered part74formed on the outer peripheral edge of the nozzle hole72on the tip71aside. Each of the round chamfered parts73and74has an arc cross-sectional shape along the axial direction of the nozzle71.

Here, when the wire diameter of the coil24is defined as Φc, the inner diameter of the nozzle hole72is defined as Φin, the radius of curvature of the inner-diameter round chamfered part73is defined as Rin, and the radius of curvature of the outer-diameter round diameter part74is defined as Rout, each of Φc, Φin, Rin, and Rout satisfy the following:

The wire diameter Φc of the coil24is a value excluding the film thickness of the insulating coating of the coil24.

This is because, regarding the equation (1), the inner diameter Φin of the nozzle hole72needs to be sufficiently wider than the wire diameter Φc of the coil24.

The equation (2) will be described.

First, the bending strength of the coil24will be described with reference toFIG.6.

FIG.6is a graph showing the change in the stress ratio to the coil24when the vertical axis is the stress ratio to the coil24[1/X] and the horizontal axis is the ratio of the bending curvature/wire diameter Φc of the coil24.

As shown inFIG.6, it may be confirmed that the larger the bending curvature of the coil24with respect to the wire diameter Φc, the smaller the stress ratio to the coil24. In addition, if the radius of curvature Rin of the inner-diameter round chamfered part73is made too large, the nozzle71becomes large and the tooth opening width Wt must be increased. Therefore, it is desirable that the ratio is in the vicinity of “1,” and the radius of curvature Rin of the inner-diameter round chamfered part73satisfies the above equation (2).

The equation (3) will be described.

Here, the nozzle71repeats reciprocating movement along the radial direction, and the coils24are wound around the tooth22to be disposed along the radial direction. Therefore, as shown inFIG.4, the coil24is always in slidable contact with the inner-diameter round chamfered part73of the nozzle71, but the coil24is in slidable contact with the outer-diameter round chamfered part74of the nozzle71only when the nozzle71is moved toward the slot19in the inserting direction (see the arrow Y2inFIG.4). That is, the frequency with which the coil24is in slidable contact with the outer-diameter round chamfered part74is ½ as compared with the frequency with which the coil24is in slidable contact with the inner-diameter round chamfered part73. Therefore, as shown in the equation (3), the radius of curvature Rout of the outer-diameter round chamfered part74is set to ½ of the radius of curvature Rin of the inner-diameter round chamfered part73.

In addition, it is desirable that the tooth opening width Wt and the space S between the nozzle71and the teeth opening19asatisfies the following:

By doing so, it is possible to avoid contact between the teeth22and the nozzle71.

FIG.7is a graph showing the change in the tooth opening width Wt/the wire diameter Φc of the coil24when the vertical axis is the tooth opening width Wt/the wire diameter Φc of the coil24and the horizontal axis is the wire diameter Φc of the coil24.

As shown inFIG.7, it is confirmed that it is desirable to set the wire diameter Φc of the coil24to satisfy

in the range from the lower limit value to the upper limit value of the above equations (1) to (4). When the wire diameter Φc of the coil24becomes smaller than 0.3 mm, the value of the tooth opening width Wt/the wire diameter Φc of the coil24increases sharply. Further, when the wire diameter Φc of the coil24becomes larger than 1.5 mm, it becomes difficult to actually bend the coil24. Therefore, the above equation (5) is used.

Further, from the graph shown inFIG.7, it is desirable that the tooth opening width Wt/the wire diameter Φc of the coil24satisfies the following:

By satisfying the above equation (6), the tooth opening width Wt may be sufficiently secured, so that the coil24may be prevented from being scratched or damaged.

As described above, the nozzle71in the winding device70is formed to satisfy the above equations (1) to (3). Therefore, the bending stress of the coil24fed out from the nozzle71may be reduced as much as possible, so that damage during the winding work of the coil24may be prevented. Further, since it is possible to prevent the nozzle71from being unnecessarily enlarged, it is possible to prevent the motor part2from being enlarged and the motor characteristics from being deteriorated.

Further, the motor part2includes the rotor core32having the protrusions35. Therefore, when rotating the rotor9, both the reluctance torque and the magnetic force (magnet torque) of the permanent magnets33may be used, and the torque of the motor part2may be effectively increased. Since the space factor of the coil24may be reduced by this amount, the working hours for winding the coil24may be reduced, and damage to the coil24may be suppressed.

Further, the core part21of the stator core20is formed in a tubular shape of regular hexagon with rounded corners when viewed from the axial direction, and has six corner parts20A and flat parts20B, respectively. The flat part20B is formed to have a uniform wall thickness so that the inner peripheral surface21aand the outer peripheral surface21bare parallel to each other. Therefore, as shown inFIG.3, the space in the slot19may be increased (see the hatch part inFIG.3) as compared with the case where the core part21is formed in a cylindrical shape (see the two-dot chain line inFIG.3). The space factor of the coil24may be reduced by this amount, and the nozzle71may be easily entered into the slot19. Therefore, the winding work of the coil24may be facilitated.

Further, it is desirable that the wire diameter Φc of the coil24satisfies the above equation (4). With this configuration, the shape (dimensions) of the nozzle71and the tooth opening width Wt may be made appropriate, and the enlargement of the motor part2and the deterioration of the motor characteristics may be reliably prevented.

Further, it is desirable that the tooth opening width Wt/the wire diameter Φc of the coil24satisfies the above equation (6). With this configuration, the tooth opening width Wt may be sufficiently secured, so that the coil24may be prevented from being scratched or damaged.

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 brushless motor1is assumed to be a drive source for a sunroof mounted on a vehicle. However, the disclosure is not limited to this, and for example, the brushless motor1may be a drive source for various electrical components mounted on a vehicle (for example, a power window, an electric seat, a wiper, and the like) or a drive source mounted on various devices other than the vehicle.

In the above-described embodiment, the case where the ratio of the number of magnetic poles of the permanent magnets33to the number of slots19(teeth22) in the motor part2is 4:6 has been described. However, the ratio is not limited to this, and the ratio between the number of magnetic poles of the permanent magnets33and the number of slots19(teeth22) may be set as desired.

REFERENCE SIGNS LIST