JP6950361B2 - motor - Google Patents

Description

The present invention relates to a motor.

Motors used in devices that require a position holding function, such as electric variable valve timing (electric VCT) devices, require a large cogging torque (detent torque). As a motor for improving the cogging torque, for example, in the one disclosed in Patent Document 1, a gap portion is provided inside or on the outer peripheral surface of the field magnet of the rotor so as to have a change in magnetic flux density in the circumferential direction within the magnetic pole range of the rotor. (Hole, groove, etc.) are provided. As a result, the cogging torque generated by the gap is superimposed on the basic cogging torque generated due to the switching of the magnetic poles of the rotor, so that the cogging torque is increased.

Japanese Unexamined Patent Publication No. 2015-146713

In a motor as described above, the cogging torque can be improved by the gap provided in the magnetic pole range of the rotor, but the present inventors have studied a configuration that can cope with a case where a larger cogging torque is required. Was there.

An object of the present invention is to provide a motor capable of improving cogging torque.

A motor that solves the above problems has a stator and a plurality of magnetic pole portions set along the circumferential direction on a surface facing the stator, and a plurality of gap portions for increasing cogging torque are partially provided in the circumferential direction. The plurality of gaps are the boundary gaps provided between the magnetic poles adjacent to each other in the circumferential direction, the number of poles of the rotor and the number of slots of the stator in the magnetic poles. It is configured to include an intrapolar void provided at a position corresponding to the cycle of the cogging torque obtained from the above, and the boundary void and the intrapolar void have the same shape when viewed from the axial direction. It has a shape .

According to this configuration, both the cogging torque generated by the boundary gap and the cogging torque generated by the intrapole gap can be superimposed on the basic cogging torque generated by the switching of the magnetic poles of the rotor, and as a result. , The cogging torque can be improved.

According to the configuration of this can be suitably improved cogging torque by the boundary gap portion and the in-electrode gap portion.

In the motor, the magnetization orientation of the magnets constituting the magnetic pole portion is set so as to be inclined toward the circumferential center line side of the magnetic pole portion toward the stator side.
According to this configuration, the magnetic flux can be suitably concentrated in the void portion in the pole, and as a result, the cogging torque can be further improved.

In the motor, the rotor is an embedded magnet type rotor in which magnets constituting the magnetic pole portion are embedded in the rotor core, and each of the boundary gap portion and the inner pole gap portion is formed in the rotor core. ing.

According to this configuration, it is possible to improve the cogging torque in the embedded magnet type rotor.
In the motor, the rotor is a surface magnet type rotor in which magnets constituting the magnetic pole portion are provided on the surface of the rotor core, and each of the boundary gap portion and the inner pole gap portion is formed in the magnet. Has been done.

According to this configuration, it is possible to improve the cogging torque in the surface magnet type rotor.

According to the motor of the present invention, the cogging torque can be improved.

It is sectional drawing of the motor of embodiment. It is a top view which shows the rotor of the same form partially. It is a top view which shows the rotor of a modification partially. It is a top view which shows the rotor of a modification partially. It is a top view which shows the rotor of a modification partially. It is a top view which shows the rotor of a modification partially.

Hereinafter, one embodiment of the motor will be described.
The motor 10 of the present embodiment shown in FIG. 1 is a brushless motor. The motor 10 includes an annular stator 12 fixed to the inner peripheral surface of the motor housing 11 and a rotor 14 arranged radially inside the stator 12 and having a rotating shaft 13.

The stator 12 has a cylindrical stator core 15, and the outer peripheral surface of the stator core 15 is fixed to the motor housing 11. A plurality of (12 in this embodiment) teeth 16 formed along the axial direction and arranged at equal pitches in the circumferential direction are formed inside the stator core 15 so as to extend inward in the radial direction. ing. Each tooth 16 is a T-shaped tooth, and its radial inner peripheral surface 16a is an arc surface extending in the axial direction from a concentric arc centered on the axis L of the rotating shaft 13.

A three-phase winding 17 is wound around each tooth 16 in a concentrated winding manner. Then, a three-phase power supply voltage is applied to the windings 17 of each phase to form a rotating magnetic field in the stator 12, and the rotor 14 fixed to the rotating shaft 13 arranged inside the stator 12 is rotated. There is.

The rotor 14 arranged inside the stator 12 includes a cylindrical rotor core 21 integrally rotatably fixed to the rotating shaft 13, and a plurality of magnets (8 magnets in the present embodiment) embedded inside the rotor core 21. It is configured as an embedded magnet type (IPM type) rotor including 22. The rotor core 21 is configured by laminating a plurality of electromagnetic steel sheets in the axial direction. Further, the rotating shaft 13 is rotatably supported by the motor housing 11 via a bearing (not shown).

The plurality of magnets 22 each constitute a plurality of magnetic pole portions 14p of the rotor 14 having different poles alternately in the circumferential direction. That is, the rotor 14 of the present embodiment is composed of eight poles. Further, the rotor 14 is a full magnet type rotor in which all the magnetic pole portions 14p thereof are composed of magnets 22. Each magnet 22 is made of, for example, a sintered magnet or a bond magnet (plastic magnet, rubber magnet, or the like) obtained by mixing magnet powder with a resin and molding and solidifying the magnet powder. The bonded magnet has a higher degree of freedom in shape than the sintered magnet, and can be formed with high dimensional accuracy. When the magnet 22 is a bond magnet, it is preferably composed of a rare earth magnet such as a samarium iron nitrogen (SmFeN) magnet, a samarium cobalt (SmCo) magnet, or a neodymium magnet. When the magnet 22 is a sintered magnet, it is preferably composed of a ferrite magnet, a samarium-cobalt (SmCo) magnet, a neodymium magnet, or other rare earth magnet.

As shown in FIG. 2, each magnet 22 has an arc shape that is convex inward in the radial direction in the axial direction. The magnetization orientation of each magnet 22 is set so as to be inclined toward the circumferential center line (magnetic pole center line Lp) of the corresponding magnetic pole portions 14p toward the outer side in the radial direction (stator 12 side). In addition, in each figure of FIG. 2 and FIGS. 3 to 6, the magnetization orientation of the magnet is indicated by an arrow.

Each magnetic pole portion 14p has its magnetic pole center line Lp (circumferential center line) set at equal intervals (45 ° intervals) in the circumferential direction and has an angular width (45 °) equal to each other in the circumferential direction. There is. That is, the boundary portions B between the north pole portion 14p and the south pole magnetic pole portion 14p are provided at intervals of 45 ° in the circumferential direction.

Each magnetic pole portion 14p has two groove portions, a first groove portion 23a and a second groove portion 23b, formed on the outer peripheral surface of the rotor core 21. Further, the rotor 14 has a third groove portion 23c formed at a position corresponding to the boundary portion B on the outer peripheral surface of the rotor core 21. The groove portions 23a, 23b, and 23c are formed linearly along the axial direction from one end to the other end of the outer peripheral surface of the rotor core 21 in the axial direction. Further, the cross-sectional shapes of the groove portions 23a, 23b, and 23c in the direction orthogonal to the axis are the same as each other, and in the present embodiment, they are arcuate.

As shown in FIG. 2, the first groove portion 23a and the second groove portion 23b are formed at positions shifted by the same angle on both sides in the circumferential direction with respect to the magnetic pole center line Lp, and have the same shape (same width). , At the same depth). That is, the first groove portion 23a and the second groove portion 23b are line-symmetrical with respect to the magnetic pole center line Lp.

The formation positions (angles from the magnetic pole center line Lp) of the groove portions 23a and 23b with respect to the magnetic pole center line Lp are set based on the period φ of the cogging torque generated by the motor 10. Specifically, the angle θ (opportunity angle) formed by the magnetic pole center line Lp and the circumferential center lines Lc of the groove portions 23a and 23b around the axis L of the rotating shaft 13 is 1/1 of the cogging torque cycle φ. It is set to 2.

Here, the period φ of the cogging torque is generally a value obtained by dividing 360 ° by the least common multiple of the number of poles of the rotor 14 (the number of magnetic poles 14p) and the number of teeth 16 of the stator 12 (the number of slots). That is, in the present embodiment, since the number of poles of the rotor 14 is 8 and the number of teeth 16 is 12, the least common multiple is 24, and the period φ of the cogging torque is 15 (= 360/24) °.

That is, in the present embodiment, the angle θ formed by the magnetic pole center line Lp and the circumferential center lines Lc of the groove portions 23a and 23b is 7.5 °, which is 1/2 of the cogging torque cycle φ (= 15 °). It is set. Therefore, the angle formed by each circumferential center line Lc of the first groove portion 23a and the second groove portion 23b with the axis L of the rotating shaft 13 as the center coincides with the period φ (= 15 °) of the cogging torque.

Further, the third groove portion 23c is formed to have the same shape (same width and same depth) as the first groove portion 23a and the second groove portion 23b. Further, as described above, the third groove portion 23c is provided at the boundary portion B between the magnetic pole portion 14p of the N pole and the magnetic pole portion 14p of the S pole adjacent to each other in the circumferential direction. That is, eight third groove portions 23c are provided at intervals of 45 ° in the circumferential direction of the rotor 14. As a result, the rotor 14 is provided with the first groove portions 23a, the second groove portions 23b, and the third groove portions 23c in this order at equal intervals (15 ° intervals in the present embodiment) in the circumferential direction, and these groove portions 23a, 23b, 23c are provided in this order. The interval in the circumferential direction coincides with the period φ of the cogging torque.

Next, the operation of this embodiment will be described.
When a three-phase power supply voltage is applied to the winding 17 of the stator 12 to form a rotating magnetic field, the rotor 14 rotates based on the rotating magnetic field. Then, when the power supply to the winding 17 is stopped, the rotating magnetic field disappears and the rotor 14 stops rotating. At this time, the rotor 14 stops at an angle position where it is in the most magnetically stable state with respect to the stator 12.

Here, since the first to third groove portions 23a, 23b, and 23c are formed on the outer peripheral surface of the rotor 14 (the outer peripheral surface of the rotor core 21), the change in magnetic flux density in the circumferential direction on the outer peripheral surface of the rotor 14 is the first. It is larger than before forming the 1st to 3rd groove portions 23a, 23b, 23c. As a result, the holding force (cogging torque) for returning the magnetic flux to a stable state is increased.

Further, where M is the least common multiple of the number of poles of the rotor 14 and the number of slots of the stator 12, the period φ of the cogging torque is φ = 360 ° / M, the magnetic pole center line Lp and the first and second groove portions 23a and 23b. The angle θ formed by the circumferential center line Lc is set to 1/2 of the period φ of the cogging torque. That is, the angle θ is set to θ = (1/2) · (360 ° / M). As a result, the basic cogging torque cycle φ caused by the switching of the magnetic poles of the rotor 14 and the cogging torque cycle generated by the first and second groove portions 23a and 23b are in phase with each other. Therefore, the cogging torque generated by the first and second groove portions 23a and 23b is superimposed on the basic cogging torque, and the cogging torque can be further improved.

Further, in the present embodiment, the third groove portion 23c is formed at the boundary portion B between the magnetic pole portion 14p of the N pole and the magnetic pole portion 14p of the S pole adjacent to each other in the circumferential direction. As a result, the cogging torque generated due to the switching of the magnetic poles of the rotor 14 is increased.

Further, the angle θ indicating the formation positions of the first and second groove portions 23a and 23b with respect to the magnetic pole center line Lp is in the range of 0 ° <θ≤ (360 ° / 2P) / 4, where P is the number of pole pairs of the rotor 14. Is set in. In the present embodiment, since the number of pole pairs of the rotor 14 is 4, the angle θ is set within the range of 0 ° <θ≤11.25 °. As a result, the first and second groove portions 23a and 23b are formed at positions closer to the magnetic pole center line Lp (within a range of 1/4 of the magnetic pole width with respect to the magnetic pole center line Lp).

Then, as described above, the magnetization orientation of the magnet 22 constituting the magnetic pole portion 14p is set so as to be inclined toward the magnetic pole center line Lp side toward the outer side in the radial direction. Therefore, the magnetic flux density around the first and second groove portions 23a and 23b in the rotor core 21 is increased, and as a result, the cogging torque generated by the first and second groove portions 23a and 23b can be further improved. In particular, the effect of improving the cogging torque becomes remarkable by increasing the magnetic flux density at the corners formed by the circumferential side surfaces of the first and second groove portions 23a and 23b and the outer peripheral surface of the rotor core 21.

Next, the effect of this embodiment will be described.
(1) The rotor 14 having a plurality of magnetic pole portions 14p set along the circumferential direction has a plurality of grooves formed on the outer peripheral surface of the rotor core 21 for increasing the cogging torque in the circumferential direction. The plurality of grooves are the third groove 23c as a boundary gap provided between the magnetic poles 14p adjacent to each other in the circumferential direction, the number of poles of the rotor 14 and the number of slots of the stator 12 in the magnetic pole 14p. It is configured to include the first and second groove portions 23a and 23b as the in-pole gap portions provided at positions corresponding to the period φ of the cogging torque obtained from the above.

According to this configuration, both the cogging torque generated by the third groove 23c as the boundary gap and the cogging torque generated by the first and second groove 23a and 23b as the inner gap can be used to switch the magnetic poles of the rotor 14. It can be superimposed on the basic cogging torque generated due to this, and as a result, the cogging torque can be improved.

(2) The first to third groove portions 23a, 23b, and 23c have the same shape as seen from the axial direction. As a result, the cogging torque can be suitably improved by the first to third groove portions 23a, 23b, 23c.

(3) The magnetization orientation of the magnet 22 constituting the magnetic pole portion 14p is set so as to be inclined toward the magnetic pole center line Lp side toward the stator 12 side (in the present embodiment, the outer side in the radial direction). According to this configuration, the magnetic flux of the magnet 22 can be suitably concentrated on the first and second groove portions 23a and 23b, and as a result, the cogging torque can be further improved.

(4) The rotor 14 is an embedded magnet type rotor in which the magnet 22 constituting the magnetic pole portion 14p is embedded in the rotor core 21, and the first to third groove portions 23a, 23b, 23c are on the outer peripheral surface of the rotor core 21. It is formed. According to this configuration, the cogging torque can be improved in the embedded magnet type rotor 14. Further, in the case of the embedded magnet type, since the first to third groove portions 23a, 23b, 23c can be formed on the outer peripheral surface of the rotor core 21, the first to third groove portions 23a, 23b, 23c can be easily formed. can.

The above embodiment may be changed as follows.
As shown in FIG. 3, the axially visible shape of the magnet 22 constituting the magnetic pole portion 14p may be rectangular. The magnet 22 shown in the figure has a flat plate shape, and its plate surface is provided so as to be orthogonal to the magnetic pole center line Lp. Further, the magnetization orientation of the magnet 22 is set to be parallel to the direction orthogonal to the plate surface (the direction along the magnetic pole center line Lp). Even with such a configuration, the same effects as those of the above-described embodiments (1), (2), and (4) can be obtained.

The number of magnets 22 provided in one magnetic pole portion 14p in the above embodiment is an example, and a plurality of magnets may be provided in each magnetic pole portion 14p.
For example, in the configuration shown in FIG. 4, each magnetic pole portion 14p has two magnets 31 embedded in the rotor core 21 so as to be arranged in the radial direction. Each magnet 31 has an arc shape that is convex inward in the radial direction in the axial direction. Further, the magnetization orientation of each magnet 31 is set so as to be inclined toward the circumferential center line (magnetic pole center line Lp) of the corresponding magnetic pole portions 14p toward the outer side in the radial direction (stator 12 side). Even with such a configuration, substantially the same effect as that of the above embodiment can be obtained.

Further, for example, in the configuration shown in FIG. 5, each magnetic pole portion 14p includes two magnets 41 embedded in the rotor core 21 so as to be arranged in the circumferential direction. Each magnet 41 has a flat plate shape, and the two magnets 41 at each magnetic pole portion 14p are arranged in a substantially V shape extending to the outer peripheral side in the axial direction. Further, the two magnets 41 are provided line-symmetrically with respect to the magnetic pole center line Lp. Further, each magnet 41 in the magnetic pole portion 14p of the N pole is magnetized so that the N pole appears on the surfaces facing each other (the surface on the magnetic pole center side) so that the outer peripheral side of the magnetic pole portion 14p becomes the N pole. Further, each magnet 41 in the magnetic pole portion 14p of the S pole is magnetized so that the S pole appears on the surfaces facing each other (the surface on the magnetic pole center side) so that the outer peripheral side of the magnetic pole portion 14p becomes the S pole. Further, the magnetization orientation of the two magnets 41 of the magnetic pole portion 14p is set so as to be inclined toward the magnetic pole center line Lp side toward the outer side in the radial direction (stator 12 side).

Even with such a configuration, substantially the same effect as that of the above embodiment can be obtained. Further, since the two magnets 41 are embedded so as to form a substantially V shape that expands radially outward in the axial direction, the rotor core volume on the outer peripheral side of the magnet 41 (the magnet between the two magnets 41 arranged in a V shape). It is possible to increase the volume of the portion including the inter-core portion 42). As a result, the reluctance torque can be increased, which can contribute to increasing the torque of the motor 10.

-In the above embodiment, the rotor 14 is an embedded magnet type (IPM type), but the present invention is not limited to this, and a surface magnet type (SPM type) may be used.
For example, in the configuration shown in FIG. 6, a cylindrical magnet 51 is provided on the outer peripheral surface of the rotor core 21. The outer peripheral surface of the magnet 51 has a circular shape centered on the axis L of the rotating shaft 13. The magnet 51 has a plurality of (eight in the figure) magnetic pole portions 14p that alternately have different poles in the circumferential direction. Further, the magnet 51 has a polar anisotropic orientation. That is, the magnetization orientation of the magnet 51 is radially inside from the outer peripheral surface of the magnetic pole portion 14p of the S pole toward the outer peripheral surface of the magnetic pole portion 14p of the adjacent N pole, as schematically shown by an arrow in FIG. Is set to a curved orientation so that is convex. Further, the magnetization orientation of the magnet 51 is set so as to be directed toward one point (magnetic flux concentration point F) on the extension line of the magnetic pole center line Lp toward the stator 12 side (outward in the radial direction) at each magnetic pole portion 14p. .. Then, on the outer peripheral surface of the magnet 51, first and second groove portions 52a and 52b as polar inner gap portions provided at the same positions as those in the above embodiment and third groove portions 52c as boundary gap portions are formed. Has been done.

Even with the configuration as shown in the figure, the same effects as those of the above-described embodiments (1), (2), and (3) can be obtained. The magnetization orientation of the magnet 51 is not limited to the polar anisotropic orientation, and may be a radial orientation or a parallel orientation.

The number of poles of the rotor 14 and the number of slots of the stator 12 in the above embodiment are examples and can be changed as appropriate. For example, the number of poles of the rotor 14 and the number of slots may be appropriately changed so that the relationship between the number of poles of the rotor 14 and the number of slots is 2n: 3n (where n is a natural number). The relationship between the number of poles of the rotor 14 and the number of slots does not necessarily have to be 2n: 3n. For example, the relationship between the number of poles of the rotor 14 and the number of slots is configured to be 10:12, 14:12, or the like. May be good.

-In the above embodiment, the first to third groove portions 23a, 23b, 23c are formed from one end to the other end of the rotor core 21 in the axial direction, but the present invention is not limited to this, and the groove portions 23a, 23b, and 23c are not limited to this. It may be formed with a length up to the middle portion.

-In the above embodiment, the first to third groove portions 23a, 23b, 23c have an arcuate cross section, but in addition to this, for example, a quadrangular cross section (U-shaped cross section) or a triangular cross section may be used.
-In the above embodiment, the first to third groove portions 23a, 23b, 23c formed on the outer peripheral surface of the rotor core 21 are the gap portions for increasing the cogging torque, but the present invention is not particularly limited to this. For example, even if the hole penetrating the rotor core 21 in the axial direction is formed as a gap portion (that is, a configuration in which the opening ends of the groove portions 23a, 23b, 23c are closed in the radial direction), the same effect as that of the above embodiment is obtained. Can be obtained.

-In the above embodiment, the number of in-pole voids (first and second groove 23a, 23b) in each magnetic pole portion 14p is an example and can be changed as appropriate. For example, either one of the first and second groove portions 23a and 23b may be omitted. Further, depending on the number of poles and the number of slots of the rotor 14, it is possible to provide three or more voids in the poles.

In the above embodiment, the rotor 14 is applied to the inner rotor type motor 10 arranged on the inner peripheral side of the stator 12, but the present invention is not particularly limited to this, and the outer rotor type motor 10 in which the rotor is arranged on the outer peripheral side of the stator 12 is applied. It may be applied to a motor. Further, it may be applied to an axial gap type motor in which the rotor 14 and the stator 12 face each other in the axial direction.

-In the above embodiment, it is applied to a brushless motor, but the present invention is not limited to this, and for example, it may be applied to a brushed motor.
-The above-described embodiment and each modification may be combined as appropriate.

10 ... motor, 12 ... stator, 14 ... rotor, 14p ... magnetic pole, 21 ... rotor core, 22 ... magnet, 23a ... first groove (intrapole gap), 23b ... second groove (intrapole gap), 23c ... Third groove portion (boundary gap portion), 31, 41, 51 ... Magnet, B ... Boundary portion, Lp ... Magnetic pole center line (circumferential center line of magnetic pole portion).

Claims (4)

With the stator
A rotor having a plurality of magnetic pole portions set along the circumferential direction on a surface facing the stator and having a plurality of gap portions partially provided in the circumferential direction for increasing cogging torque is provided.
The plurality of gaps have a cycle of cogging torque obtained from the boundary gaps provided between the magnetic poles adjacent to each other in the circumferential direction, the number of poles of the rotor and the number of slots of the stator in the magnetic poles. It is configured to include an intrapole void provided at a corresponding position.
A motor characterized in that the boundary gap portion and the inner pole gap portion have the same shape when viewed from the axial direction. In the motor according to claim 1,
A motor characterized in that the magnetization orientation of the magnets constituting the magnetic pole portion is set so as to be inclined toward the circumferential center line side of the magnetic pole portion toward the stator side. In the motor according to claim 1 or 2.
The rotor is an embedded magnet type rotor in which a magnet constituting the magnetic pole portion is embedded in a rotor core.
A motor characterized in that each of the boundary gap portion and the inner pole gap portion is formed in the rotor core. In the motor according to claim 1 or 2.
The rotor is a surface magnet type rotor in which magnets constituting the magnetic pole portion are provided on the surface of the rotor core.
A motor characterized in that each of the boundary gap portion and the inner pole gap portion is formed on the magnet.

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